ML14035A456

Response to Request for Additional Information Regarding Response to Bulletin 2012-01, Design Vulnerability in Electric Power System.

ML14035A456
Person / Time
Site:	Calvert Cliffs
Issue date:	01/31/2014
From:	Gellrich G H Calvert Cliffs, Constellation Energy Nuclear Group, EDF Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001
Download: ML14035A456 (5)

Text

George H. Gellrich Vice President Calvert Cliffs Nuclear Power Plant, LLC 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410.495.5200 410.495.3500 Fax CENG a joint venture of 0Constellation ey19DF Energy- D CALVERT CLIFFS NUCLEAR POWER PLANT January 31, 2014 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:

REFERENCES:

Document Control Desk Calvert Cliffs Nuclear Power Plant Unit Nos. 1 and 2; Docket Nos. 50-317 and 50-318 Response to Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System" (a) Letter from Mr. G. H. Gellrich (CCNPP) to Document Control Desk (NRC), dated October 23, 2012, Response to NRC Bulletin 2012-01,"Design Vulnerability in Electric Power System" (b) Letter from Ms. M. G. Evans (NRC) to Mr. G. H. Gellrich (CCNPP), dated December 20, 2013, Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System" In Reference (a), Calvert Cliffs Nuclear Power Plant, LLC submitted the required response to Nuclear Regulatory Commission Bulletin 2012-01, Design Vulnerability in Electric Power System. In Reference (b), the Nuclear Regulatory Commission requested additional information to support their review of Reference (a). Attachment (1) provides the responses to the Nuclear Regulatory Commission's request for additional information contained in Reference (b).No regulatory commitments are contained in this letter.w~j..

Document Control Desk January 31, 2014 Page 2 Should you have questions regarding this matter, please contact Mr. Douglas E. Lauver, Director-Licensing, at (410) 495-5219.I declare under penalty of perjury that the foregoing is true and correct. Executed on January 31, 2014.Very truly yours, GHG/PSF/bjd

Attachment:

(1) Response to Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System" cc: NRC Project Manager, Calvert Cliffs NRC Regional Administrator, Region I NRC Resident Inspector, Calvert Cliffs S. Gray, MD-DNR ATTACHMENT (1)RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO BULLETIN 2012-01, "DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM" Calvert Cliffs Nuclear Power Plant, LLC January 31, 2014 ATTACHMENT (1)RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO BULLETIN 2012-01, "DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM" RAIl: 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- JE vital buses until permanent corrective actions are completed.

CCNPP Response 1: Lessons learned from the events at Byron Station were reviewed and various interim corrective actions evaluated for safety and efficiency at Calvert Cliffs Nuclear Power Plant (CCNPP). Based on the plant's offsite power configuration, electrical design details, and on lessons learned, the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):-Operating crews at CCNPP were briefed on the operating indications for a single loss of phase on the alternating current high and medium voltage systems.-A long-term note was added to the Shift Turnover Sheet to maintain 13 kV and 4 kV vital bus voltmeters in position "3-1" (A-C phase) to allow CCNPP operating crews to identify the precursors to the Byron event and minimize its potential at CCNPP.-The Unit I and 2 Control Room operating logs have been revised to check that the 13 kV and 4 kV bus voltages are within range and that the voltage phase selector switch is in the "3-1" position.-Periodic walk-downs of the switchyard are conducted to identify OPC vulnerabilities.

-Transformer yard rounds are performed weekly and include general and detailed inspections of the transformers to ensure parameters are within expected limits.-Annual infrared inspections of yard equipment are completed as part of routine inspections.

RAI2: Provide a status and schedule for completion of plant design changes and modifications to resolve issues with an open phase of electric power.CCNPP Response 2: Status:-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.-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.I ATTACHMENT (1)RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO BULLETIN 2012-01, "DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM"-With the goal of ensuring accurate detection without compromising nuclear safety or increasing plant risk, this new OPC technology is being thoroughly evaluated, will be tested, and will be fully analyzed before installation.

-Vulnerability studies of the OPC faults have been started for CCNPP.Schedule:-Calvert Cliffs Nuclear Power Plant has committed to the generic schedule provided in the Industry OPC Initiative.

-It is our 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 NEI OPC Guidance Document.2