Fukushima Dam: Mud Sample Contains Radioactive Cesium At 3,000,000 Bq/m2

3,000,000 Bq/m2 of cesium from the dam in Fukushima (Fukushima Diary, Mar 13, 2012):

Ministry of Education, Culture, Sports, Science and Technology found out high level of cesium is concentrated in the bottom of the lake called Horai dam. This dam is to generate electricity, located in Nihonmatsu (60km North west to Fukushima plants), where is in Abukuma river.

Prof. Onda from Tsukuba university reported the mud sample taken in 20 cm deep underground of the bottom of the lake contained 3,000,000 Bq/m2 of cesium, where other samples taken in 4 other reservoirs around Horai lake showed 200,000~400,000 Bq/m2 of cesium.(July and August in 2011)  3,000,000 Bq/m2 is as contaminated as soil of 20km area.

Prof. Onda explains, cesium doesn’t melt into the water. Water of downstream is not harmful to drink.

However, they also found out that when the soil is highly contaminated, water of the downstream river is also highly contaminated, which proves Prof. Onda is wrong. Cesium was attached to the small swimming sand, which is smaller than 0.1mm diameter.

Ministry of Land, Infrastructure, Transport and Tourism states there is the risk of the contaminated mud to flow into the downstream in flood, but there is no plan of decontamination at the moment.

Other nuclides such as strontium or plutonium were not tested.


放射性物質:ダム底の泥に 雨で川へ流れ濃縮か 福島
阿武隈川中流域にある発電用の「蓬萊(ほうらい)ダム」(福島県二本松市、福島市、貯水量約380万立方メートル)の底の泥に大量の放射性セシウムが蓄積 していることが13日、文部科学省の調査で判明した。付近の貯水池と比べ10倍の濃度だった。東京電力福島第1原発事故で土壌に蓄積したセシウムが、雨で 土と一緒に川へ流れ込み、ダムでせき止められて濃縮したとみられる。

同省の委託で調査した恩田裕一筑波大教授(水文学)が同日のシンポジウムで報告した。恩田教授は昨年7~8月、原発の西北西約60キロにある蓬萊ダ ムの底の泥を深さ20センチまで採取、乾燥後のセシウム濃度を周辺の4カ所の貯水池の泥と比べた。その結果、蓬萊ダムの泥は1平方メートル当たり約 3000キロベクレルで、原発から半径20キロ圏内の警戒区域内の土壌汚染濃度に相当した。他の貯水池の同200~400キロベクレルに比べ約10倍あっ た。




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