ML25231A236
| ML25231A236 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/26/2025 |
| From: | Geoffrey Miller Plant Licensing Branch II |
| To: | Coleman J Southern Nuclear Operating Co |
| Kalathiveettil, D | |
| References | |
| EPID L-2025-LLR-0006 | |
| Download: ML25231A236 (1) | |
Text
August 26, 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 NOS. 1 AND 2 - INSERVICE TESTING PROGRAM PUMP ALTERNATIVE REQUEST RR-P SIXTH INSERVICE TESTING INTERVAL (EPID L-2025-LLR-0006)
Dear Jamie Coleman:
By letter dated January 30, 2025, Southern Nuclear Operating Company (SNC, the licensee) submitted Alternative Request RR-P-2 for specific pumps during its Sixth Inservice Testing (IST) interval at the Edwin I. Hatch Nuclear Plant (Hatch), Unit Nos. 1 and 2, which is scheduled to begin on January 1, 2026.
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that Alternative Request RR-P-2 for Hatch, Units 1 and 2, provides an acceptable level of quality and safety for the IST activities for the pumps within the scope of the request. Accordingly, 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)(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 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 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 Nos. 50-321 and 50-366
Enclosure:
Safety Evaluation cc: Listserv GLENN MILLER Digitally signed by GLENN MILLER Date: 2025.08.26 08:05:15 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PUMP ALTERNATIVE REQUEST RR-P-2 SIXTH INSERVICE TESTING INTERVAL SOUTHERN NUCLEAR OPERATING COMPANY EDWIN I. HATCH NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-321 AND 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 Alternative Request RR-P-2 to the U.S. Nuclear Regulatory Commission (NRC) for specific pumps 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), Units 1 and 2.
The licensee submitted Alternative Request RR-P-2 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 pumps 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 Units 1 and 2, Sixth IST interval is the 2022 Edition of the ASME OM Code. The Hatch Units 1 and 2, Sixth IST interval is scheduled to begin on January 1, 2026.
3.1 Licensees Alternative Request RR-P-2 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-2 are as follows:
Paragraph ISTB-3500, Data Collection and ISTB-3510, General, requires, in part:
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 components:
Component ID Pump Description / Pump Type ASME Code Class ASME OM Code Category 1E11-C002A Residual Heat Removal Pump 2A /
Centrifugal 2
Group A 1E11-C002B Residual Heat Removal Pump 2B /
Centrifugal 2
Group A 1E11-C002C Residual Heat Removal Pump 2C /
Centrifugal 2
Group A 1E11-C002D Residual Heat Removal Pump 2D /
Centrifugal 2
Group A 2E11-C002A Residual Heat Removal Pump 2A /
Vertical Line Shaft 2
Group A 2E11-C002B Residual Heat Removal Pump 2B /
Vertical Line Shaft 2
Group A 2E11-C002C Residual Heat Removal Pump 2C /
Vertical Line Shaft 2
Group A 2E11-C002D Residual Heat Removal Pump 2D /
Vertical Line Shaft 2
Group A 3.1.3 Licensees Proposed Alternative and Basis for Use In its January 30, 2025, submittal, the licensee states in part:
Plant Hatch proposes to use the existing installed instrumentation during Group A, Comprehensive and Baseline Testing. Even though 1(2)E11-FI-R608A
& B exceed the Code allowable range limit or three times the reference value, the measured parameter is more accurately displayed than the Code requires. The above proposed alternative is acceptable since the variance in the actual test results is more conservative than that allowed by the Code.
Based on the determination that this alternative 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 the Fifth IST interval for Hatch, Units 1 and 2.
In a 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:
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 full-scale range for each analog instrument shall not be greater than three times the reference value. The Residual Heat Removal (RHR) system pump flow indicators 1(2)E11-FI-R608A and R608B, exceed this Code range limit.
This alternative request is a re-submittal of NRC approved 4th and 5th Interval(s)
Relief Request RR-P-4, previously submitted and approved for use for these instruments. 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)
The original installed instrumentation associated with the RHR pumps was not designed with the instrument range limits of OM Code ISTB-3510(b)(1) taken into consideration. The actual instrument ranges and loop accuracies are itemized below.
Instrument Range Reference Value Allowed Range Accuracy 1E11-FI-R608A&B 0-25000 gpm 7700 gpm 0-23100 gpm
+/- 0.87%
2E11-FI-R608A&B 0-25000 gpm 7700 gpm 0-23100 gpm
+/- 0.87%
Component Component Accuracy Loop Accuracy Per ISTA-2000 1(2)E11-FT-N015A & B 0.5%
0.87%
1(2)E11-K600A & B 0.5%
0.87%
1(2)E11-FI-R608A & B 0.5%
0.87%
gpm = gallons per minute The licensee also stated in part:
1(2)E11-FI-R608A & B exceed the Code allowable full scale range limit of three times the reference value. The design of the indicator range includes consideration for LPCI flow rate (17,000 gpm for two pumps), whereas the minimum IST pump flow rate reference value is 7,700 gpm for Unit 1 and 2. The Code maximum allowable inaccuracy in measured flow rate would be 462 gpm (i.e.,.02 x 23,100) for Units 1 and 2, whereas the actual maximum inaccuracy is measured flow is 218 gpm (i.e.,.0087 x 25,000) for both Unit 1 and 2. Therefore, the actual accuracy of the installed flow indicators is better than required by the Code, this the range of the indicator exceeding the Code limit of three times the reference value is of no consequence.
3.2
NRC Staff Evaluation
In Alternative Request RR-P-2, 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 RHR pumps.
Paragraph ISTB-3510(b)(1) requires that the full-range of each instrument be no greater than three times the reference value.
The installed flow instrumentation associated with the RHR pumps at Hatch, Units 1 and 2, have a range of 0 to 25,000 gpm and loop accuracy of +/- 0.87 percent. The typical value or reference value for the flowrate of the RHR pumps during testing is 7700 gpm. To meet the requirement of ISTB-3510(b)(1), the flow instrument must have a range limit of 0 to 23,100 gpm (3 x 7,700).
Therefore, the installed flow instrument with a range of 0 to 25,000 gpm does not meet the ASME OM Code requirements. In lieu of the ASME OM Code requirements, the licensee proposed to use the installed instrumentation with a range of 0 to 25,000 gpm, but with a required instrument accuracy of +/-0.87 percent during Group A, Comprehensive, and Preservice Testing, which is more conservative than the ASME OM Code accuracy requirements.
Based on the ASME OM Code required flow instrument range and the ASME OM Code requirement for accuracy of +/- 2 percent, the NRC staff has determined that the ASME OM Code would allow up to a maximum variance of 462 gpm (0.02 x 23,100) in the measured parameters.
Although the installed flowrate instruments exceed the ASME OM Code allowable range limit of three times the reference value, the maximum variance allowed by the higher installed gauge range of 0 to 25,000 gpm and the better than required accuracy of +/-0.87 percent, would be only 218 gpm, which is more conservative than the ASME OM Code allowable variance of 462 gpm.
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 evaluation, the NRC staff has determined that Alternative Request RR-P-2 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 instrument accuracy requirements in the ASME OM Code.
The NRC staff notes that the applicable code of record for the Hatch Units 1 and 2, Sixth IST interval, is the 2022 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a. The Hatch Units 1 and 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. 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 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 has determined that Alternative Request RR-P-2 for Hatch, Units 1 and 2, provides an acceptable level of quality and safety for IST activities for the specific pumps 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 Alternative Request RR-P-2 for the specified pumps 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, Units 1 and 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: August 26, 2025
ML25231A236 NRR-028 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC NAME DKalathiveettil KZeleznock SBailey DATE 08/19/2025 08/21/2025 08/19/2025 OFFICE NRR/DORL/LPL2-1/BC NAME MMarkley (EMiller for)
DATE 08/26/2025