TXX-6044, Interim Deficiency Rept CP-86-36 Re Large Bore Piping Supports.Initially Reported on 860609.Scope Revised to Delete Small Bore ASME Class 2 & 3 Piping to Provide More Accurate Results.Next Rept Will Be Submitted by 861201

Interim Deficiency Rept CP-86-36 Re Large Bore Piping Supports.Initially Reported on 860609.Scope Revised to Delete Small Bore ASME Class 2 & 3 Piping to Provide More Accurate Results.Next Rept Will Be Submitted by 861201

ML20197B346
Person / Time
Site:	Comanche Peak
Issue date:	10/17/1986
From:	Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
CP-86-36, TXX-6044, NUDOCS 8610280378
Download: ML20197B346 (3)

Text

. l Log # TXX-6044 o File # 10110 903.9 TEXAS UTILITIES GENERATING COMPANY SKYWAY TOWER 400 NORTH OLIVE STREET, I.B. 81. DALLAS. TEXAS 75301 October 17, 1986

)

M E".iff.U E Mr. Eric H. Johnson, Director 40E'p1Rl >I Division of Reactor Safety and Projects  :

U. S. Nuclear Regulatory Commission j OCT 2 I g 611 Ryan P1aza Drive, Suite 1000 Arlington, TX 76012 d [; h' lt n;

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50-445 AND 50-446 LARGE BORE PIPING AND SUPPORTS SDAR: CP-86-36 (INTERIM REPORT)

Dear Mr. Johnson:

On June 9,1986, we notified you of a reportable item involving the scope of plant modifications resulting from the project's pipe support reverification program (see TXX-4844). This is a follow-up interim report on a reportable item under the provision of 10CFR50.55(e). We have submitted interim reports logged TXX-4958 and TXX-5033, dated August 13, 1986, and September 26, 1986, respectively.

In order to provide more accurate results and scheduling information, the scope of this issue has been revised to delete small . bore (2" and less) ASME Class 2 and 3 piping and supports that are not part of the large bore or Class 1 stress problems. An additional reportable item - identified as SDAR CP 72, Small Pore Piping and Supports, - has been issued to encompass these scope deletions (see TXX-6042).

The continuing engineering evaluation for large bore piping and supports has identified the following additional instances which are considered reportable pursuant to 10CFR50.55(e). These instances are within modification category 4

" Cumulative Effects" and are further defined as follows:

1. Fluid Transients:

Original design activities considered the effects of fluid transients in only three systems. During the requalification program, additional systems have been identified and analyzed wherein the effects of fluid transients have resulted in increased pipe support loads. Modifications of these supports will be required.

2. Support Stability:

Original design recirements for specific support types did not include adequate provisions to assure support stability.

Specifically, measures were not provided to preclude axial movement or rotation of the piping to an " unqualified position". An l " unqualified position" results from movement or drifting of the

support to a position other than that assumed in the piping stress analysis.

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.- TXX-6044 October 17, 1986 Page 2 of 2 Specific support types affected by this condition include:

a) "Zero" clearance box frames supported by struts, b) Long column-strut supports, and c) U-bolts on single struts or snubbers exhibiting overstress.

3. General Cumulative Effects:

During the requalification program, all stress problems and supports have been scheduled for re-analysis and evaluation. Pipe support modifications have been required as a result of the cumulative effects of the multiple design issues. Multiple iterations would be required to isolate the effects of any specific design attribute.

These iterations are costly and-therefore will not be performed.

Specific issues contributing to these cumulative effects can be categorized as follows.

a) Generic stiffness b) Axial rotational restraints c) Support mass d) Mass point spacing e) High frequency mass participation f) Fluid transients g) Support load increases due to support optimization.

The attached list shows the support modifications initiated to date. The evaluation of this issue is continuing. We anticipate submitting our next report by December 1, 1986.

Very truly yours, t%'T W. G. Counsil JCH/amb Attachment c - NRC Region IV (0 + 1 copy)

Director, Inspection & Enforcement (15 copies)

U. S. Nuclear Regulatory Commission Wrshington, D.C. 20555

_ - . _ . . =.

TXX-6044 October 17, 1986 Page 1 of 1 ATTACHMENT LARGE BORE PIPE SUPPORT MODIFICATIONS Number of Small Bore Mnit Cateaory Modificatiens Deletions

• 1 Prudent 865 26 Recent Industry Practice 1041 56 Adjustment 97 33 Cumulative Effects 470 32 2 Prudent 1272 4 Recent Industry Practice 253 14 Adjustment 90 10 Cumulative Effects 328 74

• These modification quantities have been subtracted from earlier report totals as a result of the revised scope of this SDAR. These small bore modifications quantities will now be reported and updated in SDAR CP-86-72.

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