Calculation of Transient Parameters of the Integral Kinetic Model with Delayed Neutrons for Space-Dependent Kinetic Analysis of Coupled Reactors

This study introduces new methodologies for integrating fission reactions induced by delayed neutrons into the Multi-Region Integral Kinetic (MIK) code by using a Monte Carlo neutron transport calculation. First, it was confirmed that it is feasible to solve the Integral Kinetic Model (IKM) with delayed neutrons by the forward Euler discretization method in terms of the number of time steps. This can be done with the help of the law of radioactive decay to reflect the delay in the emission of delayed neutrons in the discretized IKM. Second, a new Monte Carlo–based methodology was introduced for calculating the cumulative distribution functions of secondary fission induced by prompt and delayed neutrons. These functions are necessary for the discretized IKM. The results of preliminary verification using the Godiva reactor confirmed the applicability of the new Monte Carlo–based methodology. A new MIK code that has the capability of calculating the fission reaction rates for delayed neutrons is currently under development. Based on the preliminary verification results, future studies will verify the discretized IKM with delayed neutrons using kinetic analyses and compare them to experimental results for prompt and delayed supercritical transients in diverse reactor configurations.