ML24225A051
| ML24225A051 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 09/13/2024 |
| From: | Scott Wall Plant Licensing Branch III |
| To: | Penfield R Vistra Operations Company |
| Wall S | |
| References | |
| EPID L-2023-LLR-0066 | |
| Download: ML24225A051 (10) | |
Text
September 13, 2024 Rod L. Penfield Site Vice President Vistra Operations Company LLC Perry Nuclear Power Plant 10 Center Rd., Mail Stop A-PY-A290 Perry, OH 44081-0097
SUBJECT:
PERRY NUCLEAR POWER PLANT, UNIT NO. 1 - ISSUANCE OF ALTERNATIVE REQUEST VR-9, REVISION 0, ASSOCIATED WITH THE FOURTH 10-YEAR INSERVICE TESTING INTERVAL (EPID L-2023-LLR-0066)
Dear Rod Penfield:
By letter dated December 8,2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23345A086), as supplemented by a letter dated April 15, 2024 (ML24106A007), Energy Harbor Nuclear Corp. (EHNC) submitted alternative request No. VR-9, Revision 0, to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternatives to specific inservice testing (IST) requirements in the 2012 Edition of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) at Perry Nuclear Power Plant (PNPP).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the EHNC requested to use the proposed alternative in request VR-9, Revision 0, on the basis that complying with the requirements of the ASME OM Code would result in hardship without a compensating increase in the level of quality and safety.
By order dated September 28, 2023 (ML23237B427), the NRC staff approved the license transfer of several EHNC-operated plants, including PNPP, from Energy Harbor Nuclear Generation LLC and EHNC to Energy Harbor Nuclear Generation LLC and Vistra Operations Company LLC (VistraOps, the licensee), as the licensed owner and operator, respectively.
By letter dated February 23, 2024 (ML24054A498), EHNC informed the NRC that:
Upon completion of the license transfer, VistraOps will adopt and endorse the outstanding commitments, licensing actions, applications, and similar items on the aforementioned docket numbers. VistraOps requests NRC continuation of the regulatory reviews and actions on these items.
On February 29, 2024 (ML24061A100), the EHNC informed the NRC that the transfer transaction would close on March 1, 2024. On March 1, 2024 (ML24057A092), the NRC staff issued Amendment No. 203 to reflect the license transfer. Accordingly, VistraOps is now authorized to act as an agent for Energy Harbor Nuclear Generation, LLC, and has exclusive responsibility and control over the physical construction, operation, and maintenance of the facility at PNPP.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes use of the licensees proposed alternative VR-9, Revision 0, for the remainder of the PNPP Fourth 10-year IST interval scheduled to end on May 17, 2029.
All other ASME Code, section XI, requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable.
If you have any questions, please contact the Project Manager, Scott Wall, at 301-415-2855 or e-mail at Scott.Wall@nrc.gov.
Sincerely, Jeffrey A. Whited, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-440
Enclosure:
Safety Evaluation cc: Listserv BRENT BALLARD Digitally signed by BRENT BALLARD Date: 2024.09.13 12:15:42 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUEST VR-9, REVISION 0 FOURTH 10-YEAR INSERVICE TESTING INTERVAL VISTRA OPERATIONS COMPANY LLC ENERGY HARBOR NUCLEAR GENERATION, LLC PERRY NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-440
1.0 INTRODUCTION
By letter dated December 8,2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23345A086), as supplemented by a letter dated April 15, 2024 (ML24106A007), Energy Harbor Nuclear Corp. (EHNC) submitted alternative request (AR)
No. VR-9, Revision 0, to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternative to specific 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) at Perry Nuclear Power Plant (PNPP) associated with the fourth 10-year inservice testing (IST) interval at Perry Nuclear Power Plant (PNPP).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the EHNC requested to use the proposed AR VR-9, Revision 0, on the basis that complying with the requirements of the ASME OM Code would result in hardship without a compensating increase in the level of quality and safety.
By order dated September 28, 2023 (ML23237B427), the NRC staff approved the license transfer of several EHNC-operated plants, including PNPP, from Energy Harbor Nuclear Generation LLC and EHNC to Energy Harbor Nuclear Generation LLC and Vistra Operations Company LLC (VistraOps, the licensee), as the licensed owner and operator, respectively.
By letter dated February 23, 2024 (ML24054A498), EHNC informed the NRC that:
Upon completion of the license transfer, VistraOps will adopt and endorse the outstanding commitments, licensing actions, applications, and similar items on the aforementioned docket numbers. VistraOps requests NRC continuation of the regulatory reviews and actions on these items.
On February 29, 2024 (ML24061A100), the EHNC informed the NRC that the transfer transaction would close on March 1, 2024. On March 1, 2024 (ML24057A092), the NRC staff issued Amendment No. 203 to reflect the license transfer. Accordingly, VistraOps is now authorized to act as an agent for Energy Harbor Nuclear Generation, LLC, and has exclusive responsibility and control over the physical construction, operation, and maintenance of the facility at PNPP.
2.0 REGULATORY EVALUATION
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.
Regulation 10 CFR 50.55a(z) states, in part, that alternatives to the requirements of 10 CFR 50.55a(f) may be used, when authorized by the NRC, if the licensee demonstrates:
(1) the proposed alternatives would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1
Applicable Code Edition and Addenda
The licensees IST Code of Record is the 2012 Edition Interval at PNPP, which started on May 18, 2019, and is scheduled to end on May 17, 2029.
3.2 Applicable Code Requirements The IST requirements of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a related to this AR, are as follows:
ASME OM Code, Subsection ISTC, Inservice Testing of Valves in Light-Water Reactor Nuclear Power Plants, paragraph ISTC-3510, Exercising Test Frequency, states, in part, that:
Active Category A, Category B, and Category C check valves shall be exercised nominally every three months, except as provided by paragraphs ISTC-3520, ISTC-3540, ISTC-3550, ISTC-3570, ISTC-5221, and ISTC-5222.
ASME OM Code, Subsection ISTC, paragraph ISTC-3522, Category C Check Valves, states, in part, that:
(c) If exercising is not practicable during operation at power and cold shutdowns, it shall be performed during refueling outages.
3.3 ASME Code Components Affected
In its submittal, the licensee requests alternative IST requirements for the following four check valves at PNPP:
Table 1 Component ID Component Description Code Class Valve Category 1B21-F032A Feedwater Header A Outboard Containment Isolation Check Valve 1
AC 1B21-F032B Feedwater Header B Outboard Containment Isolation Check Valve 1
AC 1N27-F559A Feedwater Header A Inboard Containment Isolation Check Valve 1
AC 1N27-F559B Feedwater Header B Inboard Containment Isolation Check Valve 1
AC Note: The feedwater check valves are Category C valves because they are self-actuating, as well as Category A valves because seat leakage is limited in the closed direction.
Valves with these characteristics are designated AC in the PNPP IST program.
3.4 Proposed Alternative VR-9, Revision 0 In AR VR-9, the licensee proposes an alternative to the IST requirements specified in paragraph ISTC-3522(c) of the ASME OM Code, Subsection ISTC, for the feedwater check valves (FWCVs) listed in Table 1 of this safety evaluation (SE) to perform the water leak rate testing on a staggered basis, such that two check valves of a single feedwater line are tested each refueling outage.
3.5 Licensees Basis for Use By letter dated March 26, 1999 (ML021840396), the NRC staff approved Amendment 105 for the PNPP to revise Technical Specification (TS) 5.5.12, Primary Containment Leakage Rate Testing Program, to state that the feedwater check valves will be tested in accordance with the IST program (TS 5.5.6). These check valves are to be water leak rate tested to satisfy the exercise close test requirements of the IST program. At PNPP, the exercise close testing includes a water leak rate test, with an acceptance criterion of less than or equal to 200 gallons per minute (gpm) per feedwater penetration, when tested at greater than or equal to 1.1 Pa, where Pa is the limit for the peak containment pressure during a loss of coolant accident and is used as the method to test for proper check valve closure (Category C exercised closed) and will also ensure no significant leakage (Category A leak testing). From 2003 to present, the licensee reports that the leakage tests performed for all four check valves met the less than or equal to 200 gpm acceptance criterion. When low pressure results are extrapolated to operating pressure levels and the valve leakage is determined to exceed the 200 gpm leakage criteria, the licensee performs a supplemental visual inspection with a borescope evaluation to check for any orifice type seat defects. The licensee states that this testing from refueling outage 1R13 (2011) to present found acceptable results during refueling outage 1R19 (2023) after having not performed the testing in refueling outage 1R18 (2021) as permitted by NRC-authorized Request VR-7 (ML21031A002) and its supplement (ML21053A010). The licensee describes these results in AR VR-9 to support its request for a staggered testing frequency for the subject check valves.
The licensee reports that the check valve visual inspection results to date have not found seating defects or missing material indicative of an orifice defect. These check valves are piston-style design with the most likely failure modes being failure to open, failure to close, and restricted motion. The licensee verifies that absence of these failure modes during visual inspections and exercising the check valve disc. The licensee asserts that a failure to open or restricted motion for these check valves would be self-evident during the on-line operating cycle.
The licensee states that a failure to close or orifice defect has not been observed during any inspections.
The licensee expects these check valves to perform their function based on valve design, likely failure modes, historical testing results at 1.1 Pa, and visual inspections performed to date.
Therefore, the licensee asserts that performing the water leak rate test on a staggered testing frequency is adequate to ensure functionality of the valves. In the event of a test failure on a feedwater check valve, the licensee states that the inboard and outboard check valves on the line not scheduled will be tested as an extent of condition.
3.6
Reason for Request
The four check valves listed in the Table 1 of this SE are normally open piston-style check valves that allow primary feedwater to the reactor vessel and maintain reactor water level within limits during all modes of operation. During a postulated accident, the safety-related valves are designed to close, thereby isolating, and preventing a loss of reactor coolant. There are two feedwater lines with each line consisting of an outboard (1B21-F032A or 1B21-F032B) and inboard (1N27-F559A or 1N27-F559B), containment isolation check valve.
The three types of tests for these check valves are exercise open, exercise close, and water leak rate. The licensee states that exercise open testing is performed by verifying expected feedwater flow into the reactor vessel using control room instruments and is not a part of this request. The licensee performs water leak rate testing to satisfy the exercise close test requirements of the IST program, which can only be performed during prolonged shutdowns when other sources of reactor water level control are available and area radiation levels are reduced. As such, the licensee considers testing during a refueling outage to be necessary in accordance with ASME OM Code, subsection ISTC, paragraph ISTC-3522(c).
The licensee states that performance of the water leak rate test requires qualified leak rate contractors, as well as carpenters to erect scaffolding. Depending on the leakage results, the licensee notes that supplemental visual inspections might be needed to support testing.
According to the licensee, this test is performed via a test rig by routing an air supply to each of the FWCV inspection appendages. When air is admitted through the FWCVs, personnel can perform a visual inspection of the disc and seating surfaces using a borescope that is inserted through a drain connection on the bottom of each valve. The licensee estimates the total accumulated dose for all testing and maintenance activities for these evolutions to be 4,000 millirem (mrem). The licensee asserts that testing during refueling will require additional dose resulting in a hardship without a compensating increase in the level of quality and safety.
3.7
NRC Staff Evaluation
As incorporated by reference in 10 CFR 50.55a, ASME OM Code (2012 Edition),
subsection ISTC, paragraphs ISTC-3510 and ISTC-3522(c), specify IST requirements for the exercising of check valves, including the testing intervals. In lieu of performing the specific check valve exercise testing required by the ASME OM Code, the licensee proposes to perform the water leak rate testing on a staggered basis, such that two check valves of a single feedwater line are tested each refueling outage. The licensee states that the testing of the specified check valves at PNPP during every alternate refueling outage will save significant radiological dose to plant personnel.
In the December 9, 2023, submittal, Table 1, VR-9 LLRT Acceptance Criteria and Data, provides leakage acceptance criteria and actual calculated leakage and visual inspection for refueling outages 1R13 (2011) through 1R19 (2023) for all four feedwater check valves, except 1R18 (2021) as specified in NRC-authorized AR VR-7 based on a COVID-19 hardship (ML21123A289). The calculated leakage rate of the FWCVs is much lower than the acceptance criteria, and visual inspection of the check valves has been satisfactory. In the April 15, 2024, supplement, the licensee provided responses to requests for additional information from the NRC staff regarding AR VR-9 with clarification as follows:
- 1.
The review of trend data indicates that both feedwater lines perform in a reasonably equal manner. As such, testing would align with division outage schedules to optimize system drains and As Low As Reasonably Achievable (ALARA) principles.
- 2.
Testing of the A feedwater line would occur in 1R20 (2025) and testing of the B feedwater line in 1R21 (2027).
- 3.
AR VR-9 does not propose an alternative method for verifying valve obturator movement.
- 4.
Water leak rate testing of the FWCVs is the method currently employed at PNPP to verify valve closure and would continue to be used as described in the request. This request seeks only to change the frequency of the exercising testing required by ISTC-3510.
- 5.
PNPP Fourth 10-Year Interval IST Program (ML20045E972) includes containment isolation valves 1B21-F032A/B and 1N27-F559A/B with testing to be performed every refueling outage with Refueling Justification (RO-12 in the PNPP IST Program) to document the justification for performance of the testing during a refueling outage in lieu of quarterly (online) or during cold shutdown in accordance with ISTC-3522(c). RO-12 will continue to be used to document that performance of this testing occurs only during refueling outages.
AR VR-9 would require performance of this test during refueling outages, but alters the frequency from every refueling outage to every other refueling outage for a feedwater line.
- 6.
TS 5.5.12 requires a program to be established to implement the leakage rate testing of primary containment as required by 10 CFR 50.54(o) and 10 CFR Part 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors, Option B, as modified by approved exemptions. TS 5.5.12 also lists program exceptions. One of the program exceptions is that the containment isolation check valves in the feedwater penetrations are tested in accordance with the IST Program. This exception is allowed by PNPP License Amendment 105 (ML021840396). These containment isolation valves are not tested under the Appendix J program. The ASME OM Code, Subsection ISTC, paragraph ISTC-3630, subparagraph (b)(4), is used to demonstrate that the check valves close to be capable of performing their safety function.
- 7.
PNPP License Amendment 105 revised the design and licensing basis of containment isolation valves in the feedwater system. Even though the acceptance criterion for these containment isolation check valves (piston check valves) leakage is 200 gpm, no maintenance has been required on the feedwater containment isolation check valve internals.
In AR VR-9, the licensee states that the check valve visual inspection results to date have not identified any seating defects or missing material indicative of an orifice defect. For these piston-style check valves, the most likely failure modes are failure to open, failure to close, and restricted motion. The absence of these failure modes is confirmed during visual inspections and exercising the disc using air during these inspections. A failure to open or restricted motion would be identified during the on-line operating cycle. The licensee reported that a failure to close has not been observed during any inspections nor has an orifice type defect been identified for these check valves at PNPP.
The NRC staff evaluated the licensees justification for these check valves to perform their safety functions based on valve design, failure mode evaluations, historical testing results, and visual inspections performed to date. From this information, the staff finds that performance of the water leak rate tests on a staggered testing frequency is adequate to provide reasonable assurance of the functionality of the check valves. In the event of a test failure on a feedwater check valve, AR VR-9 includes a provision that the inboard and outboard check valves on the line not scheduled for testing will be tested as an extent of condition. As a clarification, the licensee stated that exercise open testing is performed by verifying expected feedwater flow into the reactor vessel using control room instruments and is not a part of this request.
In support of its request, the licensee stated that the check valve exercise testing requires specialized external resources such as qualified leak rate contractors to perform the tests and carpenters to erect scaffolding for access to the valves. In addition, depending on the leakage results, the licensee noted that supplemental visual inspections might be required to support the testing. The NRC staff reviewed the licensees characterization of the hardship posed by the occupational health and safety concerns associated with the total accumulated dose for all testing and maintenance activities for these evolutions is estimated to be 4000 mrem during a refueling outage. The staff considers that requiring the check valves listed in the licensees submittal to be exercised every refueling outage represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Based on the information provided for the specific feedwater check valves at PNPP identified in the licensees submittal, the NRC staff finds that (1) previous testing and visual inspection of these check valves indicate their acceptable historical performance; (2) no current concerns with the performance of these check valves have been identified; (3) periodic maintenance activities are not modified by this request; and (4) a hardship exists for the performance of exercise testing of these check valves every refueling outage that is contrary to the health and safety of plant personnel.
NRC staff notes that the current PNPP fourth 10-year IST interval program (ML20045E972),
Note No. 13 provides the historical basis for the leak rate test acceptance criteria, listing a series of submittals that resulted in Amendment 105 to the PNPP TSs and the historical exception taken to Regulatory Guide (RG) 1.163, Performance-Based Containment Leak-Test Program, June 2023, Revision 1 (ML23073A154). The RG 1.163 requirements in the PNPP TS 5.5.12, Primary Containment Leakage Rate Testing Program, were replaced with Nuclear Energy Institute (NEI) 94-01, Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J, Revision 3-A (ML12221A202), with the conditions and limitations specified in NEI 94-01, Revision 2-A (ML100620847), when PNPP Amendment 185 (ML19022A324) was implemented.
Based on its review, the NRC staff has determined that the licensees AR VR-9 for performing water leak rate testing of FWCVs on a staggered basis, such that two check valves of a single feedwater line are tested each refueling outage for the four specified check valves at PNPP, is acceptable in accordance with 10 CFR 50.55a(z)(2). The staff finds that the performance history of these check valves provides reasonable assurance that the check valves listed in the licensees request will be operationally ready to perform their safety functions with the provisions of AR VR-9.
4.0 CONCLUSION
As set forth above, the NRC staff finds that AR VR-9, Revision 0, will provide reasonable assurance that the check valves at PNPP listed in the licensees request will be operationally ready to perform their safety functions during remainder of the PNPP fourth 10-year IST interval, which is scheduled to end on May 17, 2029. The NRC staff finds that complying with the specified IST requirements of the ASME OM Code for testing the check valves within the scope of AR VR-9, Revision 0, would result in a hardship without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC authorizes the use of AR VR-9, Revision 0, for remainder of the PNPP fourth 10-year IST interval scheduled to end on May 17, 2029.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), remain applicable.
Principal Contributors: G. Bedi, NRR T. Scarbrough, NRR Date: September 13, 2024
- via memo NRR-028 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EMIB/BC*
NAME SWall SRohrer SBailey DATE 08/09/2024 08/13/2024 08/07/2024 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME JWhited (BBallard for)
SWall DATE 09/12/2024 09/13/2024