ML19080A041
| ML19080A041 | |
| Person / Time | |
|---|---|
| Issue date: | 03/20/2019 |
| From: | Sunil Weerakkody NRC/NRR/DRA |
| To: | |
| References | |
| Download: ML19080A041 (2) | |
Text
Proposal to Address Treatment of PRA Methods for TSTF-505 Proposal in September 27, 2017 TSTF to NRC Letter:
- e. A RICT must be calculated using the PRA and non-PRA methods approved by the NRC, including [list specific PRA and non-PRA methods (e.g., Fire PRA and Seismic Margins Analysis) used to assess risk]. Changes to these PRA and non-PRA methods require prior NRC approval. The PRA maintenance and upgrade process will validate that changes to the PRA models used in the RICT program follow the guidance in Appendix 1-A of ASME/ANS RA-Sa-2009, "Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications," and will be documented for NRC inspection.
Change to Approaches A RICT must be calculated using the following PRA and non-PRA methods approved by the NRC, including [list specific PRA and non-PRA methods used for fire and seismic analysis (e.g., Fire PRA and Seismic Margins Analysis)]. Changes to these PRA and non-PRA methods require prior NRC approval.
Reference to PRA Standard The PRA maintenance and upgrade process will validate that other changes to the PRA models used in the RICT program follow the guidance in Appendix 1-A of ASME/ANS RA-Sa-2009, "Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications."
Notification of PRA Upgrade Propose the following, which is consistent with other TS reporting requirements, such as the Post Accident Monitoring Report and the Steam Generator Tube Inspection Report.
- f. A report shall be submitted to the licensees NRC Headquarters Project Manager and Resident Inspectors, in accordance with Specification [5.6.X] following each PRA upgrade and associated peer review, and at least 30 days prior to using the upgraded PRA to calculate a RICT.
To ensure the reporting requirement is not overlooked, it is separated into a separate paragraph.
It's not necessary or consistent with other TS reporting requirements to state that the report is sent to the NRC or that it's being sent "by letter."
To be consistent with similar TS requirements, a reporting requirement is added to TS Section 5.6, "Reports":
A report shall be submitted to the licensees NRC Headquarters Project Manager and Resident Inspectors, in accordance with Specification [5.6.X] following each PRA upgrade and associated peer review, and at least 30 days prior to using the upgraded PRA to calculate a RICT. The report shall describe the scope of the upgrade, including (1) the PRA models upgraded, (2) the peer review and finding closure reports available to the NRC for oversight and inspection activities, (3) the number of, and characterization of, Page 1
Proposal to Address Treatment of PRA Methods for TSTF-505 the open findings remaining in the upgraded model, and (4) identification of any RICTs of less than 30 days calculated to change by more than 50% for the zero-maintenance configuration.
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Proposal to Address Treatment of PRA Methods for TSTF-505 5.5.18 Risk Informed Completion Time Program This program provides controls to calculate a Risk Informed Completion Time (RICT) and must be implemented in accordance with NEI 06-09-A, Revision 0, "Risk-Managed Technical Specifications (RMTS) Guidelines." The program shall include the following:
- a. The RICT may not exceed 30 days;
REVIEWER'S NOTE ----------------------------------
The Risk Informed Completion Time is only applicable in MODES supported by the Licensees PRA. Licensee's applying the RICT Program to MODES other than Modes 1 and 2 must demonstrate that they have the capability to calculate a RICT in those MODES or that the risk indicated by their MODE 1 and 2 PRA model is bounding with respect to the lower MODE conditions.
- b. A RICT may only be utilized in MODE 1, 2 [, and 3, and MODE 4 while relying on steam generators for heat removal];
- c. When a RICT is being used, any change to the plant configuration, as defined in NEI 06-09-A, Appendix A, must be considered for the effect on the RICT.
- 1. For planned changes, the revised RICT must be determined prior to implementation of the change in configuration.
- 2. For emergent conditions, the revised RICT must be determined within the time limits of the Required Action Completion Time (i.e., not the RICT) or 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the plant configuration change, whichever is less.
- 3. Revising the RICT is not required if the plant configuration change would lower plant risk and would result in a longer RICT.
- d. If the extent of condition evaluation for inoperable structures, systems, or components (SSCs) is not complete prior to exceeding the Completion Time, the RICT shall account for the increased possibility of common cause failure (CCF) by either:
- 2. Risk Management Actions (RMAs) not already credited in the RICT calculation shall be implemented that support redundant or diverse SSCs that perform the function(s) of the inoperable SSCs, and, if Page 3
Proposal to Address Treatment of PRA Methods for TSTF-505 practicable, reduce the frequency of initiating events that challenge the function(s) performed by the inoperable SSCs.
- e. A RICT must be calculated using the following PRA and non-PRA methods approved by the NRC, including [list specific PRA and non-PRA methods used for fire and seismic analysis (e.g., Fire PRA and Seismic Margins Analysis)]. Changes to these PRA and non-PRA methods require prior NRC approval. The PRA maintenance and upgrade process will validate that other changes to the PRA models used in the RICT program, including changes involving newly-developed methods, follow the guidance in Appendix 1-A of ASME/ANS RA-Sa-2009, "Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications.," Regulatory Guide 1.200, Revision 2, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities, and NEI 17-07, Revision 1X, Performance of PRA Peer Reviews Using the ASME/ANS PRA Standard.
- f. A report shall be submitted to the licensees NRC Headquarters Project Manager and Resident Inspectors, as well as the Director of the NRR Division of Risk Assessment, in accordance with Specification [5.6.X].
following each PRA upgrade and associated peer review, and at least 30 days prior to using the upgraded PRA to calculate a RICT.
[5.6.X Probabilistic Risk Assessment (PRA) Upgrade Report A report shall be submitted to the licensees NRC Headquarters Project Manager and Resident Inspectors, as well as the Director of the NRR Division of Risk Assessment, following each PRA upgrade involving a newly-developed PRA method and the associated peer review, and at least 360 days prior to using the upgraded PRA to calculate a Risk Informed Completion Time in accordance with Specification [5.5.18]. The report shall describe the scope of the upgrade, including (1) the PRA models upgraded and newly developed methods used, (2) the peer review and finding closure reports available to the NRC for oversight and inspection activities, (3) the number of, and characterization of, the open findings remaining in the upgraded model, and (4) identification of any RICTs of less than 30 days calculated to change by more than 50% for the zero-maintenance configuration.]
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