ML22286A229
| ML22286A229 | |
| Person / Time | |
|---|---|
| Issue date: | 10/13/2022 |
| From: | Alex Garmoe NRC/NRR/DRO/IRAB |
| To: | |
| Alex Garmoe, NRR/DRO/IRAB, 415-3814 | |
| References | |
| Download: ML22286A229 (15) | |
Text
SDP Overview Alex Garmoe Senior Reactor Analyst Division of Reactor Oversight Office of Nuclear Reactor Regulation
SDP and NRC Regulatory Framework
- NRC roles include rulemaking, licensing, oversight, and much more
- SDP supports the roles outlined in red (inspection, performance assessment, enforcement)
- Operating reactor performance assessed via Performance Indicators and Inspection results (Findings)
SDP and NRC Regulatory Framework
- Enforcement
- Focused on the severity of non-compliance with requirements (License, CFR, etc.)
- Cited (response required) or Non-Cited (credit CAP) violations
- Severity Level
- Finding
- Focused on safety significance of non-adherence to self-imposed standards
- Significance (color)
- Long-time view that safety is assured through compliance
- ROP brought in more risk-informed approaches that have revealed that its not as simple as compliance = safety
Initial Issue Screening
- Start with a question or issue of concern
- Could ultimately be nothing, could be somethingdont know at this point
- Multiple risk-informed screenings applied
- Very Low Safety Significance Issue Resolution process
- Was failure to meet a requirement or standard within the licensees ability to foresee and correct - is it a Performance Deficiency?
- Minor vs more-than-Minor questions and examples
- If you get here, SDP begins
Qualitative Safety Goals
- Qualitative Safety Goals were included in the Commissions 1986 Safety Goal Policy Statement
- Individuals bear no significant additional risk to life and health
- Societal risks to life and health should be comparable to or less than the risk of generating electricity from viable competing technologies and should not be a significant addition to other societal risks
Quantitative Health Objectives
- Quantitative Health Objectives established as a measure to determine that the Qualitative Safety Goals are met
- Risk of prompt fatalities from reactor accidents should not exceed 0.1% of the sum of prompt fatality risk from other accidents to which members of the public are generally exposed
- Risk of cancer fatalities from reactor operation should not exceed 0.1% of the sum of cancer fatality risks from all other causes
- Risk of prompt fatality to general population of all other accidents to which they are generally exposed was 5E-4 per year
- Applying 0.1% safety goal criteria to the total accident risk 5E-7 per year
- Considering early risk to individuals (IER) within one mile of the plant, QHO is generally met if LERF < 1E-5 per year (NUREG 1860 Appendix D)
- IER calculated as approx. 3E-7 per reactor year when considering worst case internal initiator
- Cancer fatality rate to the general population from all other causes was 2E-3 per year
- Applying 0.1% safety goal criteria to the total cancer risk 2E-6 per year
- Considering latent risk to individuals (ILR) within 10 miles of the plant, QHO is generally met if CDF < 1E-4 per year (NUREG 1860 Appendix D)
- ILR calculated as approximately 4E-7 per reactor year when considering worst case accident sequence
Significance Determination Process
- Determine whether Finding is Green, White, Yellow, or Red
- Deterministic SDPs when quantitative calculations not possible Color CDF LERF Green <1E-6 <1E-7 White 1E-6 to 1E-5 1E-7 to 1E-6 Yellow 1E-5 to 1E-4 1E-6 to 1E-5 Red >1E-4 >1E-5 QHO surrogates
Significance Determination Process 255-day timeline goal 120 days to Exit 45 days to issue IR 90 days to finalize
Detailed Risk Evaluations
- INL provided with licensee risk model information
- Models use generic data supplemented by plant-specific data
- Event trees and fault trees model Initiating Event propagation and failure modes of components and include human error, dependencies, and common cause failures
- Significant uncertainties (aleatory and epistemic)
- No need to spend effort on endless refinement once were confident that the quantitative color is unlikely to change
Guidance Documents
- Issue Screening Guidance: IMC 0612
- SDP Guidance: IMC 0609 Attachment 4: Initial Characterization of Findings App A: At-power SDP App B: Emergency Preparedness App H: Containment Integrity App C: Occupational Radiation Safety App I: Licensed Operator Requal App D: Public Radiation Safety App J: SG Tube Integrity App E: Security App K: Maintenance Risk/Risk Mgmt App F: Fire Protection App L: B.5.b App G: Shutdown Operations App M: Qualitative SDP
- RASP Handbook for detailed risk evaluations
Decisions Along The Way
- Regional-level meeting to approve the performance deficiency, plan for significance evaluation, resources needed, and key messages for licensee
- Establish single management point of contact for communications
- Agency-level meeting to approve the preliminary significance evaluation and enforcement
- Decision-makers from region, HQ technical division, NRR/DRO, OE
- Post Conference Review
- A second SERP to approve the final significance evaluation after consideration of additional information provided by the licensee
Important Concepts
- Confidence in the color matters more than absolute precision
- Significant uncertainties and modeling limitations
- SDP uses the concept of best available information
- Recognition and consideration of uncertainties and sensitivities
- Exposure time, recoverability
- Risk-informed consideration of qualitative factors at the SERP
- Operating reactor assessment process relies upon timely SDP completion
- Level of effort can be beyond that commensurate with the safety significance of issues
Questions