Neutron radiative capture on 242Pu: addressing the target accuracies for innovative nuclear systems

Abstract

A low-carbon energy oulook to mitigate the impact of the climate change requires the progressive replacement of fossil fuel technologies by sources with low CO2 emissions. In this context, nuclear energy is expected to play a relevant role. Ensuring the long-term sustainability of nuclear energy points to the use of innovative nuclear systems, such as Accelerator Driven Systems and Generation-IV reactors and new fuel compositions, such MOX fuels aimed at the reduction of the nuclear waste. The design and operation of these nuclear innovative systems requires a better knowledge of the capture and ssion cross sections of the Pu isotopes. For the case of 242Pu, a reduction of the uncertainty in the fast region (2-500 keV) from the current 35% down to 8-12% is required. Moreover, aiming at improving the evaluation of the fast energy range in terms of average parameters, the OECD NEA High Priority Request List, requests high-resolution capture measurements with improved accuracy below 2 keV. The uncertainties also afect the thermal point, where previous experimental results deviate from each other by 20%. This thesis presents the new measurement of the 242Pu(n,) cross section from thermal to 500 keV combining diferent neutron beams and techniques. In collaboration with JGU Mainz and HZ Dresden-Rossendorf, we produced a sample consisting of a stack of sevenssion-like targets making a total of 95(4) mg of 242Pu electrodeposited on thin (11.5 um) aluminium backings. The thermal point was determined at the Budapest Research Reactor by means of Neutron Activation Analysis and Prompt Gamma Analysis, and the Resolved (1 eV - 4 keV) and Unresolved Resonance Regions (1 - 500 keV) were measured using a set of four Total Energy detectors at n TOF-EAR1. This manuscript deals with the description of the facilities and experimental techniques, the detailed data reduction for both experiments, and the discussion of the nal results and achieved accuracies for the capture cross section in each energy region.