Method of and an apparatus for the evaluation of burned-out nuclear fuel elements

摘要

Nuclear fuel elements or slugs are removed from the nuclear reactor cores and subjected to inspection, according to the invention, by introducing a plurality of such elements into a submerged inspection vessel which is then closed, the liquid driven out by compressed air and deionized water (deionate) circulated through the inspection vessel at a constant rate. A portion of the deionized water is branched from the circulating stream at a constant rate and the activity of at least one fission-product nuclide is determined continuously to plot the activity versus temperature, thereby signaling a possible defect in the shell of a fuel element. In addition, ultrasonic vibration is applied in the inspection vessel to the fuel elements so that deposits on the exterior thereof are released into the deionate whose circulating path includes a filter and an ion-exchange column for removal of such deposits.