Kazakhstan became independent 25 years ago this week as the Soviet Union fell apart. Amid celebrations and fresh hopes for the future,

the nation's new rulers quickly realize their former it masters had left behind a very dangerous legacy.

A mass of unguarded radioactive materials at the secret nuclear weapons testing zone.

I am Rustam Hobel and in the Polygon people here on the BBC Walt Service

I'll be telling the story of this vast secret testing zone and semi-Palatensk, the threat it

pose to the world and the lives it is shaped.

The story begins in the early days of the Cold War, a time when the two superpowers, the Soviet Union and the United States were in a standoff and armed themselves with nuclear weapons as a way of maintaining a fragile equilibrium of world peace.

The first thing to know is that Kazakhstan in Soviet times was a favorite place for nuclear

chemical and biological weapons experiments by the Soviet Union.

One reason is that it was very far away from Moscow that the United States

might not know about or find some of these secret testing zones and laboratories. David Hoffman,

Pouleau's

David Hoffman,

Pulitzer winning author of the dead hand.

Semi-Politensk's testing zone.

It's the size of Belgium.

It's on a very flat desolate part of Kazakhstan and the Soviet Union in this testing zone

carried out 456 nuclear explosive tests during the Cold War.

116 of them were in the atmosphere,

and later atmospheric tests were banned.

340 were underground.

Harmful radiation from the open air nuclear tests spread across the semi-Palatins test zone, known as the Polygon.

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