And so, if you look at the pictures, you'll see an interesting number denoting the quantity of plutonium powering the device. It's not measured in grams, or even micrograms, or any unit of mass, as would be common with ordinary materials. Instead, the quantity of plutonium is measured in curies.
And is there a means of converting curies to mass?
Well, sort of... except radioactive decay generally means the original mass of a sample of material has been steadily converting itself into something else over time, so to provide a measurement of mass might not be a practical piece of information later on, and given the application in these circumstances, the gross weight of the device is more relevant than the mass of the plutonium therein, and the power provided by the plutonium, and how hot the slug is, turns out to be the more interesting number.
So what's a curie?
The term "specific activity" is defined as the amount
of radioactivity - or the decay rate - of a particular
radionuclide per unit mass of the radionuclide. For
example, the specific activity of Ra-226 is 1, meaning
that one gram of Ra-226 contains one (1) curie (assumed
to be uniformly distributed throughout that mass)
http://www.iem-inc.com/information/tools/specific-activities
And, so based on all those pictures, the devices seem to average ~2.0 to ~4.3 curies of plutonium.
The specific radioactivity of plutonium, according to the above source, is:
Pu-238 - 1.7E1
So, approximately one or two grams per device.
Based on all this information, I bet harvesting plutonium pacemakers would be way more lucrative than stealing kidneys.
A very interesting document. Unfortunately you can't trivially copy-paste text from it, so instead I'll like to direct readers to page 4, to the text that starts below figure 5. It seems that most of the size/weight of the nuclear pacemaker was because of shielding, that was designed to withstand even an airplane crash or getting hit by a bullet - all because plutonium is a substance from hell that will kill you if you let it in your blood or expose to air. OTOH radiation was not a concern, measured levels under normal operation were way below safety limits.
I wish more devices could make use of something like this. In sure there are other safety concerns involved but I'd love to replace the forever dying AA batteries in my mouse with one of these and forget about it forever. What does a nuclear battery cost I wonder...
And is there a means of converting curies to mass?
Well, sort of... except radioactive decay generally means the original mass of a sample of material has been steadily converting itself into something else over time, so to provide a measurement of mass might not be a practical piece of information later on, and given the application in these circumstances, the gross weight of the device is more relevant than the mass of the plutonium therein, and the power provided by the plutonium, and how hot the slug is, turns out to be the more interesting number.
So what's a curie?
And, so based on all those pictures, the devices seem to average ~2.0 to ~4.3 curies of plutonium.The specific radioactivity of plutonium, according to the above source, is:
So, approximately one or two grams per device.Based on all this information, I bet harvesting plutonium pacemakers would be way more lucrative than stealing kidneys.