JAPAN | Tepco to soon inject unit 3 with nitrogen

Posted on July 9, 2011


JAPAN | JAPAN TIMES |  Saturday, July 9, 2011

Hosono says drive toward stable cooling on track

Tokyo Electric Power Co. said Saturday it will soon begin injecting nitrogen into reactor 3 at the Fukushima No. 1 power plant to prevent a hydrogen explosion — a sign that the utility could achieve stable cooling of all the crippled reactors by mid-July as initially planned.

The injection of nitrogen into the No. 3 reactor will be carried out as soon as Tepco gets the green light from the Nuclear and Industrial Safety Agency and local governments.

Tepco has already began injecting hydrogen into reactors 1 and 2.

The injection of nitrogen into the No. 3 unit is part of what is known as “step one,” which could be achieved by July 17. Tepco began injecting nitrogen in the No. 1 unit in April. This wasn’t possible for unit 3 because excessively high radiation prevented workers from laying the necessary groundwork.

The utility said it can start the injection after connecting hoses to the necessary pipes at the reactor. It found out Friday that the pipes and hoses will be easy to connect and the work should take only a few days.

Tepco also said NISA instructed it to submit a report concerning the nitrogen injection.

The utility plans to achieve a cold shutdown of the reactors after stable cooling is achieved.

Still, high levels of radiation at the No. 3 reactor building could prevent workers from carrying out the nitrogen injection, Tepco official Junichi Matsumoto said at a news conference Friday.

He said Tepco will consider increasing the number of radiation-blocking mats at the building to reduce workers’ exposure to radiation.

Meanwhile, the government has said it will send more psychiatrists to the Fukushima No. 1 and No. 2 plants to help reduce the mental stress of workers.

Reactor rate at 36.8%

The ratio of the nation’s 54 commercial nuclear reactors that are actually operating came to 36.8 percent in June, according to the Japan Atomic Industrial Forum.

As of the end of the month, 35 reactors, including those at the Fukushima No. 1 plant, were suspended, bringing the rate down to its lowest level since May 1979, when the figure dropped to 34.2 percent after reactors nationwide were suspended following the Three Mile Island nuclear crisis in the United States.

The suspension since May 15 of the No. 3 reactor at Kansai Electric Power Co.’s Mihama power plant for a regular checkup also contributed to pushing down the rate, the forum said.

The rate stood at 58.3 percent in March, 50.9 percent in April and 40.9 percent in May.

The ratio is expected to remain low in the face of possible delays in restarting those reactors suspended for regular checkups, after the government suddenly ordered additional safety assessments called “stress tests.”

The government had said earlier that sufficient steps had been taken to restart and safely operate two reactors suspended for checks at the Genkai power plant in Saga Prefecture.

But on Wednesday, it said additional safety assessments would be conducted at all nuclear power plants to check the reactors’ capacity to withstand extreme natural events, causing prefectural and local government leaders to retract or postpone their decisions to approve rebooting the two Genkai reactors in the near future.

According to NISA, the operation ratio of commercial reactors stood at 67.3 percent in fiscal 2010 and 65.7 percent the year before. The rate is expected to drop significantly this fiscal year.

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