SYSTEM FOR ULTRASONIC MONITORING OF A SPACE ABOVE THE CORE OF A NUCLEAR REACTOR

摘要

The invention relates to nuclear engineering and can be used for monitoring the state of a space above the core of a nuclear reactor containing a liquid metal coolant. The operating principle of an ultrasonic monitoring system is based on exciting, and obtaining in response, ultrasonic signals which are reflected from structural elements located in a space (a gap being monitored) between the top level of the heads of fuel rod assemblies and the bottom level of rotating plugs of a nuclear reactor that is cooled by an opaque coolant, for example liquid sodium. This system serves for detecting, in the space being monitored (gap being monitored), obstacles to rotation of the rotating plugs during refuelling operations. To increase the reliability of detecting obstacles in the space being monitored above the core and to determine the location of said obstacles, the ultrasound reflector is configured in the form of a ring on which at least one row of vertical cylindrical rods is arranged, the ring is attached to one of the thermal screens surrounding the reactor core, preferably one proximate to the nuclear reactor vessel, wherein the spacing at which the cylindrical rods are arranged in the row is less than the spacing between the assemblies.