Two-Region Kinetic Model for Reflected Reactors

Reflected reactors constitute one of the most important classes of nuclear reactors. Yet. experimental data clearly shows that the kinetic behavior of some types of reflected systems cannot be adequately characterized using the standard point kinetic model. In this work, a two-region, nodal kinetic model for reflected systems is developed that appears to explain the anomalous behavior of these systems in terms of integral parameters that are both measurable and calculable. The model is based on previous work by Avery and Cohn. We augment the Avery-Cohn model with the introduction of simple probability relationships essential to calculating the coupling parameters between the core and the reflector. Using these probability relationships, we then derive the definition of the effective multiplication factor keff in terms of the multiplication factor of the core region. k c, and the reflector return fraction. f We also derive the reflected-core inhour equatIOn and introduce expressions to calculate the neutron lifetimes characterizing the systemʹs static and dynamic behavior. The model is then tested using Rossi-a data from the University of New Mexicoʹs AGN-20l reactor.