3 ms·

I don't believe him. 1kg of uranium spread into 10x ingots, suspended in a pool of heavy water ... I don't think this is sufficient to actually maintain critic

I don't believe him. 1kg of uranium spread into 10x ingots, suspended in a pool of heavy water ... I don't think this is sufficient to actually maintain criticality, even if he had a startup neutron source. There isn't nearly enough mass. A commonly cited figure for a CANDU reactor is ~8 kg, in a well-designed geometry, with a properly designed reflector in addition to the moderator. He used metallic uranium instead of uranium oxide. Therefore, I don't think he had a sufficient neutron source to get the chain reaction started. For example, modern power reactors rely on (alpha + oxygen -> neon + neutron) reaction, with the alpha decay of the fuel as the alpha source. "Should the reactor run away" Water-moderated reactors have a negative temperature coefficient of reactivity. So if he actually achieved criticality and generated enough power to produce heat, the reactor would be self-regulating.

madaxe_again 11y ago
Ditto - there's quite a bit here that suggests it's a fabrication, as had someone done this they'd want to talk about the gritty technical challenges they overcame, not gloss over them. That said, if you want to play nuclear physicist, there are plenty of fun home projects. Farnsworth fusors can be built cheaply by a dedicated amateur, and you can build your own particle accelerator (cyclotron or synchrotron, take your pick) if the fancy takes you. Easier yet is making a cloud or bubble chamber, and you can use all sorts as a particle source.
vmorgulis 11y ago
Me too. Looks like a 4chan story.
gh02t 11y ago
> even if he had a startup neutron source In the words of my [nuclear engineering] professor: "criticality is a property of the system and is independent of any external source." 1kg of uranium isn't enough to form a critical mass, period. Nothing else really matters and adding a source doesn't change that. It's possible this person built something that experienced induced fissions, but a self-sustaining chain reaction (i.e., a reactor) is not.

madaxe_again 11y ago

Ditto - there's quite a bit here that suggests it's a fabrication, as had someone done this they'd want to talk about the gritty technical challenges they overcame, not gloss over them. That said, if you want to play nuclear physicist, there are plenty of fun home projects. Farnsworth fusors can be built cheaply by a dedicated amateur, and you can build your own particle accelerator (cyclotron or synchrotron, take your pick) if the fancy takes you. Easier yet is making a cloud or bubble chamber, and you can use all sorts as a particle source.

vmorgulis 11y ago

Me too. Looks like a 4chan story.

gh02t 11y ago

> even if he had a startup neutron source In the words of my [nuclear engineering] professor: "criticality is a property of the system and is independent of any external source." 1kg of uranium isn't enough to form a critical mass, period. Nothing else really matters and adding a source doesn't change that. It's possible this person built something that experienced induced fissions, but a self-sustaining chain reaction (i.e., a reactor) is not.