TXX-6315, Interim Deficiency Rept CP-86-73 Re ASME Snubber Attachment Brackets W/Potential to Restrict Movement or Bind Snubbers. Initially Reported on 861020.Brackets Replaced.Next Rept Will Be Submitted by 870612

Interim Deficiency Rept CP-86-73 Re ASME Snubber Attachment Brackets W/Potential to Restrict Movement or Bind Snubbers. Initially Reported on 861020.Brackets Replaced.Next Rept Will Be Submitted by 870612

ML20204H052
Person / Time
Site:	Comanche Peak
Issue date:	03/20/1987
From:	Counsil W, Keeley G TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CP-86-73, TXX-6315, NUDOCS 8703260534
Download: ML20204H052 (3)

Text

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E Log # TXX-6315 File # 10110

._ C 903.9 r C Ref # 10CFR50.55(e) 1UELECTRIC 2,Ud"""",a,,, March 20, 1987 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50-445 AND 50-446 ASME SNUBBER ATTACHMENT BRACKETS SDAR: CP-86-73 (INTERIM REPORT)

Gentlemen:

On October 20, 1986, we verbally notified your Mr. Ian Barnes of a deficiency involving installation of ASME snubber attachment brackets. Our last interim report was logged TXX-6188, dated December 23, 1986. On March 6, 1987, we requested and received a two week extension until March 20, 1987, to provide our next report. We have concluded that this issue is reportable under the provisions of 10CFR50.55(e), and the required information follows:

DESCRIPTION OF PROBLEM A drawing review of all ASME snubbers was conducted to verify the adequacy of swing clearances. 1063 snubbers were identified as having attachment brackets with attributes that could potentially result in restricted movement and/or binding of the snubbers. As a result of field examinations, this number was reduced to 165.

An evaluation of the 165 supports was conducted in which the predicted pipe movements were compared to the field verified swing angle data.

A summary of the evaluation results follows:

- 83 supports were determined to have sufficient field verified swing an'gle to accommodate the predicted pipe movement.

- 15 supports were determined to be unnecessary in a previously initiated pipe support requalification effort and are being deleted.

- 30 supports are being modified as a result of the pipe support requalification effort (but not as a result of this deficiency).

- 16 supports have been identified as having less clearance than required by analysis and are being modified to correct the situation.

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TXX-6315 March 20, 1987 Page 2 of 3

- 3 supports have no safety related function nor impair the safety related function of other components and are therefore being removed from further evaluation.

- 18 supports are under further evaluation.

Several causes for the deficiencies have been identified.

1. Certain sizes of struts and snubbers may use interchangeable rear attachment brackets. These rear attachment brackets were kept mixed in the same bulk storage bin. Although this practice was considered acceptable for rear bracket types XRB-06 and XRB-08, it may have been unacceptable when strut rear attachment brackets of a later edition (SRRB-06 and SRRB-08) were used with the corresponding size snubber.

2. Theforwardbracketsforsize3(SMF)snubbersthatarefabricategatthe minimum specified "c-c" dimension do not have the full required 5 swing when pinned to a rear ~ bracket.

3. Size 10 snubbers, depending on which revision of rear bracket was used and wgichfabricationtoleranceswereemployed,maynothavethefullrequired 5 swing.

SAFETY IMPLICATION i

j The supports deleted or modified by the requalification effort are not being analyzed in their origini ccnfiguration to determine the safety significance (as this is neither practical cr useful). Rather, it is conservatively assumed that these supports, the supports yet to be analyzed, and the supports being modified

as a result of this deficiency, may have had inadequate swing clearances l sufficient to impair their ability to perform their required safety function, i

i CORRECTIVE ACTION To prevent recurrence of deficiency 1, the bulk storage bins have been purged of all SRRB-06 and SRRB-08 strut rear attachment brackets. Additionally, future shipments of rear attachment brackets of these sizes will consist only of the XRB type.

Corrective actions to prevent racurrence of deficiencies 2 and 3, are still under review and will be provided in our next submittal.

As previously noted,16 supports are being modified as a result of this deficiency. The evaluation of the remaining 18 supports is scheduled for completion by May 15, 1987.

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r TXX-6315 March 20, 1987 Page 3 of 3 We will submit our 6 ext report no later than June 12, 1987.

Very truly yours, W. G. Counsil By: , -

E. S. Keeley e >

Manager, Nuclear Lice ng BSD:lw c- Mr. E. H. Johnson, Region IV Mr. D. L. Kelley, RI - Region IV Mr. H. S. Phillips, RI - Region IV

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