KIEV, Ukraine - Chernobyl was shut down forever with the flip of a switch Friday, shifting attention to needed repairs on the sarcophagus covering the nuclear plant's ruined reactor, which is leaking radiation 14 years after the world's worst nuclear accident.
The closing of Chernobyl's last working reactor was intended to prevent disasters like the one that sent a radioactive cloud across Europe, affecting millions of people and leaving a poisoned zone in this former Soviet republic.
President Leonid Kuchma, issuing the order to halt the reactor, alluded to the difficult work still ahead, saying: ''This menacing page of the book of modern history cannot be considered closed.''
At a state ceremony in Kiev, Kuchma gave the order to halt the reactor over a video linkup with the plant 84 miles away. At 1:16 p.m., Chernobyl shift chief Oleksandr Yelchishchev turned a switch, sending containment rods sliding into the core of reactor No. 3. Within seconds, a dial showed the atomic reaction in the core dropping to zero.
Kuchma asserted that energy-starved Ukraine was ''forsaking a part of our national interests for the sake of global safety.''
President Clinton, in a taped address released by the U.S. Embassy in Kiev, called it a ''triumph for the common good.''
''America is on your side. We wish you God speed,'' he said, adding in Ukrainian: ''Slava Ukrayini (Glory to Ukraine)!''
On April 26, 1986, Chernobyl's reactor No. 4 exploded and caught fire, contaminating vast areas of Ukraine, Russia and Belarus - all part of the Soviet Union at the time - and spewing a radioactive cloud over Europe.
The Kremlin tried to conceal the accident and delayed evacuation of people from nearby towns for days. Firefighters and other workers who were the first at the destroyed reactor had little or no protection from radiation.
More than 4,000 cleanup workers have died since and 70,000 have been disabled by radiation in Ukraine alone. About 3.4 million of Ukraine's 50 million people, including some 1.26 million children, are considered affected by Chernobyl.
A haphazardly built concrete and steel sarcophagus covers the ruined reactor, but it has developed leaks over the years. It emits high radiation levels and is also leaking water that may be contaminated.
The grayish Soviet-era structure is believed to contain up to 66 tons of melted nuclear fuel, in addition to some 37 tons of radioactive dust.
The covering now ''automatically assumes a leading role. It's our largest project,'' said the structure's director, Valentyn Kupny.
Ukraine hopes to build a new, airtight covering over the sarcophagus as part of a $758 million international project running through 2007. But that will not solve the problem entirely, Kupny said.
''The work of handling the fuel remaining inside will take dozens of years,'' he said. ''We'll have to work out an engineering decision on what to do with this fuel. At present, there is no such decision.''
The unloading of fuel rods from the other idled reactors will also last for years. And Ukraine still has to figure out how to help the 6,000 plant workers and their families survive the closure.
U.S. Energy Secretary Bill Richardson said Friday in Kiev that he had approved a grant to create a nuclear safety center that would employ Chernobyl workers, but which likely could offer jobs only to a fraction of those laid off. He did not say how much funding the grant would provide.
While many Ukrainians, tired of living with radiation fears, rejoiced over the plant's closure, some nuclear workers and officials called Friday a day of mourning.
''This event is like a funeral,'' said Russian Atomic Energy Minister Yevgeny Adamov.
Anatoliy Brig, a veteran nuclear worker who participated in the cleanup and attended Friday's closure ceremony, was bitter.
''This child of ours should have been kept working,'' Brig said. ''This reactor could have heated the country until 2007.''
For years, the energy-strapped government faced pressure from environmental groups and foreign leaders but refused to close the plant, citing the electricity it provided and demanding foreign aid in return. Kuchma finally pledged to shut down Chernobyl during a visit by Clinton earlier this year.
The European Commission has approved a $585 million loan to help Ukraine build two new reactors to replace the electricity produced at Chernobyl, and the European Bank for Reconstruction and Development will provide an additional $215 million.
The environmental group Greenpeace has called on Ukraine to abandon nuclear plant construction and find alternative sources of energy.
Pierre Cardin, the French fashion designer attending the ceremony as a UNESCO goodwill ambassador, seemed to echo that sentiment.
''It is a big, very big day today for your country and for the world too,'' he said. ''Don't begin again the drama of Chernobyl.''
