Paper No. 7
Presentation Time: 3:15 PM


PEAKE, R. Thomas, US Environmental Protection Agency, 1200 Pennsylvania Ave, NW, 6608J, Washington, DC 22031,

The Environmental Protection Agency’s (EPA or the Agency) generic radioactive waste disposal standards[1] at 40 CFR 191 are the applicable environmental standards at the Department of Energy’s (DOE) Waste Isolation Pilot Plant (WIPP), the nation’s deep geologic repository for defense transuranic radioactive waste. The standards require DOE to address the situations in which the disposal system is undisturbed by humans or is intruded into by human activity, specifically drilling. This presentation will use WIPP as an example to raise questions about human intrusion if the Agency develops new radioactive waste disposal standards as recommended by the Blue Ribbon Commission (BRC) on America’s Nuclear Future[2].

If undisturbed, performance assessments of the 10,000 year compliance period indicate that the radioactivity at WIPP will remain contained by the Salado Formation, which is primarily halite with some clay and thin inter-bedded anhydrite layers. The only plausible mechanism for release of radioactivity that has been identified is human intrusion by drilling. Thus, the drilling rate is an important factor in calculated potential releases from WIPP, as the expected number of intrusions over 10,000 years is ~5-6.

WIPP is in a sedimentary basin with natural resources and a drilling history, so EPA required DOE to use the past 100 years’ record of drilling as the drilling rate for the 10,000 year compliance period. In contrast, the Yucca Mountain repository, in volcanic tuff, used a deterministic, stylized intrusion scenario. If the Agency develops a new generic standard what criteria should be used in addressing potential future human intrusion? Should there be a difference in assumptions for drilling in different lithologies as in current guidance to 40 CFR 191?

[1] Environmental Radiation Protection Standards For Management And Disposal Of Spent Nuclear Fuel, High-Level And Transuranic Radioactive Wastes, 40 CFR Part 191.

[2] Blue Ribbon Commission on American’s Nuclear Future: Report to the Secretary of Energy, January 2012.