System and method for removing calandria from a nuclear reactor

Abstract

A method of segmenting a calandria within vault of a nuclear reactor is provided. The method comprises: providing at least one cutting tool; cutting a portion of the vault to form an opening; forming a shielded volume defined by a shielding wall, the vault, and end shields of the calandria, the shielding wall configured to absorb radiation from within the shielded volume; segmenting a shell and internal components of the calandria within the shielded volume; and removing the shell and internal components of the calandria from the shielded volume. Optionally, a filler, such as concrete, may be used to immobilize the calandria. Once the calandria shell and internal components are removed the end shields may be segmented or detached from the vault and transferred intact by positioning the tube sheet potion of each end shield against each other.

Description

SYSTEM AND METHOD FOR REMOVING CALANDRIA FROM A NUCLEAR REACTORCROSS REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

[0001] The present application claims priority to U.S. provisional patent application no. 63 / 602,540 filed on November 24, 2023, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD

[0002] The disclosure relates generally to decommissioning a nuclear reactor, and more particularly to removing a calandria at end of life.BACKGROUND

[0003] A nuclear reactor has a limited operational life. For example, second generation CANDUTM-type reactors (“CANada Deuterium Uranium”) are designed to operate for approximately 25 to 30 years. After this time, nuclear reactor may in some instances be decommissioned. Nuclear reactor decommissioning 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, removing end fittings, releasing and removing calandria tube inserts, severing and removing pressure tubes, removing calandria tube, and removing the calandria. Many of the components that are removed may radioactive and require special handling.SUMMARY

[0004] In an aspect, the disclosure describes a method of segmenting a calandria within vault of a nuclear reactor, the method comprising: providing at least one cutting tool; cutting a portion of the vault to form an opening with one of the at least one cutting tool; forming a shielded volume defined by a shielding wall, , the vault, and end shields of the calandria, the shielding wall configured to absorb radiation from within the shielded volume, optionally the shielding wall covers the opening; segmenting a shell and internal components of the calandria within the shielded volume; and removing the shell and internal components of the calandria from the shielded volume.

[0005] In an embodiment, the method comprises removing shielding ball bearings from between the end shield and a calandria side tube sheet; segmenting the calandria side tube sheet; removing lattice tubes from the end shield; and segmentation of the end shield. The method may comprise filling the calandria with a filler for supporting the calandria and absorbing radiation; wherein the portion of the vault cut by the at least one cutting tool is the reactivity mechanism deck. Alternatively, the method may comprise filling a portion of the shielded volume, and the calandria, with a filler to support the calandria and to absorb radiation emitted from the calandria; segmenting the end shields within the shielded volume, wherein the shielding wall comprises shielding blocks defining the surface of the end shields; and removing the end shields from the shielded volume. In an example, the filler is light weight concrete having an oven-dry density of not less than 800 kg / m3and not more than 2000 kg / m3. In another example, segmenting the shell and the internal components of the calandria within the shielded volume comprises: peeling the calandria shell off the filler; and segmenting the internal components.

[0006] In an embodiment, the method comprises positioning a transporter under the calandria; and removing the shell and internal components of the calandria from the shielded volume with the transporter.

[0007] In an embodiment, the method comprises decoupling the end shields from the vault; and positioning one of the end shields on top of the other end shield on a transporter. The method may also comprise positioning one of the end shields on top of the other end shield, comprises positioning a tube sheet portion of one of the end shields against a tube sheet potion of the other end shield.

[0008] In an embodiment, the method comprises inserting at least one cutting channel through the calandria, each of the at least one cutting channel defining a volume for receiving one of the at least one cutting tool; filling a portion of the shielded volume, and the calandria, with a filler to support the calandria and to absorb radiation emitted from the calandria, optionally the filler is concrete; cutting a portion of the vault to form an opening with the at least one cutting tool, wherein the portion of the vault is the reactivity mechanism desk; segmenting the end shields within the shielded volume. The filler may be light weight concrete having an oven-dry density in a range of 800 kg / m3to 2000 kg / m3.

[0009] The method of any one of claims 13, wherein the at least one cutting tool comprises a wire cutting tool having a cutting wire extending into the cutting channel, the method comprising cutting through the cutting channel and the filler.

[0010] In an embodiment, the method comprises drilling core openings into the filler along a core opening axis; inserting the at least one cutting tool into the at least one cutting channel; cutting at least one of the filler and the calandria along a first plane connecting the core opening axis and an axis of one of the at least one cutting channels; cutting at least one of the filler and the calandria laterally from the axis of the one of the at least one cutting channels to define a second plane, the first and second planes intersecting to segment a portion of the filler. In an example, the portion has a substantially quadrilateral cross-section. In another example, the cutting at least one of the filler and the calandria laterally from the at least one cutting channels may comprise: inserting a cutting tool into a first lattice tube; cutting at least one of the filler and the calandria along the second plane intersecting the first lattice tube and a second lattice tube. In another example, the cutting at least one of the filler and the calandria laterally from the at least one cutting channels may comprise: cutting the filler between adjacent fuel channels, wherein the second plane does not intersect a lattice tube of the calandria.

[0011] In an embodiment, the method comprises inserting the at least one cutting tool into the cutting channel to segment the calandria, internal components of the calandria, and end shields.

[0012] Embodiments may include combinations of the above features.

[0013] In another aspect, the disclosure describes a method of removing a calandria from a vault of a nuclear reactor, the method comprising: providing at least one cutting tool; cutting a portion of the vault with the at least one cutting tool; positioning the calandria on a transporter; moving the calandria out of the vault; positioning a shielding liner over a shell of the calandria; and filling the shielding liner with filler for immobilizing the calandria within the liner.

[0014] In an embodiment, the filler is concrete.

[0015] In an embodiment, the method comprises positioning a first portion of the shielding liner on the transporter before the calandria is positioned on the transporter, positioning a second portion of the shielding liner on the calandria after the calandria ispositioned on the transporter, and coupling the first and second portions of the shielding liner to define the calandria within the shielding liner.

[0016] Embodiments may include combinations of the above features.

[0017] In another aspect, the disclosure describes a method of segmenting a calandria within vault of a nuclear reactor. The method comprises: providing at least one cutting tool; sealing each of a plurality of lattice tubes of the vault with sealing members; forming a shielding volume defined by the vault and end shields of the calandria; filling a portion of the shielded volume with water to submerge the calandria, with water; cutting a portion of the reactivity mechanism desk to form an opening with the at least one cutting tool; segmenting the calandria, internal components of the calandria, and tube sheets of the end shields within the shielded volume within a volume of the water; removing the calandria, internal components of the calandria, and tube sheets of the end shields from the vault.

[0018] In an embodiment, the sealing members are at least one of plugs and welding plates.

[0019] In an embodiment, the tube sheets are the calandria side tube sheets.

[0020] In an embodiment, the method comprises removing the water, the segmenting the end shields.

[0021] In an embodiment, the segmenting the calandria, internal components of the calandria, and tube sheets of the end shield comprises: providing a crate configured to receive segmented nuclear components of nuclear reactor, the crate having a plurality of holes for draining water; positioning segmented portions of at least one of the calandria, the internal components of the calandria, and the tube sheets of the end shield, in the crate; positioning a shielded cover over the crate, the shielded cover configured to receive the crate and provide radiation shielding for the segmented components in the crate; lifting the create out of the water; draining the water from the crate; drying the segmented components; positioning the dried segmented components into a container for transport to an to external storage facility.

[0022] Embodiments may include combinations of the above features.

[0023] In another aspect, the disclosure describes a system for handling radioactive waste. The system comprises: a crane configured to move a crate into and out of a vault of a nuclear reactor, the vault filled with water; the crate configured to receive segmented nuclear components of nuclear reactor, the crate defining at least one opening for draining water; a shielded cover configured to receive the crate and provided radiation shielding for the segmented components in the crate; a dryer configured to evaporate water from the segmented components; and a container for transporting the segmented components from the dryer.

[0024] In an embodiment, the dryer is at lease one of an infrared heater, black-body radiation heater, resistance power heater, convection heater.

[0025] Embodiments may include combinations of the above features.

[0026] Further details of these and other aspects of the subject matter of this application will be apparent from the detailed description included below and the drawings.DESCRIPTION OF THE DRAWINGS

[0027] Reference is now made to the accompanying drawings, in which:

[0028] FIG. 1 is a perspective view of a CANDU™-type reactor.

[0029] FIG. 2A is a cutaway view of a CANDUTM-type nuclear reactor fuel channel assembly.

[0030] FIG. 2B is a perspective view of a platform, work table and a calandria tube insert removal tool adjacent a face of the CANDU™-type reactor, according to an embodiment.

[0031] FIG. 3 is a schematic view of an example cutting tool inserted into a calandria vessel of the reactor shown in FIG. 1.

[0032] FIG. 4 is a schematic view of an example method of dismantling a nuclear reactor.

[0033] FIG. 5A is a front elevation view of an example calandria wrapped in overpacking. FIG. 5B is a side elevation view of the example calandria wrapped in overpacking shown in FIG. 5A.

[0034] FIG. 6 is a schematic view of another example method of dismantling a nuclear reactor.

[0035] FIG. 7 is a schematic view of another example method of dismantling a nuclear reactor.

[0036] FIG. 8 is a schematic view of another example method of dismantling a nuclear reactor.

[0037] FIG. 9 is an elevation view of example end shields stacked on a transporter.

[0038] FIG. 10 is a schematic view of another example method of dismantling a nuclear reactor.

[0039] FIG. 11 A is a front cut away view of a calandria inside a vault of a nuclear reactor. FIG. 11 B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 11A.

[0040] FIG. 12 is a side cut away view of the calandria inside a vault of a nuclear reactor shown in FIG. 11A where a portion of the vault is removed.

[0041] FIG. 13A is a front cut away view of the calandria inside the vault of a nuclear reactor shown in FIG. 11A illustrating cutting the calandria shell. FIG. 13B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 13A.

[0042] FIG. 14 is a front cut away view of the calandria inside the vault of a nuclear reactor shown in FIG. 13A showing segmentation of the calandria shell.

[0043] FIG. 15A is a side cut away view of the calandria inside the vault of a nuclear reactor shown in FIG. 14 after the calandria shell has been removed. FIG. 15B is a side cut away view of the calandria inside the vault shown in FIG. 15A with a portion of the end shields removed.

[0044] FIG. 16 illustrates a schematic view of another example method of dismantling a nuclear reactor.

[0045] FIG. 17 illustrates a side cut away view of the calandria inside the vault of a nuclear reactor with cutting channels 16 installed vertically through calandria 10.

[0046] FIG. 18A shows is a front cut away view of a calandria inside a vault of a nuclear reactor. FIG. 11 B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 18A. FIG. 110 is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 18A with cores drilled sections the vault.

[0047] FIG. 19A illustrates a front cut way view of a calandria inside a vault of a nuclear reactor shown in FIG. 18A with the reactivity mechanisms deck removed.

[0048] FIG. 19B is an enlarged fragmentary view of an example segmented portion of the calandria shown in FIG. 19A.

[0049] FIG. 19C is an enlarged fragmentary view of another example segmented portion of the calandria shown in FIG. 19A.

[0050] FIG. 19D shows an example cutting tool exterior to a calandria.

[0051] FIG. 19E illustrates movement paths of example cutting tools and waste container trolleys.

[0052] FIG. 20 illustrates a schematic view of another example method of dismantling a nuclear reactor.

[0053] FIG. 21 illustrates an example system for drying and packing radioactive waste.DETAILED DESCRIPTION

[0054] Before any embodiments are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.DEFINITIONS

[0055] Although terms such as “maximize”, “minimize” and “optimize” may be used in the present disclosure, it should be understood that such term may be used to refer to improvements, tuning and refinements which may not be strictly limited to maximal, minimal or optimal.

[0056] The term “connected” or "coupled to" may include both direct coupling (in which two elements that are coupled to each other and contact each other) and indirect coupling (in which at least one additional element is located between the two elements).

[0057] The term “substantially” as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

[0058] Terms such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0059] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and / or" means any one of the items, any combination of the items, or all of the items with which this term is associated.

[0060] The term "about" can refer to a variation of± 5%, ± 10%, ± 20%, or± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and / or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0061] The “radioactive waste”, “radioactive material”, and “radioactive components” includes “Low-Level Radioactive Waste (LLW) and Intermediate-level radioactive waste (ILW).

[0062] The term “Low-Level Radioactive Waste (LLW) can refer to radioactive waste having a dose rate less than 10 mSv / h (1 rem / h) at 30 cm (unshielded). LLW consists of minimally radioactive material that has become contaminated with radionuclides.

[0063] The term Intermediate-level radioactive waste (ILW) can refer to radioactive waste having a dose rate greater than or equal to 10 mSv / h (1 rem / h) at 30 cm (unshielded). ILW consists primarily of used reactor core components, ion exchange columns, resins, and filters used to keep the reactor water system clean. ILW is more radioactive than LLW, and requires shielding to protect workers during handling.

[0064] Aspects of various embodiments are described through reference to the drawings.

[0065] FIG. 1 is a perspective of a reactor core of a CANDU™-type reactor 6. The reactor core is typically contained within a vault that is sealed with an air lock for radiation control and shielding. Although aspects are described with particular reference to the CANDU™- type reactor 6 for convenience, the disclosure is not limited to CANDUTM-type reactors,and may be useful outside this particular field as well. A substantially cylindrical vessel, known as the calandria vessel 10 of the CANDUTM-type reactor 6, contains a heavy-water moderator. The calandria vessel 10 has an annular shell 14 and a tube sheet 18 at a first end 22 and a second end 24. The tube sheets 18 include a plurality of apertures (referred to herein as bores 19) that each accept a fuel channel assembly 28. As shown in FIG. 1 , a number of fuel channel assemblies 28 pass through the tube sheets 18 of calandria vessel 10 from the first end 22 to the second end 24.

[0066] As in the illustrated embodiment of Figs. 1 and 2A, in some embodiments the reactor core is provided with two walls at each end 22, 24 of the reactor core: an inner wall defined by the tube sheet 18, also referred to as a calandria side tube sheet, at each end 22, 24 of the reactor core, and an outer wall 64 (often referred to as a “end shield” or “fueling machine side tube sheet”) located a distance outboard from the tube sheet 18 at each end 22, 24 of the reactor core. A lattice tube 65 spans the distance between the tube sheet 18 and the end shield 64 at each pair of bores 19 (i.e., in the tube sheet 18 and the end shield 64, respectively).

[0067] FIG. 2A is a cutaway view of one fuel channel assembly 28 of the reactor core illustrated in FIG. 1. As illustrated in FIG. 2A, each fuel channel assembly 28 includes a calandria tube (“CT”) 32 surrounding other components of the fuel channel assembly 28. The CTs 32 each span the distance between the tube sheets 18. Also, the opposite ends of each CT 32 are received within and sealed to respective bores 19 in the tube sheets 18. In some embodiments, a rolled joint insert, for example calandria tube insert 34, is used to secure the CT 32 to the tube sheet 18 within the bores 19. A pressure tube (“PT”) 36 forms an inner wall of the fuel channel assembly 28. The PT 36 provides a conduit for reactor coolant and fuel bundles or assemblies 40. The PT 36, for example, generally holds two or more fuel assemblies 40, and acts as a conduit for reactor coolant that passes through each fuel assembly 40. An annulus space 44 is defined by a gap between each PT 36 and its corresponding CT 32. The annulus space 44 is normally filled with a circulating gas, such as dry carbon dioxide, helium, nitrogen, air, or mixtures thereof. One or more annulus spacers or garter springs 48 are disposed between the CT 32 and PT 36. The annulus spacers 48 maintain the gap between the PT 36 and the corresponding CT 32, while allowing passage of annulus gas through and around the annulus spacers

[0068] As also shown in FIG. 2A, each end of each fuel channel assembly 28 is provided with an end fitting assembly 50 located outside of the corresponding tube sheet 18. Each end fitting assembly 50 includes an end fitting body 57 and an end fitting liner 58. At the terminal end of each end fitting assembly 50 is a closure plug 52. Each end fitting assembly 50 also includes a feeder assembly 54. The feeder assemblies 54 feed reactor coolant into or remove reactor coolant from the PTs 36 via feeder tubes 59 (FIG. 1). In particular, for a single fuel channel assembly 28, the feeder assembly 54 on one end of the fuel channel assembly 28 acts as an inlet feeder, and the feeder assembly 54 on the opposite end of the fuel channel assembly 28 acts as an outlet feeder. As shown in FIG. 2A, the feeder assemblies 54 can be attached to the end fitting assemblies 50 using a coupling assembly 56 including a number of screws, washers, seals, and / or other types of connectors. The lattice tube 65 (described above) encases the connection between the end fitting assembly 50 and the PT 36 containing the fuel assemblies 40. Shielding ball bearings 66 and cooling water surround the exterior of the lattice tubes 65, which provides additional radiation shielding.

[0069] A positioning hardware assembly 60 and bellows 62 are also coupled to each end fitting assembly 50. The bellows 62 allows the fuel channel assemblies 28 to move axially - a capability that can be important where fuel channel assemblies 28 experience changes in length over time, which is common in many reactors. The positioning hardware assemblies 60 can be used to set an end of a fuel channel assembly 28 in either a locked configuration that fixes the axial position, or an unlocked configuration. The positioning hardware assemblies 60 are also coupled to the end shield 64. The illustrated positioning hardware assemblies 60 each include a rod having an end that is received in a bore of the respective end shield 64. In some embodiments, the rod end and the bore in the end shield 64 are threaded. Again, it should be understood that although a CANDUTM-type reactor is illustrated in FIGS. 1-2A, the invention may also apply to other types of reactors, including reactors having components that are similar to those illustrated in FIGS. 1-2A.

[0070] FIG. 2B illustrates one embodiment of a heavy work table (“HWT”) 96 installed on a tooling platform (“RTP”) 95 adjacent the end 24 of the nuclear reactor. A similar HWT can be installed adjacent the end 22 of the nuclear reactor. The HWT 96 and any tools mounted on the HWT are controlled by a control station (not shown).

[0071] As shown in FIG. 3, A calandria cutting tool 100 may be mounted on the HWT 96 and is positioned to remove calandria tube inserts 34 from tube sheet 18 at the end 24. The control of the position of the calandria cutting tool 100 with respect to the end shield 64 and operation of the tool 100 may occur from the control station. Specifically, the operator can control the height of the RTP 95 along axis Y, the location of the cutting tool 100 on the HWT 96 along axis X and the pitch with respect to the end shield 64 to orient axis Z to be perpendicular to the end shield 64. In some embodiments, the height of RTP 95 may be adjusted by ball screws, for example, by way of one ball screw at each corner of RTP 95.

[0072] When the cutting tool 100 is aligned with the selected opening in the end shield 64, the operator can insert the calandria cutting tool 100 into the appropriate fuel channel along axis Z. The cutting tool 100 can include any number of suitable sensors and / or cameras to verify that the cutting tool 100 is properly aligned with the respective opening in the end shield 64. Once inserted, cutting tool 100 may commence cutting operations as described below. Due to the high radiation fields in calandria vessel 10, all cut operations may be performed remotely. As such, a controller 300 may be provided for controlling the movement cutting tool 100, worktable 96, platform 95, gripper 103, moveable contamination barrier 104, etc. In an example, cutting tool 100 may a cutting tool described in International Patent Application No. PCT / CA2024 / 051259, the entire contents of which are hereby incorporated by reference.

[0073] FIG. 3 illustrates a schematic view of cutting tool 100 inserted into calandria vessel 10. Calandria 10 comprises an A-face opposing a C-face, each having an end shield 64. Lateral sides of calandria 10 are referred to as D-face and B-face (not shown). As shown in FIG. 3, cutting tool 100 may be position on worktable 96 on platform 95. Crane 101 may be provided for handling of segmented calandria vessel 10 pieces and may be installed on the Reactivity Mechanisms (RM) Deck 102. A gripper 103 may extend from RM Deck 102 which can be deployed inside calandria vault 11 to grip segmented portions of calandria vessel 10. Gripper 103 may extend into vault 11 through holes cut in the vault 11 to permit access to calandria 10. In some embodiment, Gripper 103 may extend into vault 11 and calandria vessel 10 through ports in reactivity mechanism deck 102 which allow vertical access to calandria vessel 10. In an example the ports may include the viewing port, liquid zone control unit port, flux detector port, liquid injection shut downnozzle, reactivity control unit nozzles, etc. Cutting calandria vessel 10 inside vault 11 may allow containment of debris and / or cutting by-products, such as dust and particles, from migrating outside vault 11. During operation of cutting tool 100, the interior of vault 11 may be kept at vacuum pressure relative to the exterior of vault 11 , e.g. by an active ventilation system (not shown).

[0074] As cutting tool 100 cuts / segments components of calandria vessel 10, gripper 103 may couple to the segmented components and move them to waste collection container 106. Remotely controlled demolition robots (not shown) may also be positioned inside the calandria vault 11 to assist in handling of the segmented portion of calandria vessel10. Holes may also be cut by cutting tool 100 in calandria vessel 10 for handling segmented pieces of calandria vessel 10. Cutting tool 100 may cut calandria vessel 10 using cutting techniques such as plasma arc, laser, waterjet, milling, etc.

[0075] In an embodiment, contamination barriers 104, such as a movable shielding wall or shielding door, may be installed to shield a bottom portion of the calandria vault 11 after it is opened. Contamination barrier 104 may be made from a material that reduces or prevents radioactivity from passing through the barrier. Barrier 104 may be installed prior to demolishing process. When necessary (during removal of segmented portion of calandria vessel 10 from inside calandria vault 11), to isolate the operating area, existing shielding walls between Fueling Machine (FM) Maintenance rooms and Transfer corridor could be activated. As an alternative, large shielding doors between FM Room and FM Maintenance rooms could be activated. In an embodiment, before the calandria vault 11 is drained, contamination barrier 104 may be installed.

[0076] To access the inside of calandria vault 11 , a wall of calandria vault 11 may be removed. Barrier 104 may be installed prior to demolishing of the wall of calandria vault11.

[0077] As described above, platform 95 may be installed on both reactor faces to provide Y-direction movements for the tools installed on it. Worktable 96 may be installed on the platform 95 to provide X-direction movements for the tools installed on it.

[0078] A transporter, e.g. a waste collection trolley 105 may be positioned inside vault 11 underneath of calandria 10. Waste collection containers 106, such as waste transfer flasks, may be positioned on trolley 105 to collect segmented pieces. During segmentingof calandria 10, barrier 104 may be positioned to close the opening in vault 11. When container 106 is full, barrier 104 may be moved / opened such that container 106 may be moved out to a segmentation room, where waste may be further segmented, assayed, and packed.

[0079] Example methods of dismantling a nuclear reactor are described below. In some embodiments, internal components of calandria 10 are removed initially and then vault 11 and remaining components of calandria 10 may be segmented, removed from reactor building, and transported to a storage facility. In other embodiments, Calandria 10 may be dismanted by removing Calandria 10 with all internal pipes as a whole from the Calandria Vault.

[0080] FIG. 4 illustrates a schematic view of an example method 400 of dismantling a nuclear reactor. Specifically, method 400 removes the calandria end shields, and shell intact as a unitary assembly from vault 11. In this embodiment, calandria 10 is radiation shielded for transport by installing the steel liner over calandria 10, in particular the calandria shell, and the liner is filled with concrete. Once removed from the nuclear reactor, the concrete filled liner containing calandria 10 may be buried or stored as is in a permanent storage facility. This approach may minimize formation of radioactive particulate otherwise formed by segmenting radioactive components of the calandria. Additionally, the more radioactive components of calandria 10 remain between the end shields and calandria shell which provide protection against radiation egress during transport of calandria 10.

[0081] As shown in FIG. 4, at block 401 method 400 may comprise setting up tools for operation in the reactor building (RB) enclosure, e.g. positioning cutting tool 100 within RG enclosure. Reactor building RB maybe maintained at negative pressure to relative to the surrounding environment to mitigate against contamination, such as dust and debris, from leaving reactor building RB. At block 402, concrete portions of vault 11 surrounding end shields 64 may be segmented and removed to provide access to the end shield. Concrete below the end shield may be left in place until jacks 41 are installed to support the weight of calandria 10 at block 403. Concrete around bottom of end shields 64 may be removed such that calandria is suspended above a gap as shown at block 404. Calandria vault floor may be cleaned at block 405 and transporter 42, e.g. a self- propelled Modular Transporter (SPMT), may be positioned under calandria 10 at block406. The travel path of transporter 42 may be reinforced to allow for the gross weight of the transporter, the calandria, and other materials positioned on the transporter. Jacks 42 may lower calandria 10 onto transporter 42 at block 407 and be removed at block 408. In another embodiment, transporter 42 may be used as a jacking system whereby the transporter may be raised to support the weight of calandria 10 until concrete portions of vault 11 under calandria 10 are dismantled. As vault 11 is dismantled, the new openings can be used to cut and remove pipes and pipe stands connecting calandria 10 to vault 11. At block 409, transporter 42 may the move caldaria 10 out of vault 11 in a room R- 108 of the reactor building; and at block 410 a shielding liner 43 may be positioned over calandria 10. At block 411 , optionally, calandria 10 may be filled with a filler. Filler may be a material used to secure internal components of calandria 10 and / or stabilize a shell 14 of calandria 10 for transport. In an example, the filler may be light weight concrete having an oven-dry density of not less than 800 kg / m3and not more than 2000 kg / m3. Other types of concrete or filler may be used to secure internal component of the calandria and / or stabilize shell 14 of calandria 10. At block 412, shielding liner 43 may also be filled with concrete, including a gap between shielding liner 43 and calandria shell 14 and / or an inside of calandria shell 14. At block 413, the reactor building may be cleaned and decontaminated. At block 414, shielding liner 43 containing calandria 10 may be moved out of the reactor building, and at block 415 the shielding liner 43 containing calandria 10 may be transported to a storage facility.

[0082] FIG. 5A and 5B shows front and side elevation views of an example calandria wrapped in overpacking. Overpack 51 may be positioned on calandria 10 after it is removed from vault 11. Overpack 51 comprise several subassemblies. Lower portion 51a of overpack 51 may be positioned on transporter 42 prior to calandria 10 being lowered onto transporter 42 and installed around calandria 10 when vault 11 is open and calandria 10 is positioned on transporter 42. Upper portion 51b of the overpack 51 may be installed outside or inside reactor building RB after calandria 10 is positioned on lower portion 51a of overpack. In an example, as calandria 10 is moved out of vault 11 on transporter, upper portion 51b of overpack may be installed. Overpack 51 may be filled with concrete and left to cure. In an embodiment, overpack 51 is shielding liner 43 which is made of material configured to reduce radiation transmission through the overpack. For example, shielding liner may be lead, steel, or other suitable material.

[0083] FIG. 6 illustrates a schematic view of an example method 600 of dismantling a nuclear reactor. In the illustrated method, calandria 10 is removed with all internal pipes as a whole vault 11 . Calandria 10 may be shielded by installing a liner, e.g. a steal liner, over the Calandria vessel and filling it with concrete. Subsequently, the calandria 10 may be stored in a temporary nuclear waste storage facility. When the radioactive decay reaches an acceptable level, calandria 10 may be segmented, packed, and transferred to a permanent storage facility.

[0084] As shown in FIG. 6, at block 601 method 600 may comprise setting up tools for operation in the reactor building (RB) enclosure, e.g. positioning cutting tool 100 within RG enclosure. Rector building RB maybe maintained at negative pressure to relative to the surrounding environment to mitigate against contamination, such as dust and debris, from leaving reactor building RB. At block 602, concrete portions of vault 11 surrounding end shields 64 may be segmented and removed to provide access to the end shield. At block 603, concrete below the end shield may be left in place until jacks 41 are installed to support the weight of calandria 10. At block 604, concrete around bottom of end shields 64 may be removed such that calandria is suspended above a gap. At block 605, calandria vault floor may be cleaned, at block 606 transporter 42, e.g. a Self-propelled Modular Transporter (SPMT), may be positioned under calandria 10. The travel path of transporter 42 may be reinforced to allow for the gross weight of the transporter, the calandria, and other materials positioned on the transporter. At block 607, jacks 42 may lower calandria 10 onto transporter 42 and be removed at block 608. In another embodiment, transporter 42 may be used as a jacking system whereby the transporter may be raised to support the weight of calandria 10 until concrete portions of vault 11 under calandria 10 are dismantled. As vault 11 is dismantled, the new openings can be used to cut and remove pipes and pipe stands connecting calandria 10 to vault 11. At block 609, transporter 42 may the move caldaria 10 out of vault 11 to a room R-108 of the reactor building. At block 610 a shielding liner 43 may be positioned over calandria 10. Shielding liner 43 may be overpacking described above with respect to FIGs 5A and 5B. At block 611 , optionally, calandria 10 may be filled with a filler. Filler may be a material used to secure internal components of calandria 10 and / or stabilize a shell 14 of calandria 10 for transport. At block 612, shielding liner 43 may also be filled with concrete, including filling a gap between shielding liner 43 and calandria shell 14 with concreteand / or filling an inside of calandria shell 14 with concrete. At block 613, the reactor building may be cleaned and decontaminated. At block 614, shielding liner 43 containing calandria 10 may be moved out of the reactor building, and at block 615 the shielding liner 43 containing calandria 10 may be transported to a temporary storage facility. At block 616, after radioactivity decay of calandria 10 has reached a desired amount, calandria 10 may be segmented and packed. At block 617, calandria 10 may be transported to a permanent storage facility.

[0085] FIG. 7 illustrates a schematic view of an example method 700 of dismantling a nuclear reactor. As shown, the dismantling method involves segmentation of calandria shell 14 followed by removal of the end shields as a whole. Cutting tool 100 may be used to cut internal components of calandria 10, e.g. by inserting cutting tool 100 though lattice sites. Calandria shell 14 may also be segmented from the inside using cutting tool 100. The size of segmented portions of calandria shell 14 may be determined based on available waste containers, crane capacity etc. Segmented portions of calandria shell 14 may be collected on a transported positioned inside the calandria vault. The transporter may travel out of the vault through the opened vault wall for packing and to transfer segmented pieces of calandria for further processing. End shields may be removed as one piece, whole, and un-segmented. End shields of calandria define shielding ball bearings 66 within the end shields which are well packed assemblies minimizing the volume of the shielding ball bearings. Once end shields are cut out from the vault, the end shield may be stacked such that the radioactive calandria tubesheets are shielded by the structure of the end shields. By keeping end shields of calandria in their operating position, coupled to the vault, while components of the calandria between the end shields are segmented, the end shields may provide protection against radiation and a contained environment within which the segmentation can take place.

[0086] As shown in FIG. 7, method 700 may comprise setting up tools for operation in the reactor building (RB) enclosure, e.g. positioning cutting tool 100 within RB enclosure. Remotely controlled robots maybe positioned in reactor building and / or cranes may perform handling operations. Additional handling equipment may installed in the reactivity mechanism deck area to assist in handling of segmented / cut calandria pieces. Reactor building RB and / or vault maybe maintained at negative pressure to relative to the surrounding environment to mitigate against contamination, such as dust and debris,from leaving reactor building RB and / or vault. At block 701 , shielding wall 71 may be installed under A-face of end shield 64. As access to calandria vault may be required to collect segmented / cut pieces of the Calandria 10, and associated moderator pipes 67, shielding wall 71 may be movable shielding doors to shield the working area and while providing access to vault 11 .

[0087] At block 702, a portion of vault 11 under end shield 64 maybe removed at any one of the faces of the reactor. As shown, in FIG. 7, the gap may be formed in A- or C- face (also shown in FIG. 3); however, the gap may also be formed in the D-face or B-face. At block 703, a gap may be formed under calandria 10 inside vault 11 such that calandria is suspended above the gap. At block 704, transporter 42, e.g. a trolley or Self-propelled Modular Transporter (SPMT), may be positioned under calandria 10 as shown. The travel path of transporter 42 may be reinforced to allow for the gross weight of the transporter, the calandria, and other materials positioned on the transporter. At block 705, calandria shell 14 may be segmented by cutting tool 100, and removed from vault 11 , and packed at block 706. At block 707, a portion of vault 11 , e.g. under C-face of end shield may be removed. The portion of vault 11 removed may be on another side of the vault 11 , e.g. on any of A-face, B-face, or D-face. At block 708, support members 43 maybe coupled to both A-face and C-face of end shields 64 to support each end shield for transport on transporter 42 and to prevent both A-face and C-face from tipping over. At block 709, the remainder of vault 11 around end shields 64 at A-face and C-face maybe removed, and at block 710, each end shield 64 maybe positioned on transporter 42 defining tubesheets between the opposing end shield faces. At block 711 , end shields 64 and segmented portions of calandria 10 may be transported to a permanent storage facility.

[0088] As shown in FIG. 8, after end shields 64 are separated from vault 11 , A-face end shield may be positioned horizontally on transporter 42 using crane 101 gripper 103, and / or other supporting / rigging equipment. C-face end shield may be positioned on top of A-face end shield or vice-versa. Each end shields may be positioned with tube sheet 18 portion of end shield facing inward toward the opposing end shield to define the radioactive components of the contaminated tube sheets 18 between the exterior portions of end shields 64. This orientation utilizes the shielding properties of end shield 64 to mitigate radiation from the tube sheet 18.

[0089] FIG. 9 illustrates a schematic view of an example method 900 of dismantling a nuclear reactor. As shown, the dismantling method involves segmentation of calandria shell 14 followed by segmentation of end shields 64 in-situ. Active components, such as internal piping and thimbles, within calandria shell 14 may be initially removed by accessing though lattice sites in end shields 64. As shown, the dismantling method involves segmentation of calandria shell 14 followed by segmentation and removal of the end shields in-situ. Cutting tool 100 may be used to cut internal components of calandria 10, e.g. by inserting cutting tool 100 though lattice sites. Calandria shell 14 may also be segmented from the inside using cutting tool 100. The size of segmented portions of calandria shell 14 may be determined based on available waste containers, crane capacity etc. Segmented portions of calandria shell 14 may be collected on a transported positioned inside the calandria vault. The transporter may travel out of the vault through the opened vault wall for packing and to transfer segmented pieces of calandria for further processing. End shields may be segmented in situ, packed and shipped to a permanent storage facility.

[0090] At block 901 of method 900, similar to the methods described above, a shielding wall may be installed to cover a portion of the calandria vault to be removed. The shielding wall is configured to allow access to the vault to collect cut pieces of calandria shell 14 and cut off moderator / thimble pipes. The shielding wall may be temporary movable shielding door installed to shield the working area and to provide access to the calandria vault. At block 902, a portion of the vault may be removed, e.g. lower portion of the calandria vault, and at block 903 a gap may be formed under calandria 10 inside vault 11 such that calandria is suspended above the gap. At block 904, transporter 42, e.g. a trolley or Self-propelled Modular Transporter (SPMT), may be positioned under calandria 10 as shown. The travel path of transporter 42 may be reinforced to allow for the gross weight of the transporter, the calandria, and other materials positioned on the transporter. At block 905, the radioactive components within calandria shell 14 may be segmented with cutting tool 100 and removed from vault 11. Calandria shell 14 may be also segmented piece-by-piece by cutting tool 100, removed from vault 11 , and packed at block 906. By segmenting calandria shell 14 within end shields 64, the end shield may be used to mitigate against radiation from calandria shell and the components within calandria shell. At block 907, shielding ball bearings 66 may be removed from end shields64. The status of the shielding ball bearings 66 may be unknown as the shielding ball bearings may be degraded over time. In an example, shielding ball bearings may be carbon steel and may have rusted. In an embodiment, to remove shielding ball bearings 66, lattice tubes 65 internal diameters may be cut, or tubesheet 18 may be cut, to determined a waste segregation strategy. Shielding ball bearing 66 may removed through the cut section of tubesheet 18 or through cut section of at least one of lattice tubes 65. At block 908, subsequently, a portion of end shields 64 may be segmented; at block 909, lattice tubes may be removed; and at block 910 the remaining portion of end shields 64 may be removed. In an example, calandria side end shields may be segmented and the lattice tubes may be removed. Continuing the example, fueling machine side end shields may then be segmented. Cutting tool 100 may be positioned on platform 96 to segment end shields 64. At block 911 , segmented end shield 64 may be packed, and at block 912 transported to a permanent storage facility.

[0091] FIG. 10 illustrates a schematic view of an example method 1000 of dismantling a nuclear reactor. As shown, the dismantling method involves segmentation and removal of calandria shell 14, followed by the segmentation and removal of internals which may be secured in position by a filler. Initially, at block 1001 , end fittings assemblies 50 may be removed from the nuclear reactor, and pressure tubes cut at end shield 64. Shield plugs, also referred to as “Thumbtacks” may be inserted into the lattice tubes to seal the inside of calandria 10. At block 1002, a portion of Reactivity Mechanisms (RM) Deck 102 may be removed. At block 1003, after vault 11 is drained, calandria 10 may be filled with filler material to stabilize calandria shell 14 and internal tubing. At block 1004, vault 11 may be opened. At block 1005, a series of vertical circumferential cuts to calandria shell 14 may be made followed by segmentation. At block 1006, portions of calandria shell 14 may be peeled off leaving end shields 64, at block 1007 remaining with the internal tubing of calandria 10, e.g. fuel channel assemblies 28, moderator pipes, etc. At block 1008, the remaining internal tubing of calandria 10 may then be segmented and removed; followed by segmentation and packing of the end shields 64 at block 1009. Because the internal tubing and internal components of calandria 10 are ILW, the filler material binding the internal tube may reduce radiation emissions and formation of radioactive particulate when the filler defining the internal tubing and internal components of calandria 10 are segmented.

[0092] Embodiments of example method 1000 for segmenting a calandria 10 are described below.

[0093] FIG. 11 A is a front view of a calandria inside a vault of a nuclear reactor; and FIG. 11 B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 11 A. As shown in FIG. 11A, in an embodiment, thimbles 17, e.g. ion chambers, liquid injectors, shutdown units, etc., may be cut along the lines A-A, B-B; and moderator inlet and outlet piping may be cut along line C-C, D-D. After the cutting, the resulting holes may be plugged such that calandria vessel 14 may be filled with a filler 20 (illustrated as the shaded region in FIG. 11A and 11 B). At this juncture, CT 32 and PT 36 may still be present within calandria shell 14. Once calandria shell 14 separated / decoupled from the external pipes surrounding calandria shell 14, PT 36 may be secured CT 32 at predetermined locations.

[0094] FIG. 12 is a side cut away view of the calandria inside a vault of a nuclear reactor shown in FIG. 11A where a portion of the vault is removed. As shown in FIG. 12, vault 11 may be opened to access the bottom portion of vault 11 by cutting a portion of vault 11 illustrated as cut away section E-E. As shown in FIG. 12, cut away section E-E may be in D-face and / or B-face. Faces A and C, comprising end shields 64 at the fueling machine deck or the lattice sites may remain unmodified and intact to maintain the radiation shielding they provide.

[0095] FIG. 13A is a front view of the calandria inside the vault of a nuclear reactor shown in FIG. 11A illustrating cutting the calandria shell; and FIG. 13B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 13A. As described above, method 1000 comprises cutting and peeling off calandria shell 14. In an embodiment, the outer shell, annular plate and subshell of the calandria shell is peeled off and segmented. Known cutting methods, such as wire cutting, may be used for cutting. A first cutting orientation may be around a circumference of calandria shell 14 and to cut to a predefined depth F-F from the surface of calandria shell 14. The cutting tool may be operated from RM Deck 102, or adjacent vault 11 through opening illustrated by cut away section E-E in FIG. 12. In an example, at least three cuts 21 may be made to allow the sectioned calandria to be segmented into manageable pieces.

[0096] FIG. 14 is a front view of the calandria inside the vault of a nuclear reactor shown in FIG. 13A showing segmentation of the calandria shell. In an embodiment, a cutting tool may be placed at A-face and C-face through a fuel channel assembly 28 to perform cuts 25, 26 for cutting a section from a calandria shell 14. Sectioned pieces of calandria shell 14 may be collected from inside of vault 11 and packed into waste containers at an appropriate location. Segmentation of the calandria shell may continue until calandria shell 14 is peeled off. End shields 64 may be sectioned through at the same depth calandria shell 14. Because outermost portions of the end shields are coupled to vault 11 by concrete, these sectioned pieces may not be removed until after calandria shell 14 has been segmented and removed.

[0097] Continuing the example, once the main shell is peeled off, a similar axial cutting operation can be repeated until calandria shell 14 is completely cut. Sectioned pieces may be collected by handling equipment which pack the pieces into waste containers. End Shield 64 pieces that are sectioned may remain in place until the calandria shell 14 is segmented and removed.

[0098] FIG. 15A is a side cut away view of the calandria inside the vault of a nuclear reactor shown in FIG. 14 after the calandria shell has been removed. As shown, end shields 64 remain. End shields 64 may be cut such that a segment 64a of each end shield 64 is coupled to vault 11 , e.g. by cement, and a segment 64b of each end shield 64 is not coupled to vault 11. Segment 64b may be radially inward from vault 11. To remove end shield 64, segment 64b may be dislodged. Extra supports may be required around the end shield segments, to ensure stability of end shield 64 as it is removed and processed. As shown in FIG. 15B, this process may continue until the segments of end shield 64 are removed, except for the segment that are coupled to vault 11 , e.g. with concrete. Cutting tools may be utilized to free the remaining pieces from vault 11 , processed and packed into waste containers.

[0099] FIG. 16 illustrates a schematic view of an example method 1600 of dismantling a nuclear reactor. As shown, the dismantling method involves segmentation the entire calandria 10 and fuel channel assemblies 28 in-situ after the vault 11 and calandria 10 are filled with a filler material, e.g. concrete, which provides shielding during segmentation process and absorbs radiation emitted from the calandria. In an example, the concrete may be light weight concrete having an oven-dry density of not less than 800 kg / m3andnot more than 2000 kg / m3. Method 1600 is described below with reference to FIGs. 16- 19D.

[0100] An advantage of method 1600 is that it may minimize preparation required for this dismantling option. Penetration through vault 11 may be plugged where required for calandria 10 and calandria vault 11 filled with the filler material. At block 1601 , end fitting assemblies 50 may be removed and shield plugs installed to close the lattice tubes. At block 1602, shielding plates may be installed over end shields 64 to further seal vault 11. CT 32, PT 36, calandria tube inserts 34, and thimbles may all still be present inside Calandria 10 and vault 11. At block 1603, after vault 11 and calandria 10 are drained of liquid, e.g. moderator fluid, cutting channels 16 may be installed to extend, through calandria 10, e.g. vertically through calandria 10 as shown in FIG. 17. Cutting channels 16 may allow access for cutting tools to segment adjacent portions of the calandria after vault and calandria 10 are filled with filler. At block 1604, after the cutting channels 16 are installed, calandria 10 and vault 11 are filled with filler, e.g. concrete, and allowed to set. Once the filler is set, the vault 11 , calandria 10, and filler define a solid volume which may be segmented and removed. At block 1605, cores 15, e.g. horizontal cores, may be drilled through end shields 64, e.g. via relief ducts; and at block 1606, RM Deck 102 may be removed to allow cutting tools access to the concrete filled calandria 10 and vault 11 . At block 1607, cutting tools may then segment a layer of the solid volume comprising the calandria, vault, and filler. At block 1608, cutting channels 16 and cores 15 may be utilized by cutting tool to cut and remove portions of the solid volume layer-by-layer. In an example, the cutting tool may be a wire cutting tool having a cutting wire extending into the cutting channel 16 or core 15 to cut through cutting channel 16 and the filler material.

[0101] Embodiments of example method 1600 for segmenting a calandria 10 are described below.

[0102] FIG. 17 illustrates a side cut away view of the calandria inside the vault of a nuclear reactor with cutting channels 16 installed vertically through calandria 10. Cutting channels 16 may be tubing, e.g. metal tubing, suitable for forming a channel. Cutting channels 16 may be inserted into calandria 10 through vertical pipes in the calandria such as rupture disc and / or reactivity control unity penetrations in vault 11. After calandria 10 is filled with filler, cutting channels 16 may allow cutting tools, e.g. wire cutters, to accessthe interior of calandria 10 to cut segments of the solid volume comprising calandria 10, vault 11 , and the filler. Each PT 36 may also be secured its respective CT 32 prior to filling calandria 10 and / or vault 11 with filler.

[0103] FIG. 18A shows is a front view of a calandria inside a vault of a nuclear reactor; FIG. 11 B is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 18A; and FIG. 11C is a side cut away view the calandria inside a vault of a nuclear reactor shown in FIG. 18A with cores drilled sections the vault. In an embodiment, thimbles 17, e.g. ion chambers, liquid injectors, shutdown units, etc.; moderator inlet and outlet piping, calandria tube inserts 34, and other piping inside calandria 10 and vault 11 may be left in place. Filler, e.g. concrete, may be poured into calandria 10 and / or vault 11 and allowed to set. To provide adequate shielding, filler may be poured to a specific height above the top of calandria shell 14 to allow the RM Deck 102 to be removed as shown in FIG. 18B. Segmentation of filler 20, calandria 10, and vault 11 may then be performed for example by wire cutting, core drilling, diamond cutting, or similar methods. Segmentation of the calandria 10 and vault 11 may occur from the top to the bottom. Vertical cuts may be made through cutting channel 16 installed inside the calandria 10 and through core drilled openings 15 drilled into filler 20. Horizontal cuts may be performed with a cutting tool inserted through fuel channels assemblies 28. These operations could be fully or partially remote. End Shields 64 may be cut with the vault 11.

[0104] FIG. 19A illustrates a front view of a calandria inside a vault of a nuclear reactor shown in FIG. 18A with the RM Deck removed. Vertical cuts 27 may be made through cutting channels 16 or core drilled openings 15; and horizontal cuts 29 may be made through fuel channel assemblies 28 and / or lattice tube to intersect vertical cuts 27 for forming segmented portions of the filler 20, calandria 10, and / or vault 10. The segmented portions may be removed through RM Deck 102, and / or an opening in vault 11 such as cut away section E-E shown in FIG. 13A, and transported to a location for packing into waste containers. In some embodiments, the segmented portions may need to be stored and / or transported in radiation shielded containers.

[0105] FIG. 19B is an enlarged fragmentary view of detail G-G. Detail G-G shows an example cross-section of a portion of calandria 10 and filler 20 cut by a cutting tool according this disclosure. In an embodiment, as described above with respect to FIG.19A, core drilled openings 15 may be drilled into the concrete along a core opening axis 39. A cutting tool may be inserted into the at least one cutting channel 16. At least one of the filler 20 and the calandria 10 are cut along a approximately vertical first plane l-l connecting the core drilled opening 15 and at least one of cutting channels 27. Multiple cuts approximately parallel to first plane l-l may be done through additional cored drilled openings and / or cutting channels to provide a series of parallel cuts. Vertical cuts 27 along first plane l-l may be intersected by approximately horizontal cuts 29. In an embodiment, at least one of the filler and the calandria are laterally cut from core drilled opening 15 and / or cutting channel 16 to define a second plane J-J, the first and second planes intersecting to segment a portion of the filler and / or calandria 10. In the example illustrated in FIG. 19B, cutting at least one of the filler and the calandria laterally from the at least one cutting channels comprises: inserting a cutting tool into a lattice tube 65; cutting at least one of the filler 20 and the calandria 10 along the approximately horizontal second plane J-J intersecting the lattice tube and another lattice tube. As shown in FIG. 19B, vertical cuts 27 and horizontal cuts 29 may intersect adjacent lattice tubes. Because vertical cuts 27 and horizontal cuts 29 may intersect calandria tubes, fuel channels, and / or lattice tubes 65 of calandria 10 which are radioactively contaminated, parts of the calandria tubes, fuel channels, and / or lattice tubes may be exposed as they are not covered by filler 20. As a result, segmented portion(s) of calandria 10 and filler 20 cut by a cutting tool shown in FIG. 19B may need to be placed in a radiation shielded container to storage and / or transport such that the segmented portion is shielded from all sides. More radioactive dust may also be created when vertical cuts 27 and horizontal cuts 29 intersect calandria tubes, fuel channels, and / or lattice tubes of calandria 10 that will need to be collected and removed.

[0106] FIG. 19C is an enlarged fragmentary view of detail H-H. Detail H-H shows an example cross-section of a portion of calandria 10 and filler 20 cut by a cutting tool according this disclosure. As shown, vertical cut 27 and horizontal cut 29 do not intersect calandria tubes, fuel channels, and / or lattice tubes 65 of calandria 10. Instead, cutting the filler 20 and the calandria 10 laterally from cutting channels 27 comprises: cutting the filler 20 between adjacent fuel channels, such that the cutting planes, i.e. approximately horizontal plane K-K and approximately vertical plane L-L, do not intersect calandria tubes, fuel channels, and / or lattice tubes 65 of calandria 10. Because the cutting planes,i.e. horizontal plane K-K and / or vertical plane L-L may be between the calandria tubes, fuel channels, and / or lattice tubes 65 of calandria 10, fewer radioactive surfaces may be exposed which reduces the radiation shielding requirements and amount of radioactive particulate formed when cutting. As a result, the segmented portion of detail H-H shown in FIG. 19C may not require as much radiation shielding for storage and / or transport as the segmented portion shown in FIG. 19B because only two faces of the segmented portion comprise exposed radioactive tubing which is ILW, i.e. the opposing faces of the segmented portion where tubing is cut. Because filler 20 may define at least four faces of the segmented portion, the filler 20 may reduce exposure to radioactive tubing. As a result, radioactive shielding may only be required on the faces of the segmented portion were radioactive tubes are exposed, i.e. the opposing faces of the segmented portion where tubing is cut.

[0107] In an embodiment, the segmented portions of the filler and calandria may have a substantially quadrilateral cross-section.

[0108] FIG. 19D illustrates an example cutting tool coupled to a collaborative robot 70 according to this disclosure positioned exterior to calandria 10. Vertical cuts 27 and horizontal cuts 29 may be made collaborative robot 70 while is positioned exterior to calandria 10.

[0109] FIG. 19E illustrates movement paths of example cutting tools and waste container trolleys. Collaborative robot 70, e.g. a cutting tool, may be moved through the opening in the vault 11 to segment portions of calandria 10 and / or piping and support connecting the calandria to the vault 11. Barrier 104 may be positioned to provide radiation shielding to cover an opening formed by removing a portion of side of vault 11. Segmented portions of calandria 10 and filler 20 may be positioned on trolley 105 which may remove the segmented portions from vault 11.

[0110] FIG. 20 illustrates a schematic view of an example method 2000 of dismantling a nuclear reactor. As shown, the dismantling method involves segmentation the entire calandria 10 and fuel channel assemblies 28 in-situ under water. Cutting tools may access calandria 10 from RM Deck 102. Method 2000 is described below with reference to FIG. 20 and 21. By segmenting calandria 10, fuel channel assemblies 28, and components thereof under water, the formation of airborne radioactive particulate fromcut radioactive components may be reduced. As a result, the demand upon a ventilation system(s) surrounding vault 11 during decommissioning may be reduced or removed.

[0111] Another advantage of method 2000 is that it may minimize the preparation required for dismantling the calandria 10. Penetrations through vault 11 , e.g. fuel channels, lattice tubes, and thimbles, may be plugged where required to provide a sealed volume configured to be filled with water. Each fuel channel may be watertight on each side of the nuclear reactor to prevent water from escaping in inside of vault 11 as it is filled with water. As shown in FIG. 20, at block 2001 , end fitting assemblies 50 may be removed and shield plugs installed to close the lattice tubes. CT 32, PT 36, calandria tube inserts 34, and thimbles may all still be present inside calandria 10 and vault 11. At block 2002, a sealing members 201 , e.g. a seal plate and / or plugs, may seal each fuel channel. In an example, the sealing member is a seal plate which may be welded to seal fuel channel(s). In another example, sealing member 201 may be plug(s) positioned in each fuel channel and / or lattice side. At block 2003, a portion of RM deck 102 may be removed to allow direct access to calandria 10. Removal of RM deck 102 may be performed in parallel to sealing the fuel channels. Cutting and handling tools may be positioned at the RM Deck area along with the waste crate, and a drying and packing station. At block 2004, segmentation and packing of calandria 10, including internal piping, is completed. Waste crate may be filled with the segmented portions of calandria 10 under the water inside vault 11. When the waste crate is full, it may be lifted from the water to drain, then moved to system 200 for drying and packing radioactive waste shown in FIG. 21. System 200 may comprise of a receiving station, heat drying and packing sections, as well as the radiation measurement tools. After a waste crate with waste is completely dry it may be placed in a shielded container for transportation. Drying and packing could be performed in parallel with underwater segmentation. In some embodiment, thimbles, thimble seismic restraint and moderator pipes should be cut and removed first to allow access to the calandria shell. After the area above the calandria shell is clear, the segmentation and removal of the upper section of calandria shell may be performed, followed by its internal piping. At block 2005, after the calandria and its internals are removed, the removal of shielding ball bearings 66 may be completed. Tubesheet 18 can be opened with the cutting tools and shielding ball bearings 66 may be collected into crate. At block 2007, after calandria 10 and shielding ball bearings 66 areremoved, tubesheet 18 may be sectioned and removed; and lattice tubes 65 may also be segmented and removed. Tubesheet 18 and lattice tubes 65 may be cut using similar tools and techniques as for calandria 10 segmentation. The tube sheets 18 that are cut may be the calandria side tube sheets such that the fuel machine side tube sheets, i.e. the end shield, are retained to form a sealed volume filled with water. At block 2009, when all underwater segmentation is complete, vault 11 may be drained and filtered using an active water filtration system to separate particulate and waste material from the water. At block 2009, optionally, vault 11 my be used to segment other equipment in the reactor building. At block 2010, the fueling machine tubesheet may be segmented using the same tools as those used for underwater segmentation.

[0112] In an embodiment, method 2000 comprising segmenting the calandria, internal components of the calandria, and tube sheets of the end shield may comprise: providing a crate configured to receive segmented nuclear components of nuclear reactor. The crate may receive segmented components from handling tools inside the vault. The crate may have a plurality of holes for draining water. The method may also comprise positioning segmented portions of at least one of the calandria, the internal components of the calandria, and the tube sheets of the end shield, in the crate; and positioning a shielded cover over the crate. The shielded cover may be configured to receive the crate and provide radiation shielding for the segmented components in the crate. Once the shielded cover is placed over the crate, the crate may be lifted out of the water. The shielded cover provides radiation shielding to protect operators from the radiated segmented components when the components are outside the vault and water. The method may also comprise draining the water from the crate; drying the segmented components; and positioning the dried segmented components into a container for transport to an to external storage facility. In an example, the segmented components may be dried by a heater to remove water from the components without mobilizing particulate matter (e.g. dust, chips, and flakes) from segmenting the components of calandria 10. Once dried, segmented components of calandria 10 may be positioned in a radiation shielded container configured to contain radiation from the segmented components. Example radiation shielded container(s) are described in International Patent Application No. PCT / CA2024 / 051337, the entire contents of which are hereby incorporated by reference.

[0113] FIG. 21 illustrates an example system 200 for drying and packing radioactive waste. System 200 comprises a drying and packing station 210, waste crate 211 , and a dryer 212. Waste crate 211 may receive segmented portions of calandria 10 under water within vault 11 from gripper 103. Waste crate 211 may comprise a shielded cover 213 for reducing radiation transmission and drain holes for draining water when waste crate is lifted from the water filled vault 11. In an example, waste crate 211 may define a at least one opening 215, e.g. on the bottom of waste crate 211 , sized to allow water to drain from the segmented components without dropping the components as they are lifted from vault 11. Dryer 212 may comprises a heater for heating the segmented waste to evaporate water and dry off the segmented waste. In an embodiment, the dryer is at least one of an infrared heater, a black-body radiation heater, a resistance power heater, and / or a convection heater. The dried segmented waste may then be pack in a shielded container 214 for transport to a waste storage facility.

[0114] Alternate embodiments

[0115] The above description is meant to be exemplary only, and one skilled in the relevant arts will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The present disclosure is intended to cover and embrace all suitable changes in technology. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. Also, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0116] As can be understood, the detailed embodiments described above and illustrated are intended to be examples only. The invention is defined by the appended claims.

[0117] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.

Claims

WHAT IS CLAIMED IS:

1. A method of segmenting a calandria within vault of a nuclear reactor, the method comprising: providing at least one cutting tool; cutting a portion of the vault to form an opening with one of the at least one cutting tool; forming a shielded volume defined by a shielding wall, , the vault, and end shields of the calandria, the shielding wall configured to absorb radiation from within the shielded volume, optionally the shielding wall covers the opening; segmenting a shell and internal components of the calandria within the shielded volume; and removing the shell and internal components of the calandria from the shielded volume.

2. The method of claim 1 comprising: removing shielding ball bearings from between the end shield and a calandria side tube sheet; segmenting the calandria side tube sheet; removing lattice tubes from the end shield; and segmentation of the end shield.

3. The method of any one of claims 1-2, comprising positioning a transporter under the calandria; and removing the shell and internal components of the calandria from the shielded volume with the transporter.

4. The method of claim 1 , comprising: decoupling the end shields from the vault; and positioning one of the end shields on top of the other end shield on a transporter.

5. The method of claim 4, wherein positioning one of the end shields on top of the other end shield, comprises positioning a tube sheet portion of one of the end shields against a tube sheet potion of the other end shield.

6. The method of claim 2, comprising filling the calandria with a filler for supporting the calandria and absorbing radiation; wherein the portion of the vault cut by the at least one cutting tool is the reactivity mechanism deck.

7. The method of claim 2, comprising: filling a portion of the shielded volume, and the calandria, with a filler to support the calandria and to absorb radiation emitted from the calandria; segmenting the end shields within the shielded volume, wherein the shielding wall comprises shielding blocks defining the surface of the end shields; and removing the end shields from the shielded volume.

8. The method of claim 6 or 7, wherein the filler is light weight concrete having an oven-dry density of not less than 800 kg / m3and not more than 2000 kg / m3.

9. The method of claim 6 or 8, wherein segmenting the shell and the internal components of the calandria within the shielded volume comprises: peeling the calandria shell off the filler; and segmenting the internal components.

10. A method of removing a calandria from a vault of a nuclear reactor, the method comprising: providing at least one cutting tool; cutting a portion of the vault with the at least one cutting tool; positioning the calandria on a transporter; moving the calandria out of the vault; positioning a shielding liner over a shell of the calandria; and filling the shielding liner with filler for immobilizing the calandria within the liner.11 . The method of claim 10, wherein the filler is concrete.

12. The method of any one of claims 10-11 comprising positioning a first portion of the shielding liner on the transporter before the calandria is positioned on the transporter, positioning a second portion of the shielding liner on the calandria after the calandria is positioned on the transporter, and coupling the first and second portions of the shielding liner to define the calandria within the shielding liner.

13. The method of claim 1 comprising: inserting at least one cutting channel through the calandria, each of the at least one cutting channel defining a volume for receiving one of the at least one cutting tool; filling a portion of the shielded volume, and the calandria, with a filler to support the calandria and to absorb radiation emitted from the calandria, optionally the filler is concrete; cutting a portion of the vault to form an opening with the at least one cutting tool, wherein the portion of the vault is the reactivity mechanism desk; segmenting the end shields within the shielded volume.

14. The method of claim 13, wherein the filler is light weight concrete having an ovendry density in a range of 800 kg / m3to 2000 kg / m3.

15. The method of any one of claims 13-14, wherein the at least one cutting tool comprises a wire cutting tool having a cutting wire extending into the cutting channel, the method comprising cutting through the cutting channel and the filler.

16. The method of claim 13-15, comprising: drilling core openings into the filler along a core opening axis; inserting the at least one cutting tool into the at least one cutting channel; cutting at least one of the filler and the calandria along a first plane connecting the core opening axis and an axis of one of the at least one cutting channels; cutting at least one of the filler and the calandria laterally from the axis of the one of the at least one cutting channels to define a second plane, the first and second planes intersecting to segment a portion of the filler.

17. The method of claim 16, wherein cutting at least one of the filler and the calandria laterally from the at least one cutting channels comprises: inserting a cutting tool into a first lattice tube; cutting at least one of the filler and the calandria along the second plane intersecting the first lattice tube and a second lattice tube.

18. The method of claim 16, wherein cutting at least one of the filler and the calandria laterally from the at least one cutting channels comprises:cutting the filler between adjacent fuel channels, wherein the second plane does not intersect a lattice tube of the calandria.

19. The method of any one of claims 16-18, wherein the portion has a substantially quadrilateral cross-section.

20. The method of any one of claims 13-16, comprising inserting the at least one cutting tool into the cutting channel to segment the calandria, internal components of the calandria, and end shields.21 . A method of segmenting a calandria within vault of a nuclear reactor, the method comprising: providing at least one cutting tool; sealing each of a plurality of lattice tubes of the vault with sealing members; forming a shielding volume defined by the vault and end shields of the calandria; filling a portion of the shielded volume with water to submerge the calandria, with water; cutting a portion of the reactivity mechanism desk to form an opening with the at least one cutting tool; segmenting the calandria, internal components of the calandria, and tube sheets of the end shields within the shielded volume within a volume of the water; removing the calandria, internal components of the calandria, and tube sheets of the end shields from the vault.

22. The method of claim 21 , wherein the sealing members are at least one of plugs and welding plates.

23. The method of any one of claims 21-22, wherein the tube sheets are the calandria side tube sheets.

24. The method of any one of claims 21-23, comprising removing the water, the segmenting the end shields.

25. The method of any one of claims 21-24, wherein segmenting the calandria, internal components of the calandria, and tube sheets of the end shield comprises: providing a crate configured to receive segmented nuclear components of nuclear reactor, the crate having a plurality of holes for draining water;positioning segmented portions of at least one of the calandria, the internal components of the calandria, and the tube sheets of the end shield, in the crate; positioning a shielded cover over the crate, the shielded cover configured to receive the crate and provide radiation shielding for the segmented components in the crate; lifting the create out of the water; draining the water from the crate; drying the segmented components; positioning the dried segmented components into a container for transport to an to external storage facility.

26. A system for handling radioactive waste, the system comprising: a crane configured to move a crate into and out of a vault of a nuclear reactor, the vault filled with water; the crate configured to receive segmented nuclear components of nuclear reactor, the crate defining at least one opening for draining water; a shielded cover configured to receive the crate and provided radiation shielding for the segmented components in the crate; a dryer configured to evaporate water from the segmented components; and a container for transporting the segmented components from the dryer.

27. The system of claim 26, where the dryer is at lease one of an infrared heater, black-body radiation heater, resistance power heater, convection heater.

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