Influence of the design basis earthquake and the safe shutdown earthquake on the design of nuclear power plants

One of the main demands to modify KTA rule 2201 consists in cancelling the existing design philosophy, i.e. design against an operating basis earthquake (AEB) as well as against a safe shutdown earthquake (SEB) in order to only design against the safe shutdown earthquake. The study is subdivided into the following sections: 1) Performance of dynamic analyses by means of models used in praxi for the response spectra method as well as for the time-history method; 2) transform of dynamic loads and calculation of all the residual (non-earthquake specific) loads by means of 3D models; 3) load superposition and structural design (calculation of the reinforcement cross-section) by means of parametric analyses; 4) complete composition and evaluation of data. The conclusions are given in section 7. on the basis of the assumptions for this study. A proposal of an admissible limited predominance-rate for a possible 'AEB' definition is considered regarding the evaluation of conservative and non-conservative assumptions. One possible proposal for the modification of KTA rule 2201 is presented: 1) Increase identified site intensity; 2) modify actual 'AEB' to: 'AEB' = 0.4 * SEB; 3) cancel all design proofs against 'AEB'. (orig./HP)