April 14, 2011
The difficult task of removing highly radioactive water at the crisis-hit Fukushima Daiichi nuclear power plant continued Thursday, with the level of polluted water in the plant’s underground trench found to be edging up again that morning after some 660 tons were pumped out.
The removal of some 60,000 tons of contaminated water from the basements of the Nos. 1 to 3 reactor turbine buildings as well as trenches connected to them is vital, as the water is hampering work to restore key cooling functions of the reactors lost in the March 11 killer earthquake and ensuing tsunami.
Plant operator Tokyo Electric Power Co (TEPCO) pumped out about 660 tons of highly radioactive water Tuesday and Wednesday from one of the trenches to a ‘‘condenser’’ inside the nearby No. 2 reactor turbine building, where in normal operations steam from the reactor is converted into water.
But the Nuclear and Industrial Safety Agency said that the water level at the vertical part of the trench on Thursday had increased by about 3.5 centimeters from the level observed at 6 p.m. Wednesday.
The level of the water is 2.5 centimeters lower than just before the water-transferring mission started.
Hidehiko Nishiyama, the agency’s spokesman, said that the rise in the water level is likely linked to the continued injection of water injection into the No. 2 reactor core, which is necessary to prevent the nuclear fuel inside from overheating.
‘‘As there is believed to be around 20,000 tons of water (in the No. 2 reactor turbine building and the trench connected to it), we feel the difficulty of lowering the level of the water in a stable manner,’’ he said.
TEPCO is preparing to transfer more of the highly radioactive water into a facility for nuclear waste disposal in the plant, which can accommodate 30,000 tons of liquid.
The water in and around the No. 2 reactor turbine building is believed to contain higher concentrations of radioactive substances than other contaminated water found at the site, and is believed to originate from the No. 2 reactor’s core, where fuel rods have partially melted.
TEPCO also started looking into how to check the quake resistance of already heavily damaged reactor buildings at the site in line with an order issued Wednesday by the government’s nuclear regulatory agency, in light of strong aftershocks from the March 11 quake.
The agency has told the utility to immediately examine the buildings and consider reinforcement work if they are judged as not sufficiently quakeproof.
TEPCO, however, has said that it cannot ‘‘immediately conduct an investigation’’ unless it confirms the safety of areas where checkups will be conducted.
To enhance preparation for tsunami waves triggered by aftershocks and other emergency situations, emergency diesel power or vehicle-mounted power sources are to be placed at higher ground, while backup units for water injection to the troubled Nos. 1 to 3 reactors are expected to be installed, according to the nuclear agency.
This article was posted: Thursday, April 14, 2011 at 4:51 am