After setbacks earlier in the week, Tokyo Electric Power Co. plans to deploy a crucial water treatment system at the Fukushima Daiichi nuclear plant today.TEPCO completed testing the system to treat some 105,000 metric tons of irradiated water in plant basements Thursday, Japan Today reported. TEPCO had hoped to put the system to use Wednesday, but the company reported last weekend that operation would be delayed because of leaks and a valve malfunction. After more work this week, TEPCO now says the system is ready for use and has reduced the water's cesium in test runs to 1/10,000th previous levels.Following the March 11 earthquake, tsunami and subsequent station blackout at Fukushima Daiichi, contaminated water flooding plant structures has prevented repairs to safety systems, leaked twice into the ocean and now threatens to overflow from basements and tunnels. Much of it passed over damaged reactor cores while crews cooled reactors using outside water, leaving behind high concentrations of radioactive isotopes.The treatment system is expected to process up to 1,200 tons of water per day and eventually recycle it as core coolant to reduce the volume of water entering the plant. Areva, in partnership with Veolia Water, engineered the system, which includes technology from Kurion, Inc.The system shares similarities with Areva's French La Hague and Melox facilities. It uses zeolite filters to turn cesium and other contaminants into a solid that can then be collected and treated separately.A recent report in the journal Nature described the system in further detail:"The water will pass through Kurion's filters, which contain a zeolite mineral - an extremely porous aluminosilicate that loosely binds metal ions. Through a combination of adsorption and ion exchange, the filters will trap the radioactive elements strontium-90, caesium-134 and caesium-137, reducing their concentration in the water by a thousand times.
Areva's process will then take over. The water will pass into a series of tanks, where it will mix with reagents such as nickel ferrocyanide and barium sulphate, along with polymers and sand. The dissolved radioactive metals will form precipitates and colloids, which can be trapped as a radioactive sludge, allowing the water to be desalinated and fed back into the reactors."
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