Well here’s a quick quote from wikipedia on nuclear transmutation.
“It transpired that, under true nuclear transmutation, it is far easier to turn gold into lead than the reverse reaction, which was the one the alchemists had ardently pursued. Nuclear experiments have successfully transmuted lead into gold, but the expense far exceeds any gain. It would be easier to convert gold into lead via neutron capture and beta decay by leaving gold in a nuclear reactor for a long period of time.
More information on gold synthesis, see Synthesis of precious metals.
197Au + n → 198Au (halflife 2.7 days) → 198Hg + n → 199Hg + n → 200Hg + n → 201Hg + n → 202Hg + n → 203Hg (halflife 47 days) → 203Tl + n → 204Tl (halflife 3.8 years) → 204Pb (halflife 1.4x1017 years)”
You would have to ask someone knowledgeable about nuclear reactors whether the conditions inside a reactor are sufficent to cause this kind of transmutation but even if it did I suspect the quantities would be microscopically small.