no such thing as waste: high quality input -> low quality output, transformation by another system, middle quality input -> lower quality output, repeat -> heat death of the universe

New Atlas | Diamonds turn nuclear waste into nuclear batteries

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How to dispose of nuclear waste is one of the great technical challenges of the 21st century. The trouble is, it usually turns out not to be so much a question of disposal as long-term storage. If it was simply a matter of getting rid of radioactive material permanently, there are any number of options, but spent nuclear fuel and other waste consists of valuable radioactive isotopes that are needed in industry and medicine, or can be reprocessed to produce more fuel. Disposal, therefore is more often a matter of keeping waste safe, but being able to get at it later when needed.

One unexpected example of this is the Bristol team's work on a major source of nuclear waste from Britain's aging Magnox reactors, which are now being decommissioned after over half a century of service. These first generation reactors used graphite blocks as moderators to slow down neutrons to keep the nuclear fission process running, but decades of exposure have left the UK with 95,000 tonnes (104,720 tons) of graphite blocks that are now classed as nuclear waste because the radiation in the reactors changes some of the inert carbon in the blocks into radioactive carbon-14.

Carbon-14 is a low-yield beta particle emitter that can't penetrate even a few centimeters of air, but it's still too dangerous to allow into the environment. Instead of burying it, the Bristol team's solution is to remove most of the c-14 from the graphite blocks and turn it into electricity-generating diamonds.

The nuclear diamond battery is based on the fact that when a man-made diamond is exposed to radiation, it produces a small electric current. According to the researchers, this makes it possible to build a battery that has no moving parts, gives off no emissions, and is maintenance-free.