Document: NRC Regulatory Guide
Document ID: 46b2c829-ce4c-4a6a-8a01-908725558ffe
Document Type: regulatory_guide
Title: Volcanic Hazards Assessment for Proposed Nuclear Power Reactor Sites + HISTORY - HISTORY 03/2020 – DG-4028-Proposed New Guide
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML2000/ML20007D621.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.26
CFR Part: 
CFR Title: 

Content:
enced in Schuster 1981), and no changes were made to the plant’s operating basis. Trojan was decommissioned in 1992. The NRC also licensed two ISFSIs on or adjacent to the Idaho National Laboratory: TMI-2 (NRC, 1999a) and the Idaho Spent Fuel Facility (NRC, 2004); and the Eagle Rock enrichment facility (NRC, 2010). Each of these installations had to consider the possibility of volcanic lava flows, in addition to ash-fall hazards, that could affect the site. These nuclear material installations represent lower radiological risks than an NPP, which is reflected in the regulatory requirements for siting and the scope of the NRC staff’s safety reviews. The acceptability of volcanic hazards at these sites was demonstrated at the time of licensing by (1) appropriate design and operational bases for ash fall, (2) low likelihood of lava-flow inundation, and (3) confidence in the licensee’s ability to divert potential lava flows. As part of the evaluation of preclosure and postclosure safety for the proposed geologic repository for high-level radioactive waste at Yucca Mountain, Nevada, the NRC staff reviewed the risks associated with volcanic activity affecting the facility. For the preclosure (operational) period, the applicant screened out the volcanic hazards involving direct effects of an eruption within the site DG-4028, Page 4 footprint, based on event probability. Ash fall hazards from distant volcanos were included as credible and their potential for initiating an event sequence evaluated. The applicant determined that the effects of ash fall on the site could be sufficiently mitigated so as not to adversely impact safe and secure operations, and the NRC review found the applicant’s analysis acceptable (NRC, 2015). For the postclosure period, the NRC staff reviewed detailed analyses on the likelihood of a new volcano forming at the proposed repository site, and the potential consequences of that event on the performance of the proposed waste isolation