ML23174A056
| ML23174A056 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 06/26/2023 |
| From: | Barber N, Howe A, Schrader K PG&E Co, Pacific Gas & Electric Co, Westinghouse |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| EPID L-2023-LRM-0039 | |
| Download: ML23174A056 (13) | |
Text
Diablo Canyon Power Plant TSTF-505 Revision 2 License Amendment Request Jordan Tyman, PG&E Ken Schrader, PG&E Nathan Barber, PG&E Andrew Howe, Westinghouse June 26, 2023
Purpose and Desired Outcomes 2
Purpose
Desired Outcomes
- Provide details regarding the License Amendment Request (LAR) contents and planned implementation schedule
Introduction Pacific Gas and Electric Company (PG&E) owns and operates Diablo Canyon Power Plant (DCPP) and is committed to safely and reliably operating the states largest clean energy producer on behalf of all Californians.
DCPP had been slated for closure at expiration of current operating licenses (2024 and 2025)
In 2022, the State of California (CA) directed PG&E to take steps to relicense DCPP for an additional 5 years to ensure statewide electrical grid reliability as additional clean energy resources are brought online PG&E intends to apply for renewed licenses from the NRC by December 2023 Proposed License Amendment Request presents a set of risk-informed alternative timelines for resolving low-risk equipment issues when operable, redundant components are available If approved, the change will prevent unnecessary unit shutdowns for low-risk scenarios, and is consistent with safely maintaining DCPP generation and supporting electrical grid reliability in CA 3
Agenda Agenda
- LAR scope and schedule
- Summary of the DCPP probabilistic risk assessment (PRA) model
- Implementation of risk-informed extended completion times (CTs)
- Staff Feedback 4
LAR Scope and Schedule 5
PG&E plans to submit LAR for NRC approved TSTF-505 Revision 2
- Scope of the LAR includes most systems and components contained in TSTF-505 Revision 2; no systems outside scope of TSTF-505 will be included
- TS 3.3.1 Reactor Trip System, TS 3.3.2 Engineered Safeguards Features, and TS 3.3.5 Loss-of-Power Diesel Generator Start changes will not be included Simplifies LAR review scope The TS 3.3.1/3.3.2/3.3.5 systems may be addressed by a future LAR
- Shutdown modes will not be included in the LAR scope (no plant specific shutdown model at this time)
LAR Scope and Schedule 6
Scope TS 3.4.9 - Pressurizer TS 3.4.11 - Pressurizer Power Operated Relief Valves (PORVs)
TS 3.5.2 - ECCS [emergency core cooling systems] - Operating TS 3.6.2 - Containment Air Locks TS 3.6.3 - Containment Isolation Valves TS 3.6.6 - Containment Spray (CS) System, Containment Fan Cooler Units (CFCUs)
TS 3.7.2 - Main Steam Isolation Valves (MSIVs)
TS 3.7.4 - 10% Atmospheric Dump Valves TS 3.7.5 - Auxiliary Feedwater (AFW) System TS 3.7.7 - Vital Component Cooling Water (CCW) System TS 3.7.8 - Auxiliary Saltwater System (ASW)
TS 3.8.1 - AC [alternating current] Sources - Operating TS 3.8.4 - DC [direct current] Sources - Operating TS 3.8.7 - Inverters - Operating TS 3.8.9 - Distribution Systems - Operating
LAR Scope and Schedule 7
Scope
- Additional information is being added to the LAR to address Requests for Additional Information (RAI) received for other plant applications in the last several years Generic RAI information identified in TSTF-505 Revision 2 Additional justification for select Required Actions in TSTF-505 Revision 2 Surrogates for containment isolation, pressurizer heaters Justification for containment spray functions Two Steam Generator Atmospheric Dump Valve Conditions not in scope based on Steam Generator Tube Rupture mitigation requirements
LAR Scope and Schedule 8
Scope
- Non-editorial TSTF-505 variations are included:
Deletion of expired Conditions and Required Actions LCO 3.5.2 (ECCS) and 3.6.6 (Containment Cooling) extended CTs eliminated Plant-Specific Conditions which are not a loss of function are included:
LCO 3.6.6 Condition D for CFCUs - one CS train and at least 2 CFCUs operable LCO 3.7.5 Condition C for AFW - one Motor Driven train and one Turbine Driven steam supply inoperable LCO 3.8.1 Condition F for diesel generator (DG) fuel oil transfer system - separate Condition for DG support system
LAR Scope and Schedule 9
Schedule
Summary of the DCPP PRA model 10 PRA Model
- Current model consists of Internal Events, Internal Flooding, Seismic, and Fire
- PRA Technical Adequacy PRA technical adequacy is consistent with Regulatory Guide (RG) 1.200 Revision 2 Diablo PRA is Capability Category II per ASME/ANS standard and RG 1.200 R2 PRA model is under configuration control with approved procedures for periodic and immediate updating
- PG&E is completing final activities to close remaining open peer review findings/observations (F&Os) prior to LAR submittal
Summary of the DCPP PRA model 11 PRA Model
- Seismic PRA Model RG 1.200, Revision 2 peer reviewed in 2017 Seismic F&Os closed in 2018 Seismic PRA results submitted to NRC as part of 50.54(f) Fukushima Response PG&E maintains a Long-Term Seismic Program (LTSP) for Diablo Canyon comprised of a geosciences team who partners with independent seismic experts to evaluate regional geology and global seismic and tsunami events to ensure the facility remains safe Extensive scientific re-evaluations performed continue to show that DCPP can safely withstand earthquakes, tsunamis and flooding that could potentially occur in the region
Summary of the DCPP PRA model 12 RICT Program Implementation
- Riskman software used for PRA quantification and model development
- EPRI Phoenix will be used for Risk-informed Completion Time (RICT)/Risk Management Action Time calculations
- Software tools and procedures will ensure compliance with requirements
- Risk-informed TS Completion Time processes to be structured similar to South Texas Project (Operations/Work Control centered)
- Organization specific training and communication plan established to appropriately train plant staff
Staff Feedback 13 Staff Feedback