U. S. Environmental Protection Agency Public Health and Environmental Radiation Protection Standards for Yucca Mountain, Nevada; Proposed Rule 40 CFR Part 197, Federal Register/ Vol. 70 No. 161, August 22, 2005, pp. 49014-49065

Talking Points from Nevada Nuclear Waste Task Force

Why is EPA proposing a new standard?

On July 9, 2004, in response to a legal challenge by the State of Nevada, the Natural Resources Defense Council, and other public interest organizations, the U.S. Court of Appeals for the District of Columbia Circuit vacated portions of the EPA Yucca Mountain Standard that addressed the period of time for which compliance must be demonstrated. The Court ruled that the 10,000 year time period for regulatory compliance was not “based upon and consistent with” the findings and recommendations of the National Academy of Sciences, and remanded that portion of the standard to EPA for revision. The Energy Policy Act of 1992 required that the EPA Yucca Mountain Standard be “based upon and consistent with” the findings and recommendations of the NAS.

The NAS recommended that the compliance assessment extend to the time of the maximum risk of radiation releases whenever they occur, as long as the characteristics of the repository environment do not change significantly. The appropriate time scale, according to NAS, is on the order of 1 million years. Despite the NAS finding that there was no scientific basis to limit the compliance period to 10,000 years, or any other specific time value, the EPA limited the compliance time to 10,000 years. Thus the Court remanded that aspect of the Yucca Mountain safety standard.

 What is EPA Proposing?

1. Retain, unchanged, the radiation exposure limit of 15 millirems per year to the Reasonably Maximally Exposed Individual for a period of 10,000 years.
2. For the time period between 10,000 and one million years, set the radiation exposure limit of 350 millirems per year to the Reasonably Maximally Exposed Individual.

3. Retain, for a period of 10,000 years, the Groundwater Protection Standard that limits exposure to an individual from drinking ground water to 4 millirems per year. For the period after 10,000 years, there is no groundwater protection standard. The 350 millirem per year dose limit from all sources to the Reasonably Maximally Exposed Individual is the sole individual protection standard. 

 Talking Points:

 EPA believes that uncertainties in calculating expected doses after 10,000 years grow to the point of making such calculations meaningless, therefore they “believe rising uncertainties justify adopting a different (higher) dose level” for a compliance limit after 10,000 years. Page 49032.

 First, as the NAS found, there is no scientific basis for a 10,000 year limit, or any other time period for compliance, and second, there is no stated basis for why the standard should be higher because of uncertainty, rather than the same or lower to be equally or more protective in the face of uncertainty.

 EPA believes the higher dose standard of 350 millirems per year is reasonable and protective because when added to the presumed background radiation level in Amargosa Valley of 350 millirems per year, the total, 700 millirems per year, is comparable to the average background radiation level experienced by people currently living in Denver, Colorado.

 There is no precedent in U.S. or international radiation regulation for setting human health standards comparable to background levels. Background levels, globally, are highly variable, and as used by EPA include respirable indoor radon, which, in the case of EPA’s Denver number represents 87% of the background dose. The indoor radon dose can be reduced and controlled. The inhalation dose from radon is not comparable, from a health standpoint, to the largely ingestion dose (primarily drinking water and food) that the Reasonably Maximally Exposed Individual would experience in Amargosa Valley.

 For countries that have set radiation standards for repositories, most have a limit of 10 millirems per year, and one (Switzerland) explicitly extends the compliance period to the time of expected maximum risk. The U.S. Nuclear Regulatory Commission health standard for low-level radioactive waste disposal sites is 25 millirems per year, as is the health standard for high-level radioactive waste storage facilities such as the proposed Private Fuel Storage in Utah.

 The International Atomic Energy Agency, in which the U.S. participates, includes in its safety principles: “the degree of isolation of high-level radioactive waste shall be such so there are no predictable future risks to human health or effects on the environment that would not be acceptable today.”  No current radiation protection regulation in the U.S., or internationally, makes acceptable a dose of 350 millirems per year to individuals of the public. It is not EPA’s charge to assure repository compliance  today by setting an extraordinarily high dose limit for future generations.

 EPA believes that its proposed standard is extraordinarily protective of human health because it extends to an unprecedented one million-year time period.

 The NAS report found that “compliance assessment is feasible for most physical and geologic aspects of repository performance on the time scale of the long term stability of the fundamental geologic regime - a time scale that is on the order of one million years at Yucca Mountain - and that at least some potentially important exposures might not occur until after several hundred thousand years.” This is the NAS’s basis for recommending that the time of compliance extend to the time that the expected greatest risk occurs.  

The Yucca Mountain repository design and performance assessment rely on the use of metal containers to isolate the waste underground for many thousands of years. DOE expects that none of the containers will fail in the first 10,000 years, making EPA’s limit of 15 millirems per year for 10,000 years of no consequence.  After 10,000 years DOE expects a significant number of container failures due to corrosion by about 80,000 years, leading eventually to a time of maximum dose to the Reasonably Maximally Exposed Individual. But the time of maximum dose is almost entirely dependent on the time and rate of container failures, which is the greatest single source of uncertainty in the Yucca Mountain performance assessment. If there were no containers enclosing the waste, the site characteristics indicate that maximum dose could occur well within 10,000 years because once waste is released, the geology of the site is such that the waste can be transported by underground water to the accessible environment in as little as a few hundred to a few thousand years. Some container failure scenarios could result in peak doses at around 10,000 years, when if the time were 10,001 years, the unprecedented dose limit proposed would be 350 millirems per year.

 The time of peak dose is only an indicator of  the time when significant numbers of containers fail. The one million year compliance period is simply the period during which NAS  thought it is feasible to predict the range of site characteristics that would affect transport of the waste to the environment.

 EPA is charged with protection of public health and safety. The real issue is not when maximum dose might occur – but: What is a safe dose limit?

 EPA believes that a ground water protection standard is not required after 10,000 years because the Court did not specifically require it.

The Court did uphold including the ground water protection standard in the Rule as being consistent with Agency ground water protection policy, which does not specify any time limit for protection of safe drinking water. The aquifer beneath Yucca Mountain provides drinking water and agricultural- use water to the people of Amargosa Valley where the Reasonably Maximally Exposed Individual would reside. There is no scientific or policy basis to end ground water protection after 10,000 years.