The nation's nuclear watchdog body slammed Tokyo Electric Power Co. on Feb. 27 over its failure to disclose information on the leakage of radioactive rainwater into the sea from the crippled Fukushima No. 1 nuclear power plant.
The nation's nuclear watchdog body slammed Tokyo Electric Power Co. on Feb. 27 over its failure to disclose information on the leakage of radioactive rainwater into the sea from the crippled Fukushima No. 1 nuclear power plant.
Plant operator TEPCO disclosed many months later that a drainage ditch near the wrecked reactors showed high concentrations of radiation and rainwater had leaked into the sea outside the enclosed harbor.
“TEPCO must reflect seriously (on the delay). We are concerned that the company's efforts to secure a safe environment will be unable to obtain trust (from the people),” said NRA Chairman Shunichi Tanaka during a meeting in Tokyo that TEPCO President Naomi Hirose attended.
Hirose apologized profusely, saying, “We are extremely sorry for adding to the anxieties of fishermen and local citizens.”
This latest setback prompted local fishermen to dig in their heels over plans by TEPCO to release treated water. On Feb. 27, the Soma-Futaba fishery cooperative association and the Iwaki fishery cooperative association agreed to put talks on hold with the utility with regard to its “subdrain plan,” a key measure to reduce contaminated water in the nuclear plant.
TEPCO plans to pump up contaminated groundwater that has accumulated in the plant compound and remove radioactive materials so it can release the water into the sea. The utility has been seeking approval from local fishermen of the plan.
TEPCO became aware more than a year ago that the concentration of radioactive materials in the water flowing in the drainage ditch was high. The utility explained the situation to an NRA working group meeting held in January 2014.
The NRA that February instructed TEPCO to take countermeasures by the end of March 2015. At that time, however, the cause of the high concentration was unclear.
In April 2014, TEPCO started taking regular measurements. It suspected that the contaminated water was draining from slopes near reactor buildings. The utility covered the slopes and cleaned the drainage ditch. However, the concentration level did not decline. It reported the failure to determine the cause to the NRA in December.
Meanwhile, TEPCO continued to conceal details, including the fact that the concentration became high whenever it rained. It was only on Feb. 24 this year that it provided a detailed report to the NRA.
TEPCO explained accumulated rainwater on the roof of a service entrance for large equipment that connects to the No. 2 reactor building was the cause of the high concentration.
The compound of the nuclear plant is contaminated with radioactive materials due to the March 2011 accident there. That explains the presence of contaminated rainwater that accumulates in drainage ditches and elsewhere on the site. However, TEPCO had decided long ago there was no need to monitor rainwater for radioactive materials.
Water that flows in drainage ditches around tanks storing contaminated water was able to drain directly into the harbor, which has been sealed off from the open sea. Alarm devices were installed there, but TEPCO did not take special measures for the drainage ditch where the highest concentration of radioactive materials that emit beta rays was about 1,500 becquerels per liter when it rained.
Even on days when it was not raining, the concentration level was about 100 becquerels.
In drawing up the subdrain plan, TEPCO explained to fishermen it would reduce the concentration level of contaminated water to less than three becquerels before releasing it into the sea.
In 2013, contaminated water leaked from faulty tanks one after another. At that time, concentration levels were more than 10,000 times higher than the latest incidence of leaks. Because of that, a TEPCO official said, “We put too low a priority on the situation.”
Yoichi Miyazawa, minister of economy, trade and industry, accused TEPCO of dealing inappropriately with the situation.
“TEPCO should have paid more attention to the issue,” he said.
An NRA official handling the matter said, “We should have pushed TEPCO much more strongly to tackle the issue.”