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:
gn. The calculations should be as realistic as possible so that the values and limitations of any mechanism or barrier are not obscured. • The events considered in the analyses to develop the set of source terms for each design are selected to bound severe accidents and design-dependent uncertainties. • The design-specific source terms for each accident category would constitute one component for evaluating the acceptability of the design. The above conditions remain valid for the assessment of mechanistic source terms used to estimate radiological consequences within the analyses of event sequences as described in NEI 18-04. Although NEI 18-04 does not address the topic in detail, the development of mechanistic source terms for designs and specific event families is another element of an integrated, risk-informed, performance-based approach to designing and licensing non-LWRs. The NRC staff expects applications or related reports to describe the mechanistic source terms, including the retention of radionuclides by barriers and the transport of radionuclides for all barriers and pathways to the environs. Where applicable, a facility may have multiple mechanistic source terms and specific event sequences to address various systems that contain significant inventories of radioactive material. Informing the Content of Applications NEI 18-04 provides useful guidance for non-LWR reactor designers and the NRC staff in the key areas of selecting and evaluating LBEs, identifying safety functions and classifying SSCs, selecting special treatment requirements, identifying appropriate programmatic controls, and assessing DID. Taken together, these activities provide essential insights for the reactor design process, define needed SSC capabilities and programmatic controls, and support documenting the safety arguments supporting applications for licenses, certifications, or approvals. NEI 18-04 thereby defines a methodology for non- LWR applicants to identify and provide