By Andrew Osborn
    The Independent UK

    Thursday 28 April 2005

    A leading Russian scientist has claimed that the sarcophagus entombing Chernobyl's broken nuclear reactor is dangerously degraded and he warned that its collapse could cause a catastrophe on the same scale as the original accident almost 20 years ago.

    Professor Alexei Yablokov, President of the Centre for Russian Environmental Policy, said the concrete and metal sarcophagus was riven with cracks, already leaking radiation and at risk of collapse unless repairs were undertaken and work on a replacement urgently begun.

    "If it collapses, there will be no explosion, as this is not a bomb, but a pillar of dust containing irradiated particles will shoot 1.5 kilometres into the air and will be spread by the wind." Depending on how the wind is blowing, Russia or Belarus would bear the brunt of such a dust cloud. Ukraine, where Chernobyl is located, would also be affected.

    The sarcophagus is designed to keep a lid on what is left of the nuclear reactor that exploded with such dire consequences during an unauthorised test in April 1986 and is supposed to stop the mass of unspent nuclear fuel that lies beneath from entering the atmosphere.

    It is estimated that only between 3 and 15 per cent of that fuel actually escaped during the explosion meaning that most of it is still trapped inside. Dr Yablokov, a member of the Russian Academy of Sciences and a one-time adviser to former president Boris Yeltsin, said nuclear reactions were actually taking place - spontaneously - inside the sarcophagus as rain and snow fell on the unspent fuel through cracks in the decaying shell.

    He said experts had "seen a luminescence characteristic of chain reactions inside the giant building". adding: "Who could predict what might happen if hundreds of thousands of tons of concrete, which was hastily poured 19 years ago, tumbled down on the ruined nuclear reactor?"

    His gloomy assessment corroborates that of the Ukrainian officials who manage the decommissioned power plant.

    Earlier this year Julia Marusych, the head of information at Chernobyl, admitted on Russian TV that the sarcophagus was in appalling condition: "The construction is unstable, unsafe, and does not meet any safety requirements."

    The sarcophagus was hastily thrown together after the explosion as a desperate attempt to contain the world's worst nuclear accident. Many of the workers who toiled on it have since died of cancer and the sarcophagus itself began showing signs of serious stress in the early 1990s.

    Built to last 50 years,experts were forced to reduce its recommended lifespan to just 20 years meaning a replacement is due in 2006.

    Some repair work was carried out earlier this year but progress is slow due to the fact that construction workers can only be in its vicinity for short periods because of radiation levels.

    Sceptics claim that warnings about its deterioration are designed to persuade Western donors to stump up the $1bn bill. A donors' conference takes place in London on 12 May and the Ukrainian government hopes to raise $300m.

    That task has been complicated, however, by recent revelations that private firms have embezzled some $185m of Chernobyl money, some of which was earmarked for a new shelter.

    The First Catastrophe

    26 APRIL 1986:

    1.23am: Reactor number four at Chernobyl nuclear power plant begins to fail. Explosion blows 1,000-ton cover off the reactor and 31 people die immediately.

    5am: Fire caused by explosion is put out by firefighters who are not warned of radiation. Many later die.

    Evening: Officials arrive at site and order evacuation of nearby town of Pripyat.

    27 April:

    Disaster is hidden until workers at Forsmark nuclear plant in Sweden are found to have radioactive particles on clothes. Swedish search for the source of radioactivity leads to the USSR.

    28 April:

    Soviet leadersadmit accident happened but full scale is not explained. First Soviet media reports: Chernobyl is fourth item in Moscow Radio's evening bulletin.

    1 May:

    Despite clouds of radiation overhead, authorities encourage locals to turn out for May Day parade in nearby Kiev.

    June-November:

    Large sarcophagus made of steel and concrete is hastily constructed.