0CAN021401, 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: | Browning J G Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 0CAN021401, BL-12-001 | |
| Download: ML14034A412 (7) | |
Text
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
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. Entergy Operations, Inc.
1448 S.R. 333 Russellville, AR 72802
Tel 479-858-3110 Jeremy G. Browning Site Vice President A rkansas Nuclear One
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
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 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, 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 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.
COMMITMENT TYPE (Check One)
SCHEDULED COMPLETION DATE (If Required)
ONE-TIME ACTION CONTINUING COMPLIANCE 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, manufacturer's delivery
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. X December 31, 2017