Wednesday, May 14, 2014
Radioactive material certainly did reach the ocean from the Fukushima meltdown. As I understand it, the amount of contaminated water from the reactor that reached the ocean would fill a large swimming pool or two.
In the vastness of the Pacific Ocean, that doesn't amount to much. Given some time to disperse (like a couple of years), the radioactivity of ocean water contaminated with water from Fukushima is indistinguishable from normal background radiation. Furthermore, the "hottest" radioactive isotopes decay pretty quickly. Iodine-131, for example, has a half-life of eight days; there isn't even a word for the tininess of the fraction of iodine-131 remaining from that incident. It's effectively gone.
There are more persistent isotopes, of course. There are cesium isotopes from the meltdown with half-lives of years, but the danger is still negligible. Information I'm seeing tells me that you would have to eat twenty tuna steaks to take in the amount of radiation you would get from one typical banana.
This is paranoia based on lack of understanding. Don't worry about radioactive tuna.