ML20112D636

Intervenor Exhibit I-SC-LP-56,consisting of Attachment 9: Pages 5-62 & 5-63 to Dec 1983 Seismic Fragilities of Structures & Components at Shoreham Nuclear Power Station

ML20112D636
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	08/07/1984
From:	Campbell R, Hardy G, Narver R, Sues R, Wesley D STRUCTURAL MECHANICS ASSOCIATES
To:
References
I-SC-LP-056, I-SC-LP-56, OL-4, NUDOCS 8501140411
Download: ML20112D636 (6)

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b SEISMIC FRAGIL! TIES OF STRUCTURES AND COMPONENTS i

i AT THE SHOREHAM NUCLEAR POWER STATION

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j N by D. A. Wesley

• G. S. Hardy R. D. Campbell J

R. B. Harver 1

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551S*!C FRAG!L!?!ES OF STRUCTURES AND C0"DONENTS AT THE SHOREWAM NUCLEAR POWER STATION Dresared for NUS CORPOD.ATION Ran:he Bernardo, California Oe:em:er,19!!3 g g STRUCTURAL

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Table 5-12 contains a list of tnose components which have grov-i l

acceleration capacities less than 1.5 g's. These components will all, J l

some degree, enter into the overall plant risk. Upon completion of l

' initial risk assessment by NUS, those components which prove to be the biggest contributors to risk should be reassessed to determine if further study would result in a more accurate median capacity level.

The following two sections contain some general results and some l

! specific results on equipment fragilities.

5. 3.1- General Results -

' The following are some general results on the equipment portion of the PRA:

1. The majority of the equipment within the Shoreham '

plant which were seismically qualified have rela-tively high ground acceleration capacities. This is due to the relatively high SSE (0.20; ZPA) coupled with the more sophisticated qualifi-cation techniques and applicable codes which are associated witn equipment in a nedern plant.

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2. Non-seismically qualified components listed in Table 5-1 generally have relatively low i capacities and relatively high uncertainties.

These results are understandable due to the lack l

i of a requirenent for seismic design.

3. Seismically qualified components whose qualifica- ,

tion reports were unavailable had to have their capacities evaluated on a generic basis. Tne resulting uncertainty on these components are generally higher than these conoonents whose f ragilities were based on specific qualification reports. Components in this category which are determined from the risk analysis to be major contribJtors to the overall plant risk should be

! identified and subse;uently reevaluated in greater depth to reduce this uncertainty and pesvide a more accurate nessare of the median capace6y.

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l 5-62 l

s 5.3.2 Specific Results The following points serve to explain in greater detail some of the more important specific fragility results on the equipment portion of the Shoreham PRA.

1. The 139 and 69 KV off site power source fragilities are based on a review of insulator f ailure in six major earth-quakes ranging f rom 0.11 g's to 0.40 g's peak ground acceleration. This resulted in a median capacity level of 0.20 g's and 3g = 0.20 and Eu = 0.25.

2. Chatter of electrical equipment indicates a transient condition of contact bounce. Depending on the circuitry design of the equipment in question, chatter may or may not cause tne f ailure of the components intended function. For instance, some electrical cabinets are designed with sufficient time delay mechanisms such that chatter of the duration of a typical earthquake will not cause a change of .

state in the equipment. Determination of the effect of chatter on an individual electrical cabinet is beyond the scope of SKA's f ragility effort and is much more efficiently handled at the systems level.

3. The reactor vessel fragility was based on information obtained f rom the Shoreham FSAR. The stress summary data in the FSAR for major GE items such as the reactor vessel were generally based on generic design loads which conservatively envelope the actual Shoreham loads. The reactor vessel ground ac:eleration capacity is shown to be sufficiently low (1.04 g's) that it could possibly be a major contributor to the plant risk. Since the reactor vessel fragility was based on estimating the amount of conservatism in utilizing generic design loads, the ROV median ground acceleration capacity could be more accuratoly defined and the uncertainty reduced by obtaining the actual Shoreham loads. Such a study would involve the cooperation of GE personnel to obtain the required specific reactor vessel inf ormation f or Shoreham.

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5-63

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