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I have been following the latest reports on the water leaking at Fukushima and the discussions on the same topic here and I have a question that I don't seem to be able to find the answer to.

By most (all ?) accounts, the water in the storage tanks is rich in Sr, which is a beta emitter and has an affinity for the bones. Particularly bad seems to be Sr-90, with some people thinking that it's a more serious problem that even the Cs-137 in the water. The problem that I have is in trying to get a biological half life of Sr-90, which I think is a more meaningful number than the decay half-life. I have seen studies quoting 14 days, 600 days, 6500 days and even 50 years for its biological half life. How can there be such spread and uncertainty? Does anyone here have any words of wisdom to offer?

If we are talking about Sr-90 in the bones (where it will eventually end up), then the "biological" half-life is ~ 50 yrs and the "effective" half life (which is more meanigful) is ~ 18 years. Neither of them is particularly short.

Have you seen any numbers as to the content of Sr-90 in the water in those Fukushima tanks? If so, could you share them here?

OscarG, it took me a while, but I got some of those numbers for you, as published by TEPCO. Take a look here (attached). They don't have specific Sr90 numbers (they say under analysis), but they have the total beta, of which I think Sr90 is the major contributor. Actually the concentrations are going up.