Thursday, July 26, 2012

No. 572: Successful development of a technology to harden radioactive effluent (July 26, 2012)

Desperate efforts are being made to develop a technology for effective and efficient treatment of polluted water in the Fukushima Daiichi Nuclear Power Plant. A research team of Showa Denko and Hitoshi Mimura of Tohoku University developed a technology to bake and harden residues of highly concentrated radioactive effluent, making it possible to harden unstable sludge residues into a stable substance. Ferrocyanide adsorbs radioactive substances like cesium effectively. Although it has 10 times stronger adsorption power than zeolite, it deposits muddy substance called waste sludge. The purification equipment from Areva of France running in Fukushima uses ferrocyanide. In Fukushima, the waste tank installed underground has a capacity of 700 cubic meters, but it is already filled with 600 cubic meters of waste sludge at present.

The above research team mixed ferrocyanide residues with special zeolite at a ratio of 1 to 1-2 and baked them at 800-1,000 degrees centigrade, and subsequently pressed the resultant product under high pressure. This technology can seal radioactive substances completely in a solid as stable as dried cement. Should this technology be applied, it will be possible to establish a treatment cycle that scoops the surface soil in the highly contaminated area, mixes the surface soil with water and ferrocyanide to eliminate radioactive substances, and solidifies the residue. The new technology has rather high removal efficiency because it can separate cesium and strontium from the soil almost entirely. Showa Denko plans to sell it to Tokyo Electric Power Company with the help of Atomic Energy Society of Japan.

Toshiba presented the manufacturing process of the Advanced Liquid Processing System (ALPS) that can eliminate 62 kinds of radioactive substances including strontium. It can process 500 tons of polluted water per day. Because about 200,000 tons of polluted water still exists on the premises of the Fukushima Daiichi Nuclear Power Plant, it will supposedly take about 400 days to treat all the polluted water. Toshiba’s ALPS will be installed late August, and the trial run will start in September. Using the special resins and activated charcoal, it can decrease the concentration of radioactive substances to lower than the legal level.  

The adsorption tower of Toshiba’s Advanced Liquid Processing System (ALPS) that can eliminate 62 kinds of radioactive substances in water.  

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