Object "Klivazh"
1979 CE.
Shown on the map at 48.213°, 38.282°.
Klivazh is the site of an underground peaceful nuclear explosion in the Soviet program of Nuclear Explosions for the National Economy. The event took place in the Donetsk Oblast of the Ukrainian SSR on September 16, 1979. The site flooded with underground waters in 2018 after Russian military occupation during Russo-Ukrainian war, with a risk of radiological pollution of drinking water in the area.
Text from the Wikipedia article Klivazh, licensed CC BY-SA 4.0.