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

Iyatomi, Yosuke ; Ogata, Nobuhisa ; Sugihara, Kozo; Seko, Noriaki; Hoshina, Hiroyuki; Okada, Kenji*; Tamada, Masao

The concentrations of fluorine (7.29.5 mg/L) and boron (0.81.5 mg/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: 0.8 mg/L, boron: 1 mg/L) at a water treatment facility. Coagulation treatment and ion exchange treatment are applied for fluorine and boron respectively. Consequently, we have started research on efficient groundwater treatment for fluorine and boron using radiation-induced graft polymerization adsorbent. 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. As over 90% of fluorine must be removed from the groundwater in order to meet the environmental standard, the treatment method for fluorine using radiation-induced graft polymerization adsorbent is less efficient than for boron and will need further improvement. Therefore, we are planning to perform a durability evaluation and recycling test of adsorbent using improved testing equipment for enhancing the efficiency.