ML24152A029
| ML24152A029 | |
| Person / Time | |
|---|---|
| Issue date: | 05/30/2024 |
| From: | Lundy Pressley NRC/NRR/DRA/APOB |
| To: | |
| References | |
| Download: ML24152A029 (4) | |
Text
Probabilistic Risk Assessment Configuration Control Examples of Minor Issues Rev. 0 Updated: 5/30/2024 The examples included in this document compliment the memorandum for the Establishment of PRA Configuration Control (CC) Inspection Cross-Regional Panels, in the Agencywide Documents Access and Management System in Accession number ML24081A131, specifically, the Probabilistic Risk Assessment (PRA) CC Issue Screening Guidance contained within. When using these examples ensure that the current revision of this document is being utilized as updates are expected as new examples are encountered and documented and the Cross-Regional Panels gain alignment.
The included examples are PRA CC specific and should be used in conjunction with existing guidance contained within Inspection Manual Chapter (IMC) 0612, Appendix E, Examples of Minor Issues. The examples included here may inform a future update of IMC 0612, App. E, as needed. The purpose of the following examples is to aid in the determination of thresholds for the minor and more-than-minor (MTM) determination and specifically provide temporary guidance to screen PRA CC related performance deficiencies in a reasonably consistent manner. There may be instances where a performance deficiency is judged more than minor notwithstanding the example guidance due to impacts or circumstances not listed in the examples. It should be noted the performance deficiencies written in this guidance are at a generic level and do not include the actual regulatory requirements or self-imposed standards.
Similar examples have been discussed with industry stakeholders during public meetings on PRA CC Significance Determination Process proposals. These examples are not intended to provide finality on any determinations and should only be utilized as reference. The Cross-Regional Panels will determine the appropriate threshold for specific actual issues.
NOTE: Consistent with existing issue screening practice, default to and process any issues in accordance with the highest-level applicable requirement, (e.g. Tech Spec violations for Risk Informed Completion Time (RICT) issues, existing Maintenance Risk Assessment (50.65 (a)(4)), etc.).
Examples:
- 1) Data not updated in accordance with procedures
- 2) Failure to review or model a plant change
- 3) Documentation and/or Justification Issue
- 4) General Model Error
- 5) Model Does Not Reflect As-Operated Plant
- 6) Model Did Not Capture All As-Operated Plant Configurations
- 1) Data not updated in accordance with procedures Performance Deficiency (PD): Licensee failed to perform PRA maintenance or PRA update within the required period of every 2 refueling outages.
IMC 0612 App. E (Examples of Minor Issues): Similar to Ex: 8.a, 1.c (program), 3.a (technical error in calculation), 3.h (non-conservative value used), 3.l (used non-conservative data vs. industry data)
Minor if: The licensee had previously performed and documented a reasonable evaluation justifying an extension beyond the required period. Use of dated information did not adversely affect a cornerstone objective, specifically the condition did not change any risk-informed decisionmaking (RIDM), or other risk-based evaluations. Use of dated information did not significantly reduce any risk margins.
More than minor (MTM) if: There was reasonable doubt that the PD could adversely affect a cornerstone objective prior to recalculation, and/or specifically there was reasonable doubt that a recalculation using updated/correct data could have the potential to adversely change any RIDM in an unfavorable manner or could have resulted in or could result in a non-conservative RIDM outcome. The use of dated information significantly reduced the available risk margins.
- 2) Failure to review or model a plant change PD: Licensee failed to perform a review of (or model) a change to the plant.
IMC 0612 App. E: Similar to Ex: 8.c (failed to scope), 8.d. (relevant info to the risk assessment was incomplete), 1.c (program), 3.a (technical error in calculation),
3.h (non-conservative value used), 3.l (used non-conservative data vs. industry data)
Minor if: The change to the plant did not adversely affect a cornerstone objective. The change to the plant was not required to be included in the PRA in accordance with (IAW) licensee procedures or the PRA Standard.
MTM if: There was reasonable doubt concerning an adverse impact to a cornerstone objective prior to evaluation of the PRA change, and/or specifically; There was reasonable doubt that the missed change or modification could have the potential on the PRA to change a risk evaluation in an unfavorable manner; or The change resulted in or could result in a non-conservative PRA based RIDM outcome; or The change to the plant should have been a required analysis IAW the PRA Standard and required an update to the PRA; or The plant modification and resulting PRA change required an update to the licensees online risk model; or The change was more than a routine PRA Maintenance update and required a PRA Upgrade.
- 3) Documentation and/or Justification Issue
==
Description:==
The licensee failed to provide documentation to adequately demonstrate compliance with maintaining the PRA program. Specifically, the licensee lacked adequate records to support decisions, and/or evaluations of changes, descriptions, and PRA changes, including but not limited to PRA Upgrades and PRA Maintenance, and records of PRA reviews.
PD: Licensee failed to adequately document PRA changes.
IMC 0612 App. E: Similar to 1.a and 1.c (Record Keeping, failed to document and evaluate),
and potentially, 3.a (technical error in calculation), 3.h (non-conservative value used), 3.l (used non-conservative data vs. industry data)
Minor if: The PD did not adversely affect a cornerstone objective, specifically there was reasonable assurance without significant re-evaluation to conclude that the change was insignificant to the PRA and any associated RIDM outcome.
MTM if: The PD adversely affected a cornerstone objective, or there was reasonable doubt prior to an updated evaluation, specifically if the licensee had to perform a reasonably significant effort to duplicate or perform the evaluation. Or the documentation was associated with or supported a PRA Upgrade or was a factor in supporting a conclusion regarding a PRA Upgrade or PRA Maintenance or was documentation associated with and supporting a Peer Review IAW licensee procedures or the PRA Standard.
- 4) General Model Error PD: Licensee failed to accurately model a risk analysis for a risk-informed program.
IMC 0612 App. E: Similar to 1.a and 1.c (Record Keeping, failed to document and evaluate),
and potentially, 3.a (technical error in calculation), 3.h (non-conservative value used).
Minor if: Review determined the model error did not adversely affect a cornerstone objective, and did not adversely impact the licensees RIDM, plans (including risk management actions (RMAs)), or schedules. Or the modeling error (e.g. RICT calculation or supporting risk-informed program evaluations) was conservative in nature and did not require significant effort to evaluate or update.
MTM if: There was reasonable doubt that a cornerstone objective was adversely affected prior to re-evaluation, and/or specifically there was reasonable doubt that the error or omission could have the potential to change a risk evaluation in an unfavorable manner; or resulted in or could result in a non-conservative RIDM outcome; including significant decrease in the available RICT calculated backstop, or the error significantly affected the risk management action time (RMAT) or resulted in the RMAT being passed without knowing. Or the error in the RICT calculation was non-conservative in nature and significantly reduced the available risk margin or required significant effort to evaluate or update.
- 5) Model Does Not Reflect As-Operated Plant
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Description:==
PRA did not accurately reflect the as-operated Plant, specifically, the licensee changed an operating philosophy. The licensee did not assess the impacts of the operational change on the PRA model and therefore the risk assessment tool (RAT) used by operators did not match the actual plant conditions resulting in a non-conservative risk assessment and RICT values.
PD: Licensee did not maintain PRA CC of the model and RAT IAW licensee procedures.
IMC 0612 App. E: Similar 1.c (failed to document and evaluate), and potentially, 3.a (technical error in calculation), 3.h (non-conservative value used).
Minor if: The MS cornerstone objective was not adversely affected since the contribution to reliability or unavailability was insignificant when compared to initial assessments, and the resulting change did not impact the RIDM process and did not require any significant changes to any risk assessments or plans and no higher risk categories were subsequently entered due to any subsequent updates or corrections.
MTM if: There was reasonable doubt concerning an adverse impact to a cornerstone objective prior to the evaluation, and/or specifically there was reasonable doubt that the error could have the potential to or did significantly change a risk evaluation in an unfavorable manner; or resulted in or could result in a non-conservative RIDM outcome; or if the change required entry into a higher risk category, or caused the licensee to take additional compensatory actions than were originally planned.
- 6) Model Did Not Capture All As-Operated Plant Configurations Description/PD: Licensee failed to adequately capture and analyze structure, system, and components (SSCs) and their interrelationships and their response for an event.
Specifically, the licensee did not account for the fact that SSCs were required to be in a specific alignment/position for the given plant configuration being analyzed.
IMC 0612 App. E: Similar 1.c (failed to document and evaluate), and potentially, 3.a (technical error in calculation), 3.h (non-conservative value used).
Minor if: The MS cornerstone objective was not adversely affected since the contribution to reliability or unavailability was insignificant, and the resulting change did not impact the RIDM process and did not require any significant changes to any assessments or plans. No higher risk categories were subsequently entered because of any subsequent updates. A licensee review subsequently determined the error, and associated impacted condition was not required to be analyzed IAW licensee procedures and/or the PRA Standard.
MTM if: There was reasonable doubt concerning an adverse impact to the cornerstone objective prior to evaluation, and/or specifically there was reasonable doubt that the error could have the potential to change a risk evaluation in an unfavorable manner; or resulted or could result in a non-conservative RIDM outcome; or if the error or omission should have been a required analysis/input IAW licensee procedures and/or the PRA Standard, or required an unplanned revision or update to the PRA model.