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Cs inventory吉村 和也; 中間 茂雄; 藤原 健壮
Journal of Radiation Protection and Research, 47(1), p.30 - 38, 2022/03
To better understand the radiation environment in urban area, this study investigated temporal changes in air dose rate as well as Cs inventories (Bq m
) in both residential areas and agricultural fields. The air dose rate decreased faster in residential areas than in agricultural fields. It was also observed that the Cs inventory on paved surfaces decreased with time due to horizontal wash-off, while the permeable surfaces showed no significant temporal changes unless decontamination. Our results suggest that the horizontal wash-off of Cs on the paved surfaces facilitated the decrease in air dose rate in urban areas to a greater extent compared with agricultural fields, of which air dose rate was decreased due to vertical migration of Cs.
吉村 和也
Journal of Nuclear Science and Technology, 59(1), p.25 - 33, 2022/01
被引用回数：6 パーセンタイル：72.21(Nuclear Science & Technology)Our goal is to review and synthesize knowledge obtained after the Fukushima Dai-ichi and Chernobyl Nuclear Power Plant accidents to provide important information to better understand environmental radiation in urban areas. As was reported in Europe, the cesium-137 (Cs) inventory (Bq m) was high on soil grounds but relatively low on impermeable surfaces such as roads and roofs because of the high initial runoff and wash-off of Cs from surfaces. The air dose rate in urban areas decreased faster than that in other land uses owing to large Cs wash-off on pavements and anthropogenic effects, such as decontamination. Thus, environmental recovery in urban area was thought to be facilitated by human activities and Cs wash-off, reducing radiation risk of local residents comparing to the other land uses.
尾崎 宏和*; 吉村 和也; 朝岡 良浩*; 林 誠二*
Environmental Monitoring and Assessment, 193(6), p.369_1 - 369_9, 2021/06
被引用回数：6 パーセンタイル：41.49(Environmental Sciences)We investigated influence of road effluent on Antimony (Sb) in combined sewer water under rainy and dry weather conditions. Sb in road effluent showed significantly higher concentration than sewer, and Sb concentration in sewer during the wet weather was also significantly higher than that during the dry weather. Furthermore, Sb concentration in the sewer water decreased with time during a wash-off event. Clear positive relationships between Sb and Cu, and Sb and Ba in both in road effluent and road dust extract indicated an impact from brake abrasion because brake lining contains Cu, Sb and Ba in high concentration. Approximately 42% of Sb load occurred during the wash-off event while those of Cu and Ba were much less. Unlike Cu and Ba, we conclude that Sb in combined sewer water is largely dependent on road effluent during wet weather, resulted by wash-off of road dust probably associating with brake lining abrasion.
吉村 和也; 藤原 健壮; 中間 茂雄
Radiation Protection Dosimetry, 184(3-4), p.315 - 318, 2019/10
被引用回数：1 パーセンタイル：11.15(Environmental Sciences)To investigate the applicability of autonomous unmanned helicopter (AUH) survey, the result of AUH survey in sub-urban area was compared with air dose rate measured on the ground. The AUH survey showed similar measurement error with the errors reported for plane permeable fields (within uncertainty factor of 2), suggesting that the AUH survey is effective tool to clarify the air dose rate distribution in urban area. The other survey tools on the ground, however, is necessary to clarify the distribution in detail. The measurement error of the AUH survey was suggested to be attributed to the spatial heterogeneity of coefficient to convert the 
ray count rate detected by AUH to the air dose rate.
吉村 和也
no journal, ,
This study evaluated Cs-137 inventories for 11 buildings in the evacuation zone in 2015 and 2016. Additionally, the results were analyzed with the data obtained in the model decontamination project to evaluate temporal trend in the distribution during the initial five years after the accident. The inventory on paved ground accounted for 20% of that on permeable field, and other building components such as roof, wall and window showed low inventory (less than 4%). These values indicate the limited contamination of urban area. The inventories of paved ground, roof and wall in 2011 and 2012 showed similar values with those obtained in this study, suggesting that initial run-off and the following wash-off effects during the first year after the accident largely defined the distribution of Cs-137 in urban area.
吉村 和也
no journal, ,
Current situation and prediction of the radiocesium contamination and air dose rate in the residential areas are a large concern for public and government. Residential area is a multimedia-environment composed of diverse surfaces such as pavements and buildings in addition to permeable fields like agricultural lands. Since radiocesium behavior depends on the surfaces1, their distribution and time dependency differ greatly from those in other land uses. Therefore, detailed monitoring of radiocesium and air dose rate focusing on the residential areas is necessary to obtain effective and practical information for radiation protection. This presentation shows monitoring tools we employed to residential areas after the FDNPP accident and some findings obtained by the monitoring.
吉村 和也
no journal, ,
Air dose rate and Cs inventories were investigated using in-situ measurement methods in residential areas located in an evacuation zone in Fukushima. The air dose rate distribution was investigated through a walking survey, which was conducted by operators carrying a -ray detector on their backs. The Cs inventories on paved and permeable grounds were measured by a portable -ray detector equipped with a collimator. The air dose rate decreased faster in residential areas than in agricultural fields. The Cs inventory on paved surfaces decreased with time owing to the horizontal wash-off, while the horizontal wash-off of Cs were not confirmed on permeable surfaces. These findings suggest that the horizontal wash-off of Cs on paved surfaces facilitated the air dose rate decrease in residential areas to a greater extent compared with agricultural fields. As shown above, the in-situ measurement methods used in this study are useful tool to evaluate time dependency of environmental radiation.
吉村 和也
no journal, ,
This study shows decreases in air dose rate and Cs activity on paved surface, which is a major radiation source in urban area, observed in urban areas 5-10 km far from the FDNPP. Air dose rate in Difficult-to-Return Zone, of which anthropogenic effects was ignorable, decreased faster in urban area than agricultural fields. The wash-off of radiocesium on paved surface was indicated to facilitate the decrease in air dose rate in urban area. The air dose rate in Specified Reconstruction and Revitalization Base Areas decreased faster than the other zones due to the decontamination, which reduced Cs activity on paved surface to less than about 20%. In areas where were not affected by decontamination, Residential Zone showed faster decreases in air dose rate and Cs activity on paved surface than the Difficult-to-Return Zone. This suggests that the anthropogenic effects other than the decontamination facilitate the decrease in air dose rate in urban areas.
