Document: NUREG-0800
Document ID: fe8ec6c2-e960-404c-854f-55c77bde1672
Document Type: srp
Title: NUREG-0800
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2400/ML24005A077.pdf
Revision Date: 2024-05
Chapter: 7
Section ID: 7
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Content:
, “Method for Performing Diversity and Defense-in-Depth Analyses of Reactor Protection Systems,” issued December 1994, summarizes several D3 analyses performed after 1990. It presents a method for analyzing proposed DI&C systems to identify vulnerabilities to common-mode failures and to confirm that the design incorporates adequate D3 strategies to address them. This analysis method postulates common-mode failures that could occur within digital reactor protection systems and determines what portions of a design need additional D3 measures to address such failures. This type of analysis is referred to as a D3 assessment in this document.  NUREG/CR-7007, “Diversity Strategies for Nuclear Power Plant Instrumentation and Control Systems,” issued February 2010, provides diversity strategies to mitigate CCF vulnerabilities in a safety-related system for which a D3 assessment has shown a need for greater diversity. NUREG/CR-7007 identifies and develops a baseline set of diversity criteria that may be appropriate for addressing potential vulnerabilities to CCFs. While this NUREG describes a method for quantitatively assessing the amount of diversity in a system, this method has not been benchmarked and should not be used as the sole basis for justifying adequate diversity.  NUREG-2122, “Glossary of Risk-Related Terms in Support of Risk-Informed Decisionmaking,” issued November 2013, defines terms used in risk-informed activities related to commercial nuclear power plants. 3. Scope The guidance in this BTP is intended for the NRC staff review of D3 assessments to address CCF in DI&C systems.4 This BTP provides review guidance to the I&C technical review staff for evaluating whether an applicant’s proposed DI&C design complies with the functional goals established by (1) the applicable safety analysis, (2) principles of risk-informed decision-making, as applicable, (3) specific regulations, and (4) Commission policy. This BTP is intended to provide review