In this paper, in order to produce high-energy neutrons, the design of a compact, portable and high efficiency reactor based on a plasma focus device is investigated. The COMSOL Multiphysics software was used to investigate and optimize 16 plasma focus devices with different stored energies for producing neutrons. To keep the fission reactor at the subcritical condition, fuel assembly containing a specific combination of fission fuel of [Formula: see text]U – [Formula: see text]Pu was used. As a result of energetic neutrons produced in the plasma focus device, no radioactive waste remained in the reactor. In addition, an efficient gas cooling system that absorbed and transferred heat was designed using the COMSOL Multiphysics software. The absorbed heat was transferred to the thermo-photo-voltaic converter, and thus electricity was generated with an efficiency of about 40%. Electrical and thermal energies are calculated in each shot for every plasma focus device. Finally, we showed that high frequency plasma focus devices had a high potential to produce energy.