Radiation fallout from Fukushima plant will take "months" to stop

2011/04/05

Contaminated water gushes out of a crack in a wall at the Fukushima No. 1 nuclear power plant on Saturday. (Provided by Tokyo Electric Power Co.)

Editor's note: We will update our earthquake news as frequently as possible on AJW's Facebook page: http://www.facebook.com/AJW.Asahi. Please check the latest developments in this disaster. From Toshio Jo, managing editor, International Division, The Asahi Shimbun.

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The government on Sunday acknowledged for the first time that it would take several months before radioactive materials stopped leaking from the crippled Fukushima No. 1 nuclear power plant.

Goshi Hosono, special adviser to Prime Minister Naoto Kan for the Fukushima crisis, told reporters: "We cannot allow radiation to go on being emitted. Yet while we have to resolve that problem as quickly as possible, it will likely take several months to achieve that goal."

Hosono is coordinating cooperation efforts with the United States to deal with the plant.

Chief Cabinet Secretary Yukio Edano also said Sunday, "It will take months to cool (the reactors) and to implement measures to prevent (radiation) from spreading."

At a Friday news conference, Kan also said the government would have to be prepared for a protracted fight to resolve the issue.

The setting of a general time frame likely means that the government wants to show it has a long-term commitment to the situation, rather than merely haphazardly fixing problems when they arise.

Firefighting pipes are now being used to pump in large volumes of water into the reactors to cool the fuel in the cores. However, highly radioactive water is believed to be leaking out of the reactor buildings and flowing into the ocean.

Officials of Tokyo Electric Power Co., the plant operator, want to restore the normal cooling system that would cool both the reactor core and the storage tanks holding the spent fuel rods. Doing so would allow sufficient water to cool the core down to under 100 degrees, at which point it would reach a cold shutdown. The core and storage pool would then become stable and there would be no danger of radioactive materials leaking to the atmosphere through hydrogen explosions, and also no need for water to be pumped into the core.

The time frame of several months given by Hosono is believed to be the time needed to achieve a cold shutdown, but reaching that stage will not be easy. The first task is to remove the contaminated water that has accumulated in the basements of the turbine buildings, which are next to the reactor buildings.

The process, which involves moving water to various pools within the plant ground, is already under way, but it is expected to take at least a week. TEPCO workers want to move the contaminated water in the basements to condensers in the No. 1 to No. 3 reactors. However, the three condensers were already filled with water, so they had to first take that water out and transfer it to the suppression pool storage tanks. This stage has now been completed.

The next step is to move the water from the condensers to their respective condensation storage tanks. This is under way for the No. 1 and No. 2 reactors, and preparations are being made to start on the No. 3 reactor, with the whole process expected to be finished in a few days. After that, the transfer of the contaminated water can finally begin.

Once the water is removed, radiation levels within the buildings will have to be measured to determine if workers can enter to begin the next step.

The March 11 earthquake and tsunami likely caused devastating damage to pipes, valves and pumps within the buildings. Restoring the equipment to normal operations is expected to be a time-consuming procedure.

While those tasks are being performed, water will continue to be pumped into the core to cool both it and the storage pool. That means that highly contaminated water will continue to leak into the outer environment.

Although some causes of the leakage have been determined, some have evaded identification, so stopping the leaks entirely will be another difficult task.

TEPCO workers on Sunday attempted to plug a leak found in a working pit near the seawater intake to the No. 2 reactor, but had not managed to stop the leakage of water into the ocean as of 6 p.m. Sunday.

TEPCO officials are now considering dropping a fence into the ocean to prevent the spread of contaminated water.

The idea being contemplated is to lower a silt fence into the water. Silt fences are used in civil engineering projects to prevent the spread of polluted water. The fence is suspended from a float and extends to the seabed like a curtain and is designed to limit the movement of seawater.

The water off the coast of the Fukushima No. 1 plant has a depth of between five to six meters. One idea being considered is to install the fence near the seawater intake from where contaminated water is flowing as well as near embankments that surround the waters off the plant site.

TEPCO also said Monday it had started pouring low-level radioactive water into the sea. The amount of the relatively uncontaminated water is 11,500 tons at the facilities to process wastewater and in the buildings which house the No. 5 and No. 6 reactors at the Fukushima No. 1 nuclear power plant, it added.

The release of the water may affect fish and seaweed near the plant, but TEPCO officials explain that eating these on a daily basis will total only as much as one-fourth the amount of radiation that people receive from natural sources.