RS-22-078, Response to Request for Additional Information for Quad Cities Relief Request RV-09, MSSVs
| ML22181B098 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 06/30/2022 |
| From: | Simpson P Constellation Energy Generation |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-22-078 | |
| Download: ML22181B098 (6) | |
Text
4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office June 30, 2022 10 CFR 50.55a RS-22-078 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265
Subject:
Response to Request for Additional Information for Quad Cities Relief Request RV-09, MSSVs
References:
- 1. Letter from P.R. Simpson (Constellation Energy Generation, LLC) to U.S.
NRC, "Submittal of Relief Requests Associated with the Sixth Inservice Testing Interval, dated February 17, 2022 (ADAMS Accession No. ML22048B569)
- 2. Email from R. Kuntz (U.S. NRC) to R. Steinman (Constellation Energy Generation), "RAI RE: Alternative RV-09, MSSVs," dated June 13, 2022 (ADAMS Accession No. ML22164A858)
In Reference 1, Constellation Energy Generation, LLC (CEG) submitted relief requests associated with the Sixth 10-Year Inservice Testing (IST) Program Interval for Quad Cities Nuclear Power Station (QCNPS). Alternative RV-09 seeks relief from American Society of Mechanical Engineers (ASME) Operation and Maintenance (OM) Code Division 1, Mandatory Appendix I, paragraph I-1320 using Code Case OMN-17. The request applies to the sixth 10-Year interval which begins on February 18, 2023, and is required by 10 CFR 50.55a(f)(4) to comply with the requirements of the 2017 Edition of the Code with no Addenda.
In Reference 2, the NRC requested additional information that is needed to complete review of the proposed relief request. The attachment to this letter provides the additional information requested. There are no regulatory commitments included in this letter.
U.S. Nuclear Regulatory Commission June 30, 2022 Page 2 Should you have any questions concerning this letter, please contact Ms. Rebecca L. Steinman at 630-657-2831.
Respectfully, Patrick R. Simpson Sr. Manager Licensing Constellation Energy Generation, LLC
Attachment:
Response to Request for Additional Information for Quad Cities Alternative RV-09, MSSVs cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Quad Cities Nuclear Power Station
ATTACHMENT Response to Request for Additional Information for Quad Cities Alternative RV-09, MSSVs EMIB-RAI-1 Requirement:
Division 1, Mandatory Appendix I, lnservice Testing of Pressure Relief Devices in Light-Water Reactor Nuclear Power Plants, paragraph I-1320, Test Frequencies, Class 1 Pressure Relief Valves, subparagraph (a) 5-Year Test Interval, which states:
Class 1 pressure relief valves shall be tested at least once every 5 years, starting with initial electric power generation. No maximum limit is specified for the number of valves to be tested within each interval; however, a minimum of 20% of the valves from each valve group shall be tested within any 24-month interval. This 20% shall consist of valves that have not been tested during the current 5-year interval, if they exist. The test interval for any installed valve shall not exceed 5 years. The 5-year test interval shall begin from the date of the as-left set-pressure test for each valve.
ASME OM Code Case OMN-17, Revision 1, Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves, Section 1, Test Frequencies, Class 1 Pressure Relief Valves, Subparagraph (a),
72-Month Test Interval, states, in part, that The test interval for any individual valve that is in service shall not exceed 72 months except that a 6-month grace period is allowed to coincide with refueling outages to accommodate extended shutdown periods for ASME OM Code 2015 Edition and prior. For ASME OM Code 2017 Edition and later, ISTA-3170 may be utilized to accommodate extended shutdown periods.
Issue:
Quad Cities Alternative Request RV-09, Section 5, Proposed Alternative and Basis for Use, first, second, and third paragraphs state:
As an alternative to the Code-required 5-year test interval per Division 1, Mandatory Appendix I, paragraph I-1320(a), QCNPS Units 1 and 2 have been utilizing NRC approved Alternative Request RV-05 (Reference 1). This Alternative Request allows QCNPS Units 1 and 2 to establish a six-year test interval for the subject Class 1 MSSVs provided each QCNPS unit adheres to the additional requirements stipulated within ASME CC OMN-17.
Constellation proposes that the subject MSSVs [Main Steam Safety Valves] be tested at least once every eight years from the date of the as-left set pressure test for each valve.
Additionally, Constellation proposes two modifications to the utilization of ASME CC [Code Case] OMN-17. The first change extends the CC OMN-17 testing interval from six years to eight years, with an allowed six-month grace period to coincide with the combined certification testing and refueling outage time periods, and with the interval not to exceed 8.5 years. The second change increases the minimum number of MSSVs from each valve group to be tested from 20% within any 24-month interval to 40% within any 48-month interval with the 40% population made up of MSSVs which have not been tested during the current 96-month interval, if they exist. The additional requirements stipulated within ASME CC OMN-17 will be retained.
At QCNPS, Units 1 and 2, Constellation implemented the fleet-wide SRV Best Practices program (Reference 3 Attachment 2) in 2010 and incorporated several enhancements between 2010 and
ATTACHMENT Response to Request for Additional Information for Quad Cities Alternative RV-09, MSSVs 2014 that resulted in improved MSSV setpoint drift performance. Continued improvements to this program further increase the MSSV reliability.
Request:
- 1. Discuss how the alternative would address valve testing results where drift is determined to be beyond the allowable limits (for example the testing interval would be adjusted to consistent with the ASME OM Code Case OMN-17 requirement).
- 2. Discuss whether the additional provisions within ASME OM Code Case OMN-17 will be retained at Quad Cities, specifically OMN-17, Section 1(c), Requirements of Testing Additional Valves, for each valve tested for which the as-found set pressure exceeds the Owner-established acceptance criteria.
- 3. Constellation proposes that the subject MSSVs be tested at least once every 8 years from the date of the as-left set pressure test for each valve, with 40% tested every 48 months. Clarify whether there will be at least one MSSV tested each refueling outage and what corrective action will be taken if an MSSV does not meet its test criteria.
CEG Response to Request EMIB-RAI-1.1:
When an as-found set-pressure test result failure is discovered, the failure will be documented in the Constellation Energy Generation, LLC (CEG) Corrective Action Program (CAP) and the requirements of OMN-17 Section 1(c) will be followed. This includes testing additional valves per Sections 1(c)(1) & (2) as well as evaluation of the failure following the guidance in Section 1(c)(3). This guidance states in part:
The Owner shall evaluate the cause and effect on system capability of valves that fail to comply with the set-pressure acceptance criteria. Based upon this evaluation, to address any generic concerns, the Owner shall determine the need for testing in addition to the minimum tests specified. Actions determined by the evaluation would be taken to address the failure. Returning the valve to a shorter test interval may be optionally implemented based on the failure and evaluation but is not required per the Relief Request.
CEG Response to Request EMIB-RAI-1.2:
The OMN-17 provisions in Section 1(c) will be retained.
CEG Response to Request EMIB-RAI-1.3:
The proposed relief request will allow for scheduling the MSSV testing such that at least 40% of the MSSVs are tested in one outage and none are tested in the subsequent outage, which leads to more than 24 months between tests. A valve setpoint test failure will be treated as described in CEG Response to Request EMIB-RAI-1.1. Since 2014, CEG has been collecting, trending and analyzing test, maintenance, inspection and performance data. ER-AA-400-1000, "Safety & Relief Valve (SRV) Testing, Tracking, and Trending," Section 4.6, "SRV Programmatic Feedback," describes methods used to optimize performance, ensure predictable performance and prevent failure.
ATTACHMENT Response to Request for Additional Information for Quad Cities Alternative RV-09, MSSVs EMIB-RAI-2 Requirements:
See EMIB-RAI-1 Issue:
Quad Cities Alternative Request RV-09, Section 5, third, fourth and fifth paragraphs, state:
At QCNPS, Units 1 and 2, Constellation implemented the fleet-wide SRV Best Practices program (Reference 3, Attachment 2) in 2010 and incorporated several enhancements between 2010 and 2014 that resulted in improved MSSV setpoint drift performance.
Continued improvements to this program further increase the MSSV reliability.
The SRV Best Practices program is comprised of methods and philosophies concerning maintenance, inspection and techniques which uses the MSSV [Main Steam Safety Valve]
manufacturer's recommended maintenance practices and enhancements identified by Constellation that have been broadly termed Best Practices. MSSV Best Practices are developed from the application of the EPRl/NMAC Safety and Relief Valve Testing and Maintenance Guide (Reference 2) and from internal fleet operational experience (OE).
The SRV best practices have been implemented through Constellation's oversight of the valve vendor's test and rebuild processes.
Major program elements include specific performance and inspection criteria and maintenance steps that exceed Original Equipment Manufacturer (OEM) specifications and/or Industry established guidelines. The main program elements include 1) Spring Testing, 2) Lapping Techniques and Tools, 3) Set Pressure Adjustment Methodology Precision, and 4) Internal Component Condition Variation Limitations. Collectively, use of these elements have supported a trend in improved setpoint retention of MSSVs in service at QCNPS.
Request:
- 1. Discuss whether the Constellation Best Practices program will include the latest industry experience with input from various groups, including the Safety Relief Valve Users Group, the BWR Owners Group, and other industry experts available in the recent EPRI Report dated July 2021.
CEG Response to Request EMBI-RAI-2:
CEG incorporates industry Operating Experience into our Best Practice Program.
CEG Best Practices procedural guidance, ER-AA-400-1000, "Safety & Relief Valve (SRV) Testing, Tracking, and Trending," assigns the corporate safety relief valve (SRV) Program Engineer the following responsibilities:
Develop, implement, and update the SRV program (3.1.1)
Maintain awareness of industry SRV issues (3.1.2)
Identify and investigate opportunities for program improvements (3.1.5)
ATTACHMENT Response to Request for Additional Information for Quad Cities Alternative RV-09, MSSVs Interface with Electric Power Research Institute (EPRI), Safety Relief Valve Users Group (SRVUG) and Target Rock Users Group (TRUG) (3.1.6)
Additionally, the procedure recommends the Site SRV Owner attend the annual SRVUG and TRUG meetings as a means of staying current with industry experience (3.3.12).
These practices ensure that the latest industry experience is identified, evaluated and captured, as appropriate, in the Best Practices Program.