Computational procedure for the bowing of reactor fuel rods

Bowing of zircaloy clad reactor fuel rods has been observed. The magnitude of rod bow has been suggested to be dependent upon axial thrust, initial curvature, support misalignment, creep relaxation, irradiation induced growth, anisotropic creep, temperature and flux gradients, pressure differential, and eccentric cross sectional geometries. A finite element code, AXIBOW, has been developed to evaluate the time and environmental dependence of bowing of reactor fuel rods and the sensitivity of predicted rod bow to the previously mentioned factors. The theoretical formulation of this code is an extension of that used for the CRASIB code which is a beam element code formulated to evaluate the effects of creep and swelling on structural deflections