This work investigated the neutronics behavior and the economics of the HYLIFE-II reactor with ThF4 and UF4, which produces an electrical power of 1 GW from the fusion power of 2.857 GW during the operation period of 30 years. The use of ThF4 and UF4 is realized by a mixture zone consisted of 90% flibe (Li2BeF4) and 10% fuel, instead of 100% flibe coolant. The mixture compositions are selected as 90% flibe + 10% UF4, 90% flibe + 10% ThF4 and 90% flibe + 5% UF4 + 5% ThF4. The capacity factor of the reactor is 0.75. The mixtures, with zone thickness of 65 cm were circulated with periods of 20.22, 19.89 and 20.11 s during the operation period of 30 years, respectively. In addition, for flibe + UF4, power stabilization by means of plutonium separation from the mixture was applied.