Office of Research and DevelopmentNational Homeland Security Research Center

Assessment of the Fate of RDD Contamination after Laundering of Soft Porous Materials

EPA/600/R-12/053 | October 2012 | www.epa.gov/ord

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EPA 600/R-12/053 October 2012

Assessment of the Fate of RDD 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

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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

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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

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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 (µCi ) ................................................................................. 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

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ABBREVIATIONS AND ACRONYMS BEGe broad energy germanium COR 137Cs 137CsC1

Contracting Officer’s Representative cesium-137 cesium chloride

DF decontamination factor DOE DQI

U.S. Department of Energy data quality indicators

EPA GM HPGe ID

U.S. Environmental Protection Agency Geiger-Mueller high purity germanium identification number

in ISOCS keV

inch in situ object counting system kilo electron volt

LLRW µCi µL mL MDA NDA NIST

low level radioactive waste micro curie microliter milliliter minimum detectable activity non-destructive analysis National Institute of Standards and Technology

NHSRC National Homeland Security Research Center ORD PNNL PNWD

Office of Research and Development Pacific Northwest National Laboratory Pacific Northwest Division

QA QAPP

quality assurance quality assurance project plan

QC quality control QMP quality management plan %R percent removal RDD RW

radiological dispersal device repeat washing

TSA WA

technical systems audit work assignment

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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.

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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

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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 of RDD 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.

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=1818) [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 (µL) pipette, 0-100 µL (Eppendorf North America, Hauppauge,

NY) as shown in Figure 3. The specific concentration of the 137Cs was about 1 micro curie

(µCi)/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 µCi to 2.2 µCi. 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 µL of

1 µCi/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 µCi 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. 137CsCl 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 Wash/Rinse Temperature

Material Swatch (with 137Cs &

washed)

Positive Control Swatcha

(with 137Cs & not washed)

Procedural Blankb

(no 137Cs & washed)

Machine Blankc

(no 137Cs & washed)

Loadd

Cotton (CC)

Cold/Cold

1 2 1 1 1 2

1 1 3 1 4

1 1 5 1 6

1 1 7,8 1 9

Cotton (HC)

Hot/Cold

1 1 10 1 11

1 1 12,13, 14, 15

1 16 Polyester

(PC) Cold/Cold

1 2 1 17 1 1 18, 19,

20, 21 Cotton (ND)

Cold/Cold without

Detergent

1 1 1 22 1 1 23 1 24 1 25

1 1 26, 27, 28

Cotton (RW)

Cold/Cold with Repeat Wash Cycles

(RW)

1 1 1 29

1 30 1 1 31, 32,

33, 34 Cotton with

Multiple Clothing in Same Load

(MC)

Cold/Cold 1 1 1 35

1 36 1 1 37, 38,

39, 40 a To determine activity loss possibly resulting from experimental procedures. b To determine cross contamination within load. c 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

over a 100 square centimeter (cm2) 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.

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Table 2. Data Quality Indicators for Critical Measurements

Measurement Analysis Method

Accuracya Precisionb Minimum Detectable Activity

Completeness

DQI Actualc DQI Actual DQI Actual DQI How determined Actual

Activity of material swatches

Gamma Detector (BEGe)

± 6% of certified value

< 2.77% 20% <3.0% 1 .85E-04 µCi / swatch

2.01E-4 µCi / swatchd

95% Number of material swatches for which activity was measured/ total number of material swatches planned for analysis

100%

NDA count of entire washing machine

Gamma Detector (BEGe)

± 6% of certified value

< 2.77% NA NA 0.010 µCi/ machine

<0.0025 µCi/machine

100% 100% = NDA count was successfully made of entire washing machine

100%

Activity of wastewater

Gamma Detector (HPGe)

±10% of certified value

<10% 20% <20% 1 pCi/mL < 1.07 pCi/mLd

95% Number of wastewater samples for which activity was measured/ total number of wastewater samples planned for analysis

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) cBased 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.

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Table 3. Results from Material Background Measurements

Material Replicate Activity (μCi) Cotton 1 <0.000184

2 <0.000178 3 <0.000193 4 <0.000166 5 <0.000194 6 <0.000198 7 <0.000175

Polyester 1 <0.000198 2 <0.000201 3 <0.000213 4 <0.000184 5 <0.000205 6 <0.000166 7 <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

Prior Activity (µCi)

Post Activity (µCi)

Cotton (cold/cold) 1.98 ± 0.0871 1.96 ± 0.0856 Cotton (cold/cold) 2.03 ± 0.0882 1.97 ± 0.0854 Cotton (cold/cold) 2.01 ± 0.0880 1.98 ± 0.0859 Polyester (cold/cold) 1.90 ± 0.0847 1.90 ± 0.0825 Polyester (cold/cold) 1.97 ± 0.0856 1.91 ± 0.0830 Polyester (cold/cold) 1.95 ± 0.0851 1.92 ± 0.0840 No Detergent (ND) 2.14 ± 0.0932 2.02 ± 0.117 Repeat Washing (RW) 2.15 ± 0.0930 2.02 ± 0.104 Multiple Clothing (MC) 2.16 ± 0.0940 2.18 ± 0.097

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3.1.4 Procedural Blanks

As shown in Table 1, one procedural blank – a swatch not spiked with 137CsCl – 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

(µCi )a Cotton Cold/Cold – 1 0.0144 ± 0.00108 Cotton Cold/Cold – 2 0.0139 ± 0.00104 Cotton Cold/Cold – 3 0.0158 ± 0.00136 Cotton Cold/Cold – 4 0.0152 ± 0.00105 Cotton Cold/Cold – 5 0.0148 ± 0.00128 Cotton Hot/Cold – 1 0.0131 ± 0.00117 Cotton Hot/Cold – 2 0.0149 ± 0.00122 Cotton Hot/Cold – 3 0.0137 ± 0.000950 Cotton Hot/Cold – 4 0.0146 ± 0.00129 Cotton Hot/Cold – 5 0.0142 ± 0.00138 Polyester Cold/Cold – 1 0.000379 ± 0.0000560 Polyester Cold/Cold – 2 0.000715 ± 0.0000769 Polyester Cold/Cold – 3 0.000800 ± 0.0000912 Polyester Cold/Cold – 4 0.000644 ± 0.0000738 Polyester Cold/Cold – 5 0.000448 ± 0.0000753 Cotton Cold/Cold; No Detergent – 1 0.0210 ± 0.00198 Cotton Cold/Cold; No Detergent – 2 0.0212 ± 0.00228 Cotton Cold/Cold; No Detergent – 3 0.0268 ± 0.00250 Cotton Cold/Cold; No Detergent – 4 0.0266 ± 0.00192 Cotton Cold/Cold; No Detergent – 5 0.0255 ± 0.00178 Cotton Cold/Cold; Repeat Washing – 1 0.00678 ± 0.000745 Cotton Cold/Cold; Repeat Washing – 2 0.00697 ± 0.00133 Cotton Cold/Cold; Repeat Washing – 3 0.00484 ± 0.00128 Cotton Cold/Cold; Repeat Washing – 4 0.00650 ± 0.000823 Cotton Cold/Cold; Repeat Washing – 5 0.00570 ± 0.000705

aCo-laundered with material swatches contaminated with approximately 2 µCi of 137CsCl.

3.1.5 Machine Blanks

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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 Laundering Conditions Load Activity (µCi )

Cotton Cold/Cold 2 <0.000212 Cotton Cold/Cold 4 <0.000229 Cotton Cold/Cold 6 <0.000198 Cotton Cold/Cold 9 <0.000257 Cotton Hot/Cold 11 <0.000253 Cotton Hot/Cold 16 <0.000235 Cotton Cold/Cold; No Detergent 24 0.000381 Cotton Cold/Cold; No Detergent 25 0.000394 Cotton Cold/Cold; Repeat Washing 30 0.000140 Cotton Cold/Cold; Multiple Clothing

36 0.000891

3.1.6 Equipment Calibration

The HPGe system used for measuring 137Cs 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

16

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.(5) .

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).(5) 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.

17

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.

18

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 µCi 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 µCi) 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 µCi using a 20 minute counting

time.

Table 7. Results from Demonstration of Contamination Application Procedure

Detector 1 Activity (µCi)

Detector 2 Activity (µCi)

Cotton-1 1.98 ± 0.042 1.94 ± 0.049 Cotton -2 2.03 ± 0.041 1.99 ± 0.051 Cotton -3 2.01 ± 0.042 1.97 ± 0.049 Polyester-1 1.90 ± 0.043 1.83 ± 0.049 Polyester -2 1.97 ± 0.040 1.93 ± 0.049 Polyester -3 1.95 ± 0.040 1.90 ± 0.048

19

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 Swatcha Detection Efficiency at 661.65 keV [γ-1] Cloth Type Thickness Weight Detector 4802 Detector 4862 Cotton 3/16” Dry: 9 g 6.193E-03 4.263E-03

Damp: 19 g 6.145E-03 4.230E-03 Average: 14 g 6.169E-03 4.246E-03

Polyester 1/16” Dry: 5.7 g 6.391E-03 4.424E-03 Damp: 9.7 g 6.371E-03 4.410E-03

Average: 7.7 g 6.381E-03 4.417E-03 a3”x3” swatch folded.

20

Figure 5. Model composed for measurements of cloth swatches: solid (left), wired (right).

21

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 (µCi )

Counting Time (s)

Detector 4802a Detector 4862 Cotton Polyester Cotton Polyester

300 4.019E-04 3.873E-04 5.887E-04 5.655E-04 600 2.584E-04 2.490E-04 4.068E-04 3.908E-04 1200 1.883E-04 1.814E-04 2.606E-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 pH Free Chlorine Content (mg/L)

Total Chlorine Content (mg/L)

Temperature Hot/Cold

(°C)

1 7.81 0.25 0.26 52/22

6 7.87 0.25 0.26 45/22

11 7.87 0.32 0.34 53/22

15 7.82 0.32 0.34 52/22

22

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

(%R):

DF (unitless) = Co/Cf

%R = (1- Cf/Co ) x 100%

where: Co = Counts of radiological activity on the material swatch before laundering (µCi ). Cf = Counts of radiological activity on the material swatch after laundering (µCi ).

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%).

23

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 Washed Swatches Decontamination

Factor Percent Removal

(%) Samplea Activity (µCi ) Load

Number Activity (µCi )

CC-1 1.89 ± 0.0844 10 0.0944 ± 0.00490 20.0 95.0% CC-2 1.97 ± 0.0864 12 0.113 ± 0.00547 17.4 94.3% CC-3 1.95 ± 0.0858 13 0.122 ± 0.00581 16.0 93.7% CC-4 1.95 ± 0.0866 14 0.106 ± 0.00508 18.4 94.6% CC-5 1.92 ± 0.0860 15 0.107 ± 0.00584 17.9 94.4% Average 17.9 94.4% HC-1 1.98 ± 0.0875 1 0.0476 ± 0.00306 41.6 97.6% HC-2 1.99 ± 0.0868 3 0.0915 ± 0.00509 21.7 95.4% HC-3 1.98 ± 0.0881 5 0.0789 ± 0.00840 25.1 96.0% HC-4 1.97 ± 0.0862 7 0.0889 ± 0.00486 22.2 95.5% HC-5 1.96 ± 0.0943 8 0.0939 ± 0.00480 20.9 95.2% Average 26.3 95.9% PC-1 1.94 ± 0.0867 17 0.0537 ± 0.00306 36.1 97.2% PC-2 1.93 ± 0.0841 18 0.0647 ± 0.00326 29.8 96.6% PC-3 1.97 ± 0.0866 19 0.0686 ± 0.00377 28.7 96.5% PC-4 1.94 ± 0.0841 20 0.0642 ± 0.00332 30.2 96.7% PC-5 1.94 ± 0.0858 21 0.0595 ± 0.00321 32.6 96.9% Average 31.5 96.8% ND-1 2.11 ± 0.0919 22 0.175 ± 0.00997 12.0 91.7% ND-2 2.05 ± 0.0893 23 0.158 ± 0.0105 12.9 92.3% ND-3 2.06 ± 0.0919 26 0.166 ± 0.00938 12.4 91.9% ND-4 2.05 ± 0.0897 27 0.1723 ± 0.00927 11.9 91.6% ND-5 2.07 ± 0.0921 28 0.1799 ± 0.0114 11.5 91.3% Average 12.2 91.8% RW-1 2.04 ± 0.0926 29 0.0686 ± 0.00401 29.7 96.6% RW-2 2.06 ± 0.0935 31 0.0655 ± 0.00442 31.4 96.8% RW-3 2.04 ± 0.0902 32 0.0567 ± 0.00374 36.0 97.2% RW-4 2.05 ± 0.0898 33 0.0679 ± 0.00417 30.2 96.7% RW-5 2.03 ± 0.0883 34 0.0731 ± 0.00442 27.8 96.4% Average 31.0 96.7% MC-1 2.08 ± 0.0943 35 0.088 ± 0.00426 23.7 95.8% MC-2 2.07 ± 0.0904 37 0.092 ± 0.00449 22.4 95.5% MC-3 2.11 ± 0.0913 38 0.097 ± 0.00556 21.7 95.4% MC-4 2.11 ± 0.0913 39 0.101 ± 0.00483 20.8 95.2% MC-5 2.09 ± 0.0932 40 0.086 ± 0.00424 24.3 95.9% Average 22.6 95.6% aCC = Cotton at cold/cold; HC = Cotton at hot/cold; PC = Polyester at cold/cold; ND = Cotton at

24

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 µCi after original loads under normal conditions (through Load 21), and 0.460 ± 0.029 µCi

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

<0.0025 µCi/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.

25

Table 12. Contamination in Wastewater

Material Laundering Conditions Activity

(pCi/mL) Total (µCi) Cotton Cold/Cold -1 84.0 ± 1.65 1.68 Cotton Cold/Cold-2 84.4 ± 1.64 1.69 Cotton Cold/Cold-3 84.4 ± 1.64 1.69 Cotton Cold/Cold-4 89.5 ± 1.72 1.79 Cotton Cold/Cold-5 88.2 ± 1.70 1.76 Cotton Hot/Cold-1 73.2 ± 1.50 1.76 Cotton Hot/Cold-2 84.2 ± 1.65 1.68 Cotton Hot/Cold-3 88.0 ± 1.70 1.76 Cotton Hot/Cold-4 85.8 ± 1.67 1.72 Cotton Hot/Cold-5 84.6 ± 1.65 1.69 Polyester Cold/Cold -1 86.4 ± 1.67 1.73 Polyester Cold/Cold-2 86.8 ± 1.68 1.74 Polyester Cold/Cold-3 93.0 ± 1.77 1.86 Polyester Cold/Cold-4 88.5 ± 1.70 1.77 Polyester Cold/Cold-5 91.2 ± 1.75 1.82 Cotton Cold/Cold; No Detergent-1 80.7 ± 1.45 1.61 Cotton Cold/Cold; No Detergent-2 75.9 ± 1.38 1.52 Cotton Cold/Cold; No Detergent-3 84.5 ± 1.50 1.69 Cotton Cold/Cold; No Detergent-4 83.1 ± 1.48 1.66 Cotton Cold/Cold; No Detergent-5 81.7 ± 1.46 1.63 Cotton Cold/Cold; Repeat Washing-1 83.8 ± 1.49 1.68 Cotton Cold/Cold; Repeat Washing-1A 4.56 ± 0.25 0.091 Cotton Cold/Cold; Repeat Washing-2 84.4 ± 1.50 1.69 Cotton Cold/Cold; Repeat Washing-2A 3.90 ± 0.229 0.077 Cotton Cold/Cold; Repeat Washing-3 83.7 ± 1.49 1.67 Cotton Cold/Cold; Repeat Washing-3A 3.35 ± 0.217 0.067 Cotton Cold/Cold; Repeat Washing-4 82.8 ± 1.48 1.66 Cotton Cold/Cold; Repeat Washing-4A 4.37 ± 0.244 0.087 Cotton Cold/Cold; Repeat Washing-5 85.8 ± 1.52 1.72 Cotton Cold/Cold; Repeat Washing-5A 4.78 ± 0.246 0.096 Cotton Cold/Cold; Multiple Clothing-1 29.3 ± 0.693 0.901 Cotton Cold/Cold; Multiple Clothing-2 28.7 ± 0.684 0.883 Cotton Cold/Cold; Multiple Clothing-3 35.4 ± 0.789 1.09 Cotton Cold/Cold; Multiple Clothing-4 29.7 ± 0.699 0.913 Cotton Cold/Cold; Multiple Clothing-5 30.2 ± 0.706 0.926

26

Table 13. Material Balance Calculation

Material – Laundering Conditionsa

Swatch Pre-

Laundering (µCi )

Swatch Post-

Laundering (µCi )

Wastewater (µCi )

Procedural Blank (µCi )

Washing Machine

(µCi )

Co-Laundered Clothing

(µCi )

Total Post-Laundering

(µCi ) Material Balance

Cotton – Cold/Cold 1.89 0.0944 1.68 0.0144 0.0046 NA 1.79 94.9% Cotton – Cold/Cold 1.97 0.113 1.69 0.0139 0.0046 NA 1.82 92.5% Cotton – Cold/Cold 1.95 0.122 1.69 0.0158 0.0046 NA 1.83 94.0% Cotton – Cold/Cold 1.95 0.106 1.79 0.0152 0.0046 NA 1.92 98.2% Cotton – Cold/Cold 1.92 0.107 1.76 0.0148 0.0046 NA 1.89 98.3%

Average 1.94 0.11 1.72 0.0148 0.0046 NA 1.85 95.6% Cotton – Hot/Cold 1.98 0.0476 1.76 0.0131 0.0046 NA 1.82 92.2% Cotton – Hot/Cold 1.99 0.0915 1.68 0.0149 0.0046 NA 1.79 90.0% Cotton – Hot/Cold 1.98 0.0789 1.76 0.0137 0.0046 NA 1.86 93.8% Cotton – Hot/Cold 1.97 0.0889 1.72 0.0146 0.0046 NA 1.83 92.8% Cotton – Hot/Cold 1.96 0.0939 1.69 0.0142 0.0046 NA 1.80 92.0%

Average 1.98 0.080 1.72 0.0141 0.0046 NA 1.82 92.2% Polyester – Cold/Cold 1.94 0.0537 1.73 0.000379 0.0046 NA 1.79 92.2% Polyester – Cold/Cold 1.93 0.0647 1.74 0.000715 0.0046 NA 1.81 93.8% Polyester – Cold/Cold 1.97 0.0686 1.86 0.000800 0.0046 NA 1.93 98.2% Polyester – Cold/Cold 1.94 0.0642 1.77 0.000644 0.0046 NA 1.84 94.8% Polyester – Cold/Cold 1.94 0.0595 1.82 0.000448 0.0046 NA 1.88 97.1%

Average 1.94 0.062 1.78 0.000597 0.00046 NA 1.85 95.2%

27

Table 13. Material Balance Calculation (Cont’d)

Material – Laundering Conditionsa

Swatch Pre-Laundering

(µCi )

Swatch Post-

Laundering (µCi )

Wastewater (µCi )

Procedural Blank (µCi )

Washing Machine

(µCi )

Co-Laundered Clothing

(µCi )

Total Post-Laundering

(µCi ) Material Balance

Cotton – Cold/Cold (ND) 2.11 0.175 1.61 0.0210 0.038 NA 1.85 87.7% Cotton – Cold/Cold (ND) 2.05 0.158 1.52 0.0212 0.038 NA 1.74 84.8% Cotton – Cold/Cold (ND) 2.06 0.166 1.69 0.0268 0.038 NA 1.92 93.2% Cotton – Cold/Cold (ND) 2.05 0.172 1.66 0.0266 0.038 NA 1.90 92.6% Cotton – Cold/Cold (ND) 2.07 0.180 1.63 0.0255 0.038 NA 1.88 90.9%

Average 2.07 0.17 1.62 0.0242 0.038 1.86 89.8%

Cotton – Cold/Cold (RW) 2.04 0.0686 1.77 0.00678 0.038 NA 1.88 92.3% Cotton – Cold/Cold (RW) 2.06 0.0655 1.77 0.00697 0.038 NA 1.88 91.3% Cotton – Cold/Cold (RW) 2.04 0.0567 1.74 0.00484 0.038 NA 1.84 90.2% Cotton – Cold/Cold (RW) 2.05 0.0679 1.74 0.00650 0.038 NA 1.85 90.4% Cotton – Cold/Cold (RW) 2.03 0.0731 1.81 0.00570 0.038 NA 1.93 94.9%

Average 2.04 0.07 1.77 0.0062 0.038 1.88 91.8%

Cotton – Cold/Cold (MC) 2.08 0.088 0.90 0.0000 0.038 0.662 1.69 81.0% Cotton – Cold/Cold (MC) 2.07 0.092 0.88 0.0000 0.038 0.693 1.71 82.5% Cotton – Cold/Cold (MC) 2.11 0.097 1.09 0.0000 0.038 0.456 1.68 79.6% Cotton – Cold/Cold (MC) 2.11 0.101 0.91 0.0000 0.038 0.557 1.61 76.4% Cotton – Cold/Cold (MC) 2.09 0.0860 0.93 0.0000 0.038 0.742 1.79 85.6%

Average 2.09 0.09 0.94 0.0000 0.038 0.622 1.70 81.0% aND = No detergent; RW = Swatch washed a second time; MC= Swatch washed with other clothing.

28

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 Wash/Rinse

Temperature Detergent

Other Laundering Conditions

Averagea Decontamination

Factor

Averagea Percent

Removal Cotton Cold/Cold Tide HE -- 17.9 94.4% Cotton Hot/Cold Tide HE -- 26.3 95.9%

Polyester Cold/Cold Tide HE -- 31.5 96.8% Cotton Cold/Cold None -- 12.2 91.8% Cotton Cold/Cold Tide HE Repeat washing 31.0 96.7% Cotton Cold/Cold Tide HE Multiple

clothing included in load with test swatch

22.6 95.6%

aAverage of five experiments.

Material balance evaluations indicate that the bulk (generally over 80%) of the 137Cs

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

29

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.

Office of Research and Development (8101R)Washington, DC 20460

Official BusinessPenalty for Private Use$300

PRESORTED STANDARDPOSTAGE & FEES PAID

EPAPERMIT NO. G-35