Text

Authorization of Alternative Request RR-P-9 - Sixth Inservice Testing Interval
	ML25267A177
Person / Time
Site:	Hatch ; (NPF-005)
Issue date:	09/25/2025
From:	Markley M; Plant Licensing Branch II
To:	Coleman J; Southern Nuclear Operating Co
	Kalathiveettil, D
References
	EPID L-2025-LLR-0013
	Download: ML25267A177 (1)
	v • d • e

September 25, 2025 Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Co., Inc.

3535 Colonnade Parkway Birmingham, AL 35243

SUBJECT:

EDWIN I. HATCH NUCLEAR PLANT, UNIT NO. 2 - AUTHORIZATION OF ALTERNATIVE REQUEST RR-P SIXTH INSERVICE TESTING INTERVAL (EPID L-2025-LLR-0013)

Dear Jamie Coleman:

By letter dated January 30, 2025, as supplemented by letter dated May 15, 2025, Southern Nuclear Operating Company (SNC, the licensee) submitted Alternative Request RR-P-9 for the 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-9 for Hatch, Unit 2, on the basis that the proposed alternative provides an acceptable level of quality and safety for the IST activities for the American Society of Mechanical Engineers (ASME) pump affected. The Nuclear Regulatory Commission (NRC) staff has completed its review and 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)(1) for this alternative.

Therefore, pursuant to 10 CFR 50.55a(z)(1), the NRC staff authorizes the use of this alternative to the 2022 Edition of the ASME Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (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, Unit 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.

J. Coleman 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: 2025.09.25 14:30:04 -04'00'

Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION AUTHORIZATION OF PUMP ALTERNATIVE REQUEST RR-P-9 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-9 to the U.S. Nuclear Regulatory Commission (NRC) requesting authorization for a proposed alternative for 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-9 pursuant to 10 CFR 50.55a(z)(1),

Acceptable level of quality and safety, on the basis that the proposed alternative will provide an acceptable 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, that:

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.

NUREG-1482, Revision 3, Guidelines for Inservice Testing at Nuclear Power Plants: Inservice Testing of Pumps and Valves and Inservice Examination and Testing of Dynamic Restraints (Snubbers) at Nuclear Power Plants (ML20202A473), July 2020.

3.0 TECHNICAL EVALUATION

The applicable Code of Record for 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-9 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-9 are as follows:

Paragraph ISTB-3500, Data Collection and ISTB-3510, General, requires, in part, that:

a) Accuracy. Instrument accuracy shall be within the limits of Table ISTB-3510-1. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirements of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within

+/-2% of actual). For individual analog instruments, the required accuracy is percent of full-scale. For digital instruments, the required accuracy is over the calibrated range. For a combination of instruments, the required accuracy is loop accuracy.

b) Range (1) The full-scale range for each analog instrument shall not be greater than 3 times the reference value.

Table ISTB-3510-1, Required Instrument Accuracy, provides the required instrument accuracy for pump tests conducted in accordance with the requirements of Subsection ISTB.

3.1.2 Components 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 In its January 30, 2025, submittal, the licensee states, in part, that:

The installed instrumentation will be utilized to determine the flowrate for the SDSW [Standby Diesel Generators Service Water] pump test. The use of this instrumentation is supported by the guidance contained in NRC NUREG-1482, Revision 3, Section 5.5.1, since the combined range and accuracy variance of the installed instrumentation is within the maximum allowable variance of the OM Code. This request applies to flowrate measurements for Group B, Comprehensive and Baseline Testing.

The above proposed alternative provides reasonable assurance of operational readiness since the accuracy of the instrumentation is better than the absolute accuracy required by the Code. Based on the determination that compliance with the Code requirements provides an acceptable level of quality and safety, this proposed alternative should be authorized pursuant to 10 CFR 50.55a(z)(1).

By letter dated December 30, 2015 (ML15310A406), a similar alternative request was authorized for Hatch, Unit 2.

In its supplemental letter dated May 15, 2025, 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:

Pursuant to 10 CFR 50.55a(z)(1), relief is requested from the requirements of the ASME OM Code, 2022 Edition, Subsection ISTB-3510(b)(1) which requires that the full-range of analog instruments shall not be greater than three times the reference value, and Table ISTB-3510-1, which requires an accuracy of +/- 2% full scale.

This alternative request is a re-submittal of NRC approved 4th and 5th Interval(s)

Relief Request RR-P-12, 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 flowrate for the Unit 2 Standby Diesel Generators Service Water (SDSW) pump is determined by measuring the differential pressure (dp), in inches of water, across a flow element and then using the vendor correlation chart to convert dp to flowrate in gallons per minute (gpm). The dp indicator (2P41-R383) has a full-scale range of - 178 inches of water to + 178 inches of water (356 inches total range), which is greater than 3 times the reference value, and is calibrated to +/- 4 inches of water (i.e., +/- 1.125% of full scale). The indicator has a range which allows measurement of the flowrate in either direction across the flow element, thus the negative and positive scale ranges. The vendor supplied dp to flow correlation chart has a range of 50 - 145 inches of water which corresponds to a flowrate range of 500 - 850 gpm.

The reference flow for this pump is 707 gpm which corresponds to 100 inches of water. The OM Code would allow a full-scale range of 0 - 300 inches of water (i.e., 3 X 100) and a calibration accuracy of +/- 6.0 inches of water (i.e., 0.02 X 300).

The combined range and accuracy of the installed instruments is within the maximum allowable of ISTB-3510(b)(1) and Table ISTB-3510-1. The maximum Code allowable dp variance would be +/- 6.0 inches of water, whereas the actual dp variance is +/- 4.0 inches of water. Therefore, use of the existing dp indicators and the vendor correlation chart provides flowrate measurements for IST that are least as accurate as required by the OM Code.

3.2

NRC Staff Evaluation

In RR-P-9, the licensee has proposed an alternative approach to the instrumentation requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1), for instruments that are used to measure the flowrate of the SDSW pump. Paragraph ISTB-3510(b)(1) requires that the full-range of each instrument be no greater than three times the reference value.

In lieu of measuring flow rate using an ASME OM Code allowed instrument with required loop accuracy of +/-2 percent, the flowrate for the Hatch, Unit 2, SDSW pump is proposed to be determined by measuring the differential pressure (dp), in inches of water, across a flow element and then using the vendor correlation chart to convert dp to flowrate in gpm. The dp indicator (2P41-R383) has a full scale range of -178 inches of water to +178 inches (356 inches total range) of water. The vendor supplied dp to flow correlation chart has a range of 50 to 145 inches of water which corresponds to a flowrate range of 500 to 850 gpm. The reference flow for this pump is 707 gpm which corresponds to 100 inches of water. To meet the requirement of ISTB-3510(b)(1), the flow instrument shall have a range limit of 300 inches of water (3 x 100). Therefore, the installed flow instrument with a range of 356 inches of water does not meet the ASME OM Code requirement. In lieu of the ASME OM Code requirements, the licensee proposed to use the installed instrumentation and flow correlation chart but to calibrate the dp indicator to +/-4 inches of water.

Based on the ASME OM Code required flow instrument range of 300 inches of water and the loop accuracy of +/-2 percent, the NRC staff finds that the ASME OM Code would allow a calibration accuracy up to +/-6.0 inches of water (i.e., 0.02 X 300) for an ASME OM Code allowed range of 0 to 300 inches of water. Although the installed flowrate instrument (356 inches of water) exceeds the ASME OM Code allowable range limit of three times the reference value, the licensees proposal to calibrate the dp indicator to +/-4 inches of water would yield an actual dp variance that is more conservative than the ASME OM Code allowable variance of +/-6 inches of water. Based on the above, the NRC staff finds that the proposed alternative will provide a more accurate measured value of the parameters than required by the ASME OM Code, and therefore, is acceptable.

The use of the existing instrument is supported by NUREG-1482, Revision 3, Guidelines for Inservice Testing at Nuclear Power Plants, paragraph 5.5.1, which addresses potential NRC approval when the combination of range and accuracy yields a reading at least equivalent to that achieved using instruments that meet the Code requirements.

Based on the above, the NRC staff has determined that Alternative Request RR-P-9 may be authorized pursuant to 10 CFR 50.55a(z)(1) on the basis that the proposed alternative provides an acceptable level of quality and safety in lieu of the applicable pump instrumentation requirements in the ASME OM Code.

The NRC staff notes that the applicable code of record for Hatch, Unit 2, Sixth IST interval, is the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a. 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 determined that proposed alternative numbered RR-P-9 for Hatch, Unit 2, provides an acceptable level of quality and safety for IST activities for the specific affected pump within the scope of the request. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1) for this proposed alternative. Therefore, pursuant to 10 CFR 50.55a(z)(1), the NRC staff authorizes RR-P-9 for the Sixth IST Interval for the specified pump within the scope of the request in lieu of the applicable IST requirements in 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.