April 6, 2011
Tokyo Electric Power Co (TEPCO) on Wednesday prepared to inject nitrogen into one of the reactors at the crippled Fukushima Daiichi nuclear power complex to reduce the potential risk of a hydrogen explosion, while it succeeded in stopping highly radioactive water leaking into the Pacific Ocean from the plant.
The nitrogen, an inert gas, is expected to be injected into the No. 1 reactor’s containment vessel, a process that could take several days. Hidehiko Nishiyama, a spokesman for the government’s nuclear agency, denied during a morning press conference that there is an ‘‘immediate danger’’ of explosion.
In addition to the task of maintaining the relative stability of all six reactors at the nuclear complex, TEPCO has also been engaged in efforts to stop highly radioactive water from leaking into the sea and cleaning up contaminated water within the plant.
At 5:38 a.m., highly contaminated water, which had been confirmed as leaking into the sea from around a cracked pit located near the No. 2 reactor water intake on Saturday, stopped flowing after TEPCO injected around 6,000 liters of chemical agents including sodium silicate, known as ‘‘water glass.’‘
The Nuclear and Industrial Safety Agency said it had ordered the utility to continue monitoring the pit to check whether the water leakage has completely stopped, and noted it is possible that the water, which has lost an outlet, could show up from other areas of the plant.
The highly radioactive water is believed to have come from the No. 2 reactor core, where fuel rods have partially melted, and ended up in the pit. The pit is connected to the No. 2 reactor turbine building and an underground trench connected to the building, both of which were found to be filled with high levels of contaminated water.
To make room to store the highly radioactive water that is hampering the plant’s restoration work, TEPCO continued to dump into the sea massive amounts of low-level contaminated water from inside a nuclear waste disposal facility at the site, as well as contaminated groundwater found from around the Nos. 5 and 6 unit buildings.
TEPCO is aiming to dispose of a total of 11,500 tons of low-level contaminated water in the sea by this weekend, a move which has sparked concern among neighboring countries and strong protests from the domestic fishing industry.
Opening up the nuclear waste disposal facility could be completed as early as Thursday, Nishiyama told the morning press conference. The move would be followed by some repair work to ensure that the facility can retain highly radioactive water safely without fear of the stored liquid leaking outside.
The plant’s power grid and most of the emergency diesel generators were knocked out by the magnitude 9.0 earthquake and ensuing tsunami on March 11, resulting in the loss of many of the reactors’ key cooling functions, partial melting of reactor cores and hydrogen explosions.
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. But the measure is causing ‘‘side effects,’’ such as the detection of contaminated water in various parts of the nuclear complex and some leakage into the sea.
A seawater sample taken near the No. 2 reactor water intake on Saturday showed a radioactive iodine-131 concentration of 7.5 million times the maximum level permitted under law, or about 300,000 becquerels per cubic centimeter.
This article was posted: Wednesday, April 6, 2011 at 4:50 am