A MATHEMATICAL MODEL FOR CALCULATING STRESSES IN A 4-LAYER CARBON-SILICON-CARBIDE-COATED FUEL PARTICLE

A previous mathematical model for calculating stresses in the coatings on a three-layer carbon-silicon-carbide-coated fuel particle has been extended to the case of a four-layer coating. The four layers considered are: low-density carbon, dense isotropic carbon, silicon carbide, and dense isotropic carbon. The assumptions used in the model and the mathematics of the calculations are similar to those of the previous model. However, a possibility of separation at the inner carbon-silicon-carbide interface has been considered, and in that case the volume available to the fission gases cannot be considered to be independent of the displacement of the inner coating. In general, it appears that the stresses due to the initial fast-neutron-induced densification of the carbon are more severe in the inner carbon than in the outer carbon. Separation at the inner interface can relieve these stresses, but it raises the possibility of high stresses in the inner carbon at a later time. © 1969.