ML071280709
| ML071280709 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/04/2007 |
| From: | Schwarz C J Entergy Nuclear Operations |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| GL-07-001 | |
| Download: ML071280709 (5) | |
Text
.-Enter~gy Entergy Nuclear Operations, Inc.Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 May 4, 2007 10 CFR 50.54(f)U. S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Palisades Nuclear Plant Docket 50-255 License No. DPR-20 Response to Generic Letter 2007-01, "Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients" for Palisades Nuclear Plant
Dear Sir or Madam:
On February 7, 2007, the Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2007-01, "Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients." The NRC requested that specific information be provided within 90 days of the date of the GL.Entergy Nuclear Operations, Inc. is providing the required response to GL 2007-01 in Enclosure 1 for Palisades Nuclear Plant.Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
,& I -A7 Document Control Desk Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on May 4, 2007.p er J. h Site Vice President Palisades Nuclear Plant Enclosure (1)CC Regional Administrator, Region Ill, USNRC Project Manager, Palisades, USNRC NRC Resident Inspector, Palisades USNRC ENCLOSURE 1 RESPONSE TO GENERIC LETTER 2007-01 Nuclear Regulatory Commission (NRC) Requested Information Within 90 days of the date of the generic letter, addressees are requested to submit the following information to NRC: (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 of failure, type of service, voltage class, years of service, and the root causes for the failures.Entergy Nuclear Operations, Inc. (ENO) Response (1) To date, PNP has experienced two cable failures within the scope of the Generic Letter. Details are provided in Attachment
- 1. In researching plant records for the requested information, ENO used the Nuclear Energy Institute interpretations of the information request provided in the NEI letter from J. H. Riley to NRC, "Interpretation of GL 2007-01, Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients," dated March 26, 2007, with the exceptions noted in NRC letter from M. J. Case to J. H. Riley of NEI,"Response to Nuclear Energy Institute (NEI) Letter Dated March 26, 2007-Re: Interpretation of Generic Letter (GL) 2007-01, Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients," dated April 13, 2007, to clarify the population of cables of interest at Palisades Nuclear Plant (PNP).Databases researched included the plant condition reporting databases, plant work order history database, Institute of Nuclear Power Operations databases, the plant maintenance rule database, and other plant-specific databases.
NRC Requested Information (2) Describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables that support[emergency diesel generators]
EDGs, offsite power, [essential service water] ESW, service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).ENO Response (2) ENO does not have formal inspection, testing, and monitoring programs at PNP to detect the degradation of inaccessible or underground power cables that support EDGs, offsite power, service water (critical
[essential]
and non-critical), component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule). However, Page 1 of 3 ENCLOSURE1 RESPONSE TO GENERIC LETTER 2007-01 ENO does periodically perform preventive maintenance activities for testing the insulation resistance (meggering) of inaccessible or underground power cables (480VAC and above) that support EDGs, offsite power, service water (critical
[essential]
and non-critical), component cooling water and other systems that are within the scope of the Maintenance Rule. During this search, underground cables were identified that have no preventive maintenance activities for periodic meggering.
These cables were entered into the plant corrective action program to evaluate if periodic meggering should be performed as a good practice.
ENO also periodically performs preventive maintenance activities to inspect manholes for dewatering at PNP. The corrective action program is also used to determine root cause and extent of conditions where deemed necessary.
This program would be used for determining the need for and extent of any increased cable or manhole monitoring.
Page 2 of 3 History of Inaccessible or Underground Power Cable Failures within the Scope of 10 CFR 50.65 for Palisades Nuclear Plant Cable Type Voltage Class Manufacturer Date of Type of Service Root Cause Failure /Service (Yrs.)750 thousand circular 5,000 volt General Electric 1/9/1986, Cable ID No. A2102/A21-The failure was in mils, 3/conductor rated, 4,160 -18 years X03/1, bus 1 A feeder cable service. The root cause triplexed, butyl rubber volt service from startup power (bus 1 A indicated that the fault insulation, polyvinyl feeds two reactor coolant was triggered by chloride jacket, pumps and one condensate moisture seeping into shielded (metal- pump), underground conduit, the cable which caused sheathed).
normally energized.
gradual deterioration of the neutral sheath of the cable.1,000 thousand 5,000 volt Anaconda 1/16/1996, Cable ID No. A1203/A12-The failure was in circular mils, rated, 2,400 -6 years X02/1, bus 1 D feeder cable service. The root cause 3/conductor triplexed, volt service from safeguards power (bus was attributed to ethylene propylene 1 D feeds safeguards manufacturing defects in rubber insulation, equipment), underground the cable insulation.
flame resistant-duct bank conduit, normally Localized foreign matter chlorinated energized.
and voids present in the polyethylene jacket, insulation acted as shielded (with initiating points for water corrugated copper treeing degradation drain wires). (water filled micro-voids that propagate over time in wet, energized cables).Page 3 of 3