UoB_Tom_Scott

Thanks for your question - for waste graphite from our UK reactors the single biggest problem radionuclide is C-14. Most other radioisotopes have, in the majority, decayed away within 20 years of the reactors being turned off but the C-14 (with a half life of 5730 years) represents a more persistent problem.

You are indeed correct that we could use other radioisotopes that decay by beta emission e.g. Ni-63 or tritium. The emitted beta particle energies are different between these isotopes and hence this would make the device more or less effective. However, by sticking to C-14 we can grow a single diamond device which is isotopically layered between C-14, C-13 and C-12 in one single crystal structure. By doing this we avoid energy losses for electrical current generation which would otherwise occur by having a physical interface between the beta-emitting material and the diamond generator.

The exact costs for waste processing to retrieve C14 are not known, but are likely to dominate the cost of the device. The actual cost of manufacture of the devices once a suitable feedstock gas is available is relatively small and so should be economically viable. In addition, by harvesting the C-14 from waste irradiated reactor graphite we reduce the residual radioactivity level of the graphite and thereby significantly reduce the onward cost requirement for its disposal.

A great question! We sincerely hope that we can change public perception for the better. A common bugbear for the public around nuclear is that when you have nuclear power reactors you generate waste which is dangerous for a very long time. Our work shows that there is potential economic value to be extracted from a proportion of this waste. If we're successful, one day I hope we might refer to the irradiated graphite as 'battery feedstock' rather than waste.

I recently experienced a great example of changing perception when shortly after launching our technology at the @CabotInstitute annual lecture, an elderly lady approached me. She volunteered that she had been a campaigner against nuclear energy for 20 years and that our battery device and the associated concept of extracting value from the waste (whilst also making it safer) had changed her perception such that she now supported nuclear power as a preferred low-carbon alternative to fossil fuel burning!

The technology is still in development, but we have received a number of ideas from the public as to how this could be used in everyday life. Take a look at our recent blog which shares some of the ideas so far: http://cabot-institute.blogspot.co.uk/2016/12/the-diamond-battery-your-ideas-for.html. Let us know if you have any to add!

I'd also add that we have a different type of diamond device which works on harvesting energy from x-ray and gamma-ray photons. This is less efficient than the C-14 device but presents the possibility of a self powered monitoring device for use in highly radioactive environments. It also presents the possibility of creating a gamma-voltaic 'shroud' which could be lowered around a canister of high level nuclear waste to hook it up as a power unit. This is another potential benefit for the technology.