>Does anyone know what the physical form Sr-90 RTGs would be in?
At least in some cases, strontium titanate pellets were used.
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Yes -- I checked that just two days ago in a couple of books I have, which include chapters on RTGs.
Apparently the strontium titanate is the preferred form because of its heat resistance -- m.p. around 1,900 C, if I remember the figure correctly.
What I wasn't able to find out however, is any information on shielding requirements/practice to protect against those Bremsstrahlung x-rays.... anyone ?
Jaro