True facts about Ocean Radiation and the Fukushima Disaster

This piece, on deepseanews.com, was written by an Oceanographer, and is a debunking of fears around the radiation risks.  The bottom line is - Dilution means that by the time radioactive seawater makes it to the US West Coast, it'll be so far diluted to be barely an effect.

It claims 538,100 terabecquerels (TBq) have been emitted from Fukushima, making it worse than Three-Mile-Island, and less than Chernobyl.

The writer goes over several Maps of Doom that have been bandied around on various blog posts, two of which are completely useless.  This one was described as being a Map of Terror, but at least it shows what the colors mean:

The red shows areas where the radiation concentration is 10,000 times less than the concentration near Fukushima, and the band further out near the US West Coast is 1 million times less concentrated.

The prediction from models are that the Hawaiian Islands will see concentrations of 30 Bq / Cubic-Meter of seawater, and on the US West Coast the concentration will be 20 Bq or less.  (Bq == Becquerels)

I could write a small novel explaining why the numbers differ between the models. For those that love the details, here’s a laundry list of those differences: the amount of radiation initially injected into the ocean, the length of time it took to inject the radiation (slowly seeping or one big dump), the physics embedded in the model, the background ocean state, the number of 20-count shrimp per square mile (Just kidding!), atmospheric forcing, inter-annual and multi-decadal variability and even whether atmospheric deposition was incorporated into the model.

To put the numbers into context they provide this map, coming from the Woods Hole Oceonographic Institute (http://www.whoi.edu/page.do?pid=83397&tid=3622&cid=94989):

It shows the Pacific Ocean concentration of Cs 137 in 1990 was 4 Bq / cubic meter.  That makes the new concentration, thanks to Fukushima, about 10x the 1990 concentration.  The amount measured in 1990 would have been leftover from the Atomic Bomb testing in the Pacific occurring during the 1950's.

The writer of the piece concludes that it'll be safe to eat the fish and to swim in the ocean.

As for leaking groundwater - 300 tonnes per day leaking into the ocean - is that a concern?  It means the radiation won't be a one-time release, but is being released over time.  However the bulk of the release occurred early on.  

Most of what's being released now is Tritium and Strontium.  Strontium is a concern because it collects in bones, hence the risk is from eating fish that have bones in them.  However, the Strontium risk is only for such fish caught near the Japanese coast.

Source: http://deepseanews.com/2013/11/true-facts-about-ocean-radiation-and-the-fukushima-disaster/