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Alex Wellerstein

Small surface area + a solid at any reasonably ambient temperature (50ºC is hot!!) = much more survivable than a large cylinder full of gas, yes? And of course with small cylinders you could also shield the cylinders much better, very trivially — boxes within boxes and so on.

1110
Alex Wellerstein

Gosh, there is a whole rabbit hole of how UF6 is stored/transported in the USA. Unsurprisingly lots of guidelines. The big cylinders (30B) are for no more than 5% U235. The little cylinders for HEU are called 5B. This is a big issue for HALEU because HALEU is >5% but would exceed the 5B supply.

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2 прямых ответов · 11 сообщений

Dinara Ermakova

The 5B versus 30B mismatch shows how much of the HALEU supply chain is packaging and transport, not just enrichment. Qualifying new cylinders for higher assay material takes real engineering time.

Alex Wellerstein

Here are a bunch of 5B cylinders being manufactured in the USA. Apparently each can contain up to 25 kg (55 lbs) of HEU. This is roughly the number of cylinders you'd expect the Iranian HEU to be packed into, although they of course could use more if they wanted to spread it out.

Ответ для Alex Wellerstein
Alex Wellerstein

(Also, and this is really just a note for me — I have confirmed that 5Bs are authorized for up to 100% U235, 25 kg. This source is really useful...) digital.library.unt.edu/ark:/67531/m...

Ответ для Alex Wellerstein
Alex Wellerstein

And one more note: the EMPTY cylinder weighs 25 kg / 55 lb. And can be loaded with 25 kg / 55 lb of UF6. So the total weight of a full cylinder is 50 kg / 110 lbs. So each of them pretty heavy, from the perspective of individual people trying to move them around.

Ответ для Alex Wellerstein
ansonimaachi

Yeah that isn't crazy if that is all you have to carry. But does make it if you are soldier coming in the night to take a bunch of these that would seem an unmanageable amount of weight unless you are going to abandon all the equipment you came in with.

Ответ для Alex Wellerstein
Alex Wellerstein

I am amused at how similar UF6 looks to various illegal drugs when in its solid form, inside a glass vial "hey man, you got any UF6? I need a fix..."

Ответ для Alex Wellerstein
Cheryl Rofer

Alex, many thanks for this information and photos! I was looking for them a while back with no luck. I want to add two important things. 1) The volatility of UF6. 2) Overpacks. 1. Yes, UF6 is a solid at room conditions. But not like, say, table salt.

Ответ для Cheryl Rofer
Cheryl Rofer

Yes, 50 C is a hot day at the beach. But it's a low boiling point. It means that the solid has a high vapor pressure - IOW - it evaporates easily. Leave it out overnight, and, like a spill of water, it will be gone in the morning. That's why it is packed in gas cylinders.

Ответ для Cheryl Rofer
Cheryl Rofer

2. Overpacks. As you point out, even the smaller cylinders are heavy. And they will not be rolled out like that photo of a line of empties! For both protection of the cylinders and maintaining separation for criticality safety, they will be packed in larger containers - overpacks.

Ответ для Cheryl Rofer
Cheryl Rofer

I'm guessing there might be six cylinders per overpack in two groups of three, which would give a total size not far from the large UF6 cylinders. Which is why I was okay with them.