ML23276B455

Technical Specification 5.6.8 Post Accident Monitoring (PAM) Report

ML23276B455
Person / Time
Site:	Wolf Creek
Issue date:	10/03/2023
From:	Bayer R Wolf Creek
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
000154
Download: ML23276B455 (1)

Text

Robert J. Bayer Plant Manager October 3, 2023 000154 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Docket No. 50-482: Technical Specification 5.6.8 - Post Accident Monitoring (PAM) Report Commissioners and Staff:

The Attachment provides the Post Accident Monitoring (PAM) Report for the inoperability of one channel of the Reactor Coolant System (RCS) Cold Leg Temperature (Wide Range) Function for greater than 30 days. Wolf Creek Generating Station (WCGS) Technical Specification (TS) 5.6.8, "PAM Report," requires the submittal of the report within 14 days after entry into Condition B of Limiting Condition for Operation (LCO) 3.3.3, "Post Accident Monitoring (PAM)

Instrumentation." Condition B of TS 3.3.3 was entered on September 22, 2023. This condition was entered due to an RCS cold leg wide range temperature channel (Table 3.3.3-1, Function

3) being inoperable.

This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4015, or Dustin Hamman at (620) 364-4204.

Sincerely, Robert J. Bayer RJB/nwl

Attachment:

Technical Specification 5.6.8 - Post Accident Monitoring (PAM) Report cc: S. S. Lee (NRC), w/a J. D. Monninger (NRC), w/a G. E. Werner (NRC), w/a Senior Resident Inspector (NRC), w/a WC Licensing Correspondence, wo/a - WO 23-000154 P.O. Box 411 l Burlington, KS 66839 l 620-364-8831

Attachment to 000154 Page 1 of 2 Technical Specification 5.6.8 - Post Accident Monitoring (PAM) Report Background Information:

On August 23, 2023, at 1954 Central Standard Time (CST), Technical Specification (TS) 3.3.3, Post Accident Monitoring (PAM) Instrumentation, Condition A was entered when the Reactor Coolant System (RCS) Cold Leg Temperature (Wide Range) Function was determined to be inoperable. TS Table 3.3.3-1, Function 3, RCS Cold Leg Temperature (Wide Range), requires 2 channels to be OPERABLE. Required Action A.1 of TS 3.3.3 requires restoring the required channel to OPERABLE status within 30 days. If the Required Action and associated Completion Time of Condition A are not met, TS 3.3.3 Condition B is entered. On September 22, 2023, the station entered into LCO 3.3.3 Condition B. LCO 3.3.3 Required Action B.1 requires initiation of action in accordance with TS 5.6.8, PAM Report, and requires that a report be submitted within 14 days of entry into Condition B.

The primary purpose of the PAM instrumentation is to display unit variables that provide information required by the control room operators during accident situations. This information provides the necessary support for the operator to take the manual actions for which no automatic control is provided and that are required for safety systems to accomplish their safety functions for Design Basis Accidents (DBAs).

RCS Cold Leg Temperatures (Wide Range) are Type A, Category 1 variables provided for verification of core cooling and long-term surveillance. RCS hot and cold leg temperatures provide input to the core subcooling monitor or may be used to manually determine RCS subcooling margin. RCS subcooling margin will allow termination of safety injection (SI), if still in progress, or reinitiation of SI if it has been stopped. RCS subcooling margin is also used for unit stabilization and cooldown control. In addition, RCS cold leg temperature is used in conjunction with RCS hot leg temperature to verify the unit conditions necessary to establish natural circulation in the RCS.

Each of the four cold legs has one wide range, thermowell-mounted resistance temperature detector (RTD). These are separate from the narrow range RTDs providing input to the Reactor Protection System. The wide range channels provide indication over a range of 0°F to 700°F.

Loops 1 and 2 have hot and cold leg wide range Class 1E temperature indications in the control room.

Preplanned Alternate Methods of Monitoring RCS Parameters:

The loop 2 cold leg wide range temperature indication (BB TI-423B) is functioning at this time and providing valid data. Additional PAM instrumentation that provides for verification of core cooling and long-term surveillance include RCS hot leg temperature (Function 2), RCS Wide Range Pressure (Function 4), reactor vessel indication (Function 5), and core exit temperature (Functions 14, 15, 16, and 17).

Cause of Inoperability:

On August 23, 2023, Control Room operators observed annunciator 056A, RCS SATURATE, and 056B, RCS <50 SUBCOOL, in alarm. ALR 00-056A, RCS Saturate, was performed and found that BB TI-413B, Loop 1 Cold Leg Wide Range Temperature, failed HIGH.

Troubleshooting activities determined the RTD (BB TE-413B) failed. The exact cause of the RTD failure is unknown at this time and will be evaluated upon equipment replacement.

Attachment to 000154 Page 2 of 2 Plans and Schedule for Restoring the Instrumentation Channels of the Function to Operable Status:

Troubleshooting was performed and the RTD was found to be open. As the RCS loop 1 cold leg wide range temperature RTD (BB TE-413B) is installed in a thermowell in the primary piping located behind the secondary shield wall, replacement of the RTD at power cannot be performed due to radiological conditions in this area which prohibit access by plant personnel.

Planning is ongoing to replace the failed RTD in Refueling Outage 26 (Spring 2024).