On the starting and operational transients at the core of the RMB based on 2D multigroup diffusion

RMB is a multipurpose reactor to be built by CNEN. As a multipurpose facility, unlike a nuclear power plant, some operations may result in transients, whether during the movement of materials from remote irradiation, extraction of neutrons through beam holes, reactor starting up, control rod accident, etc. For that, a methodology to visualize some variables like neutron fluxes, temperatures, power, etc., was developed. In this one present some preliminary results based on multigroup diffusion theory, thermal hydraulics feedbacks, and numerical methods, systematized in the DINUCLE code. DINUCLE couples a numerical code of multigroup spatial kinetics, for calculations of the flux of neutrons in the core of reactors, with a numerical code for the analysis of thermo hydraulic transients in rods and plates, considering the refrigerant always single-phase. Use was made of a programming in VBA (Visual Basic for Applications) from Excel, for data visualization in the transient.