SBK-L-14017, Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

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Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System
ML14035A217
Person / Time
Site: Seabrook NextEra Energy icon.png
Issue date: 01/29/2014
From: Walsh K
NextEra Energy Seabrook
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001, SBK-L-14017
Download: ML14035A217 (5)
v • d • e


Text

4f NEXTera EN ERG January 29, 2014 10 CFR 50.54(f)

Docket No. 50-443 SBK-L-14017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 - 0001 Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

References:

1. NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated July 27, 2012. (Accession No. ML12074A115)
2. NextEra Energy Seabrook, LLC letter SBK-L-12220, Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated October 22, 1012 (Accession No. ML12299A467)
3. NRC letter, Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability. in Electric Power System," dated December 20, 2013. (Accession No. ML13351A314)

In Reference 1, the NRC requested information about each facility's electric power system designs in light of operating experience involving the loss of one of the three phases of the offsite power circuit (single-phase open circuit condition) at Byron Station, Unit 2.

In Reference 2, NextEra Energy Seabrook, LLC (NextEra) provided its response to NRC Bulletin 2012-0 1.

In Reference 3, the NRC requested additional information regarding NextEra's response to NRC Bulletin 2012-0 1.

The enclosure to this letter contains NextEra's response to the request for additional information.

There are no regulatory commitments contained in this letter.

NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

U.S. Nuclear Regulatory Commission SBK-L-14017/Page 2 Should you have any questions regarding this letter, please contact Mr. Michael Ossing, Licensing Manager, at (603) 773-7512.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on January Z,', 2014.

Sincerely, NJA ,,- -

Kevin swas Site Vice President NextEra Energy Seabrook, LLC Enclosure cc: NRC Region I Administrator J.G. Lamb, NRC Project Manager NRC Senior Resident Inspector

Enclosure to SBK-L-14017 Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System On July 27, 2012., the U.S. Nuclear Regulatory Commission (NRC) issued Bulletin 2012-01, "Design Vulnerability in Electric Power System" (Agencywide Documents Access and ManagementSystem Accession No. ML12074A115), to all holders of operatinglicenses and combined licensesfor nuclearpower reactors. In addition, Watts Bar Nuclear Plant, Unit 2, is addressingthe issues identified in the bulletin as part of the licensingprocess. Bulletin 2012-01 requested information about eachfacility's electricpower system designs, in light of recent operatingexperience involving the loss of one of the three phases of the offsite power circuit (single-phaseopen circuit condition) at Byron Station, Unit 2.

On October 22, 2012 Seabrook Station provided its response to Bulletin 2012-01 (Reference 1).

The Nuclear Energy Institute (NEI)organizedindustry representativesto outline the industry strategy,goal, criteriaand timeline for nuclear stations to detect andprotectfrom an adverse open phase condition and develop an Open Phase Condition Initiative document. The NEI Open Phase Condition Initiative document was submitted to the NRC on October 9, 2013 (Reference 2).

In orderfor the NRC staff to complete its review of responses to the bulletin, the following additionalinformation is requested.

RAI I Provide a summary of all interim corrective actions that have been taken since the January30, 2012, event at Byron Station, Unit 2, to ensure thatplant operators can promptly diagnose and respond to open phase conditions on the offsite power circuitsfor Class-i E vital buses until permanent corrective actions are completed.

NextEra Response Lessons learned from the events at Byron station were reviewed and various interim corrective actions were evaluated for safety and efficiency at Seabrook Station. Based on the plant's offsite power system configuration, electrical design details, and lessons learned, the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):

  • Once every shift, current on all three phases of each offsite transmission line is checked to diagnose an open phase condition on the offsite transmission lines.

1 of 2

  • Once every shift, the transformer yard rounds are performed which include general and detailed inspections of the transformers to ensure parameters are within expected limits.

" Weekly walk-downs are being performed of the switchyard and air termination yard to identify any abnormal conditions on any equipment.

  • The Byron Event and required procedure changes were covered in the operator training to help plant operators understand the event and diagnose and respond to an OPC.

0 Switchyard Operations Procedure was verified to ensure three phase currents are checked prior to and following 345kV breaker switching operations as a backup to local visual verification of equipment position.

  • Bi-annual thermographic inspections of air termination yard equipment are being completed as part of routine inspections. In addition the Switchyard Operations Procedure has been updated to require the thermographic inspection after returning a transmission line to service.
  • Video Alarm Response Operating Procedures and Main Control Board Hardwire Annunciator Alarm Response Procedures were revised to include recognition of equipment problems caused by OPC.
  • Operations procedures were revised to include recognition of equipment problems caused by OPC.

RAI 2

Provide a status and schedulefor completion ofplant design changes and modifications to resolve issues with an open phase of electricpower.

Status Based on Seabrook Station's unique design and configuration of the 345kV switchyard and station buses, switchyard reliability improvements and proper operating and maintenance practices, a single credible failure that could cause an undetected open phase condition is not a credible event.

Schedule Since a single credible failure that could cause an undetected open phase condition is not a credible event at Seabrook Station, no plant design changes and modifications are being pursued to resolve issues with an open phase of electric power.

References

1. NextEra Energy Seabrook, LLC letter to NRC, Seabrook Station Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated October 22, 2012 (ML12299A467)
2. Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013 (ML13333A147) 2 of 2

Text

4f NEXTera EN ERG January 29, 2014 10 CFR 50.54(f)

Docket No. 50-443 SBK-L-14017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 - 0001 Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

References:

1. NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated July 27, 2012. (Accession No. ML12074A115)
2. NextEra Energy Seabrook, LLC letter SBK-L-12220, Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated October 22, 1012 (Accession No. ML12299A467)
3. NRC letter, Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability. in Electric Power System," dated December 20, 2013. (Accession No. ML13351A314)

In Reference 1, the NRC requested information about each facility's electric power system designs in light of operating experience involving the loss of one of the three phases of the offsite power circuit (single-phase open circuit condition) at Byron Station, Unit 2.

In Reference 2, NextEra Energy Seabrook, LLC (NextEra) provided its response to NRC Bulletin 2012-0 1.

In Reference 3, the NRC requested additional information regarding NextEra's response to NRC Bulletin 2012-0 1.

The enclosure to this letter contains NextEra's response to the request for additional information.

There are no regulatory commitments contained in this letter.

NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

U.S. Nuclear Regulatory Commission SBK-L-14017/Page 2 Should you have any questions regarding this letter, please contact Mr. Michael Ossing, Licensing Manager, at (603) 773-7512.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on January Z,', 2014.

Sincerely, NJA ,,- -

Kevin swas Site Vice President NextEra Energy Seabrook, LLC Enclosure cc: NRC Region I Administrator J.G. Lamb, NRC Project Manager NRC Senior Resident Inspector

Enclosure to SBK-L-14017 Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

Seabrook Station Response to Request for Additional Information Regarding Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System On July 27, 2012., the U.S. Nuclear Regulatory Commission (NRC) issued Bulletin 2012-01, "Design Vulnerability in Electric Power System" (Agencywide Documents Access and ManagementSystem Accession No. ML12074A115), to all holders of operatinglicenses and combined licensesfor nuclearpower reactors. In addition, Watts Bar Nuclear Plant, Unit 2, is addressingthe issues identified in the bulletin as part of the licensingprocess. Bulletin 2012-01 requested information about eachfacility's electricpower system designs, in light of recent operatingexperience involving the loss of one of the three phases of the offsite power circuit (single-phaseopen circuit condition) at Byron Station, Unit 2.

On October 22, 2012 Seabrook Station provided its response to Bulletin 2012-01 (Reference 1).

The Nuclear Energy Institute (NEI)organizedindustry representativesto outline the industry strategy,goal, criteriaand timeline for nuclear stations to detect andprotectfrom an adverse open phase condition and develop an Open Phase Condition Initiative document. The NEI Open Phase Condition Initiative document was submitted to the NRC on October 9, 2013 (Reference 2).

In orderfor the NRC staff to complete its review of responses to the bulletin, the following additionalinformation is requested.

RAI I Provide a summary of all interim corrective actions that have been taken since the January30, 2012, event at Byron Station, Unit 2, to ensure thatplant operators can promptly diagnose and respond to open phase conditions on the offsite power circuitsfor Class-i E vital buses until permanent corrective actions are completed.

NextEra Response Lessons learned from the events at Byron station were reviewed and various interim corrective actions were evaluated for safety and efficiency at Seabrook Station. Based on the plant's offsite power system configuration, electrical design details, and lessons learned, the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):

  • Once every shift, current on all three phases of each offsite transmission line is checked to diagnose an open phase condition on the offsite transmission lines.

1 of 2

  • Once every shift, the transformer yard rounds are performed which include general and detailed inspections of the transformers to ensure parameters are within expected limits.

" Weekly walk-downs are being performed of the switchyard and air termination yard to identify any abnormal conditions on any equipment.

  • The Byron Event and required procedure changes were covered in the operator training to help plant operators understand the event and diagnose and respond to an OPC.

0 Switchyard Operations Procedure was verified to ensure three phase currents are checked prior to and following 345kV breaker switching operations as a backup to local visual verification of equipment position.

  • Bi-annual thermographic inspections of air termination yard equipment are being completed as part of routine inspections. In addition the Switchyard Operations Procedure has been updated to require the thermographic inspection after returning a transmission line to service.
  • Video Alarm Response Operating Procedures and Main Control Board Hardwire Annunciator Alarm Response Procedures were revised to include recognition of equipment problems caused by OPC.
  • Operations procedures were revised to include recognition of equipment problems caused by OPC.

RAI 2

Provide a status and schedulefor completion ofplant design changes and modifications to resolve issues with an open phase of electricpower.

Status Based on Seabrook Station's unique design and configuration of the 345kV switchyard and station buses, switchyard reliability improvements and proper operating and maintenance practices, a single credible failure that could cause an undetected open phase condition is not a credible event.

Schedule Since a single credible failure that could cause an undetected open phase condition is not a credible event at Seabrook Station, no plant design changes and modifications are being pursued to resolve issues with an open phase of electric power.

References

1. NextEra Energy Seabrook, LLC letter to NRC, Seabrook Station Response to NRC Bulletin 2012-01, Design Vulnerability in Electric Power System, dated October 22, 2012 (ML12299A467)
2. Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013 (ML13333A147) 2 of 2
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