核燃料再处理技术原指用化学分离和纯化的方法从经过辐照的核燃料中分离可裂变的钚同位素。 但现代核燃料再处理已不仅仅着重于回收钚，还可以分离其它有用的元素，比如铀、甚至贵金属。

再处理技术有多重目的，其重要性随着时代变化而起伏。起初，核燃料再处理的唯一目的是分离可以用于制造原子弹的钚。随着核电站的普及，乏燃料越来越多，于是钚被作为核燃料用于热中子堆。含有钚的混合氧化物核燃料能够产生更多的电力，同时还能够消耗一部分钚。 占乏燃料绝大部分的再处理铀可以用于快中子增殖反应堆。理论上，快中子堆还可以燃烧锕系元素。但是在铀价低廉的时代，快中子堆商业化面临很多困难。

Nuclear reprocessing technology was developed to chemically separate and recover fissionable plutonium from irradiated nuclear fuel. Reprocessing serves multiple purposes, whose relative importance has changed over time. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With the commercialization of nuclear power, the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors. The reprocessed uranium, which constitutes the bulk of the spent fuel material, can in principle also be re-used as fuel, but that is only economic when uranium prices are high. Finally, a breeder reactor is not restricted to using recycled plutonium and uranium. It can employ all the actinides, closing the nuclear fuel cycle and potentially multiplying the energy extracted from natural uranium by about 60 times.