Development and Verification of a Reactor Dynamics Code for Molten Salt Reactors with Flowing Fuel

The development of DYN3D-MSR code is described in the paper. This code is based on a three-dimensional code DYN3D for calculation of steady states and transients in light water reactors LWR, which was developed in FZR. The MSR modification of DYN3D code is designed to calculate steady states and transients of Molten Salt Reactors. The fuel of this reactor should be liquid in a form of molten salt mixture and should act also as a coolant. The thermal-hydraulic and neutron kinetic characteristic will differ from classical LWR. For the code development a MSR design with fuel floating in channels inside hexagonal graphite structure is considered. The first step of development is a 1D version, which is based on a numerical method for hexagonal fuel element geometry from original code and which includes new models describing fuel flow. DYN1D-MSR as the first step of 3D version development is already an effective tool for transient analysis of MSR. The first results for fuel flow slowdown have shown the ability to provide space dynamics calculations.