Video of a LEGO automobile


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“Not on earth”

Best answer he could give. I am so fucking envious of his probable future. I hope he gets it.

Eh. I would be more impressed if it burned gasoline.

Actually, I want the nuclear model. Does LEGO make a functional reactor yet? Can I get it in yellowcake yellow?

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FTW!!! (Also, I was in this queue before you. :stuck_out_tongue: )

Not so far, I am afraid. But I for one wouldn’t mind hafnium-free-zirconium clad uranium dioxide lego bricks. And beryllium ones. And cadmium ones for the rods. And purified graphite for the moderator, maybe also zirconium-clad for structural reasons of the snap-in components… I think it’d be generally doable.

The material engineering of atomic piles is fascinating.

You’d have to go for black, as yellowcake is only a precursor for the uranium dioxide fuel. (But we could go hardcode and go with metallic uranium…)

A potential problem with the bricks would be their swelling. Some of the fission products are gaseous, and neutron damage swells quite many alloys, graphite, and I think the uranium dioxide itself too. So the bricks design would need to take this into account to still hold together after burning some MWh/kg…


What about depleted uranium? If it’s safe enough for Iraqi kids, surely it’s safe enough for American kids?

You can get some from; but they don’t ship it off the US, which annoys me, and I don’t have friends in any of the hot zones to get me a sample of a spent kinetic penetrator ordinance. :frowning:

But DU won’t be of much help for a conventional reactor. Natural-composition one is difficult enough to get working, you need heavy water or annoyingly pure graphite. Maybe if you built also a LEGO spallation neutron source, it could run as a subcritical reactor on fast neutrons, albeit the lack of cross section at those energies is even more annoying. Enriched one would be the best but then you have yet more annoying bureaucrats who want it all for themselves, and LEGO ultracentrifuges would need certain special parts that keep being on backorder.

Doesn’t annoy me one bit, since I have no idea what it means. In my defense, I do know what “albeit” means.

Essentially it is a “virtual size” of the nucleus for the neutron of a given energy. The spacing of the nuclei is given by the lattice constant of the material, the “size” is the cross section. Add the neutron flux per area, and you get a probability that a neutron will smash into the nucleus (and react there, or at least bounce off and usually leave some of its energy behind as a heat) instead of just merrily zipping along, ignoring the nucleus altogether.

the name of the unit, “barn”, originated (if I remember well enough) from when the Manhattan Project scientists calculated the cross section of Xe-135, an especially annoying neutron poison in reactor engineering (see xenon poisoning (in English literature) or iodine pit (in Russian) for how it makes reactors misbehave), and one said that it is big as a barn. The naming stuck since (and Xe-135 has 2 million barns for capture of a thermal neutron). (Edit: it was about the uranium nucleus. The xenon-135 appeared as a problem a bit later.)


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