Assessment of hydrologic impact of extending exploratory shafts into the Calico Hills nonwelded tuff unit at Yucca Mountain, Nevada
The US Department of Energy (DOE) is performing analyses to address an objection by the US Nuclear Regulatory Commission to plans in the Consultation Draft of the Site Characterization Plan for direct excavation of the Calico Hills nonwelded (CHn) unit within the repository exploration block at Yucca Mountain, Nevada. The excavation was planned as part of site characterization activities for the potential high-level nuclear waste repository at Yucca Mountain. This characterization activities for the potential high-level nuclear waste repository at Yucca Mountain. This characterization activity has been deferred, pending the results of a risk/benefit analysis of alternative methods for obtaining needed characterization data from CHn unit. The benefits from characterizing the CHn unit are generally related to obtaining information leading to improved confidence in predictions of site performance. The risks are generally associated with potential adverse impacts to site performance that result from excavation or other intrusion into the CHn unit. The purpose of the risk/benefit analysis is to produce a recommendation to the Director, Regulatory and Site Evaluation Division. DOE/Yucca Mountain Site Characterization Project Office for a strategy for characterizing the CHn unit. The recommendation will describe characterization activities that are expected to provide the needed information while limiting adverse impacts to site performance to the extent practical. The risk/benefit analysis was supported with scoping calculations to provide a quantitative evaluation of the impacts associated with different strategies. The working group responsible for the risk/benefit analysis requested that these scoping calculations to be supported with more detailed performance assessments for evaluating impacts of different characterization activities. This report summarizes the results of these performance assessment analyses. 9 refs., 30 figs., 1 tab.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 138139
- Report Number(s):
- PNL-7648; ON: DE91014139; TRN: 91:022009
- Resource Relation:
- Other Information: PBD: Mar 1991
- Country of Publication:
- United States
- Language:
- English
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