9 Septembre 2016
September 7, 2016
It has been nearly five and a half years since the meltdowns at Tokyo Electric Power Co. (TEPCO)'s Fukushima No. 1 nuclear plant, and both the utility and the Japanese government remain stymied in their efforts to control the buildup of radioactively contaminated water at the facility.
The problem is simply stated: Groundwater flows down from higher inland elevations towards the Pacific, collecting in the nuclear plant's shattered reactor buildings and becoming contaminated. The plant grounds are packed with (occasionally leaky) storage tanks full of water pumped out of the reactor and turbine building basements, but the water does not stop.
TEPCO has attempted to stop the groundwater from getting into the buildings with a 1.5-kilomter subterranean "ice wall" (actually frozen soil) around the No. 1-No. 4 reactor buildings, but results have been inconclusive. Meanwhile, water decontaminated at the plant remains laced with radioactive tritium, and no storage site has yet been found to put this wastewater. The government is aiming to have all the radioactive water at the Fukushima plant dealt with by the end of 2020, the year Tokyo will host the Summer Olympics, but the way ahead is far from clear.
For one, the ice wall has holes in it.
"Due to heavy rain, the temperature rose above 0 degrees Celsius in two locations (along the wall)," a TEPCO public relations representative told a news conference on Sept. 1, the day after Typhoon Lionrock passed through northeastern Japan. The rainfall that came with the storm had caused a massive increase in the flow of groundwater, which then melted two holes in the ice wall, the official stated.
The freezing operation began in March this year, but part of the perimeter refused to solidify due to local geological features that caused the groundwater to flow particularly quickly. The fact that the typhoon's rains could punch more holes in the wall revealed yet another weak point in the entire project, and experts have begun openly calling it a failure.
TEPCO decided on the ice wall in 2013, to close the spigot on the some 400 tons of radioactively contaminated water being produced daily at the Fukushima plant as groundwater came into contact with the melted fuel from the station's reactor cores. A total of 1,568 pipes were sunk vertically 30 meters into the earth along a perimeter around the reactor buildings. Then coolant chilled to 30 degrees below zero was circulated through the pipes to freeze the surrounding soil and create an "ice dam."
The project was treated as TEPCO's trump card in its battle against the contaminated water problem, and the utility began the freezing operation along the plant's seaward side in March this year. Freezing commenced on the rest of the wall in June, and TEPCO claimed that as of August, 99 percent of the seaward section and 91 percent of the landward section had been frozen successfully
However, in the five months since the operation began, there has been almost no drop in the amount of radioactive water produced. Experts at an Aug. 18 meeting of the Nuclear Regulation Authority (NRA) asked TEPCO point blank, "When will we see results?" Others commented, "TEPCO's claim that the ice wall is highly effective at blocking the water flow is utterly bankrupt," leaving utility officials fumbling for answers.
"The ice wall isn't really a 'wall' per say, but more like a bamboo screen, which has gaps," Nagoya University professor emeritus Akira Asaoka told the Mainichi Shimbun. "It's obvious that the ice wall's ability to block water is poor. A different type of wall should be considered as soon as possible."
To complicate matters, the ice wall project is tangled up with expectations for the 2020 Tokyo Olympics. The Japanese government decided in September 2013 to commit large sums of public money to the ice wall and other contaminated water countermeasures. Four days later, Prime Minister Shinzo Abe was in Buenos Aires, telling the assembled members of the International Olympic Committee's general session that "the situation (at the Fukushima plant) is under control." He stated that the effects of the radioactive water had been entirely confined to the 0.3 square kilometers of the plant's harbor. Later that day, Tokyo was announced as host of the 2020 Games.
So far, the central government has poured some 34.5 billion yen into the ice wall project. To say that the stupendously expensive initiative had failed would very likely invite scathing public criticism. Minister of Economy, Trade and Industry Hiroshige Seko told a news conference last month that "it's true the ice wall is a difficult project, but the freezing is progressing." And yet, no results have been forthcoming.
Solving the Fukushima No. 1 plant's contaminated water problem by 2020 is inscribed in the reactor decommissioning schedule set by the government and TEPCO. If the ice is a failure, it would not just throw the work schedule off kilter; it would violate a publicly stated commitment to the international community.
To boost the ice wall's effectiveness, in June TEPCO began injecting a specialized cement into parts of the perimeter that remained stubbornly unfrozen, and instituted supplementary projects to make the ground easier to freeze. TEPCO plans to freeze every side of the perimeter, but it remains to be seen if the utility will have anything to show for its work.