The explosion at the Chernobyl nuclear plant on 26 April 1986 has left a lethal legacy that will endure for a thousand years. The catastrophe at Chernobyl is the worst accident in the history of commercial nuclear power, and the environmental consequences have prompted an international response. Co-ordinating this effort and planning for the future are the challenges facing the Chernobyl Shelter Fund’s implementation plan as it moves to the critical second phase.
The explosion of the reactor core of Chernobyl Unit 4 in 1986 sent up tons of radioactive material into the atmosphere. Serious contamination affected the population and vast areas of the Ukraine, Belarus and Russia. Within days the wind had spread radionuclides over much of Europe and beyond. This latter contamination, however, represents only a few per cent of the nuclear inventory of Chernobyl Unit 4. In excess of two hundred tons of uranium and nearly a ton of radionuclides, comprising 80 per cent plutonium, remain within what is left of the reactor.
In the months immediately following the disaster the authorities in the Ukraine and Russia raced to build a shelter over the wrecked reactor. The urgency of the work and the impossibility of direct access to the reactor meant that the shelter could not be built to conventional building standards. The shelters structure subsequently deteriorated with the roof and other elements threatening to collapse.
In the years after the accident, although numerous technical solutions were offered for the precarious structure, none were deemed suitable because of the uncertainties associated with the condition of the shelter. In early 1997, on the initiative of the European Union, Ukraine and the United States, the Shelter Implementation Plan (SIP) to protect people and the environment from the enormous radioactivity remaining in the reactor, some 95% of its original inventory, was developed. The Chernobyl Shelter Fund (CSF) was set up in December 1997 to fund the SIP.
The CSF is administered by the European Bank for Reconstruction and Development (EBRD) and overseen by the Assembly of Contributors representing more than 20 countries and the EU. It is planned that over the eight to nine year project the shelter will be transformed into a stable and environmentally safe system that will last for many decades. The entire project is estimated to cost US $768 million and represents the largest venture ever undertaken by the EBRD. The value of the programme can be better appreciated if the costs of equivalent Western labour and materials are used, in which case a figure of US $5 billion would be more accurate.
According to Vince Novak, Head, Chernobyl Shelter Fund and Director of the EBRDs Nuclear Safety Unit, The project is unique in terms of the level of radioactivity and uncertainties involved. There was considerable risk to the European Banks reputation if the Chernobyl project did not go well.
Investigative and engineering tasks, the main objective of Phase 1 of the SIP, are now substantially complete. Urgent repairs to the reactors ventilation stack and the shelters roof beams have been carried out. By the end of this year the Shelter stabilisation concept and the strategy of confinement will be finalised and integrated, and the transition to Phase 2 completed.
To facilitate the transition, Det Norske Veritas was commissioned by the EBRD to carry out a comparative risk assessment of five alternative industrial structural models for Phase 2. Using available information, uncertainties which dissimilarly affect the choice of the industrial structural model were identified and quantified relative to the cost and schedule objectives.
DNV used part of its Project Risk Management (PRM) methodology to conduct the work. The resulting activity model was then fed through a Vite Project simulation. DNV had earlier contributed to the research efforts at Stanford University which led to the formation of Vite. Finally, a definitive scenario was produced to determine the relative ranking of each industrial structural model. Commenting on the overall effort Vince Novak said, DNVs approach focused on issues of interface and interaction in large projects. This analysis was very helpful.
Funding for Phase 2 of the Shelter Implementation Plan has been secured and an industrial structural model chosen. It was expected that Russia would contribute to the funding but in the end decided not to do so. Russian design institutes, nevertheless, have been encouraged by the Russian government to co-operate with the SIP.
A decision over the nature of the stabilisation and confinement work will be taken before the end of 2000. This is the most important contract, and further project definition will be necessary to prepare it for international tender. A cost-benefit analysis will identify which alternative proves to be the optimum.
To assist the EBRD and the Assembly of Contributors an International Advisory Group was set up in July 1998. The Group provides independent technical advice and has been actively involved in all the recent strategic decisions. Pal Bergan, DNVs Head of Corporate Research & Development and a member of the International Advisory Group, says The project has a unique composition involving technical, economic, political and ethical dimensions, with radiation as well as monetary budgets central to the decision making. The complexities of the Chernobyl legacy are a warning to the nuclear industry around the world.
The international co-operative effort and oversight of this project is an impressive testimony to what can be achieved in the most critical of circumstances. Indeed, the processes deployed to address the uncertainties surrounding the Chernobyl reactor site and the identification of solutions should encourage those involved in less complex projects that seemingly intractable problems can be solved.
Date: 2000-12-15