Document: NRC Regulatory Guide
Document ID: db0c5d18-2d27-4720-8935-40b402e52f9a
Document Type: regulatory_guide
Title: Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light Water Reactors + HISTORY - HISTORY 05/2019 – Issued DG-1353 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1831/ML18312A242.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.233
CFR Part: 
CFR Title: 

Content:
riate protection of SR SSCs against external hazards. The PRA models used for applications are expected to address the full spectrum of internal events and external hazards that pose challenges to the capabilities of the plant. NEI 18-04 addresses multimodule issues by including guidance that there should be no risk-significant DBEs involving a release from two or more modules, and any BDBEs that involve releases from multiple reactor modules or sources should not be high-consequence BDBEs. NEI 18-04 defines high consequence BDBEs as those with consequences that exceed 10 CFR 50.34 dose criteria. When these objectives related to multimodule issues are achieved, there should be no DBAs with significant releases from two or more modules or radionuclide sources. The guidance also includes an assessment of the following aggregate risk measures: • The total frequency of exceeding a site boundary dose of 100 millirem (mrem) from all LBEs shall not exceed 1/plant-year. This metric is introduced to ensure that the application considers the consequences from the entire range of LBEs, from higher frequency, lower consequences to lower frequency, higher consequences. The value of 100 mrem is from the annual exposure limits in 10 CFR Part 20, “Standards for Protection against Radiation.” • The average individual risk of early fatality within 1 mile of the exclusion area boundary from all LBEs shall not exceed 5×10-7/plant-year to ensure that the plant meets the NRC safety goal quantitative health objective for early fatality risk. • The average individual risk of latent cancer fatalities within 10 miles of the exclusion area boundary from all LBEs shall not exceed 2×10-6/plant-year to ensure that the plant meets the NRC safety goal quantitative health objective for latent cancer fatality risk. Important roles for the PRA in NEI 18-04 include the evaluation of the aggregate or plant-level acceptance criteria and identification of risk-significant LBEs. As shown in