Plutonium Powered Pacemaker (From 1974)

[acidburnNSA]

For context, the 0.1 rem yearly dose to the patient is about 1/6th of the average background dose we all get every year.

This Pu-238 is the same stuff that's powering the Voyager probes and a few Mars rovers.

Note that it's not Pu-239, which is fissile nuclear fuel for chain reactions (power plants, bombs, etc.)

[stinkbeetle]

> For context, the 0.1 rem yearly dose to the patient is about 1/6th of the average background dose we all get every year.

Wouldn't you be more concerned about dose rates in tissues near the device though, rather than whole body dose? At the surface of the pacemaker it would be about 90 rem / year.

[_kb]

Or approximately 100 bananas, for scale.

[ChuckMcM]

Yeah but their spouse :-) 75x larger dose.

[jandrewrogers]

> Dose rates at the surface of the pacemaker are approximately 5 to 15 mrem per hour from the emitted gamma rays and neutrons.

Where are these gamma rays and neutrons coming from? The decay chain for Pu-238 is via alpha emission (Pu-238 -> U-234 -> Th-230 -> ...) which won't penetrate the casing.

[acidburnNSA]

Not sure about neutrons. Gammas, or x-rays at least, could come from bremmstrahlung.

[pfdietz]

Alpha particles will produce secondary radiation occasionally when they hit light nuclei. The oxygen in the Pu oxide is almost entirely O-16 to minimize neutron production.

[Horffupolde]

Possibly Pu-239 or other impurities.

[cyberax]

All U and Pu isotopes undergo spontaneous fission, producing neutrons and random daughter products.

[bobmcnamara]

Some very small portion of Pu-238 will eventually pass through Tl-210 -> Pb-209.

[sanarothe]

For similar / further reading on historical pacemakers, check out https://www.implantable-device.com/category/implantable-comp... where David Prutchi has amassed what I think is a comprehensive history of pacemakers / neurostimulators ranging from these early atomic designs up through current day devices / companies.

[xattt]

More interesting to me is how this tech was programmed. There would have been some external unit to set parameters.

[userbinator]

Since it's from 1974, my guess is a few trimpots behind a sealed cover.

[anovikov]

Pu-238 in this thing would cost $14K in today's prices!