NLS2010079, Response to Cooper Nuclear Station License Renewal Request for Additional Information
| ML102360174 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 08/20/2010 |
| From: | Dori Willis Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2010079 | |
| Download: ML102360174 (9) | |
Text
H Nebraska Public Power District Always there when you need us 54.17 NLS2010079 August 20, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Response to Cooper Nuclear Station License Renewal Request for Additional Information Cooper Nuclear Station, Docket No. 50-298, DPR-46
References:
- 1. Letter from Bo Pham, U.S. Nuclear Regulatory Commission, to Brian O'Grady, Nebraska Public Power District, dated August 16, 2010, "Completion of Cooper Nuclear Station License Renewal Review."
- 2. Letter from Stewart B. Minahan, Nebraska Public Power District, to U.S.
Nuclear Regulatory Commission, dated September 24, 2008, "License Renewal Application" (NLS2008071).
Dear Sir or Madam:
The purpose of this letter is for the Nebraska Public Power District to respond to a Nuclear Regulatory Commission Request for Additional Information (Reference 1) related to the Cooper Nuclear Station License Renewal Application (LRA) (Reference 2). This response is provided in . Certain conforming changes to the LRA are provided in Attachment 2.
The General Manager of Plant Operations is authorized to sign under oath or affirmation in the absence of the Chief Nuclear Officer in accordance with Regulatory Issue Summary 01-018.
Should you have any questions regarding this submittal, please contact David Bremer, License Renewal Project Manager, at (402) 825-5673.
COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.com
NLS2010079 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct.
Executed on 0O " *
(D te)
Sincerely, DemetisL.Wli General Manager of Plant Operations
/wv Attachments cc: Regional Administrator w/attachments USNRC - Region IV Cooper Project Manager w/ attachments USNRC - NRR Project Directorate IV- 1 Senior Resident Inspector w/ attachments USNRC - CNS Nebraska Health and Human Services w/ attachments Department of Regulation and Licensure NPG Distribution w/ attachments CNS Records w/ attachments
NLS2010079 Attachment 1 Page 1 of 3 Attachment 1 Response to Cooper Nuclear Station License Renewal Request for Additional Information Cooper Nuclear Station, Docket No. 50-298, DPR-46 The Nuclear Regulatory Commission (NRC) Request for Additional Information (RAI) regarding the License Renewal Application (LRA) is shown in italics. The Nebraska Public Power District's (NPPD) response to the RAI is shown in block font.
NRC Request: RAIB.1.25-2
Background
NUREG-1801, Rev. 1, "GenericAging Lessons Learned," (the GALL Report) addresses inaccessible medium voltage cables in aging managementprogram (AMP)XIE3, "Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements." The purpose of this program is to provide reasonableassurance that the intendedfunctions of inaccessiblemedium voltage cables (2 kV to 35 kV), that are not subject to environmental qualification requirements of 10 CFR 50.49 and are exposed to adverse localized environments caused by moisture while energized, will be maintainedconsistent with the current licensing basis. The scope of the program applies to inaccessible (in conduits, cable trenches, cable troughs, duct banks, undergroundvaults or direct buried installations)medium-voltage cables within the scope of license renewal that are subject to significant moisture simultaneously with significant voltage.
The applicationof AMP X.E3 to medium voltage cables was based on the operating.experience (OE) available at the time Revision 1 of the GALL Report was developed. However, recently identified industry OE indicates that the presence of water or moisture can be a contributing factor in inaccessiblepower cablesfailures at lower service voltages (480 V to 2 kV). Applicable OE was identified in licensee responses to GenericLetter 2007-01, "Inaccessibleor UndergroundPower Cable Failuresthat DisableAccident Mitigation Systems or Cause Plant Transients," which includedfailures ofpower cable operatingat service voltages of less than 2 kV where water was considereda contributingfactor. The staff has proposed changes to be included in the next revision of the GALL Report AMP XI.E3 to address recently identified OE concerning the failure of inaccessible low voltagepower cables, which includes general water intrusion as afailure mechanism and increases the scope ofprogram to includepower cables greaterthan or equal to 480 V.
Issue The staff has concluded, based on recently identified industry OE concerning the failure of inaccessiblelow voltage power cables (480 V to 2 kV) in the presence of significantmoisture, that these cables should be included in an AMP. The staff notes thatyour AMP does not address these low voltage cables.
NLS2010079 Page 2 of 3 Request
- 1. Provide a summary of the evaluation of recently identified industry OE and any plant-specific OE concerninginaccessible low voltage power cablefailures within the scope of license renewal (not subject to 10 CFR 50.49 environmental qualification requirements),
and how this OE applies to the need for additionalaging management activities by the applicantfor such cables.
- 2. Provide a discussion of how Cooper Nuclear Station will manage the effects of aging on inaccessible low voltage power cables within the scope of license renewal andsubject to aging management review; with considerationof recently identified industry OE and relevantplant-specific OE. The discussion should include assessment ofyour AMP description,program elements (i.e., Scope of Program,ParametersMonitored/Inspected, Detection ofAging Effects, and CorrectiveActions), and FinalSafety Analysis Report summary description to demonstrate reasonableassurance that the intendedfunctions of inaccessible low voltage power cables subject to adverse localized environments will be maintainedconsistent with the currentlicensing basis through the period of extended operation.
NPPD Response:
I1. NPPD responded to Generic Letter (GL) 2007-01, "Inaccessible or Underground Power Cable Failures That Disable Accident Mitigation Systems or Cause Plant Transients," in a letter dated May 7, 2007 (NLS 2007029, ADAMS Accession Number ML071300389).
In this letter, NPPD stated in response to Question 1 that Cooper Nuclear Station (CNS) had experienced zero failures of those cables within the scope of GL 2007-01 (i.e., within the scope of 10 CFR 50.65 (Maintenance Rule)). The inaccessible low-voltage cables (480 V to 2 kV) that are in scope for license renewal are also in scope for the Maintenance Rule. Therefore, the GL 2007-01 results are applicable to this RAI response.
CNS operating experience from May 7, 2007, to August 16, 2010, was researched in the Corrective Action Program database. CNS has experienced no age-related failures of inaccessible low-voltage power cables that are within the scope of license renewal and subject to aging management review since the response to GL 2007-01. One event was noted during the CNS operating experience search. In May 2008, an inaccessible electrical power cable to a safety-related sump pump motor was found damaged during a routine surveillance. The damage was subsequently determined to have occurred prior to installation. This condition was not associated with aging and the damaged cable was replaced.
Regarding recently identified industry operating experience, NPPD has reviewed the information provided in the industry responses to GL 2007-01, recent NRC and Electric Power Research Institute guidance documents, and recent industry/NRC meetings on this topic. It was determined no program changes are required from this review of recent
NLS2010079 Page 3 of 3 industry operating experience. Nevertheless, NPPD has determined that it is appropriate to expand the scope of the LRA B. 1.25 (Non-EQ Inaccessible Medium-Voltage Cable) aging management program to include the in-scope inaccessible low-voltage power cables, as described in the response to Question 2.
- 2. In response to Question 2 of GL 2007-01, NPPD stated:
CNS inspection, testing and monitoring practices for inaccessible or underground power cables presently include periodic meggering of 4160 and 480VAC motors and feeder cables. The duct banks for the safety related service water pumps are sloped downward toward manholes with sump pumps and control room alarms for high water level. Plant condition reporting is used to determine root cause and extent of condition where deemed necessary and would be the mechanism for determining the need for, and extent of, any increased cable monitoring.
In consideration of industry operating experience associated with GL 2007-01, and plant specific operating experience, NPPD will expand the scope of the LRA B. 1.25 (Non-EQ Inaccessible Medium-Voltage Cable) to include in-scope inaccessible low-voltage power cables. The parameters monitored or inspected, as required by the program, are changed to include in-scope inaccessible low-voltage power cables. The in-scope inaccessible low-voltage power cables will be tested for degradation of the cable insulation at least once every 10 years. The inspections for water in manholes containing in-scope inaccessible low-voltage power cables will be performed at least once every two years.
A proven, commercially available test will be used for detecting deterioration due to wetting of the insulation system for all in-scope inaccessible low-voltage power cables (480 V to 2 kV).
In addition, LRA Sections A. 1.1.25 (Non-EQ Inaccessible Medium-Voltage Cable Program) and B. 1.25 (Non-EQ Inaccessible Medium-Voltage Cable) are revised to delete the criterion of "exposure to significant voltage" (system voltage for more than 25% of the time) associated with in-scope inaccessible medium-voltage cable.
Corresponding changes to the LRA are shown in Attachment 2 (Changes 1 and 2).
NLS2010079 Page 1 of 3 Attachment 2 Changes to the License Renewal Application Cooper Nuclear Station, Docket No. 50-298, DPR-46 This attachment provides changes to the License Renewal Application (LRA) that conform to the Request for Additional Information (RAI) response in Attachment 1. The changes are presented in underline/strikeout format.
- 1. LRA Section A. 1.1.25, "Non-EQ Inaccessible Medium-Voltage Cable Program," is revised to read:
"Non-EQ Inaccessible Medium-Voltage Cable Program The Non-EQ Inaccessible Medium-Voltage Cable Program is a new program that inspects the following underg*rui in-scope inaccessible low-voltage and medium-voltage power cables.
- iaccssilemediumf voltagc cables between the station sen'ice water-pumps (SWP 1A, 1B, 1*C, and 1D) and the 4.16 k,. safety switchgea
- i*nacce;ible mAedium voltage cables between 12.5 W ever-head loop and the fire pump moiter- (FP M4OT E-)
- ~inccsible mnediuim voltage cables between the standby diesel (DG1 anad DG2) to the 4.16 k:% safety busses (IF and 1G)
- inccesible mediumff voltage cables between the 4.16 kW non safety buses (1A and iB) and the 161 WM contr-el house power-t-ransformers (located in the 345 kW sitehyafd)
The Non-EQ Inaccessible Medium-Voltage Cable Program entails periodic inspections for water collection in cable manholes and periodic testing of cables. In-scope medium-voltage cables (cables with operating voltage from 2 kV to 35 kV) exposed to significant moisture and vl--tage will be tested at least once every ten years to .provide an indication of the condition of the conductor insulation. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g., cable in standing water).
Periodic exposures to moisture that lasts less than a few days (i.e., normal rain and drain) are not significant. Signifieafn voltage exposure is defined as being su.bjected to sstem veltage for- moere than twenty five percent of the time.
The program includes Inspections for water accumulation in manholes containing in-scope inaccessible low-voltage and medium-voltage power cables will be performed at least once every two years.
In-scope inaccessible low-voltage power cables (cables with operating voltage from 480 V to 2 kV) that are subject to aging management review are included in this program.
The in-scope inaccessible low-voltage power cables will be tested for degradation of the
NLS2010079 Page 2 of 3 cable insulation prior to the period of extended operation and at least once every 10 years thereafter. A proven, commercially available test will be used for detecting deterioration due to wetting of the insulation system for all in-scope inaccessible low-voltage power cables (480 V to 2 kV).
This program will be implemented prior to the period of extended operation. This new program will be implemented consistent with the corresponding program described in NUREG-1 801 Section XI.E3, Inaccessible Medium-Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, prior to the peri.d extended .f operation."
- 2. LRA Section B. 1.25, "Non-EQ Inaccessible Medium Voltage Cables," is revised to read':
"B.1.25 Non-EQ Inaccessible Medium-Voltage Cable Program Description The Non-EQ Inaccessible Medium-Voltage Cable Program is a new program that inspects the following under-gr*u* in-scope inaccessible low-voltage and medium-voltage power cables.
T inaEessible medium voltage ables between the station sentice water- pumps (SWP oA, 1B, 1 , and 1D) and the 4.16 kV safety switchgear Inacpessiblcmediumvm veltageecables bitween 12.5 kV overhead lfop and the fire pump motor- (FP MOT B) poindesnible mneditium vltage ablnditione theond tandby diesel (iG! and DG2) te the 1.16 kV safety busses (IF anid i G)
The Non-EQ Inaccessible Medium-Voltage Cable Program entails periodic inspections for water collection in cable manholes and periodic testing of in-scope inaccessible power cables.
In-scope medium-voltage cables (cables with operating voltage from 2 kV to 35 kV) exposed to significant moisture and v~eltage will be tested at least once every ten years to provide an indication of the condition of the conductor insulation. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g., cable in standing water). Periodic exposures to moisture that lasts less than a few days (i.e.,
normal rain and drain) are not significant. Significant voltage exposure is define being subjected to system voltage for more than twenty five per""ent of the time.
This LRA Section was previously revised in NLS2009040 (ADAMS Accession Number ML091690050).
NLS2010079 Page 3 of 3 The program includes Inspections for water accumulation in manholes containing in-scope inaccessible low-voltage and medium-voltage power cables will be performed at least once every two years.
In-scope inaccessible low-voltage power cables (cables with operating voltage from 480 V to 2 kV) that are subject to aging management review are included in this program.
The in-scope inaccessible low-voltage power cables will be tested for degradation of the cable insulation prior to the period of extended operation and at least once every 10 years thereafter. A proven, commercially available test will be used for detecting deterioration due to wetting of the insulation system for all in-scope inaccessible low-voltage power cables (480 V to 2 kV).
This program will be implemented prior to the period of extended operation. This new program will be implemented consistent with the corresponding program described in NUREG-1801 Section XI.E3, Inaccessible Medium-Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements.
NUREG-1801 Consistency The program elements for managing the effects of aging on in-scope inaccessible medium-voltage power cables will be consistent with NUREG-1801,Section XI.E3, Inaccessible Medium-Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements.
Exceptions to NUREG-1801 None.
Enhancements Nene This program includes in-scope inaccessible low-voltage power cables (480 V to 2 kV) that are subject to aging management review."
Reference:
Response to RAI B. 1.25-2.
4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4
ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© Correspondence Number: NLS2010079 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE Implement the Non-EQ Inaccessible Medium- NLS2008071-16 January 18, 2014 Voltage Cable Program. [LRA Section B. 1.25] Revision 1 Inspections for water accumulation in manholes containing in-scope inaccessible low-voltage and medium-voltage power cables will be performed at least once every two years.
In-scope inaccessible low-voltage power cables (cables with operating voltage from 480 V to 2 kV) that are subject to aging management review are included in this program. The in-scope inaccessible low-voltage power cables will be tested for degradation of the cable insulation prior to the period of extended operation and at least once every 10 years thereafter. A proven, commercially available test will be used for detecting deterioration due to wetting of the insulation system for all in-scope inaccessible low-voltage power cables (480 V to 2 kV).
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