Yes, some radioactive bits are leaking into the ocean.
To put it in perspective, the amount of radiative material that's getting out is LESS than you'd find being emitted from the chiminies of a 1000MW coal burning power plant.
Burning coal puts radioactive shit into our atmosphere to the tune of _at least_ six chernobyl-class meltdowns _EACH YEAR_. Yet this is happily ignored by the antinuke protesters because it's inconvenient to acknowledge it.
And yet, that's _nothing_ compared to the amount of radioactive crap carried around in the lungs of each and every smoker on the planet. Shall we treat smokers as toxic radiological waste?
Yes, you can (just) detect radioactive products in the water from Fukushima on the US western Seaboard. In general it's a change from 8 radioactive particles per 10 cubic metres of water to 9 radioactive particles per cubic metres of water. Go and compare them with the levels detectable after the Bikini Atoll tests, or for more recent examples, the 1970s atmospheric tests at Mureroa Atoll. (Hint, they're significantly less and people weren't overly worried about those)
It's about relative risk. Radiation exposure doesn't result in three-eyed fish or cancers. That's chemical toxins - like coal slurry ponds (responsible for the _2_ largest environmental disasters in the USA since 2001). Radiation usually kills cells, and the effects of exposure are either you die if you get a massive dose, or you don't die.
Even the extremely radioactive lungs of a smoker don't cause them to develop cancers. The culprit for that seems to be when the polonium in those lungs breaks down to berylium (which is _extremely_ carginogenic and not at all radioactive)
Radioactives can be detected from a distance and dealt with. Chemical toxins are quiet and things like arsenic are a gift that just keeps on giving. (Depleted Uranium is classified as a radiological hazard. The actual poisoning path is as a toxic heavy metal in the same family as lead. If exposed to weapons-grade plutonium you'll probably die of chemical poisoning long before the radioactivity has any chance to affect you.)
We fear radiation accidents in the same way we fear aircraft crashes despite being hundreds of times more likely to be killed driving to the airport. It's not a rational thing and it pays no attention to hard statistics.
But that irrational fear of the unlikely death frequently causes us to be killed by the more mundane, common hazards - people deciding to drive long distances instead of flying being a classicexample.
1500 people died of stress-related causes in the Fukushima evacuations. The only injuries due to radiation were a couple of minor burns on the ankles of a half dozen staff working in the reactor buildings - and they healed within days.