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Japan is going to triple the number of regions it checks for airborne radiation as officials are beginning to uncover more contaminated “hot spots” far from the devastated nuclear power plant, Tokyo Electric Power Co. (TEPCO) officials said.

The government said it will increase radiation monitoring by helicopter to 22 prefectures from the six closest to the plant, which began spewing radiation after an earthquake and tsunami struck the station in March. The plan comes after radioactive waste more than double the regulatory limit was 200 kilometers (125 miles) from the plant this week.

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Authorities have refused to give a cumulative figure for radiation released from the Fukushima Dai-ichi nuclear plant after estimating in June that fallout in the six days following the quake was equal to 15 percent of total radiation released in the Chernobyl nuclear disaster in 1986.

Officials on Aug. 12 found compost in a kindergarten yard in Tokamachi city, Niigata prefecture containing radioactive cesium measuring 27,000 becquerels per kilogram, said Kenichiro Kasuga, an official at the city’s disaster prevention department.

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Under Japanese law, waste measuring over 8,000 becquerels per kilogram is radioactive and no one can bury it in a landfill.

City officials found sludge measuring 18,900 becquerels per kilogram from radioactive cesium on the same day as part of tests done at 60 educational and childcare facilities, Kasuga said. The city government is storing the waste in drums until the government sets final guidelines for its disposal, he said.

The hotspots in Niigata likely came from wind blowing northwest toward the prefecture in the days following the Fukushima accident, officials said.

The government will begin monitoring radiation levels in 16 prefectures from Aomori, in the far north of the main island of Honshu, to Aichi in central Japan 460 kilometers (290 miles) from the plant by the end of October, the Ministry of Education, Culture, Sports, Science and Technology said in a statement on its website.

Radiation monitoring has taken place in four other prefectures and in Gunma and the western part of Fukushima prefecture, said Hirotaka Oku, a spokesman at the science and technology ministry.

Checks in Ibaraki and Yamagata prefecture wrapped up in August and the findings will come out soon, he said.

The discovery of radiation at Niigata kindergartens coincides with the start of the rice harvest in the prefecture that was the country’s biggest producer last year with 7 percent of the total. Officials have already found radiation from Dai-Ichi in food including beef, tea and spinach.

So far, early tests on rice haven’t detected radiation, said Shingo Gocho, assistant director in Niigata prefecture’s agricultural division. The government is taking samples from 45 areas in 29 villages, towns and cities that make up the prefecture’s growing area, he said. The crops won’t ship until they know the results, he said.

Tokyo Electric’s Dai-Ichi plant released about 770,000 tera becquerels of radioactive materials between March 11 and March 16, Japan’s Nuclear and Industrial Safety Agency said June 6.

Japan’s government is under-reporting the amount of airborne radiation across the country, said Tom Gill, an anthropology professor at Meiji Gakuin University in Tokyo, citing his studies in Fukushima prefecture since March.

The “maximum” radiation level given for Fukushima prefecture on Aug. 13 was 2.64 microsieverts per hour in the village of Iitate 40 kilometers northwest of the Dai-Ichi plant, Gill said, according to figures from the Science Ministry published daily in national newspapers.

That compares with the official reading in the village itself the next day of 14.2 microsieverts per hour, he said, showing a picture he took of the reading on that day. He was speaking at a presentation in Yokohama near Tokyo on Aug. 19.

The government excludes the highest readings among 20 measuring stations in the village from the data it collates for publication, Gill said.

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