ML20128Q225

Forwards Draft Rept Re Unisolated LOCAs Outside of Drywell in Facility Reactor Bldg.Requests Adequate Info from Applicant to Support Operability of Valves in HPCI & Main Steam Line Drain Lines Under Pipe Break Conditions

ML20128Q225
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	03/22/1985
From:	Speis T Office of Nuclear Reactor Regulation
To:	Knight J, Thompson H Office of Nuclear Reactor Regulation
Shared Package
ML20127A367	List: ML20127A363 ML20127A500 ML20127A968 ML20127B005 ML20127B638 ML20127B641 ML20127B709 ML20127B780 ML20127C153 ML20127C469 ML20127C607 ML20128P302 ML20128P388 ML20128P824 ML20128P861 ML20128P871 ML20128P892 ML20128P901 ML20128P921 ML20128P941 ML20128P963 ML20128P984 ML20128P988 ML20128P994 ML20128Q012 ML20128Q031 ML20128Q051 ML20128Q062 ML20128Q089 ML20128Q101 ML20128Q225 ML20128Q285 ML20128Q299 ML20128Q313 ML20128Q366 ML20128Q388 ML20128Q409 ML20128Q435 ML20128Q448 ML20128Q467 ML20128Q477 ML20128Q487 ML20128Q492 ML20128Q502 ML20128Q508 ML20128Q520 ML20128Q524 ML20128Q535 ML20128Q846
References
FOIA-85-199 NUDOCS 8507130394
Download: ML20128Q225 (1)

Text

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MAR 2 2 1905 MEMORANDUM FOR: Hugh L. Thompson, Director Division of Licensing James P. Knight, Acting Director Division of Engineering FROM:

Themis P. Speis, Director Division of Safety Technology

SUBJECT:

UNIS0 LATED LOCA OUTSIDE DRYWELL IN SHOREHAM The enclosed draft report on unisolated LOCAs outside of the drywell in the Shoreham reactor building is a scoping study to identify high energy line breaks that are important with respect to isolation requirements.

It identified breaks in the RWCU, HPCI, and MSL drain lines as important.

This study used an upper bound ass *umption that the isolation valves in these lines do not work. The preliminary results of the analysis indicated that the estimate of core-damage frequency for unisolated LOCA outside the drywell at Shoreham assuming that the isolation valves failed to close upon demand is about 2x10 5/ reactor year.

If the isolation valves were assumed to close upon demand, the estimate of the core-damage frequency would be about 4x10 7/ reactor year. These frequencies of core damage are predicated upon the assumption that the condensate system can be used to mitigate the consequences of an unisolable large LOCA, with an 80% success rate.

In order for RRAB to complete its review of this issue, it is necessary that DL obtain adequate information from the applicant to support the operability of the valves in the HPCI, RWCU and MSL drain lines under pipe break conditions.

This information will need to be reviewed by DE to verify adequacy of the valves' operability.

The operability of the isolation valves is important

.for putting these line breaks in the proper safety perspective.

For further information, cor. tact E. Chow, RRAB, x24727.

8507130394 850426 g

PDR FOIA BELAIRBS-199 PDR Themis P. Speis, Director Division of Safety Technology

Enclosure:

[ l,l, __.

As stated cc:

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