ML24191A456
| ML24191A456 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/19/2024 |
| From: | Markley M NRC/NRR/DORL/LPL2-1 |
| To: | Coleman J Southern Nuclear Operating Co |
| References | |
| EPID L-2024-LLR-0016 | |
| Download: ML24191A456 (13) | |
Text
July 19, 2024
Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Company 3535 Colonnade Parkway, Birmingham, AL 35243
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT UNITS 3 AND 4 - REQUEST FOR RELIEF AND ALTERNATIVE REQUIREMENTS FOR SQUIB (EXPLOSIVELY ACTUATED) VALVES FIRST TEST INTERVAL (EPID NO. L-2024-LLR-0016)
Dear Jamie Coleman:
By letter dated February 15, 2024, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24046A230), as supplemented by letter dated May 7, 2024 (ML24128A245), Southern Nuclear Operating Company (SNC, the licensee) submitted requests (V34-IST-ALT-03 and V34-IST-ALT-03-R1) to the U.S. Nuclear Regulatory Commission (NRC) to authorize for relief from specified requirements of Title 10, Code of Federal Regulations (10 CFR), Section 50.55a and to authorize an alternative to the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) testing and replacement interval requirements for the squib (explosively actuated) valves in OM Code Sections ISTC-5260(c), ISTC-5260(e)(2), ISTC-5260(e)(3), and ISTC-5260(e)(4) on the basis that conformance with certain OM C ode requirements would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The proposed alternative would allow for no testing or replacement of the squib valve pyrotechnic charges or its associated electrical circuitry, and no disassembly for internal examination, during the first refueling outages for Vogtle, Units 3 and 4.
Specifically, Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 55.55a(z)(2), the licensee requested that the NRC authorize Alternative Request V34-IST-03-R1 for testing certain squib valves at Vogtle, Units 3 and 4, on the basis that compliance with the ASME OM Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality or safety.
SNC proposes to modify the requirement to test and replace at least 20-percent of the pyrotechnic charges used in explosively actuated valves at least once every two years. SNC requested an allowance to skip the tests that would normally be conducted during the first refueling outage (RFO) at each unit. The licensee stated that this would result in zero tests and replacements taking place during the first two years of the First Inservice Testing (IST) Interval for Vogtle, Units 3 and 4. SNC stated that the manufacturer of these charges (Collins Aerospace) has recently informed the industry that it will no longer be supporting replacement orders of the charges for the nuclear industry. Prior to this notification, SNC had elected to not keep extra charges in inventory, but instead to order additional charges as needed in time to
support the required testing. Consequently, SNC does not have spare charges available to replace those that are scheduled for testing during the first RFO of each unit. The proposed alternative would allow for no testing of explosive charges or their associated electrical circuitry, disassembly for internal examination, or replacement of the squib valve pyrotechnic charges during the first refueling outages for Vogtle, Unit 3 and Unit 4, with increased testing, disassembly for examination, and replacement during the second refueling outage for each unit.
The NRC staff has reviewed the subject request for relief and concludes, as set forth in the enclosed safety evaluation (SE), that conformance with the OM Code represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety . Therefore, the NRC staff authorizes proposed alternative V34-IST-03-R1 until the completion of the second refueling outage (RFO2) for Vogtle, Units 3 and 4. All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief from, or an alternative to, was not specifically requested approved in this subject request remain applicable.
If you have questions, please contact the Senior Project Manager, John Lamb, at 301-415-3100 or John.Lamb@nrc.gov .
Sincerely,
Michael T. Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulations
Docket Nos.: 52-025, 52-026
Enclosure:
Safety Evaluation
cc: ListServ
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
RELATED TO RELIEF REQUEST TO ASME OM CODE REQUIREMENTS
FOR EXPLOSIVELY ACTUATED VALVES
SOUTHERN NUCLEAR OPERATING COMPANY, INC.
GEORGIA POWER COMPANY
OGLETHORPE POWER CORPORATION
MEAG POWER SPVM, LLC
MEAG POWER SPVJ, LLC
MEAG POWER SPVP, LLC
CITY OF DALTON, GEORGIA
VOGTLE ELECTRIC GENERATING PLANT, UNITS 3 AND 4
DOCKET NOS.52-025 AND 52-026
1.0 INTRODUCTION
By letter dated February 15, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24046A230), as revised by letter dated May 7, 2024 (ML24128A245), Southern Nuclear Operating Company (SNC, the licensee) submitted requests (V34-IST-ALT-03 and V34-IST-ALT-03-R1) to the U.S. Nuclear Regulatory Commission (NRC) to authorize relief from specified requirements of Title 10, Code of Federal Regulations (10 CFR), Section 50.55a and to authorize an alternative to certain Inservice Testing (IST)
Program requirements in the 2012 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code), on the basis that conformance with certain OM Code requirements would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The requested relief and proposed alternative are associated with testing and replacement interval requirements for the squib (explosively actuated) valve pyrotechnic charges at the Vogtle Electric Generating Plant (Vogtle), Units 3 and 4, for the First 10-Year IST Interval Program. The submitted Alternative Request V34-IST-ALT-03, dated February 15, 2024, was superseded in its entirety by Alternative Request V34-IST-ALT-03-R1 submitted on May 7, 2024.
As stated in its letter dated May 7, 2024, the proposed alternative would modify the requirement to test and replace at least 20 percent of the pyrotechnic charges used in explosively actuated valves at least once every two years for the first refueling outage for Vogtle, Units 3 and 4, by requesting an allowance to skip the first refueling outage occurrence of testing and increase the number of test and replacements that would occur at the second occurrence. In addition, SNC proposes to similarly modify the requirement to disassemble for examination one squib valve of each size during the first refueling outage for Vogtle, Units 3 and 4, by requesting an allowance to skip the first refueling outage occurrence of disassembly for internal examination and increase the number of disassembly for internal examination that would occur at the second refueling outage.
Specifically, pursuant to subparagraph (2) in paragraph (z), Alternatives to codes and standards requirements, of Section 55a, Codes and standards, in Part 50, Domestic Licensing of Production and Utilization Facilities, to Title 10, Energy, of the Code of Federal Regulations (10 CFR 50.55a(z)(2)), the licensee requested to implement proposed Alternative Request V34-IST-ALT-03-R1 to perform a one-time deferral of the frequency for the testing and replacement of the squib pyrotechnic charges and the disassembly and inspection of the valve and actuator, as an alternative to specific requirements in the ASME OM Code on the basis that compliance with the testing requirements would result in a hardship without a compensating increase in the level of quality and safety.
2.0 REGULATORY EVALUATION
2.1 Background
The Vogtle, Units 3 and 4, Updated Final Safety Analysis Report (UFSAR), Revision 12 (ML23165A215), Section 5.4.8.1.3, Other Po wer-Operated Valves Including Explosively Actuated Valves Design and Qualification, states, in part, that:
Explosively-actuated valves have shear caps and are actuated by an explosive charge fired by an electrical signal.
The Vogtle, Units 3 and 4, UFSAR, Revision 12, Section 6.3.2.2.8.9, Explosively Opening (Squib) Valves, states, in part, that:
Squib valves are used to isolate the incontainment refueling water storage tank injection [IRWST] lines and the containment recirculation lines. In these applications, the squib valves are not expected to be opened during normal operation and anticipated transients. In addition, after they are opened it is not necessary that they re-close.
The type of squib valve used in these applications provides zero leakage in both directions. It also allows flow in both directions. A valve open position sensor is provided for these valves. The IRWST injection squib valves and the containment recirculation squib valves in series with check valves are diverse from the other containment recirculation squib valves. They are designed to different design pressures. The IRWST injection and the containment recirculation squib valves are qualified to operate after being submerged; this capability adds margin to the performance of the PXS [Passive Core Cooling System] in handling debris during long-term core cooling following a LOCA [Loss-of-Coolant Accident].
Squib valves are also used to isolate the fourth stage automatic depressurization system lines. These squib valves are in series with normally open motor operated gate valves. Actuation of these squib valves requires signals from two separate protection logic cabinets. This helps to prevent spurious opening of these squib valves. The type of squib valve used in this application provides zero leakage of reactor coolant out of the reactor coolant system [RCS]. The reactor coolant pressure acts to open the valve. A valve open position sensor is provided for these valves.
The Vogtle, Units 3 and 4, UFSAR, Revision 12, Section 13.6, Security, states, in part, that:
The explosive cartridge assembly used in the squib valves (see Subsection 6.3.2.2.8.9) has been determined by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) to be exempt (Reference 5 [ U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) letter to Westinghouse Electric Company, dated October 6, 2015, and associated Special Explosive Device Determination and exemption (ATF Reference No. 15-801205)]) from the requirements of 27 CFR 555 as special explosive devices pursuant to 27 CFR 555.32 for possession and use for their intended purpose in the AP1000 nuclear reactor passive safety system. However, the explosive materials used in their manufacture are subject to the provisions of 27 CFR, Part 555. Thus, any alterations to the explosive cartridge assembly will render this exemption void and any explosive mate rials removed from the explosive cartridge assembly are subject to the regulations of 27 CFR 555.
2.2 Regulations
The NRC regulations in 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 regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state, in part, that alternatives to the requirements of paragraphs (b) through (h) of this section 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 SNCs Alternative Request V34-IST-ALT-03-R1
Applicable ASME OM Code Edition
The ASME OM Code of Record at Vogtle, Units 3 and 4, is the 2012 Edition of the ASME OM Code as incorporated by reference in 10 CFR 50.55a for the Initial 10-Year Interval IST Program, that began on April 1, 2023, and ends on March 30, 2033.
ASME OM Code Components Affected
In its submittal dated May 7, 2024, SNC proposed alternative testing for the following valves:
Table 1: ASME Components Within Scope of Proposed Alternative V34-IST-ALT-03-R1
Component Number System Code Class OM Category 3/4-RCS-V004A, B, Automatic C, & D Depressurization 1 D System (ADS) 3/4-PXS-V118A & B Passive Core Cooling System (PXS) 3 D
3/4-PXS-V120A & B PXS 3 D
3/4-PXS-V123A & B PXS 1 D
3/4-PXS-V125A & B PXS 1 D
Applicable ASME OM Code Requirements
The IST requirements in the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, related to Alternative Request V34-IST-ALT-03-R1 are as follows:
ASME OM Code, Division 1, Section IST, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-5260(c), Explosively Actuated Valves, states:
At least 20% of the charges in explosively actuated valves shall be fired and replaced at least once every 2 yr [years]. If a charge fails to fire, all charges with the same batch number shall be removed, discarded, and replaced with charges from a different batch.
ASME OM Code, Division 1, Section IST, Subsection ISTC, paragraph ISTC-5260(e)(2) states:
At least once every 2 yr., one valve of each size shall be disassembled for internal examination of the valve and actuator.
a) This examination will verify the operational readiness of the valve assembly by evaluating the internal components for their operational functionality, ensuring the integrity of the individual components, and removing any foreign material, fluid, or corrosion in accordance with the Owners examination procedures.
b) All valves shall be disassembled for internal examination at least once every 10 yr.
ASME OM Code, Division 1, Section IST, Subsection ISTC, paragraph ISTC-5260(e)(3) states:
For the valves selected in the test sample for subparagraph ISTC-5260(c), the operational readiness of the actuation logic and associated electrical circuits must be verified for each sampled valve following removal of its charge. This verification must include confirmation that sufficient electrical parameters (voltage, current, resistance) are available for each actuation circuit.
ASME OM Code, Division 1, Section IST, Subsection ISTC, paragraph ISTC-5260(e)(4), states:
For the valves selected in the test sample for subparagraph ISTC-5260(c), the sampling must select at least one explosively actuated valve from each redundant safety train every 2 yr. Each sampled pyrotechnic charge shall be tested in the valve or a qualified test fixture to confirm the capability of the charge to provide the necessary motive force to operate the valve to perform its intended function without damage to the valve body or connected piping.
Proposed Alternative
In its letter dated May 7, 2024, SNCs proposed Alternative Request V34-IST-ALT-03-R1 that states, in part, that:
SNC proposes to modify the requirement to test and replace at least 20% of the pyrotechnic charges used in explosively actuated valves at least once every two years for the first refueling outage for Units 3 & 4 by requesting an allowance to skip the first refueling outage occurrence of testing and increase the number of test and replacements that would occur at the second occurrence. In addition, SNC proposes to similarly modify the requirement to disassemble for examination one squib valve of each size during the first refueling outage for Units 3 & 4 by requesting an allowance to skip the first refueling outage occurrence of disassembly for internal examination and increase the number of disassembly for internal examination that would occur at the second refueling outage. This would result in zero explosive charge tests, disassembly for internal examination, and replacements taking place during the first two years of the First IST Interval for Units 3 & 4, which would include the first refueling outage for each unit but SNC would then test and replace 100% of the squib valve explosive charges, and disassemble two valves of each size for internal examination, within the second 2 years of the First IST Interval.
Further, since no charges would be removed under the proposed alternative, the verification of operational readiness of the actuation logic and associated electrical circuits for each sampled valve following removal of its charge would also not be performed pursuant to ISTC-5260(e)(3).
Following the second two-year period, testing and replacement of the charges would resume at a normal rate of approximately 50% within each two-year period as originally required per ASME OM Code subparagraph ISTC-5260(c), ISTC-5260(e)(3) and ISTC-5260(e)(4). In addition, following the second two-year period, disassembly for internal examination, would resume at a normal rate of one valve of each size as originally required per ASME OM Code subparagraph ISTC-5260(e)(2).
=
Reason for Request===
Based on the SNC letter dated May 7, 2024, the NRC staff summarizes the licensees reason for the request as follows:
Currently, all known charges used in explosively actuated (squib) valves in post-2000 Generation III+ nuclear power facilities are sole sourced from a single company. Westinghouse Electric Company LLC (WEC) was notified on November 23, 2022, that the charge manufacturer, Collins Aerospace, would no longer supply explosive charges, and WEC then notified the licensee as the explosive charge squib valves are provided to Vogtle, Units 3 and 4, by WEC. There are currently no other AP1000 plants in the United States nuclear industry utilizing these valves. The licensee does not maintain an inventory of spare charges because they are used infrequently, have a short shelf life, and have an inservice life of eight years. In addition, they are hazardous and require special handling and storage. As a result, the licensee elected not to keep extra charges in inventory at Vogtle, Units 3 and 4, but decided instead to order additional charges through WEC as needed as the time to replace some of the charges for testing purposes came near. Therefore, SNC does not have charges available to replace those that are scheduled to be removed from valves currently in service at Vogtle, Units 3 and 4, to be test fired to meet the ASME OM Code requirements during the first refueling outage of each unit, unless a manufacturer that can supply charges prior to the first refueling outage for each unit is identified.
Technical Specifications require these valves to operable in modes 1 through 4. Thus, a return to power operation would not be allowed after testing. Similar hardship concerns exist with verification of the operational readiness of the actuation logic and associated electrical circuits, since there is potential for misfiring during this verification and with disassembly (which includes removal of the explosive charge) for examination of the squib valves. Any mishandling which might occur during the removal of the explosive charges could result in damage that would render the charge and the squib valve inoperable. With no replacement charges available, such an inoperability would also prevent a return to power operation.
Basis for Use
In its letter dated May 7, 2024, the licensee stated, in part, that:
Post-2000 plants that use pyrotechnically actuated valves all use similar valve designs. In these designs, a chemical charge is ignited within the valves actuator and the rapid expansion of the chemical reaction increases pressure within the actuator ultimately leading to failure of a retention pin causing, and allowing, the actuator to shear a cap within the valve body. The process depends upon the reliability of the chemical charge. Testing of these chemical charges found that, while chemical charges may degrade over time, they would not degrade to the point of unviability within the inservice life of the charge. Periodic testing of the charges only confirms
that no other degradation mechanisms are in play, which could not be simulated and tested during equipment qualification. However, the alternative testing schedule would result in testing of all squib valves within approximately 6 years of installation (May 2021 to spring 2027), i.e.,
within the manufacturers recommendations for the service life of the explosive charges.
Due to the amount of testing that was performed on charges from the same batches that are currently installed in the explosively actuated valves at Vogtle, Units 3 &4, and the successful results of those tests, there is reasonable assurance that the installed charges would actuate as required if called upon to do so by the circuitry of the valves.
The qualified in-service life for these squib valves is eight years. The Code requires only 20% of the charges in explosively actuated valves to be tested at each refueling outage, and only one valve of each size to be disassembled for internal examination, and thus acknowledges a service life of several cycles. With such a service life, testing at the first cycle is expected to show the valves continue to be operable. Thus, meeting the ASME OM Code testing and disassembly for internal examination requirement s at the first refueling outage (RFO1) does not provide an increase in the level of quality and safety that compensates for the lost operation of the power plant.
Duration of Proposed Alternative
The duration of Alternative Request V34-IST-ALT-03-R1 is until the completion of the second refueling outage (RFO2) for Vogtle, Units 3 and 4. In the letter dated May 7, 2024, SNC stated that RFO2 is included in the justification of the request since during RFO2, the squib valves that would have tested during RFO1 will be tested to get back on the required testing frequency.
3.2 NRC Staff Evaluation
The 2012 Edition of the ASME OM Code, Subsection ISTC, as incorporated by reference in 10 CFR 50.55a, requires explosively actuated valves to be periodically fired and their pyrotechnic charges replaced according to a prescribed schedule.
The 14-inch squib valves in the ADS in Vogtle, Units 3 and 4, perform safety-related functions to open as part of the phased depressurization of the RCS in AP1000 reactors to allow the gravity-driven PXS to provide cooling of the reactor core. The 8-inch PXS squib valves in Vogtle, Units 3 and 4, perform safety-related functions to open (1) to allow cooling water to be supplied to the reactor core from the IRWST; and (2) to allow recirculation of water from the containment sump to the reactor vessel for long-term core cooling. These safety-related squib valves are included in the preservice testing (PST) and IST Programs at Vogtle, Units 3 and 4.
Previously, SNC submitted a proposed alter native, VEGP 3 & 4-PST-ALT-01, (ML18333A356) to conduct alternative testing of the pyrotechnic charges used in explosively actuated valves during the PST period at Vogtle, Units 3 and 4. SNC identified three batches of pyrotechnic charges: one batch for each of the three sizes of the pyrotechnic charges specified as the 14-inch squib valve, 8- inch squib valve - high energy, and 8-inch squib valve - low energy. The alternative testing of these charges, depicted in Table 2 below, represented a significant percentage test sampling of the total charges in the specific batch for each charge size and would exceed the number required for PST by the ASME OM Code. The NRC concluded that this testing provided an acceptable level of quality and safety, and authorized VEGP 3 & 4-
PST-ALT-01, as described in the NRC safety evaluation (SE) dated March 26, 2019 (ML19071A238).
Table 2: VEGP Units 3 and 4, Explosively Actuated Valve Charge Testing per Purchase Specification
Batch Charge size Number in IST IST Number to Number plants (number (20%) (1/train) be Tested Fabricated per unit x units)
A 14" valves 8 (4 x 2) 2 4 8 16 B 8" valves - high 12 (6 x 2) 3 6 8 20 C 8" valves - low 4 (2 x 2) 1 2 8 12
Notes:
- 1. Each charge size is a single batch.
- 2. There are two sizes of charges for the 8" explosively actuated valves, high energy and low energy.
The PST treatment of the explosively actuated valves establishes a history of testing performance that serves as part of the licensees supporting basis for proposed Alternative Request V34-IST-ALT-03-R1.
The NRC staff reviewed the initial alternative dated February 15, 2024, proposed by the licensee to the applicable explosively actuated valve testing requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a. The NRC staff provided requests for additional information (RAIs) to clarify several aspects of the alternative request. In particular, the NRC staff requested the licensee to (a) descri be the hardship associated with satisfying the ASME OM Code requirements, (b) describe the plan to meet the other requirements in the ASME OM Code, and any adjustments related to compliance with those requirements, (c) clarify if an alternative was being requested for testing of squib valve charges during subsequent refueling outages, (d) provide specific information related to the service life of the currently installed squib valve charges, (e) discuss the notification of the unavailability of squib valve charges provided by the manufacturer, and (f) discuss the plans for contracting with an alternate manufacturer to obtain squib valve charges. In its submittal dated May 7, 2024, SNC responded to each of the individual RAI items, and submitted Alternative Request V34-IST-ALT-03-R1 to supersede its initial request.
In its letter dated May 7, 2024, SNC described the hardship associated with satisfying the ASME OM Code requirements for testing the explosively actuated valve charges because of limitations on the return to power operation for Vogtle, Units 3 and 4, that would result until replacement charges could be obtained and installed. In addition to the unavailability of replacement charges, SNC stated that concerns exist with verification of the operational readiness of the actuation logic and associated electrical circuits required by the ASME OM Code, because there is a potential for misfiring during this verification. With no replacement charges available, such a misfiring of the charge would result in valve inoperability. Further, the licensee stated that concerns exist with squib va lve disassembly (which includes removal of the explosive charge) for internal examination required by the ASME OM Code.
The NRC staff reviewed Alternative Request V34- IST-ALT-03-R1 and each of the detailed RAI responses provided by the license. The NRC staff fi nds that the information provided by SNC sufficient to support performance of these explosively actuated valves. The NRC staff finds the explosively actuated valves within the scope of Alternative Request V34-IST-ALT-03-R1 to have acceptable performance history. Additional supporting justification was provided in the licensees initial acceptance testing as de scribed in NRC safety evaluation (SE) dated March 26, 2019 (ML19071A238).
Based on its review of the proposed alternative V34-IST-ALT-03-R1 and the licensees RAI responses, the NRC staff finds that a hardshi p or unusual difficulty exists without a compensating increase in the level of quality and safety. Testing the subject explosively actuated valves to meet the ASME OM Code would lead to an inability to replace pyrotechnic charges thereby limiting a return to power operation. The NRC staff evaluated SNCs proposed alternative testing schedule and basis for justifying a one-time deferral of the testing requirements and finds the proposed alternative V34-IST-ALT-03-R1 acceptable to support the duration of the proposed alternative until the completion of the RFO2 for Vogtle, Units 3 and 4.
The NRC staff finds that the licensee has prov ided reasonable assurance that the subject explosively actuated valves will be capable of performing their safety functions until the end of the second refueling outage for Vogtle, Units 3 and 4. Based on the above, the NRC staff finds that the proposed alternative V34-IST-ALT-03-R1 satisfies 10 CFR 50.55a(z)(2) on the basis of hardship for specified ASME OM Code requirements for sample testing and associated activities for the subject explosively actuated valves at Vogtle, Units 3 and 4.
4.0 CONCLUSION
Based on the above, the NRC staff concludes that SNC has demonstrated in its proposed alternative V34-IST-ALT-03-R1 that a hardship or unusual difficulty, without a compensating increase in the level of quality and safety, would exist to perform the specified IST requirements for the explosively actuated valves in Table 1 of this SE at the required interval specified in the ASME OM Code prior to the end of the RFO2 at Vogtle, Units 3 and 4. The NRC also finds there is sufficient basis for concern for hardship with verification of the operational readiness of the actuation logic and associated electrical circuits, since there is potential for misfiring during this verification and with disassembly (which includes removal of the explosive charge) for examination of the squib valves.
Additionally, the NRC staff has determined that the proposed alternative will provide reasonable assurance that the explosively actuated valves in Table 1 of this SE will be operationally ready to perform their safety functions until the end of the RFO2 at Vogtle, Units 3 and 4.In the letter dated May 7, 2024, SNC stated that RFO2 is included in the justification of the request since during RFO2, the squib valves that would have tested during RFO1 will be tested to get back on the required testing frequency. Based on the above, the NRC finds the licensees planned restoration of testing acceptable.
Therefore, the NRC staff authorizes proposed Alternative Request V34-IST-ALT-03-R1 until the completion of the second refueling outage at Vogtle, Units 3 and 4.
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), in the subject request remain applicable.
Principal Contributors: Nicholas Hansing, EMIB/DEX/NRR Thomas Scarbrough, EMIB/DEX/NRR
Date: July 19, 2024
ML24191A456 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC NAME JLamb KGoldstein SBailey DATE 07/09/2024 07/19/2024 07/09/2024 OFFICE NRR/DRO/IQVB/BC NRR/DSS/SCPB/BC NRR/DORL/LPL2-1/BC NAME KKavangh MValentin MMarkley DATE 07/09/2024 07/10/2024 07/19/2024 OFFICE NRR/DORL/LPL2-1/PM NAME JLamb DATE 07/19/2024