High levels of radiation resulting from the Chernobyl disaster are detected at Forsmark Nuclear Power Plant in Sweden, leading Soviet authorities to publicly announce the accident.

On 26 April 1986, reactor 4 of the Chernobyl Nuclear Power Plant, located near Pripyat, Ukraine, exploded. With dozens of direct casualties and thousands of health complications stemming from the disaster, it is one of only two nuclear accidents rated at the maximum severity on the International…