Estimation of groundwater treatment using radiation-induced graft polymerization adsorbent at the Mizunami Underground Research Laboratory. Annual report on 2006 fiscal year (Joint research)

The concentrations of fluorine (7.2-9.5mg/L) and boron (0.8-1.5mg/L) dissolved in groundwater pumped from shafts during excavation at the Mizunami Underground Research Laboratory (MIU), Tono Geoscience Centre, are reduced to the levels below the environmental standards (fluorine:0.8mg/L, boron:1mg/L) at a water treatment facility. Coagulation treatment and ion exchange treatment are applied for fluorine and boron respectively. On the other hand, the Quantum Beam Science Directorate in JAEA has applied a groundwater treatment method using radiation-induced graft polymerization adsorbent to remove rare metals dissolved in hot springs and sea water. Consequently, the Environment and Industrial Materials Research Division, Quantum Beam Science Directorate and the Tono Geoscientific Research Unit, Geological Isolation Research and Development Directorate have started collaborative research on groundwater treatment for fluorine and boron. Regarding the treatment for boron, over 95% of boron has been removed from groundwater volume of 760 times greater than the volume of the adsorbent. With respect to the fluorine removal, 95% of fluorine has been removed from groundwater volume of 320 times greater than the volume of the adsorbent. When the high concentration material, fluorine in groundwater, has been removed by low concentration, the adsorbent did not work enough the ability of removal. We'll need further improvement that the treatment method for fluorine using radiation-induced graft polymerization adsorbent is more efficient than coagulation treatment at a water treatment facility. Therefore, we are planning to perform a durability evaluation and recycling test of adsorbent using improved testing equipment for enhancing the efficiency. (author)