Abstract: A nuclear reactor radioactive emission monitor measures quantities of a selected radioactive component in a stream of radioactive fluid. The device comprises two fluid paths with each path having a filter to absorb a radioactive component while passing the remainder of the stream of radioactive fluid; each fluid path also has a detector to measure the level of radioactivity emitted by the retained radioactive component in the two filters. A valve alternately directs the stream of fluid from the first fluid path to the second fluid path while simultaneously purging the remainder of the fluid from the non-selected fluid path. The output of one or more of the detectors is integrated as a function of time to indicate any increase in the radioactivity emitted by the radioactive component retained by the filter.

Abstract: A method and means of non-invasively determining the liquid level and density in a nuclear power reactor pressure vessel is disclosed. In general the method consists of detecting neutron levels external of the pressure vessel at least at positions adjacent the bottom of the fuel core, the center of the fuel core and the top of the fuel core; and the detected neutron level signals are directed to monitoring means.The detecting means may comprise fission chambers and monitoring means may comprise simple electric meters.