Methods and post-irradiation examination techniques applied in testing the performance of irradiated CANDU nuclear fuel

The Post-irradiation Examination Laboratory, Lei, in Nuclear Research Institute at Pitesti, INR, is a nuclear facility which is in charge with examination of irradiated nuclear fuel as well as other irradiated materials components of nuclear reactor. Such irradiated fuels and materials come from the TRIGA materials testing reactor at INR Pitesti, the Cernavoda NPP and other nuclear power stations. The operational core of this laboratory is constituted of two blocks of hot cells suitable for handling and examination of radioactive materials with gamma activity level up to 106 Ci (Emed ≤ 0.6 MeV and high concentrations of transuranium elements (Pu, Am, Cm). To obtain pertinent information regarding the performances of the domestic CANDU nuclear fuel, a significant number of fuel elements irradiated at different power histories in MW (Th)TRIGA reactor were examined in the Lei hot cells, making use of different post-irradiation examination techniques. These techniques imply both non-destructive examination methods (visual inspection and photography, testing with eddy currents, surface analysis, gamma scanning) and destructive methods (sheath boring and measurement of pressure and volumes of fission gases, metallography, ceramography, determination of burnup by mass spectroscopy on solved irradiated fuel samples, tensile test). The data obtained from post-irradiation examination are useful on one hand to certify the reliability and performance of nuclear fuel and on the other hand for developing the CANDU fuel