ML19294A528

RO 78-100 on 780803:rept Submitted Re Deficiency in Seismic Analysis of Reactor Vessel Insulation.Mod Made,But Was Not Seismically Analyzed

ML19294A528
Person / Time
Site:	North Anna
Issue date:	11/14/1978
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
References
NUDOCS 7812070271
Download: ML19294A528 (1)

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Virginia Electric and Power Company A g. 4$

North Anna Pcwer Station Unit il 3 @ 9 I Docket No. 50-338 Report No. LER 78-100 Event Date 11-8-78 Report Date 11-09-78 On August 3.1978, a report was taade under the provisions of 10 CFR 50.55 (e) concerning a deficiency in seismic analysis of the react insulation for North Anna Unit 2. Unit 2 on August 8.1978 which encompassed part 21 reporting requirvents for Unit No. 1. A field modification was made to the insulation of the in-core instru mentation cozzles, but the nodification was not seismically analyzed. An investigation was performed and it was found that 2 to 6 incere It instrumentation tubes may yield in the worse case of a seisnic event. was also found that no Further tubes will rupture; therefore, the safety of the plant is not endangered. will be forwarded in a later report. There is no effect upon the safe operation of the plant at this time and power production will continue. Modifications to the insulation supports will be installed at the next refueling at North Anna Unf- 1 in order to rneet the seismic criteria. 7 8 3 9 0 7 9 p g,}}