Neutron flux measurements in the TRADE experiment : Critical configuration

Abstract : The TRiga Accelerator Driven Experiment (TRADE) to be performed in the existing TRIGA reactor of the ENEA Casaccia centre had the objective of coupling a spallation target, a proton accelerator and a sub-critical reactor core. On the way of the transmutation of minor actinides in dedicated facilities, the TRADE experiment represents the intermediate step between the validation of each component of an Accelerator Driven System (ADS), i.e. the spallation target, the high intensity accelerator and the sub-critical core, and the final facility aiming to incinerate radioactive nuclear waste. Measurements have been performed in the TRIGA - RC1 reactor of the ENEA Casaccia centre in the second semester of 2004 to characterize the neutron flux in a critical configuration. Gold and Indium samples were introduced in the core with the help of a "fast rabbit" pneumatic device. Bare samples and samples covered with Cadmium foils were successively irradiated to estimate the thermal and epithermal fluxes. Measurements have been carried out along a traverse of the core. Samples were put inside Aluminium shuttles travelling in stainless steel tubes. Trains composed of five shuttles allowed for simultaneous measurements in five different axial positions. γ spectrometry of the radioactive nuclides has been performed with two HPGe detectors.