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Tepco's nuke plant delays cause for worry
Publication Date : 31-07-2013
Tokyo Electric Power Co. has so far been unable to locate the source of spreading contaminated groundwater at its Fukushima No. 1 nuclear power plant, fuelling concerns the radioactive contamination may spread into wider areas, even out of the plant’s port facilities.
As the configuration of underground tunnels of power cables and seawater pipes where the contaminated water is accumulating is complicated, implementing measures such as draining the water, will take a lot of time.
At a time when the leakage of radioactive water into the Pacific Ocean has come to the fore, Tepco's delay in taking necessary action could affect the whole process of decommissioning the crippled reactors at the plant.
Tepco spokesman Noriyuki Imaizumi revealed the water level of the tainted groundwater in a test well located on the sea side of the No. 2 reactor has risen rapidly.
“If the water level continues to rise, it could reach the ground surface,” Imaizumi, an acting general manager of the company’s nuclear power-related division, said at a press conference Monday.
According to the company, the water level has risen about 70 centimetres over the past 20 days.
“We’ll consider taking steps to drain the groundwater and other measures,” he added.
To prevent contaminated groundwater from leaking into the sea, Tepco is working to reinforce the ground foundation of seawalls. The rising water level in the test well means the measures to prevent leakage have been working.
However, the company apparently failed to give much thought to the fact that the groundwater would have nowhere else to go.
For the past two months, Tepco has become bogged down in exploring measures to deal with the tainted groundwater by trial and error and has become unable to take decisive actions. The company initially suspected that the contamination originated somewhere near the exit of a tunnel for electric cables that runs from the No. 2 reactor’s turbine building to the sea.
In April 2011, the utility carried out work to stem the leakage of radioactive water at locations where tainted water was found to have leaked into the sea and the soil.
Imaizumi said, “The contaminated water that had already leaked into soil has spread gradually.”
However, as a result of monitoring radiation levels at other test wells, Tepco finds it difficult to believe the contamination originated from a single location.
On the sea side of Nos. 1 to 4 reactors, there are two types of tunnels, one for electric cables and the other for pipes for seawater, and more than 15,000 tonnes of contaminated water remains there.
Two years ago, the company did not conduct any work at locations other than the exit of test wells to prevent water leakage. It even failed to make any effort to remove the water from the tunnels at that time.
A source close to the matter said, “As problems occurred one after another at that time, [the company] couldn’t afford to work on the tunnels.”
As tunnels for electric cables are less resistant to earthquakes than reactors and other key equipment at the plant, they may have been damaged by the March 2011 Great East Japan Earthquake. The bottom of the tunnels is lined with gravel, and leaked contaminated water may have moved to other spots where groundwater is located.
Some tunnels are connected to turbine buildings where huge amounts of radioactive water are concentrated. Tepco plans to launch work to drain the tainted water but is likely to face many challenges, including how to close the connections to the turbine buildings.
Tepco began examining groundwater under the nuclear plant in December to find out why the pace of the drop in the level of radioactive substances in the port had slowed.
In May, the level of radioactive substances in the groundwater sharply rose, but Tepco denied that contaminated water had leaked into the Pacific Ocean. Even after the Nuclear Regulation Authority pointed out the possibility of such a leak, the utility adamantly refuted this. However, Tepco changed tack and admitted the leaks this month only after it found the water levels of the groundwater and the sea moved in unison.
Even so, the power company said the leaked water was “only affecting the area inside the port” that rings the facility.
Tepco's slow disclosure has been criticised.
“Tepco should have suspected there were leaks when the radiation level of the seawater did not decrease as quickly as before,” said Tsukuba University professor Tsutomu Yamanaka, an expert in hydrological science. “Seawater flows in and out of the port. A considerable volume of water has leaked.”
Atsunao Marui, head of the Groundwater Research Group at the National Institute of Advanced Industrial Science and Technology, said, “Groundwater also flows beneath the seafloor, so it’s possible that contaminated groundwater could spring up outside the port.”
Marui added that water outside the port also needs to be carefully checked.
Cloud over decommissioning
The problem of contaminated groundwater is casting a shadow over the process of decommissioning reactors of Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant.
The current plan places top priority on preventing the spread of environmental contamination by controlling the tainted water.
If the increase of contaminated water cannot be curbed, work to fill the reactors with water and remove nuclear fuel, which has melted down and then solidified, will be stymied.
To deal with the contaminated groundwater, it is essential to reduce the amount of such water in the basements of reactor and turbine buildings.
However, about 400 tonnes a day of groundwater flows into the buildings’ basements, increasing the quantity of contaminated water.
Currently, the number of storage tanks has been increased as a stop-gap, but sooner or later space for additional tanks will run out.
Tepco and the government were preparing to remove uncontaminated groundwater from wells above the plant dug to collect the water and discharge it into the sea before it can seep into the buildings’ basements.
But many in the local fisheries industry voiced strong concern about damage that could be caused by fears of radiation in connection with the plan. The latest leakage of contaminated groundwater surfaced against this background.
On Thursday, Hiroshi Kishi, president of JF Zengyoren, a national federation of the Japan Fisheries Cooperatives group, visited Tepco's head office and the Economy, Trade and Industry Ministry and said, “It [this time’s leakage] is a breach of trust of the people working in the fisheries industry and the public.”
Since March, a series of problems have occurred at the nuclear plant, such as a power blackout for many hours and leakage of contaminated water from underground water storage facilities. Thus Tepco's actions have not kept up with the problems.
The Nuclear Regulation Authority, which oversees safety management at the nuclear plant, decided to set up a working team to analyse conditions concerning contamination.
But the NRA’s actions have also been badly delayed. At a meeting Monday, an expert said the NRA “still can’t grasp the risks posed by the current situation”.