U.S. DEPARTMENT OF ENERGY EXPERIENCE IN CREATING AND COMMUNICATING THE CASE FOR THE SAFETY OF A POTENTIAL YUCCA MOUNTAIN REPOSITORY Page: 3 of 13
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W. J. Boyle and A. E. Van Luik
(interpreted to mean all interested parties including the public). However, they do not quite answer all
of the suggestions for improvement provided by the NEA-IAEA review. Making a comprehensive
case for system safety is not a trivial undertaking, and the definition of what a safety case is has
changed since 2002.
3. The safety case as a concept
The IAEA and NEA are jointly promulgating an international document titled Safety Requirements for
Geological Disposal (currently in draft , as cited in an NEA publication ) that defines the safety
case as . . . "an integration of arguments and evidence that describe, quantify and substantiate the
safety, and the level of confidence in the safety, of the geological disposal facility." That publication
has a Figure that explains the safety case concept (Figure 1).
It is the Department's contention that the tiered document structure created to support the site
recommendation process collectively addresses all of the elements of a safety case mentioned in
Figure 1. Is a hierarchy of documents the best way to make a multiple-audience case for safety?
Perhaps it is not. The Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) is
getting international praise for its Project Opalinus Clay Safety Report , a single volume English
language report addressing every aspect of a safety case as defined by IAEA and NEA. However, the
Swiss authorities are receiving three documents from Nagra, two comprehensive technical reports
synthesizing the geological investigations and engineering underlying the above-cited safety
assessment. So, a hierarchy of documents may be necessary even when a comprehensive single-
volume safety argument has been produced.
The Nagra Project Opalinus Clay Safety Report is an exemplary multi-audience, one-volume case for
safety, suitable to the stage of the Swiss repository program (the feasibility-of-siting stage, in this
case). Creating a similar document for the Department's licensing phase would be challenging, but
worthwhile in terms of being able to explain the content of the massive, highly focused license
application to more general (non-specialist but still technically astute) audiences. Producing such a
multi-audience document is under consideration.
CRITICAL OBSERVATIONS ON THE 2002 YUCCA MOUNTAIN SAFETY EVALUATION
LEADS TO A CHALLENGE OF THE REGULATIONS
4. An administrative challenge to the Nuclear Regulatory Commission's regulation
The State of Nevada sought to re-open the regulation to be addressed by the Department for its Yucca
Mountain license application by requesting a formal rulemaking to change the NRC's regulation 
in several ways. The one portion of the request that is of interest here is for the Nuclear Regulatory
Commission to address the NEA-IAEA review observations on the Department's interpretation of the
Nuclear Regulatory Commission's [then draft] regulation  in its conduct of the safety assessment
supporting the site recommendation. The Nuclear Regulatory Commission pointed to the words of the
NEA-IAEA review in supporting its denial of the request .
The NEA-IAEA review suggested in its Sections 2.1 and 2.2 that the Department was too focused on
showing quantitative regulatory compliance with the Nuclear Regulatory Commission's regulation (as
it was in turn reflected in the DOE's own regulation, the 'Siting Guidelines' ). This observation
from the review was overlooking the fact that the regulation also requires demonstration of
understanding in support of the compliance calculation, and that the regulationleft the approach to
showing compliance to the Department. The NEA-IAEA review also suggested the Department ought
to construct a safety case within which to place the regulation-driven safety assessment.
The State of Nevada challenged the Nuclear Regulatory Commission regulation in part to request it
explicitly include a requirement for the Department to do as the NEA-IAEA review suggested: to
construct a comprehensive safety case within which to place its safety evaluation.
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Boyle, W. J. & Luik, A. E. Van. U.S. DEPARTMENT OF ENERGY EXPERIENCE IN CREATING AND COMMUNICATING THE CASE FOR THE SAFETY OF A POTENTIAL YUCCA MOUNTAIN REPOSITORY, report, August 30, 2005; Las Vegas, Nevada. (https://digital.library.unt.edu/ark:/67531/metadc876036/m1/3/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.