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:
el 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 that shows strong influences of only local tectonic stresses (e.g., Sherrod et al., 1997). Quaternary volcanoes that are consistent with the tectono-magmatic models should be characterized sufficiently to support each stage of the hazard analysis, as needed. Determination of sufficiency of available information is a key part of the SSHAC process through which the center, body, and range of technically defensible interpretations of data, models, and methods are evaluated (NUREG- 2213). For some volcanic hazards assessment studies, characterization might proceed in stages, commensurate with the level of information required to support the next stage of the analysis. For example, large uncertainties about the timing of past events might be acceptable during the initial screening analyses but might produce unacceptable results if propagated into a probabilistic assessment of eruption likelihood. Thus, the need to reduce that magnitude of uncertainty through radiometric dating might be deferred until after a probabilistic hazard assessment is conducted and the risk significance of that hazard is assessed. Volcanic systems tend to be long lived, with some loci of activity persisting throughout the Quaternary Period. In addition, volcanic systems generally are complex topographic features with both constructive and destructive processes operating at relatively high rates through time. Consequently, the DG-4028, Page 13 record of past events will be incompletely preserved at the present-day surface. An acceptable characterization program will need to consider the potential for buried or eroded deposits in the region of interest and evaluate the uncertainties that such buried or eroded deposits represent in the appropriate hazard analyses (e.g., Wang and Bebbington, 2012).