“…Systems for detecting leaks in fuel-element cladding during reactor operation [6][7][8], systems for locating fuel assemblies with defective (with respect to gas or fuel) fuel-element cladding in external systems after removal from the reactors, and a spectrometric circuit on a radioactive loop [5] were developed and adopted. Fuel elements with different fuel (plutonium dioxide, uranium carbide, uranium metal, uranium nitride), with an artificial defect in different locations and of different forms in fuel-element cladding, the development of a defect during irradiation, and the response of the system that monitors cladding seals were investigated.…”