Continuing complications at the Fukushima Daiichi nuclear plant in Japan have escalated the fear of widespread radiation contamination. Yesterday, another fire was discovered at the plant following the hydrogen explosion that occurred on Tuesday at the plant’s No. 2 reactor and similar explosions at the No. 1 and No. 3 reactors. “There is still a very high risk of further radioactive material coming out,” warned Prime Minister Naoto Kan in an address to the Japanese people. For now, about 200,000 people living within a 12.4-mile radius of the plant have been evacuated and flights over the area have been banned.
Early Tuesday morning, a blast at the Fukushima Dai-ichi Nuclear Power Station damaged the vessel containing the nuclear reactor core and sent large amounts of radioactive material into the air. A fire in the plant also broke out. The explosion was the third at the plant since Friday’s earthquake and tsunami. The situation at Fukushima is the worst nuclear disaster since Chernobyl. According to The International Atomic Energy Agency, at one point, radiation was leaking into the air at a rate of 400 milliseverts per hour. Anyone exposed to over 100 millisieverts a year risks cancer.
Spent fuel rods have also been a concern at Fukushima. On the top of reactor buildings, there are cooling pools that hold used rods and keep the material from entering the environment. But because workers have not been able to restore the cooling systems, the pools are rapidly heating up. Earlier in the week, the water in the pool on reactor No. 4 was boiling. If the water evaporates and the rod becomes dry, it could catch fire and create massive clouds of radioactive material.
Some experts consider the pools to be a greater threat than a meltdown of the reactor cores because they are not as well protected. Reactors have strong containment vessels that can withstand smaller explosions, but the previous explosions at the plant caused two of the pools to be exposed to the environment.
But experts say that there is still time to mitigate the situation. Thomas B. Cochran, a senior scientist in the nuclear program at the National Resource Defense Council, told the New York Times earlier in the week that there was still time for fire hoses to fill the pools or helicopters to drop tons of water. Still the situation is precarious. The threat posed by exposed and heated fuel pools is so severe that immediately after the earthquake, plant officials focused on repairing and maintaining the cooling pools.
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