CHERNOBYL - A spot of brilliant light beamed out from the red and white striped ventilation stack above the Chernobyl nuclear power station's reactor Number 4 on Wednesday.
A Ukrainian welder, braving an unhealthy dose of radiation, was repairing supports to the ventilator damaged in the 1986 explosion that ripped apart Chernobyl's fourth reactor in the world's worst civil nuclear accident.
The explosion spewed a deadly radioactive cloud, forcing hundreds of thousands of people to leave their homes. Ukraine's health ministry says radiation-related diseases are four times more prevalent in that country since the explosion.
Barbed wire surrounds a 30-kilometer (20 miles) exclusion zone around the plant and several abandoned towns. Ukrainian police stop cars at checkpoints to test them with Geiger counters for contamination.
The repairs, funded by the United States and Canada, are the first of a series of desperately needed measures to stop the collapse of the steel and concrete "sarcophagus" entombing the reactor after years of bickering between Ukraine and Western donor countries.
The US$200,000 worth of repairs are a drop in the ocean compared to the $750 million the former Soviet republic says it needs to make the crumbling sarcophagus safe.
But the work being done is the most urgent as it should stop the ventilator from toppling onto neighboring reactor Number 3, which the plant plans to restart next week.
The third reactor, the only one of four still functioning after the disaster, was closed down last year after cracks were discovered in the cooling system's pipes.
Now the third and fourth reactors, which stand back to back under the shaky ventilation stack, form the two strands in impoverished Ukraine's strategy to extract cash from Western nations pushing for Chernobyl's closure by the year 2000.
Valery Popov, an engineer charged with monitoring the sarcophagus, thumbed through photographs of cracked concrete and corroded metal girders.
"Behind the metal wall," said Popov, pointing to the massive slate-gray barn-like structure over the fourth reactor, "there are large cracks right across the concrete structure."
He said the wall, holding back tons of highly radioactive debris, had shifted 40 millimeters in 1997 alone.
Popov said the roof was in danger of collapse and rainwater, which had seeped into the structure and become contaminated, could pose a threat to the water table not far from the surface.
"The structure is not hermetically sealed," he explained. "The more we dither about 'stabilizing' the structure, the worse it gets -- I think we shall have to build a new, second sarcophagus to contain the reactor."
Western donors, including the Group of Seven (G7) rich industrial nations, have promised more than $300 million toward overhauling the sarcophagus and are likely to stump up the rest.
The sticking point is an additional $1.6 billion demanded by Ukraine to complete two new nuclear plants in the west of the country. The government argues it needs them to replace Chernobyl's lost generating capacity.
The European Bank for Reconstruction and Development (EBRD), the Chernobyl donors' main representative, has fought the demand, saying loans for the two plants would be unviable. Ukraine's skewed system of subsidies and poor tariff collection mean a fifth of its electricity is simply given away.
With each side camped out on their positions for now, Ukraine will restart Chernobyl's third reactor four days before the EBRD holds its annual general meeting in Kiev next month, which plant officials say is a coincidence.
