Tokyo Electric Power Co. said radioactive cesium levels in a well at the Fukushima No. 1 nuclear power plant on July 8 were 90 times higher than those measured at the same site just three days earlier.
TEPCO said July 9 that cesium levels of 27,000 becquerels per liter, the highest cesium levels found since the onset of the March 2011 nuclear disaster, were detected in water samples a day earlier from a well on the seaward side of the No. 2 reactor building.
“It is unclear whether the radioactive water is leaking into the sea,” a TEPCO official said. “After gathering needed data, we will conduct analyses.”
The unusually high cesium levels were found in a well near the water intake for the No. 2 reactor, from which highly radioactive water leaked into the sea in April 2011.
TEPCO said cesium-134 levels in the well water were 9,000 becquerels, 150 times the legally permitted level, while 18,000 becquerels of cesium-137, 200 times the legally allowed level, were also detected in the water.
Although total cesium levels in the water collected on July 8 were 90 times the levels measured on July 5, levels of other radioactive substances, including strontium, were 890,000 becquerels, the same as three days ago.
“We do not know why only cesium levels have risen,” a TEPCO official said.
On May 24, TEPCO also detected strontium levels of 1,000 becquerels and 500,000 becquerels of tritium or tritiated hydrogen, in water from a well 25 meters west of the shore protection.
Since the May 24 discovery, TEPCO has dug four new wells, located north, south, east and west of the original well, to measure levels of underground radioactive substance levels. The highest cesium levels since the disaster were found at one of the four new wells.
Although hundreds of thousands of becquerels of tritium have been detected at some of the wells, tritium levels differ from day to day.
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