Our friend Maris sent me a pm and I find it I must put it here.

The radioactive Strontium 90 did not exist freely on earth before the atomic and thermonuclear atmospheric bomb tests in the 1950s and 1960s. It cannot be used in the making of glass because it undergoes beta decay into Yttrium 90 and this spontaneous conversion has a half life of only 28.8 years. The Yttrium 90 changes to Zirconium 90 and this reaction has a half life of only 64 hours. Any glass made of radioactive Strontium would crumble into Zirconium sand in only a few decades.