...of anyone now living.
This said, 14 MeV neutrons from fission, via the 198Hg[n,2n]197Hg -> 197Au reaction would be far more efficient at this transformation, than fission gamma rays.
The note in the reddit site you linked states the gold would be radioactive. This is true, but the cooling times would be very short. Gold has no neutron rich radioisotopes that are very long lived. Gold recovered from the evaporation of residual mercury would be usable within months, not years.
There are a lot of fusion start ups these days, and surprisingly they're generating investor interest. I believe almost all of them, if not everyone of them, will fail. One of the fun things about them is that it would seem none of them have come close to figuring out how to recovery exergy from the plasma. This renders the fusion heat nearly worthless, particularly because the device needs some heat shielding to survive. If however, the neutrons pass through the walls, into mercury, to recover exergy, then maybe that would work.
Most of the wall designs I've seen for fusion reactors are based on tungsten. Under these conditions, assuming a fusion reactor could operate continuously - which is not clear to me - tungsten would be transmuted into the extremely valuable elements rhenium, osmium, iridium, and ultimately platinum were it to operate for decades. It wouldn't be all that impressive. The neutron flux of a fusion reactor is very low compared to that of a fission reactor, which is many orders of magnitude higher.
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