Not disagreeing on principle here, but I am not sure this is an apples to apples comparison. The Chernobyl meltdown caused the uncontrolled release of large amounts of radioactive cadmium. Fungi (unlike most plants) tend to be less discriminatory about what metals they pick up from the soil because they're capable of sequestering the harmful stuff in their cell walls. This isn't to say that bioaccumulation up the food chain doesn't also happen in the oceans (the mercury problem in fish is caused by releases from coal plants), but this is (a) much smaller, (b) treated to reduce the radioactive heavy metals, and (c) not into soil, where things have a chance to persist and accumulate.

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".

Sure, but a single particle of that drop when ingested may cause cancer (because there's no thin film of aluminium inside of your body), the entire oceanic eco-system is one extremely complex filtering system for water - and a whole bunch of people get a substantial part of their diet from the sea.

Also, from a cursory search I found this. Quote:

Accumulations of organic tritium into the mussel tissues from tritiated-phytoplankton demonstrate an environmentally relevant transfer pathway of tritium even when water-concentrations are reduced, adding weight to the assertion that organically bound tritium acts as a persistent organic pollutant. The persistence, potential for biomagnification and the increased toxicity of organic tritium increases the potential impact on the environment following a release of HTO; current legislation does not adequately take into account the nature of organic forms of tritium and therefore may be underestimating accumulation and toxic effect of tritium in the environment.

There's a bunch more in the related articles below.

One particle of radiation is very different than a bullet.