EPA 402-R-14-011
www.epa.gov/narel
September 2014
Validation of
Rapid Radiochemical Method for
Total Radiostrontium (Sr-90) in
Brick Samples
for Environmental Remediation Following
Radiological Incidents
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Radiation and Indoor Air
National Analytical Radiation Environmental Laboratory
Montgomery, AL 36115
Office of Research and Development National
Homeland Security Research Center
Cincinnati, OH 45268
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
This report was prepared for the National Analytical Radiation Environmental Laboratory of the Office of
Radiation and Indoor Air and the National Homeland Security Research Center of the Office of Research
and Development, United States Environmental Protection Agency (EPA). It was prepared by
Environmental Management Support, Inc., of Silver Spring, Maryland, under contract EP-W-13-016, Task
Order 0014, managed by Dan Askren. This document has been reviewed in accordance with EPA policy
and approved for publication. Note that approval does not signify that the contents necessarily reflect the
views of the Agency. Mention of trade names, products, or services does not convey EPA approval,
endorsement, or recommendation.
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
CONTENTS
Acronyms, Abbreviations, Units, and Symbols iii
Radiometric and General Unit Conversions v
1. Introduction 1
2. Radioanalytical Methods 2
3. Method Validation Process Summary 2
4. Participating Laboratory 3
5. Measurement Quality Objectives 4
6. Method Validation Plan 4
6.1 Method Uncertainty 5
6.2 Detection Capability 5
6.3 Method Bias 5
6.4 Analyte Concentration Range 7
6.5 Method Specificity 7
6.6 Method Ruggedness 8
7. Techniques Used to Evaluate the Measurement Quality Objectives for the Rapid Methods
Development Project 8
7.1 Required Method Uncertainty 8
7.2 Required Minimum Detectable Concentration 9
8. Evaluation of Experimental Results 10
8.1 Summary of the Combined Rapid 90Sr - Brick Method 10
8.2 Required Method Uncertainty 10
8.3 Required Minimum Detectable Concentration 12
8.4 Evaluation of the Absolute and Relative Bias 14
8.5 Method Ruggedness and Specificity 15
9. Timeline to Complete aBatch of Samples 16
10. Reported Modifications and Recommendations 16
11. Summary and Conclusions 18
12. References 19
Attachment I: Estimated Elapsed Times 20
Attachment II: Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices
Prior to Americium, Plutonium, Strontium, Radium, and Uranium Analyses for
Environmental Remediation Following Radiological Incidents 21
Appendix: Rapid Technique for Milling and Homogenizing Concrete and Brick Samples
42
Attachment III: Rapid Radiochemical Method for Total Radiostrontium (Sr-90) in Building
Materials for Environmental Remediation Following Radiological Incidents 51
Appendix A: Method and Calculations for Detector Calibration 70
Appendix B: Calculations for Isotopic 89Sr and 90Sr Results 77
Attachment IV: Composition of Brick for Spiking in this Study 81
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Figure
Figure 1 - Sr Yields for Method Based on Measurement of Sr(NC>3)2 16
Tables
Table 1 - Sr-90 Method Validation Test Concentrations and Results 4
Table 2 - Sample Identification and Test Concentration Level for Evaluating the Required
Minimum Detectable Concentration 5
TableS -MARLAP Level C Acceptance Criteria 9
Table 4A - Sr-90 Analytical Results for Required Method Uncertainty Evaluation 11
Table 4B - Experimental Standard Deviation of the Five PT Samples by Test Level 12
Table 5 -Reported 90Sr Concentration Blank Brick Samples 13
Table 6 - Reported Results for Samples Containing 90Sr at the As-Tested MDC Value (0.4040
PCi/g) ... 14
Table 7 - Absolute and Relative Bias Evaluation of the Combined Rapid Sr - Brick Method. 15
Table 8 - Summary of Sr-90 Gravimetric % Yield Results for Test and Quality Control Samples
15
September 2014 ii
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Acronyms, Abbreviations, Units, and Symbols
AAL analytical action level
ACS American Chemical Society
APS analytical protocol specification
Bq becquerel
CZ/NC critical net concentration
CSU combined standard uncertainty
Ci curie
cpm counts per minute
cps counts per second
d day
DL discrimination level
dpm disintegrations per minute
dps disintegrations per second
DQO data quality obj ective
DRP discrete radioactive particle
E&Z Eckert & Ziegler Analytics
EPA U.S. Environmental Protection Agency
FRMAC Federal Radiological Monitoring and Assessment Center
ft foot
g gram
gal gallon
G-M Geiger-Muller [counter or probe]
GPC gas-flow proportional counter
Gy gray
h hour
ICP-AES inductively coupled plasma - atomic emission spectrometry
ID identifier/identification number
IND improvised nuclear device
IUPAC International Union of Pure and Applied Chemistry
kg kilogram (103 gram)
L liter
Lc critical level
LCS laboratory control sample
m meter
M molar
MARLAP Multi-Agency Radiological Laboratory Analytical Protocols Manual
MDA minimum detectable activity
MDC minimum detectable concentration
MeV mega electron volts (106 electron volts)
mg milligram (10"3grams)
min minute
mL milliliter (10"3 liter)
mm millimeter (10~3 meter)
MQO measurement quality obj ective
MS matrix spike
September 2014 iii
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
MVRM method validation reference material
|im micrometer (1CT6 m)
uCi microcurie (1CT6 curie)
NAREL EPA's National Analytical Radiation Environmental Laboratory, Montgomery,
AL
NHSRC EPA's National Homeland Security Research Center, Cincinnati, OH
NIST National Institute of Standards and Technology
ORD EPA Office of Research and Development
ORIA EPA Office of Radiation and Indoor Air
^MR required relative method uncertainty
pCi picocurie (1CT12 curie)
PPE personal protective equipment
ppm parts per million
PT proficiency test
QAPP quality assurance project plan
R Roentgen - unit of X and y radiation exposure in air
rad unit of radiation absorbed dose in any material
ROD radiological dispersal device
rem roentgen equivalent: man
s second
SI International System of Units
STS sample test source
Sv sievert
MMR required method uncertainty
WCS working calibration source
wt% percent by mass
y year
September 2014 iv
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Radiometric and General Unit Conversions
To Convert
years (y)
disintegrations per
second (dps)
Bq
Bq/kilogram (kg)
Bq/cubic meters
(m3)
Bq/m3
microcuries per
milliliter ((iCi/mL)
disintegrations per
minute (dpm)
cubic feet (ft3)
gallons (gal)
gray (Gy)
roentgen equivalent:
man (rem)
To
seconds (s)
minutes (min)
hours (h)
days (d)
becquerel (Bq)
picocurie (pCi)
pCi/gram (g)
pCi/g
Bq/L
pCi/g
(iCi
pCi
m3
liters (L)
rad
sievert (Sv)
Multiply by
3.16xl07
5.26xl05
8.77xl03
3.65xl02
1
27.0
2.70xl(T2
2.70xl(T2
1(T3
109
4.50xl(T7
4.50X10"1
2.83xlO~2
3.78
102
io-2
To Convert
s
min
h
d
Bq
pCi
pCi/g
pCi/g
Bq/L
pCi/g
pCi
m3
L
rad
Sv
To
y
dps
Bq
Bq/kg
Bq/m3
Bq/m3
(iCi/mL
dpm
ft3
gal
Gy
rem
Multiply by
3.17xl(T8
1.90xl(T6
1.14x10^
2.74xlO~3
1
3.70xl(T2
37.0
37.0
IO3
io-9
2.22
35.3
0.264
10~2
IO2
NOTE: Traditional units are used throughout this document instead of the International System of Units (SI).
Conversion to SI units will be aided by the unit conversions in this table.
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Acknowledgments
The U.S. Environmental Protection Agency's (EPA's) Office of Radiation and Indoor Air's
(ORIA) National Analytical Radiation Environmental Laboratory (NAREL), in conjunction with
the EPA Office of Research and Development's National Homeland Security Research Center
(NHSRC) developed this method validation report. Dr. John Griggs served as project lead.
Several individuals provided valuable support and input to this document throughout its
development. Special acknowledgment and appreciation are extended to Kathleen M. Hall, of
NHSRC.
We also wish to acknowledge the valuable suggestions provided by the staff of NAREL, who
conducted the method validation studies. Dr. Keith McCroan, of NAREL, provided significant
assistance with the equations used to calculate minimum detectable concentrations and critical
levels. Numerous other individuals, both inside and outside of EPA, provided comments and
criticisms of this method, and their suggestions contributed greatly to the quality, consistency,
and usefulness of the final method. Environmental Management Support, Inc. provided technical
support.
September 2014 vi
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
1. Introduction
Rapid methods need to be developed and validated for processing samples taken in response to a
radiological incident. In order to address this need, a project was initiated to develop rapid
methods that can be used to prioritize environmental sample processing as well as provide
quantitative results that meet measurement quality objectives (MQOs) that apply to the
intermediate and recovery phases of an incident.l Similar to the rapid method project initiated in
2007 for other radionuclides in water samples (EPA 2008), this rapid method development
project for a brick matrix addressed four different radionuclides in addition to 90Sr: 241Am, natU,
26Ra, and 239/240Pu. Each of these radionuclides will have separate method validation reports for
a brick matrix.
The method validation plan developed for the rapid methods project follows the guidance in
Method Validation Guide for Qualifying Methods Used by Radiological Laboratories
Participating in Incident Response Activities (EPA 2009), Validation and Peer Review of U.S.
Environmental Protection Agency Radiochemical Methods of Analysis (2006), and Chapter 6 of
Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP) (EPA 2004).
The method was evaluated according to MARLAP method validation "Level C." The method
formulated was preliminarily tested at a commercial laboratory and refinements to the method
made according to the feedback from the laboratory and the quality of the generated results. For
the method validation process, the laboratory analyzed several sets of blind proficiency test (PT)
samples according to specifications that meet established MQOs and guidance outlined in
Radiological Sample Analysis Guide for Radiological Incidents - Radionuclides in Soil (EPA
2012). The MQO specification for the required method uncertainty of 0.32 pCi/g was based on a
90Sr brick concentration similar to the MC
limit for a 50-year exposure of 2.4 pCi/g.
90Sr brick concentration similar to the MQO for the soil matrix, i.e., at approximately 1 x 10 5 risk
This report provides a summary of the results of the method validation process for a combination
of two methods: Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices
Prior to Americium, Plutonium, Strontium, Radium, and Uranium Analyses for Environmental
Remediation Following Radiological Incidents (Attachment II) and Rapid Radiochemical
Method for Total Radiostrontium (Sr-90) in Building Materials for Environmental Remediation
Following Radiological Incidents (Attachment III). In this document, the combined methods are
referred to as "combined rapid 90Sr - Brick method." The method validation process is applied to
the fusion dissolution of soil and building material using sodium hydroxide and the subsequent
separation and quantitative analysis of 90Srusing a calibrated gas proportional counter to detect
on on
the beta particles of Sr (pmean = 0.547 million electron volts [MeV] and Y (pmean = 0.934
MeV). The chemical yield of each sample processed was determined by gravimetric means of a
Sr(NO3)2precipitate. The laboratory's complete report, including a case narrative and a
compilation of the reported results for this study, can be obtained by contacting EPA's National
Analytical Radiation Environmental Laboratory (NAREL)
(http://www.epa.gov/narel/contactus.html).
1 ORIA and the Office of Research and Development jointly undertook the rapid methods development projects. The
MQOs were derived from Protective Action Guides determined by ORIA.
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
2. Radioanalytical Methods
The combined rapid 90Sr - Brick method was written in a format consistent with EPA guidance
and conventions. The rapid method was formulated to optimize analytical throughput for sample
preparation, fusion process, chemical processing and radiation detection. The final step of the
fusion method prepares the sample for separation and analysis by the Rapid Radiochemical
Method for Total Radiostrontium (Sr-90) in Building Materials for Environmental Remediation
Following Radiological Incidents. Specifications for sample processing were incorporated into
the rapid method. These specifications are reflected in the scope and application and in the body
of the methods. The specifications include the use of a gravimetric yield monitor and the
required method uncertainty. Known interferences are addressed in Section 4 of the attached
method (Attachment III). For this validation study, the laboratory used a 100-minute counting
time for the three test level samples as well as for the required minimum detectable concentration
(MDC) samples. A 1.5-g sample of the brick matrix was processed (see Attachment IV for the
chemical composition of the brick matrix). A summary of the rapid method is presented in
Section 8.1 prior to presenting the experimental results of the method validation analyses.
The final combined rapid 90Sr - Brick method is included as Attachments II and III to this report.
Although this final method is a departure from the originally tested method, the incorporated
revisions are significant improvements and do not change the general methodology. The
validation process was performed using the final combined method in the attachments.
3. Method Validation Process Summary
on
The method validation plan for the combined rapid Sr - Brick method follows the guidance
provided in Method Validation Guide for Qualifying Methods Used by Radiological
Laboratories Participating in Incident Response Activities (EPA 2009), Validation and Peer
Review of U.S. Environmental Protection Agency Radiochemical Methods of Analysis (EPA
2006), and Chapter 6 of MARLAP (2004). This method validation process was conducted under
the generic Quality Assurance Project Plan Validation of Rapid Radiochemical Methods for
Radionuclides Listed in EPA 's Standardized Analytical Methods (SAM) for Use During
Homeland Security Events (EPA 2011). The combined rapid 90Sr - Brick method is considered a
"modified application" of an existing method (EPA 2004, Section 6.6.3.5). Therefore, the
method was evaluated according to MARLAP method validation "Level C." More specifically,
the method was validated against acceptance criteria for the required method uncertainty (Z/MR) at
a specified analytical action level (AAL) concentration and the required MDC. In addition,
analytical results were evaluated for statistical bias, absolute bias for blank samples and relative
bias at each of the three test level radionuclide activities. The gravimetric yield of the method
was also evaluated as a characteristic of method ruggedness.
The method validation process was divided into four phases:
1. Phase I
a. Laboratory familiarization with the method concept.
b. Set-up of the laboratory and acquisition of reagents, standards and preparation of
in-house performance test (PT) samples.
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
c. Perform preliminary tests of the rapid fusion method.
d. Make changes to improve the method based on the preliminary tests.
2. Phase II
a. Conduct blank sample analyses to assess the method critical level concentration.
b. Conduct method validation for required method uncertainty.
3. Phase III
a. Conduct verification of the required MDC.
4. Phase IV
a. Report results.
b. Laboratory writes report to describe the process and narratives on the method.
c. Review and comment on method.
d. Environmental Management Support, Inc., writes method validation report, which
is reviewed by laboratory.
During Phases I, II, and III, the laboratory processed and evaluated batch quality control samples
according to their laboratory quality manual, including an analytical reagent blank, laboratory
control sample (LCS) and a sample duplicate.
The objective of the first (preliminary) phase was to familiarize the laboratory with the
formulated rapid method and then gain hands-on experience in using the rapid method to identify
areas that might require optimization. During this phase, the laboratory processed samples of
blank brick material, and blank brick that was spiked in-house with 90Sr - activities consistent
with evaluating the required method uncertainty at the AAL and the required MDC (see "Sr-90
Method Validation Test Concentrations and Results," Table 1). The analysis of the blank and
laboratory spiked brick samples used in Phase I provided insight into the feasibility of the
proposed method. Based on information and experience gained during Phase I practice runs, the
combined rapid 90Sr - Brick method was optimized without compromising data collected during
the validation process in Phases II and III. The method was not subjected to a "formal" method
validation evaluation process in Phase I.
During Phases II and III of the method validation process, the laboratory analyzed PT samples
(consisting of method validation reference materials [MVRM]) provided by an external, National
Institute of Standards and Technology (NIST)-traceable source manufacturer (Eckert & Ziegler
Analytics (E&Z), Atlanta, GA). The MVRM was pulverized brick prepared by E&Z. The macro-
analysis of brick material is provided in Attachment IV. The laboratory was instructed to analyze
specific blind PT samples having concentration levels consistent with validation test levels for
the required method uncertainty and the required MDC. The test levels of the PT samples are
listed in Tables 1 and 2. Following completion of the method validation studies, comments from
the laboratory were evaluated, and the method revised to conform to the documented "as-tested"
conditions in Phases II and III. Thus the validation data presented in this report reflect the
combined final method included in the attachments to this document.
4. Participating Laboratory
on
NAREL validated the combined rapid Sr - Brick method using chemically characterized brick
samples spiked with NIST-traceable 90Sr source. NAREL has demonstrated satisfactory
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
performance in national radioanalytical performance proficiency programs for radionuclides in
water and other matrices.
5. Measurement Quality Objectives
The combined rapid 90Sr - Brick method was developed to meet pre-established MQOs for the
rapid methods project. The selected MQOs included the radionuclide concentration range, the
required method uncertainty at a specified radionuclide concentration (e.g., AAL), and the required
on
MDC. The required relative method uncertainty (cpMn) for the combined rapid Sr - Brick method
was set at 13%2 at a targeted brick AAL equal to 2.41 pCi/g, which is approximately the 1 * 1CT5
risk concentration for a 50-year exposure period for a soil matrix. This soil concentration value is
based on guidance found in the Federal Radiological Monitoring and Assessment Center
O Q/\
(FRMAC). The target MDC for the combined rapid Sr - Brick method for the brick matrix was
0.40 pCi/g (-17% of the AAL). However, the PT sample supplier generated method validation and
MDC samples having 90Sr concentrations slightly different than the targeted values. Table 1
summarizes the targeted MQOs for the 90Sr method validation process and the study test values
based on the actual spiked concentrations of the PT samples. It should be noted that the method
was validated for a brick matrix having a typical chemical composition and four additional
radionuclides in concentrations corresponding to a 10~5 risk AAL for soil. The brick concentrations
for the four other radionuclides were 241Am (1.570 pCi/g), 238U (12.35 pCi/), 226Ra (4.755 pCi/g),
9^Q
and Pu (1.890 pCi/g). The PT sample supplier provided test data for 10, 1-gram samples that
documents the spread in the spike in the samples as a 1.59% standard deviation of the distribution
of results.
Table 1 - Sr-90 Method Validation Test Concentrations and Results
MDC
!/2 x AAL
AAL
3 x AAL
Target
Value
0.40
1.21
2.41
7.23
Known Value,
pCi/g(A = l)
0.4040 +0.0093
1.210 + 0.028
2.440 + 0.063
7.28 + 0.16
Average
Measured
Value
0.51
1.160
2.17
6.83
Required
Method
Uncertainty,
MMR
—
0.32
0.32
0.95 [1]
Standard Deviation
PI
0.19
0.073
0.23
0.43
[1] The value of 0.95 pCi/g is the absolute value for the required method uncertainty and represents 13% of 7.28
pCi/g.
[2] Calculated standard deviation of the 10 and 5 measurement results for the MDC and Test Level samples,
respectively.
6. Method Validation Plan
on
The combined rapid Sr - Brick method was evaluated for the six important performance
characteristics for radioanalytical methods specified in Quality Assurance Project Plan
2 Type I and II decision error rates were set at zi_a= 0.01 and z\-$= 0.05. The required method uncertainty is
calculated using the formula, MMR = (AAL-DL)/[zi_a + ZI_P] where the analytical action level (AAL) is as noted
above and the discrimination level (DL) is !/2 the AAL.
3 Federal Radiological Monitoring and Assessment Center. Appendix C of the FRMAC Manual (FRMAC 2010) or
calculated using Turbo. FRMAC 2010 available from Sandia National Laboratory.
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Validation of Rapid Radiochemical Methods for Radionuclides Listed in EPA 's Standardized
Analytical Methods (SAM) for Use During Homeland Security Events (EPA 2011). These
characteristics include method uncertainty, detection capability, bias, analyte activity range,
method ruggedness, and method specificity. A summary of the manner in which these
performance characteristics were evaluated is presented below. The chemical yield of the
method, an important characteristic for method ruggedness, was also evaluated.
6.1 Method Uncertainty
The method uncertainty of the combined rapid 90Sr - Brick method was evaluated at the AAL
concentration (2.44 pCi/g known value) specified in the MQOs presented in Table 1. In
accordance with MARLAP method validation "Level C," this is a new application and was
evaluated at each of three test concentration levels, one of which was the AAL equivalent
activity concentration to approximately IxlCT5 risk for a soil matrix. The laboratory analyzed
five replicate external MVRM PT samples containing 90Sr activities at approximately one-half
the AAL, the AAL and three times the AAL. The method was evaluated against the required
method uncertainty, MMR= 0.32 pCi/g, at and below the AAL, and against the relative required
method uncertainty, (pmL= 13% of the known test value, above the AAL. The test level
concentrations analyzed are listed in Table 1 "Known Value."
6.2 Detection Capability
The detection capability of the combined rapid 90Sr - Brick method was evaluated to meet a
required MDC of 0.4040 pCi/g as specified in Table 2. In accordance with the guidance provided
in Method Validation Guide for Radiological Laboratories Participating in Incident Response
Activities (EPA 2009), the laboratory estimated the critical net concentration based on the results
of seven reagent blank samples. Results from 10 replicate samples having an "as tested"
concentration at the required MDC were compared to the critical net concentration to determine
method detection capability.
Table 2 - Sample Identification and Test Concentration Level for Evaluating the Required
Minimum Detectable Concentration
Test Sample Designation
MA1-MA10
(Brick MDC samples)
BMDC1-BMDC7
(Brick2 matrix blanks)
Number of
Samples
Prepared
10
7
Nuclide
90Sr
90Sr
MDC Known
Value
(pCi/g)
0.4040 + 0.0093
(*=1)
—
Mean Measured
Concentration (pCi/g)
[i]
0.51+0.19(^=1)
0.119 + 0.077
[1] Mean and standard deviation of 10 spiked samples and 7 blanks. The stated combined standard uncertainty
(CSU) includes the uncertainty in the 90Sr reference standard used to prepare the samples. The concentration of
90Sr in the blank brick sample matrix was not statistically different than zero. No limit for detection was
provided.
[2] Blank brick matrix supplied by Eckert & Ziegler Analytics, Atlanta, Georgia.
6.3 Method Bias
Two types of method bias were evaluated, absolute and relative.
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Absolute Bias
Absolute bias was determined as a method performance parameter. The results from the seven
blank brick samples for the required MDC evaluation were assessed for absolute bias according
to the protocol and equation presented in the Method Validation Guide for Qualifying Methods
Used by Radiological Laboratories Participating in Incident Response Activities (EPA 2009).
There was no acceptance limit for bias established for the method in the validation process.
The following protocol was used to test the combined rapid 90Sr - Brick method for absolute
bias:
1. Calculate the mean (X) and estimated standard deviation (sx) for "N" (at least seven) blank
sample net results.
2. Use the equation below to calculate the T value:
\X\
T= ' I (1)
1. An absolute bias in the measurement process is indicated if
T>tl_al2(N-\) (2)
where 11-0/2 (N-i) represents the (1 - a/2)-quantile of the ^-distribution with N-l degrees of
freedom. For seven blanks, an absolute bias is identified at a significance level of 0.05, when
|T|> 2.447.
Relative Bias
The results from the five external PT brick samples for each of the three test levels were
evaluated for relative bias according to the protocol and equation presented in the Method
Validation Requirements for Qualifying Methods Used by Radioanalytical Laboratories
Participating in Incident Response Activities. No acceptable relative bias limit was specified for
this method validation process.
The following protocol was used to test the combined rapid 90Sr - Brick method for relative bias:
1. Calculate the mean (X) and estimated standard deviation (sx) of the replicate results for each
method validation test level.
2. Use the equation below to calculate the |T| value
X-K
T =
(3)
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
where:
X is the average measured value
sx is the experimental standard deviation of the measured values
N is the number of replicates
K is the reference value
u(K) is the standard uncertainty of the reference value
A relative bias in the measurement process is indicated if
IT
>t
eff) (3 a)
The number of effective degrees of freedom for the T statistic is calculated as follows:
calculated by the equation generally is not an integer so veff should be truncated (rounded
down) to an integer. Then, given the significance level, 0.05, the critical value for "|T|" is defined
to be ?i-o/2(vefi), the (1 - a/2)-quantile of the ^-distribution with veff degrees of freedom (see
MARLAP Appendix G, Table G.2).
6.4 Analyte Concentration Range
___ on
The combined rapid Sr - Brick method was evaluated for the required method uncertainty at
three test level activities. The five replicate PT samples from each test level concentration were
analyzed. The proposed (target) and "as tested" (known) test level activities are presented in
Table 1 . Note that the final test concentration values for the PT samples varied from the
proposed test levels but that these values were well within the sample preparation specifications
provided to the PT sample provider.
6.5 Method Specificity
The brick sample is fused with sodium hydroxide in zirconium crucibles for -15 minutes at 600
°C in a furnace. The fused material is dissolved using water and transferred to a centrifuge tube.
A preconcentration step with calcium phosphate enhanced with iron hydroxide is used to remove
the Sr from the alkaline matrix. The precipitate is dissolved in dilute acid and a calcium fluoride
precipitation is performed to further remove brick matrix components such as silicates that can
adversely affect column flow. The precipitate is dissolved in strong nitric acid with boric acid
and aluminum present and the solution is passed through a Sr Resin extraction chromatography
cartridges that selectively retains strontium while allowing most interfering radionuclides and
matrix constituents to pass through to waste. Strontium is eluted from the column with 0.05 M
HNOs and taken to dryness in a tared, stainless steel planchet. The planchet containing the
strontium nitrate precipitate is weighed to determine the strontium yield.
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
6.6 Method Ruggedness
The sodium hydroxide fusion has been used successfully on U.S. Department of Energy's Mixed
Analyte Performance Evaluation Program soil samples containing refractory actinides and
strontium. The method is rapid and simple yet very rugged. The calcium fluoride step with HF
present removes silicates, which tend to clog the resin cartridges. The sample size was limited to
1.5 g of brick to minimize any undissolved solids in the column load solutions. A calcium
phosphate co-precipitation method was used instead of calcium carbonate since complete
dissolution of the final precipitate in the column load solution could not be achieved with
calcium carbonate.
The method validation reference material samples contained other beta emitting radionuclides (U
and 226Ra decay products).
7. Techniques Used to Evaluate the Measurement Quality Objectives for the
Rapid Methods Development Project
A general description of the specifications and techniques used to evaluate the required method
uncertainty, required MDC and bias was presented in Section 6. The detailed method evaluation
process for each MQO, the bias and the radiochemical yield is presented in this section.
7.1 Required Method Uncertainty
on
The combined rapid Sr - Brick method was evaluated following the guidance presented for
"Level C Method Validation: Adapted, Newly Developed Methods, Including Rapid Methods"
in Method Validation Guide for Qualifying Methods Used by Radiological Laboratories
Participating in Incident Response Activities (EPA 2009) and Chapter 6 of Multi-Agency
Radiological Laboratory Analytical Protocols Manual (EPA 2004).
MARLAP "Level C" method validation requires the laboratory to conduct a method validation
study wherein five replicate samples from each of the three concentration levels are analyzed
according to the method. The concentration test levels analyzed are listed in Table 1. For
Qj-\
validation "Level C," externally prepared PT samples consisting of NIST-traceable Sr were
used to spike MVRM. In order to determine if the proposed method met the rapid methods
development project MQO requirements for the required method uncertainty (WMR = 0.32 pCi/g),
each external PT sample result was compared with the method uncertainty acceptance criteria
listed in the table below. The acceptance criteria stated in Table 3 for "Level C" validation
stipulate that, for each test sample analyzed, the measured value had to be within ± 2.9 Z/MR
(required method uncertainty) for test level activities at or less than the AAL, or ± 2.9 ^MR
(required relative method uncertainty) for test level activities above the AAL.
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Table 3 - MARLAP Level C Acceptance Criteria
MARLAP
Validation
Level
C
Application
New
Application
Sample
Type111
Method
Validation
Reference
Materials
Acceptance
Criteria [2]
Measured value
within ± 2.9 MMRor
± 2.9 cpMR of
validation value
Number of
Test Levels
3
Number of
Replicates
5
Total Number
of
Analyses
15
[1] "Method Validation Reference Materials" is not a requirement of MARLAP for these test levels. However, in
order to assure laboratory independence in the method validation process, a NIST-traceable source
manufacturer was contracted to produce the testing materials for Phases II and III of the project.
[2] The measured value must be within ± 2.9 UMR for test level concentrations at or less than the AAL and within ±
2.9 0yR for a test level concentration above the AAL. It was assumed that the uncertainty of a test sample
concentration will be negligible compared to the method uncertainty acceptance criteria and was not
incorporated in the acceptance criteria.
7.2 Required Minimum Detectable Concentration
The analytical results reported for the PT samples having a 90Sr concentration at the tested MDC
of 0.4040 pCi/g were evaluated according to Sections 5.5.1 and 5.5.2 of Testing for the Required
MDC in Method Validation Guide for Qualifying Methods Used by Radiological Laboratories
Participating in Incident Response Activities (EPA 2009). NAREL analyzed the external PT
samples in accordance with the proposed rapid method.
Critical Net Concentration
In order to evaluate whether the combined method can meet the required MDC (0.4040 pCi/g),
the critical net concentration, as determined from the results of analytical blanks, must be
calculated. The critical net concentration with a Type I error probability of a = 0.05, was
calculated using the following equation (consistent with MARLAP, Chapter 20, Equation 20.35):
'Blanks
(5)
where sBlanks is the standard deviation of the n blank-sample net results (corrected for instrument
background) in radionuclide concentration units of pCi/g, and t\-a(n-\) is the (1 - a)-quantile of
the ^-distribution with n-\ degrees of freedom (see MARLAP Table G.2 in Appendix G). For
this method validation study a Type I error rate of 0.05 was chosen.
For seven (minimum) blank results (six degrees of freedom) and a Type I error probability of
0.05, the previous equation reduces to:
CLNC(pCi) = 1.94xs
Blanks
(6)
The use of the above equations assumes that the method being evaluated has no bias.
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Verification of Required MDC
Each of the 10 analytical results reported for the PT samples having a concentration at the
required MDC for 90Sr (0.4040 pCi/g) was compared to the estimated critical net concentration
for the method. The following protocol was used to verify a method's capability to meet the
required method MDC for a radionuclide-matrix combination:
I. Analyze a minimum of seven matrix blank samples for the radionuclide.
II. From the blank sample net results, calculate the estimated Critical Net Concentration,
III. Analyze 10 replicate samples spiked at the required MDC.
IV. From the results of the 10 replicate samples spiked at the required MDC, determine the
number (Y) of sample results at or below the estimated C//NC-
V. If Y < 2, the method evaluated at the required MDC passes the test for the required MDC
specification.
VI. If Y > 2, the method evaluated at the required MDC fails the test for the required MDC
specification.
8. Evaluation of Experimental Results
Only the experimental results for Phases II and III of the method validation process are reported
and evaluated in this study. Information presented in this section will include results for Sections
6 and 7. The 90Sr analytical results were evaluated for the required method uncertainty, required
MDC and bias. In addition, the mean radiochemical yield for the method for Phases II and III is
reported to provide the method user the expected mean and range of this method performance
characteristic.
8.1 Summary of the Combined Rapid 90Sr - Brick Method
The brick sample is fused with sodium hydroxide, dissolved in water and preconcentrated using
calcium phosphate and calcium fluoride precipitations. The brick samples are analyzed
for 90Sr using the method for building materials (Rapid Radiochemical Method for Total
Radiostrontium (Sr-90) in Building Materials for Environmental Remediation Following
Radiological Incidents, Attachment III).
8.2 Required Method Uncertainty
___ on
Table 4A summarizes the Sr results for a 1 .5-g sample and the acceptability of each result
compared to the acceptance criteria presented in Section 7.1. The final sample test sources were
a SrNOs precipitate counted on a gas proportional counting system for 100 minutes that was
September 2014 10
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
capable of meeting a required method uncertainty of 0.32 pCi/g at and below the AAL of 2.440
pCi/g.
Table 4A - Sr-90 Analytical Results for Required Method Uncertainty Evaluation
Nuclide: Sr-90
Proposed Method:
Required Method Validation
Matrix: Brick AAL Tested: 2.440 pCi/g
Combined Rapid 90Sr - Brick Method
Level: MARLAP "C"
Required Method Uncertainty, WMP : 0.32 pCi/s at and below AAL; 13% above AAL
Acceptance Criteria:
Test Levels 1 and 2: 2.9 x MMR = ± 0.92 pCi/g of quoted known value of sample in test level
Test Level 3 : 2.9 x ^j^ = ± 37.7% of quoted known value of sample in test level (7.28 pCi/g)
Test Level 1
Sample
(Analytics
Batch SO-
Ul)
SOI
S02
S03
S04
SOS
pCi/g
Known
1.210
Uncertainty [1]
(pCi/g)
0.028
pCi/g
Measured
.26
.14
.19
.15
.06
csu [2]
(pCi/g)
0.14
0.14
0.15
0.14
0.14
Allowable
Range
(pCi/g)
0.29-2.1
Acceptable
Y/N
Y
Y
Y
Y
Y
Test Level 2
Sample
(Analytics
Batch SO-
U2)
SR6
SR7
SR8
SR9
SR10
pCi/g
Known
2.440
Uncertainty [1]
(pCi/g)
0.063
pCi/g
Measured
1.98
2.13
1.94
2.48
2.33
CSU [2]
(pCi/g)
0.15
0.16
0.15
0.18
0.17
Allowable
Range (pCi/g)
1.5- 3.4
Acceptable
Y/N
Y
Y
Y
Y
Y
September 2014
11
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Test Level 3
Sample
(Analytics
Batch SO-
US)
S14
S15
S16
S17
S18
pCi/g
Known
7.28
Uncertainty [11
(pCi/g)
0.16
pCi/g
Measured
7.20
6.81
6.24
6.61
7.30
csu [2]
(pCi/g)
0.27
0.26
0.24
0.25
0.27
Allowable Range
(pCi/g)
4.5-10
Acceptable
Y/N
Y
Y
Y
Y
Y
[1] Quoted uncertainty (k= 1) by the radioactive source manufacturer.
[2] Combined standard uncertainty (CSU), coverage factor k=l.
As a measure of the expected variability of results for a test level, the calculated standard
deviation of the five measurements of each test level is provided in Table 4B. The standard
deviation of the analytical results for a test level was much smaller than the required method
uncertainty.
Table 4B - Experimental Standard Deviation of the Five FT Samples by Test Level
Test Level
1
2(AAL)
3
Mean
Concentration
Measured
(pCi/g)
1.160
2.17
6.83
Standard Deviation of
Measurements
(pCi/g)
0.073
0.23
0.43 (6.3%)
Required Method
Uncertainty
(pCi/g)
0.32
0.32
0.95L1J(13%)
[1] This figure represents the absolute value of the required method uncertainty, calculated by multiplying the
known value of Test Level 3 (7.28 pCi/g) by the required relative method uncertainty.
8.3 Required Minimum Detectable Concentration
The combined rapid 90Sr - Brick method was validated for the required MDC using a 1.5 g
sample and a gas proportional counting time of 100 minutes.
on
Tables 5 and 6 summarize the Sr results and the acceptability of the method's performance
specified in Section 7.2 to meet the tested required MDC of 0.4040 pCi/g.
September 2014
12
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
90
Table 5 - Reported Sr Concentration Blank Brick Samples
Sample ID
S41
S42
S43
S44
S45
S46
S47
Mean [2]
Standard Deviation
Critical Net Concentration
(pCi/g)
Concentration (pCi/g)
0.24
0.11
0.069
0.058
0.21
0.106
0.042
0.119
0.077
0.15
CSU [1] (pCi/g)
0.11
0.10
0.088
0.097
0.10
0.085
0.084
[1] Combined standard uncertainty (CSU), k=l or coverage factor of 1.
[2] Mean and standard deviation were calculated before rounding.
Critical Net Concentration
The critical net concentration for the method under evaluation was calculated using Equation 6
from Section 7.2. Based on the results of the seven blanks (Table 5), the critical net
concentration for the combined method was determined to be 0.15 pCi/g.
RequiredMDC
A summary of the reported results for samples containing 90Sr at the required MDC is presented
in Table 6. The mean measured value and standard deviation of the ten 90Sr MDC test samples
were calculated as 0.51+ 0.19 pCi/g (A=l). Each result was compared to the critical net
concentration of 0.15 pCi/g. If the result was at or below the critical net concentration, a "Y"
qualifier was applied to the sample result; otherwise an "N" qualifier was applied. As presented
on
in the table, the number of Y qualifiers is < 2, so the combined rapid Sr - Brick method
evaluated passes the test for the required MDC specification (see Method Validation Guide for
Qualifying Methods Used by Radiological Laboratories Participating in Incident Response
Activities [EPA 2009] for a description of the test).
September 2014
13
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Table 6 - Reported Results for Samples Containing
(0.4040 pCi/g)
90
Sr at the As-Tested MDC Value
Sample ID
S30
S31
S32
S33
S34
S35
S36
S37
S38
S39
Mean P1
Standard Deviation of Results
Concentration
(pCi/g)
0.38
0.99
0.34
0.45
0.55
0.48
0.44
0.37
0.44
0.61
0.51
0.19
^-^NC
Acceptable maximum
values < CLNC (Y)
Number of results > CLNC
Number of results < CLNC
csu [1]
(pCi/g)
0.11
0.14
0.11
0.11
0.11
0.12
0.12
0.10
0.11
0.11
0.15 pCi/g
2
—
—
Evaluation
Test Result
< cr [3]
— *--LNC
N
N
N
N
N
N
N
N
N
N
—
—
—
10
0
PASS
[1] Combined standard uncertainty (CSU), coverage factor k=l.
[2] Mean and standard deviation were calculated before rounding.
[3] Critical net concentration.
Based on the validation study results, it may be concluded that the combined rapid 90Sr - Brick
method for 1.5 g sample and a 100-minute counting time is capable of meeting a required MDC
for 90Sr of 0.4040 pCi/g (the known value of the MDC PT sample).
8.4 Evaluation of the Absolute and Relative Bias
The 90Sr results for the seven blank brick samples (Table 5), 10 MDC samples (Table 6) and
the five replicate PT samples on the three test levels (Table 4A) were evaluated for absolute
and relative bias according to the equations presented in Section 6.3. The results and
interpretation of the evaluation are presented below in Table 7.
September 2014
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Table 7 - Absolute and Relative Bias Evaluation of the Combined Rapid Sr - Brick Method
Type of
Bias
Absolute
Relative
Relative
Relative
Relative
Test
Level
Blanks
MDC
1
2-
AAL
3
Known Value
± CSU (k=l)
(pCi/g) [1]
0.0000
0.4040 ±0.0093
1.210 ±0.028
2.440 ± 0.063
7.28 ±0.16
Mean of
Measurements
± Standard
Deviation pl
(pCi/g)
0.119 + 0.077
0.51 ±0.19
1.160 ±0.073
2.17 ±0.23
6.83 ±0.43
Difference
from
Known
0.1193
0.11
-0.050
-0.27
-0.45
Number of
Measurements/
Degrees of
Freedom
7/6
10/9
5/12
5/7
5/11
|T|
4.11
1.67
1.16
2.22
1.77
tdf
2.45
2.26
2.18
2.36
2.20
Bias
Yes/
No
Y
N
N
N
N
[1] The stated CSU includes the uncertainty in the Sr reference standard used to prepare the samples and the
standard deviation of the spiked test samples.
[2] Standard deviation of the measurements.
The results for the seven blank samples had a mean and standard deviation of 0.1193 + 0.077
pCi/g. A statistical analysis of the data indicated that there was an absolute bias for the blank
samples.
No relative bias was noted for the measurements performed on the 10 MDC or any of the method
uncertainty test levels. The mean concentration of 0.51 pCi/g for the 10 MDC test samples falls
within 0.106 pCi/g (or 26%) of the known value of 0.4040 pCi/g.
As determined by the paired-^ test described in section 7, no relative bias was indicated for any
of the method uncertainty test levels. The relative percent difference for each test level was:
• Test Level 1: -4.1%.
• Test Level 2: -11%.
• Test Level 3: -6.2%.
8.5 Method Ruggedness and Specificity
The results summarized in Table 8 represent the gravimetric yields for all three test levels,
blanks, laboratory control samples and MDC samples that were processed in accordance with the
final methods in Attachments II and III.
Table 8 - Summary of Sr-90 Gravimetric % Yield Results for
Test and Quality Control Samples
Number of Samples
Mean Gravimetric Yield
Standard Deviation of Distribution (la)
Median
Minimum Value
5th Percentile
95th Percentile
Maximum Value
48
85.2
6.8
83.5
73.8
77.1
98.9
99.9
September 2014
15
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
The yields for samples evaluated using this method are shown on Figure 1. The gravimetric
yields were very good, with an average yield of 85.2% ± 6.8% (1 standard deviation). The lowest
chemical yield was -73.8% while 90% of the yields were between 77.1 and 98.9%. The high
on
chemical yields are an indication of the ruggedness of the combined Sr rapid method.
Strontium Gravimetric Yield
120.00
% 100.00
80.00
Y
j 60.00
G 40.00
I
d 20.00
0.00
10 20 30 40
Sample Number
50
60
Figure 1 - Sr Yields for Method Based on Measurement of Sr(NO3)2
9. Timeline to Complete a Batch of Samples
NAREL kept a timeline log on processing a batch of samples and associated internal quality
control samples. The total time to process a batch of samples, including counting of the samples
and data review/analysis, was approximately 7.5 to 8.5 hours, assuming a 1 to 2-hour count time.
NAREL's breakdown of the timeline by method-process step is presented in Attachment I (this
information is also presented in more detail in the method flow chart in Attachment III, Section
17.5).
10. Reported Modifications and Recommendations
NAREL performed the method validation and made one significant modification to the method
prior to analyzing samples for Phases II and III of the project. The selected modification
provided by NAREL is listed below.
The primary modification was to employ a calcium phosphate precipitation instead of calcium
carbonate since the calcium phosphate approach allowed the analysis of 1.5-g sample aliquants
with less dissolution problems in the column load solution.
The following changes were made in the procedure Rapid Method for Sodium Hydroxide Fusion
of Concrete and Brick Matrices Prior to Americium, Plutonium, Strontium, Radium, and
September 2014
16
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Uranium Analyses for Environmental Remediation Following Radiological Incidents
(Attachment II).
NOTE: The step numbers below may have changed in the post-validation method in Attachment II.
QO
1.1. Preconcentration of Sr from Hydroxide Matrix (Brick)
NOTE: The preconcentration steps for 90Sr in this section, using calcium phosphate instead of
calcium carbonate, can also be applied to concrete samples but this will have to be validated by
the laboratory. See Section 11.3 for steps validated for 90Sr in concrete samples.
1.1.1. Transfer each fused sample to a 225-mL centrifuge tube, rinse crucibles well
with water, and transfer rinses to each tube.
1.1.2. Dilute to approximately 150 mL with water.
1.1.3. Pipet2mL 1.25M Ca(NO3)2 into each tube.
1.1.4. Add 1 mL 50-mg/mL iron carrier into each tube.
1.1.5. Add 5 mL 3.2M (NH4)2HPO4 to each tube.
1.1.6. Cap tubes and mix well.
1.1.7. Centrifuge tubes for 5 minutes at 3500 rpm.
1.1.8. Pour off the supernate and discard to waste.
1.1.9. Add 1.5M HC1 to each tube to redissolve each sample in a total volume of
-60 mL.
1.1.10. Cap and shake each tube to dissolve solids as well as possible.
1.1.11. Dilute each tube to -170 mL with 0.01M HC1. Cap and mix.
1.1.12. Add 22 mL of concentrated HF into each tube. Cap and mix well.
1.1.13. Place tubes to set in an ice bath for -10 minutes to get the tubes very cold.
1.1.14. Centrifuge for -6 minutes at 3500 rpm.
1.1.15. Pour off supernate and discard to waste.
1.1.16. Pipet 5 mL of concentrated HNO3 and 5 mL of 3-M HNO3 - 0.25M boric
acid into each 225 mL tube to dissolve precipitate.
1.1.17. Cap and mix well. Transfer contents of the tube into a labeled 50-mL
centrifuge tube.
1.1.18. Pipet 5 mL of 3M HNOs and 5 mL of 2M aluminum nitrate into each tube,
cap tube and mix.
1.1.19. Transfer rinse solutions to 50 mL centrifuge tubes and mix well (shake or use
vortex stirrer).
1.1.20. Centrifuge the 50 mL tubes at 3500 rpm for 5 minutes to remove any traces
of solids.
1.1.21. Transfer solutions to labeled beakers or new 50 mL tubes for further
processing.
September 2014 17
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
1.1.22. If solids remain, add 5 mL 3M HNCb to each tube, cap and mix well,
centrifuge for 5 minutes and add the supernate to the sample solution.
Discard any residual solids.
1.1.23. Set aside for 90Sr analysis using Rapid Radiochemical Method for Total
Radiostrontium (Sr-90) In Building Materials for Environmental
Remediation Following Radiological Incidents (Reference 16.4)
11. Summary and Conclusions
The combined rapid 90Sr - Brick method was successfully validated according to Method
Validation Requirements for Qualifying Methods Used by Radioanalytical Laboratories
Participating in Incident Response Activities and Chapter 6 of Multi-Agency Radiological
Laboratory Analytical Protocols Manual (EPA 2004) for a typical brick matrix containing
241 Am, isotopic uranium, 226Ra, and 239Pu in similar concentrations corresponding to a 10~5 risk
for a soil exposure pathway. The method was evaluated using well-characterized brick analyzed
for its macro-constituents by an independent laboratory4 and for its radiological constituents
(Attachment IV) using the combined rapid 90 Sr - brick method by NAREL, The radiochemical
results provided by NAREL for the brick blank samples indicated that that there was some
detectable 90Sr in the blank material (0.119 ± 0.029 standard error, pCi/g). It is unknown whether
the measured 90Sr was from the blank brick material or from the reagents used in the method.
The pulverized brick samples were spiked with three low-level 90Sr concentrations consistent
with a concentration range that incorporated the 10~5 exposure risk contaminant level in soil
(1.210 pCi/g, 2.440 pCi/g, and 7.28 pCi/g) in the presence of low-level concentrations of 241Am,
239Pu, 226Ra, and uranium (Table 1). The combined rapid 90Sr method met MARLAP Validation
Level "C" requirements for required method uncertainty (0.32 pCi/g) at and below the AAL, and
for a required relative method uncertainty of (13%) above the AAL concentration of 2.440 pCi/g.
A sample size of 1.5 grams and a counting time of 100 minutes were used in the method
validation process.
Based on the results of the seven blank brick samples (Table 5), the critical net concentration for
the combined method was determined to be 0.15 pCi/g for a 1.5 g sample and a 100-minute
counting time. The results for the seven blank samples had a mean and standard deviation of
-0.119 + 0.077 pCi/g. A statistical analysis of the data indicated there was an absolute bias
(difference from the expected zero concentration) for the blank brick samples.
The mean measured value and standard deviation of the 10 90Sr in the MDC test samples were
calculated as 0.51 + 0.19 pCi/g (A=l). Each result was compared to the critical net concentration
of 0.15 pCi/g. All 10 measurements had a result greater than the critical net concentration, thus
verifying that the method can meet a required MDC of 0.4040 pCi/g.
Predicated on the statistical tests provided in the Method Validation Requirements for Qualifying
Methods Used by Radioanalytical Laboratories Participating in Incident Response Activities, the
combined method was found not to have a relative bias for the three test levels. The mean
4 Wyoming Analytical Laboratories, Inc. of Golden, Colorado, performed the macro analysis.
September 2014 18
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
relative difference from the known for the low, AAL and high test levels was -4.1%, -11.1%,
and -6.28%. The average bias versus reference values at the 3 test levels, as well as the MDC
on
study, indicates this rapid method is a very robust, reliable method to determine Sr in brick
samples.
Although radionuclide and chemical interferences (241 Am, uranium, 239Pu, 226Ra and typical
constituents in the blank brick) were in the test samples, the method specificity was adequate
under conditions as tested. Additionally, high and reproducible chemical yield results (mean
yield = 85.2 + 6.8% ) was observed for the 48 analyses evaluated. The method is rapid and the
validation study indicates it can be used with confidence after a radiological incident for the
analysis of emergency brick samples.
12. References
Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP). 2004. EPA
402-B-1304 04-001 A, July. Volume I, Chapters 6, 7, 20, Glossary; Volume II and Volume
III, Appendix G. Available at www.epa.gov/radiation/marlap/.
U.S. Environmental Protection Agency (EPA). 2006. Validation and Peer Review of U.S.
Environmental Protection Agency Radiochemical Methods of Analysis. FEM Document
Number 2006-01, September 29. Available at: www.epa.gov/fem/agency_methods.htm.
U.S. Environmental Protection Agency (EPA) 2008. Radiological Laboratory Sample Analysis
Guide for Incidents of National Significance - Radionuclides in Water, Office of Air and
Radiation, Washington, DC, EPA 402-R-07-007, January 2008. Available at:
http://nepis.epa.gov/Adobe/PDF/60000LAW.PDF.
U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for Qualifying
Methods Used by Radiological Laboratories Participating in Incident Response Activities.
Revision 0. Office of Air and Radiation, Washington, DC. EPA 402-R-09-006, June.
Available at: www.epa.gov/narel.
U.S. Environmental Protection Agency (EPA). 2011. Quality Assurance Project Plan Validation
of Rapid Radiochemical Methods For Radionuclides Listed in EPA 's Standardized Analytical
Methods (SAM) For Use During Homeland Security Events. July, Revision 2. Office of Air
and Radiation, National Analytical Radiation Environmental Laboratory.
U.S. Environmental Protection Agency (EPA). 2012. Radiological Sample Analysis Guide for
Incident Response — Radionuclides in Soil. Revision 0. Office of Air and Radiation,
Washington, DC. EPA 402-R-12-006, September 2012.
September 2014 19
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Attachment I:
Estimated Elapsed Times
Combined Rapid 90Sr - Brick Method
Step
Rapid Fusion
Vacuum Box Setup
Load Sample to Sr Resin
Elute Sr from resin
Planchet Mounting
Count sample test source (1-2 hours)
Elapsed Time
(hours)*
2.5
2.75
4.25
5.0
6.5
7.5-8.5
* These estimates depend on the number of samples that can be processed
simultaneously.
September 2014
20
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
Attachment II:
Rapid Method for Sodium Hydroxide Fusion of Concrete5 and Brick Matrices Prior
to Americium, Plutonium, Strontium, Radium, and Uranium Analyses for
Environmental Remediation Following Radiological Incidents
1. Scope and Application
1.1. The method is applicable to the sodium hydroxide fusion of concrete and brick samples,
prior to the chemical separation procedures described in the following procedures:
1.1.1. Rapid Radiochemical Method for Americium-241 in Building Materials for
Environmental Remediation Following Radiological Incidents (Reference 16.1).
1.1.2. Rapid Radiochemical Method for Plutonium-238 and Plutonium-239/240 in
Building Materials for Environmental Remediation Following Radiological
Incidents (Reference 16.2).
1.1.3. Rapid Radiochemical Method for Radium-226 in Building Materials for
Environmental Remediation Following Radiological Incidents (Reference 16.3).
1.1.4. Rapid Radiochemical Method for Total Radiostrontium (Sr-90) in Building
Materials for Environmental Remediation Following Radiological Incidents
(Reference 16.4).
1.1.5. Rapid Radiochemical Method for Isotopic Uranium in Building Materials for
Environmental Remediation Following Radiological Incidents (Reference 16.5).
1.2. This general method for concrete and brick building material applies to samples
collected following a radiological or nuclear incident. The concrete and brick samples
may be received as core samples, pieces of various sizes, dust or particles (wet or dry)
from scabbling, or powder samples.
1.3. The fusion method is rapid and rigorous, effectively digesting refractory radionuclide
particles that may be present.
1.4. Concrete or brick samples should be ground to at least 50-100 mesh size prior to fusion,
if possible.
1.5. After a homogeneous, finely ground sample is obtained, the dissolution of concrete or
brick matrices by this fusion method is expected to take approximately 1 hour per batch
of 20 samples. This method assumes the laboratory starts with a representative, finely
ground, 1-1.5-g aliquant of sample and employs simultaneous heating in multiple
furnaces. The preconcentration steps to eliminate the alkaline fusion matrix and collect
the radionuclides are expected to take approximately 1 hour.
1.6. As this method is a sample digestion and pretreatment technique, to be used prior to
other separation and analysis methods, the user should refer to those individual methods
U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method for Plutonium-238 and
Plutonium-239/240 in Building Materials for Environmental Remediation Following Radiological Incidents,
Office of Air and Radiation, Washington, DC, EPA 402-R-07-007, April 2014. Unpublished.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
and any project-specific requirements for the determination of applicable measurement
quality objectives (MQOs).
1.7. Application of this method by any laboratory should be validated by the laboratory using
the protocols provided in Method Validation Guide for Qualifying Methods Used by
Radioanalytical Laboratories Participating in Incident Response Activities (Reference
16.6), or the protocols published by a recognized standards organization for method
validation.
1.7.1. In the absence of project-specific guidance, MQOs for concrete or brick samples
may be based on the Analytical Action Levels (AALs), the Required Method
Uncertainty (MMR) and the Required Relative Method Uncertainty (cpMn) found in
the Radiological Laboratory Sample Analysis Guide for Incident Response —
Radionuclides in Soil (Reference 16.7).
2. Summary of Method
2.1. The method is based on the rapid fusion of a representative, finely ground 1-1.5-g
aliquant using rapid sodium hydroxide fusion at 600 °C.
2.2. Pu, U, and Am are separated from the alkaline matrix using an iron/titanium hydroxide
precipitation (enhanced with calcium phosphate precipitation) followed by a lanthanum
fluoride matrix removal step.
2.3. Sr is separated from the alkaline matrix using a carbonate precipitation, followed by a
calcium fluoride precipitation to remove silicates.
2.4. Ra is separated from the alkaline matrix using a carbonate precipitation.
3. Definitions, Abbreviations and Acronyms
3.1. Discrete Radioactive Particles (DRPs or "hot particles"). Particulate matter in a sample
of any matrix where a high concentration of radioactive material is present as a tiny
particle (|im range).
3.2. Multi-Agency Radiological Analytical Laboratory Protocols (MARLAP) Manual
(Reference 16.8).
3.3. The use of the term concrete or brick throughout this method is not intended to be
limiting or prescriptive, and the method described herein refers to all concrete or
masonry-related materials. In cases where the distinction is important, the specific issues
related to a particular sample type will be discussed.
4. Interferences and Limitations
NOTE: Large amounts of extraneous debris (pebbles larger than Vi", non-soil related debris) are not
generally considered to be part of a concrete or brick matrix. When consistent with data quality
objectives (DQOs), materials should be removed from the sample prior to drying. It is recommended this
step be verified with Incident Command before discarding any materials.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
4.1. Concrete or brick samples with larger particle size may require a longer fusion time
during Step 11.1.8.
4.2. As much information regarding the elemental composition of the sample should be
obtained as possible. For example some concrete or brick may have native
concentrations of uranium, radium, thorium, strontium or barium, all of which may have
an effect on the chemical separations used following the fusion of the sample. In some
cases (e.g., radium or strontium analysis), elemental analysis of the digest prior to
chemical separations may be necessary to determine native concentrations of carrier
elements present in the sample.
NOTE: In those samples where native constituents are present that could interfere with the
90C
determination of the chemical yield (e.g., strontium for Sr analysis) or with the creation of a
. 226T
sample test source (e.g., Ba for Ra analysis by alpha spectrometry), it may be necessary to
determine the concentration of these native constituents in advance of chemical separation (using a
separate aliquant of fused material) and make appropriate adjustments to the yield calculations or
amount of carrier added.
4.3. Matrix blanks for these matrices may not be practical to obtain. Efforts should be made
to obtain independent, analyte-free materials that have similar composition as the
samples to be analyzed. These blanks will serve as process monitors for the fusion, and
as potential monitors for cross contamination during batch processing.
4.4. Uncontaminated concrete or brick material may be acceptable blank material for Pu,
Am, and Sr analyses, but these materials will typically contain background levels of U
and Ra isotopes.
4.4.1. If analyte-free blank material is not available and an empty crucible is used to
generate a reagent blank sample, it is recommended that 100-125 milligram (mg)
calcium (Ca) per gram of samples be added as calcium nitrate to the empty
crucible as blank simulant. This step facilitates Sr/Ra carbonate precipitations
from the alkaline fusion matrix.
4.4.2. Tracer yields may be slightly lower for reagent blank matrices, since the concrete
and brick matrix components typically enhance recoveries across the
precipitation steps.
4.5. Samples with elevated activity or samples that require multiple analyses from a single
concrete or brick sample may need to be split after dissolution. In these cases the initial
digestate and the split fractions should be carefully measured to ensure that the sample
aliquant for analysis is accurately determined.
4.5.1. Tracer or carrier amounts (added for yield determination) may be increased
where the split allows for the normal added amount to be present in the
subsequent aliquant. For very high activity samples, the addition of the tracer or
carrier may need to be postponed until following the split, in which case special
care must be taken to ensure that the process is quantitative until isotopic
exchange with the yield monitor is achieved. This deviation from the method
should be thoroughly documented and reported in the case narrative.
4.5.2. When this method is employed and the entire volume of fused sample is
processed in the subsequent chemical separation method, the original sample size
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
and units are used in all calculations, with the final results reported in the units
requested by the project manager.
4.5.3. In cases where the sample digestate is split prior to analysis, the fractional
aliquant of the sample is used to determine the sample size. The calculation of
the appropriate sample size used for analysis is described in Section 12, below.
4.6. In the preparation of blank samples, laboratory control samples (LCSs) and duplicates,
care should be taken to create these quality control samples as early in the process as
possible, and to follow the same tracer/carrier additions, digestion process, and sample
splitting used for the field samples. In the case of this method, quality control samples
should be initiated at the point samples are aliquanted into crucibles for the fusion.
4.7. Although this method is applicable to a variety of subsequent chemical separation
procedures, it is not appropriate where the analysis of volatile constituents such as iodine
or polonium is required. The user of this method must ensure that analysis is not
required for any radionuclide that may be volatile under these sample preparation
conditions, prior to performing this procedure.
4.8. Zirconium crucibles used in the fusion process may be reused.
4.8.1. It is very important that the laboratory have a process for cleaning and residual
contamination assessment of the reused zirconium crucibles. The crucibles
should be cleaned very well using soap and water, followed by warm nitric acid
and then water. Blank measurements should be monitored to ensure effective
cleaning.
4.8.2. Segregation of crucibles used for low and high activity samples is recommended
to minimize the risk of cross-contamination while maximizing the efficient use
of crucibles.
4.9. Centrifuge speed of 3500 rpm is prescribed but lower rpm speeds (>2500 rpm) may be
used if 3500 rpm is not available.
4.10. Titanium chloride (TiCb) reductant is used during the co-precipitation step with iron
hydroxide for actinides to ensure tracer equilibrium and reduce uranium from U+6 to
U+4 to enhance chemical yields. This method adds 5 mL 10 percent by mass (wt%)
TiCb along with the Fe. Adding up to 10 mL of 10 wt% TiCb may increase uranium
chemical yields, but this will need to be validated by the laboratory.
oo/r r)r)f\
4.11. Trace levels of Ra may be present in Na2CC>3 used in the Ra pre-concentration step
used in this method. Adding less 2M Na2CC>3 (<25 mL used in this method) may reduce
226Ra reagent blank levels, while still effectively pre-concentrating 226Ra from the
fusion matrix. This will need to be validated by the laboratory.
4.12. La is used to pre-concentrate actinides along with LaF3 in this method to eliminate
matrix interferences, including silica, which can cause column flow problems. La
follows Am in subsequent column separations and must be removed. Less La (2 mg)
was used for brick samples to minimize the chance of La interference on alpha
spectrometry peaks. While this may also be effective for concrete samples, this will
have to be validated by the laboratory.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
5. Safety
5.1. General
5.1.1. Refer to your laboratory safety manual for concerns of contamination control,
personal exposure monitoring and radiation dose monitoring.
5.1.2. Refer to your laboratory's chemical hygiene plan (or equivalent) for general
safety rules regarding chemicals in the workplace.
5.2. Radiological
5.2.1. Discrete Radioactive Particles (DRPs or "hot particles")
5.2.1.1. Hot particles will be small, on the order of 1 millimeter (mm) or less.
DRPs are typically not evenly distributed in the media and their
radiation emissions are not uniform in all directions (anisotropic).
5.2.1.2. Concrete/brick media should be individually surveyed using a thickness
of the solid sample that is appropriate for detection of the radionuclide
decay particles.
NOTE: The information regarding DRPs should accompany the samples during
processing as well as be described in the case narrative that accompanies the
sample results.
5.3. Procedure-Specific Non-Radiological Hazards:
5.3.1. The sodium hydroxide fusion is performed in a furnace at 600 °C. The operator
should exercise extreme care when using the furnace and when handling the hot
crucibles. Long tongs are recommended. Thermal protection gloves are also
recommended when performing this part of the procedure. The fusion furnace
should be used in a ventilated area (hood, trunk exhaust, etc.).
5.3.2. Particular attention should be paid to the use of hydrofluoric acid (HF). HF is an
extremely dangerous chemical used in the preparation of some of the reagents
and in the microprecipitation procedure. Appropriate personal protective
equipment (PPE) must be used in strict accordance with the laboratory safety
program specification.
6. Equipment and Supplies
6.1. Adjustable temperature laboratory hotplates.
6.2. Balance, top loading or analytical, readout display of at least ± 0.01 g.
6.3. Beakers, 100 mL, 150 mL capacity.
6.4. Centrifuge able to accommodate 225 mL tubes.
6.5. Centrifuge tubes, plastic, 50 mL and 225 mL capacity.
6.6. Crucibles, 250 mL, zirconium, with lids.
6.7. 100 uL, 200 uL, 500 uL, and 1 mL pipets or equivalent and appropriate plastic tips.
6.8. 1-10 mL electronic/manual pipet(s).
6.9. Drill with masonry bit (H-inch carbide bit recommended).
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
6.10. Hot water bath or dry bath equivalent.
6.11. Ice bath.
6.12. Muffle furnace capable of reaching at least 600 °C.
6.13. Tongs for handling crucibles (small and long tongs).
6.14. Tweezers or forceps.
6.15. Sample size reduction equipment (ball mill, paint shaker, etc.) and screens. The
necessary equipment will be based on a laboratory's specific method for the process of
producing a uniformly ground sample from which to procure an aliquant.
NOTE: See appendix for a method for ball-milling and homogenization of concrete or brick
6.16. Vortex stirrer.
7. Reagents and Standards
NOTES:
Unless otherwise indicated, all references to water should be understood to mean Type I reagent water
(ASTM D1193; Reference 16.9).
All reagents are American Chemical Society (ACS)-grade or equivalent unless otherwise specified.
7.1. Type I reagent water as defined in ASTM Standard Dl 193 (Reference 16.9).
7.2. Aluminum nitrate (A1(NO3)3' 9H2O)
7.2.1. Aluminum nitrate solution (2M): Add 750 g of aluminum nitrate (A1(NO3)3'
9H2O) to -700 mL of water and dilute to 1 L with water. Low-levels of
uranium are typically present in A1(NC>3)3 solution.
NOTE: Aluminum nitrate reagent typically contains trace levels of uranium
concentration. To achieve the lowest possible blanks for isotopic uranium measurements,
some labs have removed the trace uranium by passing ~250 mL of the 2M aluminum
nitrate reagent through ~7 mL TRU® Resin or UTEVA® Resin (Eichrom Technologies),
but this will have to be tested and validated by the laboratory.
7.3. Ammonium hydrogen phosphate (3.2M): Dissolve 106 g of (NH/^HPC^ in 200 mL of
water, heat on low to medium heat on a hot plate to dissolve and dilute to 250 mL with
water.
7.4. Boric Acid, H3BO3.
7.5. Calcium nitrate (1.25M): Dissolve 147 g of calcium nitrate tetrahydrate
(Ca(NO3)2'4H2O) in 300 mL of water and dilute to 500 mL with water.
7.6. Iron carrier (50 mg/mL): Dissolve 181 g of ferric nitrate (Fe(NC>3)3 • 9H2O) in 300 mL
water and dilute to 500 mL with water.
7.7. Hydrochloric acid (12M): Concentrated HC1, available commercially.
7.6.1. Hydrochloric acid (0.01M): Add 0.83 mL of concentrated HC1 to 800 mL of
water and dilute with water to 1 L.
7.6.2. Hydrochloric acid (1.5M): Add 125 mL of concentrated HC1 to 800 mL of
water and dilute with water to 1 L.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
7.8. Hydrofluoric acid (28M): Concentrated HF, available commercially.
7.9. Lanthanum carrier (1.0 mg La3+/mL): Add 1.56 g lanthanum (III) nitrate hexahydrate
[La(NO3) 3 . 6H2O] in 300 mL water, diluted to 500 mL with water.
7.10. Nitric acid (16M): Concentrated HNOs, available commercially.
7.10.1. Nitric acid (3M): Add 191 mL of concentrated HNO3 to 700 mL of water and
dilute to 1 L with water.
7.10.2. Nitric acid-boric acid solution (3M-0.25M): Add 15.4 g of boric acid and 190
mL of concentrated HNOs to 500 mL of water, heat to dissolve, and dilute to 1
liter with water.
7.10.3. Nitric acid (7M): Add 443 mL of concentrated HNO3 to 400 mL of water and
dilute to 1 L with water.
7.10.4. Nitric acid (8M): Add 506 mL of concentrated HNO3 to 400 mL of water and
dilute to 1 L with water.
7.11. Sodium carbonate (2M): Dissolve 212 g anhydrous Na2CC>3 in 800 mL of water, then
dilute to 1 L with water.
7.12. Sodium hydroxide pellets.
7.13. Titanium (III) chloride solution (TiCl3), 10 wt% solution in 20-30 wt% hydrochloric
acid.
7.14. Radioactive tracers/carriers (used as yield monitors) and spiking solutions. A
radiotracer is a radioactive isotope of the analyte that is added to the sample to
measure any losses of the analyte. A carrier is a stable isotope form of a radionuclide
(usually the analyte) added to increase the total amount of that element so that a
measureable mass of the element is present. A carrier can be used to determine the
yield of the chemical process and/or to carry the analyte or radiotracer through the
chemical process. Refer to the chemical separation method(s) to be employed upon
completion of this dissolution technique. Tracers/carriers that are used to monitor
radiochemical/chemical yield should be added at the beginning of this procedure. This
timing allows for monitoring and correction of chemical losses in the combined
digestion process, as well as in the chemical separation method. Carriers used to
prepare sample test sources but not used for chemical yield determination (e.g., cerium
added for microprecipitation of plutonium or uranium), should be added where
indicated.
8. Sample Collection, Preservation, and Storage
Not Applicable.
9. Quality Control
9.1. Where the subsequent chemical separation technique requires the addition of carriers
and radioactive tracers for chemical yield determinations, these are to be added prior to
beginning the fusion procedure, unless there is good technical justification for doing
otherwise.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
9.2. Batch quality control results shall be evaluated and meet applicable analytical protocol
specifications (APS) prior to release of unqualified data. In the absence of project-
defined APS or a project-specific quality assurance project plan (QAPP), the quality
control sample acceptance criteria defined in the laboratory's Quality Manual and
procedures shall be used to determine acceptable performance for this method.
9.2.1. An exception to this approach may need to be taken for samples of
exceptionally high activity where human safety may be involved.
9.3. Quality control samples are generally specified in the laboratory's Quality Manual or
in a project's APS. At the very minimum the following are suggested:
9.3.1. A laboratory control sample (LCS), which consists solely of the reagents used
in this procedure and a known quantity of radionuclide spiking solution, shall
be run with each batch of samples. The concentration of the LCS should be at
or near the action level or level of interest for the project
9.3.2. One reagent blank shall be run with each batch of samples. The blank should
consist solely of the reagents used in this procedure (including tracer or carrier
from the analytical method added prior to the fusion process).
9.3.3. A sample duplicate that is equal in size to the original aliquant should be
analyzed with each batch of samples. This approach provides assurance that
the laboratory's sample size reduction and sub-sampling processes are
reproducible.
10. Calibration and Standardization
10.1. Refer to the individual chemical separation and analysis methods for calibration and
standardization protocols.
11. Procedure
11.1. Fusion
11.1.1. In accordance with the DQOs and sample processing requirements stated in
the project plan documents, remove extraneous materials from the concrete
or brick sample using a clean forceps or tweezers.
11.1.2. Weigh out a representative, finely ground 1-g aliquant of sample into a
labeled crucible (1.5-g aliquants for 90Sr analysis).
NOTES:
It is anticipated that concrete or brick powder sample material will be dry enough to
aliquant without a preliminary drying step. In the event samples are received that
contain moisture, the samples may be dried in a drying oven at 105 °C prior to taking
the aliquant.
For Sr and Ra analyses, a reagent blank of 100-150 mg calcium per gram of sample
(prepared by evaporating 2.5 mL of 1.25M calcium nitrate, Ca(NO3)2, for radium and 3
mL of 1.25M Ca(NO3)2 for strontium) should be added to the crucible as a blank
simulant to ensure the blank behaves like the concrete or brick samples during the
precipitation steps.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
11.1.3. Add the proper amount of tracer or carrier appropriate for the method being
used and the number of aliquants needed.
11.1.4. Place crucibles on a hot plate and heat to dryness on medium heat.
NOTE: Heat on medium heat to dry quickly but not so high as to cause splattering.
11.1.5. Remove crucibles from hot plate and allow to cool.
11.1.6. Add the following amounts of sodium hydroxide based on the aliquant
size/analysis required.
1 g for Pu, Am, U: 15 g NaOH
l.SgforSr: 15 g NaOH
IgforRa: 10 g NaOH
11.1.7. Place the crucibles with lids in the 600 °C furnace using tongs.
11.1.8. Fuse samples in the crucibles for-15 minutes.
NOTE: Longer times may be needed for larger particles.
11.1.9. Remove hot crucibles from furnace very carefully using tongs, andtransfer to
hood.
11.1.10. Add -25-50 mL of water to each crucible -8 to 10 minutes (or longer) after
removing crucibles from furnace, and heat on hotplate to loosen/dissolve
solids.
11.1.11. If necessary for dissolution, add more water, and warm as needed on a
hotplate.
11.1.12. Proceed to Section 11.2 for the actinide preconcentration procedure, 11.3 or
11.4 for Sr preconcentration, or 11.5 for Ra preconcentration steps.
11.2. Preconcentration of Actinides (Pu, U, or Am) from Hydroxide Matrix
11.2.1. Pipet 2.5 mL of iron carrier (50 mg/mL) into a labeled 225-mL centrifuge
tube for each sample.
11.2.2. Add La carrier to each 225-mL tube as follows:
Concrete: 5 mL of 1 mg La/mL for Pu, Am, U
Brick: 5 mL of 1 mg La/mL for Pu, and U; 2 mL 1 mg La/mL for Am
11.2.3. Transfer each fused sample to a labeled 225 mL centrifuge tube, rinse.
11.2.4. crucibles well with water, and transfer rinses to each tube.
11.2.5. Dilute each sample to approximately 180 mL with water.
11.2.6. Cool the 225 mL centrifuge tubes in an ice bath to approximately room
temperature as needed.
11.2.7. Pipet 1.25M Ca(NO3) 2 and 3.2M (NH4)2HPO4 into each tube as follows:
Pu, Am: 2 mL 1.25M Ca(NO3) 2 and 3 mL 3.2M (NH4)2HPO4
U: 3 mL 1.25M Ca(NO3)2 and 5 mL 3.2M (NH4)2HPO4
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
11.2.8. Cap tubes and mix well.
11.2.9. Pipet 5 mL of 10 wt% TiCb into each tube, and cap and mix immediately.
11.2.10. Cool the 225 mL centrifuge tubes in an ice bath for -10 minutes.
11.2.11. Centrifuge tubes for 6 minutes at 3500 rpm.
11.2.12. Pour off the supernate, and discard to waste.
11.2.13. Add 1.5MHC1 to each tube to redissolve each sample in a total volume of
-60 mL.
11.2.14. Cap and shake each tube to dissolve solids as well as possible.
NOTE: There will typically be undissolved solids, which is acceptable.
11.2.15. Dilute each tube to -170 mL with 0.01M HC1. Cap and mix.
11.2.16. Pipet 1 mL of 1.0 mg La/mL into each tube.
11.2.17. Pipet 3 mL of 10 wt% TiCb into each tube. Cap and mix.
11.2.18. Add 22 mL of concentrated HF into each tube. Cap and mix well.
11.2.19. Place tubes to set in an ice bath for -10 minutes to get the tubes very cold.
11.2.20. Centrifuge for -10 minutes at 3000 rpm or more or as needed.
11.2.21. Pour off supernate, and discard to waste.
11.2.22. Pipet 5 mL of 3M HNCh - 0.25M boric acid into each tube.
11.2.23. Cap, mix and transfer contents of the tube into a labeled 50 mL centrifuge
tube.
11.2.24. Pipet 6 mL of 7M HNOs and 7 mL of 2M aluminum nitrate into each tube,
cap and mix (shake or use a vortex stirrer), and transfer rinse to 50-mL
centrifuge tube.
11.2.25. Pipet 3 ml of 3M HNO3 directly into the 50 mL centrifuge tube.
11.2.26. Warm each 50 mL centrifuge tube in a hot water bath for a few minutes,
swirling to dissolve.
11.2.27. Remove each 50 mL centrifuge tube from the water bath and allow to cool to
room temperature
11.2.28. Centrifuge the 50 ml tubes at 3500 rpm for 5 minutes to remove any traces of
solids (may not be visible prior to centrifuging), and transfer solutions to
labeled beakers or tubes for further processing. Discard any solids.
11.2.29. Proceed directly to any of those methods listed in Sections 1.1.1, 1.1.2, or
1.1.5(forPu, U, or Am).
on
11.3. Preconcentration of Sr from Hydroxide Matrix (Concrete)
NOTE: The preconcentration steps for 90Sr in this section can also be applied to brick samples, but
this will have to be validated by the laboratory. See Section 11.4 for steps validated for 90Sr in
brick samples.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
11.3.1. Transfer each fused sample to a 225-mL centrifuge tube, rinse crucibles well
with water, and transfer rinses to each tube.
11.3.2. Dilute to approximately 150 mL with water.
11.3.3. Add 15-mL concentrated HC1 to each tube.
11.3.4. Cap and mix solution in each tube.
11.3.5. Pipet 1-mL of 1.25M Ca(NO3)2into each tube.
11.3.6. Add 2-mL of 50-mg/mL iron carrier into each tube.
11.3.7. Add 25-mL of 2MNa2CO3to each tube.
11.3.8. Cap tubes and mix well.
11.3.9. Cool the 225-mL centrifuge tubes in an ice bath for -10 minutes.
11.3.10. Centrifuge tubes for 5 minutes at 3500 rpm.
11.3.11. Pour off the supernate, and discard to waste.
11.3.12. Add 1.5MHC1 to each tube to redissolve each sample in a total volume of
-50 mL.
11.3.13. Cap and shake each tube to dissolve solids as well as possible.
11.3.14. Dilute each tube to -170 mL with 0.01M HC1. Cap and mix.
11.3.15. Add 22 mL of concentrated HF into each tube. Cap and mix well.
11.3.16. Place tubes to set in an ice bath for-10 minutes to get the tubes very cold.
11.3.17. Centrifuge for-6 minutes at 3500 rpm.
11.3.18. Pour off supernate, and discard to waste.
11.3.19. Pipet 5 mL of concentrated HNO3and 5 mL of 3M HNO3 - 0.25M boric acid
into each 225 mL tube to dissolve precipitate.
11.3.20. Cap and mix well. Transfer contents of the tube into a labeled 50-mL
centrifuge tube.
11.3.21. Pipet 5 mL of 3M HNOs and 5 mL of 2M aluminum nitrate into each tube,
cap tube and mix.
11.3.22. Transfer rinse solutions to labeled 50-mL centrifuge tubes and mix well
(shake or use vortex stirrer).
11.3.23. Centrifuge the 50 mL tubes at 3500 rpm for 5 minutes to remove any traces
of solids.
11.3.24. Transfer solutions to labeled beakers or new 50 mL tubes for further
processing.
11.3.25. If solids remain in the original 50 mL tubes (step 11.3.23), add 5 mL of 3M
HNO3 to each tube containing solids, cap, and mix well, Centrifuge for 5
minutes and add the supernate to the sample solution from step 11.3.24.
Discard any remaining solids.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
11.3.26. Set aside for 90Sr analysis using RapidRadiochemicalMethodfor Total
Radiostrontium (Sr-90) In Building Materials for Environmental
Remediation Following Radiological Incidents (Reference 16.4).
on
11.4. Preconcentration of Sr from Hydroxide Matrix (Brick)
NOTE: The preconcentration steps for 90Sr in this section, using calcium phosphate instead of
calcium carbonate, can also be applied to concrete samples but this will have to be validated by
the laboratory. See Section 11.3 for steps validated for 90Sr in concrete samples.
11.4.1. Transfer each fused sample to a labeled 225-mL centrifuge tube, rinse
crucibles well with water, and transfer rinses to each tube.
11.4.2. Dilute to approximately 150 mL with water.
11.4.3. Pipet2mL 1.25M Ca(NO3)2 into each tube.
11.4.4. Add 1 mL 50-mg/mL iron carrier into each tube.
11.4.5. Add 5 mL 3.2M (NH4)2HPO4to each tube.
11.4.6. Cap tubes and mix well.
11.4.7. Centrifuge tubes for 5 minutes at 3500 rpm.
11.4.8. Pour off the supernate and discard to waste.
11.4.9. Add 1.5M HC1 to each tube to redissolve each sample in a total volume of
-60 mL.
11.4.10. Cap and shake each tube to dissolve solids as well as possible.
11.4.11. Dilute each tube to -170 mL with 0.01M HC1. Cap and mix.
11.4.12. Add 22 mL of concentrated HF into each tube. Cap and mix well.
11.4.13. Place tubes to set in an ice bath for-10 minutes to get the tubes very cold.
11.4.14. Centrifuge for-6 minutes at 3500 rpm.
11.4.15. Pour off supernate and discard to waste.
11.4.16. Pipet 5 mL of concentrated HNO3 and 5 mL of 3M HNO3 - 0.25M boric acid
into each 225 mL tube to dissolve precipitate.
11.4.17. Cap and mix well. Transfer contents of the tube into a labeled 50-mL
centrifuge tube.
11.4.18. Pipet 5 mL of 3M HNOs and 5 mL of 2M aluminum nitrate into each tube,
cap tube and mix.
11.4.19. Transfer rinse solutions to labeled 50 mL centrifuge tubes and mix well
(shake or use vortex stirrer).
11.4.20. Centrifuge the 50 mL tubes at 3500 rpm for 5 minutes to remove any traces
of solids.
11.4.21. Transfer solutions to labeled beakers or new 50 mL tubes for further
processing.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
11.4.22. If solids remain in the original 50 mL tubes (step 11.4.20), add 5 mL of 3M HNO3
to each tube containing solids, cap, and mix well, Centrifuge for 5 minutes and add
the supernate to the sample solution from step 11.4.21. Discard any remaining
solids.
11.4.23. Set aside for 90Sr analysis using Rapid Radiochemical Method for Total
Radiostrontium (Sr-90) In Building Materials for Environmental
Remediation Following Radiological Incidents (Reference 16.4).
11.5. Preconcentration of 226Ra from Hydroxide Matrix
11.5.1. Transfer each sample to a labeled 225 mL centrifuge tube, rinse crucibles
well with water, and transfer rinses to each tube.
11.5.2. Dilute to approximately 150 mL with water.
11.5.3. Add 10 mL of concentrated HC1 to each tube.
11.5.4. Cap and mix each tube well.
11.5.5. Pipet 0.5 mL of 1.25M Ca(NO3)2into each tube.
11.5.6. Add 25 mL of 2M Na2CO3 to each tube.
11.5.7. Cap tubes and mix.
11.5.8. Cool the 225-mL centrifuge tubes in an ice bath for -5-10 minutes.
11.5.9. Centrifuge tubes for 6 minutes at 3500 rpm.
11.5.10. Pour off the supernate, and discard to waste.
11.5.11. Pipet 10 mL 1.5M HC1 into each tube to dissolve precipitate. Cap and mix.
11.5.12. Transfer sample solution to a labeled 50-mL centrifuge tube.
11.5.13. Pipet lOmL 1.5MHC1 into each 225-mL tube to rinse. Cap and rinse well.
11.5.14. Transfer rinse solution to 50 mL-tube and mix well.
NOTE: Typically the HC1 added to dissolve the carbonate precipitate is sufficient to
acidify the sample. If the precipitate was unusually large and milky suspended solids
remain, indicating additional acid is needed, the pH can be checked to verify it is pH 1
or less. To acidify the pH <1,1 or 2 mL of concentrated hydrochloric acid may be added
to acidify the solution further and get it to clear. Undissolved solids may be more likely
to occur with brick samples. Tubes may be warmed in a water bath to help dissolve
samples.
11.5.15. If solids remain in the original 225 mL tubes, add 5 mL of 1.5MHC1 to each
tube containing solids, cap, and mix well. Centrifuge for 5 minutes and add
the supernate to the sample solution from step 11.5.14. Discard any
remaining solids.
11.5.16. Set aside for 226Ra analysis using Rapid Radiochemical Method for Radium-
226 in Building Materials for Environmental Remediation Following
Radiological Incidents (Reference 16.3).
12. Data Analysis and Calculations
12.1. Equations for determination of final result, combined standard uncertainty, and
radiochemical yield (if required) are found in the corresponding chemical separation
and analysis methods, with the project manager providing the units.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
12.2. In cases where samples have elevated activity, smaller initial sample aliquants may be
taken from the original sample. Alternately, smaller aliquant volumes may be taken
from the final sample volume containing the dissolved precipitate (digestate).
Aliquants should be removed carefully and accurately from this final sample volume.
NOTE: Small aliquants taken from the final sample digestate for Sr and Ra analysis may be used
in the respective analytical procedures as is. Smaller aliquants for actinide analysis should be
diluted to a 15 mL total volume with 3M HNO3 so that load solution acidity is maintained when
valence adjustment reagents are added.
For a single split, the effective size of sample is calculated:
w =w —2_ (-i\
a s T^l \ '
s
Where:
Ws = original sample size, in the units designated by the project manager (e.g.,
1 g, etc.)
Ds = mass or volume of the entire final digestate, (e.g., 20 mL, etc.).
Da = mass or volume of the aliquant of digestate used for the individual
analyses, (e.g., 5.0 mL, etc.). Note that the values for Da must be in the
same units used in Ds.
Wa = sample aliquant size, used for analysis, in the units designated by the
project manager (e.g., kg, g, etc.).
NOTE: For higher activity samples, additional dilution may be needed. In such cases, Equation 1
should be modified to reflect the number of splits and dilutions performed. It is also important to
measure the masses or volumes, used for aliquanting or dilution, to enough significant figures so
that their uncertainties have an insignificant impact on the final uncertainty budget. In cases
where the sample will not be split prior to analysis, the sample aliquant size is simply equal to the
original sample size, in the same units requested by the project manager.
13. Method Performance
13.1. Report method validation results.
13.2. The method performance data for the analysis of concrete and brick by this dissolution
method may be found in the attached appendices.
13.3. Expected turnaround time per sample
13.3.1. For a representative, finely ground 1 -g aliquant of sample, the fusion should
add approximately 2 hours per batch to the time specified in the individual
chemical separation methods.
13.3.2. The preconcentration steps should add approximately 2 to 2.5 hours per
batch.
NOTE: Processing times for the subsequent chemical separation methods are given in
those methods for batch preparations.
14. Pollution Prevention
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
This method inherently produces no significant pollutants. The sample and fusion reagents
are retained in the final product and are carried into the ensuing chemical separation
techniques, which marginally increases the salt content of the effluent waste. It is noted that
if the sampled particulates include radionuclides that may be volatile under the fusion
conditions, these constituents will be exhausted through the fume hood system.
15. Waste Management
15.1. Refer to the appropriate chemical separation methods for waste disposal information.
16. References
Cited References
16.1. U.S. Environmental Protection Agency (EPA). 2013. Rapid Radiochemical Method
for Americium-241 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R14-007. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.2. U.S. Environmental Protection Agency (EPA). 2013. Rapid Radiochemical Method
for Pu-238 and Pu-239/240 in Building Materials for Environmental Remediation
Following Radiological Incidents. Revision 0, EPA 402-R14-006. Office of Air and
Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.3. U.S. Environmental Protection Agency (EPA). 2013. Rapid Radiochemical Method
for Radium-226 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R14-002. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.4. U.S. Environmental Protection Agency (EPA). 2013. Rapid Radiochemical Method
for Total Radiostrontium (Sr-90) in Building Materials for Environmental
Remediation Following Radiological Incidents. Revision 0, EPA 402-R14-001. Office
of Air and Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.5. U.S. Environmental Protection Agency (EPA). 2013. Rapid Radiochemical Method
for Isotopic Uranium in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R14-005. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.6. U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for
Qualifying Methods Used by Radiological Laboratories Participating in Incident
Response Activities. Revision 0. Office of Air and Radiation, Washington, DC. EPA
402-R-09-006, June. Available at: www.epa.gov/narel.
16.7. U.S. Environmental Protection Agency (EPA). 2012. Radiological Laboratory Sample
Analysis Guide for Incident Response — Radionuclides in Soil. Revision 0. Office of
Air and Radiation, Washington, DC. EPA 402-R-12-006, September 2012. Available
at: www.epa.gov/narel.
16.8. MARLAP. Multi-Agency Radiological Laboratory Analytical Protocols Manual.
2004. Volumes 1-3. Washington, DC: EPA 402-B-04-001A-C, NUREG 1576, NTIS
PB2004-105421, July. Available at: www.epa.gov/radiation/marlap.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
16.9. ASTM Dl 193, "Standard Specification for Reagent Water" ASTM Book of Standards
11.01, current version, ASTM International, West Conshohocken, PA.
Other References
16.10. Maxwell, S., Culligan, B. and Noyes, G. 2010. Rapid method for actinides in
emergency soil samples, RadiochimicaActa. 98(12): 793-800.
16.11. Maxwell, S., Culligan, B., Kelsey-Wall, A. and Shaw, P. 2011. "Rapid Radiochemical
Method for Actinides in Emergency Concrete and Brick Samples," Analytica Chimica
Acta. 701(1): 112-8.
16.12. U.S. Environmental Protection Agency (EPA). 2010. Rapid Radiochemical Methods
for Selected Radionuclides in Water for Environmental Restoration Following
Homeland Security Events, Office of Air and Radiation. EPA 402-R-10-001, February.
Revision 0.1 of rapid methods issued October 2011. Available at: www.epa.gov/narel/.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
17. Tables, Diagrams, and Flow Charts
17.1. Fusion Flow Chart
Timeline for Rapid Fusion and Preparation of Building
Materials Samples for Precipitation and Analysis
Rapid Fusion (Steps 11.1 - 11.9)
1. Add concrete or brick sample to 250 mL Zr crucible.
2. Add appropriate tracers/carriers.
3. Dry on hot plate.
4. Add 10-15 g NaOH pellets to crucible.
5. Heat -15 min. at 600 °C.
6. Remove from furnace and allow to cool.
V
Prepare for precipitations (Step 11.1.10)
1. Add waterto crucibles to dissolve fused sample as
much as possible and transferto centrifuge tubes.
2. Warm on hotplate to dissolve/loosen solids.
3. Transfer to 225 mL centrifuge tube.
4. Rinse crucibles well with water and transferto tubes.
5. Fusion solution is ready foractinide orRa/Sr
precipitations.
Elapsed Time
45 minutes
11/2 hours
Continued on Appropriate
Procedure Chart
I
Actinide
Precipitation
Procedure
X
/
Carbonate (concrete)
or Phosphate (brick)/
Fluoride
Precipitations for Sr
Procedure
\
/
Carbonate
Precipitation for Ra
Procedure
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
17.2. Actinide Precipitation Flow Chart
Actinide Precipitation Procedure
Actinide
Precipitation
Procedure
Continued from 17.1 Fusion Flow Chart
1. Add Fe and La to each tube.
2. Dilute to 180 ml_ with water.
3. Cool to room temperature in ice bath.
4. Add Ca and (NH4)2HPO4 to each tube. Cap and mix.
5. Add TiCI3 to each tube. Cap and mix.
6. Cool in ice bath foMO min.
7. Centrifuge for6 min and pour off supernate.
8. Redissolve in 1.5M HCI.
9. Dilute to 170 mLwith 0.01M HCI.
10. Add La, TiCI3, and HF and cool in ice bath for 10 min.
11. Centrifugefor 10 min and pour off supernate.
12. Redissolve in 5mL 3M HNO3-0.25M H3BO3 + 6 mL
HNO3 +7 mL 2M AI(NO3)3 + 3 mL 3M HNO3, warming
to dissolve in 50 mL centrifuge tubes.
13. Centrifuge to remove any trace solids.
14. Transfer sample solutions to newtubes or beakers
and discard any traces of solids.
15. Allow sample solutions to cool to room temperature.
16. Analyze sample solutions forspecific actinides using
rapid methods forspecific actinides in building
materials.
Elapsed Time
3 hours
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
17.3. Strontium Precipitation Flow Chart
Strontium Precipitation Procedure (Concrete)
CaCO3 / CaF2
Precipitation for Sr
in Concrete
Procedure
Elapsed Time
Continued from 17.1 Fusion Flowchart
1. Dilute to 150 ml with water.
2. Add 15 ml of concentrated HCL to each tube.
3. Add 1 ml 1.25M Ca (NO3)2, 100 mg Fe and 25 ml
2M Na2CO3 to each tube.
4. Cool 10 min in ice bath.
5. Centrifuge for 5 min. and pour off supernate.
6. Add 1.5M HCI to each tube to redissolve each
sample.
7. Dilute each tube to-170 ml with 0.01 M HCI.
8. Add 22 ml concentrated HF and cool in ice bath for
10 min.
9. Centrifuge for 6 min and pour off supernate.
10. Redissolve in 5 ml 3M HNO3-0.25M H3BO3 + 5mL
concentrated HNO3 +5 ml 2M AI(NO3)3 + 5 ml 3M
HNO3.
11. Cap and mix using shaking orvortex stirrer.
12. Centrifuge for 5 min and discard trace solids.
13. Analyze sample solutions for 90Sr using 90Sr method
for building materials.
21/2 hours
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
Strontium Precipitation Procedure (Brick)
Ca3(PO4)2 / CaF2
Precipitation for Sr
in Brick Procedure
Continued from 17.1 Fusion Flowchart
1. Dilute to 150 ml with water.
2. Add 2 ml 1.25M Ca(NO3)2, 50 mg Fe, and 5 ml
3.2M (NH4)2HPO4 to each tube.
3. Centrifuge for 5 min and pour off supernate.
4. Redissolve in -60 ml_1.5M HCL
5. Dilute to 170 ml with 0.01M HCI.
6. Add 22 ml Concentrated HF and wait 10 min.
7. Centrifuge for 6 min and pour off supernate.
8. Redissolve in 5 ml 3M HNO3-0.25M H3BO3 + 5 ml
concentrated HNO3 +5 ml 2M AI(NO3)3 + 5 ml 3M
HNO3.
9. Cap and mix using vortex stirrer.
10. Centrifuge for 5 min and discard trace solids.
11. Analyze sample solutions for 90Sr using 90Sr method
for building materials.
Elapsed Time
21/2 hours
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
17.4. Radium Precipitation Flow Chart
Carbonate Precipitation for Radium Procedure
Carbonate
Precipitation for
Radium Procedure
Continued from 17.1 Fusion Flowchart
1. Dilute to 150 ml with water.
2. Add 10 ml concentrated HCI to each tube.
3. Add 0.5 ml 1.25M Ca(NO3)2 and 25 ml 2M Na2CO3
to each tube.
4. Cool ~10 min in ice bath.
5. Centrifuge for 6 min and pour off supernate.
6. RedissolveinIO ml 1.5M HCL.
7. Transfer to 50 ml centrifuge tubes.
8. Rinse 225-mL tube with 10-mL 1.5M HCL and
transfer to 50-mLtube.
9. Cap and mix by shaking or using vortex stirrer.
10. Centrifuge for 5 min and discard trace solids.
11. Analyze sample solutions for 226Ra using 226Ra
method for building materials.
Elapsed Time
3 hours
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
Appendix:
Rapid Technique for Milling and Homogenizing Concrete and Brick Samples
Al. Scope and Application
ALL Concrete or brick samples may be received as powder, core samples or other size
pieces or chunks. The goal is to obtain representative sample aliquants from
homogeneous amounts of sample.
A1.2. The ball mill method describes one approach for the rapid, gross preparation of
concrete or brick samples to yield representative 1-2-g aliquant for radiochemical
analysis of non-volatile radionuclides. The method addresses steps for splitting,
drying, and milling of 50-2,000 g concrete or brick samples. The concrete or brick
sample must be reduced to pieces or fragments less than -25 mm in diameter prior
to using the ball mill. This can be done with a hydraulic press or mallet.
Al .3. The method is designed to be used as a preparatory step for the attached methods
for fusion of concrete or brick for 241Am, 2J9/240Pu, U, *Sr, and 226Ra. It may also
be applied to other matrices whose physical form is amenable to pulverization in
the ball mill.
Al .4. If the levels of activity in the sample are low enough to permit safe radiological
operations, up to 2 kg of concrete or brick can be processed.
Al .5. For smaller amounts of concrete or brick samples, a drill with masonry bit can be
used in a lab hood inside a plastic bag to collect the powder that results.
A2. Summary of Methods
A2.1. This method uses only disposable equipment to contact the sample, minimizing the
risk of contamination and cross-contamination and eliminating concerns about
adequate cleaning of equipment.
A2.2. Extraneous material, such as rocks or debris, may be removed prior to processing
the sample unless the project requires that they be processed as part of the sample.
NOTE: The sample mass is generally used for measuring the size of solid samples. The initial
process of acquiring a representative aliquant uses the volume of the sample, as the total
sample size is generally based on a certain volume of concrete or brick (e.g., 500 mL).
A2.3. The entire sample as received (after reducing fragment size to less than -25 mm
diameter) is split by coning and quartering until 75-150 mL of concrete or brick are
available for subsequent processing. If less than 450 mL of concrete or brick is
received, the entire sample is processed.
A2.4. The concrete or brick is transferred to a paint can or equivalent. Percent solids are
determined, if required, by drying in a drying oven. A mallet and plastic bag or
hydraulic press may be needed to break up larger pieces.
A2.5. Grinding media (stainless steel or ceramic balls or rods) are added, and the sample
is milled to produce a finely-ground, well-homogenized, powder with predominant
particle size less than 250 micrometers (um).
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NOTE: A mortar and pestle may also be used as needed to grind the sample further.
A2.6. If the sample may contain discreet radioactive particles (DRPs), particles larger
than a nominal size of 150 um are screened for radioactivity, and further milled, or
processed with another appropriate method to ensure that they will be chemically
available for subsequent processing.
A2.7. The resulting milled sample is stored in, and aliquanted directly from, the container
used for pulverization.
A2.8. The drill bit method involves drilling into the sample using a drill bit. The
operation is performed inside a disposable plastic bag in a hood so that the drilled
out sample is caught within the plastic bag (this approach also minimizes the spread
of contamination). A drill bit such as a H-inch carbide bit is recommended. The
holes should be drilled in such a way as to obtain representative powdered samples.
The drill bit should be cleaned between uses on different samples using soap and
water.
A3. Definitions, Abbreviations, and Acronyms
A3.1. Discrete Radioactive Particles (DRPs or "hot particles"). Particulate matter in a
sample of any matrix where a high concentration of radioactive material is
contained in a tiny particle (um range).
A3.2. Multi-Agency Radiological Analytical Laboratory Protocols (MARLAP) Manual
(Reference A16.3).
A3.3. ASTM C999 Standard Practice for Soil Sample Preparation for the Determination
of Radionuclides (Reference A16.4).
A4. Interferences
A4.1. Radi ol ogi cal Interference s
A4.1.1. Coning and quartering provides a mechanism for rapidly decreasing the
overall size of the sample that must be processed while optimizing the
representativeness of the subsampling process. By decreasing the time and
effort needed to prepare the sample for subsequent processing, sample
throughput can be significantly improved. Openly handling large amounts
of highly contaminated materials, however, even within the containment
provided by a fume hood, may pose an unacceptable risk of inhalation of
airborne contamination and exposure to laboratory personnel from
radioactive or other hazardous materials. Similarly, it may unacceptably
increase the risk of contamination of the laboratory.
A4.1.2. In such cases, the coning and quartering process may be eliminated in lieu
of processing the entire sample. The time needed to dry the sample will
increase significantly, and the container size and the number and size of
grinding media used will need to be adjusted to optimize the milling
process. See ASTM C999 for an approach for homogenization and milling
of larger soil samples.
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A4.1.3. The precise particle size of the milled sample is not critical to subsequent
processes. However, milling the sample to smaller particle sizes, and
thorough mixing, both facilitate representative sub-sampling by
minimizing the amount of sample that is not pulverized to fine mesh and
must be discarded. Additionally, subsequent fusion and digestion
processes are more effective when performed on more finely milled
samples.
A4.1.4. This method assumes that radioactivity in the sample is primarily adsorbed
onto the surface of particles, as opposed to being present as a hot particle
(see discussion of DRPs below). Thus, nearly all of the activity in a
sample will be associated with sample fines. By visually comparing the
sample to a qualitative standard of 50-100 mesh size particles, it is
possible to rapidly determine whether the sample is fine enough to
facilitate the subsequent fusion or digestion. This method assumes that
when greater than 95% of the sample is as fine or finer than the 50-100
mesh sample, bias imparted from losses of larger particles will be
minimal.
A4.1.5. If the sample was collected near the epicenter of a radiological dispersal
device (RDD) or improvised nuclear device (IND) explosion, it may
contain millimeter- to micrometer-sized particles of contaminant referred
to as "discrete radioactive particles" or DRPs. DRPs may consist of small
pieces of the original radioactive source and thus may have very high
specific activity. They may also consist of chemically intractable material
and present special challenges in the analytical process. Even when the
size is reduced to less than 50-100 mesh, these particles may resist fusion
or digestion of the solids into ionic form that can be subjected to chemical
separations.
A4.1.6. When DRPs may be present, this method isolates larger particles by
passing the sample through a disposable 50-mesh screen after which they
can be reliably checked for radioactivity. DRPs may reliably be identified
by their very high specific activity, which is readily detectable, since they
show high count rates using hand-held survey equipment such as a thin-
window Geiger-Muller (G-M) probe.
A4.1.7. When present, DRPs may be further milled and then recombined with the
original sample. Alternatively, the particles, or the entire sample may need
to be processed using a different method capable of completely
solubilizing the contaminants such that the radionuclides they contain are
available for subsequent chemical separation.
A5. Safety
A5.1. General
A5.1.1. Refer to your safety manual for concerns of contamination control,
personal exposure monitoring, and radiation dose monitoring.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
A5.1.2. Refer to your laboratory's chemical hygiene plan (or equivalent) for
general safety rules regarding chemicals in the workplace.
A5.2. Radiological
A5.2.1. Refer to your radiation safety manual for direction on working with
known or suspected radioactive materials.
A5.2.2. This method has the potential to generate airborne radioactive
contamination. The process should be carefully evaluated to ensure that
airborne contamination is maintained at acceptable levels. This should
take into account the activity level, and physical and chemical form of
contaminants possibly present, as well as other engineering and
administrative controls available.
A5.2.3. Hot Particles (DRPs)
A5.2.3.1. Hot particles will usually be small, on the order of 1 mm or
less. Typically, DRPs are not evenly distributed in the
media, and their radiation emissions are not uniform in all
directions (anisotropic). Filtration using a 0.45 urn or
smaller filter may be needed following subsequent fusion to
identify the presence of smaller DRPs.
A5.2.3.2. Care should be taken to provide suitable containment for
filter media used in the pretreatment of samples that may
have DRPs, because the particles become highly statically
charged as they dry out and will "jump" to other surfaces
potentially creating contamination-control issues.
A5.3. Method-Specific Non-Radiological Hazards
A5.3.1. This method employs a mechanical shaker and should be evaluated for
personnel hazards associated with the high kinetic energy associated with
the milling process.
A5.3.2. This method employs a mechanical shaker and involves vigorous agitation
of steel or ceramic balls inside steel cans. The process should be evaluated
to determine whether hearing protection is needed to protect the hearing of
personnel present in the area in which the apparatus is operated.
A6. Equipment and supplies
A6.1. Balance, top-loading, range to accommodate sample size encountered, readability
to ±1%.
A6.2. Drying oven, at 110 ± 10 °C.
A6.3. Steel paint cans and lids (pint, quart, 2-quart, 1-gallon, as needed).
A6.4. Steel or ceramic grinding balls or rods for ball milling, -15-25 mm diameter. The
size and number of grinding media used should be optimized to suit the types of
concrete or brick, the size of the can, and the volume of sample processed.
A6.5. Disposable wire cloth - nominal 48 mesh size (-300 um).
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
A6.6. Disposable sieves, U.S. Series No. 50 (300 um or 48 mesh) and U.S. Series No.
100 (150 urn or 100 mesh).
A6.7. Red Devil 5400 mechanical paint shaker or equivalent.
A6.8. Disposable scoop, scraper, tongue depressor or equivalent.
A7. Reagents and Standards
No reagents needed.
A8. Sample Collection, Preservation and Storage
A8.1. Samples should be collected in appropriately sized plastic, metal or glass
containers.
A8.2. No sample preservation is required. If samples are to be held for an extended period
of time, refrigeration may help minimize bacterial growth in the sample.
A8.3. Default sample collection protocols generally provide solid sample volumes
equivalent to approximately 500 mL of sample. Such samples will require two
splits to obtain a -100 mL sample.
A9. Quality Control
A9.1. Batch quality control results shall be evaluated and meet applicable Analytical
Protocol Specifications (APS) prior to release of unqualified data. In the absence of
project-defined APS or a project-specific quality assurance project plan (QAPP),
the quality control sample acceptance criteria defined in the laboratory quality
manual and procedures shall be used to determine acceptable performance for this
method.
A9.2. Quality control samples should be initiated as early in the process as possible.
Since the risk of cross-contamination using this process is relatively low, initiating
blanks and laboratory control samples at the start of the chemical separation
process is acceptable. If sufficient sample is available, a duplicate sample should be
prepared from the two discarded quarters of the final split of the coning and
quartering procedure.
A10. Procedure
NOTE: This method ensures that only disposable equipment comes in contact with sample materials
to greatly minimize the risk of sample cross-contamination and concerns about adequate cleaning of
equipment. Under certain circumstances (disposable sieves are not available, for example), careful,
thorough cleaning of the sieves with water and the ethanol may be an option.
A10.1. If necessary, reduce the concrete or brick particle diameter to less than -25 mm
using a hydraulic press, mallet, or alternate equipment capable or reducing the
fragment size.
A10.2. Estimate the total volume of sample, as received.
NOTE: If the sample is dry, the risk of resuspension and inhalation of the solids may be
determined to be unacceptable. In such cases, the entire sample may be processed in a larger
can. The drying and milling time will be increased, and more grinding media will be
required to obtain a satisfactory result.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
NOTE: The next step uses absorbent paper in the reverse fashion for the normal use of this
type of paper; it allows for a smooth division of the sample and control of contamination.
Al 0.2.1. Spread a large piece of plastic backed absorbent paper, plastic side up
in a hood.
A10.2.2. If the sample volume is less than 450 mL, there is no benefit to coning
and quartering.6
A10.2.2.1. Carefully pour the sample onto the paper.
Al0.2.2.2. Remove extraneous material, such as rocks or debris,
unless the project requires that such material be processed
as part of the sample. Continue with Step A10.2.5.
A10.2.3. If the sample volume is greater than -450 mL, carefully pour the entire
sample into a cone onto the paper.
Remove extraneous material, such as rocks or debris unless the project
requires that such material be processed as part of the sample.
A10.2.4. If levels of gross activity in the sample permit, the sample is split at
least twice using the coning and quartering steps that follow.
NOTE: Unused quarters are considered representative of the original sample and
may be reserved for additional testing. The process should be carried out
expediently to minimize loss of volatile components in the sample, especially if
volatile components or percent solids are to be determined.
A10.2.4.1. Spread the material into a flat circular cake of soil using a
tongue depressor or other suitable disposable implement.
Divide the cake radially and return two opposing quarters
to the original sample container.
Al0.2.4.2. Reshape the remaining two quarters into a smaller cone,
and repeat Step A10.2.2.1 until the total volume of the
remaining material is approximately 100-150 mL.
NOTE: Tare the can and lid together. Do not apply an adhesive
label. Rather, la bel the can with permanent marker since the can
will be placed in a drying oven. The lid should be labeled
separately since it will be removed from the can during drying.
A10.2.5. Transfer the coned and quartered sample to a tared, labeled 1-pint paint
can. If the total volume was less than -450 mL, transfer the entire
sample to a tared, labeled 1-quart paint can.
NOTE: Constant mass may be determined by removing the container from the
oven and weighing repeatedly until the mass remains constant with within 1% of
the starting mass of the sample. This determination may also be achieved
6 International Union of Pure and Applied Chemistry (IUPAC). 1997. Compendium 1675 of Chemical Terminology,
2nd ed. (the "Gold Book"). Compiled by A. D. (Reference A16.1).
September 2014 47
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
operationally by observing the time needed to ensure that 99% of all samples will
obtain constant mass.
A10.3. Place the can (without lid) in an oven at 110 ± 10 °C and dry the concrete or brick
to constant mass.
NOTE: Concrete or brick samples may be dry enough such that heating prior to
homogenizing the sample is not required.
A10.4. Weigh the combined mass of the can, sample, and lid. If the percent solids are
required see Section A12.1 calculations. Remove can from oven and allow to
cool.
A10.5. Add five 1.5 cm stainless steel or ceramic balls or rods to the can. Replace the lid
and seal well.
A10.6. Shake the can and contents for 5 minutes, or longer, as needed to produce a
finely-milled, well-homogenized, sample.
NOTE: Although the precise particle size of the milled sample is not critical, complete
pulverization and fine particle size facilitates representative sub-sampling and subsequent
fusion or digestion processes. A qualitative standard can be prepared by passing quartz sand
or other milled material through a 50-mesh and then a 100-mesh screen. The portion of the
sample retained in the 100 mesh screen can be used as a qualitative visual standard to
determine if samples have been adequately pulverized.
A10.7. Visually compare the resulting milled sample to a qualitative 50-100 mesh
pulverized sample (-150-300 um or 50-100 mesh using the Tyler screen scale).
The process is complete once 95% of the sample (or greater) is as fine, or finer,
than the qualitative standard. If, by visual estimation, more than -5% of total
volume of the particles in the sample appear to be larger than the particle size in
the standard, return the sample to the shaker and continue milling until the process
is complete.
A10.8. Following milling, a small fraction of residual larger particles may remain in the
sample.
A10.8.1. If the sample was collected close to the epicenter of an RDD or IND
explosion, it may also contain particles of contaminant referred to as
"discrete radioactive particles" or DRPs. In such a case, the larger
particles should be isolated by passing through a disposable 48 mesh
screen and checked for radioactivity. DRPs are readily identified by
their very high specific activity which is detectable using hand-held
survey equipment such as a thin-window G-M probe held within an
inch of the particles.
A10.8.1.1. If radioactivity is clearly detected, the sieved material is
returned to the can and ball milled until the desired mesh
is obtained. In some cases, these materials may be
resistant to further pulverization and may need to be
processed according to a method specially designed to
address highly intractable solids.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
A10.8.1.2. If the presence of DRPs is of no concern, the larger
particles need not be included in subsequent subsamples
taken for analysis. It may be possible to easily avoid
including them during aliquanting with a disposable
scoop. If not, however, they should be removed by sieving
through a nominal 50 mesh screen (disposable) prior to
further subsampling for subsequent analyses.
A10.9. Sample fines may be stored in, and aliquanted directly from, the container used
for drying and pulverization.
Al 1. Calibration and Standardization
Al 1.1. Balances used shall be calibrated using National Institute of Standards and
Technology (NIST)-traceable weights according to the process defined by the
laboratory's quality manual.
A12. Data Analysis and Calculations
A12.1. The percent solids (dry-to-as-received mass ratio) for each sample is calculated
from data obtained during the preparation of the sample as follows:
% Solids = M^"_Mt- Xl0()
"^-asrec "-'-"tare
Where:
Mdry = mass of dry sample + labeled can + lid (g)
Mtare = tare mass of labeled can + lid (g)
Masrec = mass of sample as received + labeled can + lid (g)
A12.2. If requested, convert the equivalent mass of sample, as received, to dry mass. Dry
mass is calculated from a measurement of the total as received mass of the sample
received as follows:
T^ c i - - i . ™ % Solids
Dry SampleEquivalent = Mtotal.asrec x———
Where:
Mtotai-as rec. = total mass of sample, as received (g)
A12.3. Results Reporting
A12.3.1. The result for percent solids and the approximate total mass of sample
as received should generally be reported for each result.
Al3. Method Performance
A13.1. Results of method validation performance are to be archived and available for
reporting purposes.
A13.2. Expected turnaround time is about 3 hours for an individual sample and about 4
hours per batch.
A14. Pollution Prevention.
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Rapid Method for Sodium Hydroxide Fusion of Concrete and Brick Matrices Prior to Am, Pu, Sr, Ra, and U Analyses
Not applicable
A15. Waste Management
Al5.1. All radioactive and other regulated wastes shall be handled according to
prevailing regulations.
A16. References
A16.1. International Union of Pure and Applied Chemistry (IUPAC). 1997. Compendium
of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D.
McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford. XML
on-line corrected version: http://goldbook.iupac.org/C01265.html. (2006) created
by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. Last update: 2010-
12-22.
A16.2. ALS Laboratories, Fort Collins, SOP 736.
A16.3. MARLAP. Multi-Agency Radiological Laboratory Analytical Protocols Manual.
2004. Volumes 1-3. Washington, DC: EPA 402-B-04-001A-C, NUREG 1576,
NTIS PB2004-105421, July. Available at: www.epa.gov/radiation/marlap.
A16.4. ASTM C 999-05, "Standard Practice for Soil Sample Preparation for the
Determination of Radionuclides," Volume 12.01, ASTM, 2005.
September 2014 50
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
Attachment III:
Rapid Radiochemical Method for Total Radiostrontium (Sr-90) in Building
Materials for Environmental Remediation Following Radiological Incidents
1. Scope and Application
1.1. The method will be applicable to samples where the source of the contamination is
either from known or unknown origins. The method provides a very rapid screen for
total radiostrontium (89Sr + 90Sr) in building materials samples, such as concrete and
brick.
1.2. This method is specific for beta-emitting isotopes of strontium in building materials
such as concrete and brick. It uses rapid digestion and precipitation steps to
preconcentrate strontium isotopes, followed by final purification using Sr Resin (see
footnote on next page) to remove interferences.
1.3. This method uses rapid radiochemical separations techniques for the determination of
beta-emitting strontium radioisotopes in concrete or brick samples following a
nuclear or radiological incident.
1.4. The method is capable of satisfying a required method uncertainty for 90Sr (total as
90Sr) of 0.32 pCi/g at an analytical action level (AAL) of 2.44 pCi/g, a required
relative method uncertainty (cpMn) of 13% above the AAL, and a MDC of 0.40 pCi/g.
To attain the required method uncertainty at the AAL, a sample weight of 1.5 g and a
count time of approximately 1.5 hours are recommended. The sample turnaround
time and throughput may vary based on additional project measurement quality
objectives (MQOs), the time for analysis of the final counting form, and initial
sample volume. The method must be validated prior to use following the protocols
provided in Method Validation Guide for Qualifying Methods Used by Radiological
Laboratories Participating in Incident Response Activities (Reference 16.1).
1.5. This method is intended to be used for building materials. The rapid 90Sr method was
initially validated for concrete building materials following the guidance presented
for "Level E Method Validation: Adapted or Newly Developed Methods, Including
Rapid Methods" in Method Validation Guide for Qualifying Methods Used by
Radiological Laboratories Participating in Incident Response Activities (Reference
16.1) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical Protocols
Manual (EPA 2004, Reference 16.2). Subsequent building material matrices were
validated at Level C ("Similar Matrix/New Application").
1.6. Other solid samples such as soil can be digested using the rapid sodium hydroxide
fusion procedure as an alternative to other digestion techniques, but the laboratory
will have to validate this procedure.
2. Summary of Method
2.1. Strontium is collected and purified from the building materials sample matrix using
sodium hydroxide fusion (Reference 16.3) and purified from potentially interfering
radionuclides and matrix constituents using a strontium-specific, rapid chemical
September 2014 51
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
separation method. The sample is equilibrated with strontium carrier, and
preconcentrated by Sr/CaCOs coprecipitation from the alkaline fusion matrix. The
carbonate precipitate is dissolved in HC1 and strontium is precipitated with calcium
fluoride to remove silicates. The precipitate is dissolved in strong nitric acid and the
solution is passed through a Sr Resin extraction chromatography column7 that
selectively retains strontium while allowing most interfering radionuclides and matrix
constituents to pass through to waste. If present in the sample, residual plutonium and
several interfering tetravalent radionuclides are stripped from the column using an
oxalic/nitric acid rinse. Strontium is eluted from the column with 0.05M HNCb and
taken to dryness in a tared, stainless steel planchet. The planchet containing the
strontium nitrate precipitate is weighed to determine the strontium yield.
2.2. The sample test source is promptly counted on a gas flow proportional counter to
determine the beta emission rate, which is used to calculate the total radiostrontium
activity.
2.2.1. The same prepared sample test source can be recounted after -10 days to
XQ QO
attempt to differentiate Sr from Sr. If the initial and second counts agree
(based on the expected ingrowth of 90Y), this is an indication that 89Sr is not
present in significant amounts relative to 90Sr (within the uncertainty of the
measurement).
2.2.2. Computational methods are available for resolving the concentration of 89Sr
and 9 Sr from two sequential counts of the sample. An example of an
approach that has been used successfully at a number of laboratories is
presented in Appendix B to this method. It is the responsibility of the
laboratory, however, to validate this approach prior to its use.
2.2.3. It is also possible to determine 89Sr more rapidly using Cerenkov counting if
significant amounts of 89Sr are suspected; this method must be validated
independently. The minimum detectable activity (MDA) levels with
Cerenkov counting, however, will be higher than of determination with gas
proportional counting and may or may not meet measurement quality
objectives.
3. Definitions, Abbreviations, and Acronyms
3.1. Analytical Protocol Specification (APS). The output of a directed planning process
that contains the project's analytical data needs and requirements in an organized,
concise form.
3.2. Analytical Action Level (AAL). The term analytical action level is used to denote the
value of a quantity that will cause the decision-maker to choose one of the alternative
actions.
7 Sr-Resin™ is a proprietary extraction chromatography resin consisting of octanol solution of 4,4'(5')-bis (t-butyl-
cyclohexanol)-18-crown-6-sorbed on an inert polymeric support. The resin can be employed in a traditional
chromatography column configuration (gravity or vacuum) or in a flow cartridge configuration designed for use
with vacuum box technology. Sr-Resin™ is available from Eichrom Technologies, Lisle, IL. Throughout the
remainder of the method, the terms "Sr-Resin" or "Sr-cartridge" will be used for Sr-Resin™.
September 2014 52
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
3.3. Discrete Radioactive Particles (DRPs or "hot particles"). Particulate matter in a
sample of any matrix where a high concentration of radioactive material is contained
in a tiny particle (um range).
3.4. Laboratory Control Sample (LCS). A standard material of known composition or an
artificial sample (created by fortification of a clean material similar in nature to the
sample), which is prepared and analyzed in the same manner as the sample. In an
ideal situation, the result of an analysis of the laboratory control sample should be
equivalent to (give 100 percent of) the target analyte concentration or activity known
to be present in the fortified sample or standard material. The result normally is
expressed as percent recovery.
3.5. Matrix Spike (MS). An aliquant of a sample prepared by adding a known quantity of
target analytes to specified amount of matrix and subjected to the entire analytical
procedure to establish if the method or procedure is appropriate for the analysis of the
particular matrix.
3.6. Multi-Agency Radiological Analytical Laboratory Protocols (MARLAP) Manual
provides guidance for the planning, implementation, and assessment phases of those
projects that require the laboratory analysis of radionuclides (Reference 16.2).
3.7. Measurement Quality Objective (MQO). MQOs are the analytical data requirements
of the data quality objectives and are project- or program-specific. They can be
quantitative or qualitative. MQOs serve as measurement performance criteria or
objectives of the analytical process.
3.8. Radiological Dispersal Device (ROD), i.e., a "dirty bomb." This device is an
unconventional weapon constructed to distribute radioactive material(s) into the
environment either by incorporating them into a conventional bomb or by using
sprays, canisters, or manual dispersal.
3.9. Required Method Uncertainty (MMR)- The required method uncertainty is a target value
for the individual measurement uncertainties and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method
uncertainty is applicable below an AAL.
3.10. Relative Required Method Uncertainty ((PMR). The relative required method
uncertainty is the MMR divided by the AAL and is typically expressed as a percentage.
It is applicable above the AAL.
3.11. Sample Test Source (STS). This is the final form of the sample that is used for
nuclear counting. This form is usually specific for the nuclear counting technique in
the method, such as a solid deposited on a filter for alpha spectrometry analysis.
3.12. Total Radiostrontium (also called Total Strontium): A radiological measurement that
OQ Qf\
does not differentiate between Sr and Sr. The assumption is that all of the
on RQ
strontium is in the form of Sr. When it is certain that no Sr is present, the total
QO
radiostrontium activity is equal to the Sr activity and may be reported as such.
3.13. Working Calibration Source (WCS): A prepared source, made from a certified
reference material (standard), including those diluted or prepared by chemical
procedure, for the purpose of calibrating an instrument.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
4. Interferences
4.1. Radiological
4.1.1. Count results should be monitored for detectable alpha activity and
appropriate corrective actions taken when observed. Failure to address the
presence of alpha emitters in the sample test source may lead to high result
bias due to alpha-to-beta crosstalk.
4.1.1.1. Elevated levels of radioisotopes of tetravalent plutonium,
neptunium, cerium, and ruthenium in the sample may hold up on
the column and co-elute with strontium. The method employs an
oxalic acid rinse that should address low to moderate levels of
these interferences in samples.
The resin has a higher affinity for polonium than strontium at
low nitric acid concentrations but only minimal retention in 8M
HNOs. If there were any residual Po (IV) retained, it would
likely be removed using the 3M HNOs-O.OSM oxalic acid rinse.
4.1.2. Significant leveis of 89Sr in the sample will interfere with the total
radiostrontium analysis.
QQ
4.1.2.1. The absence of higher activities of interfering Sr may be
detected by counting the sample test source quickly after initial
separation (minimizing ingrowth of 90Y), and then recounting the
sample test source after 1-21 days to verify that the calculated
activity (based on the expected ingrowth of 90Y) does not change
OQ
significantly. The presence of only Sr may be indicated when
the calculated activity of the second count is less than that of the
first count by an amount greater than that which can be attributed
to statistical variation in the two analyses. However, the second
OQ
count activity is a complex function of the amount of the Sr
present, the ingrowth of the 90Y from 90Sr and the time between
the first and second counts.
4.1.2.2. Alternatively, Appendix B provides a numerical approach for the
isotopic determination 89Sr and 90Sr from two sequential counts
of the sample, one immediately following separation, and one
after a delay to allow for ingrowth of 90Y and decay of 89Sr.
910
4.1.3. High levels of Pb may interfere with low-level strontium analysis due to
ingrowth of short-lived 210Bi during chemical separations, where Pb is
retained by Sr Resin but is not eluted. If 210Pb is known to be present in
samples, minimizing the time between the final rinse and the elution of
910
strontium to less than 15 minutes will maintain levels of interfering Bi to
less than 0.1% of the 210Pb activity present. The presence or absence of
interfering 210Bi may be determined by recounting the sample test source to
elution step if 214Pb (half life-26.8 minutes) makes it to the Sr Resin. In this
case, holding the samples until the 214Bi decays (~2 hours) may be
verify the half-life of the nuclide present. Bi-214 also can grow in during the
elution stej
case, holdi
advisable.
September 2014 54
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
99R™, 99zl 919
4.1.4. High levels of Th or its decay progeny Ra and Pb may interfere with
low-level strontium determinations due to ingrowth of short-lived decay
products during chemical separations. Monitoring count data for alpha
activity may provide indications of interferences. Minimizing the time
between the final rinse and the elution of strontium from the column to 5
minutes should maintain levels of interfering 212Pb and 208T1 to less than 2%
of the parent nuclide activity. The presence or absence of 212Pb may be
determined by recounting the sample test source to verify the half-life of the
nuclide present.
4.1.5. Levels of radioactive cesium or cobalt in excess of approximately 103 times
the activity of strontium being measured may not be completely removed
and may interfere with final results. Column rinsing to remove interferences
may be increased to minimize interference if high levels of cesium or cobalt
are known to be present. Changing cartridge connector tips and/or column
reservoirs prior to final elution of strontium from Sr Resin can facilitate
removal of sample matrix interferences. It may also be possible to increase
the nitric acid in the eluted Sr fraction to 8M HNCb and reprocess the
sample through the column separation method again.
4.2. Non-Radiological
4.2.1. Stable strontium present in the concrete, brick or other solid sample at levels
that are significant relative to the stable Sr carrier added will increase the
apparent gravimetric yield and cause a negative bias in the final results. If
the quantity of native strontium in the sample aliquant exceeds -5% of the
expected strontium carrier mass, chemical yield measurements will be
affected unless the native strontium is accounted for in the yield
calculations.
4.2.2. The native strontium content in the sample may be determined by an
independent spectrometric measurement (such as inductively coupled
plasma - atomic emission spectroscopy [ICP-AES], etc.) or by taking an
aliquant and processing the sample without the addition of strontium carrier
to obtain an estimate of the native strontium content of the sample.
4.2.3. Sr Resin has a greater affinity for lead than for strontium. Lead will
quantitatively displace strontium from the column when the two are present
in combined amounts approaching or exceeding the capacity of the column.
If the combined quantity of lead and strontium carrier in the sample exceeds
the capacity of the column, decreased strontium yields will be observed.
High lead levels are not typically seen in building materials samples.
However, decreasing the sample size will help address samples with
elevated levels of lead.
4.2.4. High levels of calcium, barium or potassium may compete slightly with
strontium for uptake on the resin, possibly leading to low chemical yield. If
these interfering matrix constituents are present in the final sample test
source, yield results will overestimate the true strontium yield and cause a
low result bias.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
4.2.5. Rinsing Sr Resin with 8M HNCb minimizes retention of Ba, K ions which
have more retention at lower nitric acid levels to optimize removal of
interferences.
4.2.6. The final solids on the planchets containing strontium nitrate should be
white to very light brown. A significant brown color could indicate
formation of iron oxide solids from the stainless steel planchets. This can
cause a positive bias in the gravimetric chemical yields. Annealing the
planchets properly minimizes the formation of iron oxide solids (Step 6.8).
5. Safety
5.1. General
5.1.1. Refer to your safety manual for concerns of contamination control, personal
exposure monitoring and radiation dose monitoring.
5.1.2. Refer to your laboratory's chemical hygiene plan for general chemical
safety rules.
5.2. Radiological
5.2.1. Hot Particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles"
(DRPs), will be small, on the order of 1 mm or less. Typically,
DRPs are not evenly distributed in the media and their radiation
emissions are not uniform in all directions (anisotropic).
5.2.2. For samples with detectable activity concentrations of these radionuclides,
labware should be used only once due to potential for cross contamination.
5.3. Procedure-Specific Non-Radiological Hazards
None noted.
6. Equipment and supplies
6.1. Analytical balance with 10^ g readability or better.
6.2. Centrifuge able to accommodate 225 mL and 50 mL centrifuge tubes.
6.3. Centrifuge tubes, 50 mL and 225 mL.
6.4. Hot plate.
6.5. Low-background gas flow proportional counter.
6.6. 100 uL, 200 uL, 500 uL, and 1 mL pipets or equivalent and appropriate plastic tips.
6.7. 1-10 mL electronic pipet.
6.8. Stainless steel planchets or other sample mounts: ~2-inch diameter, annealed at 530-
550 °C or higher in a furnace for -3.5 to 4 hours with a volume of ~5 mL. Planchets
annealed properly will typically have a bronze/brown color. Do not overheat as the
planchets will become more susceptible to acid degradation and iron oxide formation.
September 2014 56
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
6.9. Tips, white inner, Eichrom part number AC-1000-IT, or PFA 5/32" x i/4" heavy-wall
tubing connectors, natural, Ref P/N 00070EE, cut to 1 inch, Cole Farmer, or
equivalent.
6.10. Tips, yellow outer, Eichrom part number AC-1000-OT, or equivalent.
6.11. Vacuum box, such as Eichrom part number AC-24-BOX, or equivalent.
6.12. Vacuum pump or laboratory vacuum system.
7. Reagents and Standards
NOTES:
All reagents are American Chemical Society (ACS) reagent grade or equivalent unless otherwise
specified.
Unless otherwise indicated, all references to water should be understood to mean Type I reagent water
(ASTM D1193, Reference 16.5). All solutions used in microprecipitation should be prepared with water
filtered through a 0.45 um (or better) filter.
7.1. Type I reagent water as defined in ASTM Standard Dl 193 (Reference 16.5).
7.2. Aluminum nitrate (A1(NO3)3' 9H2O).
7.2.1. Aluminum nitrate solution, 2M (A1(NO3)3): Add 750 g of aluminum nitrate
(A1(NO3)3' 9H2O) to -700 mL of water and dilute to 1 L with water.
7.3. Ethanol, reagent (^HsOH): Available commercially (or mix 95 mL 100% ethanol
and 5 mL water).
7.4. Nitric Acid, HNO3 (15.8M), concentrated, available commercially.
7.4.1. Nitric acid (8M): Add 506 mL of concentrated HNO3 to 400 mL of water
and dilute to 1 L with water.
7.4.2. Nitric acid (3M): Add 190 mL of concentrated HNO3 to 800 mL of water
and dilute to 1 L with water.
7.4.3. Nitric acid (0.1M): Add 6.4 mL of concentrated HNO3 to 900 mL water.
Dilute to 1 L with water.
7.4.4. Nitric acid (0.05M): Add 3.2 mL of concentrated HNO3 to 900 mL water.
Dilute to 1 L with water.
7.5. Nitric acid (3M)/oxalic acid solution (0.05M): Add 190 mL of concentrated HNO3
(7.3) and 6.3 g of oxalic acid dihydrate (C2H2CV2H2O), to 800 mL of demineralized
water and dilute to 1 L with de-ionized water.
Sr Resin columns, -1.00 g resin, 3 mL, small particle size (50-100 um), in
appropriately sized column or stacked 2 mL+ 1 mL pre-packed cartridges. (Available
from Eichrom Technologies, Inc., Lisle IL.)
7.7. Strontium carrier solution, 7 mg/mL in 0.1M HNO3, traceable to a national standards
body such as NIST or standardized at the laboratory by comparison to independent
standards.
7.7.1. Option 1: Dilute elemental strontium standard to a concentration of 7.00
mg/mL (or mg/g) in 0.1 M HNO3. Verify per Step 7.7.3.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
7.7.2. Option 2: To -200 mL de-ionized water, add 6.3 mL HNO3 and
approximately 16.90 g of strontium nitrate (Sr(NC>3)2 dried to constant mass
and the mass being determined to at least 0.001 g). Dilute to 1000 mL with
water. Calculate the amount of strontium nitrate/mL actually present and
verify per Step 7.7.3.
7.7.3. Prior to use, verify the strontium carrier solution concentration by
transferring at least five 1.00-mL portions of the carrier to tared stainless
steel planchets. Evaporate to dryness on a medium heat on a hotplate using
the same technique as that used for samples (Heat 5 minutes after dryness is
reached to ensure complete dryness). Allow to cool and weigh as the nitrate
to the nearest 0.1 mg. The relative standard deviation for replicates should
be less than 5% and the average residue mass within 5% of the expected
value.
7.8. 90Sr standard solution (carrier free), traceable to a national standards body such as
NIST, in 0.5M HNO3 solution.
8. Sample Collection, Preservation, and Storage
Not Applicable.
9. Quality Control
9.1. Batch quality control results shall be evaluated and meet applicable Analytical
Protocol Specifications (APS) prior to release of unqualified data. In the absence of
project-defined APS or a project-specific quality assurance project plan (QAPP), the
quality control sample acceptance criteria defined in the laboratory quality manual
and procedures shall be used to determine acceptable performance for this method.
9.1.1. A laboratory control sample (LCS) shall be run with each batch of samples.
The concentration of the LCS should be at or near the action level or a level
of interest for the project.
9.1.2. One method blank shall be run with each batch of samples fused using the
procedure Rapid Method for Sodium Hydroxide Fusion of Concrete and
Brick Matrices Prior to Americium, Plutonium, Strontium, Radium, and
Uranium Analyses (Reference 16.3). If analyte-free blank material is not
available and an empty crucible is used to generate a reagent blank sample,
it is recommended thatlOO mg calcium be added as calcium nitrate to the
empty crucible as blank simulant. This addition facilitates strontium
carbonate precipitations from the alkaline fusion matrix.
9.1.3. One laboratory duplicate shall be run with each batch of samples. The
laboratory duplicate is prepared by removing an aliquant from the original
sample container.
9.1.4. A matrix spike sample may be included as a batch quality control sample if
there is concern that matrix interferences, such as the presence of elemental
strontium in the sample, may compromise chemical yield measurements, or
overall data quality.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
10. Calibration and Standardization
on
10.1. The effective detection efficiency for total radiostrontium (referenced to Sr) is
QO QO
calculated as the weighted sum of the Sr and Y efficiencies that reflects the
relative proportions of 90Y and 90Sr based on the 90Y ingrowth after 90Sr separation.
10.2. Set up, operate, and perform quality control for gas-flow proportional counters (GPC)
in accordance with the laboratory's quality manual and standard operating
procedures, and consistent with ASTM Standard Practice D7282, Sections 7-13
(Reference 16.4).
on
10.3. See Appendix A for details on calibration/standardization of the GPC specific to Sr
and 90Y.
11. Procedure
11.1. Initial Sample Preparation for 89Sr + 90Sr
11.1.1. 89>90sr may be preconcentrated from building material samples using the
separate procedure (Reference 16.3), which fuses the samples using rapid
NaOH fusion followed by carbonate and fluoride precipitations to
on Q/-\
preconcentrate ' Sr from the hydroxide matrix.
NOTE: The fusion procedure provides a column load solution for each sample
(consisting of 20 mL of 8M HNO3-0.5M A1(NO3)3), ready for column separation on Sr
Resin.
11.1.2. This separation can be used with other solid sample matrices if the initial
sample preparation steps result in a column load solution containing ~8M
HNO3- 0.5M A1(NO3)3 is used.
11.1.3. A smaller volume of the total load solution may be taken and analyzed as
needed for very high activity samples, with appropriate dilution factor
calculations applied.
11.2. Rapid Sr Separation using Sr Resin
11.2.1. Set up vacuum box
11.2.1.1. Place the inner tube rack (supplied with vacuum box) into the
vacuum box with the centrifuge tubes in the rack. Place the lid
onto the vacuum box system.
11.2.1.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit in the inner white tip into each yellow tip.
11.2.1.3. For each sample solution, place the Sr Resin cartridges (2 mL+1
mL cartridges) on to the inner white tip.
11.2.1.4. Place reservoirs on the top end of the Sr Resin cartridge.
11.2.1.5. Turn the vacuum on (building vacuum or pump) and ensure
proper fitting of the lid.
IMPORTANT: The unused openings on the vacuum box should be sealed.
Yellow caps (included with the vacuum box) can be used to plug unused
white tips to achieve a good seal during the separation. Alternately,
plastic tape can be used to seal the unused lid holes as well.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
11.2.1.6. Add 5 mL of 8M HNOs to the column reservoir to precondition
the Sr Resin cartridges.
11.2.1.7. Adjust the vacuum to achieve a flow-rate of ~1 mL/min.
NOTE: Unless otherwise specified in the procedure, use a flow rate of ~1
mL/min for load and strip solutions and ~2-3 mL/min for rinse solutions.
11.2.2. Sr Resin Separation
11.2.2.1. Transfer each sample solution from the fusion procedure
(Reference 16.3) into the appropriate reservoir. Allow solution to
pass through the Sr Resin cartridge at a flow rate of ~1 mL/min.
11.2.2.2. Add 5 mL of 8M HNO3 to each beaker/tube (from Step 11.2.2.1)
as a rinse and transfer each solution into the appropriate reservoir
(the flow rate can be adjusted to ~2 mL/min).
11.2.2.3. Add 15 mL of 8M HNOs into each reservoir as second column
rinse (flow rate -3-4 mL/min).
11.2.2.4. Turn off vacuum and discard rinse solutions.
11.2.2.5. Add~5 mL 3M HNO3 - 0.05M oxalic acid solution to each
column (flow rate -1-2 mL/min).
11.2.2.6. Add 5 mL of 8M HNCb into each reservoir as second column
rinse (flow rate ~3 mL/min).
11.2.2.7'. Discard column rinses.
11.2.2.8. Record time and date of the end of last rinse to the nearest 15
minutes as t\, "time of strontium separation."
11.2.2.9. Place clean 50 mL centrifuge tubes beneath the columns to catch
the strontium eluate before proceeding to the next step.
11.2.2.10. Elute strontium from the columns by adding 15 mL of 0.05M
HNO3 at~l mL/min.
11.2.2.11. Discard Sr Resin cartridges.
11.2.3. Preparation of the STS and determination of chemical yield
11.2.3.1. Clean and label a stainless steel planchet for each STS.
11.2.3.2. Weigh and record the tare mass of each planchet to the nearest
0.1 mg.
11.2.3.3. Transfer the strontium eluate from Step 11.2.2.10 to the planchet
and take to dryness on a hotplate (medium heat) to produce a
uniformly distributed residue across the bottom of the planchet.
NOTE: A few mL at a time typically is added to the planchet during
evaporation. Do not evaporate all the way to dryness to prevent
splattering. After adding all 15 mL, take the planchet all the way to
dryness.
11.2.3.4. Rinse tubes with ~2 mL 0.05M HNO3 and add to the planchet.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
11.2.3.5. Heat on hot plate for -5-10 minutes after initial dryness is
reached.
11.2.3.6. Allow planchets to cool.
11.2.3.7'. Weigh and record the gross mass of each planchet to the nearest
0.1 mg.
NOTE: If gravimetric yields are unusually high with the possibility of
moisture present, additional heating and reweighing should be
performed.
11.2.3.8. Calculate the chemical yield as presented in Step 12 of this
method.
11.3. Counting the Sample Test Source
11.3.1. On a calibrated gas-flow proportional detector that has passed all required
daily performance and background checks, count the STS for a period as
needed to satisfy MQOs.
OQ
11.3.1.1. If the presence of Sr cannot be excluded, and total
radiostrontium is being determined as a screen for the presence
of 89Sr or 90Sr, count the STS as soon as practicable after
QO
preparation to minimize the ingrowth of Y into the STS.
11.3.1.2. If the presence of 89Sr can be excluded, total radiostrontium will
provide isotopic 90Sr results and the STS may be counted at any
time after preparation (taking into account the appropriate
increase in activity due to 90Y ingrowth).
11.3.2. Calculate the total radiostrontium (90Sr) sample results using calculations
presented in Step 12.
11.3.3. Hold planchets for recounting as needed.
12. Data Analysis and Calculations
12.1. Calculation of Total Radiostrontium
12.1.1. When a sample is analyzed for total radiostrontium (equivalent 90Sr), the
effective efficiency is calculated as follows:
Sr — G Sr90 ' VA ^ I ^ & y90 \ /
where
£iotai sr = effective detection efficiency for total radiostrontium
on
referenced to Sr
£sr9o = final 90Sr detection efficiency
QO
£Y90 = final Y detection efficiency
AY9o = decay constant for 90Y, 3.005x 10"6 seconds (s)"1
t\ = date and time of the Sr/Y separation (s)
h = date and time of the midpoint of the count (s)
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
NOTE: The elapsed time between the sample count and the reference date must be
calculated using the same time units as the decay constant.
12.1.2. The standard uncertainty of the effective efficiency is calculated as follows:
(2)
where
NOTE: The terms w(£sr9o> £y9o) and r(sSr90, sV90) are derived during calibrations as
shown in Appendix A, Step A4.
12.1.3. The total radiostrontium activity concentration (^Ciotai sr) equivalent to 90Sr
is calculated as follows:
AC - ~
^ '-Total Sr
- oo v „* „ ,-,
2.22x£Ttl<, xYxWxDF
i oiai or
where
nC1 _ p~4r9ott~'o)
and where
RH = beta gross count rate for the sample (counts per minute
[cpm])
R\, = beta background count rate (cpm)
STotai sr = effective efficiency of the detector for total strontium
referenced to 90Sr
Y = fractional chemical yield for strontium
W = weight of the sample aliquant (g)
DF = correction factor for decay of the sample from its
reference date until the midpoint of the total strontium
count
ASr90 = decay constant for 90Sr, 7.642x 1(T10 s"1
to = reference date and time for the sample (s)
t\ = date and time of the Sr/Y separation (s)
NOTE: The elapsed time between the sample count and the reference date must be
calculated using the same time units as the decay constant
12. 1 .4. The standard counting uncertainty of the total radiostrontium activity
concentration, z/ccC^Crotai sr) is calculated as follows:
McC V^TotalSr) ~'
tb (4)
TotalSr
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
where:
4 = Duration of the sample count (min)
tb = Duration of the background subtraction count (min)
12.1.5. The combined standard uncertainty (CSU) for the total radiostrontium
activity concentration, uc(ACi0\a\ sr), is calculated as follows:
Mc (^^ Total Sr ) - -, McC G^ Total Sr ) +
where:
Total Sr
|
Y2 W2
Total Sr •* "
(5)
w(Y) = standard uncertainty of fractional chemical yield for strontium
w(W) = standard uncertainty of the weight of the sample aliquant (g)
12.1.6. If the critical level concentration (Lc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations:8
0.4x -^--1 + 0.677x 1 + ^ +1.645 x I (ft th +0.4)x-^x 1 + ^
U J 10 r ^ I
(6)
2.71:
MDC = -
f v / /'/ v f? v V^ v tr1^
ts xz,.z,z,x&TotalSr x/ xrr
12.2. Chemical Yield for Strontium
12.2.1. Calculate the chemical yield for strontium using the gravimetric data
collected in Step 11.2.3:
(7)
ccVc+cnW
where:
Y = strontium yield, expressed as a fraction
ms = mass of Sr(NC>3)2 recovered from the sample (mg)
77 ) = gravimetric factor for strontium weighed as the nitrate,
0.414
= Sr mass concentration in the strontium carrier solution
(mg/mL)
= volume of strontium carrier added to the sample (mL)
8 The formulations for the critical level and minimum detectable concentrations are based on the Stapleton
Approximation as recommended in MARLAP Section 20A.2.2, Equations 20.54 and 20A.3.2, and Equation 20.74,
respectively. The formulations presented assume a = 0.05, ft = 0.05 (with z\-a = ZJ_P = 1.645), and d = 0.4.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
cn = Sr mass concentration native to the sample - if
determined (mg/g)
W = weight of sample aliquant (g)
12.2.2. Calculate the standard uncertainty of the yield as follows:
c,,+c,
where
M(-) = standard uncertainty of the quantity in parentheses,
eses.
M(-) = standard uncertainty of the quantity in parentheses,
Mr(0 = relative standard uncertainty of the quantity in parenth
12.3. Results Reporting
12.3.1. Unless otherwise specified in the APS, the following items should be
reported for each result:
12.3.1.1. Result for total radiostrontium in scientific notation ±1 combined
standard uncertainty.
12.3.1.2. Weight of sample aliquant and any dilutions used.
12.3.1.3. Yield of tracer and its uncertainty.
12.3.1.4. Case narrative.
13. Method Performance
13.1. Results of method validation performance are to be archived and available for
reporting purposes.
13.2. Expected turnaround time per sample or per batch (See Step 17.5 for typical
processing times (assumes samples are not from RDD).
13.2.1. Preparation and chemical separations for a batch of 20 samples can be
performed by using a vacuum box system (24 ports each) simultaneously,
assuming 24 detectors are available. For an analysis of a 1-g sample
aliquant, sample preparation and digestion should take -2.5 h.
13.2.2. Purification and separation of the strontium fraction using cartridges and
vacuum box system should take -2.5 h.
13.2.3. Sample test source preparation takes -1.5 h.
13.2.4. A 60-90-minute counting time is sufficient to meet the MQO in Step 9.2,
assuming 1.5-g aliquant, a background of 1 cpm, detector efficiency of 0.4-
0.5, and radiochemical yield of at least 0.5.
13.3. Total radiostrontium (89Sr+90Sr) data reduction should be achievable between 5 and
8.5 hours after the beginning of the analysis, depending on batch size and count time.
13.4. The sample may be recounted following a delay of 10-21 days to differentiate the
OQ Q/\ Q|"\
Sr and Sr activities. If the source contains pure Sr, the total radiostrontium
activity calculated from the two counts should agree within the uncertainty of the
September 2014 64
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
measurements. Minimizing the time between the chemical separation of Sr and the
initial count, longer count times, and increasing the delay between the two counts,
will minimize the overall uncertainty of the data and provide more sensitive and
reliable measures of the radiochemical purity of the STS.
NOTE: The 89Sr and 90Sr may be determined from two consecutive counts of the source -
calculations are presented in Appendix B. This approach must be validated prior to use.
14. Pollution Prevention
14.1. The use of Sr Resin reduces the amount of acids and hazardous metals that would
otherwise be needed to co-precipitate and purify the sample and prepare the final
counting form.
15. Waste Management
15.1. Nitric acid and hydrochloric acid wastes should be neutralized before disposal and
then disposed in accordance with prevailing laboratory, local, state and federal
requirements.
15.2. Final precipitated materials may contain radiostrontium and should be treated as
radioactive waste and disposed in accordance with the restrictions provided in the
facility's radioactive materials license and any prevailing government restrictions.
15.3. Used resins and columns should be considered radioactive waste and disposed of in
accordance with restriction provided in the facility's radioactive materials license and
any prevailing government restrictions.
16. References
Cited References
16.1. U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for
Radiological Laboratories Participating in Incident Response Activities. Revision 0.
Office of Air and Radiation, Washington, DC. EPA 402-R-09-006, June. Available
at: www.epa.gov/narel.
16.2. Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP).
2004. EPA 402-B-1304 04-001 A, July. Volume I, Chapters 6, 7, 20, Glossary;
Volume II and Volume III, Appendix G. Available at:
www. epa. gov/radiation/marlap.
16.3. U.S. Environmental Protection Agency (EPA). 2014. Rapid Method for Sodium
Hydroxide Fusion of Concrete and Brick Matrices Prior to Americium, Plutonium,
Strontium, Radium, and Uranium Analyses. Revision 0, EPA 402-R-14-004. Office of
Air and Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.4. ASTM D7282 "Standard Practice for Set-Up, Calibration, and Quality Control of
Instruments Used for Radioactivity Measurements," ASTM Book of Standards 11.02,
current version, ASTM International, West Conshohocken, PA.
16.5. ASTM Dl 193, "Standard Specification for Reagent Water," ASTM Book of
Standards 11.02, current version, ASTM International, West Conshohocken, PA.
September 2014 65
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
Other References
16.6. Maxwell, S. 2006. "Rapid Column Extraction Method for Actinides and 89/90Sr in
Water Samples,"/. RadioanalyticalandNuclear Chemistry. 267(3): 537-543.
16.7. Maxwell, S., Culligan, B. and Noyes, G. 2010. Rapid method for actinides in
emergency soil samples, Radiochimica Ada. 98(12): 793-800.
16.8. Maxwell, S., Culligan, B., Kelsey-Wall, A. and Shaw, P. 2011. "Rapid
Radiochemical Method for Actinides in Emergency Concrete and Brick Samples,"
AnalyticaChimicaActa. 701(1): 112-8.
16.9. SR-04, "Radiochemical Determination of Radiostrontium in Water, Sea Water, and
Other Aqueous Media," Eastern Environmental Radiation Facility (EERF)
Radiochemistry Procedures Manual, Montgomery, AL, EPA 520/5-84-006 (August
1984).
16.10. SRW04-11, "Strontium 89, 90 in Water," Eichrom Technologies, Inc., Lisle, Illinois
(February 2003).
16.11. Nuclear data from NUDAT 2.3 and the National Nuclear Data Center at Brookhaven
National Laboratory; available at: www.nndc.bnl.gov/nudat2/indx dec.jsp, database
version of 6/30/2009.
16.12. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Americium-241 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R-14-007. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.13. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Pu-238 and Pu-239/240 in Building Materials for Environmental Remediation
Following Radiological Incidents. Revision 0, EPA 402-R-14-006. Office of Air and
Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.14. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Radium-226 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R-14-002. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.15. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Total Radiostrontium (Sr-90) in Building Materials for Environmental
Remediation Following Radiological Incidents. Revision 0, EPA 402-R-14-001.
Office of Air and Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.16. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Isotopic Uranium in Building Materials for Environmental Remediation
Following Radiological Incidents. Revision 0, EPA 402-R-14-005. Office of Air and
Radiation, Washington, DC. Available at: www.epa.gov/narel.
17. Tables, Diagrams, Flow Charts and Validation Data
17.1. Validation Data
This section intentionally left blank.
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
17.2. Nuclide Decay and Radiation Data
Table 17.2 - Decay and Radiation Data
Nuclide
90Sr
90y
89Sr
Half-life
(days)
1.052E+04
2.6667
50.53
X
(s-1)
7.642X10'10
3.005xlO"6
1.587xlO'7
Abundance
1.00
1.00
1.00
f-^max
(MeV[1])
0.546
2.280
1.495
A*
(MeV)
0.196
0.934
0.585
[1] MeV - mega electron volts
17.3. Ingrowth and Decay Curves and Factors
In-Growth Curve for 90Y in 90Sr
200 300 400 500
Time Elapsed After Sr-90 Separation (h)
^^^Y-90 Sr-90- • • Beta Activity
700
Total Beta Activity Ingrowth Factors for 90Y in 90Sr
Ingrowth time elapsed (hours)
Factor
Ingrowth time elapsed (hours)
Factor
0.25
0.003
144
0.790
2
0.021
192
0.875
4
0.042
240
0.926
12
0.122
320
0.969
24
0.229
400
0.987
48
0.405
480
0.994
72
0.541
560
0.998
96
0.646
640
0.999
Factor = (90 Y activity/90Sr activity at zero hours of ingrowth)
September 2014
67
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
o 0.5-
89 £
Decay Curve for Sr
100 200 300 400
Time Elapsed since collection (h)
— Sr-89 Activity
500
600
700
89 c
Decay Factors for avSr
Decay time elapsed (hours)
Factor
Decay time elapsed (hours)
Factor
0.25
1.000
144
0.921
2
0.999
192
0.896
4
0.998
240
0.872
12
0.993
320
0.833
24
0.986
400
0.796
48
0.973
480
0.760
72
0.960
560
0.726
96
0.947
640
0.694
Factor = (89Sr activity/89Sr activity at zero hours of ingrowth)
17.4. Decay Schemes for 89Sr and 90Sr
89Sr and 90Sr Decay Scheme
= l.l5MeV
= 50.53 d
f«=2.67 d
p = 0.55 MeV
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Rapid Radiochemical Method for Total Radiostrontium in Building Materials
17.5. Process Flow with Typical Processing Times
Separation Scheme and Timeline for Determination of
Strontium Isotopes in Building Materials Samples
Discard load and
rinse solutions
(Step 11.2.2.7)
Discard Sr Resin
(Step 11.2.2.11)
Rapid Fusion (See Separate Procedure)
1. Add Sr carrier and fuse with NaOH
2. Ca carbonate and Ca fluoride precipitations
3. Dissolve in nitric acid and aluminum nitrate (column
load solution)
Vacuum Box Setup (Step 11.2.1.3)
1. Place Sr cartridges (2mL+1mL) on box
2. Condition columns with 5mL 8M HNO3@1 mL/min
v
Load Sample to Sr Resin Cartridges (Step 11.2.2.1)
1. Load sample @1 mL/min
2. Beaker/tube rinse: 5mL 8M HNO3 @ ~2 mL/min
3. Column rinse: 15 mL 8M HNO3 @ 3^ mL/min
4. Column rinse: 5 mL 3M HNO3-0.05 oxalic acid @ 1-2
mL/min
5. Column rinse: 5 mL 8M HMOs @ ~3 mL/min
v
EluteSrfrom Resin (Step 11.2.2.10)
1. Add 15mL0.0.05M HNO3 @ 1 mL/min
2. Remove tubes for planchet mounting
Planchet Mounting (Step 11.2.3.3)
1. Add Sr eluate to planchet on hot plate, drying to low
volume, and adding more eluate
2. Rinse tubes with ~2 mL 0.0.05M HNO3 and add to
planchet
3. Heat to dryness on hotplate
4. Cool and weigh planchets
v
Count sample test source (STS)
by gas proportional counting as
needed (Step 11.3)
Elapsed Time
21/2 hours
23/4 hours
41/4 hours
5 hours
61/2 hours
71/2-81/2 hours
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
Appendix A:
Method and Calculations for Detector Calibration
on
Al. The effective detection efficiency for total radiostrontium (referenced to Sr) is calculated
on on
as the weighted sum of the Sr and Y efficiencies that reflects the relative proportions of
90Y and 90Sr based on the 90Y ingrowth after strontium separation.
NOTE: While 89Sr efficiency calibration is not needed unless 89Sr analysis will be performed,
instructions for preparation are provided to support the two count approach should this option be
desired.
ALL Due to the low mass of carrier used for this method, self-absorption effects may be
assumed to be constant. Calibrate each detector used to count samples according to
ASTM Standard Practice D7282, Section 16, "Single Point Efficiency or Constant
Test Mass for a Specific Radionuclide" and the instructions below.
Al .2. Prepare a blank and at least three working calibration sources (WCS) for 90Sr and
90Y, and 89Sr (if needed) as follows:
on RQ
Al .2.1. The Sr and Sr radioactive standard solutions used to prepare WCSs
shall be traceable to a national standards body such as NIST and shall
originate from a standards supplier (or lot) different from standards used
for calibration verification and batch quality controls. The standards
should be diluted in nitric acid.
Al.2.2. The planchets used for the sources shall be of the same size, materials and
type as those used for the analysis of STSs.
Al.2.3. Preparation of 89Sr WCSs (if needed): 89Sr standard solution (in 0.5M
HNOs) is evaporated to dryness in a stainless steel planchet as follows:
OQ
Al.2.3.1. For each Sr WCS to be prepared, and for the associated
blank, add strontium carrier to 15 mL of 0.05M HNOs in a
disposable 50 mL centrifuge tube. The amount of carrier
should be adjusted to approximate the amount expected to be
recovered from routine samples.
NOTES:
If the average recovery has not been determined, the laboratory may
assume 85% chemical yield for determining the amount of carrier to
use in Step Al.2.3.1.
If the 89Sr standard contains residual chloride, it will attack the surface
of the planchet and compromise the quality of the calibration standard.
In such cases, convert the aliquant of standard solution to a nitrate
system by adding 1 mL concentrated HNOs and taking to dryness 2
times prior to quantitatively transferring the solution to the planchet.
Al.2.3.2. For each WCS, add a precisely known amount of traceable 89Sr
solution to a 50 mL centrifuge tube. Sufficient activity must be
present at the point of the count to permit accumulation of
greater than 10,000 net counts in a counting period deemed to
be reasonable by the laboratory. The minimum activity used,
however, should produce WCS count rates at least 20 times the
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
background signal but not greater than 5000 counts per second
(cps).
Al .2.3.3. Mix the solution and quantitatively transfer each WCS and the
blank to respective clean stainless steel counting planchets
using three rinses of 0.05M FDSTCb.
Al .2.3 .4. Evaporate to dryness using the same techniques used for
sample test sources.
on
Al.2.3.5. For each detector to be calibrated, count three Sr WCSs for
sufficient time to accumulate at least 10,000 net counts.
Al .3 . Preparation of 90Sr and 90Y WCSs: Separate WCSs for 90Sr and 90Y are prepared by
chemically separating 90Y from a standard solution of 90Sr.
Al .3 . 1 . For each 90Sr WCS to be prepared, and for the associated blank, add 1 mL
of 7 mg/mL strontium carrier to a disposable 50-mL centrifuge tube
containing 10 mL 8M FDSTOs. The amount of carrier added should
correspond to that expected to be recovered from a routine sample.
NOTE: If the average recovery has not been determined, the laboratory may assume
85% chemical yield for determining the amount of carrier to use for Step Al.3.1.
3M HNO3 may be used instead of 8M HNO3, however Sr yields may be slightly less.
on on
Al.3.2. For each Sr WCS, add a precisely known amount of traceable Sr
solution to a 50-mL centrifuge tube containing 10 mL of 8M
Sufficient activity should be present at the point of the count to permit
accumulation of greater than 10,000 90Sr and 10,000 90Y net counts in the
respective sources in a counting period deemed to be reasonable by the
laboratory. The minimum activity used, however should produce WCS
count rates at least 20 times the background signal but not greater than
5000 cps.
Al.3.3. Set up one (2+1 mL) Sr Resin column for each 90Sr WCS and for the
associated blank. Condition each column with 5 mL of 8M FDSTCb.
Column effluents are discarded to waste.
Al .3 .4. Place a clean centrifuge tube under each column to catch all combined 90Y
effluents.
NOTE: Unless otherwise specified in the procedure, use a flow rate of ~1 mL/min for
load and strip solutions and ~3 mL/min for rinse solutions.
Al.3.5. Load the 90Sr solution onto the column at 1 drop/second or less (~1
on
mL/min). The load solution effluent containing Y is retained.
Al .3 .6. Rinse the centrifuge tube with three successive 2-mL portions of 8M
FDSTOs adding each of the rinses to the column after the previous rinse has
___ on
reached the upper surface of the resin. These effluents also contain Y
and are retained.
A 1.3. 7. Rinse the column with 10 mL of 8M FESTOs and retain the column
effluents containing 90Y. Record the date and time that the final rinse
solution leaves the column to the nearest 5 minutes as t\, "Time of 90Y
on
Separation." Remove the centrifuge tube that has the combined Y
September 2014 71
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
effluents. Place a clean tube under the column to catch the strontium
eluate in subsequent steps.
NOTE: From this point, 90Sr must be eluted, and the 90Sr WCS must be prepared
and counted as expeditiously as possible to minimize 90Y ingrowth and necessary
corrections to the efficiency. Counting of the 90Sr WCS should be completed, if
possible, within 3-5 hours but no longer than 10 hours from the time of 90Y
separation. If processing or counting capacity is limited, concentrate resources on
90Sr WCS and counting first. The 90Y WCS are not compromised by ingrowth but
must only be counted promptly enough to minimize decay and optimize counting
statistics.
Al.3.8. Strip strontium from each column by adding 15 mL of 0.05M HNOs to
each column, catching the effluents containing 90Sr in the centrifuge tube.
on on
Al .3 .9. Quantitatively transfer Sr and Y fractions to respective tared planchets
using three portions of 0.05M
Al.3.10. Evaporate to dryness using the same techniques used for sample test
sources, with the same heat time applied after dryness is reached.
NOTE: Gravimetric measurements may be performed following the counting to
minimize elapsed time between separation and counting.
Al .4. Weigh the 90Sr and 90Y WCS sources and calculate the net residue mass.
Al .4. 1 . The net mass of the strontium nitrate precipitate shall indicate near
quantitative yield of strontium of 95-103%. If strontium yield falls outside
this range, determine and address the cause for the losses and repeat the
process. The known activity of 90Sr in the standard is corrected for losses
based on the measured chemical yields of the strontium carrier.
Note that no correction shall be applied for values greater than 100% because this
will produce a negative bias in the calibrated efficiency.
Al .4.2. The net residue mass of the 90Y should be low. Higher residue mass may
indicate the breakthrough of strontium and will result in high bias in the
90Y efficiency, but it may simply be the result of corrosion of the stainless
planchet during evaporation of 8M HNOs, forming a small amount of iron
oxide. Lower Sr carrier yields on the Sr planchet would indicate the
present of Sr breakthrough.
NOTE: Formation of a small amount of iron oxide on the planchet during
evaporation may result in a slight mass on the 90Y planchet (~1 mg) but does not
affect the 90Y counting significantly.
Al .4.3 . Count three 90Sr WCS on each detector to be calibrated, for sufficient time
to accumulate at least 10,000 net counts.
Al .4.4. Count three 90Y WCS on each detector to be calibrated, for sufficient time
to accumulate at least 10,000 net counts.
Al .4.5. Count the associated blanks as a gross contamination check on the
process. If indications of contamination are noted, take appropriate
corrective actions to minimize spread and prevent cross-contamination of
other samples in the laboratory.
September 2014 72
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
Al .5. Verify the calibration of each detector according to ASTM Standard Practice
D7282, Section 16, and the laboratory quality manual and standard operating
procedures.
Al .6. Calculations and data reduction for 90Sr and 90Y calibrations and calibration
verifications are presented in Sections A2, A3, and A4. Calculations for total
radiostrontium are in Section 12 of the method.
on
A2. Calculation of Detection Efficiency for Sr
A2. 1 . Calculate the following decay and ingrowth factors for each WCS:
DFS = e-**»&-V (Al)
/FY90=l-e-A™('2-'l) (A2)
where
on
DFS = decay factor for decay of the Sr standard from its reference date
until the 90Sr/90Y separation
ingrowth factor for ingrowth of 90Y after the 90Sr/90Y separation
decay constant for 90Sr, 7.642x 1(T10 s"1
AY90 = decay constant for 90 Y, 3 .005 x 1 (T6 s"1
on
to = reference date and time for the Sr standard (s)
t\ = date and time of the Sr/Y separation (s)
QO
t% = date and time of the midpoint of the Sr count (s)
NOTE: The elapsed time between the sample count and the reference date must be calculated
using the same time units as the decay constant
A2.2. Calculate the 90Sr detection efficiency for each WCS:
R — R R
b
TJ7 xp ~ _ ^ __ JF
•" C •"
_ __ _ __ .
Sr90,i A ^ Tr j^^ •" Y90,; CY90 A ^ Tr j^^ •" Y90,; CY90
where
e&90,i = 9°Sr detection efficiency for the /* WCS
£Y90 = average 90Y detection efficiency (from Step A3.2)
Rs,i = beta gross count rate for the/'* WCS (cpm)
Rb = background count rate, in cpm
R^t = beta net count rate for the /' WCS (cpm)
^4Csr90std = activity concentration of the 90Sr standard solution on its
reference date (dpm/mL or dpm/g)
FS;; = amount (volume or mass) of the standard solution added to the
/*WCS(mLorg)
A2.3. Average the efficiencies determined in Step A2.2 for all the WCSs to obtain the
final detection efficiency for 90Sr.
1 -A
'V ^ / \ A \
GSi90 = GSi90 ~~ 2-i GSi90,i (A4)
September 2014 73
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
where
9°Sr detection efficiency determined for the f WCS in A2.2,
n = number of WCSs prepared and counted.
ulat
follows:
A2.4. Calculate the standard uncertainty of the average 90Sr detection efficiency as
Y90
IF Yso = — X^Y9o, = average value of 90Y ingrowth factors (A6)
and
u(-) = standard uncertainty of the value in parentheses,
Mr(-) = relative standard uncertainty of the value in parentheses.
on
A3. Detection Efficiency for Y
on
A3.1. Calculate the Y detection efficiency, 6^90,2, for each WCS,
sY9o. = ^"^ = ^' (A?)
^-"Sr90 std 's,i s,i ^"Sr90 std ^ ••' -
where
and
on
eY9o,; = Y detection efficiency determined for the WCS
Rsj = beta gross count rate for the /'th WCS (cpm)
Rb = background count rate, in cpm
Rn i = beta net count rate for the f WCS (cpm)
' Qj-\
ACs&o std = activity concentration of the Sr standard solution on its reference
date (disintegrations per minute per mL [dpm]/mL or dpm/g)
Fs,z = amount of the standard solution added to the/'* WCS (mL or g)
DFSj = combined correction factor for decay of the 90Sr standard in the f
WCS from its reference date until 90Y separation, and for the decay
of 90Y from its separation until the midpoint of the count
Asr90 = decay constant for 90Sr, 7.642x 1(T10 s"1
AY90 = decay constant for 90Y, 3.005x 1(T6 s"1
90
to = reference date and time for the Sr standard (s)
t\ = date and time of the 90Y separation (s)
on
h = date and time at the midpoint of the Y count (s)
NOTE: The elapsed time between the sample count and the reference date must be calculated using
the same time units as the decay constant
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
A3.2. Average the efficiencies determined in Step A3.1 to obtain the final detection
efficiency for 90Y.
1 "
SY90 = SY90 = ~ 2-iSY90,i (A")
n i=\
where
eY9o,; = 9°Y detection efficiency determined for the f WCS in Step A3.1
n = number of WCS prepared and counted
A3.3. The combined standard uncertainty of the average efficiency for 90Y including
uncertainty associated with the preparation of the calibration standards is calculated
as follows:
„-_ A^- v-ut<- °.*) (A10)
where
w(-) = standard uncertainty of the value in parentheses,
Mr(-) = relative standard uncertainty of the value in parentheses.
NOTE: The uncertainty of the net count rate, uRn^ includes the uncertainty of the background or
u2 (fiBji) = u2 (Rs) + u2 (fi6) = (Rs/ts) -
A4. Calculate the covariance and correlation coefficient for the 90Sr efficiency and the 90Y
efficiency:
M(%90^Y9o) = %9o£Y90Mr2(^CSr90Std)-(M2(£Y9o)-£Y90Mr2(^CSr90Std))/-FY90 (Al 1)
and
Si90 = Y90 ~ ~~7= - r~^ - 7
wO?Sr90)wO?Y90)
where
u(-,-) = estimated covariance of the two quantities in parentheses,
r(-,-) = estimated correlation coefficient of the two quantities in
parentheses,
u(-) = standard uncertainty of the quantity in parentheses,
ur(-) = relative standard uncertainty of the quantity in parentheses.
A5. Detection Efficiency for 89Sr (if needed for Appendix B Calculations)
A5. 1 . Calculate the detection efficiency, esr89,*, for each WCS as follows:
ssi,9l= R*'-Rb - = - ^ - (A13)
'
where
(A14)
and
89Sr detection efficiency for the f WCS
September 2014 75
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
= beta gross count rate for the f WCS (cpm)
= background count rate, in cpm
? std = activity concentration of the 89Sr standard solution on the reference
date (dpm/mL or dpm/g)
Fs,z = amount (volume or mass) of the standard solution added to the f
WCS (mL or g)
DFs,i = correction factor for decay of the 89Sr standard for the /* WCS
from its reference date until the midpoint of the sample count
ASr89 = decay constant for 89Sr, 1.58?x 10~7 s"1
OQ
^o = reference date and time for the Sr standard (s)
t\ = date and time at the midpoint of the 89Sr count (s)
OQ
detection efficiency for Sr.
A5.1.1. Average the efficiencies determined in Step A5.1 to obtain the final
>Sr89,i (A15)
II j=1
where
£sr89,z = 89Sr detection efficiency determined for the /'* WCS in Step A5.1,
n = number of WCSs prepared and counted.
OQ
A5.1.2. The combined standard uncertainty of the average efficiency for Sr
including uncertainty associated with the preparation of the calibration
standards is calculated as follows:
(A16)
where
u(-} = standard uncertainty of the value in parentheses,
wr(0 = relative standard uncertainty of the value in parentheses.
September 2014 76
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
Appendix B:
OQ Q|-|
Calculations for Isotopic Sr and Sr Results
OQ Q|"\
A numerical approach for determining Sr and Sr activity from a single sample is performed
by a number of laboratories. This presentation, however, allows a more rigorous evaluation of
uncertainties than commonly employed. Lacking this treatment, many labs have found that the
traditional approach (evaluating counting uncertainty for a single count only) has led to
overestimation of the quality of results, and to poor decisions regarding the presence or absence
of low activities of one radioisotope of strontium in the presence of elevated activities of the
second.
OQ Qf\
These calculations may be valuable to laboratories who wish to determine isotopic Sr and Sr
in a large number of samples with a minimum of additional effort beyond the initial preparation
and counting of total radiostrontium. Specifically, it involves performing a second count of the
same radiostrontium sample test source (STS) and mathematically resolving the activity of the
two isotopes. Although the STS may be recounted as soon as 1-2 days after the initial count,
resolution is optimized if the two counts span as large a range of the 90Y ingrowth as practicable.
The time elapsed between the chemical separation and the first count should be minimized, while
on on
the second count should optimally proceed as Y approaches secular equilibrium with Sr but
before significant decay of 89Sr has occurred, for example, after 3-5 half-lives of 90Y have
elapsed (1-2 weeks).
This section may not be employed without complete validation of the approach by the
on °>Q
laboratory, including testing with samples containing ratios of Sr relative to Sr varying from
pure 90Sr to pure 89Sr.
on °>Q
B1. The equations in this section are used to calculate the Sr and Sr activity of a sample
from data generated from two successive counts of the same radiostrontium sample test
source.
B1.1. For each of the two counting measurements (/'=!, 2), calculate the following decay
and ingrowth factors:
°} (Bl)
} (B2)
77 _
/Y90,! ~
where:
decay factor for decay of 89Sr from the collection date to the
midpoint of the /* count of the STS
decay factor for decay of 90Sr from the collection date to the
midpoint of the f count of the STS
on
combined decay and ingrowth factor for decay of Sr from the
collection date to the Sr/Y separation and ingrowth of 90Y from the
separation to the midpoint of the f count of the STS
September 2014 77
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
= decay constant for 89Sr = 1.587x10 7 s 1
= decay constant for 90Sr = 7.642x 10~10 s"1
to = collection date and time for the sample (s)
4ep = date and time of the Sr/Y separation (s)
ti = date and time of the midpoint of the f count of the STS (s)
NOTE: The elapsed time between the sample count and the reference date must be calculated
using the same time units as the decay constant
B1.2. For i = 1,2, use the results from Section A5.1 in Appendix A to calculate the
following sensitivity factors:
a, = DF^e^,, (B4)
"i = *-'*'sr90,iSSr90,i + ^^90,iS^90,i \^~>)
where
at = sensitivity of the count rate in the /'* measurement to 89Sr activity
bj = sensitivity of the count rate in the /'* measurement to 90Sr activity
eY9o,; = 9°Y efficiency of the detector for the f count of the STS
£sr9o,i = 9°Sr efficiency of the detector for the f count of the STS
B1.3. Calculate the standard uncertainties of the sensitivity factors using the equations:
u(s^) (B6)
Y90,,'
(B7)
where the estimated covariance of the 90Sr and 90Y efficiencies is calculated as
follows:
u(s ,s ) = r(s ,s )u(s }u(s ) (B8)
and where the estimated correlation coefficient r(esr9o,z, £Y9o,z) was determined during
the calibration.
B1.4. Calculate the covariances u(a\,ci2) and u(b\,b2) as follows:
u(al)u(a2), if only one detector is used
ala2u^(ACSlWstd), if two detectors are used
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
12-^^-90,1 ) U(SSi90,l ' £Y90,1 /
+ DFSr90,l DFSr90,2 U * (£Sr90,l ) + FY90,1 FJ90,2 U ' (£ Y90.1 X USm§ °^ 0nC det6CtOr (B 1 0)
,0 std), using two detectors
where
= activity concentration of the Sr standard used for calibration
on
Csr90 std = activity concentration of the Sr standard used for calibration
Mr(-) = relative standard uncertainty of the quantity in parentheses
B1.5. For i = 1,2, calculate the net beta count rates, RDJ, and their standard uncertainties:
^,-=^,--*b,- (BH)
l= Kk + ^k (B12)
K< ^
where:
RKJ = net beta count rate for the /'th count of the STS (cpm)
R^i = beta gross count rate for the f count of the STS (cpm)
Rbj = beta background count rate for the /' count of the STS (cpm)
4;, = sample count time for the /'th count of the STS (min)
7b,z = background count time for the /'th count of the STS (min)
B1.6. Using the values calculated in A5.1 - A5.5, calculate the 89Sr and 90Sr activity
concentrations:
AC^ SQ = —^-^ l-^- (B13)
2.22xXxVxY
^CSr90 = a' n'2~a2 "•' (B 14)
222xXxVxY
where:
X = alb2-a2bl (B15)
and where:
2.22 = conversion factor from dpm to pCi
Y = chemical yield for strontium
V = sample weight (g)
B2. The standard counting uncertainties for 89Sr (wcC(^4CSr89)) and 90Sr (wcC(^4CSr90)) are
calculated in units of pCi/g as follows:
2.22xXxWxY
(B16)
September 2014 79
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Rapid Radiochemical Method for Total Radiostrontium in Brick Samples
2.22xXxWxY
(B17)
90 c
B3. The combined standard uncertainties (CSU) for Sr and Sr are calculated as follows:
2 (u2(W) u2(Y) b2u2(a
orgq 1 1
(B18)
1/2
September 2014
80
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Validation of Rapid Radiochemical Method for Sr-90 in Brick Samples
Attachment IV:
Composition of Brick for Spiking in this Study
Metals by ICP-AES [4]
Silicon Dioxide
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Titanium
Manganese
Strontium
Uranium
Thorium
Non-Metals
Chloride
Sulfur
Phosphorus
Radionuclide
Uranium 238, 234
Plutonium 239/240
Americium 24 1
Strontium 90
Radium 226
Concentration (ppm) [11
721,700
78,700
400
1,600
40,000
4,600
15,300
1,500
4,400
600
100
<30
<30
—
5,600
1,500
Concentration (pCi/g) [2'3]
1.054 ±0.020, 1.102 ±0.021
-0.0003 ±0.0041
0.048 ±0.039
0.119± 0.077
1.025 ±0.027
NOTE: Analyses conducted by an independent laboratory.
[1] Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with the elemental analysis values. Parts
per million (ppm).
[2] Reported values represent the average value of seven blank samples analyzed except
for 226Ra and U by NAREL. Ten blank brick samples were analyzed for 226Ra.
Sixteen blank brick samples were analyzed for the uranium isotopes.
[3] Reported uncertainty is the standard deviation of the results (k=l).
[4] ICP-AES=Inductively Coupled Plasma - Atomic Emission Spectrometry
September 2014
81
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