WITHDRAWN: Burn-up and kinetics evolution of the Fixed Bed Nuclear Reactor using different fuel types

This article focuses on calculation of reactivity and kinetic parameters of the Fixed Bed Nuclear Reactor (FBNR), using different spherical fuel elements (TRISO, CERMET and simplified TRISO), which is investigated by the SRAC computer code. The fuel used is a uranium dioxide sphere (UO2) with different U235 enrichments. The purpose of this study is providing some calculated physics results of the FBNR with the different fuel types in order to can make a choice of sensible reactor configurations in the future, concretely: (1) The effective neutron multiplication coefficients increase to fuel enrichment for all the three fuel types. With fuel enrichment of 5% U235 the reactor operates for 997 days and 1975 days approximately for the TRISO and CERMET fuels respectively; but for the simplified TRISO fuel, it is still in a subcritical state. Therefore, using the simplified TRISO fuel it has to increase the fuel enrichment so that the reactor can operates. (2) The kinetic parameters (the prompt-neutron lifetime and effective delayed neutron fraction) of the reactor also are changed to fuel enrichment and fuel type. The values of those kinetic parameters are very important to determine reactor reactivity and power transients for safety and effectively operation of the reactor.