ID :
207157
Wed, 09/14/2011 - 17:57
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Shortlink :
https://oananews.org//node/207157
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Cesium in Pacific likely to flow back to Japan in 20-30 years
TOKYO, Sept. 14 Kyodo -
Radioactive cesium that was released into the ocean in the nuclear accident at the Fukushima Daiichi power plant is likely to flow back to Japan's coast in 20 to 30 years after circulating in the northern Pacific Ocean in a clockwise pattern, researchers said Wednesday.
Researchers at the government's Meteorological Research Institute and the Central Research Institute of Electric Power Industry disclosed the findings at a meeting of the Geochemical Society of Japan, an academic association, in Sapporo.
The researchers estimated that the amount of radioactive cesium-137 that was directly released into the sea came to 3,500 terabecquerels over the period from March to the end of May, while estimating that roughly 10,000 terabecquerels fell into the ocean after it was released into the air.
One terabecquerel equals 1 trillion becquerels. Cesium-137, which has a relatively long half life of about 30 years, can accumulate in the muscles once it is in the body and can cause cancer.
A total of 13,500 terabecquerels of radioactive cesium-137 is slightly more than 10 percent of that of the residual substance left in the northern Pacific after previous nuclear tests, according to the researchers.
The researchers, including chief researcher Michio Aoyama of the Japan Meteorological Agency's research institute, analyzed how the radioactive material dispersed in the sea during the latest accident, using data on radioactive materials detected after the nuclear tests.
According to the analysis, the cesium is expected to first disperse eastward into the northern Pacific from the coast of Fukushima Prefecture, northeast of Tokyo, via relatively shallow waters about 200 meters deep or less.
The cesium will then be carried southwestward from the eastern side of the International Date Line at a depth of 400 meters before some of it returns to the Japanese coast carried northward by the Japan Current from around the Philippines.
The analysis showed that some of the cesium will flow into the Indian Ocean from near the Philippines, and in another 40 years will reach the Atlantic, while some will turn westward south of the equator after reaching the eastern end of the Pacific and crossing the equator.
Tokyo Electric Power Co., the operator of the crisis-hit plant, said about 1,000 terabecquerels of radioactive cesium had leaked into the sea from cracks at the plant.
The researchers' estimate, which was calculated using the density of cesium detected in seawater, is more than triple that.
''To get a complete picture of cesium-137 released in the accident, we need highly precise measurements across the Pacific,'' Aoyama said before Wednesday's meeting.
Radioactive cesium that was released into the ocean in the nuclear accident at the Fukushima Daiichi power plant is likely to flow back to Japan's coast in 20 to 30 years after circulating in the northern Pacific Ocean in a clockwise pattern, researchers said Wednesday.
Researchers at the government's Meteorological Research Institute and the Central Research Institute of Electric Power Industry disclosed the findings at a meeting of the Geochemical Society of Japan, an academic association, in Sapporo.
The researchers estimated that the amount of radioactive cesium-137 that was directly released into the sea came to 3,500 terabecquerels over the period from March to the end of May, while estimating that roughly 10,000 terabecquerels fell into the ocean after it was released into the air.
One terabecquerel equals 1 trillion becquerels. Cesium-137, which has a relatively long half life of about 30 years, can accumulate in the muscles once it is in the body and can cause cancer.
A total of 13,500 terabecquerels of radioactive cesium-137 is slightly more than 10 percent of that of the residual substance left in the northern Pacific after previous nuclear tests, according to the researchers.
The researchers, including chief researcher Michio Aoyama of the Japan Meteorological Agency's research institute, analyzed how the radioactive material dispersed in the sea during the latest accident, using data on radioactive materials detected after the nuclear tests.
According to the analysis, the cesium is expected to first disperse eastward into the northern Pacific from the coast of Fukushima Prefecture, northeast of Tokyo, via relatively shallow waters about 200 meters deep or less.
The cesium will then be carried southwestward from the eastern side of the International Date Line at a depth of 400 meters before some of it returns to the Japanese coast carried northward by the Japan Current from around the Philippines.
The analysis showed that some of the cesium will flow into the Indian Ocean from near the Philippines, and in another 40 years will reach the Atlantic, while some will turn westward south of the equator after reaching the eastern end of the Pacific and crossing the equator.
Tokyo Electric Power Co., the operator of the crisis-hit plant, said about 1,000 terabecquerels of radioactive cesium had leaked into the sea from cracks at the plant.
The researchers' estimate, which was calculated using the density of cesium detected in seawater, is more than triple that.
''To get a complete picture of cesium-137 released in the accident, we need highly precise measurements across the Pacific,'' Aoyama said before Wednesday's meeting.
