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:
rization of volcanic hazards other than ash fall, consistent with NUREG-0800, Section 2.5.1. Ash-fall hazards can occur from volcanoes located farther than 320 km (200 mi) from a site. For the purpose of the initial evaluation of potential hazards from volcanic ash falls, the region of interest for the volcanic hazards assessment should extend a sufficient distance beyond 320 km (200 mi) to encompass those Quaternary volcanic systems that have the potential to affect the design or operation of the proposed reactor. If there is evidence of Quaternary volcanism in the regions of interest, a conceptual model of tectono-magmatic processes should be developed early in the characterization stage of the volcanic hazards assessment. The conceptual model, or series of alternative models, should develop an understanding of the geological sources and controls of Quaternary volcanism in the systems of interest. The goal of the tectono-magmatic model is to determine how the past patterns of Quaternary volcanism should be projected to estimates of future activity. The hazard analysis can screen out volcanic systems that are not consistent with the tectono-magmatic model. This screening, however, is dependent on establishing sufficient confidence in the underlying technical basis showing that future volcanism is not a credible event. For example, if the locus of volcanic activity in the region has shifted through time because of tectonic processes, a rationale might be developed to exclude older Quaternary volcanic centers from the analysis (e.g., Yogodzinski et al., 1996). The hazards analysis should characterize volcanic systems that are consistent with the tectono-magmatic model. Insights from the tectono-magmatic model should be used to guide subsequent data collection and model development. For example, volcanic systems that show potential relationships between regional tectonic stresses and vent locations would likely characterize a larger tectonic province than a system