The night shift had very limited time to prepare for and carry out the experiment. Anatoly Dyatlov, deputy chief-engineer of the entire Chernobyl Nuclear Power Plant, was present to supervise and direct the experiment; as he out-ranked all other supervisory personnel present, his orders and instructions overrode any objections of other senior personnel present during the test and its preparation. Serving under Dyatlov, Aleksandr Akimov was chief of the night shift, and Leonid Toptunov was the operator responsible for the reactor's operational regimen, including the movement of the control rods. Toptunov was a young engineer who had worked independently as a senior engineer for approximately three months.