GO2-10-166, Response to Request for Additional Information License Renewal Application

Response to Request for Additional Information License Renewal Application

ML103280371
Person / Time
Site:	Columbia
Issue date:	11/19/2010
From:	Gambhir S Energy Northwest
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GO2-10-166
Download: ML103280371 (4)

Text

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Sudesh K. Gambhir Vice President, Technical Services ENERGY P.O. Box 968, Mail Drop PE04 NORTHW EST Richland, WA 99352-0968 Ph. 509-377-8313 F. 509-3T7-2354 sgambhir@energy-northwest.com November 19, 2010 G02-10-166 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

COLUMBIA GENERATING STATION, DOCKET NO. 50-397 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION

References:

1) Letter, G02-1 0-11, dated January 19, 2010, WS Oxenford (Energy Northwest) to NRC, "License Renewal Application"

2) Letter dated August 16, 2010, NRC to SK Gambhir (Energy Northwest),

"Request for Additional Information for the Review of the Columbia Generating Station, License Renewal Application," (ADAMS Accession No. ML102230369)

3) Letter, G02-21-10-139, dated September 21, 2010, SK Gambhir (Energy Northwest), to NRC, "Request for Additional Information for the Review of the Columbia Generating Station, License Renewal Application

Dear Sir or Madam:

By Reference 1, Energy Northwest requested the renewal of the Columbia Generating Station (Columbia) operating license. Via Reference 2, the Nuclear Regulatory Commission (NRC) requested additional information (RAI) related to the Energy Northwest submittal. In Reference 3, Energy Northwest responded to Reference 2.

Following conversations with Ms. Evelyn Gettys, NRC License Renewal Project Manager, and other NRC staff members, Energy Northwest decided to revise the response to RAI 3.6-2 provided in Reference 3.

The attachment is the revised response to RAI 3.6-2 contained in Reference 2. The revised response is a complete replacement for the original response provided in Reference 3. No new commitments are included in this response.

If you have any questions or require additional information, please contact Abbas Mostala at (509) 377-4197.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on the date of this letter.

mctfully, mbhir Vice President, Technical Services

Attachment:

Revised Response to Request for Additional Information cc: NRC Region IV Administrator NRC NRR Project Manager NRC Senior Resident Inspector/988C EJ Leeds - NRC NRR EFSEC Manager RN Sherman - BPA/1 399 WA Horin - Winston & Strawn EH Gettys - NRC NRR (w/a)

BE Holian - NRC NRR RR Cowley - WDOH

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION Attachment Page 1 of 2 REVISED RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RAI 3.6-2

Background:

In LRA Table 3.6.2-1, under component/commodity group, "Uninsulated Ground Conductors and Connections," the applicant indicated that there are no aging effects requiring management for the metallic components of uninsulated ground conductors and connections.

Issue:

The LRA did not provide technical justification of how uninsulated ground conductors and connections are not subject to aging degradation such as loss of material due to general corrosion in soil environment.

Request:

Provide a detail technical justification as to why uninsulated ground conductors are not subject to any aging degradation.

Energy Northwest Response (revised)

The uninsulated ground conductors and connections at Columbia Generating Stations (Columbia) include the bare conductors which ground various buildings and the grounding grid. The conductors are described in the applicable electrical drawings as bare copper. The connections are not strictly electrical connections, but straps, lugs, or mounting brackets that support the ground conductors. The bare copper conductor and connections could potentially be subject to corrosion and a loss of material properties as mentioned in the EPRI Electrical Handbook. However, the review of industry operating experience (from the Electrical Handbook) listed no findings associated with uninsulated ground conductors and connections.

Copper is a good choice for this application because of its high electrical conductivity, high fusing temperature, and high corrosion resistance. Copper is also relatively strong, and it is easy to join by welding, compression, or clamping. Ground connections are commonly made with welds or mechanical type connectors, which include compression-, bolted-, and wedge-type devices.

Energy Northwest reviewed industry technical information regarding material aging and has determined that there are no aging effects at Columbia requiring management for copper grounding materials. In addition, Energy Northwest reviewed industry and plant operating experience and did not identify any failures of copper ground systems due to aging effects. A review of the Columbia plant-specific operating experience showed no failures of the plant grounding system. In addition, the lack of significant rainfall at

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION Attachment Page 2 of 2 Columbia, the water table about 60 feet below ground surface level, and the moderate climate precludes deleterious impact to the copper conductors from corrosion. Energy Northwest also inspected underground portions of the Columbia grounding system in the transformer yard in 2009 during a plant modification. No aging-related effects were identified during the inspection. Therefore, based on industry and plant-specific operating experience, no aging effects requiring management were identified for the uninsulated ground conductors and connections at Columbia.