© 2015 Atomic Energy Society of Japan, All Rights Reserved. A study on reduction of potential radiotoxicity for spent fuel by using high-temperature gas-cooled reactors (HTGRs)has been performed. Unlike partitioning and transmutation (P&T), the reactor concept is investigated from the viewpoint of reduction of radiotoxicity generation itself. To reduce radiotoxicity, <sup>238</sup>U, which generates Pu, Am and Cm, should be excluded. Therefore, we proposed HTGR fueled by new-concept fuels with alternative fuel matrixes instead of <sup>238</sup>U. Those are yttria-stabilized zirconia (YSZ)and thorium, and the fissile material is highly enriched uranium (HEU)with an enrichment of 93%. With HEU, the radiotoxicity can be significantly reduced, and the cooling time to decay to a natural uranium level can be shortened to approximately 800 years. Fuel integrity and proliferation resistance can be maintained by dilution using YSZ, and the neutronic characteristics of self-regulation are maintained by the loading of erbium. The fuel can generate the same amount of heat as ordinary uranium fuel. The electricity generation cost is as cheap as GTHTR300. It is concluded that the proposed reactor concept can reduce the cooling time by less than 1% from 100 thousand years to 800 years without additional development of innovative technology.