Environment & Energy
Related: About this forumA Diamond Battery (Carbon-14 based) to Run for Millenia.
If one attends, as I do, lectures at the Princeton Plasma Physics Laboratory, during the "Science on Saturday" series, one will see a bunch of videos running before the lecture on the applications of plasma. One of them involves growing diamonds.
We do not have a lot of 14C on this planet, some, but not a lot. We could have a lot of it if we were to use nitride nuclear fuels from the 14N(n,p)14C nuclear reaction, and I often muse about this, as the nuclear properties of 14C are interesting. It has a very low, close to the zero of 4He, neutron capture cross section. It is a (slightly) less efficient neutron moderator, allowing for the shift of a neutron spectra toward the epithermal as opposed to the thermal spectrum, useful for higher actinide utilization. That might be of interest decades from now, long after I'm dead; it is impossible to realize now.
I came across this cute bit from one of my news feeds relating to an existing source of 14C:
The UK Took the Reactor Graphite It Was Going to Bury for Millennia, Drove the Radioactive Carbon Off as Gas, and Sealed It Inside a Diamond That Now Trickles Electricity on a 5,700-Year Clock
An excerpt:
Scientists and engineers at the UK Atomic Energy Authority and the University of Bristol have built what they say is the worlds first carbon-14 diamond battery. The short version: they pull radioactive carbon out of old reactor graphite, grow it into a synthetic diamond, and let the stones own radiation generate a trickle of electricity. No recharging, no moving parts, no maintenance. The catch, and it is a big one, is how small that trickle is, and we will get to that. But the core claim holds up. A battery built around carbon-14 keeps producing power on a timescale of thousands of years, long after the device it sits inside has stopped existing.
It runs on the part of a reactor nobody wants
Older reactors use big blocks of graphite to moderate the nuclear reaction. Over years of bombardment, carbon atoms inside those blocks get transmuted into carbon-14, a radioactive version of ordinary carbon. When a plant is decommissioned, the graphite comes out as waste that has to be stored, and the UK alone is sitting on roughly 95,000 metric tons of it.
The useful discovery, made by the University of Bristols diamond battery team, is that the carbon-14 concentrates near the surface of those blocks. That means you can heat the graphite and drive most of it off as gas rather than reprocessing the entire block. Pull the carbon-14 out and the leftover graphite is less radioactive, which downgrades it from intermediate-level waste to low-level waste and makes it cheaper and simpler to store. As Bristol materials professor Tom Scott put it, the goal is to turn a long-term problem of nuclear waste into a nuclear-powered battery. It is worth being precise here. Carbon-14 is only a small part of what makes nuclear waste hazardous, so nobody is claiming this empties the storage vaults. It goes after one specific, awkward material...
The caveat of the last sentence strikes me as disingenuous, since I personally believe - rather iconoclastically I concede - that there is no such thing as "nuclear waste," and that the claim that there is such a thing is a psychological artifact and the result of a lack of imagination. To my mind, being aware of pretty much every component of used nuclear fuel, every element and nuclide therein, that there are only two types of materials in used nuclear fuel and reactor components, useful radioactive materials and useful non-radioactive materials.
Nonetheless, I rather like the thinking here, putting a radioactive material to use. Note that this idea is not "new." 237Np, the only isotope of neptunium found in used nuclear fuel is considered "nuclear waste." For decades however, it has been transmuted into 238Pu which has powered every deep space mission ever sent beyond the orbit of Mars, and some within the Martian orbit.
The "batteries" are not actually batteries in this case, and the language is sloppy. They are generators. They produce exergy, they do not destroy exergy as batteries do.
The articles note that the diamond batteries are tiny and no, they won't power your precious electric car for which you are willing to sacrifice everything, even the planet, to have. Often when discussing nuclear issues here I have to deal with the bourgeois car fetish, which is easily dismissed.
Have a nice weekend.
Easterncedar
(6,656 posts)eppur_se_muova
(42,911 posts)Standard commercial C-13 enrichment is done by CO distillation; an even higher enrichment factor should be obtained for C-14. Of course, you don't need very high enrichment levels to build a more powerful battery for low-current applications. There are probably enough C-13 enrichment columns in the world that one could certainly be diverted for just C-14 enrichment.
https://nsc.jp.nipponsanso.com/Portals/0/resources/en/rd/giho/pdf/41/tnscgiho41_E07.pdf
(Compares CO vs CF4 distillation)
NNadir
(38,875 posts)Over the years, I've sourced a lot of heavy isotope labeled compounds, never 14C. Generally in our lab we're looking for deuterium labeled, but it does happen sometimes we need to appeal to 13C. Up around a MW of 500, one starts to get interferences from the 1% natural 13C.
If I were looking to get 14C, I think it would be wise to avoid irradiated graphite in favor of neutron irradiated 14N, which would produce it pure out of the box.
I'm not sure though how it's done, but the use of 14C was pretty common at one point, and may still be practiced in places, thus the separation, if required in lieu of the 14N(n,p)14C reaction must be well known and widely practiced. The neutron method would offer the advantage of depleting 14N and thus enriching the low levels of 15N in natural nitrogen.
13C is easier to handle though and again, mass spec can follow it pretty well, as can NMR. There are means to recover enough labeled compound by extraction for NMR with solid phase extraction, particularly if one is willing to invest a lot of accumulation time on the instrument.
Mass spec is faster and cheaper though, assuming one has paid for the mass spec.
Both mass spec and NMR of course, offer structural information in DMPK settings, where as 14C only offers organ distribution.