ML22053A280
| ML22053A280 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 03/31/2022 |
| From: | True D Nuclear Energy Institute |
| To: | NRC/NRR/DRA/APOB |
| References | |
| Download: ML22053A280 (6) | |
Text
©2022 Nuclear Energy Institute Doug True Sr. Vice President Nuclear Energy Institute March 2022 Risk-informed Decision-making:
Greater Than the Sum of its Parts
©2022 Nuclear Energy Institute 2 Regulations based on deterministic requirements provide the foundation for assuring the safety of nuclear power plants Risk Analysis provides a tool to assess the risk that remains even when regulations are followed The residual risk is never zero Risk Analysis provides an estimate of the residual risks (aka level of safety) associated with the deterministic requirements Risk Analysis can also assess the risk increment of changes to requirements and/or non-compliances Safety vs. Risk
©2022 Nuclear Energy Institute 3 Conceptual Relationship Between Safety & Risk Level of Residual Risk Lots Little No Safety Systems One Safety Train Two Safety Trains Three Safety Trains Four Safety Trains Twenty-seven Safety Trains Example Deterministic Requirement:
Redundancy of Safety Systems
©2022 Nuclear Energy Institute 4 Focus on the safety significant issues:
Allows allocation of resources in the manner that most effectively improves safety Incentivizes licensee focus on issues important to safety Reduces resources applied to issues of low importance Stimulates a net improvement in safety Must account for limitations in risk analysis models (e.g., PRA)
PRA is a tool that must be used appropriately PRA is neither omnipotent, nor omniscient
- Neither is a deterministic approach Risk-informing Improves Safety
©2022 Nuclear Energy Institute 5 PRA results are the product of a model that contains uncertainties
- PRA does not create those uncertainties, it simply illuminates them RG 1.174 outlines an integrated decision-making framework, in part to address uncertainties in PRA results
- PRA is one input
- The elements should not be treated separately Addressing uncertainties:
- Identify uncertainties that are important to the decision
- Consider implications for defense-in-depth &
safety margins
- Example: FLEX for post-Fukushima response Risk-informing Addresses Uncertainty Defense in Depth Safety Margins Current Regulations Small Change in Risk Performance Monitoring Integrated Decision-making Risk-informed Decision-making All safety impacts of the proposed licensing basis changes are evaluated in an integrated manner1 1 - Reg. Guide 1.174
©2022 Nuclear Energy Institute 6 Regulatory Changes:
ATWS Rule Station Blackout Rule Severe accident vents and water addition for BWR Mark I & II Voluntary Changes:
Fire protection pipe failure impacts all divisions of AC/DC power Addition of non-safety feedwater pump Procedural changes to enable novel uses of systems Operator training on important human actions Examples of Risk Insights Improving Safety