Void evolution simulation in neutron-irradiated vanadium

Void evolution in high dose neutron irradiated vanadium is studied with the use of newly created numerical code. To calculate void densities measured in vanadium at high temperatures, the vacancy selfdiffusion energy must be as high as 3.5 eV and the concentration of oxygen must be sufficient to provide surface energy of voids as low as 1.2 J/m(2). Due to the size dependence of void preference, high dose modeling revealed a possibility for void coarsening in vanadium at low temperatures, low void surface energies (caused by oxygen chemisorption) and low dislocation densities. With increasing dislocation density, maximum void concentrations increase significantly at low temperatures while at high temperatures the situation is reversed. The dose required to reach maximum void number density has a minimum at intermediate temperatures. The highest swelling is predicted for low dislocation densities and high oxygen concentrations in the initial stage of irradiation and vice versa at high doses.