28 Octobre 2014
Oct. 28, 2014 - Updated 04:49 UTC+1
Tokyo Electric Power Company, or TEPCO, says the levels of radioactive cesium in the compound's groundwater at the damaged Fukushima Daiichi nuclear plant fluctuated greatly last week.
TEPCO detected the highest concentration of cesium in samples of water taken from 2 monitoring wells near a reactor building on Wednesday.
One well had 428,000 becquerels of cesium per liter of water, while the other contained 458,000 becquerels.
But only 2 days later, the reading in the first well had dropped to 5,200 becquerels, or one-eightieth of the level detected on Wednesday. The concentration in the other well stood at 470 becquerels, or about one-one-thousandth of the previous quantity.
TEPCO says these wells are connected underground with other wells that are highly contaminated. So the operator believes cesium poured into them with this month's heavy rains and then flowed out with the underground water.
The utility says this problem cannot be fundamentally solved because the area around the wells thought to be the source of the contamination has extremely high radiation levels and cannot be decontaminated.
The 2 wells are among those from which tainted groundwater is pumped and discharged into the sea after being decontaminated.
But TEPCO has suspended the operation and is considering whether to resume the work.