UNITED NATIONS (Sputnik) — The April 26, 1986 Chernobyl disaster is widely considered the worst nuclear accident at a civilian power plant.
"I particularly commend the governments of Belarus, the Russian Federation and Ukraine for their joint work," Ban said in a statement published on the UN website.
A series of chemical explosions blew the top off the Chernobyl reactor, which had no containment structure. Today the reactor is encased in a thick concrete shell.
An international outcry over a two-day delay before authorities publicly announced the accident is credited in part with inspiring an era of glasnost (openness) initiated by then Soviet leader Mikhail Gorbachev.