Editor's Note: This is part of IEEE Spectrum's ongoing coverage of Japan's earthquake and nuclear emergency. For more details on how Fukushima Dai-1's nuclear reactors work and what has gone wrong so far, see our explainer.
Six weeks after the Great East Japan Earthquake struck the northeastern coast of the country and crippled the Fukushima Dai-1 Nuclear Power Plant, a stark reminder of what might still lie ahead came on April 26, the 25th anniversary of the Chernobyl nuclear accident in the former Soviet Union. A quarter of a century on and the International Atomic Energy Agency continues to “assist the Ukrainian government in evaluating the amount and types of radioactive waste that has accumulated at the nuclear power plant.” And the plant is still awaiting decommissioning, “a mammoth undertaking that requires extensive planning,” according to the agency.
Fukushima, too, faces a long road. Tokyo Electric Power Co. (TEPCO) unveiled a roadmap last week aiming to produce a cold shutdown of the three damaged reactors within the next nine months, many experts believe that the timetable is based more on hope than realistic goals, given the many hurdles that still remain. Not least among these challenges is the high radiation levels preventing onsite workers, who are already fatigued, from carry out their tasks for any sustained length of time.
“I think (the roadmap) is a very optimistic, one full of expectations, and I have grave doubts that it is viable,” says Atsushi Kasai, former laboratory chief of Japan’s Atomic Energy Agency. “No one really knows what the state of the three reactors are like inside because of the very high radiation levels (in the reactor buildings). The workers will have to go in to investigate the situation. We simply don’t have enough data to know how long it will take to bring them to a cold shutdown.”
TEPCO is not battling alone in its fight to close the power station. Toshiba Corp., which supplied two of the reactors at the site, and Hitachi Ltd. which provided one, each now have over a thousand workers involved in helping to stabilize the plant, and Hitachi is working on its own shut down plan.
To date, a total of 600 Toshiba employees have worked at both the Fukushima Dai-1 and Dai-2 sites (Dai-2 is in a state of cold shutdown) “with about 140 or 150 employees working as needed on a rotational bases at the Dai-1 site,” a Toshiba official told Spectrum. He added that while Toshiba has provided TEPCO with dosimeters, electric motors for cooling water pumps, transformers, distribution switchboards, and power cables, Toshiba itself is receiving a variety of assistance from its collaborative partners in the power business in the United States including Westinghouse Electric Co., civil engineers The Shaw Group, power technologies provider Babcock & Wilcox, and utilities company Exelon Nuclear Partners.
“And with these companies we’ve also formed a task force and submitted a decommission draft plan to TEPCO,” the official said. “After the plant is stabilized, the plan outlines the opening up of the reactor, removal of the fuel rods and transporting them to a safe place.” The draft also includes steps to dismantle the plant and remove the radioactive debris. “The minimum time given is ten years,” the official added. “This could be extended because there might be complications.”
Hitachi, together with Hitachi-GE Nuclear Energy Ltd. and Hitachi-GE Nuclear Holdings LLC, also has over a thousand “staff members providing support and assistance where needed,” according to a Hitachi official. Earlier, the company submitted its own decommission plan to TEPCO, “but it was more a general outline,” said the official. “Now we are working with our [GE joint ventures], Exelon, and Bechtel Corp on a more detailed proposal. But until we can check the condition of the reactors, we cannot give a timeline on how long it will take to decommission.”
Meanwhile, the battle to keep the three reactors in a relatively stable state continues. Today, TEPCO sent a remote controlled robot into the No. 1 reactor building to check the reactor for water leaks. It found none and no significant rise in radiation levels. As a result the company will test out increasing the amount of water it is injecting into the reactor from a daily 6 metric tons to a maximum of 14 metric tons starting Wednesday. The aim is to steadily boost the amount of water that is collecting in the torus, or suppression pool, until it covers the pressure vessel and can cool it down from the outside.
The company is also reconnecting outside power cables feeding the site so that in the event of another earthquake and tsunami, the plant might not suffer another total power outage.