Um estudo da física de sistemas multiplicadores subcríticos acionados por aceleradores

Abstract

In this work were reviewed the operation principles of subcritical multiplying systems powered by accelerators (ADS) from the point of view of the neutron transport. To do this it was necessary to characterize theoretically the external neutron source produced by spallation reactions and to study the proposal of simulating this kind of high-energy nuclear reaction through fusion reactions as deuterium-tritium (D-T). The problem of the neutron transport was treated using the method of discrete ordinates with multigroups of energy for one spatial dimension, both for the direct and the adjoint calculation using the perturbation theory, through the ANISN/PC code. The model used to neutronic calculations was based on the fast part of the benchmark Yalina-Booster using 3 groups of energy. Static calculations were performed for the flux and for the criticality in three spatial regions for slab and cylindrical geometry, as well as tests of effects of the change in the method of calculating the spatial derivative that is used by ANISN/PC code. The infinite multiplication coefficient was calculated analytically for one spatial region in order to compare the analytical results with the numerical results. The results allowed to analyze the physics of the neutron transport involved in the problem as well as the comparison with results calculated by the diffusion theory, in addition of it they provided the learning with the use of the ANISN/PC code and with theoretical studies preliminary made.