We conducted a preliminary study to investigate how an immersive 3D environment based on novel technology can be used in simulator studies in nuclear domain. Our ultimate aim is to better understand the cognitive processes in achieving an overview of the nuclear process in a virtual reality control room (VR CR). The VR-environment was created by importing 3D-models into the Unity design environment. A novel headset was used offering a blend between the central high-resolution display and a larger lower-resolution context display. Two operator crews participated in the main test, and one crew for the pilot test. In brief simulated incidents and accidents the operators had to detect a fault and start to manage it; in a longer run, a sudden fire in the CR was simulated, forcing the crew to move to the Emergency CR. After each trial, the operators were interviewed and asked to describe what they had done during the trial, what information they had used and what hypothesis they had made about the cause of the fault. The results showed that the crews were able to successfully complete their tasks and manage the incident/accident, even though the development of the VR CR is still in progress.