TOKYO — Confronted with worse-than-expected damage at its battered nuclear plant, Tokyo Electric Power Co. on Tuesday revised its strategy for cooling Fukushima Dai-Ichi’s reactors. The utility company nevertheless reaffirmed its goal of stabilizing the plant – and ending Japan’s nuclear crisis – within six to nine months.

Tepco was forced to overhaul its road map after learning last week of a substantial meltdown in the unit 1 reactor at the Fukushima Dai-Ichi facility, on Japan’s northeastern coast. Fuel pellets had collected at the bottom of the pressure vessel, burning small holes or cracks in the containment vessel that allowed coolant to leak out.

Japanese authorities say they fear similar scenarios have occurred at units 2 and 3, though engineers have not entered those reactor buildings.

Rather than flood the reactors with fresh water, a strategy outlined in the initial road map released April 17, Tepco plans to build a circulation system.

Water will be pumped into the pressure vessel, decontaminated after it leaks out, then pumped back in.

Although Tepco still says it will be able to shut down the three troubled reactors by January or thereabouts, it faces increasing skepticism from the government and the Japanese people, who complain that Tepco has too often misjudged the severity of the situation.

Damage at the unit 1 building became clear only last week, when engineers fixed a gauge that measures water levels.

Tepco had said for weeks that the fuel rods in unit 1 were 60 percent covered with water.

It turned out that the fuel rods in the vessel were fully exposed.

Amid the worst nuclear emergency in a quarter-century, 80,000 people who lived within 12 miles of the plant have fled their homes.

Japan’s government has re-evaluated its energy policy, calling for the shutdown of one earthquake-prone nuclear plant southwest of Tokyo.

Separately, Japan’s government agreed Tuesday to allow investigators from the International Atomic Energy Agency to visit and assess the Fukushima Dai-Ichi plant from Tuesday to June 2.