The design of the J-type neutron flux distribution measurement system

This paper introduces the design of a J-type aeroball system that the tube penetrates the lateral wall of reactor pressurized vessel (RPV), then immed iately goes down to the vessel bottom and then goes up through the lower co re support plate into the reactor core. Some experimental results related t o gas flowing within a thin tube are presented in the paper, such as the ga s friction drag coefficient on the ball's way and etc. From theoretical and experimental viewpoints, the feasibility of the system is proved in pneuma tic holding-up and beta measurement aspects. In order to ensure an enough r atio of signal to noise, the maximum distance between two measuring points in water reactors is given. The paper gives out the measuring number per tw o-assemblies width N-i = Int(n(i)/2 + 0.51), which is the accuracy relation between the number of fuel assembly and the minimum one of measuring point to only reconstruct 2D neutron flux distribution completely by the measure d data. (C) 1999 Elsevier Science S.A. All rights reserved.