ML23025A047
| ML23025A047 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/25/2023 |
| From: | Tennessee Valley Authority |
| To: | Kimberly Green NRC/NRR/DORL/LPL2-2 |
| Green K | |
| References | |
| Download: ML23025A047 (1) | |
Text
Browns Ferry Nuclear Plant Pre-Submittal Meeting for Proposed License Amendment Request Regarding Technical Specification Surveillance Requirements 3.4.3.2 and 3.5.1.11 Regarding Safety Relief Valves January 25, 2023
Agenda Introduction
Background
Description of the License Amendment Precedent Conclusion Schedule Milestones Closing Remarks 2
Introduction
- Tennessee Valley Authority (TVA) is submitting a request for an amendment to Renewed Facility Operating License Nos. DPR-33, DPR-52, and DPR-68 for Browns Ferry Nuclear Plant (BFN), Units 1, 2, and 3.
- This proposed license amendment would modify Technical Specification (TS)
Surveillance Requirements (SRs) 3.4.3.2 and 3.5.1.11 regarding safety relief valves (SRVs). The proposed change would replace the current requirement in these TS SRs to verify the SRVs open when manually actuated with an alternative requirement that verifies that the SRVs are capable of being opened.
- The proposal would also change the SR frequency from the BFN Surveillance Frequency Control Program (SFCP) to the Inservice Testing (IST) Program.
- NRC approval is requested one year from submittal of the license amendment request (LAR).
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=
Background===
- The SRVs are Target Rock model 7567F two-stage, pilot-operated safety relief valves.
- The SRVs can actuate by either of two modes: the safety mode or the non-safety mode:
- In the safety mode (mechanical self-actuation), the spring-loaded pilot valve opens when steam pressure at the valve inlet overcomes the spring force holding the pilot valve closed.
Opening the pilot valve allows a pressure differential to develop across the main valve piston and opens the main valve.
- In the non-safety mode (manual-remote opening), hand switches in the main control room can be used to manually open the valves below the self-actuating setpoints as a heat sink after reactor shutdown or for relief during in-service transient events.
- Six of the SRVs serve as Automatic Depressurization System (ADS) valves. Their purpose is to reduce reactor coolant system pressure, thus allowing low pressure emergency cooling injection.
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Description - Reason for Request
- TS surveillance testing of SRVs at BFN is currently performed at a reactor pressure vessel pressure greater than or equal to 945 psig to verify that, mechanically, each valve is functioning properly and that no blockage exists in the valve discharge line.
- Per TS SR 3.4.3.2 and 3.5.1.11, the SRVs are manually actuated every 24 months (i.e., each refueling outage) in accordance with the BFN SFCP.
- The Boiling Water Reactor Owners Group recommends avoiding unnecessary challenges to the SRVs and modifying operations to reduce spurious SRV blowdowns and reduce the probability of SRVs to stick open when challenged. Experience in the industry has shown that manual actuation of SRVs during plant operation may create a potential for SRV seat leakage.
- Reducing or eliminating the number of manual actuations of the SRVs during plant startup minimizes the potential depressurization and cooldown events due to failure-to-close SRV events, as well as minimizing the potential for pilot or main stage leakage of the SRVs.
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Description - Proposed Change to BFN TS SR 3.4.3.2 6
Description - Proposed Change to BFN TS SR 3.5.1.11 7
Description - Proposed Change to BFN TS Bases SR 3.4.3.2 8
Description - Proposed Change to BFN TS Bases SR 3.4.3.2 (cont.)
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Description - Proposed Change to BFN TS Bases SR 3.5.1.11 10
Description - Proposed Change to BFN TS Bases SR 3.5.1.11 (cont.)
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Description - Technical Evaluation
- 10 CFR 50.55a(f) requires that the licensees inservice testing (IST) program meet the requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code). The current BFN IST Program has been prepared to meet the requirements of the ASME OM Code.
- BFN Units 1, 2, and 3 are in the fourth ten-year IST interval, and the Code of Record is the ASME OM Code, 2004 Edition through 2006 Addenda.
- Mandatory Appendix I, Section I-3410, of the ASME OM Code allows a series of overlapping tests to individually test SRV components and does not require in-situ SRV testing following maintenance. Rather, each SRV removed for maintenance or testing and reinstalled shall have the electrical and pneumatic connections verified either through mechanical/electrical inspection or test.
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Description - Technical Evaluation (cont.)
- The proposed change revises the Frequency for performing SR 3.4.3.2 and SR 3.5.1.11 to be in accordance with the IST Program. This will allow crediting IST Program tests performed at frequencies other than the current 24-months as established by the BFN SFCP.
- Based on the above, SRV testing will continue to demonstrate proper operation without the need for in-situ testing with reactor steam and that this testing fully meets the requirements of the ASME OM Code for safety and relief valves which the NRC staff has previously found to be acceptable.
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Precedent
- Duke Energy submitted a license amendment request for Brunswick Steam Electric Plant that replaced the TS SRs to verify that the SRVs open when manually actuated with an alternative requirement that verifies that the SRVs are capable of being opened.
(Letter from Duke Energy to NRC, Brunswick Steam Electric Plant, Units Nos. 1 and 2, Renewed Facility Operating License Nos. DPR-71 and DPR-62, Docket Nos. 50-325 and 50-324, Request for License Amendment - Surveillance Requirements for Safety Relief Valves, dated March 4, 2019 [ML19063B740])
- The LAR was approved in a letter from the NRC to Duke Energy, Brunswick Steam Electric Plant, Units 1 and 2 - Issuance of Amendment Nos. 297 and 325 to Modify Technical Specification Surveillance Requirements 3.4.3.2 and 3.5.1.11 Regarding Safety Relief Valves (EPID L-2019-LLA-0043), dated January 8, 2020 [ML19316B057].
- The scope of that precedent is that same as the scope of this request.
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Schedule Milestones
- January 25, 2023 - Pre-submittal meeting with NRC
- August 2023 - Potential LAR supplement
- February 2024 - Requested NRC approval date (one year following submittal)
- March 2024 - Expected implementation deadline for BFN 15