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, the characterization studies should focus on developing sufficient information to determine the maximum credible distance that potentially hazardous volcanic phenomena can travel from the volcanic source. For each potential volcanic source, only those phenomena that are credible for the volcanic source need to be considered (e.g., lava flows would be considered for basaltic scoria cones, but large pyroclastic density currents would not be considered). For each credible volcanic phenomenon, spatial screening criteria generally can be developed from the distance that the most extensive past event traveled from its source. This approach assumes that the character of past events is reasonably constrained and represents an appropriate basis to consider the character of future events. Most importantly, any spatio-temporal trends in the volcanic system need to be sufficiently characterized to provide confidence that the range of past events provides an appropriate maximum bound on the character of future events. Burial and erosion of older deposits is a common problem that should be evaluated in the characterization of any volcanic system. The screening analysis should directly address whether burial or erosion of older deposits creates uncertainties in evaluating the maximum bound on the extent of past events and, if warranted, develop appropriate estimates of uncertainty on the maximum bound to account for burial or erosion processes. In some terranes, a long history of burial and erosion of volcanic deposits might make it impracticable to develop confidence in the maximum extent of past events. Other factors, such as spatio-temporal trends in the volcanic system or insufficient site-characterization information, might also affect the confidence in the maximum extent of past events. In these situations, maximum-extent estimates might be developed from information in appropriate analogue volcanic systems or from general information in, for example, IAEA-TECDOC-1795.