EPA/600/R-10/094 | November 2010 | www.epa.gov/ord
United States
Environmental Protection
Agency
Evaluation of Simple Green®
Commercial Cleaner for
Radiological Decontamination
on Indoor Surfaces
Office of Research and Development
National Homeland Security Research Center
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for
on
U.S. ENVIRONMENTAL AGENCY
CINCINNATI, OH
Office of Research and Development
National Homeland Security Research Center
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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 through Chemical, Biological, Radiological Nuclear Defense Information analysis
Center (CBRNIAC) Technical Area Task #503 (contract number SP0700-00-D-3180) with Battelle.
This report has been peer and administratively reviewed and has been approved for publication as an
EPA document. 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:
John Drake
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268
513-569-7164
drake.iohn(@.epa.gov
If you have difficulty accessing this PDF document, please contact Kathy Nickel
(Nickel.Kathy@,epa. gov) or Amelia McCall (McCall.Ameria@,epa.gov) for assistance.
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The 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.
An important goal of NHSRC's research is to develop and deliver information on decontamination
methods and technologies to clean up CBR contamination. When directing such a recover}'
operation. EPA and other stakeholders must identify and implement decontamination technologies
that are appropriate for the given situation. In certain situations following an accidental or
intentional release of radiological materials (including terrorist incidents such as a radiological
dispersal device (RDD) or "dirty bomb"), off-the-shelf, household cleaners may provide the clean up
that is needed. This document provides information on ability of the first such household cleaner we
examined to decontaminate indoor surfaces in a residential setting.
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.
Oregon7 Sayles, Ph.D., Acting Director
National Homeland Security Research Center
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The U.S. Environmental Protection Agency's (EPA)
National Homeland Security Research Center (NHSRC)
is helping to protect human health and the environment
from adverse impacts resulting from acts of terror by
carrying out performance tests on homeland security
technologies. In this investigation, NHSRC selected the
commercial cleaner Simple Green® and evaluated its
ability to remove radioactive cesium (Cs-137) from the
surface of multiple building materials found regularly
in homes. These materials include: wood finished with
polyurethane, vinyl flooring, painted wallboard, plastic
laminate, and polished granite.
Experimental Procedures. Simple Green® is a
concentrated multipurpose cleaner sold commercially.
The manufacturer recommends that a 1:10 dilution
(described as medium strength) of the Simple Green®
concentrate be used for "everyday" household use.
Because this is a strength likely to be already prepared
for normal household use, this concentration was
selected for use during this evaluation. For each
surface material, six 15 centimeter (cm) x 15 cm
coupons were contaminated with approximately 1
microCurie (iiCi) of Cs-137 per coupon. The amount of
contamination deposited on each coupon was measured
using gamma spectroscopy. Three coupons (in a
horizontal orientation) of each surface material were
decontaminated with 1:10 Simple Green® and three were
decontaminated with water. The diluted Simple Green®
(DSG) or water was sprayed onto the coupon surface
and the entire surface was then scrubbed with a brush in
a circular motion. The surfaces were then wiped with a
cloth dampened with water and then dried with a clean
dry disposable towel.
Results. The percent removal (%R) and
decontamination factor (DF) were calculated for each
surface coupon material. The decontamination of two of
the surface materials, plastic laminate and vinyl flooring,
resulted in a %R of more than 93% for both DSG
and water. The decontamination of wood coated with
polyurethane resulted in %R values of approximately
65% for both DSG and water. The decontamination of
granite and painted wallboard resulted in average %R
values between 7% and 14%. Of these surface materials.
only plastic laminate exhibited a statistically significant
difference between the %R for DSG and that for water.
The similarity between the %R produced by DSG and
water was somewhat unexpected because the presence of
the DSG would be expected to increase the effectiveness
of the cleaning compared to the cleaning performed with
only water. In general, the less porous materials (plastic
laminate and vinyl flooring) were decontaminated more
effectively than the more porous materials (wood and
painted wallboard). The decontamination effectiveness
was more dependent on the porosity of the surfaces
as opposed to the use of DSG or not. In addition, the
surfaces used during this evaluation were all cleaned
prior to contamination. The results might be different
if the surfaces were dirty or grimy. In these cases, the
cleaning properties of Simple Green® may be more
effective in mobilizing radionuclide contamination than
water. Some additional decontamination experiments
were performed with granite coupons from different
sources. Data from these experiments suggested that the
removal of cesium from the granite was dependent on
the surface characteristics of the granite.
Deployment and Operational Factors. During this
evaluation, the DSG was applied at a rate consistent
with the manufacturer's recommendation for general
use of the product, which equated to approximately 15
seconds per coupon, or 5 m2/hour. Because Simple
Green® is a household cleaner, no skills or specialized
training were required, and the only required tools were
a spray bottle, brush, and disposable towels, making
the method very portable. Two disposable towels
were used for each surface coupon. The disposable
towels made up the entirety of the secondary waste
as all the liquid was absorbed into the towels. The
health physicist overseeing the health and safety
aspects of this evaluation collected wipe samples from
the gloves of the person performing decontamination
with the DSG and water once during the evaluation of
each surface material to determine the likelihood of
worker contamination when using this decontamination
approach. In all instances, there was no measurable
activity- on the gloves, indicating that the gloves had not
become contaminated even though in some cases most
of the CS-137 had been removed from the coupons.
Personal contamination was apparently prevented
because the gloves did not come into contact with the
surface of the coupons. The technician was using the
brush and towels at all times to remain protected from
contamination. Lastly, a one-liter container of Simple
Green® concentrate costs approximately $10. Following
the method used during this evaluation, a one-liter
container costing approximately $10 would correspond
to a material only cost of approximately $0.06/m2 to use
DSG as a decontamination agent.
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Contributions of the following individuals and organizations to the development of this document are
gratefully acknowledged.
United States Environmental Protection Agency (EPA)
John Drake
Emily Snyder
Tonya Nichols
Eletha Brady-Roberts
United States Department of Energy's Idaho National Laboratories
United States Department of Energy's Lawrence Livermore National Laboratories
Robert Fischer
Battelle Memorial Institute
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Disclaimer iii
Foreword iv
Executive Summary
Acknowledgments vi
Abbreviations/Acronyms ix
1.0 Introduction 1
2.0 Technology Description 3
3.0 Experimental Details 5
3.1 Prc-cvaluation Preparation 5
3.1.1 Surface Coupon Preparation 5
3.1.2 Coupon Contamination 5
3.1.3 Measurement of Activity on Coupon Surface 6
3.2 Evaluation Procedures 6
4.0 Quality Assurance/Qualify Control 9
4.1 Intrinsic Germanium Detector 9
4.2 Audits 9
4.2.1 Performance Evaluation Audit 9
4.2.2 Technical Systems Audit 10
4.2.3 Tesf/QA Plan Deviations 10
4.2.4 Data, Quality Audit 10
4.3 QA/QC Reporting 10
5.0 Evaluation Results 11
5.1 Decontamination Efficacy 11
5.2 Deployment and Operational Factors 13
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6.0 Performance Summary 15
6.1 Decontamination Efficacy 15
6.2 Deployment and Operational Factors 15
7.0 References 17
Appendix Additional Granite Results 19
Figures
Figure 2-1. Bottle of Simple Green® concentrate 3
Figure 3-1. Demonstration of contaminant application technique 6
Figure 3-2. Laminate coupon being scrubbed with brush after DSG application 7
Tables
Table 3-1. Replicates of Coupons of Various Materials 7
Table 4-1. Calibration Results - Difference from Th-228 Calibration Energies 9
Table 4-2. NTST-TraceableEu-152 Activity Standard Check 10
Table 5-1. Decontamination Efficacy Results 12
Table 5-2. Operational Factors Gathered from the Evaluation 14
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ANSI
ASTM
BG
BQ
CBRNIAC
Cs
cm
DARPA
DF
DHS
DOD
DSG
EPA
Eu
HPGe
IEEE
INL
keV
L
u€i
nig
mL
inR
NHSRC
NIST
ORD
QA
QC
QMP
%R
RCT
RH
RML
TSA
American National Standards Institute
ASTM International
background
Becquerel
degrees Celsius
Chemical, Biological. Radiological, Nuclear Defense Information Analysis
Center
cesium
centimeters
Defense Advanced Research Projects Agency
decontamination factor
Department of Homeland Security
Department of Defense
diluted Simple Green®
U.S. Environmental Protection Agency
europium
high purity germanium
Institute of Electrical and Electronics Engineers
Idaho National Laboratory
kiloelectron volt(s)
liter
micro Curie
milligrams
millilitcrs
mil lire m
National Homeland Security Research Center
National Institute of Standards and Technology
Office of Research and Development
quality assurance
quality control
Quality Management Plan
percent removal
radiological control technician^)
relative humidity
Radiological Measurement Laboratory
technical svstems audit
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1.0
Introduction
The U.S. Environmental Protection Agency's (EPA)
National Homeland Security Research Center
(NHSRC) is helping to protect human health and the
environment from adverse effects resulting from acts
of terror. NHSRC is emphasizing decontamination
and consequence management, water infrastructure
protection, and threat and consequence assessment.
In doing so. NHSRC is working to develop tools and
information that will improve the ability of operational
personnel to detect the intentional introduction of
chemical, biological, or radiological contaminants on or
into buildings or water systems, to contain or mitigate
these contaminants, to decontaminate affected buildings
and/or water systems, and to dispose of contaminated
materials resulting from clean-ups.
NHSRC is looking at a range of issues which would
need to be addressed in the aftermath of terrorist use
of a radiological dispersal device in an urban area. In
the early phase of response to such an event evacuation
zones would have been established based on predictions
of contamination levels in affected areas, requiring
members of the public to vacate their homes and
businesses. As contamination levels became better
understood, based on surveys and characterization
efforts, some previously restricted areas would be
released, allowing residents to return to homes and
businesses previously off-limits. Returning residents
may be concerned about the possibility of small amounts
of contamination having been brought into their homes.
for instance by being tracked in on shoes or brought
in on clothing and personal items, and may wish to
perform some cleaning activities themselves. In this
study, NHSRC sought to examine the merits of using
common commercially available cleaning agents for
decontamination of surfaces inside a residence which
might be only very slightly contaminated. In this study
NHSRC examined a range of possible cleaning products
and selected one product for the initial evaluation.
Criteria considered in the selection process included
(1) wide availability through commercial suppliers
(major retail chain stores, grocery stores, pharmacies.
department stores, hardware stores), (2) likelihood of
the availability of significant quantities, (3) consistent
formulation across suppliers and geographic regions,
(4) applicability to multiple surface types, and (5) cost.
Based on a survey of available products, one of the
products which seemed to best meet these criteria was
selected for the initial evaluation. The product selected
was Simple Green®- The study concentrated primarily
on evaluating the ability of Simple Green® for removal
of radioactive cesium isotope (Cs-137) from several
common indoor surfaces. A peer-reviewed test/QA plan1
was developed and followed to generate the following
performance information:
• Decontamination efficacy, defined as the extent
of radionuclide removal following use of Simple
Green®.
« Deployment and operational factors, including the
approximate rate of surface area decontamination,
applicability to irregular surfaces, skilled labor
requirement, portability, secondary waste
management, and cost associated with use of Simple
Green®.
This evaluation was conducted throughout May and
June of 2010. All of the experimental work took
place in a radiological contamination area at the U.S.
Department of Energy's Idaho National Laboratory
(INL). This report describes the quantitative results and
qualitative observations gathered during the evaluation
of Simple Green®. Battelle and EPA were responsible
for QA oversight. The Battelle QA Manager conducted
a technical systems audit (TSA) during the evaluation as
well as a data quality audit of the evaluation data.
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2.0
Technology Description
Simple Green® is a commercially available multi-
purpose cleaner that was evaluated for its ability to
decontaminate radiological contamination. The cleaner
is sold as a concentrate and is typically diluted prior
to cleaning multiple surfaces and contaminants. The
dilution level of one part Simple Green® concentrate to
nine parts ASTM International (ASTM) Type 12 water
(hereafter referred to as simply water) for a 1:10 dilution
factor was used for this evaluation. The manufacturer
recommends that a 1:10 dilution of the Simple Green®
concentrate be used for "everyday" household use.
Because this dilution level is likely to be prepared
already for normal household use, this dilution level was
selected for use during this evaluation. This dilution
level corresponds to the "medium everyday strength"
on the Simple Green® "Quick-Mix Guide" from the
Simple Green® website (www. simple green, com) and will
be referred to throughout this report as diluted Simple
Green® (DSG).
Figure 2-1. Bottle of Simple Green® concentrate.
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3.0
Experimental Details
3.1 Pre-evaluation Preparation
3.1.1 Surface Coupon Preparation
The surface coupons used for the evaluation were
composed of common surface materials that would
likely be decontaminated in a residential setting. The
selection of coupon materials involved consideration of
likely pathways for radiological contamination to present
a personal health hazard. It was decided that coupon
materials should represent those commonly found in
food preparation and personal hygiene areas, and are
listed below. In addition to Hie five materials listed,
stainless steel was used as a baseline or control material
for comparison. The materials were obtained from
home improvement or lumber stores. The outline of the
coupons was measured and marked onto the surface of
the material and the material was cut using a material-
appropriate saw and blade. The various materials
were cut into approximately 15 centimeters (cm) x 15
cm coupons and had surface finishes representative of
the surface finish that would typically be found in a
residential setting (e.g. countcrtops. tabletops. flooring,
walls, etc.). Some of these materials were rather thin
so they were mounted to a plywood support using an
epoxy resin so the coupons could be measured using
the existing detector geometry set up for coupons that
are approximately 4 cm thick. Seven coupons of each
surface material were prepared for testing.
These surface coupons were made from:
« Wood finished with polyurethane - wood cut
from the middle of doors of a bathroom vanity
(American Classics. Medium Oak Model KB36-MO
cabinet, Haddonfield. NJ) stained with two coats of
polyurethane
* Vinyl flooring (Armstrong, Model 26295061,The
Home Depot, Idaho Falls. ID)
• Painted wall board (SHEETROCK* Brand
FIRECODE® C Core Gypsum Panels, Lowes®,
Idaho Falls, ID) with 2 coats of Pastel Base Behr
Premium Plus Semi-Gloss Enamel paint (The Home
Depot, Idaho Falls, ID)
• Plastic laminate - Wilsonart® 4728K-350-52 (The
Systemcenter Inc., Honolulu, HI)
* Polished granite - India granite (Biscuit Brown.
Mickelson Marble, Idaho Falls, ID)
The wood, painted wallboard, and granite represent
porous surfaces while the vinyl flooring and plastic
laminate represent nonporous surfaces. Prior to
contaminant application, the coupon surfaces were
visually examined for obvious cracks or abnormalities
and, if none were found, the coupon surfaces were
cleaned with a soft nylon brush and water and allowed
to air dry for approximately 24 hours. The side of each
coupon was marked with an identifying number using
a permanent marker. The edges of the coupons were
sealed with epoxy prior to contaminant application
to protect against the possibility of any contaminant
solution seeping into the coupons through the edges and
to ensure that Cs-137 was applied only to the surface of
the coupons.
3.1.2 Coupon Contamination
Coupons were contaminated by spiking individually with
2.5 milliliters (mL) of aqueous solution that contained
0.26 milligrams (mg)/liter (L) Cs-137 as a solution of
cesium chloride, corresponding to an activity level of
approximately 1 microCurie (|iCi) over the 225 square
centimeter (cm2) surface. Application of the Cs-137
in an aqueous solution was justified because even if
Cs-137 were dispersed in particle form following a
radiological dispersion device or "dirty bomb" event,
cesium chloride can take up moisture from the air and go
fully or partially into solution before the surfaces could
be decontaminated. In addition, from an experimental
standpoint, it is much easier to apply liquids, rather than
dry particles, homogeneously across the surface of the
coupons. The liquid spike was delivered to each coupon
using an aerosolization technique developed by INL
under a Defense Advanced Research Projects Agency
(DARPA) and a U.S. Department of Homeland Security
(DHS) project3.
The aerosol delivery device was constructed of two
syringes. The plunger and needle were removed from
the first syringe and discarded. Then a compressed
nitrogen gas line was attached to the rear of the syringe.
The second syringe contained the contaminant solution
and was equipped with a 27 gauge needle, which
penetrated through the plastic housing near the tip of
the first syringe. Compressed nitrogen flowing at a rate
of approximately 1 - 2 L per minute created a turbulent
flow through the first syringe. When the contaminant
solution in the second syringe was introduced, this
solution became nebulized by the turbulent gas flow. A
fine aerosol was ejected from the tip of the first syringe,
creating a controlled and uniform spray of fine liquid
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droplets onto the coupon surface. The contaminant spray
was applied all the way to the edges of the coupon,
which were taped (after having previously been sealed
with epoxy) to ensure that the contaminant was applied
only to the surfaces of the coupons. The photographs
in Figure 3-1 show this procedure being performed
using a nonradioactive, nonhazardous aqueous dye to
demonstrate that the 2.5 mL of contaminant solution is
effectively distributed across the surface of a coupon.
Because the gamma radiation from each coupon was
measured before and after application of DSG and water,
differences in contaminant load between coupons is also
not critical. However, the acceptable upper and lower
limits for the target amount of gamma radiation applied
to each coupon prior to application of the DSG or water
was set at 0.5 to 1.5 uCi.
Radionuclide activities on coupons were calculated
based on efficiency, emission probability, and half-life
values. Decay corrections were made based on the date
and the duration of the counting period. Full RML
gamma counting QA/quality control (QC), as described
in the test/QA plan, was employed and certified
results were provided. The measurement of gamma
radiation from the coupon surfaces is not a destructive
measurement technique; therefore, the same coupons that
were spiked with Cs-137 and had the gamma radiation
measured were used for application of the DSG or water.
3.2 Evaluation Procedures
Prior to the start of testing, a "dry run" of the
experimental design was performed to determine the
Figure 3-1. Demonstration of contaminant application technique.
3.1.3 Measurement of Activity on
Coupon Surface
Each contaminated coupon was allowed to air dry
until the surface no longer appeared wet and then was
transported to the INL Radiological Measurement
Laboratory (RML) for measurement of the Cs-137
gamma radiation from the surface of each coupon.
Gamma radiation from the surface of each concrete
coupon was measured to quantify contamination levels
both before and after decontamination with DSG or
water. These measurements were made using an intrinsic,
high purity germanium detector (Canberra LEGe Model
GL 2825R/S, Meriden, CT). After being placed in the
detector, each coupon was measured until the average
activity level of Cs-137 from the surface stabilized
to a relative standard deviation of less than 2%. The
low activity coupons (less than 2 millirem (mR)/hour
as qualitatively surveyed by the radiological control
technicians [RCTs]) were counted for approximately
one hour while the more highly contaminated coupons
(more than 2 mR/hour) were counted for approximately
20 minutes. Gamma-ray spectra acquired from Cs-137-
contaminated coupons were analyzed using RML data
acquisition and spectral analysis programs.
exact approach to using DSG and ASTM water as
surface decontamination agents. The resulting approach
included the decontamination of one coupon at a time
positioned horizontally within a secondary container
and the decontamination procedure was the same for
the DSG and water. The steps included: 1) application
of the DSG or water across the surface of each coupon
by squeezing the trigger of a spray bottle (Plastic Spray
Bottle, Wal-Mart, Idaho Falls, Idaho) three times, 2) a
hand brush was used to scrub the surface using a circular
motion, 3) the surface was wiped with a disposable
towel (Wypall X60, Kimberly Clark, Neenah, WI)
moistened with 10 mL of water, and 4) a clean dry towel
was used to dry the surface completely. Figure 3-2
shows a picture of the decontamination approach being
performed. The temperature and relative humidity (RH)
were recorded throughout the two-day evaluation (TMH-
360 Digital Thermometer, EAI Education, Oakland, NJ).
The temperature in the laboratory was consistently
within the range of 22.8 degrees Celsius (°C) to 23.9 °C
and the RH was between 18% and 21%.
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Figure 3-2. Laminate coupon being scrubbed with brush
after DSG application.
Table 3-1 presents the experimental design that was
completed during this evaluation. For each surface
material, six coupons were contaminated with Cs-137.
Three of the coupons were decontaminated with DSG
and three with water. Both DSG and water were used
to determine if the DSG has a decontamination efficacy
beyond that of water. One coupon of each surface
material was left uncontaminated and decontaminated
with DSG to serve as a method blank. These control
coupons were stored along with the rest of the coupons
from the time of preparation through the completion of
the evaluation to evaluate the possibility of cross
contamination. In addition, on each day of testing,
one stainless steel coupon (Multipurpose Stainless
Steel, Model 9085K41, McMaster-Carr, Princeton,
NJ), contaminated with Cs-137, was decontaminated
with both DSG and water. The contaminated stainless
steel coupons were included as an extremely smooth,
nonporous control to demonstrate that a surface can
be decontaminated successfully. Throughout the
evaluation, three coupons of each surface material that
were not contaminated were measured for background
(BG) gamma radiation.
Table 3-1. Replicates of Coupons of Various Materials
Blank, No
Material _ . ,.
Decontamination
Wood (polyurethane)
Vinyl
Painted wall board
Plastic laminate
Polished granite
Stainless steel control
3
3
3
3
3
3
Blank,
Decontaminated
with Simple Green
1 per day
1 per day
1 per day
1 per day
1 per day
none
Contaminated,
Decontaminated
with Water
3
3
3
3
2t
1 per day
Contaminated,
Decontaminated with
Simple Green
3
3
3
3
3
1 per day
o granite coupons were used because of limited coupon availability.
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4.0
Quality Assurance / Quality Control
QA/QC procedures were performed in accordance with
the test/QA plan1 for this evaluation.
4.1 Intrinsic Germanium Detector
The germanium detector was calibrated three times
during the Simple Green® evaluation. The calibration
was performed in accordance with standardized
procedures from the American National Standards
Institute (ANSI) and the Institute of Electrical and
Electronics Engineers (IEEE).4 In brief, detector
energy was calibrated using thorium (Th-228) daughter
gamma rays at 238.6, 583.2, 860.6, 1620.7, and 2614.5
kiloelectron volts (keV). Table 4-1 gives the difference
between the known energy levels and those measured
following calibration. The energies were compared to
the previous 30 calibrations to confirm that the results
were within three standard deviations of the previous
calibration results. All the calibrations fell within this
requirement.
counting QA process for certified results.
The background activity of the coupons was determined
by analyzing three coupons from each type of surface
material used for this evaluation. The ambient activity
level of these coupons was measured for one hour. No
activity (attributable to Cs-137) was detected above
the minimum detectable level of 2x 10"4 uCi on these
coupons. Because the background activity was not
detectable, no background subtraction was required.
Throughout the evaluation, duplicate measurements
were taken in 12 instances to evaluate the repeatability
of the activity measurement with the different surface
materials. Following coupon contamination, six coupons
were measured twice. Following the decontamination
of those six coupons using DSG or water, those same
coupons were measured twice again. Six of the 12
duplicate pairs exhibited a difference in activity levels
between the two measurements of less than 1%, while
Table 4-1. Calibration Results - Difference from Th-228 Calibration Energies
Calibration Energy Levels (keV)
Date
5-18-2010
6-10-2010
6-14-2010
Energy 1
238.632
-0.004
-0.002
-0.004
Energy 2
583.191
0.015
0.008
0.010
Energy 3
860.564
-0.030
-0.016
-0.005
Energy 4
1620.735
-0.330
-0.154
-0.180
Energy 5
2614.533
0.033
0.019
0.029
Gamma ray counting was continued on each coupon
until the activity level of Cs-137 on the surface had a
relative standard deviation (RSD) of less than 2%. As
mentioned in Section 3.1.3, the low activity coupons
were counted for approximately one hour while the
more highly contaminated coupons were counted for
approximately 20 minutes. The final activity assigned to
each coupon was a compilation of information obtained
from all components of the electronic assemblage that
comprise the "gamma counter," including the raw data
and the spectral analysis described in Section 3.1.3.
Final spectra and all data that comprise the spectra were
sent to a data analyst who independently confirmed
the "activity" number arrived at by the spectroscopist.
When both the spectroscopist and an expert data analyst
independently arrived at the same value the data were
considered certified. This process defines the full gamma
the other six duplicate pairs had a difference of less
than 4% between the two measurements, within the
acceptable difference of 5%.
4.2 Audits
4.2.1 Performance Evaluation Audit
The INL RML performed regular checks of the accuracy
of the Th-228 daughter calibration standards (during
the time when the detector was in use) by measuring
the activity of a National Institute of Standards and
Technology (NIST)-traceable europium (Eu-152)
standard (in units of Becquerel, BQ) and comparing it
to the accepted NIST value. Results within 7% of the
NIST value are considered to be within acceptable limits.
The Eu-152 activity comparison is a routine QC activity
performed by the INL RML, but for the purposes of this
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evaluation serves as the performance evaluation
(PE) audit, an audit that confirms the accuracy of the
calibration standards used for the instrumentation critical
to the results of an evaluation. Table 4-2 gives the
results of each of the audits applicable to the duration
of the evaluation. All results are below the acceptable
difference of 7%.
4.2.4 Data Quality Audit
The Battelle QA Manager verified all of the raw data
acquired during the evaluation and transcribed into
spreadsheets for use in the final report. The data were
traced from the initial raw data collection, through
reduction and statistical analysis, to final reporting, to
ensure the integrity of the reported results.
Table 4-2. NIST-Traceable Eu-152 Activity Standard Check
Date
NIST Activity (BQ)
INL RML Result (BQ) Relative Percent Difference
April 2010
125,000
121,600
2.76%
May 2010
125,000
120,600
3.58%
June 2010
125,000
121,100
3.17%
4.2.2 Technical Systems Audit
The Battelle QA Manager conducted a TS A during
testing at INL to ensure that the evaluation was
performed in accordance with the test/QA plan.1
As part of the audit, the actual evaluation procedures
were compared with those specified in the test/QA plan1
and the data acquisition and handling procedures were
reviewed. No significant adverse findings were noted in
this audit. The records concerning the TSA are stored
indefinitely with the Battelle QA Manager.
4.2.3 Test/QA Plan Deviations
Throughout testing few deviations to the test/QA plan
were documented. These deviations as well as the
impact on the evaluation are shown below:
• Clarification of the decontamination procedure used
for DSG and water (as already described in Section
3.2) - no impact to the evaluation as this deviation
provided additional detail about the decontamination
method following the "dry run"
• Use of D SG rather than water for method blanks
- positive impact to the evaluation as use of DSG
provided for a more thorough evaluation of possible
cross contamination
• Clarification of the source of wood used for wood
coupons - no impact to the evaluation
• Clarification of the source of granite used for
coupons - no impact to the evaluation
• Two granite coupons were decontaminated with
water instead of three - the impact to the evaluation
is the collection of slightly less repeatability data
for granite decontaminated with water
4.3 QA/QC Reporting
Each assessment and audit was documented in
accordance with the test/QA plan.1 The Battelle QA
Manager prepared the draft assessment report and sent
it to the Test Coordinator and Battelle Program Manager
for review and approval. The Battelle QA Manager then
sent the final assessment report to the EPA and Battelle
staff.
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5.0
Evaluation Results
5.1 Decontamination Efficacy
The decontamination efficacy of DSG was determined
for each contaminated coupon in terms of percent
removal (%R) and decontamination factor (DF). Both
terms provide a means of representing the extent of
decontamination accomplished by a technology. The
%R presents efficacy as a percent relative to the initial
activity and the DF is the ratio of the initial activity to
the final activity or the factor by which the activity was
decreased. These terms are defined by Equation 1 below:
%R = (l-A/Ao) x 100% and DF = Ao/Af (1)
where:
Ao = the radiological activity of the coupon before
application of DSG or water
Af is radiological activity from the surface of the
coupon after treatment.
Table 5-1 gives the activity level of each surface
coupon after contamination with Cs-137, the activity
level following decontamination with either DSG or
water, and the %R and DF for DSG and water for
each surface coupon. The target activity for each of
the contaminated coupons (pre-dccontamination) was
within the acceptable range of 1 uCi ± 0.5 uCi. The
overall average (plus or minus one standard deviation)
of the contaminated coupons was 1.17 uCi + 0.14 uCi,
a variability of 12%. For all surface coupons, the post-
decontamination coupon activities were less than the pre-
decontamination activities showing an overall reduction
in activity. However, the magnitude of decrease between
the surface coupon materials varied widely.
A paired t-test was performed on the data resulting
from decontamination due to DSG and water. The
probabilities (p) associated with these paired t-tests
provide the probability that the %R and DF values
from DSG and water come from data sets that are the
same. Therefore, probabilities of less than 0.05 indicate
significant differences between the two data sets at the
95% confidence interval.
For plastic laminate, the average %R for
decontamination using DSG and water was 97.6%R ±
0.2%R and 93.4%R ± 1,1%R, respectively. The DF
values for DSG and water were 41.3 ±3.8 and 15.4 ±
2.3. respectively. The paired t-tcst revealed a significant
difference (p=0.021) between the %R produced by
decontamination using DSG and the %R produced by
decontamination using water as well as between the
DF resulting from each decontamination approach
(p=0.0077).
The average %R for DSG was higher than for water.
This result indicates that for plastic laminate, albeit
slightly, DSG removed Cs-137 more effectively than
water.
The decontamination of vinyl flooring with DSG
(96.8%R ± 0.3%R,) and water (96.0%R ± 0.7%R)
resulted in average %R values of greater than 95% and
DF values of 31.0 ± 3.2 for DSG decontamination and
25.5%R ± 4.8%R for water. Even though the uncertainty
around these values was rather small (<1% in the case
of %R), the mean values were very similar resulting in a
paired t-test (%R p=0.30, DF p=0.31) that indicated that
there was no significant difference at the 95% confidence
interval between the decontamination of the vinyl
flooring using DSG and that using water.
For the coupons made of wood coated with
polyurethane, the degree of decontamination was
considerably less than for the previous two surface
materials. The average %R for DSG and water was
67.2%R ± 3.5%R and 68.1%R ± 6.7%R, respectively,
while the average DF values were 3.1 ± 0.3 and 3.2 ±
0.6, respectively. The results from each decontamination
approach were very similar, which was confirmed with
a paired t-test (%R p=0.89, DF p=0.82) meaning that no
statistical difference between the performance of DSG
and that for water was observed.
The granite and painted wallboard coupons were
decontaminated to a much lesser extent than the
previously discussed surface materials. For the granite
coupons, the average %R values for DSG and water were
13.9%R± 1.6%Rand 11.7%R± 3.3%R, respectively,
while the average DF values were 1.2 ± 0.0 and 1.1 ±0.0
for DSG and water, respectively. Three granite coupons
were decontaminated with DSG. However, because
only five identical granite coupons could be obtained
at (lie time of testing, only two granite coupons were
decontaminated with water. For the painted wallboard
coupons, the average %R for DSG and water was 9.5%R
± 1.7%R and 7.3%R ± 3.5%R, respectively, while the
average DF values were 1.1 ± 0.0 for DSG and water.
As was the case with the vinyl flooring and the wood,
a paired t-test showed that for granite (%R p=0.73, DF
p=0.74) and painted wallboard (%R p=0.42, DF p=0.42)
-------
Table 5-1. Decontamination Efficacy Results
Coupon Type-
Decon Agent
Plastic laminate - DSG
Plastic laminate - Water
Vinyl Flooring - DSG
Vinyl Flooring - Water
Wood - DSG
Wood - Water
Painted Wallboard- DSG
Painted Wallboard - Water
Granite - DSG
Stainless steel control Water
Predecon
(u€i)
0.93
1.16
1.06
0.96
1.14
1.18
1.35
1.37
1.27
1.35
1.38
1.43
1.35
1.23
1.19
1.15
1.07
1.15
0.93
1.22
1.18
1.08
1.02
1.05
1.17
1.16
1.13
1.17
1.12
0.92
1.12
1.14
1.20
Postdecon
(u€i)
0.0224
0.0310
0.0236
0.075
0.071
0.068
0.044
0.049
0.037
0.064
0.045
0.058
0.49
0.36
0.39
0.3
0.42
0.35
0.86
1.09
1.06
1.00
0.91
1.01
1.00
1.02
0.96
1.06
0.96
0.0234
0.04
0.059
0.05
%R
97.6
97.3
97.8
92.2
93.8
94.2
96.7
96.4
97.1
95.3
96.7
95.9
63.7
70.7
67.2
73.9
60.7
69.6
7.5
10.7
10.2
7.4
10.8
3.8
14.5
12.1
15.1
9.4
14.0
97.5
96.3
94.8
95.7
Avg
%R±SD
97.6 ±0.2
93.4 ±1.1
96.8 ±0.3
96.0 ±0.7
67.2 ±3. 5
68.1 ±6.7
9.5 ±1.7
7.3 ±3. 5
13.9 ±1.6
11 7 + T T
%9 ± 0 8
O^ 1 _i_ C\ f^
yj.2 ± U.O
DF
41.5
37.4
44.9
12.8
16.1
17.4
30.7
28.0
34.3
21.1
30.7
24.7
2.8
3.4
3.1
3.8
2.5
3.3
1.1
1.1
1.1
1.1
1.1
1.0
1.2
1.1
1.2
1.1
1.2
39.3
27.3
19.3
23.1
Avg DF±SD
41. 3 ±3.8
15.4 ±2.3
31.0 ±3.2
25.5 ±4.8
3.1 ±0.3
3.2 ±0.6
1.1 ±0.0
1.1 ±0.0
1.2 ±0.0
11+00
33 3± 8 5
11 1 4- 1 1
21. 2 ±2.1
TTwo granite coupons were decontaminated with water.
-------
there was no significant difference between the %R or
DF values for DSG or water. An appendix provides
some additional data from coupons prepared from seven
different sources of polished granite.
All of the surface coupons for each of the five surface
types were collected from the same source and were
essentially identical. For each of those surface materials,
the method used for decontaminating with DSG and
water was shown to be reproducible. With the exception
of granite and painted wallboard, the materials that
exhibited the lowest average %R, the standard deviation
of the replicate %R values were less than 10% of the
average %R. In addition, plastic laminate and vinyl
flooring exhibited reproducibility of within less than 1%.
Even for granite and painted wallboard, the standard
deviations generated were less than 5%R.
Data for the stainless steel control coupons are also
listed in Table 5-1. Once during each day of testing a
contaminated stainless steel coupon was decontaminated
to show that a nonporous surface such as stainless steel
could be effectively decontaminated. For both DSG
and water, these coupons exhibited removals of greater
than 95%R. In addition, for each coupon material.
noncontaminated coupons were treated with the same
decontamination procedure with DSG and water to
determine whether or not cross-contamination was taking
place during the evaluation. No detectable activity was
measured on any of these method blank coupons.
Based on the data in Table 5-1 the performance of
the DSG and water was nearly identical. The two
nonporous surfaces, plastic laminate and vinyl flooring,
as well as the nonporous stainless steel controls were
decontaminated by more than 90%. The porous
surfaces of wood, painted wallboard, and granite were
decontaminated to a much lesser extent. Since DSG
is a product intended to provide enhanced cleaning
performance over simply using water, the fact that there
was generally no significant difference between using
DSG and water was unexpected. However, one possible
reason for the similar performance is that the coupon
surfaces were cleaned prior to contamination and were
free from dirt and grime. If dirty coupons had been
used it is possible that the DSG would have been a more
effective decontamination agent
5.2 Deployment
Factors
Table 5-2 summarizes qualitative and quantitative
practical information gained by the operator during the
evaluation of Simple Green®. All of the operational
information was gathered during use of DSG on a
variety of types of coupons positioned horizontally in
a laboratory hood. Some of the information given in
Table 5-2 could differ if DSG were applied to a larger
surface or to surfaces that were not evaluated during this
evaluation.
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Table 5-2. Operational Factors Gathered from the Evaluation
Parameter
Description/Information
Decontamination
rate
Approximately 15 seconds per coupon to accomplish routine of three sprays, scrub with
a brush, wipe with a damp towel, and dry with another clean, dry towel. Corresponds to
approximately 5 mVhour.
Applicability to
irregular surfaces
Wiping off irregular or rough surfaces is not likely to function well. This decontamination
technique seems best suited for smooth surfaces, as were exclusively used during this
evaluation.
Skilled labor
requirement
Simple Green® is a household cleaner. No skill or specialized training was required.
Extent of portability
The only required tools are a spray bottle of DSG (spray bottle would need to be purchased
separately as Simple Green® is purchased as a concentrate), a brush, and disposable towels.
These can be carried most places.
Secondary waste
management
Two disposable towels were used for each surface coupon, corresponding to approximately
4,000 cm3 of disposable towel waste per square meter of surface decontaminated. There
was no excess liquid waste as all the liquid was absorbed into the disposable towels.
Also, one brush was used and disposed of for each coupon. However, this detail was
an artifact of the experimental design. It is likely that one brush could be used for most
decontamination jobs.
Personal
contamination
The health physicist overseeing the health and safety aspects of this evaluation collected
wipe samples from the gloves of the person performing decontamination with the DSG and
water once during the evaluation of each surface material. In all instances, there was no
measurable activity, indicating that the gloves had not become contaminated even though in
some cases most of the Cs-137 had been removed from the coupons. Apparently, personal
contamination was prevented because the gloves did not come into contact with the surface
of the coupons. At all times, the technician was using the brush and towels to remain
protected from contamination.
Surface damage
No surface damage was visible.
Cost
A 1 liter container of Simple Green® concentrate costs approximately $10. Following the
methodology used during this evaluation, a cost of $ 10 for a liter of concentrate would
correspond to approximately $0.06/m2 (material only).
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6.0
Performance Summary
This section summarizes Battelle's results from the
evaluation of Simple Green®.
6.1 Decontamination Efficacy
The percent removal (%R) and decontamination factor
(DF) were calculated for each surface coupon material.
The decontamination of two of the surface materials,
plastic laminate and vinyl flooring, resulted in %R
values of more than 93% for both DSG and water. The
decontamination of wood coated with polyurethane
resulted in %R values of approximately 65% for both
DSG and water. The decontamination of granite and
painted wallboard resulted in average %R values
between 7% and 14%. Of these surface materials, only
plastic laminate exhibited a statistically significant
difference between the %R for DSG and that for water.
Simple Green® is a product intended to provide
enhanced cleaning performance over simply using
water. The fact that there was generally no significant
difference between using DSG and water was
unexpected. However, one possible reason for the similar
performance is that the coupon surfaces were cleaned
prior to contamination and were free from dirt and grime.
If dirt}' coupons had been used it is possible that the
DSG would have been a more effective decontamination
agent. In general, the less porous materials (plastic
laminate and vinyl flooring) were decontaminated more
effectively than the more porous materials (wood and
painted wallboard). The decontamination effectiveness
was more dependent on the porosity of the surfaces as
opposed to the use of DSG or not.
Some additional decontamination experiments were
performed with granite coupons from different sources.
Data from these experiments suggested that the removal
of cesium from granite was dependent on the surface
characteristics of the granite.
6.2 Deployment
Factors
Approximately 15 seconds per coupon were required to
accomplish the decontamination method used during this
evaluation which was consistent with the instructions
for use suggested by the manufacturer, corresponding
to a decontamination rate of approximately 5 m2/
hour. Because Simple Green® is a household cleaner,
no skills or specialized training were required, and
the only required tools were a spray bottle, brush, and
disposable towels making the method very portable.
Two disposable towels were used for each surface
coupon. The two disposable towels made up the entirety
of the secondary waste as all the liquid was absorbed
into the towels. The health physicist overseeing the
health and safety aspects of this evaluation collected
wipe samples from the gloves of the person performing
decontamination with the DSG and water once during
the evaluation of each surface material to determine
the likelihood of worker contamination when using this
decontamination approach. In all instances, there was
no measurable activity, indicating that the gloves had
not become contaminated even though in some cases
most of the CS-137 had been removed from the coupons.
Apparently, personal contamination was prevented
because the gloves did not come into contact with the
surface of the coupons. At all times, the technician was
using the brush and towels to remain protected from
contamination. Lastly, a one liter container of Simple
Green® concentrate costs approximately $10. Following
the method used during this evaluation, a cost of $10
for a one-liter container would correspond to a material
only cost of approximately $0.06/m2to use DSG as a
decontamination agent.
-------
-------
1. "Test/QA Plan for the Performance of Selected
Radiological Decontamination Processes on Urban
Substrates," Version 1.0. Battelle, Columbus, Ohio,
March 2009.
2. Annual Book of ASTM Standards, Water and
Environmental Technology, "Standard Specifications
for Reagent Water," Vol. 11.01, 1996.
3. Radionuclide Detection and Decontamination
Program. Broad Agency Announcement 03-013,
U.S. Department of Defense (DOD) Defense
Advanced Research Projects Agency (DARPA)
and Hie U.S. Department of Homeland Security,
classified program.
4. "Calibration and Use of Germanium Spectrometers
for the Measurement of Gamma Emission Rates
of Radionuclides," American National Standards
Institute. ANSI N42.14-1999. IEEE New York, NY
(Rev. 2004).
7.0
References
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-------
Appendix
Additional Granite Results
Table A. Additional Granite Decontamination
Efficacy Results
Coupon
Type-Decon
Agent
Granite -
DSQt
Granite -
Water1
Pre-
decon
(uCi)
1.21A
1.16B
1.21C
1.24D
1.2E
1.02F
1.17G
1.05G
Post-
decon
(uCi)
0.88
0.49
1.1
1.14
1.09
0.96
1.10
0.96
%R
27.3
57.8*
9.1
8.1
9.2
5.9
6.0
8.2
DF
1.4
2.4
1.1
1.1
1.1
1.1
1.1
1.1
T Letters in first data column are for reference to the granite descriptions
in Table B.
*DSG applied twice because brushing step omitted the first time.
The coupons described by the data in Table A were
unique compared to the rest of the surface materials
because seven of the eight coupons came from unique
sources of polished granite with slightly different
colors and surface characteristics. Because the
decontamination method was shown to be reproducible
for the other surface coupons (see main body of report),
it is likely that differences between the %R values for
the polished granite coupons are due to differences in
surface characteristics across the coupons rather than
measurement variability. For the polished granite
decontaminated with water, none of the coupons
exhibited %R values exceeding 10% regardless of the
surface characteristics. For the DSG decontaminated
coupons, there was a broad range of %R (9.1%R to
57.8%R). However, the coupon with the highest
removal had DSG application and towel wiping routine
performed twice because the brushing step had been
omitted following the first DSG application. The
technician then repeated the DSG application and towel
wiping routine, but this time included the brushing step.
Because the surface coupons were not from the same
source material and the application methods were not
identical, it is not possible to determine if there were
significant differences between the DSG and water
decontamination. Because of the variability in %R, it
seems likely that the DSG decontamination is highly
dependent on the surface characteristics of the polished
granite. Table B provides descriptions (including the
grain size, or size of stones making up the appearance of
the granite, and color) of the seven sources of polished
granite coupons.
Table B. Description of Granite Coupons
Coupon*
A
B
C
D
E
F
G
Grain
Size
(inch)
Ito2
1 and %
1/8 to !/4
1/8 to !/4
1/8 to !/4
1 and %
1/8 to !/4
Color
Black
Larger orange and gray
grains mixed with smaller
black grains
Mixture of brown and black
Orange grains
Red with black grains
Large orange grains with
smaller black grains
Black
'Letters are referenced to coupons in Table A.
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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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