ML21307A105
| ML21307A105 | |
| Person / Time | |
|---|---|
| Issue date: | 11/30/2021 |
| From: | Laura Kozak, Antonios Zoulis NRC/NRR/DRA/APOB, Division Reactor Projects III |
| To: | |
| References | |
| Download: ML21307A105 (7) | |
Text
PRA Counterpart Meeting Antonios M. Zoulis, Branch Chief Laura Kozak, Senior Reactor Analyst PRA Oversight Branch, DRA, NRR November 2021
The NRC has a concern that licensees are not evaluating the OPC, and the Open Phase Isolation System (OPIS) for inclusion into their PRA models of record. This has been observed during the Open Phase TI inspections.
While the level of risk from OPC doesnt rise to the level of backfit, it can affect Risk Informed Decisionmaking activities. It also does not reflect the as-built as operated plant.
OPC can particularly affect plant risk during RICT or (a)(4) assessments when plant configurations change. For instance, by removing an offsite power transformer from service for a workweek configuration leaving the plant and its safety buses aligned to a single source of offsite power for the duration of the maintenance window.
Requirements Supporting Review 1-5.3 of the ANS PRA Standard discusses monitoring of PRA inputs and collecting new information for the PRA Configuration Control Program.
The OPC is industry-wide operational experience that affects the PRA. It resulted in plant modifications, procedure changes, and in some cases, operator actions.
This may change the results of the PRA and can affect RIDM in the future.
4 (a)(4)
RICT 50.69 SFCP NFPA-805 Reflect As-built As-Operated plant Requirement
- As-built, as-operated plant NFPA-805
- License condition
- Standard Section 2.4.3.3 SFCP
- License condition
- ASME/ANS Ra-Sa-2009 RICT
- License Condition
- ASME/ANS Standard Ra-Sa-2009 50.69
- ASME/ANS Ra-Sa-2009 a(4)
- NUMARC 93-01, Rev 4F, Section 11.3.3
5 Questions?
Back Up Slide
7 Requirements Supporting Review ASME/ANS Ra-Sa-2009 Section 1-5 PRA Configuration Control (CC)
Key Elements Monitor PRA inputs and collect new information Maintains and Upgrades the PRA consistent with the as-built, as operated plant Ensures cumulative impact of pending changes is considered Maintains CC of computer codes Documentation Input Changes Could affect PRA:
- Design
- Operation
- Maintenance
- Industry-wide operational history
- Changes to inputs or new information shall be evaluated
- Relevant changes to a specific application (i.e.,
RICT, SFCP, 50.69) shall meet pertinent SRs for the application.