Application of the modified neutron source multiplication method to the prototype FBR Monju

Truchet, G.*; Van Rooijen, W. F. G.*; Shimazu, Yoichiro*; Yamaguchi, Katsuhisa

The Modified Neutron Source Method (MNSM) is applied to the prototype FBR Monju. Among Monju's particularities that have a big influence on the MNSM factors are: the presence of two californium sources near the core and the position of the detector, which is located far from the core outside of the reactor vessel. In order to evaluate the detector count rate, a propagation calculation has been conducted from the reactor vessel to the external detector. For two subcritical states, an estimation of the reactivity has been made and compared to experimental data obtained in the restart experiments at Monju (2010). Results indicate a good agreement between the MNSM reactivity and the reactivity measured with other methods.