ML26027A002
| ML26027A002 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/26/2026 |
| From: | Kimberly Green Plant Licensing Branch II |
| To: | Eckermann J Tennessee Valley Authority |
| Green K | |
| References | |
| EPID L-2025-LLA-0121 | |
| Download: ML26027A002 (0) | |
Text
From:
Kimberly Green To:
Eckermann, J Beau Cc:
Edmondson, Carla
Subject:
Request for Additional Information - TVA LAR to Revise Browns Ferry TS 3.3.2.1 re Rod Worth Minimizer (EPID L-2025-LLA-0121)
Date:
Monday, January 26, 2026 12:54:00 PM Attachments:
- Beau,
By \
letter dated July 31, 2025 (Agencywide Documents Access and Management System Accession No. ML25212A156), the Tennessee Valley Authority (TVA) submitted a license amendment request for Browns Ferry Nuclear Plant, Units 1, 2, and 3 (Browns Ferry). The proposed amendments would revise Browns Ferry Technical Specification 3.3.2.1, Control Rod Block Instrumentation, to modify Required Action C.2.1.2 regarding the rod worth minimizer.
The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has identified areas where additional information is needed to complete its review.
Attached, please find a draft request for additional information (RAI). A draft RAI was previously transmitted to you be email on December 18, 2025. At your request, a clarification call was held on January 21, 2026, to clarify the NRC staffs request. As a result of the clarification call, the NRC has eliminated SNSB-RAI 1 and SNSB-RAI 2.b as shown in redline/strikeout below. SNSB-RAI 2 will become SNSB-RAI and part a will be de-lettered.
Requests
SNSB-RAI 1
Browns Ferry Updated Final Safety Analysis (UFSAR) (ML25295A491) section 7.7.4.3.2 states that the RWM function reinforces procedural controls that limit the reactivity worth of control rods under low 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 method by which this reactivity restriction is observed.
Describe the procedural controls that are referenced in UFSAR section 7.7.4.3.2. Provide a discussion on how the RWM function reinforces procedural controls and how the reinforcement of the procedural controls will be established if the RWM is in bypass or when it is inoperable.
SNSB-RAI 2
In the LAR enclosure, section 3.2, the fourth paragraph states, in part:
The inadvertent operator-initiated withdrawal of a single control rod from the core is classified as a non-limiting transient event.
As discussed in Section 14.5 of the BFN UFSAR, the RWE
[control rod withdrawal error] at low power is categorized as an infrequent accident and is not considered credible during reactor startup or during low power ranges.
Provide responses to the following:
- a. On reviewing BFN UFSAR section 14.5, specifically subsection 14.5.4.2, Continuous Rod Withdrawal During Reactor Startup, the NRC staff could not find the statement that RWE at low power is categorized as an infrequent accident and is not considered credible during reactor startup or during low power ranges. Please clarify.
- b. In reference to the statement from the LAR (cited above), state which events and explain in what aspect during startup is this event non-limiting.
A response to the attached RAI is requested in 30 days from the date of this email.
The NRC staff considers that timely responses to RAIs help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response time, please me at (301)415-1627 or via email atKimberly.Green@nrc.gov.
Sincerely, Kimberly J. Green, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
REQUEST FOR ADDITIONAL INFORMATION BY OFFICE OF NUCLEAR REACTOR REGULATION CHANGES TO TECHNICAL SPECIFICATION 3.3.2.1, CONTROL ROD BLOCK INSTRUMENTATION FOR BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2, and 3 DOCKET NOS. 50-259, 50-260, & 50-296 EPID L-2025-LLA-0121 Introduction By application dated July 31, 2025 (ADAMS Accession No. ML25212A156), Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) for Browns Ferry Nuclear Plant, Units 1, 2, and 3 (BFN). The proposed amendment would modify BFN, Technical Specification 3.3.2.1, Control Rod Block Instrumentation, Required Action C.2.1.2, regarding the rod worth minimizer (RWM). The proposed change will replace the once per calendar year allowance of reactor startup with an inoperable RWM with an action to verify that control rod coupling checks have been performed, which will allow an unrestricted number of reactor startups with RWM inoperable while using independent verification of banked position withdrawal sequence compliance.
The U.S. Nuclear Regulatory Commission (NRC) staff is currently reviewing the LAR and has identified areas where additional information is needed to complete its review. The request for additional information (RAI) is identified below.
Regulatory Basis Appendix A, General Design Criteria [GDC] for Nuclear Power Plants, to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, establishes the minimum requirements for the principal design criteria for water-cooled nuclear power plants. The principal design criteria establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety. GDC 28, Reactivity Limits, states:
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.
Request SNSB-RAI In the LAR enclosure, section 3.2, the fourth paragraph states, in part:
The inadvertent operator-initiated withdrawal of a single control rod from the core is classified as a non-limiting transient event. As discussed in Section 14.5 of the BFN UFSAR, the RWE [control rod withdrawal error] at low power is categorized as an infrequent accident and is not considered credible during reactor startup or during low power ranges.
On reviewing BFN UFSAR section 14.5, specifically subsection 14.5.4.2, Continuous Rod Withdrawal During Reactor Startup, the NRC staff could not find the statement that RWE at low power is categorized as an infrequent accident and is not considered credible during reactor startup or during low power ranges. Please clarify.