Search

EP-3642850-B1 - SYSTEM AND METHOD FOR VOLUME REDUCTION OF NUCLEAR REACTOR COMPONENTS

EP3642850B1EP 3642850 B1EP3642850 B1EP 3642850B1EP-3642850-B1

Inventors

  • DEADMAN, Jason

Dates

Publication Date
20260506
Application Date
20180605

Claims (15)

  1. A volume reduction system (110, 210) for reducing a volume of nuclear reactor components, the volume reduction system being provided, when in use, within a vault of a nuclear reactor, and comprising: a feed unit (114, 214) configured to receive a component from a nuclear reactor, wherein the component includes a radioactive tube (32, 36), and wherein the feed unit (114, 214) is configured to grip an inside and/or outside surface of the radioactive tube (32, 36) and move the radioactive tube (32, 36) to a segmenting unit (118, 218) located in proximity to the feed unit; the segmenting unit (118, 218) configured to receive the radioactive tube (32, 36) from the feed unit (114, 214), the segmenting unit (118, 218) including a cutting element (130) that segments the radioactive tube (32, 36) into segmented pieces; and a shredder unit (142, 242) configured to receive the segmented pieces of the radioactive tube (32, 36) and shred the segmented pieces of the radioactive tube (32, 36); wherein the shredder unit (142, 242) includes a plurality of shredding elements (146, 246), wherein the shredding elements (146, 246) are shaped and sized and made of material strong enough to grasp, pull, and shred the segmented pieces of the radioactive tube (32, 36).
  2. The volume reduction system (110, 210) of claim 1, wherein the radioactive tube is a pressure tube (36).
  3. The volume reduction system (110, 210) of either of claims 1 and 2, wherein the feed unit (114, 214) includes a gripping structure to grip a surface of the radioactive tube (32, 36); optionally wherein the gripping structure includes at least one finger that extends radially and presses against the interior surface of the radioactive tube (32, 36).
  4. The volume reduction system (110, 210) of claim 3, wherein the feed unit (114, 214) includes a retraction unit having a retraction plug, wherein the retraction plug includes the at least one finger, and wherein the feed unit (114, 214) further includes a feeder assembly (54) having at least a further finger that grips an exterior surface of the radioactive tube (32, 36).
  5. The volume reduction system (110, 210) of any of claims 1 to 4, wherein the radioactive tube (32, 36) is a first tube, wherein the cutting element (130) is shaped and sized and made of a material strong enough to simultaneously cut through and segment both the first tube as well as a second tube disposed within the first tube.
  6. The volume reduction system (110, 210) of either of claims 1 or 2, wherein the cutting element (130) is a metal blade.
  7. The volume reduction system (110, 210) of either of claims 1 and 2, wherein the cutting element (130) is configured to move along a direction that is transverse to a longitudinal direction of the radioactive tube (32, 36), so as to radially cut through and segment the radioactive tube (32, 36); wherein the segmenting unit (118, 218) includes a drive element coupled to the cutting element (130), and a controller coupled to the drive element (134), wherein the controller (138) is configured to control the drive element (134) so that the cutting element (130) cuts and segments the radioactive tube (32, 36) into at least two pieces; and wherein the feed unit (114, 214) is configured to slow movement of the radioactive tube (32, 36) prior to the radioactive tube (32, 36) being segmented by the segmenting unit (118, 218).
  8. The volume reduction system (118, 218) of either of claims 1 and 2, wherein each of the shredding elements (146, 246) includes a projection (150); and wherein a first one of the shredding elements (146, 246) includes a first projection having a first shape, and wherein a second one of the shredding elements (146, 246) includes a second projection having a second shape, wherein the first shape is different than the second shape.
  9. The volume reduction system (110, 210) of claim 8, wherein a first one of the shredding elements (146, 246) rotates about a first axis, and a second one of the shredding elements (146, 246) rotates about a second axis, wherein the first axis is offset relative to the second axis.
  10. The volume reduction system (110, 210) of either of claims 8 and 9, wherein the shredding elements (146, 246) are positioned on four separate axes, wherein the two of the four axes are laterally offset from the other two axes, such that the four axes form four corners of a trapezoid; and wherein a first one of the shredding elements (146, 246) rotates in a first direction, and a second one of the shredding elements (146, 246) rotates in a second direction, wherein the first direction is different than the second direction.
  11. The volume reduction system (110, 210) of any of the preceding claims, further comprising a fire suppression system (400), wherein the fire suppression system (400) includes a nozzle disposed adjacent the shredder unit (142, 242) to emit fire-retardant material.
  12. A method for reducing, within the vault of a nuclear reactor, the volume of a nuclear reactor component, said method comprising: removing a component from a nuclear reactor, wherein the component includes a radioactive tube (32, 36); gripping an inside and/or outside surface of the component with a feed unit (114, 214); moving the component with the feed unit (114, 214) to a segmenting unit (118, 218) located in proximity to the feed unit (114, 214); cutting and segmenting the component into segmented pieces with a cutting element (130) in the segmenting unit (118, 218); and shredding the component with a shredding unit (142, 242), wherein the shredding unit (142, 242) shreds the segmented pieces.
  13. The method of claim 12, wherein the component includes a radioactive pressure tube (36).
  14. The method of either of claims 12 or 13, wherein the step of cutting and segmenting includes moving a metal blade to cut through the component, optionally wherein the step of cutting and segmenting includes decelerating the component prior to cutting the component with the metal blade; wherein the step of shredding the segmented pieces includes rotating a plurality of shredding elements (146, 246) about a plurality of offset axes to grasp and pull and shred the segmented pieces.
  15. The method of any of claims 12 to 14, wherein the component includes two tubes, wherein one of the tubes is disposed within the other tube; both of the two tubes are moved with the feed unit to the segmenting unit (118, 218); and the two tubes are simultaneously cut and segmented into segmented pieces with the cutting element (130) in the segmenting unit (118, 218).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims all benefit including priority to United States Provisional Patent Application 62/524,098, entitled "SYSTEM AND METHOD FOR VOLUME REDUCTION OF NUCLEAR REACTOR COMPONENTS", and filed June 23, 2017; and Romanian Patent Application a 2018 00140 , filed February 28, 2018. FIELD OF THE INVENTION Embodiments described herein relate to volume reduction systems for processing nuclear reactor components. BACKGROUND A nuclear reactor has a limited life of operation. For example, second generation CANDU™-type reactors ("CANada Deuterium Uranium") are designed to operate for approximately 25 to 30 years. After this time, the existing fuel channels can be removed and new fuel channels can be installed. Performing this "retubing" process can extend the life of a reactor significantly, as an alternative to decommissioning the reactor. Nuclear reactor retubing processes include removal of a large number of reactor components and include various other activities, such as shutting down the reactor, preparing the vault, and installing material handling equipment and various platforms and equipment supports. The removal process can also include removing closure plugs and positioning hardware assemblies, disconnecting feeder assemblies, severing bellows, and removing end fittings. The removal process can also include the removal and disposal of highly radioactive pressure tubes and calandria tubes from the reactor core. Removal and/or disposal of these tubes, as well as other components of the nuclear reactor, may take considerable time and effort. After the removal process is complete, an inspection and installation process is typically performed. For example, tube sheets positioned at each end of the reactor may include a plurality of bores. Each of the plurality of bores supports a fuel channel assembly that spans between the tube sheets. When a fuel channel assembly is removed, each tube sheet bore is inspected to ensure that the removal of the fuel channel assembly has not damaged the tube sheet bore and that the tube sheet bore is ready for insertion of a new fuel channel assembly. After the tube sheets are confirmed to be in suitable condition, calandria tubes, pressure tubes, end fittings, and other components can be installed back into the bores. For each fuel channel assembly, part of this process involves rolling the end of the calandria tube to the tube sheet of the calandria (e.g., using a deformable calandria insert), inserting an end fitting body into the bore, rolling the end of the pressure tube into the end fitting body, and inserting an end fitting liner into the end fitting. JP 2004 361113 A discloses a disassembly method for pressure tube of advanced thermal reactor. CA 2 766 459 A1 discloses calandria tube, pressure tube, and annulus spacers removal apparatus and method for nuclear reactor retubing. WO 2007/083401 A1 discloses a method for dismantling heat exchanger installed in building for nuclear reactor. WO 2015/197528 A1 discloses an installation and method for fragmenting at least one tube, preferably a radiologically contaminated tube. US 6 523 466 B1 discloses a checkerboard shear volume reduction system. JP 2005 161277 A discloses crushing apparatus and a method of crushing by crushing apparatus. SUMMARY The invention is defined in the independent claims. Further aspects and preferred embodiments are defined in the dependent claims. Any aspects, embodiments and examples of the present disclosure which do not fall under the scope of the appended claims do not form part of the invention and are merely provided for illustrative purposes. In some embodiments, a volume reduction system for nuclear reactor components is provided. The system includes a feed unit to receive a radioactive tube from a nuclear reactor, and a segmenting unit to receive the tube from the feed unit. The segmenting unit includes a cutting element that segments the tube into segmented pieces. The system also includes a shredder unit to receive segmented pieces of the tube and shred the segmented pieces. Some embodiments provide a method for reducing the volume of a nuclear reactor component, including removing the component from the nuclear reactor, moving the component with a feed unit to a segmenting unit, cutting and segmenting the component into segmented pieces with a cutting element in the segmenting unit, and shredding the segmented pieces with a shredding unit. In some embodiments, a method for reducing the volume of nuclear reactor tubes is provided, and comprises removing two tubes from the nuclear reactor, where one of the tubes is disposed within the other tube. The method also includes moving the two tubes with a feed unit to a segmenting unit, cutting and segmenting the two tubes simultaneously into segmented pieces with a cutting element in the segmenting unit, and shredding the segmented pieces with a shredding unit. In some embodiments, a volume redu