ML25287A025
| ML25287A025 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/14/2025 |
| From: | David Wrona Plant Licensing Branch II |
| To: | Erb D Tennessee Valley Authority |
| Green K | |
| References | |
| EPID L-2025-LLR-0086 | |
| Download: ML25287A025 (1) | |
Text
October 14, 2025 Mr. Delson C. Erb Vice President, OPS Support Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801
SUBJECT:
BROWNS FERRY NUCLEAR PLANT, UNIT 3 - RE: ALTERNATIVE REQUEST BFN-IST-06 (EPID L-2025-LLR-0086)
Dear Mr. Erb:
By letter dated September 18, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML25261A131) Tennessee Valley Authority (TVA, the licensee),
submitted a request for the Browns Ferry Nuclear Plant (BFN), Unit 3, to the U.S. Nuclear Regulatory Commission (NRC or Commission) for a proposed alternative to certain American Society of Mechanical Engineers (ASME) Operations and Maintenance (OM) Code inservice testing (IST) requirements.
Specifically, the licensee requested in Alternative Request BFN-IST-06 to extend the testing interval required in the ASME OM Code for certain Standby Liquid Control (SLC) pumps until the end of the spring 2026 refueling outage (U3R22) at BFN, Unit 3, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(z)(2), Hardship without a compensating increase in quality and safety. The NRC staff review of Alternative Request BNF-IST-06 is described in this safety evaluation.
The NRC staff has reviewed the alternative request and concludes, as set forth in the enclosed safety evaluation, that TVA has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC authorizes the proposed alternative until the end of the spring 2026 refueling outage (U3R22) at BFN, Unit 3.
If you have any questions, please contact the Project Manager, Kimberly Green at 301-415-1627 or via e-mail at kimberly.green@nrc.gov.
Sincerely, David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-296
Enclosure:
Safety Evaluation cc: Listserv DAVID WRONA Digitally signed by DAVID WRONA Date: 2025.10.14 16:07:48 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUEST BFN-IST-06 ASME OM CODE, 2020 EDITION BROWNS FERRY NUCLEAR PLANT, UNIT 3 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-296 EPID L-2025-LLR-0086
1.0 INTRODUCTION
By letter dated September 18, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25261A131), Tennessee Valley Authority (TVA, the licensee) submitted Alternative Request BFN-IST-06 to the U.S. Nuclear Regulatory Commission (NRC) for authorization of an alternative to specific inservice testing (IST) requirements in the 2020 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) as incorporated by reference in Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a, Code and standards, for the Browns Ferry Nuclear Plant (BFN), Unit 3.
Specifically, the licensee requested in Alternative Request BFN-IST-06 to extend the testing interval required in the ASME OM Code for certain Standby Liquid Control (SLC) pumps until the end of the spring 2026 refueling outage (U3R22) at BFN, Unit 3 pursuant to 10 CFR 50.55a(z)(2), Hardship without a compensating increase in quality and safety. The NRC staff review of Alternative Request BNF-IST-06 is described in this safety evaluation.
2.0 REGULATORY EVALUATION
The NRC regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, state in part:
Throughout the service life of a boiling or pressurized water-cooled nuclear power facility, pumps and valves that are within the scope of the ASME OM Code must meet the inservice test requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in [10 CFR 50.55a(f)(2) and (3)] and that are incorporated by reference in [10 CFR 50.55a(a)(1)(iv)], to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state:
Alternatives to the requirements of [10 CFR 50.55a(b) through (h)] or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The applicant or licensee must demonstrate that:
(1) Acceptable level of quality and safety. The proposed alternative would provide an acceptable level of quality and safety; or (2) Hardship without a compensating increase in quality and safety. Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensees Alternative Request BFN-IST-06 Applicable OM Code Edition The applicable OM Code of record for the Fifth IST Interval at BFN, Unit 3, is the 2020 Edition of the ASME OM Code as incorporated by reference in 10 CFR 50.55a. The Fifth IST interval began on August 31, 2023, at BFN, Unit 3.
Applicable ASME OM Code Components Alternative Request BFN-IST-06 applies to the SLC pumps at BFN, Unit 3, as indicated in Table 1 below.
Table 1 Site/Unit Pump ID Pump Description Pump Type ASME Code Class ASME OM Group Browns Ferry Nuclear Plant, Unit 3 3-PMP-63-6A SLC Pump 3A Positive Displacement 2
B 3-PMP-63-6B SLC Pump 3B Positive Displacement 2
B Applicable ASME OM Code Requirements ASME OM Code, Subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, paragraph ISTB-3400, Frequency of Inservice Tests, states in part:
An inservice test shall be run on each pump as specified in Table ISTB-3400-1.
For those pumps identified in ISTB-1400(d), a pump periodic verification test shall be performed biennially in accordance with this Subsection.
ASME OM Code, Subsection ISTB, Table ISTB-3400-1, Inservice Test Frequency, specifies that for Group B pumps, a Group B Test shall be performed quarterly, and a Comprehensive [Pump] Test (CPT) and a Pump Periodic Verification Test (PPVT) shall be performed biennially.
ASME OM Code, Subsection ISTB, paragraph ISTB-5322, Group B Test Procedure, states in part:
Group B tests shall be conducted with the pump operating as close as practical to a specified reference value.
ASME OM Code, Subsection ISTA, General Requirements, paragraph ISTA-3170, Inservice Examination and Test Frequency Grace, subparagraph ISTA-3170(a)(1) states:
For periods specified as fewer than 2 yr [years], the period may be extended by up to 25% [percent] for any given test.
Licensees Proposed Alternative and Basis for Use In Alternative Request BFN-IST-06, the licensee proposed to extend the interval for Group B quarterly pump tests required by ASME OM Code, paragraph ISTB-3400, for the 3-PMP-63-6A [3A] and 3-PMP-63-6B [3B] SLC pumps until the end of the BFN, Unit 3, refueling outage (U3R22) in the spring of 2026. This will allow performance of the biennial CPT and PPVT for the 3A and 3B SLC pumps during the spring 2026 refueling outage, and the Group B quarterly pump tests will resume as scheduled following repair of the SLC test line throttle valve (3-THV-63-518) and reactor startup from the U3R22 outage at BFN, Unit 3.
Licensees Basis for Use In Alternative Request BFN-IST-06, the licensee provided previous IST trends for the 3A and 3B SLC pumps to show the operational readiness of the pumps. The last 4 years of data from the quarterly Group B testing and the last 10 years of data from the CPT for the 3A and 3B SLC pumps indicate that there is no current pump degradation. The recorded values for pump vibration, flow, and discharge pressure during the review period were within ASME OM Code and design limits. Therefore, the licensee asserted that it is unlikely that the upcoming quarterly pump tests would produce a failing value for any test parameter.
The licensee stated that periodic maintenance of each pump is performed to disassemble, inspect pump internals, and refurbish as necessary in accordance with the BFN Preventive Maintenance Program. The 3A SLC pump was internally inspected in March 2022, and it had previously been replaced in March 2014. The 3B SLC pump was internally inspected in March 2016 and March 2024. The last two inspections found the pump internals in good condition with only periodic refurbishment needed. The licensee considers that the available data support the assumption that the pumps are capable of performing their design functions until their next scheduled internal inspections.
The licensee stated that repairs to the 3-THV-63-518 valve are planned for the upcoming spring 2026 refueling outage because repair of the valve requires tagging out the 3A and 3B SLC pumps, rendering them inoperable. Under current conditions, the licensee asserts that performing the Group B quarterly test for the 3A and 3B SLC pumps would constitute a hardship without a compensating increase in the level of quality and safety. The licensee considers that the proposed alternative provides reasonable assurance of pump operational readiness and an acceptable level of quality and safety.
Licensees Reason for Request In its submittal, the licensee explained that on August 12, 2025, during the performance of SLC pump functional testing on BFN, Unit 3, testing was stopped, after the 3A pump (3-PMP-63-6A) test, due to abnormal indications on the SLC pump discharge pressure instrument (3-PI-63-7B). Testing re-commenced on August 13, 2025, and again was halted due to abnormal indications. During this performance, pressure continued to rise even as the SLC test line throttle valve (3-THV-63-518) was opened. Subsequent troubleshooting identified a stem/disc separation in the 3-THV-63-518 valve, which is the ASME Boiler and Pressure Vessel Code,Section XI, Code Class 2 equivalent and Seismic Class I boundary isolation valve utilized for throttling the quarterly test flow circuit.
SLC pump functional testing was originally due by July 22, 2025, but, because of a surveillance schedule conflict and resource availability during a forced outage, was extended by the Code-allowed grace period to August 15, 2025. Testing of the 3A SLC pump was completed satisfactorily. However, due to failure of the 3-THV-63-518 valve, testing of the 3B pump (3-PMP-63-6B) was not completed within its required quarterly periodicity, including the grace period, which elapsed at 0000 Central Time on August 16, 2025. The licensee plans to perform extent of condition disassembly and inspection on the SLC test line throttle valves for BFN, Units 1 and 2, during their next respective refueling outages.
Based on the condition of the 3-THV-63-518 valve, the licensee stated that performing pump testing could result in damaging the valve, which is currently in its safety position of locked closed. Degradation or chattering of the 3-THV-63-518 valve during pump testing could result in the valve failing to re-close, which would render both loops of SLC inoperable due to a loss of the of the Seismic/Code Class 2 Equivalent boundary valve. The licensees review of the suspected mechanism of the stem/disc separation indicates that the failure allows motion of the valve disc with flow with the handwheel full open, and the valve would function as a stop-check if the test was performed. The closing of the handwheel was able to seat the valve when observed via a borescope. The licensee determined that there is not a likely failure mode where the disc becomes lodged in the flow stream.
The licensee stated that maintaining the 3-THV-63-518 valve locked closed eliminates the normal testing flow path. Vessel injection through the squib valves (3-FCV-63-8A and 3-FCV-63-8B) is not an acceptable solution for online testing due to the complexity associated with the testing and the potential for injecting sodium pentaborate. An alternate flow path through SLC pump discharge drain valves 3-DRV-63-522 and 3-DRV-63-523 is available, but has not historically been utilized for testing. The drain valves are gate valve designs, which are not ideal for throttling and pressure control, and the piping downstream of the 3-DRV-63-523 valve is not rated for the 1150 pounds per square inch gauge normal test pressure.
Additionally, SLC vent valve 3-VTV-63-521 is an alternate throttle valve. However, use of this vent valve and flow path requires flow through the 3-THV-63-518 valve which risks further damage to the valve condition. Therefore, use of the vent valve, drain valves, or injecting into the reactor vessel are not considered to be desirable alternatives for quarterly testing.
The SLC test line throttle valve is common to both the 3A and 3B SLC pumps. To affect repairs to this valve, both SLC pumps will be declared inoperable, requiring entry into BFN Technical Specification (TS), Limiting Condition for Operation (LCO) 3.1.7, Condition B, which requires restoration of at least one SLC pump within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. If an SLC subsystem is not restored to operable status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, BFN, Unit 3, would be required to enter TS LCO 3.1.7, Condition C, which requires entry into Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and entry to Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The licensee stated that repairs to the 3-THV-63-518 valve are expected to take 4 to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Removing the clearances post-repair and performing the SLC pump functional test to restore operability could take another 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
The licensee submitted Alternative Request BFN-IST-06 pursuant to 10 CFR 50.55a(z)(2) based on the determination that compliance with the ASME OM Code required quarterly SLC pump functional tests cannot be performed without considerable plant safety and reliability risks prior to significant repairs to the 3-THV-63-518 valve. The licensee plans to repair this valve during the BFN, Unit 3, Cycle 22 refueling outage (U3R22) in the spring of 2026 to restore acceptable test alignment, without time pressure and with a focus on quality. As a contingency, the repair scope is included on the forced outage maintenance list and would be performed if a forced outage were to occur prior to the planned refueling outage with scope and plant conditions that allow the repair.
3.2
NRC Staff Evaluation
In Alternative Request BFN-IST-06, the licensee proposed to extend the interval for the Group B tests required in the ASME OM Code (2020 Edition), Subsection ISTB, paragraph ISTB-3400, for the SLC pumps 3-PMP-63-6A and 3-PMP-63-6B at BFN, Unit 3, in accordance with 10 CFR 50.55a(z)(2) on the basis that compliance with those requirements represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee stated that the current OM Code of Record for the IST Program at BFN, Unit 3, requires the subject Group B pumps to be tested every 3 months. The licensee indicated that the pump testing was originally due by July 22, 2025, but due to a surveillance schedule conflict and resource availability during a forced outage, was extended by the grace period to August 15, 2025, allowed by ASME OM Code, Subsection ISTA, paragraph ISTA-3170(a)(1). The licensee reported that testing of the 3A SLC (3-PMP-63-6A) pump was satisfactory on August 15, 2025. However, due to failure of the 3-THV-63-518 valve, testing of the 3B SLC pump (3-PMP-63-6B) could not be completed within the required timeframe. In its request, the licensee proposed to extend the IST testing schedule for these pumps until the end of the BFN, Unit 3, spring 2026 refueling outage (U3R22), when the throttle valve (3-THV-63-518) is expected to be repaired. Alternative Request BFN-IST-06 specifies that if BFN, Unit 3, experiences a forced outage prior to the spring outage, the licensee will assess whether the 3-THV-63-518 valve can be successfully repaired, depending on the plant conditions and without jeopardizing the health and safety of plant personnel.
In its submittal dated September 18, 2025, the licensee provided the history of the tests results for the 3A and 3B SLC pumps at BFN, Unit 3. In particular, the quarterly Group B over the last 4 years, biennial Comprehensive pump testing over last 10 years, and one PPVT test in 2024 (as required by OM Code, Subsection ISTB, paragraph ISTB-3400) demonstrate successful performance of the SLC pumps. The recorded values of pump vibration, flow, and differential pressure remain within the ASME OM Code and design limits. Minor variation is evident among the measured pump performance provided in the pump data tables in the licensee submittal. However, the data tables indicate that all trends are within the acceptance criteria. The NRC staff did not identify any significant adverse trends in the provided data that might reflect degraded performance of the SLC pumps.
In its submittal dated September 18, 2025, the licensee provided the maintenance history of the 3A and 3B SLC pumps. The licensee reported that periodic maintenance of each pump is performed to disassemble, inspect pump internals, and refurbish, as necessary, in accordance with the BFN Preventive Maintenance Program. The 3A SLC pump was internally inspected in March 2022, and had been previously replaced in March 2014. The 3B SLC pump was internally inspected in March 2016 and March 2024. During the last two inspections, the licensee reports that the as-found pump internals were in good condition with only periodic refurbishment needed. The NRC staff considers the licensee information to support a determination that the pumps are capable of performing their design functions until their next scheduled internal inspections.
The licensee stated that the repairs of the 3-THV-63-518 valve are planned for the upcoming spring 2026 refueling outage, because repair of the valve requires tagging out the 3A and 3B SLC pumps, rendering them inoperable. Based on the condition of the 3-THV-63-518 valve, performing SLC pump testing could result in damaging the valve, which is currently in its safety position of locked closed. Degradation or chattering of the 3-THV-63-518 valve from the pump testing could result in the valve failing to re-close, which would render both loops of the SLC system inoperable due to a loss of the Seismic/Code Class 2 Equivalent boundary valve. Under current conditions, the NRC staff finds that performing the Group B quarterly test for the 3A and 3B SLC pumps would constitute a hardship without a compensating increase in the level of quality and safety.
Based on its independent review of the test data and performance history of the SLC pumps within the scope of Alternative Request BFN-IST-06, the NRC staff has determined that there is reasonable assurance of the operational readiness of the 3A and 3B SLC pumps at BFN, Unit 3, to perform their design functions during the proposed IST test interval extension. The NRC staff finds that compliance with the specified IST requirements for the subject pumps during the short duration of the requested alternative would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Therefore, the NRC staff determined that the proposed alternative meets the requirements of 10 CFR 50.55a(z)(2). As a result, the NRC staff finds that Alternative Request BFN-IST-06 may be authorized for an extension of the specified testing intervals for the 3A and 3B SLC pumps at BFN, Unit 3, until the end of the spring 2026 refueling outage (U3R22). The staff notes that Alternative Request BFN-IST-06 specifies that if BFN, Unit 3, experiences a forced outage prior to the spring 2026 outage, the licensee will assess whether the 3-THV-63-518 valve can be successfully repaired, depending on the plant conditions and without jeopardizing the health and safety of plant personnel.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that the licensee has justified that compliance with the applicable ASME OM Code test requirements for the subject 3A and 3B SLC pumps at BFN, Unit 3, would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety until the throttle valve 3-THV-63-518 is repaired.
The NRC staff also found that the testing and performance experience of the subject pumps provides reasonable assurance that they will be operationally ready to perform their safety functions for the duration of the request. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2).
Therefore, the NRC staff authorizes Alternative Request BFN-IST-06 to extend the Group B quarterly testing of the 3A and 3B SLC pumps until the end of the spring 2026 refueling outage (U3R22) at BFN, Unit 3.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), remain applicable.
Principal Contributors: G. Bedi, NRR T. Scarbrough, NRR Date: October 14, 2025
ML25287A025 NRR-028 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-2/LA NRR/DEX/EMIB/BC NRR/DORL/LPL2-2/BC NAME GEMiller ABaxter (SLent for)
SBailey DWrona DATE 10/14/2025 10/14/2025 10/14/2025 10/14/2025 OFFICE NRR/DORL/LPL2-1/PM NAME GEMiller DATE 10/14/2025