Transforming chernobyl

The explosion of unit 4 of the Chernobyl nuclear power plant on 26 April 1986 was caused by deficiencies in the design of its RBMK reactor and its operation. Radioactive material was discharged outside the destroyed reactor, contaminating a large area: tens of thousands of people were evacuated from within a 30 km zone around the plant and other areas in Ukraine, Belarus and Russia were heavily affected.

The response

Following the accident, the Soviet authorities acted to prevent the further spread of radioactive material remaining in the exploded reactor. A provisional structure was constructed around the wrecks of unit 4 in hazardous conditions. This shelter became known as the “sarcophagus” and its purpose was to confine the remaining 95 per cent of the unit’s total radioactive inventory. The shelter was, however, only designed as a temporary solution.

In order to remedy the human and environmental consequences of the 1986 catastrophe, the international community offered its support to the Ukrainian government. By 2000, the Ukrainian government had closed the three remaining reactors and was faced with the task of dealing with the resulting nuclear waste and spent nuclear fuel. Since 1995 the safe decommissioning of units 1-3 in Chernobyl has been supported by the EBRD-managed Nuclear Safety Account.

A comprehensive strategy for the destroyed unit 4 was designed to deal with the threat of contamination from the nuclear material enclosed in the shelter built around the unit in 1986. These works have been financed since 1997 by the EBRD-managed Chernobyl Shelter Fund.

The solution

The strategy and plan for the conversion of the “sarcophagus” into a stable and environmentally safe system is addressed by a detailed work strategy, called the Shelter Implementation Plan (SIP). The SIP was developed in 1997 by a group of Western and Ukrainian experts and financed by the EU’s TACIS Programme and the US Department of Energy. Agreed by Ukraine, the G7 and EU, the SIP provided the roadmap to the solution and a basis for assistance for its implementation.

The implementation

At the beginning of 2005, the SIP entered its final stage. All major Chernobyl site infrastructure facilities and programmes (radiation and industrial protection, medical training, emergency response) have since been completed. These facilities and programmes ensure adequate protection of people during the construction activities, which have commenced. Site services in the construction zone have been renewed and a change facility constructed.

A comprehensive monitoring system (nuclear, radiation and seismic) as well as the site access control and physical protection system are under construction and scheduled for completion in 2008.

In early 2007 a programme consisting of a series of challenging measures to increase the stability of the existing shelter has been successfully completed. These measures, performed under extremely difficult conditions, inside and outside the shelter, are designed to reduce the risk of a collapse which would whirl up large amounts of contaminated dust and complicate any further activities on site. The stabilisation measures were essentially completed on time and in budget (with an overall cost of around USD 50 million)

The tender process for the New Safe Confinement - the largest component of the SIP - is complete and contract signature is scheduled for September 2007.

The New Safe Confinement will confine radioactive material within the shelter and isolate it from incoming rainwater and snow . The shelter will be protected from further degradation or collapse caused by adverse weather, and radioactive dust will be confined inside.

The confinement is an enormous arch - with a span of 260 metres and height of 100 metres – and will enclose the existing “sarcophagus” and its radioactive contents for a period of a minimum of 100 years. It is being assembled away from unit 4 to limit workers’ radiation exposure . The arch-shaped confinement will be erected and slid into position over the old shelter. Once in place, safer working conditions will enable the deconstruction of unstable parts of the shelter and future dismantling and waste management activities.

Donor commitments

Today the EBRD-managed international assistance programmes in Chernobyl have received more than EUR 1 billion, which is delivered through the Chernobyl Shelter Fund (CSF) and the Nuclear Safety Account (NSA) respectively. Both programmes have been developed and carried out in close co-operation with the Ukraine authorities, whose commitment and support continue to be indispensable.