edit: Your figure is for the exclusion zone. That is the area currently unfit for human habitation, and is defined as the area in a radius 30km around the plant. The area that was, and still is contaminated by the accident is significantly larger than the exclusion zone.
Comments
According to the NY Times[1] the area, as designated by the Ukraine parliament is 15,000 square miles. Switzerland is 15,937 square miles.
[1] http://www.nytimes.com/2011/03/20/weekinreview/20chernobyl.h...
edit: Your figure is for the exclusion zone. That is the area currently unfit for human habitation, and is defined as the area in a radius 30km around the plant. The area that was, and still is contaminated by the accident is significantly larger than the exclusion zone.