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Part of the answer is that atmospheric explosions generate a lot less fallout precisely because they move less dirt: that first link states that a 30m high towe

Part of the answer is that atmospheric explosions generate a lot less fallout precisely because they move less dirt: that first link states that a 30m high tower was used in large part to minimise fallout and left a crater with maximum depth of 140cm. So "Trinity" 75 years later isn't a very good indicator of how atomic civil engineering on a short timescale will fare. It's interesting and perhaps a little reassuring that the 2009 review of natural background exposure didn't find conclusive effects other than for radon, but the enthusiasm in the US for peaceful nuclear explosions had already ebbed more than 40 years earlier after some quite cavalier experiments, so it's not so much "why is it unpopular?" as "why couldn't the topic be reconsidered in the light of newer research and less as a cheerleading exercise for nuclear weapons development?". Probably it's hard to judge the economics of PNEs Vs conventional civil engineering since the nuclear industry is quite coupled to the military.

throwaway4aday 4y ago
Were they proposing surface detonations to dig the channels? From my limited knowledge of blasting, the conventional explosives are placed in holes drilled into the rock in order to fracture it so it can be easily removed. Would you not do the same with nuclear explosives but just on a larger scale?
- thombat 4y ago
  That's exactly what you do, but that means some finely pulverised irradiated material probably gets ejected. The notorious example of this was the Sedan nuclear excavation test [1] which created a usefully big hole (100m deep, 390m diameter) by removing some 11 million tons of soil, but "the radioactive fallout from the test contaminated more US residents than any other nuclear test." Much of the fallout was due to the fraction of the yield that was from fission, and WP notes that "had this test been conducted after 1965 when improvements in device design were realized, achieving a 100-fold reduction in radiation release is considered feasible". But the public enthusiasm for the program was naturally impaired. [1] https://en.wikipedia.org/wiki/Sedan_(nuclear_test) https://en.wikipedia.org/wiki/Sedan_(nuclear_test)

throwaway4aday 4y ago

Were they proposing surface detonations to dig the channels? From my limited knowledge of blasting, the conventional explosives are placed in holes drilled into the rock in order to fracture it so it can be easily removed. Would you not do the same with nuclear explosives but just on a larger scale?

thombat 4y ago
That's exactly what you do, but that means some finely pulverised irradiated material probably gets ejected. The notorious example of this was the Sedan nuclear excavation test [1] which created a usefully big hole (100m deep, 390m diameter) by removing some 11 million tons of soil, but "the radioactive fallout from the test contaminated more US residents than any other nuclear test." Much of the fallout was due to the fraction of the yield that was from fission, and WP notes that "had this test been conducted after 1965 when improvements in device design were realized, achieving a 100-fold reduction in radiation release is considered feasible". But the public enthusiasm for the program was naturally impaired. [1] https://en.wikipedia.org/wiki/Sedan_(nuclear_test) https://en.wikipedia.org/wiki/Sedan_(nuclear_test)