ML24308A001
| ML24308A001 | |
| Person / Time | |
|---|---|
| Issue date: | 11/04/2024 |
| From: | Lundy Pressley NRC/NRR/DRA/APOB |
| To: | |
| References | |
| Download: ML24308A001 (5) | |
Text
Enclosure 1 PRA Configuration Control OpESS Panel Template Note: The standard IMC 0611 four-part write-up can be submitted in lieu of this worksheet.
Date of Panel August 8, 2024 Inspection Date July 8-12, 22-26 Licensee Z Exit Date August 20, 2024 Region IV (Arlington, TX)
Report Number IRAB BC (Panel Chair)*
APOB BC* Reinaldo Rodriguez (ABC)
Regional BC* Nick Taylor Regional SRA Cale Young/Rick Deese DRO or DRA SRA/RRA*
Alex Garmoe/John Hanna/Lundy Pressley Lead Inspector Shiattin Makor Regional Enforcement Coordinator*
John Kramer NRR Enforcement Coordinator Brian Hughes Other Staff
- Voting member and required for quorum Performance deficiency (including regulation or standard not met)
The inspectors identified a minor violation of License Condition of 2.C.9, Fire Protection, for the licensees failure to implement and maintain in effect all provisions of the approved riskinformed fire protection programs in accordance with NFPA 805 per 10 CFR 50.48(c).
Specifically, the licensee failed to provide documentation to adequately demonstrate compliance with maintaining the PRA configuration control (CC) program.
Brief summary of the issue During the Z Fire Protection Team Inspection (FPTI), the inspectors interviewed PRA staff, selected inspection samples, and reviewed the licensees processes and procedures to ensure that the PRA CC program was being maintained to support risk-informed decisions.
The licensees approved risk-informed fire protection programs in accordance with NFPA 805 per 10 CFR 50.48(c), modify their fire protection program license condition to include RiskInformed Changes that May Be Made Without Prior NRC Approval, allowing the licensee to change the program using risk assessments that are based on the as-built, as-operated, and maintained plant and reflect the operating experience of the plant.
An acceptable way to demonstrate PRA Technical Adequacy is Regulatory Guide (RG) 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities Revision 2. The purpose of RG 1.200 is, in part, (a) to provide guidance to licensees for use in determining the technical adequacy of the base PRA used in a risk-informed regulatory activity, and (b) to endorse standards and industry peer review guidance. Under Section C, Regulatory Position, it describes one acceptable approach for defining technical adequacy of an acceptable base PRA and provides guidance in four areas that is also found in Z fleet procedure, PRA Maintenance and Update, EN-DC-151, Revision 9.
According to Z Procedure, EN-DC-151, PRA Maintenance and Update, Revision 9, a periodic PRA update should be performed at least once every four years, unless a shorter duration is required by plant-specific applications (e.g., risk-informed completion time (RICT) requires every two cycles). If the licensee is unable to meet this requirement, the PRA update frequency can be extended for up to two years with a site condition report, an evaluation confirming the technical adequacy of the existing model, and the approval of the Manager of Nuclear Analysis.
This requirement is specifically found in Section 7.4, Periodic PRA Model Updates, where Section 2 of this procedure states, a periodic PRA update should be performed at least once every four years, unless a shorter duration is required by plant-specific applications (e.g.,
RICT requires every two cycles). Unless explicitly prohibited by a regulatory requirement, this update frequency can be extended for up to two years, such that the total update period shall NOT exceed 6 years. Any extension to the 4-year frequency shall include:
a) a site condition report documenting the deviation from the nominal update frequency b) a documented evaluation confirming the technical adequacy of the existing model and applicable risk applications for this extended period, and c) The approval of the Manager of Nuclear Analysis It should also be noted that in Section 8.0, Records, Section 1, it states, The PRA Update report shall be a controlled document.
While the inspectors were verifying that the processes and procedures were followed to monitor and update the PRA, it was identified by the licensee after completing the Internal Events PRA update that an extension would be needed for the Fire PRA update. The licensee generated a corporate and site condition report to capture the need to extend the required Fire PRA update but failed to meet the requirements in EN-DC-151 to document the evaluation confirming the technical adequacy of the existing model and applicable risk applications for the extended period and the approval of the Manager of Nuclear Analysis.
Specifically, the corporate tracking condition report documented the need to extend the PRA update with the immediate action to start the Z Fire PRA Update with contractor Y and reviews to start in early 2024. The inspectors noted that both condition reports documented the deviation but were closed without completed actions. The corporate condition report was closed to the required site condition report, and the site failed to document the actions, evaluation, and approval. Since both condition reports were closed without the actions being documented and the licensee failed to create an inspectable record the inspectors requested the evaluation that confirmed the technical adequacy of the existing PRA model and applicable risk applications for the extended period. The licensee informed that since it was only captured in email, after 90 days, it was no longer retrievable and would have to be recreated.
The inspectors also reviewed the model change request (MCR) list that the licensee recreated and provided as the evaluation to confirm the technical adequacy of the existing model and applicable risk applications for the extended period and noted the following gaps,
- 1. Two of the MCRs were graded at a B level which is defined as, important and necessary to address but may be deferred until the next PRA update, according to EN-DC-151. For these MCRs the licensee determined the risk impact was found to be less than conservatisms removed and resulted in a net decrease in risk.
- 2. The list of MCRs did include the High Energy Arc Fault (HEAF) guidance and implementation that would require a focused scope peer review. For the HEAF the licensee did not expect for it to cause a net risk increase and committed to including the MCR for that change.
- 3. Line 36 of the MCR list does not mention that it is a 50.69 license amendment commitment. Specifically, the licensee made a commitment in enclosure 2 of the April 25, 2022, supplement, to update the FPRA fire ignition frequencies by December 2023. Contrary to this commitment, the licensee noted in the list that they would consider updating the fire ignition frequencies in the next model update and considered that the commitment for RICT implementation to update NUREG-2169 was met by utilizing the updates frequencies in the RICT model during RICT implementation.
From this review and discussions with agency PRA subject matter experts, the inspector determined that the conclusions from the provided MCRs were reasonable.
Corrective Actions As a result of this performance deficiency, the licensee generated a condition report to address the lack of a documented evaluation to extend the periodic PRA update. The licensee re-created the risk analysis for the evaluation that confirmed the technical adequacy of the existing PRA model and applicable risk applications for the extended period and demonstrated a net decrease in risk for the Revision 7 model update, which the inspectors confirmed by reviewing the list of model change requests.
The licensee also verified that the PRA model would need an upgrade for the required focus scope peer review for the new high energy arcing fault (HEAF) guide (NUREG-2262) that changes the fire modeling. The licensee noted that this is peripheral, not direct impact. The licensee plans to revise EN-DC-151 to include documentation of the technical adequacy in the condition report so that the information can be easily retrievable.
Minor/more-than-minor (including basis) and proposed significance The inspectors screened this performance deficiency determined the performance deficiency to be minor because it was associated with the equipment performance and procedure quality attributes of the Mitigating Systems cornerstone objective and but did not adversely affect the cornerstone objective to ensure the availability, reliability, and capability of the systems that respond to initiating events to prevent undesirable consequences. Additionally, the inspectors reviewed IMC 0612, Appendix E, Examples of Minor Issues, and determined that the performance deficiency was similar to examples 1.a. and 1.b in section 1, Record Keeping, Cross-cutting aspect and basis Enforcement (if applicable) Violation: Z License Condition 2.C.9 specifies, in part, that the approved risk-informed fire protection programs, The risk assessment approach, methods, and data shall be acceptable to the NRC and shall be appropriate for the nature and scope of the change being evaluated; be based on the as-built, as-operated, and maintained plant; and reflect the operating experience at the plant.
EN-DC-151 establishes a process for maintaining active Z Nuclear PRA internal and external events Level 1 and LERF models, current with the as-built and as-operated plants. The expected use of this procedure will ensure that current industry standards, experience, and technology are incorporated appropriately into the models.
Contrary to the above, from January 15, 2024, through August 20, 2024, the licensee failed to fully implement and maintain in effect all provisions of their approved Fire Protection Program.
Specifically, the licensee failed to provide documentation to adequately demonstrate compliance with maintaining the PRA configuration control (CC) program.
Enforcement Action: This violation has been entered into the licensees corrective action program and is being treated as a minor violation.
Comments This issue was originally proposed as a Green violation. However, additional information was provided by the licensee during the review. The information provided by the licensee generally indicated the gaps were conservative from a risk standpoint.
Decision Reached The cross regional panel unanimously concluded that the issue should be screened as minor.