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UK scientists generate electricity from Americium to power future space missions (nnl.co.uk)
60 points by okket 18 days ago | hide | past | web | favorite | 25 comments


There is a nice table that shows, that Americium-241 has low power density, but it's half-life is 432 years. It also mentions that the real reason, why this is interesting, is because Am-241 is a byproduct and a pure isotope that can be used without refining.

Of course, power density is inversely proportional to half-life. Low power density BECAUSE the half-life is 432 years.

> power density is inversely proportional to half-life

It's not that simple. The energy per event varies by orders of magnitude depending on the specific transition (even within given particle decays, the energy of the emitted particle varies), also the number of atoms per volume or mass varies depending on material.

Clearly. However it IS a good approximation. For RTGs, we desire primarily alpha emitters as alpha particles are generally the easiest type of decay product to shield (the thin metal casing will stop all alpha particles). And common Alpha emitters such as Po-210, Am-241, Pu-238, and U-232 all have a decay energy of about 5-6MeV even though they differ in half life (and thus power density) by 3 orders of magnitude.

The approximation holds true for the heavy elements, with similar atomic mass. I wonder if the power density of any similar half-life lighter nuclei would be significantly greater, or whether the energy of decay reduces roughly proportionately with their mass.

And, of course, almost all alpha emitters are heavier elements: https://www.researchgate.net/profile/Adam_Woolsey2/publicati...

> that can be used without refining

It has to first be separated from the rest of the actinide waste, which is very challenging, as they're chemically similar elements. Previously this had to be done with a centrifuge (separating by mass), but a lot of research effort has gone into developing more practical chemical refining methods.

Americium-241 can be found in smoke detectors which came into the headlines when a kid tried to build a nuclear reactor in his backyard back in 1996:


A lot of newer smoke detectors work on a photo-electric principle rather than by ionisation. That means they don't contain anything radioactive, and also tend to be more effective because they're less prone to false alarms.

I believe those are « fire detectors » as they sense the flickering light of a fire.

Flame detectors work via video feeds typically and analyze a video for flame and smoke patterns. Those come in both stand alone detectors and systems that work off of existing security camera feeds. (see also UV based detection)

They were referring to a photoelectric smoke detector vs ionization types. Both are still available but photo is much more common now days. They look exactly the same exterior wise, but it works by having a tiny light box where smoke goes in and changes the light the sensor is seeing. They can still cause false alarms because they are sensitive to dust and particulate matter, but they operate on intelligent addressable systems now which can adjust their sensitivity to some degree over time.

No. Those might exist too, but photo-electric smoke detectors definitely detect smoke.

Interesting person - he was actually making a Neutron Source rather than a reactor: https://en.wikipedia.org/wiki/David_Hahn#Creation_of_the_neu...

So is this essentially an RTG powered by Americium instead of Strontium or Plutonium? Or is this pioneering a new method of operation compared to a traditional RTG?

>>> used the heat generated from this highly radioactive material to generate enough electric current to light up a small lightbulb ...

Sounds like an americium-powered RTG to me, albeit not a particularly powerful one.

Powering a lightbulb for 432 years? Sign me up.

I don't think the power generation part of this is a breakthrough at all, just a "proof of the pudding is in the eating" demonstration.

As I understand it, the practical refinement of a significant amount of Americium from waste is the breakthrough. But that doesn't win hearts and minds like a 432 year space lightbulb.

> So is this essentially an RTG powered by Americium instead of Strontium or Plutonium?

That is the idea. Plutonium RTGs are very hard to get by. As in only the U.S. have a few such RTGs in stock and I am not sure they are producing new ones.

I cannot express how disappointed I was to learn that they are just using the americium as a heat source, and not converting the kinetic energy of the alpha particles directly to electric current by induction.

The video embedded in the article plays like a movie trailer or an extended ad for a pharma company. Cool science though.

I always get a little tingle up my spine when I hear someone in a video append an isotope number to a chemical element. Cool beans.

Very interesting ... I wonder when did they start to work on this? and how long until we see this in use?

These (Americium RTGs) work pretty good in Minecraft (specifically Enigmatica 2 Expert Mode). Reliable, decent power output, zero maintenance. Not got as far as orbit yet, but I expect to take at least one of these with me to power the spacecraft.

Didn't expect to see that mentioned here, playing that myself currently.

The article says it is a thermoelectric generator.

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