Ukraine ousted Khrushchev and became the Soviet leader from 1964 to 1982. Many prominent Soviet sports players, scientists, and artists came from Ukraine. On 26 April 1986, a reactor in the Chernobyl Nuclear Power Plant exploded, resulting in the Chernobyl disaster, the worst nuclear reactor accident in history. This was the only accident to receive the highest possible rating of 7 by the International Nuclear Event Scale, indicating a "major accident", until the Fukushima Daiichi nuclear disaster in March 2011. At the time of the accident, 7 million people lived in the contaminated territories, including 2.2 million in Ukraine. After the
Peaceful nuclear explosion the use of national technical means, the treaty states that information and access to sites of explosions will be provided by each side, and includes a commitment not to interfere with verification means and procedures. The protocol to the PNE Treaty sets forth the specific agreed arrangements for ensuring that no weapon-related benefits precluded by the Threshold Test Ban Treaty are derived by carrying out a nuclear explosion used for peaceful purposes, including provisions for use of the hydrodynamic yield measurement method, seismic monitoring, and on-site inspection. The agreed statement that accompanies the treaty specifies that a "peaceful application" of