Information regarding the levels of radioactive materials in defined process streams of nuclear power plants is necessary to evaluate plant performance, to provide at an early stage information on possible radioactive releases, and to allow plant operators to take actions to control these releases. This International Standard provides criteria for the design, selection, testing, calibration and functional location of equipment for the monitoring of radioactive substances within plantprocess streams during normal operation conditions and anticipated operational occurrences. IEC 60768 is only applicable to continuous in-line or on-line measurement, i.e. monitors of which the detector measures radioactivity by being positioned in the process stream (i.e. immerged in) or adjacent to the process stream (i.e. viewing straight through a pipe or tank). It does not apply to monitors of which the detector measures a representative proportion of the stream at some remote location (sampling assembly), which are within the scope of IEC 60861. IEC 60768 is only applicable to monitors for normal and incident conditions. Process stream radiation monitoring equipment for accident and post-accident conditions are within the scope of IEC 60951-4.