Fukushima One Year On: World Nuclear Association. A major earthquake on 11 March 2011 caused a 15-metre tsunami to strike the Fukushima Daiichi nuclear power plant on Japan's Tohoku coast, disabling the power supply and heat sinks, thereby triggering a nuclear accident. The reactors involved were boiling water units of a 1960s design owned and operated by Tokyo Electric Power Company and supplied by GE, Toshiba and Hitachi.
Reactors 1-4 came into commercial operation 1971-78. Without cooling water, the cores of units 1, 2 and 3 overheated and largely melted in the first three days. Hydrogen generated by this high-temperature process caused explosions in the upper service floors of reactor buildings at units 1 and 3. Unit 4 had not been operating, but was affected by a hydrogen explosion due to gas back-flow from unit 3. The major accident was rated at Level 7 on the International Nuclear Event Scale due to high radioactive releases to air in the first few days. Effects on people Effects on the sea, fishing and food Current situation. Higher estimate of Fukushima releases.
The latest analysis has upped the figures for the amount of radioactivity released during the accident at Fukushima Daiichi, although the estimate for the main long-term contaminant, caesium-137, was actually reduced. In previous official estimates from Japanese government agencies only broad figures were given for gross releases of iodine-131 and caesium-137. Now Tepco has compiled a more detailed estimate based on data from radiation monitoring cars and validated by government measurements of materials deposited on the ground.
The figures are divided between air and sea and raise the overall scale of the iodine-131 release by a factor of three, while marginally reducing the scale of caesium-137 release. The potential health risk posed by the Fukushima accident was that released iodine-131 could accumulate in the thyroid glands of growing children and lead to cancer cases. The first estimates made shortly after the accident put releases of iodine-131 at 130 PBq. Preliminary Dose Estimation from the nuclear accident after the 2011 Great East Japan Earthquake and Tsunami. Fukushima Nuke News.
IAEA Alert Log. IAEA - INES (Events Scale) IRSN (french) Toutes les actualités Estimation des coûts d’accidents nucléaires en France : Méthodologie appliquée par l’IRSN En février 2013, l'IRSN publiait les premiers résultats de ses investigations relatives au coût d’un accident nucléaire. L’Institut publie aujourd’hui un rapport méthodologique sur ce sujet. Alors que l’attention s’est focalisée l'an dernier sur le chiffrage total des conséquences d’un accident dans notre pays, l’importance de ce nouveau rapport réside surtout dans l’approche analytique qu’il propose pour les différentes composantes de ce coût. Lire la suite Prix ETSON 2014 : Appel à papier pour concourir Pour favoriser la coopération entre ses jeunes experts, le réseau européen des organismes techniques de sûreté ETSON – dont l’IRSN est membre fondateur – récompense chaque année un papier rédigé par un groupe de jeunes experts travaillant pour les organismes techniques de sûreté (TSOs).
Lire la suite Le projet ANR Perfroi est lancé Lire la suite Lancement du projet ANR Denopi. French nuclear agency rates Japan accident 5 or 6. (c) Copyright Thomson Reuters 2011. Click For Restrictions. PARIS, March 14 (Reuters) - France&${esc.hash}39;s ASN nuclear safety authority said on Monday the nuclear accident in Japan could be classed as level 5 or 6 on the international scale of 1 to 7, on a par with the 1979 U.S. Three Mile Island meltdown. The severity estimate, based on ASN&${esc.hash}39;s assessment of data provided by Japan, is above the rating of 4 that Japan&${esc.hash}39;s nuclear safety agency has given the accident at Tokyo Electric Power Co&${esc.hash}39;s <9501.T> Fukushima Daiichi nuclear power plant.
"Level four is a serious level," ASN President Andre-Claude Lacoste told a news conference, but added: "We feel that we are at least at level five or even at level six. " The other three reactors at the plant were not in operation at the time of the quake due to scheduled maintenance. "We are at the beginning of a crisis that could last for weeks," Lacoste said. French claim full scale of nuclear disaster being hidden.
Plans are being drawn up to evacuate every British national in Japan amid mounting fears of a nuclear catastrophe. Thousands of Britons were last night warned to leave Tokyo and all other areas under threat of radiation poisoning. The Foreign Office is even chartering additional planes to ensure that all British citizens can leave the country on free-of-charge rescue flights - as thousands of terrified passengers cram into Tokyo airport attempting to flee. It comes as the Japanese authorities resorted to dumping water on over-heating reactors at the Fukushima nuclear plant from helicopters in a desperate last-ditch attempt to stop a catastrophic meltdown. Experts have warned that they have 48 hours to avoid another Chernobyl. [caption The Foreign Office says Britons should still try to get commercial flights out of Japan if possible.
There will be no charge for British nationals and their immediate families who were 'directly affected' by the tsunami. Enlarge By DANIEL BATES In 1972, the U.S. French Radioactivity Measures. IAEA Response System. World Nuclear Association | Information and Issue Briefs | Radiation and the Nuclear Fuel Cycle. March 2004 Printer friendly version is also available Natural sources account for most of the radiation we all receive each year. Up to a quarter of that received is due to human activity and originates mainly from medical procedures.
The nuclear fuel cycle does not give rise to significant radiation exposure for members of the public. Radiation protection standards assume that any dose of radiation, no matter how small, involves a possible risk to human health. This deliberately conservative assumption is increasingly being questioned. Radiation can arise from human activities or from natural sources. Radiation arising from human activities typically accounts for up to 25% of the public's exposure every year. Less than 1% of exposure is due to the fallout from past testing of nuclear weapons or the generation of electricity in nuclear, as well as coal and geothermal power plants. Our knowledge of radiation effects derives primarily from groups of people who have received high doses. Boiling water reactor. The boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR), also a type of light water nuclear reactor.
The main difference between a BWR and PWR is that in a BWR, the reactor core heats water, which turns to steam and then drives a steam turbine. In a PWR, the reactor core heats water, which does not boil. This hot water then exchanges heat with a lower pressure water system, which turns to steam and drives the turbine. The BWR was developed by the Idaho National Laboratory and General Electric in the mid-1950s. The main present manufacturer is GE Hitachi Nuclear Energy, which specializes in the design and construction of this type of reactor. Overview[edit] BWR schematic. Description of major components and systems[edit] Condensate and feedwater[edit] Control systems[edit] Steam turbines[edit] Size[edit]