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:
pe failures, (2) tsunami or seiche phenomena if a large debris avalanche enters a large body of water, and (3) the possibility of hydrothermal systems or emission of volcanic gases reaching a proposed site. These volcanic phenomena have a broad range of physical, thermal, and chemical characteristics, some of which could create unusual demands on the design and operation of a nuclear reactor. Approach for Volcanic Hazards Assessment In developing a rationale to support the technical positions outlined in Section C, the NRC staff relied heavily on the detailed technical information provided in IAEA-TECDOC-1795, as well as other cited sources of information. This guide focuses on the data and methods needed for an acceptable volcanic hazards assessment and does not present a detailed discussion of the conduct of a probabilistic volcanic hazards assessment. Many of the details on conducting a probabilistic volcanic hazards assessment are provided in existing documents, for example, IAEA SSG-21 and IAEA-TECDOC-1795. NUREG-2213, “Updated Implementation Guidelines for SSHAC Hazard Studies,” and associated references discuss additional details on conducting a risk informed probabilistic assessment of volcanic hazards. Rationale for the Period of Interest General Design Criterion 2 of 10 CFR Part 50, Appendix A, requires consideration of natural phenomena that have been reported historically for the site. The NRC staff has long considered the approximately 200-year historical period for many parts of the United States as inadequate to evaluate the timing and character of infrequent-to-rare but potentially hazardous natural events, such as earthquakes and ground deformation. For geologic phenomena, the NRC staff considers the Quaternary Period (i.e., the last 2.6 million years) as providing sufficient margin to the historical period to accurately evaluate the timing and character of past geological events (e.g., NUREG-0800, Section 2.5.1). The duration of the Quaternary