Solução das equações da cinética pontual de nêutrons com efeitos de temperatura e venenos: um estudo de caso do acidente em Chernobyl

Abstract

In this dissertation, the solution of the equations of the Neutron Point Kinetics is presented, applying the Rosenbrock method. In the first part of this work, in order to verify the methodology, one and six groups of delayed neutron precursors are considered for reactivities of the type: constant, ramp, quadratic, sine, zig-zag and pulsed source. In the second part, the effects of temperature and then poisons on the final behavior of the neutron density are included in the cited equations. Subsequently, a case study of the Chernobyl accident is performed in order to simulate the preliminary characteristics of the accident, where the joint effects of poisons and temperature in the nuclear reactor are analyzed. The numerical results obtained are compared to those found in the literature, which achieved good accuracy as the time step is reduced, ensuring the overcoming of the system stiffness. The simulation of the characteristics of the accident at Chernobyl produced results that were physically consistent with the reference data. Thus, this study contributes to ensuring the safe operation of nuclear reactors by analyzing the behavior of the neutron density for different reactivity insertions. Besides, this study contributed to highlight the importance of temperature effects and especially poisons in the final power behavior, extremely relevant for decision making in the operation and safety of a nuclear power plant.