20% Enrichment Sufficient to Make Nuclear Bomb

[image error]

Gordon Edwards

There is a lot of confusion about uranium enrichment in Iran.

In natural uranium, only 7 atoms out of 1000 are chain-reacting uranium-235. The other 993 atoms are, for the most part, uranium-238 atoms – not a chain-recating material. 

Uranium enrichment refers to any technology that increases the percentage of the chain-reacting U-235 beyond the 0.7% level (i.e.natural uranium). But there is a good deal of misinformation and/or misunderstanding about enriched uranium in the media recently.

 (1) Nuclear Explosions

It is often reported that 90% uranium enrichment is “needed” to have a nuclear weapon. This is not true. The Hiroshima bombs had only 80% enrichment. Iran has a good deal of 60% enriched uranium, and you can make a bomb from 60% enriched uranium — it would be bulkier than a bomb with 90% enrichment and therefore harder to deliver, but not so very much harder. 

Also, the mechanism needed for making a uranium bomb is very much easier than what is needed for a plutonium bomb. It can be done with a lot less effort and taking very little time. It’s called a “gun-type” atomic bomb rather than an “implosion-type” atomic bomb. 

The gun-type bomb just fires one chunk of uranium into another chunk (the target) so that the two chunks add up to more than a “critical mass”.  It is so simple it cannot possibly fail – as a result they never had to test this type of bomb before using it. They dropped it on the city of Hiroshima with no testing. There is a need for a precision timed “neutron source” but that is very old technology that has been well known for ages.

The implosion-type bomb is much more sophisticated, requiring a perfectly spherical shaped mass of plutonium metal surrounded by concentric plastic explosives to drive the sphere inward toward the centre – an “ implosion”.  That is so tricky it’s pretty well got to be tested before using. The USA tested it at Alamogordo before dropping it on the city of Nagasaki.

Nuclear non-proliferation authorities maintain that a powerful nuclear explosive device (gun-type) could be made with any uranium enriched to 20% or more. Such an explosive device would not have to be delivered by rocket or aeroplane, but could be delivered in the hull of a ship, or in a truck, or even in the trunk of a car, and detonated by remote control.

Independent experts now say the same is true of most HALEU (high-assay low-enriched uranium) enriched to more than 12% U-235. Although this reality is not officially acknowledged by regulators, it means that the fuel for some of the “fast” or “advanced” SMNRs being proposed — like the ARC [NB] or eVinci [Sask] or Natrium [Wyoming] reactors — is already weapons usable material, even though it is below the 20% enrichment level.

[…]

Via https://www.ccnr.org/Uranium_&_Plutonium_2022.pdf