L-MT-24-015, Response to Request for Additional Information - Alternative Request VR-09 for OMN-17
| ML24137A235 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/16/2024 |
| From: | Brown G Northern States Power Company, Minnesota, Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-24-015 | |
| Download: ML24137A235 (1) | |
Text
2807 West County Road 75 Monticello, MN 55362 May 16, 2024 L-MT-24-015 10 CFR 50.55a ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Response to Request for Additional Information - Alternative Request VR-09 for OMN-17 (EPID L-2023-LLR-0064)
References:
- 1) NSPM letter to NRC, "10 CFR 50.55a(z)(1) Request Regarding OMN-17, Revision 1, VR-09," dated November 13, 2023 (ADAMS Accession No. ML23317A222)
- 2) NRC email to NSPM, "Monticello - Final Request for Additional Information re: Alternative Request VR-09 for OMN-17," dated April 15, 2024 Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM") submitted a 10 CFR 50.55a(z)(1) request associated with the Monticello Nuclear Generating Plant (MNGP) Sixth 10-Year Inservice Test (IST) Interval on November 13, 2023 (Reference 1). In that request, NSPM proposed adopting two modifications to the American Society of Mechanical Engineers (ASME) Operations and Maintenance (OM) Code Case OMN-17, Revision 1, "Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves."
On April 15, 2024, the NRC identified the need for additional information (Reference 2). The enclosure to this letter provides NSPM's response to Reference 2.
Please contact Mr. Ron Jacobson at 612-330-6542 or ronald.g.jacobson@xcelenergy.com if there are any questions or if further information is needed.
Document Control Desk L-MT-24-015 Page 2 Summary of Commitments This l~.m,~kes no new commitments and no revisions to existing commitments.
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~* y;:>,>O Gregory D. Brown Plant Manager, Monticello Nuclear Generating Plant Northern States Power Company-Minnesota Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC
L-MT-24-015 Enclosure NSPM Page 1 of 11 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ALTERNATIVE REQUEST VR-09 FOR OMN-17
1.0 BACKGROUND
Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM") submitted a 10 CFR 50.55a(z)(1) request associated with the Monticello Nuclear Generating Plant (MNGP) Sixth 10-Year Inservice Test (IST) Interval on November 13, 2023 (Reference 1). In that request, NSPM proposed adopting two modifications to the American Society of Mechanical Engineers (ASME) Operations and Maintenance (OM) Code Case OMN-17, Revision 1, "Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves," (Reference 3).
On April 15, 2024, the NRC identified the need for additional information (Reference 2).
2.0 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION The NRC requests for additional information from Reference 2 are repeated in the following pages in italics.
EMIB-RAI-1 The precedents (as supplemented) cited in Alternative Request VR-09, Section 23 include the testing of safety relief valves (SRVs) at several nuclear power plants that share test information over the extended test intervals for individual valves. In this manner, the overall performance of the SRVs over the extended test intervals can be monitored for common cause issues. The licensee is requested to describe its plans to obtain similar performance information over the proposed test intervals for the applicable SRVs at MNGP.
Response to EMIB-RAI-1 Performance information over the proposed test intervals for the applicable SRVs will continue to be obtained for NSPMs population of SRVs. NSPM plans to continue its current practice of refurbishment, assembly, and testing of assembled SRV bodies and topworks at an off-site facility. Each tested SRV assembly is installed for a duration permitted by OMN-17. In accordance with the Technical Specifications (TS) and the In-service Test (IST) Program, performance information from the valve population is taken and trended.
NSPM plans to create an SRV program document providing guidance for determining maximum allowed in service time. The maximum in service time for each valve is considered dependent upon the following factors: OMN-17 allowed test interval, set pressure drift history, pilot and main seat leak tightness, and the number of test and operating lifts. The data from all
L-MT-24-015 Enclosure NSPM Page 2 of 11 valves is used and will continue to be used to monitor the performance of each SRV over their proposed extended test interval. Test results are analyzed for acceptability. Common cause issues are identified through trending and through code-required testing scope expansion and evaluation for any unsatisfactory SRV test results.
EMIB-RAI-2 The precedents (as supplemented) cited in Alternative Request VR-09, Section 23 provide details regarding SRV best practices programs at the various nuclear power plants, such as the application of guidance prepared by the Electric Power Research Institute, to support the extension of the SRV test intervals at each nuclear power plant. The licensee is requested to describe the SRV best practices program established at MNGP to support the extension of the SRV test intervals proposed in Alternative Request VR-09.
Response to EMIB-RAI-2 The NSPM SRV precision/critical maintenance practices are comprised of vendor procedures, lessons learned from operating experience (OE), and specific testing, maintenance, inspection, and repair criteria that are approved by NSPM (incorporated into vendor test/maintenance procedures through procurement documents). Maintenance practices include specific performance and inspection criteria and certain maintenance steps that exceed original equipment manufacturer (OEM) specifications and/or industry established guidelines.
Procedures for these elements include receipt inspection, predictive maintenance, SRV inspection, test system design, test sequence, test procedures, environmental conditions, spring assembly removal and inspection, cold bar seat tightness test, and set pressure test used at MNGP and at the vendor facility which align with the Electric Power Research Institute (EPRI) technical report, "Nuclear Maintenance Applications Center: Safety and Relief Valve Testing and Maintenance Guide" dated August 2015 (Reference 4). Testing is performed in accordance with 2017 ASME Code and OMN-17 for the MNGP Sixth Inservice Testing Interval.
NSPM is in the process of enhancing the NSPM SRV precision/critical maintenance practices to improve the SRV best practice elements and process described above. New techniques and technology for SRV testing and maintenance continue to be evaluated for implementation.
Further detail on current maintenance practices is provided in the response to EMIB-RAI-4(d).
EMIB-RAI-3 Alternative Request VR-09, Section 20, first paragraph, states, in part:
NSPM proposed to implement Code Case OMN-17, Revision 1, with two modifications, as follows: The first modification proposes that the MSRVs be tested at least once every eight
L-MT-24-015 Enclosure NSPM Page 3 of 11 years from the date of the as-left set pressure test for each valve, with a six-month grace period to coincide with the combined certification testing and [refueling] outage (RFO) time periods, for an interval not to exceed 8.5 years. The second modification changes the minimum number of MSRVs from the 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 MSRVs which have not been tested during the current 96-month interval, if they exist. The additional requirements stipulated within ASME Code Case OMN-17, Revision 1, will be retained.
(a) 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."
(i) Summarize the supporting basis for the changes being proposed at Monticello for the extension of MSRV testing from 6 years to 8.5 years.
(ii) Clarify any intended difference between the phrase six-month grace period to coincide with the combined certification testing and refueling outage (RFO) time periods above, and the 6-month grace period is allowed to coincide with refueling outages in the Code Case OMN-17.
(b) The alternative proposed a modification to Code Case OMN-17 to change the minimum number of MSRVs 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 consisting of MSRVs which have not been tested during the previous 96-month interval, if they exist.
(i) Summarize the supporting basis for the proposed changes at Monticello from testing at least 20 percent of the MSRVs every 24 months to 40 percent of the MSRVs within a 48-month period.
(ii) Clarify whether any MSRVs will be tested each refueling outage and what corrective action will be taken if an MSRV does not meet its test criteria.
Response to EMIB-RAI-3 (a)(i) The following discussion provides response to EMIB-RAI-3(a)(i), EMIB-RAI-3(b)(i),
EMIB-RAI-4(c), and EMIB-RAI-4(e).
The SRV performance history provided in Table 2 of Reference 1 provides the bases for the increase in the test interval from six to eight years and changes to the minimum number of SRVs tested in the valve group from 20% every 24 months to 40% every 48 months. The change to 40% every 48 months allows the scheduling flexibility
L-MT-24-015 Enclosure NSPM Page 4 of 11 discussed in the response to EMIB-RAI-3(b)(ii) but does not change the total number of SRVs tested every 48 months.
An evaluation reviewed the as-left and as-found setpoints for the SRV topworks tested from 2017 to 2023. Improvements were made to the SRV maintenance and testing strategy from 2010 to 2013 and results of the period reviewed demonstrate the effectiveness of those changes. From 2017 to 2023, 13 SRVs were removed and as-found tested and using the linear extrapolation method, 12 of 13 valves were projected to have lift set points within the +/- 3.0% as-found set pressure tolerance for more than 8.5 years. One valve had a projection of 7.2 years to reach the 3% tolerance. Continued use of OMN-17, which requires disassembly and inspection prior to the start of every test interval, and implementation of the NSPM SRV precision/critical maintenance practices, are expected to further improve valve performance. SRVs with low projected service life will be evaluated for use and may be tested at intervals less than 8 years.
The proposed alternative is to extend the OMN-17 6-year test interval (a maximum of 6.5 years should the OMN-17 allowed maximum grace period be used) to 8 years (a maximum of 8.5 years with grace).
(a)(ii) There was no intended difference between the alternative request (Reference 1) and OMN-17 on the use of grace. NSPM will apply grace for SRV testing only as allowed by OMN-17. OMN-17 specifies usage based on applicable ASME OM Code edition. For the Sixth Inservice Testing Interval at MNGP the 2017 ASME OM Code is the Code of Record, thus OMN-17 specifies ISTA-3170 applicability. The 2017 ASME OM Code specifies in ISTA-3170, "Inservice Examination and Test Frequency Grace," that test frequency periods greater than or equal to 2 years may be extended by up to 6 months.
(b)(i) Refer to the response provided for EMIB-RAI-3(a)(i).
(b)(ii) With supporting performance history, NSPM may not test SRVs every refueling outage in order to obtain the maximum radiological benefit. There are four SRVs on each side of the 951 elevation in the Drywell. Scaffolding and shielding used for SRV removal are installed by hemisphere within the Drywell. If no SRVs are being removed in that half of the Drywell, then the scaffolding and shielding may not be installed during the given refueling outage. Approximately 1 Rem is accrued to install the scaffolding and shielding on each side of the drywell. Additionally, there are rigging challenges for some SRVs. In some cases, an SRV must be removed to access another for testing.
If an SRV does not meet its as-found set-pressure criteria in accordance with OMN-17, then two additional SRVs as required will be tested. If either of these two additional SRVs are found to not meet their as-found set-pressure criteria, then all remaining SRVs within the same valve group shall be tested. All SRVs at MNGP are in the same valve group. An SRV that does not meet its as-found set-pressure criteria will still be evaluated per OMN-17, which requires evaluating the cause and effect on system capability of valves that fail to comply with the set-pressure acceptance criteria or the
L-MT-24-015 Enclosure NSPM Page 5 of 11 acceptance criteria for other tests, and addressing any generic concerns, including the need for additional testing.
EMIB-RAI-4 Alternative Request VR-09, Section 20, second, third, fourth, fifth, sixth paragraphs, states:
NSPM has incorporated the guidance of 2015 EPRI Technical Report (TR) "Nuclear Maintenance Applications Center: Safety and Relief Valve Testing and Maintenance Guide" Revision of TR 105872, Technical Report 3002005362, into the procedures for receipt inspection requirements, predictive maintenance, and inspection of the MSRVs.
NSPM recently performed an evaluation of the performance of the Target Rock MSRVs.
It was concluded that there was reasonable assurance that the required setpoint drift tolerance of +/- 3% would be met after extending the test interval from the current six-year interval to a proposed eight-year interval.
This assessment reviewed as-left/as-found set pressure data going back to 2017 and identified; (1) Whether the valves' set pressure drifted up or down, and (2) The absolute set pressure change between tests. Based on the time between the as-left and as-found set pressure test of each MSRV, the set pressure drift was then linearly extrapolated to determine whether the MSRV's set pressure would still be within the site's required +/- 3%
tolerance band following an eight-year period. Table 2 summarizes the setpoint drift projection, in years of service, predicting when each MSRV would exceed the+/- 3% set pressure tolerance band for MSRVs removed and tested since 2017.
Table 2 also includes as-left testing for setpoint for each MSRV. The NSPM MSRV precision/critical maintenance practices are developed from the application of the EPRI/NMAC Safety and Relief Valve Testing and Maintenance Guide (Reference 2) and from NSPM Operational Experience (OE). The NSPM MSRV precision/critical maintenance has been implemented through NSPM's oversight of the valve vendor's test and rebuild processes.
Extending the test interval from six to eight years and revising the intervening outage testing sample size and frequency are acceptable based upon past MSRV performance. The ASME OM Code requires additional valves to be tested if as-found values are outside the acceptable range. For each MSRV tested at MNGP for which the as-found set pressure exceeds the greater of either the plus/minus tolerance limit of the established set-pressure acceptance criteria or+/- 3% of MSRV nameplate set-pressure, two additional MSRVs are tested from the same valve group. If the as-found set-pressure of any of the additional MSRVs tested exceeds the criteria, then all the remaining valves of that same group will be tested.
(a) Describe the elements/details used from the EPRI Report to develop into the procedures for receipt inspection requirements, predictive maintenance, and inspection of the MSRVs, to support the proposed alternative.
L-MT-24-015 Enclosure NSPM Page 6 of 11 (b) Does NSPM rely on any other aspect of the EPRI Report? If so, please summarize that aspect of the report.
(c) Explain the results of the evaluation of the performance of the Target Rock MSRVs to support the proposed alternative.
(d) Describe the element/details used to develop (1) The NSPM MSRV Precision/Critical Maintenance practices, from the application of the EPRI/NMAC Safety and Relief Valve Testing and Maintenance Guide and (2) from NSPM Operational Experience (OE).
(e) Explain the basis for accepting to extend the test interval from 6 to 8 years and revising the intervening outage testing sample size and frequency based upon past MSRV performance.
(f) Clarify the basis for +/- 3% set point pressure tolerance.
Response to EMIB-RAI-4 (a) MNGP conducts the following, which align with elements of the EPRI report:
Receipt Inspection Receipt inspection is performed in accordance with the requirements of the NSPM quality assurance program and aligns with elements of the EPRI report, Section 5.2.2.2, "PRV [Pressure Relief Valve] Receipt Inspection," by inspecting the condition of the shipping container and SRV, verifying that all components are received and sealed as expected, and documenting and reporting any unacceptable conditions. The SRV assembly is stamped with serial numbers that are tracked throughout the maintenance process.
Predictive Maintenance MNGP predictive maintenance aligns with elements of the EPRI Report, Section 6.1, "Predictive Maintenance and Inspection." The storage requirements in effect at MNGP ensure the valves are protected from exposure to the environment, airborne contamination, acceleration forces, and physical damage. Inspection is performed at the vendor for conditions and indications on the pressure retaining bolting, flange surfaces, and internal pressure boundary surfaces. Temperature Monitoring is performed (SRV tailpipe) using permanently installed thermocouples. A temperature baseline has been developed for each SRV.
Inspection Monticello SRV inspection activities align with elements of the EPRI Report, Section 6.3, "Preventive Maintenance (PM) Inspection." Prior to removal from the plant, the inlet and discharge flanges and the associated studs and nuts are inspected. The MNGP inspection procedure includes inspection of all removed gaskets for evidence of leakage or improper orientation.
L-MT-24-015 Enclosure NSPM Page 7 of 11 At the vendor facility the valves are inspected prior to testing and refurbishments.
Following testing and refurbishment the valve is inspected for cleanliness and sealed prior to shipping.
SRVs are subject to ASME Section XI inspection activities (ISI) in addition to ASME OM Code tests (IST).Section XI activities include nondestructive examination (typically PT, MT, VT for SRV maintenance), repair/replacement (for pressure boundary items),
and Authorized Nuclear Inservice Inspector (ANII) review of repair/replacement activities. MT and PT examinations of SRVs are typically associated with a welded and/or machined repair of the valve bodies or the installation of new bellows.
SRV valves that are overhauled are subject to National Board Valve Repair ("VR")
Quality Control program manual inspections. As discussed in the EPRI Report, Minnesota is a VR state, therefore SRV inspection, repair and setpoint adjustment activities must comply with National Board Requirements.
(b) MNGP aligns with elements of several other sections of the EPRI Report. The test system design, testing sequence, testing procedures, environmental conditions, spring assembly removal and inspection, cold bar seat tightness test, and set pressure test used at the vendor facility align with the EPRI Report.
Test System Design The EPRI Report, Appendix E, "Test Benches and Test Systems," describes example test systems and criteria for the systems. NSPM has selected a facility for MNGP that has a test system capable of thermal stabilization and with vessels of a sufficient size and quality to support the MNGP valve requirements.
Test Sequence Maintenance and testing is performed in the sequence described in the EPRI Report, Section 4.2.1, "Test Sequence." The SRV is removed and prepared for shipment at MNGP. The SRV is shipped to an off-site test facility for an as-found set pressure test as required by the ASME OM Code. Refurbishment is performed in accordance with OMN-17 and the NSPM SRV precision/critical maintenance practices. As-left testing is performed as required by ASME OM Code. Following satisfactory testing the SRV is shipped back to MNGP for receipt inspection, installation, and testing.
Testing Procedures The EPRI Report, Section 4.2.2, "Test Repeatability," describes activities that must be evaluated and controlled in test procedures to ensure repeatability. This is documented within NSPM approved vendor-controlled procedures and MNGP site procedures for removal and installation of SRVs.
Environmental Conditions The EPRI Report, Section 4.2.2.1, "Environmental Conditions," provides guidance on the test and ambient temperature as well as the test fluid and pressure. The SRV are steam tested at an off-site facility. The required pressure and temperature tolerances
L-MT-24-015 Enclosure NSPM Page 8 of 11 are controlled in the test procedure. Additionally, the valve is insulated during testing to ensure environmental conditions are properly established.
Spring Assembly Removal and Inspection Removal and inspection of the pilot spring is performed in alignment with the EPRI Report, Section 6.3.2.9 "Spring Assembly (Spring and Washer) Removal and Inspection". An abutment gap tolerance was developed. Removal and inspection of the second stage and main body springs is also performed in alignment with the EPRI Report, Section 6.3.2.9. The NSPM SRV precision/critical maintenance practices require the pilot, second stage, and main body spring characteristics to meet physical dimensional requirements.
Cold Bar Seat Tightness Test The EPRI Report, Table C-3, "Seat Tightness Testing Methods for Pressure Relief Devices," discusses seat tightness testing. This test is a cold bar seat tightness test performed prior to set pressure testing to determine pretest seat condition. This qualitative test identifies if leakage is present and needs to be further evaluated or quantified. Acceptance criteria for this test is light fogging. Formation of droplets is unacceptable.
If significant leakage is detected (e.g., elevated SRV tailpipe temperatures) NSPM may request a leak rate test prior to the set pressure test.
Additionally, as an enhancement, a second cold bar test is performed on the gasketed joints. The acceptance criteria for this test is that no moisture is detected.
Set Pressure Test Set Pressure Testing is performed in conformance with 2017 ASME OM Code, OMN-17, and the EPRI Report guidance.
(c) Refer to the response provided for EMIB-RAI-3(a)(i).
(d)(1) The current elements from the NSPM SRV precision/critical maintenance practices that have driven satisfactory set pressure performance are described below:
Spring Measurements The NSPM SRV precision/critical maintenance practices require the spring characteristics to meet physical dimensional requirements for overall length, parallelism, and squareness and require replacement if criteria are not within specifications. NSPM may request a spring rate test.
Lapping Techniques The lapping technique performs multiple lapping passes and to meet restrictive tolerances. Based on measurements, inspection, and test results, NSPM SRV precision/critical maintenance practices require lapping any or all of the pilot seat, the second stage seat and/or main seat to satisfy leak tightness criteria.
L-MT-24-015 Enclosure NSPM Page 9 of 11 Internal Component Condition Controls The SRV inspection and maintenance processes include several inspections for internal components with revised criteria. Tight tolerances are applied to the pilot abutment and preload gaps which reduce the likelihood of vibration-induced seat leakage caused by pressure transients. These additional inspections have minimized variation of the SRV internal components.
Additionally, NSPM evaluating implementing enhanced practices for spring testing, lapping techniques, set pressure adjustment methodology and average delay time trending.
At the off-site vendor facility, detailed NSPM-approved vendor procedures are followed for maintenance and provide the required steps for disassembly, inspection, repair, replacement of components, and reassembly of the SRV. Trained vendor personnel perform disassembly, inspection, repair or refurbishment and reassembly. Vendor quality assurance and quality control inspectors monitor work activities per the vendor quality assurance program.
Pilot Stage Disassembly, Inspection, and Testing The spring assembly is removed, measured, and inspected. The pilot assembly is disassembled after measuring the spring abutment gap and the internals are removed and measured for dimensional tolerances, inspected, and cleaned.
Measurements of the preload flange spacer thickness and preload space anti-rotation pin height are taken. The pilot disc seating area is measured and lapped to the desired angle and finish and recorded. The pilot stage is then reassembled. Dimensions and measurements are followed to obtain the correct stack up.
Second Stage Disassembly, Inspection, and Testing Measurements are taken during the second stage disassembly to verify dimensions are within specification. All components are inspected, cleaned, and lapped as necessary to meet required tolerances. Second stage disc seat angles and lapping are verified within specification in the same manner as the pilot disc.
The second stage is reassembled and internal assembly is measured for accuracy.
Main Body Disassembly, Inspection, and Testing The main body spring is measured. The main body disc seat angles and lapping are verified within specification in the same manner as the pilot and second stage discs. Dimensions are verified during reassembly. The packing is tested to verify leakage is within specification.
Following testing and refurbishment the valve is inspected for cleanliness and sealed prior to shipping.
L-MT-24-015 Enclosure NSPM Page 10 of 11 An Authorized Nuclear Inspector (ANI) reviews any repairs. ANI activities are governed by ASME BPVC Section XI (Inservice Inspection) and by the National board of Boiler and Pressure Vessel Inspectors code NBIC-23 (National Board Inspection Code). The off-site vendor performs work in accordance with an NBIC program (VR manual). The vendor also has a 10 CFR 50 Appendix B QA program audited by a Third Party, and the audit results are reviewed and adopted by NSPM.
(d)(2) The NSPM SRV precision/critical maintenance practices incorporate learnings from the NSPM OE program, which provides guidance and requirements for sharing, evaluating, translating OE into station processes. The corrective action program is also used to document and evaluate applicable and significant operating experience. Other elements include the OE from the OEM specifications and/or industry established guidelines.
(e) Refer to the response provided for EMIB-RAI-3(a)(i).
(f) The as-found tolerance of 3% is defined in Technical Specifications. SR 3.4.3.1 states the SRV lift setpoint is 1109 +/- 33.2 psig. 33.2 psig is 3% of 1109 psig rounded conservatively.
The as-left set pressure tolerance is +/- 1% to allow for drift.
EMIB-RAI-5 The MNGP Unit 1, Sixth IST Interval Program (ML22249A234) includes main steam relief valves RV-2-71A, 71B, 71C, 71D, 71E, and 71F, which are also included in the proposed Alternative Request VR-09. For these valves, MNGP Unit 1, Sixth IST Program Interval,, Valve Tables (pages 165 and 166) includes a frequency column that lists RT (Relief Valve Test) as ASME Class 1, Appendix I, Section I-3310 and I-3410. Further, the IST Program frequency column lists SY6 (pages 165 and 166) and under SY6 description on page 27 of 266 lists Alternative Request VT-5. In Alternative Request VR-09, the licensee provides the frequency of relief valves as per I-1320.
(a) Explain this difference and mismatch between the IST Program and Alternative Request VR-09.
(b) Explain how Alternative Request VR-5 is applicable to the valves listed in Alternative Request VR-09.
Response to EMIB-RAI-5 (a) This issue is an error in the MNGP IST program Sixth 10-Year Interval Plan, which incorrectly specified VR-05 on page 27 where it should have specified OMN-17. This has been entered in the Corrective Action Program.
(b) VR-05 is not applicable to VR-09.
L-MT-24-015 Enclosure NSPM Page 11 of 11
3.0 REFERENCES
- 1. NSPM letter to NRC, "10 CFR 50.55a(z)(1) Request Regarding OMN-17, Revision 1, VR-09," dated November 13, 2023 (ADAMS Accession No. ML23317A222)
- 2. NRC email to NSPM, "Monticello - Final Request for Additional Information re: Alternative Request VR-09 for OMN-17," dated April 15, 2024
- 3. ASME OM Code Case OMN-17, Revision 1, "Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves"
- 4. EPRI 2015 Technical Report. Nuclear Maintenance Applications Center: Safety and Relief Valve Testing and Maintenance Guide. Revision of TR-105872, Technical Report 3002005362, dated August 2015