In all, 7 million people in the former Soviet republics of Belarus, Russia and Ukraine are estimated to suffer physical or psychological effects of radiation related to the April 26, 1986, catastrophe, when reactor No. 4 exploded and caught fire.
An area half the size of Italy was contaminated, forcing hundreds of thousands of people to be resettled and ruining some of Europe's most fertile agricultural land, the United Nations said.
Hundreds of Ukrainians filled the small Chernobyl victims' chapel in the Ukrainian capital, Kiev, at 1:23 a.m. Monday (6:23 p.m. Sunday ET), the exact time of the explosion. Later, they laid flowers and lit candles at a small hill where marble plates are inscribed with the names of hundreds of victims.
Nearly 1,000 mourners gathered Monday afternoon at Kiev's memorial to Chernobyl victims, a soaring statue of five falling metallic swans. Some placed flowers and photos of deceased relatives at its base.
"Nothing can be compared with a mother's sorrow," said Praskoviya Nezhyvova, an elderly retiree clutching a black-framed photograph of her son, Viktor. She said he died of Chernobyl-related stomach cancer in 1990 at age 44.
Volodymyr Diunych, a driver who took members of the hastily recruited and inadequately equipped cleanup crews to the site, recalled watching as residents were evacuated "in an awful rush" days after the disaster. Meanwhile, the Soviet Union's traditional May Day celebrations went ahead in Kiev, 80 miles south of Chernobyl, only five days after the accident.
Soviet authorities had withheld much information on the world's worst nuclear accident, both from its own people and from the rest of the world. Only last year, Ukraine's security service declassified secret files documenting malfunctions and safety violations at the plant that caused the release of small doses of radiation from time to time long before the explosion.
Ukraine shuttered Chernobyl's last working reactor in December 2000, but many problems remain.
Ukrainian experts say that the concrete-and-steel shelter that was hastily constructed over the damaged reactor needs urgent repairs, but authorities claim that there are no serious safety threats. Meanwhile, many people injured or displaced because of the explosion complain about inadequate government support.
Sergei Shchvetsov, the head of Russia's Chernobyl Union, said that 40,000 people disabled in operations to clean up the blast live in Russia and the "volume of benefits to which (they) are eligible is narrowing every year," the ITAR-Tass news agency reported.
Greenpeace activists held a small protest outside Russia's Department for the Inspection of Radiation Security, carrying signs that read "No more Chernobyls."
Meanwhile, in the Ukrainian town of Slavutych — built to house Chernobyl workers displaced by the accident — people held a solemn memorial meeting early Monday to honor the memory of their relatives, friends and colleagues.
The accident occurred after officials put the reactor through a test in which power was reduced and some safety devices were disabled.
More than 2.32 million people have been hospitalized in Ukraine as of early 2004 with illnesses blamed on the disaster, including 452,000 children, according to Ukraine's Health Ministry. Ukraine has registered some 4,400 deaths.
The most frequently noted Chernobyl-related diseases include thyroid and blood cancer, mental disorders and cancerous growths. The United Nations said in a statement that in some areas of Belarus, thyroid cancer among children has increased more than 100-fold when compared with the period before the accident.
Two years ago, the U.N. reported that 200,000 people still live in highly contaminated areas and 4.5 million residents in three countries are receiving financial help - draining national budgets.
The explosion and fire at Chernobyl's No. 4 reactor contaminated 23 percent of Belarus, 5 percent of Ukraine and 1.5 percent of Russia, according to the report. It also spewed a radioactive cloud across Europe.