| 摘要 |
PURPOSE:To permit measurement of a velocity of flow by making use of the component of <24>Na by disposing two pieces of detector blocks contg. neutron detector groups, adding the detection signals obtd. from the respective blocks and calculating transfer time. CONSTITUTION:The detecting blocks 4, 4 spaced at a distance L are disposed on the outer circumference of a heat insulating material 3 provided on the outer circumference of a piping 2 in which a coolant or sodium 1 flows. The blocks 4 are disposed equally at every prescribed interval with the neutron detectors 5... around the piping. The detector signals of the detectors 5... in the respective blocks 4 are summed and are inputted to a correlative analysis part. The transfer time tau of the sodium 1 contg. <24>Na between the two blocks is determined by the respective prescribed equations according to whether the component (x) by the influence of <24>Na, etc., and the component (y) by the neutrons arriving directly from the furnace core exerting a simultaneous influence to the above-mentioned sum signal are in a correlative relation or not. The velocity of flow L/tau is then determined in a flow rate calculation part and further the flow rate is calculated from the determined velocity of flow.
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