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:
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 quantifying sources of uncertainty in the analysis (although such analyses do not necessarily reflect all important sources of uncertainty), and (e) Leading to better decision-making by providing a means to test the sensitivity of the results to key assumptions.” Importantly, NRC (SECY-98-144) emphasizes the distinction between the suite of information used to support risk-informed decision making and a risk-based decision framework that relies solely on DG-4028, Page 8 the results of a numerical PRA. For example, as discussed in NRC Office of Nuclear Reactor Regulation Office Instruction LIC-106, “Integrated Risk-Informed Decision-Making for Licensing Reviews,” dated June 10, 2019 (NRC 2019b), risk-informed regulatory decisions typically begin with an understanding of the sensitivity of new information to the results of a facility’s PRA. Once these numerical results are understood, additional qualitative or quantitative information typically is considered to gain additional insights on risk significance. This information can include consideration of available alternatives to a proposed action, degree of uncertainty in new information such as the likelihood of initiating events, or additional qualitative or quantitative investigations. Simply stated, risk-based decision-making would consider only the results of a PRA, whereas a risk-informed decision allows consideration of the PRA results within the broader context of the NRC’s regulatory framework (e.g., NRC, 2018). In the context of a volcanic hazards assessment, the NRC staff notes that risk insights provide a valuable mechanism to assess whether potential volcanic hazards are significant to safety. The approach to developing these insights relies on having an appropriate PRA for the proposed facility and