Their mission: reconnaissance on the roof of Power Unit 3. After robots failed due to extreme radiation, humans were sent in. #Zhelezniakov’s team mapped the deadly zones, allowing other liquidators to know exactly where they could survive for only a few precious seconds. In the most contaminated spots, radiation reached 13,800 roentgens—a lethal dose. Only two members of the group survived: #Oleksandr and #Holtsman.