Nuclear power: Control-room design: Lessons from TMI: Improved instrumentation plus computer-based decision aids under development should help minimize the potential consequences of accidents

Control-room operators in the Crystal River nuclear power plant in Gainesville, Fla., were going about their routine tasks on Feb. 26, 1980, when warning lights began to flash. It was 2:23 p.m. A malfunction had led to the loss of most of the important control-room instruments needed for operator action. Wiihin a minute, the nuclear reactor shut itself off, as it had been designed to do in an emergency. As during the 1979 Three Mile Island-2 accident, the power-operated relief valve was stuck open, and coolant water was escaping into the containment building. Unlike TMI, however, the potentially dangerous situation did not develop into a significant accident. Even though much of the instrumentation malfunctioned, the operators were able to shut a blocked valve and stop the loss of reactor coolant through the relief valve. By 3:15 p.m. they had brought the reactor to a shutdown.