power – strom und macht


Susanne Gerber


TOKYO (Kyodo) — An excessive level of radioactive cesium has been found in the meat of one of 11 cows taken to a meat packing plant in Tokyo from Minamisoma, Fukushima Prefecture, the Tokyo metropolitan government said Friday.

It is the first time an excessive level of radioactive cesium has been found in meat, according to the health ministry. The meat in question contained radioactive cesium, measuring 2,300 becquerels per kilogram, against the provisional ceiling of 500 becquerels, according to the local government.

The meat of the 10 other cows is being inspected, the metropolitan government said, adding that no meat from the batch has entered the market.

The city of Minamisoma lies on the outskirts of the Fukushima Daiichi nuclear power plant in the same prefecture, which has emitted radioactive materials in the aftermath of the disaster caused by the March earthquake and tsunami.


Radioactive cesium-137 was found in Tokyo’s tap water for the first time since April as Japan grapples with the worst nuclear disaster in 25 years. Products including spinach, mushrooms, bamboo shoots, tea, milk, plums and fish have been found to be contaminated with cesium and iodine as far as 360 kilometers (224 miles) from the station. Prolonged exposure to radiation in the air, ground and food can cause leukemia and other cancers, according to the London-based World Nuclear Association.

The Nuclear Safety Commission of Japan sets a safety limit of 200 becquerel per kilogram for cesium-134 and cesium-137. The limit for iodine-131 consumption is 300 becquerel per kilogram.For vegetables, Japan has a limit at 2,000 becquerel of iodine per kilogram and 500 becquerel of cesium a kilogram.

Cesium-137 has a half-life of about 30 years, compared with two years for cesium-134, according to the National Institute of Standards and Technology. Iodine-131 takes eight days for half of the substance to decay.


Caesium, is one of the radioactive fission products created within a nuclear reactor during its operation. Caesium-137 is one of the major radioactive isotopes of caesium. It is a major radioisotope, a gamma emitting isotope in the radioactive waste resulting from nuclear reactors. Caesium-137 is radioactive for a long period of time (half-life is about 30 years) and can contaminate property, entailing extensive cleanup. It can also be absorbed into the food chain.


The announcement by Japan’s Agency for Natural Resources and Energy that high levels of radioactive cesium have been detected in seawater near the crippled nuclear reactors raises the prospect that radiation could enter the food chain. Cesium 137 levels were 20 times the normal level about 1,000 feet from the effluent at the Fukushima Daiichi nuclear power plant. That is far less than the level of the other main radioactive isotope spilling from the plant, iodine 131. It was found in concentrations of more than 1,150 times the maximum allowable for a seawater sample a mile north of the plan. Still, scientists say, cesium 137 poses the greater long-term danger to the marine food chain.

Cesium 137 has a half-life of 30 years. Worse still, it is absorbed by marine plants, which are eaten by fish and — like mercury — tends to become concentrated as it moves up the food chain. “It’s worrisome in that CS 137 is leaking, although the levels are still low,” said Paul G. Falkowski, a professor at Rutgers University’s Institute of Marine and Coastal Sciences. “At some point this water that is pooling in various places is ultimately going to make its way out to the sea.” And if there is a lot of cesium 137 over an extended period “then you’ll have to worry.” The exact source of the cesium 137 is unclear, although some scientists have speculated that the seawater dumped on the overheating reactors to cool them picked up radiation and then washed back out to sea. But Japanese officials said highly radioactive water in several tunnels is threatening to overflow and may also contain cesium 137.


 It was found 1.13 becquerels of caesium-134 per litre of urine in an eight-year-old girl – the highest reading for that isotope. The highest reading for caesium-137 (1.30 becquerels) was in a seven-year-old boy, Kyodo news agency said. Richard Wakeford, an expert in radiation exposure at the Dalton Institute in Manchester, England, said he was not surprised caesium had been found in Fukushima city residents, given the distance and direction the radiation plume had travelled. “What we’re seeing here is residual caesium that will be around for quite a while,“ he said. The discovery came days after health authorities in Fukushima began checking internal radiation doses among all 2 million of the prefecture’s residents, a 30-year project that will cost an estimated ¥100 billion ($1.1 billion). In separate tests, radioactive caesium and iodine were found in the urine of 15 residents from two towns between 30 and 40 kilometres from the Fukushima Daiichi plant. While none had exceeded the maximum allowable dose of 20 millisieverts a year, experts voiced concern over the presence of caesium-137, a byproduct of nuclear fission with a half-life of 30 years.

Filed under: Danger, Fukushima, Radiation

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