27 Mai 2015
May 27, 2015
By MASANOBU HIGASHIYAMA/ Staff Writer
Tokyo Electric Power Co. said it “completed” the onerous task of processing about 620,000 tons of highly radioactive water stored at the Fukushima No. 1 nuclear power plant on May 27.
The work ended at 9:15 a.m., and it greatly reduces the risk of large amounts of radioactive substances leaking into the environment surrounding the crippled plant, TEPCO officials said.
The water, kept in storage tanks at the plant, had contained tens of millions to hundreds of millions of becquerels of radioactive substances per liter.
However, TEPCO has yet to decide how to handle the rising volume of processed water that still contains low levels of radioactive substances. Currently, about 440,000 tons of such water, containing several hundreds of becquerels of radioactive substances per liter, are on the plant site.
The site also has about 180,000 tons of contaminated water with some radioactive substances, such as strontium, removed. This water needs further processing to eliminate other radioactive substances.
The triple meltdown at the plant following the March 2011 Great East Japan Earthquake and tsunami has required tons of water to cool the nuclear fuel and keep the situation under control. That in turn led to a huge volume of highly contaminated water held in row upon row of storage tanks at the plant.
Another problem for TEPCO has been the 300 tons a day of groundwater flowing into the nuclear reactor buildings and becoming contaminated with radioactive substances. The utility is planning a “frozen soil wall” to divert the groundwater into the ocean before it reaches the buildings.
May 27, 2015 - Updated 10:20 UTC+2
The operator of the damaged Fukushima Daiichi nuclear plant says removal of 2 main radioactive substances is complete from most of the highly contaminated wastewater stored at the facility.
Tokyo Electric Power Company had presented a plan to the government to finish processing roughly 600,000 tons of radioactive wastewater by the end of March.
Officials with the utility cited problems with equipment for failing to meet that target. Instead, they aimed to complete at least one round of processing by the end of this month.
They announced on Wednesday that workers had removed cesium and strontium from about 620,000 tons of the wastewater stored in tanks.
They said about 10,000 tons of stored water could not be removed from the tanks and remained unprocessed.
They said workers were able to remove about 60 other types of radioactive substances from 440,000 tons of the wastewater. That leaves about 180,000 tons still to be processed for those substances.
TEPCO officials said the processed water is still contaminated and will remain in storage tanks.
Workers on Wednesday also began dismantling some of the storage tanks. The tanks are made with steel plates bolted together rather than welded and are prone to leaks.
TEPCO has about 370 of these tanks and is considering how many to replace with seamless types.
TOKYO (Kyodo) -- The operator of the crippled Fukushima Daiichi nuclear plant said Wednesday it has finished filtering a total of 620,000 tons of extremely toxic water being stored in tanks on the premises of the complex to lower its radiation level.
Tokyo Electric Power Co. says the risk of radiation leakages from the water tanks is now much lower. However, around 400 tons of radioactive water is still being generated everyday as groundwater is seeping into the plant and mixing with tainted water more than four years since the nuclear accident.
According to TEPCO, some 440,000 tons of the water has been treated through a key water processing system said to be capable of removing 62 different types of radioactive material with the exception of tritium. The remaining 180,000 tons has been processed through another facility capable of removing strontium, but still contains other types of radioactive substances and needs further treatment.
The highly radioactive water has been generated during the process of cooling the plant's reactors that suffered meltdowns in the March 2011 nuclear crisis triggered by the magnitude 9.0 earthquake and tsunami.
When Prime Minister Shinzo Abe visited the Fukushima plant in September 2013, TEPCO President Naomi Hirose pledged that the company would filter all the water kept in tanks by March 31, 2015 to drastically reduce the amount of radioactive materials it contains.
But the process has been delayed due to a series of problems with its key water treatment facilities.
The operator of the crippled Fukushima No. 1 nuclear plant said Wednesday it had finished filtering 620,000 tons of extremely toxic water stored in tanks on the premises of the complex to lower its radiation level.[…]