Vice President Al Gore circled by helicopter Thursday over the concrete-and-steel dome that covers Chernobyl's ruined reactor, then landed for a closer look at the site of the world's worst nuclear accident.

The vice president also toured the nearby ghost town of Pripyat, walking through abandoned apartment blocks and a children's playground. He spoke quietly to one Chernobyl plant worker who used to live there but was evacuated after the 1986 accident in the former Soviet republic.Gore made no remarks during his trip to the decaying Ukrainian plant, saying he was collecting his thoughts and would speak later in the day.

The vice president, who has made environmental issues one of his political priorities, has been discussing the fate of the reactor and its deteriorating sarcophagus on a two-day visit to Ukraine.

Ukrainian officials say they need Western help to shore up the weakening sarcophagus over reactor No. 4, which was destroyed in the accident. They also want aid to shut down the last working reactor at Chernobyl.

Although President Leonid Kuchma has pledged to close the power plant by 2000, top Ukrainian officials say the government first wants $1.2 billion compensation for lost energy.

On Wednesday, Gore failed to obtain a clear promise from Ukraine to close the plant by 2000 but said he was convinced that Kiev would honor previous pledges to do so. He also said America would help the country replace the lost power after Chernobyl's closure.

"It's imperative for the safety of the Ukrainian people, for the safety of Europe, for the well-being of the world, for the remaining reactor to be shut down as soon as it is feasible to do so," Gore said.

Gore plans to hold discussions on a new international effort to raise money to rebuild the deteriorating Chernobyl shelter. That project is expected to cost $750 million, and Kuchma said Ukraine has so far secured only $390 million.