The big bang.

Chernobyl was a turning point. Until the nuclear reactor there exploded in April 1986, most Westerners bought the notion that the Soviet Union was a genuine superpower. After the Chernobyl disaster, it began to sink in that the USSR was really a Third world country in disguise.

At 1:22a.m. on 26 April 1986, a reactor crew carelessly turned off the safety systems of the Chernobyl Unit 4 reactor. Within 36 seconds, the reactor surged out of control. A steam explosion blew off the unit's roof releasing a cloud of radioactive gases more than a kilometre into the sky. This deadly plume spread radiation across Europe as far away as Italy and Scandinavia. The core of the reactor melted down, turning 150 tonnes of uranium fuel into lava that burned for ten days, giving off lethal vapours.

Five hundred thousand Soviet soldiers were sent to the plant north of Kiev in Ukraine to clean up the mess. They were not told of the extreme danger in which they worked. They bulldozed atomic debris into unlined and unmarked waste pits. Then, they buried the bulldozers. They entombed the damaged reactor in concrete.

Three years after the disaster, the Soviet government admitted that a quarter of a million people were still at risk from radiation. The country simply lacked the resources to move them to safety. To cover up the scale of the problem, the government consistently lied about the level of danger.

Eight years after the explosion, radioactive wild pigs root for radioactive berries in the radioactive forests that surround Chernobyl. Background radiation levels 500 times higher than normal are recorded, and 6,000 people still work in two reactors a few hundred metres from the site of the disaster. The belief has spread among the workers that vodka gives them protection against radiation. So, many of them go through their shifts drunk.

The concrete tomb that contains the still-hot reactor is crumbling and the Group of Seven industrialized nations has pledged $200 million to permanently seal it off . The pits into which contaminated soil was hastily tossed are now leaking. There are as many as 800 of these burial grounds and the location of some is unknown. A closed zone of 38 kilometres around the damaged plant is now a huge dirty stain from which radiation is seeping in all directions.

Officially, 31 people died in the Chernobyl disaster. However, thousands of clean-up workers and locals have since died from the effects of radiation. Nobody knows for sure how many people have been affected by the nuclear catastrophe, but one recent estimate is that worldwide the number is 55 million. Britain's Atomic Energy Authority has estimated that 40,000 people worldwide may die of cancer over the next 70 years because of the disaster.

The Chernobyl disaster exposed the limits of Soviet technical skill. It showed the world how fragile was the country's grasp on superpower status. Some have suggested that the explosion and the attempt to cover it up marked the beginning of the end of Mikhail Gorbachev's leadership and of the Soviet Union itself.

Meanwhile, badly designed nuclear reactors, similar to the one at Chernobyl, are still operating all over Central and Eastern Europe. Some are under the control of poorly trained staff who must keep them running despite a shortage of spare parts. Western technical experts who visit these reactors are said to leave terrified. That's why Julian Borger of The Guardian sums up an article on the aftermath of Chernobyl with this bleak forecast: "A second Chernobyl becomes more likely with every passing day."