DCL-19-097, Schedule Extension for Full Implementation of Open Phase Detection System

Schedule Extension for Full Implementation of Open Phase Detection System

ML19343B177
Person / Time
Site:	Diablo Canyon
Issue date:	12/09/2019
From:	Gerfen P Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-19-097
Download: ML19343B177 (2)

Text

Pacific Gas and Electric Company'"

Paula Gerten Diablo Canyon Power Plant Site Vice President Mail code 104/6/605 P.O. Box 56 Avila Beach, CA 93424 805.545.4596 Internal: 691.4596 Fax: 805.545.4234 December 9, 2019 PG&E Letter DCL-19-097 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Schedule Extension for Full Implementation of Open Phase Detection System

References:

1. PG&E Letter DCL-18-036, "Change of Commitment Dates for Full Implementation of Open Phase Detection System," dated May 14, 2018 (ML18134A328)

2. Nuclear Energy Institute Open Phase Condition Initiative, Revision 3, dated June 2019 (transmitted to NRC under NEI letter dated June 6, 2019, Douglas E.

True to Ho Nieh, Jr., re: "Industry Initiative on Open Phase Condition, Revision 3") (ML19163A176)

Dear Commissioners and Staff:

In Reference 1, Pacific Gas and Electric Company (PG&E) informed the NRC of hardware changes to the open phase detection system at Diablo Canyon Power Plant (DCPP), Units 1 and 2. The changes necessitated additional monitoring time before enabling the system's trip functions. In Reference 1, PG&E committed to enable the trip functions for both units by December 31, 2019.

The additional monitoring time has revealed new reliability concerns associated with the open phase detection system. To address the equipment reliability concerns, PG&E has made additional changes, including both hardware and software (detection algorithm) changes. Therefore, PG&E is hereby extending the schedule for enabling the trip functions for DCPP Units 1 and 2 to December 31, 2020.

This schedule change is consistent with the Nuclear Energy lnstitute's (NEl's) Open Phase Condition (OPC) Initiative (Reference 2), which states: "Plants that have not accumulated 24 months of monitoring time by December 31, 2019, may extend the A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-19-097 December 9, 2019 Page 2 monitoring period into 2020 until they reach 24 months." In addition, because 24 months of monitoring time will not have elapsed from the time the hardware and software changes described above were installed through December 31, 2020, PG&E may determine that further monitoring time is warranted. If so, this will be communicated in a future submittal.

The extended monitoring period will not adversely impact the safe operation of DCPP Units 1 and 2 for the same reasons stated in Reference 1.

PG&E is also considering the use of the risk-informed evaluation methodology contained in Reference 2, which is intended to demonstrate that operator manual actions combined with OPC detection and alarm would be sufficient to mitigate the impact of an OPC. If the methodology is determined to be viable and warranted for DCPP, PG&E will inform the NRC accordingly.

This schedule change is processed in accordance with the NEI guidance for deviations to the OPC Initiative and NEI 99-04, "Guidelines for Managing NRC Commitment Changes."

If you have any questions or require additional information regarding this schedule extension, please contact Mr. Hossein Hamzehee, DCPP Regulatory Services Manager, at 805-545-4720.

s72y, Pau~~~

Site Vice President jmsp/4927 cc: Scott A. Morris, NRC Region IV Administrator Christopher W. Newport, NRC Senior Resident Inspector Balwant K. Singal, NRC Senior Project Manager Diablo Canyon Distribution A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek