TXX-6025, Final Deficiency Rept CP-86-33 Re Use of Incorrect Pipe Support Stiffness Values in Class 1 Pipe Stress Analyses. Initially Reported on 860429.Evaluation Continuing & Support Mods Will Be Issued as Needed

Final Deficiency Rept CP-86-33 Re Use of Incorrect Pipe Support Stiffness Values in Class 1 Pipe Stress Analyses. Initially Reported on 860429.Evaluation Continuing & Support Mods Will Be Issued as Needed

ML20211F226
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-86-33, TXX-6025, NUDOCS 8610310105
Download: ML20211F226 (2)

Text

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, Log # TXX-6025

• File # 10110 503.9 TEXAS UTILITIES GENERATING COMPANY SKYWAY TOWER . 400 NORTH OLIVE STREET L.B. At . DALLAS. TEXAS 7Mel October 17, 1986 E,Yn" LU?,%

h;. l Mr. Eric H. Johnson, Director 1

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Division of Reactor Safety and Projects l 2 l 1586 f n' U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 LL G

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Arlington, TX 76012

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NO. 50-445 STIFFNESS VALUES FOR CLASS 1 STRESS ANALYSIS SDAR: CP-86-33 (FINAL REPORT)

Dear Mr. Johnson:

On April 29, 1986, we verbally notified your Mr. T. F. Westerman of a deficiency involving the use of incorrect pipe support stiffness values in the Unit 1 Class 1 pipe stress analyses. We have submitted interim reports logged TXX-4831 and TXX-4976, dated May 28, 1986, and August 22, 1986, respectively.

We are reporting this issue under the provisions of 10CFR50.55(e) and the required information follows.

DESCRIPTION As identified during the CPSES pipe support requalification effort, incorrect stiffness values were used in the Unit 1 Class I piping stress analyses.

Review of the ongoing requalification program has indicated that approximately 30% of the existing pipe supports are overstressed or require modification primarily due to load increases. The factors contributing to increased support loads include support optimization, revised damping values, trapeze modifications, and possibly stiffness.

As a result of these conditions, all stress proMoms are currently scheduled for reanalysis. The recalculation of a stresi, uah .is to specifically isolate the effects of stiffness or any ottar aty 2 ite would require multiple iterations. These iterations are costly anc unprocx.tive, and therefore will not be performed.

SAFETY IMPLICATIONS In the event the deficiency had remained undetected, the integrity of the Class 1 piping and supports could not be assured during normal operating or accident conditions.

8610310105 861017 PDR ADOCK 05000445 S PDR 4 ,,,,,sm o, rms mur,,, m,cr.,c am,,m.

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TXX-6025 October 17, 1986 Page 2 CORRECTIVE ACTION This evaluation is continuing and support modifications will be issued as required to alleviate all unacceptable conditions. The status of support a modifications is being reported under 10CFR50.55(e) via SDARs CP-86-36, CP 63, and CP-86-72.

Very truly yours, THb

, W. G. Counsil JCH/amb c - NRC Region IV (0 + 1 copy)

Director, Inspection & Enforcement (15 copies)

U. S. Nuclear Regulatory Commission Washington, D. C. 20555 s

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