Drop Analysis of Plate-Type Fuel Assembly in a Research Reactor

In nuclear research reactors, plate-type fuel assemblies are often employed to achieve high neutron flux. During loading/unloading of these assemblies, a tight control over fuel assembly movement is maintained with established procedure. However, any mishandling during this procedure could result in an accidental drop, leading to mechanical damage to the fuel assembly. It may further result in fission product release to the environment in case of mishandling of a spent fuel assembly. The present work investigates the extent of the damage to the fuel assembly during a drop accident and evaluates the fuel plate integrity. In this paper, drop accidents are classified into two categories based on the location where the fuel assembly drop takes place. If an accident occurs within the reactor core region, impact on other fuel assemblies placed on the grid plate is considered. In case it occurs in other region of the reactor pool, a direct impact of the fuel assembly on the reactor pool bottom is envisaged. Numerical simulations are performed to simulate drop accidents using finite element analysis, and quantitative assessment of the damage is presented in terms stress, deformation, and energy history in the present work.