AEP-NRC-2025-46, Unit 2, 10 CFR 50.55a Requests Associated with the Sixth Ten-Year Inservice Testing Interval
| ML25364A335 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/30/2025 |
| From: | Dailey S Indiana Michigan Power Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| AEP-NRC-2025-46 | |
| Download: ML25364A335 (0) | |
Text
INDIANA MICHIGAN POWEil-An MP Company BOUNDLESS ENERGY-December 30, 2025 Docket Nos.: 50-315 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, Ml 49106 indianamichiganpower.com AEP-NRC-2025-46 10 CFR 50.55a 10 CFR 50.55a Requests Associated with the Sixth Ten-Year lnservice Testing Interval
References:
- 1. Letter from David J. Wrona, NRC, to Joel P. Gebbie, l&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 - Request For Use of Alternative REL-PP1 Associated With Pump lnservice Testing (CAC Nos. MF6548 and MC6549)," dated February 4, 2016, ADAMS Accession No. ML16032A031.
- 2. Letter from David J. Wrona, NRC, to Joel P. Gebbie, l&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 - Relief Request REL-002 Associated With Valve Seat Leakage Testing (CAC Nos.
MF6546 and MC6547)," dated March 4, 2016, ADAMS Accession No. ML16054A572.
- 3. Letter from Q. Shane Lies, l&M, to NRC, "Donald C. Cook Nuclear Plant Units 1 and 2 Fifth 10-Year Interval Pump and Valve lnservice Testing Program," AEP-NRC-2016-35, dated June 30, 2016, ADAMS Accession No. ML16197A057.
Pursuant to 10 CFR 50.55a(f)(5)(i), Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, requests U.S. Nuclear Regulatory Commission authorization or approval of the enclosed 10 CFR 50.55a requests associated with the Sixth lnservice Testing Interval for CNP.
Relief Request REL-PP1 is being submitted under the provisions of 10 CFR 50.55a(z)(2) as compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Relief Request REL-002 is being submitted under the provisions of 10 CFR 50.55a(f)(6)(i) because complying with the code requirements is impractical. The applicable 1 0 CFR 50.55a provision is identified in each relief request. Relief Requests REL-002 and REL-PP1 were previously approved for CNP's fifth 10-year test interval (References 1, 2, and 3).
l&M requests approval of the relief requests prior to the start of the sixth 10-year test interval, which will begin July 1, 2026.
U.S. Nuclear Regulatory Commission Page 2 AEP-NRC-2025-46 This letter contains no new commitments. Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Director, at (269) 466-2649.
Sincerely,
~A Scott A. Dailey Site Vice President JMT/sjh
Enclosure:
Relief Request for Pump and Valve lnservice Test Program for Donald C. Cook Nuclear Plant Sixth Ten-Year Interval c:
EGLE - RMD/RPS J. 8. Giessner - NRC Region Ill NRC Resident Inspector N. Quilico - MPSC R. M. Sistevaris - AEP Ft. Wayne S. P. Wall, NRC Washington D.C.
A. J. Williamson - AEP Ft. Wayne, w/o enclosures
Enclosure to AEP-NRC-2025-46 Relief Requests for Pump and Valve lnservice Test Program for Donald C. Cook Nuclear Plant Sixth Ten-Year Interval
REQUEST FOR RELIEF REL-PP1 Boric Acid Pump Vibration Requirements Proposed Alternative lnservice Testing (1ST) Requirements in accordance with 1 0CFR50.55a(z)(2) as compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
- 1. ASME Code componentts) Affected Table 1 Pump Number Pump Name ASME OM Pump Type Code Group 1-PP-46-1 Boric Acid Storage Tanks A
Centrifugal Transfer Pump #1 1-PP-46-2 Boric Acid Storage Tanks A
Centrifugal Transfer Pump #2 2-PP-46-3 Boric Acid Storage Tanks A
Centrifugal Transfer Pump #3 2-PP-46-4 Boric Acid Storage Tanks A
Centrifugal Transfer Pump #4
2. Applicable Code Edition and Addenda
American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants (OM) Code, 2022 Edition.
- 3. Applicable Code Reguirementts)
ISTB-3540, "Vibration" (a) On centrifugal pumps, except vertical line shaft pumps, measurements shall be taken in a plane approximately perpendicular to the rotating shaft in two approximately orthogonal directions on each accessible pump-bearing housing. Measurements shall also be taken in the axial direction on each accessible pump thrust bearing housing.
- 4. Reason toe Request Two horizontal, centrifugal, two speed pumps with mechanical seals are available per unit.
Although not required, one pump may be aligned to run continuously at low speed to provide recirculation of the boric acid system and the boric acid tank. The second pump can be aligned with the shared boric acid tank and is considered as a standby pump, with service being transferred as operation requires. This second pump is also used to intermittently circulate fluid through the shared tank. Automatic initiation of the reactor coolant makeup system will align the running pump for high speed operation to provide normal makeup of boric acid solution as required. Manual operation of the boric acid transfer pumps (i.e., starting an inactive pump) can also be used to provide reactor coolant makeup as necessary. For emergency boration, supplying of boric acid solution to the suction of the charging pump can be accomplished by manually opening boration flow
control valves for either or both pumps. The transfer pumps also function to transfer boric acid solution from the batching tank to the boric acid tanks.
By design, the only accessible point for taking axial vibration measurements is the outboard motor bearing. It is unsafe to monitor the axial direction vibration on the inboard pump bearing due to the proximity of the rotating shaft, and there is no position to monitor the outboard pump bearing housing because of the presence of heat tracing. Modifications to the coupling shield to allow access were attempted. However, the modified shield did not provide sufficient clearance to allow individuals performing the measurement to safely place their hands near the rotating shaft.
- s. Proposed Alternative and Basis tor Use Axial vibration will be measured at the outboard motor bearing for the pumps listed in Table
- 1. The vibration limits contained in ASME OM Code Table ISTB-5121-1, will be applied to the vibration levels monitored at the outboard motor bearing during both the Group A test and Comprehensive test.
Although the axial vibration measurement would now include the noise from the motor, that contribution would be minimal considering that the pump is directly coupled to the motor and all significant axial contributors to vibration should originate from the pump. The proposed location to take axial vibration measurements, coupled with continued use of the vibration ranges given in Table ISTB-5121-1 of the ASME OM Code, should provide an acceptable level of quality and safety.
In accordance with 1 0CFR50.55a(z)(2) the proposed alternative of taking axial vibration measurements in an alternative location, coupled with continued use of the vibration ranges given in Table ISTB-5121-1 of the ASME OM Code, will provide an acceptable level of quality and safety.
- s. Duration of Proposed Alternative The proposed alternative shall be implemented during the Code of Record 1ST Interval for the 2022 Edition of the OM Code, beginning July 1; 2026.
- 1. precedents
- 1. Letter from L. Raghavan, NRC, to Mano K. Nazar, Indiana Michigan Power Company (l&M), "D. C. Cook Nuclear Plant, Units 1 and 2 - Relief Requests for The Fourth 10-year Pump and Valve lnservice Testing Program Interval (TAC Nos. MC9455 and MC9456),"
dated June 28, 2006, ADAMS Accession No. ML061730175.
- 2. Letter from David J. Wrona, NRC, to Joel P. Gebbie, l&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 - Request for Use of Alternative REL-PP1 Associated with Pump lnservice Testing (CAC Nos. MF6548 and MC6549)," dated February 4, 2016, ADAMS Accession No. ML16032A031.
REQUEST FOR RELIEF REL-002 Seat Leakage Testing for Information Notice 91-56 Valves Impractical 1ST Requirements in accordance with 10CFR50.55a(f)(5)(iii) and 1 0CFR50.55a(f)(6)(i) granting of relief based on the impracticality of performing testing in accordance with code requirements, and in consideration of the burden on the licensee if the code requirements were imposed on the facility
- 1. ASME Code componentls) Affected Alternative testing is requested for the valves in Table 1.
Table 1 Valve ID Function Cateoorv Class 1-IMO-261 Refueling Water Storage Tank (RWST)
A 2
Supply to Safety Injection (SI) Pumps Shutoff Valve, Unit 1 1-IMO-910 RWST to eves (Chemical Volume and A
2 Control System) Charging Pumps Suction Header Train "A" Shutoff Valve, Unit 1 1-IMO-911 RWST to eves Charging Pumps Suction A
2 Header Train "B" Shutoff Valve, Unit 1 2-IMO-261 RWST Supply to SI Pumps Shutoff Valve, A
2 Unit 2 2-IMO-910 RWST to eves Charging Pumps Suction A
2 Header Train "A" Shutoff Valve, Unit 2 2-IMO-911 RWST to eves Charging Pumps Suction A
2 Header Train "B" Shutoff Valve, Unit 2
2. Applicable Code Edition and Addenda
American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants (OM) Code, 2022 Edition.
- 3. Applicable Code Reauirementls)
ASME OM Code Requirements ISTC-3630(b) "Differential Test Pressure," states in part that, "Valve seat tests shall be made with the pressure differential in the same direction as when the valve is performing its function."
ISTC-3630, "Leakage Rate for Other Than Containment Isolation Valves," states that Category A valves with a leakage requirement not based on an Owner's 1 O CFR 50, Appendix J program, shall be tested to verify their seat leakages within acceptable limits.
Valve closure before seat leakage testing shall be by using the valve operator with no additional closing force applied.
(a) Frequency. Tests shall be conducted at least once every 2yr.
(b) Differential Test Pressure. Valve seat tests shall be made with pressure differential in the same direction as when the valve is performing its function... "
- 4. Reason Joe Request These valves are classified as Category A valves requiring a seat leakage test due to concerns based on Information Notice 91-56, "Potential Radioactive Leakage to Tank Vented to Atmosphere".
CNP Unit 1 and Unit 2 were constructed and licensed prior to the concern about back-leakage to the RWST being identified. As a result, the system in which these valves are located is not designed and constructed to allow accident-direction testing.
There are no isolation valves between these valves and the RWST. There is no practical means to measure seat leakage with pressure applied in the accident direction.
System modifications to allow for leakage determination tests that would meet code provisions would involve installing a minimum of one eight-inch isolation valve and test/vent connection in order to test 1 [2]-IMO-261 and an eight-inch isolation valve for 1[2]-IM0-910 and 911 leakage tests. Another option would require addition of a 24-inch isolation valve on the RWST outlet header which would shut off flow to all of the Emergency Core Cooling System (ECCS) pump suctions from the RWST.
A system modification would require an extended out-of-service time for ECCS. This would be a significant burden to implement and result in a non-standard system configuration.
5. Proposed Alternative and Basis for Use
These valves will be tested in a reverse flow direction using the static head from the RWST.
Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, is of the opinion that the proposed testing of the gate valves, combined with the leakage testing of the check valves in series with them, provides reasonable assurance that the system leakage requirements will be met under accident conditions.
l&M proposes to test the valves in reverse direction (the test pressure differential is opposite to the pressure differential that would exist when the valve is performing its isolation function) using the static head from the RWST. Testing the wedge at low line pressures ( 12-17 pounds per square inch differential (psid)) using static head of the RWST will mainly test the seal created by the mechanical wedging force alone, thus providing an indication of the degree of degradation of the seating surfaces. The increased line pressure under accident conditions (122 psid for IMO-910 and IMO-911, 195 psid for IMO-261) will act to further seat the sealing face closest to the RWST, so the proposed test at lower pressure in the opposite direction will test this seating surface without the additional service pressure that would tend to diminish leakage by pressing the disk into the seat with greater force. Therefore, the proposed seat leakage test provides reasonable assurance of the operational readiness of the valves to isolate the RWST from back leakage during the LOCA recirculation phase.
6. Duration of Proposed Alternative
The proposed alternative identified in this relief request shall be implemented during the Code of Record Interval for the 2022 Edition of the OM Code, beginning July 1, 2026.
7. Precedents
- 1. Letter from L. Raghavan, NRC, to Mano K. Nazar, l&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 (DCCNP-1 and DCCNP-2) - Relief Request REL-002 and REL-021 for the Third and Fourth Interval lnservice Testing Programs (TAC NOS. MD0939, MD0940, MD2498, and MD2499)," dated December 8, 2006, ADAMS Accession No. ML063340516.
- 2. Letter from David J. Wrona, NRC, to Joel P. Gebbie, l&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 - Relief Request REL-002 Associated with Valve Seat Leakage Testing (CAC Nos. MF6546 and MC6547)," dated March 4, 2016, ADAMS Accession No. ML16054A572.