Document: NRC Regulatory Guide
Document ID: b3da4d67-03d8-4f52-b04b-8e76d142c857
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:
on-LWR SSCs as having specific “barrier functions,” in which the SSC serves as a physical or functional barrier to the transport of radionuclides. “Barrier functions” can also include indirect functions, in which an SSC serves to protect one or more other SSCs that may be classified as barriers. The barrier functions are important in the development and assessment of mechanistic source terms that help determine the offsite doses for non-LWR designs for each LBE. Performance criteria for a barrier, or set of barriers taken together, to the transport of radionuclides are discussed in SECY-18-0096, “Functional Containment Performance Criteria for Non-Light-Water- Reactors,” dated September 28, 2018 (Ref. 30), which describes an approach to “functional containment” for non-LWRs that may not rely on traditional containment structures to limit the physical transport and release of radioactive material to the environment. The Commission’s SRM dated December 4, 2018 (Ref. 32), approved the methodology described in SECY-18-0096 for establishing functional containment performance criteria for non-LWRs. A major objective of the process in NEI 18-04 is to establish a systematic approach to assessing and determining appropriate relationships between the needed capabilities and reliabilities for SSCs and the role of those SSCs in mitigating and preventing LBEs. The safety classification of SSCs is made in the context of how the SSCs perform specific safety functions for each LBE in which they play a role in preventing or mitigating an event. The reliability of the SSC serves to prevent the occurrence of the LBE by lowering its frequency of occurrence. If the SSC function is successfully completed within an event DG-1353, Page 17 sequence, the SSC and its associated capabilities have helped to mitigate the consequences of the LBE. The safety classification process and the corresponding special treatments to ensure reliabilities and capabilities of SCCs thereby