system
Given the following post, respond as if you're commenting on Reddit:
human
Why is Tritium so ridiculously expensive?

I am a huge fan of self-powered radioluminescent light sources powered by tritium like keychains. For a long time I have been wondering why  isn't there anything more powerful (like a flashlight) since such keychains output is something like couple hundred microlumens. After a quick web search I found out that tritium price is in the range of 30.000 USD per gram making it one of the most expensive substances on Earth.  


I would like to learn why is that so. From what I understand tritium is produced as a waste product in heavy water moderated reactors in quantities exceeding commercial demand and that it can also be made from lithium (which is a common and cheap metal) by neutron capture. Is it so difficult and expensive to separate tritium from deuterium in reactors moderator? Is it so difficult to insert a lithium rod into an ordinary nuclear reactor in order to irradiate it with neutrons and then extract resulting tritium?  


I wish to understand difficulties behind tritium production and where does the high cost come from.
gpt
a.) It's got an expiration date. You've got a half-life of about 12 years, which means that you constantly need a new supply of it, and that any light is going to die, and any manufacturer is going to need to anticipate a continuing production line, not just buy up a lot at once.

b.) It's not naturally occurring - all tritium comes from nuclear reactions, so there's no source of it out there to be cheaply exploited, you need to contract with a nuclear plant.

c.) It's radioactive - on its own, it's not especially dangerous, but if it's inhaled or consumed, it can hurt people, which means that the costs of storing it, shipping it, and working with it are much higher.

d.) No economies of scale - since the entire marketplace of tritium is pretty small, and the process to create it is pretty specialized, you don't get to spread the fixed costs over a lot of products.  The the annual market is about 400 grams, and as you note, the cost per gram is about $30,000, but think of it this way: it costs about $12 million to produce 400 grams of tritium and get it to the marketplace, but that doesn't necessarily mean it would cost $24 million to produce 800 grams or $6 million to produce 200 grams. It might cost $11 million just to get *any* tritium out there, and after it's set up, then maybe each additional gram is fairly cheap. But you gotta start somewhere. 

So it might be that all the tasks involved are scalable, and tritium could get much cheaper if there was demand. But getting started is so expensive, and demand is pretty small, so it's a niche product.