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:
incompleteness in the geologic record, which might not accurately represent the range of DG-4028, Page 16 future events. As discussed in IAEA-TECDOC-1795, many different types of numerical models are available to simulate the characteristics of potentially hazardous phenomena. However, there is no technical consensus on which numerical models are most appropriate for evaluating a range of potential future phenomena. As a result, a significant part of the PH evaluation should focus on the development of a technical basis to support model selection. The NRC staff considers the SSHAC process an acceptable approach to develop support for model selection and to determine appropriate model parameters. A particular challenge in volcanology is that individual volcanic phenomena can exhibit a wide range of physical, thermal, and chemical characteristics, presenting significant challenges in developing numerical models that accurately represent complex thermo-fluid-dynamical interrelationships. This large range of characteristics is not shared with other natural hazards, such as earthquakes or floods. For many volcanic phenomena, different models can calculate significantly different hazards at sites away from the source volcano. As a result, the volcanic hazards assessment should develop an appropriate technical basis to support the selection of numerical models used in the analysis. Based on guidance presented in NUREG-1804, “Yucca Mountain Review Plan,” issued July 2003 (NRC, 2003), the NRC staff concludes that an acceptable level of volcanic hazards assessment model support consists of the following: • Model parameters are based, to the extent possible, on the characteristics of the volcanic system being evaluated. • Uncertainties and variabilities in these characteristics have a transparent technical basis and are accounted for in the model parameters. • Alternative conceptual models have been considered, and the selection of a preferred model (or models) is