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Conference Article: Contribution of earthquakes to the risk of a HTR-100 plant.

Altes, J. (Kernforschungsanlage Juelich GmbH (Germany, F.R.). Inst. fuer Nukleare Sicherheitsforschung)

Abstract

Within risk analyses for nuclear power plants with high temperature reactors also the contribution of earthquakes has to be considered. In a study for the HTR-100 recently carried out by the Institute of Nuclear Safety Research of KFA such investigations had been done. For the analysis a site with high earthquake risk was chosen for which a seismological expert opinion exists. The earthquake occurrence rates dependent on the intensities, the 84% fractile free field response spectra and the dynamic material properties are known. The structural response of the primary circuit within the reactor building is calculated using a 3d finite element model including the soil structure interaction. The calculations consider different soil properties. In a sensitivity study the influence of changing the support conditions for the reactor vessel and its internals on the response behaviour is analyzed. The eigenfrequencies and eigenforms as well as the deformations, accelerations and stresses are calculated. The maximum stresses occur at the support of the steam generator. The failure probabilities are calculated for this part of the structure using the first order reliability method. The influence of the earthquake intensities and the properties of the subsoil on the failure probabilities are analyzed. The failure probabilities due to earthquakes are very low, so that there is no risk dominant contribution.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Seismic behaviour of gas cooled reactor components. Proceedings of a specialists' meeting held in Gif-sur-Yvette, France, 14-16 November 1989
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--22, pp:34-41