As the half lives of the unstable Yttrium isotopes are low (Y being the longest at 106 days), yttrium extracted from strontium-free moderately aged spent fuel has negligible radioactivity. However, the strong gamma emitter Y will be present as long as its parent nuclide Sr is. Should a nonradioactive sample of Yttrium be desired, care must be taken to remove all traces of strontium and sufficient time to let the short lived Y-90 (64 hours half life) decay must be allowed before the product can be used.