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:
ibutes reflect adequate SSC reliability and capability. Figure 5-3, “Framework for Evaluating LBEs Using Layers of Defense Concept Adapted from IAEA,” in NEI 18-04, depicts this element of the DID assessment and lists the success criteria for the successive layers as being (1) prevention of abnormal operations, initiating events and AOOs; (2) return to normal [following a possible AOO] and prevention of DBEs; (3) perform required safety functions [in response to possible DBE] and prevent BDBEs; (4) maintain required safety functions for retention of radioactive material; and (5) prevent adverse public health and safety impacts. The five layers of DID reflected in this element are also used in an overall assessment of DID and summarized in Table 5-2, “Guidelines for Establishing the Adequacy of Overall Plant Capability Defense-In-Depth,” in NEI 18-04. The reactor designer is responsible for ensuring that DID is achieved through the incorporation of DID features and programs in the design phases and, in turn, conducting the evaluation that arrives at the decision of whether adequate DID has been achieved. The process in NEI 18-04 calls for the reactor designer to form an integrated decision panel (IDP), which supports the overall design effort (including development of plant capability and programmatic DID features), conducts the DID adequacy evaluation of that resulting design, and documents the DID baseline. RG 1.201, “Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance,” provides a structure for the operation of an IDP, and NEI 00-04, “10 CFR 50.69 SSC Categorization Guide” (Ref. 31), provides the related industry guidance. The guidance in RG 1.201 and NEI 00-04 addresses the importance of a multi-discipline panel of experts and the role of an IDP in assessing limitations of the supporting PRA, modeling SSCs and human actions, and the need to identify and address