Waste storage cask for radioactive waste

Abstract

According to an aspect, there is provided a waste storage cask for radioactive waste and method of loading said casks with waste. The cask including a main body, a cover, and removable overpack shielding configured to be removed after an amount of time has elapsed. The main body and the removable overpack shielding together attenuate radiation emitted from the radioactive waste below a threshold when the radioactive waste is freshly sealed in the cask. The main body attenuates radiation emitted from the radioactive waste below the threshold after the amount of time has elapsed. According to an aspect, there is provided a waste storage cask for radioactive waste. The cask including a main body, a cover, and a cap. The main body and the cover couple to form at least one primary seal. The main body and the cap couple to form at least two secondary seals.

Description

WASTE STORAGE CASK FOR RADIOACTIVE WASTECROSS-REFERENCE

[0001] This application claims priority from United States patent application 63 / 589208, titled “WASTE STORAGE CASK FOR RADIOACTIVE WASTE”, filed on October 10, 2023, the contents of which are incorporated herein by reference.FIELD

[0002] Embodiments of the present disclosure generally relate to the field of nuclear waste, and more specifically, embodiments relate to devices, systems, and methods for improved nuclear waste transportation and storage.INTRODUCTION

[0003] Storage casks for radioactive materials necessitate specific design features to enhance their safety and long-term security. However, throughout a long lifetime, storage casks for radioactive materials may be required to work with multiple different varieties of tool sets. Furthermore, different casks may be configured to receive different types of waste material.

[0004] Such tailored designs may increase the processing complexity during a retube or decommissioning process. This complexity may also increase the time and cost to retube or decommission a reactor. Furthermore, these differing cask designs may necessitate different storage considerations.

[0005] Improvement in the field of waste storage casks is desirable.SUMMARY

[0006] Different components of waste from the retube and / or decommissioning process may be stored in different waste containers. For example, end fittings may be configured to fit in large waste containers while calandria tube / pressure tubes and calandria tube inserts may be configured to fit in small waste containers. Though the calandria tube / pressure tubes and calandria tube inserts may each fit inside small waste containers, their radioactivity may necessitate differing shielding configurations.

[0007] A waste storage cask that is configured to receive these differing types of waste may be advantageous. Furthermore, if such a waste storage cask is configured to interoperate with existing tooling systems (e.g., the Loading Interface Device (LID), the Containment Loading Hoist (CLH)), then these casks may further expedite retubing and / or decommissioning activities. The LID and CLH are engineered tools. The purpose of the LID includes accurately positioning the waste transfer flask over the opening of the casks described herein, as well as to provide radiation shielding for workers. The CLH can be used for lifting and handling small and large waste transfer flasks, and for the loading and unloading of waste containers during the storage operations at the waste management facility.

[0008] Devices described herein can act as waste storage casks. In some embodiments, they may act as intermediate-level waste (ILW) storage casks. These casks can, for example, accept both large waste containers (e.g., end fitting waste) and small waste containers (e.g., calandria tubes / pressure tube and calandria tube insert waste) containing the ILW generated from, for example, retube and / or decommissioning operations. These casks may further be configured to receive other types of operational waste (e.g., tooling, reactor components, flasks, filters, ILW in different configurations, other waste, etc.). The devices described herein may be suitable to be classified as a Type-B(M) Transport Package based on IAEA SSR-6, the contents of which are incorporated by reference.

[0009] Devices described herein can be configured to interface with CANDU-6 tooling sets. For example, devices described herein can seamlessly mate with other existing tooling used in the CANDU-6 retubing or decommissioning reactor processes (e.g., the LID, the CLH, and the small and large waste containers). Compatibility with existing tooling minimizes the use of extra tooling and works seamlessly with all CANDU-6 or other reactors.

[0010] In accordance with one aspect, there is provided a waste storage cask for radioactive waste. The cask includes a main body configured to receive the radioactive waste and a cover. The main body and the cover may couple to form a primary seal (e.g., a gasket). The main body may further be configured to couple with a cap that can be positioned over the cover. The cap and the main body can form a secondary seal. The waste storage cask may further include removable overpack shielding configured to attenuate radiation from waste stored therein.

[0011] According to an aspect, there is provided a waste storage cask for radioactive waste. The cask including a main body configured to receive the radioactive waste, a cover, andremovable overpack shielding configured to be removed after an amount of time has elapsed. The main body and the cover are configured to couple to form at least one primary seal. The main body and the removable overpack shielding together attenuate radiation emitted from the radioactive waste below a threshold when the radioactive waste is freshly sealed in the cask. The main body attenuates radiation emitted from the radioactive waste below the threshold after the amount of time has elapsed.

[0012] In some embodiments, the main body is configured to couple to a cap positioned over the cover, and the main body and the cap are configured to couple to form at least one secondary seal.

[0013] In some embodiments, the cap includes a secondary port for leak testing the at least one secondary seal.

[0014] In some embodiments, the removable overpack shielding is configured to be removed to accommodate the installation of impact limiters.

[0015] In some embodiments, the removable overpack shielding is selected based on the identity of the radioactive waste.

[0016] In some embodiments, the cover includes a primary port for leak testing the at least one primary seal.

[0017] In some embodiments, the removable overpack shielding includes removable side overpack shielding.

[0018] In some embodiments, the main body is cylindrical.

[0019] In some embodiments, the radioactive waste is one of calandria tube inserts, calandria tubes / pressure tubes, and end fittings.

[0020] In some embodiments, the cask further includes at least one of trunnions, slots, and pockets.

[0021] In some embodiments, the cask further includes trunnions and feet. The trunnions align with the feet from a top perspective.

[0022] In some embodiments, an interior of the main body is configured with a divider that subdivides the interior into compartments, and each of the compartments is configured to receive the radioactive waste.

[0023] In some embodiments, the divider is at least one of shaped, angled, or cutaway.

[0024] In some embodiments, the compartments comprise at least four compartments.

[0025] In some embodiments, four of the at least four compartments are configured to receive a stack of one or more calandria tube / pressure tube or end fitting waste containers, and two opposing compartments are configured to receive a stack of one or more calandria tube insert waste containers.

[0026] In some embodiments, the main body is configured to receive a shielding liner.

[0027] In some embodiments, the shielding liner is selected based on the identity of the radioactive waste.

[0028] In some embodiments, the cask further includes a spacer to increase a height of the stack of the one or more waste containers to meet the bottom of the cover.

[0029] In some embodiments, the radioactive waste includes a stack of one or more waste containers.

[0030] In some embodiments, the overpack shielding is configured to cover a portion of an exterior of the main body.

[0031] In some embodiments, the portion includes the exterior surface between two flanges.

[0032] In some embodiments, the overpack shielding includes a first portion and a second portion, the first portion configured to couple to the second portion to define at least a portion of an exterior surface of the cask.

[0033] In some embodiments, the first portion has a first mating surface configured to couple to a second mating surface of the second portion.

[0034] In some embodiments, the first mating surface defines a projection configured to be received in a groove defined in the second mating surface.

[0035] In some embodiments, wherein the overpack shielding has an opening to receive a trunnion on the main body.

[0036] According to an aspect, there is provided a waste storage cask for radioactive waste. The cask including a main body configured to receive the radioactive waste, a cover, and a cap. The main body and the cover are configured to couple to form at least one primary seal. The main body and the cap are configured to couple to form at least two secondary seals.

[0037] According to an aspect, there is provided a method of storing radioactive waste, the method including providing a cask described herein and inserting a stack of the one or more waste containers into the cask, wherein the top surface of the stack meets the bottom of the cover.

[0038] Many further features and combinations thereof concerning embodiments described in this disclosure will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE FIGURES

[0039] In the figures,

[0040] FIG. 1 illustrates a prospective view of a cask, according to some embodiments.

[0041] FIG. 2 illustrates a prospective view of a cask without the cover, according to some embodiments.

[0042] FIG. 3A-3C illustrates a prospective view of three different casks with overpack shielding, according to some embodiments.

[0043] FIG. 3D-3G illustrates a top view of the interior of four different casks, according to some embodiments.

[0044] FIG. 4 illustrates a cross-sectional view of a cask configured for large waste containers and a cask configured for small waste containers, according to some embodiments.

[0045] FIG. 5 illustrates trunnion placement, according to some embodiments.

[0046] FIG. 6 illustrates a prospective view of the interior components of a primary seal, according to some embodiments.

[0047] FIG. 7A illustrates a cross-sectional view of a shipping cover for a cask, according to some embodiments.

[0048] FIG. 7B illustrates a cross-sectional view of a cask with a cover and shielding cap, according to come embodiments.

[0049] FIG. 8 illustrates a cross-sectional view of a shipping cover for a cask and a magnified view of same, according to some embodiments.

[0050] FIG. 9 illustrates a prospective view of a cask with impact limiters, according to some embodiments.

[0051] FIG. 10 illustrates a cross-sectional view of a cask with impact limiters, according to some embodiments.

[0052] FIG. 11 A illustrates a prospective view of a cask configured for pressure tube / calandria tube waste, according to some embodiments.

[0053] FIG. 11B illustrates a cross-sectional view of the cask of FIG. 11 A, according to some embodiments.

[0054] FIG. 12A illustrates a prospective view of a cask configured for calandria tube insert waste, according to some embodiments.

[0055] FIG. 12B illustrates a cross-sectional view of the cask of FIG. 12A, according to some embodiments.

[0056] FIG. 13A illustrates a prospective view of a cask configured for end fitting waste, according to some embodiments.

[0057] FIG. 13B illustrates a cross-sectional view of the cask of FIG. 13A, according to some embodiments.

[0058] FIG. 14 illustrates a comparison of three different shapes for the cask, according to some embodiments.

[0059] FIG. 15 illustrates a cross-sectional view of a rectangular cask made from steel and concrete, according to some embodiments.

[0060] FIG. 16A-16B illustrates casks with the side overpack shielding being installed thereon, according to some embodiments.DETAILED DESCRIPTION

[0061] Devices described herein can act as waste storage casks. In some embodiments, they may act as intermediate-level waste (ILW) storage casks. These casks can, for example, accept both large waste containers (e.g., end fitting waste) and small waste containers (e.g., calandria tubes / pressure tube and calandria tube insert waste) containing the ILW generated from, for example, retube and / or decommissioning operations. The small waste containers and large waste containers can be unshielded thin-walled cylindrical containers intended to retain waste within a larger shielded flask or cask. The small and large waste containers can be engineered containers. The small waste containers can be used in conjunction with, for example, small waste transfer flasks on the reactor face. The small waste containers can be used to contain, for example, calandria tube inserts, volume reduced calandria tube / pressure tubes with the annulus gas spacers removed and packed into small waste transfer flasks during the retube campaign. The radioactive waste is transported from the reactor building to the waste storage facility where waste containers are loaded inside the casks described herein. Large waste containers are used in conjunction with the large waste transfer flask on the reactor face to retrieve the removed end fittings during the retube campaign and transport radioactive waste from the reactor building to the waste storage facility.

[0062] These casks may further be configured to receive other types of operational waste (e.g., tooling, reactor components, flasks, filters, ILW in different configurations, other waste, etc.). The devices described herein may be suitable to be classified as a Type-B(M) Transport Package based on IAEA SSR-6, the contents of which are incorporated by reference.

[0063] The casks described herein may be configured for different types of waste such as calandria tube inserts, calandria tubes / pressure tubes, and end fittings. In particular, these casks may be able to accept both small waste containers and large waste containers as-is. For example, the casks may be configured to receive 4 large waste containers (2x2 single layer), 16 small waste containers (2x2 four layers), or 8 small waste containers (1x2 four layers). Other configurations are also possible. Other configurations are conceived for other waste as well (e.g., accepting waste directly or differently sized waste containers). The cask may be optimized in size and weight for ease of handling, storage, and transport. The casks may be designed to generate low radiationenvironments for safe handling, storage, and inspections. In some embodiments, the casks may be configured to not exceed fifty metric tonnes when filled to enable the casks to operate with current transportation infrastructure (e.g., cranes). In some embodiments, overpack shielding may be removable to reduce the shipping weight and to reduce the materials used in final storage. The casks may have rigging points therein installed for ease of movement and transport. In some embodiments, the cask may meet target dose rates for storage and shipment. In some embodiments, the casks may be designed to interface with existing retube or decommissioning tools.

[0064] In some embodiments, impact limiters can be installed on the casks enabling the casks to pass mechanical tests to meet transportation requirements (e.g., 9 m drop and 1 m onto a steel bar followed by a thermal test (800°C for 30 mins) as per IAEA SSR-6). In some embodiments, the casks may be configured to fit inside the permanent storage facility and be compliant with deep geological repository requirements.

[0065] General Cask Configuration.

[0066] FIG. 1 illustrates a prospective view of a cask 100, according to some embodiments.

[0067] The cask 100 may comprise trunnions 102, a cask main body 104, and a cover 110, e.g. a cover on a top or upper portion of cask 100. The cask 100 may be configured to receive radioactive waste for storage. In some embodiments, the radioactive waste may be stored in large or small waste containers. For example, the cask 100 may receive end fittings in large waste containers, or calandria tube inserts or pressure tube / calandria tubes in small waste containers. In other embodiments, the radioactive waste may be inserted directly into the cask 100 not contained by a waste container. In some embodiments, the cask 100 may be configured to receive a mixture of waste materials. In some embodiments, the cask 100 may be configured to receive different waste types in the same cask 100 (e.g., end fittings in large waste containers with pressure tubes / calandria tubes in small waste containers).

[0068] The cask main body 104 may be configured to house the radioactive waste such as calandria tube inserts, end fittings, or pressure tubes / calandria tubes. The cask main body 104 may comprise steel, lead, and / or concrete (e.g., heavy concrete for greater radiation shielding). In some embodiments, the cask main body 104 may comprise other materials. The interior of the cask main body 104 may generally be subdivided into four quarters to accommodate four stacks of waste containers. The cask main body 104 may be subdivided (not shown in FIG. 1) using adivider. In some embodiments, the divider may generally be straight. In some embodiments, the divider may not be straight, for example, to provide clearance for waste, the cover, or other components. In some embodiments, the divider may be angled or shaped. In some embodiments, the divider may have cutaways in it to accommodate various components. Further examples of dividers are provided in FIG. 3D-3G.

[0069] In some embodiments, the seal of the cask 100 can be maintained by, for example, a steel liner with a flange to the cask main body 104 welded to the cover 110.

[0070] The trunnions 102 may serve as a mounting or pivoting point for the cask 100. In alternative embodiments, the trunnions 102 may not be present. In some embodiments, the trunnions 102 may be replaced in whole or in part with other features suitable to serve as a mounting or pivoting point for the cask 100. In some embodiments, the trunnions 102 may be replaced with slots or pockets.

[0071] The four lifting trunnions 102 may be spigotted and bolted onto the cask main body 104. In some embodiments for crane lifting, the trunnions 102 are preferred over pockets. The trunnions 102 may allow for relative ease of tilting the cask 100. The lower pair of trunnions 102 may act as a pivot when they are nested on a yoke on the transport frame, and the upper pair of trunnions 102 are attached to the crane. As the cask 100 is lowered by the crane, it tilts, rotating about the lower pair of trunnions 102.

[0072] The cover 110 can be configured to open to permit waste to be inserted into the cask 100 and closed to keep the waste inside. In some embodiments, the cover 110 may be sealed. In some embodiments, a gasket may be used to provide a seal between the cask main body 104 and the cask cover 110 when the cask 100 is filled with waste. Depending on the seal properties, it may be installed at the manufacturer’s site, in an auxiliary building during the acclimatization period, during production after the cask top-assembly 110 is removed from the cask 100, etc.

[0073] In some embodiments, it may be advantageous to provide overpack shielding to the cask 100 to attenuate the radioactivity emitted from the cask 100. The overpack shielding may be optionally provided where the cask main body 104 on its own is insufficient to attenuate radioactivity arising from the contents of the cask. For example, it may be financially expedient to manufacture a cask main body 104 which is capable of attenuating low radioactivity waste. For such casks 100, the overpack shielding may be used to attenuate the cask 100 when higher radiation waste is stored therein. Furthermore, the radioactivity of the waste may decrease withtime. Thus, it may be advantageous to use removable overpack shielding to attenuate radioactivity wherein the overpack shielding may be removed and used elsewhere while the cask 100 itself is still used to store the waste.

[0074] FIG. 2 illustrates a prospective view of a cask 200 without the cover, according to some embodiments.

[0075] Similar to that of the cask 100 of FIG. 1 , cask 200 comprises trunnions 202 and a cask main body 204. The cover is not pictured. The cover may be removed to insert waste (e.g., waste containers). The interior of cask 200 may include a divider 214. The divider 214 may include angular guides 222 (described in greater detail below). The cask 200 is also shown with overpack shielding (side overpack shielding 206).

[0076] The trunnions 202 may generally share the same description and variations as described for the trunnions 102 of FIG. 1.

[0077] The cask main body 204 may generally share the same description and variations as described for the cask main body 104 of FIG. 1 .

[0078] The overpack shielding (e.g., side overpack shielding 206 and / or top overpack shielding described in greater detail below) may optionally be installed on the cask 200 (e.g., the cask main body 204) to absorb radiation. For example, if high radiation waste is disposed within the cask 200, then overpack shielding may be advantageous to reduce radiation levels on the exterior of the cask 200. In some embodiments, the overpack shielding may be removed when radiation levels of the waste decrease (e.g., after an amount of time, for example, ten years) and the cask 200 may be left with the waste, but no longer with the overpack shielding. In some embodiments, the overpack shielding may be removed and installed on another cask 200 as needed. Such configurations may reduce the total number of overpack shielding units (e.g. side overpack shielding 206) required to effectively shield a total number of casks 200 (e.g., because not all casks 200 require the overpack shielding).

[0079] In some embodiments, the overpack shielding may be installed based on the radioactivity of waste disposed within the cask 200 and, for example, desired radiation levels outside the cask 200 (e.g., the overpack shielding is installed to keep radiation levels outside the cask 200 below a threshold). In some embodiments, the cask 200 may be reused. For example, waste may be removed from the cask 200 (e.g., because the radioactivity of the waste hasreduced below a threshold or to be processed further) and different waste may be inserted into the cask 200. In such situations, the overpack shielding may be removed (e.g., if the new waste is of lower radioactivity), installed (e.g., if the new waste is of higher radioactivity), or changed (e.g., for a different type of overpack shielding (e.g., a taller or shorter side overpack shielding 206 unit) or to repair or maintain the overpack shielding). In some embodiments, the nature of the overpack shielding may depend in part on the nature of the materials used other components of the cask 200 (e.g., the cask main body 204). For example, the overpack shielding may be made of more absorbing materials if the cask main body 204 is made of less absorbing materials.

[0080] In some embodiments the materials and thickness of the casks are based on the radioactivity of the intended contents of the cask initially and after a period of time (e.g., 50 years before the casks are transferred to, for example, a deep geological repository). For example, the total thickness of the cask main body 204 and the overpack shielding needs to be sufficient to safely shield radiation after the waste is initially transferred into the cask 200 and the total thickness of the cask main body 204 (or any other additional features such as a shielding liner described in greater detail below) needs to be sufficient to safely shield the radiation when the overpack shielding is intended to be removed. Based on the expected radioactive decay of the products therein and the expected timeline before transfer (e.g., 50 years before transferring the cask to a deep geological repository) the relationship between the cask main body 204 and overpack shielding can be ascertained. When the expected time elapses, the overpack shielding can be removed (e.g., and potentially reused on other casks), while the cask 200 can be safely transferred it next site while being much lighter. This can help reduce the costs of maneuvering and transporting the cask and reduce the amount of material making up the final cask for storage.

[0081] Overpack shielding may also be advantageous as it may be removed during transportation thereby reducing the total weight that is shipped. This may make the cask 200 more maneuverable during transportation. Accordingly, the overpack shielding might be designed to interoperate with the cask (as illustrated in FIG. 2 the side overpack shielding 206 is configured to provide openings for the trunnions 202 and to come up under a flange of the cask main body 204). The side overpack shielding 206 may come close to being flush to the flange, but some clearance may be provided for removal and installation of the side overpack shielding 206. The upper flange may provide a wider mounting surface (for example, for a cap such as a shipping cover, top overpack shielding, or a shielding cap (as described in greater detail below), as a small gap between the cap and cover may be helpful due to impact implications). The lower flange, which can have the same outer diameter of the upper flange, may ease mounting to the footweldment. It may also enable a common impact limiter to be mounted on both ends of the cask (as described below).

[0082] The divider 214 may optionally be used to subdivide the interior or the cask 200. For example, as illustrated, the divider 214 may divide the interior into four approximately equal compartments. In some embodiments, four separate stacks of waste (e.g., stacks of waste containers) can be inserted into this configuration. In some embodiments, some of the compartments may be left empty, for example, to control the radiation levels of the cask 200. In some embodiments, the divider 214 may divide the interior of the compartment into unequal compartments (e.g., more space may be provided for compartments that are to receive waste and less space for compartments to be left empty). In some embodiments, the divider 214 may be shaped based on the waste intended to be stored therein (e.g., the walls of the divider 214 may be curved or otherwise shaped to accommodate waste of specific configurations (e.g., waste containers)). In some embodiments, the divider 214 may include depressions or cutaways to accommodate other components of the cask 200 (e.g., components of the cover). In some embodiments, the divider 214 may divide the interior into a different number of compartments (e.g., two, three, five, six, seven, etc.).

[0083] Example Cask Configurations.

[0084] FIG. 3A-3C illustrates a prospective view of three different casks 300 with side overpack shielding 306 and top overpack shielding 312, according to some embodiments.

[0085] Each of the casks 300a, 300b, and 300c (collectively casks 300) are configured to receive different types of waste but are compatible with the LID and CLH systems.

[0086] Cask 300a may be configured to receive end fitting waste containers. End fitting waste can be stored in large waste containers. Cask 300a may be configured to receive four large waste containers divided within the interior of cask 300a. Furthermore, owing to the radioactive properties of the end fittings, additional shielding may only be required on a bottom half of the cask 300a.

[0087] Cask 300b may be configured to receive calandria tube insert waste containers. Calandria tube insert waste can be stored in small waste containers. In an example, cask 300b may be configured to receive eight small waste containers with calandria tube inserts positioned opposite each other in the interior of cask 300b (one column of four small waste containersopposite another column of four small waste containers totalling eight). Owing to the radioactive properties of the calandria tube inserts, it may be advantageous to only fill the cask 300b to half capacity as to enable the regular shielding to effectively shield the radioactivity. Additionally shielding liners may be used (as described in greater detail below).

[0088] Cask 300c may be configured to receive calandria tube / pressure tube waste containers. Calandria tube / pressure tube waste can be stored in small waste containers. In an example, cask 300c may be configured to receive sixteen small waste containers with calandria tube / pressure tube waste in the interior of cask 300c (e.g., four columns of four small waste containers totalling sixteen).

[0089] As can be seen from FIG. 3A-3C each of example casks 300a, 300b, and 300c generally may take the same external configuration enabling each of these casks 300a, 300b, and 300c to interoperate with the same tooling equipment. This can minimize the time and cost of retube and / or decommissioning processes. It can also simplify transportation and storage procedures for the casks (as the same procedure can be used for different waste types). Each of these casks 300a, 300b, and 300c is described in greater detail below.

[0090] The casks 300 may comprise trunnions 302, cask main bodies 304, side overpack shielding 306, foot weldments (feet) 308, covers 310, and top overpack shielding 312.

[0091] The trunnions 302 may generally share the same description and variations as described for the trunnions 102 of FIG. 1.

[0092] The cask main body 304 may generally share the same description and variations as described for the cask main body 104 of FIG. 1 .

[0093] Side overpack shielding 306 can offer shielding from radioactivity from the materials inside. Side overpack shielding 306 generally shares details and variations as described for side overpack shielding 206 of FIG. 2. The side overpack shielding 306 may be configured to be removed for transport and / or after fifty years of storage.

[0094] Feet 308 can be configured to keep the cask 300 upright. Feet 308 on the cask 300 can enable the use of a transporter or forklift truck to transport the cask 300. These feet 308 may be removable to enable the attachment of impact limiters needed when long distance transportation is required (described in greater detail below).

[0095] The cover 310 may generally share the same description and variations as described for the cover 110 of FIG. 1.

[0096] Top overpack shielding 312 may be provided over cover 310 and coupled to the cask main body 304 to provide shielding from radioactivity from the materials inside. See for example casks 300b and 300c show in FIG. 3B-3C. Top overpack shielding 312 generally shares details and variations as described for overpack shielding as described above. Top overpack shielding 312 may be configured to be removed for transport and / or after fifty years of storage.

[0097] In some embodiments, a divider 314 may be provided which may help keep the waste containers in place. The divider 314 generally shares details and variations as described for the divider 214 of FIG. 2. The divider 314 may divide the interior of cask 300 into compartments. In some embodiments, the divider 314 may divide the interior of the cask into four quarters. In some embodiments, these four quarters may generally be equal (e.g., for end fitting waste and calandria tube / pressure tube waste). In some embodiments, these four quarters may not be equal for shielding purposes (e.g., for calandria tube insert waste). Different lengths of dividers 314 may be used for different waste containers. For example, a longer divider 314 may be used to accommodate sixteen small waste containers (e.g., casks 300b and 300c) and a shorter divider may be used to accommodate four large waste containers (e.g., 300a). This may be done because the height of one large waste container may be shorter than that of four small waste containers stacked on top of each other. In some embodiments, the divider 314 may be shaped, angled, or include cutaways to provide clearance for or accommodate the waste, the cover, or other components of the cask 300. Casks 300 according to this disclosure are not limited to the illustrated configurations and other configurations are possible.

[0098] In some embodiments, the divider 314 may be omitted and the cask 300 may be usable as a single large disposal opening. This may be advantageous to dispose of miscellaneous, for example, metallic waste, that does not necessarily require a divider and may be stored with casks 300 containing the end fitting, calandria tube / pressure tube, and / or calandria tube insert waste.

[0099] Optional accessory mounting bars (not shown) can enable the attachment of impact limiters or additional shielding plates if needed.

[0100] In some embodiments, the cask 300 may be all-steel (e.g., comprised of an entirely steel outer shell and top that provides the majority of the shielding). In some embodiments, it may be steel and concrete (e.g., heavy concrete). In some embodiments, lead may be used. The cask300 may be configured to accommodate four large waste containers or sixteen small waste containers. In some embodiments, such as those illustrated in FIG. 3A-C the cask 300 may be cylindrical in shape. Other shapes are conceived (described below).

[0101] According to an aspect, there is provided a waste storage cask 300 for radioactive waste. The cask 300 including a main body 304 configured to receive the radioactive waste, a cover 310, and removable overpack shielding 306, 312 configured to be removed after an amount of time has elapsed. The main body 304 and the cover 310 are configured to couple to form at least one primary seal. The main body 304 and the removable overpack shielding 306, 312 together attenuate radiation emitted from the radioactive waste below a threshold when the radioactive waste is freshly sealed in the cask 300. The main body 304 attenuates radiation emitted from the radioactive waste below the threshold after the amount of time has elapsed.

[0102] In some embodiments, the removable overpack shielding 306, 312 is configured to be removed to accommodate the installation of impact limiters.

[0103] In some embodiments, the removable overpack shielding 306, 312 is selected based on the identity of the radioactive waste.

[0104] In some embodiments, the cover 310 includes a primary port for leak testing the at least one primary seal.

[0105] In some embodiments, the removable overpack shielding 306, 312 includes removable side overpack shielding 306.

[0106] In some embodiments, the main body 304 is cylindrical.

[0107] In some embodiments, the radioactive waste is one of calandria tube inserts, calandria tubes / pressure tubes, and end fittings.

[0108] In some embodiments, the cask 300 further includes at least one of trunnions, slots, and pockets 302.

[0109] In some embodiments, the cask 300 further includes trunnions 302 and feet 308. The trunnions 302 align with the feet 308 from a top perspective.

[0110] In some embodiments, an interior of the main body 302 is configured with a divider 314 that subdivides the interior into compartments, and each of the compartments is configured to receive the radioactive waste.

[0111] In some embodiments, the divider 314 is at least one of shaped, angled, or cutaway.

[0112] In some embodiments, the compartments comprise at least four compartments.

[0113] In some embodiments, four of the at least four compartments are configured to receive a stack of one or more calandria tube / pressure tube or end fitting waste containers, and two opposing compartments are configured to receive a stack of one or more calandria tube insert waste containers.

[0114] In some embodiments, the main body 304 is configured to receive a shielding liner 315.

[0115] In some embodiments, the shielding liner 315 is selected based on the identity of the radioactive waste.

[0116] In some embodiments, the radioactive waste includes a stack of one or more waste containers.

[0117] In some embodiments, the overpack shielding 306 is configured to cover a portion of an exterior of the main body 304.

[0118] In some embodiments, the portion includes the exterior surface between two flanges.

[0119] In some embodiments, wherein the overpack shielding 306 has an opening to receive a trunnion 302 on the main body 304.

[0120] FIG. 3D-3G illustrates top views of the interior of four different casks 300d, 300e, 300f and 300g, according to some embodiments.

[0121] The casks 300d, 300e, 300f and 300g show different configurations of dividers 314. The dividers 314 can be configured based on the type of waste intended to be included therein. The casks 300d, 300e, 300f and 300g may be configured such that they can receive any divider 314 based on, for example, the type of waste to be included therein.

[0122] In some embodiments, casks 300d and 300e may include inner shielding 315. The inner shielding 315 may line the interior of the cask main body 304. The inner shielding 315 may be provided, for example, to absorb radiation emitted from the contents of the casks 300d and 300e. In some embodiments, the inner shielding 315 may be used, for example, for waste with higher radioactivity. The inner shielding 315 may be useful to configure the casks 300d and 300e to hold highly radioactive waste (e.g., calandria tube inserts). This may be beneficial because it can configure the cask 300d and 300e to hold more radioactive waste while still providing the comparable radiation dose outside the cask while keeping the outer dimensions of the cask the same for tooling. The inner shielding 315 can make the casks 300d and 300e usable for a wider range of radioactive waste while only providing the additional shielding where needed (and thus using extra material and weighing more only when needed).

[0123] In some embodiments, the inner shielding 315 may be configured to be removed if, for example, waste with lower radioactivity, may replace the waste with higher radioactivity.

[0124] FIG. 16A-B illustrates casks 1600 with the side overpack shielding 1606 being installed thereon, according to some embodiments.

[0125] In some embodiments, the side overpack shielding 1606 can be mounted to the cask main body 1604 in two pieces that envelop opposite sides of the cask main body 1604. The over pack shielding 1606 can be coupled to the cask. The overpack shielding 1606 may also have a shielding plate (not pictured) installed along the seam between the two pieces of the side overpack shielding 1606. The overpack shielding 1606 may also shielding rings (not pictured) around the seam of the trunnions. The shielding plate and shielding rings may be useful to attenuate the radiation travelling through gaps in the overpack shielding 1606.

[0126] In some embodiments, the overpack shielding may comprise two portions 1606. These portions 1606 may be configured to mate with each other at, for example, the seam. For example the first portion 1606 may have a projection 1607a as a mating surface and the second portion 1606 may have a groove 1607b as a mating surface to receive the projection 1607a. Such configurations may be advantageous to eliminate any straight paths from the exterior of the cask through a gap between the overpack shielding 1606 to ensure that any radiation needs to travel through (and be attenuated by) at least part of the overpack shielding 1606.

[0127] In some embodiments, the overpack shielding 1606 includes a first portion and a second portion, the first portion configured to couple to the second portion to define at least a portion ofan exterior surface of the cask 1600. For example, the overpack shielding may be configured to fit substantially in the space between an upper flange of the cask 1600 and a lower flange of the cask 1600.

[0128] In some embodiments, the first portion has a first mating surface configured to couple to a second mating surface of the second portion.

[0129] In some embodiments, the first mating surface defines a projection 1607a configured to be received in a groove 1607b defined in the second mating surface. For example, the coupled portions may be configured to reduce or eliminate a straight line of travel for radiation from the cask 1600 to ensure emitted radiation must travel through at least some of the overpack shielding 1606.

[0130] Packing Details.

[0131] Referring to FIG. 1 , in some embodiments, the casks 100 may be loaded with waste. In some embodiments, the cover 110 may be removed from cask main body 104. Waste may then be inserted into the interior of the cask main body 104. In some embodiments, the cask main body 104 may include a divider. In such embodiments, the waste may be aligned to insert into a destination compartment prior to insertion. In some embodiments, the waste may include a waste container (e.g., a large waste container). In some embodiments, the waste may include a stack of waste containers (e.g., small waste containers). In some embodiments, stacks of waste may be inserted a single waste container at a time or with the whole stack at once. In some embodiments, the cask 100 can be sealed.

[0132] Referring to FIG. 2, some embodiments may include an angular guide 222 to guide waste (e.g., waste containers) into the interior of the casks 200. As illustrated, the angular guides 222 may be situated on the divider 214. The angular guides 222 may aide in orientation and / or positioning of waste containers and / or waste when inserted into the cask 200. In an example, angular guides 222 may interface with a counterpart groove (not shown) is a waste container for guiding the waste container into the interior of casks 200. Angular guides 222 as illustrated may provide an inclined surface to gently shift any inserted waste containers and / or waste towards the center of the compartment (e.g., away from the sides). In some embodiments, the angular guides 222 may be positioned elsewhere (e.g., on the interior wall of the cask 200). As illustrated the angular guides 222 provide a chamfered surface. In some embodiments, the angular guide 222 may be chamfered or beveled. Positioning waste containers or waste appropriately can aide indosage management (e.g., by ensuring the radioactive waste is correctly positioned within the cask 200 and shielded suitably).

[0133] Referring to FIG. 6, some embodiments may include a chamfered edge 624. This feature may also aide in the orientation and / or positioning of waste containers and / or waste when inserted into the cask 600. The chamfered edge 624 may follow the entire interior perimeter (or circumference) of the inner edge of the cask 600 or the edge may be partially chamfered. The chamfered edge 624 may comprise a single angle or it may offer a rounded interior edge (e.g., a smooth transition from top lip to inner wall). Other angle transitions are conceived. The chamfered edge 624 may provide similar technical benefits as those described for the angular guides 222 described above.

[0134] Referring to FIG. 1 , in some embodiments, waste may be removed from the cask 100 and replaced with other waste. In such embodiments, the cask 100 may be unsealed and, for example, reconfigured to accommodate the new type of waste. For example, a divider may be added, removed, or replaced by a different divider. A shielding liner may be added, removed, or replaced with a different shielding liner. A spacer may be added, removed, or replaced with a different spacer. Other reconfigurations are also conceived. These reconfigurations may be based on the incoming waste (e.g., where the incoming waste type is different than the waste which was removed), changing regulations, or other reasons. Once the new waste is inserted, then the cask 100 may be resealed.

[0135] Spacer and Shielding Liner Details.

[0136] FIG. 4 illustrates a cross-sectional view of a cask 402 configured for large waste containers and a cask 404 configured for small waste containers, according to some embodiments.

[0137] FIG. 4 illustrates that spacers 408 can be used for different cask configurations. For example, one large waste container may be shorter than four small waste containers stacked on top of each other. As such, to configure the cask 402 for large waste containers (as used to dispose of end fittings), a spacer 408 can be provided at the bottom of the interior of the cask 402. The spacer 408 can ensure that the waste containers are level with the cover of the cask to ensure a tight seal with uniform properties as between casks 402 with large waste containers and casks 404 with small waste containers. To configure the cask 404 for small waste containers (e.g., asused to dispose of calandria tubes / pressure tubes or calandria tube inserts), a spacer 408 may not be used.

[0138] In some embodiments, shielding liners for the small waste containers with calandria tube inserts may allow the cask exterior to remain unchanged as between the other configurations. In some embodiments, the shielding liners enables the exterior cask design to be the same (e.g., same trunnions, same side overpack shielding, etc.) over different types of waste while still providing sufficient shielding of the waste.

[0139] In some embodiments, the cask 402 further includes a spacer 408 to increase a height of the stack of the one or more waste containers to meet the bottom of the cover.

[0140] Trunnion Alignment.

[0141] FIG. 5 illustrates trunnion placement, according to some embodiments.

[0142] In some embodiments, the trunnion (or other mounting / pivoting points) positioning may minimize the footprint of the casks. For example, in cask 502, the trunnions 506 are not aligned with the feet 508 which may generate a greater width than other configurations. As a further example, in cask 504, the trunnions 510 are aligned with the feet 512 which economizes the footprint of cask 504. By aligning the trunnions 510 with the feet 512, a greater number of casks 504 can fit in the same amount of space when compared to casks 502 that do not align the trunnions 506 with the feet 508.

[0143] Overpack Shielding.

[0144] Referring to FIG. 3A-C, in some embodiments, the casks 300 can be configured to have removable overpack shielding (e.g., side overpack shielding 306 and top overpack shielding 312). The advantage of removable overpack shielding can be that the shielding is removable for transportation. In an aspect, another advantage may be that the overpack shielding can be removed after the cask 300 has been in storage for, for example, fifty years (and the rate of radioactivity has decreased).

[0145] In some embodiments, the thickness of the shielding materials can be unified for all waste types. This may be achieved by adding extra shielding in the shielding liner and / or by filling the cask 300 to, for example, half capacity (see, e.g., cask 300b).

[0146] In some embodiments, the cask 300 may be used for calandria tube insert waste and the thickness of the shielding required may be higher. In such embodiments, different approaches may be used. For example, a shielding liner can be added into a small waste container and the number of calandria tube inserts in the waste container can be reduced (though small waste containers with calandria tube inserts may need to be changed more often while processing the reactor face). As another example, the overpack shielding may be kept the same as between the different cask 300 containers, but shielding could be added within casks 300 for calandria tube inserts. This may reduce the number of small waste containers with calandria tube inserts per cask 300 (e.g., producing an additional cask 300). For the overpack shielding, an additional plate may be added on the cover 310. In such embodiments, the number of small waste containers with calandria tube inserts in each cask 300 may be reduced to eight.

[0147] In some embodiments for overpack shielding, the shielding plate design can be universal for all cask 300 configurations. The cask 300 in the calandria tube insert configuration may have the same side shielding plates as for end fitting and calandria tube / pressure tube, and an additional plate may be added on the cover 310.

[0148] Seal and Shipping Cover.

[0149] FIG. 6 illustrates a prospective view of the interior components of a primary seal 608, according to some embodiments.

[0150] The cask 600 may comprise, for example, a cask main body 602. The cask main body 602 may generally share the same description and variations as described for the cask main body 104 of FIG. 1. A cover may be configured to coupled to the cask main body 602 at primary seal 608. In some embodiments, the primary seal 608 may comprise an O-ring (as illustrated). Other seals are also possible.

[0151] In some embodiments, an alignment pin or guide 606 may be provided. The alignment pin or guide 606 can be used to ensure that the cover may be properly aligned with the cask main body 602.

[0152] In addition to a cover, in some embodiments, the cask may be equipped with a cap (e.g., top overpack shielding, a shielding cap, or a shipping cover). Top overpack shielding may provide additional radiation attenuation to the top of the cask which may be removable. The shielding cap may be a permanent fixture to provide radiation attenuation to the top of the caskand safety during transportation. Shipping covers may be used during shipping to provide a contingency in the event of damage to the lid. For example, when the cask is dropped, if an impact limiter (as described in greater detail below) is damaged, then without a transport seal, the primary seal of the lid may be damaged.

[0153] FIG. 7A illustrates a cross-sectional view of a shipping cover 710 for a cask 700, according to some embodiments.

[0154] The cask 700 may comprise, among other things, a cask main body 702 and a cover 704. The cask main body 702 and cover 704 may generally share the same description and variations as described for the cask main body 104 and cover 110 of FIG. 1. The cover 704 can be coupled to the cask main body 702 at primary seal 708. In some embodiments, the primary seal 708 may comprise a gasket that is sealed permanently to the cask main body 702. During storage, this may be sufficient to safely and securely store the cask 700.

[0155] In some embodiments, the gasket making up primary seal 708 may be a flat gasket. In some embodiments, the gasket may be an O-ring. Other possible configurations of seal are conceived. In some embodiments, the gasket may comprise, for example, rubber and / or steel. In some embodiments, other materials may be used in implementing gasket.

[0156] In some embodiments, a cushion 705 can be provided. The cushion 705 may be provided to, for example, equalize the load within the cask.

[0157] In some embodiments, an alignment pin or guide 706 may be provided. The alignment pin or guide 706 can be used to ensure that the cover 704 is properly aligned with the cask main body 702.

[0158] During transport, an additional shipping cover 710 may be applied to further secure the cask 700. For example, the shipping cover 710 may be applied on over the cover 704 onto cask main body 702 and coupled thereto. Together the shipping cover 710 and the cask main body 702 can generate the secondary seal(s) 714. The secondary seal(s) 714 may comprise one or more gaskets, for example, similar to the gasket described above with regards to the primary seal 708. Multiple secondary seals 714 may be provided for pressure testing and / or redundancy. In some embodiments, a secondary alignment pin or guide 712 may be provided similar to the alignment pin or guide 706 described above. The secondary alignment pin or guide 712 can be used to ensure that the shipping cover 710 is properly aligned with the cask main body 702.

[0159] Once the shipping cover 710 is applied, impact limiters may be installed thereto. In the event of significant damage to the impact limiters, then the shipping cover 710 may be exposed to damage. As such, this damage may impact the secondary seals 714, but leave the primary seal 708 intact. Such a design may enable the cask 700 to be safely transported in compliance with transportation of radioactive material regulations such as IAEA SSR-6.

[0160] In some embodiments, top overpack shielding may also be applied to the top of the cask 700. The top overpack shielding may couple to the cask 700 in a similar manner to the shipping cover 710. The top overpack shielding may be removed (along with any side overpack shielding) after a certain amount of time when the radioactivity within the cask has dropped and before the cask 700 may be transferred to storage.

[0161] FIG. 7B illustrates a cross-sectional view of a cask 720 with a cover 724 and shielding cap 730, according to come embodiments. Also illustrated in FIG. 7B is the side overpack shielding 721.

[0162] Instead of implementing a shipping cover 710 that is only installed for shipping, the cask 720 may be sealed in a manner that complies with transportation regulations without any additional components.

[0163] For example, the cask 720 may be equipped with a cover 724 to form the primary seal 728. In some embodiments, the primary seal 728 may comprise a gasket that is sealed permanently to the cask main body 722. During storage, this may be sufficient to safely and securely store the cask 720.

[0164] In some embodiments, the gasket making up primary seal 728 may be a flat gasket. In some embodiments, the gasket may be an O-ring. Other possible configurations of seal are conceived. In some embodiments, the gasket may comprise, for example, rubber and / or steel. In some embodiments, other materials may be used in implementing gasket.

[0165] In some embodiments, an alignment pin or guide 726 may be provided. The alignment pin or guide 726 can be used to ensure that the cover 724 is properly aligned with the cask main body 722.

[0166] In some embodiments, a shielding cap 730 may further be installed on the cask main body 722 to form the secondary seal(s) 734.

[0167] For example, the shielding cap 730 may be applied on over the cover 724 onto cask main body 722 and coupled thereto. Together the shielding cap 730 and the cask main body 722 can generate the secondary seal(s) 734. The secondary seal(s) 734 may comprise one or more gaskets, for example, similar to the gasket described above with regards to the primary seal 728. Multiple secondary seals 734 may be provided for pressure testing and / or redundancy. In some embodiments, a secondary alignment pin or guide 732 may be provided similar to the alignment pin or guide 726 described above. The secondary alignment pin or guide 732 can be used to ensure that the shielding cap 730 is properly aligned with cask main body 722.

[0168] A shipping cover 710 (or top overpack shielding) may be configured with components to aid in subsequent removal. Removing the shipping cover 710 (or top overpack shielding) may be advantageous as it can be removed when no longer needed (e.g., when not being transported or after the radioactivity of the interion waste has dropped). The shielding cap 730 may be configured as a permanent feature of the cask once sealed. The shielding cap 730 may not require additional components to aid in subsequent removal (e.g., no openings for bolts). This can be advantageous to reduce the manufacturing complexity and reduce the complexity of transportation processes (no shipping cover 710) needs to be installed thereto.

[0169] In some embodiments, the main body 702, 722 is configured to couple to a cap 710, 730 positioned over the cover 704, 724, and the main body 702, 722 and the cap 710, 730 are configured to couple to form at least one secondary seal 714, 734.

[0170] According to an aspect, there is provided a waste storage cask 700, 720 for radioactive waste. The cask 700, 720 including a main body 702, 722 configured to receive the radioactive waste, a cover 704, 724, and a cap 710, 730. The main body 702, 722 and the cover 704, 724 are configured to couple to form at least one primary seal 708, 728. The main body 702, 722 and the cap 710, 730 are configured to couple to form at least two secondary seals 714, 734.

[0171] FIG. 8 illustrates a cross-sectional view of a shipping cover 810 for a cask 800 and a magnified view of same, according to some embodiments.

[0172] The cask 800 may comprise, among other things, a cask main body 802 and a cover 804. The cover 804 can be coupled to the cask main body 802 at primary seal 808. An additional shipping cover 810 may be applied to further secure the cask 800. The shipping cover 810 and the cover 804 may generate the secondary seals 814. The cask 800 and its components (cask main body 802, cover 804, primary seal 808, shipping cover 810, and secondary seals 814) mayall share the same general description and variations as described above for cask 700 and its components (cask main body 702, cover 704, primary seal 708, shipping cover 710, and secondary seals 714) of FIG. 7A. Additionally, the cask 800 may be configured for a shielding cap or top overpack shielding.

[0173] The shipping cover 810 may include a port 826 which may be used for pressure testing. In some embodiments, ports 826 may be included within for example the cover 804, the shipping cover 810, or other components of the cask 800. Such ports 826 may be useful for pressure testing the primary and / or secondary seals 808 and 814. As illustrated in FIG. 8, the port 826 may be disposed between the secondary seals 814 (e.g., between two O-rings) to check the pressure therebetween. In some embodiments, there may be multiple separate ports 826 to check the integrity of the seals 808 and 814. In some embodiments, there may be a port 826 to leak-check the primary seal 808. In some embodiments, there may be a port 826 to leak-check the secondary seals 814 (e.g., the O-rings). In some embodiments, a pressure test may be used during initial sealing to ensure that the cover 804 has been installed properly. In some embodiments, a pressure test may be used to ensure that any shipping covers 810 have been installed correctly. In some embodiments, pressure tests may be carried out after transporting the cask 800 to ensure that the cask 800 is still sealed. For example, the pressure test of the primary seal 808 may be checked to ensure that the shipping cover 810 can be removed. As a further example, the shipping cover 810 may be checked for leaks, for example, before removing any impact limiters. Ports 826 may be installed elsewhere for other reasons.

[0174] In accordance with one aspect, there is provided a waste storage cask 800 for radioactive waste. The cask 800 includes a main body 802 configured to receive the radioactive waste and a cover 804. The cask main body 802 and the cover 804 can couple to form a primary seal 808. The cask main body 802 may be further configured to couple to a shipping cover (or shielding cap) 810 to generate secondary seal(s) 814. The main body 802 and the cover 804 are configured to couple to form a primary seal 808.

[0175] Additional ports may be used to test leaks elsewhere. Such testing may be used to develop a cask or to check the integrity of the seals at some point during storage. An additional port in, for example, the cover 804 configured to test the space between, for example, the primary seal 808 and any secondary seals 814 (e.g., over the cover 804) can be used to test the integrity of the primary seal 808. As described above, a port 826 positioned between any secondary seals 814 to test the integrity of same.

[0176] In some embodiments, the cap 810 includes a secondary port 826 for leak testing the at least one secondary seal 814.

[0177] Impact Limiters.

[0178] FIG. 9 illustrates a prospective view of a cask 900 with impact limiters 914, according to some embodiments.

[0179] Cask 900 includes cask main body 904, impact limiters 914, and connecting members 916. The cask 900 and its components may all generally share the same general description and variations as described above. The impact limiters 914 are structures that can be installed to the top and bottom of the cask main body 904 during the transport of the cask 900 to a, for example, long-term storage site. The connecting members 916 illustrate one exemplary way to install impact limiters 914, e.g., to provide tension keeping both impact limiters 914 secure on the cask main body 904.

[0180] In some embodiments, it may be beneficial to install impact limiters 914 on the cask 900 for transportation. For example, the cask 900 may be loaded with waste, for example, during retubing processes or decommissioning processes, then sealed. At this point the waste may need to be transported elsewhere for storage or for further processing.

[0181] FIG. 10 illustrates a cross-sectional view of a cask 900 along line 10-10 with impact limiters 914, according to some embodiments.

[0182] The cask 900 may be configured to transform to a transport flask by removing the side overpack shielding and foot weldment, and installing impact limiters 914.

[0183] Cask 900 includes cask main body 904, impact limiters 914, and connecting members 916. Visible in this figure are the cover 1018 and shipping cover 1020 (as were described in reference to FIG. 7A). In some embodiments, a cask sealed with a cover and a shielding cap (as described with reference to FIG. 7B).

[0184] As described above, should cask 900 experience an accident, impact limiters 914 may receive the brunt of the impact force. However, should the incident be sufficiently powerful, then the impact limiters 914 may become compromised. In such a situation, shipping cover 1020 (or the shielding cap) may absorb further damage before the cover 1018 is damaged. This mayenable the cask 900 to withstand more severe accidents and may enable it to comply with stricter requirements for the transport of radioactive waste.

[0185] A flange at the bottom of the cask 900 may enable identical impact limiter 914 designs to be used on either side of the cask 900. This may cut down on the manufacturing costs and complexity for the impact limiters 914.

[0186] In some embodiments, the removable overpack shielding is configured to be removed to accommodate the installation of impact limiters 914.

[0187] Specific Example Cask Configurations.

[0188] Calandria Tube / Pressure Tube Waste.

[0189] FIG. 11A illustrates a prospective view of a cask 1100 which is configured for receiving pressure tube / calandria tube waste, according to some embodiments.

[0190] FIG. 11 B illustrates a cross-sectional view along the line 11 B-11 B of the cask 1100, according to some embodiments.

[0191] The cask 1100 may include trunnions 1102, a cask main body 1104, side overpack shielding 1106, feet 1108, a cover 1110, and top overpack shielding 1112. In general, the cask 1100 and its components share the qualities, as appropriate, as those described for cask 300c and its components in FIG. 3C.

[0192] As described above, calandria tube and pressure tube waste may be stored in small waste containers. The small waste containers can fit in stacks of four per column within cask 1100. Owing to the radioactive properties of the calandria tube and pressure tube waste, four stacks may safely be stored within the cask 1100 while providing sufficient shielding for a total of sixteen small waste containers. The overpack shielding (e.g., side overpack shielding 1106 and top overpack shielding 1112) may offer additional shielding during storage and may be configured to be removed for transportation and / or after fifty years of storage.

[0193] Calandria Tube Insert Waste.

[0194] FIG. 12A illustrates a prospective view of a cask 1200 configured for calandria tube insert waste, according to some embodiments.

[0195] FIG. 12B illustrates a cross-sectional view along the line 12B-12B of the cask 1200, according to some embodiments.

[0196] The cask 1200 may include trunnions 1202, a cask main body 1204, side overpack shielding 1206, feet 1208, a cover 1210, and top overpack shielding 1212. In general, the cask 1200 and its components share the qualities, as appropriate, as those described for cask 300b and its components in FIG. 3B.

[0197] As described above, the waste for calandria tube inserts may be stored within small waste containers. The small waste containers can fit in stacks of four per column within cask 1200. Owing to the radioactive properties of the calandria tube inserts, two stacks may safely be stored within the cask 1100 while providing sufficient shielding for a total of eight small waste containers. To accommodate this, the cask 1100 can be equipped with a wider insert that only permits two stacks to be inserted into the cask 1100 on opposite quarters leaving the remaining space for shielding. The overpack shielding (e.g., side overpack shielding 1206 and top overpack shielding 1212) may offer additional shielding during storage and may be configured to be removed for transportation and / or after fifty years of storage.

[0198] End Fitting Waste.

[0199] FIG. 13A illustrates a prospective view of a cask 1300 configured for end fitting waste, according to some embodiments.

[0200] FIG. 13B illustrates a cross-sectional view along the line 13B-13B of the cask 1300, according to some embodiments.

[0201] The cask 1300 may include trunnions 1302, a cask main body 1304, side overpack shielding 1306, feet 1308, a cover 1310, and top overpack shielding 1312. In general, the cask 1300 and its components share the qualities, as appropriate, as those described for cask 300a and its components in FIG. 3A.

[0202] As described above, the waste for end fittings may be stored within large waste containers. The large waste containers can fit in stacks of one per column within cask 1300. Owing to the radioactive properties of the end fitting waste, in an example, four large waste containers can be safely stored within the cask 1300 while providing sufficient shielding for the four large waste containers. The large waste containers may be slightly shorter than the small waste containers. To accommodate this, the cask 1300 can be equipped with a spacer that addsa small amount of height to the large waste containers such that they reach the same height as four small waste containers to provide a tight fit to the large waste containers. The overpack shielding (e.g., side overpack shielding 1306 and top overpack shielding 1312) may offer additional shielding during storage and may be configured to be removed for transportation and after fifty years of storage. The side overpack shielding 1306 may only cover, for example, a bottom portion of the cask main body 1304.

[0203] Alternative Designs.

[0204] Shape.

[0205] In some embodiments, the cask may be rectangular rather than cylindrical. In some embodiments, the cask may be a larger cylinder capable of holding six stacks of waste container (i.e. , six large waste containers or twenty-four small waste containers). The choice of shape may impact the simplicity of the tooling and the process.

[0206] FIG. 14 illustrates a comparison of three different shapes for the cask, according to some embodiments.

[0207] In some embodiments, the cask 1402 comprises a cylindrical design capable of holding four large waste containers or four stacks of four small waste containers. Cask 1402 generally follows the same design as described above for FIG. 3A-C.

[0208] A round four-column cask 1402 may be a monolithic cylindrical body that can be forged and then cavity machined out. The monolithic cylindrical body can be forged or rolled. The lid and bottom can be forged separately and attached. A forged cask body may provide high strength. The weight may be configured to be less than 50,000 kg. More casks would be required than for a six-column cask 1406, but the savings on manufacturing may nonetheless make this option more affordable.

[0209] In some embodiments, the cask 1404 comprises a rectangular or square design capable of holding four large waste containers or four stacks of four small waste containers. In such embodiments, the outer shell’s thick bottom and wall plates can be attached to each other with fasteners. Four lifting trunnions may be spigotted into and bolted onto the wall plates.

[0210] A rectangular or square four column cask 1404 may be a monolithic rectangular or square body that can be forged and cavity machined out. The cask 1404 may be machined fromplates and assembled. Assembled rectangular or square cask structures may create high stress points on the corners which may require additional design considerations. The weight may be configured to be less than 50,000 kg. More casks would be required than for a six-column cask 1406, but the savings on manufacturing may nonetheless may this option more affordable.

[0211] In some embodiments, the cask 1406 comprises a cylindrical design capable of holding six large waste containers or six stacks of four small waste containers.

[0212] A round six-column cask 1406 may also be a monolithic cylindrical body that can be forged and then cavity machined out. The monolithic cylindrical body can be forged or rolled. The lid and bottom can be forged separately and attached. However, there may be size limitations on the diameter of the forged cylinder. The cost may be higher due to the deep cavity to machine. A forged cask body may provide high strength. The weight may be higher than 50,000 kg. Such a cask may require complex tooling solutions when compared to the round four-column cask 1402.

[0213] Cask Materials.

[0214] In some embodiments, the cask is made from steel and concrete (e.g., heavy concrete). Such embodiments may comprise a steel / concrete main body with an all-steel top that provides shielding and air-tight containment.

[0215] FIG. 15 illustrates a cross-sectional view of a rectangular cask 1500 made from steel and concrete, according to some embodiments.

[0216] The body may comprise a hollow weldment with an inner wall 1502 and an outer wall 1504. The hollow void may be filled with concrete 1506 (e.g., heavy concrete). Four lifting trunnions 1508 may be embedded into the concrete 1506 and welded onto the outer walls 1504.

[0217] In some embodiments, the top may be made of two pieces 1510 and 1512. In some embodiments, the thinner and smaller plate 1512 at the bottom can be changed from steel to tungsten for improved shielding. There may be a metal seal sandwiched between a top surface on the body and the underside of the cask.

[0218] In some embodiments, inside the body can be a divider weldment 1514 that helps keep waste containers in place after placement into the cask 1500. Also inside the body is a spacer weldment 1516, which may be used to adjust the height of the waste containers (e.g., to increase the height of the large waste container).

[0219] In some embodiments, the cask 1500 can have feet 1518 that enable the use of a transporter or forklift truck to move it. These feet 1518 may be removable to enable the attachment of impact limiters needed when long distance transportation is required.

[0220] In some embodiments, accessory mounting bars 1520 enable the attachment of impact limiters and additional shielding plates.

[0221] In some embodiments, an all-steel cask may have a smaller footprint than a steel and concrete cask. An all-steel cask may be stronger and / or have greater structural integrity. In some embodiments, the all-steel cask may not require a spacer inside for large waste container because a shorter liner may be relatively easy to install. In some embodiments, the steel and concrete cask may be lower in cost to manufacture. In some embodiments, the all-steel cask may not require any special processing. In some embodiments, steel plates can be bolted together which may maintain machined accuracy.

[0222] In some embodiments, the concrete may be heavy concrete. In some embodiments, other materials may be used. For example, in some embodiments lead may be used. Lead exhibits excellent radioactivity absorption and may be advantageous in some embodiments.

[0223] Further Considerations.

[0224] In some embodiments, shielding analyses can be performed to ascertain the depth of shielding on the cask to meet surface radiation requirements. In some embodiments, overpack plates may also be used when necessary.

[0225] In some embodiments, the casks may be designed such that the maximum weight (when filled and including overpack plates) can be less than the capacity of transportation infrastructure (e.g., a crane). This can ensure that the casks can be moved using transportation infrastructure. In some embodiments, lifting points can be added to the cask to aid in lifting.

[0226] In some embodiments, materials for the casks are selected to resist to radiation such that their ability to contain the contents of the cask is not compromised.

[0227] In some embodiments, swivel lifting rings can be used to lift and attach overpack plates to the cask. In such embodiments, procedures can be written such that these items can be removed once the plates are attached such that they are not used for lifting the cask. These itemsmay also be removed prior to the cask entering the container loading interface. In some embodiments, lifting the cask is done using the trunnions (or other pivoting / mounting point).

[0228] According to an aspect, there is provided a method of storing radioactive waste, the method including providing a cask described herein and inserting a stack of the one or more waste containers into the cask, wherein the top surface of the stack meets the bottom of the cover.

[0229] Implementation Details.

[0230] The foregoing discussion provides many example embodiments. Although each embodiment represents a single combination of inventive elements, other examples may include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, other remaining combinations of A, B, C, or D, may also be used.

[0231] 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.

[0232] 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).

[0233] 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.

[0234] 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 subratios falling within the broader ratio.

[0235] 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.

[0236] 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.

[0237] Although the embodiments have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope as defined by the appended claims.

[0238] Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps

[0239] As can be understood, the examples described above and illustrated are intended to be exemplary only.

Claims

WHAT IS CLAIMED IS:

1. A waste storage cask for radioactive waste, the cask comprising: a main body configured to receive the radioactive waste; a cover, wherein the main body and the cover are configured to couple to form at least one primary seal; and removable overpack shielding configured to be removed after an amount of time has elapsed; wherein the main body and the removable overpack shielding together attenuate radiation emitted from the radioactive waste below a threshold when the radioactive waste is freshly sealed in the cask; and wherein the main body attenuates radiation emitted from the radioactive waste below the threshold after the amount of time has elapsed.

2. The cask of claim 1 , wherein the main body is configured to couple to a cap positioned over the cover, and the main body and the cap are configured to couple to form at least one secondary seal.

3. The cask of claim 2, wherein the cap comprises a secondary port for leak testing the at least one secondary seal.

4. The cask of claim 1 , wherein the removable overpack shielding is configured to be removed to accommodate the installation of impact limiters.

5. The cask of claim 1 , wherein the removable overpack shielding is selected based on the identity of the radioactive waste.

6. The cask of claim 1 , wherein the cover comprises a primary port for leak testing the at least one primary seal.

7. The cask of claim 1 , wherein the removable overpack shielding comprises removable side overpack shielding.

8. The cask of claim 1 , wherein the main body is cylindrical.

9. The cask of claim 1 , wherein the radioactive waste is one of calandria tube inserts, calandria tubes / pressure tubes, and end fittings.

10. The cask of claim 1 , further comprising at least one of trunnions, slots, and pockets.

11. The cask of claim 1 , further comprising trunnions and feet, wherein the trunnions align with the feet from a top perspective.

12. The cask of claim 1 , wherein: an interior of the main body is configured with a divider that subdivides the interior into compartments; and each of the compartments is configured to receive the radioactive waste.

13. The cask of claim 12, wherein the divider is at least one of shaped, angled, or cutaway.

14. The cask of claim 12, wherein the compartments comprise at least four compartments.

15. The cask of claim 14, wherein: four of the at least four compartments are configured to receive a stack of one or more calandria tube / pressure tube or end fitting waste containers; and two opposing compartments are configured to receive a stack of one or more calandria tube insert waste containers.

16. The cask of claim 1 , wherein the main body is configured to receive a shielding liner.

17. The cask of claim 16, wherein the shielding liner is selected based on the identity of the radioactive waste.

18. The cask of claim 16, further comprising a spacer to increase a height of the stack of the one or more waste containers to meet the bottom of the cover.

19. The cask of claim 1 , wherein the radioactive waste comprises a stack of one or more waste containers.

20. The cask of claim 1 , wherein the overpack shielding is configured to cover a portion of an exterior of the main body.21 . The cask of claim 20, wherein the portion comprises the exterior surface between two flanges.

22. The cask of claim 1 , wherein the overpack shielding comprises a first portion and a second portion, the first portion configured to couple to the second portion to define at least a portion of an exterior surface of the cask.

23. The cask of claim 22, wherein the first portion has a first mating surface configured to couple to a second mating surface of the second portion.

24. The cask of claim 23, wherein the first mating surface defines a projection configured to be received in a groove defined in the second mating surface.

25. The cask of claim 1 , wherein the overpack shielding has an opening to receive a trunnion on the main body.

26. A waste storage cask for radioactive waste, the cask comprising: a main body configured to receive the radioactive waste; a cover, wherein the main body and the cover are configured to couple to form at least one primary seal; and a cap, wherein the main body and the cap are configured to couple to form at least two secondary seals.

27. A method of storing radioactive waste, the method comprising: providing a cask of any one of claims 1-26; and inserting a stack of the one or more waste containers into the cask, wherein the top surface of the stack meets the bottom of the cover.