Document: NRC Regulatory Guide
Document ID: fa5814c8-b91a-435c-8ee0-5cd4915f8b80
Document Type: regulatory_guide
Title: Performance-Based Emergency Preparedness for Small Modular Reactors, Non-Light-Water Reactors, and Non-Power Production or Utilization Facilities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1808/ML18082A044.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.242
CFR Part: 
CFR Title: 

Content:
dents for the facility, the applicant should apply a risk-informed integrated decision making process.9 The integrated decision making process should consider the defense-in-depth philosophy, maintain sufficient safety margins, and include treatment of uncertainties. In addition, the applicant should justify that the PRA is acceptable for this use, and that it considers internal and external hazards, all modes of operation, and all significant radionuclide sources. The PRA should also include event sequences involving single or multiple modules/units, if applicable, to provide useful risk insights into the source term selection process. The treatment of uncertainties in the PRA should provide a quantification of the impacts of uncertainties using quantitative uncertainty analyses and supported by sensitivity analyses.10 B-3. A technical basis for the screening of any identified release scenarios from quantitative consideration (for example, on the basis of low likelihood or very long accident progression times) would need to be provided. The categorization of accidents, including any category bounds based on frequency including consideration of uncertainty, should be explained. If based on PRA, the use of a low frequency “cut off” should include consideration of uncertainty. Event sequences with frequencies below the “cut off” should be retained in the PRA results and used to confirm that there are no cliff edge effects and that there is adequate defense-in-depth. B-4. The accident radiological source terms should be estimated for the specific facility using accepted analysis methods and codes, such as the MELCOR or MAAP codes. The source term calculations should reflect the performance of the facility under normal and off-normal conditions, include sufficient data on the facility performance, and model the transport of fission products across all barriers and pathways to the environs. 9 RG 1.174, “An Approach for Using Probabilistic Risk Assessment In