10 CFR 50.69

Stephen Dinsmore

Senior Reliability and Risk Analyst

Division of Risk Assessment

Office of Nuclear Reactor Regulation

U.S. Nuclear Regulatory Commission

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50.69 Risk-Informed Categorization and Treatment of Structures, Systems and

Components for Nuclear Power Reactors

NESCCNovember 3, 2014

10 CFR 50.69 Overview

• Voluntary alternative rule• Determine safety significance of SSCs after defining the

population of safety-related components• Modify special treatment requirements on SSCs based

on their safety significance• Treatment of low-safety-significance SSCs being

addressed in draft new inspection manual procedure 37060

• Vogtle Submitted Pilot Application August 31, 2012• NRR SER in final review phase

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10 CFR 50.69Four-Box Categorization

10 CFR 50.69Categorization Process

• Minimum of a Level 1, internal events PRA – External events and Shutdown using PRA or using conservative

evaluations– Non-PRA functions and defense-in-depth addressed with questions that

Integrated Decision-making Panel answers

• Active component significance based on – Risk increase caused if component failed (Risk Achievement Worth) and – Nominal contribution to current risk (Fussel-Vessly)– Quantitative sensitivity studies for key uncertainties

• Passive component pressure retaining (rupture) significance based on consequences of failure

• Performance monitoring linked to unreliability increases• Change-in-risk primarily verifies categorization and subsequent

monitoring guideline values

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