Fluctuation of the neutron multiplication factor caused by the sloshing motion of the fuel solution system

Sato, Shohei; Okuno, Hiroshi  

The deformation of the fuel solution causes the reactivity. From the viewpoint of nuclear safety, it is important to comprehend the feature of this effect. Before now, it is found that the negative reactivity is induced, if the height of the fuel solution, which is more 0.5 is deformed. In the last report, we executed the combination computing between the fluid calculation and the criticality calculation, and calculated the time change of the neutron multiplication factor of the oscillated fuel solution. In this report, we investigate the relativity of the solution height for the fluctuation of the neutron multiplication factor using the same method. The fluid calculation is executed to calculate the fluctuation of the fuel solution contained in the slab tank oscillated with following the sine wave. The criticality calculation is executed to calculate the neutron multiplication factor deformed by the oscillation obtained from the fluid calculation. As the result, we found that there is a threshold, which can classify the fluctuation pattern of the neutron multiplication factor and the threshold is 0.4 which is expressed by the ratio of the solution height and the width of the tank. Also, we found that the threshold is smaller than before value.