Document: NRC Regulatory Guide
Document ID: 4d46a966-d280-43da-9b03-8b0abe7b29ce
Document Type: regulatory_guide
Title: Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2120/ML21204A065.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.183
CFR Part: 
CFR Title: 

Content:
onal guidance on combined license applications. 1.6 Final Safety Analysis Report Requirements The regulations in 10 CFR 50.71, “Maintenance of Records, Making of Reports,” include the requirements for updating the facility’s FSAR. Specifically, 10 CFR 50.71(e) requires that the FSAR be updated to include all changes made in the facility or procedures described in the FSAR and all safety analyses and evaluations performed by the licensee in support of approved requests for license amendments or in support of conclusions that changes did not require a license amendment in accordance with 10 CFR 50.59. The analyses required by 10 CFR 50.67 are subject to this requirement. The licensee should update the affected radiological analysis descriptions in the FSAR to reflect the design basis changes to the methodology and input. The analysis descriptions should contain sufficient detail to identify the methodologies used, significant assumptions and inputs, and numeric results. RG 1.70 provides additional guidance. The licensee should remove the descriptions of superseded analyses from the FSAR in the interest of maintaining a clear design basis. 2. Attributes of an Acceptable Accident Source Term The NRC did not set forth an acceptable AST in 10 CFR 50.67. Regulatory Position 3 of this guide identifies an AST that is acceptable to the NRC staff for use in new power reactor applications and operating power reactors. The NRC, its contractors, various national laboratories, peer reviewers, and others expended substantial effort in performing severe accident research and in developing the source terms in Sandia National Laboratories technical report SAND-2011-0128, “Accident Source Terms for Light Water Nuclear Power Plants Using High-Burnup of MOX Fuel,” issued January 2011. However, this RG is not a full endorsement of SAND-2011-0128. Regulatory Position 3 states certain conditions and limitations for its use. However, future research may identify opportunities for