Test on to coax cesium in paddy soil up to surface

FUKUSHIMA — A government-affiliated research institute began experiments Saturday to decontaminate soil in rice fields in the village of Iitate, Fukushima Prefecture, where radiation levels are high due to the crippled Fukushima No. 1 nuclear plant crisis.

Iitate is among the areas designated for evacuation and planting rice has been banned.

The experiment by the National Agriculture and Food Research Organization, based in Tsukuba, Ibaraki Prefecture, is focusing on making cesium rise to the surface so it can be removed.

The institute conducted the test by spraying a water-mixed chemical that will harden the soil. After about a week, when the water has evaporated, the cesium is expected to appear on the rice field's surface, several centimeters thick like a white scab.

It should then be possible to scrape away the hardened cesium with farm machines, lowering the field's radiation level.

"It makes it easier to detect which places to scrape away (because the cesium can easily be seen) and the contaminated soil will not scatter around," said Tatsuya Naka, a lead researcher at NARO, which sprayed the chemical on about 10 ares Saturday.

Before conducting the experiment, NARO checked the radiation level of nearby soil and detected 65,900 becquerels per kilogram from the surface to 2.5 cm deep. The figure was 1,330 becquerels per kilogram from 2.5 cm to 5 cm below the surface and almost none 5 cm and deeper.

A separate experiment by another research institute showed that if soil 4 cm from the surface with 10,000 becquerels per kilogram of radiation is taken away, the radiation level will be reduced to about 2,600 becquerels per kilogram.

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