ML14043A117

South Texas Project, Units 1 and 2, Response to Request for Additional Information Regarding Response to Bulletin 2012-01, Design Vulnerability in Electrical Power System.

ML14043A117
Person / Time
Site:	South Texas
Issue date:	01/30/2014
From:	Powell G T South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001, NOC-AE- 14003077, STI: 33814165
Download: ML14043A117 (5)

Text

Nuclear Operating Company South Texas Pro/cd Ekctric Generating Station P.. Box 289 Wadswortf Teas 77483 -vv-- --January 30, 2014 NOC-AE- 14003077 1 OCFR50.4 STI: 33814165 U.S. Nuclear Regulatory Commission Attention:

Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 STPNOC Response to Request for Additional Information regarding Response to Bulletin 2012-01, "Design Vulnerability in Electrical Power System"

References:

1. Letter from NRC to All Power Reactor Licensees, NRC Bulletin 2012-01: Design Vulnerability in Electrical Power System, Dated July 27, 2012 (ML12074A115) (OMB Control No.: 3150-0012).

2. Letter from G.T. Powell, STPNOC (NOC-AE-12002917), to NRC Document Control Desk, "Response to NRC Bulletin 2012-01: Design Vulnerability in Electrical Power System, Dated October 25, 2012 (ML12313A015)

3. Letter from NRC to All Power Reactor Licensees, (Request for Additional Information Regarding Response to Bulletin 2012-01, " Design Vulnerability in Electrical Power System"), Dated December 20, 2013 (ML13351A314)

On July 27, 2012, the U.S. Nuclear Regulatory Commission (NRC) staff issued the Bulletin 2012-01, "Design Vulnerability in Electrical Power System" (Reference

1) to all power reactor licensees and holders of combined licenses for nuclear power reactors.

The Bulletin required that each licensee provide a response to the Required Action within 90 days of the date of the Bulletin.

STPNOC submitted the response to the NRC on October 25, 2012 (Reference 2).By letter dated December 20, 2013 (Reference 3), the NRC requested additional information (RAI) from licensees to verify that they have completed interim corrective actions and compensatory measures and to determine the status of each licensee's long term corrective actions. The RAI requires that each licensee provide a response by February 3, 2014. The enclosure to this letter provides the required response to the RAI.There are no commitments in this letter. 'it lie NOC-AE-14003077 Page 2 of 3 If there are any questions regarding this letter, please contact Hung Le at (361) 972-7932 or me at (361) 972-7566.I declare under penalty of perjury that the foregoing is true and correct.Executed on Tc-A,,.,w4 go. 20i,4 G.T. Powell Site Vice President hcl

Enclosure:

Response to Request for Additional Information NOC-AE-14003077 Page 3 of 3 cc: (paper copy)(electronic copy)Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (MS 8 B1)11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 Jim Collins City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP Balwant K. Singal U. S. Nuclear Regulatory Commission John Ragan Chris O'Hara Jim von Suskil NRG South Texas LP Kevin Polio Richard Pena L. D. Blaylock City Public Service Peter Nemeth Crain Caton & James, P.C.C. Mele City of Austin Richard A. Ratliff Texas Department of State Health Services Robert Free Texas Department of State Health Services Enclosure NOC-AE-14003077 Page 1 of 2 Response to Request for Additional Information REQUEST FOR ADDITIONAL INFORMATION FOR 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 Management System Accession No. ML 12074A1 15), to all holders of operating licenses and combined licenses for nuclear power reactors.

In addition, Watts Bar Nuclear Plant, Unit 2, is addressing the issues identified in the bulletin as part of the licensing process.Bulletin 2012-01 requested information about each facility's electric power system designs, in light of recent 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 order for the NRC staff to complete its review of responses to the bulletin, the following additional information is requested:

1. Provide a summary of all interim corrective actions that have been taken since the January 30, 2012, event at Byron Station, Unit 2, to ensure that plant operators can promptly diagnose and respond to open phase conditions on the offsite power circuits for Class-I E vital buses until permanent corrective actions are completed.

2. Provide a status and schedule for completion of plant design changes and modifications to resolve issues with an open phase of electric power." STPNOC Response 1. Summary of All Interim Corrective Actions Lessons learned from the events at Byron station were reviewed and various interim corrective actions evaluated for safety and efficiency at the South Texas Project. Based on the plant's offsite power configuration, electrical design details, and operating experiences, the following actions were taken to ensure plant operators can promptly diagnose and respond to Open Phase Conditions (OPC):* Interim Corrective Actions o Daily switchyard walk-downs by operations staff are on-going to identify OPC vulnerabilities.

Enclosure NOC-AE-14003077 Page 2 of 2 o Operating procedures and training curriculum were reviewed and revised to ensure operators can diagnose and respond to an OPC.o Operating procedures were revised to ensure that whenever bus voltage is checked on Engineered Safety Features (ESF) buses that all three phases of ESF bus voltages are checked.o Transformer yard rounds by operations staff are performed daily and include general and detailed inspections of the transformers.

o Semi-annual infrared inspections of yard equipment are being completed as part of routine inspections.

o Continuing training for the January 30, 2012 Unit 2 Byron station event was provided to all STP licensed operators.

2. Status and Schedule for Completion of Plant Design Changes* Status o The industry is investigating options being researched by several vendors [Power and Control System 2000 (PCS2000), Electrical Power Research Institute (EPRI), Schweitzer, etc.) to detect OPC faults. There is currently no generic, off-the-shelf technology that has been proven to detect all the required open phase fault conditions for all plant and transformer designs.o The industry is fully engaged in the development of the Nuclear Energy Institute (NEI) OPC Guidance Document, as well as development of enhancements to software tools being used to analyze OPC faults.o New OPC technology will be thoroughly evaluated, analyzed, and tested before installation.

The OPC technology design goals are to ensure accurate detection without compromising nuclear safety and increasing plant risk.o Qualitative vulnerability studies of the OPC faults have been completed (Reference 2), and quantitative vulnerability studies are scheduled to start and be completed by the end of this year for South Texas Project Unit 1 and Unit 2[Reference Condition Report (CR) 12-8728-9].

• Schedule o The South Texas Project Unit 1 and Unit 2 plan to follow the generic schedule provided in the Industry OPC Initiative from NEI.O It is our intention to meet the OPC milestones of this schedule; however, deviations may be required to accommodate outage schedules, software and hardware availability, manufacturer's delivery capabilities, licensing delays, etc.o Any deviation from the Industry OPC Initiative schedule will be documented in the STP corrective action program and through the deviation/exemption process addressed in the NEI OPC Guidance Document which is under development.