Abstract: This study reviews the development history of gaseous fuel reactors and investigates design schemes and critical facilities in the United States and Russia, demonstrating the feasibility of gaseous uranium hexafluoride (UF₆) fueled reactors without insurmountable technical barriers. While such reactors exhibit disruptive characteristics including direct burning, online fuel cycling, deep burnup capability, and inherent fuel meltdown prevention. Notwithstanding their potential benefits, the development of gaseous fuel reactors presents substantial engineering challenges that require resolution, such as flow critical safety, turbulent mixing, fuel physicochemical properties, material compatibility. With the imperatives decarbonization trend of global energy and advancing deep-space exploration requirements, gaseous fuel reactors present potential applications in new generation of ground nuclear plants, space nuclear power systems, hydrogen production plants, and reactor-pumped lasers. And gaseous fuel reactors could strategically complement conventional nuclear energy development roadmaps. A 2 MWth space exploration gaseous fuel reactor (SEGFR) was proposed that use gaseous UF₆ as both fuel and coolant. The Monte Carlo program MCNP was used to study and calculate its physical properties. Through systematic material evaluation and core configuration optimization, critical parameters of reactor were analyzed. The neutronic calculation results indicate that the proposed scheme is a thermal-neutron spectrum. The preliminary configuration demonstrates satisfactory reactivity equilibrium, with both initial excess reactivity and shutdown margin fulfilling normal operational requirements. The negative Doppler effect ensures inherent safety through prompt negative temperature feedback. Subcriticality exceeds 1%Δk/k across operational scenarios while satisfying the stuck drum criterion. The optimized 20 days refueling cycle ensures adequate reactivity margins while preserving operational flexibility within the design envelope. Overall, the core design in this paper is reasonable, and the neutron characteristics meet the requirements of reactivity balance, which can provide reference for the design of gaseous fuel reactors.