Review of in-core power distribution measurements: technical status and problems

This report reviews the technical status and problems associated with the on-line measurement of core power distributions in nuclear reactors. The need for and significance of the various measured and inferred quantities relating to power distribution are defined. The current status of the instrumentation and data acquisition systems supplied by the four domestic LWR vendors is described. The techniques employed with each of these systems to process the measurements on-line and to infer the different power distribution parameters are also documented. Sources of uncertainty in the inferred power distribution and problems with the measurement systems are identified and the impact which these may have on plant operations is enumerated. Examples are cited where plant operation has been restricted for these reasons. The report concludes with a summary of areas where additional research and development might be beneficial