ML11355A213
| ML11355A213 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/21/2011 |
| From: | Environmental Protection Agency |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| Shared Package | |
| ML11355A208 | List: |
| References | |
| RAS 21596, 50-247-LR, ASLBP 07-858-03-LR-BD01, 50-286-LR | |
| Download: ML11355A213 (4) | |
Text
NYS000260 Submitted: December 21, 2011 Strippable Coatings l Homeland Security Research l US EPA Page 1 of 4 Jump to main content.
Homeland Security Research Contact Us Search: All EPA This Area Go
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- Strippable Coatings Research Highlights Removing Radiological Contamination From Concrete Using Strippable Coatings This document does not constitute nor should be construed as an EPA endorsement of any particular product, service, or technology.
EPA evaluates homeland security related technologies that will help protect human health and the environment from the adverse impacts of terrorist acts. Radiological attacks may require massive evacuation to protect human health and greatly interfere with economic and business activities. As a result, there is much interest in technologies that can be used to mitigate these effects and help with the cleanup following terrorist acts.
As part of this effort, EPA has evaluated two strippable coating technologies for their ability to remove cesium-137 (Cs-137) from concrete surfaces:
- Stripcoat TLC Free' (Bartlett Services Inc.)
- OrionTM Strippable Coating (Orion' SC) (Isotron Corp.)
Figure 1. Applying the Coating with a Sprayer The coatings were applied to concrete coupons contaminated with Cs-137. Both products can be applied like paint, using commercially available, airless paint sprayers, brushes, or rollers. Figure 1 shows application with a paint sprayer, the method used in this evaluation. The treated surfaces were allowed to cure overnight into a solid coating and were then removed from the concrete surface. Orion' SC apparently binds radiological material through chemical and physical interactions when it is cured. Stripcoat TLC Free' apparently binds radiological material only http://www.epa.gov/nhsrc/news/news102908.html 11/1/2011
Strippable Coatings l Homeland Security Research l US EPA Page 2 of 4 through physical interaction between the radiological material and the cured coating. Each technology was evaluated for:
- Decontamination efficacy (percent removal) from vertical and horizontal surfaces, 7 days and 30 days after contamination of the coupons
- Application and removal times
- Ease of use on irregular surfaces
- Labor requirements
- Utility requirements
- Portability
- Secondary waste
- Surface damage
- Preparation and cleanup
- Cost Note that the 7-day and 30-day tests were performed to determine if a more rapid response would provide a better decontamination efficacy with these products. Another important objective of the evaluation was to determine if the wet strippable coatings would adhere adequately to a vertical surface.
Test Design To evaluate the decontamination technologies on vertical surfaces (simulating walls) as well as horizontal surfaces (simulating sidewalks and driveways), a test stand was fabricated that held four rows of six concrete coupons to create surfaces that were approximately 90 centimeters (cm) wide x 60 cm deep (horizontal) or tall (vertical). Concrete coupons were made of standard building concrete that met the specifications for both Type I and II Portland cements.
Each coupon was 15 cm square and 4 cm thick. Six of the 24 coupons used to construct each surface were contaminated with Cs-137 (approximately 53 microcuries [µCi]).
Figure 2 shows several concrete coupons and a test stand loaded with the coupons.
Figure 2. Concrete Coupons (left) and Test Stand With Contaminated Coupons (right) - H and V indicate horizontal and vertical orientation, respectively, and A-F indicate the surface positions After the coupons were contaminated with Cs-137, some were allowed to age for 7 days and some for 30 days prior to their placement in the test stand for application and removal of the coatings.
Following application, the coatings were allowed to dry overnight, and then removed by first scoring an edge with a paint scraper and then pulling the coating off the surface by hand or scraping lightly. Following the manufacturers recommendations, this application and removal process was repeated three times. Figure 3 shows the removal processes for each coating. After the final removal of the coatings, the residual radioactivity on the coupons was measured. The decontamination efficacy was determined from the difference in activity before and after application of the decontamination technologies.
http://www.epa.gov/nhsrc/news/news102908.html 11/1/2011
Strippable Coatings l Homeland Security Research l US EPA Page 3 of 4 Figure 3. Removal of Stripcoat TLC Free' (left) and Removal of Orion' SC (right)
Performance and Results The decontamination efficacy calculated for each of the contaminated coupons is expressed in terms of percent removal (%R). Table 1 gives the Cs-137 activity on the concrete coupons before and after the application of the coatings for both the 7-day and 30-day tests in both horizontal and vertical orientations.
- For Stripcoat TLC Free', the overall average %R for the 7-day and 30-day tests was 32.0 +/- 9.9.
- For Orion' SC, the overall average %R for the 7-day and 30-day tests was 76.2 +/- 7.4.
- For each technology, %Rs from the 7-day and 30-day tests were not significantly different from one another.
- For each technology, %Rs from the vertical and horizontal surfaces were not significantly different from one another.
Table 1. Decontamination Efficacy Results for 7-Day and 30-Day Tests Strippable Coating Days Following Pre-Decontamination Post-Decontamination Cs-137 Technology Contamination and Cs-137 Activity Cs-137 Activity a b %Rb (Company) Orientation Ci Cib 7H 56.8 +/- 1.7 38.3 +/- 4.5 32.5 +/- 8.5 7V 53.5 +/- 1.7 38.5 +/- 5.3 28.0 +/- 9.8 Stripcoat TLC 7 Overall 55.2 +/- 2.4 38.4 +/- 4.7 30.3 +/- 9.0 Free' (Bartlett Services Inc.) 30 H 53.2 +/- 3.0 34.3 +/- 5.8 35.8 +/- 8.7 30 V 55.6 +/- 1.4 37.8 +/- 7.0 31.9 +/- 13.0 30 Overall 54.4 +/- 2.6 36.0 +/- 6.4 33.8 +/- 10.7 7H 55.7 +/- 1.3 11.3 +/- 2.3 79.7 +/- 4.1 7V 53.6 +/- 1.5 12.0 +/- 2.6 77.5 +/- 5.2 Orion' SC (Isotron 7 Overall 54.6 +/- 1.7 11.7 +/- 2.3 78.6 +/- 4.6 Corp.) 30 H 53.6 +/- 1.8 12.9 +/- 6.5 76.2 +/- 11.2 30 V 53.3 +/- 1.9 15.3 +/- 3.8 71.5 +/- 6.3 30 Overall 53.5 +/- 1.8 14.1 +/- 5.2 73.8 +/- 9.0 a
Orientation: H indicates horizontal surface, V indicates vertical surface, and Overall, the average of horizontal and vertical surfaces.
b Data are presented in terms of average and standard deviation.
Operational factors of using these strippable coatings are identified and summarized in Table 2.
Table 2. Strippable Coating Operational Factors Stripcoat TLC Free' Factors Orion' SC (Isotron Corp.)
(Bartlett Services Inc.)
Application and Application: 12 m2/hr Application: 4.6 m2/hr removal Removal: 4.9 m2/hr Removal: 1.6 m2/hr Ease of use on Elastic coating readily peels off surface Some scraping might be required irregular surfaces Labor requirements No specialized training No specialized training http://www.epa.gov/nhsrc/news/news102908.html 11/1/2011
Strippable Coatings l Homeland Security Research l US EPA Page 4 of 4 Utility requirements If sprayer used, 110 v; otherwise none If sprayer used, 110 v; otherwise none Portability Portable Portable Secondary waste Solid waste production: ~0.26 kg/m2 Solid waste production: ~0.5 kg/m2 Solid waste density: ~0.145 g/cm3 Solid waste density: ~0.188 g/cm3 Surface damage Minimal, only loose particles Minimal, only loose particles removed removed Preparation and Product used as is; pump rinsed with Product requires mixing; pump rinsed cleanup mineral spirits between with water between applications to avoid clogging applications Cost $16.66/m2 for one application $58.84/m2 for one application Unit definitions: m2=square meters, hr=hour, v=volt, g=gram, kg=kilogram, and cubic centimeters=cm3 Note that the removal rate of Orion' SC will likely depend on the characteristics of the surface being decontaminated as some scraping is required for removal. The Stripcoat TLC Free' can be applied to irregular surfaces and easily removed across the borders of the coupons.
For more information about radiological decontamination of concrete using strippable coatings, view the Strippable Coatings for Radionuclides page.
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