Not a good hobby.

Some elements, including plutonium, are not good to have around. Plutonium is flammable, poisonous, and radioactive. Also, in the past, people have accidentally put too much plutonium in a small space, creating a critical mass and exposing themselves, very quickly, to a lethal dose of radiation (gamma and neutrons). It's dangerous stuff.

It's possible to make plutonium by exposing uranium 238 (most uranium found in nature is 238) to a source of neutrons. The uranium nucleus absorbs a neutron, spits out two beta particles, and becomes a plutonium 239 nucleus. This is how plutonium for nuclear weapons is usually created. You can also fuel nuclear reactors with plutonium.

When it's used to make nuclear warheads for submarine-launched ballistic missiles, it's necessary to remove traces of plutonium 240. Plutonium 239 is so radioactive that it's actually warm to the touch. Plutonium 240 is even more radioactive. If it hadn't been removed from the warheads in our missiles, the upper level of our missile compartment would have been impractical to enter. That would have been a problem.

[Our reactor, which powered the submarine, used uranium 235. That's much easier to work around safely than plutonium.]

Banning the creation of plutonium 239 would be one way to make it much harder to build nuclear weapons.

Almost no plutonium occurs in nature. Mostly what there is forms from the natural decay of uranium 238. (The neutrons released in the decay are absorbed by other uranium 238 nuclei.) plutonium 239 has a short half life so it doesn't accumulate.

Another element that pretty much doesn't exist in nature is americium. Americium 241 is created by getting a plutonium 239 nucleus to absorb two neutrons and spit out one beta particle.

Americium is used in smoke detectors. No kidding. You probably have some in your home.

It's safer than plutonium 239 (most things are) because it decays with just alpha particles, not gammas and neutrons. Paper is actually an adequate shield against alpha radiation. However, if you get some alpha-emitting element in your lungs, it will just keep emitting alphas until it eventually causes cancer. I don't see a warning on my smoke detector about the problem of safely disposing of the thing. I think there should be one.

The amount in the smoke detector is very small. About 0.29 micrograms. A microgram is one millionth of a gram.

In 1994 a teenager tried to build a breeder reactor with the americium from about 100 smoke detectors (and other radioactive elements from camping lantern mantles, gun sights, and old clocks). There's a book about him called The Radioactive Boy Scout. (He was an Eagle Scout. He's dead now, from drugs and alcohol. His name was David Hahn.)

soil in your garden

Might have to be a very big garden.

Rickover’s regulations back in the Navy were based on the sensible idea that, if you can get less exposure and still operate the propulsion plant, that’s what you should do.

Our limit back in the 1970s was 300 millirem a year and 100 in a calendar quarter. If you’re not used to rem, 1 rem is 0.01 sievert. So 100 millirem is 0.001 sievert, or 1 millisievert.

Everyone on the submarine wore a thermoluminescent dosimeter (TLD). Nuclear weapons people and nuclear propulsion people like me got more exposure at sea than on land at sea level. People who stood watch in the operations compartment actually got less than on land because the ocean and the hull of the submarine shielded them.

My total occupational exposure was 600 millirem. According to this epa.gov/radiation/radiation-so… that’s less than the average American in a year. Some of these sources on this web page don’t apply to me at all. Half of exposure medical? I don’t get any medical exposure. I probably get a lot less medical care than most people, though.

I was at sea on that submarine for a total of only about 16 to 17 months. (A standard deterrent patrol was 10 weeks.) I trained on a prototype in Idaho for between 5 and 6 months. Exposure there, believe it or not, was measured with film badges.