Previsão da criticalidade através da curva 1/M no reator IPEN/MB-01

Abstract

During the first reactor startup when the exact configuration of the control and safety banks is not known, it is necessary to estimate certain reactor parameters such as the control rod positions and the boron dilution ratio in order to safely achieve criticality. To make this estimation, the subcritical multiplication methodology was applied to predict criticality using 1 the M curve. To carry out the proposed method, one must consider the reactor core design, know the position and distribution of fuel elements, the location of the neutron source and detectors used, and understand the specifications of the equipment used for neutron flux measurement, ensuring they are within the appropriate operating ranges to avoid errors during measurement. It is also important to identify the parameter responsible for altering the neutron flux. Once all parameters that influence neutron distribution and core neutron balance, including the effects of the installed neutron source, have been established, it becomes possible to apply the 1 subcritical multiplication by constructing the M ) curve to predict the moment at which the reactor reaches criticality. The parameter responsible for the variation in the counting rate was the movement of the control banks, which were initially inserted fully into the core during the startup and then gradually withdrawn in 5% increments until criticality was achieved. Once the effective multiplication coefficient approached 1, the estimate of control rod positions, along with their margin of error, was obtained by interpolating the last two points on the generated curve. At the conclusion of the procedure, the observed results were discussed to deepen the theoretical knowledge taught in applied physics in nuclear reactor engineering.