EPA/600/R-15/171 I September 2015 I www.epa.gov/research
United States
Environmental Protection
Agency
Impact of Stagnant Air Flow
Conditions on the Curing Times
of Strippable Coatings and
Gels as used for Radiological
Decontamination
Office of Research and Development
National Homeland Security Research Center
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EPA/600/R-15/171
September 2015
Impact of Stagnant Air Flow Conditions
on the Curing Times
of Strippable Coatings and Gels
as used for Radiological Decontamination
Evaluation Report
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 United States Environmental Protection Agency through its Office of Research and
Development's National Homeland Security Research Center, funded and managed the research
described here under EPA Contract Number EP-C-09-027, Work Assignments 4-11 and 5-11
with ARCADIS U.S., Inc. This report has been peer and administratively reviewed and has been
approved for publication as an Environmental Protection Agency report. It does not necessarily
reflect views of the Environmental Protection Agency. No official endorsement should be
inferred. The Environmental Protection Agency does not endorse the purchase or sale of any
commercial products or services.
Questions concerning this document or its application should be addressed to:
Lukas Oudejans, Ph.D.
Decontamination and Consequence Management Division
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency (MD-E343-06)
109 T.W. Alexander Dr.
Research Triangle Park, NC 27711
Phone: 919-541-2973
Fax: 919-541-0496
E-mail: Oudeians.Lukas@epa.gov
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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):
Peer Reviewers:
Terry Stilman, Region 4
Jim Mitchell, Region 5
Sang Don Lee, ORD, NHSRC
Quality Assurance Review:
Ramona Sherman, ORD/NHSRC
ARCADIS U.S., Inc.
This report builds on published EPA radiological decontamination reports and technical briefs in
which decontamination factors for a select number of decontamination technologies were
measured. The contributions to that work by John Drake (ORD/NHSRC, retired) are greatly
acknowledged.
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Table of Contents
Disclaimer iii
Acknowledgments iv
Table of Contents v
List of Figures vii
List of Tables ix
Acronyms and Abbreviations xi
Executive Summary xii
l.OIntroduction 1
1.1 .Purpose 1
1.2 .Project Objectives 2
2.0Experimental Approach 3
2.1 .Experimental Test Chamber 4
2.2.Environmental Controls 5
2.2.1 Temperature Control 7
2.2.2 RH Control 7
2.2.3 Pressure Control 8
2.2.4 Aeration Rate Control 8
2.2.5 Chemical Fume Hood for Decontaminant Preparation 9
2.3 .Test Materials 9
2.3.1 Coupon preparations 10
2.4.Selected Decontamination Technologies 11
2.4.1 InstaCote CC Wet/CC Strip 12
2.4.2 CBI DeconGel® 1108 13
2.4.3 Bartlett StripCoat TLC Free™ 14
2.4.4 EAI SuperGel 16
2.5 .Test Matrix 17
2.6 .Preparation of Coupons for Testing 18
2.7. Preparation and Application of the Decontamination Agents 19
2.7.1 Decontamination Coating Amounts 19
2.8.Procedure to Determine Curing Status 21
2.8.1 Strippable Coating Products 21
2.8.2 Non Strippable EAI SuperGel 21
2.9.Curing Status Definitions 22
2.9.1 Strippable Coating Products 22
2.9.2 Non Strippable Gel 22
3.0Test Results and Discussion 24
3.1.CC Wet/CC Strip 24
3.2.DeconGel® 1108 27
3.3 .Stripcoat TLC Free™ 30
3.4.EAI SuperGel 32
3.4.1 Stagnant Air Conditions 32
3.4.2 With Air Flow (1 ACH) Conditions 34
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4.0Quality Assurance and Quality Control 37
4.1 .Data Quality Objectives 37
4.2 .Data Quality Indicators 37
4.3 .Equipment Calibrations 38
4.4.Quantitative Acceptance Criteria 39
5.0Summary 42
6.0References 44
Appendix A: Loading Volumes of Strippable Coatings / Gels for No-Air-
Flow and High-Humidity-Post-Application Tests 46
Appendix B: Critical and Non-Critical Measurements 50
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List of Figures
Figure 2-1. Decontamination chamber 5
Figure 2-2. Decontamination chamber schematics 6
Figure 2-3. Concrete coupon molds (top left); with poured cement (top right); removal of molding
(bottom left); complete concrete coupons (bottom right) 11
Figure 2-4. Coupons assembled for testing 19
Figure 2-5. Scheme of the successive attempts to peel off decontamination coating from coupon surface.
21
Figure 2-6. Removal of EAI SuperGel from a stainless steel coupon 22
Figure 3-1. Appearance of the overly dried-out CC Wet/CC Strip coating (5 °C/20% RH/0 ACH, 4 h
post-application of CC Strip coat) 24
Figure 3-2. One-piece-removal of CC Wet/CC Strip coating from stainless steel (40 °C/20% RH/0 ACH;
4 h post-application of CC Strip™ coat) 25
Figure 3-3. One-piece-removal of CC Wet/CC Strip coating from concrete (20 °C/20% RH/0 ACH; 4 h
post-application of CC Strip coat) 25
Figure 3-4. One-piece-removal of DeconGel® 1108 coating from stainless steel (left) and concrete (right)
(5 °C/20% RH/0 ACH, 18 h post-application of 2nd coat) 27
Figure 3-5. Incomplete curing of DeconGel® 1108 coating from stainless steel (20 °C/80% RH/0 ACH, 4
h post-application of 2nd coat) 27
Figure 3-6. Complete curing of DeconGel® 1108 coating from stainless steel (40 °C/80% RH/0 ACH, 4 h
post-application of 2nd coat) 28
Figure 3-7. One-piece-removal of Stripcoat TLC Free™ coating from concrete (20 °C/20% RH/0 ACH,
4 h post-application of 2nd coat) 30
Figure 3-8. One-piece-removal of Stripcoat TLC Free™ coating from stainless steel (20 °C/20% RH/0
ACH, 4 h post-application of 2nd coat) 30
Figure 3-9. EAI SuperGel coating on concrete (left) and stainless steel (right) at 20 °C/20% RH/0 ACH,
1.5 h post-application of gel 32
Figure 3-10. EAI SuperGel coating on concrete (40 °C/20% RH/0 ACH, 1.5 h post-application of gel). 33
Figure 3-11. EAI SuperGel coating on stainless steel (5 °C/20% RH/1 ACH, 1.5 h post-application of
gel) 34
Figure 3-12. EAI SuperGel coating on concrete (5 °C/20% RH/1 ACH, 1.5 h post-application of gel)... 35
Figure 3-13. EAI SuperGel coating on concrete (20 °C/20% RH/1 ACH, 1.5 h post-application of gel). 35
Figure A-l. Loading volumes for CC Wet applications at different temperatures for no-air-flow and low
RH pre- to high RH post-application tests 47
Figure A-2. Loading volumes for CC Strip applications at different temperatures for no-air-flow and low
RH pre- to high RH post-application tests 47
Figure A-3. Loading volumes for DeconGel® 1108 applications at different temperatures for no-air-flow
and low RH pre- to high RH post-application tests 48
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Figure A-4. Loading volumes for StripCoat TLC applications at different temperatures for no-air-flow
and low RH pre- to high RH post-application tests 48
Figure A-5. Loading volumes for EAI SuperGel applications at different temperatures for no-air-flow and
low RH pre- to high RH post-application tests 49
Figure A-6. Loading volumes for SuperGel applications at different temperatures for 1 ACH air flow
tests 49
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List of Tables
Table ES-1. Summary of manufacturer information and observed shortest curing times for tested
strippable coatings under stagnant air conditions xiv
Table ES-2. Summary of observed changes in appearance of none coating forming gel xv
Table 2-1. Description of building materials for curing time testing 10
Table 2-2. Decontamination agents and technologies used for curing times testing 12
Table 2-3. Test matrix for each decontamination technology 17
Table 2-4. Average loading volumes per surface area for decontamination coatings tested 20
Table 3-1. Assessment of CC Wet/CC Strip curing times with opacity rating of coating under various
environmental conditions without ventilation (stagnant air) 26
Table 3-2. Assessment of DeconGel® 1108 curing times under various environmental conditions without
ventilation (stagnant air) 29
Table 3-3. Assessment of the Stripcoat TLC Free™ curing times under various environmental conditions
without ventilation (stagnant air) 31
Table 3-4. Assessment of the EAI SuperGel under various environmental conditions without air flow
(stagnant air, 0 ACH), 1.5 h following application 33
Table 3-5. Assessment of the EAI SuperGel under various environmental conditions under an airflow
equivalent to 1 ACH, 1.5 h following application 36
Table 4-1. DQIs for critical measurements 38
Table 4-2. Equipment calibration schedule 38
Table 4-3. Acceptance criteria for critical measurements 39
Table 4-4. Summary of critical measurements and completeness of data for stagnant air flow tests 40
Table 4-5. Summary of critical measurements and completeness of data for 1 ACH tests 41
Table B-l. Temperature prior and post-application of CC Wet/CC Strip for no-air-flow and high-
humidity-post-application tests 51
Table B-2. Relative humidity prior and post-application of CCWet/CC Strip for no-air-flow and high-
humidity-post-application tests 51
Table B-3. Other parameters for application of CC Wet/CC Strip for no-air-flow and high-humidity-post-
application tests 51
Table B-4. Curing time assessments for CC Wet/CC Strip for no-air-flow and high-humidity-post-
application tests 51
Table B-5. Temperature prior and post-application of DeconGel® 1108 for no-air-flow and high-
humidity-post-application tests 52
Table B-6. Relative humidity prior and post-application of DeconGel® 1108 for no-air-flow and high-
humidity-post-application tests 52
Table B-7. Other parameters for application of DeconGel® 1108 for no-air-flow and high-humidity-post-
application tests 52
Table B-8. Curing time assessments for DeconGel® 1108 no-air-flow and high-humidity-post-application
tests 52
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Table B-9. Temperature prior and post-application of StripCoat TLC for no-air-flow and high-humidity-
post-application tests 53
Table B-10. Relative humidity prior and post-application of StripCoat TLC for no-air-flow and high-
humidity-post-application tests 53
Table B-l 1. Other parameters for application of StripCoat TLC for no-air-flow and high-humidity-post-
application tests 53
Table B-12. Curing time assessments for StripCoat TLC for no-air-flow and high-humidity-post-
application tests 53
Table B-13. Temperature prior and post-application of SuperGel for no-air-flow and high-humidity-post-
application tests 54
Table B-14. Relative humidity prior and post-application of SuperGel for no-air-flow and high-humidity-
post-application tests 54
Table B-15. Other parameters for application of SuperGel for no-air-flow and high-humidity-post-
application tests 54
Table B-l6. Curing time assessments for SuperGel for no-air-flow and high-humidity-post-application
tests 54
Table B-17. Temperature prior and post-application of SuperGel with 1 ACH and low-humidity-post-
application tests 55
Table B-l8. Relative humidity prior and post-application of SuperGel with 1 ACH and low-humidity-
post-application tests 55
Table B-l9. Other parameters for application of SuperGel with 1 ACH and low-humidity-post-
application tests 55
Table B-20. Curing time assessments for SuperGel with 1 ACH and low-humidity-post-application tests.
55
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Acronyms and Abbreviations
ACH air change(s) per hour
DI deionized
DQI data quality indicator
DTRL Decontamination Technologies Research Laboratory
EPA U.S. Environmental Protection Agency
ft3 cubic feet or foot
h hour(s)
L liter(s)
min minute(s)
mL milliliter(s)
mm millimeter(s)
MSDS Material Safety Data Sheet
NHSRC National Homeland Security Research Center
NIST National Institute of Standards and Technology
ORD Office of Research and Development
OSC On-Scene Coordinator
PDAQ portable data acquisition (system)
PPE personal protective equipment
QA Quality Assurance
QAPP Quality Assurance Proj ect Plan
QC Quality Control
RDD Radiological Dispersal Device
RH Relative Humidity
SD Standard Deviation
sec second(s)
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Executive Summary
The U.S. Environmental Protection Agency's (EPA's) Office of Research and Development
(ORD) Homeland Security Program (HSRP) is helping to protect human health and the
environment from adverse impacts following an act of terrorism through evaluations of
homeland security related technologies. Decontamination technologies such as fumigants,
liquids, and removable coatings continue to be evaluated under this program for their abilities to
react or remove chemical, biological or radiological agents from materials encountered in the
urban environment. Performance testing of strippable coatings or gels designed to facilitate
radiological decontamination efforts have focused on measurement of their efficacies under
mostly research laboratory environmental conditions. Deviations from normal conditions in
temperature, relative humidity (RH), or air exchange have been shown to change the curing
times of coatings or gels to a level that curing may not occur within the manufacturer provided
timeframe. Such was observed during the 2010 Liberty RadEx exercise, an exercise that was
designed to test the country's capability to clean up and help communities recover from a
radiological dispersal device (RDD) detonation.
This project is a follow up to a previous National Homeland Security Research Center (NHSRC)
report (EPA 2014) which evaluated the impact of environmental conditions on the ability of
strippable coatings to cure properly on a representative building material in the urban
environment. That report described the impact of temperature and RH at a fixed (single) air
change per hour rate. Here, the air exchange was reduced to zero during curing of the strippable
coating or gel as to create a stagnant air flow condition.
Four decontamination products were selected based on their previously observed ability for
successful in situ removal of radionuclides from building materials (EPA 201 la, EPA 201 lb,
EPA 2013a, EPA 2013b). Three of these technologies were included in the testing described in
the initial study (EPA 2014), namely, InstaCote CC Wet/CC Strip, CBI Polymers DeconGel®
1108, and Bartlett Nuclear Inc. StripCoat TLC Free™. The fourth technology included in this
report is the EAI SuperGel as originally developed at Argonne National Laboratories. This gel
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was evaluated as a decontamination technology by EPA in EPA 201 lc, EPA 2013b, EPA 2013c,
and EPA 2013d.
Each of these technologies was applied to concrete and stainless steel coupons. The curing
process of these coatings was tested under various environmental conditions ranging from just
above the freezing point of the products (5 °C) to a summer-like temperature of 40 °C. The RH
was set as low (20% RH) prior to application of the coating or gel. Coupons were kept at such
conditions for 48-72 hours (h) to allow for equilibrium of the coupons with the set conditions.
Application of the water containing decontamination coatings or gels increases RH in the test
chamber, similar to what can be expected when a coating is applied in a relatively small,
enclosed, environment. Following application, RH was controlled to remain as high as observed
during the application of the water based coatings or gels, namely 80% RH or higher. This
condition was maintained under zero air flow conditions (stagnant air) and mimics an enclosed,
confined, area with no ventilation.
Up to four attempts were made to remove a strippable coating (InstaCote CC Wet/CC Strip, CBI
Polymers DeconGel® 1108, and Bartlett Nuclear Inc. StripCoat TLC Free™) from the surfaces,
namely 4 h, 18 h, 24 h, and 32 h after application of the product. No additional removal attempts
were made for application times beyond the observed (shortest) curing time. The EAI SuperGel
does not form a strippable coating. It stays as a gel on the surface and should be removed by e.g.,
wet vacuuming. The research effort described here did not assess the wet vacuum approach for
removal but instead assessed whether the appearance of the gel (e.g., viscosity or level of
hydration) was affected by the environmental conditions.
Table ES-1 summarizes the observed curing times for three coatings and gels that turn into
strippable coatings under all conditions tested. Curing was defined here as hardening of the
coating material on the stainless steel and concrete surfaces leading to removal/peeling of the
coating as one single piece ("Excellent") or several smaller pieces ("Good") without leaving
areas of uncured coating present on a coupon surface. Incomplete curing was defined when the
coating could only partially be removed due to the presence of wet spots or if the peeling process
resulted in numerous small dried out pieces of coating. No curing was defined when coatings
were wet and did not peel from the majority of the surfaces.
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It is assumed that complete removal of the coating or gel is highly critical to reach the highest
possible % removal of radionuclides from a surface. The peeling off in multiple pieces or as a
single piece should not have an impact on the overall % removal.
Table ES-1. Summary of manufacturer information and observed shortest curing times for tested
strippable coatings under stagnant air conditions.
CC Wet/CC Strip
DeconGel81108
Stripcoat TLC Free ™
Manufacturer recommended curing time
24 h at high RH, low
temp, no ventilation
hours for thin coatings to
overnight or longer for
thick coatings and high RH
4-10 h, depending on
coat thickness and RH
Environmental Conditions
(T/RH precond/RHcuring)
Observed curing times (h)/observations
5°C/20% RH/80% RH
4/multiple pieces3
18/one piece
4/one piece
20°C/20% RH/80% RH
4/one-several pieces'5
18/one piece
4/one piece
40°C/20% RH/80% RH
4/one piece
4/one piece
4/one piece
a Loss of elasticity of coating resulted in multiple small, brittle, pieces being removed; complete removal was
achieved.
b Coating on stainless steel coupon was brittle but came off; coating on concrete surface came off in one piece after
4 h.
The curing was found to be very rapid under warm (40 °C) temperatures when all coatings tested
were strippable at 4 h post-application. Coatings curing at medium (20 °C) and low (5 °C)
temperatures require longer curing times.
The observed curing of CC Wet/CC Strip occurred well within the 24 h post-application time
period recommended by the manufacturer for processing of this coating under worst case
environmental conditions (high humidity, low temperatures, no ventilation). Similarly,
DeconGel® 1108 curing times for all conditions tested are in line with the recommended 24 h
curing time by the manufacturer. As indicated by the manufacturer, drying times exceeding 24 h
may be required for decontamination scenarios where thicker coatings are applied in humid
environments. StripCoat TLC Free™ formed strippable coatings at 4 h post-applications under
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all environmental conditions tested. This is consistent with the manufacturer-recommended
curing times of 4-10 h.
Results for EAI SuperGel, as summarized in Table ES-2, indicate that dehydration of the gel
occurs at elevated temperatures and is more noticeable for concrete which presumably absorbs
some of the moisture of the gel. Dehydration appears to be orientation dependent with the
horizontal concrete coupon absorbing more moisture than the vertically positioned coupon. EAI
SuperGel was removable from the surface using a crude spackling knife approach as the
manufacturer's recommended wet vacuuming of the surface was beyond the scope of this
project. The presence of an additional air exchange resulted in additional dehydration of the gel.
Table ES-2. Summary of observed changes in appearance of none coating forming gel.
EAI SuperGel
Manufacturer recommended interaction time
1-2 ha
Environmental Conditions
(T/RHprecond/R Hcu ring)
Observed curing times (h)/observations
Stagnant Air
1 ACH air flow
5°C/20% RH/80% RH
WET /removable
Dehydrated / removable
20°C/20% RH/80% RH
WET - dehydrated / removable
Dehydrated / removable
40°C/20% RH/80% RH
Dehydrated / removable
Dehydrated / removable
ACH: air change per hour
a: Recommended interaction time to reach efficacy; not a curing time
Results from this study confirm that environmental conditions have an impact on the curing time
of two of the three tested strippable coatings. However, the occasionally observed prolonged
curing time was always less than the manufacturer's provided information. Curing times do
differ across products. The change in EAI SuperGel appearance is connected to changes in
environmental conditions. It is unknown whether these changes in appearance impact the
expected decontamination efficacy for this product.
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Loading volumes (hence, the thickness) of a coating material per surface test area were slightly
dependent on temperature. Temperature-related changes in loading volumes varied across
decontamination products. The impact of the coating thickness on the curing time was not
explicitly determined in this study. However, the impact of the coating thickness on the curing
time appears to be low as all coatings cured within the vendor- recommended curing times.
All strippable decontamination coatings tested were easy to apply, with no requirement for a pre-
preparation process. None of the products posed major challenges during the application using
the brush-on technique employed in this study.
Impact of the Study:
Based on the results obtained in this study, the lack of ventilation during the curing process of
the tested strippable coatings/gels do affect their curing time. However, the longer curing times
that were observed were within the specifications as provided by the manufacturers. The
peelability was assessed on stainless steel and concrete. Caution should be used in extrapolating
these bench test results to large scale field applications where, e.g., transitions across materials or
changes in shape may alter the ability to peel the coating from the surface, despite that the
coating has been cured.
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1.0 Introduction
As part of the 2010 Liberty RadEx exercise in Philadelphia, Pennsylvania, several
decontamination technologies were demonstrated in full scale for the removal of radionuclides
from building materials. This exercise was designed to test the country's capability to clean up
and help communities recover from a radiological dispersal device (RDD) detonation. One of
these demonstrations involved the application of a strippable coating to wall and floor surfaces of
the city's subway system. One of the observations made during Liberty RadEx was that the
coating did not cure properly over an extended period of time (more than 24 hour [h]) while the
curing time stated by the manufacturer was 4 - 6 h, depending on the environmental conditions.
The failure to cure was postulated to be due to the high relative humidity (RH) and the low
ventilation environment experienced during the demonstration in the enclosed area.
Strippable coatings or gels are examples of surface cleaning technologies that most likely would
be employed to decontaminate surfaces for which minimal destruction is desired. These would
include materials that are part of infrastructure of high economic, cultural, or historical
significance.
1.1 Purpose
The purpose of this work was to evaluate the impact that environmental conditions may have on
the ability of strippable coatings to cure properly on a representative building material in the
urban environment. This is a follow up study to a previous study (EPA 2014) where a single air
exchange per hour was present under various temperature and RH conditions. This study focused
on various environmental conditions under stagnant (zero air flow) conditions.
Curing of the strippable coating is critical to obtain high contaminant-removal efficiency as the
coating traps the targeted radionuclides. Only a successful removal of the coating may lead to
removal of the radionuclides; any (uncured) coating left on the surface would result in a lower
removal efficacy. Note that this work did not assess the impact that these environmental
conditions may have on the actual decontamination efficacy (i.e., removal of radionuclides from
a surface) of the technology. Efficacies against various radionuclides were determined previously
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(EPA 201 la) for these and other decontamination technologies at approximately 20 °C and 20%
RH.
1.2 Project Objectives
The specific project objectives to achieve the overall purpose consisted of:
• a systematical assessment of the curing process as a function of time through measurement of
the ability to peel the strippable coating from a surface under different environmental
conditions under stagnant flow conditions during the curing of the coating; and
• an assessment of whether the orientation of the surface (vertical versus horizontal) affects the
curing time.
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2.0 Experimental Approach
A modified glove box was used to establish a controlled temperature, RH, and air change
environment that would mimic a range of environmental conditions that may be encountered
during the remediation of an industrial or municipal setting. Building material coupons (concrete
and stainless steel) were allowed to equilibrate for a specified period of time within the
controlled environmental conditions of the modified glove box prior to application of the
strippable coating or gel under the set of conditions. The equilibration period of the materials
was at least 48 h long. A decontamination coating or gel was then applied according to the
manufacturer's instructions.
After application of the coating, the curing time was determined through measurement of the
ability to successfully process the coating as per the manufacturer's recommended procedure.
For these strippable decontamination products, the first attempt to peel a decontamination
coating was made 4 h post-application. If not successful, three additional attempts were made at
18, 24 and 32 h post-application. One decontamination product was a gel that would not change
its physical form but rather stayed on the surface as a gel. The manufacturer of this product
recommends physical removal of the gel through wet vacuuming of the surface. The
experimental limitations to vacuum a surface in the modified glove box led to a revised and more
qualitative assessment of the appearance of the gel rather than an assessment whether wet
vacuuming was deemed successful.
The time to cure the strippable decontamination coating on dry, clean surfaces of stainless steel
and concrete coupons was determined for three commercially available decontamination
technologies. This report summarizes results for tests performed under stagnant, zero air flow,
conditions during curing of the coating. An earlier report discusses tests conducted at one air
change per hour (ACH) of the same experimental chamber (EPA 2014). In that study, curing
times were measured under three temperatures associated with two controlled RH values,
namely, low (20%) RH or high (80%) RH, both maintained during the conditioning period of the
coupons and during the curing period of the strippable coating or gel after application.
Introduction of the water containing coating materials created significant spikes in RH,
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especially for the initial dry (20% RH) condition. Increases in RH when starting from 80% were
much less pronounced. Under the stagnant air flow conditions, changes in RH post application
would be even more noticeable for tests starting with low RH than for tests starting at high RH.
Therefore, the test matrix included only low (20%) RH conditions (at three different
temperatures) during the conditioning of the coupons. Following application of the coating / gel,
RH was kept above 80% during the curing period to reflect a stagnant air condition where RH is
not reduced by ventilation.
Each test point consisted of a set of three concrete coupons and one stainless steel coupon as a
smooth surface reference material. For each test set, application and drying/curing of the coating
or gel and the attempted removal of the coating was performed for two orientations of concrete
coupons (two concrete coupons in vertical and one concrete coupon in horizontal position). For
stainless steel reference coupons, curing time assessments were performed for the vertical
orientation only as what was anticipated to be the more challenging orientation for curing.
2.1 Experimental Test Chamber
A modified glove box was used as a test chamber to meet the environmental requirements of this
project. The decontamination chamber, shown in Figure 2-1, consisted of a modified glove box
with an internal volume of approximately 255 liters (L) (9.0 ft3). The exterior was insulated
using V2" TUFF-R, a rigid foil-clad polyisocyanurate board. Over an 8-h period, this chamber
was designed to be able to:
• Achieve RH values between 20-80% and maintain them within ±5% RH;
• Achieve temperatures between 5-40 °C and maintain them within ± 3 °C;
• Allow for the monitoring of RH and temperature conditions; and
• Allow for the coupons to be introduced and pulled out of the chamber through an airlock.
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Figure 2-1. Decontamination chamber.
2.2 Environmental Controls
The associated schematics of the chamber are shown in Figure 2-2.
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F©
AIM
PDAQ/LabView Control System
House air
¦u®
VARIABLE
TEMPERATURE
LIQUID RESERVOIR
(VTRL)
Legend:
Description
Symbol/Device
Insulated Line
Plumbing
Electrical Signal
Vaisala HMD53 Temperature/HumidityTransmitter
MT 101
Glove box Ambient Pressure Transmitter
PT 101
HF-HBA Gas Humidity Bottle
HC 101
Heated injection line Temperature Controller
TC 101
Meter Box Flow Controller/Meter
FC 101
Solenoid Valve for RH control
VI
Solenoid relief valve for Glove box Ambient Pressure
V2
Neslab RTE-100 recirculator
VTLR
Universal Analyzers Inc. Sample Cooler (M/N-1090PV)
Condenser Unit
Figure 2-2. Decontamination chamber schematics.
Temperature and RH in the decontamination chamber were measured using a Vaisala
HUMICAP® temperature and humidity sensor, model HMD53 (Vaisala, Inc.; Helsinki, Finland)
(MT 101 in Figure 2-2). The humidity sensor was factory preset to measure 0 to 90% (non-
condensing) RH. The temperature sensor was preset to measure from -20 to 60 °C. This Vaisala
sensor is used for control of temperature and RH inside the glove box. The temperature inside
the glove box was also monitored by a type K thermocouple (OMEGA Engineering, Inc.,
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Stamford, CT, USA) that would continuously sense temperatures from 0 to 1100 °C. Output
from the Vaisala RH/T sensor (MT-101 in Figure 2-2) and thermocouple were connected to an
IOTech data acquisition system (IOTech Inc.; Cleveland, OH, USA). Data from this IOTech
were collected by Lab VIEW software (National Instruments Co., Austin, TX, USA). This
software was programmed to control temperature, RH, and glove box pressure.
2.2.1 Temperature Control
A temperature controlled fluid was flowing through a radiator and returned to a Neslab RTE-100
recirculator (Neslab Instruments Inc., Portsmouth, NH, USA) which has both heating and
cooling capabilities that span the planned experimental temperature range of 5-40 °C. The
recirculator bath was controlled at a temperature from slightly above or below the target
temperature depending on the need to heat or cool the glove box to reach the desired conditions.
The temperature inside the recirculator bath was monitored by a type K thermocouple (Omega
Engineering, Inc., Stamford, CT, USA). The test chamber temperature was controlled by
thermocouple output-controlled fans blowing the glove box atmosphere through a small radiator
mounted inside the glove box. When the temperature was too cold (when heating the glove box)
or too hot (when cooling the glove box), fans on the radiator inside the glove box were activated
by the software using a relay device. The cooling/heating fluid was recirculated at all times
during conditioning.
2.2.2 RH Control
To assist with low (20%) RH conditions, air flow in the glove box was supplied by recirculating
the glove box air through a meter box (see Section 2.2.4). This meter box (FC 101 in Figure 2-2)
was pulling glove box air through a cylinder containing desiccant silica gel (Fisher Scientific,
Lane Fair Lawn, NJ, USA) and then Drierite™ (Hammond Drierite Co., Ltd.; Xenia, OH, USA)
to dry the glove box air (Figure 2-2) . This air flow was then pumped back into the glove box
after passing through a Peltier chiller (Model 1090PV, Universal Analyzer Inc., Carson City,
NV, USA). Recirculation was necessary to maintain cool and dry conditions. The recirculated air
bypasses the silica and Drierite™ when RH is below the set point to reduce the need to exchange
the media. A three-way solenoid valve (Norgren, Littleton, CO, USA) (VI in Figure 2-2)
7
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connected to a relay controls this bypass mechanism. Since water (vapor) is the main constituent
of the strippable coating that is released during the curing process while the humidity is
controlled, the term "air change" can be used to describe this setup despite the recirculating
process of the glove box air.
High (80%) RH control was accomplished through the use of a high-flow gas humidity bottle,
model HF-HBA with Nafion® tubing (Fuel Cell Technologies, Inc.; Albuquerque, NM, USA)
(HC 101 in Figure 2-2). This device is labeled HC-101 in Figure 2-2. The gas humidity bottle
consisted of a heated vessel containing a length of Nafion® tubing submersed in water. Water
vapor passes through the walls of the Nafion® tubing and is picked up by passing air, which
leaves the gas humidity bottle 90 to 100% saturated with water vapor.
2.2.3 Pressure Control
The static pressure of the glove box was controlled so that injection of the hot humid air did not
cause a positive pressure to build up in the chamber. This control was accomplished using a
differential pressure transducer (Model 265, Setra Systems, Boxborough, MA, USA) (PT-101 in
Figure 2-2) which compared the static pressure inside the glove box to ambient pressure in the
laboratory. When the differential pressures rose above 0.4 inches FhO, a solenoid connected
directly to the glove box atmosphere was opened by the Lab VIEW software, which allowed the
pressure to equilibrate.
2.2.4 Aeration Rate Control
The aeration rate of the glove box was controlled by an Apex Instruments, Inc. (Fuquay-Varina,
NC, USA) XC-40 meter console (FC 101 in Figure 2-2) during the conditioning of the coupons,
prior to application of the decontamination technology. This meter box (FC 101 in Figure 2-2)
was equipped with a precision dry gas meter with a mechanical or digital display (model AP25,
0.7/rev. with digital gas volume totalizer, with Quadrature Encoder, 8 digit LCD Display; 1 cc
resolution) and mechanical orifice flow meter with 50 mm Minihelic® Pressure Gauge (range 0-
2" [0-50 millimeter (mm)] H2O). After application of the decontamination technology, the
8
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metered box was turned off to create a stagnant, zero air change, environment during the curing
of the strippable coating or gel.
2.2.5 Chemical Fume Hood for Decontaminant Preparation
Decontamination agents were prepared in a regular chemical fume hood. Environmental
conditions such as temperature and RH were monitored but not controlled. Environmental
conditions in the chemical fume hood were measured using a temperature and RH data logger
(HOBO U12 T/RH Data Logger, Onset Computer Corporation, Bourne, MA, USA). The
humidity sensor was factory-preset to measure 5 to 95% RH while the temperature sensor was
preset to measure from -20 to 70 °C.
2.3 Test Materials
The representativeness and uniformity of test materials are essential in achieving defensible
evaluation results. Material representativeness means that the materials are typical of those
currently used in interiors and exteriors of buildings in terms of quality, surface characteristics,
and structural integrity. In this effort, representativeness was assured by selecting test materials
(i.e., concrete and stainless steel) that are typical of those found in industrial and municipal
settings. All materials used in this project met industry standards or specifications for indoor
and/or outdoor use and were obtained from national suppliers.
Material uniformity means that all these material coupons are equivalent for purposes related to
testing. Uniformity was maintained by obtaining and preparing a quantity of test material
sufficient to allow multiple test samples to be prepared with intentionally uniform characteristics
(e.g., test coupons were prepared from the same starting materials, using the same preparation
procedure, as per EPA's Decontamination Technologies Research Laboratory (DTRL) internal
operating procedure. The specifications of materials used for preparation of test coupons are
summarized in Table 2-1.
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Table 2-1. Description of building materials for curing time testing.
Material
Manufacturer/
Supplier Name
Material specifications
Coupon Surface Size
Lx WxH (inches)
Material Preparation
Stainless
Steel
McMaster-Carr
Multipurpose Stainless
Steel (48"X48") type
304, #2B mill
(unpolished, 0.036"
thick)
6x6x1/8
Remove any
lubricant/grease from
shearing with acetone and
wipe dry. Remove
particles and dust by
wiping clean with water
and wipe dry.
Concrete
Lowe's
hardware
store
Quikrete® Type 1 & II
Portland Cement;
Quikrete® All Purpose
Sand
6 x 6 x 1.5
Remove particles by
swiping with a soft nylon
brush and DI* water.
Allow to air dry on a
laboratory bench for at
least five days.
* Deionized
2.3.1 Coupon preparations
Heavy duty power hydraulic shears were used to cut the stainless steel coupons from larger
sheets to the correct length and width.
The concrete coupons were fabricated per internal operating procedure, using the commercially
available Quikrete® Type I & II Portland Cement, Quikrete® All Purpose Sand and DI water.
One batch of fifty (50) 6" x 6" coupons was created by mixing 67.9 lb Portland cement and
166.5 lb sand with 19.0 L of DI water. Each batch of concrete coupons was allowed to cure for at
least 30 days in a climate-controlled environment. Environmental conditions for the concrete
coupon storage area were measured using a temperature and RH data logger (HOBO U12 T/RH
Data Logger). The humidity sensor was factory-preset to measure 5 to 95% RH.
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Figure 2-3. Concrete coupon molds (top left); with poured concrete (top right); removal of
molding (bottom left); complete concrete coupons (bottom right).
Concrete coupons were labeled with a permanent marker on the side of each coupon. A pre-
printed label was also placed next to each coupon to aid in the identification of coupons and test
conditions on digital photographs.
2.4 Selected Decontamination Technologies
Specialty decontamination strippable coatings designed for decontamination of radionuclides
were used in this study. Decontamination agents are shown in Table 2-2. Four of the better
performing decontamination technologies for removal of radionuclides from concrete were
selected for this study. This selection was based on technology evaluations performed by EPA
through its National Homeland Security Research Center (NHSRC) (EPA 201 la, EPA 2011b,
EPA 2013a, EPA 2013b).
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2013/06/19
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A description of the technology and its active ingredients as provided by the manufacturer of
each formulation is summarized in Table 2-2. The mechanism of action and other relevant
information regarding each decontamination agent, including special instructions for storage,
handling, as well as the preparation and application instructions and information on
recommended curing times, are described in detail in Sections 2.4.1 through 2.4.3.
Table 2-2. Decontamination agents and technologies used for curing times testing.
Decon Agent
Manufacturer/Supplier Name
Technology
Active Ingredients
CC Wet/CC Strip
InstaCote, Inc.; Erie, Ml, USA
Contamination control
wetting agent/Strippable
coating applied onto
cured wetting agent
Water-Glycerin-non-ionic
surfactants (wetting
agent) and Vinyl-Acrylic-
Latex (coating)
DeconGel® 1108
CBI Polymers, Inc.; Honolulu,
HI, USA
Strippable coating
Proprietary
StripCoat TLC Free™
Bartlett Nuclear, Inc.;
Plymouth, MA, USA
Strippable coating
Vinyl-Acrylic-
Polyisobutylene-
Polyisoprene
EAI SuperGel
Environmental Alternatives,
Inc.; Keene, NH, USA
Super absorbing hydrogel
Anionic mixture of
polyacrylamide and
polyacrylate
2.4.1 InstaCote CC Wet/CC Strip
The InstaCote CC Wet/CC Strip product consists of two components. CC Wet is a water-based
wetting agent used to stabilize loose removable contamination on surfaces. This water-based
anti-dusting medium helps prevent airborne areas of contamination from occurring. The
application of wetting agent also aids capturing of contamination in crevices and pores. Here, CC
Wet was used as a pre-coat for the application of the stripcoat (CC Strip). CC Strip is a water-
based vinyl-acrylic-latex coating recommended for removal of loose radiological or other
hazardous contamination. CC Strip is typically applied over CC Wet. CC Strip re-hydrates the
CC Wet coating to encapsulate the contamination captured by the wetting agent. CC Strip is
applied as a liquid and cures to a clear, highly elastic coating which is removed by peeling.
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2.4.1.1 Curing information provided by manufacturer for CC Wet/CC Strip
The manufacturer recommends a 24-h curing time for CC Strip to ensure that the product is fully
cured under the worst case environmental conditions (high humidity, low temperatures, no
ventilation). Per the manufacturer, a good indicator of sufficient curing would be a change in the
opacity of the coating - a coating that is ready for removal will become opaque while uncured
coating is translucent.
2.4.1.2 Application information CC Wet/CC Strip
The CC Wet and the CC Strip formulations are sold as ready-to-use products and do not require
any special preparation prior to application. The CC Strip was mixed with a paint stick prior to
use. As per manufacturer recommendation, the CC Wet was allowed to cure for 24 h to account
for the potential for excessive moisture formation on horizontal surfaces. The manufacturer
recommends a spray-on or roll-on/brush-on technique for application of CC Wet and CC Strip
onto contaminated surfaces. In this study, CC Wet was sprayed on using a 240 milliliter (mL)
adjustable spray wash bottle with an adjustable sprayer and allowed to dry for 24 h prior to
application of the CC Strip. The CC Strip was applied to the test coupons using the "brush-on"
technique developed in other research efforts using strippable coating decontamination agents
(EPA 201 la). The application was performed using a standard two-inch (5.0 cm) paint brush.
This paint brush was loaded with wet CC Strip by dipping the brush into the container of the
ready-to-use well mixed CC Strip. The coating was applied evenly over the entire surface of the
coupon. The brush was then used to smooth the applied CC Strip on each test coupon.
2.4.2 CBI DeconGel® 1108
CBI Polymers DeconGel® 1108 is a one-component, water-based, broad application, peelable
decontamination hydrogel coating designed for safely removing radioactive contamination or as
a covering to contain contamination. DeconGel® 1108 is recommended for decontamination of
radioisotopes as well as particulates, heavy metals, and water-soluble and insoluble organic
compounds, including tritiated compounds. When dry, the product locks the contaminants into a
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polymer matrix. The film containing the encapsulated contamination can then be peeled and
disposed of according to appropriate local, state and federal regulations.
2.4.2.1 Curing information provided by manufacturer for DeconGel®1108
According to the manufacturer, the DeconGel® 1108 drying time increases with wet film
thickness and can vary. Drying time depends on a combination of the ambient humidity,
temperature, type of substrate and applied wet film thickness. Curing can take from as little as an
hour for thinner coatings in a dry environment with considerable air flow, to overnight or longer
if thicker coats are applied in humid environments (e.g., thicker coats on porous concrete).
Drying times exceeding 24 h may be required for good peel performance on bare concrete, wood
and other highly porous substrates when thick films are applied in humid environments.
2.4.2.2 Application information for DeconGel® 1108
The DeconGel® 1108 is sold as a ready-to-use "paint-like" formulation and does not require any
preparation prior to application. For each test, a fresh portion of approximately 200 mL of
DeconGel® 1108 was transferred from the primary container to a test-specific container that was
then moved to the glove box. Per the manufacturer's instructions, the DeconGel® 1108 may be
applied with a paint brush or trowel. For these tests, the DeconGel® 1108 was applied to the test
coupons using the "apply-dry-peel" technique developed in other research efforts (EPA 201 la,
EPA 201 lb). In this method, the application was performed using a standard two-inch paint
brush. The paint brush was loaded with the decon gel by dipping the brush into a plastic
container containing the DeconGel® 1108 coating. Wet coating was applied generously until the
entire surface of the coupon was covered. The paint brush was then used to work the first layer
of wet coating into the surfaces. After the first application, the DeconGel® 1108 was allowed to
dry for 2 h, and a second coat was added on top of the initial coating following the same method.
2.4.3 Bartlett StripCoat TLC Free™
As per Bartlett Nuclear's website (Bartlett 2010), the Stripcoat TLC Free™ is "a non-hazardous,
non-toxic, water based solution designed to safely remove and prevent the spread of
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contamination". "While curing, Stripcoat mechanically and chemically entraps contamination."
The dried coating containing the encapsulated contamination can then be peeled off the surface
and disposed. Stripcoat TLC Free™ can also serve as a barrier to prevent contamination from
attaching to a surface or as a covering to contain contamination. Stripcoat TLC Free™ should
not be exposed to direct sunlight for long periods. Sunlight can damage the coating, causing it to
lose its strippable qualities. Stripcoat TLC Free™ is not a submersible coating. However, some
short-term exposure of the cured coating to water should not adversely affect the coating's
qualities.
2.4.3.1 Curing information provided by manufacturer for Stripcoat TLC Free™
Per manufacturer's information, following the second application, the coating requires 4-10 h to
cure prior to removal. Curing times may depend on the coating thickness and humidity. Stripcoat
TLC Free™ can normally be removed after 4 h at normal room temperature. Thin applications
can cure in as little as one hour.
2.4.3.2 Application information Stripcoat for TLC Free™
The Stripcoat TLC Free™ is sold as a ready-to-use "paint-like" formulation and does not require
any preparation prior to application other than hand mixing prior to and during each use to
ensure homogeneity. Per manufacturer's instructions, the Stripcoat TLC Free™ may be applied
with industrial spray equipment (preferred method), paint rollers or brushes. In this study, the
Stripcoat TLC Free™ was applied to the test coupons using the "apply-allow to dry-reapply"
technique developed in other research efforts (EPA 201 la, EPA 2013a). The application was
performed using a standard two-inch paint brush. The paint brush was loaded with wet Stripcoat
TLC Free™ by dipping the brush into a container containing the ready-to-use, well mixed
Stripcoat TLC Free™. The first coating was applied until the entire surface of the coupon was
covered. The brush was then used to smooth the applied Stripcoat TLC Free™ on each test
coupon. The second coating was applied after 2 h with the thickness of the final coat estimated as
1-2.5 mm, with a visible pattern of brush strokes.
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2.4.4 EAI SuperGel
EAI SuperGel is a mixture of superabsorbent polymers containing solid sequestering agents
dissolved in a nonhazardous ionic wash solution. The resulting hydrogel is applied to a
contaminated surface and provides exchangeable ions to the substrate to promote desorption of
radioactive cesium and other radionuclides. The superabsorbent polymers consist of an anionic
mixture of polyacrylamide and polyacrylate in both linear and cross-linked form.
2.4.4.1 Curing information provided by manufacturer for EAI SuperGel
The hydrogel is allowed to react with the contaminated surface for at least 30-90 minutes to
maximize the ionic exchange of radionuclides and diffusion/absorption into the hydrogel. The
hydrogel is designed to adhere to vertical surfaces without slipping and maintain hydration in
direct sunlight for more than an hour.
2.4.4.2 Application information for EAI SuperGel
The solid sequestering agent is mixed into the dry polymer (10% by mass). The ionic wash
solution is composed of a single component salt at 1 mole/liter (L) concentration (no strong acid
or base is used). As per manufacturer's instructions, the reconstituted hydrogel (19-20 gram ionic
wash solution per gram of dry polymer mix) is applied by hand (e.g. brush) for small
applications or sprayed on for larger applications. In this study, due to the small size of the test
chamber, the EAI SuperGel was applied to the test coupons using a "brushing-and-smoothing"
technique recommended by manufacturer for small area applications and used in other research
efforts (EPA 201 lc). The application was performed using a standard two-inch paint brush. The
paint brush was loaded by dipping the brush in a plastic container with EAI SuperGel. Sufficient
SuperGel was applied to create a thick coating on the surface. A spackling knife was used to
smooth the SuperGel across the surface, until the entire surface of the coupon was covered.
Decontamination (residence) time for the SuperGel on horizontal and vertical surfaces was
specified by the manufacturer as 90 minutes.
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2.5 Test Matrix
The time required for the strippable decontamination coatings to cure on stainless steel and
concrete coupons was determined for three environmental conditions consisting of three
temperatures (selected within the 5-40 °C range) and one RH value (20%) during conditioning of
the materials followed by a transition to 80% RH following application of the decontamination
technology under stagnant, zero air exchange, conditions. Since all decontamination products
were water based, no efforts were made to include temperatures below their respective freezing
points. Manufacturer-provided freezing points ranged from 27-28 °F (-3 °C) for the CC Strip and
CC Wet products to 32 °F (0 °C) for Stripcoat TLC Free™. A freezing point for CBI DeconGel®
1108 of 0 °F [sic] was noticed in the material safety data sheet (MSDS) for this product. No
information was available for the freezing point of EAI SuperGel. Actual freezing points of the
decontamination products were not determined in this study.
The high temperature of 40 °C represents a frequently encountered mid-day high summer
temperature in the continental USA. Although higher temperatures can be observed, it is less
likely that a coating would be applied under such conditions considering the likely need to wear
personal protective equipment (PPE) for extended periods of time during the application of the
coating. The test matrix is shown in Table 2-3. A 9 ft3/h air flow (equivalent of 1 air change per
hour [ACH]) was established during the conditioning of coupons. After application of the
decontamination technology, the air flow was turned off resulting in stagnant air flow conditions
during the curing time period.
Table 2-3. Test matrix for each decontamination technology.
Temperature
[°C]
RH during
coupon
conditioning [%]
RH Post
application [%]
Concrete
vertical
Concrete
horizontal
Stainless steel
vertical
5
20
80
2
1
1
20
20
80
2
1
1
40
20
80
2
1
1
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For one technology, namely, EAI SuperGel, additional curing assessments were conducted in the
presence of an air flow equivalent to 1 ACH. This evaluation was intended to be part of the
initial curing tests (EPA 2014) but was executed incorrectly at that time and was repeated here
for the three temperatures shown in Table 2-3 and 20% RH, both pre- and post- application of
the technology.
Up to four attempts, as described in Section 2.8, were made per coupon to peel the
decontamination coating from the surface. A first attempt was made after 4 h followed by
attempts at 18 h, 24 h, and 32 h after application of the coating to the surface. If a peeling
attempt was successful from all four coupons after a specific time, the test for that coating at that
environmental condition was considered to be completed. The overnight drying of these coatings
was in general expected to be sufficient for complete curing based on previous research efforts
for concrete material coupons with temperatures between 19 and 21 °C and RH values between
20 and 22% (EPA 2011a).
2.6 Preparation of Coupons for Testing
Prior to the coating application, the surface of each coupon was examined for obvious cracks or
abnormalities and, if none were found, the coupon surfaces (both concrete and stainless steel)
were cleaned with a soft nylon brush and DI water and allowed to air dry on a laboratory bench
for at least five days. Labeled coupons were then moved to the test chamber/glove box that was
set at the specific set of temperature/RH/air change conditions.
After a conditioning period of at least 48 h (up to 72 h if the equilibration phase included a
weekend) at 20% RH to allow equilibration between the coupon material temperature and the
glove box temperature and RH, the decontamination coating was applied to the test coupons.
Figure 2-4 shows a set of concrete coupons assembled for testing.
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Figure 2-4. Coupons assembled for testing.
2.7 Preparation and Application of the Decontamination Agents
Decontamination products were prepared and applied per manufacturer's instructions, with
emphasis given to realistic application procedures that could be expanded to larger surface areas.
A fresh batch of coating/gel was used for each test. Immediately prior to testing, a small amount
of the coating/gel was prepared in a clean plastic container. The container was weighed and the
weight was recorded in the laboratory notebook. This preparatory work was performed in the
chemical fume hood to satisfy health and safety concerns related to working with the coating
(i.e., appropriate ventilation, respiratory protection). Environmental conditions in the chemical
fume hood were measured using a HOBO U12 T/RH data logger.
The ready-to-use batch of freshly prepared coating material was then transferred from the
chemical fume hood to the glove box using the modified airlock. The coating/gel was applied per
manufacturer's instructions inside the modified glove box under the specified T and RH
conditions maintained in the glove box. The sequence in which the coating/gel was applied to the
test coupons was recorded so that the sequence could be repeated in the coating removal
procedure at the end of the curing period.
2.7.1 Decontamination Coating Amounts
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The amount of coating used for each application was assessed gravimetrically by weighing the
test container with coating material before application and then immediately post-application of
the (double) coating to the entire test set of four (one stainless steel and three concrete) coupons.
The loading volume per surface area [liter (L)/m2] for each set was calculated based on the mass
[kg] and specific gravity [kg/L] of each coating applied onto the total test surface area of 4 x 36
square inches (= 144 square inches [0.0929 m2]). Loading volumes were adjusted for the amount
of coating that remained on the brush post application. The remaining amounts on the brush were
calculated from a series of gravimetric measurements of pre- and post-application weights of
brushes [kg] used for coating applications and the specific gravity of each coating.
Test-specific loading volumes for each coating varied across tests and are shown in Figures A-l
through A-5 in Appendix A and Table B-3, B-7, B-l 1, B-15, and B-19 of Appendix B. The
average loading volumes for each coating/gel are given in Table 2-4.
Table 2-4. Average loading volumes per surface area for decontamination coatings tested.
Decon Agent
Average loading volume per surface area3
[L/m2, ± SD]; n=number of measurements
CC Wet
0.37 ±0.05; n = 3
CC Strip
0.34 ±0.01; n = 3
DeconGel® 1108
1.08 ± 0.01; n = 3b
StripCoatTLC Free™
0.54 ± 0.03; n = 3b
EAI SuperGel
0.73 ±0.31; n = 3
a Loading volumes were adjusted for average amount of coating that remained on brush post-application.
b Double coating applied.
The application of these decontamination products by sprayer was not considered as part of this
study. Any potential differences in curing time between application by brush or sprayer due to
differences in the amount applied per surface area would require additional testing.
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2.8 Procedure to Determine Curing Status
2.8.1 Strippable Coating Products
The first attempt to peel off a coating from the coupon surface was made in the lower right
corner of each coupon (Corner 1 in Figure 2-5) at 4 h post-application. Prior to the first peeling
attempt, a slight surface cut at a 45 degree angle was performed with a utility knife to
start/facilitate the removal of the coating. The peel was started at this score line, moving towards
the center of the test coupon. If the first peel-off attempt was unsuccessful, the following
attempts to peel off the coating were performed starting with the upper right corner, then upper
left corner, then lower left corner of each coupon (corners 2, 3 and 4 in Figure 2-5). This curing
assessment process was conducted for all three strippable coatings.
Coupons were allowed to dry for 4 h before the first attempt to peel off the coating was made.
The second attempt (if needed) was performed after an overnight (18 h) curing. A third attempt
was scheduled at 24 h and, if needed, a fourth at 32 h post-application.
Figure 2-5. Scheme of the successive attempts to peel off decontamination coating from coupon
surface.
2.8.2 Non Strippable EAI SuperGel
The manufacturer recommended method of removal (by wet vacuum) was unpractical due to
small size of experimental chamber. EAI SuperGel assessments did not involve attempts to peel
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off the hydrogel as this product does not form a strippable coating. Instead, the SuperGel
appearance on coupons was assessed by the ability to remove the gel using a spackling knife
(Figure 2-5).
2.9.1 Strippable Coating Products
Based on the strippable coating/gel design, decontamination of a building material can be
expected to be successful only when a coating can be removed in its entirety from the surface as
the coating would capture the radionuclides. Efforts to remove incompletely cured coatings
would lead to lower decontamination factors. Four definitions of the curing status at a specific
time post application were identified as follows:
1. Excellent curing: Coating was successfully removed from the coupon in one piece,
2. Good curing: Coating was successfully removed from the coupon in several smaller
sections without leaving non-cured coating material on the surface,
3. Partial curing: Coating could only be removed partially as localized wet spots (not cured)
were present or the peeling process resulted in numerous small (dried out) pieces, and
4. No curing: Removal of coating was not possible due to the wet nature of the coating.
2.9.2 Non Strippable Gel
Figure 2-6. Removal of EAI SuperGel from a stainless steel coupon.
2.9 Curing Status Definitions
A qualitative assessment of the gel consistency was made as the ability to vacuum the gel of the
surface in the small glove box was impracticable. Gel consistency was defined as normal,
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granulated, or dehydrated. Also assessed was whether the gel adhered to vertical surfaces as
defined in terms of movement or slipping down a vertical surface. Although these criteria do not
establish whether the gel can be removed from a surface by wet vacuuming, they may be linked
to changes in radionuclide removal performance due to e.g., a shorter interaction time on a
vertical surface for lower viscosities or the lack of a gel like behavior.
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3.0 Test Results and Discussion
3.1 CC Wet/CC Strip
The CC Wet/CC Strip coating cured at 4 h post-application for all environmental conditions.
However, much more "brittle" coatings were observed for the 5 °C/20% RH test. At this lower
temperature, the coating appears to have lost its elasticity. Although cured, the coating can only
be removed as small, brittle, pieces. Complete removal is possible after a 4h curing time. Longer
curing times were not evaluated as the loss of elasticity would not have improved the ability to
remove the coating in one piece (or several large pieces) as observed for higher temperatures.
The application of a thicker coating at low temperature might have improved the ability to
remove the coating as one piece. This was not investigated further in this study.
Figure 3-1. Appearance of the overly dried-out CC Wet/CC Strip coating (5 °C/20% RH/0 ACH, 4
h post-application of CC Strip coat).
Figures 3-2 and 3-3 show examples of the CC Wet/CC Strip coating curing that could be
removed completely as one elastic piece from stainless steel and concrete, respectively.
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Figure 3-2. One-piece-removal of CC Wet/CC Strip coating from stainless steel (40 °C/20% RH/0
ACH; 4 h post-application of CC Strip™ coat).
Figure 3-3. One-piece-removal of CC Wet/CC Strip coating from concrete (20 °C/20% RH/0 ACH;
4 h post-application of CC Strip coat).
Table 3-1 summarizes the results of the CC Wet/CC Strip curing time assessment under all
environmental conditions tested for stagnant air conditions tests.
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Table 3-1. Assessment of CC Wet/CC Strip curing times with opacity rating of coating under
various environmental conditions without ventilation (stagnant air).
Test Conditions
[Temperature,
pre-, post-
application RH]
Assessments of
curing process
[h post-
application]
Stainless Steel
Vertical
Concrete
Vertical #1
Concrete
Vertical #2
Concrete
Horizontal #1
5 "C/20%/80%
4
SEMI-TRANSLUCENT
BRITTLE PIECES
SEMI-TRANSLUCENT
BRITTLE PIECES
SEMI-TRANSLUCENT
BRITTLE PIECES
SEMI-TRANSLUCENT
BRITTLE PIECES
18
24
32
20 "C/20%/80%
4
SEMI-TRANSLUCENT
BRITTLE PIECES
SEMI-TRANSLUCENT
ONE PIECE
SEMI-TRANSLUCENT
ONE PIECE
SEMI-TRANSLUCENT
ONE PIECE
18
24
32
40 "C/20%/80%
4
SEMI-TRANSLUCENT
ONE PIECE
SEMI-TRANSLUCENT
ONE PIECE
SEMI-TRANSLUCENT
ONE PIECE
SEMI-TRANSLUCENT
ONE PIECE
18
24
32
excellent curing/complete removal in one piece,
good curing/complete removal in several pieces,
partial curing/partial removal,
no curing/no removal possible.
A summary of the CC Wet/CC Strip loading volumes for the no- ventilation and high-humidity-
post-application tests is shown in Figure A-l and A-2 (Appendix A). All critical and non-critical
measurements taken for CC Wet/CC Strip tests are given in Appendix B (Table B1-B4).
Following the complete curing of this technology, the applied coating may deteriorate and loose
e.g., its elasticity making it more difficult to remove. This potential weathering of the coating
was not investigated as part of this study.
LEGEND:
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
26
-------
3.2 DeconGel® 1108
For most of the environmental conditions tested, the DeconGel® 1108 required at least overnight
processing and resulted in easily strippable one-piece coatings, as shown in Figure 3-4 for
stainless steel and concrete.
Figure 3-4. One-piece-removal of DeconGel® 1108 coating from stainless steel (left) and concrete
(right) (5 °C/20% RH/0 ACH, 18 h post-application of 2nd coat).
Strippable coatings could not be removed after 4 h except for the high temperature condition
which cured in 4 h. Figure 3-5 illustrates the wetness of the DeconGel® 1108 product after 4 h
curing at 20 °C while Figure 3-6 shows the cured gel after 4 h curing at 40 °C, both under
stagnant air flow conditions.
from stainless steel (20 °C/80% RH/0
Figure 3-5. Incomplete curing of DeconGel® 1108 coating
ACH, 4 h post-application of 2nd coat).
27
-------
Figure 3-6. Complete curing of DeconGel® 1108 coating
ACH, 4 h post-application of 2nd coat).
from stainless steel (40 °C/80% RII/0
The DeconGel®' 1108 cured at 18h for all stagnant air conditions in line with the manufacturer's
information that heat can reduce the drying times of the DeconGel® 1108, especially in humid
environments. Table 3-2 summarizes the results of the DeconGel 8' 1108 curing time assessments
under all environmental conditions tested under stagnant air flow (0 ACH). A summary of the
DeconGel® 1108 loading volumes for no- ventilation and high-humidity-post-application tests is
shown in Figure A-3 (Appendix A). All critical and non-critical measurements taken for
SuperGel tests are given in Appendix B (Table B5-B8). Following the complete curing of this
technology, the coating may deteriorate and loose its elasticity making it more difficult to
remove. This potential weathering was not investigated as part of this study.
28
-------
Table 3-2. Assessment of DeconGel® 1108 curing times under various environmental conditions
without ventilation (stagnant air).
Test Conditions
[Temperature,
pre-, post-
application RH]
Assessments of curing
process
[h post-application]
Stainless steel
vertical
Concrete
vertical #1
Concrete
vertical #2
Concrete
horizontal #1
5 "C/20%/80%
4
WET
WET
WET
WET
18
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
24
32
20 °C/20%/80%
4
WET
WET
WET
WET
18
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
24
32
40 oC/20%/80%
4
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
18
24
32
Excellent curing/complete removal one piece
Good curing/complete removal several pieces
Partial curing/partial removal
No curing/no removal possible
LEGEND:
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
29
-------
3.3 Stripcoat TLCFree™
Assessments of the curing process were performed 4 h post-application of the second coat. No
additional assessments were needed as Stripcoat TLC Free™ produced easily strippable coatings
under all environmental conditions tested under stagnant air flow conditions (0 ACH). Figures 3-
7 and 3-8 show removal of cured Stripcoat TLC Free™ from a concrete and a stainless steel
coupon, respectively.
Figure 3-7. One-piece-removal of Stripcoat TLC Free™ coating from concrete (20 °C/20% RH/0
ACH, 4 h post-application of 2nd coat).
Figure 3-8. One-piece-rem oval of Stripcoat TLC Free™ coating from stainless steel (20 °C/20%
RH/0 ACH, 4 h post-application of 2nd coat).
30
-------
Table 3-3 summarizes the results of the Stripcoat TLC Free™ curing time assessments under all
environmental conditions tested under stagnant (0 ACH) air flow conditions. A summary of the
Stripcoat TLC Free™ loading volumes for no-ventilation and high-humidity-post-application
tests is shown in Figure A-4 (Appendix A). All critical and non-critical measurements taken for
SuperGel tests are given in Appendix B (Table B9-B12). Following the complete curing of this
technology, the coating may deteriorate and loose its elasticity making it more difficult to
remove. This potential weathering of the coating was not investigated as part of this study.
Table 3-3. Assessment of the Stripcoat TLC Free™ curing times under various environmental
conditions without ventilation (stagnant air).
Test Conditions
[Temperature,
pre-, post-
application RH]
Assessments of curing
process
[h post-application]
Stainless steel
vertical
Concrete
vertical #1
Concrete
vertical #2
Concrete
horizontal #1
5 "C/20%/80%
4
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
18
24
32
20 "C/20%/80%
4
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
18
24
32
40 "C/20%/80%
4
ONE PIECE
ONE PIECE
ONE PIECE
ONE PIECE
18
24
32
Excellent curing/complete removal one piece
Good curing/complete removal several pieces
Partial curing/partial removal
No curing/no removal possible
LEGEND:
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
31
-------
3.4 EAI Super Gel
Assessments of the curing process were performed 1.5 h post-application of the gel. The
application to the test coupons using a "brushing and smoothing" technique resulted in relatively
smooth applications on concrete. A perfectly smooth application was not obtained for stainless
steel coupons in vertical orientation. The average coating thickness post-application was
estimated as 1-3 mm across the coupon surface.
3.4.1 Stagnant Air Conditions
Successful removal of EAI SuperGel from a concrete and a stainless steel coupon by spackling
knife is shown in Figure 3-9.
Figure 3-9. EAI SuperGel coating on concrete (left) and stainless steel (right) at 20 °C/20% RH/0
ACM, 1.5 h post-application of gel.
Evidence of a dehydrated gel was noticed at the higher 40 °C temperature as shown in Figure 3-10.
Although the gel can be removed, its consistency may have altered to a point where the ability to extract
radionuclides from the porous surface may have changed. This was not investigated as part of this study.
32
-------
Figure 3-10. EAI SuperGel coating on concrete (40 °C/20% RII/0 ACH, 1.5 h post-application of
gel).
Visual assessments of the EAI SuperGel under all environmental conditions tested under
stagnant (0 ACH) air flow conditions are summarized in Table 3-4. It should be noted that in
contrast to the other tested coatings discussed previously, the condition "WET" is a positive
indication of a gel that has not been affected by the environmental conditions.
Table 3-4. Assessment of the EAI SuperGel under various environmental conditions without air
flow (stagnant air, 0 ACH), 1.5 h
"ollowing application.
Test Conditions
[Temperature,
pre-, post-
application RH]
Stainless steel
vertical
Concrete
vertical #1
Concrete
vertical #2
Concrete
horizontal #1
5 oC/20%/80%
WET
WET
WET
WET
20 X/20%/80%
WET
WET
WET
REDUCED
HYDRATION/VOLUME
40 X/20%/80%
WET
REDUCED
HYDRATION/VOLUME
REDUCED
HYDRATION/VOLUME
DRY, REDUCED
HYDRATION/VOLUME
No change observed (well hydrated, no run-off)
Minor changes observed (minor changes in hydration and/or slipping of the hydrogel from
vertical surfaces)
Significant changes observed (significant changes in hydration/volume, partial run-off)
Very significant changes observed (complete run-off or disintegration of the hydrogel
structure and/or inability to remove)
A summary of the EAI SuperGel loading volumes for no- ventilation and high-humidity-post-
application tests is shown in Figure A-4 (Appendix A). All critical and non-critical
measurements taken for EAI SuperGel tests are given in Appendix B (Table B13-B16).
33
LEGEND;
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
-------
3.4.2 With Air Flow (1 ACH) Conditions
Additional assessments of the EAI SuperGel were conducted in the presence of an air flow
equivalent to 1 ACH. This evaluation was intended to be part of the initial curing tests (EPA
2014) but was executed incorrectly at that time and was repeated for relevant environmental
conditions. Coupons were conditioned at 20% RH. Following application of the SuperGel, RJ1
was forced to return to 20% under a 1 ACFI flow condition. However, at 1 ACH, this drying
process is relatively slow, especially considering that the assessment of the EAI SuperGel
occurred only 1.5 hr post application. As such, RH during curing was 40 to 60%, depending on
temperature.
The EAI SuperGel as removed from the vertical stainless steel coupon was well hydrated after
90 min post-application (Figure 3-11), independent on the tested temperatures.
Figure 3-11. EAI SuperGel coating on stainless steel (5 °C/20% RH/1 ACH, 1.5 h post-application
of gel).
A slightly dehydrated EAI SuperGel was described as "granulated" in Table 3-4. An example of
granulated gel is shown in Figure 3-12.
34
-------
Figure 3-12. EAI SuperGel coating on concrete (5 °C/20% RH/1 ACH, 1.5 h post-application of
gel).
The visual appearance of the hydrogel on porous concrete surfaces (both vertical and horizontal)
was indicative of an even further reduced hydration, especially for the normal and higher
temperatures (20° and 40°C) as illustrate in Figures 3-13 for a 20° temperature.
Figure 3-13. EAI SuperGel coating on concrete (20 °C/20% RH/1 ACH, 1.5 h post-application of
gel).
Figure A-5 (Appendix A) shows loading volumes of the EAI SuperGel as a function of
temperature. Visual assessments for the EAI SuperGel as tested under 1 ACH are summarized in
Table 3-5. For this product, the condition "WET" is a positive indication of a gel that has not
been affected by the environmental conditions.
35
-------
Table 3-5. Assessment of the EAI SuperGel under various environmental conditions under an
airflow equivalent to 1 ACH, 1.5 h following application.
Test Conditions
[Temperature,
pre-, post-
application RH]
Stainless steel
vertical
Concrete
vertical #1
Concrete
vertical #2
Concrete
horizontal #1
5 "C/20%/80%
WET
GRANULATED
GRANULATED
DRY, REDUCED
VOLUME
20 °C/20%/80%
WET
REDUCED
HYDRATION/VOLUME
REDUCED
HYDRATION/VOLUME
DRY, REDUCED
VOLUME
40 oC/20%/80%
WET
REDUCED
HYDRATION/VOLUME
REDUCED
HYDRATION/VOLUME
DRY, REDUCED
HYDRATION/VOLUME
No change observed (well hydrated, no run-off)
Minor changes observed (minor changes in hydration and/or slipping of the hydrogel from
vertical surfaces)
Significant changes observed (significant changes in hydration/volume, partial run-off)
Very significant changes observed (complete run-off or disintegration of the hydrogel
structure and/or inability to remove)
All critical and non-critical measurements taken for EAI SuperGel tests at 1 ACH are given in
Appendix B (Table B17-B20).
LEGEND:
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
36
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4.0 Quality Assurance and Quality Control
4.1 Data Quality Objectives
The objective of the experiments was to determine curing times for various strippable coatings
used for decontamination of radionuclides on a representative building material in the urban
environment under various environmental conditions (a combination of temperature, RH and air
change rate).
Critical measurements required to fulfill this objective included:
• RH and temperature measurements during the curing process of decontamination
coatings.
• Air change rate of the test chamber prior to application of the coating or gel. Air flow was
turned off after application to mimic stagnant air conditions.
• Time lapse between application and actual curing of decontamination coating (for up to
four coating removal attempts within 4 - 32 h post-application of the coating).
Non-critical measurements were:
• RH and temperature measurements during aging process of concrete coupons.
• Concrete coupon aging time (minimum of 30 days under normal laboratory conditions).
• RH and temperature in fume hood as used during preparation of decontamination
coatings.
4.2 Data Quality Indicators
Data quality indicators (DQIs) for the critical measurements used to determine if the collected
data met the quality assurance (QA) objectives are summarized in Table 4-1.
37
-------
Table 4-1. DQIs for critical measurements.
Measurement Parameter
Analysis Method
Accuracy
Precision/ Repeatability
Differential time
Stop watch
1 s
Is
RH
Vaisala probes
±3% RH*
2% RH
Temperature
Vaisala probes
±0.4 °C**
0.1 °C
Temperature
Thermocouple
±1.5 °C***
NA
Air Change Rate
Dry Gas Meter
1
15L/h (6% of 1 ACH)
* For 0-90% RH range; ** For 0-40 °C range; *** For 40-375 °C range; **** For range 0-2 inches Hg (0-50 mm H2O).
4.3 Equipment Calibrations
The equipment used to make the critical measurements was maintained and calibrated prior to
use. The method of calibration as well as the frequency of calibration is listed in Table 4-2.
Table 4-2. Equipment calibration schedule.
Equipment
Frequency
Stop watch
As specified by manufacturer in a Certificate of Calibration (NIST*
traceable re-certification)
Vaisala Probe (T, RH)
Yearly/biweekly checks**
Thermocouple
Yearly
HOBO U12T/RH data logger
Prior to aging of each batch of coupons
Meter Box
Yearly
* National Institute of Standards and Technology.
** Calibration checks every week according to internal operating procedures.
38
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4.4 Quantitative A cceptance Criteria
The quantitative acceptance criteria for each critical measurement as established in the Quality
Assurance Project Plan (QAPP) prior to the curing tests are shown in Table 4-3. The percent
completeness of the data set for each test is defined as the ratio of the number of data points
taken that pass the acceptance criteria for the critical measurements to the total number of data
points taken, multiplied by 100%.
Table 4-3. Acceptance criteria for critical measurements.
Measurement Parameter
Target Values
Precision
Completeness
%
Curing time/times of strippable
coatings
Time points
(4 h, 18 h, 24 h and 32 h)
± 5 min
100
Chamber Temperature
5, 20, 40 °C
±3 °C
90
Chamber RHa
20 and 80%
±5%
90
9 ft3/h during
Chamber aeration rateb
conditioning; no airflow
post application
±6%
90
a Target RH of 20% was maintained during conditioning of coupons, RH was maintained at 80% after application of
coating or gel by injections of water vapor from high-flow gas humidity bottle.
b Air flow measurements prior to application of decontamination coating; flow was turned off immediately after
application of coating.
Test specific results for all critical and non-critical measurements performed for the curing time
assessments under the stagnant air flow condition are given in Appendix B (Table B-l through
B-16). A summary is given in Table 4-4. All measurements were 100% complete with the
exception of one (out of twelve) average post application RH value and three (out of twelve)
chamber aeration rates during the conditioning of coupons prior to application of the
decontamination technology.
The post application RH did not reach 80% for the EAI SuperGel curing test at 40 °C. This is not
unexpected at it is more difficult to reach 80% RH within a short period of time at this elevated
temperature. The presence of a water based products facilitates the increase in humidity (from
20% to 80%) during application. However, this initial increase is limited by the available amount
39
-------
of water in the decontamination product. This single lower average RH value should not have
impacted the observed appearance of this product.
The aeration rates outside of the acceptance criteria of 9.0±0.54 ft3/h used to calculate
completeness, were only minimally (107-110%) outside of the target ventilation rate, and are not
expected to impact the length of decontamination coating curing times, nor to effect the usability
of the stagnant air tests.
Table 4-4. Summary of critical measurements and completeness of data for stagnant air flow tests
Measurement
Parameter
Target Values
Average measured
for individual
tests; n = number
of tests
Number of tests
below acceptance
criteria out of total
number of tests
Completeness
(%)
Curing
time/times of
strippable
coatings
Time point 1
(4 h post-application)
4 h 01 min 17 sec;
n = 12
0/12
100
Time point 2
(18 h post-application)
17 h 57 min 51 sec;
n = 2
0/2
100
Time point 3
(24 h post-application)
None3
N/A
N/A
Time point 4
(32 h post-application)
None3
N/A
N/A
Chamber
Temperature
5 °C
7.4 °C; n = 4
0/4
100
20 °C
21.7 °C; n = 4
0/4
100
40 °C
40.0 °C; n = 4
0/4
100
Chamber RH
Pre application 20% RH
20.6% RH; n = 12
0/12
100
Post application >80% RH
78.7% RH; n = 12
1/12
92
Chamber
aeration rateb
9 ft3/h
9.5; n = 12
3/12
75
N/A: Not Applicable
a None performed. No curing time assessments at 24 h or 32 h post application were needed
b Air flow measurements prior to application of the decontamination coating or gel
Test specific results for all critical and non-critical measurements performed for the curing time
assessments under 1 single ACH for EAI SuperGel are given in Appendix B (Table B-17
through B-20). A summary is given in Table 4-5. All measurements were 100% complete with
the exception of the post application RH values.
40
-------
The post application RH under the 1 ACH condition did reached 20% once for the EAI SuperGel
curing test at 20 °C. The average RH was approximately 60%. This is not unexpected at it is
difficult to reach 20% RH within 1.5 hr contact time of this gel considering the amount of water
that is available in the chamber (as part of the gel) post application. Although test criteria for RH
post application were not met at 1 ACH, the impact is minimal as this condition is closer to what
would happen in reality. The higher average RH values post application should have no impact
on the observed appearance of this product.
Table 4-5. Summary of critical measurements and completeness of data for 1 ACH tests
Measurement
Parameter
Target Values
Average measured
for individual
tests; n = number
of tests
Number of tests
below acceptance
criteria out of total
number of tests
Completeness
(%)
Curing
time/times of
strippable
coatings
Time point 1
(1.5 h post-application)
1 h 30 min 06 sec;
n = 3
0/3
100
Chamber
Temperature
5 °C
7.0 °C; n = 1
0/1
100
20 °C
22.6 °C; n = 1
0/1
100
40 °C
40.0 °C; n = 4
0/1
100
Chamber RH
Pre application 20% RH
20.1% RH; n = 3
0/3
100
Post application 20% RH
63.1% RH; n = 3
3/3
0
Chamber
9 ft3/h
9.4 ft3/h; n = 3
prior to application
0/3
100
aeration rate
9 ft3/h
9.2 ft3/h; n=3 post
application
0/3
100
41
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5.0 Summary
The decontamination products evaluated in this study are intended for large-area in situ removal
of a wide spectrum of radionuclides, even under challenging environmental conditions. All
strippable decontamination coatings tested (InstaCote CC Wet/CC Strip, CBI Polymers
DeconGel® 1108, Bartlett Nuclear StripCoat TLC Free™, and EAI SuperGel) were easy to
apply, with no requirement for pre-preparation processes. None of the products posed major
challenges during the application using the brush-on technique employed in this study. The
loading volumes per surface test area were, to some extent, dependent on temperature.
The curing process of these coatings was tested under various environmental conditions that all
had a stagnant, zero air flow, coating curing condition in common. The curing was very rapid
under warm (40 °C) temperatures conditions when all coatings tested were strippable at 4 h post-
application. Normal (20 °C) and low (5 °C) temperatures delayed curing beyond 4h for
DeconGel® 1108. No measurable differences in the curing times of these coatings were observed
when applied to vertical surfaces versus horizontal surfaces.
The removal of CC Wet/CC Strip coating from stainless steel at 5 °C and 20% RH was more
difficult due to the dried out nature and loss in elasticity of the coating after 4 h. This observation
may be somewhat biased by the generally low amount of the coating material that was applied
using the brush on procedure resulting in a thinner than recommended coating layer that would
be more difficult to remove. An application of a second layer of CC Strip may facilitate the
removal of the coating under these conditions.
For DeconGel® 1108, the observed overnight curing times or shorter are in line with the
recommended curing time by the manufacturer for decontamination scenarios where thicker
coatings are applied in humid environments when drying times exceeding 24 h may be required
for good peel performance.
42
-------
StripCoat TLC Free™, which has the shortest manufacturer-recommended curing times (4-10 h)
amongst all strippable coatings tested, formed strippable coatings at 4 h post-application under
all environmental conditions tested.
Results for EAI SuperGel indicate that dehydration of the gel occurs at elevated temperatures. It
is also more noticeable for concrete as some of the gel moisture gets absorbed by the porous
concrete. EAI SuperGel was removable from the surface by scraping the gel from a surface using
a spackling knife. The adherence to the surface did not change across the tested environmental
conditions suggesting that the recommended wet vacuum removal should be successful under all
tested conditions.
The information presented in this report should help EPA responders or On-Scene Coordinators
(OSCs) in the field in identifying conditions under which strippable coatings or gels may not
cure as fast as one may expect or may change their appearance based on curing times at normal
room temperature conditions. The identification of more challenging conditions, including
stagnant air conditions, that lead to longer curing times as stated by the manufacturers of these
products are consistent with the observations in this report under the tested environmental
conditions.
This study did not address whether a coating or gel may weather with time resulting in e.g., a
loss of elasticity and with that a more difficult or incomplete removal. Such weathering may put
a time limit on how long a strippable coating should stay on a surface before removal. This was
not investigated in this study.
43
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6.0 References
Bartlett (2010). Stripcoat TLC Free™ product information,
http://www.bartlettnuclear.com/producs-technologv-contamination-control-coatings-stripcoat-
tic.htm. Last accessed June 2014.
EPA 201 la. Evaluation of Nine Chemical-Based Technologies for Removal of
Radiological Contamination from Concrete Surfaces. EPA Technical Brief. Cincinnati, OH,
USA. National Homeland Security Research Center Office of Research and Development, U.S.
Environmental Protection Agency.
EPA 201 lb. CBI Polymers DeconGel® 1101 and 1108 for Radiological Decontamination.
Technology Evaluation. Cincinnati, OH, USA, EPA Report 600/R-l 1/084. National Homeland
Security Research Center Office of Research and Development, U.S. Environmental Protection
Agency.
EPA 2011c. Argonne National Lab oratory Argonne SuperGel forRadiological Decontamination.
Technical Evaluation. Cincinnati, OH, USA, EPA Report 600/R-l 1/081. National Homeland
Security Research Center Office of Research and Development, U.S. Environmental Protection
Agency.
EPA 2013a. Bartlett Services, Inc. Stripcoat TLC Free™ Radiological Decontamination of
Americium. Technology Evaluation. Cincinnati, OH, USA. EPA Report 600/R-13/005. National
Homeland Security Research Center Office of Research and Development, U.S. Environmental
Protection Agency.
EPA 2013b. Decontamination of Cesium, Cobalt, Strontium, and Americium from Porous
Surfaces. Technology Evaluation. Cincinnati, OH, USA, EPA Report 600/R-13/232. National
Homeland Security Research Center Office of Research and Development, U.S. Environmental
Protection Agency.
44
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EPA 2013c. Decontamination of Concrete with Aged and Recent Cesium Contamination.
Technology Evaluation. Cincinnati, OH, USA, EPA Report 600/R-13/001. National Homeland
Security Research Center Office of Research and Development, U.S. Environmental Protection
Agency.
EPA 2013d. Decontamination of Concrete and Granite Contaminated with Cobalt-60 and
Strontium-85. Technology Evaluation. Cincinnati, OH, USA, EPA Report 600/R-13/002.
National Homeland Security Research Center Office of Research and Development, U.S.
Environmental Protection Agency.
EPA 2014. Evaluation of the Curing Times of Strippable Coatings and Gels as used for
Radiological Decontamination. Technology Evaluation. Research Triangel Park, NC, USA, EPA
Report 600/R-14/238. National Homeland Security Research Center Office of Research and
Development, U.S. Environmental Protection Agency.
45
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Appendix A: Loading Volumes of Strippable Coatings / Gels for No-Air-Flow
and High-Humidity-Post-Application Tests
46
-------
CC Wet loading volumes
"
-
10 15 20 25 30 35 40 45
T[°C]
~ 20%/80% RH dry surface tests
Figure A-l. Loading volumes for CC Wet applications at different temperatures for no-air-flow
and low RH pre- to high RH post-application tests.
CC Strip loading volumes
3
_£
S
%
15
30
20 25
T I'C]
¦ 20%/80% RH dry surface tests
Figure A-2. Loading volumes for CC Strip applications at different temperatures for no-air-flow
and low RH pre- to high RH post-application tests.
47
-------
DeconGel DG1108 loading volumes
E
-o 70-0
$
15
30
20 25
T [*C]
> 20%/80% RH dry surface tests
Figure A-3. Loading volumes for DeconGel® 1108 applications at different temperatures for no-air-
flow and low RH pre- to high RH post-application tests.
StripCoat TLC loading volumes
S 18
—I
£
c
•2 16
10 15 20 25 30 35 40 45
T [°C]
~ 20%/80% RH dry surface tests
Figure A-4. Loading volumes for StripCoat TLC applications at different temperatures for no-air-
flow and low RH pre- to high RH post-application tests.
48
-------
SuperGel loading volumes
30 .0 -
25.0 •••-*-
1
3
^J.20.0
f
g
? 1S0
0.0
0 5 10 IS 20 25 30 35 40 45
Tpq
~ 2096/80% RH tests dry surface
Figure A-5. Loading volumes for EAI SuperGel applications at different temperatures for no-air-
flow and low RH pre- to high RH post-application tests.
SuperGel loading volumes
1~
:
:
:
:
C-
:
**
3
i
0 5 10 15 20 25 30 35 40 45
T[°C]
X20% RH dry tests dry surface
Figure A-6. Loading volumes for SuperGel applications at different temperatures for 1 ACH air
flow tests.
49
-------
Appendix B: Critical and Non-Critical Measurements
50
-------
Table B-l. Temperature prior and post-app
ication of CC Wet/CC Strip for no-air-flow and high-humidity-post-application tests
Test
Temperature [°C] measured during equilibration/pre-application
Temperature [°C] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
7.6±0.01
7.6-8.1
100%
7.6±0.05
7.6-8.3
20°C/20%/80% RH test/no-air-flow
20.8±0.12
20.6-21.1
100%
21,4± 0.08
21.2-21.7
40°C/20%/80% RH test/no-air-flow
40.0±0.03
39.9-40.1
100%
40.0 ± 0.05
39.5-40.2
Table B-2. Relative humidity prior and post-application of CCWet/CC Strip for no-air-flow and high-
lumidity-post-application tests.
Test
RH [%] measured during equilibration/pre-application
RH [%] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
20.3±0.27
19.6-27.8
100%
80.0± 1.1
78.9-87.0
20°C/20%/80% RH test/no-air-flow
20.1 ±0.20
19.8-37.2
100%
79.6± 1.2
72.4-83.1
40°C/20%/80% RH test/no-air-flow
19.3±0.61
19.0-25.7
99.6%
78.4±2.8
40.2-79.4
able B-3. Other parameters for application of CC Wet/CC Strip for no-air-
low and high-humidity-post-ap
plication tests.
Test
Air flow during equilibration/post-
application
[ft3 per hour/% of target ventilation
rate]
Average
amount
of CC Wet
used for
application
[mLs/coupon]
Average application
rate of CC Wet
[sec per coupon, +/-
SD
Average amount
of CC Strip used
for application
[mLs/coupon
Average application
rate of CC Strip
[sec per coupon, +/-
SD]
Final coating
thickness [mm]
5°C/20%/80% RH test/no-air-flow
9.4/no flow
105%/not applicable
7.6
0:00:12
00:01
10
00:34
00:02
0.9-1
20°C/20%/80% RH test/no-air-flow
9.0/no flow
100%/not applicable
10.0
0:00:13
00:02
10
00:45
00:02
0.9-1
40°C/20%/80% RH test/no-air-flow
9.9/no flow
110%/not applicable
8.4
0:00:22
00:06
9.8
00:41
00:05
0.9-1
Table B-4. Curing time assessments for CC Wet/CC Strip for no-air-flow and high-humidity-post-application tests.
Test
Average curing time,
1st attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
2nd attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
3rd attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
4th attempt to peel-off
[h:min:sec post-application, +/- SD]
5°C/20%/80% RH test/no-air-flow
4:01:41
0:00:28
20°C/20%/80% RH test/no-air-flow
4:00:09
0:00:03
40°C/20%/80% RH test/no-air-flow
4:00:42
0:00:37
51
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Table B-5. Temperature prior and post-application of DeconGel® 1108 for no-air-flow and high-humidity-post-application tests.
Test
Temperature [°C] measured during equilibration/pre-application
Temperature [°C] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
7.51 ±0.26
6.92-7.82
100%
7.8±0.02
7.7-7.9
20°C/20%/80% RH test/no-air-flow
22.1 ±0.04
21.9-22.1
100%
22.2±0.3
22.1-22.3
40°C/20%/80% RH test/no-air-flow
40.0±0.08
39.9-42.3
100%
40.0±0.4
39.8-40.1
Table B-6. Relative humidity prior and post-application of DeconGel® 1108 for no-air-flow and high-humidity-post-application tests.
Test
RH [%] measured during equilibration/pre-application
RH [%] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
23.9±0.99
22.0-27.8
95.1%
79.4±2.3
76.0-89.9
20°C/20%/80% RH test/no-air-flow
20.1 ±0.16
19.8-20.4
100%
88.0±0.7
85.1-88.8
40°C/20%/80% RH test/no-air-flow
18.4±0.84
16.4-21.7
100%
78.8±2.7
72.7-83.1
Table B-7. Other parameters for application of DeconGel'8' 1108 for no-air-flow and high-humidity-post-application tests.
Test
Air flow during equilibration/post-application
[ft3 per hour/% of target ventilation rate]
Average
amount
of coating
used for 1st
application
[mLs/coupon]
Average
amount
of coating
used for 2nd
application
[mLs/coupon
Average application rate
[sec per coupon, +/- SD]
Final coating thickness
[mm]
5°C/20%/80% RH test/no-air-flow
9.2/no-flow
103%/not applicable
13.2
12.7
0:00:58
0:00:04
1.1-1.4
20°C/20%/80% RH test/no-air-flow
9.4/no-flow
105%/not applicable
13.2
12.7
0:00:58
0:00:04
1.1-1.4
40°C/20%/80% RH test/no-air-flow
9.3/no-flow
104%/not applicable
12.7
13.4
0:00:55
0:00:02
1.1-1.4
Table B-8. Curing time assessments for DeconGel® 1108 no-air-flow and high-humidity-post-application tests.
Test
Average curing time,
1st attempt to peel-off
[h:min:sec post-application, +/-
SD]
Average curing time,
2nd attempt to peel-off
[h:min:sec post-application, +/-
SD]
Average curing time,
3rd attempt to peel-off
[h:min:sec post-application, +/-
SD]
Average curing time,
4th attempt to peel-off
[h:min:sec post-application, +/-
SD]
5°C/20%/80% RH test/no-air-flow
3:59:12
0:00:46
18:00:34
0:00:12
20°C/20%/80% RH test/no-air-flow
4:03:39
0:05:20
17:55:08
0:03:01
40°C/20%/80% RH test/no-air-flow
3:59:11
0:00:10
52
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Table B-9. Temperature prior and post-application of StripCoat TLC for no-air-flow and high-humidity-post-application tests.
Test
Temperature [°C] measured during equilibration/pre-application
Temperature [°C] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
7.5±0.14
7.4-10.5
99.4%
7.5±0.03
7.4-7.6
20°C/20%/80% RH test/no-air-flow
21.4±0.07
21.8-22.2
100.0%
22.3±0.06
22.2-22.7
40°C/20%/80% RH test/no-air-flow
40.0±0.37
31.7-40.2
99.6%
40.0±0.04
39.8-40.2
Table B-10. Relative humidity prior and post-application of StripCoat TLC for no-air-flow and high-humidity-post-application tests.
Test
RH [%] measured during equilibration/pre-application
RH [%] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
20.3±1.2
19.8-30.3
98.1%
78.9±3.7
38.2-87.2
20°C/20%/80% RH test/no-air-flow
20.1 ±0.19
19.0-25.3
99.9%
83.0±6.3
26.6-88.2
40°C/20%/80% RH test/no-air-flow
18.8±2.5
15.7-36.6
97.2%
78.0±9.2
19.9-82.8
Table B-ll. Other parameters for application of StripCoat TLC for no-air-flow and high-humidity-post-application tests.
Test
Air flow during equilibration/post-
application
[ft3 per hour/% of target ventilation rate]
Average amount
of coating used for 1st
application
[mLs/coupon]
Average amount
of coating used
for 2nd application
[mLs/coupon
Average application rate
[sec per coupon, +/- SD]
Final coating
thickness
[mm]
5°C/20%/80% RH test/no-air-flow
9.5/no-flow
106%/not applicable
7.8
7.6
00:20
00:03
0.8-1.1
20°C/20%/80% RH test/no-air-flow
9.9/no-flow
110%/not applicable
7.4
7.4
00:22
00:03
0.8-1.1
40°C/20%/80% RH test/no-air-flow
9.5/no-flow
106%/not applicable
6.9
7.1
00:20
00:04
0.8-1.1
Table B-12. Curing time assessments for StripCoat TLC for no-air-flow and high-humidity-post-application tests.
Test
Average curing time,
1st attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
2nd attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
3rd attempt to peel-off
[h:min:sec post-application, +/- SD]
Average curing time,
4th attempt to peel-off
[h:min:sec post-application,
+/- SD]
5°C/20%/80% RH test/no-air-flow
4:01:00
0:00:43
^
20°C/20%/80% RH test/no-air-flow
4:01:36
0:02:34
^
40°C/20%/80% RH test/no-air-flow
4:04:24
0:00:42
^
53
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Table B-13. Temperature prior and post-application of SuperGel for no-air-flow and high-humidity-post-application tests.
Test
Temperature [°C] measured during equilibration/pre-application
Temperature [°C] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
7.0±0.03
6.8-7.0
100%
7.0±0.03
6.9-7.1
20°C/20%/80% RH test/no-air-flow
22.6±0.04
22.5-22.8
100%
22.7±0.14
22.5-23.1
40°C/20%/80% RH test/no-air-flow
40.0±0.04
39.9-40.2
100%
40.0±0.03
39-8-40.1
Table B-14. Relative humidity prior and post-application of SuperGel for no-air-flow and high-humidity-post-application tests.
Test
RH [%] measured during equilibration/pre-application
RH [%] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/80% RH test/no-air-flow
21.3±1.5
19.8-24.6
100.0%
76.7±10.5
32.2-87.3
20°C/20%/80% RH test/no-air-flow
20.2±0.39
19.8-23.6
100.0%
78.0±11.7
24.7-85.0
40°C/20%/80% RH test/no-air-flow
18.2±0.48
17.0-19.7
100%
66.0±8.8
21.7-70.8
Table B-15. Other parameters for application of SuperGel for no-air-
Test
Air flow during equilibration/post-application
[ft3 per hour/% of target ventilation rate]
Average amount
of coating used for
application
[mL/coupon]
Average application rate
[h:min:sec per coupon, +/- SD]
Final coating
thickness [mm]
5°C/20%/80% RH test/no-air-flow
9.6/no-flow
107%/ not applicable
25.2
0:00:19
0:00:03
0.5-1.1
20°C/20%/80% RH test/no-air-flow
9.4/no-flow
104%/ not applicable
12.7
0:00:31
0:00:07
0.5-1.1
40°C/20%/80% RH test/no-air-flow
8.6/no-flow
95%/ not applicable
13.0
0:00:23
0:00:03
0.5-1.1
low and high-humidity-post-application tests.
Table B-16. Curing time assessments for SuperGel for no-air-flow and high-humidity-post-application tests
Test
Assessment of curing time
[h:min:sec post-application, +/- SD]
5°C/20%/80% RH test/no-air-flow
1:30:14
0:00:08
20°C/20%/80% RH test/no-air-flow
1:30:51
0:00:03
40°C/20%/80% RH test/no-air-flow
1:30:12
0:00:08
54
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Table B-17. Temperature prior and post-application of SuperGel with 1 ACH and low-humidity-post-application tests.
Test
Temperature [°C] measured during equilibration/pre-application
Temperature [°C] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/20% RH test/1 ACH air-flow
7.0±0.03
6.8-7.1
100%
7.0±0.02
6.9-7.0
20°C/20%/20% RH test/1 ACH air-flow
22.6±0.04
22.5-22.8
100%
22.8±0.11
22.6-23.0
40°C/20%/20% RH test/1 ACH air-flow
40.0±0.04
39.9-40.2
100%
40.0±0.03
39-9-40.1
Table B-18. Relative humidity prior and post-application of SuperGel with 1 ACH and low-humidity-post-application tests.
Test
RH [%] measured during equilibration/pre-application
RH [%] measured post-application
Mean ± SD
Range
% completeness
Mean ± SD
Range
5°C/20%/20% RH test/1 ACH air-flow
21.8±1.8
19.8-29.3
99.9%
61.4±4.1
40.8-70.3
20°C/20%/20% RH test/1 ACH air-flow
20.2±0.39
19.8-23.4
100.0%
63.5±10.0
21.3-70.6
40°C/20%/20% RH test/1 ACH air-flow
18.2±0.4
17.0-23.5
100%
64.4±6.9
24.8-69.3
Table B-19. Other parameters for application of SuperGel with 1 ACH and low-humidity-post-application tests.
Test
Air flow during equilibration/post-application
[ft3 per hour/% of target ventilation rate]
Average amount
of coating used for
application
[mL/coupon]
Average application rate
[h:min:sec per coupon, +/- SD]
Final coating
thickness [mm]
5°C/20%/20% RH test/1 ACH air-flow
9.7/9.6
107%/106%
25.2
0:00:23
0:00:02
0.5-1.1
20°C/20%/20% RH test/1 ACH air-flow
9.4/9.4
104%/104%
13.5
0:00:25
0:00:06
0.5-1.1
40°C/20%/20% RH test/1 ACH air-flow
9.1/8.6
101 %/96%
13.2
0:00:22
0:00:03
0.5-1.1
Table B-20. Curing time assessments for SuperGel with 1 ACH and low-humidity-post-application tests
Test
Assessment of curing time
[h:min:sec post-application, +/- SD]
5°C/20%/20% RH test/1 ACH air-flow
1:30:19
0:00:06
20°C/20%/20% RH test/1 ACH air-flow
1:29:45
0:00:07
40°C/20%/20% RH test/1 ACH air-flow
1:30:14
0:00:10
55
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56
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&EPA
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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