ML19318D223

Revised LER 80-004/01T-1:on 800306,errors Found in Seismic Analysis of Common Decay Heat Suction Piping Associated W/ Valves DH-V1 & DH-V2.Seismic Analysis Corrected & Mods Made to DH-V2.Mods to DH-V1 to Be Completed by 801015

ML19318D223
Person / Time
Site:	Three Mile Island
Issue date:	07/03/1980
From:	Mitchell D METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19318D221	List: ML19318D220 ML19318D223
References
LER-80-004-01T, LER-80-4-1T, NUDOCS 8007080214
Download: ML19318D223 (2)

Text

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EVENT oEsca PTION ANO PROSAS CON t ENCES

,o;2; l niiring pipir.:', reanalysis, errors were d Escovered in the scismic analysis of the t g ; common decay heat suct' ion piping associated with DH-V1 and DH-V2. When subicceed ]

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,,,o,lThe cause of this event is analysis error. The afrected piping seismic analysis been corrected and appropriate hardware changes to Dil-V2 were completed and I m1 h:is m Ithe modifications to DH-V1 will be completed hv 10-15-80.

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. Attachment 2 TLL 313 NARRATIVE REPORT LER 80-004/0lT-1

1. Explanation of Occurrence While performing piping reanalysis of non-conformance identified by inspect ions required by NRC IE ilul letin 79-14, errors were discovered by the Architect-Engineer in the seismic analysis of the common decay heat suc* ion piping associated with valves DH-V1 and DH-V2. Specifically, an incorrect center of gravity was assumed for valves and their motor operators.

When subjected to Operating liasis Earthquake loads, the piping associated with l valves DH-V1 and DH-V2 may exceed Code allowabic stresses as a result of insuffielent restraint provided by the original design. This event is considered reportabic per Technical Speelfication 6.9.2.A (9).

II. Cause of_ Occurrence The cause of this occurrence is classified as a design / analysis error in that an incorrect valve center of gravity was selected as input data for the piping seismic analysis.

Ill. Circumstances Surrounding Occurrence This error was discovered by the Architect-Engineer while verifying the conformance of the analysis to the "as-built" piping condition as required by IE Bulletin 79-14.

The plant was in long-term cold shutdown with core cooling being provided by the Decay Heat Removal System taking suction from the Reactor Coolant System through the DH-Vl/DH-V2 suction piping. The initial error was discovered during the evaluation.of DH-V2 piping on 03/06/80. The follow-up anaylsis of DH-V1, which is an identical valve to Dil-V2, discovered similar reportahic conditions on 03/10/80 and, therefore, was not included in the report eclocopied on 03/07/80.

l IV. Corrective Action To Be Taken to Prevent Recurrence l Because the unit is in a cold shutdown mode, no immediate corrective I action is required. Emergency Procedure 1202-35, Loss of Decay Heat I Removal, addressed inoperability of the normal Decay Heat Removal suction piping and provides adequate guidance to the operator for this event. long term corrective action has consisted of correcting the affected piping scismic analysis and appropriate hardware changes are planned. This modification was to be in the form of a mechanical snubber  :

for Dil-Vt. Ilowever, an extremely long procurement time has caused a reevaluation and request for a hydraulic snubber. This has prevented the corrective actions for DH-V1 from being implemented by 6/20/80 as stated in LER 80-004/01-T-0. Therefore, we are revising our date for

, completion of the hardware changes to DH-V1 until 10/15/80.

V. Component Failure Data

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Not _applicabic, as no components have failed. This event report considers potential piping failure.

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