Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
side within 1 mile of the plant boundary, for evaluation purposes, an individual should be assumed to reside 1 mile from the site boundary. An accident may result in the release of a large quantity of radionuclides to the environment that can result in high acute doses to specific organs (e.g., red blood marrow, lungs, lower large intestine) that, in turn, can result in prompt (or early) health effects, fatalities, and injuries. Doses that accumulate during the first week after the accidental release are usually considered when calculating these early health effects. Potential exposure pathways for fatal acute doses typically include inhalation, cloudshine, groundshine, and resuspension inhalation. An early fatality is defined as one that results in death within 1 year of exposure. • Individual latent cancer fatality risk (ILCFR): The risk of a latent cancer fatality to a biologically average individual who resides within 10 miles of the site. Doses from both acute and chronic exposures, including lifetime 50-year committed doses from early-phase exposure, can result in latent cancer fatalities. These doses arise from exposures that occur during both the early phase (within 1 week of the release) from early-phase exposure pathways such as cloudshine, RG 1.247, Page 16 groundshine, inhalation, and resuspension inhalation, and during the long-term phase from long-term exposure pathways such as groundshine and resuspension inhalation. Applicants may define risk surrogates subject to the following considerations: • PRAs of large LWRs use core damage frequency (CDF) and large early release frequency (LERF) as risk surrogates for ILCFR and IEFR, respectively. The definitions of CDF and LERF provided in RG 1.200 may require modification before they can be meaningfully applied to NLWRs, if they can be used at all. • Large release frequency (LRF) is used as a risk metric for 10 CFR Part 52 DC and COL applications for LWRs, as approved in SRM-SECY-90-16,