Earlier quoted context omitted.
Pu 238 doesn’t undergo spontaneous fission. It’s an alpha emitter.
How do you emit alpha particles without a nuclear process?
It’s a nuclear reaction. It just isn’t fission.
How do plutonium-powered pacemakers work?
31–40 of 87 posts
Re: How do plutonium-powered pacemakers work?
#32>Wikipedia says the technique was abandoned because of worries that the capsule wouldn't be absolutely certain to survive a cremation. (Cremation temperatures go up to around 1000°C; titanium melts at 1668°C.) You'd think they could switch to tungsten if that was the issue?
Titanium is nicely biocompatible. Tungsten can be poisonous. https://patient.info/doctor/tungsten-poisoning
Re: How do plutonium-powered pacemakers work?
#33Earlier quoted context omitted.
Not that long... or rather, it could work for a very long time but wouldn't be that useful because of the low power provided. From Wikipedia - https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge... Plutonium-238 has a half-life of 87.7 years, reasonable power density of 0.54 watts per gram - that's heat energy.And then there's math on that which has a rather low efficiency (somewhere around 23% for a stirlin…
Those numbers aren't that bad, actually. A cell phone's peak power draw isn't much more than 5W, so you'd need 10g / efficiency. At 10% efficiency, that's 100g, which is 5 cm^3 for plutonium. A cell phone battery is about 3 times that size, assuming 3000 mAh and an energy density of 600 Wh/L. Of course you'd have to build in a heat engine, but perhaps even a peltier would work given the generous efficiency allowance.
Also you don't need peak power all the time, you just need more than your average power draw combined with a battery big enough to smooth out the gaps. I'd think the biggest problem would be your phone being dangerously hot all the time.
Re: How do plutonium-powered pacemakers work?
#34Earlier quoted context omitted.
How do you emit alpha particles without a nuclear process?
It’s a nuclear reaction. It just isn’t fission.
Right. Pu238 alpha decay is aneutronic so it doesn't contribute to a chain reaction. However heating from too much Pu238 (or more importantly, Pu240) would be a heat removal/thermal challenge.
Re: How do plutonium-powered pacemakers work?
#35>Wikipedia says the technique was abandoned because of worries that the capsule wouldn't be absolutely certain to survive a cremation. (Cremation temperatures go up to around 1000°C; titanium melts at 1668°C.) You'd think they could switch to tungsten if that was the issue?
Titanium is nicely biocompatible. Tungsten can be poisonous. https://patient.info/doctor/tungsten-poisoning
Could you have an inner layer of tungsten to seal the plutonium, and an outer layer of titanium to avoid poisoning the host?
Re: How do plutonium-powered pacemakers work?
#36Earlier quoted context omitted.
Keeping nuclear material (safely) in your body is the easy part, the hard part is converting that energy into something your body can use. The issue is, our (badly designed) meat-hardware runs on glucose instead of heat or electricity, and there's no easy (or any way that I know of really, but then I'm not a scientist) to convert heat/electricity into glucose.
I went to a lecture recently by a researcher who is investigating the mechanisms of photosynthesis. The chlorophyll uses the energy from the photon to pump an electron, which (after a long and poorly-understood chain of reactions, which is what he was studying) creates an energy gradient which powers ATP synthase to produce ATP. Presumably if we understood and could recreate this reaction, we could create the electro…
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Re: How do plutonium-powered pacemakers work?
#37Earlier quoted context omitted.
Keeping nuclear material (safely) in your body is the easy part, the hard part is converting that energy into something your body can use. The issue is, our (badly designed) meat-hardware runs on glucose instead of heat or electricity, and there's no easy (or any way that I know of really, but then I'm not a scientist) to convert heat/electricity into glucose.
That's true but isn't 80% of our energy usage used to heat and regulate our body temp? I was wondering if we would then need less "food" for daily calories...
Where I live there is a rather large temperature change between summer and winter (usually 60 K, sometimes higher), and during the summer I definitely feel the need to eat less calories. However this may just be an emotional response rather than anything biological.
Re: How do plutonium-powered pacemakers work?
#38Dumb question, but would it be possible to have a nuclear-powered object in your body producing energy for your body to use?
I look forward to the day nuclear powered sustenance becomes a fad diet, and accidentally creating immortal zombies whose minds have expired before their bodies.
Re: How do plutonium-powered pacemakers work?
#39Earlier quoted context omitted.
That's true but isn't 80% of our energy usage used to heat and regulate our body temp? I was wondering if we would then need less "food" for daily calories...
Where I live there is a rather large temperature change between summer and winter (usually 60 K, sometimes higher), and during the summer I definitely feel the need to eat less calories. However this may just be an emotional response rather than anything biological.
Ambient temperature definitely affects calorie consumption. No doubt about it. Body burns more calories keeping organs at 37C if the exterior is 10C, compared to 40C.
Re: How do plutonium-powered pacemakers work?
#40Earlier quoted context omitted.
That's true but isn't 80% of our energy usage used to heat and regulate our body temp? I was wondering if we would then need less "food" for daily calories...
Isn't heat essentially a by-product of muscles "burning" the glucose? I'm not sure we actually need more heat besides what's already being generated as a by-product.
You need more if you're cold enough!
Go out in frigid weather with a T-shirt on. You'll soon shiver - your body is recruiting muscles to generate heat. But also, your "brown fat" cells will start pumping out heat as well.