Studies of passive safety tests by using the experimental fast reactor Joyo; Verification of Joyo plant dynamics analysis code Mimir-N2

Takamatsu, Misao ; Kuroha, Takaya*; Aoyama, Takafumi 

Studies for passive safety tests to be conducted by using Joyo have been carried out to demonstrate the inherent safety of LMFBR. In these studies, emphasis has been placed on the improvement of the calculation accuracy of the feedback reactivity. Therefore, in the passive safety tests, the feedback reactivity measurement is planned under the condition simulating ATWS event. The Mimir-N2 which has been developed to analyze Joyo plant dynamic is used for predicting plant behavior during transients. In order to determine the passive safety tests plan, the improvement of the accuracy of Mimir-N2 was required. In this study, transient tests including manual reactor shutdown test, loss of power supply test and preliminary transient over power test were conducted to verify the updated model of the Joyo MK-III core and the heat transport system of Mimir-N2. As a result, a good agreement was obtained between calculated and measured sodium temperatures.