Method and Apparatus for Handling Drums

In the disposal of hazardous waste such as radioactive materials, stringent precautions must be taken to guard against spilling or leaking of their containers. Typically, liquid or dry waste materials are stored in standard fifty-five gallon drums the walls of which often experience serious corrosion making them very susceptible to rupturing during handling. Manual handling of such drums can be dangerous to personnel, particularly with radioactive materials, and conventional remote control handling has proved unsatisfactory because of its reliance upon "crab claw" type devices which squeeze the drums about their midsection or between their ends. Such gripping devices entail a high risk of damaging the drums and causing their contents to spill.

It is one of the purposes of this invention to contain the object drum within a salvage overpack steel drum. Such overpacks, as they are hereinafter called, are heavy duty steel cylinders which may contain a special liner resistant to most hazardous materials. The overpacks are not themselves novel, except for a special gasket which may surround the run of their open end as described below, and neither are some of the individual elements of the apparatus of this invention. Thus self-loading vehicles designed to carry cylindrical tanks are taught in U.S. Pat. No. 2,808,948 and handling devices having a lower platform adapted to slide under a load and an upper lid to clamp the load vertically against the platform are shown in U.S. Pat. No. 2,682,347. However, the prior art neither anticipates nor suggests the overall combination of the drum handling method and apparatus described and claimed herein.

The invention provides a method of handling a drum from a first location in an upright position on a floor to a rotated position supported above the floor. The first step of the method is the positioning of a carrier platform on the floor alongside the drum. An open-ended overpack is then lowered vertically over the drum at the first location. The platform is next moved towards the drum while the overpack is translated with respect to the platform so that the overpack and drum therewithin maintain their position on the floor at the first location and the platform slides under the overpack and drum. A lid is lowered downwardly to clamp the overpack against the platform. The platform and lid are then elevated with the clamped overpack therebetween. Finally the platform and lid with the clamped overpack therebetween are rotated.

The invention also provides apparatus for handling a drum from a first location in an upright position on a floor to a rotated inverted position supported above the floor. It includes a powered steerable vehicle and movable driven frame means on the vehicle adapted for vertical displacement with respect thereto. A carrier platform is rotatably mounted on the frame and disposable in a horizontal position adjacent to the floor alongside the drum so that it may slide over the floor and under the drum. Lifting arm means are included which are pivotable to and slidable along said frame. First motion coordinating means are provided which cause the pivotable and slidable end of the arm means to remain fixed with respect to the first drum location as the vehicle is moved toward that location. Support link means are included which are longitudinally slidable on the opposite end of the lifting arm means. Drive means are also provided for translating the arm and link means into selected positions with respect to the frame and to one another. An open-ended overpack supported vertically by the link means is adapted to be lowered over the drum. On each side of the overpack detachable connector means are included for attachment to the link means at selected positions both above and below the horizontal centerline of the overpack. A lid is movable on the frame toward and away from the platform for clamping the overpack therebetween. Second motion coordinating means are provided for causing the overpack to move in a vertical path as the lifting arms are pivoted downwardly. By the foregoing structure the overpack can be lowered vertically over the drum by pivoting the arm and link means and can then be held fixed in relation to the first drum location as the carrier platform is caused to slide under the overpack by forward motion of the vehicle toward the drum, whereupon the lid can be lowered to clamp the overpack so that upon detachment of the link means the overpack and drum therewithin can be lifted and then rotated.

FIG. 1 is a pictorial view partly broken away showing the apparatus of the invention in its initial relation to an object drum;

FIG. 2 is a schematic side elevation showing the initial position of the overpack being lowered over the drum;

FIG. 3 is a schematic side elevation illustrating the platform about to slide under the drum;

FIG. 4 is a schematic side elevation showing the platform supporting the overpack with the lid clamped in place;

FIG. 5 is a schematic side elevation showing the arms swung clear of the overpack; and

FIG. 6 is a schematic end elevation showing the overpack and drum being rotated through a horizontal position toward an upside-down position.

Referring first to FIG. 1 the drum handling apparatus of the invention includes a vehicle 10 having four rubber tired wheels 11 and powered electrically from storage batteries 12 or from an external source linked by cables. A steering mechanism (not shown) is provided for the wheels 11 of the vehicle 10. It and the other controls described below may be operated from a personnel cab 13 or by remote control. In many instances, and certainly in the handling of radioactive waste, the vehcile 10 will indeed be adapted to remote operation and to this end a closed circuit television camera 14 may be mounted thereon for a clear view of the working area in front of the vehicle.

A typical fifty-five gallon drum 15 is shown in FIG. 1 in a free-standing upright position on a floor 16. In a nuclear power plant facility there may be many of such drums stored in vaults from which they must periodically be removed for transport to suitable permanent disposal sites. The apparatus and method of this invention find particular application in such vaults for picking up each drum in turn and carrying it to some means for long distance transport. It is not uncommon that such drums are seriously corroded after prolonged vault storage and the walls thereof weakened to the extent that rupture and leakage will occur if they are not handled with great gentleness. Such corrosion is found to be more severe at the lower ends of the drums when they have been standing upright in storage for long periods of time and for this reason, it is best to rotate the drums 180.degree. to an inverted position while they are being moved about. This relieves the weakened lower ends of the drums of the weight of the contents during handling. Conventional crab claw handling devices impose squeezing forces on the object drum which can very well cause damage and spilling of the hazardous contents. The purpose of the present invention is to pick up each drum and turn it on its side with the least possible force imposed on its walls.

It will be understood from the following description that a number of different drive devices are included in the apparatus of the invention. These may be hydraulic and hence a central hydraulic power pack 18 may be provided within the vehicle 10, or they may be electromechanical. A movable driven frame 19 is mounted on the vehicle and is adapted for independent displacement in two modes. First by means of a hydraulic tilting cylinder 20, that end of the frame 19 closest to the cab 13 can be raised or lowered while it pivots about the other end 21. Also the frame 19 includes a scissors linkage 22 operated through hydraulic cylinders, not shown in the drawings, by which an upper section 23 of the frame can be raised or lowered.

Extending from the forward end of the frame 19 is a rotator 24 rotatable about the longitudinal axis of the vehicle. It will be understood, therefore, that the upper section 23 of the frame may be raised and lowered, the forward rotator 24 may be turned about its axis on the frame, and all of these elements may be tilted forwardly by the mechanism 20 or tilted back to the horizontal position shown in FIG. 1.

Supported by the rotator 24 and extending forwardly from the vehicle 10 is a carrier platform 26. It includes a thin entry knife edge 27 at its forwardmost portion and this entry edge may be tilted downwardly into contact with the floor 16 when the tilting cylinder 20 is operated. Also supported by the rotator 24 is a lid 28 which is movable toward and away from the platform 26 by means of a hydraulic piston 29.

Bearings 30 (one shown) are mounted on a slide 31 which can be translated on the frame section 23 from the position shown in solid lines in FIG. 1 to as retracted position shown in dotted lines. Suitable hydraulic actuators are provided for the purpose but they are not shown in the drawings. Pivoted in these bearings 30 are side-by-side lifting arms 32 and 33. At the outer end of the arm 32 is a slidable right-angle support link 34 which can be moved in and out longitudinally relative to the arm 32 by a hydraulic piston 35. Similarly, at the outer end of the arm 33 is a slidable right-angle support link 36 which can be extended to various positions on the arm 33 by a hydraulic piston 37. As shown in FIG. 6 trunnions 40 extend from the outer ends of the supporting links 34 and 36. The trunnions 40 are slidable within slots 41 on brackets 42 fixed to the side of an otherwise standard overpack 43. Only one such bracket is visible in the drawings.

When the trunnions are at the upper ends of the slots they are above the horizontal centerline of the overpack and in that position permit the overpack to hang vertically under its own weight. When the trunnions are in the lower ends of the slots they are below the horizontal centerline of the overpack in an optimum position for causing relative horizontal sliding movement of the overpack. At the middle of the slot 41 between these upper and lower ends the bracket 42 is open so that when the trunnion 40 moves to that position it may be withdrawn by the action of the bracket 42 and disengaged entirely from the overpack 43. The same is true of the other trunnion and slot on the other side of the overpack.

In operation the drum 15 is in a free-standing upright position at a first location on the floor 16. The vehicle 10 is driven by remote control toward the drum 15 as viewed through the television camera 14 until it reaches a certain position spaced from the drum 15 as shown in FIGS. 1 and 2. By means of the scissors linkage 22 the upper section 23 of the frame 19 is at an elevated position at this time so that the vehicle can travel across the floor 16 with sufficient clearance for the carrier platform 26. The arms 32 and 33 and links 34 and 36 carry the overpack 43 in a suspended position with the trunnions 40 in the upper ends of the slots 41 in the brackets 42.

When the vehicle 10 reaches a certain predetermined position in relation to the drum 15, which can be sensed photoelectrically or by other suitable means, the vehicle is stopped and the overpack 43 is lowered downwardly over the object drum 15 as shown in FIG. 2. This lowering movement of the overpack is vertical translation along the axis of the drum 15 so that the overpack slides about the drum preferably without contacting it. Certain motion coordinating means are provided, such as programmed computer means, for causing the trunnions to move in a vertical path as the lifting arms are pivoted downwardly. The particular form of these coordinating means can vary and they are not shown in the drawings. It is enough to say that they are coordinating means which cause the cylinders 35 and 37 to extend and retract the arms 32 and 33 on the links 34 and 36, and which cause the slide 31 to move forwardly on the frame section 23 at the same time, with the result that the overpack 43 descends in a straight line. The frame 19 is then lowered so that the platform 26 is positioned just above the floor.

Next the tilting cylinder 20 is operated to lift the end of the frame 19 remote from the drum 15 as shown by the arrow in FIG. 3 so as to tilt the platform 26. The outer knife edge 27 then touches the floor 16 as shown in FIG. 3. As shown in FIGS. 3 and 4, the ends of the arms 32 and 33 pivoted in the bearings 30 on the slide 31 which is translated to the left on the frame 19 while the vehicle is driven to the right closer to the drum 15. These movements are shown by arrows in FIG. 4. The overpack and drum therewithin thus maintain their position on the floor at the first location and the knife edge 27 and remainder of the platform 26 slide under the overpack and drum. During this relative movement the trunnions 40 are in the lowermost ends of the slots 41 of the brackets 42 to hold the overpack 43 in place beneath its horizontal centerline so that it does not tend to tip over.

The tilting cylinder 20 is again actuated to tilt the frame 19 back to its horizontal position as shown in FIG. 4. The lid 28 is lowered as shown by an arrow in FIG. 5 by operation on hydraulic cylinder 29 in a downwardly direction onto the overpack without contacting the drum to clamp the overpack against the platform 26. A gasket of elastomeric material, preferably polytetrafluoretylene, may be located about open rim of the overpack 43 which is lowermost as seen in FIG. 1, to lubricate its sliding onto the platform 26 and to seal the overpack to the platform 26 when the force of the lid 28 is applied. The links 34 and 36 are translated such that the trunnions are freed of the brackets 42 through the central openings thereof and the arms are then pivoted upwardly to the position shown in FIG. 5 as shown by the curved arrows. The frame 19 is then elevated from the lowered position shown in FIG. 4 back to the slightly higher position shown in FIG. 5.

In the final step of the operation the rotator 24 is turned 180.degree. so that the drum is turned upside-down. This rotation is shown by an arrow in FIG. 6 moving through the halfway horizontal position. The vehicle 10 is then driven by remote control to the next destination of the drum which may be transport means of some kind and any spilled contents are retained by the closed-end overpack. Unloading is carried out by a series of steps which are the reverse of those described above. Throughout all of this handling the drum 15 is never squeezed in crab claw fashion. It is enclosed in the overpack, lifted and then turned on its side with a minimum of force applied to its walls, thus ensuring to the greatest possible extent that no leakage occurs.

The foregoing embodiment of the apparatus and method are to be understood as a preferred form of the invention and the full scope of the invention is to be determined from the following claims.