The Fukushima nuclear site is now overflowing with contaminated water (from cooling the remaining fuel cores to prevent further meltdown) which is being stored in huge tanks. Like they have almost 1.2 million tonnes of water from which the major radioactive contaminants have been removed (they say). And they’ve almost run out of space for more tanks.

However the stored water is still contaminated with tritium (³H), a rare radioactive isotope of hydrogen with a nucleus containing one proton and two neutrons, and a half-life of 12.32 years. Although radioactive, tritium is generally considered safe, at least externally (one common use is in luminous watches and displays).

But this presents a problem, because to even reduce the tritium level by 90% through natural decay will, I guestimate, take in the region of 40 years (something over 3 half-lives). Would that level of reduction be enough? I don’t know; I’ve not seen the data.

Extracting the tritium from the water is technically very difficult and there is no industrial-scale process available to do it.

So to solve their storage problem Tokyo Electric (Tepco) want dump the contaminated water into the Pacific Ocean. The alternative contending suggestion is to allow the water to evaporate into the atmosphere (taking the tritium with it); but this has been rejected.

Now I see the logic of dumping the water into the ocean. There is already a (low) level of tritium in seawater anyway; and most nuclear facilities use either seawater or river-water as a coolant, with the waste water flowing back into the river/ocean in real-time with low levels of contaminants (mostly tritium).

My reaction to this as a scientist is that dumping the water into the sea, over a period of years, and maybe from several sites separated by a distance, is likely the best solution; and not a solution that would, I think, worry me if it were “in my backyard”. On the other hand I do quite see, from an environmental viewpoint, why local people and nearby countries don’t like the idea.

It’s just a pity there isn’t an industrial-scale extraction process, because the tritium would be extremely valuable, even if it amounted to just a handful of grams. For one, the JET European Torus experimental nuclear fusion reactor is planning a run for late this year, and for that they need a few grams of tritium, which costs around $30,000 a gram. Surely there must be a way?