Analysis of core configuration for conceptual gas cooled fast reactor (GFR) using OpenMC

This study focused on a conceptual core configuration of Gas Cooled Fast Reactor (GFR), as part of a generation IV reactor. Uranium-plutonium carbide (UC-PuC) was used as reactor fuel and a Monte Carlo simulation method using OpenMC has been carried out. This study aims to find the composition of uranium-plutonium carbide fuel to use inside a fuel pin, making up a hexagonal prism fuel assembly arranged to form an entire core. A homogeneous and heterogeneous core configuration was considered in this study, while the plutonium percentage varied from 8 %-15 %. For the homogenous core configuration, 10 % was found as the optimum plutonium fraction with the value of %Δk/k =1, which was then used as a reference to make up a heterogeneous core configuration. A heterogeneous core with 3 radial fuel regions of F1 using 9 % Pu fraction, F2 10 %, and F3 11 % showed the most stable result for 5-year burn-up with a %Δk/k of 0.7. The %Δk/k value was decreased by 0.3 due to the fission reaction that occurred more evenly in all 3 fuel regions of heterogeneous configuration, reducing the core power peaking factor. (author)