Monju safety margin analysis based on measurements

Nishida, Kazuhiro; Kitamura, Kenji*; Yamada, Fumiaki

The results of the function test and the startup test of the Prototype Fast Breeder Reactor Monju were examined for the hypothetical analysis of the rapid withdrawal of the control rod assembly and to analyze pump seizure in the Primary Heat Transport System, in order to obtain accurate transition of the plant dynamics. These analyses confirmed that both of the accidents settle down without affecting the plant structure. During the withdrawal accident, reactor power reached 106%. During the pump seizure accident, the fuel cladding mid-wall temperature reached 702C. Both of these values are sufficiently below the safety margins for anomaly transients and accidents during operation and former analyses for design safety permission. The differences between these results and the former analyses for design safety permission have mostly been attributed to the characteristics of the control rods.