0CAN021401, Units 1 and 2, Response to Request for Additional Information (Rai)Regarding Response to Bulletin 2012-01, Design Vulnerability in Electric Power System

Units 1 and 2, Response to Request for Additional Information (Rai)Regarding Response to Bulletin 2012-01, Design Vulnerability in Electric Power System

ML14034A412
Person / Time
Site:	Arkansas Nuclear
Issue date:	02/03/2014
From:	Jeremy G. Browning Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
0CAN021401, BL-12-001
Download: ML14034A412 (7)

Text

Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802 Tel 479-858-3110 Jeremy G. Browning Site Vice President Arkansas Nuclear One 0CAN021401 February 3, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852

SUBJECT:

Response to Request for Additional Information (RAI)

Regarding Response to Bulletin 2012-01, Design Vulnerability in Electric Power System Arkansas Nuclear One - Units 1 and 2 Docket Nos. 50-313 and 50-368 License Nos. DPR-51 and NPF-6

REFERENCES:

1. NRC Bulletin 2012-01 Design Vulnerability in Electric Power System, dated July 27, 2012 (0CNA071207) (ML12074A115)

2. Entergy letter to NRC, 90-Day Response to Bulletin 2012-01, Design Vulnerability in Electric Power System, dated October 25, 2012 (0CAN101201) (ML12299A391)

3. NRC letter to Entergy, RAI Regarding Response to Bulletin 2012-01, Design Vulnerability in Electric Power System, dated December 20, 2013 (0CNA121306) (ML13351A314)

Dear Sir or Madam:

On July 27, 2012, the NRC issued Bulletin 2012-01, Design Vulnerability in Electric Power System (Reference 1). Entergy provided the required 90-day response for Arkansas Nuclear One, Units 1 and 2, in Reference 2. The NRC subsequently issued a Request for Additional Information (RAI) via Reference 3. Attachment 1 provides responses to the RAI.

This letter contains a new regulatory commitment, which is identified in Attachment 2.

Should you have any questions concerning the content of this letter, please contact Stephenie Pyle at 479.858.4704.

0CAN021401 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on February 3, 2014.

Sincerely, ORIGINAL SIGNED BY JEREMY G. BROWING JGB/mkh Attachments: 1. Response to Request for Additional Information (RAI) Regarding Response to NRC Bulletin 2012-01

2. List of Regulatory Commitments cc: Mr. Marc L. Dapas Regional Administrator U. S. Nuclear Regulatory Commission, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Alan Wang MS O-88B1 One White Flint North 11555 Rockville Pike Rockville, MD 20852 U. S. Nuclear Regulatory Commission Attn: Mr. Michael Orenak MS O-8G9A One White Flint North 11555 Rockville Pike Rockville, MD 20852

Attachment 1 to 0CAN021401 Response to Request for Additional Information (RAI)

Regarding Response to NRC Bulletin 2012-01 to 0CAN021401 Page 1 of 2 Response to Request for Additional Information (RAI)

Regarding Response to NRC Bulletin 2012-01 RAI 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 (OPC) on the offsite power circuits for Class-1E vital buses until permanent corrective actions are completed.

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 Arkansas Nuclear One (ANO). Based on the plants offsite power configuration, electrical design details, and lessons learned, the following actions were taken to ensure plant operators can promptly diagnose and respond to OPCs:

Interim Corrective Actions o Weekly walk-downs of the switchyard to identify OPC vulnerabilities are on-going.

o Operating instructions and training curriculum were reviewed to ensure operators can diagnose and respond to an OPC.

o ANO has negative sequence overvoltage relays that alarm if negative sequence is greater than or equal to 5%. The annunciator corrective actions have been revised to alert operators to the potential that the Negative Sequence alarm may be due to an OPC.

o Transformer yard rounds are performed daily which include inspections of the transformers to ensure parameters are within expected limits.

o Bi-annual infrared inspections of yard equipment are being completed as part of routine inspections (performed at power).

to 0CAN021401 Page 2 of 2 RAI 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 2 - Status and Schedule for Completion of Plant Design Changes Status o Entergy Operations, Inc. (Entergy) is investigating options being researched by several vendors (PSC2000, Electric Power Research Institute, Schweitzer, etc.) to detect OPC faults. There is currently no generic, off-the-shelf technology that has been proven to detect all the required OPC faults for all plant and transformer designs.

o With the goal of ensuring accurate detection without compromising nuclear safety or increasing plant risk, this new OPC technology is being thoroughly evaluated and tested to provide reasonable assurance of precluding false operation of automatic features.

Schedule o Entergy has committed to the generic schedule provided in the Industry OPC Initiative.

o It is Entergy's intention to meet the milestones of this schedule; however, deviations may be required to accommodate outage schedules, software and hardware availability, manufacturers 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 Nuclear Energy Institute OPC Guidance Document.

Attachment 2 to 0CAN021401 List of Regulatory Commitments to 0CAN021401 Page 1 of 1 List of Regulatory Commitments The following table identifies those actions committed to by Entergy Operations, Inc. (Entergy) in this document. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.

TYPE SCHEDULED (Check One) COMPLETION COMMITMENT ONE-TIME CONTINUING DATE ACTION COMPLIANCE (If Required)

Entergy has committed to the generic schedule provided in the Industry OPC Initiative. It is Entergy's intention to meet the milestones of this schedule; however, deviations may be required to accommodate outage schedules, software and hardware availability, manufacturers delivery X December 31, 2017 capabilities, licensing delays, etc.

Any deviation from the Industry OPC Initiative schedule will be documented through the deviation/exemption process addressed in the Nuclear Energy Institute OPC Guidance Document.