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 CompanySouth Texas Pro/cd Ekctric Generating Station P.. Box 289 Wadswortf Teas 77483 -vv-- --January 30, 2014NOC-AE- 140030771 OCFR50.4STI: 33814165U.S. Nuclear Regulatory Commission Attention:

Document Control DeskWashington, DC 20555-0001 South Texas ProjectUnits 1 & 2Docket Nos. STN 50-498, STN 50-499STPNOC 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 DocumentControl Desk, "Response to NRC Bulletin 2012-01:

Design Vulnerability inElectrical 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 Bulletin2012-01, "Design Vulnerability in Electrical Power System" (Reference

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

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

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 andcompensatory 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. Theenclosure to this letter provides the required response to the RAI.There are no commitments in this letter. 'itlie NOC-AE-14003077 Page 2 of 3If there are any questions regarding this letter, please contact Hung Le at (361) 972-7932 or meat (361) 972-7566.

I declare under penalty of perjury that the foregoing is true and correct.Executed on Tc-A,,.,w4 go. 20i,4G.T. PowellSite Vice President hcl

Enclosure:

Response to Request for Additional Information NOC-AE-14003077 Page 3 of 3cc:(paper copy)(electronic copy)Regional Administrator, Region IVU. S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. SingalSenior Project ManagerU.S. Nuclear Regulatory Commission One White Flint North (MS 8 B1)11555 Rockville PikeRockville, MD 20852NRC Resident Inspector U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16Wadsworth, TX 77483Jim CollinsCity of AustinElectric Utility Department 721 Barton Springs RoadAustin, TX 78704A. H. Gutterman, EsquireMorgan, Lewis & Bockius LLPBalwant K. SingalU. S. Nuclear Regulatory Commission John RaganChris O'HaraJim von SuskilNRG South Texas LPKevin PolioRichard PenaL. D. BlaylockCity Public ServicePeter NemethCrain Caton & James, P.C.C. MeleCity of AustinRichard A. RatliffTexas Department of State HealthServicesRobert FreeTexas Department of State HealthServices Enclosure NOC-AE-14003077 Page 1 of 2Response to Request for Additional Information REQUEST FOR ADDITIONAL INFORMATION FORBULLETIN 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 andManagement System Accession No. ML 12074A1 15), to all holders of operating licenses andcombined licenses for nuclear power reactors.

In addition, Watts Bar Nuclear Plant, Unit 2, isaddressing the issues identified in the bulletin as part of the licensing process.

Bulletin 2012-01requested information about each facility's electric power system designs, in light of recentoperating 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 sincethe January 30, 2012, event at Byron Station, Unit 2, to ensure that plantoperators can promptly diagnose and respond to open phase conditions onthe 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 andmodifications to resolve issues with an open phase of electric power."STPNOC Response1. Summary of All Interim Corrective ActionsLessons learned from the events at Byron station were reviewed and various interimcorrective actions evaluated for safety and efficiency at the South Texas Project.

Based onthe plant's offsite power configuration, electrical design details, and operating experiences, the following actions were taken to ensure plant operators can promptly diagnose andrespond to Open Phase Conditions (OPC):* Interim Corrective Actionso Daily switchyard walk-downs by operations staff are on-going to identify OPCvulnerabilities.

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

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

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

2. Status and Schedule for Completion of Plant Design Changes* Statuso The industry is investigating options being researched by several vendors [Powerand 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 phasefault 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 tosoftware tools being used to analyze OPC faults.o New OPC technology will be thoroughly evaluated,

analyzed, and tested beforeinstallation.

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 andbe completed by the end of this year for South Texas Project Unit 1 and Unit 2[Reference Condition Report (CR) 12-8728-9].

• Scheduleo The South Texas Project Unit 1 and Unit 2 plan to follow the generic scheduleprovided 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 andhardware availability, manufacturer's delivery capabilities, licensing delays, etc.o Any deviation from the Industry OPC Initiative schedule will be documented inthe STP corrective action program and through the deviation/exemption processaddressed in the NEI OPC Guidance Document which is under development.