Decontamination of school facilities in Fukushima-city

Yoshikawa, Hideki; Iijima, Kazuki  ; Sasamoto, Hiroshi   ; Fujiwara, Kenso ; Mitsui, Seiichiro  ; Kitamura, Akira  ; Kurikami, Hiroshi  ; Tokizawa, Takayuki; Yui, Mikazu; Nakayama, Shinichi 

Following the release of radionuclides into the environment as a result of the accident at Fukushima Daiichi Nuclear Power Plant, Japan Atomic Energy Agency (JAEA) had to develop an immediate and effective method of reducing the dose rate received by students in school facilities. A demonstration of a reducing method was carried out by JAEA at a junior high school ground and kindergarten yard in the center of Fukushima-city. Dose rates of the released radionuclides are largely controlled by the ground level contamination and accumulation of mainly cesium-137 (Cs) and cesium-134 (Cs) in populated areas. An effective means of reducing dose rate was to remove the surface soil and to bury it on-site under fresh uncontaminated soil or soil collected under deep depth at the site for shielding. The dose rate at1 m above ground level was reduced from 2.5 Sv/h to 0.15 Sv/h.