Radiation levels in the sea near what is left of the Japanese nuclear power plant "Fukushima-1", is still high, but since the accident has been more than six months.
The highest point (100 thousand Bq / m) pollution reached in early April. It was expected that the larger part of radioactive iodine, cesium and plutonium quickly disperse to the Pacific Ocean.
However, this did not happen. Probably the reason is that the contaminated water is still flowing into the sea from the nuclear plant, and can, twist current radioactive material in one place. More likely is that both factors work together.
Ken Byusseler of Oceanographic Institution, Woods Hole (USA) said, "The New York Times," at his disposal were the July test: they were 10 thousand Bq / m. According to him, a few months before the crash concentration was only 1.5 Bq.
Simon Boksol of Southampton (United Kingdom) said that the blame for the Kuroshio — the Japanese equivalent of the Gulf Stream. Kuroshio skirts archipelago, destroying material in the deep ocean. But near the coast it creates huge swirls from 80 to 100 km in diameter, which send some stuff back to the coast.
Mr. Byusseler their results have not been published — check back. But preliminary data suggest the rightness Mr. Boksola: to sea (30-600 km offshore) radioactivity decreases.
There is nothing surprising in the fact that marine life has not dealt with radioactivity, says Mr. Boksol. Usually algae accumulate radioactive iodine-131, which decays rapidly, and cesium-134 and cesium-137 with a half-life of two and thirty years, respectively, are concentrated in shellfish and can persist for decades. "From the very beginning there was no reason to believe that radiation levels drop soon after the accident," — said the expert.
According to official estimates the Japanese government and plant operator TEPCO, from March 11 to the end of May fell into the ocean 3500 TBq of cesium-137. Pollution has increased in April due to the fact that a) is not able to immediately find the leak, b) TEPCO decided to dump contaminated water into the ocean. The following 10 thousand TBq cesium apparently were in the sea with the water condensed from the steam. Last week, TEPCO admitted that so far every day flows away from the station into the sea up to 500 tons of contaminated water. This, however, is too small to explain this slow decline radiation.
By the way, last week, the Japanese government proposed a new plan to combat pollution of the soil. Announced that in Fukushima Prefecture to destroy about 30 million m? land and vegetation. Have to "shave off" five-centimeter layer of agricultural land, forests and residential areas. A little later it was reported that in eight prefectures are constructed temporary storage facility for contaminated soil.
But there is good news. According to TEPCO, the first time since the disaster temperature of all three of the most severely damaged reactor units fell below 100 ° C. This is an important milestone on the way to a cold shutdown, which would effectively preserve the station for good. The last reactor temperature which went into decline was the second block. He was the main source of radioactive water in April.