Patent Number: 053655540
Section: description

The probe comprises a cage-like inner support structure 10 which houses and supports the instrumentation of the probe. The support structure 10 is attached to a pair of inner perforate end plates 11, 12 with an array of dummy fuel pencil stubs 13 which are attached to actual fuel bundle end plates 14, 15. The outer periphery of the probe consists of an array of active fuel pencils 16 extending longitudinally between the end plates 14, 15 and connected thereto at their ends. Thus the probe can be configured to simulate a fuel bundle of the reactor in which it is to be used. The instrumentation includes sensors each of which is responsive to a physical parameter to be measured. In the illustrated device there is a mechanical pressure sensor 17 responsive to fluid pressure and an end plate displacement sensor 18, the latter being in the form of a rod which is connected to the end plate 15 and extends longitudinally therefrom. The instrumentation may include other sensors (not shown), each being responsive to a respective physical parameter to be recorded. Each sensor carries a scribe 19, 20, or equivalent writing device which cooperates with a recording device for recording the measurements of the parameters over time. In the illustrated embodiment of the invention the recording device is a rotary drum 21, but it may take any other suitable form such as a rotary disc or a travelling tape. The drum 21 is driven at a constant speed to provide a time base. As shown, the device for rotating the drum 21 comprises a rotary shaft 22 carrying an impeller 23 which is responsive to the fluid flow along the fuel channel so as to rotate the shaft 22. The shaft 22 serves as the input shaft of a speed reducing mechanism 24, the latter having an output shaft 25 on which the rotary drum 21 is mounted. Since the fluid flow in the reactor fuel channel is normally held constant, the drum 21 is rotated at a constant speed. In certain applications, however, where the fluid flow may not be constant, the speed of the drum can be kept constant simply by governing the speed of the impeller to the speed corresponding to the lowest flow rate expected. In order to clarify the structure of the probe and to show essential components, certain elements have been omitted from the drawing. In particular, a part of the inner and outer rings of fuel pencils has been omitted to reveal the instrumentation. The sensors, scribes, recording drum and gear reducing mechanism are conventional, and are supported within the cage-like support structure. The drum 21 and the speed reducing mechanism 24, which may be a gear reduction train, are arranged coaxially within the cage, one end of the rotary shaft 22 being journalled in a bearing mounted centrally on the end plate 11.