Tokyo Electric Power Co. said Friday that special cooling equipment will be in place at one of the reactors at the quake-hit Fukushima Daiichi nuclear complex by the end of the month, making the safe shutdown of the reactor a realistic prospect for the first time since the crisis began nearly two months ago.

Simultaneously, an operation has begun to flood damaged reactors with thousands of tons of additional water to cool them more effectively.

Risks remain in such an operation, however, including further stress on the reactor, which has already been under severe strain after a magnitude-9 earthquake and subsequent tsunami on March 11. But the government's Nuclear and Industrial Safety Agency gave the go-ahead to the flooding operation, saying the facility is capable of withstanding the weight of the additional water.

Separately, NISA spokesman Hidehiko Nishiyama was asked Friday about media reports that he has a daughter working for the plant operator, known as Tepco. While there is no prohibition on such a situation, the reports raise further questions about the independence of NISA as a regulator. Critics have previously noted that the agency is part of the Ministry of Economy, Trade and Industry, which is mandated to promote the use of nuclear power.

Speaking at a regular news conference, Nishiyama said he has always acted in accordance with the ethics of the civil service, but declined to comment specifically on the reports, which appeared in the weekly magazine Shukan Bunshun and the newspaper Nikkan Gendai.

Workers will start retrofitting a new cooling system at the No. 1 reactor on Sunday following the installation of ventilators that are expected to reduce the amount of airborne radioactive substances inside the reactor building. The work is expected to be completed by the end of the month, said a Tepco official.

The new cooling system will comprise a heat exchanger, to be installed near the equipment hatch of the reactor building, and air-cooling devices, to be installed outside the building.

The system is designed to replace the damaged water-based cooling system that was heavily damaged by the quake and tsunami. The breakdown of the cooling system was the cause of massive overheating that seriously damaged the core units of all three operational reactors.

A similar system will be installed at the No. 2 and No. 3 reactors by July, a Tepco official said.

"Once the cooling system comes online, the reactor is expected to cool down to less than 100 degrees Celsius in a day or so," the official said. Cool shutdown is when the temperature within the reactor is under 100 degrees on a continuous basis.

The nuclear fuel rods at the three reactors are believed to be partially above the water level, due partly to leakage through damaged parts of the reactor pressure vessel, the thick steel cylinder that houses the nuclear fuel. Tepco on Friday began inject more water into the reactor to increase the rate of flow from 6 cubic meters per hour to 8 cubic meters per hour, a move that is expected to completely submerge the fuel rods and also fill the reactor's containment vessel, which surrounds the pressure vessel, within about 20 days.

"By submerging the pressure vessel, the temperature of the fuel will be more effectively reduced than before," said Tetsuo Sawada, an assistant professor at the Tokyo Institute of Technology.

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