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:
esses 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 uncertainties. Figure 5-4, “Integrated Process for Incorporation and Evaluation of Defense-In- Depth,” in NEI 18-04 depicts the overall process and relationships among LBE selection and analyses, SSC classification, and DID assessments. As part of the DID adequacy evaluation, each LBE is evaluated to confirm that risk targets are met without exclusive reliance on a single element of design, single program, or single DID attribute, and this evaluation is confirmed by the IDP. NEI 18-04 explains that one of the primary motivations of employing DID attributes is to address uncertainties, including those that are reflected in the PRA estimates of frequency and consequence as well as other uncertainties that are not sufficiently characterized for uncertainty quantification nor amenable to sensitivity analyses. NEI 18-4 Section 4.4.5, “Special Treatment Requirements for SSCs,” describes how the plant capability DID attributes include design margins that protect against specific uncertainties. In addition, both the plant capability and programmatic elements of DID incorporate measures to compensate for residual unknowns. DG-1353, Page 19 Table 5-1, “Role of Major Elements of TI-RIPB Framework in Establishing DID Adequacy,” in NEI 18-04 summarizes how a designer uses the NEI 18-04 process to establish DID. Plant Capability Defense in Depth Table 5-2, “Guidelines for Establishing the Adequacy of Overall Plant Capability Defense-in- Depth,” in NEI 18-04 provides overall guidelines and layer-specific guidelines for non-LWR designers to assess plant capability defense in depth. An important qualitative overall guideline is that two or more independent plant design or operational features be provided to meet the layer-specific guidelines for each LBE. Any SSCs