The Korea Institute of Nuclear Safety said it found no radioactive iodine or cesium in the air at 12 monitoring stations nationwide over the weekend.

The institute said on Monday that it also could not find any radioactive substances in rainwater collected on Saturday and Sunday from nine regions including Seoul and Chuncheon.

The institute said that since April 26th, it has detected little radioactive substances in the air and rainwater around the nation. It added that on Thursday it collected and inspected tap water supplied by 23 water treatment plants, but no radiation was detected.

The levels of the radioactive material xenon, which is being measured only in Gangwon Province, are also decreasing steadily.