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Thursday, June 20, 2013

Fukushima's Groundwater Is Contaminated

At different levels than earlier reported.

It sounds somewhat scary, but it's important to understand what the regulatory levels are based on.



They are based on drinking a certain amount of water per day, all year (a total of 7.3E5 ml in the U.S. regulations).  There is a low annual dose limit for the general public (100 mrem/year in the U.S.).

So having Sr-90 at 30 times the limit isn't terrible unless that's your only source of water for a very long time.  But even then, it's not horrific, since we're talking about (30 x 100 mrem/yr = 3 rem/yr).  Radiation workers are allowed 5 rem/yr.  If you solely drank it for 20 years (and ignoring radioactive decay), you'd have 60 rem.  That would increase the average person's cancer risk by about 6%.

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