CP-201900126, Special Report 2-SR-19-001-00, Inoperable Post Accident Monitoring Instrumentation Report.

Special Report 2-SR-19-001-00, Inoperable Post Accident Monitoring Instrumentation Report.

ML19067A075
Person / Time
Site:	Comanche Peak
Issue date:	02/25/2019
From:	Thomas McCool Vistra Operations Company
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-201900126, TXX-19027 2-SR-19-001-00
Download: ML19067A075 (5)

Text

ENERGY 4-rxu 9'* energy I m Luminant Thomas P. McCool Site Vice President Luminant P.O. Box 1002 6322 North FM 5,6 Glen Rose, TX 76043 o 254.897 .6042 CP-201900126 TXX-19027 U.S. Nuclear Regulatory Commission Ref 10 CFR 50.36 ATIN: Document Control Desk Washington, DC 20555-0001 2/25/2019

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-446 SPECIAL REPORT 2-SR-19-001-00 INOPERABLE POST ACCIDENT MONITORING INSTRUMENTATION REPORT

Dear Sir or Madam:

Enclosed is a 14-day Special Report titled "COMANCHE PEAK NUCLEAR POWER PLANT - UNIT 2, SPECIAL REPORT 2-SR-19-001-00, INOPERABLE POST ACCIDENT MONITORING INSTRUMENTATION" submitted in accordance with CPNPP Technical Specification 5.6.8, PAM Report.

This Jetter contains no new regulatory commitments.

If you have any questions regarding this submittal, please contact Garry Struble at (254) 897-6628 or garry.struble@luminant.com.

6555 SIERRA DRIVE IRVING, TEXAS 75039 0214-812-4600 VISTRAENERGY.COM

TXX-19027 Page 2 of 2 Sincerely,

' ~

Thomas P. McCool

Enclosure:

COMANCHE PEAK NUCLEAR POWER PLANT - UNIT 2, SPECIAL REPORT 2-SR-19-001-00, INOPERABLE POST ACCIDENT MONITORING INSTRUMENTATION c- Scott Morris, Region IV (CL&E)

Margaret O'Banion, NRR (CL&E}

Resident Inspectors, Comanche Peak (CL&E}

Enclosure to TXX-19027 Page 1 of 3 VISTRA OPERATIONS COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT - UNIT 2 SPECIAL REPORT 2-SR-19-001-00 INOPERABLE POST ACCIDENT MONITORING INSTRUMENTATION 1.0 Report Requirements This special report is submitted in accordance with Section 5.6.8, PAM Report of the CPNPP Technical Specifications (TS). Specifically, TS Section 3.3.3, Post Accident Monitoring (PAM) Instrumentation requires the PAM Instrumentation to be OPERABLE in MODES 1, 2, and 3 for each function in Table 3.3.3-1. With one or more functions with one required channel inoperable, Condition A.1 requires the inoperable channel be restored to OPERABLE status within 30 days.

If the Required Action and associated Completion Time of Condition A is not met then, Required Action B.1 requires initiating actions immediately in accordance with Specification 5.6.8.

When a report is required by the required actions of LCO 3.3.3, "Post Accident Monitoring (PAM) Instrumentation," a report shall be submitted within the following 14 days. The report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status.

2.0 Event Description The principle function of the Core Exit Thermocouples (GET) at CPNPP is to provide indication of reactor core exit temperature during and after postulated accidents. The GET system is made up of four separate quadrants. At least two Train A and two Train B thermocouples must be OPERABLE in each quadrant with a maximum deviation of <75°F between thermocouples to meet acceptance criteria. Additionally, there must be five OPERABLE CETs per OPERABLE train (at least one GET per quadrant and one additional GET in the center of the core that is different from one of the first four CETs) to meet acceptance criteria.

There are no control functions associated with the Core Exit Thermocouples.

Instrument output can be read on the plant computer.

On January 12, 2019, CPNPP Unit 2 entered MODE 3 following refueling outage 2RF17. Entering MODE 3 caused Technical Specification LCO 3.3.3, Post Accident Monitoring Instrumentation to become applicable. On January 19, 2019, while performing power distribution measurements per procedure NUC-115 unexpected core exit thermocouple response was identified. It was identified that some cables coming from thermocouples were swapped causing the unexpected

Enclosure to TXX-19027 Page 2 of 3 readings. After investigation it was determined that the following CET conditions existed;

1. Quadrant 1, Train A had one known (2-TE-0007) failed CET prior to 2RF17.

Quadrant 1, Train A had five functioning CETs. Quadrant 1, Train B had two CETs affected by the cable swap leaving four functioning CETs.

2. Quadrant 2, Train A had six CETs functioning. Quadrant 2, Train B had one CET (2-TE-0008) failed prior to 2RF17 leaving six functioning CETs. No Quadrant 2 CETs were affected by the cable swap.

3. Quadrant 3, Train A had three failed CETs prior to 2RF17 (2-TE-0020, 0048, 0038). The remaining three Train A CETs were unaffected by the cable swap.

Quadrant 3, Train B had one failed CET prior to 2RF17 (2-TE-0050). Four Train B CETs were affected by the cable swap leaving one functioning CET (2-TE-0017) in Quadrant 3, Train B.

4. Quadrant 4, Train A had two failed CETs (2-TE-0043,0047) prior to 2RF17.

Quadrant 4, Train A had five CETs unaffected by the cable swap. Quadrant 4, Train B had two failed CETs prior to 2RF17 (2-TE-0014, 0021). Quadrant 4, Train B had the six remaining CETs affected by the cable swap. Quadrant 4, Train B had no functioning CETs.

Technical Specification LCO 3.3.3, PAM Instrumentation, Condition A for Quadrant 3 and Quadrant 4 for one Channel with less than 2 operable CETs was entered under active LCOAR A2-2019-0035.

3.0 Required Information 3.1 Preplanned Alternate Methods of Monitoring As described above, the inoperability was not known until January 19, 2019, while performing power distribution measurements per procedure NUC-115. At that time there was only one channel OPERABLE in Quadrant 3 and Quadrant 4 requiring entry into LCO 3.3.3, Condition A.

Therefore, a preplanned alternate method of monitoring is not required for this report.

These thermocouples are listed as Equipment Important to Emergency Response (EITER), Category B. As such, plant procedure STl-433.01, Maintaining Equipment Important to Emergency Preparedness indicates that all CET indication would have to be inoperable to impact emergency response declaration. There were still enough OPERABLE CETs that

Enclosure to TXX-19027 Page 3 of 3 appropriate emergency declarations could have been made with the remaining CETs.

3.2 Cause of the lnoperability Two cables between the CET and the Plant Computer were swapped such that it caused the inoperability of Quadrant 3 and Quadrant 4, Train B CET for PAM Instrumentation.

3.3 Plans and Schedule for Restoring the Instrumentation Channels of the Function to OPERABLE Status The two swapped cables were re-landed to their proper locations and PAM Instrumentation was restored to OPERABLE status on February 14, 2019.

Both PAM CET channels (Train A and Train B) for Quadrant 1, Quadrant 2, Quadrant 3, and Quadrant 4 are OPERABLE.