ML071340045

Calvert Cliffs, Nine Mile Point, R. E. Ginna, 90-Day Response to Generic Letter 2007-01, Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients.

ML071340045
Person / Time
Site:	Calvert Cliffs, Nine Mile Point, Ginna
Issue date:	05/07/2007
From:	Heffley J M Constellation Energy Group
To:	Document Control Desk, NRC/NRR/ADRO
References
GL-07-001
Download: ML071340045 (4)

Text

J. M. Heffley Chief Nuclear Officer 0 Constellation Energy Generation Group Constellation Generation Group 1997 Annapolis Exchange Parkway Suite 310 Annapolis, MD 21401 410-897-5020 May 7, 2007 U. S. Nuclear Regulatory Commission 1555 Rockville Pike Rockville, MD 20852 ATTENTION:

SUBJECT:

Document Control Desk Calvert Cliffs Nuclear Power Plant Unit Nos. I & 2; Docket Nos. 50-317 & 50-318 Nine Mile Point Nuclear Station Unit Nos. I & 2; Docket Nos. 50-220 & 50-410 R.E. Ginna Nuclear Power Plant Docket No. 50-244 90-Day Response to Generic Letter 2007-01

REFERENCE:

(a) Generic Letter 2007-01, "Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients," dated February 7, 2007 Generic Letter 2007-01 (Reference a) was issued by the Nuclear Regulatory Commission to: (1) Inform licensees that the failure of certain power cables can affect the functionality of multiple accident mitigation systems or cause plant transients.

(2) Inform licensees that in the absence of adequate monitoring of cable insulation, equipment could fail abruptly during service, causing plant transients or disabling accident mitigation systems.(3) Ask licensees to provide information on the monitoring of inaccessible or underground electrical cables.The generic letter also required a response within 90 days of the issue date.We have researched files at Calvert Cliffs Nuclear Power Plant (CCNPP), Nine Mile Point Nuclear Station (NMPNS), and R.E. Ginna Nuclear Power Plant (Ginna) for failures of underground and inaccessible power cables of any voltage within the scope of 10 CFR 50.65 (the Maintenance Rule).These searches utilized data bases, paper files, and microfiche.

A IQ 7 Document Control Desk May 7, 2007 Page 2 The generic letter request for information is in two parts. The responses for CCNPP, NMPNS, and Ginna are presented below.Request 1: Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicate the type, manufacturer, date offailure, type of service, voltage class, years of service, and the root causes for the failure.Response: No record of inaccessible or underground power cable failures within the scope of 10 CFR 50.65 (the Maintenance Rule) was found at CCNPP, NMPNS, or Ginna.Request 2: Describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables that support EDGs, offsite power, ESW, service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).Calvert Cliffs Nuclear Power Plant Response: Manholes are inspected approximately once a year for water and, if water is found, it is removed. This preventive maintenance inspection routine was established to reduce the likelihood that underground power cables are exposed to a water environment or to reduce the length of exposure to water. Also, some manholes have sump pumps. These preventive measures do not detect degradation of inaccessible or underground power cables but they assist in eliminating or reducing the likelihood that these cables are subjected to a wet environment.

The inaccessible and underground power cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) are maintained continuously energized except for the power cables for the saltwater pumps. On a routine basis, the energized cables are de-energized to support preventative maintenance tasks and, at that time, are tested to ground by means of a megohm-meter (meggar).The six cables that provide power to the six saltwater pumps (three per unit) are inaccessible.

Two of the pumps in each unit are operating at any given time and the cables are, therefore, energized.

The third pump is typically started weekly, thereby functionally testing the power cables for this motor. The insulation of all of the saltwater pump cables is tested with a meggar as part of routine maintenance.

Nine Mile Point Nuclear Station Response: Manholes are inspected approximately every six months for water and, if water is found, it is removed.This preventive maintenance inspection routine was established to reduce the likelihood that underground power cables are exposed to a water environment or to reduce the length of exposure to water. Also, some manholes have installed sump pumps. These preventive measures do not detect degradation of inaccessible or underground power cables but they assist in eliminating or reducing the likelihood that these cables are subjected to a wet environment.

Since there is no history of failure and the exposure to moisture is reduced by routine pumping of manholes, NMPNS has not established inspection, testing, and monitoring programs specifically to detect degradation of inaccessible or underground power cables that are within the scope of 10 CFR Document Control Desk May 7, 2007 Page 3 50.65 (the Maintenance Rule). However, some inaccessible and underground power cables that are within the scope of 10 CFR 50.65 are tested to ground with a meggar as part of the associated motor's routine maintenance.

R.E. Ginna Nuclear Power Plant Response: Repetitive tasks have been established within the overall maintenance program such that periodic testing is performed on all of the inaccessible or underground power cables within the scope of 10 CFR 50.65 (the Maintenance Rule). The testing methods include, but are not limited to, Time Domain Reflectometry, Megger, and Hi Pot. An exception to this testing are four 115 kV power cables that are in an oil-filled cable duct. These cables are continuously energized.

This letter provides information requested by Generic Letter 2007-01 and does not contain regulatory commitments.

Document Control Desk May 7, 2007 Page 4 Should you have questions regarding the information in this submittal, please contact Mr. L. S. Larragoite at (410) 897-5087.Very truly yours, 4(Joh) M. Heffley itef Nuclear O fficer STATE OF MARYLAND TO WIT COUNTY OF ANNE ARUNDEL I, John M. Heffley, state that I am Chief Nuclear Officer, Constellation Generation Group, LLC, for Calvert Cliffs Nuclear Power Plant, Inc., Nine Mile Point Nuclear Station, LLC, and R. E. Ginna Nuclear Power Plant, LLC, and that I am duly authorized to execute and file this response on behalf of these companies.

To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by employees and/or consultants of the companies.

Such information has been reviewed in accordance with company practice, and I believe it to be reliable.cribed and sworn before me, a Notary Public, in/vej'f- , thisli'Aday of ,2007.WITNESS my Hand and Notarial Seal: My Commission Expires: and for the State of Marylan and County of 4otary Public Date JMH/EMT/jmp cc: Director, Project Directorate I-1, NRC D. V. Pickett, NRC S. J. Collins, NRC Resident Inspector, NRC (Calvert Cliffs)Resident Inspector, NRC (Ginna)Resident Inspector, NRC (Nine Mile)R. I. McLean, Maryland DNR J. P. Spath, NYSERDA P. D. Eddy, NYSOPS