title: Measurement of air dose rates over a wide area around the Fukushima Dai-ichi Nuclear Power Plant through a series of car-borne surveys.
abstract: A series of car-borne surveys using the Kyoto University RAdiation MApping (KURAMA) and KURAMA-II survey systems has been conducted over a wide area in eastern Japan since June 2011 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant and to evaluate the time-dependent trend of decrease in air dose rates. An automated data processing system for the KURAMA-II system was established, which enabled rapid analysis of large amounts of data obtained using about 100 KURAMA-II units. The initial data used for evaluating the migration status of radioactive cesium were obtained in the first survey, followed by other car-borne surveys conducted over more extensive and wider measurement ranges. By comparing the measured air dose rates obtained in each survey (until December 2012), the decreasing trend of air dose rates measured through car-borne surveys was found to be more pronounced than those expected on the basis of the physical decay of radioactive cesium and of the air dose rates measured using NaI (Tl) survey meters in the areas surrounding the roadways. In addition, it was found that the extent of decrease in air dose rates depended on land use, wherein it decreased faster for land used as building sites than for forested areas.
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan. Electronic address: andoh.masaki@jaea.go.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Andoh
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nakahara
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Matsuda
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Takahashi
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mikami
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kinouchi
authors.affiliation: Hitachi Solutions East Japan, Ltd., NBF Sendai Honcho Bldg., 2-16-10 Honcho, Aoba-ku, Sendai, Miyagi 980-0014, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Sato
authors.affiliation: Kyoto University Research Reactor Institute, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanigaki
authors.affiliation: Kyoto University Research Reactor Institute, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Takamiya
authors.affiliation: Kyoto University Research Reactor Institute, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Sato
authors.affiliation: Kyoto University Research Reactor Institute, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Okumura
authors.affiliation: National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Uchihori
authors.affiliation: Japan Atomic Energy Agency, 2-2-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8577, Japan.
authors.forename: Kimiaki
authors.initials: K
authors.lastname: Saito
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001336:Automobiles; D062406:Fukushima Nuclear Accident; D007564:Japan; D055848:Nuclear Power Plants; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000379:methods*; D011847:Radioactive Fallout / Q000032:analysis*; D011868:Radioisotopes / Q000032:analysis*; D012621:Seasons
chemical_list: D000396:Air Pollutants, Radioactive; D011847:Radioactive Fallout; D011868:Radioisotopes
keywords: Air dose rate; Car-borne survey; CsI (Tl) scintillation detector; Fukushima Dai-ichi NPP accident; KURAMA; KURAMA-II