The Code DYN3D/M2 for the Calculation of Reactivity Initiated Transients in Light Water Reactors with Hexagonal Fuel Elements -Code Manual and Input Data Description-

The code DYN3D/M2 is used for investigations of reactivity transients in cores of thermal power reactors with hexagonal fuel elements. The 3-dimensional neutron kinetics model HEXDYN3D of the code is based on a nodal expansion method for solving the two-group neutron diffusion equation. The thermo-hydraulic part FLOCAL consists of a two-phase flow model describing coolant behaviour and a fuel rod model. The fuel elements are simulated by separate coolant channels. Additional, some hot channels with power peaking factors belonging to chosen fuel elements can be considered. Several safety parameters as temperatures, DNBR and fuel enthalpy are evaluated. Macroscopic cross sections depending from the thermo-hydraulic parameters and boron concentration are input data of the code. The stationary state and transient behaviour can be analyzed. The arrangement of input data are descibed for using the different option of the code.