Largest radioactive exclusion zone

The largest area to be closed off to the public following a nuclear accident is the Chernobyl Nuclear Power Plant Zone of Alienation, an area of approximately 2,600 km2 (1,003 sq miles) that surrounds the site of the 1986 Chernobyl disaster in northern Kiev Oblast, Ukraine.

The exclusion zone was first established on 2 May 1986 as a mandatory evacuation area extending 30 km (18.6 miles) from the crippled power plant. It was later expanded in 1997 to include other areas farther to the west that had been contaminated by radioactive material carried by the prevailing winds. Beyond these areas lies a semi-abandoned region where residents were given the option to evacuate, but were not required to do so.

The Chernobyl Zone of Alienation comprises two distinct areas. The original exclusion zone, which has manned checkpoints and patrols keeping unauthorized visitors out, and the post-1997 expansion, which is uninhabited but not as actively guarded. The inner part of the exclusion zone covers an area of around 2,400 km2 (926 sq miles). The Chernobyl Zone of Alienation (minus the industrial and urban areas close to the plant itself) forms the Chernobyl Radiation and Ecological Biosphere Reserve, a 2,270-km2 (876-sq-mile) nature reserve with strict limitations on human settlement and activity.

As the Chernobyl power plant was located close to the border between the Ukrainian and Belarussian SSRs, the original 30-km (18.6-mile) evacuation zone also included a large area of what is now Belarus. This northern portion of the evacuation area is today the Polesie State Radioecological Reserve, a less-heavily restricted (though still largely uninhabited) exclusion zone that covers an area of 2,160 km2 (833 sq miles). This means the total area that has been either made off-limits to the public or placed under severe restrictions as a result of the Chernobyl disaster is around 5,760 km2 (2,223 sq miles).

No other exclusion area comes even close to the size of the Zone of Alienation. The exclusion zone around the Fukushima Daiichi plant in Japan (site of the 2011 Fukushima nuclear accident) covered 371 km2 (143 sq miles) as of 2018, and the East Ural Nature Reserve in Russia (an area that was downwind of the 1957 Kyshtym disaster) covers roughly 166 km2 (64 sq miles). The largest non-nuclear exclusion zone is Zone Rouge, which encompasses the toxic and explosive-filled sites of several World War I battlefields in northern France. In the immediate aftermath of the war, Zone Rouge comprised 1,200 km2 (463 sq miles) of land that was off-limits to the public.