KIEV, Ukraine (AP) - A minor radiation leak was discovered today in a reactor destroyed at Chernobyl 10 years ago in the world's worst nuclear accident.
Plant operators reported that a small amount of radioactive dust leaked into the water filtration system of reactor No. 3 from the adjacent reactor No. 4, which was shattered by explosion and fire 10 years ago Friday.
Today's leak ranked as a level one on the seven-level scale of nuclear accidents developed by the International Atomic Energy Agency, said Andry Shatsman, shift engineer at the plant.
Level one means an accident does not pose radiation danger, but indicates a lack of safety provisions. The 1986 Chernobyl explosion measured seven and the Three Mile Island accident in 1979 was graded five.
Shatsman said workers in protective clothing cleaned up the contamination today, and no other employees were exposed to radiation.
The No. 4 reactor was entombed in a steel-and-concrete sarcophagus after the 1986 explosion and is no longer operating. But scientists have expressed concern about radioactive material leaking from the growing number of cracks and holes in the sarcophagus.
Another reactor was shut down indefinitely after a fire in 1991, leaving two working reactors at Chernobyl.
Ukraine's aging nuclear plants are plagued by minor accidents.
The last incident at Chernobyl was a radiation spillage in November, which initially went unreported. Later reports showed it was a relatively serious accident that exposed one worker to a year's allowed dose of radiation.
The 1986 explosion and fire at Chernobyl created a radioactive cloud that contaminated some 10,000 square miles and reached as far as western Europe. Some 5 million people in Belarus, Ukraine and Russia were affected, the World Health Organization says.
At least 30 people died immediately from the accident, but thousands more are believed to have perished from radiation-related illnesses.
On Tuesday, flames raced through five contaminated, deserted villages near the plant for seven hours, causing radiation levels to rise by as much as tenfold. Officials played down the potential health hazards. A cigarette was believed to have started the blazes.
Ukraine has promised to close Chernobyl by 2000 but only if the West helps pay for the closure, loss of jobs and other related costs. The G-7 group of industrialized nations this month upped its offer to $3.1 billion to assist Ukraine in the costs of closing the plant, but has refused to give a timetable for delivering the money.