ML24087A152
| ML24087A152 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 03/18/2024 |
| From: | Grady C Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-115 | |
| Download: ML24087A152 (1) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 ANNUAL CHANGES, TESTS, AND EXPERIMENTS REPORT REGULATORY COMMITMENT EVALUATION REPORT 10 CFR 50.59(d)(2)
Serial No.24-115 SPS/MMT RO Docket Nos.
50-280 50-281 License Nos. DPR-32 DPR-37 Virginia Electric and Power Company hereby submits the annual report of Changes, Tests, and Experiments pursuant to 10 CFR 50.59(d)(2) implemented at Surry Power Station. The Attachment provides the descriptions and summaries of the Regulatory Evaluations and the Regulatory Commitment Change Evaluations completed in 2023.
Should you have any questions regarding this report, please contact Michael M. True, Jr. at (757) 365-2446.
Verytrc::izi ~l'il/')c\\
Cathy Grady Director Nuclear Safety & Licensing Surry Power Station Attachment Commitments made in this letter: None cc:
.United States Nuclear Regulatory Commission, Region II Marquis One Tower, Suite 1200 245 Peachtree Center Avenue, NE Atlanta, Georgia 30303--1257 NRC Senior Resident Inspector Surry Power Station March 18, 2024 Surry Units 1 & 2 Serial No.24-115 10 CFR 50.59 Annual Report Page 1 of 6 10 CFR 50.59 Changes, Tests, and Experiments, and Regulatory Commitment Evaluations for 2023 SU-22-00152/Rev. 0 Regulatory Evaluation 03/22/2023
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Description:==
The proposed activity is installing an interposing relay in series with an "a" contact associated with the upstream feeder breakers (15E1 and 15F1) for the Unit 2 Emergency Bus (4160V) supply breakers (25H8 and 25J8) closing circuits. A new "a" contact from the interposing relay will then be wired in place of the relocated "a" contact from the upstream feeder breaker ( 15E 1 and 15F1) for breakers 25H8 and 25J8. A new "b" contact from the interposing relay will be wired in place of the relocated "b" contact from the upstream feeder breaker (15E1 and 15F1) for breakers 25H8 and 25J8. The existing "b" contact from 15E1 and 15F1 for 25H8 and 25J8 will be spared in place.
For 25H8, in addition to the "a" contact from 15E1 closing circuit being relocated to the interposing relay, the contacts in the closing circuit associated with 86PW and 86R lockout relays are also moved such that all three contacts will be required to be closed to energize the interposing relay.
Additionally, for 25H8, a second interposing relay will be installed in conjunction with the trip circuit contacts for both 86PW and 86R Bus Lockout Relays. A new "a" contact from the interposing relay will then be rewired in place of the relocated "a" contact for both the 86PW and 86R contacts in the trip circuit for 25H8.
The interposing relays will be seismically mounted inside of the respective Emergency Bus supply breaker cabinet along with associated wiring. A separate pair of fuses from the same DC source as the respective Emergency Bus Supply Breaker will provide power to the interposing relay for 25J8. A single set of fuses will power both interposing relays for 25H8.
This is being done to resolve an Appendix R fire concern identified in CR 1180502, which identified potential damage to the control circuit wiring that provides the interlocks from the 15E1 and 15F1 supply breakers to the control circuits for Unit 2 Emergency Bus Normal Supply Breakers 25H8 and 25J8, respectively.
Summary:
The proposed activity is installing interposing relays in the 25H8 and 25J8 Emergency Bus Normal Supply Breakers to address Appendix R concerns with wiring going to the 15E 1 and 15F1 Transfer Bus Supply Breakers along with wiring that runs from 25H8 to the Reserve Station Service Transformer Relay Panel. The interposing relay in the closing circuit will energize and deenergize in conjunction with the position of 15E1 and 15F1 to provide the interlock between 25J8/15F1 and 25H8/15E1 breakers. The relay in 25H8 trip circuit will energize and de-energize depending on the condition of 86PW and 86R bus lockout relays.
Serial No.24-115 10 CFR 50.59 Annual Report Page 2 of 6 An evaluation is required due to the potential adverse effect of having an additional electrical component within the breaker operating scheme for 25H8 and 25J8 Emergency Bus Normal Supply Breakers.
Does the activity result in more than a minimal increase in the frequency of occurrence of an accident previous evaluated in the SAR? - No. The modification installs two relays in 25H8 and one relay in 25J8 Emergency Bus Normal Supply Breakers. There is no impact to any accident frequency.
Does the activity result in more than a minimal increase in the likelihood of occurrence of a malfunction of a SSC important to safety previously evaluated in the SAR? - No. The interposing relay in the closing circuit energizes and deenergizes in conjunction with the position of 15E1 /15F1 to provide the interlock between 15E1/25H8 and 15F1/25J8. In the event of a failure, the Emergency Bus Normal Supply Breaker would open, resulting in the EOG supplying the Emergency Bus. An additional relay is installed in 25H8 trip circuit for 86PW and 86R lockout relays. In the event of failure, either 25J8 or 25H8 would trip or there would be a loss of the redundant 86PW and 86R lockout trips for 25H8 breaker. This condition is bounded in the accident analysis.
Does the activity result in more than a minimal increase in the consequences of an accident previously evaluated in the SAR? - No. A failure of the fuses or relay could result in the Emergency Bus Normal Supply Breaker opening and the EOG supplying the Emergency Bus.
This condition is bounded by the assumption in the accident analysis of a complete loss of offsite power.
Does the activity result in more than a minimal increase in the consequences of a malfunction of a SSC important to safety previously evaluated in the SAR. No. In the event of a relay failure, the Emergency Bus Supply Breaker would open and the EOG would supply the Emergency Bus.
As this condition is bounded by the accident analysis, there is no increase in consequences of a malfunction.
Does the activity create a possibility for an accident of a different type than any previously evaluated in the SAR? No. The installation of a relay in the Emergency Bus Normal Supply Breaker does not introduce any new accident type.
Does the activity create a possibility for a malfunction of a SSC important to safety with a different result than any previously evaluated in the SAR? No. A failure of the relay or contacts to operate has three possible results. One is the Emergency Bus Supply Breaker opening and the EOG powering the bus. This is bounded by the assumptions of a loss of offsite power in the accident analysis. The second possibility is that the breaker closing interlock between 15E1/25H8 and 15F1/25J8 would cease to function. The closing of 25J8 and 25H8 is governed by operating procedures that require synchronizing across and closing the Emergency Bus Supply Breaker prior to manually closing. The third is the loss of a redundant trips for 25H8. There are multiple other trips that are available to provide this function.
Does the activity result in a design basis limit for a fission product barrier as described in the SAR being exceeded or altered? No. The worst-case relay failure would result in the Emergency Bus Supply Breaker opening and the EOG would supply the Emergency Bus. As this condition
Serial No.24-115 10 CFR 50.59 Annual Report Page 3 of 6 is bounded by the accident analysis, a fission product barrier limit is neither altered nor exceeded.
Does the activity result in departure from a method of evaluation described in the SAR used in establishing the design bases or in the safety analysis? No. There is no change to the method of evaluation.
ETE-NAF-2023-0006/Rev. 0 Regulatory Evaluation 03/29/2023
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Description:==
The activity being reviewed is the implementation of the PAD5 code-based method (WCAP-17642-P-A) and affected transient analyses into the Surry Unit 2 licensing basis, as documented in ETE-NAF-2023-0006.
The 10 CFR 50.59 applicability review identified the following changes were subject to a 10 CFR 50.59 screen:
- 1. Method Changes:
including the update to the fuel melt limit assumed within the safety analyses.
- 2. Safety Analysis Changes:
- a. Reanalysis of the Control Rod Ejection Accident: The new control rod ejection analysis was performed to assess the impact of different fuel property inputs from PADS on the transient analysis, as well as assess against the updated fuel melt limit applicable to PADS.
The activities listed above also require updates to the SPS UFSAR.
Of the changes determined to require a screen, all changes screened in for evaluation.
Summary:
The primary purpose of the changes being implemented as part of this 10 CFR 50.59 Evaluation is to capture the impact of using PADS to generate fuel-related inputs on affected analyses for Surry Power Station (SPS) Unit 2. Implementation of PADS at Surry Power Station Unit 1 was previously completed in support of the most recent refueling outage in the fall of 2022. This activity directly addresses the phenomena of thermal conductivity degradation (TCD).
Previously, the NRC released Information Notice 2009-23, which requested licensees to review the information notice and determine if TCD had been adequately addressed at each operating facility. To address this concern, Westinghouse developed an improved fuel thermal model and fuel performance evaluation code and methodology documented in WCAP-17642-P-A, Revision 1, which has been approved by the NRC. The methodology and associated code, known as PADS, incorporates several improved fuel thermal performance models, including consideration of TCD with increasing burnup, compared to the current PAD 4.0 code and method described in the Surry Power Station Updated Final Safety Analysis Report (UFSAR).
This 10 CFR 50.59 activity implements the PADS code and method into Chapter 3 of the SPS UFSAR and implements an updated Chapter 14 safety analysis to account for the use of PADS
Serial No.24-115 10 CFR 50.59 Annual Report Page 4 of 6 inputs for SPS Unit 2. An Evaluation is required because methods of analysis are changed from those currently described in the SPS UFSAR and a Chapter 14 safety analysis was re-run to address the use of PAD5 inputs and to ensure the respective acceptance criteria continue to be met such that their individual design functions remain unaffected. Because of this methodology change and potentially affected SAR-described design functions, which are considered adverse changes under 10 CFR 50.59, an Evaluation is required to assess each of the eight Evaluation criteria. The method change is solely evaluated under Criterion 8 consistent with NEI 96-07, Revision 1, Section 4.3.8, while the reanalyzed safety analysis is evaluated under Criteria 1 through 7.
The reanalyzed safety analysis continues to meet the applicable acceptance criteria ensuring the design functions remain unaffected. Because the 50.59 treatment of the reanalysis under Criteria 1 - 7 only involved input changes and all acceptance criteria continue to be met, there was no impact on frequency of occurrence of accidents or SSC malfunctions, no increase in radiological consequences of the accidents or via SSC malfunctions, and no potential for different accidents directly or via SSC malfunctions. The fuel melt limit, which is considered a DBLFPB, is altered as an acceptance criterion for safety analyses for which fuel melt is evaluated; however, the fuel melt limit is included in the approved WCAP-17642-P-A, Revision 1 topical, which is implemented en toto under Question 8 of the Evaluation.
Finally, as the method of analysis for this event is unchanged, Criterion 8 of the Evaluation is not applicable.
As previously indicated, WCAP-17642-P-A, Revision 1 (Westinghouse's PAD5 model and code) is being implemented as the new fuel performance evaluation methodology at SPS Unit 2 which includes incorporation into the safety analyses. PAD5 is NRC-approved and offers improvements over the current PAD 4.0 fuel performance code/method, namely the consideration of the effects of TCD with increasing burn up. The change in methodology is not considered a departure from a method of evaluation because PAD5 is NRG-approved, is being used for its intended application, is used within the limitations outlined in the WCAP-17642-P-A, Revision 1 SER, and it offers technical improvements over PAD 4.0. Only Criterion 8 applies to this change because it only involves a change in the method of evaluation.
Implementation of PAD5, including the reanalyzed safety analysis and use of the new fuel melt limit, may be implemented without NRC approval under the provisions of 10 CFR 50.59.
SU-19-00124, Rev. 0 Regulatory Evaluation 06/22/2023
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Description:==
The proposed activity is to implement supporting safety analysis, instrumentation, and procedural changes to support manual throttling of the low head safety injection (LHSI) flowrate via the LHSI pump discharge valves (i.e., SI-MOV-1 (2)864A/B) prior to recirculation mode transfer (RMT). Throttling the LHSI flow prior to RMT ensures adequate net positive suction head (NPSH) and containment analysis margin when the pump suction source of water is changed from the refueling water storage tank (RWST) to the containment sump. This manual operator action is only applicable if a single LHSI pump is available during safety injection and the RWST level reaches 30% (new RWST Low Level Alarm setpoint).
The following activities are assessed in this Screen:
- 1. RWST Low Level Alarm change from 20% to 30%
Serial No.24-115 10 CFR 50.59 Annual Report Page 5 of 6
- 2. Manually throttling the LHSI discharge valves (1/2-SI-MOV-1(2)864A/B)
- 3. Safety Analysis associated with activities 1 and 2 above Only activity 3 had an adverse effect when completing the SAR-Described Design Functions of the 50.59 Screen.
Summary:
The proposed activity is to implement supporting safety analysis, instrumentation, and procedural changes to support manual throttling of the low head safety injection (LHSI) flowrate via the LHSI pump discharge valves (i.e., 1 (2)-SI-MOV-1 (2)864NB) prior to recirculation mode transfer (RMT) to ensure adequate net positive suction head (NPSH) and containment analysis margin when the pump suction source of water is changed from the refueling water storage tank (RWST) to the containment sump. Once the suction source has been realigned to the sump the LHSI pump discharge valves will be unthrottled and returned to their full open position. This manual operator action is only applicable if a single LHSI pump is available during safety injection and the RWST level reaches 30% (new RWST Low Level Alarm setpoint).
The current containment safety analysis outlined in the SAR utilized minimum LHSI flowrates based on full flow through the LHSI discharge piping and valves. The safety analysis will change based on throttling the minimum flow rates even further. Therefore, a change to the safety analysis, a change to the RWST Low-Level Alarm setpoint, and procedural changes are required and therefore an evaluation was necessary. As documented in this evaluation, all eight criteria were answered no or N/A and therefore no LAR is required.
Commitment Change Evaluation Original Commitment Summary:
11/09/2023 Surry will perform fuel dispersal in accordance with the B.5.b. Phase 1 strategy for B.2.m.1.
Revised Commitment Summary:
In lieu of dispersal, the strategy for Spent Fuel Pool (SFP) thermal mitigation measures for Surry Units 1 and 2 will credit time sensitive actions for SFP external makeup and SFP external spray implementation from the time plant personnel diagnose that external SFP makeup is required, as supported by NEI 06-12.
Justification:
The original NRC Order EA-02-026 requiring a SFP thermal management program was fully rescinded because the requirements were incorporated into 10 CFR 50.54 (hh)(2). 10 CFR 50.54 (hh)(2) was subsequently moved to 10 CFR 50.155 (b)(2). The revised mitigation strategy continues to maintain compliance with 10 CFR 50.155. The revised thermal mitigation strategy results in an improvement in nuclear safety by significantly reducing the number of irradiated fuel assembly movements in the SFP while ensuring that the SFP external makeup and external spray can be implemented in a timely manner.
Commitment Change Evaluation Original Commitment Summary:
Serial No.24-115 10 CFR 50.59 Annual Report Page 6 of 6 12/06/2023 SN 94-239: Virginia Electric and Power Company Surry Power Stations Units 1 and 2, North Anna Power Station Units 1 and 2 Proposed Technical Specifications Changes Control Rod Movement Surveillance Frequency (ML18153A930)
CTS-2595, Change Surveillance Frequency of Control Rod Partial Movement from monthly to quarterly per voluntary GL 93-05.
Revised Commitment Summary:
This surveillance frequency is now being adjusted under the SFCP (Surveillance Frequency Control Program) based on License Amendments 273 and 272. This commitment is no longer valid under this tracking process. Based on present qualitative and quantitative analysis performed under the SFCP as STI-S12-2023-001, Table 4.1-2A, Line Item 2, the frequency of Partial Movement of all Control Rods is being changed from quarterly to every 6 months.
Justification:
Previous License Amendments 273 and 272 with the supporting documents and references permits the application of the SFCP to adjust the surveillance frequencies as bounded within.