The most pertinent information regarding safety of research reactors comes from specific test data developed in experiments at the National Reactor Testing Station (now the Idaho National Engineering Laboratory) SPERT facilities In Idaho, and at the GA TRIGA facilities in San Diego, California. An analysis of these data clearly indicates that the TRIGA reactor has the greatest inherent safety of any available megawatt level research reactor. The safety of the TRIGA is due to the large prompt negative temperature coefficient of reactivity, which is an intrinsic characteristic of the standard U-Zr-H fuel. The TRIGA temperature coefficient acts independently of any external controls to assure safe and reliable self-shutdown in the event of an accidental reactivity insertion.