Using Stirling Americium RTG for Space Station electricity

[Kryten]

Is Sr 90 common enough for lunar and station operations?

It's near pure beta, so harder than contain than alpha sources like Pu-238. It should be kept in mind that this makes it harder to handle at all stages of purification and production, which has adverse affects on the cost.

[sgt_flyer]

Still - why only RTGs or stirling engines ?

There are other techniques under devellopment (like https://en.m.wikipedia.org/wiki/Optoelectric_nuclear_battery) which offer good energy density - without needing the mechanisms of a stirling. (Though those come with their own downsides - like having to launch the radioisotope separated from the generator in it's own secure reentry capable container (as the generator use high pressure gases) - and assembling once in space. Still, it's not the kind of stuff you want near live people (especially in the amounts needed for something as big as a manned space station)

[Requia]

AM 241 is *really* radioactive relative to its heat output, radiation shield mass is a concern even for unmanned spacecraft. If you need the heavy shield and 'do not let this reenter under any circumstances' protocol you may as well use a proper reactor on a manned vessel (for unmanned there's a problem with needing to refuel, though Prometheus was targeting a 20 year mission so its still possible). Doubt you can beat solar in LEO though.

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That optonuclear thing is pretty neat looking, the decay chain of strontium 90 is almost entirely beta radiation, the gamma is pretty much insignificant. Solves the shielding problem nicely since the whole goal is to capture the energy of the beta radiation anyway.

Edited September 19, 2015 by Requia