A new mathematical approach using Hermite approximations method for analysis of transient behavior in research reactors

Abstract

In this paper, a new mathematical model based on Hermite approximations is presented to investigate the thermal behavior of a research reactor in transient conditions. For this purpose, the point kinetics equations are coupled to the thermal-hydraulic equations for a coolant and improved lumped heat conduction equation for the fuel and cladding. In contrast with the traditional method (such as finite difference method), the developed method can find exactly maximum temperatures of the fuel and cladding without considering numerical nodes in the fuel and cladding materials. This method obtains the peak fuel and cladding temperatures with only solving two ordinary differential equations. In complex thermal systems such as nuclear reactors, accurate prediction of the maximum fuel and cladding temperature is very important from a safety perspective. Hence, it is more desirable to provide a simple and efficient model for analyzing transient behavior of the system in a short time. The RELAP5 code has been used to validate the developed model. The comparison between the developed model and RELAP code results show that the physical models and the framework implemented in this model are reliable.