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 ------- 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 ------- 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 iii ------- 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. iv ------- 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 v ------- 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 vi ------- 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 vu ------- 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 viii ------- 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 ix ------- 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 x ------- 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) xi ------- 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 xii ------- 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. xiii ------- 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 xiv ------- 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. XV ------- 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. xvi ------- 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 1 ------- (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. 2 ------- 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, 3 ------- 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. 4 ------- Figure 2-1. Decontamination chamber. 2.2 Environmental Controls The associated schematics of the chamber are shown in Figure 2-2. 5 ------- 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., 6 ------- 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 ------- 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 ------- 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. 9 ------- 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. 10 ------- 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). 11 2013/06/19 ------- 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. 12 ------- 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 13 ------- 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 14 ------- 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. 15 ------- 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. 16 ------- 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 17 ------- 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. 18 ------- 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 19 ------- 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. 20 ------- 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 21 ------- 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, 22 ------- 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. 23 ------- 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. 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). 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. 25 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 56 ------- &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 ------- |