ML23101A025

Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122

ML23101A025
Person / Time
Site:	Browns Ferry
Issue date:	04/11/2023
From:	Sivaraman M Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
EA-22-122 IR 2023090
Download: ML23101A025 (1)

Text

TENNESSEE VALLEY AUTHORITY Post Office Box 2000, Decatur, Alabama 35609-2000 April 11, 2023 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1 and 2 Renewed Facility Operating License No. DPR-33, DPR-52 NRC Docket No. 50-259, 50-260

Subject:

Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122

Reference:

Letter from NRC to TVA, Browns Ferry Nuclear Plant - NRC Inspection Report 05000259/2023090 and 05000260/2023090; and Preliminary White Finding and Apparent Violation dated March 2, 2023 The Enclosure to this letter provides Tennessee Valley Authority's (TVA) response to the subject apparent violation. TVA acknowledges that this condition existed as documented in the inspection report and does not contest the apparent violation. TVAs assessment of this event concurs that it was of White significance.

There are no new commitments contained in this letter. If you have any questions, please contact Christopher L. Vaughn at (256) 729-2636.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 11th day of April, 2023.

Respectfully, Manu Sivaraman Site Vice-President Browns Ferry Nuclear Plant

Enclosure:

Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122

U.S. Nuclear Regulatory Commission Page 2 April 11, 2023 cc: (w/ Enclosure)

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

Enclosure Tennessee Valley Authority Browns Ferry Nuclear Plant Units 1 and 2 Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122 (See Attached)

Enclosure Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122 Restatement of Preliminary White Apparent Violation 05000259/2023090-01, Browns Ferry Unit 1 HPCI Inoperable on July 12, 2022:

An NRC-identified apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI, was identified for the licensees failure to identify and correct a condition adverse to quality associated with the Electro Governor-Remote (EGR) and remote servo subcomponents. This resulted in the inoperability of the Browns Ferry, Unit 1 High Pressure Coolant Injection (HPCI) system on July 12, 2022. Specifically, the licensee failed to promptly identify adverse conditions during the preventive maintenance internal inspection of the EG-R on October 27, 2018, wherein the licensee inspection should have reported observed rust or moisture and initiated a condition report (CR) in accordance with the Section 6.2.5 requirement of Mechanical Preventive Instruction, MPI-0-073-TRB001, HPCI Turbine Preventive Maintenance, Revision 0053.

TVAs Response to the Apparent Violation:

TVA understands and accepts the Apparent Violation. TVAs assessment of this event concurs that having the HPCI system potentially unavailable for 48 days is of White significance.

TVA wishes to clarify that the updated condition monitoring standards of 0.05 percent moisture content was not established by the Terry Turbine Users Group (TTUG) in their August 2021 virtual conference. While this topic was discussed at this conference, the new monitoring standards were not established until the Electric Power Research Institute (EPRI) published The Effects of Moisture in Terry Turbine Lube Oil and Governor Systems" on December 3, 2021.

Reason for the Apparent Violation:

The U1 HPCI EGR actuator failed July 12, 2022, due to rust accumulation on the pilot valve and inner bore, reducing the required clearances needed for the EGR to actuate when demanded. An investigation determined that the root causes of this event were:

Procedural guidance in MPI-0-073-TRB001, High Pressure Coolant Injection (HPCI) Turbine Preventive Maintenance was less than adequate to ensure visual inspection task identifies adverse conditions prior to failure.

Station personnel did not identify risk associated with Unit 1 HPCI EGR reliability when making decisions related to the associated maintenance strategy based on an industry recommendation for oil moisture content that significantly changed.

This investigation also identified the additional contributing cause:

TVA Nuclear Fleet lacks a process to ensure that new or revised EPRI publications are reviewed for site applicability.

Enclosure Response to Preliminary White Finding and Apparent Violation in NRC Inspection Report 05000259/2023090 and 05000260/2023090, EA-22-122 Corrective Steps That Have Been Taken and the Results Achieved:

The EGR and remote servo were promptly replaced. The Browns Ferry, Unit 1, HPCI was declared operable following the completion of corrective maintenance and flow rate testing on July 15, 2022, at 0915 CDT.

TVA has implemented a modification to correct the slope of Browns Ferry, Unit 1 HPCI Gland Seal Condenser leak off lines.

TVA has established a new Preventive Maintenance Activity to place HPCI Auxiliary Lube Oil Pump in service on a biweekly basis to recoat the EGR internals and provide real-time validation of anticipated governor valve response.

(CA 1829973-003)

Corrective Steps that Will Be Taken:

As corrective actions to prevent recurrence, BFN plans to do the following:

Revise the section of MPI-0-073-TRB001, High Pressure Coolant Injection (HPCI) Turbine Preventive Maintenance applicable to the EGR visual inspection. The revised procedure will now include enhanced acceptance criteria (both wording and images) to remove the task performer from knowledge-based performance and ensure that task will be performed in rule-based performance during future inspections. The new inspection instructions will require CR initiation and photographing the inspection results.

(CA 1829973-001)

Revise 0-TI-230L Lubrication Oil Analysis & Monitoring Program, to include HPCI / RCIC moisture content limits, action levels and recovery actions to reflect the new recommended moisture limits. (CA 1829973-002)

TVA also plans to perform the following additional corrective actions:

Implement a modification to correct the slope of the Unit 2 HPCI Gland Seal Condenser leak off lines. (CA 1829973-007) o The Unit 3 HPCI Gland Seal Condenser leak off lines are configured correctly.

Create a TVA Nuclear Fleet Process to review EPRI publications to determine site applicability. This process should include how to get updates from EPRI when new or revised products are issued and how to document the disposition of reviews. (CA 1829973-011)

Date When Full Compliance Will Be Achieved:

The Browns Ferry, Unit 1, HPCI returned to full compliance following the completion of corrective maintenance and flow rate testing on July 15, 2022, at 0915 CDT. All corrective actions are scheduled to be completed by August 2, 2023.