ML20094H066
| ML20094H066 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/02/1995 |
| From: | Mccollum W DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M92383, NUDOCS 9511130313 | |
| Download: ML20094H066 (5) | |
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thikeH u er Company
. Wlul44f R. h!cCount. Jk Catauba Nuclear Generation Department Vicenaident 48% ConcordRoad (bWjo314.?M Ollice Yor*k. SCTJ745 (8f21831JUifax DUKEPOWER November 2,1995 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555
Subject:
Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 Request for Relief Number 95-03
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Reply to NRC Request for AdditionalInformation (TAC Nos. M92383 and M92384)
Reference:
Letter from Roben E. Manin, NRC to William R. McCollum, Catawba, dated September 25,1995 Gentlemen:
Please find attached our reply to the subject request for additionalinformation. Please note that all of the welds in the nuclear service water (RN) system piping which were the subject of the original request for relief will either have been repaired or the affected piping will have been downgraded to Duke Class F by November 10,1995. Therefore, the subject request for relief will no longer be necessary by ulis date. The enclosed information is being provided to you for information and to assist you in closing out this issue.
Should you have any questions concerning this material, please call L.J. Rudy at (803) 831-3084.
Very truly yours, f
W.R. McCollum
. LJR/s Attachment
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9511130313 951102 PDR ADOCK 05000413 P,
. PDR..
4 Doc'ument Control Desk Page 2 November 2,1995 i
xc (with attachment):
S.D. Ebneter, Regional Administrator Region II RJ. Freudenberger, Senior Resident Inspector R.E. Martin, Senior Project Manager ONRR i
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5 Document Control Desk Page 3 November 2,1995 bxc (with attachment):
Z.L. Taylor L.J. Rudy D.L. Ward J.E. Reeves NCMPA-1 NCEMC PMPA SREC Document Control File 801.01 Group File 801.01 ELL-EC050 I
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REPLY TO NRC REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR RELIEF NUMBER 95-03 1.
The May 11,1995, submittal did not state all pin hole leak locations. It states that there were 75 pin hole leaks and that 39 leaks were repaired. For relief on the other 36 leaks, the locations must be listed, including the unit in which the leaks are located.
Reply The 36 welds were listed in the initial request for relief package; however, Catawba did not clearly identify the specific welds requiring the relief. After the request for relief was sent to the NRC, the decision was made to downgrade 22 of these welds from Duke Class C to Duke Class F (non-nuclear safety). Duke Class F piping is not subject to the requirements of ASME and Generic Letter 90-05. This downgrade included all 4" welds identified on the original request. Additionally, during this review, it was found that one of the welds was inadvertently listed twice. This leaves a balance of 13 welds that should have been addressed separately in the May 11,1995 submittal. This request should have also clearly stated that the relief period needed for these welds was between May 11, 1995 and November 10,1995. By November 10,1995, all of the 75 welds listed in the request for relief will have been repaired, replaced, or downgraded. These 13 welds are located on the radiation monitor piping in the auxiliary building. The following is a list of the 13 welds: 1RN 531-9, IRN 531-6,1RN 423-80,1RN 527-3,1R.N 527-4, IRN 526-3,2RN 445-1,2RN 445-5,2RN 439-23,2RN 439-17,2RN 439-19,2RN 442-7, and 2kN 443-11.
2.
Clarify repair plan schedules. Will the repairs in Unit I be performed at the same time as those in Unit 2?
Benly Request for Relief Number 95-03 should have stated that all 75 welds (this includes welds for Units 1 and 2) would be repaired, replaced, or downgraded prior to the end of the next outage, which is Unit 2 End-of-Cycle (EOC) 7, which ends in November of 1995.
3.
Provide plans to mitigate further MIC attack. Has Generic Letter 89-13,
" Service Water System Problems Affecting Safety-Related Equipment" been fully implemented?
Reply Programs are presently being developed at Catawba to mitigate MIC attack within the RN piping systems. MIC was not detected in these systems until May of 1995. Prior to that date, all current sample data did not support the presence of MIC. By letters dated
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t January 26,1990, September 12,1990, October 20,1993, and September 29,1994, Duke Power Company provided updates to the status and schedule for implementation of all activities associated with the subject generic letter. Accordingly, as of January 1,1995, Catawba had completed implementation of this generic letter.
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4.
Since socket welds are generally not amenable to volumetric NDE, it is not clear how the flaw size assumptions used in the LEFM calculations are supported. Please clarify.
Reply Since volumetric NDE is ineffective in flaw characterization of the socket welds, a sampling of the 2" socket weld fittings was sanctioned and flaw size was characterized by the Duke Power Company Metallurgy Lab. Reference Attachment 3, CNS Stainless Steel RN Piping - Flaw Sizing Addendum to Metallurgy Report #1812 in the request for relief.
This evaluation is a description of eight socket welds with the most severe MIC attack sites, followed by a generalization of the typical form in each type of weld.
5.
Ifas additional non-destructive evaluation to assess the overall system integrity been considered or performed?
Reply Yes, since the volumetric NDE is shown to be ineffective in flaw characterization of the MIC attack of butt and socket welds. Radiography was considered and a sampling of 4" j
butt weld fittings were radiographed (RT) under ideal laboratory conditions and the j
results were determined to be insufficient for flaw sizing for this application as well.
l Until an acceptable NDE method is developed, Catawba will continue a periodic visual inspection / repair / replacement program. This program will continue until other corrective measures are approved to mitigate the MIC problem.
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