ML19211C728

LER 79-130/03L-0:on 791227,insufficient Clearance Discovered Between RCS Hot Leg & Pipe Whip Restraint Shims.Caused by Bechtel Design Error.Pipe Whip Restraints Modified

ML19211C728
Person / Time
Site:	Davis Besse
Issue date:	01/08/1980
From:	TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19211C727	List: ML19211C726 ML19211C728
References
LER-79-130-03L, LER-79-130-3L, NUDOCS 8001140320
Download: ML19211C728 (2)

Text

lU. S. NUCLE AR HEGUL ATORY CO*.1 MISSION

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CON'T'4 75 htpOa1 D ATE 80:o i M 63 EVENT 0 ATE 0)61 COCK ET NU'.'UE R 8 EVENT DESCRIPTION A ND PROB ABLE CONSECUENCES h lOn December 21, 1979, it was discovered that there was insufficient clearance between j

o 2[the Reactor Coolant System (RCS) hot leg and some of the shims of the pipe whip res-o 3 ltraints. On December 27, 1979, it was determined that this was in conflict with an j to-that there be no contact betweentheRCy lassumption of the RCS piping seismic analysis, io s This became immediately reportable under T.S. j 0 6 l hot leg piping and the whip restraints.

There was no danger o the health and safety of the public or station per-l l6.9.1.8.h.

O 7;sonnel. These restraints do not affect normal operation.(NP-32-79-14) lro a CO*.'P.VALVE S Y S T Gt CAUSE CAUSE CCLE CODE SU8 CODE CO'*PONENT CODE SU't CO D E SUSCODE R l T l@ l X @ lZl@

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i o discovered by TECo personnel while performing RCS hot leg RTD modification work.

Undet ,[ Facility Change Request 79-441, Supplement 1, pipe wr.ip restraints R1 and R4 were ljij7j R3 had the shim completely removed.

jl modified by removing shin packs from the shins.

, 3 29, 1979.ll The work was completed by 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on December 80 i 4 7 8 9 DISCOVERY DESCRIPTION

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, IDENTIFICATION OF OCCURRENCE: A conflict between an assumption in the Reactor Coolant System (RCS) piping seismic analysis and some pipe whip restraints Conditions Prior to Occurrence: On December 21, 1979, while performing modifica-tion work on the RCS hotleg, it was discovered there was no clearcnce between the On December 27, 1979, hot leg and some of the shims of the pipe whip restraints.

it was determined that this was in conflict-with the RCS piping seismic analysis assumptions,that there would be no contact between the hot leg piping and the pipe whip restrainta during a seicnic event. This became tenediately reportable under Technical Specification 6.9.1.8.h as a condition which conflicts with an assump-tion of an accident analysis.

Being in cold shutdown (Mode 5), the unit remained down until corrections were made.

Designation of Apparent Cause of Occurrence: The cause of the occurrence was an architectural design error by Bachtel. These errors were discovered while perform-ing RCS hot leg resistance temperature detector (RT3) modification work. .These original design errors were random and not due to any general deficiency in the original design method.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. These whip restraints are not required for normal system performance.

Corrective Action: Under Facility Change Request 79-441, Supplement 1, pipe whip R3 was restraints R1 and R4 were modified by removing shim packs from the shims.

modified by removing the shim completely. All affected whip restraint modifications were completed by 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on December 29, 1979, prior to returning the unit to operation.

Failure Data: There were no previously reported conflicts between the pipe whip restraints and the assumptions of the seismic analysis.

LER #79-130 1738 027.