Equipment for non-destructive determination of burnup of nuclear reactor fuel elements

This arrangement makes a detailed measurement of the irradiation loading especially of the 4 corner rods in a partly burnt-up fuel element possible, and enables one to measure its variation along the rod. Such exact measurements permit one to draw final conclusions on the burn-up of the whole element and determine the fuel element exchange programme, where less burnt-up elements are exchanged for more burnt-up elements after a certain operating time inside the reactor, in order to obtain optimum use of the fuel. A holding arrangement inside the radioactive decay pond belongs to the arrangement, and so does a collimator for taking out the radiation to be measured through the approx. 1.80 metre thick concrete shield and the actual measuring equipment outside the shield. The rectangular fuel element is set in the holding arrangement in the radioactive decay pond for measurement. The radiation taken out from there is adjusted by shutters in the collimator adjustable from outside. In order to avoid absorption of radiation, the distance from the fuel element to the collimator is bridged by a tube. The collimator opens into the actual measuring equipment, outside the shielding, consisting of a spectrometer of high resolution (Ge Li Spectrometer). (HP)