ML14356A571

Supplement to Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01

ML14356A571
Person / Time
Site:	Diablo Canyon
Issue date:	12/22/2014
From:	Allen B S Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001, DCL-14-118
Download: ML14356A571 (4)

Text

Pac i f i c Gas and E l ectr i c Company December 22, 2014 PG&E Letter DCL-14-118 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal:

691.4888 Fax: 805.545.6445 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 10 CFR 50.54(f) Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Supplement to Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01

Reference:

1. PG&E Letter DCL-14-009, "Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01 ,"dated February 3, 2014 (ML 14034A415)

Dear Commissioners and Staff: In Reference 1, Pacific Gas and Electric Company (PG&E) committed to submit a supplement identifying any changes to the actions taken to address open phase conditions, and provide details of any additional actions needed including proposed design changes and their planned schedule for completion.

The supplement is provided in the Enclosure to this letter. This letter satisfies the commitment specified in Reference

1. PG&E is making a regulatory commitment (as defined by NEI 99-04) in this letter. The commitment is identified in the Enclosure to this letter. If you have any questions, or require additional information, please contact Interim Manager of Regulatory Services, Mr. Philippe Soenen at (805) 545-6984.

Sincerely, Barry S. Allen A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• Wolf Creek Document Control Desk December 22, 2014 Page 2 RNTT/4231/50601137 Enclosure cc: Diablo Distribution

• cc/enc: Marc L. Dapas, NRC Region IV Administrator PG&E Letter DCL-14-118 Thomas R. Hipschman, NRC Senior Resident Inspector Siva P. Lingam, NRC Senior Project Manager Gonzalo L. Perez, California Department of Public Health A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• Wolf Creek Enclosure PG&E Letter DCL-14-118 Supplement to Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01 In Pacific Gas and Electric (PG&E) Letter DCL-14-009, "Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01," dated February 3, 2014, PG&E made the following regulatory commitment: "Based on the results of the analyses being performed in 2014 for Diablo Canyon, PG&E will submit a supplement to the NRC by December 31, 2014. The supplement will identify any changes to current . actions taken to address OPCs, and will provide details of any additional actions needed including proposed design changes and their planned schedule for completion." This letter submits the following details that are associated with the commitment:

Changes to the actions: PG&E has not made changes to the actions discussed in PG&E Letter DCL-14-009.

The current daily visual inspections and operations annunciator response procedures remain reasonable and adequate mitigation strategies to address the OPC in the interim period prior to implementing design changes that are discussed below. Design Changes: Based on modeling and sensitivity studies which were completed in September 2014, PG&E will develop the following design changes:

• PG&E plans to install the Electric Power Research Institute (EPRI) Open Phase Detection system, on the high voltage side of both the 230/12 kV SUT (start-up transformers) and the 500/25 kV GSU (generator step-up transformers), at the solidly grounded neutral point of the Y connected windings.

o The systems will be Non-C.Iass 1 E. o These systems will be installed in the "alarm only" monitoring mode initially, to verify the dependability of the system settings (i.e., the system appropriately detects and does not spuriously actuate).

o After an "alarm only" monitoring period, the tripping functions will be enabled, as described below in the "planned schedule" section. 1 Enclosure PG&E Letter DCL-14-118 These design changes will meet the NEI initiative goals as follows: 1. An open phase condition should not prevent functioning of safety-related structures, systems, and components.

An open phase condition is defined as an open phase, with or without a ground, which is located on the high voltage side of a transformer connecting a General Design Criterion (GDC) 17, 1971 offsite power circuit to the transmission system. This could also be two open phases in this same location with or without grounds. 2. An open phase condition should be detected and alarmed in the control room. Planned Schedule:

Although it was PG&E's intention to meet the milestones of the Industry OPC Initiative, the current status of PG&E's efforts to implement the Open Phase Detection system do not support the Industry OPC Initiative schedule.

• specifically, PG&E will not complete the design, installation and *testing of hardware/software by the 2016 date for installation and the 2017 date for functionality due to the time required to complete the designs and current planned refueling outage schedules for both Diablo Canyon Power Plant Units 1 and 2. PG&E is making the following regulatory commitment:

PG&E is committed to the following schedule for implementation of the Open Phase Detection system:

• Unit 1 installations will be completed during the Unit 1 twentieth refueling outage (1 R20) which is forecasted to be completed in June 2017. Trip functions will be enabled by June 30, 2018.

• Unit 2 installations will be completed during the Unit 2 twentieth refueling outage (2R20) which is forecasted to be completed in April 2018. Trip functions will be enabled by December 31, 2018 (i.e., within nine months after the end of 2R20, crediting the operational experience from the Unit 1 installation).

The planned schedule for implementation of the Open Phase Detection system may be further revised to accommodate outage schedules, software and hardware availability, manufacturer's delivery capability, licensing delays, etc. Any further deviation from this planned schedule will be documented through the pending deviation/exemption process addressed in the NEI OPC Guidance Document.

2 Pac i f i c Gas and E l ectr i c Company December 22, 2014 PG&E Letter DCL-14-118 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal:

691.4888 Fax: 805.545.6445 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 10 CFR 50.54(f) Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Supplement to Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01

Reference:

1. PG&E Letter DCL-14-009, "Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01 ,"dated February 3, 2014 (ML 14034A415)

Dear Commissioners and Staff: In Reference 1, Pacific Gas and Electric Company (PG&E) committed to submit a supplement identifying any changes to the actions taken to address open phase conditions, and provide details of any additional actions needed including proposed design changes and their planned schedule for completion.

The supplement is provided in the Enclosure to this letter. This letter satisfies the commitment specified in Reference

1. PG&E is making a regulatory commitment (as defined by NEI 99-04) in this letter. The commitment is identified in the Enclosure to this letter. If you have any questions, or require additional information, please contact Interim Manager of Regulatory Services, Mr. Philippe Soenen at (805) 545-6984.

Sincerely, Barry S. Allen A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• Wolf Creek Document Control Desk December 22, 2014 Page 2 RNTT/4231/50601137 Enclosure cc: Diablo Distribution

• cc/enc: Marc L. Dapas, NRC Region IV Administrator PG&E Letter DCL-14-118 Thomas R. Hipschman, NRC Senior Resident Inspector Siva P. Lingam, NRC Senior Project Manager Gonzalo L. Perez, California Department of Public Health A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• Wolf Creek Enclosure PG&E Letter DCL-14-118 Supplement to Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01 In Pacific Gas and Electric (PG&E) Letter DCL-14-009, "Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01," dated February 3, 2014, PG&E made the following regulatory commitment: "Based on the results of the analyses being performed in 2014 for Diablo Canyon, PG&E will submit a supplement to the NRC by December 31, 2014. The supplement will identify any changes to current . actions taken to address OPCs, and will provide details of any additional actions needed including proposed design changes and their planned schedule for completion." This letter submits the following details that are associated with the commitment:

Changes to the actions: PG&E has not made changes to the actions discussed in PG&E Letter DCL-14-009.

The current daily visual inspections and operations annunciator response procedures remain reasonable and adequate mitigation strategies to address the OPC in the interim period prior to implementing design changes that are discussed below. Design Changes: Based on modeling and sensitivity studies which were completed in September 2014, PG&E will develop the following design changes:

• PG&E plans to install the Electric Power Research Institute (EPRI) Open Phase Detection system, on the high voltage side of both the 230/12 kV SUT (start-up transformers) and the 500/25 kV GSU (generator step-up transformers), at the solidly grounded neutral point of the Y connected windings.

o The systems will be Non-C.Iass 1 E. o These systems will be installed in the "alarm only" monitoring mode initially, to verify the dependability of the system settings (i.e., the system appropriately detects and does not spuriously actuate).

o After an "alarm only" monitoring period, the tripping functions will be enabled, as described below in the "planned schedule" section. 1 Enclosure PG&E Letter DCL-14-118 These design changes will meet the NEI initiative goals as follows: 1. An open phase condition should not prevent functioning of safety-related structures, systems, and components.

An open phase condition is defined as an open phase, with or without a ground, which is located on the high voltage side of a transformer connecting a General Design Criterion (GDC) 17, 1971 offsite power circuit to the transmission system. This could also be two open phases in this same location with or without grounds. 2. An open phase condition should be detected and alarmed in the control room. Planned Schedule:

Although it was PG&E's intention to meet the milestones of the Industry OPC Initiative, the current status of PG&E's efforts to implement the Open Phase Detection system do not support the Industry OPC Initiative schedule.

• specifically, PG&E will not complete the design, installation and *testing of hardware/software by the 2016 date for installation and the 2017 date for functionality due to the time required to complete the designs and current planned refueling outage schedules for both Diablo Canyon Power Plant Units 1 and 2. PG&E is making the following regulatory commitment:

PG&E is committed to the following schedule for implementation of the Open Phase Detection system:

• Unit 1 installations will be completed during the Unit 1 twentieth refueling outage (1 R20) which is forecasted to be completed in June 2017. Trip functions will be enabled by June 30, 2018.

• Unit 2 installations will be completed during the Unit 2 twentieth refueling outage (2R20) which is forecasted to be completed in April 2018. Trip functions will be enabled by December 31, 2018 (i.e., within nine months after the end of 2R20, crediting the operational experience from the Unit 1 installation).

The planned schedule for implementation of the Open Phase Detection system may be further revised to accommodate outage schedules, software and hardware availability, manufacturer's delivery capability, licensing delays, etc. Any further deviation from this planned schedule will be documented through the pending deviation/exemption process addressed in the NEI OPC Guidance Document.

2