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§63.101--Purpose and nature of findings
(a)(1) Subpart B prescribes the standards for issuance of a license to
receive and possess source, special nuclear, or byproduct material at a
geologic repository operations area at the Yucca Mountain site. In
particular, §63.41(c) requires a finding that the issuance of a license
will not constitute an unreasonable risk to the health and safety of the
public. The purpose of this subpart is to set out the performance
objectives for postclosure performance of the geologic repository and
other criteria that, if satisfied, support a finding of no unreasonable
risk. Postclosure performance objectives for the geologic repository
include a requirement to limit radiological exposures to the reasonably
maximally exposed individual, a requirement to limit releases of
radionuclides to the accessible environment to protect ground water, and a
requirement to limit radiological exposures to the reasonably maximally
exposed individual in the event of human intrusion (see §63.113(b), (c),
and (d), respectively).
(2) Although the postclosure performance objectives specified at
§63.113 are generally stated in unqualified terms, it is not expected that
complete assurance that the requirements will be met can be presented. A
reasonable expectation, on the basis of the record before the Commission,
that the postclosure performance objectives will be met, is the general
standard required. Proof that the geologic repository will conform with
the objectives for postclosure performance is not to be had in the
ordinary sense of the word because of the uncertainties inherent in the
understanding of the evolution of the geologic setting, biosphere, and
engineered barrier system. For such long-term performance, what is
required is reasonable expectation, making allowance for the time period,
hazards, and uncertainties involved, that the outcome will conform with
the objectives for postclosure performance for the geologic repository.
Demonstrating compliance will involve the use of complex predictive models
that are supported by limited data from field and laboratory tests,
site-specific monitoring, and natural analog studies that may be
supplemented with prevalent expert judgment. Compliance demonstrations
should not exclude important parameters from assessments and analyses
simply because they are difficult to precisely quantify to a high degree
of confidence. The performance assessments and analyses should focus upon
the full range of defensible and reasonable parameter distributions rather
than only upon extreme physical situations and parameter values. Further,
in reaching a determination of reasonable expectation, the Commission may
supplement numerical analyses with qualitative judgments including, for
example, consideration of the degree of diversity among the multiple
barriers as a measure of the resiliency of the geologic repository.
(b) Subpart B lists findings that must be made in support of an
authorization to construct a geologic repository operations area at the
Yucca Mountain site. Prior to closure, §63.31(a)(1) requires a finding
that there is reasonable assurance that the types and amounts of
radioactive materials described in the application can be received,
possessed, and stored in a geologic repository operations area of the
design proposed without unreasonable risk to the health and safety of the
public. After permanent closure, §63.31(a)(2) requires the Commission to
consider whether there is a reasonable expectation the site and design
comply with the postclosure performance objectives. Once again, although
the criteria may be written in unqualified terms, the demonstration of
compliance must take uncertainties and gaps in knowledge into account so
that the Commission can make the specified finding with respect to
paragraph (a)(2) of §63.31. |