Rod drop accident analysis for Angra 1

A methodology for analysing the rod drop accident in pressurized water reactors operating in the automatic control mode. Calculations concerning the third cycle of the Angra 1 Nuclear Power Plant are used to illustrate the application of this methodology is presented. In this analysis all possible configurations for dropped rods caused by a single failure in the controller circuits have been considered. The dropped rod worths, power distributions and ex core detector tilts are determined by using the Siemens/KWU nuclear code system, in particular the MEDIUM, PINPOW and DETILT codes. The transient behaviour of the plant during the rod drop event is simulated with the SACI2 code, developed at CDTN. Determinations related to the DNBR design limit are conducted by utilizing the KWU PUMA2 code. It must be emphasized that the present work is only intended to propose a method to analyse the rod drop accident. For the purpose of licensing, the analysis must be repeated, with the participation of FURNAS, taking into account the actual control and protection conditions of Angra 1. (Author)