ML25272A289
| ML25272A289 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 09/29/2025 |
| From: | David Brown Energy Northwest |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| GO2-25-117 | |
| Download: ML25272A289 (1) | |
Text
David P. Brown Columbia Generating Station P.O. Box 968, PE23 Richland, WA 99352-0968 509.377.8385 dpbrown@energy-northwest.com GO2-25-117 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
COLUMBIA GENERATING STATION, DOCKET NO. 50-397 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE COLUMBIA TS 3.3.2.1 CONTROL ROD BLOCK INSTRUMENTATION References: 1. Letter from Energy Northwest to NRC, License Amendment Request to Revise Columbia Generating Station Technical Specification 3.3.2.1, Control Rod Block Instrumentation, dated March 21, 2025 (ADAMS Accession Number ML25083A158)
- 2. Letter from NRC to Energy Northwest, Final Request for Additional Information - Columbia - LAR to Revise Columbia Generating Station TS 3.3.2.1, Control Rod Block Instrumentation - EPID: L-2025-LLA-0057, dated September 4, 2025 (ADAMS Accession Number ML25248A004)
Dear Sir or Madam:
By Reference 1, Energy Northwest submitted a license amendment request to revise the Columbia Generating Station Technical Specification 3.3.2.1, Control Rod Block Instrumentation. In Reference 2, the Nuclear Regulatory Commission requested additional information to support the Energy Northwest submittal. The enclosure to this letter contains the information requested in Reference 2.
There are no regulatory commitments made in this submittal.
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September 29, 2025 ENERGY NORTHWEST
GO2-25-117 Page 2 of 2 If you have any questions or require additional information, please contact Ms. T. M. Collis at 509-377-8395.
I declare under penalty of perjury that the foregoing is true and correct.
Executed this ____ day of BBBBBBBBBBB, 2025.
Respectfully, David P. Brown Site Vice President
Enclosure:
Response to Request for Additional Information Regarding License Amendment Request to Revise Columbia Technical Specification 3.3.2.1, Control Rod Block Instrumentation cc:
NRC RIV Regional Administrator NRC NRR Project Manager NRC Senior Resident Inspector/988C CD Sonoda - BPA JW Hayes - BPA EFSECutc.wa.gov - EFSEC E Fordham - WDOH R Brice - WDOH L Albin - WDOH
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GO2-25-117 Enclosure Page 1 of 3 Response to Request for Additional Information Regarding License Amendment Request to Revise Columbia Technical Specification 3.3.2.1, Control Rod Block Instrumentation
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Background===
By application dated March 21, 2025 (ADAMS Accession No. ML25083A158), pursuant to Section 50.90 of Title 10 of the Code of Federal Regulations (CFR), Energy Northwest submitted a License Amendment Request (LAR) for Columbia Generating Station (Columbia). The licensees proposed amendment would modify Columbias Technical Specification (TS) 3.3.2.1, Control Rod Block Instrumentation, Required Action C.2.1.2, which currently restricts reactor startup with an inoperable rod worth minimizer (RWM) to once per calendar year. The proposed change to the Required Action C.2.1.2 would be to allow additional reactor startups with a new action to verify control rod coupling inspections have been performed prior to a reactor restart.
Regulatory Basis 10 CFR 50, Appendix A General Design Criterion 28, Reactivity Limits, states that The reactivity control systems shall be designed with appropriate limits on the amount and rate of reactivity increase to assure that the effects of postulated reactivity accidents can neither (1) result in damage to the reactor coolant pressure boundary greater than limited local yielding, nor (2) sufficiently disturb the core, its support structures, or other reactor pressure vessel internals to impair significantly the capability to cool the core. These postulated reactivity accidents shall include consideration of rod ejection (unless prevented by positive means), rod dropout, steam line rupture, changes in reactor coolant temperature and pressure, and cold-water addition.
Question 1 SNSB RAI-1 The LAR enclosure, Section 3.2, fourth paragraph states:
The inadvertent Operator-initiated withdrawal of a single control rod from the core is classified as a nonlimiting transient event.
Provide responses to the following questions:
x Compared to which other transient events during startup is it nonlimiting?
x What are the parameters due to which this event is considered nonlimiting?
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GO2-25-117 Enclosure Page 2 of 3 Energy Northwest Response to SNSB RAI-1:
Part 1 Regardless of the operability of the Rod Worth Minimizer System, the Operator-initiated control rod withdrawal error is not a credible transient in either the startup or low power ranges. There are no other transient events during startup to compare the control rod withdrawal error with since the event itself is not probable.
Part 2 No mathematical models are involved in this event. The need for input parameters or initial conditions is not required, as there are no results to report.
Question 2 SNSB RAI-2 FSAR Section 7.7.1.2.2.2, Rod Block Trip System, paragraph b.2.(e) states:
The RWM [Rod Worth Minimizer] can initiate a rod insert block and a rod withdrawal block. The purpose of these functions is to reinforce procedural controls that limit the reactivity worth of control rods under lower power conditions. The rod block trip settings are based on the allowable control rod worth limits established for the design basis rod drop accident. Adherence to prescribed control rod patterns is the normal method by which this reactivity restriction is observed.
According to the above description, the RWM system is provided with rod block and rod withdrawal trip settings established for the rod drop accident. In the absence of the RWM system, explain how these trips at the same trip setting in the RWM are accomplished.
Energy Northwest Response to SNSB RAI-2:
The terms rod withdrawal block and rod withdrawal trip are used interchangeably, particularly in Final Safety Analysis Report (FSAR) Section 7.7.1.2.2.2, Rod Block Trip System. The Rod Worth Minimizer (RWM) is only capable of generating rod insertion blocks and rod withdrawal blocks; the system is not capable of generating a scram signal.
There is no other system or component that generates the rod insertion block or rod withdrawal block at the same settings as the RWM. However, in the absence of the RWM System, second licensed Operator or qualified member of the technical staff enforces adherence to the established startup, shutdown, and low power level control rod sequences. This enforcement is preventive in nature, as the control rod selection is verified prior to rod movement made by the first Operator, preventing the establishment of control rod patterns that are not consistent with the approved rod position sequence.
Verification that control rod movement is in compliance with the banked position withdrawal sequence is required to meet Technical Specification 3.1.6, Rod Pattern Control, and Technical Specification 3.3.2.1, Control Rod Block Instrumentation, requirements.
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GO2-25-117 Enclosure Page 3 of 3 Question 3 SNSB RAI-3 For the RWM function to be bypassed or inoperable, its block function would be disabled.
Please confirm that for each startup without RWM, the specific procedural controls a, b, c, and d initiated by the Operator listed in FSAR Section 7.7.1.10.2, Operation, will be implemented. In case these controls are changed, provide the revised controls justifying their adequacy.
Energy Northwest Response to SNSB RAI-3:
The specific procedural controls listed in a, b, c, and d of Final Safety Analysis Report (FSAR) Section 7.7.1.10.2, Operation, are not being changed. Future changes to the procedural controls would require a license amendment, as the controls for b and d of FSAR Section 7.7.1.10.2 are enforced by Required Action C.2.2 of Technical Specification 3.3.2.1, Control Rod Block Instrumentation.
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