First broadcast February 2007
The mysterious death in London of the Russian dissident Alexander Litvinenko was a story which could have come from the pages of a dramatic spy novel. But it actually happened - and has still not been fully explained.
This two-part series examines the work of scientists acting as nuclear detectives seeking to identify and control the spread of radioactive materials.
Part Two: Governments
Nuclear know-how is becoming increasingly available and governments, keen to develop their own nuclear weapons programmes, are investigating nuclear technologies.
Is a new round of proliferation underway?
This second programme investigates public - and not so public - nuclear weapons programmes.
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