Abstract:
It is common to store decayed radioactive waste in waste packages, lowered into vertical concrete cylindrical storage containers called tile holes. These containers of these packages decay over time and may become fragile, making it difficult to remove them using conventional methods. A retrieval tool has been developed, comprising a cylinder that fits between the tile hole internal diameter and the outside diameter of the waste package inside the tile hole. Inflatable air wedges are equally spaced inside the cylinder. The air wedges are inflated to a low pressure (2.1 psig) to provide uniform grip to the outside of the packages, minimizing the risk of damage to the decayed containers. A back-up system uses horizontal safety bars at the bottom of the cylinder, which may be rotated to form a partial platform under the waste package, preventing the package from falling in the event of a failure.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to retrieval systems and more specifically, to a device and system for lifting and/or moving objects that cannot be gripped and lifted safely and reliably by readily available, conventional means. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is common to store decaying radioactive waste in vertical concrete cylindrical storage containers called tile holes. Within these tile holes are waste packages, which are formed in part by plastic and metal waste containers containing various levels of decayed radioactive wastes. These waste packages were originally loaded into the tile holes by a wire rope leader attached to the waste package. After each waste package was lowered into the tile hole, the wire leader was cut and the remaining length of wire remained attached to the waste package. 
         [0003]    The tile holes are considered to be a temporary storage location. At some point the waste packages are to be retrieved, repackaged and put into a long term storage facility. Over time the containers have become degraded, with the plastic material of the waste containers being irradiated and becoming fragile, while the metal containers may have suffered from corrosion. Due to the degraded nature of the waste containers, retrieving these poses a significant safety risk as there is danger of the waste containers breaking apart. 
         [0004]    Previous attempts made at retrieving decayed waste packages from tile holes have revealed that the existing retrieval tooling is inadequate. The waste container integrity after a number of years of storage introduced significant risk of failure and contamination if the waste container was damaged during the retrieval process. The method of retrieval currently available is to simply hook onto the wire that is attached to the waste packages and they are lifted out one at a time, using a crane. In a June 2010 retrieval campaign, two waste packages were successfully retrieved in this fashion. The operation was stopped when a leader detached from the third waste package, which prevented safe retrieval of the waste package using existing tooling. One of the waste packages retrieved from this tile hole was examined in one of Chalk River Laboratories hot cell facilities to evaluate the structural integrity of the plastic container. 
         [0005]    The waste container shattered and broke apart when handled by manipulators, indicating that the waste containers had degraded over time. 
         [0006]    It is not acceptable to have a retrieval system which may allow waste packages to fail and potentially release radioactive waste. There is therefore a need for an improved method and technology to lift waste packages safely from tile holes. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the invention to provide an improved method and system to lift waste packages from tile holes. 
         [0008]    A retrieval tool has been designed and developed that comprises air bladders that are inflated to clamp around the periphery of a waste package without creating pressure points. There is also a safety backup system that deploys a support platform below the waste package once partial lifting has begun. Other features of the retrieval tool include spring loaded fingers to move the waste package from the walls of the tile hole, guiding the waste package into the retrieval tool. The spring loaded fingers were found to be effective for a specific waste package form, but may equally be a tapered leading edge for differing packages. The system also has a number of other advantageous features that include the release and activation mechanisms of the backup safety system. 
         [0009]    The heart of the retrieval tool comprises a sheet metal cylinder fitted with air bladders (wedges) that fits into the tile hole and has sufficient clearance inside to accommodate the waste package to be gripped. The air wedges are filled with air from a supply source, to a pressure sufficient to grip the waste container. In a recent demonstration on actual degraded waste packages, a pressure of 2.1 PSIG safely gripped these straight-walled containers weighing up to 50 Kg. 
         [0010]    A backup safety system was also incorporated into the retrieval tool, comprising vertical safety rods that allow safety bar arms to be rotated under the load to provide support to the bottom of the waste package. The safety bar arms are curved such that when the safety bar arms are in the open or stowed position they take the form of the sheet metal cylinder and remain out of the way whilst the waste package is entering into the retrieval tool. 
         [0011]    This retrieval tool provides the first practical method for large scale retrievals of degraded and fragile decayed waste packages from temporary storage tile holes. 
         [0012]    There may be other applications that require a tool to provide limited loading when lifting containers, packages or anything that may require gentle and even pressure during lifting. 
         [0013]    The functionality of this tool was tested in a November 2011 retrieval campaign. The November 2011 retrievals retrieved a total of four waste packages, and included a waste package with a failed lift cable identified in the June 2010 retrieval campaign. It was a very successful test, given that the lid of the last waste package lifted was observed to be broken within the tile hole, with a brittle failure similar to that of the container previously examined in the Chalk River Laboratories facilities. All four waste packages were retrieved without incident or further damage to the waste containers. The November 2011 campaign demonstrated that degraded waste packages can be safely gripped and retrieved from tile holes, and that the system of the invention is a viable option for the relocation of waste packages to alternate engineered storage locations. 
         [0014]    Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein: 
           [0016]      FIG. 1  shows a graph of gamma radiation dose rates during a retrieval exercise; 
           [0017]      FIG. 2  shows a retrieval tool system suspended from a lifting tube and load limiter; 
           [0018]      FIG. 3  shows a photograph of the lower end of the retrieval tool; 
           [0019]      FIG. 4  shows the six air wedges in a deflated state, while  FIG. 5  shows the air wedges partially inflated; 
           [0020]      FIG. 6  shows a detail of the air wedges clamped in the body of the retrieval tool; 
           [0021]      FIG. 7  presents a screen capture of the top of a package in a tile hole array, as viewed from the retrieval tool&#39;s camera; 
           [0022]      FIG. 8  shows a drawing of the air wedges themselves; 
           [0023]      FIGS. 9 and 10  show details of the air wedge clamp; 
           [0024]      FIG. 11  shows a schematic diagram for the compressor and vacuum supply system; 
           [0025]      FIG. 12A  shows the body weldment of the retrieval tool,  FIGS. 12B and 12C  showing the rotatable safety bars in lowered and raised positions respectively; 
           [0026]      FIG. 13  shows details of the vertical latch subassembly of the retrieval tool; 
           [0027]      FIG. 14  shows details of the lift tube spider subassembly of the retrieval tool; 
           [0028]      FIG. 15  shows details of the actuator disk subassembly of the retrieval tool; 
           [0029]      FIG. 16  shows a detail of the latch mechanism of the retrieval tool, including the latch release cable; 
           [0030]      FIG. 17  shows a detailed view of the top of the retrieval tool where the radial position locking mechanism is visible; 
           [0031]      FIG. 18  shows a detailed view of the top of the retrieval tool where the open and closed radial positions of the actuator disk subassembly are visible; 
           [0032]      FIG. 19  shows a detail of the load limiter subassembly of the retrieval tool; 
           [0033]      FIG. 20  shows a view of a tile hole with a retrieval tool partially inserted, and a contamination control bag positioned at the opening of the tile hole; 
           [0034]      FIG. 21  shows a detail of a contamination control bag in accordance with an embodiment of the present invention; 
           [0035]      FIG. 22  shows a collection of hand tools for use with the retrieval tool; 
           [0036]      FIG. 23  shows the hooking of a waste package wire using a small hook, which will transfer the wire to the rectangular head of a larger hook tool. The larger hook has a built-in friction device, allowing one end of the cable to be pulled up to the top of the tile hole, yet preventing it from slipping out of the hook; 
           [0037]      FIG. 24  shows a prototype version of a wire cutter tool; 
           [0038]      FIG. 25  shows a photograph of the lower end of the Mark III retrieval tool; 
           [0039]      FIG. 26  shows a drawing of the lower end of the Mark III retrieval tool, from a perspective similar to that of  FIG. 25 ; 
           [0040]      FIG. 27  shows a cross-sectional drawing of the Mark III retrieval tool; and 
           [0041]      FIG. 28  shows a partial, enlarged view of the cross-sectional drawing of the Mark III retrieval tool of  FIG. 27 , showing the details of the upper end of the inflatable air wedges in this embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    As explained above, recent attempts at retrieving decayed waste packages from tile holes have revealed that the existing retrieval tooling is inadequate. The waste container integrity after a number of years of storage introduced significant risk of failure and contamination if the waste container was damaged during the retrieval process. The current method of retrieval is to simply hook onto the wire leader that is attached to the waste packages and they are lifted out one at a time. Since some of the waste containers have degraded over time the risk of breaking the waste containers during retrieval is high. 
         [0043]    A retrieval tool has been developed to address the problems in the art, employing six inflatable air wedges equally spaced inside the body of the retrieval tool. Any practical number of air wedges could be used, though for purposes similar to the one described, between 3 and 8 air wedges would generally be used. The tool body is in the form of a stainless steel cylinder that has been designed to fit between the tile hole internal diameter and the outside diameter of the waste package inside the tile hole. The air wedges are inflated to a low pressure (2.1 psig, for example) that is intended to provide a generally uniform pressure onto the outside of the waste packages to minimize the gripping force required to lift the waste packages. This will minimize the risk of damaging the decayed waste containers. 
         [0044]    Also included in the design of the retrieval tool is a back-up system using “safety bars”. There are six safety bars that fit between the air wedges, and are fabricated from steel bars oriented vertically. Again, any practical number of safety bars could be used, though for purposes similar to the one described, between 3 and 8 safety bars would generally be used. The lower end of each bar is fitted with a horizontal arm and onto each horizontal arm is mounted spring steel “fingers” or other suitable leading edge. Both the horizontal arm and the “fingers” are curved to match the profile of the retrieval tool. When the horizontal arms are in the stowed or open position, the fingers form a tapered lead-in to help guide the waste package into the retrieval tool. Once the air wedges are pressurised, the captured waste package is lifted a short distance, and the horizontal arms are dropped downwards and then rotated to the closed position. When the horizontal arms are in the deployed or closed position they form a partial platform under the waste package, preventing large pieces of material, or the entire package, from falling due to the collapse of the waste container or failure of the air wedges. 
         [0045]    Another aspect of the retrieval system is the addition of a containment control bag specifically designed to be hooked onto the retrieval tool, to enclose the waste package and its contents when transferring the waste package from the tile hole across the ground to its designated overpackage. 
         [0046]    Prototype tools were built to verify and demonstrate the use of a pneumatic gripping system to lift waste packages from tile holes. As shown in the successful retrieval of the waste package during a test, the retrieval tool provides a gentle means of gripping degraded and brittle waste containers without further damage to that waste container. Other observations include:
       The seam in the tile hole did not hinder the retrievals. This observation was noted only after the waste package at this location was engaged and lifted clear of the tile hole.   A camera mounted on the retrieval tool was very useful, permitting monitoring of the process.   The four waste packages that were lifted were all resting against the side of the tile hole wall which meant the retrieval tool had to move and centre the waste packages before engaging these, which occurred without difficulty.   The tool incorporated a photodiode sensor, which was located 10-12 mm above the internal stop within the retrieval tool to detect radiation levels. A tablet computer was used to analyse the signal to give real-time field levels, and recorded these values in 1 second intervals. These have been plotted and included as  FIG. 1 . The four periods of elevated readings indicate the period of time in which the retrieval tool engaged a waste package.       
 
         [0051]    Two primary prototype retrieval tools were developed: a Mark I tool and a later Mark II tool, both of which were built and tested. From observations made at the Mark I tool demonstration, there were a number of operating and design requirements to be included as part of the Design Inputs for the Mark II tool. The key inputs that were documented are as follows:
   1. A tool is needed to cut the existing wire leader within the tile hole.   2. The retrieval tool shall preferably be able to move packages that are resting on the wall of the tile hole without crushing the edge of the waste container.   3. Provide a mechanism to ensure the Safety Bars remain fully open as the retrieval tool is lowered over each waste package.   4. The safety bars are to be firmly fixed in place, in the deployed (i.e. closed) position during retrieval of a package.   5. Consideration should be given to flaring the bottom of the retrieval tool (with a round edge) to assist in self-centering the waste package as the retrieval tool is lowered over it.   6. Ensure that only one waste package at a time is captured when the air bags are inflated.   7. Add a ‘gentle’ hard stop so the retrieval tool settles consistently on the top of the waste package before the air wedges are activated.   8. Add additional clearance between the internal diameter of the retrieval tool and the outside diameter of the waste package.   9. Demonstrate the retrieval tool using a mock-up with plexiglass tube and three or four stacked packages/cans, on the Mark II version to validate that the retrieval tool does not interfere with the waste package beneath the one being retrieved.
 
Later it was determined that the safety bars should be in a deployed (i.e. closed) position while the retrieval tool is travelling down through the tile hole to the waste package, to keep the triangular fingers from catching on the sides of the tile hole wall. This improved the operability of the system.
   
 
         [0061]    Thus, the following list of design inputs was developed: 
         [0000]                                        TABLE 1                   List of Design Inputs for Mark II retrieval tool            #   Description                    1   Weight of packages: 5 to 50 kg       2   Air pressure delivery system operation &lt; 15 psig and be protected           by a PSV (pressure safety valve) to &lt;15 psig       3   Volume of air in pressurized system to be less than 1.5 ft 3         4   Verification to be carried out on a tile hole       5   Equivalent diameter of air wedges to be &lt;6.5 inch diameter       6   Equipment shall permit the retrieval of nine waste packages from            a tile hole without having to reconfigure the retrieval tool       7   A mechanical back-up system (safety bars) to be in place to            provide support to a package if the air wedges cannot provide            sufficient friction to hold the waste package being retrieved       8   Appropriate markings to be added to the equipment to show            vertical and radial positions of safety bars       9   Air wedges are to be retracted as far as possible to maximize            clearance to packages prior to retrieval       10   Easy to use tools (e.g. handle to wind in wire, wrench to move one            feature relative to another) to be employed to activate the            equipment during operation       11   Equipment to be designed to be able to retrieve waste            packages that are close to, or are touching the tile hole wall       12   Lifting equipment to follow ASME B30.20-2010 Category A            Service Class 0       13   Equipment to be designed to lift packages from tile holes without            snagging       14   Incorporate a mechanical stop to ensure that the equipment cannot            go beyond the depth of the waste package being retrieved       15   Equipment to ensure only one waste package can be retrieved at            one time       16   The equipment is to accommodate the worst case geometries of the            tile hole and packages as per the requirements provided below:       17   Waste container material: plastic and metal       18   Waste package height: 15 to 18 inches       19   Waste package outside maximum diameter: 10 to 13 inches       20   Tile hole diameter: 14.775/15.225 inches (based on ASTM A-76)       21   Tile hole depth: Nominally 15 feet 11 inches       22   Provide means to cut and remove leader wires attached to waste            packages without damage to waste packages       23   Operation of equipment should be designed to keep operators away            from the tile hole opening       24   Equipment to include a camera or cameras to enable visual            monitoring inside the tile hole       25   Tool to be retrievable from tile hole in the event of a failure                    
These issues were addressed in developing the embodiment described herein.
 
       Design Details 
       [0062]    This section describes the proof of concept retrieval tool features and its principal of operation. 
         [0063]    The general assembly of the retrieval tool  10  can be seen in  FIGS. 2 and 3 . The stainless steel lower cylinder  12  is suspended from a round lift tube  14 . The round lift tube  14  in turn, is suspended from a crane, backhoe or similar lowering machine, via a load limiter  16  (i.e. a spring loaded shock absorber), which keeps the entire weight of the retrieval tool  10  and lowering machine from bearing on the waste package being removed. The height of the retrieval tool  10  is dictated by the depth of the tile hole. The prototype retrieval tool  10  is over 19 feet long and has been designed to remove one waste package at a time from an Irradiated Rod Part (IRP) tile hole with up to nine waste packages stored inside. The stainless steel lower cylinder  12  contains six equally spaced inflatable air wedges  18  (see  FIGS. 4 and 5 ). The triangular shaped metal fingers  20  can be seen in  FIG. 2 , and in the photo of the lower part of the retrieval tool  10  in  FIG. 3 . These triangular shaped metal fingers  20  are designed to centre the retrieval tool  10  within the tile hole and to encourage waste packages that are leaning against the side of the tile hole into the aperture of the retrieval tool  10 . 
         [0064]    A back-up feature is the use of a partial platform that can be positioned below the waste package being retrieved. Providing such a platform presented a design challenge since the partial platform had to allow the waste package to pass through it and into the stainless steel cylinder  12  as the retrieval tool  10  is being lowered. This requirement was met by using six rotatable “safety bars”  22 . The lower part of each safety bar has a 90° horizontal arm  24  welded to it. The safety bar horizontal arms  24  are arcuately-shaped so that when retracted (in the “open” position) the safety bar horizontal arms  24  align with the leading peripheral edge of the stainless steel cylinder  12 , allowing the waste package to enter the retrieval tool  10 .  FIG. 6  presents one of the safety bar horizontal arms  24  with the triangular shaped metal fingers  20  removed so that it can be clearly seen.  FIG. 7  presents a view of the safety bar horizontal arms  24  in a deployed (i.e. “closed” position), although the safety bar horizontal arms  24  are actually above the waste container in this view. 
         [0065]    The safety bars  22  are connected to a disc assembly  26  (a cam) that is located above the stainless steel cylinder  12 . This disc assembly  26  is connected to a square hollow tube  28  that extends to the top of the retrieval tool  10 . Inside the square tube  28  is the round lift tube  14  that connects to the stainless steel cylinder  12  and also to the top of the retrieval tool  10 . It is the round lift tube  14  which bears the load of the system. The round lift tube  14  and square tube  28  can rotate relative to each other. When the square tube  28  is rotated, it turns the disc assembly  26  with respect to the stainless steel lower cylinder  12 . This in turn rotates the safety bar arms  24  towards the centre of the stainless steel cylinder  12  providing a platform in case the waste package or parts of the waste package fall from the inside of the retrieval tool  10 . Inside the round lift tube  14  are the pneumatic lines  30  connecting the inflatable air wedges  18  to compressor and vacuum system  32 , and also wires connecting a video camera with integral LED lighting  34 , and a radiation detector  36 . The electronic data for radiation detection and camera footage is captured on a laptop computer, tablet computer or similar device. 
         [0066]    Referring to  FIG. 8 , the six inflatable air wedges  18  are constructed from a commercially available lay-flat hose (similar to a fire hose) that is clamped shut at both ends by bolting the lay-flat hose to the stainless steel lower cylinder  12  of the retrieval tool  10 . A hole  38  near one end of each section of hose allows the inflatable air wedges  18  to be connected to a plastic tube by means of a through-wall fitting and tube connector  40 . In this particular case, the lay-flat hose is a 4″ nominal size PVC covered polyester yarn reinforced 75 psi rated water hose, purchased from McMaster-Carr (item No. 5295K41), chosen since it had the right balance of flexibility, puncture resistance, friction and lay-flat width. Other hoses can be considered depending on the application. The through-wall fitting  40  was also purchased from McMaster-Carr (item No. 8682T21), and was installed in the hose wall. All six inflatable air wedges  18  were connected to the compressor and vacuum system by means of the distribution header  42  shown in  FIGS. 4 ,  5  and  11 , and ¼″ ‘Polyflo’ tubing. 
         [0067]      FIG. 6  shows a close-up view of the inflatable air wedges  18  clamped to the stainless steel lower cylinder  12  of the Mark I version of the retrieval tool  10 .  FIG. 4  shows the six inflatable air wedges  18  in a deflated state. Also visible is the distribution header  42 , comprising tube tees, adapters and through-wall fittings  40 .  FIG. 5  shows the inflatable air wedges  18  partially inflated, again in the Mark I version of the retrieval tool  10 .  FIGS. 9 and 10  show the clamp details for the inflatable air wedges  18 , while  FIG. 11  shows a schematic diagram of the pressure/vacuum supply, all of which are for the Mark II version of the retrieval tool  10 . 
         [0068]    As shown in  FIG. 8 , each of the inflatable air wedges  18  comprises a length of 4″ PVC covered polyester yarn lay-flat water hose. Each length of hose is clamped at the top and bottom of the stainless steel cylinder with a pair of clamps as shown in  FIGS. 9 and 10 , the clamp of  FIG. 9  being placed on the inside of the stainless steel cylinder  12 , and the clamp of  FIG. 10  being placed on the outside. The inside clamp of  FIG. 9  is fabricated from austenitic, annealed stainless steel, UNS S30400/S30403 (AISI 304/304L). The outside clamp of  FIG. 10  is fabricated from type 304L stainless steel, 11 gauge, 2B finish, per ASTM A240. These inside and outside clamps are bolted together using stainless steel bolts, though other fasteners could also be used such as rivets. As the inflatable air wedges  18  are inflated and deflated, their length will change to a small degree. To accommodate this, the stainless steel cylinder  12  is actually fabricated from two co-axial cylinders, in a sliding sleeve arrangement. There is no need for springs or other mechanisms to bias the two cylinders relative to one another; they can slide freely as their positions will be determined by the length of the inflatable air wedges  18 , and the extent to which the inflatable air wedges  18  are inflated. 
         [0069]    As shown in the schematic diagram of  FIG. 11 , the compressor and vacuum system  32  consists primarily of a 1.3 CFM vacuum/pressure pump  50  and a 2 U.S. gallon air receiver  52 . The compressor and vacuum system  32  is protected with a 10 PSI pressure safety valve  54  upstream of an adjustable air regulator  56 , and a 5 PSI pressure safety valve  58  on the downstream side. As well be explained in greater detail hereinafter, the operating pressure of the prototype system was 2.1 psig. The two-way valve  60  is used to control the delivery of air pressure to the inflatable air wedges  18 . The three-way control valve  62  is used to control the vacuum to collapse the inflatable air wedges  18 . The compressor and vacuum system  32  is provided with visual pressure displays  64 ,  66  on the upstream and downstream of the two-way control valve  60 , and a 5 micron air filter  68 . All of the pneumatic tubing is ¼″ Polyflo tubing. While this is a manual system, it could easily be automated and operated with a commercial tablet or laptop computer, or a dedicated electronic control system. 
         [0070]    The general arrangement of the latest version of the retrieval tool  10  and major sub-assemblies are shown in  FIGS. 12A to 19 . The details of how the locking mechanism works on the safety bar horizontal arms  24  is shown in  FIGS. 14 to 18 . As much as possible, the retrieval tool was built from stainless steel, aluminum and other corrosion resistant materials to allow the retrieval tool to be exposed to outdoor weather conditions. 
         [0071]    As shown in  FIG. 12A , the six rotatable safety bars  22  are mounted to the stainless steel cylinder  12  with stainless steel guides  80  which are tack-welded to the stainless steel cylinder  12 . The six rotatable safety bars  22  are equally-spaced about the circumference of the stainless steel cylinder  12 , are free to rotate within the stainless steel guides  80 , and can move a certain distance longitudinally. This longitudinal movement allows the safety bar horizontal arms  24  to drop down below the bottom of the stainless steel cylinder  12  before being rotated inwardly, avoiding a waste package that may be protruding slightly below the bottom of the stainless steel cylinder  12 . The rotatable safety bars  22  are shown in their lower position in  FIG. 12B  and in their upper position in  FIG. 12C . The triangular metal fingers  20  at the bottom of the retrieval tool  10  are welded to the safety bar horizontal arms  24  as shown in photograph of  FIG. 12A . The waste packages invariably lean to one side against the wall of the tile hole. The triangular metal fingers  20  urge the waste package away from the tile hole wall to allow gripping of the waste package. 
         [0072]    The six rotatable safety bars  22  pass through the lift tube spider  82  welded to the top of the stainless steel cylinder  12 , the upper ends of the rotatable safety bars  22  being connected to the actuator disk  26 . As noted above, the actuator disk  26  can move between an upper position in which the safety bar horizontal arms  24  are recessed within the stainless steel cylinder  12 , and a lower position in which the safety bar horizontal arms  24  drop below the bottom of the stainless steel cylinder  12 . The actuator disk  26  is held in the upper position by means of the latch  84  shown in  FIG. 13 . The latch  84  pivots between two positions—the raised position in which it holds up the actuator disk  26  per  FIG. 16 , and a lowered position in which the actuator disk  26  drops under the force of gravity, allowing the safety bar arms  24  to drop down below the bottom of the stainless steel cylinder  12 . The latch  84  is urged to the raised position by a spring  86 , pivoting around latch pin  88 . A wire latch release cable  90  is connected to the upper part of the latch  84  with a small pin  92 , the latch release cable  90  being used to release the latch  84  when the actuator disk  26  is rotated. The other end of the latch release cable  90  is connected to a rod clamp and tubing 92 (¼″ OD×0.035 wall thickness seamless stainless steel ASTM a269 type 304) mounted on the lift tube spider  82  (see  FIG. 14 ). 
         [0073]    As shown in  FIG. 14 , the lift tube spider  82  is a circular stainless steel plate  94  with strengthening webs  96 , which is welded to the top of the stainless steel cylinder  12  to give it strength. The lift tube spider  82  serves as a bearing surface for the actuator disk  26  when it drops, and also serves as a support surface for the lock plate  98 , the stop plate  100  and the video camera  34 . Slots are cut into the lift tube spider  82  so that it will not interfere with the rotatable safety bars  22 . 
         [0074]    The lock plate  98  is a stainless steel plate with two holes through which the lock bar  102  may be inserted. This allows the rotational position of the actuator disk  26  to be fixed in one of two positions. This in turn, fixes the safety bar horizontal arms  24  in either the stowed or deployed position. The lock plate  98  is mounted to the lift tube spider  82  with threaded hex standoffs (2″ long×10-32 UNF threads, 18-8 stainless steel McMaster-Carr p/n 91115a417 or equal, and 10-32 UNF×⅜″ long socket button head cap screws, to meet ANSI b18.3 and ASTM f835). 
         [0075]    The stop plate  100  is a stainless steel plate which rests on the top of the waste package after the retrieval tool  10  is lowered into position. The stop plate  100  is mounted to the lift tube spider  82  with ¼-20 UNC×5″ long threaded stud, 18-8 stainless steel, McMaster-Carr p/n 95412a562 or equal, and ¼-20 UNC hex nuts, 18-8 stainless steel, to AISI b18.22 and ASTM f594. 
         [0076]    The camera mounting plate  102  is a stainless steel plate which is mounted to the lift tube spider  82 , again, with threaded rod and hex nuts. Any suitable video camera  34  may be used, but in the prototype, Micro Video Products model number mvc2000wp-led, was used, with a 100′ cable and the focus distance set at 17″. A computer tablet may be used to operate this fixed focus camera. The camera was set up to give the clearest picture from the tip of the safety bars. It was used as a reference to ensure that the waste package was not slipping in the retrieval tool by observing any changes in the image. No slippage was observed in any of the retrievals. 
         [0077]    The details of the actuator disk  26  construction are shown in  FIG. 15 . The actuator disk lower assembly  110  and actuator disk upper plate  112  are connected with threaded hex standoffs (¾″ long×10-32 UNF threads, 18-8 stainless steel McMaster-Carr p/n 91115a407 or equal) and button head cap screws on the top (10-32 UNF×⅜″ long socket button head cap screw, to meet ANSI b18.3 and ASTM f835 or equal), with flat head cap screws on the bottom (10-32 UNF×½″ long socket flat head cap screw, to meet ANSI b18.3 and ASTM f835 or equal). 
         [0078]    As shown in  FIGS. 16 and 17 , the top end of each safety bar terminates at a fitting  114  that slides within grooves  116  in the actuator disk lower assembly  110  and actuator disk upper plate  112 . Thus, when the actuator disk  26  is rotated with respect to the stainless steel cylinder  12 , the fittings  114  slide within the grooves  116 , causing the rotatable safety bars  22  to rotate. Also as shown in  FIGS. 15 ,  16 ,  17  and  18 , each fitting  114  has a steel j-hook  118  (¼-20 UNC thread, McMaster-Carr p/n 9492t13 or equal cut threads to ½″ long, or equal), which holds a spring  120  connected to a hub at the center of the actuator disk assembly  26 . This spring biases the fitting  114  towards the center of the actuator disk assembly  26 , and biases the safety bar horizontal arms  24  to the deployed position. 
         [0079]    The actuator disk assembly also includes a steel eyebolt  122  with a shoulder for lifting the assembly (¼″-20 thread, 500 lb working load min 1″-thread length). 
         [0080]    The main square tube  28  is fabricated from stainless steel sheet, type 304L, 20 ga, 2b finish, material per ASTM a240. It has a number of brackets  132  welded along its length to guide the lock rod  130 . Each lock rod lift bracket  132  has a pair of rod clamps to guide the lock rod  130 . One or more clamp-on stainless steel shaft collars (¼″ two piece clamp-on stainless steel shaft collar McMaster-Carr p/n 6436k32 or equal) may be fastened to the lock rod  130  to limit its range of longitudinal movement within the guides. 
         [0081]    Thus, the lock rod  130  slides vertically through holes in the actuator disk assembly  26  shown in  FIG. 15 , and drops into one of two holes in the lock plate  98  of  FIGS. 14 and 17 . With this arrangement, the actuator disk  26  can be rotated into one of two discrete positions, with the cams in the actuator disk  26  opening and closing the safety bars  22 . The actuator disk  26  rests on the vertical latch  84  shown in  FIG. 16  to maintain the safety bars  22  in the upper position. Once the waste package is raised slightly, a tug on a wire latch cable  90  trips the latch  84  which allows the safety bars  22  drop the height of the latch  84 . 
         [0082]    A detail of the load limiter assembly  16  is shown in  FIG. 19 . The eyenut  140  would typically be chosen to accommodate whatever lifting machine is to be used, and the weight of the retrieval tool  10 . In this case a ¾″-10 UNC eyenut, plain steel galvanized, 5,200 work load limit, McMaster-Carr p/n 3019t21 was used. The eyenut  140  is locked using a ¾-10 UNC hex jamnut, zinc plated, SAE grade 5. 
         [0083]    In this assembly four pneumatic cylinder tie rods  142  (forming part of Motions Controls LLC 2½″ bore×12″ stroke cylinder, p/n d49senc sl12 ra1 or equal) and pneumatic cylinder tie rod nuts  144  (forming part of Motions Controls LLC 2½″ bore×12″ stroke cylinder, p/n d49senc sl12 ra1 or equal) fasten together the upper end cap  146  and lower end cap  148  (pneumatic cylinder end cap assembly, Motions Controls LLC 2½″ bore×12″ stroke cylinder, p/n d49senc sl12 ra1 or equal). 
         [0084]    A pneumatic cylinder piston and rod assembly  150  (forming part of Motions Controls LLC 2½″ bore×12″ stroke cylinder, p/n d49senc sl12 ra1 or equal) is housed within a pneumatic cylinder barrel  152  (forming part of Motions Controls LLC 2½″ bore×12″ stroke cylinder, p/n d49senc sl12 ra1 or equal). The pneumatic cylinder barrel  152  also houses three standard music wire compression springs 154 (1.937 OD×4.5″ free length 89.2 lb force at 2.788″ compressed height, k=52.1 lb/1 n, Associated Spring Raymond p/n c1937-192-4500-m), which are seated against load limiter end spring cups  156  at the upper and lower end, and are divided by two load limiter center spring cups  158  within the pneumatic cylinder barrel  152 . 
         [0085]    Prior to the retrieval tool  10  being presented and lowered into the tile hole, via a crane, there are two operations that were deemed to be required. The first requirement is to place a contamination control bag  170  around the protruding tile hole outside diameter.  FIG. 20  shows such an operation being performed. The contamination control bag  170  has been added to provide a back-up system to catch any potential debris that may fall from the waste package or the waste container or parts of the waste package, should it disintegrate or break up once the retrieval tool is moved away from the tile hole aperture. A sketch of the contamination control bag  170  used for the proof-of-concept tool is shown in  FIG. 21 . As shown in this figure, the contamination control bag  170  generally comprises a woven tarpaulin fabric sleeve  172 , with drawstrings  174 ,  176  on both the top and bottom. The woven tarpaulin fabric sleeve  172  has a nominal length of 4′. Six equally spaced loops of 8″ in length were sewn to the inside of the woven tarpaulin fabric sleeve  172  to support the drawstrings  174 ,  176 . The contamination control bag  170  was designed to be sufficiently durable to contain a 50 kg waste package. The contamination control bags were used without any issues being raised by the team that used them. 
         [0086]    The other operation is to hook the wire leader attached to the waste package to be retrieved, from inside the tile hole and to thread it through the top of the stainless steel cylinder  12  of the retrieval tool  10 . The wire leader hook  180  shown in  FIG. 22  was designed for this purpose. It is shown in use in  FIG. 23 . Once the wire leader is passed through the retrieval tool  10 , the wire leader can be gently pulled through as the waste package is lifted. The excess wire leader is placed into a receptacle, made from a new pail with a hole in its lid, to minimize the spread of radioactive contamination outside the tile hole. 
         [0087]    Before lowering the retrieval tool  10  into the tile hole the actuator disc assembly  26  is set to its raised position and the safety bars  22  are locked into their “open” position. The radial positions of the outer square tube  28  relative to the inner round tube  14  are marked on the retrieval tool  10  as “open” and “closed” as shown by  FIG. 18 . That is, one or more viewing holes are cut in the outer square tube  28  so that the surface of the inner round tube  14  can be seen. The surface of the inner round tube  14  is then marked up so that the operating position of the actuator disc assembly  26  can be monitored through the viewing holes. A rotating tool  182  as shown in  FIG. 22 , has been designed for rotating the square tube  28  relative to the round tube  14 . As shown, rotating tool  182  looks like a large wrench with a long handle. The open “C” part of this tool fits over the square section of the outer square tube  28 . Simultaneously lifting the lock rod  130  out of its current hole, and “jerking” the rotating tool  182  in the correct rotational direction (one direction opens the safety bars and the other direction closes them), rotates the square tube  28  relative to the inner round tube  14 . By removing the vertical force lifting the lock rod  130 , (once it is out of alignment from its original hole) the square tube rotation can continue until the lock rod  130  falls into its second location hole indicating it has reached the locked “closed” position. 
         [0088]    When the retrieval tool  10  is lowered into the tile hole it will eventually come to rest via the stop plate  100  located on the inside of the retrieval tool  10 . To avoid having the whole weight of the retrieval tool  10  bearing down onto the top of the waste package to be retrieved, a load limiter  16  containing a reaction spring was incorporated near to the top of the retrieval tool  10  positioned close to the lifting hook  140  to remove the full weight of the retrieval tool  10  from crushing the waste packages within the tile hole. The point at which the retrieval tool  10  makes contact with the top of the waste package to be retrieved is determined with the aid of the video camera  34 . The video camera  34  sits in the middle of the stainless steel cylinder  12  of the retrieval tool  10  and points in the vertically downward direction, sitting just above the stop plate  100 . By using the live video recording the point in time at which the descent of the retrieval tool  10  stops can be observed. This is when the retrieval tool stop plate  100  makes contact with the waste package.  FIG. 7  shows a screen shot taken with the camera during a retrieval. Screen shots and video recordings can be recorded during the retrieval process for subsequent reference if required. 
         [0089]    Prior to lowering the retrieval tool  10  over a package, the compressor and vacuum system  32  is switched on to deflate the inflatable air wedges  18  to provide maximum clearance between the retrieval tool  10  and the waste package. At the point in which the retrieval tool  10  has reached its appropriate engagement distance into the tile hole, the inflatable air wedges  18  are inflated by actuating the valves shown in  FIG. 11  to the correct position. Pressure is set to provide a maximum value of 2.1 psig. Once the working pressure has been attained, the retrieval tool  10  is then lifted by approximately 1 foot at which point the actuator disc assembly  26  is lowered by releasing the latch  84 , via the latch release cable  86 , which is shortened by the use of the latch release tool  184  shown in  FIG. 22 . The latch release tool  184  is simply a fork at the end of a long handle. The fork part of the latch release tool  184  is placed such that the latch release cable  86  is in between the two prongs of the fork. By rotating the latch release tool  184 , the latch release cable  86  shortens and eventually the latch  84  pivots sufficiently to allow the actuator disc assembly  26  to drop via gravity. Since the safety bars  22  are connected to the actuator disc  26  they also drop. This allows the six safety bar horizontal arms  24  to tuck under the waste package to act as a back up support in case the waste package and/or its contents fall. The safety bars  22  are locked into their “open” position by using the wrench tool and following the reverse process outlined earlier. 
         [0090]    When the retrieval tool  10  is raised near to the surface, the contamination control bag  170  is hooked onto the retrieval tool  10  with a hand tool, and two cinch cords  176  are pulled in opposite directions to close the bottom of the contamination control bag  170  which is then tied in place. The waste package within the retrieval tool  10  is then transferred with the contamination control bag  170  still hooked to the retrieval tool  10  and is placed into an overpack container for further disposal. In case the wire leader has to be severed inside the tile hole the cutting tool  186  shown in  FIG. 24  was developed. In short, this device consists of a pair of wire cutters clamped to a length of rod. The wire cutters can be actuated by pulling on a length of wire cable that is fixed to a handle of the wire cutters, and is guided along the length of rod with suitable guides. 
         [0091]    Performance parameters for the described Mark II retrieval tool are as follows:
       load test using 50 kg. Slippage occurred at 1.4 psig. The decision was to use 2.1 psig for field work   Air pressure delivery system operation&lt;15 psig. A 10 psig over pressure valve has been incorporated into the equipment as per  FIG. 11     Volume of pressurized air=0.75 ft 3  (&lt;1.5 ft 3 )   Verification was carried out in tile hole array #31   Inflatable air wedges  18  use 4 inch nominal diameter hose   The retrieval tool  10  was fabricated to accommodate the retrieval of nine waste packages from a tile hole without having to reconfigure the retrieval tool  10     Safety bars  22  have been incorporated to provide a mechanical back-up system to support a waste package if the inflatable air wedges  18  cannot hold a waste package   Appropriate markings have been added to show vertical and radial positions of the safety bars  22     Inflatable air wedges  18  are retracted via the use of a vacuum pump to provide sufficient radial clearance   Easy to use tools have been employed to activate the safety bars  22  and retrieve wire during operation   Equipment was designed to be able to retrieve waste packages touching the tile hole wall   Lifting equipment followed ASME B30.20-2010 Category A Service Class 0 requirements   Equipment was designed to lift packages from tile holes without snagging by having no sharp edges on the outside edges of the retrieval tool   a mechanical stop  100  has been incorporated into the design   The equipment has been designed to ensure only one waste package can be retrieved at one time by using a stop plate inside the retrieval tool   retrieval tool designed for both plastic and steel containers   The retrieval tool  10  enables a waste package of 15 to 18 inches height to be retrieved by pre-setting the stop plate   The retrieval tool  10  enables a waste package of diameter 10 to 13 inches to be retrieved   The retrieval tool  10  has been designed to fit inside a tile hole of 14.775/15.225 inches in diameter   The retrieval tool  10  has been designed to fit inside a tile hole of 15 feet 11 inches in depth   A means to cut and remove wires attached to waste packages without damage to packages has been developed   Operation of retrieval tool  10  was designed to keep operators away from the tile hole opening using ALARA principles   The retrieval tool  10  incorporates a video camera  34     retrieval tool  10  has been designed to have a clearance fit inside the tile hole to prevent tool hang up       
 
       Testing for Validation and Training 
       [0116]    A number of commissioning tests were carried out. One of the commissioning tests included the ability of the air wedges to support a full load. A successful test was carried out and documented. This test assisted in setting the working pressure of the air wedges, set at 2.1 psig, and provided a significant safety factor for subsequent demonstrations and future development testing. 
         [0117]    The first meeting to demonstrate the Mark II retrieval tooling took place in Chalk River Laboratories B456 facility on 2011 Sep. 28. From the initial demonstration, a draft Operating Instruction was compiled and used for a number of subsequent demonstrations and training sessions led by the operations team that also involved riggers and crane operators. The feedback from all participants assisted in developing the Operating Instruction for the next phases of training and testing. 
         [0118]    The next phase of testing was carried out on a new tile hole using inactive packages on two separate days 2011 Sep. 22 and 29. When the retrieval tool was initially placed into the tile hole aperture it was noted there was not a significant amount of clearance between the outer part of the retrieval tool and the inside of the tile hole. With the aid of some rotation and shaking, the retrieval tool dropped into the tile hole and once past the entrance descended with ease. It was later noted that the entrance to the tile hole appeared to be reduced compared to the general diameter of the tile hole. 
         [0119]    There are up to nine packages contained within a tile hole and the designated numbering system is that package #1 is at the bottom and #9 is at the top of the tile hole. Packages #8 and #9 were removed with no unusual events and the decontamination control bag worked as expected. 
         [0120]    However, a problem did occur when retrieving waste package #7. It was observed that the retrieval tool would not drop sufficiently over waste package #7. Two likely reasons for this included:
   1. The eccentricity between the two pipes, that form the tile hole, restricted the effective working diameter within the tile hole.   2. The fingers of the retrieval tool which are used to move the waste package from the side of the tile hole surface got trapped in the interconnecting gap between the tile hole pipes.   
 
         [0123]    On 2011 Oct. 19, a series of five tiles holes located in a different array than that of the planned retrievals were opened and measured, the tile holes being found to have a narrower diameter than the design specification of the retrieval tool. Despite the discrepancy, the functionality of the retrieval tool was still found to be effective. The top of these tile holes ranged from 14.44″ diameter to 14.75″ diameter (below the minimum tolerance of 14.75″). The tool was then modified by grinding the heads of the screws on the periphery of the retrieval tool body, and the modified tool was then tried in each of the five tile holes. The tool entered three of the five tile holes without difficulty including the initial test hole, and was stopped halfway down one of the tile holes by a projecting lump of concrete spatter. 
         [0124]    It should be noted that the overriding objective was to validate the proof-of-concept tooling. The heart of the retrieval tooling is the application of inflatable surfaces to limit the radial forces acting on the waste containers and this aspect worked well. The issue of fitting the retrieval tool inside the tile hole can in part be accommodated by reducing the outside diameter of the retrieval tool if the retrieval tool is needed for future retrievals. 
         [0000]    The two main issues from field trials were:
       The clearance between the outside diameter of the retrieval tool  10  and the inside effective diameter of tile hole, and   The centering fingers catching in the gap between the two concrete pipes that form the tile hole.
 
Options to reduce the outside diameter of the retrieval tool  10  include the following:
 
For the short term:
   Grind off most of the heads of all of the protruding screws from the outer surface of the retrieval tool and retest in the same tile hole as per previous tests.
 
For the longer term:
   Use stronger material for the safety bars, e.g. austempered metal that offers 8 to 10 times more material strength. This will allow the safety bar diameter to be reduced from the current 0.5 inch diameter to 0.375 or even 0.25 inch diameter saving up to 0.5 inches on external diameter of the retrieval tool  10 .   Replace the protrusion of existing button head screws with another option e.g. rivets. Likely saving 0.25 inch on the outside diameter of the retrieval tool  10 .   Locate the collar connecting the lower and upper parts of the retrieval tool  10  on the inside of the retrieval tool  10  rather than on the outside as per the current design saving a further 0.25 inch on the outside diameter of the retrieval tool  10 .
 
Options to avoid “snagging” of the centering fingers include:
   Using a pole to gently pry the waste package from the surface of the tile hole wall. If the waste package can be moved, lower the retrieval tool  10  into place with safety bars open but not locked. This may allow the fingers to pass the tile hole joint.   Using the retrieval tool  10  to move the package from the wall of the tile hole wall, as per the current method, but gently pulling the waste package cable to aid centering of the waste package.       
 
       Mark III Version 
       [0133]    As noted above, the principles of the invention may be applied to various types of waste packages and tile hole arrangements. In this regard, a Mark III retrieval tool was developed to accommodate a slightly different, and more durable, type of waste package. Specifically, the Mark III design addresses a scenario where:
       the waste package in question is a metal bodied one, which is considerably more robust than the plastic ones lifted with the Mark II retrieval tool.   the lid of the waste package has a metal clasp which projects radially outwards from the body, increasing the effective diameter of the waste package.   The maximum waste package mass is 25 Kg, rather than the 50 Kg ones lifted by the Mark II retrieval tool.   The tile hole was fabricated from a metric series of concrete pipe, and is marginally (say ¼″) smaller.       
 
         [0138]    This scenario allowed the number of air wedges and safety bars to be reduced. It also allowed changes to be made to the opening into the retrieval tool, and the deflation system for the inflatable air wedges. These changes simplified the design of the retrieval tool and reduced the cost of fabrication. 
         [0139]    As shown in  FIGS. 25 to 27 , the number of inflatable air wedges  18  was reduced to three, and the number of rotatable safety bars  22 /safety bar horizontal arms  24  was reduced to three. The same size of inflatable hose was used as in the Mark II retrieval tool, with the three inflatable air wedges  18  spaced evenly around the circumference of the stainless steel cylinder  12 . Similarly, the three rotatable safety bars  22  were evenly spaced around the circumference of the stainless steel cylinder  12 . Although this decreased the percentage of surface area that is covered on the inside of the stainless steel cylinder  12 , the Mark III design was still found to be effective with the more robust waste containers. 
         [0140]    The issue of how much of the stainless steel cylinder  12  surface to cover with inflatable air wedges  18  is a matter of balancing the fragility of the waste package with the desire to reduce complexity. At one extreme a small number of inflatable air wedges  18  would result in a small number of higher pressure, discrete pressure points, while at the other extreme, a large coverage area of inflatable air wedges  18  would result in lower pressure, uniform loading. The Mark II was successful since it applied this uniform pressure, allowing the circular cross section of the waste package to act in like a masonry arch. All elements of the waste package were in uniform compression, so they did not fail. 
         [0141]    The Mark III scenario allows the luxury of a waste package which would allow discrete pressure points. Although the inflatable air wedges  18  in the Mark III design place compression forces at more discrete points, enough friction is established to lift the waste package without damaging it. 
         [0142]    Generally, the retrieval tool would be designed with a correlation between the number of inflatable air wedges  18  and the number of rotatable safety bars  22 . Typically, the same number of each would be used so that they do not interfere with one another, though one could use twice as many air wedges as safety rods, or vice versa. For example, one could place two inflatable air wedges between each safety rod. 
         [0143]    In the Mark III design, the triangular shaped metal fingers  20  were not used as it was found that using a stainless steel cylinder  12  with a tapered leading edge was sufficient and more practical. Since the waste packages are more robust for the Mark III retrieval tool, it was acceptable to use a greater force rather than finesse to get the retrieval tool over the waste package. Eliminating the triangular shaped metal fingers  20  reduces complexity, and makes the tool itself more robust. 
         [0144]    As shown in  FIGS. 26 and 27 , all of the components in the opening to the stainless steel cylinder  12  were designed with a tapered leading edge: the leading edge of the rotatable safety bars  22 , the safety bar horizontal arms  24 , and the cylinder strengthening members  190 . 
         [0145]    Finally, the use of a vacuum to collapse the inflatable air wedges was eliminated from the Mark III design in favour of a spring-loaded air wedge mounting design. As shown in  FIG. 27  and in the enlarged view of  FIG. 28 , the upper ends of the inflatable air wedges  18  were not bolted to the sides of the stainless steel cylinder  12  as in the case of the Mark II design. Rather, the clamps  192  on upper ends of the inflatable air wedges  18  were connected to spring loaded supports  194  providing a vertical pull on the inflatable air wedges  18 . This allows the length of the inflatable air wedges  18  to vary between the deflated to inflated conditions, eliminating the need for a sliding sleeve arrangement found in the Mark II design. When the flow of compressed air to the inflatable air wedges  18  is stopped and the inflatable air wedges  18  are allowed to deflate, the vertical pull from the spring loaded supports  194  will cause the inflatable air wedges  18  to flatten, forcing the air out of them. With this arrangement, it is not necessary to provide a vacuum pump. 
       Options and Alternatives 
       [0146]    Many variations to the described system are possible. Examples of variations include:
       changing the materials of construction;   allowing the air wedges to deflate naturally without applying a vacuum;   modifying the retrieval tool  10  to retrieve more than one waste package; and   making use of electric or pneumatic actuators to allow opening and closing of the rotatable safety bars  22  remotely.       
 
         [0151]    Other changes and variations also follow logically from the description herein, particularly to accommodate the design of specific tile holes and/or waste packages. 
       CONCLUSIONS 
       [0152]    One or more currently preferred embodiments have been described by way of example. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims. 
         [0000]    All citations are hereby incorporated by reference.