1. Opening Remarks - Technical Briefing (28/3/2011)<br />1. Current Situation<br />An earthquake of magnitude 6.5 occurred at 22:23 UTC on 27 March near the east coast of Honshu. NISA has confirmed that there have been no abnormal radiation readings at the Onagawa nuclear power plant, the closest to the epicentre, whose three units remain in cold shutdown since the earthquake of 11 March. As of 02:30 UTC today, there were no reports of any problems at nuclear plants in Japan related to the latest seismic event. <br />Overall at the Fukushima Daiichi plant, the situation is still very serious.<br />NISA informed the IEC that a meeting is planned with TEPCO to determine the origin and path of water in the turbine buildings of Units 1 to 4. As seen with the contaminated workers, high dose rates in the turbine buildings and contaminated water in the basements can hamper recovery efforts. <br />The pumping of contaminated water from the basement floor of Unit 1’s turbine building into its main condenser is in progress, whereas at Unit 2 that process has not begun because the steam condenser is full. At Unit 3, the pumping of contaminated water and in particular where it is going, are under consideration. The issue is also being examined for Unit 4. <br />Temperatures measured at the feed water nozzle and at the bottom of the Reactor Pressure Vessel (RPV) continue to decrease slightly at Units 1 and 2, except the temperature at the feed water nozzle of Unit 1’s RPV, which has slightly increased to 274 °C. <br />A positive development is that the pumping of fresh water into the reactor pressure vessel of Unit 1 is to switch from the use of fire trucks to temporary electrical pumps running on offsite power on 29 March. At Unit 2, this switch was carried out on 27 March, with a diesel generator as backup in case offsite power is interrupted. Fresh water is also being injected continuously into the reactor pressure vessel of Unit 3, albeit currently pumped by fire trucks. The switch to temporary electrical pumps for this unit is planned for today. <br />On 27 March at Unit 3, water was sprayed into the spent fuel pool using a concrete pump truck, and seawater was also pumped in through the spent fuel cooling system. It is planned to start pumping fresh water into the spent fuel pool tomorrow.<br />It is also planned to commence pumping freshwater into the spent fuel pool of Unit 4 from tomorrow. <br />Units 5 and 6 remain in cold shutdown.<br />At noon today in Japan, the three workers mentioned in previous briefings were released from the National Institute of Radiological Sciences where they had been kept under observation. The result of analyses performed indicates that the level of localised exposure received by two of them is between 2,000 and 3,000 millisievert (i.e. somewhat lower than the previous estimate of 2,000 to 6,000 millisievert). <br />2. Radiation Monitoring<br />On 27 March, deposition of iodine-131 was detected in 9 prefectures, and deposition of cesium-137 in 4 prefectures. The highest values were observed in the prefecture of Tochigi with 320 becquerel per square metre for iodine-131 and 73 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, on 27 March, the range was from 6.4 to 110 becquerel per square metre. For caesium-137, the range was from 16 to 61 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 100 becquerel per square metre, while for caesium-137 it was 36 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday. <br />Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. One team made gamma dose-rate measurements in the Tokyo and Chiba region at 3 locations. Gamma-dose rates measured ranged from 0.08 to 0.13 microsievert per hour, which is within or slightly above the background. The second team made additional measurements at distances of 30 to 46 km from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 3 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.02 to 0.3 Megabecquerel per square metre.<br />New results from the marine monitoring stations 30 km off-shore were received for seawater samples taken on 26 March. The levels decreased at most of the locations. For iodine-131 the concentration results for four monitoring stations are between 6 to 18 becquerel per litre, and for caesium-137 between “below limit of detection” and 16 becquerel per litre. The dose rates measured on the sea surface remain relatively low between 0.04 and 0.1 microsievert per hour. <br />Samples collected on 26 March 330 metres east of the discharge point showed increasing concentrations. There were found to be 74,000 becquerel per litre for iodine-131, 12,000 becquerel per litre for caesium-137, and 12,000 becquerel per litre for caesium-134.<br />It is still too early to draw conclusions for expected concentrations in marine food, because the situation can change rapidly. Modelling results show an initial north-eastern transport of liquid releases from the damaged reactors. <br />Monitoring of iodine-131 and cesium-137 in drinking water is on-going. Iodine-131 has been monitored by the Japanese authorities in 2 of 10 samples taken in the Fukushima prefecture with values of 60 and 90 becquerel per litre. In the Ibaraki prefectures, iodine-131 was detected in 2 of 9 samples, the values were 40 and 90 becquerel per litre. The Japanese limits for the ingestion of drinking water by infants is 100 becquerel per litre. <br />As far as food contamination is concerned, samples reported from 26 to 27 March in six prefectures (Fukushima, Gunma, Ibaraki, Niigata, Tochigi and Yamagata) reported iodine-131 in asparagus, cabbage, celery, chive, cucumber, eggplant, leek, mushrooms, parsley, tomato, spinach and other leafy vegetables, strawberries and watermelon. One sample of hana wasabi taken on 24 March in Fukushima prefecture was above the regulation values set by the Japanese authorities. Caesium-137 was also measured above the regulation value in the same sample of hana wasabi, but in the remaining five prefectures, caesium-137 was not detected or the results were below regulation values.<br />The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Fukushima on Sunday and discussed issues related to food contamination, including standards and sampling plan designs for radionuclides in food and the environment, radionuclide transfer from soil to plants, and mitigation strategies. The FAO/IAEA team also met with the local authority in Ibaraki prefecture today. They will have meetings with local government officials in Tochigi and Gunma tomorrow.<br />