The sarcophagus entombed over 200 tons of highly radioactive corium lava 30 tons of highly contaminated dust and 16 tons of exposed uranium and plutonium.
A dozen or so operators dressed in military uniform were almost entombed by the rows of instruments, as though they were crouching inside battlefield trenches.
When finished, the 250-meter-wide steel arch is to slide 200 meters to cover the sarcophagus hastily built after the 1986 explosion to entomb Chernobyl Reactor Number 4.