05000316/LER-2024-003, Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage

Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage

ML24235A156
Person / Time
Site:	Cook
Issue date:	08/22/2024
From:	Ferneau K Indiana Michigan Power Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
AEP-NRC-2024-66 LER 2024-003-00
Download: ML24235A156 (1)

LER-2024-003, Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
3162024003R00 - NRC Website

text

INDIANA MICHIGAN POWIR-An MP Company BOUNDLESS ENERGY-August 22, 2024 Docket No.: 50-316 U. S. Nuclear Regulatory Commission A TIN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Donald C. Cook Nuclear Plant Unit 2 LICENSEE EVENT REPORT 316/2024-003-00 Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, Ml 49106 indianamichiganpower.com AEP-NRC-2024-66 10 CFR 50.73 Unit 2 Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage In accordance with 10 CFR 50. 73, Licensee Event Report (LER) System, Indiana Michigan Power Company, the licensee for Donald C. Cook Nuclear Plant Unit 2, is submitting as an enclosure to this letter the following report:

LER 316/2024-003-00: Unit 2 Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage There are no commitments contained in this submittal.

Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Director, at (269) 466-2649.

Sincerely,

~t~

Kelly J. Ferneau Site Vice President MPH/kmh Enclosure:

Licensee Event Report 316/2024-003-00: Unit 2 Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage

U.S. Nuclear Regulatory Commission Page 2 c:

EGLE - RMD/RPS J. B. Giessner -- NRC Region Ill NRC Resident Inspector N. Quilico -- MPSC R. M. Sistevaris -- AEP Ft. Wayne S. P. Wall, NRC Washington D.C.

A. J. Williamson -- AEP Ft. Wayne AEP-NRC-2024-66

Enclosure to AEP-NRC-2024-66 Licensee Event Report 316/2024-003-00: Unit 2 Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage

Abstract

On June 27, 2024, at 0803 hours0.00929 days <br />0.223 hours <br />0.00133 weeks <br />3.055415e-4 months <br /> EDT, a Unit 2 shutdown was completed in accordance with Technical Specification (TS) 3.4.13, Reactor Coolant System (RCS) Operational Leakage, Condition C. On June 26, 2024, at 2303 hours0.0267 days <br />0.64 hours <br />0.00381 weeks <br />8.762915e-4 months <br />, a packing leak developed on 2-QRV-251,

Chemical Volume & Control System (CVCS) Charging Pumps Discharge Flow Control Valve, which was determined to be greater than the 10 gallons per minute (gpm) limit per TS. The packing for 2-QRV-251 was replaced and the valve was returned to service.

Following the manual Unit 2 Reactor Trip, per normal plant shutdown operating procedures, at approximately 17 percent(%) power, the Unit 2 Turbine Driven Auxiliary Feedwater Pump (TDAFP) automatically started when two steam generator levels reached less than the low-low setpoint.

)

The completion of the plant shutdown required by TS is reportable as a License~ Event Report (LER) in accordance with 10CFR 50.73(a)(2 (i)

(A) and the Unit 2 TDAFP Auto Start is reportable in accordance with 10CFR 50.73(a)(2)(iv)(A).

I EVENT DESCRIPTION

2. DOCKET NUMBER

3. LER NUMBER I

00316 NUMBER NO.

I YEAR SEQUENTIAL REV

~-,

003 1-0 On June 27, 2024, at 0803 hours0.00929 days <br />0.223 hours <br />0.00133 weeks <br />3.055415e-4 months <br /> EDT, a Unit 2 shutdown was completed in accordance with Technical Specification (TS) 3.4.13, Reactor Coolant System (RCS) [AB] Operational Leakage, Condition C. On June 26, 2024, at 2302 hours0.0266 days <br />0.639 hours <br />0.00381 weeks <br />8.75911e-4 months <br /> EDT, with Unit 2 operating in Mode 1 at 100 percent (%) power, a packing leak developed on 2-QRV-251, Chemical Volume & Control System (CVCS) [CB] Charging Pumps Discharge Flow Control Valve [FCV]. The leak rate was determined, through monitoring by Control Room operators, to be approximately 11.8 gallons per minute (gpm) and not repairable at power.

Since this leak rate was greater than the 10 gpm limit allowed per TS 3.4.13 for identified leakage, TS 3.4.13, Condition B, was entered, which requires RCS Operational Leakage to be reduced to within limits in four (4) hours or less. Subsequently, on June 27, 2024, at 0302 hours0.0035 days <br />0.0839 hours <br />4.993386e-4 weeks <br />1.14911e-4 months <br />, TS 3.4.13, Condition C, was entered when the required action of Condition B, could not be met. Condition C requires Unit 2 to be shutdown to MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

At 0159 hours0.00184 days <br />0.0442 hours <br />2.628968e-4 weeks <br />6.04995e-5 months <br />, Operators commenced a shutdown of Unit 2 in accordance with the Power Reduction Procedure due to the identified RCS leak. At 0803 hours0.00929 days <br />0.223 hours <br />0.00133 weeks <br />3.055415e-4 months <br />, Unit 2 was manually tripped from 17% power, in accordance with normal operating procedures. All required equipment operated as expected following the reactor trip.

Following the manual Unit 2 Reactor Trip, the Unit 2 Turbine Driven Auxiliary Feedwater Pump (TDAFP) automatically started when two steam generator levels reached less than the low-low setpoint, The completion of the plant shutdown required by TS is reportable as a Licensee Event Report (LER) in accordance with 1 0CFR 50. 73(a)(2)(i)(A) and the Unit 2 TDAFP Auto Start is reportable as an LER in accordance with 1 0CFR 50. 73(a)(2)(iv)

(A).

COMPONENT 2-QRV-251, eves CHARGING PUMPS DISCHARGE FLOW CONTROL VALVE with Chesterton 5800 packing.

CAUSE OF THE EVENT The direct cause of the leak was determined to be a packing failure, within 2-QRV-251, that resulted in a leak rate of approximately 11.8 gpm. An Apparant Cause Evaluation (ACE) is in progress at the time of the writing of this LER. If the ACE reveals further insights or causes different than described in this LER, a supplement will be provided.

CORRECTIVE ACTIONS 2-QRV-251 was repacked with a replacement Chesterton 5800 packing set and returned to service.

ASSESSMENT OF SAFETY CONSEQUENCES NUCLEAR SAFETY

2. DOCKET NUMBER

3. LER NUMBER I

00316 NUMBER NO.

I YEAR SEQUENTIAL REV

~-I 003 1-0 The approximately 11.8 gpm leak rate from 2-QRV-251 was significantly less than the makeup capacity of the CVCS Charging Pump and there was no actual or potential nuclear safety hazard resulting from the 2-QRV-251 packing failure.

INDUSTRIAL SAFETY There was no actual or potential industrial safety hazard resulting from the 2-QRV-251 packing failure.

RADIOLOGICAL SAFETY There was no actual or potential radiological safety hazard resulting from the 2-QRV-251 packing failure. This event was of minimal significance to the health and safety of the public.

PROBABILISTIC RISK ASSESSMENT A Probabilistic Risk Assessment risk evaluation was performed to determine the safety significance of the leak and ensuing shutdown. The automatic start of the Unit 2 TDAFP did not adversely affect the shutdown and was not factored into the evaluation.

The safety significance can be estimated by calculating the Conditional Core Damage Probability (CCDP) and the Conditional Large Early Release Probability (CLE RP) of the transient initiating event. A comparison of the calculated CCDP and CLERP estimates to regulatory guidance resulted in the conclusion that this event was of very low safety significance.

PREVIOUS SIMILAR EVENTS A review of LERs for the past five years found one similar event. On May 1, 2020, at 1059 hours0.0123 days <br />0.294 hours <br />0.00175 weeks <br />4.029495e-4 months <br />, a Unit 2 shutdown, due to exceeding TS 3.4.13 RCS Operational Leakage limits, was completed and reported under LER 316/2020-002-00. The cause of that leak was determined to be a bellows failure within 2-NRV-163, Reactor Coolant Loop #3 to Pressurizer Spray Control Valve, that resulted in a failure of the 0.5 inch welded telltale line for 2-NRV-163. This event is similar in that both events involved RCS Operational Leakage limits being exceeded. The event was different in that the leak on 2-QRV-251 was due to the packing failure. Page 3

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