Text

Response to NRC Request for Additional Information Regarding Bulletin 2012-01, Design Vulnerability in Electric Power System.
	ML14031A434
Person / Time
Site:	Fermi
Issue date:	01/30/2014
From:	Conner J; DTE Energy
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	BL-12-001, NRC-14-0007
	Download: ML14031A434 (6)
	v • d • e

JI Todd Conner Site Vice President DTE Energy Corpany 6400 N.Dixie Highway, Newport, MI 48166 Tel: 734.586.4849 Fax: 734.586.5295 Email: coanerj@dteenergy.con PTE Energy 10 CFR 50.54(f)

January 30, 2014 NRC-14-0007 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) NRC Letter, "Request for Additional Information Regarding Response to Bulletin 2012-01, 'Design Vulnerability in Electric Power System,"' dated December 20, 2013 (ML13351A314)

3) DTE Electric Company Letter to NRC, "Fermi 2 90-Day Response to NRC Bulletin 2012-01: Design Vulnerability in Electric Power System," NRC-12-0059, dated October 24, 2012 (ML12299A246)

4) Nuclear Energy Institute (NEI) Letter to NRC, "Industry Initiative on Open Phase Condition, Project Number: 689," dated October 9, 2013 (ML13333A147)

Subject:

Response to NRC Request for Additional Information Regarding Bulletin 2012-01, "Design Vulnerability in Electric Power System" In Reference 2, NRC staff requested additional information regarding initiatives associated with NRC Bulletin 2012-01, "Design Vulnerability in Electric Power System." The Enclosure to this letter provides the DTE Electric Company (DTE) response to the RAI.

Should you have any questions or require additional information, please contact Mr.

Zackary W. Rad of my staff at (734) 586-5076.

Sincerely,

USNRC NRC-14-0007 Page 2

Enclosure:

DTE Response to NRC RAI Regarding Bulletin 2012-01 cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission, Regulated Energy Division (kindschl@michigan.gov)

USNRC NRC-14-0007 Page 3 I, J. Todd Conner, do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.

J. Todd Conner Site Vice President Nuclear Generation On this 3 0 day of January, 2014 before me personally appeared J. Todd Conner, being first duly sworn and says that he executed the foregoing as his free act and deed.

Notary Public SHARON S. MARSHALL NOTARY PUBLIC, STATE OF MI COUNTY OF MONROE MY COMMISSION EXPIRES Jun 14, 2019 ACTING INCOUNTY OF A4

Enclosure to NRC-14-0007 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 DTE Response to NRC RAI Regarding Bulletin 2012-01

Enclosure to NRC-14-0007 Page 1 RAI Regarding Bulletin 2012-01 On July 27, 2012, the US. Nuclear Regulatory Commission (NRC) issued Bulletin 2012-01, "Design Vulnerability in Electric Power System" (Agencywide DocumentsAccess 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 requestedinformation about each facility'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.

In orderfor the NRC staff to complete its review of responses to the bulletin, the following additionalinformation 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 thatplant operatorscan promptly diagnose and respond to open phase conditions on the offsite power circuitsfor Class-1E vital buses until permanentcorrective actions are completed.

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

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 reliability at Fermi 2. Based on the plant's offsite power 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):

" Interim Corrective Actions o Performed a review of the station's offsite power support, switchyard configurations, and electrical distribution system designs, including walkdowns, to determine potential OPC vulnerability and verify the extent of susceptibility to OPC for both Divisions. The extent of susceptibility is limited to approximately 20' for Division 1 and approximately 1000' of radial tapline to the SAT SS65 for Division 2. Divisional switchyards, including both areas of OPC susceptibility, are inside the plant perimeter. See the system description provided in Reference 3.

o Performed walkdowns of the switchyards and verified the absence of Ohio Brass insulators or post insulators used in an underhung, tensioned fashion.

Enclosure to NRC-14-0007 Page 2 o Implemented periodic walkdowns of the switchyards to identify OPC vulnerabilities. The areas of potential OPC susceptibility are located within the plant perimeter and are inspected daily.

o Revised daily operator outside rounds to incorporate specific points of inspection for potentially susceptible lines and connectors.

o Implemented operator training to ensure operators can recognize, diagnose, and respond to an OPC.

o Implemented new response procedures to provide operational instructions addressing OPC.

o Implemented weekly and situational monitoring via thermography of the vulnerable connections within the areas of OPC susceptibility.

o DTE is currently performing a quantitative OPC engineering analysis with industry recognized and qualified software (ETAP Version 12 PowerStation).

2. Status and Schedule for Completion of Plant Design Changes

" Status o All holders of operating licenses and combined licenses for nuclear power reactors are investigating options being researched by several vendors (PSC2000, 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 All holders of operating licenses and combined licenses for nuclear power reactors are fully engaged in the development of the NEI OPC Guidance Document, as well as development of enhancements to software tools being used to analyze OPC faults.

o All new OPC technologies and options are being evaluated for reliability and will be fully analyzed to ensure that nuclear safety is not compromised and plant risk is not increased.

o Vulnerability studies of the OPC faults have begun for Fermi 2. Additionally, DTE is evaluating potential viable solutions to preclude OPC vulnerabilities due to the plant's unique system configuration as delineated in the system description provided in Reference 3.

" Schedule o DTE has committed to the schedule provided in the Industry OPC Initiative (Reference 4).

o It is DTE's intention to meet the 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 through the deviation/exemption process addressed in the NEI OPC Guidance Document (currently under development as discussed in Reference 4).