if we stuck a suitably shaped non-critical amount of plutonium in the firebox.
Non-critical? There isn’t much energy released from natural decay compared to criticality. We created things like this to power space probes like the Voyager I and II craft. 4.5kg of this Plutonium created about 2500w of thermal energy the the beginning of its life and the power declines from there.
Well, you’d then have another problem. Unlike coal/wood/oil fuel, you can’t turn off radioactive decay.
You’d have megawatts (gigawatts?) of thermal energy boiling off all your water pretty quickly, and likely eventually melting down your steam engine firebox, and it would be that hot for decades!
You can boost it by hollowing out the middle and filling it with tritium, but plutonium is dense, so 80 tons will probably fit in the firebox just fine.
It’ll heat up the firebox, which is exactly what the firebox wants to happen. It’s not like we’re using precisely-timed explosives to briefly make the mass much more than critical and counter its desire to blow itself apart for long enough that it blows other things apart, too.
Non-critical? There isn’t much energy released from natural decay compared to criticality. We created things like this to power space probes like the Voyager I and II craft. 4.5kg of this Plutonium created about 2500w of thermal energy the the beginning of its life and the power declines from there.
source
So I need 80 tons of it in my firebox?
Well, you’d then have another problem. Unlike coal/wood/oil fuel, you can’t turn off radioactive decay.
You’d have megawatts (gigawatts?) of thermal energy boiling off all your water pretty quickly, and likely eventually melting down your steam engine firebox, and it would be that hot for decades!
You can boost it by hollowing out the middle and filling it with tritium, but plutonium is dense, so 80 tons will probably fit in the firebox just fine.
I feel like there’s a thing that will happen when I put that much in such a comparatively small place.
It’ll heat up the firebox, which is exactly what the firebox wants to happen. It’s not like we’re using precisely-timed explosives to briefly make the mass much more than critical and counter its desire to blow itself apart for long enough that it blows other things apart, too.