Cleaning Up Catastrophic Messes
2014 R&D 100 Winner
On March 11, 2011, the Fukushima I Nuclear Power Plant experienced a catastrophic failure, resulting in the meltdown of three of the plant’s six nuclear reactors. The failure occurred when the plant was hit by a tsunami triggered by the magnitude 9.0 Tohoku earthquake. The plant began releasing substantial amounts of radioactive material on March 12, becoming the largest nuclear incident since the Chernobyl disaster in April 1986.
Hitachi Research Laboratory and Hitachi-GE Nuclear Energy Ltd joined together to develop the Hitachi Cs-Sr simultaneous adsorbent to treat radionuclide-contaminated water being stored at the Fukushima Daiichi Nuclear Power Station. This adsorbent is the first of its kind that can simultaneously adsorb radioactive cesium (Cs) and radioactive strontium (Sr) dissolved in water at a high adsorption rate of 99% or better, satisfying the standards for drinking water established by the Japanese Ministry of Health, Labor and Welfare (radiation dose of 10 Bq/L or less) using half the quantity of conventional adsorbents.
The adsorbent consists of inorganic substances such as crystalline silicotitanate (CST) pelletized using a kind of inorganic binder. Pelletized CST is treated with a dilute sodium hydroxide solution for chemical surface modification and for increasing the amount of sodium cations (Na+) by substituting them for hydrogen cations. Adsorption of Cs and Sr is caused by the ion exchange reaction of Na on the adsorbent surface with Cs and Sr. The adsorbent has separate adsorption sites (or reaction sites) for Cs and Sr, and it adsorbs each separately without any interference.
The Hitachi Cs-Sr simultaneous adsorbent Development Team
Takashi Asano, Principal Developer, Hitachi-GE Nuclear Energy Ltd.
Yuko Kani, Principal Developer, Hitachi Research Laboratory, Hitachi Ltd.
Mamoru Kamoshida, Hitachi Research Laboratory, Hitachi Ltd.
Noriaki Takeshi, Hitachi-GE Nuclear Energy Ltd.