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2011年4月21日 (木)


--The Asahi Shimbun, April 19
EDITORIAL: TEPCO must prepare for additional risks in taming Fukushima crisis

Tokyo Electric Power Co. (TEPCO) has set a specific time frame for its long battle to end the nuclear crisis. The company on April 17 unveiled a road map for stabilizing the dangerous situation at its Fukushima No. 1 nuclear power plant, which was severely damaged by the March 11 earthquake and tsunami.

In the first stage of the plan, which will take about three months, measures will be taken to ensure stable and safe cooling of the damaged reactors and spent fuel pools.

In the second stage, steps will be made to bring the reactors to a stable state of cold shutdown in a process expected to require three to six months to complete.

It will take even longer to rebuild the lives of people living in areas around the ravaged nuclear power plant.
TEPCO admitted for the first time that it will take as many as six to nine months just to put the sources of radioactivity under control, which is a prerequisite for Fukushima evacuees to return home and restart their lives.

The continuous pouring of water on the reactors and the pools have prevented the No. 1 to No. 4 units at the plant from running out of control.

If this makeshift measure fails, the risk of a massive release of radioactive materials will grow sharply, forcing the government to reconsider again its policy concerning the evacuation of residents in the surrounding areas.

That would place far severer strains on the residents than the already heavy burdens they are bearing now.

The utility needs to execute its plan for containing the crisis under such circumstances. What is the most important is to prevent the situation from becoming any worse.

First and foremost, the company needs to be properly prepared for unpredictable events that may occur.

The biggest fear is a possible disruption in external power supply that causes the water injection to stop, which happened after a recent huge aftershock.

TEPCO's blueprint refers to such risks as aftershocks and lightning strikes, indicating that the company is trying to figure out ways to enhance the external power supply system. This should be done swiftly.

Easing this emergency requires working on reactors and fuel pools that cannot be inspected from up close due to high levels of radiation.

It is certain that the fix-it plan will have to be reviewed after each step is taken.

The company must not be so focused on carrying out the scheduled plan that it overlooks a big problem.

The road map raises concerns about whether the number of workers needed to carry through the lengthy process can be secured.

The plan requires a raft of tough and risky tasks, like sealing the container vessel of the No. 2 reactor and reinforcing the structure supporting the fuel pool for the No. 4 reactor. We wonder how many workers will be needed to perform these jobs.

Workers will face the risk of being exposed to high levels of radiation.

At the entrance to the building housing the No. 1 reactor, for instance, a level of radiation recently detected was so high that working for just an hour at the location would expose the worker to more radiation than the upper limit.

TEPCO's plan duly acknowledges the risk by pointing out the concern that long-term work at places with high levels of radiation may be required.

Workers must be replaced regularly before they are exposed to excessive amounts of radiation.

In addition, all of the damaged No. 1 to No. 4 reactor buildings are releasing radiation. That means the measures prescribed must be taken simultaneously at all the four buildings.

The manpower that can be provided by TEPCO, the reactor makers and their affiliates may be far from enough to carry out all these tasks.

Two key challenges in the mission are how to secure a sufficient number of workers, including reinforcements, and how to protect the health of these workers.

The government is also taking on a heavy responsibility by accepting TEPCO's road map to safety at the crippled nuclear power plant.


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