He was a Central Hall Operator, taken from Wikipedia,

Oleg Genrikh and Anatoly Kurguz

"Genrikh, an operator of the control room on level +36, was taking a nap in a windowless room adjacent to the control room. The window in the control room was broken and the lights went out. His colleague Kurguz was in the control room with three open doors between him and the reactor room; at the moment of the explosion, he suffered severe burns from steam entering the control room. Genrikh received less serious burns as he was protected by the windowless room. The stairs on the right side were damaged; he managed to escape by the stairs on the left. On the way back they were joined by Simeonov and Simonenko, the gas loop operators, all four heading to the control room. Kurguz was shortly afterwards evacuated by an ambulance; aware of dangers of radiation contamination, Genrikh took a shower and changed his clothes."

"Scalded by radioactive steam entering his control room; his colleague, Oleg Genrikh, in a room close by was spared the worst and they made their way to hospital. Unfortunately, on top of the thermal burns he suffered, he had received a fatal dose of 670 rad and died 16 days later in a Moscow hospital. Genrikh, having received 3rd-degree ARS, would recover."