Testing and implementation of a Radcal-based reactor vessel monitoring system for inadequate core cooling determination

Technology for Energy Corporation and Scandpower, Incorporated, in conjunction with Arkansas Power and Light Company have developed a system for monitoring the coolant inventory status within a reactor vessel during loss-of-coolant accidents (LOCAs). The sensor portion of the system is a single rod with multiple heated-junction thermocouple sets. The patented Radcal probe is used to monitor coolant inventory and temperature above the reactor core and both heat transfer conditions and shutdown power in the core. The TEC/Radcal system can also provide core-exit thermocouple, submargin coolig, and core power monitoring functions. Radcal was originally developed and tested as a local power instrument by a group of eight U.S. and European utilities and had over 400 sensor years in reactors of actual experience before Reactor Vessel Level Inventory System (RVLIS) development began. Extensive testing during simulated LOCAs has demonstrated the ability of the Radcal probe to track coolant conditions and collapsed level over a full range of small break accidents. Arkansas Power and Light and Unit 2 will install the first TEC/Radcal System in 1985