FIGURE 5.1 Major milestones in the U.S. approach to a high-level waste geologic repository. In 2002, Nevada vetoed the site recommendation but Congress overrode the veto and authorized DOE to apply for a license to construct the repository at Yucca Mountain (not shown). SOURCE: Williams, 2002.

The USNRC Center for Nuclear Waste Regulatory Analyses also recently published an article on the importance of transparency and traceability in building a safety case for high-level waste repositories (Mohanty and Sagar, 2002).

At each Decision Point, new information is evaluated and used to update the safety case, if necessary. Then this updated safety case together with all relevant information are used to decide, how to proceed (i.e., whether to proceed on the original course or revise the course of action in the reference framework). The committee does not imply that the safety case should be an additional USNRC licensing requirement or that the regulations are inadequate to evaluate repository safety.

Some Decision Points for DOE correspond to the decisions to apply for licenses (i.e., the next license for whatever point the program currently finds itself). DOE is responsible for the license application but the actual decision to issue a license is made by the USNRC.

DOE has so far attempted to describe a safety case for Yucca Mountain in the iterative series of documents called “Repository Safety Strategy.” To date, DOE has issued four versions of the safety strategy for a Yucca Mountain repository. The OECD/NEA and IAEA jointly reviewed revision 3 of DOE’s safety strategy and concluded that:

“[revision 3] is a first commendable attempt at outlining the strategy for achieving safety and for demonstrating compliance with the regulations as well as the basis for confidence in the analyses. The [review team] suggests that the information contained in [revision 3] should be updated and extended, and used as a basis for developing the proposed safety case document for the next phase of the programme” (NEA, 2002, p. 58).



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