Who can own plutonium?
Hey Dr Zoomie, what’s this about an Aussie getting arrested (or maybe he was threatened with an arrest?) just for wanting to collect all of the chemical elements?
It does seem a little odd, doesn’t it? I mean, I’m breathing air right now and that’s a mixture of three main elements (nitrogen, oxygen, and argon) with traces of radon. If I dig up some dirt in the yard the shovel’s going to contain carbon, hydrogen, oxygen, silicon, aluminum, uranium, radium, phosphorus, nitrogen, and a bunch more; seawater contains sodium, chlorine, and traces of virtually every other element in the Periodic Table, including uranium, plutonium, and americium. So (I hear you musing) – if we can safely breathe the air, drink the water, swim in the ocean, and dig in our gardens…why can’t I own every single chemical element?
Part of the problem is that there are a lot of chemical elements that are deadly when they’re purified, but safe when combined with other elements. I sprinkled two of these on my vegetables at dinner this evening – sodium (which reacts explosively with water) and chlorine (which has been used in chemical attacks throughout the Middle East in the last several years). So, sure, you can buy table salt in any grocery store and you can add it to your food – but if you buy elemental sodium you need to store it immersed in oil to keep it from bursting into flame or exploding. And to buy more than small amounts of low concentrations of chlorine gas can require a permit because large volumes of high concentrations of the gas can hurt or kill a lot of people.
Again – there are a lot of chemical elements that are safe in some chemical compounds but deadly in their pure form.
Some gases (such as He, Ne, Ar, Kr, Xe, and N) will smother us by displacing oxygen from the atmosphere; some gases (such as F, Cl, Br). Arsenic, mercury, thallium, and cadmium are toxic; beryllium will destroy our lungs, Na, K, Rb, and Cs catch fire or will explode in the presence of water, lead and uranium are heavy metals, and then there’s all the radioactive elements – and that’s where a guy in Australia got in trouble.
Every chemical element heavier than lead is either partially or totally radioactive. Bismuth is the former – it includes both stable and radioactive isotopes – while radium, thorium, uranium, plutonium, and every other heavier element contains only radioisotopes. And to own radioactive materials beyond exempt amounts, you’ve got to have a license.
In the US, for example, uranium and thorium are considered “source materials” that are regulated by the Nuclear Regulatory Commission. I’m allowed to own some uranium and thorium – what’s called an “unimportant quantity” – but to have anything more than that I need to have a radioactive materials license. So if I have rocks containing more than “one twentieth of one percent by weight” of uranium or thorium I’m OK – but if I get out my chemistry set and remove the uranium or thorium from the rock then I’m breaking the law and I can get in trouble. And then we have the guy in Australia…the guy who was OK in his collection of the elements until he got to plutonium. In the US, one is allowed to own very small amounts of many radionuclides; up to a point radionuclides are exempt from regulation – for Cs-137 the exemption limit is 10 µCi, which is why it’s OK for me to have a 1 µCi check source on one of my instruments. But I’m not allowed to have 11 µCi of Cs-137 unless I have a license and if I’m caught with 11 of those sources then I can be fined. The thing is, in the US there’s no exemption limit for plutonium, so anyone who owns any amount of plutonium needs to have a radioactive materials license.
The reason given in the Australian press was “non-proliferation” – because some plutonium isotopes are fissile, it might be used as fuel for a nuclear weapon. Because of this, the man, who is said to have purchased it from an American online science shop, was arrested, lost his job, and faces up to 10 years in prison.
The thing is, not all plutonium is fissile, and even the isotope that is fissile requires several kilograms before we have to start worrying that it’s going to trigger a nuclear explosion. While I don’t know exactly how much plutonium was in the source the guy in Australia bought, it was likely on the order of micrograms – he’d have needed millions of these sources to become a threat. Of course, plutonium is also toxic – but so’s lead; toxicity is a good reason to control access to materials (although I can buy an awful lot of lead without even needing to show an ID), but with a few exceptions it’s not a reason to lock someone up.
In this case…I don’t know the Australian laws and I’m not sure about the exact circumstances or charges that were brought. I can, however, understand the desire to collect – including radioactive materials (I have my own radioactive rocks and minerals and a few other odds and ends – all exempt!) – and I know that there are many cases in which the intent of the person committing a crime is as important as their actions. In this case, the intent appears to have been to complete a collection, not to make a nuclear weapon, and one can hope the judge will see things the same way.
Oh – and one final thought. The Periodic Table goes way beyond plutonium – the collector could have picked up a smoke detector for americium, but it’s hard to legally own anything beyond uranium (atomic number 92), and the Periodic Table goes all the way up to element 118, many of which have such short halflives that they’re around only fleetingly and most of which simply don’t exist outside of a laboratory in any meaningful quantities. It’s too bad that he was busted on what was likely his last purchase.