13 1955 Special Power Excursion Reactor Test The SPERT experiments (I-IV) regularly pushed reactors far beyond normal safety limits in order to discover what the normal safety limits were.The tests used four increasingly sophisticated safety testing vessels to study the behavior of reactors when their power level changed rapidly. By deliberately moving control rods, the SPERT tests offered insight into fuel plate design, core configuration, coolant flow, temperature, pressure, reflectors, moderators, and void and temperature coefficients. Reports and recommendations were sent to the agencies responsible for establishing licensing requirements for commercial water reactors around the world. “ We were to explore the limits of the reactor’s behavior, and it was expected that we would test the reactors to destruction.” — Warren Nyer, ANL-West