Countermeasures to reduce radiocesium in brown rice

Abstract

Four countermeasures have been adopted to reduce the contamination of brown rice by radiocesium released from the Tokyo Electric Power Company Holdings’ Fukushima Daiichi Nuclear Power Plant: 1) prohibition of rice cultivation and harvesting, 2) decontamination of farmland, 3) application of potassium and 4) inspection of brown rice. Since 2011, rice cultivation and harvesting has been prohibited in the evacuation-designated zones. In 2012, rice cultivation and harvesting was banned in areas where radiocesium-contaminated brown rice exceeded the present limit on radiation level of 100 Bq/kg. Decontamination of farmland has been conducted since 2012 by removal of topsoil in most cases. Additional potassium application has been recommended to raise soil exchangeable potassium content to 25 mg/100 g before conventional NPK fertilization. Since 2012, every 30-kg bag of brown rice produced in Fukushima Prefecture has been inspected to prevent shipment of any brown rice containing radiocesium exceeding the standard value from shipping. From 2020, sampling inspection is conducted except the evacuation ordered area.