ML19074A142
| ML19074A142 | |
| Person / Time | |
|---|---|
| Issue date: | 03/19/2019 |
| From: | Don Helton, Tim Reed Special Projects and Process Branch, NRC/NRR/DRA |
| To: | |
| Venkataraman B | |
| References | |
| Download: ML19074A142 (8) | |
Text
Current Thoughts on Resolving Low Safety Significant Issues Office of Nuclear Reactor Regulation Public Meeting March 19, 2019 Tim Reed, Division of Operating Reactor Licensing Don Helton, Division of Risk Assessment
Presentation Purpose Provide current thoughts on potential process enhancements and encourage feedback from stakeholders 2
Problem
- In some cases, there is an inappropriate expenditure of resources and attention on low safety significant issues
- While this is the exception, not the rule, it appears to stem, in large measure, from the complexity, uniqueness, and lack of detail in the licensing basis 3
Nexus of Issues with the Licensing Basis
- The licensing basis (LB), while complex, challenging, and constantly changing, serves it purpose well - but there are exceptions
- Issues arise where the information in the LB is subject to different interpretations
- e.g., old issues that date from the 60s, 70s, early 80s
- When an issue has a clear nexus to the LB it is addressed with the standard approaches (i.e., typically fix it or change the LB)
- When it does not have a clear nexus and it is not clearly in the LB then our current view is that we have discretion and flexibility on how to proceed
- One idea to address the not in situation: if, based on a complete LB record, the issue does not clearly fall within the LB, then pause and assess safety significance
- What about the scenario when the issue is in the LB and it is readily apparent to be low safety significant?
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High safety Not clearly within the Clearly within the existing licensing basis existing licensing basis Evaluate issue to determine regulatory actions with tools such as: Address issue with appropriate tools such as:
- 50.54(f) or generic communication
- Enforcement
- Backfittting
- Order
- If generic - screen as a generic issue
- Consider prompt corrective actions (CAP)
- Use LIC-504 and TIA as applicable Address issue with appropriate tools (i.e., either the Not within the licensing basis + clearly low safety - licensee comes into compliance or changes the EXIT: licensing basis):
- Document decision
- Corrective actions (CAP)
- Make public record
- Change the licensing basis (50.59, LAR, relief, exemptions, etc)
- Assess adequacy of the requirement (i.e.,
rulemaking) 5 Low safety
Thoughts on Low Safety Significance Determination
- The good news is that we have lots of ways of determining significanceunfortunately, we have lots of ways of determining significance
- We should leverage elements of this existing guidance:
- e.g., PRA-distilled screening questions
- e.g., Office Instruction LIC-504
- e.g., Regulatory Guide 1.174
- Some challenges:
- Assessing safety margin and defense-in-depth upstream of determining oversight vs. backfit standing
- Having sufficiently characterized the issue to reasonably judge safety significance
- Handling the nexus between individual plant-specific issues, and emergent issues that apply to multiple plants 6
Need for Clear and Durable Documentation
- Document the issue and its impacts on SSCs, and human performance
- Document associated LB including if there were different perspectives between the licensee and NRC on the LB
- Document the conclusion: Not clearly in the LB
- Document the basis and conclusion that it is low safety significant
- Conclude no further regulatory action is needed and LB can remain as is
- Make the record a public record.
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Thank You 8