Monitoring Reactor Vessel Liquid Level with a Vertical String of Self-Powered Neutron Detectors

Changes in in-core self-powered neutron detector signals, recorded during a nuclear loss-of-coolant accident (LOCA) simulation, have been correlated with liquid level changes that occurred during the core uncovery and recovery events. The correlations indicate that these detectors can be used to monitor reactor vessel liquid level during a LOCA. A display and alarm system using these detectors to provide reactor operators with an indication of a core uncovery and subsequent thermal excursion and with a means to measure the effectiveness of LOCA recovery procedures is described.