In this week's Chemical and Engineering News, this really interesting article by Craig Bettenhausen on 3He:
The industrial gas giant Air Liquide has signed a long-term agreement to purchase helium-3 (3He) from a Canadian nuclear power firm. The arrangement creates the first significant private supply of the ultra-rare gas, a light isotope of helium used in deep cryogenics, nuclear science, and quantum computing.
Air Liquide will take 3He that Laurentis Energy Partners extracts from a nuclear power byproduct, further purify it, and package it for sale. Jennifer Chapin, director of projects at Laurents, says the initial output will be between 5,000 and 10,000 L per year. “This really does present a shift in terms of market availability,” she says.
Though the gas can be used for medical imaging and other nuclear science, Patrick Wikus, a cryogenics expert at the scientific instrument maker Bruker, expects the main application of the new supply to be in quantum computing, which requires operating temperatures near 0 K.
...Conventional liquid 4He cooling gets down to 1–4 K. To go even colder, scientists mix super-cooled 3He and 4He; the entropy gain from the mixing cools the system down even further. Called 3He-4He dilution, the process can get as low as 5 mK.
Adding 3He to a typical chiller costs $30,000 to $40,000, Wikus says, at a cost today of around $1,000 per L. At that price, recycling is a must. “When I did my PhD, I had 20 L of 3He. If I had lost those, that would have been it for my thesis,” he says.
Read more to find out how the material is extracted (from hydrogen bombs!)
It is a decay product of tritium, modern nukes need about 1g of T2 mixed with D2 to work properly (boosting triples the yield of fission primary) and it is stored separately in a little pressure bottle inside the nuke. As tritium has halflife about 10 years, it needs to be replaced after certain time, and recycled, 3He is the byproduct. But there is not enough of tritium in nukes to cover 3H demand. You can make T by irradiating Li or D in reactor, and the unique advantage of CANDU reactors for this is that they are moderated with D2O so they generate tritium naturally in the moderator, and they accumulate 3He over time
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