Radiation Monitoring Radioactive Iodine (I‐131) of Clean Water (the Tokyo Metropolis and 12 Prefectures) 110 Bq/kg in Tochigi Prefecture on March 24 Morioka City, Iwate Akita City, Akita Yamagata City, Yamagata Hitachinaka City, Ibaraki Utsunomiya City, Tochigi Maebashi City, Gunma Saitama City, Saitama Ichihara City, Chiba Shinjuku Ward, Tokyo Chigasaki City, Kanagawa Niigata City, Niigata Kofu City, Yamanashi Shizuoka City, Shizuoka Radiation Monitoring of Clean Water 7.6 Radioactive Iodine (I‐131) in Tap Water⽔道⽔中の放射性ヨウ素（I-131） Bq/kg: becquerels per kilogram * In the figure above, values below the detection lower limit are treated as 0 for convenience. * Only prefectures where radioactive iodine was detected in the measurement are indicated in the figure. Interim Report on Measures for Radioactive Materials in Tap Water Prepared based on the reference material for the Ministry of Health, Labour and Welfare (MHLW)'s Study Meeting on Measures for Radioactive Materials in Tap Water (June 2011) As a result of the inspection of radioactive materials in tap water conducted by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), radioactive iodine was detected in the Tokyo Metropolis and 12 prefectures out of 47 prefectures nationwide. Highest concentrations were detected at the respective locations from March 18 to 29, 2011, but I-131 concentrations turned to decrease in many locations in the latter half of March 2011. In and after April 2011, only small amounts of I-131 were detected at some of these locations. Included in this reference material on March 31, 2013 Updated on January 18, 2016 25 Radiation Monitoring Radioactive Cesium (Cs‐134 + Cs‐137) of Clean Water (the Tokyo Metropolis and 7 Prefectures) 18 Bq/kg in Ibaraki Prefecture on March 21 Morioka City, Iwate Yamagata City, Yamagata Hitachinaka City, Ibaraki Utsunomiya City, Tochigi Maebashi City, Gunma Saitama City, Saitama Ichihara City, Chiba Shinjuku Ward, Tokyo Radiation Monitoring of Clean Water 7.6 Radioactive Cesium (Cs‐134 + Cs‐137) in Tap Water⽔道⽔中の放射性セシウム（Cs-134 +Cs-137） * In the figure above, values below the detection lower limit are treated as 0 for convenience. Bq/kg:becquerels per kilogram * Only prefectures where radioactive cesium was detected in the measurement are indicated in the figure. * ● is marked on dates when the readings were ND (not detected; below the detection lower limit). Interim Report on Measures for Radioactive Materials in Tap Water Prepared based on the reference material for the Ministry of Health, Labour and Welfare (MHLW)'s Study Meeting on Measures for Radioactive Materials in Tap Water (June 2011) As a result of the inspection of radioactive materials in tap water conducted by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), radioactive cesium was detected in the Tokyo Metropolis and 7 prefectures out of 47 prefectures nationwide. Highest concentrations were detected at the respective locations from March 20 to early April 2011, but radioactive cesium concentrations were relatively smaller than radioactive iodine concentrations. In and after April 2011, only small amounts of radioactive cesium were detected at some of these locations. Included in this reference material on March 31, 2013 Updated on January 18, 2016 26 31,2013 materialonMarch Included inthisreference detected sinceMay2011,nottomentionshort-half-liferadioactiveiodine. The long-termtapwatermonitoringshowedthatradioactivecesiumhasseldombeen Monitoring of Clean Water Radiation (Bq/kg) (Bq/kg) 100 110 10 20 30 40 50 60 70 80 90 10 12 14 16 18 20 0 0 2 4 6 8 3/18 3/18 3/25 3/25 4/1 4/1 Tap Water Results of Long‐term Radiation Monitoring of 4/8 4/8 4/15 4/15 4/22 4/22 Radioactive Cesium (Cs‐134 + Cs‐137) in Tap Water 4/29 4/29 5/6 5/6 5/13 5/13 5/20 5/20 5/27 Radioactive Iodine (I‐131) in Tap Water 5/27 6/3 6/3 6/10 6/10 6/17 6/17 6/24 6/24 7/1 7/1 7/8 7/8 7/15 7/15 7/22 7/22 27 千葉県市原市 群⾺県前橋市 茨城県ひたちなか市 岩⼿県盛岡市 静岡県静岡市 新潟県新潟市 東京都新宿区 埼⽟県さいたま市 栃⽊県宇都宮市 ⼭形県⼭形市 岩⼿県盛岡市 7/29 Ichihara City, Chiba Maebashi City, Gunma Hitachinaka City, Ibaraki Morioka City, Iwate 7/29 Shizuoka City, Shizuoka Niigata City, Niigata Shinjuku Ward, Tokyo Saitama City, Saitama Utsunomiya City, Tochigi Yamagata City, Yamagata Morioka City, Iwate 8/5 8/5 Committee on Living Environment 8/12 8/12 8/19 8/19 8/26 8/26 9/2 9/2 9/9 9/9 9/16 9/16 9/23 9/23 9/30 9/30 10/7 10/7 10/14 10/14 10/21 東京都新宿区 埼⽟県さいたま市 栃⽊県宇都宮市 ⼭形県⼭形市 10/21 ⼭梨県甲府市 神奈川県茅ヶ崎市 千葉県市原市 群⾺県前橋市 茨城県ひたちなか市 秋⽥県秋⽥市 Shinjuku Ward, Tokyo Saitama City, Saitama Utsunomiya City, Tochigi Yamagata City, Yamagata 10/28 10/28 Kofu City, Yamanashi Chigasaki City, Kanagawa Ichihara City, Chiba Maebashi City, Gunma Hitachinaka City, Ibaraki Akita City, Akita and Water Supply in March 2012 11/4 11/4 11/11 11/11 11/18 11/18 11/25 11/25 12/2 12/2 12/9 12/9 12/16 12/16 12/23 12/23 12/30 12/30 1/6 1/6 1/13 1/13 Radiation Monitoring of Clean Water Clean of Monitoring Radiation 7.6 Radiation Monitoring of Clean Water Inspections by Water Suppliers Changes in Number of Specimens for Radioactive Cesium Inspection (specimens) Detection of Radioactive Cesium (Purified Water) (Bq/kg) (Note) Number of cases where radioactive cesium Purified Raw 浄⽔ 原⽔ 180 detection was reported (specimens) water water 165 Number of specimens with either showing a ≦ 8000 ⽚⽅がvalue over 1 and the total being 10 or less>1、合計が 10の検出検体数 160 7176 合計がNumber of specimens with the total being >10の検出検体数 over 10 7000 6812 6680 6670 6666 6753 6441 6573 6418 140 140.5 最⾼濃度Maximum concentration (Cs‐134+Cs‐137)Cs-134+Cs-137134Cs+137Cs（Bq/kg） 6101 6000 120 5000 100 130 83 4000 80 68.8 3000 2603 60 67 2000 40 29 1000 20 19 35 6.1 3.1 3 212 133 148 165 158 158 186 168 173 16 13 1.5 119 127 110.5 1 0.4 0 0 0 6 6 Radiation Monitoring of Clean Water 7.6 Bq/kg: becquerels per kilogram 12th Health Sciences Council's Committee on Living Environment and Water Supply in March 2012 Water suppliers conduct inspections of radioactive cesium for approx. 6,000 to 7,000 specimens of purified water and over 100 specimens of raw water per month. The maximum monthly value of radioactive cesium concentration was 140.5 Bq/kg detected in March 2011, but the value declined gradually thereafter and there has been no report of radioactive cesium detection at a level exceeding 10 Bq/kg since June 2011. Included in this reference material on March 31, 2013 28 Radiation Monitoring of Clean Water Behavior of Radioactive Cesium Conceptual Diagram of Behavior of Radioactive Cesium Environmental Water Tap water Air water purification (mainly river water) Cs I May cesium iodide, gaseous cesium, etc. Cs Cs be contained? Cs Cs Mote Removal Mote (coagulating sedimentation, filtering) ＋ ＋ Particulate cesium Cs Partial removal Cs Cesium ion (adsorption, coagulating sedimentation, filtering) Cesium may exist in such forms as particulate Radiation Monitoring of Clean Water 7.6 cesium or Cs+ (cation) in environmental water. Generally, cations are easily adsorbed by ＋ adsorptive suspensoids with exchange capacity. I Iodine Cs Cesium ion Prepared based on the reference material for the 12th Health Sciences Council's Committee on Living Environment and Water Supply in March 2012 Radioactive cesium discharged due to the accident at Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi NPS consists of Cs-134 and Cs-137 in equal proportion (1:1) and has also been detected at the same rate in the environment. Radioactive cesium was in the form of particles or gas immediately after discharge from the NPS, but it is considered to have fallen down onto the ground surface and to have been adsorbed into soil and particles, etc. In water, radioactive cesium is adsorbed into particles and tends to behave in the same manner as soil or other suspensoids, and therefore, is highly likely to be reduced by removing suspensoids in water. Included in this reference material on March 31, 2013 Updated on January 18, 2016 29 Radiation Monitoring of Clean Water Control of Radioactive Cesium Most of the radioactive cesium that reaches sources of tap water is adsorbed into suspensoids such as soil and flows out. Therefore, radioactive cesium can be controlled through strict turbidity management. Example of Behavior of Radioactive Cesium (Cs‐134 and Cs‐137) a浄⽔場における放射性セシウム(134Cs、137Cs)の挙動例t Water Purification Plant National Institute of Public Health (Kosaka, et al., Journal of国立保健医療科学院（投稿中データ） Japan Water Works Association, 2014) Cs-137 Cs-134 Radioactive cesium (Bq/L) Radioactive <0.83 <0.59 <0.76 <0.67 <0.58 <0.50 <1.0 <0.47 <0.58 <0.57 Radiation Monitoring of Clean Water 7.6 Water after Biological activated Raw water sedimentation carbon treated water Rapid filtered water Zeolite, ion exchangers, nanofiltration membranes and reverse osmosis membranes are professionally used for removing radioactive materials, but these cannot be used for ordinary water purification due to high cost, required facilities and inefficiency (in particular, the use of nanofiltration membranes and reverse osmosis membranes is power consuming). Bq/L: becquerels per liter 12th Health Sciences Council's Committee on Living Environment and Water Supply in March 2012 As of April 2011, radioactive cesium concentrations in raw water, water after sedimentation, biological activated carbon treated water, and rapid filtered water were measured at water purification plants in Fukushima Prefecture.