EPA/600/R-20/125 | June 2020
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
&EPA
Report for Assessment of Non-
Destructive Decontamination
Methodologies for Mixed Porous
Surfaces: Aging of Technology
under High Humidity and UV
Conditions
Office of Research and Development
Homeland Security Research Program

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Page intentionally left blank

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Report for Assessment of Non-Destructive Decontamination Methodologies for Mixed
Porous Surfaces: Aging of Technology under High Humidity and UV Conditions
Kathy Hall
U.S. Environmental Protection Agency
Center for Environmental Solutions and Emergency Response
Homeland Security & Materials and Management Division
Disaster Characterization Branch
Cincinnati, OH 45268
Ryan James, Xiaoyan Xia, Zachary Willenberg
Battelle; Columbus OH
EPA Contract No. EP-C-10-060 and EP-C-15-012.
June 2020

-------
- Page intentionally left blank -
ii

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Disclaimer
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development's
Homeland Security Research Program, funded and managed this evaluation. The document was
prepared by Battelle Memorial Institute under EPA Contract Number EP-C-15-002; Task Order 13. This
document was reviewed in accordance with EPA policy prior to publication. Note that approval for
publication does not signify that the contents necessarily reflect the views of the Agency. Mention of
trade names or commercial products does not constitute endorsement or recommendation for use of
a specific product.
Questions concerning this document or its application should be addressed to:
Kathy Hall
Center for Environmental Solutions and Emergency Response
Office of Research and Development (NG16)
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 379-5260
hall.kathy@epa.gov

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. To meet this mandate, EPA's research program is
providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants
affect our health, and prevent or reduce environmental risks in the future
The Center for Environmental Solutions and Emergency Response (CESER) within the Office of
Research and Development (ORD) conducts applied, stakeholder-driven research and provides
responsive technical support to help solve the Nation's environmental challenges. The Center's
research focuses on innovative approaches to address environmental challenges associated with the
built environment. We develop technologies and decision-support tools to help safeguard public
water systems and groundwater, guide sustainable materials management, remediate sites from
traditional contamination sources and emerging environmental stressors, and address potential
threats from terrorism and natural disasters. CESER collaborates with both public and private sector
partners to foster technologies that improve the effectiveness and reduce the cost of compliance,
while anticipating emerging problems. We provide technical support to EPA regions and programs,
states, tribal nations, and federal partners, and serve as the interagency liaison for EPA in homeland
security research and technology. The Center is a leader in providing scientific solutions to protect
human health and the environment.
Gregory Sales, Director
Center for Environmental Solutions and Emergency Response
iv

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
List of Abbreviations
%R
percent removal
cm
centimeter
Cs-137
cesium-137
DeconGel
DeconGel™ 1128 strippable coating
EPA
U.S. Environmental Protection Agency
HSRP
Homeland Security Research Program
mL
milliliter
mm
millimeter
Nal
sodium iodide
NIST
National Institute of Standards and Technology
QA
quality assurance
QC
quality control
RH
relative humidity
SC
strippable coating
Stripcoat
Stripcoat TLC Free™ strippable coating
STDEV
Standard deviation
T
temperature
UV
ultra-violet
UVA
ultra-violet A-rays
UVB
ultra-violet B-rays
piCi
microCurie
Hw/cm2
microwatt per square centimeter
V

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
ACKNOWLEDGMENTS
This document was developed by the U.S. Environmental Protection Agency's (EPA) Homeland
Security Research Program (HSRP) within EPA's Office of Research and Development. Kathy Hall was
the project lead for this document. Contributions of the following individuals and organizations to the
development of this document are acknowledged.
United States Environmental Protection Agency
Kathy Hall, Center for Environmental Solutions and Emergency Response
John Hall, Center for Environmental Solutions and Emergency Response
Terry Stilman, Region 4
Rick Demmer, Idaho National Laboratory
Michael Kaminski, Argonne National Laboratory
Battelle Memorial Institute
Ryan James
Xiaoyan Xia
Dalia Natour
Zachary Willenberg
vi

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Table of Contents
Page
List of Abbreviations	v
Table of Contents	vii
Executive Summary	ix
1.0 Introduction	1
2.0 Technology Descriptions	2
2.1	Stripcoat TLC Free™	2
2.2	DeconGel™ 1128	2
3.0 Experimental Details	2
3.1	Coupon Preparation	4
3.2	Contaminant Application	4
3.4	Controlled Coupon Storage	6
3.5	Application and Evaluation of Decontamination Technologies	6
3.6	Calculation of Decontamination Factor and Percent Removal	8
4.	Quality Assurance/Quality Control	8
4.1	Quality Assurance Measurements	8
4.2	Technical Systems Audit	8
4.3	Data Quality Audit	8
4.4	QA/QC Reporting	8
5.	Evaluation Results and Performance Summary	9
5.1 Evaluation Results	9
5.1.1	Phase 1. Bricks Stored and Strippable Coatings Dried in Elevated T and RH	9
5.1.2	Phase 2. Bricks Stored in Elevated T and RH with Strippable Coating Dried Under
Elevated UV	12
5.1.3	Phase 3. Baseline Study using Bricks Stored in Ambient Environmental Conditions	16
5.1.4	Summary of Strippable Coating Deployment and Operational Factors	16
5.1.5. Conclusions	18
6.	References	18
LIST OF FIGURES
Figure 1. Phase 1 and 3 brick (left) and Phase 2 brick (right)	4
Figure 2. Handheld pump sprayer	4
Figure 3. Activity measurement by Canberra Inspector 1000	5
Figure 4. Coupon Storage Chamber	6
Figure 5. Application of Stripcoat (left) and DeconGel (right)	6
Figure 6. RH controlled chamber with UV light exposure	7
Figure 7. Removal of decontamination technologies Stripcoat (left) and DeconGel (right)	7
LIST OF TABLES
Table 1. Number and Type of Mixed Brick Coupons Used for Each Experimental Condition	3
vii

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Table 2. %R for Bricks Stored and Strippable Coatings Dried in Elevated T and RH	9
Table 3. Qualitative Results for Bricks Stored and SCs Dried in Elevated T and RH	11
Table 4. %R of Bricks Stored in Elevated T and RH with Strippable Coating Dried under Elevated UV...12
Table 5. Abbreviated Brick-only Comparison of Phase 1 and Phase 2 Bricks	14
Table 6. Qualitative Data for Bricks Stored in Elevated T and RH with Strippable Coating Dried under
Elevated UV	14
Table 7. Stripcoat Deployment and Operation Factors	16
Table 8. DeconGel 1128 Deployment and Operation Factors	17
viii

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Executive Summary
The U.S. Environmental Protection Agency's (EPA's) Homeland Security Research Program (HSRP) is
protecting human health and the environment from adverse impacts resulting from chemical,
biological, radiological and nuclear contamination. Such contamination can result from an intentional
act (such as terrorism), or an unintentional act (such as a natural disaster or industrial accident). One
way the HSRP protects human health and the environment is by carrying out performance tests and
operational demonstrations on homeland security decontamination technologies. In 2015, EPA and
Battelle conducted an operational demonstration of two strippable coating (SC) decontamination
technologies, Stripcoat TLC Free™ SC (Stripcoat) and DeconGel™ 1128 SC (DeconGel). During this
demonstration (which occurred during the summer), Stripcoat and DeconGel were sprayed onto a
brick building and allowed to dry for approximately 24 hours. Following the drying step, the coatings
were unable to be removed from the brick surface. To further explore the result of this
demonstration, the HSRP recently evaluated the performance of Stripcoat and DeconGel under
controlled elevated temperature (T), relative humidity (RH), and ultra-violet (UV) light conditions. The
research included observation of the operational removal of the SCs as well as determination of the
efficacy for the removal of radioactive Cesium-137 (Cs-137) from aged mixed porous surfaces.
Brick coupons (excised samples) were contaminated with a liquid aerosol of Cs-137. At this point, pre-
contamination radiological activity was measured. Coupons were then placed in a vertical test stand.
Following manufacturer's recommendations, the SC decontamination technologies were applied to all
of the coupons in the test stand. Following the application of the SCs, Phases 1 and 2 of testing
included storing the contaminated brick coupons at elevated temperature (T) (81.8 °F ± 1.5 °F) and
relative humidity (RH) (averaged 82% ± 1%) conditions. Phase 1 experiments included drying the
coupons with the applied SCs under the elevated T and RH conditions over durations of overnight, and
3, 6, and 9 months. Phase 2 experiments included drying coupons with the applied SCs under elevated
T and RH conditions with UV light exposure over durations of overnight, and 3, 6, 9, and 12 weeks.
After the specified experimental durations, the post-decontamination radiological activity were
measured for each brick coupon tested. The decontamination efficacy was determined by calculating
a percent removal for each decontamination technology based on the measurements of pre- and
post-decontamination activity. Important deployment and operational factors were also documented
and reported.
Decontamination Efficacy: The decontamination efficacy (in terms of percent removal, %R) of
Stripcoat and DeconGel was evaluated following contamination of the coupons with approximately 1.7
microCurie (piCi) Cs-137 measured by gamma counting.
The Phase 1 decontamination efficacies of Stripcoat in terms of %R for Cs-137 were:
•	26% ± 5% after contaminant application without any storage in elevated T and RH
•	26% ± 6% after contaminated bricks were stored in elevated T and RH for 3 months
•	20% ± 2% after contaminated bricks were stored in elevated T and RH for 6 months
•	19% ± 3% after contaminated bricks were stored in elevated T and RH for 9 months
The Phase 1 decontamination efficacies of DeconGel in terms of %R were:
ix

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
•	28% ± 8% after contaminant application without any storage in elevated T and RH
•	28% ± 3% after contaminated bricks were stored in elevated T and RH for 3 months
•	36% ± 1% after contaminated bricks were stored in elevated T and RH for 6 months
•	39% ± 6% after contaminated bricks were stored in elevated T and RH for 9 months
The Phase 2 decontamination efficacies of Stripcoat with UV light exposure were:
•	52% ± 6% without any storage in elevated T and RH
•	43% ± 18% after contaminated bricks were stored in elevated T and RH for 3 weeks
•	45% ± 5% after contaminated bricks were stored in elevated T and RH for 6 weeks
•	40% ± 5% after contaminated bricks were stored in elevated T and RH for 9 weeks
•	51% ± 10% after contaminated bricks were stored in elevated T and RH for 12 weeks
The Phase 2 decontamination efficacies of DeconGel with UV light exposure were:
•	Under ambient storage conditions (non-elevated RH and T) none of the dried DeconGel was
able to be removed from the surface and therefore, no removal occurred
•	58% ± 4% after contaminated bricks were stored in elevated T and RH for 3 weeks
•	55% ± 6% after contaminated bricks were stored in elevated T and RH for 6 weeks
•	54% ± 6% after contaminated bricks were stored in elevated T and RH for 9 weeks
•	56% ± 1% after contaminated bricks were stored in elevated T and RH for 12 weeks
Deployment and Operational Factors: Stripcoat and DeconGel were applied with a paint sprayer,
dried overnight, and removed by peeling off the dried coating. Stripcoat was demonstrated to be
easily removed from the surface of the bricks regardless of the pre-decontamination brick storage or
SC drying conditions. DeconGel was demonstrated to be extremely difficult to remove following pre-
decontamination storage of bricks in ambient (non-humidified) conditions. However, after pre-
decontamination storage in elevated T and RH conditions, DeconGel was able to be applied, dried
overnight, and then removed relatively easily from the brick surface. Drying under elevated UV
conditions did not impact the ease of removal for either SC.
Research Conclusions:
•	Stripcoat decontamination efficacy and operational removal were independent of storage and
drying conditions. This is not consistent with results obtained during 2015 field testing.
However, variables of scale, brick, and aging conditions contribute to these differences.
•	DeconGel is extremely difficult and sometimes impossible to remove (using the standard
removal approach) after storage in ambient humidity conditions.
•	DeconGel removal efficacy may increase slightly after longer storage in elevated humidity
conditions.
•	DeconGel removal efficacy and operational removal were independent of the drying under
elevated UV exposure.
•	Decontamination efficacy is highly impacted by the brick surface as seen in the very different
%Rs from bricks from two different buildings built only 5 year apart.
x

-------
1.0 Introduction
The National Response Framework, Nuclear/Radiological Annex, published in June of 2008, designated
U.S. Environmental Protection Agency (EPA) as a coordinating agency for long term recovery following
terrorist incidents involving radioactive materials. Consistent with EPA's legislated mission, this
directive gives the EPA the governmental responsibility for the environmental response following
releases of radiological materials that impact non-coastal private property. To meet the expected
technology needs associated with acts of radiological terrorism, the EPA's Office of Research and
Development, Homeland Security Research Program (HSRP), is conducting research to develop and
deliver information on decontamination methods and technologies evaluations. These
decontamination technology evaluations provide data to be used in support of decisions concerning
the selection and use of decontamination technologies for buildings contaminated with radiological
threat agents.
The decontamination efficacy of Stripcoat TLC Free™ SC (Stripcoat) and DeconGel™ 1128 SC
(DeconGel) has been evaluated previously to remove radioactive cesium (Cs)-137 from different types
of surfaces in laboratory and pilot-scale experiments (1-7). The percent removals of Cs-137 from
different surfaces such as concrete, limestone, granite and marble were somewhat variable. In the
evaluation of Stripcoat on separate concrete surfaces study, the percent removal of cesium-137
between the 7-day and 30-day tests was determined to not be significantly different from one
another. However, the thinner application did result in the Stripcoat tearing at the borders of the test
coupons. In 2015, EPA and Battelle conducted an operational demonstration of these two strippable
coating (SC) decontamination technologies, Stripcoat and DeconGel (8). During this demonstration
(which occurred during the summer), Stripcoat and DeconGel were sprayed onto a brick building and
allowed to dry for approximately 24 hours. It was found that after applying multiple coats and
additional overnight dry time, both Stripcoat and DeconGel coatings were unable to be peeled off the
wall in pieces larger than a few square inches, having become entrapped in the mortar joints. It is not
clear if the lack of ability to peel was solely due to thickness of the layers of Stripcoat and DeconGel or
if surface characteristics or some other variable such as humidity or exposure to sunlight played a role.
To further explore the result of this demonstration, Battelle performed the project "Non-destructive
decontamination methodologies for mixed porous surfaces under high humidity and UV conditions"
under the direction of the U.S. EPA's HSRP through Contract EP-C-15-002. The experimental work
involved in this technology evaluation was performed at Battelle following their quality assurance
project plan. The experimental plan to evaluate the decontamination efficacy of two selected
commercial decontamination technologies for removal of Cesium-137 (Cs-137) from mixed brick
surfaces typically found in urban buildings and infrastructure is described below.
During this evaluation, the two SCs were applied to brick surfaces and aged under high temperature
(T) and relative humidity (RH) for a period of nine months. In addition, the same procedure was
conducted except the experimental time period was 12 weeks and the coupons with SCs were dried
overnight under elevated T and elevated ultra-violet (UV) conditions. As an operational baseline
experiment, the SCs were also applied to uncontaminated brick coupons (excised samples) that had
been stored under ambient environmental conditions (never in elevated RH). The evaluations took
place between November 2017 and October 2019. This report describes the quantitative results and
qualitative observations gathered during the evaluations.
1

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
2.0 Technology Descriptions
2.1	Stripcoat TLC Free™
Stripcoat (Stripcoat TLC Free™, Sanchem Inc., Chicago, IL) is a non-hazardous, non-toxic strippable
coating designed for safely removing and preventing the spread of radioactive contamination. As
shown in Figure 1, Stripcoat is sold as a "paint-like" formulation and application options include use of
a brush, roller, or sprayer (a sprayer was used during this project). The target thickness for application
is 1 millimeter (mm). While curing, Stripcoat mechanically entraps contamination. Following
application, the coating requires 410 hours to cure prior to removal (overnight was used during this
evaluation). The dried coating containing the encapsulated contamination can then be peeled off the
surface and disposed. Stripcoat can also serve as a barrier to prevent contamination from attaching to
a surface or as a covering to contain contamination. More information is available at
https://www.bhienergv.com/services/power-services/technologies/specialtv-coatings/
2.2	DeconGel™ 1128
DeconGel (DeconGel™ 1128, CBI Polymers Inc, Honolulu, HI) is a strippable coating designed for safely
removing radioactive contamination from surfaces or as a covering to contain contamination.
DeconGel 1128 is sold as a gel formulation and application options include use of a paint brush, roller,
or sprayer (a sprayer was used during this project). The water-based wet coating (hydrogel) can be
applied to horizontal, vertical or inverted surfaces and can be applied to most surfaces including bare,
coated and painted concrete, aluminum, steel, lead, rubber, Plexiglas®, Herculite®, wood, porcelain,
tile grout, vinyl, and ceramic and linoleum floor tiles.
Following application, the coating requires
approximately 12 hours to cure prior to removal.
When dry, the product binds the contaminants into a
polymer matrix. The dried coating containing the
encapsulated contamination can then be peeled off
the surface and disposed. More information is
available at www.decongel.com.
3.0 Experimental Details
The experimental steps included application of radioactive contaminant Cs-137 to the brick coupons,
measurement of radioactive contamination present on coupons by gamma counting, application of
the SC decontamination technologies, and subsequent measurement of residual contamination. This
study was performed in three phases characterized by how the contaminated brick coupons were
stored prior to decontamination and conditioned upon application of the SCs. Phase 1 included
storage of the contaminated coupons under elevated T and RH and post-application SC drying under
the same elevated T and RH conditions. Phase 2 was similar in that the contaminated brick coupons
were stored under elevated T and RH prior to application of the SCs, but upon application of the SCs,
Figure 1. Stripcoat (left) and DeconGel (right).
2

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
the overnight drying of the SCs took place under elevated T, RH and UV. Phase 3 was an operational
baseline experiment using non-contaminated brick coupons stored in ambient environment
conditions. The SCs were applied to these coupons and removed after overnight drying in ambient
environmental conditions.
Phase 1 was conducted over 9 months. For each of the SCs, 16 brick coupons were contaminated at
the start of the experiment, pre-decontamination activity measurements were collected, and then
four replicate contaminated coupons were decontaminated with SCs immediately with SC drying
under elevated T and RH. The rest of the coupons were placed in elevated T and RH storage. Then,
four replicate contaminated coupons were removed from elevated T and RH storage for pre-
decontamination activity measurements collection and SC decontamination (with drying under
elevated RH) in three-month increments (3, 6, and 9 months). The process was repeated with brick
coupons stored under elevated T and RH except that the coupons with SCs were dried overnight under
elevated T, RH and UV conditions in three-week increments (3, 6, 9 and 12 weeks) to determine the
decontamination efficacy attained by each decontamination technology. Phase 3 was conducted as a
one-time operational performance of the SC assessed by applying to brick coupons that had been
stored in ambient environmental conditions. The coupons with SCs were then dried under ambient
environmental conditions (never having been exposed to elevated RH or UV light). In addition, Quality
Control (QC) samples that included background and positive control coupons were evaluated using
four replicates each. Table 1 summarized the overall experimental design.
Table 1. Number and Type of Mixed Brick Coupons Used for Each Experimental Condition
Condition
# of Decon
Technologies
Sample
Collection
Cycles
Replicate
Samples
Total test
Samples
Background
Samples
Positive
Controls
Total
Coupons
Elevated T
and RH
2
4
(0, 3, 6, 9
months)
4
32
4
4
40
Elevated T,
RH and UV
(drying)
2
5
(0, 3, 6, 9, 12
weeks)
4
40
4
4
48
Ambient
Baseline
2
1
(time zero)
4
8
NA1
NA1
8
1NA - Not applicable as the ambient baseline experiment was an operational only test performed without
radiological contamination.
3

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
3.1 Coupon Preparation
All the brick coupons used during this study were collected during the demolition of two red-
brick buildings at Battelle. Phase 1 (elevated T and RH) and Phase 3 (ambient environment
condition) experiments were performed using bricks from a building that was constructed in
1956 (mortar made up approximately 10% of the surface) and Phase 2 experiments were
performed using bricks (mortar was not salvaged during demolition) from a building that was
constructed in 1951 (2). Full-sized bricks were cut using a diamond saw to dimensions of
approximately 10 centimeter (cm) x 15 cm with the outward face of the brick unaltered for
testing. Each coupon was marked with an identifying number using a permanent marker.
Figure 2. Phase 1 and 3 brick (left) and Phase 2 brick (right).
3.2 Contaminant Application
Each coupon was contaminated with approximately one milliliter (mL)
of unbuffered, slightly acidic aqueous solution containing 1.7 microCurie
(|iCi)/mL of Cs-137. This corresponded to the desired activity level of 1.7
fiCi per coupon delivered to each coupon using a handheld pump
sprayer (Figure 3) that had been calibrated to dispense the desired
volume. The liquid spike was prepared by diluting a 20 |iCi/mL solution
of Cs-137 to the proper spiking concentration using volumetric pipettes
and glassware. The contaminant spray was applied all the way to the
edges of the coupon. A small amount of pooling was expected and
occurred during contaminant application, but the coupon was air dried
briefly prior to activity measurement.
Figures. Handheld pump sprayer.
r
4

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
3.3 Contaminant Measurement
During each phase of testing, each contaminated coupon was
removed from the radiological containment storage in sealed
containers and a pre-decontamination activity measurement
was acquired (in the energy levels specific to Cs-137 [662 keV]
and Rb-86 [1,774 keV] only) using a sodium-iodide (Nal)
radiation detector, (Inspector™ 1000, Canberra, Meriden,
Connecticut), as shown in Figure 4. Following application of
the decontamination technologies, the residual radioactive
contamination on the same coupons was measured again, in
the identical geometry (by placing the bricks approximately
2.5 cm below the detector face in a marked location), to
calculate the percent removal (%R). In addition, four coupons
that had not been contaminated were measured for
background activity with each set of conditions. The BG
coupons were exposed to the same storage conditions but
were not exposed to the decontamination technologies
being evaluated. The pre- and post-decontamination counts were collected over a 100-second
measurement period. Because of the variable geometries of contaminant application, no activity
calculations were performed. Net counts per second were used as the quantitative unit for
determining decontamination efficacy by comparing the counts before decontamination to those after
decontamination.
A National Institute of Standards and Technology (NIST) traceable button source of Cs-137 was used
for a daily instrument check by placing it below the detector face in a common geometry.
Figure 4. Activity measurement by
Canberra Inspector 1000.
5

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
3.4	Controlled Coupon Storage
The contaminated brick coupons were stored within T and RH
controlled radiological containment. Specifically, the temperature-
controlled coupon storage chamber (HPI-1836, Avantco Equipment,
Lancaster, PA) shown in Figure 5 was located within a radiological
containment area in which a humidifier was used to elevate and
maintain the RH. The T and RH of the storage chamber were
continuously monitored and the data were stored in a HOBO data
logger (Onset, Bourne, MA). Over the course of Phase 1 (November
2017 - September 2018) and Phase 2 (July 2019 - October 2019),
the T averaged 81.8 °F ± 1.5 °F and the RH averaged 82% ± 1%.
Phase 2 included drying of the SCs under UV light exposure in the
same storage cabinet. UV light exposure was provided using a 24-
inch FLUVAL T5 QUAD fluorescent lighting system (Rolf C. Hagen
Corp., Mansfield, MA), which provided both the UV-A (wavelengths
320-400 nanometers [nm]) and UV-B (wavelengths 280-320 nm)
light to which the brick coupons were exposed. The brick coupons
were placed 5 cm below the lighting system for overnight drying.
Over the illuminated area, the UVA intensity averaged 98 microwatt
per square centimeter (|iw/cm2) ± 6 |iw/cm2 and the UVB intensity
averaged 11 |iw/cm2 ± 3 |iw/cm2. This UV light intensity
corresponds to a UV Index of at least 10 (considered 'Very High' by
EPA)(9-11).
3.5	Application and Evaluation of Decontamination Technologies
For each experimental cycle, eight brick coupons that had been stored in the T and RH-controlled
chamber and had undergone pre-decontamination activity measurement were transferred to a fume
hood to be decontaminated using Stripcoat and DeconGel (four brick coupons for each). Then the
brick coupons were placed on a stand inside an open-ended box for coating and radiological
containment. One coat of SC was applied to the surface of the coupons using a Wagner paint sprayer
with iSpray™ nozzle (Wagner SprayTech Corporation, Plymouth, MN). After an hour, another coat was
applied (Figure 6). Then, the coupons were transferred back to the chamber to dry overnight.
Figure 6. Application of Stripcoat (left) and DeconGel (right).
6

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
For Phase 1 experiments, the brick coupons were dried under elevated T and RH and for Phase 2
experiments, the brick coupons were dried under elevated T and RH as well as UV exposure for 15
hours. This was accomplished by illuminating the cabinet with UV bulbs as shown in Figure 7. For
Phase 3 experiments, the brick coupons were never contaminated, but they were stored under
ambient environmental conditions and when the SCs were applied, they were dried overnight under
ambient environmental conditions.
Figure 7. RH controlled chamber with UV light exposure.
After drying of the coupons coated with SCs, each of the dried coupons were transferred from the
chamber to a plastic container, sealed with duct tape, and put in a plastic transfer container. All of the
brick coupons tested were transferred to a radiological containment fume hood for SC removal.
Removal of the dried Stripcoat coating was easily removed by grabbing the edge of the dried SC and
pulling the SC off the surface in one piece. The dried DeconGel coating always required some
additional effort, such as a plastic
knife, to free a corner or an edge
so that the dried coating could be
removed from the surface as it
was more tightly bound to the
brick. Figure 8 shows a
photograph of removal of
Stripcoat and DeconGel. After
removal of the dried strippable
coating, the post-decontamination
radiological activity was measured Figure 8. Removal of decontamination technologies Stripcoat
for each brick coupon tested.	(left) and DeconGel (right).
/
" ^
7

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
3.6 Calculation of Decontamination Factor and Percent Removal
The efficacy of decontamination was calculated for each contaminated coupon in order to evaluate
the performance of each decontamination technology. The decontamination efficacy was represented
using the following equation for %R:
%R = l-(Af/A0) x 100%
where A0 is the radiological activity from the surface of the coupon before application of a
decontamination procedure and Af is radiological activity from the surface of the coupon after
application of the decontamination procedure. The %R is the percent of contamination that was
removed by the decontamination technology.
4. Quality Assurance/Quality Control
4.1	Quality Assurance Measurements
Quality assurance (QA)/quality control (QC) procedures were performed in accordance with the
project quality requirements. The measurement of gamma radiation from the surface of the coupons
was performed using a Nal gamma radiation detector and its accuracy was monitored through daily
performance checks that included analysis of a Cs-137 NIST standard. The counts per second from this
standard were required to be within 10% of the average response throughout the duration of testing.
Across 27 days of performing check samples, the average response was 152 ± 3 counts per second.
The percent difference from the average ranged from 1% to 7% with an average of 2% ± 1%. Both pre-
decontamination and post-decontamination activity measurements were conducted in triplicate. The
standard deviation of activity measurement for all of the replicate brick coupons were less than 10%.
The background activity of four non-contaminated coupons were measured for each decontamination
technology. No background subtraction was performed.
4.2	Technical Systems Audit
A technical systems audit was conducted during testing to ensure that the evaluation was performed
in accordance with project quality requirements. As part of the audit, the actual evaluation
procedures were compared with those specified in the project quality requirements. In addition, the
data acquisition and handling procedures were reviewed. No significant adverse findings were noted
in this audit. The records concerning the audit are stored indefinitely with the Battelle QA Manager.
4.3	Data Quality Audit
At least 10% of the data acquired during the evaluation were audited. The Battelle QA Manager traced
the data from the initial acquisition, through reduction and statistical analysis, to final reporting, to
ensure the integrity of the reported results. All calculations performed on the data undergoing the
audit were checked. No significant findings were noted.
4.4	QA/QC Reporting
Each assessment and audit was documented in accordance with project quality requirements.
8

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
5. Evaluation Results and Performance Summary
5.1 Evaluation Results
The decontamination efficacy of the Stripcoat and DeconGel was measured for each contaminated
coupon in terms of percent removal (%R). The removal percentage of decontamination for each brick
coupon was calculated using the equation in Section 3.6. Since all of the background activity is below
detection limit, the raw count rate was used to calculate %R. The results are discussed below based on
different experimental conditions.
5.1.1 Phase 1. Bricks Stored and Strippable Coatings Dried in Elevated T and RH
Table 2 gives the %R for each brick coupon tested, the average %R and standard deviation for each
decontamination technology over four replicates collected during each month of testing.
Table 2. %R for Bricks Stored and Strippable Coatings Dried in Elevated T and RH
Month
Stripcoat
DeconGel
% removal
Average
STDEV
% removal
Average
STDEV

22%


21%


0
27%
26%
5%
33%
28%
8%
24%
37%

33%


20%



29%


28%


3
20%
26%
6%
28%
28%
3%
33%
31%

21%


23%



20%


36%


6
17%
20%
2%
38%
36%
1%
20%
36%

22%


36%



21%


35%


9
21%
19%
3%
47%
39%
6%
15%
33%

18%


41%


The decontamination efficacies of Stripcoat in terms of %R for Cs-137 were:
•	26% ± 5% after contaminant application without any storage in elevated T and RH
•	26% ± 6% after contaminated bricks were stored in elevated T and RH for 3 months
•	20% ± 2% after contaminated bricks were stored in elevated T and RH for 6 months
•	19% ± 3% after contaminated bricks were stored in elevated T and RH for 9 months
9

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Several t-tests were performed to evaluate the likelihood that the average Stripcoat %R results for
each month were the same. The t-test results indicated the %R from each successive month of testing
were not significantly different from one another. The %R associated with the initial test referred to as
month 0 was significantly different from month 6 (p=0.041) and month 9 (p=0.032). Differences were
significant at the 95% confidence level (p-values < 0.05). Even with these significant differences the
overall average %Rs for Stripcoat spanned only 7 % so the magnitude of difference was not large.
The decontamination efficacies of DeconGel in terms of %R were:
•	28% ± 8% after contaminant application without any storage in elevated T and RH
•	28% ± 3% after contaminated bricks were stored in elevated T and RH for 3 months
•	36% ± 1% after contaminated bricks were stored in elevated T and RH for 6 months
•	39% ± 6% after contaminated bricks were stored in elevated T and RH for 9 months
Several t-tests were performed to evaluate the likelihood that the average DeconGel %R results for
each month were the same (at the 95% confidence level). The t-test results indicated the %R from
month 0 was not significantly different from any of the other months. Month 3 was significantly less
than months 6 (p=0.002) and 9 (p=0.018). Moreover, months 6 and 9 (p=0.46) were not significantly
different from one another at the 95% confidence level. Even with these significant differences, the
overall average %Rs for DeconGel spanned only 11 % so the magnitude of difference is not large.
Additional t-tests were performed to evaluate the likelihood that the average %Rs of Stripcoat and
DeconGel between months were different. For months 0 (p=0.73) and 3 (p=0.64), these analyses
confirmed what seems obvious just by comparing the averages and standard deviations (which clearly
overlap) as the t-test indicated there was not a significant difference between the Stripcoat and
DeconGel %Rs. The t-test results demonstrated significant differences between Stripcoat and
DeconGel during month 6 (p<0.0001) and 9 (p=0.001), confirming the comparison of averages and
standard deviation of the Stripcoat and DeonGel. The %Rs of DeconGel were higher than that of
Stripcoat with 36%±1% compared to 20%±1% month 6 and 39%±6% compared to 19%±3% for month
9 indicating that DeconGel demonstrated a greater efficacy when the coupons were stored in high RH
chamber longer. Note that during months 0 and 3, for DeconGel, not all of the dried SC was able to be
removed from the brick surface, therefore decreasing the %R attained to various extents that are not
fully captured by the quantitative data. These qualitative operational factors are described below.
In addition to the quantitative %R determinations, another important set of data were the operation
factors surrounding the removal of the strippable coatings throughout the course of the experiment.
Table 3 presents the qualitative data for the bricks stored and strippable coatings dried in elevated T
and RH (Phase 1 experiments). These qualitative data include the approximate time required for
removal of the strippable coating for each brick as well as the approximate amount of coating that
was able to be removed from the brick and mortar. Summary observations are included below.
10

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Table 3. Qualitative Results for Bricks Stored and SCs Dried in Elevated T and RH
Month
Stripcoat
DeconGel
Time for
removal (min)
Coating removed
Time for
removal (min)
Coating removed
0
1
100%
10
~90% from brick, ~10% from mortar
1
100%
10
~95% from brick and mortar
1
100%
10
~95% from brick, ~90% from mortar
1
100%
20
~75% from brick, ~0% from mortar
3
1
100%
13
~95% from brick, ~0% from mortar
1
100%
8
~95% from brick, ~0% from mortar
1
100%
35
~95% from brick, ~0% from mortar
1
100%
>20
~66% from brick, ~0% from mortar
6
1
100%
5
100%
2
100%
4
100%
2
100%
3
100%
5
100%
3
100%
9
1
100%
4
100%
1
100%
5
100%
1
100%
5
100%
1
100%
3
100%
Observations from the qualitative data for elevated RH experiments include:
•	Dried Stripcoat was relatively easy to peel off as 100% was always able to be removed from
the brick and mortar components of the coupons. The time required for removal of the dried
coating from each brick was in the range of 1 to 5 minutes.
•	Dried DeconGel was more difficult to peel off, especially on mortar. During the 0- and 3-
month experiments, after 8-35 minutes of working on the removal, complete removal of
DeconGel was not able to be attained from any of the brick coupons. In several cases, almost
all (>95%) of the DeconGel was removed, but in three instances between 10-33% remained on
the brick and there were several instances that most or all of the DeconGel remained on the
mortar component of the brick. In the cases where the DeconGel could not be removed, it
was because the edges of the coating were not able to be peeled up from the surface at all,
thereby not allowing the decontamination technician to be able to grip and then peel off the
coating from the rest of the surface.
•	While still more difficult to remove than the Stripcoat (note the removal times for each),
during the 6 and 9-month experiments, the dried DeconGel coating was completely removed
from both brick and mortar surfaces in a single piece.
•	Dried Stripcoat coating was able to be removed by starting to peel the edge of the brick by
gripping the dried coating by hand and then peeling the rest of the coating off of the surface.
Dried DeconGel could be peeled off in similar manner, but in order to grip the edge of the
11

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
coating a plastic knife was required to pry the edge of the coating off the surface in order to
allow gripping it by hand. Then the peeling had to be done little by little in order to keep the
dried DeconGel coating from tearing. In contrast, dried Stripcoat was more elastic, not tearing
easily, therefore easily removed in one piece once the edge was started.
Overall, the data indicate that for Stripcoat, the operational function is largely independent of the
storage and/or drying in elevated T and RH conditions, but for DeconGel, the longer that the bricks are
stored within elevated T and RH conditions, the more likely it is that the dried DeconGel coating will
be able to be removed from the bricks.
5.1.2 Phase 2. Bricks Stored in Elevated T and RH with Strippable Coating Dried Under
Elevated UV
Table 4 gives the %R for each brick coupon tested, the average %R and standard deviation for each
decontamination technology over four replicates collected during each week of testing. The
decontamination efficacies of Stripcoat were determined after the contaminated bricks had been
stored in elevated T and RH for timeframes ranging from 0 to 12 weeks. In separate Stripcoat
experiments after 0, 3, 9, and 12 weeks, the Stripcoat was applied to the contaminated surfaces and
then dried over 15 h with elevated T and UV. Under these conditions, the %Rs were:
•	52% ± 6% without any storage in elevated T and RH
•	43% ± 18% after contaminated bricks were stored in elevated T and RH for 3 weeks
•	45% ± 5% after contaminated bricks were stored in elevated T and RH for 6 weeks
•	40% ± 5% after contaminated bricks were stored in elevated T and RH for 9 weeks
•	51% ± 10% after contaminated bricks were stored in elevated T and RH for 12 weeks
Several t-tests were performed to evaluate the likelihood that the average Stripcoat %R results for
each week were the same. The t-test results indicated the %Rs from each successive week of testing
were not significantly different from one another while the %R associated with the initial test, referred
to as Week 0, was significantly different from Week 6 (p=0.021). Even with this significant difference
the overall average %R for Stripcoat spanned only 12 % so the magnitude of difference is not large.
Table 4. %R of Bricks Stored in Elevated T and RH with Strippable Coating Dried under Elevated
UV
Weeks
Stripcoat
DeconGel
% removal
Average
STDEV
% removal
Average
STDEV
0
60%
52%
6%
NR
NR
NR
52%
NR
50%
NR
46%
NR
3
37%
43%
18%
56%
58%
4%
70%
54%
33%
62%
33%
61%
6
45%
45%
5%
56%
55%
6%
12

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Weeks
Stripcoat
DeconGel
% removal
Average
STDEV
% removal
Average
STDEV

50%


46%



38%


59%



46%


57%



43%


60%


9
41%
40%
5%
58%
54%
6%
33%
50%

43%


47%



66%


57%


12
47%
51%
10%
56%
56%
1%
48%
57%

43%


55%


NR - no removal as the dried SC was not able to be removed from the brick.
The decontamination efficacies of DeconGel after the contaminated bricks had been stored in
elevated T and RH from 0 to 12 weeks and the drying was done over 15 h of elevated T and UV were:
•	Under ambient storage conditions (non-elevated RH and T) none of the dried DeconGel was
able to be removed from the surface and therefore, no removal occurred
•	58% ± 4% after contaminated bricks were stored in elevated T and RH for 3 weeks
•	55% ± 6% after contaminated bricks were stored in elevated T and RH for 6 weeks
•	54% ± 6% after contaminated bricks were stored in elevated T and RH for 9 weeks
•	56% ± 1% after contaminated bricks were stored in elevated T and RH for 12 weeks
The average %Rs from the Phase 2 experiments range from 54% to 58%. This compares with a range of
28% to 39% during the Phase 1 experiments. As for the Stripcoat results discussed above, this was
somewhat unexpected but was attributed to the bricks being sourced from different buildings.
Another interesting aspect of the DeconGel results is that the Week 0 experiments resulted in none of
the dried DeconGel being removed from the brick surface. Therefore, none of the Cs-137 was able to
be removed. Consistent with the Phase 1 results, this is attributed to the storage of the bricks in
ambient conditions prior to the start of the elevated T and RH experiments. This will be discussed
further in the discussion of qualitative factors below.
Several t-tests were performed to evaluate the likelihood that the average DeconGel %R results for
each week were the same. The t-test results indicated the %Rs across the entire experiment were not
significantly different from one another (p-values ranged from 0.29 to 0.84).
Additional t-tests were performed to evaluate the likelihood that the average %Rs of Stripcoat and
DeconGel between weeks were different. For Weeks 3 (p=0.19) and 12 (p=0.38), these analyses
confirmed what seems obvious just by comparing the averages and standard deviations (which clearly
overlap) as the t-test indicated there was not a significant difference between the Stripcoat and
DeconGel %Rs. The t-test results demonstrated significant differences between Stripcoat and
DeconGel during month 6 (p=0.040) and 9 (p=0.013), confirming the comparison of averages and
standard deviation of the Stripcoat and DeconGel. The %Rs of DeconGel were higher than that of
13

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Stripcoat with 55%±6% compared to 45%±5% for month 6 and 54%±6% compared to 40%±5% for
month 9.
The average %Rs from the Phase 2 experiments range from 40% to 52%. This compares with a range of
19% to 26% during the Phase 1 experiments. This was somewhat unexpected as the bricks used in
each experiment looked similar; however, they were collected from different buildings and apparently
had different characteristics that impacted the %Rs. The Phase 1 bricks were from a building built in
1956 and the Phase 2 bricks from a building built in 1951. One possible reason for this discrepancy was
that the Phase 1 bricks had mortar on one edge while the Phase 2 bricks had no mortar. It is possible
that the Phase 1 bricks (or perhaps the mortar) had a higher affinity for Cs-137 or that Cs-137 was
transported below the surface where there would be no access to the strippable coating for removal.
An abbreviated experiment was performed to study the impact of mortar on the decontamination
efficacy.
There were four bricks remaining from the Phase 1 project so an abbreviated experiment was
performed where the Phase 1 and Phase 2 bricks were contaminated onto the brick only (no
contamination was sprayed onto the mortar of the Phase 1 bricks) that had been stored at 80% RH for
5 days. Then Stripcoat was applied to 2 bricks and DeconGel was applied to 2 bricks and overnight
drying was performed without elevated RH or UV. The results (Table 5) show that the %Rs are very
similar to the Phase 2 removals suggesting that the presence of mortar tends to increase the affinity of
mixed surfaces for Cs-137, decreasing the decontamination efficacy (as was seen when mortar was
included during the Phase 1 experiments).
Table 5.	Abbreviated Brick-only Comparison of Phase 1 and Phase 2 Bricks
Bricks
Stripcoat
DeconGel
% removal
Average
% removal
Average
Phase 1
47%
40%
52%
54%
32%
55%
Phase 2
49%
48%
59%
60%
47%
60%
As during Phase 1, the operational factors surrounding the removal of the strippable coatings were
documented throughout the course of the experiment. Table 6 presents the qualitative data for the
(Phase 2 experiments). These qualitative data include the approximate time required for removal of
the strippable coating for each brick as well as the approximate amount of coating that was able to be
removed from the brick surface.
Table 6. Qualitative Data for Bricks Stored in Elevated T and RH with Strippable Coating Dried
under Elevated UV
Week
Stripcoat
DeconGel
Time for removal
(min)
Coating removed
Time for removal
(min)
Coating removed
0
1
100%
~10
0%
1
100%
~10
0%
14

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0

Stripcoat
DeconGel
Week
Time for removal
(min)
Coating removed
Time for removal
(min)
Coating removed

1
100%
"10
0%

1
100%
~10
0%

2-3
100%
10
100%
3
2-3
100%
2
100%
2-3
100%
10
100%

2-3
100%
3
100%

1.5-2
100%
2-3
>90%
6
1.5-2
100%
2
100%
1.5-2
100%
2
100%

1.5-2
100%
2
100%

2
100%
15
>95%
9
1
100%
<10
>95%
1
100%
3
100%

1
100%
3
100%

~2
100%
~2
>95%
12
~2
100%
~2
>95%

~2
100%
~2
>95%

~2
100%
~12
>90%
Observations from the qualitative data for Phase 2 experiments including bricks stored in elevated T
and RH with strippable coating dried under elevated UV include:
•	Dried Stripcoat coating was relatively easy to peel off as 100% was always able to be removed
from the brick coupons. The time required for removal of the dried coating from each brick
was in the range of 1 to 3 minutes. There was not a notable difference in Stripcoat removal
between the Phase 1 and Phase 2 experiments.
•	Dried DeconGel coating was more difficult to peel off than Stripcoat. During the initial week of
experiments, after 10 minutes of effort, the decontamination technicians were not able to get
a grip on the dried coating at the edge of the brick. Because no progress seemed likely the
effort to remove it was abandoned.
•	Lack of DeconGel removal during Week 0 suggested that the UV drying may have been the
cause of the removal difficulty. However, during the Weeks 3-12 experiments using bricks
stored at elevated T and RH (with UV applied only during SC drying), between 90%-100% of
the dried DeconGel was able to be removed from every brick with the removal time ranging
from 2-15 minutes, but in most cases removal occurring in 2 or 3 minutes, which is similar to
Stripcoat. During Weeks 3-12, there was not a notable difference in DeconGel removal
between Phase 1 and Phase 2 experiments.
•	Similar to the Phase 1 experiments, dried Stripcoat coating was able to be removed by starting
to peel the edge of the brick by gripping the dried coating by hand and then peeling the rest of
the coating off of the surface. Dried DeconGel could be peeled off in similar manner, but in
15

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
order to grip the edge of the coating a plastic knife was required to pry the edge of the coating
off the surface in order to allow gripping it by hand. Then the peeling had to be done little by
little in order to keep the dried DeconGel coating from tearing. In contrast, dried Stripcoat was
more elastic, not tearing easily, and therefore easily removed in one piece once the edge was
started.
These data also indicate that for Stripcoat, the operational function is largely independent of the
storage in elevated T and RH conditions and drying with elevated UV exposure. For DeconGel, storage
of brick in ambient environmental conditions (specifically non-humidified) have a detrimental effect
on the ability to remove dried DeconGel from the brick surfaces. In addition, the data suggest that
DeconGel removal function is independent of UV drying.
5.1.3	Phase 3. Baseline Study using Bricks Stored in Ambient Environmental Conditions
The Phase 3 study was purely an operational evaluation (no Cs-137 contamination was applied to the
bricks) of Stripcoat and DeconGel being applied to brick coupons to observe its removal after bricks
had been stored in ambient environmental conditions. Consistent with the Phase 2 experimental
results, the Stripcoat was able to be removed from the bricks in approximately 1 minute while the
DeconGel was not able to be removed from the bricks at all. Again, after 10 minutes of effort the
removal attempt was abandoned.
5.1.4	Summary of Strippable Coating Deployment and Operational Factors
Tables 7 and 8 summarize various practical information (both qualitative and quantitative) gained
during the evaluation of Stripcoat during this and previous technology evaluations (12,13)involving
these strippable coatings. A number of operational factors were documented by the technician who
performed the testing.
Table 7. Stripcoat Deployment and Operation Factors	
Parameter	Description/Information
Decontamination
rate
Coating preparation: Provided ready for use
Application: Approximately 3 minutes at 100 mL per coat onto 0.16 m2 for an
application rate of 3.2 m2/hour and a Stripcoat use rate of 625 mL/m2 for each
coat
Drying time: overnight	
Applicability to
irregular surfaces
Application to more irregular surfaces than were tested here is unlikely to be a
problem as a sprayer can coat most surfaces accessible to an operator
Stripcoat cures to a very elastic film that is conducive for use on irregular
surfaces (such as brick)	
Skilled labor
requirement
After a brief training session to explain the procedures, no special skills would
be required to successfully perform both the application and removal
procedures
Utilities requirement
No utilities were needed when paint brush application was used
Stripcoat was applied using a paint sprayer, which requires minimum 120 volts
	alternating current power	
_ ^ ^ ^	• With the exception of extreme cold, which would prevent the application of the
Extent ot portability	, , .
water-based Stripcoat, the technology is portable
16

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
Shelf life of media
• Shelf life is advertised as one year
Secondary waste
• Solid waste production: approximately 400 g/m2for two applications of two
management
coats
Surface damage
• No visible surface damage; removed only loose particles that were
consequently stuck to the removed coating
• $24/L corresponding to $17/m2 per application; Bartlett suggests three
applications, which would correspond to approximately $50/m2
Table 8. DeconGel 1128 Deployment and Operation Factors
Parameter
Decontamination
rate
Description/Information
Coating preparation: Provided ready for use
Application: Approximately 3 minutes at 250 mL per coat onto 0.16
m2 for an application rate of 3.2 m2/hour and a DG 1128 use rate of
1.56 L/m2 for each coat
Drying time: overnight
Applicability to
irregular surfaces
Application to more irregular surfaces than were tested here is
unlikely to be a problem as a sprayer can coat most types of surfaces
accessible to an operator
DG 1128 cures to a relatively strong but flexible film that is
conducive for use on the surfaces made from brick as was used
during this evaluation
Skilled labor
requirement
After a brief training session to explain the procedures, no special
skills would be required to successfully perform both the application
and removal procedures
Utilities
requirement
No utilities when paint brush application was used
DeconGel 1128 was applied using a paint sprayer, which requires
minimum 120 volts alternating current power
Extent of
portability
With the exception of extreme cold, which would prevent the
application of the water-based DG 1128, the technology is not
limited due to portability
Shelf life of media
Shelf life is advertised as one year
Secondary waste
management
Solid waste production: approximately 460 g/m2for two applications
of two coats
Surface damage
No visible surface damage; removed only loose particles that were
consequently stuck to the removed coating
Cost
Cost is $40/L, which corresponds to approximately $240/m2 if used
in a similar way as used during this evaluation.
17

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
5.1.5. Conclusions
•	Stripcoat decontamination efficacy and operational removal were independent of storage and
drying conditions. They might be related to the coating thickness applied and the length of curing.
However, the effect of loading volume (thickness) and the curing time were not investigated in
this study.
•	DeconGel is extremely difficult to remove after storage in ambient humidity conditions.
•	DeconGel removal efficacy may increase slightly after longer storage in elevated humidity
conditions.
•	DeconGel removal efficacy and operational removal were independent of the drying under
elevated UV exposure.
•	Decontamination efficacy is highly impacted by the brick surface as seen in the very different %Rs
from bricks from two different buildings built only 5 year apart. This indicated that the property of
the brick surface might affect the binding of Cs-137 to the decontamination technology or the
percentage of peeling.
6. References
1.	U.S. Environmental Protection Agency (U.S. EPA). Bartlett Services, Inc. Stripcoat TLC FreeTM
Radiological Decontamination Strippable Coating Technology Evaluation Report. U.S.
Environmental Protection Agency, Cincinnati, OH. EPA/600/R-08/099, September 2008.
2.	U.S. Environmental Protection Agency (U.S. EPA). Removing Radiological Contamination from
Concrete Using Strippable Coatings, EPA Technical Brief. U.S. Environmental Protection Agency,
Cincinnati, OH. EPA/660/S-08/021, October 2008.
3.	U.S. Environmental Protection Agency (U.S. EPA). CBI Polymers DeconGel® 1101 and 1108 for
Radiological Decontamination. U.S. Environmental Protection Agency, Cincinnati, OH. EPA 600/R-
11/084, August 2011.
4.	U.S. Environmental Protection Agency (U.S. EPA). Evaluation of Nine Chemical-Based Technologies
for Removal of Radiological Contamination from Concrete Surfaces. U.S. Environmental Protection
Agency, Cincinnati, OH. EPA Technical Brief, August 2011.
5.	U.S. Environmental Protection Agency (U.S. EPA). Decontamination of Cesium, Cobalt, Strontium,
and Americium from Porous Surfaces. U.S. Environmental Protection Agency, Cincinnati, OH.
EPA/600/R-13/232, November 2013.
6.	U.S. Environmental Protection Agency (U.S. EPA). Technology Evaluation Report: Non-Destructive
Decontamination Methodologies for Mixed Porous surfaces. U.S. Environmental Protection
Agency, Cincinnati, OH. EPA/600/R-16/150 June 2016.
18

-------
Radiological Decontamination of Mixed Porous Surfaces: High Humidity and UV Conditions Date: 6/29/2020
E PA/600/R-20/125
Version: 0
7.	U.S. Environmental Protection Agency (U.S. EPA). Evaluation of the Curing Times of Strippable
Coatings and Gels as used for Radiological Decontamination. U.S. Environmental Protection
Agency, Cincinnati, OH. EPA/600/R-14/238, September 2014.
8.	U.S. Environmental Protection Agency (U.S. EPA). Technical Report for the Demonstration of Wide
Area Radiological Decontamination and Mitigation Technologies for Building Structures and
Vehicles. U.S. Environmental Protection Agency, Cincinnati, OH. EPA/600/R-16/019, 2016.
9.	Craig S. Long, Alvin J. Miller, Hai-Tien Lee, Jeannette D. Wiid, Richard C. Przywarty, and Drusilla
Hufford. [National Weather Service] Ultraviolet Index Forecast Vol. 77, No. 4, April 1996.
10.	UV radiation monitoring: UV index and UV dose, http://www.temis.nl/uvradiation/info/
(accessed March 30, 2020).
11.	U.S. EPA. Action Steps for Sun Protection, U.S. Environmental Protection Agency, Washington DC.
EPA/430-F-99-026; September 1999.
12.	U.S. EPA. Bartlett Services, Inc. StripcoatTLC Free™ Radiological Decontamination of Americium,
U.S. Environmental Protection Agency, Cincinnati, OH. EPA 600/R-13/005, February 2013.
13.	U.S. EPA. CBI Polymers DeconGel® 1108 for Radiological Decontamination of Americium, U.S.
Environmental Protection Agency, Cincinnati, OH. EPA 600/R-12/067, January 2013.
19

-------
vvEPA
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

-------