XBWR A ONE DIMENSIONAL XENON TRANSIENT PROGRAMME FOR BOILING NUCLEAR REACTORS

摘要

XBWR is a FORTRAN programme for the analysis of Xenon transients in axial geometry. It couples a two group neutron diffusion calculation in plane geometry with a two phase flow cooling channel calculation and the heat conduction in the typical fuel rod. The programme allows to follow any given power time schedule, such as shut-down and restart, day-night power variation etc., while the reactor is being kept critical by control rod movement, variable poison¬ing of the core, or coolant flow recirculation rate. The Xenon and Iodine concentrations variation is evaluated pointwise (up to 100 points) by analytical solution for successive fixed time steps. At the end of each time step a new distribution of fluxes, power, voids and temperatures is obtained, which is consistent with the reactor critical condition as it is got by variation of the control parameter taking into account the feedbacks. The new flux distribution is used as input for Xenon and Iodine concentrations evolution in the next time step.