Patent Number: 06240153&
Section: description

DETAILED DESCRIPTION OF INVENTION As shown in FIG. 1, the present invention is an apparatus 10 for cleaning large reactor studs 20 which are used to secure reactor heads on nuclear reactors. The present invention overcomes many of the problems of the prior art by providing an apparatus 10 that allows reactor studs 20 to be cleaned in the vertical position. Additionally, the present invention provides for cleaning multiple reactor studs 20 within apparatus 10 thereby increasing the efficiency of the cleaning process. Further, apparatus 10 of the present invention provides for efficient cleaning of reactor studs 20 using both a mechanical cleaning process and cleaning solvents which are recycled and reused. Apparatus 10 is a self-contained unit having a housing 12 that encloses sealable compartments 14. As shown, the housing 12 encloses two or more sealable compartments 14 each of which is capable of enclosing a reactor stud 20 for cleaning. However, the apparatus of the present invention can be constructed to have multiple sealed compartments for individually cleaning multiple reactor studs. Alternatively, the apparatus of the present invention can be constructed with a single sealable compartment 14 for cleaning a single reactor stud 20. The sealable compartment 14 has a base 16, vertical walls 18, and a top side covering 22. Top side covering 22 has a port 24 for each compartment 14 which allows reactor stud 20 to be lowered into sealable compartment 14 in order to be cleaned. Each port 24 has a port covering 46 that is hinged over port 24 and seals compartment 14 when in the closed position. As can be seen, reactor stud 20 is lowered into sealable compartment 14 such that it longitudinal axis remains in a substantially vertical position. The base 26 of reactor stud 20 is mounted on a turntable 30 keeping the longitudinal axis of stud 20 in the vertical position. Turntable 30 not only provides a mounting support for mounting reactor stud 20, but it also provides for the rotation of the stud 20 about its longitudinal axis. With the present invention it has been found that the ability to set reactor stud inside apparatus 10 while keeping its longitudinal axis in a vertical direction is a significant advantage over the prior art. Reactor stud 20 can be lifted out of its original position using a crane or other device by attaching the crane to lifting connection 28. When lifted by the crane in such manner, reactor stud 20 will naturally hang with its longitudinal axis in the vertical axis. Prior art cleaning machines required additional handling to place reactor stud 20 with its longitudinal axis in the horizontal direction. The present invention eliminates this unnecessary handling by allowing reactor stud 20 to be lowered through port 28 and directly into sealable compartment 14 of apparatus 10. This decreased handling significantly decreases safety risks associated with cleaning reactors studs 20. As shown in FIG. 2, compartment 14 also contains a cleaning mechanism, preferably brushes 36, rotatably mounted on a brush support 38. Brush support 38 has a shaft 40 that when driven by motor 42 rotates brushes 36 to clean reactor stud 20. Preferably, brushes 36 are rotated in the reverse direction from which turntable 30 rotates studs 20 to enhance cleaning. Brush support 38 can be moved from a first position in which shaft 40 is placed in notch 44 to a second position where shaft 40 extends through port 24. Brush support 38 is placed in the first position to prevent the brushes from interfering with the initial placement and setting of reactor stud 20 as it is lowered through port 24 and into sealable compartment 14. After reactor stud 20 has been mounted, brush support 38 is then moved into the second position to allow brushes 36 to intimately contact reactor stud 20. As shown in FIG. 3, sealable compartment 14 preferably has a fluid-tight viewing port or window 48 that allows viewing of the reactor stud during the cleaning process. Additionally, sealable compartment 14 may have an access door 50 that allows access to sealable compartment 14. Access door 50 allows technicians to assist, if needed, in mounting reactor stud 20 in the proper position on turntable 30. Further, access door 50 allows access to the stud for inspection after the cleaning process is complete. Apparatus 10 is totally self-contained and is a portable device. Housing 12 has retractable stabilizing supports 52 that can be retracted when moving apparatus 10 to a different location and can be extended to stabilize apparatus 10 during the cleaning process. Preferably, housing 12 has access ladders 54 to provide technicians access to top coverings 22 to assist in moving reactor studs 20 through ports 24. Referring to FIG. 4, preferably, apparatus 10 of the present invention is equipped with a solvent circulation system 60 for applying solvent to reactor stud 20 during the cleaning process to enhance cleaning. Solvent circulation system 60 can be used to recirculate conventional solvents or other cleaning agents known to those skilled in the art for cleaning reactor studs. Solvent is stored in a solvent sump 66 when recirculation system 60 is not in use. When the cleaning process begins, pump 62 under power of motor 64 pumps solvent from sump 66 and directs it through spray nozzles 68 onto reactor stud 20. Spray nozzles 68 are of a design commonly known to those skilled in the cleaning art. The solvent which is sprayed from nozzle 68 onto reactor stud 20 drains from compartment 14 through a drain 72. The solvent is then filtered in filter 74 to remove any contaminants picked up in the cleaning process. The filtered solvent then drains back into solvent sump 66. Spent solvent can be easily drained from sump 66 and disposed of according to acceptable hazardous waste regulations. Preferably, apparatus 10 is also equipped with a movable spray wand 70 which can be positioned to apply solvent to reactor stud 20 to assist in cleaning particular areas. Solvent recirculation system 60 provides several advantages to apparatus 10 of the present invention. Spray nozzles 68 and spray wand 70 assist the brushes 36 in cleaning reactor stud 20. Additionally, the use of a solvent eliminates airborne contamination that might normally be generated as mechanical brushes engage the rotating reactor stud 20. Apparatus 10 of the present invention further enhances this feature by recirculating the solvent thereby minimizing any waste generated through the use of a solvent to enhance the cleaning process. Also, the sump can be easily drained for environmentally safe disposal of spent solvent. FIG. 4 depicts a process flow sheet for a recirculation system to a single sealed compartment 14. However, as will be recognized, a single solvent recirculation 60 can be utilized with multiple sealed compartments 14. Each sealed compartment will have its own spray nozzles 68, spray wand 70, and drain 72. All sealed compartments 14 can utilize the same pump 62, solvent sump 66, and filter 74. As can now be recognized, the apparatus of the present invention provides for ease and safety in cleaning the reactor studs used to secure reactor heads on nuclear reactors. The present invention overcomes many of the problems associated with prior art cleaning machines. Particularly, the present invention provides an apparatus which reduces stud handling by allowing the reactor studs to be cleaned in the vertical position. Additionally, the apparatus of the present invention provides for independent cleaning of multiple reactor studs simultaneously or in rapid sequence. Further, the apparatus of the present invention has a solvent recirculation system that provides the advantages of solvent cleaning while minimizing the amount of solvent waste created. The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the details of the illustrated apparatus and construction and method of operation may be made without departing from the spirit of the invention.