Absorbent yet to soak up radioactive water at Fukushima plant
TOKYO (Kyodo) -- Workers tried Sunday to block the leakage of highly radioactive water into the sea from the crisis-hit Fukushima Daiichi nuclear plant by injecting polymeric water absorbent that can soak up 50 times its volume, but the water flow remains unaffected, the government's nuclear safety agency said.
Chief Cabinet Secretary Yukio Edano, meanwhile, told a press conference that it could take several months before radiation stops leaking from the plant, suggesting a lengthy battle ahead to resolve the crisis triggered by the devastating March 11 quake and tsunami.
Engineers put 8 kilograms of the polymeric water absorbent together with 60 kilograms of sawdust and three bags of shredded newspaper into pipes leading to a pit connected to the No. 2 reactor building where a 20-centimeter crack has been found to be leaking radioactive water into the Pacific Ocean, the agency said.
However, those materials injected at a point 23 meters away from the seaside pit have not been sucked into the water flow, leaving no impact on the rate of leakage, said Hidehiko Nishiyama, a spokesman for the governmental Nuclear and Industrial Safety Agency.
Nishiyama said the plant operator Tokyo Electric Power Co. will keep monitoring the situation until Monday morning to examine the effects of the water-absorbing mission. The firm will also try to trace the route of the radioactive water leakage from the pit by draining colored water on Monday, he added.
The utility known as TEPCO deployed the absorbent called "water gel bag," which contains polymeric materials used for diapers, as its efforts to encase the pit's fracture in concrete failed on Saturday.
Highly radioactive water has been filling up the basement of the No. 2 building and a tunnel-like underground trench connected to it. The water in the pit is believed to have come from the No. 2 reactor core, where fuel rods have partially melted.
TEPCO has revealed that radioactive iodine-131 more than 10,000 times the legal concentration limit was detected in the water found in the pit.
Nishiyama said the utility firm has confirmed that pits from the plant's other reactors do not have similar cracks. Workers have also been checking the condition of the embankment at the plant on the coast to find out other possible routes for radiation leakage into the sea, according to the agency.
Levels of radioactive substances have been skyrocketing in the sea near the nuclear power plant, fanning concerns about the expansion of sea contamination and the impact on fishery products.
The plant operator said the same day that two TEPCO workers in their 20s who had been missing since the magnitude 9.0 quake and tsunami that crippled the power station were found dead in the basement of a reactor turbine building last Wednesday.
They died of bleeding from multiple injuries apparently after the tsunami struck the plant, TEPCO said. It is the first time that TEPCO workers have been confirmed to have died at the Daiichi plant following the twin disasters.
In addition to efforts to block the contaminated water leakage, technicians continued operations Sunday to secure enough space in tanks to remove radioactive water that has been soaking the basement of the plant's Nos. 1-3 reactors.
The stagnant water has been obstructing work to restore the vital cooling functions at the reactors. Referring to Edano's remarks, Nishiyama said TEPCO aims to reestablish stable cooling systems at the plant within several months to prevent further radiation leakage and put recovery work at the site on track.
To store the tainted water, the utility is considering using a large artificial floating island called a "megafloat," and U.S. Navy barges that originally carried fresh coolant water for injection into the reactors, Nishiyama said.
Up to 11,000 tons of low-level radioactive water will be stored in the basement of the No. 4 reactor's turbine building as an emergency step, he added.
The utility has been pouring massive amounts of water into the reactors and their spent nuclear fuel pools as a stopgap measure to cool them down, because serious damage to the fuel rods from overheating could lead to the release of enormous amounts of radioactive materials into the environment.
However, the measure is believed to be linked to the possible leak of contaminated water from the reactors, where fuel rods have partially melted.
As part of recovery work, engineers on Sunday also connected pumps used to inject fresh water into the troubled reactors to an external power source, switching from emergency diesel generators, to stably pour in the coolant water, according to the agency.
Nishiyama said TEPCO will inject nitrogen into the containment vessel of the No. 1 reactor on Tuesday or later to help prevent the risk of more hydrogen explosions caused by overheating of the reactor.
(Mainichi Japan) April 3, 2011
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