In the 25 years since the explosion at Chernobyl, it’s been a constant struggle to confine radioactive materials at the site. After years of ad hoc efforts, work has started on a massive $2 billion structure designed to seal the site for 100 years. The ruins will be dismantled with remote-controlled equipment, preparing them for permanent storage at a future site. Technology Review looks at what it takes to clean up a nuclear disaster over the years.
The French consortium Novarka will construct a 100-meter-tall structure near the ruined reactor building (in background), then slide it over the building to encase it. The rebar cage in the foreground will form the basis for a concrete foundation that will support one of 19 towers used to lift prefabricated parts into place during construction of the containment building.
In the months after the explosion, Soviet authorities organized a construction project that involved remotely operated cranes and almost 100,000 workers. They erected a temporary concrete-and-steel structure to enclose the reactor, even as experts speculated on the possibility of another explosion. The red walls seen here beneath the looming cranes are the beginnings of the structure, which came to be called the sarcophagus.
The explosion scattered highly radioactive chunks of graphite from the reactor’s core over the roof of an adjacent building. Here, a worker scoops up a piece of the hazardous material. Protective lead sheets are tied to his clothes. To avoid radiation poisoning, workers limited their shifts to less than a minute each.
Light streams through gaping holes in the makeshift sarcophagus in this view from inside the ruined reactor building. A project undertaken to seal these holes against escaping radiation, and to prop up the walls of the sarcophagus, was finished in 2008. The ruins inside the sarcophagus remain vulnerable. If they collapse, it could become impossible to move buried radioactive materials to a permanent storage facility.
The last Chernobyl reactor, number 3, wasn’t shut down until 2000. The 20,000 containers of spent fuel that had accumulated over the years must be kept cool to avoid a fire that could release radiation. Today, most of the fuel is stored in water under the metal plates in the facility seen here. Tubes containing the fuel are visible in the foreground. (Some of the fuel is still stored in pools at the reactors.)
As part of the remediation project, the fuel will be moved into more stable steel-and-concrete casks, which will be slid into the structures shown here. The casks are meant to store fuel safely for 100 years.
Workers at Chernobyl wear protective equipment and clothing, even though most of the radiation is contained within the “sarcophagus”—especially now that gaping holes in the sarcophagus have been patched. Soil in the area is contaminated and had to be sorted and stored after it was dug up during the first stages of construction of the new containment structure.