ML20009A953

Final Deficiency Rept Re Lock Overstress Condition of Pipe Bearing on Flat Plate,Initially Reported on 810309.Four Supports W/Design Deficiencies Have Been Redesigned & Reissued for Const.New Design Criteria Issued

ML20009A953
Person / Time
Site:	Columbia
Issue date:	06/26/1981
From:	Matlock R WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, G2-81-157, GO2-81-0157, GO2-81-157, NUDOCS 8107140540
Download: ML20009A953 (2)

Text

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y'* 50.55(e) Report Dockmt No. 50-397 Washington Public Power Supply System P.O. Box 968 3000 GeorgeWashingtonWay Richland, Washington 99352 (509)372-5000 JLne 26,1981 G02-81 -0157 Docket No. 50-397 Mr. R. H. Engelken, Director -y W N

U.S. Nuclear Regulatory Commission Region V PIN N Suite 202, Walnut Creek Plaza /b' /d j]

d) 7-1990 North California Blvd. f -

Walnut Creek, CA 94596

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Dear Mr. Engelken:

'W NMM 9

Subject:

SUPPLY SYSTEM NUCLEAR PROJECT N0. 2 V

• ci REPORTABLE DEFICIENCY -10CFR50.55(e)

LOCAL OVERSTRESS CONDITION OF PIPE BEARING ON FLAT PLATE In accordance with the guidelines for the reporting of 10CFR50.55(e) conditions your staff was informed on March 9,1981, of a potentially reportable condition regarding local overstress condition on pipe bearing on flat plate. An interim report describing the deficiency and our approach to the resolution was submitted per G02-81-76, dated April 10, 1981. The WNP-2 project has completed its evaluation and has determined this condition to be reportable under the provisions of 10CFR50_.55(e).

Attached is our report on this deficien::y. Please contact us if you have additional questions.

Very truly yours,

/ Program Director, WNP-2 TAS:dm cc: WS Chin -BPA ND Lewis -EFSEC, Olympia TA Mangelsdorf-Bechtel-954K RE Snaith -B&R NY AD Toth -NRC Resident Inspector JJ Verderber-B&R NY A. S-hwencer-NRC WNP-;?-FILES

/f6 8107140540 010626 64 PDR ADOCK 00000397 S PDR B l - 13 3. j

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f FINAL REPORT REPORTABLE DEFICIENCY AND CORRECTIVE ACTION WPPSS NUCLEAR PROJECT NO. 2 POSSIBLE LOCAL OVERSTRESS CONDITION OF PIPE BEARING ON FLAT PLATE WASHINGTON PUBLIC POWER SUPPLY SYSTEM DOCKET NO. 50-397 LICENSE.N0. CPPR-93 Nature of Deficiency Piping reaction forces on pipe support RHR-127 were originally identified as being distributed into the pipe over a relatively small contact surface.

Formulas for stress in thin-walled cylinders bearing on a flat surface re-sult in line contact with the piping, exceeding ASME Code allowable stresses.

Safety Significance If this type of deficiency were to remain uncorrected, ASME Code allowable' stresses could be exceeded during faulted conditions. The potential failure could adversely affect the safe operation of the plant.

Corrective Action (1) Initially a finite element analysis was run on a segment of pipe at support RHR-127; the results were found unacceptable due to stress levels. Pipe stress levels obtained by finite element analysis have been reviewed for other cases and found acceptable for pipes smaller than 14".

(2) A comprehensive field walk was completed which identified 119 similar type pipe supports at WNP-2. This list was reduced to 15 pipe supports requiring further investigation. All 15 pipe supports were ASME III/2, III/3, or B31.1 and were analyzed by finite element analysis. No support of this type of condition exists en any ASME Section III Class I Systems.

(3) An ANSYS finite element analysis was performed on the 15 supports of which four(4)weredeterminedtohavedesigndeficiencies. These have since been redesigned and reissued for construction. Design criteria have t,een issued governing the design of fcture hangers, to ensure that this potent hi design deficiency will not be repeated.

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