Energy may possibly be released in purely fissionable materials or in mixtures of fission/fusion materials following irradiation to produce compression and heating leading to micro-explosions. This is a variation of the “laser-fusion” concept A design of a pellet is presented that consists of a fissionable trigger and a mantle of fusionable material. Sophisticated neutronics and burnup calculations for the fission trigger show that such a device possesses a substantially higher “gain” than a purely fusionable pellet. This may open a new outlook for the peaceful utilization of nuclear energy through a breeder reactor system with an extremely short fuel doubling time and with the possibility of directly converting the released energy into electricity. Furthermore, the fission trigger may be used to kindle not only DT and LiD mantles but also DD and probably p-11B mantles to full thermonuclear ignition.