Loss of energy IV class at 100% of plain power (PP). FIREBIRD III contrast with the mentioned event at 88% of PP occurred at CNE (Embalse nuclear power plant) on February, 23rd., 1984

The work consists of two objectives: a) to simulate with the FIREBIRD III code an electrical energy loss of the IV class at 100% of plain power (PP); b) contrast of the mentioned event of type IV loss when the plant operated at 88% of PP. In the case of 100% of PP, three kinds of calculation are made: a) one of them oriented to the reactor's safety concept, that is, where the slower cut system acts; 2) oriented to analyze the STEPBACK effectiveness; 3) the control systems and cut systems act when the corresponding 'set points' are reached. The results compared with those obtained by the Hydna-3 code and other Canadian references, are satisfactory. In the case of 88%, the Embalse nuclear power plant's supplied information each 12 seconds in the TRIP LOG reactor, and each 1 second in the computer list, the necessary data for the simulation are not available. The transient, varying the parameters, delayed in trip and stepback, and the different cut times of feed water to the secondary loop, are analyzed. (Author)