Review of proposed instrumentation for measurement of inadequate core cooling in LWRs

Recent events in the nuclear industry have resulted in an increase of attention and emphasis toward the development and use of instrumentation systems to measure the approach to inadequate core cooling conditions in light water reactors. A large number of instrumentation concepts and systems have been proposed for this purpose. Of the systems which have actually been constructed, few have been thoroughly tested. The various concepts and systems are reviewed and their status, capabilities, and limitations briefly discussed. Two instrumentation systems based upon the use of differential pressure measurements and heated junction thermocouples have been developed and partially tested by Westinghouse and Combustion Engineering, respectively. As the NRC has recently recommended the generic approval of these two systems, many utilities are expected to pursue the use of thee systems to satisfy NRC requirements