Chernobyl Nuclear Disaster

Abstract

Abstract On April 26, 1989, an explosion and fire at the Chernobyl nuclear power plant in Ukraine released an estimated 1.4 × 10 18 Bq of ionizing radiation into the surrounding atmosphere. Acute health effects were noted in 237 highly exposed emergency workers, 134 were treated for acute radiation syndrome, and 28 died. An estimated 600 000 people were involved in the recovery and cleanup operations after the disaster and about 116 000 nearby residents were evacuated from the area, which became known as the Chernobyl exclusion zone . Areas of the countries surrounding the plant—Belarus, the Russian Federation, and Ukraine—are considered “contaminated” based on cesium‐137 measurements. On the basis of these measurements, about 3% of the former Soviet Union is considered contaminated by cesium‐137 densities greater than 37 kBq m −2 . Radioactive material spread throughout the Northern Hemisphere, but radiation doses to populations outside Ukraine, Belarus, and the Russian Federation were relatively low and showed large differences depending on the occurrence of rainfall. Thyroid cancer in children exposed at a young age to Chernobyl is widely accepted as causally associated with the Chernobyl disaster. Other than childhood thyroid cancer, no other health effects have been considered related to Chernobyl exposure, but recently data on emergency workers may indicate some increase in morbidity and mortality caused by leukemia and solid organ cancer. Large areas of Ukraine, Belarus, and the Russian Federation are still excluded from agricultural uses, and other environmental uses are subject to strict controls. In the years ahead, a safer containment structure for the residual risk of the melted nuclear fuel still inside the quickly built “sarcophagus” or “shelter object” will need to be constructed. Chernobyl continues to serve as a model of international collaboration to assess and manage risks to human health and to the environment from the world's largest nuclear disaster.