RBG-47884, Special Report Due to High Pressure Core Spray Actuation

Special Report Due to High Pressure Core Spray Actuation

ML18197A363
Person / Time
Site:	River Bend
Issue date:	07/16/2018
From:	Schenk T Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RBG-47884
Download: ML18197A363 (5)

Text

• --- Entergx Entergy Operations, Inc.

River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 Tel 225-381 -4374 Timothy Schenk Regulatory Assurance Manager RBG-47884 July 16, 2018 Attn: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville , MD 20852-2738

Subject:

Special Report due to High Pressure Core Spray Actuation River Bend Station , Unit 1 Docket No. 50-458 License No. NPF-47

Dear Sir or Madam :

In accordance with River Bend Station Technical Requirements Manual , attached is a Special Report containing the total accumulated High Pressure Core Spray (HPCS) actuation cycles to date and HPCS nozzle usage factor information . This document contains no commitments . If you have any questions , please contact Mr. Tim Schenk at 225-381-4177.

TAS/twf ATTACHMENT:

1. Special Report due to High Pressure Core Spray Actuation cc: (with Attachment)

U.S. Nuclear Regulatory Commission Attn : Ms. Lisa M. Regner, Project Manager 09-D-14 One White Flint North 11555 Rockville Pike Rockville , MD 20852

RBG-47884 Page 2 of 2 U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Blvd.

Arlington , TX 76011-4511 NRC Senior Resident Inspector Attn : Mr. Jeff Sowa 5485 U.S. Highway 61 , Suite 1 St. Francisville , LA 70775 Public Utility Commission of Texas Attn : PUC Filing Clerk 1701 N. Congress Avenue P. O. Box 13326 Austin , TX 78711-3326 RBF1-18-0144

RBG-47884 Page 1 of 3 I

ATIACHMENT 1 RBG -47884 SPECIAL REPORT DUE TO HIGH PRESSURE CORE SPRAY ACTUATION

RBG-47884 Page 2 of 3 SPECIAL REPORT DUE TO HIGH PRESSURE CORE SPRAY ACTUATION ABSTRACT At 15:31 CST on April 26, 2018, I&C technicians were restoring Reactor Vessel Water Level Transmitter B21-LTN081C to service with the Reactor operating in Mode 1 at 100% power. During this transmitter restoration, the station experienced an invalid initiation of High Pressure Core Spray (HPCS) with injection into the reactor vessel. The HPCS Diesel Generator also started per design, but did not connect to the switchgear because there was no bus under voltage. Operations terminated the injection after approximately 40 seconds in accordance with Alarm Response Procedures. The Feedwater Level Control System responded per design, and maintained nominal Reactor water levels . This condition was previously reported pursuant to 10CFR50.72 and 10CFR50.73. This report is being submitted in accordance with the River Bend Station Technical Requirements Manual.

BACKGROUND River Bend Station (RBS) Technical Requirements Manual (TRM) states "In the event an Emergency Core Cooling System is actuated and injects water into the Reactor Coolant System, a Special Report shall be prepared and submitted to the Commission within 90 days describing the circumstances of the actuation and the total accumulated actuation cycles to date. The c~rrent value of the usage factor for each affected safety injection nozzle shall be provided in this Special Report whenever its value exceeds 0.70 ."

High Pressure Core Spray (HPCS) is designed to limit the release of radioactive materials to the environment following a loss of coolant accident (LOCA) by injecting water into the Reactor Coolant System (RCS) . HPCS is also designed to automatically initiate when level 2 is reached in the Reactor Pressure Vessel (RPV) . The RPV level 2 signal is generated by Reactor Water Level Transmitters in the Nuclear Boiler Instrumentation System . The '(' reference leg of the Nuclear Boiler Instrumentation System contains two HPCS level 2 Water Level Transmitters .

EVENT DESCRIPTION On April 26, 2018 after replacing Reactor Water Level Transmitter B21-LTN081C, an invalid initiation occurred resulting in the actuation of HPCS.

With the Reactor operating in Mode 1 at 100% power, I&C technicians were sent to the field to replace the transmitter which is in the '(' reference leg. In the process of returning the transmitter to service, air introduced during the installation caused a perturbation in the '(' reference leg. With two HPCS level transmitter on the '(' reference leg affected by this perturbation, HPCS initiated and the Division III Diesel Generator started as designed . Operators responded to the initiation by taking the appropriate actions per alarm response procedure. The HPCS system was placed in standby, the plant was stabilized

RBG-47884 Page 3 of 3 and field activities stopped . All plant parameters responded as would be expected for an inadvertent actuation of the HPCS System. A troubleshooting procedure was developed and utilized to restore '('

reference leg following the event.

USAGE FACTOR DISCUSION The usage factor for the HPCS injection nozzle has been conservatively calculated to be 0.31 after 43 actuation cycles by Structural Integrity (SI) Associates calculation FP-RBS-302 completed November 21, 2016 . This event represents the 31st actuation cycle to date for the HPCS system and is therefore bounded by the SI calculation . In conclusion, the usage factor for the HPCS injection nozzle is calculated to be less than 0.31.