2011/03/30
The Fukushima No. 1 nuclear power plant's No. 1 reactor, foreground, No. 2 reactor, No. 3 reactor and No. 4 reactor behind the rising white smoke on March 15 (Tokyo Electric Power Co.)
As workers at the crippled Fukushima No. 1 nuclear power plant continue to pump tons of water onto its overheating reactors, the problem of what to do with radioactive water now flooding parts of the facility is becoming a major problem.
Officials directing the operation are being forced to improvise increasingly intricate plans to shift the radioactive water to other parts of the plant and allow workers vital access to the stricken reactors.
The water has filled trenches extending from the turbine buildings at the No. 1, No. 2 and No. 3 reactors and is also lying in pools in the basements of the three reactors' turbine buildings. It is thought that the water in the trenches flowed from the basements.
Dealing effectively with the contaminated water is vital to containing the spread of radiation. It has to be removed to allow the operation to cool the fuel rods in the reactor cores to move forward.
Tokyo Electric Power Co. (TEPCO), the plant's operator, said it was planning to pump the contaminated water into storage tanks on the grounds of the plant. That will involve shifting thousands of tons of radioactive water.
The trenches have a capacity of about 13,300 tons, but as much as 10,000 tons of contaminated water may already have poured into them.
The trenches house electrical cables and pipes providing seawater to cooling pumps and are normally kept dry, allowing workers to inspect the equipment.
Radiation levels as high as 300 millisieverts per hour were detected near the entrance to the trench at the No. 2 reactor. Radiation levels at the No. 1 and No. 3 reactors have reached between 0.8 and 1 millisievert per hour.
The shafts from the trenches are about 50 to 70 meters from the ocean. The possibility of radioactive water leaking into the ocean has not been ruled out.
Workers have been piling up dirt around the trenches to prevent them from spilling over. TEPCO workers began piling more dirt around the entrance to the shaft at the No. 1 reactor from Monday.
Pools of contaminated water, between 0.4 and 1.5 meters in depth, are still obstructing work in the basements of the reactors' turbine buildings.
The pipes in the trench are connected to the turbine building, and a TEPCO official said, "We cannot rule out the possibility that the water flowed underground."
TEPCO officials are putting priority on removing the water from the turbine buildings.
They want to remove the contaminated water using pumps in the reactors' steam condensers, which are air tight, but those condensers are themselves full of water.
TEPCO workers will first have to move that relatively uncontaminated water to condensate storage tanks outside of the buildings. Those tanks themselves already contain some water.
At the No. 2 and No. 3 reactors, temporary hoses are being used to move the water in the storage tanks to a storage tank for a suppression pool located further from the two turbine buildings. That work began Monday.
There are two suppression pool storage tanks south of the No. 4 reactor. Those tanks are used for all of the reactors at the Fukushima plant and their total capacity is 6,800 tons. There is currently only room for about 4,000 tons of water.
Facilities to process waste water at the plant have not yet been restored, which means that the water will have to be stored on site.
While work to deal with the contaminated water continued on Tuesday, workers kept on pumping water to cool the reactor cores and storage pools containing spent fuel rods.
The temperature in the No. 1 reactor core began rising again. At 2 a.m. Tuesday, it reached 329 degrees, considerably higher than the reactor's normal operating temperature of approximately 285 degrees. The pressure in the reactor was stable.
The volume of water pumped into the No. 1 reactor was increased by 30 percent from 8 p.m. Monday to 140 liters a minute. The temperature at 6 a.m. Tuesday was 323 degrees.
An official of TEPCO's Fukushima office said: "The temperature repeatedly increases and decreases. However, we have been able to control it. We will continue to keep a close eye on the situation."
The water pumping operation has put TEPCO in a predicament: Water must be provided to cool the unstable cores but if it continues to leak from the turbine buildings to the trenches, it may spill out into the environment.
An official with the Nuclear and Industrial Safety Agency said, "The work will involve seeking a balance between two contradictory considerations."
Because the stability of the reactor cores is the most important issue, TEPCO officials have no choice but to continue pumping the water in.
Meanwhile, Chief Cabinet Secretary Yukio Edano said the highly contaminated water and the detection of plutonium on the Fukushima plant grounds "showed there had been a partial melting of fuel rods."
Prime Minister Naoto Kan told an Upper House Budget Committee session on Tuesday that there was a high possibility that the reactors at the Fukushima No. 1 nuclear power plant would never be used again.
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