ML20195C400

Affidavit of LC Shao Re Control Bldg Design Errors Resulting in Substantially Weaker Walls than Intended by Original Design criteria.As-built Structure Has one-half of Seismic Capacity & Safety Margin

ML20195C400
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	06/29/1978
From:	Shao L C NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	NRC COMMISSION (OCM)
Shared Package
ML20195C358	List: ML20195C351 ML20195C385 ML20195C400
References
TAC-07551, TAC-11299, TAC-7551, NUDOCS 8811030075
Download: ML20195C400 (2)

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION d

BEFORE THE COMMISSION In the Matter of

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PORTLAND GENERAL ELECTRIC COMPANY )

Docket No. 50-344'

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et al.

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(Trojan Nuclear Plant)

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AFFIDAVIT OF LAWRENCE C. SHA0 STATE OF MARYLAND

) SS C0pNTY OF HONTG0MERY )

I am an Assistant Director for General Reactor Safety Research, Offlee of Research, U.S. Nuclear Regulatory Commission, Washington,

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D.C.

20555.

Until recently I was Chief. Engineering Branch, Division of Operating Reactors, with responsibility for the review of the structural analysis and design of the Trojan Nuclear Plant.

o I have prepared the folicWing statement regarding the NRC's Order for Hodification of License dated May 26, 1978, as it relates to the reduction in safety margin for the Control Building at the Trojan Nuclear Plant.

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The Control Butiding Design Errors The Architect-Engineer (Bechtol) allotted too much strength tn the walls in shear during the calculations perfonned for the ori inal J

design due to misapp1(cations of design formulai As a resuit, less speel rebar was spa:ified for and installed in the shear walls than would have been the case had the design formulae been applied correctly.

In addition, the steel in the inner concrete cores was found to be generally not continuous as had been assumed in the design calculations.

Therefore, this discontinuous steel cannot be relied upon to carry st.tdr loads. The result of these errors is that the shear walls are substantially weaker than intended by the original design critoria.

The loss in safety margin is significant.

The "as-buil.t" structure has on the order of one-half of the seismic capacity nriginally intended and approved. While adequate margins of safety still remain to allow operation with the as-built Control Butiding, the safety margin for that building is reduced on the order of 50%.

st~JA. *w rence C. Shao Subscribed and sworn tn STATE OF MARYLAflD before me this 27th day COUtiTY OF M0flTG0MERY of June 1978

,i Anne X. Baron g% gg Notary Public MY COMMISS10tl EXPtRES:

July 1, 1978

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