The University of Tokyo’s Institute of Industrial Science says it has developed a cloth that radioactive cesium sticks to, which can be used to remove the toxic substance from water.
The cloth reduced the amount of radioactive cesium from about 20 becquerels per liter to a level below the lowest detectable level of 8 becquerels, researchers said Monday.
For the experiment, associate professor Kazuyuki Ishii of the institute and other researchers put the cloth in water collected from the downspout of a home in Iitate, Fukushima Prefecture, near the crippled Fukushima No. 1 nuclear plant.
The chemically treated cloth contains potassium ferrocyanide and ferric chloride, both food additives.
The researchers also found that the cloth was able to collect on its surface nearly 70 percent of the radioactive cesium in a solution that contained soil contaminated with about 30,000 becquerels of radioactive cesium per kilogram.
Ishii said the cloth can be made with inexpensive materials and he hopes it will help decontaminate areas within homes with relatively low levels of radioactive cesium, such as downspouts.
Debris burning safe
Kitakyushu detected no dangerous levels of cesium in a recent trial incineration of quake and tsunami debris that was conducted over the strong objection of local residents opposed to the city’s handling the March 2011 disaster wreckage amid fears of radioactive contamination.
The city said it detected only 19 to 30 becquerels per kilogram of cesium in airborne ash in exhaust gas after it burned the debris from Miyagi Prefecture. The government-set allowable limit is 8,000 becquerels.
No cesium was detected from accumulated ash and waste gas emitted from chimneys with filters at two waste incineration plants in the Fukuoka Prefecture city. The debris originated in Ishinomaki, Miyagi Prefecture, which was hit hard by last year’s calamity.
“The results will reassure residents, because they indicate (there is no threat to) people as well as farm and marine products,” Kitakyushu Mayor Kenji Kitahashi said.
The city conducted the incineration test after protesters blocked the debris delivery to a storage site last week and clashed with riot police, causing a delay in the shipment and resulting in the arrests of two men.
Reactor check planned
Tokyo Electric Power Co. plans to check the interior of the crippled reactor 1 at the Fukushima No. 1 nuclear plant between late August and September by inserting a camera into the primary containment vessel.
Reactors 1, 2 and 3 experienced meltdowns last year in the wake of the March 2011 quake and tsunami, but the utility has so far only managed to insert an endoscope into reactor 2, where it found the water level was at a lower than expected 60 cm, a sign that a large part of the cooling water injected into it is leaking from the vessel.