A normally permissible method of simplifying, without any loss in accuracy, the Walther model for calculating the mechanical performance of coated fuel particles

Abstract The Walther formalism may be simplified if the properties of each layer in a coated fuel particle are such that the expressions 33 C (k) ω,l + 13 C (k) ω,l 11 C (k) ω,l + 12 C (k) ω,l and 33 C (k) γω,l + 13 C (k) γω,l 11 C (k) γω,l + 12 C (k) γω,l are equal and independent of neutron dose. The symbols C σ , i and C Γσ , i denote the elastic and radiation creep constants of layer i , the superscript ( k ) indicates that these are in general functions of neutron dose, while the subscripts 1 and 2 refer to the tangential and 3 to the radial directions. Provided these conditions are valid (as they are for most, if not all model calculations performed to date) the need to compute stresses at closely spaced intervals across each layer and perform a number of numerical integrations are eliminated. Since these particular parts of the associated computer programme STRESS 3 are by far the most time consuming a significant saving in execution times may be achieved.