Technical Issues Related to Siting Criteria andSeismic Design of ISFSI Using DCSS

摘要

Currently 10 CFR Part 72.102 requires that for Independent Spent Fuel Storage Installations (ISFSIs) for storing spentrnfuel in a dry cask storage system (DCSS), located west of the Rocky Mountain Front (approximately 104 ° west longitude),rnseismicity must be evaluated using deterministic techniques of 10 CFR Part 100, Appendix A, and that the design earthquakern(DE) must be equivalent to a safe shutdown earthquake (SSE) for a nuclear power plant. In June 1998, the Nuclear RegulatoryrnCommission (NRC) approved a Rulemaking Plan to amend Part 72 to allow the new ISFSI licensees to use probabilistic seismicrnhazard analysis methods for evaluating geological and seismological criteria, and to recognize uncertainties in geosciencernparameters.rnThese criteria are proposed to make 10CFR Part 72 regulations conform to the recent changes in 10CFR Part 50rnregulations in nuclear power plants seismic criteria. The Rulemaking Plan also recommended that the new ISFSI licensees bernallowed an option to use a graded approach to seismic design of "Important to Safety" ISFSI structures, systems, andrncomponents (SSCs). This paper examines technical issues related to the proposed 10CFR Part 72 amendments in the RulemakingrnPlan for the seismic siting criteria and design of ISFSIs. The issues examined in the paper include level of site investigationsrnrequired, selection of a design earthquake and associated probability of exceedance, and structural stability/structural integrityrnof casks during a seismic event. The suggested graded approach has been examined in details from the perspectives of the riskrnto public health and safety, and regulatory burden on the stakeholders.