ML26023A192
| ML26023A192 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 01/28/2026 |
| From: | Scott Wall NRC/NRR/DORL/LPL3 |
| To: | Ferneau K Indiana Michigan Power Co |
| Wall S | |
| References | |
| EPID L 2026 LLR 0001 | |
| Download: ML26023A192 (0) | |
Text
January 28, 2026 Ms. Kelly J. Ferneau Executive Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106
SUBJECT:
DONALD C. COOK NUCLEAR PLANT, UNIT NOS. 1 AND 2 - ISSUANCE OF RELIEF REQUEST REL-002 ASSOCIATED WITH PUMP INSERVICE TESTING (EPID L-2026-LLR-0001)
Dear Ms. Ferneau:
By letter dated December 30, 2025 (Agencywide Documents Access and Management System Accession No. ML25364A335), Indiana Michigan Power Company (I&M, the licensee) submitted a request for relief from certain requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code), associated with pump inservice testing (IST) for the Donald C. Cook Nuclear Plant, Units 1 and 2 (CNP).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(f)(5)(iii) and 50.55a(f)(6)(i), the licensee requested relief and to use alternative requirements for inservice testing items, on the basis that the code requirement is impractical.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that I&M has adequately addressed the requirements in 10 CFR 50.55a(f)(6)(i). The NRC staff determines that it is impractical for the licensee to comply with certain requirements of the ASME OM Code related to valve seat leakage testing. The proposed alternative of request REL-002 provides reasonable assurance that the affected valves will remain operationally ready. Therefore, the NRC staff approves the use of REL-002 for the Sixth IST interval at CNP.
All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.
K. Ferneau If you have any questions, please contact the Senior Project Manager, Scott Wall, at 301-415-2855 or e-mail at Scott.Wall@nrc.gov.
Sincerely, Ilka Berrios, Acting Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-315 and 50-316
Enclosure:
Safety Evaluation cc: Listserv ILKA BERRIOS Digitally signed by ILKA BERRIOS Date: 2026.01.28 11:59:33 -05'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST REL-002 INDIANA MICHIGAN POWER COMPANY DONALD C. COOK NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-315 AND 50-316
1.0 INTRODUCTION
By letter dated December 30, 2025 (Agencywide Documents Access and Management System Accession No. ML25364A335), Indiana Michigan Power Company (I&M, the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC, the Commission) a request for relief from certain requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of nuclear power plants (OM Code), associated with pump inservice testing (IST) for the Donald C. Cook Nuclear Plant, Units 1 and 2 (CNP).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Sections 50.55a(f)(5)(iii) and 50.55a(f)(6)(i), the licensee requested to use the proposed alternatives in request REL-002 on the basis the ASME Code requirement is impractical.
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 inservice test 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 paragraphs (f)(2) and (3) of this section
[10 CFR 50.55a] and that are incorporated by reference in paragraph (a)(1)(iv) of this section [10 CFR 50.55a], to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The regulations in 10 CFR 50.55a(f)(5)(iii), IST program update: Notification of impractical IST Code requirements, state:
If the licensee has determined that conformance with certain Code requirements is impractical for its facility, the licensee must notify the Commission and submit, as specified in § 50.4, information to support the determination.
The regulations in 10 CFR 55a(f)(6)(i), Impractical IST requirements: Granting of relief, state:
The Commission will evaluate determinations under paragraph (f)(5) of this section that code requirements are impractical. The Commission may grant relief and may impose such alternative requirements as it determines are authorized by law, will not endanger life or property or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
The NRC may grant relief and may impose alternative requirements pursuant to paragraph 10 CFR 50.55a(f)(6)(i). In requesting relief under 10 CFR 50.55a(f)(5)(iii), IST program update:
Notification of impractical IST Code requirements, the licensee must demonstrate that conformance is impractical for its facility.
Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to grant the relief requested by the licensee.
3.0 TECHNICAL EVALUATION
The information provided by the licensee in support of the request for an alternative to ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, has been evaluated and the bases for NRC staffs conclusion are documented below.
3.1 Licensees Alternative Request REL-002 ASME OM Code Components Affected In its submittal, the licensee requested to use an alternative to the applicable ASME OM Code requirements for the valves listed in Table 1.
Table 1 Valve ID Function Category Class 1-IMO-261 Refueling Water Storage Tank (RWST) Supply to Safety Injection (SI) Pumps Shutoff Valve, Unit 1 A
2 1-IMO-910 RWST to Chemical Volume and Control System (CVCS) Charging Pumps Suction Header Train A Shutoff Valve, Unit 1 A
2 1-IMO-911 RWST to CVCS Charging Pumps Suction Header Train B Shutoff Valve, Unit 1 A
2 2-IMO-261 RWST Supply to SI Pumps Shutoff Valve, Unit 2 A
2 2-IMO-910 RWST to CVCS Charging Pumps Suction Header Train A Shutoff Valve, Unit 2 A
2 2-IMO-911 RWST to CVCS Charging Pumps Suction Header Train B Shutoff Valve, Unit 2 A
2 Applicable Code Editions and Addenda For the Sixth IST interval, the CNP IST program is based on the 2022 Edition of the ASME OM Code as incorporated by reference in 10 CFR 50.55a.
Applicable Code Requirements 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 10 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... "
=
Reason for Request===
In the submittal, the licensee stated, in part:
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 was] 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 an eight-inch isolation valve and test/vent connection in order to test 1[2]-IM0-261 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.
Proposed Alternative and Basis for Use The licensee proposed the following alternative:
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.
Duration of Proposed Alternative The licensee requested the alternative to be approved for the Sixth IST interval of the CNP IST Program is currently scheduled to begin on July 1, 2026.
3.2 Staff Evaluation Per the ASME OM Code, valves that have a seat leakage requirement to be limited to a specific amount in the closed position to fulfill their required function are classified as Category A valves.
Category A valves must meet the requirements of ASME OM Code, Subsection ISTC, paragraph ISTC-3600, Leak Testing Requirements. ASME OM Code, Subsection ISTC, subparagraph ISTC-3630, Leakage Rate for Other Than Containment Isolation Valves, states, in part, under (b), Differential Test Pressure, that Valve seat tests shall be made with the pressure differential in the same direction as when the valve is performing its function.
In Relief Request REL-002, the licensee notified the NRC staff that the ASME OM Code requirements for leak testing are not practical for the valves listed in Table 1 of this safety evaluation in accordance with 10 CFR 50.55a(f)(5)(iii). The licensees original design and analysis concluded that these valves did not have a need to specify leakage criteria, and were listed in the IST program as Category B valves. However, Information Notice 91-56, Potential Radioactive Leakage to Tank Vented to Atmosphere, prompted the licensee to re-evaluate the valve categorization, with its determination that the valves needed to be upgraded to Category A in the IST program at CNP.
In 10 CFR 50.55a(f)(6)(i), the NRC regulations state that the Commission will evaluate determinations under 10 CFR 50.55a(f)(5) that ASME OM Code requirements are impractical.
The NRC has determined that the existing system design precludes the seat leakage testing of the valves within the scope of Relief Request REL-002 in the direction specified by the OM Code requirements. In Relief Request REL-002, the licensee describes significant system modifications, requiring an extended out-of-service time for the ECCS, that would be required to accommodate compliance with the ASME OM Code requirements, and would result in a non-standard system configuration. Therefore, the NRC staff has determined that it is impractical for the licensee to comply with the ASME OM Code requirement to conduct leakage tests for the subject valves in the accident direction. In 10 CFR 50.55a(f)(6)(i), the NRC regulations state that the Commission may grant relief and may impose such alternative requirements as it determines are authorized by law, will not endanger life or property or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
In Relief Request REL-002, the licensee has proposed an alternative to test the valves in the reverse direction using the static head of the RWST. The NRC granted this relief request for use during previous IST intervals. The safety evaluations completed for the previous intervals for this relief request (ML16054A572 and ML063340516, respectively) remain applicable. A leakage test in the reverse direction to the accident conditions using the head of water in the RWST as the driving force must provide equivalent or more conservative results than a test in the accident direction to be considered adequate. In evaluating the adequacy of the licensees proposed test, the physical construction and arrangement of the valve seat and disk, as well as the pressure forces acting in the attached piping, must be considered. The valves listed in Table 1 are 8-inch, 150 pound flexible wedge gate valves, as discussed in precedent submittals. For this specific valve type, the design of the valve disk and seating surfaces is a symmetrical arrangement where thrust applied by the valves motor operator will tend to seat each wedge face equally. Additionally, the flexible wedge design is robust and will not exhibit significant deformation at the relatively low line pressures (less than 200 pounds per square inch gage) encountered during an accident scenario. These design features provide confidence that both faces of the valve wedge will seat equally to limit overall seat leakage through the valve.
Pressure applied in a seat leakage test will tend to unseat the face of the valve disk closest to the pressure source and seat the downstream face. In that both faces will be equally seated by the actuator thrust, a seat leakage test of these specific valves in either direction will provide a reasonable indication of overall degradation of the seating surfaces. As a result, adequate leak tightness is ensured by the mechanical wedging force provided by the actuator for the valves within the scope of Relief Request REL-002.
During past inspections, the NRC staff evaluated the motor-operated valve (MOV) program established by the licensee in accordance with 10 CFR 50.55a(b)(3)(ii) to demonstrate that MOVs are capable of performing their design-basis safety functions. In this instance, the licensee has adjusted the valves within the scope of this request as part of its MOV program to close against the estimated differential pressure that would exist during the transition from the loss-of-coolant accident (LOCA) injection phase to the LOCA recirculation phase. The seat load on these valves is specifically designed to ensure both seats of the flex wedge are fully seated to remain leak tight under the postulated system conditions. 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 onto the seat with greater force.
Based on its review, the NRC staff has determined that the licensee has justified in Relief Request REL-002 that the ASME OM Code requirement to conduct leakage tests is impractical for the subject valves in the accident direction. Further, the staff finds that the proposed alternative seat leakage test provides reasonable assurance of the operational readiness of the subject valves to isolate the RWST from back leakage during the loss of coolant accident recirculation phase.
The NRC staff notes that the applicable Code of Record for the CNP Sixth IST interval is the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a. The CNP Sixth IST interval is scheduled to begin on July 1, 2026. The ASME OM Code (2022 Edition),
Subsection ISTA, General Requirements, paragraph ISTA-3120, Inservice Examination and Test Interval, as incorporated by reference in 10 CFR 50.55a, requires that licensees implement 10-year intervals for their IST programs. ASME OM Code Case OMN-31, Alternative to Allow Extension of ISTA-3120 Inservice Examination and Test Intervals from 10 to 12 Years, is conditionally accepted in Revision 5 to RG 1.192, Operation and Maintenance Code Case Acceptability, ASME OM Code, which the licensee could voluntarily implement to extend their IST intervals from 10 to 12 years, if they satisfy the conditions on its use. The NRC regulations in 10 CFR 50.55a allow licensees to implement the same ASME OM Code as their Code of Record for two successive IST program intervals. Therefore, the licensee of CNP could implement the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, for both the Sixth and Seventh IST intervals required by the ASME OM Code, Subsection ISTA, paragraph ISTA-3120.
4.0 CONCLUSION
As set forth above, the NRC staff determines that it is impractical for the licensee to comply with certain requirements of the ASME OM Code for the valves listed in Table 1. The proposed alternative in relief request REL-002 provides reasonable assurance that valves listed in Table 1 will remain operationally ready.
Granting relief pursuant to 10 CFR 50.55a(f)(6)(i) is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request remain applicable.
Therefore, the NRC staff authorizes the use of REL-002 for the Sixth IST interval at CNP, which is currently scheduled to begin on July 1, 2026.
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request remain applicable.
Principal Contributor: Nicholas Hansing, NRR Scott Wall, NRR Date: January 28, 2026
K. Ferneau
SUBJECT:
DONALD C. COOK NUCLEAR PLANT, UNIT NOS. 1 AND 2 - ISSUANCE OF RELIEF REQUEST REL-002 ASSOCIATED WITH PUMP INSERVICE TESTING (EPID L-2026-LLR-0001) DATED JANUARY 28, 2026 DISTRIBUTION:
PUBLIC RidsNrrDorlLpl3 Resource RidsRgn3MailCenter Resource RidsNrrLASLent Resource RidsAcrs_MailCTR Resource RidsNrrPMDCCook Resource RidsNrrDexEmib Resource NHansing, NRR Accession No.: ML26023A192
- via memorandum NRR-028 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DNRL/NPHP/BC*
NAME SWall SLent SBailey DATE 01/23/2026 01/27/26 01/21/2026 OFFICE NRR/DORL/LPL3/BC (A)
NRR/DORL/LPL3/PM NAME IBerrios SWall DATE 01/28/2026 01/28/2026 OFFICIAL RECORD COPY