EPA/600/R-12/053 | October 2012 | www.epa.gov/ord
United States
Environmental Protection
Agency
Assessment of the Fate of
ROD Contamination after
Laundering of Soft Porous
Materials
Office of Research and Development
National Homeland Security Research Center
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EPA 600/R-12/053
October 2012
Assessment of the Fate of ROD Contamination
after Laundering of Soft Porous Materials
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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DISCLAIMER
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development's National Homeland Security Research Center, funded and managed this
technology evaluation under Contract No. EP-C-10-001 with Battelle. This report has been peer
and administratively reviewed and has been approved for publication as an EPA document. It
does not necessarily reflect the views of the EPA. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use of a specific product.
Questions concerning this document or its application should be addressed to:
Emily Snyder
National Homeland Security Research Center
Office of Research and Development (E-343-06)
U.S. Environmental Protection Agency
109 T.W. Alexander Drive
Research Triangle Park, NC 27711
919-541-1006
snyder.emily@epa.gov
11
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FOREWORD
The U.S. Environmental Protection Agency (EPA) holds responsibilities associated with
homeland security events: EPA is the primary federal agency responsible for decontamination
following a chemical, biological, and/or radiological (CBR) attack. The National Homeland
Security Research Center (NHSRC) was established to conduct research and deliver scientific
products that improve the capability of the Agency to carry out these responsibilities.
NHSRC is pleased to make this publication available to assist the response community to prepare
for and recover from disasters involving CBR contamination. This research is intended to move
EPA one step closer to achieving its homeland security goals and its overall mission of
protecting human health and the environment while providing sustainable solutions to our
environmental problems.
Jonathan G. Herrmann, Director
National Homeland Security Research Center
in
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ACKNOWLEDGMENTS
Contributions of the following individuals and organizations to the development of
this document are gratefully acknowledged.
United States Environmental Protection Agency (EPA)
John Drake, NHSRC
Kathy Hall, NHSRC
Jeff Szabo, NHSRC
Lukas Oudejans, NHSRC
John Cardarelli, Office of Emergency Management, Consequence Management
Advisory Team (CMAT)
Scott Hudson, CMAT
James Michael, Office of Resource Conservation and Recovery (ORCR)
Battelle Memorial Institute
Pacific Northwest National Laboratories
IV
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CONTENTS
Page
DISCLAIMER ii
FOREWORD iii
ACKNOWLEDGMENTS iv
CONTENTS v
ABBREVIATIONS AND ACRONYMS vii
EXECUTIVE SUMMARY viii
1.0 INTRODUCTION 1
1.1 Background 1
1.2 Scope of Assessment 1
2.0 EXPERIMENTAL APPROACH 2
2.1 Equipment and Materials 2
2.1.1 Material Swatches 2
2.1.2 Washing Machine 4
2.1.3 Wastewater 4
2.1.4 Tap Water 5
2.2 Contaminant Application 5
2.3 Laundering Assessment 6
2.4 Gamma Radiation Measurement 8
2.4.1 Material Swatches 8
2.4.2 Washing Machine 9
2.4.3 Wastewater 10
2.5 Tap Water Analyses 10
3.0 QUALITY ASSURANCE/QUALITY CONTROL CHECKS 11
3.1 QC Results 11
3.1.1 Replicate Samples 11
3.1.2 Background Radioactivity on Clothing Materials 11
3.1.3 Positive Control Swatches 13
3.1.4 Procedural Blanks 14
3.1.5 Machine Blanks 14
3.1.6 Equipment Calibration 15
3.2 Audits 16
3.2.1 Technical Systems Audit 16
3.2.2 Data Quality Audit 17
3.3 Data Review 17
4.0 RESULTS 18
4.1 Contaminant Application Procedure Demonstration 18
4.2 Gamma Radiation Geometry Modeling 19
4.3 Tap Water Analyses 21
4.4 Laundering Assessment Data 22
5.0 CONCLUSIONS 28
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6.0 REFERENCES 29
LIST OF FIGURES
Figure 1. Application pattern on material swatch 3
Figure 2. Front load washing machine used for laundering experiments 4
Figure 3. 137CsCl being applied to cotton and polyester material swatches 6
Figure 4. Cotton swatch positioned on BEGe detector 9
Figure 5. Model composed for measurements of cloth swatches: solid (left), wired (right) 20
LIST OF TABLES
Table 1. Experimental Matrix 7
Table 2. Data Quality Indicators for Critical Measurements 12
Table 3. Results from Material Background Measurements 13
Table 4. Results for Positive Control Samples 13
Table 5. Results for Procedural Blanks 14
Table 6. Results for Machine Blanks 15
Table 7. Results from Demonstration of Contamination Application Procedure 18
Table 8. Detection Efficiency Values for Material Swatches 19
Table 9. MDA Values for Detectors (|iCi) 21
Table 10. Results from Tap Water Analyses 21
Table 11. Results from Laundering Assessment 23
Table 12. Contamination in Wastewater 25
Table 13. Material Balance Calculation 26
Table 14. Summary of Laundering Efficacy Results 28
VI
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ABBREVIATIONS AND ACRONYMS
BEGe broad energy germanium
COR Contracting Officer's Representative
137Cs cesium-137
137CsCl cesium chloride
DF decontamination factor
DOE U.S. Department of Energy
DQI data quality indicators
EPA U.S. Environmental Protection Agency
GM Geiger-Mueller
HPGe high purity germanium
ID identification number
in inch
ISOCS in situ object counting system
keV kilo electron volt
LLRW low level radioactive waste
(iCi micro curie
(iL microliter
mL milliliter
MDA minimum detectable activity
NDA non-destructive analysis
NIST National Institute of Standards and Technology
NHSRC National Homeland Security Research Center
ORD Office of Research and Development
PNNL Pacific Northwest National Laboratory
PNWD Pacific Northwest Division
QA quality assurance
QAPP quality assurance project plan
QC quality control
QMP quality management plan
%R percent removal
ROD radiological dispersal device
RW repeat washing
TSA technical systems audit
WA work assignment
vn
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EXECUTIVE SUMMARY
EPA is responsible for environmental cleanup after the release of a radiological dispersal device
(RDD), including recommendations on how the general public outside of the evacuation zone
can reduce their exposure to this contamination. The current recommendation for handling
clothing radioactively contaminated by an RDD is to remove the clothing and bag it. It is
unknown how effective washing with water is for removing RDD contamination from clothing
items and perhaps, more importantly, the impacts of the general public knowingly or
unknowingly washing contaminated clothing are not characterized. The National Homeland
Security Research Center (NHSRC) is investigating the efficacy of machine washing for
removing RDD contamination - specifically cesium 137 (137Cs) and determining the fate of
137Cs contamination after washing.
This assessment involved identifying and demonstrating methods for depositing 137CsCl on soft
porous surfaces (material swatches) and for measuring the activity on the swatches and on a
washing machine. With those methods demonstrated, polyester and cotton material was
contaminated with a known amount of 137Cs, then washed in a standard front load, low volume,
home-use washing machine using a common liquid detergent (Tide HE). Two wash
temperatures were investigated. The amount of 137Cs on the material swatches before and after
laundering was measured to determine removal efficiency. In addition, a set of experiments
were conducted where uncontaminated clothing (two pairs of jeans and two T-shirts) was
washed with the contaminated swatch to assess potential cross contamination. The amount of
137Cs that exited the washing machine in the wastewater was measured for all experiments; at
the conclusion of the entire set of experiments the 137Cs remaining on the washing machine was
measured.
Results indicate that most of the 137Cs spiked onto material swatches was removed by
laundering with Tide HE detergent and typical laundering conditions. Some decrease in washing
efficacy appears to result when laundering is done without Tide HE (91.8% removal of 137Cs
from cotton by laundering in cold/cold temperatures without detergent versus 94.4% removal of
137Cs from cotton by laundering in cold/cold temperatures with detergent). Noticeable
differences were not observed between other laundering conditions. Laundering 137Cs
contaminated material swatches with noncontaminated clothing reduced the amount of 137Cs
ending up in the wastewater - in that laundering condition, approximately 30% of the 137Cs
appears to end up on the originally noncontaminated clothing. Little 137Cs contamination
appears to remain on the washing machine - although this study only examined washing of low
levels of one radioactive compound on small material swatches.
Vlll
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1.0 INTRODUCTION
1.1 Background
The U.S. Environmental Protection Agency (EPA) is responsible for environmental
cleanup after the release of a radiological dispersal device (RDD). The Office of Research and
Development (ORD) National Homeland Security Research Center (NHSRC) is tasked to
perform scientific studies that investigate methods of RDD cleanup. This project was designed
to help develop decontamination efficacy data related to the laundering of clothing and other
porous soft materials contaminated due to an RDD. These data could be used to construct self-
help guidance to enable the general public living outside the evacuation zone to reduce their
exposure to radiological contamination.
The current recommendation for handling radioactively contaminated clothing is to take
the clothing off and bag it for later disposal/1'2-* At present, it is unclear to what extent laundering
in a conventional washing machine is an effective means of removing RDD contamination from
clothing items, or the effect of the general public knowingly or unknowingly washing their
contaminated clothing. Washing clothing and other soft porous items (such as linens and
slipcovers) may also help people living outside of the exclusion zone reduce their exposure to
radiation. The objective of this work was to determine the following:
1. the efficacy of washing to remove contamination [focus on Cesium-137 (137Cs) from
a cesium chloride (137CsCl) RDD]
2. the fate of the 137Cs contaminant after washing, including the amount of 137Cs that
exits the washer through the wastewater.
1.2 Scope of Assessment
This assessment involved (1) identifying and demonstrating methods for deposition of
137CsCl on soft porous surfaces (material swatches), (2) measuring the activity on swatches
before and after deposition of 137CsCl before and after laundering (3) measuring the residual
activity remaining on a washing machine used to launder contaminated material swatches, and
(4) measuring the activity of the discharged wastewater.
With the demonstrated methods, two types of clothing material were contaminated with
137CsCl and laundered under different conditions. The radiation produced by the contamination
1
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on the material swatches was measured before and after laundering. Those results were used to
determine the decontamination efficacy of laundering under various conditions for removing
137Cs contamination. Wastewater from the washing machine was collected and measured for
137Cs activity. The residual 137Cs activity in the washing machine was measured after all
contaminated material swatches had been laundered.
2.0 EXPERIMENTAL APPROACH
This work was conducted according to procedures described in the Quality Assurance
Project Plan (QAPP)for Assessment of the Fate ofRDD Contamination after Laundering of Soft
Porous Materials (May 31, 2011; Version 1) (available upon request). A summary of these
procedures is provided in the following sections. All experimental work was conducted in
laboratories at Battelle's Pacific Northwest Division (PNWD) in Richland, WA.
2.1 Equipment and Materials
2.1.1 Material Swatches
Swatches of two types of material, 100% cotton (blue) and 100% polyester (black), were
obtained by cutting 15.2 cm (6 in.) x 15.2 cm (6 in.) swatches from cloth that had been purchased
from a local fabric store. The material swatches were washed once prior to use in testing so they
were more representative of clothing that might be worn and become contaminated in a real
world incident. The conditions of this pre-washing were not critical to testing as used clothing
would have been washed under a wide variety of conditions. The swatches were marked with a
permanent marker at approximately 25 locations equally spaced to assist in the deposition of a
uniform level of activity over each cloth swatch (see Figure 1).
After contaminant application, each swatch was stored in its own transparent plastic bag
so that the ID number was visible and to protect against cross-contamination between swatches.
The activity of the storage bags was not measured prior to use.
Following laundering, the material swatches were dried under a heat lamp for at least 4
hours, then measured for 137Cs gamma radiation (see Section 2.4.1). The swatches were then
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placed in unused plastic bags (contamination of the bags before and after swatch storage was not
measured) and transported to the Radiological Measurement Laboratory.
For some experiments, actual clothing was washed in the load along with the material
swatches. In each such load, the clothing included two cotton white t-shirts and two pairs of
cotton blue jeans. The activity of the co-laundered clothing was measured only after laundering.
1/2"
Figure 1. Application pattern on material swatch.
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2.1.2 Washing Machine
A used, low volume Maytag 4000 series washing machine was used to launder
contaminated material swatches. The machine was a front loader and used 15 gal or less of
water per load. The machine was connected to tap water in the Battelle PNWD laboratory
(Figure 2). The pH and chlorine content of the source (tap) water were measured each day of
testing. The tap water temperature was measured prior to each load. The detergent used for
laundering the swatches in all the experiments that included detergent was liquid Tide HE®. The
wash/rinse temperatures depended on the material:
1) For cotton: hot/cold and cold/cold (same agitation used for both conditions)
2) For polyester: cold/cold.
The approximate composition of the detergent was determined from the material safety data
sheet. The combined wash and rinse time was approximately 40 minutes when just material
swatches were laundered; when multiple clothing was laundered with a material swatch, the
combined wash and rinse time was approximately 55 minutes.
Figure 2. Front load washing machine used for laundering experiments.
2.1.3 Wastewater
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During each laundry load, the wastewater (both wash and rinse cycles) from the machine
was collected together directly from the machine discharge line into a holding container.
Separate holding containers were used for each load. The water in the holding container was
agitated after collection prior to sampling in an effort to produce an effluent with evenly
distributed contamination. A transfer pump was then used to pull a sample (~1 L) of the
wastewater from approximately the center of the holding container. After sampling, the contents
of the holding containers were transferred to larger waste collection containers. The wastewater
samples were measured for gamma radiation (see Section 2.4.3). After the assessment was
completed, the wastewater (both bulk and samples) and the holding containers were disposed of
as low level radioactive waste (LLRW) according to Pacific Northwest National Laboratory
(PNNL) site procedures.
2.1.4 Tap Water
The water in the test facility was supplied by the City of Richland, Washington
(http://www.ci.richland.wa.us/DocumentView.aspx?DID=l818) [Accessed Aug 2012]. Prior to
the first load, in the middle of all loads, and after all loads, one sample of tap water was collected
for analysis by placing a beaker under the tap water supply to the washing machine.
2.2 Contaminant Application
Each material swatch was contaminated by pipetting 2 mL of 137CsCl solution (Isotope
Products, Valencia, CA, product code 7137) onto the material swatches with a Research®
adjustable-volume microliter (jiL) pipette, 0-100 jiL (Eppendorf North America, Hauppauge,
NY) as shown in Figure 3. The specific concentration of the 137Cs was about 1 micro curie
(|iCi)/milliliter (mL). After contamination, each swatch was dried under a heat lamp in a
radiologically-controlled hood. The swatches were kept under the heat lamp until visually dry
which was usually less than four hours. Dry contaminated swatches were stored in sealed plastic
bags under ambient conditions and laundered within 30 days of 137CsCl application.
Because the activity from each contaminated swatch was measured before and after
application of the radionuclide and after laundering, minor differences in the amount of
contaminant applied between swatches was not critical. The acceptable range of activity on each
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swatch after contamination was 1.8 jiCi to 2.2 jiCi. If a swatch varied from this target range of
activity, the swatch was not used.
This contaminant application procedure was demonstrated using replicate material
swatches (both cotton and polyester). A swatch was placed flat in a glass container and 80 jiL of
1 |iCi/mL 137CsCl solution was applied directly to each of the 25 predetermined locations. After
application and drying, the swatch was analyzed for 137Cs activity using a Broad Energy
Germanium (BEGe) detector. Goals of the method demonstration were to (1) ensure that the
contaminant application procedure reproducibly administered between 1.8 to 2.2 jiCi of 137CsCl
on each material swatch, (2) determine background radiation levels for the material swatches,
and (3) determine an associated method detection limit.
Figure 3. CsCl being applied to cotton and polyester material swatches.
2.3 Laundering Assessment
The experimental matrix for the laundering assessment is shown in Table 1. Five
material swatches were run in separate loads under each laundering condition (e.g., water
temperature, with and without detergent, etc.). With each laundering condition, various quality
control samples were processed with the contaminated material swatches including:
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Table 1. Experimental Matrix
Material
Cotton
(CC)
Cotton
(HC)
Polyester
(PC)
Cotton
(ND)
Cotton
(RW)
Cotton
with
Multiple
Clothing in
Same Load
(MC)
Wash/Rinse Material Swatch Positive Control
Temperature (with 137Cs & Swatch3
washed) (with 137Cs & not
washed)
Cold/Cold 1 2
1
1
1
Hot/Cold 1
1
Cold/Cold 1 2
1
Cold/Cold 1 1
wilhoul j
Detergent
1
Cold/Cold 1 1
with Repeat
Wash Cvcles
(RW) 1
Cold/Cold 1 1
1
Procedural
Blankb
(no 137Cs &
washed)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Machine Loadd
Blank0
(no 137Cs &
washed)
1
1 2
3
1 4
5
1 6
7,8
1 9
10
1 11
12,13,
14,15
1 16
17
18, 19,
20,21
22
23
1 24
1 25
26, 27,
28
29
1 30
31,32,
33,34
35
1 36
37, 38,
39,40
a To determine activity loss possibly resulting from experimental procedures.
b To determine cross contamination within load.
0 To determine cross contamination between loads.
d Some rows in table contain multiple loads; each load contained one contaminated material swatch.
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• Positive control swatch - Contaminated and not washed; used to determine activity
loss possibly resulting from experimental procedures;
• Procedural blank - Non-contaminated material swatch; one procedural blank washed
in each load with contaminated material swatch; used to determine cross
contamination within load; and
• Machine blank - Non-contaminated material swatch; washed in loads without
contaminated material swatch; used to assess cross contamination between loads
(e.g., from possible residual contamination on the washing machine).
2.4 Gamma Radiation Measurement
Gamma radiation of the material swatches, washing machine, and wastewater was
measured. The gamma counting systems used for this assessment did not have geometry or
room-specific detection limits, or calibration factors. Geometry factors for the material swatches
and the washing machine were developed using the procedure NDA-CP-GAMMA "Gamma
Results Calculation" (unpublished technical procedure, U.S. Department of Energy (DOE),
Pacific Northwest National Laboratory, Richland, WA).
2.4.1 Material Swatches
A BEGe detector (Canberra, Meriden, CT) with in-situ object counting system (ISOCS)
software (Canberra, Meriden, CT) was used to measure 137Cs gamma radiation on the material
swatches both before and after laundering. After laundering, the material swatches were
removed from the washing machine damp and placed in a plastic bag. The material swatches
were analyzed for gamma radiation while still in the plastic bag (see Figure 4).
Operation and measurement procedures for the Canberra BEGe detector and ISOCS
software are documented in manuals prepared by Canberra (Canberra 2002a, 2002b).(3'4)
The gamma assay results were analyzed using NDA-CP-GAMMA "Gamma Results
Calculation" and NDA-MP-GAMMA "Gamma Assay" which encompasses spectra
identification, efficiency calibration curve generation, and activity calculations (unpublished
technical procedures, U.S. DOE, Pacific Northwest National Laboratory, Richland, WA).
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Figure 4. Cotton swatch positioned on BEGe detector.
2.4.2 Washing Machine
The activity in the washing machine was determined by performing a non-destructive
analysis (NDA) count of the entire machine using a BEGe detector with ISOCS software. The
counting efficiency curve was generated for the range of 50 to 2000 kiloelectron volt (keV).
Efficiency curve uncertainty for the range 600 to 700 keV was estimated to be 6% at the 68.3%
confidence level.
The NDA count was then followed by measuring the radiation emitted from the washing
machine components with an operational survey instrument, specifically, a Geiger Mueller (GM)
detector (BNW-1, Eberline Instrument Corporation, West Columbia, SC) to determine the
location of the activity in the machine. This measurement was conducted according to
procedures in RCP-4.2.01 Surveys for Release of Material and Equipment from Radiological
Control (unpublished technical procedure, U.S. DOE, Pacific Northwest National Laboratory,
Richland, WA) which involves wiping the washing machine components with a technical smear
r\
over a 100 square centimeter (cm ) area, then measuring the technical smear for alpha and
beta/gamma radiation. The measurement was made approximately midway through the
laundering experiments (e.g., after the 21st load) and after the final load (consistent with the
period of performance for the associated projects).
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2.4.3 Wastewater
The 137Cs activity in wastewater samples was measured using a high purity germanium
(HPGe) system. The HPGe system was operated under PNNL Operating Procedure AGG-RRL-
001 Rev. No. 3 "Gamma Energy Analysis Operation and Instrument Verification Using the
Genie 2000™ Support Software." With this procedure, a container with certified mixed gamma
ray emitting nuclides in a specified geometry (container with known volume) was placed on the
detector and measured. The measurement is used for the calibration of the counting efficiency
and energy of the radionuclides in this particular geometry. Once the calibration was
determined, wastewater samples were placed in this specific geometry and analyzed to determine
the concentration of the radionuclides present in the sample.
2.5 Tap Water Analyses
The collected tap water samples were analyzed for pH, chlorine content, and temperature
as follows:
• pH was measured with a pH meter (Model HI4521, Hanna Instruments, Ann Arbor,
MI) using PNNL technical procedure AGG-pH-001. Using this procedure, pH of the
tap water sample was determined electrometrically using a glass combination
electrode. The electrode was calibrated using standard solutions of known pH
bracketing the anticipated pH. Once calibrated, the electrode was immersed in the tap
water sample to determine the pH.
• Chlorine content was determined colorimetrically using Hach Free & Total Chlorine
Spectrophotometric Test Kit, 0-10 mg/L, per manufacturer's instructions (Hach,
Loveland, Colorado).
• Temperature was measured with a non-calibrated thermometer.
The pH and temperature of the tap water were measured immediately and the chlorine was
measured within 15 minutes of sample collection.
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3.0 QUALITY ASSURANCE/QUALITY CONTROL CHECKS
The critical measurements for these experiments were:
• Activity of the material swatches before and after laundering.
• Activity of the wastewater (from rinsing and washing cycles).
• Activity of the washing machine after completion of laundering.
The data quality indicators for these critical measurements are shown in Table 2.
3.1 QC Results
QC samples generated during the laundering assessment included: replicate samples,
positive control swatches, procedural blanks (not inoculated, laundered), and machine blanks.
3.1.1 Replicate Samples
As shown in Table 1, five material swatches were run under the same conditions in
separate loads (e.g., Loads 1, 3, 5, 7, and 8). These five replicate samples provided a quality
control check on the experimental precision.
3.1.2 Background Radioactivity on Clothing Materials
Background radioactivity of each individual material swatch was not measured prior to
spiking with 137CsCl and laundering. Rather, gamma measurement of replicate swatches made
from the same material that was used to prepare the test swatches was conducted to assess if
there was any background contamination in the original materials. Results from these
measurements are provided in Table 3. As shown in Table 3, no background radioactive
contamination was found on the materials used to prepare test swatches (detection limits vary
depending upon sample count time and the standard deviation of the measurement system
background). The minimum detectable activity for this measurement is provided in Table 2.
11
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Table 2. Data Quality Indicators for Critical Measurements
Measurement
Activity of
material swatches
NDA count of
entire washing
machine
Activity of
wastewater
Analysis
Method
Gamma
Detector
(BEGe)
Gamma
Detector
(BEGe)
Gamma
Detector
(HPGe)
Accuracy3
DQI
± 6% of
certified
value
± 6% of
certified
value
±10% of
certified
value
Actual"
< 2.77%
< 2.77%
Precision
DQI
20%
NA
20%
Actual
<3.0%
NA
<20%
Minimum Detectable
Activity
DQI
1 .85E-04
jiCi /
swatch
0.010
jiCi/
machine
1 pCi/mL
Actual
2.01E-4
jiCi /
swatch
O.0025
|iCi/machine
<1.07
pCi/mLd
Completeness
DQI
95%
100%
95%
How determined
Number of material
swatches for which
activity was measured/
total number of material
swatches planned for
analysis
100% = NDA count was
successfully made of
entire washing machine
Number of wastewater
samples for which
activity was measured/
total number of
wastewater samples
planned for analysis
Actual
100%
100%
100%
aDetermined by analysis of NIST-traceable button source.
bRelative percent difference of duplicate analysis of one sample when results are >5 times minimum (except for washing machine)
°Based on the average of all measurements taken.
dBased on the average MDA calculated for all measurements.
NA = Only one count of the washing machine was made so replicate results not available to assess precision.
12
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Table 3. Results from Material Background Measurements
Material
Cotton
Polyester
Replicate
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Activity (uO)
<0.000184
<0.000178
<0.000193
<0.000166
<0.000194
<0.000198
<0.000175
<0.000198
<0.000201
<0.000213
<0.000184
<0.000205
<0.000166
<0.000179
3.1.3 Positive Control Swatches
As shown in Table 1, positive control swatches were processed for each material (cotton
and polyester). The positive control swatches were contaminated but not laundered - however
they were handled in every other way identically to the test material swatches (e.g., drying after
contamination, measurement of radioactivity before and after load was run, etc.). The results
from the positive control swatches are provided in Table 4. These results indicate that minimal
loss of 137Cs contamination resulted from experimental procedures (excluding laundering).
Table 4. Results for Positive Control Samples
Positive Control
Sample
Cotton (cold/cold)
Cotton (cold/cold)
Cotton (cold/cold)
Polyester (cold/cold)
Polyester (cold/cold)
Polyester (cold/cold)
No Detergent (ND)
Repeat Washing (RW)
Multiple Clothing (MC)
Prior Activity
1.
2.
2.
1.
1.
1.
2
2
2
98
03
01
90
97
95
.14
.15
.16
±
±
±
±
±
±
±
±
±
0
0
0
0
0
0
.0871
.0882
.0880
.0847
.0856
.0851
0.0932
0.
0.
.0930
.0940
Post
c
1.
1.
1.
1.
1.
1.
96
97
98
90
91
92
2.02
2
2
.02
.18
Activity
uCi)
±
±
±
±
±
±
±
±
±
0
0
0
0
0
0
0.
0.
0.
.0856
.0854
.0859
.0825
.0830
.0840
117
104
097
13
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137,
3.1.4 Procedural Blanks
As shown in Table 1, one procedural blank - a swatch not spiked with 1J/CsCl - was
laundered with each wash evolution. The 137Cs activity was measured on the procedural blank
after laundering (refer to Section 3.1.2 for discussion of swatch background activity). The
results from the procedural blanks are provided in Table 5. These results indicate that minimal
contamination (typically less than 1% of the amount on the pre-washed swatch laundered with
the procedural blank) was introduced from the experimental procedures used in this study.
Table 5. Results for Procedural Blanks
Material
Laundering Conditions
Activity of Procedural
Blank after Laundering
(u€i)a
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Polyester
Polyester
Polyester
Polyester
Polyester
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
-1
-2
O
-4
-5
Hot/Cold - 1
Hot/Cold - 2
Hot/Cold - 3
Hot/Cold - 4
Hot/Cold - 5
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
-1
-2
-3
-4
-5
; No Detergent - 1
; No Detergent - 2
; No Detergent - 3
; No Detergent - 4
; No Detergent - 5
; Repeat Washing - 1
; Repeat Washing - 2
; Repeat Washing - 3
; Repeat Washing - 4
; Repeat Washing - 5
0.0144
0.0139
0.0158
0.0152
0.0148
0.0131
0.0149
0.0137
0.0146
0.0142
0.000379
0.000715
0.000800
0.000644
0.000448
0.0210
0.0212
0.0268
0.0266
0.0255
0.00678
0.00697
0.00484
0.00650
0.00570
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
0.00108
0.00104
0.00136
0.00105
0.00128
0.00117
0.00122
0.000950
0.00129
0.00138
0.0000560
0.0000769
0.0000912
0.0000738
0.0000753
0.00198
0.00228
0.00250
0.00192
0.00178
0.000745
0.00133
0.00128
0.000823
0.000705
aCo-laundered with material swatches contaminated with approximately 2 jiCi of CsCl.
3.1.5 Machine Blanks
14
-------
A machine blank (swatch not contaminated with 137CsCl) was laundered ten times during
the study (see Table 1). The 137Cs contamination on the machine blank was measured before
and after laundering. Results from the machine blank are provided in Table 6. The 137Cs
measurement of the machine blanks was made and reviewed before subsequent loads were
washed. The 137Cs activity on the machine blank was either not detected or generally less than
1% of the amount of 137Cs activity detected before laundering of associated material swatches.
This result indicates that if contaminated clothing is washed, very little of the activity will end up
as residual contamination on the washing machine.
Table 6. Results for Machine Blanks
Material
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Laundering Conditions
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Hot/Cold
Hot/Cold
Cold/Cold; No Detergent
Cold/Cold; No Detergent
Cold/Cold; Repeat Washing
Cold/Cold; Multiple Clothing
Load
2
4
6
9
11
16
24
25
30
36
Activity (uCi )
<0.000212
<0.000229
<0.000198
<0.000257
<0.000253
<0.000235
0.000381
0.000394
0.000140
0.000891
3.1.6 Equipment Calibration
137,
The HPGe system used for measuring Cs activity in the wastewater was operated
under PNNL Operating Procedure AGG-RRL-001 Rev. No. 3 "Gamma Energy Analysis
Operation and Instrument Verification Using the Genie 2000™ Support Software"; this
procedure is described previously in Section 2.4.3. This procedure requires that background and
control counts be performed weekly.
The calibration procedures for the Canberra BEGe detector and ISOCS software used for
measuring the 137Cs activity on the material swatches and washing machine are documented in
manuals prepared by Canberra (Canberra 2002a, 2002b).(3'4) Detector energy calibration was
established using multiple gamma rays in the range of 60 to 1408 keV. A linear or quadratic fit
of the centroid of each full-energy peak versus detector channel was done with an estimated
uncertainty of 0.1 keV over the range of 50 to 2000 keV. Energy (re)calibration and
15
-------
performance checks were performed each time the BEGe detector was used with NIST-traceable
button source containing Americium-241 and Europium-152. The detector efficiency for
performance check measurements was also generated by modeling. Measured activity values for
three different gamma rays (60, 779, and 1408 keV) were compared against the source certificate
values. Acceptance criteria for the measurement results were to be within (±)10% of the
corresponding certified value.
The performance checks of the BEGe detector were conducted prior to and after the
sample measurement(s). The object measurements were considered to be valid only in a case
where both performance checks prior to and afterward were within calibration limits. Analysis
of the measurement results was performed by a qualified measurement specialist. The
measurement report was then peer-reviewed and approved by the NDA Program Manager.
The GM detector used to measure radiation from washing machine components is
calibrated annually unless the instrument fails the pre-use tests, in which case the instrument is
recalibrated. The GM-pancake probe was calibrated according to Procedure 3.7.0 GM-Pancake
Probe Calibration Procedure and the count rate meter was calibrated according to Procedure
3.9.2 Eberline GM Count Rate Meter Calibration Procedure (unpublished technical procedures,
U.S. DOE, Pacific Northwest National Laboratory, Richland, WA).
3.2 Audits
Each audit described below was documented in accordance with the NHSRC QMP.^ .
3.2.1 Technical Systems Audit
The QA Manager conducted a technical systems audit (TSA) of the test procedures at
Pacific Northwest National Laboratory on June 30, 2011, to ensure that the evaluation was being
conducted in accordance with the Quality Assurance Project Plan (QAPP) and the Quality
Management Plan (QMP).^ As part of the TSA, test procedures were compared to those
specified in the QAPP, and data acquisition and handling procedures were reviewed.
Observations and findings from these TSAs were documented and submitted by the testing
personnel for response. No adverse findings resulted from this TSA. TSA records are
permanently stored with the QA Manager.
16
-------
3.2.2 Data Quality Audit
At least 10% of the data acquired during the evaluation were audited. The QA Manager
traced the data from the initial acquisition, through reduction and statistical analysis, to final
reporting to ensure the integrity of the reported results. All calculations performed on the data
undergoing the audit were checked.
3.3 Data Review
Records and data generated in the evaluation received a quality control (QC)/technical
review before they were used in calculating or evaluating results and prior to incorporation in
reports. All data were recorded by the project's technical staff. The person performing the
QC/technical review was involved in the experiments and added his/her initials and the date to a
hard copy of the record being reviewed. This hard copy was returned to the project staff member
who stored the record.
17
-------
4.0 RESULTS
All results for gamma radiation measurements presented in this section have been
corrected for any bias in the BEGe detector that was calculated using a National Institute of
Standards and Technology (NIST)-traceable button source of 137Cs. These activities, as well as
the standard deviation from triplicate analysis of each sample (swatch, wastewater, etc.), are
included with the corrected activities reported.
4.1 Contaminant Application Procedure Demonstration
The purpose of this method demonstration was to ensure that 137CsCl could be applied
and measured reproducibly on the material swatches. In this work, replicate material swatches
(three for cotton and three for polyester) were contaminated with 2 jiCi of CsCl as described
previously in Section 2.2. The 137Cs gamma radiation emitted from the contaminated swatches
was measured with a BEGe detector. Two units of the same BEGe detector were used to make
the measurements to further ensure the procedure's precision.
Results are provided in Table 7 and show that the desired spike level (1.8 - 2.2 jiCi) was
reproducibly applied and measured on the material swatches. The corrected results reflect a bias
for the BEGe detectors that was calculated using a NIST-traceable button source of 137Cs.
In addition to the contamination application procedure demonstration, the minimum
detectable activity (MDA) for the detectors using defined models developed for the material
swatches was determined. The calculated MDA was 1.85E-04 jiCi using a 20 minute counting
time.
Table 7. Results from Demonstration of Contamination Application Procedure
Detector 1
Activity (uCi)
Cotton- 1
Cotton -2
Cotton -3
1.98
2.03
2.01
±
±
±
0.042
0.041
0.042
Detector 2 Activity
GiCi)
1.94
1.99
1.97
±
±
±
0.049
0.051
0.049
Polyester- 1
Polyester -2
Polyester -3
1.90
1.97
1.95
±
±
±
0.043
0.040
0.040
1.83
1.93
1.90
±
±
±
0.049
0.049
0.048
18
-------
4.2 Gamma Radiation Geometry Modeling
Measurement systems chosen for this assessment were two ISOCSs characterized BEGe
detectors, S/N 4802 and S/N 4862, respectively. Both detectors were set in a vertical position
surrounded by lead shielding to reduce ambient background and potential interferences. The top
of the lead shielding was covered with transparent tape to hold the cloth swatches at a distance of
two inches from the detector end caps.
The measurement geometries were modeled using information available on detector
standoff distance and the dimensions and weights of the material swatches. Initially, detection
efficiency curves for dry and damp cotton and polyester swatches were generated for each
detector. A comparison in detection efficiency between dry and damp material swatches was
found to be below one percent at the 661.65 keV energy line which is the energy line associated
with gamma decay of 137Cs. Therefore calibration curves for each detector were reduced to two:
cotton and polyester (based on dry material). Efficiency values for all configurations are
presented in Table 8. Figure 5 shows a model composed for the material swatch measurements.
Table 8. Detection Efficiency Values for Material Swatches
Cloth Type
Cotton
Cloth
Thickness
3/16"
Swatch"
Weight
Dry: 9 g
Damp: 19 g
Average: 14 g
Polyester
1/16"
Dry: 5.7 g
Damp: 9.7 g
Average: 7.7 g
Detection Efficiency
Detector 4802
6.193E-03
6.145E-03
6.169E-03
6.391E-03
6.371E-03
6.381E-03
at 661.65 keV [y-1]
Detector 4862
4.263E-03
4.230E-03
4.246E-03
4.424E-03
4.410E-03
4.417E-03
a3"x3" swatch folded.
19
-------
Figure 5. Model composed for measurements of cloth swatches: solid (left), wired (right).
20
-------
Several background measurements were performed to assess MDA values anticipated for the
detectors using defined models (clothes). The results of the measurement exercise are
summarized in Table 9.
Table 9. MDA Values for Detectors (uCi)
Counting
Time (s)
300
600
1200
Detector 4802a
Cotton
4.019E-04
2.584E-04
1.883E-04
3
Polyester
873E-04
2.490E-04
1
814E-04
Detector 4862
Cotton
5.887E-04
4.068E-04
2.606E-04
Polyester
5.655E-04
3.908E-04
2.503E-04
aDetector used in laundering assessment.
4.3 Tap Water Analyses
Results from analysis of the tap water samples for pH, chlorine content, and temperature
are provided in Table 10. These parameters did not vary significantly over the course of the
laundering assessment. The tap water used during the testing was not analyzed for the presence
of background radioactivity, however it was supplied by the City of Richland and meets the
drinking water standard of <200 pCi/L.
Table 10. Results from Tap Water Analyses
Load
1
6
11
15
pH
7.81
7.87
7.87
7.82
Free
Chlorine
Content
(mg/L)
0.25
0.25
0.32
0.32
Total
Chlorine
Content
(mg/L)
0.26
0.26
0.34
0.34
Temperature
Hot/Cold
(°C)
52/22
45/22
53/22
52/22
21
-------
4.4 Laundering Assessment Data
The efficacy of laundering for removing 137Cs contamination from clothing was
calculated for each contaminated material swatch. The decontamination efficacy was
represented using the following equations for decontamination factor (DF) and percent removal
DF (unitless) = Co/Cf
= (l-Cf/C0)xlOO%
where:
C0 = Counts of radiological activity on the material swatch before laundering (jiCi ).
Cf = Counts of radiological activity on the material swatch after laundering (jiCi ).
Each of these equations represents the same data in a slightly different way. The DF is the factor
by which the contamination was removed and the %R is the percentage of contamination that
was removed by laundering. The average and relative standard deviation for the DF and %R for
the five samples for a specific material type/machine temperature were calculated.
Results from the laundering assessment are provided in Table 11. A two-sample t-test
was applied independently in each of the following two cases to compare average percent
removals:
• Cotton (cold/cold) versus polyester (cold/cold)
• Cotton (cold/cold with detergent) versus cotton (cold/cold with no detergent).
In both cases, the p-value of the test was <0.0001, indicating that the two averages compared are
statistically significantly different. Each average was calculated from five data values - one
value per tested material swatch. All five percent removals for cotton laundered at cold/cold
with detergent (ranging from 93.7 to 95.0%) exceeded the five values for cotton laundered at
cold/cold with no detergent (ranging from 91.3 to 92.3%) and were also below the five percent
removals for polyester laundered at cold/cold with detergent (ranging from 96.5 to 97.2%).
22
-------
Thus, in this work, laundering of contaminated clothing removed a significantly greater amount
of residual activity from polyester than from cotton under cold/cold wash conditions; and
Table 11. Results from Laundering Assessment
Pre-Washed Swatches
Sample"
CC-1
CC-2
CC-3
CC-4
CC-5
HC-1
HC-2
HC-3
HC-4
HC-5
PC-1
PC-2
PC-3
PC-4
PC-5
ND-1
ND-2
ND-3
ND-4
ND-5
RW-1
RW-2
RW-3
RW-4
RW-5
MC-1
MC-2
MC-3
MC-4
MC-5
Activity (uCi )
1.89 ± 0.0844
1.97 ± 0.0864
1.95 ± 0.0858
1.95 ± 0.0866
1.92 ± 0.0860
1.98 ± 0.0875
1.99 ± 0.0868
1.98 ± 0.0881
1.97 ± 0.0862
1.96 ± 0.0943
1.94 ± 0.0867
1.93 ± 0.0841
1.97 ± 0.0866
1.94 ± 0.0841
1.94 ± 0.0858
2.11 ± 0.0919
2.05 ± 0.0893
2.06 ± 0.0919
2.05 ± 0.0897
2.07 ± 0.0921
2.04 ± 0.0926
2.06 ± 0.0935
2.04 ± 0.0902
2.05 ± 0.0898
2.03 ± 0.0883
2.08 ± 0.0943
2.07 ± 0.0904
2.11 ± 0.0913
2.11 ± 0.0913
2.09 ± 0.0932
Washed Swatches
Load
Number
10
12
13
14
15
1
3
5
7
8
17
18
19
20
21
22
23
26
27
28
29
31
32
33
34
35
37
38
39
40
Activity (uCi )
0.0944 ± 0.00490
0.113 ± 0.00547
0.122 ± 0.00581
0.106 ± 0.00508
0.107 ± 0.00584
Average
0.0476 ± 0.00306
0.0915 ± 0.00509
0.0789 ± 0.00840
0.0889 ± 0.00486
0.0939 ± 0.00480
Average
0.0537 ± 0.00306
0.0647 ± 0.00326
0.0686 ± 0.00377
0.0642 ± 0.00332
0.0595 ± 0.00321
Average
0.175 ± 0.00997
0.158 ± 0.0105
0.166 ± 0.00938
0.1723 ± 0.00927
0.1799 ± 0.0114
Average
0.0686 ± 0.00401
0.0655 ± 0.00442
0.0567 ± 0.00374
0.0679 ± 0.00417
0.0731 ± 0.00442
Average
0.088 ± 0.00426
0.092 ± 0.00449
0.097 ± 0.00556
0.101 ± 0.00483
0.086 ± 0.00424
Average
Decontamination
Factor
20.0
17.4
16.0
18.4
17.9
17.9
41.6
21.7
25.1
22.2
20.9
26.3
36.1
29.8
28.7
30.2
32.6
31.5
12.0
12.9
12.4
11.9
11.5
12.2
29.7
31.4
36.0
30.2
27.8
31.0
23.7
22.4
21.7
20.8
24.3
22.6
Percent
Removal
(%)
95.0%
94.3%
93.7%
94.6%
94.4%
94.4%
97.6%
95.4%
96.0%
95.5%
95.2%
95.9%
97.2%
96.6%
96.5%
96.7%
96.9%
96.8%
91.7%
92.3%
91.9%
91.6%
91.3%
91.8%
96.6%
96.8%
97.2%
96.7%
96.4%
96.7%
95.8%
95.5%
95.4%
95.2%
95.9%
95.6%
aCC = Cotton at cold/cold; HC = Cotton at hot/cold; PC = Polyester at cold/cold; ND = Cotton at
23
-------
cold/cold with no detergent; RW = Cotton at cold/cold, washed a second time; MC = Cotton at
cold/cold laundered with multiple noncontaminated pieces of clothing.
laundering cotton with detergent removed significantly more residual activity than laundering
cotton without detergent. The amount of contamination in the wastewater from the washing
machine is provided in Table 12.
The residual contamination found on the washing machine components was 0.070 ±
0.003 jiCi after original loads under normal conditions (through Load 21), and 0.460 ± 0.029 jiCi
after loads with no detergent, repeat washing, and clothing. The washing machine was not
decontaminated between these measurements or loads. The MDA for this measurement was
O.0025 |iCi/machine.
The results from the material swatches (pre- and post-laundering) and the wastewater
were used to calculate a material balance for the laundering assessment - essentially how much
of the original 137Cs contamination could be accounted for. Results of that calculation are
provided in Table 13. The 137Cs contamination is slightly less accounted for with the cotton
swatches laundered at hot temperatures than with cotton or polyester laundered at cold
temperatures. However, this difference is small enough to be a result of imprecision of the
experiments.
24
-------
Table 12. Contamination in Wastewater
Material
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Polyester
Polyester
Polyester
Polyester
Polyester
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Cotton
Laundering Conditions
Cold/Cold -1
Cold/Cold-2
Cold/Cold-3
Cold/Cold-4
Cold/Cold-5
Hot/Cold- 1
Hot/Cold-2
Hot/Cold-3
Hot/Cold-4
Hot/Cold-5
Cold/Cold -1
Cold/Cold-2
Cold/Cold-3
Cold/Cold-4
Cold/Cold-5
Cold/Cold; No Detergent- 1
Cold/Cold; No Detergent-2
Cold/Cold; No Detergent-3
Cold/Cold; No Detergent-4
Cold/Cold; No Detergent-5
Cold/Cold; Repeat Washing- 1
Cold/Cold; Repeat Washing- 1 A
Cold/Cold; Repeat Washing-2
Cold/Cold; Repeat Washing-2A
Cold/Cold; Repeat Washing-3
Cold/Cold; Repeat Washing-3 A
Cold/Cold; Repeat Washing-4
Cold/Cold; Repeat Washing-4A
Cold/Cold; Repeat Washing-5
Cold/Cold; Repeat Washing-5 A
Cold/Cold; Multiple Clothing- 1
Cold/Cold; Multiple Clothing-2
Cold/Cold; Multiple Clothing-3
Cold/Cold; Multiple Clothing-4
Cold/Cold; Multiple Clothing-5
Activity
(pCi/mL)
84.0 ± 1.65
84.4 ± 1.64
84.4 ± 1.64
89.5 ± 1.72
88.2 ± 1.70
73.2 ± 1.50
84.2 ± 1.65
88.0 ± 1.70
85.8 ± 1.67
84.6 ± 1.65
86.4 ± 1.67
86.8 ± 1.68
93.0 ± 1.77
88.5 ± 1.70
91.2 ± 1.75
80.7 ± 1.45
75.9 ± 1.38
84.5 ± 1.50
83.1 ± 1.48
81.7 ± 1.46
83.8 ± 1.49
4.56 ± 0.25
84.4 ± 1.50
3.90 ± 0.229
83.7 ± 1.49
3.35 ± 0.217
82.8 ± 1.48
4.37 ± 0.244
85.8 ± 1.52
4.78 ± 0.246
29.3 ± 0.693
28.7 ± 0.684
35.4 ± 0.789
29.7 ± 0.699
30.2 ± 0.706
Total (u€i)
1.68
1.69
1.69
1.79
1.76
1.76
1.68
1.76
1.72
1.69
1.73
1.74
1.86
1.77
1.82
1.61
1.52
1.69
1.66
1.63
1.68
0.091
1.69
0.077
1.67
0.067
1.66
0.087
1.72
0.096
0.901
0.883
1.09
0.913
0.926
25
-------
Table 13. Material Balance Calculation
Material -
Laundering
Conditions"
Cotton - Cold/Cold
Cotton - Cold/Cold
Cotton - Cold/Cold
Cotton - Cold/Cold
Cotton - Cold/Cold
Average
Cotton - Hot/Cold
Cotton - Hot/Cold
Cotton - Hot/Cold
Cotton - Hot/Cold
Cotton - Hot/Cold
Average
Polyester - Cold/Cold
Polyester - Cold/Cold
Polyester - Cold/Cold
Polyester - Cold/Cold
Polyester - Cold/Cold
Average
Swatch
Pre-
Laundering
(u€i)
1.89
1.97
1.95
1.95
1.92
1.94
1.98
1.99
1.98
1.97
1.96
1.98
1.94
1.93
1.97
1.94
1.94
1.94
Swatch
Post-
Laundering
(u€i)
0.0944
0.113
0.122
0.106
0.107
0.11
0.0476
0.0915
0.0789
0.0889
0.0939
0.080
0.0537
0.0647
0.0686
0.0642
0.0595
0.062
Wastewater
(u€i)
1.68
1.69
1.69
1.79
1.76
1.72
1.76
1.68
1.76
1.72
1.69
1.72
1.73
1.74
1.86
1.77
1.82
1.78
Procedural
Blank
(u€i)
0.0144
0.0139
0.0158
0.0152
0.0148
0.0148
0.0131
0.0149
0.0137
0.0146
0.0142
0.0141
0.000379
0.000715
0.000800
0.000644
0.000448
0.000597
Washing
Machine
(u€i)
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.0046
0.00046
Co-
Laundered
Clothing
(u€i)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Total Post-
Laundering
(u€i)
1.79
1.82
1.83
1.92
1.89
1.85
1.82
1.79
1.86
1.83
1.80
1.82
1.79
1.81
1.93
1.84
1.88
1.85
Material
Balance
94.9%
92.5%
94.0%
98.2%
98.3%
95.6%
92.2%
90.0%
93.8%
92.8%
92.0%
92.2%
92.2%
93.8%
98.2%
94.8%
97.1%
95.2%
26
-------
Table 13. Material Balance Calculation (Cont'd)
Material -
Laundering
Conditions"
Cotton - Cold/Cold (ND)
Cotton - Cold/Cold (ND)
Cotton - Cold/Cold (ND)
Cotton - Cold/Cold (ND)
Cotton - Cold/Cold (ND)
Average
Cotton - Cold/Cold (RW)
Cotton - Cold/Cold (RW)
Cotton - Cold/Cold (RW)
Cotton - Cold/Cold (RW)
Cotton - Cold/Cold (RW)
Average
Cotton - Cold/Cold (MC)
Cotton - Cold/Cold (MC)
Cotton - Cold/Cold (MC)
Cotton - Cold/Cold (MC)
Cotton - Cold/Cold (MC)
Average
Swatch Pre-
Laundering
(u€i)
2.11
2.05
2.06
2.05
2.07
2.07
2.04
2.06
2.04
2.05
2.03
2.04
2.08
2.07
2.11
2.11
2.09
2.09
Swatch
Post-
Laundering
(u€i)
0.175
0.158
0.166
0.172
0.180
0.17
0.0686
0.0655
0.0567
0.0679
0.0731
0.07
0.088
0.092
0.097
0.101
0.0860
0.09
Wastewater
(u€i)
.61
.52
.69
.66
.63
1.62
.77
.77
.74
.74
.81
1.77
0.90
0.88
1.09
0.91
0.93
0.94
Procedural
Blank
(u€i)
0.0210
0.0212
0.0268
0.0266
0.0255
0.0242
0.00678
0.00697
0.00484
0.00650
0.00570
0.0062
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
Washing
Machine
(u€i)
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.038
Co-
Laundered
Clothing
(u€i)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.662
0.693
0.456
0.557
0.742
0.622
Total Post-
Laundering
(u€i)
.85
.74
.92
.90
.88
1.86
.88
.88
.84
.85
.93
1.88
.69
.71
.68
.61
.79
1.70
Material
Balance
87.7%
84.8%
93.2%
92.6%
90.9%
89.8%
92.3%
91.3%
90.2%
90.4%
94.9%
91.8%
81.0%
82.5%
79.6%
76.4%
85.6%
81.0%
aND = No detergent; RW = Swatch washed a second time; MC= Swatch washed with other clothing.
27
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5.0 CONCLUSIONS
In this study, experimental procedures were successfully demonstrated for consistently
applying and measuring 137Cs contamination on material swatches before and after laundering in
a conventional washing machine.
A summary of the efficacy of laundering to remove contamination from porous soft
materials is provided in Table 14. As shown, most of the 137CsCl spiked onto material swatches
was removed by laundering with Tide HE detergent and typical laundering conditions. Some
decrease in washing efficacy appears to result when laundering is done without Tide HE (91.8%
removal of 137Cs from cotton by laundering in cold/cold temperatures without detergent versus
94.4% removal of 137Cs from cotton by laundering in cold/cold temperatures with detergent).
This work does not imply that other detergents would or would not provide similar results, as
more work is needed in this area. Noticeable differences were not observed between other
laundering conditions.
Table 14. Summary of Laundering Efficacy Results
Material
Cotton
Cotton
Polyester
Cotton
Cotton
Cotton
Wash/Rinse
Temperature
Cold/Cold
Hot/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Cold/Cold
Detergent
Tide HE
Tide HE
Tide HE
None
Tide HE
Tide HE
Other
Laundering
Conditions
—
—
—
—
Repeat washing
Multiple
clothing
included in load
with test swatch
Average"
Decontamination
Factor
17.9
26.3
31.5
12.2
31.0
22.6
Average"
Percent
Removal
94.4%
95.9%
96.8%
91.8%
96.7%
95.6%
aAverage of five experiments.
137,
Material balance evaluations indicate that the bulk (generally over 80%) of the Cs
contamination on material swatches ends up in the washing machine wastewater for most
conditions tested. Laundering 137Cs contaminated material swatches with noncontaminated
clothing reduced the amount of 137Cs ending up in the wastewater - in that laundering condition,
approximately 30% of the 137Cs ends up on the originally noncontaminated clothing. Little 137Cs
28
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contamination appears to remain on the washing machine - although this study only examined
washing of low levels of one radioactive compound on small material swatches. Actual clothing
contaminated with higher levels or different radioactive compounds may yield different results.
These results suggest that laundering potentially contaminated clothing in a conventional
washing machine may assist people living outside of an exclusion zone to reduce their exposure
to radiation. The impact of the wastewater from the washing machine on the downstream
wastewater infrastructure must also be considered.
6.0 REFERENCES
1. World Health Organization, Frequently Asked Questions: Japan nuclear concerns, September
2011, http://www.who.int/hac/crises/jpn/faqs/en/index6.html. Accessed Aug 2012.
2. U.S. Department of State, Fact Sheet, "Guidance for Responding to Radiological and Nuclear
Incidents, http://travel.state.gov/travel/tips/health/health 1184.html, Accessed Aug 2012.
3. Canberra Industries Inc. 2002a. Model S573/S574 ISOCS/LabSOCS, Validation and
Verification Manual, v.4.0.
4. Canberra Industries Inc. 2002b. Model S573 ISOCS Calibration Software, User's Manual,
v.4.0.
5. Quality Management Plan. 2009. National Homeland Security Research Center, Office of
Research and Development, U.S. Environmental Protection Agency; Amendment to
Solicitation PR-CI-09-10042, Cincinnati Procurement Operations Division, posted July 13.
29
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United States
Environmental Protection
Agency
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
Office of Research and Development (8101R)
Washington, DC 20460
Official Business
Penalty for Private Use
$300
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