Pebble bed thermal–mechanical theoretical model

Experimental and numerical analyses on LiSO4 and Li2TiO3 pebble beds used in a ITER test blanket module

“…The pebble arrangement in the initial part of the first loading cycle and in the final part of the unloading cycle is not described by the model. The aspect of the experimental contact zone (a cylindrical part plastically deformed) corresponds perfectly to the evolution of the plasticity assumed in the model (see [1][2][3]). …”

“…The theoretical model developed by the authors describes the thermo-mechanical behaviour of two compressed spheres and extends the results to a pebble bed assuming that it is made up of a mixture of regular lattices [1][2][3]. The mechanical stiffness is determined by considering two half spheres as variable cross-section beams and assuming the behaviour of the material to be elastic-perfectly plastic under compressive stresses and elastic under tensile stresses.…”

“…The model has been assessed by performing numerical simulations using finite element method (FEM) computer codes and comparing the results with theoretical results. Moreover, a comparison has been made with experimental data found in the literature [1][2][3]. However, the geometry of the TBMs and the distribution of the thermal and mechanical loads are very complex and the theoretical model can not be applied in the form which has been developed.…”