Work to build a permanent shelter to secure the exploded reactor at the Chernobyl nuclear power plant in Ukraine reached a key milestone on Tuesday when workers raised the arched section that will cover the destroyed unit.
The explosion at reactor No. 4 at the Chernobyl power plant in the early hours of April 26, 1986, sent radioactive fallout into the atmosphere that spread from the Soviet Union across Europe. It remains the world’s worst nuclear accident.
The structure raised to its full height on Tuesday will be part of the so-called New Safe Confinement, a colossal arch-shaped structure that will be slid on rails over the existing sarcophagus covering the reactor.
During the initial lifting operation, about 5,000 tonnes of steel were raised to a preliminary height of up to 22m, according to the European Bank for Reconstruction and Development, which is leading the project.
Bank president Suma Chakrabati called Tuesday “a very significant milestone, which is a tribute to the ongoing commitment of the international donor community, and an important step towards overcoming the legacy of the accident.”
When it is finished in 2015, the structure will weigh 20,000 tonnes and span 257m.
The overall shelter project is budgeted at 1.54 billion euros (US$2 billion) — 1 billion euros for the structure itself — and much uncertainty lies ahead. One particular concern is dismantling the plant’s chimney, which must be taken down before the shelter is put in place. The chimney is lined with radioactive residue that could break up and enter the atmosphere as it is taken apart.
Laurin Dodd, managing director of the shelter project management group, said some sort of fixative would have to be applied to the chimney’s interior.
“This is one of the most challenging parts, because it’s an unknown,” he said.
Other possible delays could come if excavations for the shelter’s foundation uncover radioactive waste or even buried machinery. Dodd said other excavations unearthed several bulldozers and cranes that had to be decontaminated.
Even when the shelter is in place, the area around the reactor building will remain hazardous. The shelter is aimed only at blocking radioactive material from escaping when the reactor is being dismantled; it won’t block radiation itself.
Chernobyl is only about 100km from Ukraine’s capital, Kiev, and lies close to the borders with Russia and Belarus. The area around the plant is still very contaminated and is designated as a depopulated “exclusion zone.”
Two workers were killed by the 1986 explosion and 28 rescuers and staff died of radiation exposure in the next months. Tens of thousands of people needed to be evacuated and fears remain over the scale of damage to people’s health.