Michael Palmer, in his book Hiroshima revisited, doesn't go as far as to rule out “nukes” entirely, but damage assessment, medical evidence, witness reports and measurements show that no such thing as claimed by the US and Japanese governments happened in Hiroshima and Nagasaki. Instead, there were other ingredients to the atrocities, like the usual napalm, so-called “pumpkin bombs” (the iconic Nagasaki model), flash bombs and coloured smoke (“special effects”), and mustard gas (to generate “radiation sickness”), which is a gel that can linger on and emit poison for weeks (depending on the weather).
Napalm and mustard gas are 100 % consistent with the medical record, which the author is professionally qualified to assess, citing academic literature (which is scarse in case of napalm, probably on account of its heavy use by the US against East Asian peoples in the “defense of democracy”).
The damage pattern is extensive rather than intensive (that is the military expert assessment), just as seen in other napalmed cities in Japan. Miraculous survivors at the alleged “ground zero” (no such thing can really be derived from the damage pattern) preclude any generation of heat drastically higher than what is attainable by conventional means (“victims were vaporized”). So do slender objects like antennas and trees (which blossomed again next spring, then interpreted as a “miracle”). The few stone buildings there were can be seen standing out among the remains of flimsy huts that were blown and burnt.
And of course there was no disruption in settlement, the cities were built up and inhabited again.
« simulations on what happens with your aging asrenal » — Swarms of red herrings to keep the myth alive. Surely other uses of supercomputers are conceivable, even for non-disclosed purposes.
Strangely, while the non-existence of such weapons is undoubtedly good news, there are many “nuke fanboys” (no girls, though – this is a male thing) who will get upset and even angry at this, as if the “atomic bomb” were some kind of god to venerate, when it really only is lies and propaganda that we've been fed when we were kids.
To be clear, this is not to dispute nuclear energy, just the claim that it may be used to obtain explosions, and even extraordinary ones.