But, lets consider the alternative for a minute it would be more dangerous to have the residues idling in metal containers, that creates the risk of non controlled spills due to natural disasters, mismanagement, human error, and, of course, wear and tear.

So, we are currently in across road with two solutions. Taking into mind that tritium has a half-life of 12 years, meaning that in 12 years half of its mass would have become helium and beta radiation, the kind of radiation you can stop with a thin alluminium layer. Taking this into account, to spill or not to spill becomes a matter of "until when is safe to store the water" and "when has the tritium decomposed to acceptable levels". We must, too, bear in mind that the tritium will decompose, either on the water tanks or on the sea.

Now we are not talking about "if", but about "when".