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:
obabilistic methods. Although the NRC staff considers deterministic methods appropriate for initial screening analysis, the NRC approach is to use probabilistic methods for a detailed volcanic hazards assessment. The rationale is that the NRC recognizes probabilistic methods as appropriately capturing an appropriate range of uncertainty in underlying models and data and for producing results that can be evaluated in a risk-informed regulatory framework. (2) IAEA characterizes some hazardous volcanic phenomena as “site exclusion criteria.” The NRC staff does not believe that such exclusionary criteria are consistent with the regulatory approach taken in 10 CFR 100.23, “Geologic and Seismic Siting Criteria,” and are not consistent with a risk-informed regulatory framework. Although the NRC staff recognizes that some volcanic phenomena might create demands that exceed existing design bases, applicants should have the option to develop new design bases if warranted by the risks from volcanic hazards at a proposed site. (3) IAEA has requirements for monitoring volcanoes if there are any volcanic hazards at the site. Although this requirement appears sensible, it does not appear applicable for nuclear reactors in the United States. The IAEA guidelines are applicable to member states around the world, some of which do not have well-funded national programs for volcano monitoring. That condition does not exist for the United States. The U.S. Geological Survey has statutory authority to monitor all potentially active volcanoes in the United States. If there is a perceived gap in monitoring activities at a proposed commercial nuclear reactor, the U.S. Geological Survey will fill that gap. The NRC staff is not aware of any other internationally accepted standards for volcanic hazards assessments that would be relevant to applications for proposed new reactors. The NRC staff is aware of and has staff participants in an American Nuclear Society working group to develop a