Fukushima Nuclear Accident Update Log

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Fukushima Nuclear Accident Update Log Updates of 2 June 2011 Staff Report → Chronology of Updates: 2 June | 12-18 May | 4-11 May | 5 May | 3 May | 2 May | 28 April | 27 April | 26 April | 21 April | 20 April | 19 April | 18 April | 15 April | 14 April | 13 April | 12 April | 11 April | 10 April | 9 April | 8 April | 7 April | 6 April | 5 April | 4 April | 3 April | 2 April | 1 April | 31 March | 30 March | 29 March | 28 March | 27 March | 26 March | 25 March | 24 March | 23 March | 22 March | 21
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  Fukushima Nuclear Accident Update Log Updates of 2 June 2011 Staff Report → Chronology of Updates :2 June | 12-18 May | 4-11 May | 5 May | 3 May | 2 May | 28 April | 27 April | 26 April | 21 April | 20 April | 19 April | 18 April | 15 April | 14 April | 13 April | 12 April | 11 April | 10 April | 9 April | 8 April | 7 April | 6 April | 5 April | 4 April | 3 April | 2 April | 1 April | 31 March | 30 March | 29 March | 28 March | 27 March | 26 March | 25 March | 24 March | 23 March | 22 March | 21 March | 20 March | 19 March | 18 March | 17 March | 16 March | 15 March | 14 March | 13 March | 12 March | 11 March | Full Update  Update Resources    Videos:  Work of the IEC: A Briefing for Director General Amano, 14March 2011     In Focus: Fukushima Nuclear Accident     Fukushima Nuclear Accident: Information Sheet     Criteria for Use in Preparedness and Response for a Nuclear orRadiological Emergency     International Nuclear and Radiological Event Scale (INES)     IAEA Incident and Emergency Centre (IEC)     International Seismic Safety Centre (ISSC)     Response Assistance Network (RANET)     Japan Nuclear and Industrial Safety Agency (NISA)  o   Listen to this story  →  Important Note on Updates   IAEA Briefing on Fukushima Nuclear Accident (2 June 2011, 18:30 UTC) Presentations:   →  Summary of Reactor Status  →  Fukushima Radiological Monitoring and Consequences  →  Fukushima Marine Environment Monitoring  →  Watch Video On Thursday, 2 June 2011, the IAEA provided the following information on the status of nuclearsafety in Japan:Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.The IAEA receives information from various official sources in Japan through the Japanesenational competent authority, the Nuclear and Industrial Safety Agency (NISA). This UpdateBrief is based on information issued by the IAEA Incident and Emergency Centre up to 16:00UTC on 31 May 2011. 1. Fukushima Daiichi Nuclear Power Plant Status  Tables 1 - 4 track progress for Units 1 - 4 towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. The tables replace the three-colour table that was used previously. Thecharts are cross-referenced to the Tokyo Electric Power Company (TEPCO) Roadmap plan tobring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stablecooling condition and to mitigate radioactive releases.On 17 May 2011, TEPCO provided a status report against the TEPCO Roadmap showingprogress since the Roadmap was issued on 17 April 2011. While the basic policy and targetsdefined in the Roadmap remain, several changes were made to account for new informationobtained and progress made to date.On 13 May TEPCO commenced the preparatory work for the installation of a cover for thereactor building of  Unit 1 . The reactor building cover will be installed as an emergency measureto prevent the dispersion of radioactive substances until mid- to long term measures, includingradiation shielding, are implemented.TEPCO has reported that information obtained after calibration of the reactor water level gaugesof  Unit 1 shows that the actual water level in the Unit 1 reactor pressure vessel was lower thanwas indicated, showing that the fuel was completely uncovered. The results of provisionalanalysis show that fuel pellets melted and fell to the bottom of reactor pressure vessel at arelatively early stage in the accident.  TEPCO reported that most part of the fuel is considered to be submerged in the bottom of reactor pressure vessel and some part exposed. TEPCO also reported that leakage of coolingwater from the reactor pressure vessel is likely to have occurred. However, TEPCO considersthat the actual damage to the reactor pressure vessel is limited, on the basis of the temperaturesnow being measured around the reactor pressure vessel.The results of the analysis are provisional; TEPCO will continue to conduct investigations.Similar analyses will be conducted for Units 2 and 3 when radiation levels allow calibration of the instrumentation.Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibilityof hydrogen combustion inside the containment vessel.In Units 1, 2 and 3 fresh water is being continuously injected both via the feed water systemlines and the fire extinguishers lines into the reactor pressure vessel; temperatures and pressuresremain stable.To protect against potential damage as a result of future earthquakes, TEPCO started work on 9May to install a supporting structure for the floor of the spent fuel pool of  Unit 4 . TEPCO hasformulated the hypothesis that the damage to the Unit 4 building could have been caused byhydrogen generated at Unit 3 that flowed into Unit 4 .Fresh water is being injected as necessary into the spent fuel pools of  Units 1 - 4 . Water supplyfrom concrete pump trucks is being gradually replaced by the Fuel Pool Cooling and Clean-upsystem in Units 1 to 3 . However, closed loop cooling has not been yet established.Stagnant water with high levels of radioactivity in the basement of the turbine buildings of  Units1 and 3 is being transferred to the condensers, the radioactive waste treatment facility, the high-temperature incinerator building and temporary storage tanks. Stagnant water in the basement of the turbine building of  Unit 6 is being transferred to a temporary tank. Countermeasures againstthe outflow of water to the sea and to prevent and minimize the dispersion of radionuclides inwater have been put in place.Full-scale spraying of anti-scattering agent is continuing at the site with the use of bothconventional and remote controlled equipment. 2. Radiation Monitoring  The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures iscontinuing. Since 17 May, deposition of I-131 has not been observed. Low levels of Cs-137deposition were reported in a few prefectures on a few days since 18 May; the reported valuesrange of from 2.2 to 91 Bq/ m2 for Cs-137.Gamma dose rates values for all 47 prefectures are reported daily by the Ministry of Education,Culture, Sports, Science and Technology (MEXT) of Japan. On 31 May the gamma dose ratereported for Fukushima prefecture was 1.5 µSv/h. In all other prefectures, reported gamma dose  rates were below 0.1 µSv/h; with a general decreasing trend. Meanwhile, the decrease of thegamma dose rate has slowed down, since the short-lived radionuclides have decayed away.Gamma dose rates reported specifically for the monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant,showed a general decreasing trend, ranging from 0.1 µSv/h to 17 µSv/h, as reported for 31 May.On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). Theconcentrations in air reported for 29 May were about 3 Bq/m3 for I-131 and about 9 Bq/m3 forCs-137. The values observed in the previous days show daily fluctuations with an overalldecreasing tendency. Protective Actions  In April, the Government of Japan announced protective actions to reduce the external exposureto the population beyond a distance of 30 km from the Fukushima-Daiichi Nuclear Plant. NISAhas reported that the evacuation of the Planned Evacuation Zones within Iitate village andKawamata town commenced on 15 May. Confirmation of completion of the evacuation isawaited.  Food Monitoring and Food Restrictions   Food Monitoring (Reported from 19 to 31 May)  Food monitoring data were reported from 19 to 31 May by the Ministry of Health, Labour andWelfare for a total of 818 samples collected in 18 different prefectures. Most of the monitoringcontinues to be concentrated in Fukushima prefecture, where 328 out of the 818 samples (over40%) were collected.Analytical results for 766 samples (over 93%) of the 818 samples indicated that Cs-134 and Cs-137 or I-131 were either not detected or were below the regulation values set by the Japaneseauthorities. However, 52 samples were above the regulation values for radioactive caesiumand/or iodine.In Fukushima prefecture, five samples of fishery products collected on 16 and 17 May; onesample of unprocessed tea leaves collected on 17 May; three samples of shiitake mushrooms andnine samples of bamboo shoots collected on 19 May; five samples of seafood collected on 20, 21and 23 May, and; one sample of Japanese apricot, two samples of shiitake mushrooms and sevensamples of bamboo shoots collected on 26 May were above the regulation values for Cs-134/Cs-137. One sample of algae collected on 21 May was also above the regulation values for Cs-134/Cs-137 and I-131.In Chiba, Gunma, Ibaraki and Tochigi prefectures, eighteen samples of unprocessed raw tealeaves collected on 17, 19, 24 and 26 May were above the regulation values for Cs-134/Cs-137.
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