March 30, 2011 08:23
Traces of the radioactive element iodine-131 leaked from the Fukushima Daiichi nuclear power plant in Japan have been detected throughout Korea. The particles are expected to keep floating into Korea from Japan until after the crisis is brought under control.
But the amounts are too small to have an impact on drinking water and food. Even if exposed all year round to iodine-131, which was detected at 12 nationwide radiation detection stations, people would get a mere one-200,000th to one-30,000th of 1mSV, the annual maximum permissible dose, a spokesman for the Korea Institute of Nuclear Safety said Tuesday.
Trace levels of cesium-134 and cesium-137, which were detected only in Chuncheon, Gangwon Province, were just one-80,000th of the annual maximum permissible dose. These are infinitesimally small amounts compared to radiation levels that occur naturally in the environment.
Iodine-131 does not exist in nature but is produced only in a nuclear explosion or in fission at a nuclear reactor. The half-life is a mere eight days. Considering that the iodine-131 detected in Korea still gives off radiation, it must have come from either a nearby nuclear test site or a troubled nuclear power plant, and Fukushima fits the bill.
Cesium-134 and cesium-137 are a little different because they have a half-life of 30 years. Even if they give off radiation now, it is hard to determine whether they were produced recently or decades ago.
Analysis of recent weather data from the Chuncheon area raises the possibility that cesium produced in a nuclear test in the Gobi Desert a long time ago might have floated into Korea on the wind, the nuclear safety agency speculated.
The trace levels of radioactive elements are believed to have come along the same route as the xenon that was detected earlier in Gangwon Province. Iodine-131 leaked at the Fukushima plant drifted up to the North Pole and then turned south toward Siberia, the KINS said.
Earlier the Korea Meteorological Administration predicted that radioactive materials would float east on the westerly wind, travel around the earth, and reach Korea around early April. But seen from the North Pole, some of the materials have traveled north on the westerly wind along a much smaller circuit, the KMA added.
The dwindling amounts of xenon in the country show that changes in air currents have pushed floating radioactive materials off this route temporarily.
A nuclear reactor emits about 200 kinds of radioactive materials, but no other radioactive substances have been detected in the air in Korea yet. Some people fear toxic uranium and plutonium. There is a slim chance that they will float into Korea because they are heavy. It is however possible that they could be carried into Korean waters. The agency is now testing waters in the East Sea and marine creatures for radiation.
A total of 70 observation and detection stations across the country are tracking radiation levels. The 12 provincial stations are collecting rainwater and air samples.
Radioactive materials become stable after emitting their intrinsic energy, known as radiation. Detection stations are working to find out what substance the radioactive materials are based on the type of radiation. Each test takes a whole day. The agency will announce the outcome of the tests every day.
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