ML19256G053

LER 79-017/01T-1:on 791108,size of Support Bolting for Rigid Anchor DHH-127 Was Found to Be Inadequate in Design & Installation.Caused by Bolts Being 5/8-inch in Diameter, Contrary to 3/4-inch Design Requirement

ML19256G053
Person / Time
Site:	Three Mile Island
Issue date:	12/11/1979
From:	Mitchell D METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19256G050	List: ML19256G049 ML19256G053
References
LER-79-017-01T, LER-79-17-1T, NUDOCS 7912270328
Download: ML19256G053 (2)

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F S 60 St OOCKET NVMEgm et EVENT DESCRIPTION ANo PAC 8ASLE CONSEQUENC2$ h o 2 i During inspections required by I E. Bulletin 79-1k, the. sine of the surrert Eoltint g ; for rigid anchor DEE-127A was found to be inadequate in Ecth_ design and l

, ,, ; installation.

Under seismic conditions, the affected decar heat removal cooling o 3  ;

piping may exceed code allevable stresses. This is reportable by T.S. 6.9 2.A(ob l o i ,5  ; This condition was discovered by the architect enrineer while the riant was in s .

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December 11, 1979 GQL 1526 IJ2 79-017/01-T-1 ,

Discoverv Descrittia; U2) performing special inspection.

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SUPPLEMENTARY ATTACEMENT TO LER 79-olT/01-T-1 During inspections required by I.E.Bulletin 79-14, the size of the support bolti. g for rigid anchor DHH-127A vas found to be inadequate in both design and installation. The bolts found during the inspection vere 5/8 inch -

diameter contrary to the 3/h inch dia=eter specified in the design require-ment. Further evaluation revealed that the 3/h inch dia=eter bolts vould have provided a safety =argin less than 1. This condition was discovered by the architect engineer while performing the inspections / evaluations required by I.E. Bulletin 79-lh. Load data sheets for each safety related anchor requiring for=al analysis were provided by the architect engineer to the prime component supplier. The prime component supplier, in turn, designed the required rigid anchors. Per the architect engineer, the prime co=ponent supplied rigid anchor DHH-127A does not meet the load require-

=ents for the loads that vere issued for its design.

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The error vent undetected and appears to be generic. The =istake affects all rigid anchors in the plant which are safety related and which previously required a for-a' analysis. Each of these rigid anchors is to be inspected and evaluated.

Although a generic error was =ade, it may be determined in so=e cases , after considering the algebraic su= nation of all loads at a particular point ,

that an existing rigid anchor is acceptable in that a mini =u= safety

=nrgin of one (1) is available.

Since the initial discovery, two out of seven rigid anchors inspected and evaluated vere fouci to be deficient. Rigid anchor's found deficient were SPSH-3 and SPSE-9 Probable consequences as a result of SPSH-3 and SPSH-9 being found deficient are that under seis=ic conditions, the affected building spray piping =ay exceed code allovable stresses.

In lieu of individual reports , a co=plete listing of all rigid anchors found deficient vill appear in the report of findings, at the completion of the inspections required by I.E. Bulletin 79-lh. All rigid anchors are to be upgraded to a safety =argin of five (5) prior to restart. Upgrading is to consist of a redesign and rework of the rigid anchors by the architect engineer.

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