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What is the threat model for fuel theft? Weaponizing uranium requires enrichment well above even what maritime reactors use. Note that the difference between 90

What is the threat model for fuel theft? Weaponizing uranium requires enrichment well above even what maritime reactors use. Note that the difference between 90% enrichment and 99.9% enrichment isn't a factor of 1.1 difference, it's a two-order of magnitude difference - the remaining impurities need to be reduced by a factor of 100, each of those extra nines is another order of magnitude. And even if fuel does get enriched, it requires extensive nuclear physics research and engineering effort to produce a fission device. The only groups proven to be capable of this are state actors, which can set up their own enrichment facilities and have no real reason to steal uranium. An alternative threat model is not producing a bomb, but dumping radioactive waste in a populated area. While damaging, radiation is a relatively slow killer save for the most intense doses. The amount of damage that it would be able to inflict is minimal relative to the amount of effort requires to break into a nuclear facility and exfiltrate fuel. The question that should be asked is, does this present a larger potential for harm as compared to the same amount of effort put into conventional means of destruction (bombing buildings, shooting up crowded areas)?

cryptonector 6y ago
Enriching HEU to weapons grade is trivial by comparison to enriching natural uranium to even just 20%. Really, the difference in effort needed is enormous. Yeah, you still need centrifuges, but you need many fewer centrifuges and many fewer passes. Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to weapons grade uranium.
- Manuel_D 6y ago
  > Enriching 90% uranium to weapons grade is trivial by comparison to enriching natural uranium to even just 20% Naturally occurring uranium is 99% U238, and 1% U235 (and some U234, but that's a trivial amount). 20% enrichment means that 80% of the fuel is U238. You only need to take out 1/5th of the U238. In order to weaponize uranium, U238 concentration needs to be reduced to 10% or below. You need to take out about 90% of the U238. Sure, if you're staring with 20% enriched uranium you'll need a factor of 20 less input material. But that's not very significant, uranium isn't particularly expensive. The factor that's limited by centrifuge capability is the final enrichment purity. That's why one of the main things nuclear weapons inspectors look at are centrifuges. > Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to 99% enriched uranium. No, you can't. The presence of too much U238 prohibits a runaway nuclear reaction regardless of the amount of uranium. You can get fission from lower enrichment, but not runaway fission. It's like flare versus a firecracker. And that's a desirable trait in electric power generation. The main principle of weapons inspection is to ensure that a country's enrichment facilities can only enrich uranium to a purity sufficient for power generation, but below weapons applications. The height and diameter of the centrifuges are the main factors here.

cryptonector 6y ago

Enriching HEU to weapons grade is trivial by comparison to enriching natural uranium to even just 20%. Really, the difference in effort needed is enormous. Yeah, you still need centrifuges, but you need many fewer centrifuges and many fewer passes. Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to weapons grade uranium.

Manuel_D 6y ago
> Enriching 90% uranium to weapons grade is trivial by comparison to enriching natural uranium to even just 20% Naturally occurring uranium is 99% U238, and 1% U235 (and some U234, but that's a trivial amount). 20% enrichment means that 80% of the fuel is U238. You only need to take out 1/5th of the U238. In order to weaponize uranium, U238 concentration needs to be reduced to 10% or below. You need to take out about 90% of the U238. Sure, if you're staring with 20% enriched uranium you'll need a factor of 20 less input material. But that's not very significant, uranium isn't particularly expensive. The factor that's limited by centrifuge capability is the final enrichment purity. That's why one of the main things nuclear weapons inspectors look at are centrifuges. > Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to 99% enriched uranium. No, you can't. The presence of too much U238 prohibits a runaway nuclear reaction regardless of the amount of uranium. You can get fission from lower enrichment, but not runaway fission. It's like flare versus a firecracker. And that's a desirable trait in electric power generation. The main principle of weapons inspection is to ensure that a country's enrichment facilities can only enrich uranium to a purity sufficient for power generation, but below weapons applications. The height and diameter of the centrifuges are the main factors here.