Fukushima Daiichi Nuclear Power Station - High Levels of Radioactivity in Surrounding Coastal Waters
Further concerns have been raised at the Fukushima Daiichi Nuclear Power Station as on-site monitoring revealed an extremely high radioactive level in nearby seawater (126.7 times higher than the legal concentration limit).
Seawater has been used as an emergency option to cool the reactors down. The water is then kept in the pool and eventually evaporates. Recently however, a leak in the spent fuel pool at Unit #4 was reported. Like the accident at the Hatch, Georgia nuclear plant in 1986, an unknown amount of contaminated water may have been released into the Ocean and could be responsible for the high rate of radioactivity in the surrounding coastal waters.
Because the global focus is on the radioactive cloud dispersal, no oceanic plume modelling has yet been proposed (as far as I know) to analyze the extent and impact of the radioactive seawater.
We propose a Lagrangian tracer method using hindcasted hydrodynamic data from the HYCOM/NCODA system to reproduce the radioactive plume trajectory from March 15th 2011 (day of explosion at Unit #4) to March 23rd 2011 (now). An automated modelling system has been created to follow the progression in the next few days.
Here are the results of the 8 day simulation of Lagrangian particles (model Pol3DD):
Because the volume of water being lost in the environment is still unknown, estimations of the radioactive concentration are impossible for the moment. This type of model, however, can estimate the potentially impacted area.
Estimation of the radioactive plume outreach on March 23rd 2011.
A few references from the news:
Google it; hits are coming every hour since TEPCO released their report on March 22.