SICOM, An equipment for very accurate dimensional and corrosion inspection of irradiated fuel assemblies

Nuclear fuel undergo evolution in its properties and characteristics as result of the operation in the nuclear reactors. Knowledge of this evolution is necessary to guaranty the behaviour and safety in the operation, as well as to optimize the economic performance of the fuel cycle. When, with the objective of improving the performance of fuel, some important modifications are made, it is necessary to prove the effect on the behaviour and evaluate the influence in each of the critical characteristics of the fuel assemblies. In this cases, it could be necessary to burn a reduced number of fuel assemblies of the new design (demonstration assemblies). During the demonstration process, some characterization of the behaviour of the fuel is made, usually at the end of each cycle. An important part of this characterization is made using NDE methods, applied at the nuclear plant during the refuelling outages. Within the Electrotechnical Research and Development Program (PIE), and with participation by IBERDROLA, TECNATOM and ENUSA, an inspection system (SICOM) has been developed for spent fuel assemblies from pressurized water plants, the aim being to check the following features: general condition, apply dimensional controls and measure the oxide layer on the peripheral fuel rods. This equipment was qualified at Tecnatom and Almaraz I NPP during the first quarter of 1995. Subsequently, in September, it was validated for the EDF P'4 plants at C.N.P.E. Belleville