Tokyo Electric Power Co. said Friday it will take a month to start circulating radioactive water cleaned using a newly installed water treatment system to cool the Fukushima No. 1 plant's crippled reactors.
Photo: Reuters/Yuriko Nakao
Tepco also said it will require about a month for spent fuel rods in the storing pools at four reactor buildings to be cooled in a stable manner.
Meanwhile, the utility said there will be no change in its road map, which projects a cold shutdown being achieved by January.
Due to the growing number of workers at the site exposed to high levels of radiation, Tepco added to its tasks improving their working environment.
Also Friday, Tepco was set to start full-scale operation of the system to clean the highly radioactive water accumulating at the damaged Fukushima No. 1 power plant, a key step in containing the nuclear crisis, the government's nuclear safety agency said.
Full operation of the newly installed water treatment system was delayed when water was found leaking during a trial run Thursday, but the Nuclear and Industrial Safety Agency said repairs have been completed.
The treated water will eventually be injected into the troubled reactors, whose key cooling functions were knocked out in the March 11 earthquake and tsunami, leading to so-called circulating injection cooling.
Tepco is eager to fully activate the water treatment system, as continually injecting water into the reactors from outside has created vast pools of contaminated water in the reactor turbine buildings and nearby areas.
The system, composed of installations developed by Kurion Inc. of the United States and France's Areva SA, will transfer some of the polluted water to a facility on the plant's premises and clean it during several processes, including reducing the amount of cesium and other radioactive substances, and removing oil and other contaminants.
Thursday's leak was found at the Kurion's installation, after a rupture disc component broke when the pressure inside rose dangerously, according to Tepco. A worker may have erroneously touched a lever to operate a valve, resulting in the pressure change, it said.
Once the water treatment system starts operating, the utility plans to decontaminate about 1,200 tons of polluted water per day. Up to 480 tons are expected to be recycled as coolant for the reactors, the agency said.
Meanwhile, Tepco planned to release later Friday an updated road map for bringing Japan's worst nuclear accident under control, but a government official said no major change was expected from the previous version.
Under the road map, first announced April 17 and revised a month later, the utility aims to bring the crippled No. 1 to 3 reactors and spent fuel pools to a stable cooling condition by mid-July and to a cold shutdown by around January at the latest.