ML20282A709
| ML20282A709 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/17/2020 |
| From: | Jennifer Dixon-Herrity Plant Licensing Branch IV |
| To: | Peters K Vistra Operations Company |
| Galvin D | |
| References | |
| EPID L-2020-LLR-0060 [COVID-19] | |
| Download: ML20282A709 (12) | |
Text
November 17, 2020 Mr. Ken J. Peters Senior Vice President and Chief Nuclear Officer Attention: Regulatory Affairs Vistra Operations Company LLC Comanche Peak Nuclear Power Plant 6322 N FM 56 P.O. Box 1002 Glen Rose, TX 76043
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NO. 2 - PROPOSED ALTERNATIVE TO THE REQUIREMENTS OF THE ASME OM CODE TO EXTEND THE INSERVICE TESTING PROGRAM INTERVAL FOR CERTAIN SNUBBERS (EPID L-2020-LLR-0060 [COVID-19])
Dear Mr. Peters:
By letter dated April 10, 2020, as supplemented by letter dated April 13, 2020, Vistra Operations Company LLC (the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of an alternative to certain American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code),
requirements at Comanche Peak Nuclear Power Plant, Unit No. 2 (Comanche Peak Unit 2).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR)
Section 50.55a(z)(2), the licensee requested to use the proposed Alternatives SNB-1 and SNB-2 on the basis that complying with the specified requirements would result in hardship or unusual difficulty. The licensee requested to extend the interval for performance of the inservice testing program for the functional testing and visual examination activities of snubbers at Comanche Peak Unit 2 listed in the request, from refueling outage 2RF18 in the spring of 2020 to refueling outage 2RF19 scheduled to occur in the fall of 2021.
On April 14, 2020, the NRC provided verbal authorization for proposed Alternatives SNB-1 and SNB-2 for a one-time extension of the operational readiness testing and visual examination intervals for the snubbers at Comanche Peak Unit 2, until refueling outage 2RF19, scheduled for the fall of 2021. As set forth in the enclosed safety evaluation, the NRC staff concludes that proposed Alternatives SNB-1 and SNB-2 will provide reasonable assurance that the snubbers at Comanche Peak Unit 2, listed in the licensees request, are operationally ready to perform their safety functions until refueling outage 2RF19. The NRC staff finds that compliance with the specified requirements in the ASME OM Code would result in hardship or unusual difficulty 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). If the licensee identifies a performance issue with any of the snubbers K. Peters listed in Alternatives SNB-1 and SNB-2, the licensee will be expected to take action to implement the requirements of the applicable ASME OM Code as incorporated by reference in 10 CFR 50.55a. This authorization will remain in effect until restart from refueling outage 2RF19 at Comanche Peak Unit 2 scheduled for the fall of 2021.
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 approved as part of Alternatives SNB-1 and SNB-2 remain applicable.
If you have any questions, please contact the Project Manager, Dennis Galvin, at 301-415-6256 or by e-mail at Dennis.Galvin@nrc.gov.
Sincerely, Jennifer L. Dixon-Herrity, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-446
Enclosure:
Safety Evaluation cc: Listserv Jennifer L.
Dixon-Herrity Digitally signed by Jennifer L. Dixon-Herrity Date: 2020.11.17 09:49:39 -05'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED ALTERNATIVES SNB-1 and SNB-2 REGARDING SNUBBER TESTING AND VISUAL EXAMINATION INTERVAL EXTENSION VISTRA OPERATIONS COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NO. 2 DOCKET NO. 50-446
1.0 INTRODUCTION
By letter dated April 10, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20101K726), as supplemented by letter dated April 13, 2020 (ADAMS Accession No. ML20104C062), Vistra Operations Company LLC (the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of an alternative to specific inservice testing (IST) program requirements in the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code), 2004 Edition through 2006 Addenda, for Comanche Peak Nuclear Power Plant, Unit No. 2 (Comanche Peak Unit 2).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.55a(z)(2), Hardship without a compensating increase in quality and safety, the licensee requested to use the proposed alternative on the basis that complying with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensee requested, in proposed Alternatives SNB-1 and SNB-2, authorization for a one-time extension of the operational readiness testing1 (SNB-1) and visual exanimations (SNB-2) of snubbers (also referred to as dynamic restraints) from refueling outage 2RF18 in the spring of 2020 to refueling outage 2RF19 in the fall of 2021 for specific snubbers in the IST program at the Comanche Peak Unit 2.
In proposed Alternative SNB-1, the licensee provided justification that compliance with the requirements in the ASME OM Code, Subsection ISTD, Preservice and Inservice Examination and Testing of Dynamic Restraints (Snubbers) in Light-Water Reactor Nuclear Power Plants, paragraph ISTD-5200, Inservice Operational Readiness Testing, to perform operational readiness testing of specific snubbers during refueling outage 2RF18 in the spring of 2020 would result in a hardship without a compensating increase in the level of quality and safety in accordance with 10 CFR 50.55a(z)(2).
1 Operational readiness testing may also be referred to as functional testing.
In proposed Alternative SNB-2, the licensee provided justification that compliance with the requirements in the ASME OM Code, Subsection ISTD, paragraph ISTD-4200, Inservice Examination, and the provisions in ASME OM Code Case OMN-13, Revision 0, Requirements for Extending Snubber Inservice Visual Examination Interval at LWR [Light-Water Reactor]
Power Plants, which is accepted in NRC Regulatory Guide (RG) 1.192, Operation and Maintenance Code Case Acceptability, ASME OM Code, as incorporated by reference in 10 CFR 50.55a, Codes and standards, to perform visual examinations of the specific snubbers during refueling outage 2RF18 in the spring of 2020 would result in a hardship without a compensating increase in the level of quality and safety in accordance with 10 CFR 50.55a(z)(2).
On April 14, 2020, the NRC provided verbal authorization (ADAMS Accession No. ML20105A353) for proposed Alternatives SNB-1 and SNB-2 for a one-time extension of the operational readiness testing and visual examination interval for the snubbers at Comanche Peak Unit 2 specified in the licensees submittal dated April 10, 2020, as supplemented by letter dated April 13, 2020. The verbal authorization documentation provided a summary of the NRC staffs evaluation for the proposed alternatives. This safety evaluation (SE) provides the details of the NRC staff review of proposed Alternatives SNB-1 and SNB-2.
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(g)(4), Inservice inspection standards requirement for operating plants, state, in part, that throughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the inservice inspection (ISI) requirements, set forth in Section XI of the editions and addenda of the ASME Boiler and Pressure Vessel Code (BPV Code) or ASME OM Code for snubber examination and testing that become effective subsequent to editions and addenda specified in 10 CFR 50.55a(g)(2) and (3) and that are incorporated by reference in 10 CFR 50.55a(a), to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The regulations in 10 CFR 50.55a(b)(3)(v)(B), Snubbers: Second provision, state that:
Licensees must comply with the provisions for examining and testing snubbers in Subsection ISTD of the ASME OM Code and make appropriate changes to their technical specifications or licensee-controlled documents when using the 2006 Addenda and later editions and addenda of Section XI of the ASME BPV Code.
The regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state, in part, that alternatives to the requirements of 10 CFR 50.55a(b) through (h) 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.
The applicable ASME OM Code of Record for the Snubber Program at Comanche Peak Unit 2 for the third 10-year IST Snubber Program interval, which is currently scheduled to end on April 19, 2022, is the 2004 Edition through the 2006 Addenda of the ASME OM Code as incorporated by reference in 10 CFR 50.55a.
3.0 TECHNICAL EVALUATION
3.1 The Licensees Proposed Alternative SNB-1, Snubber Operational Readiness Testing As incorporated by reference in 10 CFR 50.55a, ASME OM Code (2004 Edition through 2006 Addenda), Subsection ISTD, requires that snubbers shall meet (1) the inservice visual examination requirements in paragraph ISTD-4000, Specific Examination Requirements, (2) the inservice operational readiness testing requirements in paragraph ISTD-5000, Specific Testing Requirements, and (3) the service life monitoring (SLM) requirements in paragraph ISTD-6000, Service Life Monitoring. The specific IST requirements of the ASME OM Code related to this alternative request are as follows:
ASME OM Code, Subsection ISTD, paragraph ISTD-5200, states, in part, that Snubbers shall be tested for operational readiness during each fuel cycle [every 2 years].
ASME OM Code, Subsection ISTD, paragraphs ISTD-5240, Test Frequency, and ISTD-5260, Testing Sample Plans, specify the test frequency and testing sample plans, respectively.
ASME OM Code, Subsection ISTD, paragraph ISTD-5261, Sample Plans, states that: The snubbers of each DTPG [Defined Test Plan Group] shall be tested using either of the following:
(a) the 10% testing sample plan (b) the 37 testing sample plan.
ASME OM Code, Subsection ISTD, paragraphs ISTD-5300, The 10% Testing Sample Plan, and ISTD-5400, The 37 Testing Sample Plan, specify these testing sample plans.
ASME OM Code, Subsection ISTD, paragraph ISTD-6000, Service Life Monitoring, specifies SLM requirements.
In the submittal, as supplemented, the licensee requests a one-time extension of the operational readiness testing interval for the snubbers listed in Table 1, Snubber Tests Requested for Deferral to 2RF19, of proposed Alternative SNB-1, as supplemented, at Comanche Peak Unit 2. The licensee uses two DTPGs for snubbers in its IST program. The licensee uses (1) the 10% test plan for steam generator snubbers, designated as PM, and (2) the 37 testing sample plan for the rest of the snubbers, designated as PSA. The licensee noted that the service life for all Comanche Peak Unit 2 snubbers is based on 40 years of expected service (using the manufacturers recommendation), and is evaluated each refueling outage to make adjustments, if needed. Based on the performance of the Comanche Peak Unit 2 snubber population, there has not been a need to adjust the service life of any snubbers to date.
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Reason for Request===
In its request dated April 10, 2020, the licensee indicated that Comanche Peak Unit 2 was scheduled to begin refueling outage 2RF18 in the spring of 2020. The licensee reported that the snubbers listed in its request are functionally tested in accordance with the frequency
specified in ASME OM Code (2004 Edition through 2006 Addenda), Subsection ISTD, paragraph ISTD-5200, every 2 years. Therefore, these snubbers were scheduled to be functionally tested during the refueling outage in the spring of 2020.
On March 13, 2020, the President of the United States declared a national emergency due to the spread and infectious nature of the Coronavirus Disease 2019 (COVID-19) and resulting pandemic. The licensee stated that the most recent guidance at that time, from the Centers for Disease Control and Prevention (CDC), included recommendations for social distancing by maintaining approximately 6 feet from other personnel to limit the spread of the virus. In addition, the State of Texas, where Comanche Peak Unit 2 is located, issued an Emergency Disaster Declaration on March 23, 2020, to take actions necessary to reduce exposure to the virus associated with the COVID-19 virus outbreak. This declaration has subsequently been updated to mandate a 14-day self-quarantine period for air travelers flying to Texas from certain areas experiencing substantial spread of the COVID-19 virus. On March 28, 2020, the Department of Homeland Security identified workers in the nuclear energy sector as essential critical infrastructure workers.
The licensee stated that functional testing of the snubbers listed in its request during the spring 2020 refueling outage at Comanche Peak Unit 2 would represent a hardship during the COVID-19 outbreak. For example, the licensee intended to reduce the amount of onsite personnel to prevent the spread of COVID-19 at Comanche Peak Unit 2. The licensee was also contingency planning in the event that some of its workforce became unavailable due to the COVID-19 outbreak. Therefore, the licensee asserted that the testing of the specified snubbers at Comanche Peak Unit 2 during the spring 2020 refueling outage would result in a hardship without a compensating increase in the level of quality and safety in accordance with 10 CFR 50.55a(z)(2).
Proposed Alternative The licensee proposed a one-time extension of the IST program testing intervals for the snubbers listed in its request from the spring 2020 refueling outage (2RF18) to the next refueling outage for Comanche Peak Unit 2 currently scheduled for the fall of 2021 (2RF19).
In proposed Alternative SNB-1, to request a one-time extension of the operational readiness testing for the specified snubbers, the licensee provided information indicating that the service life (2033) of those snubbers extends beyond refueling outage 2RF19 scheduled for the fall of 2021. Further, the licensee reported that in the last 10 years, 241 snubbers have been tested with only four snubber test failures that occurred during the fall of 2018 (refueling outage 2RF17). The licensee evaluated those failures and took corrective action in accordance with the Comanche Peak corrective action program. The licensee reported that its evaluation of the failures concluded that the piping systems to which these snubbers are attached remained within their design parameters and would have fulfilled their safety functions. The licensee stated that the first failed snubber (RC-2-RB-028-701-1) was determined to be an isolated failure per ASME OM Code, Subsection ISTD, paragraph ISTD-5422, Isolated Failure, and was replaced with an acceptable spare snubber. The licensee stated that its evaluation of the second failed snubber (CS-2-RB-061-704-1) determined that this failure was due to a mishandling event or being struck by an external load, and was an isolated failure per paragraph ISTD-5422. The licensee indicated that this snubber was replaced by another acceptable spare snubber. The licensee reported that the failure of the third snubber (RC-2-135-402-C41K) was due to a possible damaged pin and spherical bearing, with dry grease found inside the snubber as a result of the high temperature of the piping to which it was
installed. Due to this snubber failure, the licensee expanded its sample to test 19 additional snubbers, and found no failures in the expanded group. The licensee stated that the failed snubber was replaced with an acceptable spare snubber with the snubber body mass installed away from the high temperature piping. The licensee reported that the fourth snubber (RC-2-018-402-C61K) was found to be missing a pin, and failed its functional test when removed for testing. The licensees analysis of the piping system, assuming that this snubber was disconnected, determined that the piping system was capable of performing its design functions, and was not adversely affected by this condition. The licensee replaced that snubber with a new spare snubber. Further, the licensee stated that one steam generator snubber (TCX-RCESHS-17) listed in proposed Alternative SNB-1 was previously tested with satisfactory results during refueling outage 2RF09 in the fall of 2006.
In proposed Alternative SNB-1, the licensee stated that the Comanche Peak Unit 2 operational readiness test history during the past 10 years shows that the snubber population is well maintained within the examination, testing, and SLM program. The licensee reported that there are no planned changes to the snubber environments or operating conditions that would affect the snubbers in a different manner than represented during the past surveillance testing. The licensee indicated that no deficiencies, adverse trends, or maintenance work orders have been identified that would impact or degrade any snubbers performance capability. The licensee stated that each snubber in the scope of this request will remain within the predicted service life interval, in accordance with ASME OM Code, Subsection ISTD, paragraph ISTD-6100, Predicted Service Life, through refueling outage 2RF19 scheduled for the fall of 2021, as determined during the refueling outage (2RF17) in the fall of 2018. Considering the entire snubber population and the current level of acceptable performance, the licensee considered that there is reasonable assurance that each snubber will continue to be operationally ready to perform its safety functions during the interval of this proposed alternative.
Overall, the licensee stated that the snubber population at Comanche Peak Unit 2 has been operating at a high level of performance for the past 10 years. The licensee asserted that the performance of these snubbers supports extending the one-time operational readiness test interval, and provided reasonable assurance that the snubbers are operationally ready to perform their safety functions.
NRC Staff Evaluation
In proposed Alternative SNB-1, the licensee provided justification that compliance with the requirements in ASME OM Code, paragraph ISTD-5200, as incorporated by reference in 10 CFR 50.55a, to conduct functional testing of specific snubbers at Comanche Peak Unit 2 during the spring 2020 refueling outage would result in a hardship without a compensating increase in the level of quality and safety in accordance with 10 CFR 50.55a(z)(2). The licensee reported that the service life expiration date for all snubbers specified in its request is at least 2030. Further, the licensee reported that in the last 10 years, 241 snubbers have been tested with only four snubber test failures that occurred during the fall of 2018 (2RF17). The licensee evaluated these failures and took corrective action per the Comanche Peak corrective action program, and all four snubbers were replaced with spare snubbers. Further, the licensee stated that one steam generator snubber (TCX-RCESHS-17) listed in proposed Alternative SNB-1, as supplemented was previously tested with satisfactory results during refueling outage 2RF09 in the fall of 2006. The licensee reported that its evaluation of the failures concluded that the piping systems to which these snubbers are attached remained within their design parameters and would have fulfilled their safety functions. The licensee stated that there have been no dynamic events or transients during plant operation since the previous refueling outage that
might affect snubber performance. Overall, the licensee demonstrated that the snubber population at Comanche Peak Unit 2 has been operating at a high level of performance for the past 10 years.
Based on the information described above for the specific snubbers at Comanche Peak Unit 2 listed in the licensees request, the NRC staff finds that (1) snubber population testing during the past 10 years indicates their acceptable historical performance; (2) ongoing inservice visual examination and testing activities have not identified snubber performance concerns, except an operating experience item related to steam generator snubbers that was addressed by the licensees corrective action program; (3) SLM activities of all snubbers is performed every refueling outage and service life maintenance activities will continue as needed; and (4) a hardship existed for certain IST program activities related to these snubbers during refueling outage 2RF18 in the spring of 2020 that would have been contrary to the health and safety of plant personnel.
Therefore, the NRC staff finds that the licensees proposed Alternative SNB-1 for a one-time extension of operational readiness testing for 39 specified snubbers at Comanche Peak Unit 2 in accordance with 10 CFR 50.55a(z)(2) will provide reasonable assurance that the snubbers will be operationally ready to perform their safety functions until refueling outage 2RF19 scheduled for the fall of 2021.
3.2 The Licensees Proposed Alternative SNB-2, Snubber Visual Examination As incorporated by reference in 10 CFR 50.55a, ASME OM Code (2004 Edition through 2006 Addenda), Subsection ISTD, requires that snubbers shall meet (1) the inservice visual examination requirements in paragraph ISTD-4000, (2) the inservice operational readiness testing requirements in paragraph ISTD-5000, and (3) the SLM requirements in paragraph ISTD-6000. Further, ASME OM Code Case OMN-13 allows a licensee to extend the visual examination of snubbers, if the provisions specified in OMN-13 are met. The specific IST requirements of the ASME OM Code related to this alternative request are as follows:
ASME OM Code, Subsection ISTD, paragraph ISTD-4200, states, that Snubbers shall be visually examined on the required schedule and evaluated to determine their operational readiness.
ASME OM Code, Subsection ISTD, subparagraph ISTD-4252(d), Subsequent Examination Intervals, states, in part, that the duration of examination intervals shall be in accordance with Table ISTD-4252-1, Visual Examination Table.
ASME OM Code Case OMN-13, Revision 0, allows licensees to extend the visual examination of snubbers, if all of the provisions specified in OMN-13 are met. The NRC accepts the use of ASME OM Code Case OMN-13, Revision 0, in RG 1.192 as incorporated by reference in 10 CFR 50.55a.
In the submittal, as supplemented, the licensee requests a one-time extension of the visual examination interval for the snubbers listed in Table 1, Snubber Visual Deferrals, of proposed Alternative SNB-2, as supplemented, at Comanche Peak Unit 2.
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Reason for Request===
In proposed Alternative SNB-2, the licensee noted that ASME OM Code, paragraph ISTD-4200, requires snubbers to be visually examined on a specified schedule to determine their operational readiness. With the use of Code Case OMN-13, the licensee indicated that the current interval schedule is 10 years. The licensee reported that Comanche Peak Unit 2 completed 100 percent of the visual examinations of the snubber population during refueling outage 2RF12 in the spring of 2011. The licensee stated that 317 visual examination of snubbers were performed during refueling outage 2RF17 in the fall of 2018, with the balance of 506 visual examinations originally scheduled to be completed during refueling outage 2RF18 in the spring of 2020. The licensee indicated that visual examinations not completed during refueling outage 2RF18 would exceed the 10-year interval allowed by ASME OM Code Case OMN-13 by approximately 6 months, if performed during refueling outage 2RF19 in the fall of 2021.
On March 13, 2020, the President of the United States declared a national emergency due to the spread and infectious nature of the COVID-19 and resulting pandemic. The licensee stated that the most recent guidance at that time from the CDC included recommendations for social distancing by maintaining approximately 6 feet from other personnel to limit the spread of the virus. In addition, the State of Texas, where Comanche Peak Unit 2 is located, issued an Emergency Disaster Declaration on March 23, 2020, to take actions necessary to reduce exposure to the virus associated with the COVID-19 virus outbreak. This declaration was subsequently updated to mandate a 14-day self-quarantine period for air travelers flying to Texas from certain areas experiencing substantial spread of the COVID-19 virus.
The licensee stated that visual examination of the snubbers listed in its request during the spring 2020 refueling outage at Comanche Peak Unit 2 would represent a hardship during the COVID-19 outbreak. For example, the licensee intended to reduce the amount of onsite personnel to prevent the spread of COVID-19 at Comanche Peak Unit 2. The licensee was also contingency planning in the event that some of its workforce became unavailable due to the COVID-19 outbreak. Therefore, the licensee asserted that visual examination of the specified snubbers at Comanche Peak Unit 2 during the spring 2020 refueling outage would result in a hardship without a compensating increase in the level of quality and safety in accordance with 10 CFR 50.55a(z)(2).
Proposed Alternative The licensee proposed a one-time extension of the visual examination intervals for the snubbers listed in its request from refueling outage 2RF18 during the spring of 2020 to the next refueling outage for Comanche Peak Unit 2 currently scheduled for the fall of 2021 (2RF19).
In proposed Alternative SNB-2, the licensee stated that since 2011, there have been 1140 visual examinations of program snubbers with only three visual examination issues identified. Of the three visual examination issues, the licensee reported that only three snubbers (RC-2-135-402-C41K, RC-2-018-402-C61K, and MS-1-RB-045-010-2) resulted in a test failure.
Snubber RC-2-135-402-C41K was observed to have a possible damaged pin and spherical bearing. Upon removal for testing, this snubber appeared to be locked; however, after testing was completed, the snubber was not locked, but was confirmed to have a significantly high drag value. The licensee randomly selected an expansion sample of 19 snubbers from similar
applications that were functionally tested. No other failures were found in the expansion sample. Snubber RC-2-018-402-C61K was found missing one of its load pins. Upon further inspection, it was determined this snubber would not hand stroke. The licensee removed the snubber for testing and replaced it with a new spare snubber. Snubber MS-2-RB-045-010-2 was reported as having been stepped on, and this condition was entered into the corrective action program. The snubber was unpinned, hand stroked through full travel, and inspected by a certified VT-3 inspector. The licensee determined that the noted condition was cosmetic only.
Therefore, the licensee reinstalled the snubber. The licensee documented and evaluated each of these three occurrences with action taken per the Comanche Peak corrective action program.
The licensee states that the one steam generator snubber (TCX-RCESHS-17) listed in Table 1, of proposed Alternative SNB-2, as supplemented, was previously tested with satisfactory results during refueling outage 2RF9 in the fall of 2006. During refueling outage 2RF11 in the fall of 2009, the licensee performed a scheduled maintenance on the reservoir fluid hoses attached to this snubber; however, a test was not performed at that time. The four steam generator snubbers (TCX-RCESHS-2, 4, 17 and 19) listed in Table 1 were last visually examined with satisfactory results during 2RF12 in the spring of 2011.
Overall, the licensee stated that the snubber population at Comanche Peak Unit 2 has been operating at a high level of performance for the past 10 years. The licensee asserted that the performance of these snubbers supports extending the one-time extension of the visual examination intervals for the snubbers listed in its request from the spring 2020 refueling outage (2RF18) to the next refueling outage for Comanche Peak Unit 2 currently scheduled for the fall of 2021 (2RF19).
NRC Staff Evaluation
In addition to using Code Case OMN-13 for Comanche Peak Unit 2, the licensee requested a one-timeextension of the visual examination intervals for the snubbers listed in its request from the spring 2020 refueling outage (2RF18) to the next refueling outage for Comanche Peak Unit 2 currently scheduled for the fall of 2021 (2RF19). The licensee stated that the Comanche Peak Unit 2 snubber examination and testing history during the past 10 years shows that the snubber population is well maintained within the examination, testing, and SLM program, and is performing well in the environment and operating conditions. The licensee indicated that there are no planned changes to the snubber environments or operating conditions that would affect the snubbers in a different manner than represented in the operating history. The licensee stated that there are no deficiencies, adverse trends, or maintenance work orders that would impact or degrade any snubbers performance capability. The licensee stated that each snubber included in the scope of proposed Alternative SNB-2 will remain within its predicted service life, in accordance with ASME OM Code, Subsection ISTD, paragraph ISTD-6100, Predicted Service Life, through the end of refueling outage 2RF19 as predicted during the fall of 2018 (refueling outage 2RF17). Considering the entire snubber population and the current level of acceptable performance, the licensee asserted that there is reasonable assurance that each snubber will continue to be operationally ready to perform its safety functions during the interval of this proposed alternative.
Based on the information described above, the NRC staff finds that (1) snubber population visual examinations during the past 10 years indicate acceptable historical performance of the snubbers within the scope of proposed Alternative SNB-2; (2) ongoing inservice visual examination activities have not identified snubber performance concerns, with specific snubber examination issues resolved by corrective action; (3) the licensee is implementing its SLM
program for all snubbers every refueling outage, and service life maintenance activities are not modified by this request; and (4) a hardship existed for the visual examination of these snubbers during the spring of 2020 that would have been contrary to the health and safety of plant personnel.
Therefore, the NRC finds that the licensees proposed Alternative SNB-2 for a one-time Snubber Program interval extension for the visual examinations of the specific snubbers at Comanche Peak Unit 2 listed in proposed Alternative SNB-2 from the spring 2020 refueling outage (2RF18) to the fall 2021 refueling outage (2RF19) will provide reasonable assurance that the specified snubbers will be operationally ready to perform their safety functions until the refueling outage in the fall of 2021, in accordance with 10 CFR 50.55a(z)(2).
4.0 CONCLUSION
On April 14, 2020, the NRC provided verbal authorization for proposed Alternatives SNB-1 and SNB-2 for a one-time extension of the operational readiness testing and visual examination intervals for the snubbers at Comanche Peak Unit 2, until refueling outage 2RF19, scheduled for the fall of 2021. As set forth above, the NRC staff concludes that proposed Alternatives SNB-1 and SNB-2 will provide reasonable assurance that the snubbers at Comanche Peak Unit 2, listed in the licensees request, are operationally ready to perform their safety functions until refueling outage 2RF19. The NRC staff finds that compliance with the specified requirements in the ASME OM Code would result in hardship or unusual difficulty 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). If the licensee identifies a performance issue with any of the snubbers listed in Alternatives SNB-1 and SNB-2, the licensee will be expected to take action to implement the requirements of the applicable ASME OM Code as incorporated by reference in 10 CFR 50.55a. This authorization will remain in effect until restart from refueling outage 2RF19 at Comanche Peak Unit 2 scheduled for the fall of 2021.
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 approved as part of Alternatives SNB-1 and SNB-2 remain applicable.
Principal Contributor: Gurjendra Bedi Date: November 17, 2020
- via e-mail OFFICE NRR/DORL/LPL4/PM*
NRR/DORL/LPL4/LA*
NRR/DNRL/NPHB/BC*
NRR/DORL/LPL4/BC*
NAME DGalvin PBlechman ABuford JDixon-Herrity DATE 10/27/2020 10/27/2020 9/4/2020 11/17/2020