ML25093A006
| ML25093A006 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 04/02/2025 |
| From: | Currier B Northern States Power Company, Minnesota, Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-PI-25-009 | |
| Download: ML25093A006 (1) | |
Text
1717 Wakonade Drive Welch, MN 55089 L-PI-25-009 10 CFR 50.55a April 2, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 10 CFR 50.55a Request 6-IST-RR-01 Associated with the Inservice Testing Program Pursuant to 10 CFR 50.55a, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), requests NRC authorization of the enclosed 10 CFR 50.55a(z)(1) alternative 6-RR-01 for the Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2. This alternative is applicable to the PINGP Inservice Testing program Code of Record Interval that uses the 2020 Edition of the ASME Operations and Maintenance (OM) Code. The details of this 10 CFR 50.55a alternative request are provided in the enclosure to this letter.
NSPM requests the approval of this request by December 20, 2025.
Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.
If you should have any questions regarding this submittal, please contact Ron Jacobson by phone (612) 330-6542 or email: ronald.g.jacobson@xcelenergy.com.
Bryan Currier Plant Manager, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota fl Xcel Energy
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Document Control Desk L-PI-25-009 Page 2 Enclosure cc:
Administrator, Region III, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC
L-PI-25-009 NSPM Enclosure Page 1 of 3 Prairie Island IST Program Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1) 6-IST-RR-01 Vertical Line Shaft Cooling Water Pump Vibration
- 1. American Society of Mechanical Engineers (ASME) Code Components Affected Pump ID Pump Description ASME Class ASME OM Code Category 045-091 121 Motor Driven Cooling Water (MDCL) Pump 3
Group A 145-392 12 Diesel Driven Cooling Water (DDCL) Pump 3
Group B 245-392 22 Diesel Driven Cooling Water Pump 3
Group B Function:
The 121 vertical MDCL pump serves as a diverse means of providing cooling water that is independent of the DDCL pumps. The Station Blackout / Electrical Safeguards Upgrade modification upgraded the 121 MDCL pump to safeguards status and changed the power supply to an essential safeguards diesel-backed power supply.
Each DDCL pump (the 12 DDCL pump and the 22 DDCL pump) is capable of supplying all essential cooling water loads during an accident. Only one cooling water pump is required for the safe shutdown of both units (accident in only one unit). The DDCL pumps are capable of providing safeguards water supply to the Auxiliary Feedwater Pumps. Each DDCL pump is capable of supplying sufficient cooling to the Unit 1 Emergency Diesel Generators, air compressors, Component Cooling heat exchangers, containment fan-coil units, and the auxiliary building unit coolers.
2. Applicable Code Edition and Addenda
ASME Operation and Maintenance of Nuclear Power Plants (OM) Code, 2020 Edition.
3. Applicable Code Requirement
ISTB-3540, Vibration.
ISTB-3540(b) states, On vertical line shaft pumps, measurements shall be taken on the upper motor-bearing housing in three approximately orthogonal directions, one of which is the axial direction.
L-PI-25-009 NSPM Enclosure Page 2 of 3
4. Reason for Request
The motor-bearings are inaccessible due to the pump design.
DDCL pumps: The driver for the 12 and 22 DDCL pumps are diesel engines coupled to a right angle drive. The pump bearings are inaccessible for vibration measurements.
MDCL pump: The design of the MDCL pump limits access to the upper thrust bearing housing of the motor to take vibration readings with a portable instrument while the pump is running. Climbing on top of the motor while it is running is a potential personnel hazard. Additionally, to remove the bearing housing cover is a potential personnel hazard while the pump is running and thus taking direct readings is not practical.
5. Proposed Alternative and Basis for Use
Vibration measurements for the 12 and 22 DDCL pumps will be taken on the right-angle drive. The thrust from the pump and driver would be transmitted to the right-angle drive, thus monitoring vibration at this location will give an acceptable indication of pump degradation. Vibration measurements will be taken in three orthogonal directions one of which is the axial direction. An additional vibration measurement will be taken on each of the diesel engines.
Vibration measurements for the 121 MDCL pump will be taken on the motor housing in three orthogonal directions, one of which is the axial direction. Vibration readings on the motor housing will give an acceptable indication of pump degradation. The axial reading will be taken on the side of the motor housing, midway between the upper and lower bearing.
- 6. Duration of Proposed Alternative The proposed alternative will be effective during the Code of Record Interval that uses the 2020 Edition of the ASME OM Code.
- 7. Precedents This alternative vibration measurement method was previously requested for the third ten-year IST Interval as 10 CFR 50.55a Relief Request No. 4, the fourth ten-year IST Interval as 10 CFR 50.55a Relief Request 1, and the fifth ten-year IST Interval as 10 CFR 50.55a request RR-03. These requests were approved by the NRC in References 1, 2, and 3 respectively.
- 8. References
L-PI-25-009 NSPM Enclosure Page 3 of 3
- 1. Letter from A. Randolph Blough, NRC, Approval of Third 10-Year Inservice Testing Program Relief Requests for Pumps and Valves - Prairie Island Nuclear Generating Plant, Units 1 and 2 (TAC No. M86807 and M86808), to Roger O.
Anderson, Northern States Power Company, dated December 8, 1993 (ADAMS Accession Numbers ML20058N763 and ML20058N802).
- 2. Letter from Mahesh L. Chawla, NRC, Prairie Island Nuclear Generating Plant, Units 1 and 2 - Issuance of Safety Evaluation for the Fourth 10-Year Inservice Testing (IST) Program Interval (TAC Nos. MC4509 and MC4510), to Joseph M.
Solymossy, Nuclear Management Company, LLC, dated July 25, 2005 (ADAMS Accession Number ML051790258).
- 3. Letter from David L. Pelton, NRC, "Prairie Island Nuclear Generating Plant, Units 1 and 2 - Relief Request for fifth 10-Year Inservice Testing Program Interval (TAC Nos. MC3928 and MC3929)", to Kevin K. Davison, Northern States Power Company, dated December 5, 2014 (ADAMS Accession Number ML14329A185).