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The status of six reactors at the Fukushima Daiichi nuclear plant

By the CNN Wire Staff
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Smoke spews from reactor

Tokyo (CNN) -- Workers at Japan's Fukushima Daiichi nuclear power plant have been scrambling to cool down fuel rods and prevent the release of additional radioactive material since a 9.0-magnitude earthquake and tsunami hit the area on March 11.

Here is a summary of the status of each of the plant's six reactors and surrounding buildings, according to the non-profit Japan Atomic Industrial Forum, Tokyo Electric Power Co. (TEPCO) and the International Atomic Energy Agency.

Reactor No. 1

Japan's Nuclear and Industrial Safety Agency said Wednesday that temperatures had spiked above 400 degrees Celsius in this reactor, forcing workers to inject more seawater into the reactor to cool it down.

On Tuesday TEPCO reported that seawater did more damage electrical and cooling systems for this reactor than previously believed, and the unit will take longer to repair than expected.

Fuel rods have been partly exposed, and the core of the reactor is believed to have been damaged. The building that houses the reactor was severely damaged in a hydrogen explosion March 12, but the containment vessel -- the steel and concrete shell that insulates radioactive material inside -- was not damaged.

Workers have been pumping a mix of seawater and boron into the reactor to prevent further core damage until coolant systems can be brought back online.

Reactor No. 2

Coolant pumps and electrical components were damaged at Reactor No. 2, and the earliest those parts can be replaced is Wednesday, TEPCO reported.

Officials say fuel inside the reactor has been partially exposed as temperatures rose and water levels dropped. Workers have injected seawater into the reactor.

The reactor building has been slightly damaged, and a suspected explosion March 15 may have damaged the reactor's containment vessel.

White smoke emerged from the building Monday and Tuesday, but the cause had not been determined.

Workers have been pumping a mix of seawater and boron into the reactor to prevent further core damage until coolant systems can be brought back online.

Reactor No. 3

Black smoke emerged from the building housing this reactor Wednesday. Officials have not said what caused it, or whether any radiation was released.

Power has been restored in the control room at this reactor -- which officials say could be a key step in bringing cooling systems back online. TEPCO planned to conduct tests Wednesday of pumps designed to inject water into the reactor.

Officials say fuel inside the reactor has been partially exposed as temperatures rose and water levels dropped. Workers have injected seawater into the reactor. Its fuel includes plutonium mixed with the uranium in its fuel rods, which experts say could cause more harm than regular uranium fuels in the event of a meltdown.

A pool containing spent fuel rods is a chief concern. Firefighters planned to continue dousing the pools with water Wednesday to keep those rods cool.

The building was severely damaged in a hydrogen explosion March 14. Gray smoke also emerged from the building Monday. By Tuesday, the smoke was white and was dissipating. Officials have not said what caused it.

Reactor No. 4

At least one fire and an explosion severely damaged the building on March 15.

The reactor does not contain any fuel rods, and no damage is suspected in the reactor's containment vessel.

But the pool that houses the spent fuel rods is a chief concern.

Crews continued using cement pumps to spray water on the pool Wednesday to keep fuel rods cool.

Reactor No. 5

Workers created vent holes in the building's roof to avoid a hydrogen explosion.

The cooling system has electrical power. That controls the temperature of the reactor, which is in cold shutdown, and the pool containing spent fuel rods.

Reactor No. 6

Workers created vent holes in the building's roof to avoid a hydrogen explosion.

The cooling system has electrical power. That controls the temperature of the reactor, which is in cold shutdown, and the pool containing spent fuel rods.

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