On-line monitoring of the IPR-R1 TRIGA reactor neutronic parameters

The on-line monitoring of several new process variables of the IPR-R1 TRIGA Reactor of the Nuclear Technology Development Center – CDTN became possible after the data acquisition and processing system implementation and the installation of one instrumented fuel rod in the reactor core. Several neutronics and thermo-hydraulics parameters are now registered, such as the operation power, the reactivity insertion in the core, the control rod position, the fuel and the water temperatures, and so on. Since the inherently safe operation of a reactor is dependent on the reactivity control, it is essential to have information on this parameter over many different temperature ranges. The fuel elements have been designed to provide a significant negative prompt temperature coefficient that allows safe reactor operation. The developed monitoring system gives the reactivity worth of the control rods, when the rod considered is inserted into the core or withdrawn from it, and also the loss of reactivity during the reactor operation. This paper describes the methodology and the results found with the on-line monitoring of the reactivity behavior of the IPR-R1 TRIGA Reactor.