Air-cooling Plan studied at the plant - Wall Street Journal

TOKYO - Japanese authorities, with growing hedges in their plans to restore the crippled the Fukushima Daiichi nuclear power plant cooling systems, are considering a new approach - relying on the air.

Reuters, that an unmanned robot working in the Fukushima Daiichi plant Monday.

The information came on the same day that Masataka Shimizu, President of the plant operator Tokyo Electric Power Co., defended the company in the Japanese Parliament. He dismissed the charge of some legislators that the company held offshore on the use of sea water to cool the reactors overheat in the early days of the crisis, saying that just as took the time to prepare.

Japan Trade Minister Banri Kaieda said Monday that the Government would ask government officials "to refrain" take positions to electric companies after their retirement from the Department, in an effort to critics address the Japan regulators are too familiar with the energy sector.

The possible use of an air-cooling system as a common to the United States and European plants was among the new details available for a disclosed plan Sunday curb three reactors damaged in the Centre of the Japan nuclear crisis.

"A system envisaged air-cooling would be like those who are already used in the French nuclear power plants," said Hidehiko Nishiyama, spokesman and Deputy Director General of nuclear and industrial safety agency Japanese. TEPCO is sounding out potential manufacturers, the Agency said.

Reuters Masataka Shimizu, President of the plant operator Tokyo Electric Power.

These systems are not used to the Japan, where the reactors are located next to the ocean to employ heat exchangers that depend on the cold water of the ocean. Japanese experts say that, although an air-cooling system is less effective, it could provide a more practical solution than the repair of pumping underground water systems.

Water, including the salt water, was pillars of Japanese efforts to cool the overheating of nuclear fuel in the first days of the nuclear crisis in the Japan. On 26 March, the plant from switching to the use of fresh water. But the water has caused problems because it has become radioactive and is now flooding in the basement of buildings nearby house critical cooling equipment.

Each reactor has two sets of water pumping systems. The first runs more radioactive water fuel rods to keep them cool; the water then mostly evaporates as steam. The second cools the water so it can be used again. An air-cooling system would be cool water from the reactor, keeping within the system.

In his strategic plan unveiled Sunday, Tepco plans to fill the factory No. 1 containment vessels and 3 reactors with water and employ systems of heat exchanges that might include an air-cooling solution. Similar projects are in place for the No. 2 heavily damaged reactor unit, but must wait for the repair of leaks that allow the leak of highly radioactive water contaminated with the damaged fuel rods.

A U.S. - made robot was used Sunday to find buildings of units no. 1 and no. 3 for the first time since they were hit by massive explosions in the first week of the crisis. It found high levels of radiation. Levels would not necessarily preclude workers find facilities for repair work, according to Mr. Nishiyama, the NISA. But he said that more data should be collected in a wider area until the workers are sent to the Interior.

Readings from radiation, evaluated with Pakbot of iRobot Corp., showed that the levels ranged from 10 to 49 millisieverts per hour on the ground floor of the reactor No. 1 and 28-57 millisieverts in reactor No. 3. Workers are allowed to be exposed to a total of 250 millisieverts per year under the Japan regulations.

The robot has not been sent in the reactor No. 2 building, believed to have the highest level of radiation.

Tadashi Narabayashi, Professor of engineering at reactor at the University of Hokkaido, said a single air-based system may bring the complex reactors Fukushima, a judgment of the cold because "reactor core temperatures have already been made considerably dropped the [water]"-spraying operation. "" Fact cold shutdown refers to when a reactor is cooled to the safe temperature - under the boiling point of water - and is depressurized.

Plant operators have succeeded in lowering the temperature in the reactor at between 90 and 200 degrees centigrade-dependent unit, much lower than degrees will pass reached a month ago when units overheating and damaged critical of the fuel rods.

"The latest disaster showed that the use of seawater as a coolant has its own problems," said Wataru Sugiyama, Atomic Energy Research Institute of Kinki University lecturer. "To pump a large amount of water in the plant requires large machines, which is not easily replaced once it is damaged by events such as a tsunami."?A small air-cooling system, however, can be installed more easily. ?

Some legislators to the Parliament of Japan Monday blown m. Shimizu, President of the Tepco, in his testimony before a Committee. Some accused the utility of tergiversé on the use of sea water to cool the reactors for fear that it would render unnecessary units.

"The thought of decommissioning reactors must have crossed your mind.". "You were afraid to damage the reactors," said Mikishi Daimon, a legislative upper house with the Communist Party.

Mr. Shimizu denied this was the case, saying that the use of sea water took the time to implement.

Tepco President also said that the utility would probably plans for two new reactors at the plant in Fukushima. He said "Go ahead with the construction of units of no. 7 and no. 8 has become difficult in the current situation".

The Trade Minister Kaieda said senior officials would be actually be arrested to take positions in utilities after they retire. "We decided to take measures concerning employment to electric companies to avoid arousing suspicion," he said.

-George Nishiyama contributed to this article.

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