Akhir 1432 / 14 March 2011, SPA -- Plant operators were struggling to prevent a meltdown at Japan's Fukushima 1 nuclear power station on Monday, after a massive earthquake and ensuing tsunami disabled its emergency cooling systems, according to dpa. The plant's fuel rods were fully exposed for more than two hours late Monday, the second time this happened in a day, the Kyodo news agency reported. The news increased fears that temperatures in the core could rise to a level where the rods would melt their way through the core's steel walls. Operators from the Tokyo Electric Power Company (TEPCO) were pumping water into the plant's damaged reactor. But officials said a steam vent of the reactor's pressure container shut down, possibly due to battery problems, leading to a sudden drop in water levels. Radiation around the plant reached 3,130 microsievert per hour, double the highest level registered so far. Japan allows an hourly exposure of 500 microsievert, which is a measure of the biological effects of radiation. However, the International Atomic Energy Agency (IAEA) in Vienna played down fears of a Chernobyl-style disaster - the worst in nuclear history. The old Soviet plant in what is now Ukraine suffered a meltdown in 1986, spreading radioactive material across Europe. "The possibility that the development of this accident (turns) into the one like in the Chernobyl accident is very unlikely," IAEA director general Yukiya Amano told reporters. "This is not an accident because of human errors or design," Amano, who is from Japan, added. "This is because of a huge natural catastrophe which was beyond the imagination and experience of people." Amano also confirmed that Japan had asked the IAEA for help, but said the details of the mission were still being discussed. Japan's NHK television network had earlier reported that the water being pumped into the plant's damaged number 2 reactor was unable to fully submerge the four-metre long rods, which contain the uranium fuel used to create fission. While the risk of an explosion was "very low," officials acknowledged that the rods may have been damaged and that some radioactive material had been detected nearby. Operators "are doing the very best to try to submerge the fuel rods," Masahi Goto of the Citizens' Nuclear Information Center in Tokyo had said at a news conference earlier. "The problem is the cooling system, as it was damaged by the tsunami," said Goto, a specialist in nuclear containment vessels for Toshiba Corp. "If the fuel rods remain exposed for a long time under the very fragile cooling system, that would lead to a meltdown," he noted. The containment vessel, which encases the core, should protect the environment from the radiation of a meltdown. But there were concerns that the quake may have damaged the structural integrity of the vessel at Fukushima, which is located 240 kilometres north of the capital Tokyo, in north-east Japan. Two of its six reactors have exploded since the magnitude-9 earthquake devastated Japan on Friday. Hydrogen explosions occurred in reactor number 1 on Saturday and reactor number 3 on Monday, minutes after a magnitude-6.2 aftershock hit the region. The second explosion injured 11 people, including soldiers, TEPCO said. About 200,000 people have been evacuated from a 20-kilometre radius around the plant. The government ordered those remaining to stay indoors with the windows and doors closed. The wind in Fukushima blew in an easterly direction during much of the day, so any radioactivity would have been swept toward the Pacific and not into Japan's interior. But the governor of Tokyo, Shintaro Ishihara, said he expected radioactivity to eventually be measured in the capital. Singapore has already started to test food imported from Japan for radiation. The Japanese nuclear crisis has also prompted a number of European countries to reconsider their use of nuclear energy. In Germany, Chancellor Angela Merkel said her country was postponing by three months plans to extend the lifespans of its 17 nuclear reactors in order to run safety tests. European Union energy ministers are also set to discuss nuclear safety at a meeting in Brussels on Tuesday.
