A new fuel cycle concept - waste-free, intrinsically safe, and efficient (WISE) - based on a "clean" nuclear plant using mobile fuel (MF) is proposed. WISE does not perturb the radiological equilibrium by minimizing transuranium and long-lived-fission product wastes. The main characteristic of WISE is the use of MF systems and of a feed-and-bleed fuel cycle strategy. Irradiated fuel together with fission products always remains inside a WISE core. This implies no release of waste until fuel reserves are available. After the fuel reserves are exhausted, an on-line reprocessing technology can be applied in order to minimize waste.