ET 07-0007, 90 Day Response to NRC Generic Letter 2007-01, Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients

90 Day Response to NRC Generic Letter 2007-01, Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients

ML071290049
Person / Time
Site:	Wolf Creek
Issue date:	05/02/2007
From:	Garrett T Wolf Creek
To:	Document Control Desk, NRC/NRR/ADRO
References
ET 07-0007, GL-07-001
Download: ML071290049 (4)

Text

WLF CREEK NUCLEAR OPERATING CORPORATION Terry J. Garrett Vice President, Engineering May 2, 2007 ET 07-0007 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

Docket No. 50-482: 90 day response to NRC Generic Letter 2007-01, Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients Gentlemen:

Pursuant to 10 CFR 50.54(f), the attachment to this letter provides the Wolf Creek Nuclear Operating Corporation (WCNOC) 90-day response to NRC Generic Letter 2007-01, "Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients." The generic letter requests licensees to provide a history of inaccessible or underground power cable failures and to describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables for cables within the scope of 10 CFR 50.65.

There are no commitments made to the NRC by this letter. If you have any questions concerning this matter, please contact me at (620) 364-4084, or Mr. Kevin Moles at (620) 364-4126.

Sincerely, Terry J. Garrett TJG/rlt Attachment cc: J. N. Donohew (NRC), w/a V. G. Gaddy (NRC), w/a B. S. Mallett (NRC), w/a Senior Resident Inspector (NRC), w/a P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HCNVET A)0aq

ET 07-0007 Page 2 of 2 STATE OF KANSAS )

COUNTY OF COFFEY )

Terry J. Garrett, of lawful age, being first duly sworn upon oath says that he is Vice President Engineering of Wolf Creek Nuclear Operating Corporation; that he has read the foregoing document and knows the contents thereof; that he has executed the same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

Terry J/i/ arrett Vice PI(esident Engineering SUBSCRIBED and sworn to before me this or.d2ay of M".aA, 2007.

L 72Th'2dL/~4 Notary Public OP Expiration Date /0_)7p* /,

Attachment to ET 07-0007 Page 1 of 2 Response to Requested Information of NRC Generic Letter 2007-01, Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients Below is the Wolf Creek Nuclear Operating Corporation (WCNOC) response to the Requested Information of NRC Generic Letter 2007-01, "Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients." The generic letter's "Requested Information" is shown in bold followed by WCNOC's response.

NRC Requested Information Item (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 failure.

WCNOC Response (1):

Research into inaccessible or underground power cable failures at Wolf Creek Generating Station (WCGS) revealed one failure in power cables within the scope of 10 CFR 50.65. Table 1 below contains the information requested as well as additional information on failure type, component supported and cable identifier. The cable identified in Table 1 is an above-ground cable, but considered to be inaccessible because it is routed in conduit.

Table 1. WCGS Inaccessible or Underground Power Cable Failures Failure Type of Type Cable Type Cable Type Service (inservice/ (Insulation (Shielded, Cable Date of (energized/

Failure # testing) Type) Yes/No) Manufacturer Failure deenergized) 1 Inservice HTK No Kerite 2004 Energized Voltage Voltage Class Class Years of (nominal (cable Service Root Causes for Component Cable service rating Prior to the Failure Failure # Supported Identifier voltage) voltage) Failure (apparent cause) 1 Startup 16MRX01AT 13.8KV 15KV ~20 One conductor of triplex transformer cable faulted due to inside XMR01 out water intrusion caused by water entering an improperly sealed end of the cable through a termination inspection peep hole.

(Outdoors, above grade)

Attachment to ET 07-0007 Page 2 of 2 NRC Requested Information Item (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).

WCNOC Response (2):

WCNOC has not implemented inspection, testing or monitoring programs to detect the degradation of inaccessible or underground power cables.

WCNOC periodically performs visual inspection for corrosion and degradation of cable tray supports and visual inspection of the ends of the cables for jacket degradation of medium voltage cables installed in manholes. These actions help to eliminate or minimize conditions known to impact cable degradation rates for cables that are within the scope of 10 CFR 50.65.

As a part of the License Renewal process, several aging management programs have been developed and will be put into place prior to the end of Wolf Creek's present 40-year license.

Reference 1 includes a commitment to implement a new program for inaccessible medium voltage cables not subject to 10 CFR 50.49 environmental qualification requirements. As described in reference 1, this program will be implemented prior to the period of extended operation and will include:

" Periodic inspection of cable manholes and removal of collected water.

• Testing of in-scope cables to provide an indication of the conductor insulation condition, such as:

o A periodic polarization index test as described in EPRI TR-103834-P1-2 or o Other testing that is state-of-the-art at the time of the testing is performed.

Reference:

1. Letter ET 06-0038, dated September 27, 2006, from T. Garrett, WCNOC, to USNRC.