
UK scientists generate electricity from Americium to power future space missions - okket
https://www.nnl.co.uk/2019/05/uk-scientists-generate-electricity-from-rare-element-to-power-future-space-missions/
======
karulont
[https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Criteria_for_selection_of_isotopes)

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.

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

~~~
gnode
> 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.

~~~
Robotbeat
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.

~~~
gnode
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.

~~~
Robotbeat
And, of course, almost all alpha emitters are heavier elements:
[https://www.researchgate.net/profile/Adam_Woolsey2/publicati...](https://www.researchgate.net/profile/Adam_Woolsey2/publication/328224660/figure/fig1/AS:680541158383618@1539265064126/Chart-
of-Nuclides-showing-different-types-of-radioactive-decay-2.ppm)

------
jnord
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:

[https://www.dailymail.co.uk/news/article-2506549/Uh-oh-
Radio...](https://www.dailymail.co.uk/news/article-2506549/Uh-oh-Radioactive-
Boy-Scout-built-nuclear-reactor-Detroit-shed-sparking-evacuation-40-000-wants-
invent-lightbulb-lasts-100-years.html)

~~~
Reason077
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.

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

~~~
officeplant
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.

------
mrkstu
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?

~~~
sandworm101
>>> 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.

~~~
imglorp
Powering a lightbulb for 432 years? Sign me up.

------
ncmncm
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.

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

~~~
grizzles
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.

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

------
tialaramex
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.

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

------
pngai
The article says it is a thermoelectric generator.

