A recent InFORM analysis of Buesseler’s data concluded that concentrations of cesium-137 have increased considerably in the central northeast Pacific, although they still are at levels that pose no concern.
“It appears that the plume has spread throughout this vast area from Alaska to California,” the scientists wrote.
They estimated that the plume is moving toward the coast at roughly twice the speed of a garden snail. Radiation levels have not yet peaked.
“As the contamination plume progresses towards our coast we expect levels closer to shore to increase over the coming year,” Cullen said.
Even that peak won’t be a health concern, Buesseler said. But the models will help scientists model ocean currents in the future.
That could prove important if there is another disaster or accident at the Fukushima plant, which houses more than a thousand huge steel tanks of contaminated water and where hundreds of tons of molten fuel remain inside the reactors.
In a worst-case scenario, the fuel would melt through steel-reinforced concrete containment vessels into the ground, uncontrollably spreading radiation into the surrounding soil and groundwater and eventually into the sea.
“That’s the type of thing where people are still concerned, as am I, about what could happen,” Buesseler said.
Scientists now know it would take four to five years for any further contamination from the plant to reach the West Coast.