At the center of Fukushima Dai-Ichi, 250 km from Tokyo, the six reactors were initially seemed almost impervious to strong ground shaking. Friday, March 11 to 14 h 46, when the ground shook, the three units in operation were immediately arrested under the emergency procedure. But the sequence of events has come to defy the worst scenarios of Engineers: generators, which were to take over power lines, cut, were drowned by the tsunami that followed the earthquake.
Private power, cooling systems have ceased to function, whereas in the heart of the reactor reactions releasing large amounts of heat are still occurring. In the control room of reactor No. 1, the level of radioactivity reached 1000 times the normal. Japanese Prime Minister, Naoto Kan, flying over the area by helicopter, ordered the evacuation of a 10 km radius around Fukushima Dai-Ichi, shortly after extended to 20 km.
Nearly 200,000 people are affected. Despite the efforts, an explosion blows the top of reactor No. 1 Saturday at 15 am 36 or just over 24 hours after the earthquake. The hydrogen present in the steam released reacted on contact with oxygen, which shattered the building's roof. The pictures are spectacular, but the authorities are reassuring: the containment, a wall of reinforced concrete one meter thick, remained intact.
But everyone is aware of the seriousness of the accident, which is then classified level 4 on the scale of nuclear and radiological events, which has seven at this stage, 22 people have been irradiated up to 190 others might have been exposed to radiation. Meanwhile, in the other two reactors stopped when the earthquake struck, the number two and number three, where the cooling functions are inoperative, a similar scenario is at work.
While the water level in reactor No. 2 is of concern, the authorities implement the reactor No. 3 the same emergency maneuvers, releasing the gas. The sea water injected into the three reactors, seems insufficient to control the process. At this stage, the reactor cores are likely to have begun to melt, threatening the integrity of the tanks containing fuels and increasing the risk of chain reactions.
Monday morning, another explosion, this time double, shakes the site. The roof of reactor No. 3 is blown. As the No. 1 reactor, containment seems to have remained intact. Integrity as the International Atomic Energy Agency will question the next day. If the Japanese authorities and international scenario as a hammer-type Chernobyl disaster is averted, for the French Nuclear Safety Authority (ASN) the nuclear accident in Fukushima reached a level of gravity beyond the Three Mile Island "The most serious nuclear accident before Chernobyl, the United States in 1979.
On site, operators are busy again to avoid the worst. In vain: Tuesday morning, an explosion inside the reactor building No. 2 to 6 h 10 leads to an alteration of the containment, which loses its seal. The analysis of the situation by the Institute for Radiological Protection and Nuclear Safety (IRSN) said the seriousness of the situation: "Given the deterioration of the containment of reactor No.
2, IRSN considers that releases on this reactor are now unfiltered and may be permanent, "said the French agency. For DSC, the nuclear accident has reached a level of severity 6. Ultimate wake-up call: the reactor 4, which was believed safe, as already stopped when the earthquake struck, has in turn an explosion in its walls, which affects a retention basin spent fuel, not protected by concrete enclosure that surrounds the heart reactor.
In the control room, the measurements of radioactivity reached a level such that employees can not stay there permanently, and must carry back and forth, trying to monitor the situation from other places. A slight rise in temperature was also measured in Units 5 and 6. While the security zone is extended to a radius of 30 km, those at the periphery of the area are caulked recommendation to stay home to avoid exposure.
According to experts, the safety of employees Fukushima Dai-Ichi working to contain the accident is under threat. "Contrary to what has happened so far, there is no doubt that the levels can affect human health," said government spokesman Yukio Edano, however, that ensures that only the site around the plant has dangerous levels of radioactivity.
In the country, fears of widespread food contamination are increasing: in Tokyo, the level of radioactivity reached ten times the normal mid-day, before falling in the afternoon. Probably as a result of radioactive releases from the explosion at reactor No. 2, driven by wind. Marion Solletty 
Private power, cooling systems have ceased to function, whereas in the heart of the reactor reactions releasing large amounts of heat are still occurring. In the control room of reactor No. 1, the level of radioactivity reached 1000 times the normal. Japanese Prime Minister, Naoto Kan, flying over the area by helicopter, ordered the evacuation of a 10 km radius around Fukushima Dai-Ichi, shortly after extended to 20 km.
Nearly 200,000 people are affected. Despite the efforts, an explosion blows the top of reactor No. 1 Saturday at 15 am 36 or just over 24 hours after the earthquake. The hydrogen present in the steam released reacted on contact with oxygen, which shattered the building's roof. The pictures are spectacular, but the authorities are reassuring: the containment, a wall of reinforced concrete one meter thick, remained intact.
But everyone is aware of the seriousness of the accident, which is then classified level 4 on the scale of nuclear and radiological events, which has seven at this stage, 22 people have been irradiated up to 190 others might have been exposed to radiation. Meanwhile, in the other two reactors stopped when the earthquake struck, the number two and number three, where the cooling functions are inoperative, a similar scenario is at work.
While the water level in reactor No. 2 is of concern, the authorities implement the reactor No. 3 the same emergency maneuvers, releasing the gas. The sea water injected into the three reactors, seems insufficient to control the process. At this stage, the reactor cores are likely to have begun to melt, threatening the integrity of the tanks containing fuels and increasing the risk of chain reactions.
Monday morning, another explosion, this time double, shakes the site. The roof of reactor No. 3 is blown. As the No. 1 reactor, containment seems to have remained intact. Integrity as the International Atomic Energy Agency will question the next day. If the Japanese authorities and international scenario as a hammer-type Chernobyl disaster is averted, for the French Nuclear Safety Authority (ASN) the nuclear accident in Fukushima reached a level of gravity beyond the Three Mile Island "The most serious nuclear accident before Chernobyl, the United States in 1979.
On site, operators are busy again to avoid the worst. In vain: Tuesday morning, an explosion inside the reactor building No. 2 to 6 h 10 leads to an alteration of the containment, which loses its seal. The analysis of the situation by the Institute for Radiological Protection and Nuclear Safety (IRSN) said the seriousness of the situation: "Given the deterioration of the containment of reactor No.
2, IRSN considers that releases on this reactor are now unfiltered and may be permanent, "said the French agency. For DSC, the nuclear accident has reached a level of severity 6. Ultimate wake-up call: the reactor 4, which was believed safe, as already stopped when the earthquake struck, has in turn an explosion in its walls, which affects a retention basin spent fuel, not protected by concrete enclosure that surrounds the heart reactor.
In the control room, the measurements of radioactivity reached a level such that employees can not stay there permanently, and must carry back and forth, trying to monitor the situation from other places. A slight rise in temperature was also measured in Units 5 and 6. While the security zone is extended to a radius of 30 km, those at the periphery of the area are caulked recommendation to stay home to avoid exposure.
According to experts, the safety of employees Fukushima Dai-Ichi working to contain the accident is under threat. "Contrary to what has happened so far, there is no doubt that the levels can affect human health," said government spokesman Yukio Edano, however, that ensures that only the site around the plant has dangerous levels of radioactivity.
In the country, fears of widespread food contamination are increasing: in Tokyo, the level of radioactivity reached ten times the normal mid-day, before falling in the afternoon. Probably as a result of radioactive releases from the explosion at reactor No. 2, driven by wind. Marion Solletty
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