HK1069669B - Checkerboard shear volume reduction system and method - Google Patents

Description

Checkerboard shear volume reduction system and method

Technical Field

The present invention relates to a method and apparatus for volume reduction and disposal of materials, the main field of application relating to irradiated radioactive materials. More particularly, the present invention relates to methods and apparatus for removing, handling and disposing of pressure and heating tubes from CANDU * nuclear reactors.

Background

To extend the operating life of a CANDU * nuclear reactor, extensive fuel line replacement must be undertaken. One critical step in the large scale replacement of fuel piping is the removal of the highly radioactive pressure and heating tubes from the reactor core.

The conventional procedure involves taking the pressure and heating tubes, about 6 meters long, out in one piece or cutting them into two sections at their mid-points. On one side in the direction of movement of the guide tube, no people are allowed around the reactor dome (thermal vault), which makes it impossible to deploy the work in parallel and thus slows down the progress of the work. A very large and bulky lead-filled vessel is used to transport the pressure tube out of the reactor dome for disposal. Passing such sized vessels through the containment structure of a CANDU * type nuclear reactor is a difficult and time consuming task, requires cranes or other heavy material handling equipment, and requires the evacuation of personnel from the work area. This disrupts the proper operation of materials, equipment and personnel, resulting in overall reactor downtime and significant loss in work scheduling and orchestration considerations. It is therefore desirable to make the method of removing and disposing of pressure and heating tubes more economical and attractive.

Disclosure of Invention

The present invention provides a method and apparatus for reducing the volume of a cylindrical catheter for disposal by crushing flat and then shearing into small slices. The shearing operation is preferably performed on a checkerboard grid formed by a plurality of intersecting planes, and the resulting slices are preferably substantially square.

According to the present invention there is provided apparatus for reducing the disposal volume of an elongate cylindrical conduit, comprising a pair of inwardly opposed modules, means for moving said modules between open and closed positions and transport means for placing the ends of said cylindrical conduit between the modules in the open position, each said module comprising a set of raised cutters and depressed recesses, each said cutter on one of the modules being adapted to be closely received within an opposed recess on the other module as said module is moved from the open position to the closed position to sequentially compress said ends into a substantially flat configuration and cut them into a plurality of slices.

According to another aspect of the present invention there is provided apparatus for reducing the disposal volume of irradiated radionuclide reactor cylindrical conduits, comprising a movable mounting base adapted to be operatively located adjacent to a reactor surface at a selected conduit location; a transport unit mounted on said base for holding said selected conduit and advancing it out of the reactor; a hold-down assembly mounted on said base, including a pair of inwardly opposed die blocks and means for moving said die blocks between open and closed positions, said die blocks being arranged to receive said selected conduit therebetween in the open position, each of said die blocks including a set of raised cutters and recessed pockets, each cutter on one of said die blocks being adapted to be closely received in an opposed pocket on the other die block, whereby said ends are sequentially squeezed into a substantially flat configuration and sheared into a plurality of slices as said die blocks are moved from the open position to the closed position.

According to yet another aspect of the present invention, there is provided a method for reducing the treated volume of an elongate cylindrical catheter, comprising: (a) placing the ends of the cylindrical conduit between a pair of inwardly opposed modules, the modules being movable between an open position and a closed position, each of the modules including a set of raised cutters and recessed pockets, each cutter on one of the modules being adapted to be closely received within an opposed pocket on the other module when the modules are moved from the open position to the closed position; (b) moving the die block from the open position to the closed position to sequentially extrude the ends into a substantially flat configuration and cut them into a plurality of cut pieces; and (c) repeating steps (a) and (b) until the cylindrical tube is cut into slices.

According to yet another aspect of the present invention, there is provided a method for reducing the disposal volume of irradiated radionuclide reactor cylindrical conduits, comprising: (a) engaging an end of a selected one of the conduits at the reactor surface and advancing a portion of the selected conduit out of the reactor; (b) placing the ends of the cylindrical conduit between a pair of inwardly opposed modules, the modules being movable between an open position and a closed position, each of the modules including a set of raised cutters and recessed pockets, each cutter on one of the modules being adapted to be closely received within an opposed pocket on the other module when the modules are moved from the open position to the closed position; (c) moving the die block from the open position to the closed position to sequentially extrude the ends into a substantially flat configuration and cut them into a plurality of cut pieces; and (d) repeating steps (b) and (c) until the cylindrical tube is cut into slices.

The invention, both as to organization and method of operation, will best be understood by reference to the following description of specific embodiments when read in conjunction with the accompanying drawings.

Drawings

FIG. 1 is a perspective view of one embodiment of a treatment volume reduction system of the present invention.

FIG. 2 is a perspective view of a press assembly.

Fig. 3 is a front view of the press assembly.

FIG. 4 is a perspective view showing the arrangement of checkerboard modules and cutters.

FIG. 5 is a perspective view of the retraction unit.

Fig. 6 is a cross-sectional side view of the retraction plug.

Fig. 7 is a perspective view of the delivery assembly.

FIG. 8 is a partial cross-sectional elevation view of the delivery assembly.

Fig. 9 is a cross-sectional front view of the flash assembly during unloading.

Detailed Description

Referring to fig. 1, a checkerboard shear volume reduction system of the present invention is shown. The system includes a retraction unit 100, a hold down assembly 200, a transport assembly 300, and a containment assembly 400. The pressure tube volume reduction system is mounted on a work platform 500, the work platform 500 being capable of horizontal lateral movement to move between grid points (lattice sites), capable of inward/outward movement to move towards and away from a grid area (the lattice sheet), and capable of vertical movement to move up and down relative to the grid area. The cylindrical pressure tube 10 is shown in figure 1 in a position for volume reduction.

Referring now to fig. 2 and 3, the press assembly 200 is shown in greater detail. The press assembly 200 includes a base 202 and an end plate 204. The end plates 204 are held in relative fixed relation by a box frame 208, a bottom plate 201, and parallel tie plates (struts) 210. Tie plates 210 are bolted at the four corners of the box frame 208.

Hydraulic cylinder 214 is fixedly mounted to end plate 204 with piston rod 218 extending inwardly from end plate 204. Piston rods 218 are connected at their distal ends to a platen 220 (placen) by cylinder bolts 222. The platen 220 is bolted to the module 226. Modules 226 are mounted on guide rods 212 by bores 224 at their four corners and are adapted to slide horizontally back and forth under the control of hydraulic cylinder 214. The opposing module 226 is carried on an inward facing surface of the platen 220. Module 226 contains a set of staggered tool steel shear blades, the details of which can be seen in fig. 4.

Referring now to FIG. 4, the detailed construction of the module 226 can be seen. Each module 226 is machined with a checkerboard pattern of raised cutters 228 and depressed grooves 230 containing ejectors 232 in the grooves 230. When brought into face-to-face relationship, the tab cutters 228 on one opposing module 226 are received in recesses 230 in the other opposing module 226 that contain ejectors 232. Although the checkerboard pattern shown in FIG. 4 comprises 4X 8 rows of alternating raised cutters 228 and depressed recesses 230, it should be understood that other patterns may be selected depending on the size and shape of the cylindrical material to be processed.

The inwardly facing surface 229 of the cutter 228 is surrounded by a cutting edge 231. The contour of the surface 229 is such that the midpoints of the respective upper and lower edges 231 project. The inwardly facing surface of the ejector 232 is inclined to facilitate ejection of the material.

The distance that knives 228 project inwardly from module 226 decreases uniformly across the surface of module 226. In particular, cutters 228 closer to a side 260 on the module 226, which side 262 is located at an edge closer to the reactor surface, protrude inward a greater distance than cutters 228 closer to a side 262 on the module 226, which side 260 is farther away from the reactor surface. As a result, the spacing between the opposed knives 228 and the flutes 230 that are farther from the reactor surface is smaller than the opposed knives 228 and flutes 230 that are closer to the reactor surface. Thus, the pressing and shearing operations will be carried out in sequence starting from the end of the cylindrical conduit 10 and proceeding towards the reactor surface.

Referring again to fig. 3, the ejector 232 includes rods 240, which rods 240 extend through horizontal bores 242 in the module 226. The vertically aligned pairs of ejector rods 240 are connected at their ends to an inverted "L" shaped ejector rail 238, the ejector rail 238 being carried in an elongated slot on the module 226. A lower rail stop 244 is disposed horizontally on the upper surface of base 202 below module 226 and an upper rail stop 246 is disposed horizontally on the inward facing surface of end plate 204. The ejector rails 238 are machined so that their ends mate with rail stops 244 and 246. As modules 226 move away from each other as hydraulic cylinders 214 retract, ejection rods 240 and ejection bars 238 move toward end plate 204 until ejection bars 238 engage lower bar stops 244 and upper bar stops 246. Continued retraction of hydraulic cylinder 214 will pull module 226 between rail stops 244 and 246 while ejector rail 238 remains seated against rail stops 244 and 246. This relative movement of the module 226 and the ejector rail 238 causes the ejector 232 to be forced outwardly in the recess 230 on the module 226 to clear any uncut cut material. Ejector 232 may be manually operated to assist in removing the jammed material from module 226.

The hold-down assembly 200 also includes a lower door 250 mounted just below the modules 226 and above the containment assembly 400. The door 250 is driven by a hydraulic cylinder 252 and linkage 254 and serves two primary purposes. First, they keep all of the crushed/sheared material within the pressing zone throughout the pressing/shearing operation to ensure that volume reduction is accomplished. Second, they provide a means for closing the opening under the hold-down assembly 200 during container exchange. This mitigates potential contamination spreading, prevents small pressure tube fragments from falling out of the system during a container change, and allows a container change with the pressure tube inside the volume reduction unit in the recovery mode. For purposes of illustration, one door 250 is shown in an open position while the other door is in a closed position. It will be appreciated that in practice, both doors 250 are moved simultaneously to the closed position during the shearing process and that in order to allow the sheared material to be discharged, both doors 250 are moved simultaneously to the open position.

Referring now to FIG. 5, the retraction unit assembly 100 is shown in greater detail. The retraction unit assembly 100 is used to initially pull the pressure tube into the volume reduction system for processing. Retraction unit 100 is mounted immediately outside of press assembly 200 and includes retraction plug 110, chain case 160, drive motor 170, and hydraulic hose reel 180. The chain case 160 includes a Serapid^TMA chain 162, the chain 162 being driven in either direction by a drive motor 170. Serapid^TMChain 162 is a machine chain that can flex in only one direction, allowing it to be used in either tension or compression. Due to Serapid^TMChains 162 may support tensile and compressive loads, which may be used to pull the pressure tube out of the tube or, in some unthreading situations (under back-outconducting), push the pressure tube back into the tube.

The retract plug 110 is mounted on a Serapid^TMAt the end of the chain 162. When it is Serapid^TMAs chain 162 is extended by drive motor 170, retraction plug 110 advances through gap 234 between opposing modules 226 in press assembly 200, through transport assembly 300, and into the end of the pressure tube to be removed.

As shown in fig. 6, the retracting plug 110 includes a nose 112, the nose 112 being sized to be closely received within the end of the pressure tube to be removed. The fingers 114 are fixedly mounted in radially disposed hydraulic pistons 116. A hydraulic piston 116 is disposed within a radially disposed cylinder bore 118 machined into nose 112. Hydraulic line 126 extends from hose reel 180 to cylinder bore 118. When the retract plug 110 is engaged in the end of the pressure tube to be removed, hydraulic pressure is applied to the hydraulic cylinder bore 118, and the hydraulic piston 116 and fingers 114 extend radially outward to match the pressure to be removedThe inner side wall of the pipe is clamped and matched. The ends 124 of the fingers 114 may be beveled, pointed, or otherwise surface treated to improve the ability to mate with the pressure tube. Nose 112 is axially secured to retraction plug base 130 by means of thrust bearing 132 and nut 134. The nose 112 is able to rotate about its axis relative to the retraction plug base 130 to rotate the pressure tube during retraction from the reactor. Oil channel groove 136 and O-ring 138 are used to hydraulically connect across a rotational interface 140 between nose 112 and retract plug 130. The transfer block 150 transfers the Serapid^TMA chain 162 is connected to retraction plug base 130.

Referring now to fig. 7 and 8, the delivery assembly 300 is shown in greater detail. The transport assembly 300 includes a carriage 302 that is slidably mounted for reversible longitudinal movement on a linear guide 304. The carriage 302 is driven on the guide rails 304 by a ball screw 306 rotated by an electric motor 308. Jaws 310 are disposed horizontally above and below the longitudinal axis of the pressure tube being treated. The jaws 310 are driven by two racks 312 with a single common pinion 314, the pinion 314 being driven by a hydraulic cylinder 318. The pinion gear 314 is mounted on a ball spline 316 so that it travels with the carriage 302 under load.

After each compression/shearing cycle, the transport assembly 300 is used to transport pressure tubes from the reactor surface into the press assembly 200. This feeding movement is achieved by driving the carriage 302 by means of the motor 308 to its inner position (i.e. towards the reactor surface) and closing the jaws 310 onto the outside of the pressure tube. The carriage 302 is then driven in the opposite direction, placing the end of the pressure tube within the press assembly 200. The jaws 310 act vertically, allowing them to enter the press assembly and hold the pressure tube in place until the knife 228 makes contact therewith. The return can be assisted by manually driving the pressure tube delivery jaw 310 and carriage 302 via the ball screw 306 and hydraulic cylinder carriage 322.

A wiper 320 is mounted on the lower jaw 310 and is used to sweep into the receptacle any debris that may collect in the area of the conveyor assembly.

Referring now to FIG. 9, containment assembly 400 is shown in greater detail. The containment assembly 400 includes a cylindrical vessel 402 and a cylindrical liner 404. A top loading door 406 is positioned on a top wall 408 of the container 402 for horizontal sliding. The top-loading door 406 may be opened by sliding it by appropriate control (e.g., hydraulic pressure) to expose a longitudinal rectangular opening 410 directly beneath the area of the module 226. The cut pieces cut by the action of the module 226 fall through the opening 410 and into the liner 404.

Liner 404 is a single-use (disposable) container made of stainless steel. Once the liner 404 is filled with slices, the liner 404 is removed from the container 402 for permanent disposal. Liner 404 is mounted within container 402 and is captured by disposal door (disposal door) 412. A disposal door 412 is disposed at the bottom of the container 402 for horizontal sliding. The disposal door 412 may be opened by sliding it by appropriate control, such as hydraulic pressure, to expose a circular opening 416 near the underside of the liner 404.

The container 402 is first transferred from the volume reduction system of the present invention to the processing region 430. The liner disposal tool 420 includes a lifting rod 422 that is removably attached at a lower end to a top wall 424 of the liner 404 using a suitable means, such as a threaded fit. The lift rods 422 pass through openings in the top wall 408 and are connected at their upper ends by cross bars 426. The liner 404 is disposed of by attachment to the lifting bar 422, lifting the liner 404 by lifting the cross bar 426 at the lifting eye 428, sliding the disposal door 412 open, and lowering the liner 404 into the disposal area. A new liner 404 may then be lifted into the container 402 and the container reassembled into the volume reduction system of the present invention. The size of the container can be varied to meet shielding requirements and effective lifting capabilities of the work platform.

The working process of the invention is controlled by a PLC-based control device, and the PLC-based control device is programmed to automatically run programs and is provided with a linkage device to prevent the out-of-sequence phenomenon. The main control station is located in the reactor vault, but far from the highest radiation field. It will be possible to remotely manually control all functions. A satellite control panel may be provided adjacent the volume reduction unit.

The operation of the pressure tube volume reduction system of the present invention will now be described. All end fittings and feed devices are removed before the pressure tube volume reduction process is initiated. Work can be performed on the respective reactor surfaces simultaneously. The volume reduction system is mounted on a work platform and the control station is built into the reactor dome. The grid-like conduit and the bellows-like boot are mounted on all channels with temporary grid-like conduit shielding plugs (or equivalent).

An empty containment assembly 400 is loaded onto the volume reduction device. Once the position of the channel is determined, the volume reduction system will be aligned with the channel and the grid-like conduit shield plug removed. The volume reduction system is finally aligned with the channel and locked onto the channel using any standard mechanical latch on the grid-like catheter sheath. Serapid^TMChain 162 is driven forward by hydraulic motor 170, thereby moving retraction plug 110 forward and inserting it into the end of the pressure tube. Fingers 114 co-operating with the end of the pressure tube, Serapid^TMChain 162 is driven in the opposite direction so that the end of the pressure tube moves back through gap 234 between modules 226. Carriage 302 is driven to the forward inboard limit (the forward inboard limit) and pressure tube delivery jaws 310 are closed to grip the pressure tube. The lower compression door 250 is closed. Fingers 114 are retracted out of engagement with the pressure tube, and Serapid^TMChain 162 is driven further in the opposite direction to move retract plug 110 out of gap 324. The modules 226 are driven together to a fully closed position. This would result in 147/16 inches being located in the gap 234The long pressure tubes are first crushed flat between the inward facing surfaces 229 and then sheared by the cutter 228 into 21/16 inch square slices while the pressure tubes remain centered on the grid points on the reactor during operation. The lower hold down door 250 is opened and the module 226 is fully opened to eject all pressure tube slices through the opening 410 into the vessel 402.

The carriage 302 is driven away from the reactor surface until the end of the pressure tube is again placed between the modules 226. The lower compression door 250 is closed and the modules 226 are driven together to a 50% closed position. The pressure tube delivery jaws 310 are then opened and the module 226 is fully closed while the carriage 302 is driven to the maximum inboard position. The pressure tube delivery jaw 310 is closed to retain the pressure tube and the lower hold down door 250 is opened. Module 226 is fully opened to eject all pressure tube slices into vessel 402.

The pressing/clamping cycle is repeated until the entire pressure tube is processed into slices. Thereafter, the system is disengaged from the channel, the grid-like conduit shield plug is replaced, the number of processed pressure tubes in the vessel is confirmed, and the volume reduction system is aligned with and locked onto the next channel to be processed.

Once the container 402 is full, it is disengaged from the volume reduction system and lifted off the work platform. An empty container is then installed below the volume reduction system and the operation continues until all pressure tubes have been processed.

The internal volume of the volume reduction system, including the internal volumes of the pressing assembly and the transport assembly, is maintained at a slight negative pressure to prevent the spread of contamination by any oxide dust or other fine particles that are generated. A shielded filter device is used to collect the active dust.

The step-wise operation carried out by the method of the invention allows stopping at any time for a long time and restarting at any time. This helps to cope with maintenance or malfunction, and accidents such as power outages, shift changes or non-volume reduction related interruptions.

The retraction unit 100, press assembly 200 and transport assembly 300 are all of a modular design to allow for quick field replacement of individual subsystems, rather than replacement of the entire apparatus, thereby reducing the spread of contamination and time lapsed due to maintenance. Since all hydraulic cylinders, electric motors and other actuators are externally shielded, the radioactive pressure tubes can be repaired or replaced if necessary with their presence in the volume reduction system. This allows for repair or maintenance activities to be performed in the event of a failure while radioactive material is still present in the system. This greatly simplifies recovery since the radioactive pressure tube does not need to be removed for repair or maintenance operations using a screw-out device. Furthermore, the compact modular design of the volume reduction system in the present invention allows its components to be easily equipped with shields. The top shield member can be seen above the press and feed assembly in fig. 1, but if the drawing is for illustration purposes, it is omitted from a balance perspective.

As previously mentioned, the volume reduction system of the present invention uses a combination of flattening of the pressure tube and shearing on a checkerboard grid formed by multiple intersecting planes. The compression operation typically causes the pressure tube to break cleanly along its side perpendicular to the compressive force, dividing the pressure tube into two sections that remain intact. A smooth transition from the crushed to the uncrushed region is immediately created within the die block 226. The material after high-grade radiation has considerable material property change. For pressure tubes of the Zr-2.5% Nb type, this aspect involves an increase in the ultimate tensile strength and a reduction in the overall elongation (ductility).

The surface profile of the cutter 228 forms a cutting edge that produces a progressive shearing action that reduces the maximum shear force required. In addition, the varying length of cutter 228 projecting inwardly from module 226 provides a sequential shearing action, with cutters closer to the end of the pressure tube acting earlier than cutters farther away from the end of the pressure tube. This also reduces the maximum shear force. It should be understood that surface profiles other than that shown in fig. 3 may be used and that the spacing of the opposed cutters may be varied to reduce the maximum shear force. Also, the cutters 228 need not be square, but may be configured to produce cut sheets having other shapes.

The single step extrusion and shearing process of the present invention for reducing pressure tubes into small flat sections has many advantages. It has minimal material handling requirements, so that no additional equipment is required to contain the irradiated waste material, and no subsequent handling of the material is required. The slices can simply fall randomly into the container, avoiding the complexity and potential risks of the system that would otherwise require a mechanism for aligning or stacking the material. This simplifies the design work, eliminates possible failure modes and maintains a compact overall size. Second, the form of the waste material does not constrain the size or shape of the subsequently shielded container, thereby allowing the optimal container size and shape to be selected to receive the desired amount of material to optimize material handling, weighing, transportation, disposal, and storage issues. For example, the reduction in the total volume of waste material allows the use of a smaller and lighter shielded container to transport them to the disposal site, thereby speeding up the overall removal/disposal task, making it more economically viable. The volume reduction system of the present invention is compact and lightweight enough for field use in a variety of applications while still being completely shielded so that personnel may be present at or near the facility.

Although the volume reduction system of the present invention has been described for use with pressure tubes, it may also be used to remove and handle heating tubes or other hollow cylindrical members having various cross-sectional shapes. Removal of the heating tube can be performed separately from the pressure tube or simultaneously. Thus, the stroke of the delivery dogs 310 and the stroke of the module 226 can be set to accommodate larger diameter heating tubes. Further scaling may also be applied to systems that process other components. The checkerboard shear technique of the present invention is capable of handling components having a large thickness (proven to be feasible for components up to 10 mm in thickness) and is easily scalable to match the requirements of the application field. The volume reduction system of the present invention may have other commercial applications, such as refurbishment and/or decommissioning of radioactive sites, and for volume reduction of non-radioactive components in non-nuclear industries, such as the waste management industry.

Claims (33)

1. An apparatus for reducing the disposal volume of an elongate cylindrical conduit comprising a pair of inwardly opposed modules, means for moving the modules between open and closed positions and transport means for placing the ends of the cylindrical conduit between the modules in the open position, each of the modules comprising a set of raised cutters and depressed recesses, each of the cutters on one of the modules being adapted to be closely received within an opposed recess on the other module as the module is moved from the open position to the closed position, thereby in turn compressing the ends into a flat configuration and shearing them into a multiplicity of slices.

2. The apparatus of claim 1, wherein: each of the cutters has an inwardly facing surface for press-fitting with the cylindrical member and a cutting edge surrounding the surface, the cutting edge being profiled to enable cutting of one of the slices with a progressive shearing action.

3. The apparatus of claim 2, wherein: the cutting edge is square.

4. The apparatus of claim 2, wherein: the spacing between the cutting edges on the knives and the respective opposing grooves varies along the array such that the slices are sequentially cut as the module moves from the open position to the closed position.

5. The apparatus of claim 2, wherein: the spacing between the cutting edges on the knives and the respective opposed flutes increases progressively along the array so that slices are cut sequentially from the end of the cylindrical conduit.

6. The apparatus of claim 1 including ejection means in each of said recesses for ejecting the cut slices.

7. The apparatus of claim 6, wherein: the ejector is actuated in response to movement of the module from the closed position to the open position.

8. The apparatus of claim 7, wherein: each of the modules is mounted for movement relative to a fixed support, the support including a stop means, the ejector including an elongate fixed member slidably mounted through the module and extending between the recess and an outer side of the module, an outer end of the ejector being arranged to engage the stop means when the module is moved from the closed position to the open position so that the other end extends into the recess and into contact with the cut sheet.

9. The apparatus of claim 1, wherein: the module is moved between open and closed positions using hydraulic cylinders mounted on the fixed support.

10. An apparatus for reducing the treated volume of an irradiated radionuclide reactor cylindrical conduit, comprising:

a movable mounting base adapted to be operatively positioned adjacent to a reactor surface at a selected conduit location;

a transport unit mounted on said base for holding said selected conduit and advancing it out of the reactor;

a pressing assembly mounted on said base, including a pair of inwardly opposed die blocks and means for moving said die blocks between open and closed positions, said die blocks being arranged to receive said selected conduit therebetween in the open position, each of said die blocks including a set of raised cutters and recessed pockets, each cutter on one of said die blocks being adapted to be closely received in an opposed pocket on the other die block, whereby said ends are sequentially squeezed into a flat configuration and sheared into a plurality of slices as said die blocks are moved from the open position to the closed position.

11. The apparatus of claim 10, further comprising a retraction unit mounted on said base for gripping an end of said selected conduit and pulling it from the reactor surface into an operatively gripped position by said transport device.

12. The apparatus of claim 10, further comprising a removable container located below the module for receiving the cut-off slices.

13. The apparatus of claim 12, further comprising a gate device located below the hold down assembly and above the container, the gate device being selectively movable from a closed position for receiving the cut-off slice to an open position for discharging the slice into the removable container.

14. The apparatus of claim 10, wherein: each of the cutters has an inwardly facing surface for press-fitting with the cylindrical member and a cutting edge surrounding the surface, the cutting edge being profiled to enable cutting of one of the slices with a progressive shearing action.

15. The apparatus of claim 14, wherein: the cutting edge is square.

16. The apparatus of claim 14, wherein: the spacing between the cutting edges on the knives and the respective opposing grooves varies along the array such that the slices are sequentially cut as the module moves from the open position to the closed position.

17. The apparatus of claim 14, wherein: the spacing between the cutting edges on the knives and the respective opposed flutes increases progressively along the array so that slices are cut sequentially from the end of the cylindrical conduit.

18. The apparatus of claim 10 including an ejector in each of said recesses for ejecting the cut slices.

19. The apparatus of claim 18, wherein: the ejector is actuated in response to movement of the module from the closed position to the open position.

20. The apparatus of claim 19 including a stop means secured to said base, said ejector means including an elongated fixed member slidably mounted through said module and extending between said recess and an outer side of said module, an outer end of said ejector means being arranged to engage said stop means when said module is moved from a closed position to an open position whereby the other end extends into said recess to contact said cut sheet.

21. The apparatus of claim 10, wherein: the module is moved between open and closed positions using hydraulic cylinders mounted on the fixed support.

22. A method for reducing a treated volume of an elongate cylindrical catheter, comprising:

(a) placing the ends of the cylindrical conduit between a pair of inwardly opposed modules, the modules being movable between an open position and a closed position, each of the modules including a set of raised cutters and recessed pockets, each cutter on one of the modules being adapted to be closely received within an opposed pocket on the other module when the modules are moved from the open position to the closed position;

(b) moving the die block from an open position to a closed position to sequentially extrude the ends into a flattened configuration and shear them into a plurality of cut pieces;

(c) repeating steps (a) and (b) until the cylindrical tube is cut into sections.

23. The method as recited in claim 22, wherein: each of the cutters has an inwardly facing surface for press-fitting with the cylindrical member and a cutting edge surrounding the surface, the cutting edge being profiled to enable cutting of one of the slices with a progressive shearing action.

24. The method as set forth in claim 23, wherein: the cutting edge is square.

25. The method as set forth in claim 23, wherein: the spacing between the cutting edges on the knives and the respective opposing grooves varies along the array such that the slices are sequentially cut as the module moves from the open position to the closed position.

26. The method as set forth in claim 23, wherein: the spacing between the cutting edges on the knives and the respective opposed flutes increases progressively along the array so that slices are cut sequentially from the end of the cylindrical conduit.

27. A method for reducing a disposal volume of an irradiated radionuclide reactor cylindrical conduit, comprising:

(a) engaging an end of a selected one of the conduits at the reactor surface and advancing a portion of the selected conduit out of the reactor;

(b) placing the ends of the cylindrical conduit between a pair of inwardly opposed modules, the modules being movable between an open position and a closed position, each of the modules including a set of raised cutters and recessed pockets, each cutter on one of the modules being adapted to be closely received within an opposed pocket on the other module when the modules are moved from the open position to the closed position;

(c) moving the die block from an open position to a closed position to sequentially extrude the ends into a flattened configuration and shear them into a plurality of cut pieces;

(d) repeating steps (b) and (c) until the cylindrical tube is cut into sections.

28. The method as recited in claim 27, wherein: each of the cutters has an inwardly facing surface for press-fitting with the cylindrical member and a cutting edge surrounding the surface, the cutting edge being profiled to enable cutting of one of the slices with a progressive shearing action.

29. The method as recited in claim 28, wherein: the cutting edge is square.

30. The method as recited in claim 28, wherein: the spacing between the cutting edges on the knives and the respective opposing grooves varies along the array such that the slices are sequentially cut as the module moves from the open position to the closed position.

31. The method as recited in claim 28, wherein: the spacing between the cutting edges on the knives and the respective opposed flutes increases progressively along the array so that slices are cut sequentially from the end of the cylindrical conduit.

32. The method as recited in claim 27, wherein: the module is moved between the open and closed positions using a hydraulic cylinder.

33. The method of claim 30, comprising receiving the cut-out slices in a container located below the module.