With the latest information posted above, which was difficult to find with google, 15 % of the mass of a nuclear warhead remains as nuclear radiation particles. If we use that new figure (15 % instead of 50 %), and we assume it has been leaking ever since the underground drainage system was destroyed during the earthquake/tsumnami, looks like 3 to 4 nukes going off every day in the sea off the coast of Fukushima for 2 1/2 years. But since some of that Fukushima Nuclear mass has been converted to heat during those 2 1/2 years, they pump water every day to dissipate that heat, we should assume conservatively the rough equivalent of 2 Ivy Kings going off the coast every day.