ML20133C849

Responds to RAI Re Rev 4.1 to Second 10-yr ISI Program

ML20133C849
Person / Time
Site:	Cooper
Issue date:	12/31/1996
From:	Graham P NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NLS960233, TAC-M95833, NUDOCS 9701080112
Download: ML20133C849 (6)

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NLS960233 December 31,1996 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Response to Request for Additional Information Regarding Revision 4.1 to the Second 10-Year Interval Inservice inspection Program (TAC No. .M95833)

Cooper Nuclear Station, NRC Docket 50-298, DPR-46

References:

1. Letter to NRC Document Control Desk from J. H. Mueller (NPPD) dated June 20,1996," Amendment 4.1 to the Second 10-year 1rterval inservice Inspection Program"

2. Letter to G. R. Ilorn (NPPD) from J. R. IIall (USNRC) dated October 24, 1996," Request for.idditionalInformation Regarding Amendment 4.1 to the Second 10-year Interval inservice luspection Program" Cutlemen:

The purpose of this letter is to provide the additional information regarding Amendment 4.1 to the Second 10-year Interval Insenice Inspection (ISI) Program (Reference 1) for Cooper Nuclear Station, that was requested in your letter of October 24,1996 (Reference 2). The response to your questions is provided ac Attachment I to this letter.

If you have any questions or require any additional infornntion, please contact me.

Sinc; rely, NA ,

Philip D. Graham 3 ,

Vice President - Nuch.ar A, M 'q '

/dnm Attachment 9701000012 961231 PDR ADOCK 05000298 G PDit

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NLS960233 December 31,1996 <

Page 2 of 2 ce; Regional Administrator USNRC - Region IV

Senior Project Manager J USNRC - NRR Project Directorate IV-1 Senior Resident Inspector USNRC Michael T. Anderson INEL Research Center NPG Distribution 1

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a Attachment 1 to NLS960233 Page1of3 i i

l ATTACllMENT 1 REQUEST FOR ADDITIONAL INFORMATION NRC Request 1. ,

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In the amended second 10-year interval ISI program plan, the Nebraska Public Power District (NPPD) provided an adjusted weld examination list. From this list, it is not

apparent what adjustments have been made. Provide a summary of adjustments and the l basis for the changes. It should be noted that examinations performed during successive j intervals should be performed on the same examination areas. Verify that the successive examination requirements of the Code (IWB-2420 and IWC-2420) have been satisfied.

NPPD Response l The following table summarizes the changes to the examination tables made in l Amendment 4.1. The adjustments were primarily editorial, i.e. adding references to relief requests, deleting welds that do not exist. In the case of the Category B-J welds in the NBl system, the schedule was adjusted to renect the examinations that were performed. I Since none of these welds were examined during the Erst 10-year interval, IWB-2420 does not apply. l

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l I Changes to Examination Tables l ISI Catenory Pace Nos. Description of Change

. Category B-A All Added Relief Request RI-06 Rev. 2 l I Category B-D All Added Relief Request RI-21 l Category B-F NBI Added Relief Request RI-20 Category B-J MS Deleted weld MSD BJ-51, neld examination f detennined that weld reputed to be on the Main Steam l system does not exist. l Category B-J NBl Revised examination schedule 1

Category C-F RCIC Added Relief Request RI-23 l Category C-G All Deleted welds PNC-CG-20A/B and PNC-CG-23A/B, Held examination determined that there are no welds present on the 20 inch valves.

Category D-A SW & Deleted welds, Geld examination determined that there REC are no integral attachment welds present on the SW Booster numns or REC numns.

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L 4 Attachment I

! to NLS960233 Page 2 of 3 I

NRC Request 2.

i Relief Request Number RI-06, Revision 2, appears to be an end ofinterval relief request for reactor vessel weld examinations. It is unclear whether the information provided is based on actual examinations performed in accordance with Code requirements. If so, NPPD must submit information on the percentage of coverage obtained for each weld, discuss the limiting factors, and provide a basis for the acceptability for the coverages obtained. Discuss the approach used to maximize coverage of the Code-required examination volume (outside and inside vessel examinations). l NPPD Response l

l RI-06, Revision 0, was previously approved by the NRC and remains valid for the second interval. RI-06. Revision 2, added access restrictions for the bottom head circumferential weld and the shell to flange circumferential weld. These access restrictions were identified during the examinations performed in the Fall 1995 Refueling outage. 1 Access to bottom head circumferential weld HMC-BB-1 is limited due to the proximity of the vessel skirt. The configuration limits scanning with the 60 probe. The total composite coverage is approximately 86%. This weld is not accessible from the vessel inner diameter.  :

Access to the shell to flange circumferential weld VCB BC-5-1, -2, & -3, is limited due to the flange to shell configuration and the proximity of the vessel thermocouples. The configuration limits scanning from the outer diameter with the 0*,45 , and 60 probes.

The thermocouples limit scanning with both the 45" and 60 probes. The drain channel in the flange surface and the presence of the bolt holes precludes a meaningful examination from the flange surface. Due to the slad internal surface of the reactor l vessel, the centerline of the weld could not be reliably located from the inner diameter.

Thus a meaningful supplemental examination of the restricted areas could not be performed. The total composite coverage is approximately 74%.

NRC Request 3.

In Request for Relief RI-21, Rev. O, NPPD included the Control Rod Drive Return Nozzle Inner Radius. However, the basis only discusses limitations associated with nozzle-to-shell welds. Provide clarification for the subject request for relief relative to inner radius examinations performed on the subject nozzles. Discuss the percent of coverage for the CRD nozzle inner radius and the limiting factors.

,. Attachment 1 to NLS960233

' Page 3 of 3 NPPD Response Request for Relief RI-21, Rev. O, Code Item B3.100, Nozzle Inner Radius, applies to the Inner Radius of the CRD Return Nozzle, N9. It does not apply to any of the other nozzles listed. Only 70% of the CRD Return Line Nozzle Inner Radius was examined as indicated in the relief request. The size of the nozzle, its configuration, and the proximity of the insulation support frame restricted access with the 60 and 70 scans. The 70%

represents the total composite coverage. The extent of coverage for individual scans is ,

documented in the examination record. Examination results were independently I reviewed by a UT Level III and by the Authorized Nuclear Inservice inspector.

NRC Request 4.

For Request for Relief RI-23, NPPD has requested relief from Code examination requirements associated with three RCIC welds in the Torus. Provide the basis for the code classification of the subject welds on the strainer, when the subject welds are in the torus.

NPPD Response Request for Relief RI-23 applies to three submerged welds on the alternate suction supply piping for the Reactor Core Isolation Cooling system (RCIC). The RCIC system functions to provide cooling water if the reactor becomes isolated from the main condenser. Although the RCIC system does not provide a RIIR, ECC, or CIIR function, NPPD has conservatively classified the RCIC suction piping as ASME Class 2 for inservice inspection. Ilowever, this section of piping is exempt from volumetric and i surface examination per IWC-1220(b). Therefore, NPPD withdraws Request for Relief l RI-23.

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4 h ATTACHMENT 3 LIST OF NRC COMMITMENTS l

Correspondence No: NLS960233 i

The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's information 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.

t COMMITTED DATE COMMITMENT OR OUTAGE None  !^

4 l PROCEDURE NUMBER 0.42 l REVISION NUMBER 1.2 l PAGE 8 OF 10 l