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Why can't the water being stored at Fukushima be reused for cooling?
https://www.reddit.com/r/askscience/comments/9myx4q/why_cant_the_water_being_stored_at_fukushima_be/
A
You don't need a centrifuge for most liquid radioactive waste. Most radioactive water can be cleaned chemically with ion exchange, reverse osmosis, and other processes.
I think the greater concern is that there is so much water (thousands of metric tonnes, where an operating plant needs about 500 to 1000 metric tonnes), and the water has transuranics (radioactive elements from the actinides like uranium, plutonium, and others). Ideally, those contaminants wouldn't be in the coolant for plants.
Tritium has to be tracked and isn't easily separated, but in the end it has a 12 year half life and will decay in three hundred years. Heavy water (deuterium) is not an issue.
E: Tritium half life is 12 years, corrected 30
B
One of the biggest issues in treating the liquid is that it is mixed contamination in seawater.
Seawater, due to its high sodium and chloride content makes it very difficult to use the standard methods of treatment, ion exchange resin beds.
Basically, the dissociated components of the salt in the water bind to all the resin sites instead of the isotopes that you want to remove.