Waiting for another catastrophe

On April 26, 1986 the worst accident in history of the nuclear power industry happened at Chernobyl Nuclear Power Plant (ChNPP) when one of the four reactors exploded causing significant damage to ChNPP buildings and releasing into the atmosphere large amounts of radioactive materials. Immediately after the accident, a temporary shelter was constructed to confine the damaged unit. The Shelter was built hastily, under extreme conditions of radiation, using original structures damaged by the explosion to support new structures. Following the accident, several structural evaluations of the Shelter were carried out and steps taken to strengthen some unstable structures. In 1996, based on available structural data, the European team of experts concluded that the Shelter was in critical condition. An estimated remaining service life of the Shelter in 1996 was 10–13 years under ordinary and none under extreme loads. Collapse of the Shelter could lead to a release of radioactive dust and increase the criticality hazard. To prevent this from happening the Team of experts developed a plan, according to which the Shelter would be stabilized during 1997–2001. In spite of the perceived urgency, no stabilization works have been carried out to date. Recent analysis of results of previous studies and stabilization efforts shows that the existing Shelter may be in danger of collapse. The only remaining safe solution is an expedient construction of a new confinement around the Shelter.