BSEP 14-0011, Response to Request for Additional Information Regarding NRC Bulletin 2012-01: Design Vulnerability in Electric Power System
| ML14043A169 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 01/31/2014 |
| From: | Hamrick G Duke Energy Carolinas, Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BSEP 14-0011 | |
| Download: ML14043A169 (4) | |
Text
DUKE George T. Hamrick Vice President
- ENERGY, Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461 o: 910.457.3698 January 31, 2014 Serial: BSEP 14-0011 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Duke Energy Progress, Inc. (Duke Energy)
Brunswick Steam Electric Plant, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. DPR-71 and DPR-62 Docket Nos. 50-325 and 50-324 Response to Request for Additional Information Regarding 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, ADAMS Accession Number ML12074A115
- 2. Letter from Michael J. Annacone (Duke Energy Progress, Inc.), to U.S.
Nuclear Regulatory Commission, Response to NRC Bulletin 2012-01:
Design Vulnerability in Electric Power System, dated October 24, 2012, ADAMS Accession Number ML12310A060
- 3. Letter from Michele G. Evans (USNRC) to Michael J. Annacone (Duke Energy Progress, Inc.), Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System," dated December 20, 2013, ADAMS Accession Number ML13351A314 Ladies and Gentlemen:
By letter dated October 24, 2012 (i.e., Reference 2), Duke Energy responded to NRC Bulletin 2012-01 (i.e., Reference 1) for the Brunswick Steam Electric Plant (BSEP), Unit Nos. 1 and 2.
On December 20, 2013 (i.e., Reference 3), the NRC provided a request for additional information (RAI) regarding Duke Energy's bulletin response. The response to the RAI is enclosed.
This document contains no new regulatory commitments.
Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager - Regulatory Affairs, at (910) 457-2487.
U.S. Nuclear Regulatory Commission Page 2 of 2 I declare, under penalty of perjury, that the foregoing is true and correct. Executed on January 31, 2014.
Sincerely, George T. Hamrick
Enclosure:
Response to Request for Additional Information Regarding NRC Bulletin 2012-01: Design Vulnerability in Electric Power System cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region II ATTN: Mr. Victor M. McCree, Regional Administrator 245 Peachtree Center Ave, NE, Suite 1200 Atlanta, GA 30303-1257 U. S. Nuclear Regulatory Commission ATTN: Mr. Siva P. Lingam (Mail Stop OWFN 8G9A) 11555 Rockville Pike Rockville, MD 20852-2738 U. S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626-0510
Enclosure Page 1 of 2 Response to Request for Additional Information Regarding NRC Bulletin 2012-01: Design Vulnerability in Electric Power System NRC letter dated December 20, 2013, requested the following:
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.
Response I - Summary of Interim Corrective Actions Lessons learned from the events at Byron station were reviewed and various interim corrective actions evaluated for effectiveness based on Brunswick plant and transformer design. Based on lessons learned, the following actions have been taken to ensure plant operators can promptly diagnose and respond to an open phase condition:
During Operating Modes 4 and 5, daily walk-downs were performed in the Transformer Yard and Switchyard (e.g., refueling outage March 2013, and maintenance outage May 2013) to identify any open phase conditions (i.e., broken 230kV connections). The walk-downs continue to be procedurally required during Operating Modes 4 and 5. During walk downs, Operations personnel look for any anomalies or out of normal conditions and take appropriate actions.
During Operating Modes 4 and 5, phase-to-phase voltage readings were obtained daily, and are evaluated for acceptability. The voltage readings continue to be procedurally required during Operating Modes 4 and 5.
Operating instructions and training curriculum were reviewed to ensure operators can diagnose and respond to an open phase condition.
Annunciator procedures for each 4kV motor were revised to include an open phase condition as a possible cause for a motor trip.
Operations procedures were revised to include recognition of equipment problems caused by an open phase condition, and appropriate responses.
Annual infrared (i.e., thermography) inspections of yard equipment have been performed and are ongoing.
Response 2 - Status and Schedule for Completion of Plant Design Changes The Duke Energy fleet is investigating options being researched by several vendors (e.g.,
PCS2000, the Electric Power Research Institute (EPRI), Schweitzer, etc.) to detect open phase fault conditions. There is currently no industry technology that has been proven to detect all the required open phase fault conditions for all plant and transformer designs. With the goal of ensuring accurate detection without compromising nuclear safety or increasing plant risk, it is paramount that this new technology being evaluated be tested and fully analyzed before installation. These research investigations are progressing faster than anticipated.
Enclosure Page 2 of 2 Vulnerability studies of the single open phase fault conditions have been started for the Duke Energy nuclear fleet. The Duke Energy nuclear fleet is fully engaged in the development of the Nuclear Energy Institute (NEI) Open Phase Condition Industry Guidance Document, as well as development of enhancements to the Electrical Transient Analysis Program (ETAP) software tool being used to analyze open phase fault conditions.
Brunswick Nuclear Plant intends to follow the schedule provided in the NEI Industry Initiative Document. Any deviations to this schedule required for such items as outage schedules or technology availability will be documented through the NEI exemption process.