Method of nondestructive monitoring of fuel-element seal tightness

A method of monitoring the seal tightness of fuel elements is described. The method is based on determining leaks of gaseous fission products during annealing of preirradiated samples. The basic steps using this method are described and mathematical expressions for determining the constants of the activation model of the leakage of gaseous fission products, which is used for processing and analyzing experimental results, are presented. The measurements results obtained using the method develop are compared with the results obtained in reactor tests of spherical fuel elements. An example using the technique is described: simulators, for which the temperature dependence of 135 Xe leakage (to 1400 K) is obtained and a quantitative relation between the number of microfuel elements with damaged coatings and leakage of gaseous fuel products, are tested. It is found that technological contamination of graphite of the simulators by uranium is present.