Brian H wrote: No, they’re quite specific about a small amount of nickel being converted to copper. One claim is that running continuously for 6 mo. converts over 50% of the sample.

if there’s *any* copper produced whatsoever, then it would be altogether too surprising if there weren’t also quite a lot of radioactive Ni-59 produced; (half-life 101 ky), formed by the reaction
Ni-58 + p -> Cu-59 -> Ni-59 + e+.

A test for Ni-59 that would seem to be conclusive.