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How do plutonium-powered pacemakers work?

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Re: How do plutonium-powered pacemakers work?

#51

Post by yummybear »

acidburnNSA wrote: post #8

FTA: > I wondered if there wasn't also worry about plutonium being recovered for weapons use, but the risk seems much smaller The answer here is a simple "nope." Plutonium in radioisotopic thermal generators is always Plutonium-238 with a 87.7 year half-life. You can't make bombs out of it. The fissile isotopes of Plutonium are 239 (24,000 year half-life) and 241 (14 year half-life, but a beta emitter instead of alph…

Isn't a 14 year half life very little for a bomb that should continue to work for decades?

Or isn't it actually used for it, but just CAN be used for it?

Re: How do plutonium-powered pacemakers work?

#53

Post by acidburnNSA »

yummybear wrote: post #51
acidburnNSA wrote: post #8

FTA: > I wondered if there wasn't also worry about plutonium being recovered for weapons use, but the risk seems much smaller The answer here is a simple "nope." Plutonium in radioisotopic thermal generators is always Plutonium-238 with a 87.7 year half-life. You can't make bombs out of it. The fissile isotopes of Plutonium are 239 (24,000 year half-life) and 241 (14 year half-life, but a beta emitter instead of alph…

Isn't a 14 year half life very little for a bomb that should continue to work for decades? Or isn't it actually used for it, but just CAN be used for it?

Yeah 241 is not commonly or ever used for weapons, it just could be. it's always easier and more practical to use u235 or pu239. Other fissile nuclides no one makes bombs out of include Americium-242m and Curium-244. Technically, sophisticated weaponeers can work with non-fissile but still fissionable nuclides like Pu240 but it's harder. But that's why the IAEA defines significant quantities of plutonium without specifying the isotopics.

Re: How do plutonium-powered pacemakers work?

#54

Post by AstralStorm »

Banthum wrote: post #40
Rjevski wrote: post #17

Earlier quoted context omitted.

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.

Liver also speeds up metabolism creating yet more heat.

Re: How do plutonium-powered pacemakers work?

#57

Post by rocqua »

dingo_bat wrote: post #39
fyfy18 wrote: post #37

Earlier quoted context omitted.

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.

Don't you start to get overheating phenomena at 40C?

Re: How do plutonium-powered pacemakers work?

#58

Post by WalterBright »

wolfgang42 wrote: post #18
Rjevski wrote: post #5

Earlier 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…

Biochemists at Caltech were studying photosynthesis back in the 70s, with an eye towards artificially replicating the process.

I see not much progress has been made.

Re: How do plutonium-powered pacemakers work?

#59

Post by c12 »

WalterBright wrote: post #58
wolfgang42 wrote: post #18

Earlier quoted context omitted.

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…

Biochemists at Caltech were studying photosynthesis back in the 70s, with an eye towards artificially replicating the process. I see not much progress has been made.

This is a paper from two years ago but it shows that progress is still being made in this field. http://science.sciencemag.org/content/352/6290/1210

Re: How do plutonium-powered pacemakers work?

#60

Post by rplnt »

Kelbit wrote: post #15
saagarjha wrote: post #2

How long to these pacemakers last? Have people had to get the plutonium "batteries" replaced?

Easier to replace the whole pacemaker than the battery, for a couple of reasons: * Pacemakers are hermetically sealed, usually laser-welded in a titanium case. Adding a replaceable battery with seals would complicate this arrangement. * By the time the battery winds down, there may be a newer, better pacemaker on the market that fits the patient's needs. * Since a battery replacement necessitates surgery, you might a…

Wouldn't wireless charging pad work well for this? Or is it unnecessary complicated considering how long batteries last?
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