On March 11, a magnitude 9.0 earthquake followed by a series of tsunami waves — the worst in the history of Japan — severely damaged the Tokyo Electric Power Co. (TEPCO)-operated Fukushima No. 1 nuclear complex, located along the coast of the towns of Futaba and Okuma in Fukushima Prefecture. As a result of the disaster, all external power sources were lost, causing the supply of cooling water to the plant’s No. 1, 2 and 3 reactors to stop. Hydrogen was generated as a result of a chemical reaction between fuel rods and water, leading to hydrogen explosions which badly damaged reactor buildings. The government, which initially estimated the accident level at 4 on the International Nuclear Event Scale (INES), later raised the level to 7 — the highest rank. This matched the level of the Chernobyl catastrophe, which at that stage was the worst nuclear accident in history.

The next six months were a huge struggle for both TEPCO and the government as they tried to deal with the tainted water. Shortly after the accident, every possible means was employed to inject water into reactors and spent nuclear fuel pools in a desperate effort to cool down nuclear fuel. Self-Defense Forces helicopters, fire engines and pumping vehicles were mobilized to inject sea water into the reactors and spent fuel pools. However, the injected water started piling up within reactor buildings, creating a mass of water contaminated with huge amounts of radiation. The water began to leak from the damaged containment vessels and piping.

At the end of March, water contaminated with high levels of radiation was found in a tunnel connecting the buildings housing the No. 1 to 3 reactors with the ocean. The water contained about 40,000 times the amount of water in reactors. Workers managed to prevent the water from leaking into the sea through a stopgap measure. However, as long as water continued to be injected into the reactors, the amount of radioactive water would only increase and overflow. Haruki Madarame, chairman of the Cabinet Office’s Nuclear Safety Commission of Japan, said neither the government nor the power supplier has the expertise to treat water contaminated with high levels of radiation, suggesting that they were not prepared to respond to any accident beyond the scope of their assumption.

According to the Nuclear and Industrial Safety Agency, contaminated water leaked into the ocean at least twice. The first instance occurred between April 1 and 6 at the No. 2 reactor, when 520 cubic meters was released; the second, between May 10 and 11 at reactor No. 3, when a total of 250 cubic meters of water was released into the open sea.

In a desperate effort to prevent further leaks, workers were forced to shift contaminated water into any tank on the premises of the plant that had some available capacity. While releasing 10,000 cubic meters of relatively low-level radioactive water into the sea, TEPCO shifted more water to neighboring facilities, and even purchased a nearby man-made floating island known as “Megafloat,” capable of holding up to 10,000 cubic meters of water and transported it to an area near the power plant.

Meanwhile, in its action plan released in April, TEPCO announced that it would cool down the reactor cores by filling their containment vessels with water. Even though the utility thought it would be an effective way to cool down the reactor cores, the water did not reach the level that was considered necessary to cool down the reactors. In May, a hole was discovered in one of the containment vessels — from which injected water was leaking, forcing TEPCO to abandon the method. As a result, contaminated water was continuing to build up within the power plant. As of the end of August, there was a total of 90,000 cubic meters of water stored in the reactor and turbine rooms of the plant’s No. 1 to 4 reactors. Counting the water stored in other facilities, the figure stood at about 113,000 cubic meters — enough to fill some 570,000 drums.

Following the failure of its initial plan, TEPCO then released a new one, announcing that the company would attempt to remove all radioactive materials from the contaminated water and reuse the purified water to cool down the reactor cores. The method would allow the utility to continue to cool down the reactors while preventing the amount of radioactive water from increasing further. TEPCO created a water purification system by combining machines produced by U.S.-based Kurion Co. and Areva Co. headquartered in France and other firms, which was put in full operation in June. In addition, the Toshiba-manufactured machine SARRY (Simplified Active Water Retrieve and Recovery System) was added in order to increase the system’s capacity to remove radioactive materials from the contaminated water.

The government hoped that if the plan was successful, it could lift emergency evacuation preparation orders for areas lying between 20 and 30 kilometers from the plant. However, a series of minor accidents, including temporary malfunctions and leaks from the 4-kilometer-long hose used to carry the water, slowed down the operation, and the operations of the system has not yet been stabilized. According to official data, 32 mishaps with the water purification system had occurred by mid-August.

“The lack of preparation and vision on how to deal with this crisis is a major point of regret,” says Yoichi Enokida, a professor of nuclear chemical engineering at Nagoya University. “The lack of objective views of the operation rate of the newly adopted nuclear waste removal system has only contributed to everyone’s rising distrust of nuclear power as a way of generating electricity.”

Mainichi Shimbun