It's a single isotope, nickel-63, which decays into regular copper-63. The amount of nickel halves every 96 years.
If you throw it in a fire, you'll disperse nickel-63 into the environment, which isn't good, but the decay process is unaffected.
If you throw it in a fire, you'll disperse nickel-63 into the environment, which isn't good, but the decay process is unaffected.
So like 1000 years for this to flush itself.
You can estimate it yourself:
0.5 ^ 10 = 0.0009765625 (~0.1%)
https://en.wikipedia.org/wiki/Half-life#Probabilistic_nature
> When there are many identical atoms decaying, the law of large numbers suggests that it is a very good approximation to say that half of the atoms remain after one half-life