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Talking points on Yucca Mountain suitability

The American Nuclear Society is satisfied that the work performed by the Department of Energy, our national laboratories and other government agencies such as the U.S. Geological Survey and the Environmental Protection Agency, is an impressive comprehensive collection of interdisciplinary studies and reports that certainly provides a sufficient basis to conclude that the Yucca Mountain site is suitable for this nation's first geological repository.

We believe the Department of Energy has done a credible interdisciplinary analysis demonstrating the suitability of the Yucca Mountain site for this nation's high-level waste geological repository, creating the basis to proceed to the next step: providing the go-ahead for the Nuclear Regulatory Commission to begin the licensing process.

We have high confidence that Yucca Mountain is a suitable site, and we recommend that Congress provide the go-ahead for the next stage of repository development: the application of a license for repository construction.

We're confident that the DOE has selected and characterized a site that, with appropriate engineering design and operation, can meet with high confidence the regulatory standard for public health and safety.

The pre-closure and post-closure assessments of the Yucca Mountain repository indicate that the combination of site and design features provide public health protection with a considerable margin of safety in meeting the regulatory standard.

There is no "perfect site" for a national repository. But, the purpose of the Nuclear Waste Policy Act was not to direct the Department of Energy to look for the impossible, but to select and characterize a site that, with appropriate engineering design and operation, can meet with high confidence the regulatory standard for public health and safety. Yucca Mountain exceeds those requirements.

We base our recommendation, in part, on the Preliminary Site Suitability Evaluation (PSSE), which shows that the site can meet the post-closure standard, and the analyses indicate that pre-closure health and safety protection are more than adequate.

The PSSE incorporates the most recent data from field and laboratory experiments. It examines many alternative models that have never before been explored. The total system performance assessment (TSPA) is a probabilistic analysis, since its conceptual models are sometimes open to alternative interpretation and its parameters are variable and uncertain. We believe the parameters look reasonable and reasonably conservative. We view the analysis as credible.

The performance assessment of the PSSE is well documented and the documentation has been thoroughly peer reviewed.

The Department of Energy's expanded approach to studying the parameters of the safety and suitability of Yucca Mountain is significant. In the past, DOE just assumed fixed values for many of the parameters. Based on the new contributions of this expanded approach to determining the suitability of Yucca Mountain, ANS has high confidence that the current repository design will meet the applicable radiation protection standards established by the Environmental Protection Agency and the Nuclear Regulatory Commission.

The success of Yucca Mountain is likely because the project:

  • Has demonstrated that the natural features of Yucca Mountain contribute very significantly to public health protection;
  • Has adopted a highly robust engineered barrier system employing multiple, independent barriers to provide long-term confinement of radionuclides;
  • Employs significant conservatism in their assessment of the future health impacts such that these impacts are probably overestimates;
  • Will conduct additional research and monitoring activities over the next several decades to centuries to further bolster confidence in the safety of the repository.

The robustness of the engineered barrier system makes the current Yucca Mountain design less sensitive to geologic parameters and uncertainty.

Large safety margins are found in the preliminary calculations shown in the PSSE. These large margins, coupled with the use of multiple, diverse barriers, makes it quite likely that the assessment will continue to show that the design meets the regulatory requirements when the detailed analysis and design is completed for the license application for Yucca Mountain.

The Yucca Mountain site geology has a number of desirable features for the long-term confinement of radionuclides, such as the zeolite strata that underlie the repository and which have the capability to strongly absorb radionuclides.

We recognize that demonstrating the performance of a repository for more than 10,000 years is a formidable task even for the best scientists and engineers. The approach that the Department of Energy has taken regarding the suitability of Yucca Mountain, and the safety Yucca Mountain will provide as a geological repository, is commendable, reasonable and scientifically sound.

The Department of Energy has chosen a system performance analysis approach with extensive sensitivity analyses of key parameters that affect overall performance. It also has chosen to employ a number of engineered barriers in addition to the natural geological barrier that the Nevada site offers.

The safety of the underground repository during the first 300 years can be assured and as such it is a better place to store spent fuel than at reactor sites for a long period of time.

Reformatted July 12, 2012, 4:12pm CDT.

 
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