JAPAN | REALITY CHECK: It’s 1 step forward, 2 steps back at Fukushima plant

Posted on July 12, 2011

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JAPAN | ASAHI SHIMBUN | 12 July 2011

Four months after the Great East Japan Earthquake, Tokyo Electric Power Co. still has a long and winding road to go before bringing the crisis at the Fukushima No. 1 nuclear power plant under control.

The company has been unable to inject nitrogen into the containment vessel of the No. 3 reactor to prevent another hydrogen explosion.

High levels of radiation have barred workers from entering the reactor building, which was badly damaged by a hydrogen explosion on March 14.

In early July, TEPCO tried to remove radioactive materials from the floor with a robot cleaner, but radiation levels did not fall as expected.

The company laid steel sheets to prevent workers’ exposure to radiation.

TEPCO has been injecting nitrogen into the No. 1 reactor building since early April and into the No. 2 reactor building since late June to prevent a hydrogen explosion.

The No. 1 reactor building was damaged by a hydrogen explosion on March 12. Part of the No. 2 reactor building was also damaged by an explosion at the suppression pool on March 15.

At the No. 4 reactor, the water temperature at the storage pool for spent nuclear fuel remained high at about 85 degrees.

TEPCO has not been able to install a circulating cooling system for the storage pool, which contains about 1,500 nuclear fuel assemblies. Water has been pumped in from an outside source through hoses, and the company plans to start operating a circulating cooling system by the end of July.

The No. 4 reactor does not contain any nuclear fuel because it was shut down for regular inspections when the tsunami swamped the plant on March 11.

Still, a fire and an explosion occurred at the No. 4 reactor building on March 15. The cause is not clear, although officials have suggested that hydrogen gas may have flowed back through an exhaust duct.

Meanwhile, the water temperature at the spent nuclear fuel storage pools for the No. 2 and No. 3 reactors has stabilized at about 35 degrees.

A circulating cooling system at the storage pool for the No. 2 reactor began operations in late May, and one at the storage pool for the No. 3 reactor in late June.

TEPCO, however, has not been able to measure the correct water temperature at the storage pool for the No. 1 reactor although water has been pumped into the pool through a piping system.

In addition, TEPCO is installing a cover for the No. 1 reactor building, which had its roof blown off in the hydrogen explosion, to prevent radioactive materials from spreading into the atmosphere and keep rainwater from entering the building.

The company is also adjusting water and pressure gauges at the No. 2 reactor.

Meanwhile, TEPCO has been cooling the spent nuclear fuel storage pools for the No. 5 and No. 6 reactors, which were shut down when the tsunami struck.

Water with low levels of radioactivity has been accumulating in the turbine building for the No. 6 reactor, and TEPCO is transporting the water to a temporary tank.

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