Measurements and calculations on sloshing effects in solution vessels having a free surface

A criticality safety experiment which simulates the sloshing effect in the solution vessel having a free surface has been performed using a Tank-type Critical Assembly (TCA) at Japan Atomic Energy Research Institute. In the experiments reactivity effects by surface deformation of the rectangular cores were measured by using critical water level worth method at constructed mock up cores in TCA. The experimental results suggest that the criticality safety of slab tanks which involve nuclear fuel solution can be satisfied even in the sloshing situation, when the ratio of the solution height to the slab thickness is larger than 0.5. Calculations were also performed on reactivity effects in solution deformation for typical solution systems using the Monte Carlo code KENO-IV and the diffusion code CITATION of which accuracy was established by comparison with the experimental data. (author)