|
|
|
|
|
|
by philipkglass
804 days ago
|
|
|
Yet, from the same book I learned that during the Manhattan project 20000 explosions were used to understand and fine-tune the implosion design, and for each explosion that happened at least 20 were analyzed on paper before. More than 1000 scientists and engineers worked on nailing that design, and it was by far the most expensive part of the entire Manhattan project. The lion's share of the project spending was for uranium enrichment at Oak Ridge. The Los Alamos experiments and all R&D together accounted for only 8% of the Manhattan Project cost: https://blog.nuclearsecrecy.com/2013/05/17/the-price-of-the-... The gun-type Little Boy bomb had a yield of 12-15 kilotons from 63 kilograms of highly enriched uranium: https://en.wikipedia.org/wiki/Little_Boy The Ivy King uranium implosion bomb had a yield of 500 kilotons from 60 kg of HEU: https://en.wikipedia.org/wiki/Ivy_King That's about 35 times more efficient without even having to manufacture tritium for boosting (and tritium is, gram for gram, by far the most expensive material in the nuclear weapons complex.) I think that implosive fission bombs would soon have been developed after the war even if they hadn't been part of the original Manhattan Project effort. I do think that with a less intense USA-USSR rivalry after the war it's plausible that thermonuclear weapons based on radiation implosion would not have been developed, or developed much later. |
|
|
Regarding the expensive part. The actual word in the book ([1], p 174) was "difficult", not expensive, I misremembered.
I am not disputing that implosion is much more efficient than the gun type. Even the Nagasaki bomb had a much higher efficiency than the Hiroshima bomb. In the Hiroshima bomb only 1.4% of the uranium underwent fission. In the Nagasaki bomb, 17% of the plutonium did that, plus an astounding 4% of the unenriched uranium temper.However, imagine von Neumann did not get involved in the project. There's a good chance it would have taken the team a few more months to solve the implosion puzzle. If such had been the case, Groves and Oppenheimer would have pulled the plug, and focused fully on the uranium design.
Now, fast forward a few more months until the end of WW2, when Oppenheimer and the vast majority of the scientists and engineers at Los Alamos had gone home. Norris Bradburry is the new boss. The US Navy comes and tells him they want to set up Operation Crossroads in the Pacific, in mid 1946, and he needs to provide 3 atomic bombs for that, and maybe a spare or two. What would he do? Tell them that he needs some extra time to work on some potential great alternative design, or reply "Yes, Sir" and go ahead and make, with whatever handful of scientists and engineers he had left, a few replicas of the Little Boy? My guess is that he would have chosen the second option.
In such a scenario, when the Soviets build their own atomic bomb, it is also a gun-type, because that's the working design they steal.
It is perfectly reasonable that the US sees implosion as a game changer (as it was) and perfect the design after the war, but the urgency is down by a factor of 10, as is the scientific manpower. A large number of scientists refused to work on atomic weapons after the end of WW2, now aware of their monstrous effects.
And here we both agree that it's quite plausible that the arms race would between the US and the Soviet Union would have been less intense. It would have taken a few extra years to get to the Ivy King level of technology, and by that point the ICBM precision would have been high enough that radiation implosion thermonuclear weapons would not have been really needed.
[1] https://www.google.com/books/edition/Atomic_Adventures/wxokD...