Effects of thermal expansion mismatch on solid breeder blanket pebble bed and structural clad thermomechanics interactions

In this paper, a thermomechanical interaction of a ceramic breeder pebble b ed and structural plate is studied based on a recently developed discrete n umerical simulation code. The calculations take into account the coupling e ffect between structural wall deformation and pebble bed deformation, which greatly increases the computing time and complicates the computational pro cedures in determining the particle-wall contact characteristics. Specifica lly, the model is applied to a lithium orthosilicate packed bed for the eva luation of the deformation of a circular plate due to bed thermal expansion , while the results are compared with SCATOLA's experimental data. Numerica l results using a fixed boundary condition show reasonable agreement with t he experimental data. In addition, numerical simulations confirm an irrever sible plate deformation after a thermal cycle run as observed in the experi ments, although these experimentally observed deformations are larger than that of the numerical estimations. Moreover, numerical results of contact f orces at contact points provide information concerning the mechanical integ rity of the bed at a moderately high temperature.