Fluctuation of the neutron multiplication factor induced by an oscillation of the fuel solution system

Sato, Shohei; Okuno, Hiroshi  ; Uchiyama, Gunzo 

This paper intends to figure out reactivity of the fuel solution system with a free surface. To fulfill this intension, criticality calculation with reflecting fluid calculation results have been carried out. For fluid calculation, the finite volume method and the VOF method are applied to track the free surface caused by an oscillation. For criticality calculation, we have applied the continuous energy Monte Carlo calculation method. As a result, three fluctuation types of have been obtained depending on the oscillation frequency and the ratio of the solution height to the width of tank (H/L). If a sloshing motion is generated, fluctuates by a wide range and has a threshold, which can classify the fluctuation type of , despite the kind of the reflector. If H/L is above the threshold, H/L=0.35, it fluctuates below the value of the static condition. The threshold value represented in this paper is smaller than that of the conventional one.