ML23219A154
| ML23219A154 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/17/2023 |
| From: | David Wrona NRC/NRR/DORL/LPL2-2 |
| To: | Jim Barstow Tennessee Valley Authority |
| References | |
| EPID L-2022-LLR-0086 | |
| Download: ML23219A154 (1) | |
Text
August 17, 2023 Mr. James Barstow Vice President, Nuclear Regulatory Affairs and Support Services Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801
SUBJECT:
BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2, AND 3 - REQUEST TO USE LATER EDITION OF ASME CODE FOR OPERATION AND MAINTENANCE AND ALTERNATIVE REQUESTS BFN-IST-01 THROUGH 05 FOR THE FIFTH 10-YEAR INTERVAL INSERVICE TESTING PROGRAM (EPID L-2022-LLR-0086)
Dear Mr. Barstow:
By letter dated December 12, 2022, as supplemented by letter dated June 1, 2023, the Tennessee Valley Authority (TVA) submitted several requests to the U. S. Nuclear Regulatory Commission (NRC) to use a later code edition and the use of alternatives to certain American Society of Mechanical Engineers (ASME) for Operation and Maintenance of Nuclear Power Plants (OM Code) at Browns Ferry Nuclear Plant (Browns Ferry), Units 1, 2, and 3.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(f)(4)(iv), TVA requested to use a later code edition and addenda for inservice testing (IST) items subject to the conditions specified in 10 CFR 50.55a(b). Also, pursuant to 10 CFR 50.55a(z)(2), TVA requested to use proposed alternatives BFN-IST-01 through 05 on the basis that compliance with the code requirements represents a hardship or unusual difficulty.
The NRC staff has reviewed the subject requests and concludes, as set forth in the enclosed safety evaluation, that: (1) request to use the 2020 Edition of the ASME OM Code in its entirety as the Code of record for pumps, valves, and snubbers in the Fifth 10-Year Interval IST Program at Browns Ferry is acceptable and (2) TVAs Alternative Requests BFN-IST-01 through 05 provide an acceptable level of quality and safety. Accordingly, the NRC staff concludes that TVA has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(f)(4)(iv) and 10 CFR 50.55a(z)(2). Therefore, the NRC approves the use of the 2020 Edition of the ASME OM Code and authorizes the use of Alternatives BFN-IST-01 through 05 for the Fifth 10-Year Interval IST Program at Browns Ferry, Units 1, 2, and 3.
All other ASME OM Code requirements for which an alternative was not specifically requested and approved in these relief requests remain applicable.
If you have any questions, please contact Ms. Kimberly Green at 301-415-1627 or via email at Kimberly.Green@nrc.gov.
Sincerely, David J. Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-259, 50-260, 50-296
Enclosure:
Safety Evaluation cc: Listserv David J.
Wrona Digitally signed by David J. Wrona Date: 2023.08.17 13:23:03 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION USE OF LATER ASME OM CODE EDITION AND ALTERNATIVE REQUESTS BFN-IST-01 THROUGH 05 REGARDING VALVE POSITION INDICATION TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2, AND 3 DOCKET NOS. 50-259, 50-260, AND 50-296
1.0 INTRODUCTION
By letter dated December 12, 2022 (Agencywide Documents Access and Management System Accession No. ML22346A189), as supplemented by letter dated June 1, 2023 (ML23152A148),
the Tennessee Valley Authority (TVA, the licensee) requested the use of a later code edition and the use of alternatives to certain requirements of the American Society of Mechanical Engineers (ASME) for Operation and Maintenance of Nuclear Power Plants (OM Code) for the Fifth 10-Year Interval Inservice Testing (IST) Program at Browns Ferry Nuclear Plant (Browns Ferry), Units 1, 2, and 3.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(f)(4)(iv),
the licensee requested to use a later code edition and addenda for inservice testing items subject to the conditions specified in 10 CFR 50.55a(b). Also, pursuant to 10 CFR 50.55a(z)(2),
the licensee requested to use proposed alternatives BFN-IST-01 through 05 on the basis that compliance with the code requirements represents a hardship or unusual difficulty.
The duration of the request to use a later edition of the ASME OM Code and the proposed alternatives is for the Fifth 10-Year Interval IST Program, which is scheduled to begin on August 31, 2023, and end on August 30, 2032.
2.0 REGULATORY EVALUATION
The NRC regulations at 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, state, in part, that 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 IST 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 regulation at 10 CFR 50.55a(f)(4)(ii), Applicable IST Code: Successive 120-month intervals, states, in part, that licensees are required to comply with the latest edition and addenda of the ASME OM Code incorporated by reference in the regulations 18 months prior to the start of each 120-month IST program interval.
The NRC regulation at 10 CFR 50.55a(f)(4)(iv), Applicable IST Code: Use of the Later editions and addenda, states:
Inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in paragraph (a)(1)(iv) of this section, subject to the conditions listed in paragraph (b) of this section, and subject to NRC approval. Portions of editions or addenda may be used, provided that all related requirements of the respective editions or addenda are met.
The NRC regulation at 10 CFR 50.55a(b)(3)(xi), OM condition: Valve Position Indication, states:
When implementing paragraph ISTC-3700, Position Verification Testing, in the ASME OM Code, 2012 Edition through the latest edition of the ASME OM Code incorporated by reference in paragraph (a)(1)(iv) of this section [10 CFR 50.55a],
licensees must verify that valve operation is accurately indicated by supplementing valve position indicating lights with other indications, such as flow meters or other suitable instrumentation to provide assurance of proper obturator position for valves with remote position indication within the scope of Subsection ISTC including its mandatory appendices and their verification methods and frequencies. For valves not susceptible to stem-disk separation, licensees may implement ASME OM Code Case OMN-28, Alternative Valve Position Verification Approach to Satisfy ISTC-3700 for Valves Not Susceptible to Stem-Disk Separation, which is incorporated by reference in paragraph (a)(1)(iii)(H) of this section [10 CFR 50.55a]. Where plant conditions make it impractical to perform the initial ISTC-3700 test as supplemented by paragraph (b)(3)(xi) of this section by the date 2 years following the previously performed ISTC-3700 test, a licensee may justify an extension of this initial supplemental valve position verification provided the ISTC-3700 test as supplemented by paragraph (b)(3)(xi) of this section is performed at the next available opportunity and no later than the next plant shutdown. This one-time extension of the ISTC-3700 test schedule as supplemented by paragraph (b)(3)(xi) of this section is acceptable provided the licensee has available for NRC review documented justification based on information obtained over the previous 5 years of the structural integrity of the stem-disk connection for the applicable valves. The licensees justification could be based on, for example, verification of the valve stem-disk connection through an appropriate weak link analysis, appropriate disk motion confirmed during diagnostic testing, or allowance and cessation of flow through the valves. The licensees justification must provide reasonable assurance that the remote indicating lights accurately reveal the position of the valve obturator until the next ISTC-3700 test as supplemented by paragraph (b)(3)(xi) of this section is performed.
The NRC regulation at 10 CFR 50.55a(z), Alternatives to codes and standards requirements, states, in part, that alternatives to the requirements in paragraphs (b) through (h) of 10 CFR 50.55a may be used when authorized by the NRC if the licensee demonstrates that: (1) the proposed alternative would provide an acceptable level of quality and safety, or (2) 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
The NRC staff has evaluated the information provided by the licensee in support of the requests to use the 2020 Edition of the ASME OM Code and for alternatives to ASME OM Code. The bases for their disposition are documented below. For clarity, the licensees requests have been evaluated in several parts according to ASME OM Code testing category.
3.1 Request to Use Later Edition of ASME OM Code 3.1.1 Licensees Request At Browns Ferry, the licensee is currently implementing the fourth 10-year IST interval, which was originally scheduled to end on August 30, 2022, but was extended to August 30, 2023, as allowed by ASME OM Code, Subsection ISTA, paragraph ISTA-3120(d). Therefore, the Fifth 10-Year Interval IST Program is required to begin no later than August 31, 2023. The Code of record for the Fourth 10-Year Interval IST Program is the 2004 Edition through 2006 Addenda of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a. In accordance with 10 CFR 50.55a(f)(4)(ii), the licensee would be required to implement the 2017 Edition of the ASME OM Code as incorporated by reference in 10 CFR 50.55a for the Fifth 10-Year Interval IST Program at Browns Ferry. In its submittal, the licensee proposes to adopt, in its entirety, the 2020 Edition of the ASME OM Code in lieu of the 2017 Edition of the OM Code, subject to the conditions in 10 CFR 50.55a(b)(3) for the pumps, valves, and snubbers contained in the Browns Ferry IST Program. Therefore, there are no related requirements associated with the proposed later Code edition for consideration associated with the request.
The licensee indicates that it plans to update the applicable procedures and processes to comply with the provisions of the 2020 Edition of the ASME OM Code, subject to the conditions in 10 CFR 50.55a(b)(3), and commence using the proposed later edition of the ASME OM Code at the beginning of the Fifth 10-Year Interval IST Program, which is scheduled to start no later than August 31, 2023. During the Fifth 10-Year Interval IST Program at Browns Ferry, the licensee states that it intends to only use those ASME OM Code Cases, as applicable, that have been endorsed by the NRC in Regulatory Guide (RG) 1.192, Operation and Maintenance Code Case Acceptability, ASME OM Code.
3.1.2 NRC Staff Evaluation The NRC regulations in 10 CFR 50.55a(f)(4)(iv) state that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(a)(1)(iv), subject to the conditions listed in 10 CFR 50.55a(b),
and subject to NRC approval. The regulations also specify that portions of editions or addenda may be used, provided that all related requirements of the respective editions or addenda are met.
The NRC revised 10 CFR 50.55a to incorporate by reference the 2020 Edition of the ASME OM Code in a final rule dated October 27, 2022 (Federal Register, Volume 87, No. 207, pages 65128-65157), subject to the conditions in 10 CFR 50.55a.
NRC Regulatory Issue Summary (RIS) 2004-12 (July 28, 2004), Clarification on Use of Later Editions and Addenda to the ASME OM Code and Section XI, clarifies the requirements for IST and inservice inspection when using later editions and addenda of the ASME OM Code and ASME Boiler and Pressure Vessel Code as required by 10 CFR 50.55a(f)(4)(iv) and (g)(4)(iv). In RIS 2004-12, the NRC staff states that the fact that ASME Code editions and addenda have been incorporated by reference into the regulations does not imply that Commission approval has already been given. The staff states that licensees must request approval to use later Code editions and addenda via a letter to the NRC. When requesting to use editions and addenda of the ASME Code that have not yet been incorporated by reference, licensees must request authorization to use these later editions and addenda as an alternative to the regulations pursuant to 10 CFR 50.55a. The staff indicates that a request to use a later edition and addenda is not a relief or alternative request, but rather is simply a request to use a later Code. The staff states that if portions of a later Code edition and addenda are used, licensees must assure that all related requirements of the respective editions and addenda are met. A discussion of the related requirements should be included in the letter to the NRC. The regulations do not specify when the letter must be submitted, only that it be submitted before using the proposed later Code edition and addenda.
The NRC regulations in 10 CFR 50.55a(f)(4)(iv) apply to the use of later ASME Code editions for the IST Program for pumps and valves. RIS 2004-12 provides guidance for the use of later ASME Code editions and addenda to satisfy 10 CFR 50.55a(f)(4)(iv). Therefore, the NRC staff considers the guidance in RIS 2004-12 to be applicable to the use of later editions of the ASME OM Code in IST Programs.
For Browns Ferry, the licensee specifies that it will implement the 2020 Edition of the ASME OM Code in its entirety as the IST Code of record for the Fifth 10-Year Interval IST Program. As a result, there are no portions of the 2020 Edition of the ASME OM Code to be evaluated as part of this request. Therefore, the NRC staff finds the licensees request to be acceptable where the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, is implemented in its entirety.
3.1.3 Conclusion Based on the review discussed above, the NRC staff finds that the licensees request to use the 2020 Edition of the ASME OM Code in its entirety as the Code of record for pumps, valves, and snubbers in the Fifth 10-Year Interval IST Program at Browns Ferry is acceptable. Therefore, the NRC staff concludes that the use of the 2020 Edition, in lieu of the 2017 Edition, of the ASME OM Code in its entirety, as incorporated by reference in 10 CFR 50.55a, as the IST Code of record for pumps, valves, and snubbers in the Fifth 10-Year Interval IST Program at Browns Ferry meets the NRC requirements in 10 CFR 50.55a(f)(4)(iv).
3.2 Alternative Request BFN-IST-01 3.2.1 Licensees Request
=
Applicable Code Edition and Addenda===
As indicated in section 3.1.3 above, the NRC staff is approving the use of a later edition of the ASME OM Code. Therefore, the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a with conditions, will be applicable to the Fifth 10-Year Interval IST Program at Browns Ferry.
=
Applicable Code Requirement===
ASME OM Code, 2020 Edition, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3700, Position Verification Testing, states:
Valves with remote position indicators shall be observed locally at least once every 2 yr [years] to verify that valve operation is accurately indicated. Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation.
Position verification for active [motor-operated valves] MOVs shall be tested in accordance with Division 1, Mandatory Appendix III.
ASME Code Components Affected Alternative Request BFN-IST-01 applies to the valves identified in Table 1.
Table 1 Site/Unit Component ID Component Description Valve Type OM Code Class Valve Size OM Category Browns Ferry Units 1, 2, and 3 1/2/3-FCV-85-37C SDIV DRN ISOL WEST Globe 2
2 B
Browns Ferry Units 1, 2, and 3 1/2/3-FCV-85-37E SDIV DRN ISOL EAST Globe 2
2 B
Browns Ferry Units 1, 2, and 3 1/2/3-FCV-85-82A SCRM DISCH HDR VT WEST Globe 2
2 B
Browns Ferry Units 1, 2, and 3 1/2/3-FCV-85-83A SCRM DISCH HDR VT EAST Globe 2
2 B
Abbreviations ID: Identification number FCV: Flow Control Valve SDIV: Scram Discharge Instrument Volume DRN: Drain ISOL: Isolation SCRM: Scram DISCH: Discharge HDR: Header VT: Vent Licensees Proposed Alternative Request BFN-IST-01 and Basis for Use The licensees proposed Alternative Request BFN-IST-01 is as follows:
For the open position, local verification (e.g., limit switches, position indicators on the valve, valve stem travel) will be used to determine valve movement is accurately indicated by the remote position indicators (red lights) located in the main control room (MCR). Supplemental position verification of the SDV [scram discharge volume] vent and drain valves in the open position will be satisfied by demonstrating the ability to maintain the SDV drained below applicable level alarm setpoints during unit operation.
For the closed position, local verification (e.g., limit switches, position indicators on the valve, valve stem travel) will be used to determine valve movement to the closed position is accurately indicated by the remote position indicators (green lights) located in the MCR. Supplemental position verification of the SDV vent and drain valves in the closed position will be satisfied by demonstrating annunciation of the SDIV [scram discharge instrument volume] high level alarm during a scram. Failure of any individual valve to close would be detectable using remote position indication in the control room.
The proposed alternative testing will be performed at the OM Code Subsection ISTC-3700 frequency of at least once every two years. TVA may adopt OM Code cases that modify the two-year frequency when approved by the NRC or once endorsed in Regulatory Guide (RG) 1.192.
Because each SDV vent and drain line contains a Code and non-Code valve in series, TVA also intends to apply this supplemental verification methodology to the non-OM Code SDV vent and drain valves in the BFN augmented IST program.
The licensee submitted Alternative Request BFN-IST-01 in accordance with 10 CFR 50.55a(z)(2) on the basis that compliance with valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), represent a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee considers that for the open and closed positions of the applicable valves in Alternative Request BFN-IST-01, local verification during stroke time testing demonstrates valve movement occurs and remote position indicators located in the MCR accurately reflect the locally observed valve position. The supplemental position verification of the SDV vent and drain valves in the open position will be provided by demonstrating the ability to maintain the SDIV drained below applicable level alarm setpoints during unit operation and by demonstrating the ability to drain the SDV and perform a scram reset. The licensee notes that each SDV is provided with three level switches that provide alarms in the MCR to alert operators of water accumulation in the SDIV. The first alarm notifies control room operators that the SDV is not fully drained. The next level alarm results in a control rod block. The final SDV level alarm results in a reactor scram. Therefore, the continuous monitoring of the SDV level provided by the system design provides supplemental verification that the open position of the SDV vent and drain valves is accurately indicated. The licensee states that failure of an SDV vent or drain valve in the closed position would be detected by indicating lights or SDV level increase. As a result, the licensee asserts that there would be ample time and warning available to drain the SDV before an automatic scram would occur due to SDV high level. The licensee also noted that supplemental position verification of the SDV vent and drain valve pairs in the closed position is provided by demonstrating annunciation of the SDIV high level alarms during a scram.
Licensees Reason for Request The licensee states that due to the design of the Browns Ferry Units 1, 2, and 3 control rod drive (CRD) system, the SDV vent and drain valves cannot be individually operated to perform supplemental position indication verification as required by 10 CFR 50.55a(b)(3)(xi). The 2-inch vent air-operated valves (AOVs) are designed as a series pair (one Code Class 2 equivalent and one non-Code Class equivalent).
The manual actuation of the vent and drain valves for the purpose of periodic exercise testing is controlled by two keylock switches. The activation of the first keylock switch opens the first solenoid in the valve body but does not affect the air volume. Activation of both keylock switches is required to affect the air volume and actuation of the drain and vent valves. On each unit, the control circuit for the air supply of the SDV vent and drain valves is a single air header fed through a single valve body with two internal solenoids. All valve pairs open and close simultaneously when given a signal due to this configuration for each unit. There are two additional potential exhaust pathways with a single normally closed solenoid valve. These are only actuated for alternative rod insertion (ARI) or anticipated transient without scram (ATWS) response. The licensee provided a layout of the SDV and related instrumentation and controls in Figure 1 of its submittal.
The licensee considers that the position verification requirement in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), is impractical to perform on each valve in the scope of Alternative Request BFN-IST-01 due to the design of the pneumatic control system for these AOVs. Each vent and drain line have two AOVs in series, with no installed capability to verify individual valve obturator position with supplemental indications. The licensee states that significant plant design changes (e.g., redesigning the SDIV system) would be necessary to perform the valve position indication testing as required by ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi).
3.2.2 NRC Staff Evaluation For the open position of the valves within the scope of Alternative Request BFN-IST-01, the licensee proposes to use the open remote position indicators (red lights) located in the MCR, together with the ability of the open valves to maintain the SDV drained below the applicable level alarm setpoints during unit operation.
For the closed position of the valves within the scope of Alternative Request BFN-IST-01, the licensee proposes to use the closed remote position indicators (green lights) located in the MCR, together with the valves being indicated as closed by annunciation of the SDIV high level alarm during a scram. In its letter dated June 1, 2023, in response to an NRC request for additional information (RAI), the licensee stated that during this scram test, if series valves on either tank failed to close, reactor pressure vessel (RPV) pressure test conditions would be affected by a change in RPV volume and makeup requirements. The licensee stated that its procedures ensure that the system is pressurized up to the AOVs for alternate VT-2 inspections during the Class 1 system pressure test. This verification demonstrates that both AOVs on each line indicate closed, and the lack of change in system parameters indicate that at least one AOV per line is providing required isolation. The SDIV high level alarm in conjunction with normal RPV pressure test conditions demonstrates that each SDV vent and drain line is physically isolated by at least one valve, and the position indication of all valves are closed.
Also in its RAI response, the licensee confirmed that the alternative testing will be performed at least once every 2 years as specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, and that the frequency will not be decreased unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case accepted in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee stated that its implementing procedures for the referenced Browns Ferry Technical Specification (TS) Surveillance Requirements (SRs) specify the IST program required frequencies when the testing is credited for IST program compliance. The licensee stated that the Surveillance Frequency Control Program (SFCP) process does not allow changing the frequencies of the Browns Ferry IST program unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case endorsed in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee relies on its administrative procedures to provide control to prevent unauthorized changes to IST required frequencies.
The NRC staff finds that compliance with the specified requirements in ASME OM Code, Subsection ISTC, paragraph ISTC 3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety because significant plant design changes (e.g., redesigning the SDIV system) would be necessary to perform the required valve position indication testing. The NRC staff also finds that the alternative, for the reasons stated above, will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request.
3.2.3 Conclusion Based on the review described above, the NRC staff finds that the licensee has demonstrated that a hardship or unusual difficulty would exist to meet the valve position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 1 of this SE, without a compensating increase in the level of quality and safety. The NRC staff also finds that Alternative Request BFN-IST-01 will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request. As a result, the NRC staff concludes that the licensees proposed Alternative Request BFN-IST-01 for the valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 1 of this SE meets the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the use of proposed Alternative Request BFN-IST-01 for the Fifth 10-Year Interval IST Program at Browns Ferry.
All other ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, for which an alternative was not specifically requested and authorized, remain applicable.
3.3 Alternative Request BFN-IST-02 3.3.1 Licensees Request
=
Applicable Code Edition and Addenda===
As indicated in section 3.1.3 above, the NRC staff is approving the use of a later edition of the ASME OM Code. Therefore, the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a with conditions, will be applicable to the Fifth 10-Year Interval IST Program at Browns Ferry.
=
Applicable Code Requirement===
ASME OM Code, 2020 Edition, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3700, Position Verification Testing, states:
Valves with remote position indicators shall be observed locally at least once every 2 yr to verify that valve operation is accurately indicated. Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation.
Position verification for active MOVs shall be tested in accordance with Division 1, Mandatory Appendix III.
ASME Code Components Affected Alternative Request BFN-IST-02 applies to the valves identified in Table 2.
Table 2 Site/Unit Component ID Component Description Valve Type OM Code Class Valve size OM Category Browns Ferry Units 2 and 3 2/3-FCV-74-46 RHR SYS I-II CROSSTIE VLV Gate 2
24 B
Browns Ferry Units 1, 2, and 3 1/2/3-SHV-74-91 RHR to FUEL POOL F/D SOV Gate 2
8 B
Browns Ferry Unit 3 3-SHV-74-150 RHR SYS I and II DISCH CROSSTIE SOV Gate 2
24 B
Abbreviations ID: Identification number FCV: Flow Control Valve RHR: Residual Heat Removal VLV: Valve SHV: Shutoff Vave SOV: Solenoid-Operated Valve DISCH: Discharge Licensees Proposed Alternative Request BFN-IST-02 and Basis for Use The licensees proposed Alternative Request BFN-IST-02 is as follows:
In lieu of OM Code Subsection ISTC-3700, TVA will perform the following:
For RHR Crosstie valves 2-FCV-74-46 and 3-SHV-74-150 in the closed safety position, TVA will supplement valve closure indication by monitoring system pressure in the out of service loop during pump testing. For the open non-safety position, TVA will manually open these valves to verify dual-indication when the valves are partially opened.
For RHR Crosstie valve 3-FCV-74-46, when closed to isolate the Loop 1 to Loop 2 crosstie in lieu of 3-SHV-74-150, TVA will supplement valve closure indication by monitoring system pressure in the out of service loop during pump testing. When valve 3-FCV-74-46 is in its normal open non safety position, TVA will manually close this valve to verify dual-indication when the valve is partially closed.
For valves 1/2/3-SHV-74-91 in the closed safety position, TVA will manually open these valves to verify the closed indicating light extinguishes when the valves are partially opened. TVA will supplement valve closure indication by using pressure or flow measurement techniques.
Supplemental indication is not required for the partial stroke open (to the non-safety position) because the manually operated passive RHR system valves within the scope of this request do not have a safety function in the open position.
The proposed alternative testing will be performed at the OM Code Subsection ISTC-3700 frequency of at least once every two years. TVA may adopt OM Code cases that modify the two-year frequency when approved by the NRC or once endorsed in RG 1.192.
The licensee submitted Alternative Request BFN-IST-02 in accordance with 10 CFR 50.55a(z)(2) on the basis that compliance with valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee states that the manually operated passive RHR valves, within the scope of Alternative Request BFN-IST-02, do not have a safety function in the open position. The licensee proposes to continue to perform the proposed remote position indication testing and supplemental position indication in accordance with the frequency requirements of the ASME OM Code. The licensee intends to verify that the valve closed position indication accurately reflects the safety position of the valve with supplemental methods described in the alternative request. The licensee considers that this alternative will simplify the implementation requirements by reducing the scope of manual field work and dose impacts to operator crews while providing an acceptable level of quality and safety to demonstrate each valve can perform its credited design safety function. Figures 2 and 3 in Alternative Request BFN-IST-02 provide the detailed layout of the applicable valves in Browns Ferry Units 1, 2, and 3.
In Browns Ferry, Unit 2, a single crosstie valve is provided in the loop crosstie line (2-FCV-74-46) and is normally closed with power removed and has no credited open safety function. Testing will be performed to demonstrate the closed safety position indication with a supplemented observation by monitoring system pressure in the opposite loop during quarterly or comprehensive pump testing for anomalous pressure increases.
In Browns Ferry, Unit 3, two crosstie valves are provided in the loop crosstie line (3-FCV-74-46 and 3-SHV-74-150). Manually operated valve 3-SHV-74-150 remains in the closed position and has no credited open safety function. Valve 3-FCV-74-46 remains in the open position with motor operator power removed and has no credited open safety function. Valve 3-SHV-74-150 is normally closed to provide crosstie operation; however, either valve 3-SHV-74-150 or valve 3-FCV-74-46 may be used to perform this function. In the event 3-FCV-74-46 is utilized for Loop I to Loop II isolation instead of 3-SHV-74-150, supplemental verification testing in the closed safety position will be performed. Testing performed to demonstrate the closed safety position indication is supplemented by monitoring of system pressure in the opposite loop during pump testing for anomalous pressure increases.
The licensee asserts that supplemental position indication will be performed at the frequency specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700 for the closed (safety) position only. The licensee considers that this testing will demonstrate the valve will perform its closed safety function. The licensee asserts that demonstrating that the valve indicates mid-position will provide reasonable assurance that the reactor operators have indication if the valve is removed from its safety position.
The licensee states that failure of the stem-to-disk connection in the closed position would be evident when the crosstie valves are operated for infrequent operations or flushes. The licensee indicates that failure in the open or partially open position would be evident by pressure anomalies in the opposite RHR loop.
The licensee specifies that RHR shutdown cooling supply to fuel pool cooling system shutoff valves 1/2/3-SHV-74-91 do not have a safety function in the open position but have a safety function in the closed position. Valves 1/2/3-SHV-74-91 have a single closed position indicating light. The licensee considers that manually opening these valves to verify the closed indicating light extinguishes when the valves are partially opened is sufficient to demonstrate proper indication. The licensee states that position indication will be supplemented by pressure or flow measurement techniques. Alternatively, for the open non-safety position, supplemental verification will be performed when the valve is aligned for supplemental fuel pool cooling (FPC).
The licensee states that each of these manually operated passive valves has a safety function in the closed position and does not have a safety function in the open position. The licensee considers that remote position indication testing by verifying that the valve indicates closed and when partially opened that the closed indicating light extinguishes (for valves with a single closed indicating light) or indicates mid-position (for valves with both open and closed indicating lights) adequately demonstrate the ability of the indicating lights to properly indicate valve position.
Licensees Reason for Request The licensee states that due to the design of the RHR system (Figures 2 and 3 in Alternative Request BFN-IST-02) at Browns Ferry, limited provisions exist that could readily be used to perform supplemental position verification of the manually operated passive RHR valves in this alternative request, as required by 10 CFR 50.55a(b)(3)(xi). The valves within the scope of this request are normally closed (except for 3-FCV-74-46, which is normally open), and need to remain in the required position at all times when both loops of RHR are required to be operable for low pressure coolant injection (LPCI).
The licensee states that the manually operated passive RHR system valves within the scope of this request are required to maintain obturator position, for RHR system train/loop boundary purposes, and are not required to change obturator position to accomplish any required function for safe shutdown, maintain safe shutdown, or mitigate the consequences of an accident, and are considered passive. These valves are only taken out of the required safety positions for infrequent operations such as supplemental FPC and system flushes when the affected loops of RHR are not required for LPCI.
The licensee considers that the position verification requirement in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), to verify that valve operation, in both open and closed positions is impractical for the subject RHR valves due to the design configuration of the RHR system.
The licensee states that to satisfy the requirements of the 10 CFR 50.55a(b)(3)(xi), numerous manual and motor-operated valves, not typically relied upon for isolation, are required to isolate a portion of the system for supplemental verification. Because the system is water filled, any leakage through the isolation valves might not provide conclusive verification results. Due to the size of the valves (8-inch and 24-inch) and that they are water filled, radiography is not a viable option. Therefore, disassembly, extensive valve maintenance, or design modification of the system to facilitate testing would be necessary to perform the valve position indication testing as required by ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi).
Each of the RHR system valves, within the scope of this alternative request, needs to be locally manually operated. The licensee states that to satisfy the requirements of ASME OM Code, Subsection ISTC, paragraph ISTC-3700, extensive effort and dose is needed to fully open these valves.
3.3.2 NRC Staff Evaluation For the closed safety position of the RHR crosstie valves 2/3-FCV-74-46 and 3-SHV-73-150, the licensee proposes to supplement valve closure indication by monitoring system pressure in the opposite loop during pump testing.
For closed safety position of the RHR shutdown cooling supply to FPC system shutoff valves 1/2/3-SHV-74-91, the licensee proposes to manually open these valves to verify the closed indicating light extinguishes when the valves are partially opened. The licensee will provide supplemental position verification of valve closure indication by use of pressure or flow measurement techniques.
For the open non-safety position of RHR valves 2-FCV-74-46 and 3-SHV-73-150, the licensee proposes to manually open these valves to verify dual-indication when valves are partially opened.
For the open non-safety position of the RHR valve 3-FCV-74-46, the licensee proposes to manually close this valve to verify dual-indication when the valve is partially closed.
The licensee considers that supplemental indication is not required for the partial stroke open (to the non-safety position) because the manually operated passive RHR system valves within the scope of this request do not have a safety function in the open position.
In its letter dated June 1, 2023, in response to an NRC RAI, the licensee confirmed that the alternative testing will be performed at least once every 2 years as specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, and that the frequency will not be decreased unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case accepted in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The implementing procedures for the referenced Browns Ferry TS SRs specify the IST program required frequencies when the testing is credited for IST program compliance.
The licensee stated that the Surveillance Frequency Control Program (SFCP) process does not allow changing the frequencies of the Browns Ferry IST program unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case endorsed in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee relies on its administrative procedures to provide control to prevent unauthorized changes to IST required frequencies.
For the valves within the scope of Alternative Request BFN-IST-02, the NRC staff finds that compliance with the specified requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety because disassembly, extensive valve maintenance, or design modification of the system to facilitate testing would be necessary to perform the valve position indication testing as required. The NRC staff also finds that alternative, as described above, will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request.
3.3.3 Conclusion Based on the review described above, the NRC staff finds that the licensee has demonstrated that a hardship or unusual difficulty would exist to meet the valve position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 2 of this SE without a compensating increase in the level of quality and safety. The NRC staff also finds that Alternative Request BFN-IST-02 will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request. As a result, the NRC staff concludes that the licensees proposed Alternative Request BFN-IST-02 for the valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 2 of this SE meets the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the use of proposed Alternative Request BFN-IST-02 for the Fifth 10-Year Interval IST Program at Browns Ferry.
All other ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, for which an alternative was not specifically requested and authorized, remain applicable.
3.4 Alternative Request BFN-IST-03 3.4.1 Licensees Request
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Applicable Code Edition and Addenda===
As indicated in section 3.1.3 above, the NRC staff is approving the use of a later edition of the ASME OM Code. Therefore, the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a with conditions, will be applicable to the Fifth 10-Year Interval IST Program at Browns Ferry.
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Applicable Code Requirement===
ASME OM Code, 2020 Edition, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3700, Position Verification Testing, states:
Valves with remote position indicators shall be observed locally at least once every 2 yr to verify that valve operation is accurately indicated. Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation.
Position verification for active MOVs shall be tested in accordance with Division 1, Mandatory Appendix III.
ASME Code Components Affected Alternative Request BFN-IST-03 applies to valves identified in Table 3.
Table 3 Site/Unit Component ID Component Description Valve Type OM Code Class Valve Size OM Category Browns Ferry Units 1, 2, and 3 1/2/3-FCV-1-168 MS LN A DRN ISOL Ball 2
2 B
Browns Ferry Units 1, 2, and 3 1/2/3-FCV-1-169 MS LN B DRN ISOL Ball 2
2 B
Browns Ferry Units 1, 2, and 3 1/2/3-FCV-1-170 MS LN C DRN ISOL Ball 2
2 B
Site/Unit Component ID Component Description Valve Type OM Code Class Valve Size OM Category Browns Ferry Units 1, 2, and 3 1/2/3-FCV-1-171 MS LN D DRN ISOL Ball 2
2 B
Abbreviations ID: Identification number FCV: Flow Control Valve MS LN: Main Steam Line (MSL)
DRN: Drain ISOL: Isolation Licensees Proposed Alternative Request BFN-IST-03 and Basis for Use The licensees proposed Alternative Request BFN-IST-03 is as follows:
Supplemental position verification of the MSL drain valves in the open position will be satisfied by periodic performance of non-intrusive testing (e.g.,
radiography) in the safety position only.
The proposed alternative testing will be performed at the OM Code Subsection ISTC-3700 frequency of at least once every two years. MSL drain valve remote position indicators will be verified at least once every two years to verify that valve operation is accurately indicated. TVA may adopt OM Code cases that modify the two-year frequency when approved by the NRC or once endorsed in RG 1.192.
Based on industry and Browns Ferry experience, the licensee has replaced the existing MOVs with ball valves AOVs in Browns Ferry Units 1, 2, and 3. The AOV ball valves installed have a slotted ball valve design (i.e., the end of the stem fits into a slot in the ball). This design has no connection devices (e.g., pins or keys). The internals of the new AOV ball valves were selected specifically for use in the drain pathway.
Electric Power Research Institute (EPRI) Technical Report (TR) 3002019621, Susceptibility of Valve Applications to Failure of the Stem-to-Disk Connection, Revision 0 (ML22200A295) provides a technical basis for determining valves not susceptible to stem-disk separation. The NRC safety evaluation dated May 4, 2022, of this EPRI TR concluded that ball valves of this design are rugged, have very few failures, and may be considered not susceptible to stem-to-disk failure (ML22042A000). The licensee states that the verification methods described in the EPRI report for ball valves (e.g., stroking the valve while monitoring system pressure and/or flow) are not possible due to the Browns Ferry system design. However, the licensee considers radiography to be effective for these valves because there are no internal components (such as pins) that would not be visible in the image generated.
The licensee considers that additional testing in the non-safety direction (closed) of the valves within the scope of Alternative Request BFN-IST-03 would require more plant resources and radiation exposure, with no compensating increase in the level of quality and safety. The licensee asserts that supplemental position indication of the safety direction only is an acceptable alternative for these valves where testing in the non-safety direction provides an unnecessary burden without a compensating increase in the level of quality and safety. The licensee states that it will continue to perform required fail safe, stroke time, and remote position indication testing in accordance with the ASME OM Code and the Browns Ferry IST program for these valves.
Therefore, the licensee submitted Alternative Request BFN-IST-03 in accordance with 10 CFR 50.55a(z)(2) on the basis that compliance with valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Licensees Reason for Request:
The licensee states that due to the design of the Browns Ferry, Units 1, 2, and 3 main steam (MS) system, the main steam line (MSL) drain valves (Figure 4 of the submittal) do not have isolations, instrumentation for local system parameters, or test connections to perform supplemental position indication verification of the drain valves, as required by 10 CFR 50.55a(b)(3)(xi). The valves within the scope of this request are 2-inch AOV drain valves and located in inaccessible areas during plant operation. Each two-inch AOV drain valve has a parallel orifice, which cannot be isolated. The MSL drains function as part of the alternate leakage pathway and must open to allow for main steam isolation valve (MSIV) leakage to be routed to the holding volume of the main condenser.
The licensee states that the valves within the scope of Alternative Request BFN-IST-03 were not provisioned with nearby isolation or test connections to allow for testing with air or water during unit shutdowns. During unit shutdowns, this piping is voided through the secondary orifice pathway, which limits potential testing methods.
The licensee considers that the position verification requirement in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), is impractical to perform on each valve within the scope of Alternative Request BFN-IST-03 due to the design of MS and MSL drain line for AOVs, with no installed capability to verify individual valve obturator position with supplemental indications during unit operation or unit shutdown.
The licensee states that significant plant design changes (e.g., redesigning the MS and MSL drain system) would be necessary to perform the valve position indication testing as required by ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi).
3.4.2 NRC Staff Evaluation For the open position of the valves within the scope of Alternative Request BFN-IST-03, the licensee proposes that the supplemental position verification of the MSL drain will be satisfied by periodic performance of non-intrusive testing, such as radiography, in the safety position. For the closed position of these valves, the licensee asserts that additional testing of the non-safety direction (closed) would require additional plant resources and radiation exposure, with no compensating increase in the level of quality and safety.
At Browns Ferry, the valves within the scope of Alternative Request BFN-IST-03 have a slotted ball valve design (i.e., the end of the stem fits into a slot in the ball). The NRC staff safety evaluation dated May 4, 2022, of the EPRI TR 3002019621 concluded that ball valves of this design are rugged, have very few failures, and may be considered not susceptible to stem-to-disk failure (ML22042A000). The NRC staff finds that radiography is effective for these valves because there are no internal components (such as pins) that would not be visible in the image generated. The staff considers that additional testing of the non-safety direction (closed) of these valves would require additional plant resources and radiation exposure, with no compensating increase in the level of quality and safety. The staff notes that the licensee will continue to perform required fail safe, stroke time, and remote position indication testing of these valves in accordance with the ASME OM Code and the Browns Ferry IST program.
In its letter dated June 1, 2023, in response to an NRC RAI, the licensee confirmed that the alternative testing will be performed at least once every 2 years as specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, and that the frequency will not be decreased unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case accepted in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The implementing procedures for the referenced Browns Ferry TS SRs specify the IST program required frequencies when the testing is credited for IST program compliance.
The licensee stated that the Surveillance Frequency Control Program (SFCP) process does not allow changing the frequencies of the Browns Ferry IST program unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case endorsed in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee relies on its administrative procedures to provide control to prevent unauthorized changes to IST required frequencies.
For the valves within the scope of Alternative Request BFN-IST-03, the NRC staff finds that compliance with the specified requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety because significant plant design changes (e.g., redesigning the MS and MSL drain system) would be necessary to perform the valve position indication testing as required. The NRC staff also finds that the alternative, as described above, will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request.
3.4.3 Conclusion Based on the review described above, the NRC staff finds that the licensee has demonstrated that a hardship or unusual difficulty would exist to meet the valve position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 3 of this SE, without a compensating increase in the level of quality and safety. The NRC staff also finds that Alternative Request BFN-IST-03 will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request. As a result, the NRC staff concludes that the licensees proposed Alternative Request BFN-IST-03 for the valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 3 of this SE meets 10 CFR 50.55a(z)(2).
Therefore, the NRC staff authorizes the use of proposed Alternative Request BFN-IST-03 for the Fifth 10-Year Interval IST Program at Browns Ferry.
All other ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, for which an alternative was not specifically requested and authorized, remain applicable.
3.5 Alternative Request BFN-IST-04 3.5.1 Licensees Request
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Applicable Code Edition and Addenda===
As indicated in section 3.1.3 above, the NRC staff is approving the use of a later edition of the ASME OM Code. Therefore, the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a with conditions, will be applicable to the Fifth 10-Year Interval IST Program at Browns Ferry.
Applicable Code Requirements ASME OM Code, 2020 Edition, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3500, Valve Testing Requirements, states:
Active and passive valves in the categories defined in ISTC-1300 shall be tested in accordance with the paragraphs specified in Table ISTC-3500-1 and the applicable requirements of ISTC-5100 and ISTC-5200.
ASME OM Code, 2020 Edition, Subsection ISTC, paragraph ISTC-3700, Position Verification Testing, states:
Valves with remote position indicators shall be observed locally at least once every 2 yr to verify that valve operation is accurately indicated. Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation.
Position verification for active MOVs shall be tested in accordance with Division 1, Mandatory Appendix III.
ASME OM Code, 2020 Edition, Mandatory Appendix I, Inservice Testing of Pressure Relief Devices in Water-Cooled Reactor Nuclear Power Plants, paragraph I-1100, Applicability, states:
The requirements of this Appendix apply to certain pressure relief devices (included in Section III of the ASME Boiler and Pressure Vessel Code, hereinafter known as the BPVC).
ASME OM Code, 2020 Edition, Mandatory Appendix IV, Preservice and Inservice Testing of Active Pneumatically Operated Valve Assemblies in Nuclear Reactor Power Plants, paragraph IV-1200, Scope, states:
Certain active pneumatically operated valves and pneumatically operated power-operated relief valves (PORVs) within the scope of ISTA-1100.
ASME Code Components Affected Alternative Request BFN-IST-04 applies to the valves specified in Table 4.
Table 4 Site/Unit Component ID (Note 1)
Component Description Valve Type OM Code Class Valve Size OM Category Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-4 MS LN A RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-5*
MS LN A RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-18 MS LN B RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-19*
MS LN B RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-22*
MS LN B RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-23 MS LN B RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-30*
MS LN C RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-31*
MS LN C RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-34*
MS LN C RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-41 MS LN D RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-42 MS LN D RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-179 MS LN A RLF RV 1
6 B/C Browns Ferry Units 1, 2, and 3 1/2/3-PCV-1-180 MS LN D RLF RV 1
6 B/C Note 1: Main steam relief valves (MSRVs) with an automatic depressurization system (ADS) function are annotated with an asterisk (*).
Abbreviations ID: Identification number PCV: Pressure Control Valve MS: Main Steam LN: Line RLF: Relief RV: Relief Valve Licensees Proposed Alternative Request BFN-IST-04 and Basis for Use The licensees proposed Alternative Request BFN-IST-04 is as follows:
TVA proposes to test the MSRVs in accordance with the OM Code Mandatory Appendix I requirements for Class I Main Steam Pressure Relief Valves with Auxiliary Actuating Devices.
The licensee states that the Browns Ferry Units 1, 2, and 3 MSRVs are Target Rock Model 7567F pilot-operated safety/relief valves (S/RVs) with an auxiliary actuating device (Figure 5 of the submittal). These valves have been categorized in accordance with ASME OM Code, Subsection ISTC, paragraph ISTC-1300, Valve Categories, as Category B/C because they are capable of remote-manual operation when inlet pressure is below the valve setpoint and are self-actuated when the inlet pressure reaches the valve setpoint.
The licensee states that each Browns Ferry unit has 13 MSRVs with only 6 credited for remote-manual operation in the safety analysis for reactor pressure control at reactor coolant system pressures below the valve automatic set pressure. The Browns Ferry IST Program categorizes the MSRVs, within the scope of this alternative request, as OM Category B/C valves in order to simplify implementation of the ASME OM Code, Mandatory Appendix I.
The licensee specifies that the position indication in the control room related to remote-manual operation of the MSRVs indicates whether the air solenoid valve is energized or de-energized rather than indicating valve stem or valve obturator travel. Thermal and acoustic monitors are installed on the piping downstream of the MSRV to provide main control room indication that the valves are open or closed or experiencing seat leakage.
OM Code Category C check valves and safety/relief devices are excluded from ASME OM Code, Mandatory Appendix IV by paragraph IV-1300, Exemptions, subparagraph (c). The licensee reports that the auxiliary actuating device is not a traditional air-operated valve (AOV) design and, therefore, does not have the provisions for compliance with Mandatory Appendix IV.
The licensee asserts that ASME OM Code, Mandatory Appendix I, paragraph I-3310, Class1 Main Steam Pressure Relief Valves With Auxiliary Devices, provides sufficient test requirements to ensure the MSRVs within the scope of Alternative Request BFN-IST-04 are capable of remote-manual operation and automatic operation at their set pressure, including verification of the pressure integrity and stroke capability of the air actuator and verification of operation and electrical characteristics of position indicators. The licensee considers the testing required by Mandatory Appendix I to satisfy the intent of 10 CFR 50.55a(b)(3)(xi).
Therefore, the licensee submitted Alternative Request BFN-IST-04 in accordance with 10 CFR 50.55a(z)(2) in that compliance with 10 CFR 50.55a(b)(3)(xi) and ASME OM Code, Subsection ISTC, paragraphs ISTC-3500 and ISTC-3700, and Mandatory Appendix IV, represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Licensees Reason for Request The licensee states that the valves within the scope of Alternative Request BFN-ISI-04 are not suited to perform supplemental position indication verification as required by ASME OM Code, Subsection ISTC, and Mandatory Appendix IV, and 10 CFR 50.55a(b)(3)(xi). The licensee considers that application of ASME OM Code, Subsection ISTC, paragraphs ISTC-3500 and ISTC-3700, to the MSRVs might result in undesirable operational impacts (e.g., the potential for an inadvertent blowdown of the primary system during MSRV exercising, and the potential to increase operational leakage from the primary system).
In Alternative Request BFN-IST-04, the licensee proposes alternative IST testing for the valves within the scope of the request in accordance with 10 CFR 50.55a(z)(2). In its request, the licensee asserts that compliance with the ASME OM Code, Subsection ISTC, paragraphs ISTC-3700 and ISTC-3500, and Mandatory Appendix IV, and 10 CFR 50.55a(b)(3)(xi) for the valves within the scope of the request under the described circumstances would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.5.2 NRC Staff Evaluation ASME OM Code, Appendix IV, paragraph IV-1200, Scope, specifies that Appendix IV applies to certain active pneumatically operated valves and pneumatically operated PORVs within the scope of ASME OM Code, Subsection ISTA, General Requirements, paragraph ISTA-1100, Scope. Based on this scope statement, the licensee requested relief from Mandatory Appendix IV of ASME OM Code as incorporated by reference in 10 CFR 50.55a for the valves identified in Alternative Request BFN-IST-04. In Alternative Request BFN-IST-04, the licensee proposes to test the MSRVs within the scope of the request in accordance with Mandatory Appendix I in the ASME OM Code.
In its letter dated June 1, 2023, the licensee provided a response to an NRC RAI regarding use of Appendix I for open and closed position verification of the valves within the scope of Alternative Request BFN-IST-04.
In its response, the licensee explains that it has a methodology to demonstrate open and closed valve positions in accordance with ASME OM Code, Appendix I, paragraph I-3310. The manual actuation tests prescribed in Browns Ferry TS SRs 3.4.3.2 and 3.5.1.11 provide a demonstration of the mechanical operation of the safety/relief valves and overlaps with other testing to demonstrate that the functions of the S/RVs can be performed. These manual actuation tests are currently performed once per operating cycle (i.e., 24 months) corresponding to start-up from refueling outages. The S/RV manual actuation lift test is credited for demonstrating the mechanical functioning of the valve for the remote actuation mode and for the automatic depressurization function. These tests demonstrate that the air actuator strokes open to allow the pilot to actuate the main body, and that the air actuator closes and allows the main body to re-seat. Each MSRV tail pipe contains external systems for acoustic monitoring or temperature change to monitor open and closed positions by sensing steam flow conditions and providing indications of steam flow and cutoff during MSRV cycling.
The licensee states that ASME OM Code, Mandatory Appendix I, paragraph I-3310, requires, in part, that (a) visual examination, (b) seat tightness determination, if practicable, and (c) set-pressure determination, be performed prior to maintenance or set-pressure adjustment. The test requirements in ASME OM Code, Mandatory Appendix I, paragraphs I-3310(a), (b), and (c), do not impact remote position indication or supplemental position indication. The provisions in ASME OM Code, Mandatory Appendix I, paragraphs I-3310(d) through (i), are performed after maintenance or set pressure adjustment.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(d) requires the determination of electrical characteristics and pressure integrity of the solenoid valves. The licensee states that this will be accomplished by either manual exercise of the MSRV during low power operation or by ensuring each S/RV solenoid valve ports pneumatic pressure to the associated S/RV actuator when energized during in-situ testing.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(e) requires the determination of pressure integrity and stroke capability of the air actuator. The licensee states that this will be accomplished by either manual exercise of the MSRV during low power operation or by ensuring each S/RV actuator stem moves when manually lift tested during vendor certification.
With exception of the main and pilot stages, the licensee considers that this test demonstrates mechanical operation.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(f) requires the determination of operation and electrical characteristics of position indicators. The licensee states that this will be accomplished by either manual exercise of the MSRV during low power operation or by verifying remote position indication accurately reflects S/RV solenoid valve position during in-situ testing of electrical characteristics and pressure integrity of the solenoid valves.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(g), requires the determination of operation and electrical characteristics of bellows alarm switch. The licensee considers that this paragraph is not applicable to the Target Rock Model 7567F pilot-operated S/RV.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(h), requires the determination of actuating pressure of auxiliary actuating device sensing element, where applicable, and electrical continuity. The licensee considers that this paragraph is not applicable to the Target Rock Model 7567F pilot-operated S/RV.
ASME OM Code, Mandatory Appendix I, paragraph I-3310(i), requires the determination of compliance with the owners seat tightness criteria. The licensee states that the test requirements for paragraph I-3310(i) do not impact remote position indication or supplemental position indication.
The licensee states that each MSRV tail pipe contains external systems for acoustic monitoring or temperature change to monitor open and closed positions by sensing steam flow conditions and providing indications of steam flow and cutoff during MSRV cycling. Acoustic monitoring and thermocouple temperature monitoring instrumentation is monitored per Browns Ferry Technical Requirements Manual, Section 3.3.5.
Also in its letter dated June 1, 2023, the licensee confirmed that the alternative testing will be performed at least once every 2 years as specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, and that the frequency will not be decreased unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case accepted in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The implementing procedures for the referenced Browns Ferry TS SRs specify the IST program required frequencies when the testing is credited for IST program compliance. The licensee stated that the implementing procedures does not allow changing the frequencies of the Browns Ferry IST program unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case endorsed in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee relies on its administrative procedures to provide control to prevent unauthorized changes to IST required frequencies.
For the valves within the scope of Alternative Request BFN-IST-04, the NRC staff finds that compliance with the specified position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), and the testing requirements in ASME OM Code, Mandatory Appendix IV, would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety because the MSRV design configuration is not suited for implementation of OM Code Subsection ISTC requirements for remote position verification or Mandatory Appendix IV AOV testing. Application of ISTC-3500 and ISTC-3700 to MSRVs results in additional undesirable operational impact (e.g., the potential inadvertent blowdown of the primary system during MSRV exercise) and the potential to increase operational leakage from the primary system. The NRC staff also finds that alternative, as described above, will provide reasonable assurance of periodic position verification and operational readiness of the valves within the scope of the request.
3.5.3 Conclusion Based on the review described above, the NRC staff finds that the licensee has demonstrated that a hardship or unusual difficulty would exist to meet the position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), and the testing requirements in ASME OM Code, Mandatory Appendix IV, for the valves listed in Table 4 of this SE, without a compensating increase in the level of quality and safety. The NRC staff also finds that Alternative Request BFN-IST-04 will provide reasonable assurance of periodic position verification and operational readiness of the valves within the scope of the request. As a result, the NRC staff concludes that the licensees proposed Alternative Request BFN-IST-04 for the position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), and for the testing requirements in ASME OM Code, Mandatory Appendix IV, for the valves listed in Table 4 of this SE meets the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the use of proposed Alternative Request BFN-IST-04 for the Fifth 10-Year Interval IST Program at Browns Ferry.
All other ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, for which an alternative was not specifically requested and authorized, remain applicable.
3.6 Alternative Request BFN-IST-05 3.6.1 Licensees Request
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Applicable Code Edition and Addenda===
As indicated in section 3.1.3 above, the NRC staff is approving the use of a later edition of the ASME OM Code. Therefore, the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a with conditions, will be applicable to the Fifth 10-Year Interval IST Program at Browns Ferry.
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Applicable Code Requirement===
ASME OM Code, 2020 Edition, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3700, Position Verification Testing, states:
Valves with remote position indicators shall be observed locally at least once every 2 yr to verify that valve operation is accurately indicated. Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation.
Position verification for active MOVs shall be tested in accordance with Division 1, Mandatory Appendix III.
ASME Code Components Affected Alternative Request BFN-IST-05 applies to the valves identified in Table 5.
Table 5 Site/Unit Component ID Component Description Valve Type OM Code Class Valve Size OM Category Browns Ferry Unit 0 0-FCV-67-1 EECW HDR A STR BKWSH Ball 3
1.25 B
Browns Ferry Unit 0 0-FCV-67-5 EECW HDR B STR BKWSH Ball 3
1.25 B
Browns Ferry Unit 0 0-FCV-67-8 EECW HDR C STR BKWSH Ball 3
1.25 B
Browns Ferry Unit 0 0-FCV-67-11 EECW HDR D STR BKWSH Ball 3
1.25 B
Abbreviations ID: Identification number FCV: Flow Control Valve EECW: Emergency Equipment Cooling Water HDR: Header BKWSH: Backwash STR: Strainer Unit 0: valve is common to the three units Licensees Proposed Alternative Request BFN-IST-05 and Basis for Use The licensees proposed Alternative Request BFN-IST-05 is as follows:
For the open position, TVA will utilize continuous monitoring of the self-cleaning EECW strainer performance when the respective strainer is put into operation as supplemental verification of position indicating lights in the open position. The absence of strainer high differential pressure alarms when the respective strainer is in operation and illumination of the local open position indicating light verifies the respective EECW strainer backwash valve is open.
For the closed position, TVA will utilize continuous monitoring of self-cleaning EECW Strainer performance. The presence of a strainer high differential pressure alarm when the respective strainer is in operation will be used as an indication the respective EECW strainer backwash valve may have failed in the closed position. When the respective strainer is not in operation, verification the closed indicating light is illuminated and operator position indicators will be used to verify the respective EECW strainer backwash valve is closed.
The proposed alternative testing will be performed at the OM Code Subsection ISTC-3700 frequency of at least once every two years.
The licensee originally submitted Alternative Request BFN-IST-05 in accordance with 10 CFR 50.55a(z)(1) in that the proposed alternative provides an acceptable level of quality and safety. However, in response to an NRC RAI, the licensee stated that Alternative Request BFN-IST-05 should be processed in accordance with 10 CFR 50.55a(z)(2) on the basis that compliance with valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensee states that it may adopt OM Code cases that modify the 2-year frequency when approved by the NRC or once endorsed in Regulatory Guide (RG) 1.192.
The licensee specifies that the EECW strainer backwash valves (0-FCV-67-1, 5, 8, 11) have a safety-related function to open when their respective strainer is put into operation and to close when the strainer is not in operation in order to isolate the backwash and to prevent diversion of EECW supply from essential components.
The licensee considers that continuous monitoring for proper operation of the EECW strainers provides supplemental verification of the EECW strainer backwash valves in the open safety position. The licensee asserts that failure of a backwash valve to open would readily be detected by alarms on high strainer differential pressure. Alternatively, the presence of a strainer high differential pressure alarm when the respective strainer is in operation can be used as an indication the respective EECW strainer backwash valve may have failed in the closed position. When the respective strainer is not in operation, the licensee notes that verification that the closed indicating light is illuminated, and operator position will be used to verify the respective EECW strainer backwash valve is closed. Additionally, the strainer backwash valves are closed and de-energized during the performance of quarterly and comprehensive pump tests. Failure of the respective EECW strainer backwash to close would result in flow diversion and would be detected by the pump test.
The licensee states that the EECW strainer backwash valves (0-FCV-67-1, 5, 8, 11) were replaced with stainless steel ball valves with Limitorque motor actuators to be compliant with ASME OM Code, Appendix III. These ball valves have a one-piece ball and stem design. This design has no connection devices (such as pins or keys), or stem-to-disk connection to fail. The internals of the new ball valves were designed specifically for use in the EECW strainer backwash drain pathway. The ball valve body is top entry with socket weld end connections which allow the valve internals to be repaired or replaced without removing the entire assembly from the process line. ASME OM Code, Appendix III testing is not expected to provide data that can be used to satisfy 10 CFR 50.55a(b)(3)(xi) due to the ball valve design.
Electric Power Research Institute (EPRI) Technical Report (TR) 3002019621, Susceptibility of Valve Applications to Failure of the Stem-to-Disk Connection, Revision 0, (ML22200A295) provides a technical basis for determining valves not susceptible to stem-disk separation. The NRC safety evaluation dated May 4, 2022, of this EPRI TR concluded that ball valves of this design are rugged, have very few failures, and may be considered not susceptible to stem-to-disk failure (ML22042A000). The licensee states that the verification methods described in the EPRI report for ball valves (e.g., stroking the valve while monitoring system pressure and/or flow) are not possible due to the Browns Ferry system design. However, the licensee considers that the proposed monitoring approach to provide equivalent method to verify valve position.
Licensees Reason for Request The licensee states that EECW strainer backwash valves are MOVs located in the intake pumping station (Figure 6 of the submittal). The valves are installed on the backwash drain lines for the EECW strainers and do not have the installed capability to perform supplemental position verification as required by 10 CFR 50.55a(b)(3)(xi).
The licensee states that each EECW supply header has a continuous self-cleaning backwash strainer to minimize clogging of downstream cooler flow passages. The EECW strainer backwash valves automatically open when the strainer turns on to provide a discharge flow path from the strainer into the Wheeler Reservoir. There is instrumentation across the inlet and outlet of the strainer to alert the MCR when the pressure drop across the strainer is too high to operate safely. However, there is no annunciation in the main control room (MCR) for the position of the backwash drain valves.
The licensee considers that the position verification requirement in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), is impractical to perform on each valve in within the scope of Alternative Request BFN-IST-05 due to the design of EECW strainers drain line for MOVs, with no installed capability to verify individual valve obturator position with supplemental indications during unit operation or unit shutdown.
The licensee states that significant plant design changes (e.g., redesigning the EECW strainer drain line system) would be necessary to perform the valve position indication testing as required by ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi).
3.6.2 NRC Staff Evaluation For the open position, the licensee will use continuous monitoring of the self-cleaning EECW strainer performance when the respective strainer is put into operation as supplemental verification of position indicating lights in the open position. The absence of strainer high differential pressure alarms when the respective strainer is in operation and illumination of the local open position indicating light verifies the respective EECW strainer backwash valve is open.
For the closed position, the licensee will use continuous monitoring of self-cleaning EECW Strainer performance. The presence of a strainer high differential pressure alarm when the respective strainer is in operation will be used as an indication the respective EECW strainer backwash valve may have failed in the closed position. When the respective strainer is not in operation, verification that the closed indicating light is illuminated, and operator position indicators will be used to verify the respective EECW strainer backwash valve is closed.
Additionally, the licensee states that the strainer backwash valves are closed and de-energized during the performance of quarterly and comprehensive pump tests. Failure of the respective EECW strainer backwash to close would result in flow diversion and would be detected by the pump test.
At Browns Ferry, the valves within the scope of Alternative Request BFN-IST-05 have a one-piece ball and stem ball valve design and has no connection devices (i.e., pins and keys) or stem-to-disk connection to fail. The NRC staff safety evaluation dated May 4, 2022, of the EPRI TR 3002019621 concluded that ball valves of this design are rugged, have very few failures, and may be considered not susceptible to stem-to-disk failure (ML22042A000).
In its letter dated June 1, 2023, in response to an RAI request, the licensee states that the strainer backwash valves within the scope of Alternative Request BFN-IST-05 cannot fully comply with the requirements of 10 CFR 50.55a(b)(3)(xi). The licensee states that maintenance activities perform MOV diagnostic testing at an initial frequency of 104 weeks for the strainer backwash valves. This frequency will be adjusted as necessary in accordance with the requirements of ASME OM Code, Mandatory Appendix III, paragraph III-6440, Determination of MOV Functional Margin. The licensee implements the diagnostic testing activity to confirm that the strainer backwash valve setup meets the design requirements, and to verify local valve position and light position indication. However, the licensee indicates that MOV diagnostics are not sufficient to verify obturator position for the installed strainer backwash valve design.
The licensee states that the monitoring of system parameters and alarms during IST pump testing will be used to supplement remote position indication and will be credited during performance of emergency equipment cooling water pump testing for the respective strainer backwash valve. Specifically, the licensee asserts that the absence of strainer high differential pressure alarms when the strainer is in operation for IST pump testing will demonstrate that the valve is in the open position. The licensee also notes that the presence of a strainer high differential pressure alarm when the respective strainer is in operation for IST pump testing will be an indicator that the valve may have failed closed in the closed position.
In its RAI response, the licensee confirmed that the alternative testing will be performed at least once every 2 years as specified in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, and that the frequency will not be decreased unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case accepted in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The implementing procedures for the referenced Browns Ferry Technical Specification (TS) Surveillance Requirements (SRs) specify the IST program required frequencies when the testing is credited for IST program compliance. The licensee stated that process does not allow changing the frequencies of the Browns Ferry IST program unless authorized by the NRC in response to a 10 CFR 50.55a(z) alternative request, or by use of an applicable ASME OM Code Case endorsed in RG 1.192, as incorporated by reference in 10 CFR 50.55a. The licensee relies on its administrative procedures to provide control to prevent unauthorized changes to IST required frequencies.
For the valves within the scope of Alternative Request BFN-IST-05, the NRC staff finds that compliance with the specified requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety because significant plant design changes (e.g., redesigning the EECW strainer drain line system) would be necessary to perform the valve position indication testing as required. The NRC staff also finds that the alternative, as described above, will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request.
3.6.3 Conclusion Based on the review described above, the NRC staff finds that the licensee has demonstrated that a hardship or unusual difficulty would exist to meet the valve position testing requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 5 of this SE, without a compensating increase in the level of quality and safety. The NRC staff also finds that Alternative Request BFN-IST-05 will provide reasonable assurance of periodic verification of the position of the valves within the scope of the request. As a result, the NRC staff concludes that the licensees proposed Alternative Request BFN-IST-05 for the valve position verification requirements in ASME OM Code, Subsection ISTC, paragraph ISTC-3700, as supplemented by 10 CFR 50.55a(b)(3)(xi), for the valves listed in Table 5 of this SE meets the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the use of proposed Alternative Request BFN-IST-05 for the Fifth 10-Year Interval IST Program at Browns Ferry.
All other ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, for which an alternative was not specifically requested and authorized, remain applicable.
4.0 CONCLUSION
As set forth above, the NRC staff approves the use of the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, in accordance with 10 CFR 50.55a(f)(4)(iv) as the Code of record for the Fifth 10-Year Interval IST Program at Browns Ferry, Units 1, 2, and 3.
Additionally, the NRC staff determines that the proposed alternatives provide reasonable assurance that the component or system is operationally ready. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes proposed alternatives BFN-IST-01 through 05 at Browns Ferry, Units 1, 2, and 3 for the Fifth 10-Year Interval IST Program. All other ASME OM Code requirements for which an alternative was not specifically requested and approved remain applicable.
Principal Contributors: G. Bedi, NRR M. Breach, NRR T. Scarbrough, NRR Date: August 17, 2023
ML23219A154 NRR-028 OFFICE NRR/DORL/LPLII-2/PM NRR/DORL/LPLII-2/LA NRR/DEX/EMIB/BC NRR/DORL/LPLII-2/BC NAME KGreen RButler SBailey DWrona DATE 08/03/2023 08/15/2023 07/28/2023 08/17/2023