The use of minor actinides and a small power proto ~ accelerator for fast reactor with a high breeding gain . (

We propose the use of a proton accelerator to run a slightly subcritical fast breeder and incinerator of minor actinides, and also the use of minor actinides to make a high bumup t%el, which can be burned in a reactor with a non-flattened core with a ratio of height to diameter (H/D= 1). By injecting medium-energy protons into a subcritical assembly, and by supplying external neutrons produced by spallation and by high-energy fission reactions, the reactor can be operated in a safer condition than a reactor operated in a critical condition. The safety problems associated with super-criticality, which might be created by factors, such as a positive Na-void coefficient and fuel bowing, can be alleviated. The metal-fueled fast breeder has small decrement in the reactivity of power and bum-up; the reactivity decrement of the oxide fuel reactor can be reduced substantially by mixing the MA of ‘7Np with the oxide-fuel. Thus, these reactors can be operated at a sub-criticality of k=O.99 with small beam proton power of 15 rnA and 1 GeV energy (15 MW). This slightly subcritical condition makes the power distribution more or less flat, which is important from the point of view of reactor safety. MA can be also used for achieving high fuel bum-up. This reactor requires a small inventory of fissile material and has large breeding gain. Thus, we suggest using Np237 to improve the characteristic of the fast reactor rather than simply incinerating this valuable commodity. Because of its small requirement for beam current, the cyclotron can be used instead of the linear accelerator, and the linac can be used for running many reactors by splitting the high cument beam. In the appendix we discuss alternative way to dispose of high level waste into the Antarctic icefield, the moon and outer space.