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:
tor’s SSCs. In practice, the NRC staff notes that, in accordance with IAEA-TECDOC- 1795, volcanic ash-fall hazards may necessitate extending the region of consideration 500–1,000 km (310–620 mi) from a proposed site. If there is no evidence of Quaternary volcanic activity in the appropriate regions, the NRC staff determined that no further analysis of volcanic hazards is warranted. Within the framework of volcanic activity in the United States, the NRC staff determined that an absence of volcanic activity in the last 2.6 million years provides sufficient basis to conclude that hazards from potential volcanic events are not significant in the context of the safe design and operation of a proposed nuclear facility. Risk Informed Regulation The NRC has a longstanding policy on implementing risk-informed regulation through the use of probabilistic risk assessment (PRA) methods in regulatory activities (60 FR 42622). In the current risk-informed, performance-based regulatory framework for NPP licensing, the staff uses insights from PRA analyses to support a range of regulatory decisions. SECY-98-144, “White Paper on Risk-Informed and Performance-based Regulation,” dated March 1, 1999 (NRC 1999b), states the following: A “risk-informed” approach to regulatory decision-making represents a philosophy whereby risk insights are considered together with other factors to establish requirements that better focus licensee and regulatory attention on design and operational issues commensurate with their importance to public health and safety. A “risk-informed” approach enhances the deterministic approach by: (a) Allowing explicit consideration of a broader set of potential challenges to safety, (b) Providing a logical means for prioritizing these challenges based on risk significance, operating experience, and/or engineering judgment, (c) Facilitating consideration of a broader set of resources to defend against these challenges, (d) Explicitly identifying and