ML25178C666
| ML25178C666 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 06/27/2025 |
| From: | Ilka Berrios Plant Licensing Branch III |
| To: | Paulhardt W Northern States Power Co |
| References | |
| EPID L-2025-LLR-0062 | |
| Download: ML25178C666 (1) | |
Text
June 27, 2025 Mr. Werner Paulhardt Site Vice President Northern States Power Company - Minnesota Prairie Island Nuclear Generating Plant 1717 Wakonade Drive East Welch, MN 55089
SUBJECT:
PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 - PROPOSED ALTERNATIVE REQUEST RR-12 COOLING WATER SYSTEM TESTING (EPID L-2025-LLR-0062)
Dear Mr. Paulhardt:
By electronic submission dated June 26, 2025, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25177D085), Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submitted Alternative Request RR-12 to the U.S. Nuclear Regulatory Commission (NRC) proposing an alternative to specific inservice testing (IST) requirements in the 2004 Edition through the 2006 Addenda to the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) for specified valves in the cooling water system at Prairie Island Nuclear Generating Plant (Prairie Island), Units 1 and 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 defer certain testing requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a for specified valves in the cooling water system on the basis that complying with the specified requirements at this time would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation that NSPM has justified in Alternative Request RR-12 that performance of the specified ASME OM Code test requirements for MV-32322 and MV-32329 in the cooling water system at Prairie Island, Units 1 and 2, at this time would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The NRC staff also has determined that the test and performance experience of the subject valves provides reasonable assurance that they will be operationally ready to perform their safety functions for the duration of the alternative request. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes Alternative Request RR-12 for the proposed extension of the IST test interval for MV-32322 and MV-32329 in the cooling water system at Prairie Island, Units 1 and 2, until either completion of the repair of MV-32038, or September 29, 2025, whichever comes first.
W. Paulhardt All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject request remain applicable.
If you have any questions, please contact the Project Manager, Beth Wetzel, at 301-415-5223 or via e-mail at Beth.Wetzel@nrc.gov.
Sincerely, Ilka Berrios, Acting Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306
Enclosure:
Safety Evaluation cc: Listserv BRENT BALLARD Digitally signed by BRENT BALLARD Date: 2025.06.27 15:53:28 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED ALTERNATIVE REQUEST RR-12 COOLING WATER SYSTEM TESTING NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306 EPID: L-2025-LLR-0062
1.0 INTRODUCTION
By electronic submission dated June 26, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25177D085), Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submitted Alternative Request RR-12 to the U.S. Nuclear Regulatory Commission (NRC) proposing an alternative to specific inservice testing (IST) requirements in the 2004 Edition through the 2006 Addenda of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) for specified valves in the cooling water system at Prairie Island Nuclear Generating Plant (Prairie Island), Units 1 and 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 defer certain testing requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a for specified valves in the cooling water system on the basis that complying with the specified requirements at this time would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The Fifth Interval IST program at Prairie Island, Units 1 and 2, began on December 21, 2014, and is scheduled to end on December 20, 2025, using the 1-year extension allowed by the ASME OM Code as incorporated by reference in 10 CFR 50.55a.
2.0 REGULATORY EVALUATION
The NRC regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, state in part:
Throughout the service life of a boiling or pressurized water-cooled nuclear power facility, pumps and valves that are within the scope of the ASME OM Code must meet the IST requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in 10 CFR 50.55a(f)(2) and (3) and that are incorporated by reference in 10 CFR 50.55a(a)(1)(iv), to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state:
Alternatives to the requirements of [10 CFR 50.55a(b) through (h)] or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The applicant or licensee must demonstrate that:
(1) Acceptable level of quality and safety. The proposed alternative would provide an acceptable level of quality and safety; or (2) Hardship without a compensating increase in quality and safety. Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensees Alternative Request RR-12 Applicable ASME OM Code Edition The applicable Code of record for the Fifth IST Interval Program at Prairie Island, Units 1 and 2, is the 2004 Edition through the 2006 Addenda of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a.
Applicable ASME OM Code Components Table 1 of this safety evaluation (SE) lists the valves at Prairie Island, Units 1 and 2, for which this alternative is being requested:
Table 1 Component Description ASME OM Code Category Type MV-32322 (Unit 1)
Loop A/B Cooling Water Return Header Cross-Over Motor Valve A B
Motor-Operated Butterfly Valve MV-32329 (Unit 2)
Loop A/B Cooling Water Return Header Cross-Over Motor Valve B B
Motor-Operated Butterfly Valve Applicable ASME OM Code Requirements The IST requirements in the ASME OM Code, 2004 Edition through the 2006 Addenda, as incorporated by reference in 10 CFR 50.55a, related to this alternative request are as follows:
ASME OM Code, Subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3510, Exercising Test Frequency, states that Active Category A, Category B, and Category C check valves shall be exercised nominally every 3 months, except as provided by ISTC-3520, ISTC-3540, ISTC-3550, ISTC-3570, ISTC-5221, and ISTC-5222. Power-operated relief valves shall be exercise tested once per fuel cycle.
ASME OM Code, Subsection ISTC, paragraph ISTC-3521, Category A and Category B Valves, states, in part:
(a) Full-stroke exercising of Category A and Category B valves during operation at power to the position(s) required to fulfill its function(s), and exercising or examining check valves during plant operation in a manner that verifies obturator travel to the closed, full-open, or partially open position required to fulfill its function(s).
ASME OM Code, Subsection ISTC, paragraph ISTC-5120, Motor Operated Valves, subparagraph ISTC-5121, Valve Stroke Testing, states, in part, that active valves shall have their stroke times measured when exercised in accordance with ISTC-3500.
Proposed Alternative and Basis for Use:
In its submittal dated June 26, 2025, the licensee proposed to defer quarterly testing of the impacted valves until either the post-maintenance testing of the valves following repair of MV-32038 or September 29, 2025, whichever comes first. MV-32322 and MV-32329 will remain danger tagged (deactivated) closed until repairs are complete (or an alternate test method for the impacted valves is developed) and will be tested per ISTC-3510, ISTC-3520, and ISTC-3521 upon restoration.
The licensee has requested this alternative in accordance with 10 CFR 50.55a(z)(2). The licensee states that testing the affected valves per the ASME OM Code requirements prior to completion of the repairs of MV-32038 would result in a hardship imposed by a larger flow of cooling water into the Auxiliary Building that can be reasonably and safely managed, or an inoperable declaration for the associated cooling water header, which would result in a Technical Specification loss of function due to the current plant configuration and immediate entry into Technical Specification Limiting Condition for Operation (LCO) 3.0.3.
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Reason for Request===
In its submittal dated June 26, 2025, the licensee stated:
Valves MV-32322 and MV-32329 are part of the cooling water return headers in the auxiliary building. The headers are provided with an emergency dump valve (MV-32038) to be used in the event that both cooling water return emergency dump lines in the turbine building fail. Each cooling water return header normally discharges to a 30-inch standpipe that discharges to the circulating water system return. If the normal return to circulating water gets blocked, cooling water level in the standpipe rises until it reaches the emergency dump line, which is a passive drain path to grade from the Turbine Building. MV-32038 is a backup to these emergency dump lines. MV-32038 is on a T between MV-32322 and MV-32329 and dumps outside the Auxiliary Building. MV-32322 and MV-32329 are normally closed and have safety functions:
In the open position (provide flow path to the emergency dump to grade)
In the closed position (separate the cooling water return headers).
The licensee further stated:
MV-32322 and MV-32329 are closed and deactivated as part of the clearance boundary in support of repairs on MV-32038, which has been removed from the system for repair activities after its as-found condition was worse than anticipated. The unanticipated as-found condition also extended the time required to complete repairs on the valve.
With MV-32038 removed, opening either MV-32322 or MV-32329 would result in cooling water flow into the Auxiliary Building that would be beyond reasonable capability to redirect or catch....
And:
While a temporary plant modification to procure or manufacture and install a spool piece or blind flange in support of testing MV-32322 and MV-32329 would be possible, doing so prior to the late test due date presents a hardship without a compensating increase in quality and safety. Specifically, a safety-related flange or spool piece would take too long to procure and a non-safety related flange, while available, would require declaring the associated cooling water header inoperable when stroking MV-32322 or MV-32329. Currently, the plant has A-train of safeguards chilled water system (SCWS) inoperable due to an equipment failure, so making a B-train cooling water header inoperable would result in loss of the SCWS safety function and immediate entry into Technical Specification LCO 3.0.3.
3.2
NRC Staff Evaluation
In Alternative Request RR-12, submitted on June 26, 2025, the licensee proposed an extension of the ASME OM Code test schedule for MV-32322 and MV-32329 in the cooling water system at Prairie Island, Units 1 and 2. These valves are part of the cooling water return headers in the auxiliary building. The headers are provided with an emergency dump valve (MV-32038) to be used in the event that both cooling water return emergency dump lines in the turbine building fail. MV-32038 is on a T between MV-32322 and MV-32329 and dumps outside the Auxiliary Building. MV-32322 and MV-32329 are normally closed and have safety functions in the open position to provide flow path to the emergency dump to grade, and in the closed position to separate the cooling water return headers.
The licensee stated that performance of the IST tests for these valves requires repair and reinstallation of MV-32038, which is currently undergoing troubleshooting and repairs, or development of an alternate test method. Cycling MV-32322 or MV-32329 with MV-32038 removed would result in a larger flow of cooling water into the Auxiliary Building that can be reasonably and safely managed. A temporary modification to support testing would either not meet the schedule (for use of a safety-related flange or spool piece), or would require an inoperable declaration for the associated cooling water header (for use of a non-safety related flange), which would result in a Technical Specification loss of function due to the current plant configuration and immediate entry into Technical Specification LCO 3.0.3. As a result, the licensee submitted the proposed alternative under the hardship provisions of 10 CFR 50.55a(z)(2).
The licensee is required to test MV-32322 and MV-32329 every 3 months per the requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a. Specifically, ISTC-3510 provides the test frequency, ISTC-3521 requires full-stroke exercise testing, and ISTC-5121 requires stroke timing when conducting the exercise test. The licensee reports that the performance of the next required IST test for components within the scope of Alternative Request RR-12 at Prairie Island, Units 1 and 2, is due on June 29, 2025. The licensee proposed to extend the IST testing schedule for MV-32322 and MV-32329 until completion of the repair of MV-32038 or September 29, 2025, whichever comes first. The NRC staff considers Alternative Request RR-12 to apply to ISTC-3510, ISTC-3521, and ISTC-5121.
In its submittal dated June 26, 2025, the licensee reported that MV-32322 and MV-32329 are closed and deactivated as part of a clearance boundary in support of repairs on MV-32038, which has been removed from the system for repair activities after its as-found condition was worse than anticipated. The licensee reports that testing the affected valves per the ASME OM Code requirements prior to completion of the repairs of MV-32038 would result in a hardship imposed by a larger flow of cooling water into the Auxiliary Building that can be reasonably and safely managed, or an inoperable declaration for the associated cooling water header, which would result in a Technical Specification loss of function due to the current plant configuration and immediate entry into Technical Specification LCO 3.0.3. Based on this information, the NRC staff agrees that testing these valves before repair of the MV-32038 valve would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee reported consistent performance of IST testing for MV-32322 and MV-32329, with no adverse trends. The last quarterly performance of the IST surveillance procedures was satisfactory for both valves and the last 10 quarterly tests were reported to be similar, with no trends noted. Therefore, the test results for the applicable components have been within the ASME OM Code limits such that there is reasonable assurance that their performance will remain acceptable for the duration of the proposed alternative.
The NRC staff observes that MV-32038 is listed in the IST Program, but is not within the scope of the licensees proposed alternative. As the valve is currently removed from the system for repairs, it is declared inoperable and undergoing repair as would be required by a failed IST test. Before returning MV-32038 to service, post-maintenance testing will be conducted in accordance with ISTC-3310, Effects of Valve Repair, Replacement, or Maintenance on Reference Values. Therefore, it is not required for MV-32038 to be considered within the scope of Alternative Request RR-12.
Based on its review of the information provided within the scope of Alternative Request RR-12, the NRC staff determined that there is reasonable assurance of the operational readiness of MV-32322 and MV-32329 at Prairie Island, Units 1 and 2, to be capable of performing their design functions during the proposed IST test interval extension. The staff found that compliance with the specified IST requirements for the subject valves during the duration of the requested alternative would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Therefore, the staff finds that the proposed alternative meets the requirements of 10 CFR 50.55a(z)(2). As a result, the NRC staff finds that Alternative Request RR-12 may be authorized for an extension of the specified test intervals for MV-32322 and MV-32329 at Prairie Island, Units 1 and 2, until either completion of the repair of MV-32038, or September 29, 2025, whichever comes first.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that NSPM has justified in Alternative Request RR-12 that performance of the specified ASME OM Code test requirements for MV-32322 and MV-32329 in the cooling water system at Prairie Island, Units 1 and 2, at this time would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The NRC staff also has determined that the test and performance experience of the subject valves provides reasonable assurance that they will be operationally ready to perform their safety functions for the duration of the alternative request. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes Alternative Request RR-12 for the proposed extension of the IST test interval for MV-32322 and MV-32329 in the cooling water system at Prairie Island, Units 1 and 2, until either completion of the repair of MV-32038, or September 29, 2025, whichever comes first.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject request remain applicable.
Principal Contributors: N. Hansing, NRR T. Scarbrough, NRR Date: June 27, 2025
ML25178C666 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EMIB/BC NAME BWetzel SLent SBailey DATE 6/27/2025 6/27/2025 6/27/2025 OFFICE NRR/DORL/LPL3/BC (A)
NAME IBerrios (BBallard for)
DATE 6/27/2025