Washington state engineers reflect on Fukushima nuclear disaster response
03/11/2013 3:09 PM
03/11/2013 5:44 PM
Two years ago today, Richland engineers were about to start a marathon effort to quickly design the details of a system that would keep radioactively contaminated water from flowing from damaged Fukushima reactors into the Pacific Ocean.
They not only succeeded, but the system AECOM workers in Richland designed under Kurion's direction continues to operate today to clean contaminated water at the Fukushima, Japan, Dai-ichi Nuclear Plant. It is expected to continue operating for years to come.
On March 11, 2011, a magnitude-9 earthquake was followed by a tsunami that caused a full meltdown at three reactors at the Fukushima plant. With no functioning cooling system, the Tokyo Electric Power Co. resorted to pouring millions of gallons of seawater into the reactors to cool them.
But by the middle of April, the plant's basements and buildings were filling with water contaminated from the failed fuel in the reactors. The upcoming start of the rainy season threatened to flood the plant, spilling the contaminated water out of the complex to flow into the ocean.
Kurion, an Irving, Calif., waste treatment company that has since moved its engineering and technology work to Richland, convinced the Tokyo Electric Power Co. that it was in a unique position to help. It had a proprietary chemical compound for an ion exchange system that is particularly good at stripping cesium, the main contaminant, from the water.
And unlike some other chemical compounds used in ion exchange water treatment systems, it has low sensitivity to salt water and is resistant to radiation.
But the concept needed to be turned into a system that could fit in the limited space available at the Daiichi Nuclear Plant and could start operating before huge volumes of contaminated water flooded into the ocean.
Kurion picked AECOM in Richland to execute the design under its direction.
"They almost lived in the office for almost a month," said Jim Homan, then the senior operations manager for AECOM's Nuclear Division. "To think you were going to design and build something in a month is ridiculous. But it was an emergency."
Under Kurion's direction, the team did the detailed engineering and executed the design of a system of pumps, piping, power and controls and ion exchange components, together with radiation shielding. Design changes were constant as new information became available about the damaged plant.
The equipment was organized in eight skids -- or frameworks about the size and shape of a commercial shipping container -- with six of them eventually were installed and operated at Fukushima.
They would be flown to Japan and needed to fit within the confines of the Soviet-era Antonov An-225 Mriya. It's the largest cargo aircraft in the world and the only plane that could transport them.
Within five weeks, the system was designed, built and shipped to Japan. The skids weighed about 22 metric tons each when shipped on three planes, but installed with shielding and vessels, some weigh nearly 100 tons.
The system was assembled in Japan in nine days and on June 14, 2011, was tested using clean water. Three days later it started treating contaminated water.
After the Three Mile Island partial nuclear meltdown in 1979, it took 18 months for a cesium removal system to start operating, according to AECOM. But the Fukushima, Japan, system designed in Richland and built in Colorado and California was removing radioactive cesium from the water fewer than 100 days following the tsunami.
The rainy season came early in 2011. Had Kurion's treatment system started operating about a week later, contaminated water would have started flooding from the plant back into the ocean, said John Raymont, Kurion president.
"It was a very dramatic race against time," he said.
A year after the tsunami hit the plant, the treatment system had processed 36 million gallons of contaminated water and removed 8.4 million curies of cesium.
Now it has cleaned 45.7 million gallons of radioactive water, or enough water to cover a football field 130 feet high, according to Kurion.
The system continues to operate to clean water used to cool the water and groundwater that is leaking into the contaminated plant.
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