Thirty years after the Chernobyl nuclear accident, there’s still a significant threat of radiation from the crumbling remains of Reactor 4. But an innovative, €1.5 billion super-structure is being built to prevent further releases, giving an elegant engineering solution to one of the ugliest disasters known to man.
Since the disaster that directly killed at least 31 people and released large quantities of radiation, the reactor has been encased in a tomb of steel-reinforced concrete. Usually buildings of this kind can be protected from corrosion and environmental damage through regular maintenance. But because of the hundreds of tonnes of highly radioactive material inside the structure, maintenance hasn’t been possible.
Water dripping from the sarcophagus roof has become radioactive and leaks into the soil on the reactor floor, birds have been sighted in the roof space. Every day, the risk of the sarcophagus collapsing increases, along with the risk of another widespread release of radioactivity to the environment.
Thanks to the sarcophagus, up to 80% of the original radioactive material left after the meltdown remains in the reactor. If it were to collapse, some of the melted core, a lava-like material called corium, could be ejected into the surrounding area in a dust cloud, as a mixture of highly radioactive vapour and tiny particles blown in the wind. The key substances in this mixture are iodine-131, which has been linked to thyroid cancer, and cesium-137, which can be absorbed into the body, with effects ranging from radiation sickness to death depending on the quantity inhaled or ingested.