ML25260A654
| ML25260A654 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 09/23/2025 |
| From: | Markley M Plant Licensing Branch II |
| To: | Coleman J Southern Nuclear Operating Co |
| Kalathiveettil, D | |
| References | |
| EPID L-2025-LLR-0011 | |
| Download: ML25260A654 (8) | |
Text
September 23, 2025 Ms. Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Co., Inc.
3535 Colonnade Parkway Birmingham, AL 35243
SUBJECT:
EDWIN I. HATCH NUCLEAR PLANT, UNIT 2 - AUTHORIZATION OF ALTERNATIVE REQUEST RR-P SIXTH INSERVICE TESTING INTERVAL (EPID L-2025-LLR-0011)
Dear Ms. Coleman:
By letter dated January 30, 2025, Southern Nuclear Operating Company (SNC, the licensee) submitted Alternative Request RR-P-7 for specific pumps during its Sixth Inservice Testing (IST) interval at the Edwin I. Hatch Nuclear Plant (Hatch), Unit 2, which is scheduled to begin on January 1, 2026.
The licensee requested Alternative Request RR-P-7 for Hatch, Unit 2, on the basis that compliance with the testing requirements in the 2022 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) for the pump affected would result in hardship without a compensating increase in the level of quality and safety. The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review and determined that Alternative Request RR-P-7, provides reasonable assurance that the affected component is operationally ready to perform its safety functions. The NRC staff concludes that SNC has adequately addressed the regulatory requirements set forth in Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.55a, Codes and standards, paragraph (z)(2) for this proposed alternative.
Therefore, pursuant to 10 CFR 50.55a(z)(2), the NRC staff authorizes the use of this alternative to the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, for the Code of Record interval, as defined in 10 CFR 50.55a(y), Definitions, that implements the 2022 Edition of the ASME OM Code, for Hatch, Units 1 and 2. Use of this alternative with other Codes of Record is not authorized.
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, Dawnmathews Kalathiveettil at Dawnmathews.Kalathiveettil@nrc.gov or 301-415-5905.
Sincerely, Michael Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-366
Enclosure:
Safety Evaluation cc: Listserv MICHAEL MARKLEY Digitally signed by MICHAEL MARKLEY Date: 2025.09.23 17:51:31 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION AUTHORIZATION OF PUMP ALTERNATIVE REQUEST RR-P-7 SIXTH INSERVICE TESTING INTERVAL SOUTHERN NUCLEAR OPERATING COMPANY EDWIN I. HATCH NUCLEAR PLANT, UNIT NO. 2 DOCKET NO. 50-366
1.0 INTRODUCTION
By letter dated January 30, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25030A363), and supplemented by letter dated May 15, 2025 (ML25135A409), Southern Nuclear Operating Company (SNC, the licensee) submitted RR-P-7 to the U.S. Nuclear Regulatory Commission (NRC) requesting authorization for a proposed alternative for a specific affected pump in lieu of certain inservice testing (IST) requirements of the 2022 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code), as incorporated by reference in Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.55a, Codes and standards, for the Sixth Inservice Testing (IST) interval at the Edwin I. Hatch Nuclear Plant (Hatch), Unit 2.
The licensee submitted Alternative Request RR-P-4 pursuant to 10 CFR 50.55a(z)(2), Hardship without a compensating increase in quality and safety, on the basis that compliance with the specified ASME OM Code requirements would result in a hardship without a compensating increase in the level of quality and safety for IST activities applied to the specific affected pump within the scope of this request.
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(z), Alternative to codes and standards requirements, state, in part, that alternatives to the requirements of paragraphs (b) through (h) of 10 CFR 50.55a 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
The applicable Code of Record for the Hatch, Unit 2, Sixth IST interval is the 2022 Edition of the ASME OM Code. The Hatch, Unit 2, Sixth IST interval is scheduled to begin on January 1, 2026.
3.1 Licensees Alternative Request RR-P-7 3.1.1 Applicable ASME OM Code Requirements The requirements in the ASME OM Code, Subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, as incorporated by reference in 10 CFR 50.55a, related to Alternative Request RR-P-7 are as follows:
Paragraph ISTB-3540, Vibration, states, in part, that:
(b) 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.
3.1.2 Component for Which Alternative is Requested The alternative was proposed for the following component:
Component ID Pump Description / Pump Type ASME Code Class ASME OM Code Category 2P41-C002 Unit 2 Standby Diesel Service Water Pump
/ Vertical Line Shaft 3
Group B 3.1.3 Licensees Proposed Alternative and Basis for Use In its January 30, 2025, submittal, the licensee states in part, that:
Vibration measurements will be taken in three orthogonal directions, one of which is in the axial direction around the pump to motor mounting flange. This is the closest accessible location to a pump bearing housing and this location is easily and safely accessible for test personnel which would ensure repeatable vibration data and should provide readings which are at least as representative of pump mechanical condition as those required by the Code. Vibration measurements have been taken in the same locations in prior intervals and have provided adequate data to monitor for degradation.
Therefore, application of the OM Code hydraulic testing criteria along with radial and axial vibration monitoring around the pump to motor mounting flange should provide adequate data for assessing the condition of the Standby Diesel Generator Service Water Pump. This request is only applicable to Comprehensive and Baseline Pump Testing. The above proposed alternative provides reasonable assurance of operational readiness since vibration measurements will be taken in three orthogonal directions at the pump to motor mounted flange which will provide information as to the mechanical integrity of the pump. Based on the determination that compliance with the Code requirements results in hardship without a compensating increase in the level of quality and safety, this proposed alternative should be authorized pursuant to 10 CFR 50.55a(z)(2).
By letter dated December 30, 2015 (ML15310A406), a similar alternative request was authorized for Hatch, Unit 2.
In its letter dated May 15, 2025 (ML25135A409), the licensee confirmed that Pump Periodic Verification Tests are not within the scope of this alternative request.
3.1.4 Licensees Reason for its Request In its January 30, 2025, submittal, the licensee states, in part, that:
Pursuant to 10 CFR 50.55a(z)(2), relief is requested from the requirements of the ASME OM Code, 2022 Edition, Subsection ISTB-3540(b) which requires that vibration measurements on vertical line shaft pumps be taken on the upper motor-bearing housing in three approximately orthogonal directions, one of which is the axial direction.
This alternative request is a re-submittal of NRC approved 4th and 5th Interval(s)
Relief Request RR-P-9, previously submitted and approved for use of the alternative method used to measure vibration for the Plant Hatch Unit 2 Diesel Service Water Pump. There have been no substantive changes to this alternative or to the basis for use, which would alter the previous NRC Safety Evaluation conclusions for previous IST Intervals for Plant Hatch. (See Precedents for SERs
[safety evaluation reports]).
The Code required vibration measurements on the upper motor housing on this Unit 2 Standby Diesel Generator Service Water vertical line shaft pump are impractical because of the following condition:
The motor has a cooling fan mounted at the top which is attached to the rotating shaft. The fan is protected by a relatively thin cover plate which prevents access to the motor housing for vibration measurements.
Removing the cover does not provide for transducer placement since the rotating fan would still be in the way.
3.2
NRC Staff Evaluation
In RR-P-7, the licensee has proposed an alternative approach to the vibration measurement requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3540(b), for the standby diesel generator service water pump 2P41-C002 because the upper motor-bearing housing is inaccessible to test personnel.
The ASME OM Code recognizes the value of implementing a vibration analysis strategy for monitoring vertical line shaft pumps by requiring measurements to be taken on the upper motor-bearing housing in three orthogonal directions, one of which is the axial direction. The licensee proposes obtaining vibration measurements on the vertical line shaft standby diesel generator service water pump 2P41-C002 at three orthogonal directions, one of which is in the axial direction in the area of the pump-to-motor mounting flange. The vibration measurements cannot be measured directly because the motor has a cooling fan mounted at the top that is attached to the rotating shaft. The fan is protected by a relatively thin cover plate which prevents access to the motor housing for vibration measurements. Removing the cover does not provide for transducer placement because the rotating fan would cause interference. Therefore, the requirement for pump vibration measurements for the vertical line shaft pump to be taken on the upper motor-bearing housing is not feasible and results in a hardship. The licensees proposed testing provides reasonable assurance of operational readiness because the licensee will be taking vibration measurements in three orthogonal directions, one of which is axial at the pump-to-motor mounting flange which provides information as to the mechanical integrity of the pump. The vibration measurements will be tracked and trended along with the hydraulic performance test data.
Obtaining vibration measurements in three orthogonal directions, one of which is in axial direction in the area of the pump-to-motor mounting flange along with the hydraulic performance will provide performance data as to the mechanical integrity of the pump and motor assembly.
Parameters such as bearing health, pump/motor unbalance, pump/motor looseness, electrical faults, and resonance issues can be monitored using these measurement points. The licensee has obtained vibration measurements at these locations for these pumps and motors in the previous IST interval. Measuring vibration at these locations has proven to provide early indication of abnormal pump/motor performance. The collected data at three orthogonal locations, one of which is in the axial direction in the area of the pump to motor mounting flange, coupled with the trending of pump hydraulic performance data, provides an acceptable alternative for monitoring component health.
In its letter dated May 15, 2025 (ML25135A409), in response to an NRC request for additional information, the licensee provided performance history information and historical vibration measurement data collected at the proposed alternative locations for the pumps within the scope of RR-P-7. The NRC staff reviewed this information and agreed with the licensees statement that the alternative locations have provided adequate data to monitor for degradation. The licensee took appropriate corrective action when the subject pumps entered the action or alert range, up to and including pump replacement.
Based on the above, the NRC staff has determined that requiring the licensee to meet the requirements for the vibration measurement locations for this specific pump at Hatch, Unit 2, required by the ASME OM Code would result in a hardship without a compensating increase in the level of quality and safety. In consideration of the reasonably good performance history of these pumps while using the alternate vibration measurement locations and the acceptance by the NRC staff of alternate vibration measurement locations for other pumps and motors, the NRC staff finds that measuring vibrations at the locations requested by the licensee is acceptable and provides reasonable assurance of the operational readiness of this pump.
Therefore, the NRC staff finds that RR-P-7 may be authorized in accordance with 10 CFR 50.55a(z)(2) for the applicable pump at Hatch, Unit 2.
The NRC staff notes that the applicable Code of Record for the Hatch, Unit 2, Sixth IST interval, is the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a. The Hatch, Unit 2, Sixth IST interval, is scheduled to begin on January 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. Although not requested, the NRC regulations in 10 CFR 50.55a allow licensees to implement the same ASME OM Code as their Code of Record for two consecutive IST program intervals.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that proposed alternative numbered RR-P-7 for Hatch, Unit 2, provides reasonable assurance that the affected pump will be operationally ready. The NRC staff has also determined that the licensee has justified that compliance with the testing requirements in the ASME OM Code for the pump within the scope of this request would result in hardship without a compensating increase in the level of quality and safety.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2) for this proposed alternative.
Therefore, pursuant to 10 CFR 50.55a(z)(2), the NRC staff authorizes the use of Alternative Request RR-P-7 for the Sixth IST Interval for the specified pump in lieu of the IST requirements of the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, for Hatch, Unit 2, for the Code of Record interval, as defined in 10 CFR 50.55a(y), Definitions, that implements the 2022 Edition of the ASME OM Code. Use of this alternative with other codes of record is not authorized.
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 G. Bedi, NRR Date: September 23, 2025
ML25260A654 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC NAME DKalathiveettil KZeleznock SBailey DATE 09/17/2025 09/19/2025 09/19/2025 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley DKalathiveettil DATE 09/23/2025 09/23/2025