AEP-NRC-2020-76, Report Per Technical Specification 5.6.6, Inoperability of Unit 1, Post Accident Monitoring, Containment Water Level

Report Per Technical Specification 5.6.6, Inoperability of Unit 1, Post Accident Monitoring, Containment Water Level

ML20332A027
Person / Time
Site:	Cook
Issue date:	11/24/2020
From:	Scarpello M Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP-NRC-2020-76
Download: ML20332A027 (4)

Text

lndlana Michigan Power Cook Nuclear Plant One Cook Place Bndgman, Ml 49106 tnc!Janarruchiganpower com BOUNDLESS ENERGY-November 24, 2020 AEP-NRC-2020-76 10 CFR 50.4 10 CFR 50.36 Docket Nos.: 50-315 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Report per Technical Specification 5.6.6, lnoperability of Unit 1, Post Accident Monitoring, Containment Water Level Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1, is sending this report pursuant to CNP Technical Specification (TS) 3.3.3, "Post Accident Monitoring (PAM) Instrumentation" and TS 5.6.6, "Post Accident Monitoring Report." The enclosure to this letter contains the report regarding the inoperability of a Unit 1 Containment Water Level Monitor. The Train B Lower Containment Water Level Monitor, 1-NLl-320, was declared inoperable on October 15, 2020. This report is being submitted due to 1-NLl-320 being inoperable for greater than 30 days in accordance with TS 3.3.3, which requires entry into TS 5.6.6. The information required by TS 5.6.6, "Post Accident Monitoring Report" is enclosed.

There are no new or revised commitments in this letter. Should you have any questions, please contact me at (269) 466-2649.

Sincerely, Michael K. Scarpello Regulatory Affairs Director DLW/mll

Enclosure:

Donald C Cook, Unit 1 Report per Technical Specification 5.6.6 lnoperability of Post-Accident Monitoring Instrument Containment Water Level

U. S. Nuclear Regulatory Commission AEP-NRC-2020-76 Page 2 R. J. Ancona- MPSC EG_LE :- RM_O/RP_s__ _

J. B. Giessner - NRC Region Ill D. L. Hille - AEP Ft. Wayne, w/o enclosures NRC Resident Inspector R. M. Sistevaris - AEP Ft. Wayne, w/o enclosures S. P. Wall - NRC Washington, D.C.

A. J. Williamson - AEP Ft. Wayne, w/o enclosures

Enclosure 1 to AEP-NRC-2020-76 Donald C Cook, Unit 1 Report per Technical Specification 5.6.6 lnoperability of Post-Accident Monitoring Instrument Containment Water Level Description of Condition On October 15, 2020, following the Donald C. Cook (CNP) Unit 1 Cycle 30 Refueling outage, the Train B containment water level monitor, 1-NLl-320, was declared inoperable. Investigation determined that the suspected cause of the failure of 1-NLl-320 is the signal processor, 1-NLl-320-SGP. Repairing 1-NLl-320-SGP requires the spare electrical assembly to be sent offsite to the vendor for refurbishment. The investigation determined that the repairs can safely be completed online and 1-NLl-320 will be returned to operable status following receipt of the refurbished parts.

Per Technical Specification (TS) LCO 3.3.3, "Post Accident Monitoring (PAM) Instrumentation,"

Condition A, 1-NLl-320 is required to be restored to OPERABLE status within 30 days. TS LCO 3.3.3, Condition B, requires submittal of a report, in accordance with TS 5.6.6 "Post Accident Monitoring Report," within 14 days of exceeding the Condition A Completion Time. The 30-day Completion Time for TS LCO 3.3.3, "Post Accident Monitoring (PAM) Instrumentation," Condition A, was reached on November 14, 2020.

Background

The primary purpose of the PAM instrumentation is to display unit variables that provide information required by the control room operators during accident situations. The Containment Water Level Monitor is a Type A, Category 1 variable provided for determination of ~dverse containment conditions (per Regulatory Guide 1.97, Revision 3, ML003740282). CNP Unit 1 has a Train A and a Train B Containment Water Level channels (1-NLl-321 and 1-NLl-320). Each channel is capable of measuring from 599' 3" elevation to 614' elevation (containment floor level to maximum flood level).

Cause of lnoperability The apparent cause of the failure of 1-NLl-320 is a faulty signal processor, 1-NLl-320-SGP.

Preplanned Alternate Method of Monitoring The Containment Water Level Monitor consists of two redundant trains with 1 channel each. Train A, 1-NLl-321, will remain operable and available while Train. B, 1-NLl-320, is inoperable. Additionally, the following instruments in containment will be used, if necessary, to monitor containment water level while 1-NLl-320 is inoperable:

1-NLl-311 - Lower Containment Sump Train A Level Indicator 1-NLA-310- Lower Containment Sump Train B Level Alarm 1-NLl-301 - Containment Recirculation Sump Level Switch - Train A 1-NLl-300 - Containment Recirculation Sump Level Switch - Train B 1-NLl-331 - Containment Water Level Recirculation Level Switch - Train A 1-NLl-330 - Containment Water Level Recirculation Level Switch - Train B

Enclosure to AEP-NRC-2020-76 Page 2 Plans and Schedule for Restoring Functionality 1-NLl-320 will be returned to operable status, at the next opportunity, following vendor repair of the spare electrical assembly. The vendor is currently challenged with available technicians due to the coronavirus p-a-ntlemic anti expects som_e_ aelays. Following recefpt of the refurt>fshed parts, the necessary installation can be completed online. The station estimates that 1-NLl-320 will be returned to operable status on or about December 17, 2020.