Traces of radioactive iodine detected in rain

Traces of radioactive iodine-131 have been found in rainwater in Seoul and another city following radiation leaks from a troubled nuclear power plant in Japan, the local nuclear regulator said Wednesday.

The Korea Institute of Nuclear Safety (KINS) said detailed analysis of rain that fell on Monday and Tuesday showed maximum iodine concentration levels of 2.48 becquerel (Bq) per liter of rainwater in Seoul and 0.308 Bq in Chuncheon, located 85 kilometers east of the capital city.

The readings are higher than those picked up in the atmosphere, which is the result of rain picking up more particles as it falls to the ground, it said.

The institute also said it detected minuscule traces of iodine radionuclides in three regions of the country on Tuesday out of 12 checked sites.

It said atmosphere concentration levels for Seoul stood at 0.079 millibecquerel (mBq) per square meter with numbers for Chuncheon standing at 0.071 mBq. Gangneung, located on the eastern coast, reported iodine levels of 0.138 mBq on the cited day.

No traces of cesium were detected in the atmosphere, and no iodine was detected in nine other locations that reported trace levels on Monday.

"The concentration of iodine in the air and rain are almost negligible and pose no real risks to public health or the environment," KINS said.

In Japan, permissible levels of iodine in tap water are set at 100 Bq per liter for babies and 300 Bq for adults.

The nuclear safety agency added that despite some concerns, there is very little chance of plutonium released from the Japanese nuclear station reaching Korea.

KINS president Yun Choul-ho pointed out that the radioactive chemical element is 2.5 times heavier than steel, has a very high vaporization temperature of 3,300 Cs, and does not dissolve in water.

"Because there is no reason to believe that plutonium has been transformed into nano particles that can float, there is almost no risk of it spreading beyond the immediate vicinity of the nuclear power plant," he said.

The expert, however, said that KINS and the Korea Atomic Energy Research Institute have the ability to conduct tests if the need arises.

The latest announcement on radiation levels, meanwhile, came after Seoul confirmed trace levels of xenon-133 in the atmosphere on Sunday and iodine-131, cesium-134 and cesium-137 late Monday.

Xenon and other radioactive isotopes are not found in nature and are only produced by a nuclear fission reaction.

South Korea has stepped up monitoring of radiation levels around the country after a series of explosions took place at the Fukushima nuclear power station 250 kilometers northeast of Japan.

The explosions that began on March 12 destroyed the containment shields of several reactors at the plant and allowed radioactive materials to be released into the surrounding areas and into the atmosphere. (Yonhap)