Contamination of the Japanese environment after the Fukushima accident and associated doses to the population

Transcription

1 Contamination of the Japanese environment after the Fukushima accident and associated doses to the population M. Simon-Cornu & P. Renaud Winter-school EURADOS Milano February 11, 2016

2 At the origine of the consequences of the Fukushima accident were the radioactive deposits Source: WHO Fukushima report, reproduced from IAEA Chernobyl report kbq/m² Bq/m 2 (radiocésium) 2-4µSv/h Source: MEXT 2

3 Part 1: Foodstuff contamination and associated doses

4 Elements relative to foodstuffs contamination after an accidental deposit The most contaminated agricultural produce after an accidental radioactive deposition are those during cultivation or those the harvest of which is imminent (days to weeks depending on the type of production) Leaves are needed for the interception of deposits and a minimal growth-stage is also necessary for the transfer from leaves to edible part of the plant (fruit, grain, root ). This growth-stage is reached between mid-spring and summer for most of cultures. And even in this case, only a small part is transferred. Leafy-vegetables for which leaves are the edible part (salad, spinach, leek, cabbage ) in cultivation at the time of deposits are then potentially the most contaminated foodstuffs. Highest activity levels are reached immediately after the deposits. The plant growth leads then to a quick decrease of their massic activity (dilution) The root-transfer is very small, even negligible in relation to the foliartransfer, but long-lasting, decreasing slowly but faster than radioactive decay Contamination of animal products is directly linked to that of their food

5 The agro-climatic context in March 2011 in Japan An end of Winter in a temperate zone ; snowy-rain during the radioactive deposits Vegetables (and few strawberry) are the only crops in growing, under greenhouse notably Except some japanese apricot, fruit-trees have neither leaves nor flowers Some cereals are installed but are far from the flowering (in May) Some semi-natural vegetals and some specific shrub have their leaves (bamboo-trees, teatrees, aralia ) The most common feeding pratice for lifestock is based on importing fodder Kawamata valley on early April In March 2011, leafy-vegetebles, notably spinach, are by far, the most contaminated foodstuffs

6 Contamination of foodstuffs from the Fukushima prefecture Number of analyses 18,000 16,000 14,000 12,000 10, Crops Fukushima Prefecture Livestoke meats >Consumption limits 800 <Consumption limits Number of analyses of foodstuffs from the Fukushima Prefecture with measured activity above (respectively below) the consumption limits (CL) : 2000 Bq/kg for 131 I ; 500 Bq/kg until March 2012, and 100 Bq/kg since then for both cesiums. Due to the season of the accident (winter) and to the importation of fodder (and the control of their activity), crops and livestock products from the Fukushima Prefecture have remained overwhelmingly below the consumption limits (CL), even in Cow milk 6

7 Iodine-131 fate in weeds and leafy-vegetables Decrease of activities for iodine 131 due to radioactive decay (halflife: 8 days)+ other environmental processes => vanishing of iodine 131 after May 2011 Bq/kg Iodine 131 Leafy-vegetables L é gumes - feuilles à Kawamata from Kawamata Leafy-vegetables from Iitate Weed leaves from Kawamata-North Weed leaves from Kawamata-South Weed leaves from Iitate

8 Activities of Milk vs Weed Bq/L Iodine ,000,000 Milk from Kawamata and Iitate 1,000, ,000 10,000 1, CL : 200 Bq/L Milk from other localities of the Fukushima Prefecture Milk from others Prefectures Weeds from Iitate and Kawamata Theorical milk activity corresponding to weed consumption ,1 March April May

9 Equivalent dose to thyroid for non-evacuated persons UNSCEAR assessment: adult : 8 17 msv ; 1 year old child: msv 131 I in leafy-vegetables (Bq/kg) 100,000 (all pathways) Thyroid activity measurements show doses 3 to 5 times lower Doses quicky reached by the ingestion pathway Thyroid dose due to a consumption of 100g by a 1 year-old child and of 300g by an adult Bq/kg 20 msv (child); 7 msv (adult) 10,000 1,000 C. limit: 2000 Bq/kg Dose assessments using urine analysis msv for 5 adults and a 14 year-old child (corresponding intake of few kg of leafy-vegetables) 100 Kawamata - Iitate - mura Hitashi 4 days period curve A consumption during 1 month 140 msv (child) 50 msv (adult) mars mars 04 avril 14 avril 24 avril 04 mai 14 mai Contamination des denrées après un accident nucléaire et exposition de la population Ph. Renaud formation VetAgro 5-7 novembre 2014

10 Fate of Cesium in weeds and leafy-vegetables Bq/kg Cesium Bq/kg Decrease of activities of about a factor 100 to 1000 in 3 months for cesium 10,000,000 1,000,000 Leafy-vegetables from Kawamata Leafy-vegetables from Iitate Weed leaves from Kawamata-North Weed leaves from Kawamata-South Weed leaves from Iitate 100,000 10,000 1,000 CL 2011 : 500 Bq/kg March 8th, 2011 Avril 7, 2011 May 7, 2011 June 6,

11 Fruits activities Bq/kg cesium ,000 1 CL 2011 : 500 Bq/kg In 2011, quite moderate activities of fruits due to the date of deposits An afterglow of the initial foliartransfer in the following harvests CL since April 1st, March mars sept.-11 March mars sept.-12 March mars sept.-13 March mars sept.-14 March mars sept.-15 Strawberries Apples Persimmons Japanese apricot Cherries Peaches figs Kiwis Pears Grappes Citrus Nuts / chesnuts Fraises Abricots japonais Cerises Pêches Pommes Figues kiwis Poires Kakis Raisins Agrumes divers Fruits secs (chataignes, noix..) 11

12 Activities of foodstuffs from most contaminated but non-evacuated localities ( ) Activities of vegetables and livestocks products are overwhelmingly below detection limits (DL) which are 5 to 10 times below consumptions limits Bean species (notably soy) and rice are above detection limits. Due to a higher root-transfer (for beans) and probably to a water/leaves 1400 transfer during paddy floodings Fukushima Kori Date Katsurao FNPP 1, , >SM >DL <SM <DL DL values for vegetal foodstuffs DL max : 20 Dl mean : 8 DL values for beef DL max : 20 (25 in 2012) Dl mean : 15 DL values for milk DL max : 10 Dl mean : 5 Naraha 0 Vegetables Légumes Fresh Fruits fruits frais Viandes Beef Lait Cow de milk vache Haricots/soja Beans/soy Rice Riz 12

13 Activities of game meats Still high activities, most often far above consumption limits Number of analyzis 1,000 Fukushima Prefecture <Consumption limits >Consumption limits Game meats 13

14 Activities of game meats Cesium (Bq/kg) Fukushima Pref. Tochigi Pref. Chiba Pref. 100,000 others Pref. 10,000 1, March-11 April-12 May-13 June-14 July-15

15 Activities of game meats 10,000 Sika deer meat Spot-billed duck Asian black bear Versicolor pheasant Copper pheasant 1, March-11 March-12 March-13 March-14 March-15 15

16 Cs+ 137 Cs activities in mushrooms and edible wild plants plants Activités massiques en césiums (Bq/kg frais) Fukushima Chiba Gunma Ibaraki Iwate Kanagawa Miyagi Saitama Shitsuoka Tochigi Autres Préfectures Little spatial variability Strong between-species variability Long-term persistence 0 Mars-11 Mars-12 Mars-13 Mars-14 0 Mar-11 Sep-11 Mar-12 Sep-12 Mar-13 Sep-13 Mar-14 Sep Lactaire à lait abondant (lactarius volemus) Hypholome couleur de Brique (hypholoma sublateritium) Lactaire délicieux (lactarius deliciosus) Poule des bois (Grifola frondosa) Pleurote en huitre (pleurotus ostreatus) Armillaire couleur de miel (armillaria mellea) Pholiote ridée (cotinarius caperatus) Pholiote changeante (Pholiota Nameco) Feb Aug Feb Aug-12 9-Feb Aug-13 8-Feb-14 9-Aug-14 7-Feb-15 16

17 Cs activities of foodstuffs (synthesis) Bq/kg fresh Leafy-vegetables Ponct : Boar meat very ponct. : Beef Boar meat p onct. Game meat Mushrooms Beef Bamboo shoots from most contaminated but non-evacuated areas Game meat Mushrooms Some kinds of fruits 2 ponct. Milk, meats crops Milk Meats, Crops 2011 Ponct : Boar meat Boar meat ponct. Mushrooms Game meat Mushrooms ponct. : Rice, soy 3 Bamboo shots Fruits, Beef Bambou shoots Vegetables Milk, Other meats Wheat, barley, Vegetables Ponct : Boar meat Boar meat Game meat Most sensitive mushrooms ponct. : Rice, soy 3 Very ponct.. Bamboo shots Mushrooms, Fruits Bamboo shoots Rice soy 3 Ponct. Beef, Vegetables Milk, Other meats Wheat, barley, Vegetables Ponct : Boar meat Game meat Most sensitive mushrooms Mushrooms Bamboo shoots Ponct. Some kinds of Fruits Rice, soy 3 Milk, Meats Crops and : Raw fresh products, 2 : Apricots, kiwis, persimmons, nuts species 3 : others kinds of bean : Blackwheat, red beans 17

18 Assessments of effective doses potentially received by foodstuffs ingestion For adults living on most contaminated localities, but non-evacuated, who would have consummed exclusively locally produced foodstuffs but respecting the consumption limits (assessments using japanese dietary habits) Effective dose for the period May-December ,6 msv Effective dose for ,3 msv Iitate 30 km 20 km Fukushima Kori Date 30 km 20 km Katsurao Fukushima- Daiichi NPP Fukushima- Daiichi NPP 20 km Naraha 20 km 30 km 30 km

19 137 Cs Whole-body counting results number of results < 1 msv* msv msv 10 > 3 msv 2 Total * 1 msv = Bq/boby (adult) = Bq/kg Whole-body counting results for the period June December 2012 % above 300 Bq/body* Whole-body counting results concerning 32,811 persons, including 19,520 below 15 years-old; maximum dose assessed: 1,1 msv tous All âges ages enfants < 15 year-old <15ans Monitoring on 40 children above 300 Bq/body (Bq/body) sept.-11 nov.-11 janv.-12 mars-12 mai-12 juil.-12 sept.-12 nov.-12 *300 Bq/body ~ 21 µsv/an for 10 year-old child, ~ 13 µsv/an (15 year-old), ~ 10 µsv/an (adult) 19

20 2 nd part : Evolution of dose rate in air and external doses

21 Evolution of dose rate in air during months following deposits % of deposited activity Dose rate - µsv/h 100% % 80% 70% 60% 50% 40% 30% Tellurium iodine 132 Iodine 131 Baryum Lanthane 140 Cesium 136 Tellurium 129m + Tellurium 129 Cesium 134 Cesium 137 Dose rate measured in Namie (Akougi Teshichiro ) % 40 10% 20 0% 0 March 15, 2011 April 15, 2011 May 15, 2011 June 15, 2011 July 17, 2011 Dose rate in air falls down quickly after deposits due to the radioactive decay of short-life radionuclides; two months after deposits, it is mainly due to cesium

22 Evolution of airborne dose during the 2 firsts years Maps of airborn dose rate at 1 m above soil, 80km around the Fukushima power plant, as seen by 6 among the 9 firsts airborned campaigns Airborn dose rates at 1m from the ground (µsv/h) Fukushi ma Daiichi NPS Fukushi ma Daiichi NPS Fukushi ma Daiichi NPS Not measured April 2011 July 2011 Nov The natural radionuclides are included. Fukushi ma Daiichi NPS Fukushi ma Daiichi NPS Fukushi ma Daiichi NPS June 2012 Nov Sept The dose rate has decreased more quickly than expected by the decay of 134 Cs

23 Normalized mean ADR (-) 1 Decrease of air dose rate 0,8 0,6 0,4 Theoretical (physical decay) Carborne (urban areas) 0,2 Airborne (surveys 1, 3, 4 to 7) Carborne( evergreen forest) In situ (surveys 1 to 3a,b) Carborne (deciduous forest) Carborne (surveys 1 to 7) Carborne (agricultural land) 0 03/ / / / / / /2014 Dose rate decreases at different rates depending on the kind of surface This decrease could be be linked to cesium moving: The falling of tree leaves (measurement bias), depth migration, run-off Remediation actions: ploughing, surface washout (artificial notably) 23

24 Efficiency of remediation actions Variable efficiency, depends on the type of environment and on initial dose rate : highest efficiency for highest dose rate Mean reduction factor in terms of dose: 20 to 50% Mean reduction factor in terms of activity: 50 to 70% by washing artificial surfaces; 80 to 90% by removing top soil layer Air dose rate Tamura Town Homes Agri Woods near homes Roads (n=4130) (n=3774) (n=3359) (n=2250) 24

25 Air dose rates vs individual effective doses by external pathway Inside house, dose rate is lower than outside Usely, considering 16h/d inside Theoretical effective dose = ½ dose in outside air (operationally used by japanese, considering that 0,23 µsv/h allows respecting 1 msv/an) The measurement results of individual monitoring show that: Effective dose = 1/3 to 1/5 dose in outside air

26 Air dose rates vs individual effective doses by external pathway 白根 山舟生 富野 梁川 東大枝 伊達 大石 大泉 粟野 五十沢 二井田 堰本 保原 大立目 金原田 上保原 伏黒 山野川 箱崎 中川 掛田 所沢 御代田 上手渡 石田 下手渡 山戸田 柱田 布川 糠田 月舘 高成田 富沢 上小国 下小国 Individual monitoring of 53,000 persons (july 2012 to June 2013) and 18,700 persons (July June 2014) from various areas of Date city Ratio (dose in air/effective dose) rapport (dose dans l'air/dose indiv. mesurée) Dose dans in l'air outside (msv/an) air (msv/y) Dose Theoretical individuelle individual théorique dose (msv/an) (msv/y) Dose individuelle mesurée (msv/an) Individual effective dose (msv/y) Areas of Date city 26

27 UNSCAER,

28 Thanks for your attention

29 Remediation actions Washing and brushing of roofs and walls with pressured water, sanding The remove of soil around a school Cleaning a drain piping Suction of cleaning water Removing of litter close to a house removing a "hot spot" at the bottom a discharge pipe of a gutter Street cleaning 29

30 Remediation actions size and tree trimming, lawn mowing Efficiency of a supplementary ploughing: nsv/v Efficiency of ploughing: nsv/h Non-ploughed soil: nsv/h 30

31 Actions de décontamination Ultra-high pression cleaning Sand or steal-balled blasting Ice blasting Cleaning Asphalt removing Fixing spray for soil 3-5μSv/h <1.5μSv/h 31