Effect of Nuclear Fuel Particle Movement on Nuclear Criticality in a Rotating Cylindrical Vessel

Abstract

In conventional criticality safety evaluations of nuclear facilities, nuclear fuel particle behavior could not be considered because any appropriate computational tools did not be developed. A new criticality evaluation tool, which can consider the particle behavior, is developed by coupling a Discrete Element Method with a continuous energy Monte Carlo type code. Criticality evaluations considering the nuclear particle movement in a rotating cylindrical tank are performed by applying this tool. Effects of the powder-filling ratio and the rotating speed on nuclear criticality are investigated in the present study. The nuclear powder free surface is fluctuated more remarkably as the filling ratio and the rotating speed are higher. The fluctuation makes the effective multiplication factor lower because of neutron leakage from the system by the increase of the superficial area and reduction of the atomic number densities due to the flowability.

Experimental analysis of heaping and self-levelling phenomena in core debris using lead spheres

“…Inter granular interactions are determined by coefficient of restitution which is 0.25 for UO 2 particulate debris both in particle-particle and particle-wall interactions in dry condition [13]. In a liquid medium, coefficient of restitution comes down further as evidenced from experiments on different materials conducted by Gondret et al [14].…”

How Should the Discrete Element Method Be Applied in Industrial Systems?: A Review

“…In the previous DEM simulations, the calculation domain, i.e., the wall boundary, was modeled using surface equations (Sakai et al, 2005) or meshes (Shigeto and Sakai, 2011;Mateo-Ortiz et al, 2014). The use of surface equations is an easy approach to create simple regimes.…”

“…Finally, modeling of an arbitrary shaped wall is also important in industrial systems. In previous studies, a combination of simple surface equations (Mio et al, 2002;Liu et al, 2011;Sakai et al, 2005), the location of DEM particles and meshes (Shigeto and Sakai, 2011;Mateo-Ortiz et al, 2014) was used to create a wall boundary in the DEM. The combination of simple surface equations was difficult to create an arbitrarily shaped domain.…”

Large‐scale discrete element modeling in a fluidized bed

“…The validity of this drag force modeling was established through correct predictions of pressure drop and minimum fluidization velocity [3,6]. Predictably, the gravitational force is given by:…”

“…Hence, the DEM has been used in many powder processes, e.g. ball mills [6,7], mixers [8,9], grinding processes [10], etc. Furthermore, the DEM easily takes into account the effects of cohesive forces [11][12][13].…”