Tokyo Electric Power Co. said Monday that it has detected radioactive cesium in groundwater samples taken from the premises of the crippled Fukushima Daiichi nuclear complex, reversing an earlier announcement that any contamination was negligible.
The announcement came as TEPCO is trying to secure the understanding of local fishermen over the dumping in the Pacific Ocean of groundwater that has been pumped out from wells at the site, saying it has confirmed that concentrations of radioactive substances are sufficiently low.
TEPCO had said radioactive cesium in the groundwater was at a level that could not be detected by an instrument at the Fukushima Daiichi complex. But the same sample was found to contain 0.22 becquerel of cesium-134 and 0.39 becquerel of cesium-137 per liter when checked at the Fukushima Daini plant, where radiation levels are lower.
Radioactive cesium was detected in 51 food products from nine prefectures in excess of a new government-set limit in the first month since it was introduced April 1, according to data released by the health ministry Tuesday.
The limit was exceeded in 337 cases, or 2.4 percent of 13,867 food samples examined by the Health, Labor and Welfare Ministry.
Cesium exceeding the previous allowable limit of 500 becquerels per kilogram was detected in 55 cases, while the new limit of 100 becquerels was exceeded in 282 cases.
Radioactive cesium from the crippled Fukushima No. 1 nuclear plant may have reached as far as Hokkaido, Shikoku and the Chugoku region in the west, according to a recent simulation by an international research team.
Large areas of eastern and northeastern Japan were likely contaminated by the plant, with concentrations of cesium-137 exceeding 1,000 becquerels per kilogram of soil in some places, says the study, which was posted Monday on the website of the National Academy of Sciences.
Researchers for the U.S.-based organization said the study, which was based on partial data readings, is the first to estimate potential cesium contamination across the country. But they also played down the incident’s impact on the three distant regions.
The science ministry’s latest aerial monitoring over Chiba and Saitama prefectures in September confirmed that radioactive cesium released from the Fukushima No. 1 power plant has contaminated parts of the Kanto region.
A ministry report released Thursday revealed that contamination was found in northern Chiba, including the cities of Kashiwa, Matsudo and Abiko, and in the mountainous areas of Chichibu in Saitama Prefecture’s west and Misato in the prefecture’s east.
The highest contaminated areas contained between 60,000 to 100,000 becquerels of cesium-134 and -137 per square meter, it showed. Cesium-134 has a half-life of two years and the one for -137 is 30 years.
Radioactive cesium exceeding the legal limit has been detected in four tea products that reached the market and were made with tea leaves from Saitama and Chiba prefectures, a recent health ministry inspection showed.
One of the products, using tea leaves from Chiba Prefecture, contained 2,720 becquerels of cesium per kilogram, far above the government-set limit of 500 becquerels, the Health, Labor and Welfare Ministry said Friday.
The three other products, made with tea leaves from Saitama Prefecture, were found to contain between 800 and 1,530 becquerels of cesium. It is the first time cesium exceeding the maximum limit has been detected in Saitama tea leaves.
The amount of radioactive cesium ejected by the Fukushima reactor meltdowns is about 168 times higher than that emitted in the atomic bombing of Hiroshima, the government’s nuclear watchdog said Friday.
The Nuclear and Industrial Safety Agency provided the estimate at the request of a Diet panel but noted that making a simple comparison between an instantaneous bomb blast and a long-term accidental leak is problematic and could lead to "irrelevant" results.
The report said the crippled Fukushima No. 1 plant has released 15,000 terabecquerels of cesium-137, which lingers for decades and can cause cancer, compared with the 89 terabecquerels released by the U.S. atomic bombing of Hiroshima.
A research agency in Fukushima Prefecture has begun testing about 110 varieties of Japanese and foreign rice in a search for strains that absorb less radioactive cesium from the soil.
The project, which was initiated by the Fukushima Agricultural Technology Center in Koriyama, after the meltdowns and explosions at the Fukushima No. 1 power plant, is unprecedented in that no research has ever been done on rice grown on land tainted by relatively high amounts of radioactive matter, the center’s research team said.
The research is important since the radioactive fallout from the Tokyo Electric Power Co. plant will likely disrupt rice farming in nearby areas for years to come, it said.
Radiation fallout from the wrecked Fukushima nuclear plant poses a growing threat to Japan’s food chain as unsafe levels of cesium found in beef on supermarket shelves were also detected in more vegetables and the ocean.
More than 2,600 cattle have been contaminated, Kyodo News reported July 23, after the Miyagi local government said 1,183 cattle at 58 farms were fed hay containing radioactive cesium before being shipped to meat markets.
Agriculture Minister Michihiko Kano has said officials didn’t foresee that farmers might ship contaminated hay to cattle ranchers. That highlights the government’s inability to think ahead and to act, said Mariko Sano, secretary general for Shufuren, a housewives organization in Tokyo.
“The government is so slow to move,” Sano said. “They’ve done little to ensure food safety.”
Beef cattle at a farm in Asakawamachi, Fukushima Prefecture, have been fed with straw tainted with high levels of radioactive cesium, and 42 cows from that farm have been shipped to Tokyo and three other prefectures, according to the Fukushima prefectural government. The prefectural and central governments, which have begun investigating the marketing route, asked all cattle farms in Fukushima Prefecture to refrain from shipping or moving any cows until Monday, when the on-the-spot inspections will be completed. Earlier this week, beef cows shipped by a farm in Minami-Soma in the prefecture were found tainted with radioactive cesium exceeding the provisional regulatory limit of 500 becquerels per kilogram.