Uncertainty assessment in the seismic response of the primary circuit of a 1300 MW PWR

This paper presents the final results of a five-years research program (1981-1986) at the CEA. The research concerns the assessment of the uncertainty in the seismic calculation of the primary circuit of a French 1,300 MWe PWR. In a first step, after the collection of documents, the model of the reactor building and the primary circuit has been done. In a second step the 3D seismic analysis of the reactor building has been performed and a set of five 3D seismic analysis of the primary circuit, coupled or uncoupled, using the floor response spectra obtained for the building, has been realized. Then in a third step, which is the main purpose of this presentation, a new basic model of the primary circuit has been achieved with five variations in boundary condition hypothesis, and, for each one, six different seismic analysises. As no significant differences for the floor spectra were found in step 2, between coupled and uncoupled calculations, the step 3 has been performed fully uncoupled. The basic method used for these seismic analysises is modal recombination. (orig./HP)