20/03 Workers frantically try to restore power at nuclear plant

2011/03/20

A fire engine of the Self-Defense Forces sprays water at the No. 3 reactor building of the Fukushima No. 1 nuclear power plant in Fukushima Prefecture on Friday. (Self-Defense Forces)

Work continued at a frenetic pace Saturday to restore electric power to the crippled Fukushima No. 1 nuclear power plant and prevent the nuclear crisis from deteriorating.

Tokyo Electric Power Co. officials said they hoped to transmit power to the No. 1 and No. 2 reactors on Saturday, which would be a huge breakthrough for workers in their weeklong fight to stave off a full meltdown.

A restoration of power could begin the process of supplying huge amounts of water to the reactor cores to cool the overheating fuel rods. TEPCO officials also hope to restore power to the four other reactors at the Fukushima No. 1 plant.

But TEPCO does not know if the cooling systems, damaged in the March 11 earthquake and tsunami, will work properly if power is restored.

In addition, the operation is expected to be a time-consuming affair, given the complexity of restoring power and operating the cooling systems.

A special rescue unit of the Tokyo Fire Department began water-spraying operations over the plant from about 2 p.m. Saturday to deal with another problem--replenishing depleted storage pools filled with spent fuel rods at the No. 3 reactor.

Plans called for spraying up to 1,000 tons of water for as long as seven hours straight.

Work began Thursday on restoring electricity to the nuclear plant, which was cut off after the Great East Japan Earthquake and tsunami severed the power supply and damaged emergency generators, TEPCO officials said.

Power lines of Tohoku Electric Power Co. used 40 years ago when the Fukushima plant was constructed were connected to temporary cables leading to the No. 1 and No. 2 reactors.

To reduce radiation exposure for workers, cables measuring a total of 1.5 kilometers were laid in a roundabout way into the plant.

Temporary cables will be connected to power lines used by TEPCO to restore electric power to the No. 3 to No. 6 reactors.

Work on restoring power to those four reactors is expected to be completed on Sunday.

If all goes well, electric power will first be restored to the No. 2 reactor, where some of the fuel rods in the core have become exposed and the suppression pool under the containment vessel has been damaged.

Officials fear radioactive materials may have leaked to the outside atmosphere.

If electricity can be restored, pumps would be used to supply large volumes of water to the core to cool the fuel rods.

Although the No. 1 to No. 4 reactors are all in a serious state, the outer building of the No. 2 reactor is the only one that has not been damaged by an explosion.

Some experts feared that an explosion at the No. 2 reactor building was inevitable. But the actual damage there was less than expected.

In fact, TEPCO officials have found that the electrical system for several of the pumps to the No. 2 reactor had not been damaged.

However, apparent steam rising from the No. 2 reactor building indicates that the temperature in the fuel storage pool has risen and that water is evaporating. Cooling the water in the pool is an urgent task, and is one reason officials want to restore power to the No. 2 reactor first.

If the pumps are operational, they can be used to supply seawater to cool the coolant in the storage pool.

But before a pump can be used, another pump must be able to cool the first pump. In addition, many vents must be properly operated, and each step of the process has to be confirmed before the switch can be turned on.

Alternative pumps have been prepared in case the pumps in the reactor have been damaged.

A TEPCO official said if any piece of equipment failed, workers would have to pinpoint the problem, fix it or find another method that works.

Officials of the Nuclear and Industrial Safety Agency said they couldn't provide a timeframe for when the water would be supplied to the reactor cores because they did not know the extent of damage to various equipment.

Emergency generators were partially restored on Saturday for the No. 5 and 6 reactors.

In the water-spraying operation, a water-supply vehicle dubbed "Super Pumper" has been placed by the ocean to supply seawater.

Another vehicle that can spray up to 3.8 tons of water a minute from a height of 22 meters will send water in the direction of the No. 3 reactor.

The storage pool containing spent fuel rods in the No. 3 reactor has a capacity of about 1,000 tons. If the water spraying continues for seven hours, it would supply about 1,260 tons of water, enough to fill even an empty storage pool.

The spray vehicle can be operated automatically so firefighters can avoid being exposed to radiation. But gasoline would have to be supplied to the vehicle two or three times over the course of the seven-hour operation.

The Tokyo Fire Department on Saturday dispatched 14 vehicles and 102 firefighters to replace the first group of 139 firefighters.

Other fire departments, including the Osaka municipal fire department, were considering dispatching vehicles to the Fukushima nuclear plant.

A CH-47 helicopter of the Ground Self-Defense Force flew over the Fukushima No. 1 plant to measure temperatures. The data will be used to determine the level of danger and assess the effects of the water spraying.