The revelation that a consignment of highly radioactive nuclear waste will be sent this week for recycling in Britain from the former Soviet state of Georgia is a reminder of how widespread the legacy of the Soviet nuclear programme is.

From warheads to radioactive lakes and decaying nuclear submarines, a complete map of Soviet radiation hazards has not yet been drawn.

The BBC Russian regional analyst Stephen Mulvey considers some that are already public knowledge.

The Chernobyl nuclear disaster, which occurred in Ukraine twelve years ago next week, is a nightmare that will continue to trouble scientists and engineers for years to come. The unstable and leaky concrete sarcophagus hastily thrown up around the ruined reactor is in severe need of repairs.

The G7 group of the world's richest industrialised nations is currently struggling to raise $760 million dollars needed to prevent the sarcophagus collapsing - and that is only phase one of a programme that is unlikely to be completed for decades.

Chernobyl was not the first accident of the Soviet nuclear programme. The secret Mayak bomb-making plant near Chelyabinsk in the Ural mountains was responsible for a whole series, beginning in the early 1950s - although little was known about them until the advent of glasnost ten years ago.

Chernobyl has contaminated the countryside for miles around

According to some reports more than 1,000 curies of radioactive waste - roughly 20 Chernobyls - was pumped from Mayak into a lake that even today is capable of delivering a fatal dose of radiation within an hour.

Mayak was also the scene of an explosion in a nuclear waste storage tank in 1957, when an estimated 70 to 80 tonnes of radioactive materials was blasted into the air.

A similar explosion was responsible for the worst post-Chernobyl disaster, at Tomsk in Siberia in April 1993. In this case several tonnes of uranium and plutonium salts were scattered over the surrounding countryside.

The manufacture of warheads has been the cause of much of the problems

Russia's main nuclear reprocessing plant is in Krasnoyarsk some 600 kilometres to the east of Tomsk. Between them Tomsk and Krasnoyarsk are responsible for the radioactive contamination of two of Siberia's great rivers, the Ob and the Yenisei, which flow north into the Kara Sea.

The Kara Sea is a notorious nuclear dump in its own right. Together with its western neighbour, the Barents Sea, it contains at least 18 nuclear reactors that formerly powered vessels of the Soviet navy.

The best-known of these is the nuclear submarine, Komsomolets, which sank 300 miles of the northern coast of Norway in 1989. Two other reactors were dumped in the Sea of Japan, and the Sea of Okhotsk.

Meanwhile, the most irradiated village in the world is reckoned by experts to be the small settlement of Sarjahl, in north-eastern Kazakhstan. The first Soviet hydrogen bomb was exploded just 30 kilometres away from it. In all more than 140 nuclear devices were detonated in northern Kazakhstan from 1949 onwards.

Disasters still unfolding

One of the most alarming features of the nuclear hotspots in the former Soviet Union, is that they are still being discovered, sometimes in unexpected places.

One source of contamination was only located last year in a military base outside the Georgian capital, Tbilisi, after soldiers mysteriously began to fall ill. It is unlikely to be the last case of its kind.

Possibly even more dangerous is the threat of nuclear material from the former Soviet Union falling into the hands of criminals, or sold to aspiring nuclear powers.