Nazi Germany had no hope of making an atomic bomb, uranium cubes reveal
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Nazi Germany had no hope of making an atomic bomb, uranium cubes reveal
Unofficial Hacker News client; not affiliated with Y Combinator.
WalterBright · · focus · HN ↗
colechristensen · · focus · HN ↗
>It was abandoned after the surrender.
Japan is strongly believed to be on the order of months away from assembling a nuclear weapon, and not just one, they have the materials for many. For them it is not geopolitically useful to actually finish a weapon, but they are more than capable.
WalterBright · · focus · HN ↗
philipkglass · · focus · HN ↗
<a href="https://www.aec.go.jp/bunya/04/plutonium/20260805_e.pdf" rel="nofollow">https://www.aec.go.jp/bunya/04/plutonium/20260805_e.pdf
As of the end of 2025, the total amount of Japan’s separated plutonium managed both within and outside Japan was approximately 44.4 tons, of which approximately 9.9 tons were held domestically and approximately 34.5 tons were held abroad.
Despite the nomenclature, weapons grade plutonium is not necessary to make nuclear weapons. Reactor grade plutonium has more problems with predetonation ("fizzle") and decay heat management, but both obstacles can be bypassed by design changes. In particular, "boosting" with a mixture of deuterium and tritium overcomes predetonation problems and can ensure repeatable high yields even with plutonium containing a high fraction of Pu-240.
<a href="https://en.wikipedia.org/wiki/Boosted_fission_weapon#Gas_boosting" rel="nofollow">https://en.wikipedia.org/wiki/Boosted_fission_weapon#Gas_boo...
The fusion reaction rate typically becomes significant at 20 to 30 megakelvins. This temperature is reached at very low efficiencies, when less than 1% of the fissile material has fissioned (corresponding to a yield in the range of hundreds of tons of TNT). Since implosion weapons can be designed that will achieve yields in this range even if neutrons are present at the moment of criticality, fusion boosting allows the manufacture of efficient weapons that are immune to predetonation. Elimination of this hazard is a very important advantage in using boosting.
This design hardens weapons against neutrons from nuclear interceptors and against neutrons generated within the core itself, e.g. spontaneous fission from "dirty" reactor plutonium.
Gas boosted bombs are more mechanically complex than the bombs of the 1940s, but the US started building them in the 1950s. Japan could easily manage the complexity today. Japan has also operated its Tritium Process Laboratory since the late 1980s, with capacity to handle 16 grams of tritium at a time. That's not much, but an individual boosted warhead may need only 3 grams of tritium.