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:
, they do not provide specific guidance on the conduct of a volcanic hazards assessment or criteria to evaluate the significance of potential volcanic hazards. IAEA SSG-21, “Volcanic Hazards in Site Evaluation for Nuclear Installations,” issued 2012, does present these important details (IAEA, 2012). The volcanic hazards approach in this guide is generally consistent with IAEA SSG-21. IAEA recognized the value of using a stepwise approach to conducting volcanic hazards assessments that uses available information to conduct a screening evaluation and then additional information to conduct a more detailed hazard analysis. IAEA also endorsed the use of a scaled approach, in which the level of effort in the hazard analysis is proportional to the risk of the nuclear facility being considered. The guidance in SSG-21, however, applies to all nuclear installations, so facility risk was scaled from nuclear reactors (high) to radioactive waste storage facilities (low). Although SSG-21 discusses risk-informed concepts, these discussions are sufficiently generalized to accommodate regulatory frameworks around the world. In this guide, the NRC staff has developed a practicable approach for the application of risk insights in the volcanic hazards assessment, which is consistent with the NRC’s risk-informed, performance-based regulatory framework. While the guide’s approach is consistent with IAEA’s risk-informed concepts, it provides appropriate information so that applicants and staff have clear guidelines on the information needed to support risk-informed decision- making. DG-4028, Page 10 This draft guide does not include three principal concepts developed in SSG-21: (1) For the detailed volcanic hazards assessment, IAEA supported the use of both deterministic and probabilistic 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