Core design selection for a long‐life modular gas‐cooled fast reactor using OpenMC code

Summary This paper discusses design selection with variation of the height‐to‐diameter (H/D) ratios and core‐blanket configuration for a long‐life modular gas‐cooled fast reactor (GFR). The modular GFR is a nuclear reactor concept that proposes a longer operation time than a traditional nuclear reactor. The potential advantage of GFRs is the expected technological application in electricity, heat processing, nuclear burning, and breeding capability. However, the GFR design still needs an investigation to find the prospective core configuration design. The main objective is to understand the feasible design of long‐life modular GFR using the OpenMC code. The OpenMC is an open‐source Monte Carlo code that offers the exact solution to solve the neutron transport equation in a high‐fidelity model and detailed three‐dimensional geometry using Evaluated Nuclear Data File (ENDF/B‐VII.1/V2) nuclear data and continuous energy. The H/D ratios give various core‐type, that is, pancake, balance, and tall core, while core‐blanket configuration explains different core layouts, that is, homogeneous, radial heterogeneous, and axial heterogeneous. The neutronics parameters characterized are the value of keff, fission reaction rate, neutron flux, fissile and fertile material, and conversion ratio distribution to know the optimum core design. The study implemented the traditional mesh tallies for the fission reaction rate distribution and the functional expansion tallies (FET) for the flux distribution. The FET feature used the Legendre polynomial for the axial calculation, whereas the Zernike polynomial for the radial calculation. Finally, the balance core‐type with homogeneous configuration is the prospective design for advanced research.