The Tokyo Electric Power Co. reported on April 18 that radioactive substances of high concentration were detected in flooding waters at the spent nuclear fuel pool of No. 2 reactor of the plant.

According to the test results, cesium-134 and -137 were confirmed to be 160,000Bq and 150,000Bq each per 1cc of contaminated water and iodine-131 to be 4,100Bq.

This is believed to originate from the reactor core where fuel rods have been partially melted, TEPCO said.

On the same day, the Ministry of Economy, Trade and Industry of Japan said, citing the data measured at the buildings of Nos. 1 and 3 reactors on Sunday, that the radiation level was 49mSv and 57mSv respectively per hour.

It is said that if people stay in the 57-millisievert-environment for hour and a half hours, they would be exposed to more than the permissible level of 250 millisieverts.

Amid the crisis growing at the Fukushima Daiichi Nuclear Power Plant, south Korea's KBS reported on Monday that trace amounts of radioactive substances were still detected at 12 monitoring stations in the southern area of the Korean Peninsula.

In the meantime, the toll of the quake and tsunami is increasing in Japan.

The number of deaths has increased to 13,895 and the missing to 13 864 as of 18:00 on Monday, according to the National Police Agency of Japan.

Asahi Shimbun Tuesday reported, citing the survey data by Japan's National Land and Geography Agency that the areas flooded by tsunami extend 561 square kilometers in total, covering 62 cities, chos and muras in six prefectures in the Pacific coastal region from Aomori Prefecture to Chiba Prefecture.

According to it, Miyagi Prefecture, most seriously hit by tsunami, accounts for more than half of the inundated areas, or 327 square kilometers.

At present lands in the northeastern coastal region of Japan whose ground went down are getting submerged in water.