FUKUSHIMA--A preliminary test detected 500 becquerels of radioactive cesium per kilogram of rice in Fukushima Prefecture, the first time the limit of 200 becquerels has been breached, the prefectural government said Sept. 23.
FUKUSHIMA--A preliminary test detected 500 becquerels of radioactive cesium per kilogram of rice in Fukushima Prefecture, the first time the limit of 200 becquerels has been breached, the prefectural government said Sept. 23.
The pre-harvest rice samples were from the former Obama town area of Nihonmatsu city.
The finding means that rice from Nihonmatsu will undergo more intensive studies during the main, post-harvest screening phase, with the number of sample locations multiplied from 38 to about 300.
Rice shipments from the area will be banned if the main inspection turns up a concentration of more than 500 becquerels per kilogram.
According to the prefectural government, the high cesium concentration was detected in brown rice of the Hitomebore brand sampled on Sept. 12.
Because the paddy contained 3,000 becquerels of cesium per kilogram of soil, the prefectural government suspected that soil may have mixed into the rice sample. But a reanalysis turned up about the same value.
"We have no idea why so high a concentration was detected," said Kazuhiko Kanno, head of the prefectural government's rice paddies and farmland section.
Brown rice samples from nearby paddies were found to contain up to 212 becquerels of radioactive cesium per kilogram.
In light of the disaster at the Fukushima No. 1 nuclear power plant, regular harvests of rice must undergo two screening phases for radioactive substances: a preliminary, pre-harvest inspection to check general trends in contamination, and a main, post-harvest inspection to decide whether the rice may be shipped.
In Fukushima Prefecture, the number of sample locations is increased to about two per 15 hectares if the preliminary inspection turns up a radiation concentration level exceeding 200 becquerels per kilogram.
Inspections of early harvests of rice that started in late August in Fukushima Prefecture have already been completed. No sample of the harvested rice has been found to exceed the central government's safety threshold.
Screening of regular harvests of rice began in early September. Both preliminary and main inspections have been completed in 13 of the 48 municipalities where rice was planted, and shipments have been authorized for all of them.
The maximum concentration found in those inspections so far had been 136 becquerels per kilogram in the former Oguni village area of Fukushima city.