Patent Number: 054224926
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention pertains to the calibration of criticality detectors for nuclear fuel manufacturing plants. Referring to FIG. 1, the present invention is used in conjunction with a criticality detector 10. The present invention comprises a connector 12, which is an alignment fixture, within which the detector 10 is positioned during use. A steel measuring tube or rod 14 is connected to the connector 12. Rod 14 has a plurality of graduations or calibrations 16 marked on an outer surface. A radiation protective holder or shield 22 is aligned directly beneath the detector 10 and contains a radiation source 20 which is provided by a radiation source extracting rod 24 movable within a guide tube 26 for providing the radiation source 20 within the shield 22. Measuring rod 14 is aligned parallel with the axis of the radiation source 20. A guide, generally designated 30, which is made of a nylon material, is movably connected to the measuring rod 14 and connected to the holder 22. Guide 30 comprises an upper guide section 32 spaced apart from a lower guide section 34. Sections 32 and 34 are joined by connecting bars 36 and 38. As shown in FIGS. 2 and 3, connecting bar 38 has key holes 37 bored therethrough for allowing a key hole mate or bolt 39 to connect connecting bar 38 to the radiation source holder 22. A thumb screw and toggle pad device 31 is operatively connected with the guide 30 at the lower section 34 for moving the guide 30 and holder 22 with radiation source 20 along the measuring rod 14. Upper section 32 of the guide 30 is aligned in the same horizontal plane as the radiation source 20 for providing a calibration measurement 3 which is indicated on the measuring rod 14 at 5. As shown in FIG. 1, when the holder 22 is placed beneath the detector 10, the distance 3 between the source 20 and the detector 10 can be adjusted based on calibration requirements and source strength. At this time, with the present invention raised into position in order to maintain the proper radiation field at the detector 10, adjustments to the system electronics can be made as required. FIG. 4 illustrates the present invention used in conjunction with a mounted detection system 10 and a wall 2. The present invention reduces the amount of radiation exposure to operating personnel. The present invention also eliminates the use of various tools which were previously used to calibrate detectors. The present invention provides for efficient savings in time by allowing the calibration to be performed while the detectors are in place, and therefore, mitigates the possibility of damage to the detectors during handling. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.