Disposing of vitrified waste

Abstract

The hazardous waste repository includes a borehole formed from the earth's surface through one or more subsurface formations. The borehole includes a storage portion formed within at least one of the one or more subsurface formations. The hazardous waste repository includes a portion of vitrified hazardous waste, the portion of vitrified hazardous waste enclosed within the enclosure of at least one high-level waste canister (HLWC), excluding the outer canister. The HLWC is located within the storage portion.

Description

[Technical Field]

[0001] The present disclosure relates to systems and methods for disposing of vitrified waste, and more particularly to systems and methods for disposing of vitrified nuclear waste in boreholes formed in subterranean formations. [Background technology]

[0002] Hazardous waste is often placed in long-term, permanent, or semi-permanent storage facilities to prevent health problems among residents living near the stored waste. Such hazardous waste storage facilities are often challenging, for example, in terms of site identification and containment assurance. For example, the safe storage of nuclear waste (whether from spent nuclear fuel, commercial power reactors, test reactors, or even military waste) is considered one of the unsolved challenges in energy technology. Safe storage of long-term radioactive waste is a major obstacle to the adoption of nuclear power in the United States and around the world. Traditional waste storage methods emphasize the use of tunnels, exemplified by the design of the Yucca Mountain storage facility. Other techniques include boreholes, which involve vertical boreholes drilled into crystalline bedrock. Other conventional techniques involve forming tunnels with boreholes emerging from the tunnel walls in shallow formations to allow human access. Summary of the Invention [Means for solving the problem]

[0003] In one exemplary implementation, the hazardous waste repository includes a borehole formed from the earth's surface through one or more subsurface formations. The borehole includes a storage portion formed within at least one of the one or more subsurface formations. The hazardous waste repository includes a portion of vitrified hazardous waste, the portion of vitrified hazardous waste enclosed within the enclosure of at least one high-level waste canister (HLWC), excluding the outer canister. The HLWC is located within the storage portion.

[0004] In certain aspects that can be combined with example implementations, the housing of the HLWC is insufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation, and the housing of the outer canister is sufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation.

[0005] In another aspect that may be combined with any of the preceding aspects, the housing of the HLWC is about 45 cm in diameter.

[0006] In another aspect that may be combined with any of the preceding aspects, the vitrified hazardous waste includes at least one of vitrified nuclear waste, vitrified chemical waste, vitrified biological waste, or crush-resistant waste packaging.

[0007] In another aspect that may be combined with any of the preceding aspects, the nuclear waste includes at least one of cesium-137 or strontium-90 capsules, spent nuclear fuel pellets, vitrified nuclear waste including nuclear fuel encased in glass, one or more pieces of a melted nuclear core, calcined waste including granular solids, pebble bed reactor pellets, or a portion of transuranic waste.

[0008] In another aspect that may be combined with any of the preceding aspects, the housing of the HLWC includes a mounting member formed on or coupled to an end of the housing.

[0009] In another aspect that may be combined with any of the preceding aspects, the attachment member includes a knob.

[0010] In another aspect that may be combined with any of the preceding aspects, the attachment member is configured to be attached to a downhole transport device.

[0011] In another aspect that may be combined with any of the preceding aspects, the downhole transportation device includes one of wireline, slickline, coiled tubing, drill pipe, or a downhole tractor.

[0012] Another aspect that may be combined with any of the preceding aspects further includes a casing disposed in the borehole.

[0013] Another aspect that may be combined with any of the preceding aspects further includes a seal positioned within the borehole.

[0014] In another exemplary implementation, a method for storing hazardous waste includes identifying a borehole formed from the earth's surface through one or more subsurface formations. The borehole includes a storage portion formed within at least one of the one or more subsurface formations. The method includes moving a portion of the vitrified hazardous waste enclosed within a high-level waste canister (HLWC) enclosure, excluding an outer canister, to a location within the storage portion.

[0015] In one aspect, which may be combined with example implementations, the housing of the HLWC is insufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation, and the housing of the outer canister is sufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation.

[0016] In another aspect that may be combined with any of the preceding aspects, the housing of the HLWC is about 45 cm in diameter.

[0017] In another aspect that may be combined with any of the preceding aspects, the vitrified hazardous waste includes at least one of vitrified nuclear waste, vitrified chemical waste, vitrified biological waste, or crush-resistant waste packaging.

[0018] In another aspect that may be combined with any of the preceding aspects, the nuclear waste includes at least one of cesium-137 or strontium-90 capsules, spent nuclear fuel pellets, vitrified nuclear waste including nuclear fuel encased in glass, one or more pieces of a melted nuclear core, calcined waste including granular solids, pebble bed reactor pellets, or a portion of transuranic waste.

[0019] Another aspect that may be combined with any of the preceding aspects includes coupling the downhole transport device to a mounting member formed on or coupled to an end of the housing of the HLWC.

[0020] In another aspect that may be combined with any of the preceding aspects, the attachment member includes a knob.

[0021] Another aspect, which may be combined with any of the preceding aspects, includes moving the HLWC on a downhole transport device through a borehole while coupled to the attachment member.

[0022] In another aspect that may be combined with any of the preceding aspects, the downhole transportation device includes one of wireline, slickline, coiled tubing, drill pipe, or a downhole tractor.

[0023] In another aspect that may be combined with any of the preceding aspects, the borehole further includes a casing disposed within the borehole.

[0024] In another aspect that may be combined with any of the preceding aspects, the borehole further includes a seal positioned within the borehole.

[0025] The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of an exemplary implementation of a hazardous waste repository according to the present disclosure.

[0027] [Figure 2] FIG. 2 is a schematic diagram of an exemplary implementation of a crush-resistant hazardous waste canister for enclosing hazardous waste within a hazardous waste repository according to the present disclosure.

[0028] [Figure 3] FIG. 3 is a schematic diagram of an exemplary implementation of a hazardous waste cask that encloses a high-level waste canister (HLWC) that encloses hazardous waste within a tunnel-type hazardous waste repository.

[0029] [Figure 4] FIG. 4 is a schematic diagram of an exemplary implementation of a high-level waste canister (HLWC) that encapsulates vitrified hazardous waste within a hazardous waste repository according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0030] Detailed Description Hazardous waste (e.g., radioactive, nuclear, chemical, biological, and other) can be disposed of in deep, inaccessible boreholes (i.e., boreholes or well bores). Public safety is typically provided by both constructed and geological barriers. Public danger arises from the fact that hazardous chemicals in the waste can dissolve in brines (or other forms of water) present within deep rock formations. This brine can migrate and transport the dissolved waste to the biosphere, where it can come into contact with humans. For example, in spent nuclear fuel, radioactive waste containing iodine-129 and chlorine-36 have sufficient half-lives that they can be transported into nearby surface aquifers by brine flow. Historically, more problematic has been the existence of potential "fast paths" to the surface, which can provide a rapid route for waste to reach the surface. To protect the public, two general approaches have been taken, often referred to as constructed containment and geological containment.

[0031] Constructed containment, in some cases, refers to the canister containing the waste. This can be a tube or spherical container designed to hold the waste and keep it away from the brine for as long a period as possible. To this end, canisters have been fabricated to be resistant to corrosion and impact, as in previous studies. Corrosion resistance can result from the use of corrosion-resistant materials either within the canister walls or as a coating for the canister. Additionally, the hydrostatic pressure of brine can be very high, typically 1 atmosphere for every 10 meters of depth. Therefore, for a depth of 1.5 km, the canister must be strong enough to withstand 150 atmospheres, which requires a thick, heavy canister capable of withstanding such pressure without suffering crushing failure or deformation that could release the waste into the formation.

[0032] Geological containment refers to a rock overburden that is thick and impermeable enough that the upward flow of brine is slow enough that hazardous levels of waste will not reach the human environment (such as freshwater aquifers) for thousands to millions of years. With regard to radioactive waste, much of the waste will be converted to non-hazardous isotopes before it can reach the surface. However, geological containment can be avoided by the existence of fast paths. Fast paths include existing earthquake faults, future earthquake faults, and the borehole itself (which forms from the surface into the formations within which the waste is stored). The idea of ​​boreholes as fast paths has received considerable attention due to the challenges of sealing them in a way that will provide protection for thousands to millions of years. Traditional sealing materials include cement, concrete, and bentonite. However, it is difficult, and perhaps impossible, to grasp what might happen to such seals over periods of hundreds, thousands, or even millions of years. In the United States, public safety must be ensured for up to one million years.

[0033] The constructed barrier, in some implementations, is a canister designed to take hundreds to thousands of years to corrode. Because the borehole typically fills rapidly with brine or other forms of water, the canister is also designed to withstand the pressures that such brine can generate. In other words, it must be able to withstand crushing. To address these issues, thicker and heavier canisters (i.e., canisters whose enclosures can withstand the pressures at the storage depth without deforming or crushing) have been proposed.

[0034] This disclosure describes example implementations of systems and methods for hazardous waste repositories in which vitrified waste is moved (temporarily or permanently) from the earth's surface into a borehole (e.g., a borehole or wellbore) formed in a subsurface formation and stored in the borehole, where the vitrified waste is separate from (i.e., not enclosed within) a hazardous waste canister (i.e., the thick (outer) canister shown in FIG. 2). These implementations take advantage of important insights not recognized by those skilled in the art of nuclear waste disposal. These are:

[0035] Fast paths do not pose significant hazards to the public because they tend to be thin (like earthquake faults) or cylindrical in shape (like access boreholes). Studies conducted by the assignee of the present application have shown that for sufficiently deep disposal, outward diffusion from a "fast path" depletes waste very rapidly as a function of vertical motion, so that waste reaching the surface is well below regulatory limits.

[0036] At depths of 500 meters to 1,500 meters and deeper, depending on the specific geology of the site, geological barriers are sufficiently effective that constructed barriers are not necessary. This has been demonstrated by careful simulations conducted by the assignee of the present application. These simulations show that a "momentary release" of the canister after the initial sealing of the borehole provides sufficient protection for humans such that long-term constructed barriers are not required to reach the strict limits of U.S. government regulations. Furthermore, geochemical techniques can be used to demonstrate that geological safety alone (without consideration of constructed barriers) may be sufficient to ensure safety.

[0037] Conventional canisters designed to store hazardous waste at a depth are designed to be able to resist crushing during the emplacement phase, with previous canister designs including "thick canister" walls sufficient to withstand the hydrostatic pressures present at disposal depths (typically 100 atmospheres per kilometer of depth). The disclosed implementations take advantage of the fact that in many instances the hazardous waste itself provides sufficient resistance to such crushing so that thick canisters are not required.

[0038] When these insights are recognized and combined in an innovative way, the resulting implementation described herein allows for significantly reduced costs, not only in the canister, but also in the borehole. Another insight is that there is no need to include a thick outer canister as a constructed barrier, as the geological barrier itself provides sufficient safety to the public.

[0039] Hazardous (e.g., radioactive or nuclear) waste that is not already a single solid piece can be made so through the same vitrification process as that used for spent nuclear fuel. In one example, chunks of other waste, including pieces of "corium" (waste from a nuclear reactor meltdown that has been solidified and broken into smaller pieces), can be placed into a relatively thin-walled canister, which is then filled with molten glass and allowed to solidify.

[0040] Accordingly, this disclosure describes implementations of hazardous waste repositories in which waste (e.g., vitrified waste) is stored in deep, inaccessible boreholes (e.g., vertical, inclined, directional, horizontal, or a combination thereof) and enclosed within high-level waste canisters including housings that are insufficient to withstand the hydrostatic pressures present at the disposal depth (typically 100 atmospheres per kilometer of depth) without deformation (e.g., crushing), but that provide at least some crush-resistance means in addition to the canister housing, e.g., due to the vitrified waste (in some cases in combination with fluids inserted into the canister to fill volume not occupied by the waste or otherwise). Other forms of non-vitrified waste, such as waste that provide some crush-resistance means, can also be enclosed within high-level waste canisters.

[0041] Furthermore, the housing of the high-level waste canister is smaller and has thinner walls as opposed to the thick outer canister described herein. From the findings enumerated above (including the sufficiency of geological isolation and the high crush resistance strength of vitrified or other filled canisters), all but the vitrified waste can be excluded from the waste package.

[0042] In some aspects, the high-level waste canister has a housing formed from a material that provides no, or an insufficient, barrier to radiation (e.g., gamma) that may travel from the enclosed radioactive waste, through the housing, and into the environment surrounding the high-level waste canister.

[0043] FIG. 1 illustrates an exemplary implementation of a hazardous waste repository 100. The hazardous waste repository 100 utilizes an underground location for the long-term (e.g., decades, centuries, or millennia or more) yet retrievable, safe, and secure storage of hazardous material, in this example, in the form of vitrified radioactive waste. In this example, vitrified hazardous waste 132, or simply vitrified waste 132 (e.g., radioactive, chemical, or biological waste, or a combination thereof), is enclosed within a high-level waste canister (HLWC) 126. In this disclosure, "vitrified waste" refers to one or more waste forms (such as highly radioactive spent nuclear fuel and / or other forms of nuclear waste) that have undergone chemical separation and been mixed with molten glass, and the mixed waste and glass (solidified through cooling) comprise a waste package (i.e., vitrified waste) that may be enclosed within the HLWC 126.

[0044] Such vitrified waste 132, in some embodiments, can be biological or chemical waste or other biologically or chemically hazardous materials. In some embodiments, vitrified waste 132 can include nuclear material, such as spent nuclear fuel recovered from a nuclear reactor (e.g., a commercial power or test reactor) or military nuclear material. For example, the nuclear material that can be combined with molten glass and formed into vitrified waste 132 can include one, some, or all (alone or in combination) of the following forms:

[0045] (1) Cesium-137 and Strontium-90 (currently temporarily stored at Hanford Laboratory, USA). This form of nuclear waste consists of a capsule 9 cm (3.5 in) in diameter and 60 cm (24 in) long.

[0046] (2) Spent nuclear fuel from commercial nuclear reactors. This form of nuclear waste consists of 1 cm pellets held in "fuel assemblies," which are rod-shaped and typically 20 cm to 30 cm in diameter (diagonal length of roughly square cross section) and 4 m in length.

[0047] (3) Previously vitrified waste. This form of nuclear waste is nuclear fuel that may have been reprocessed but is now encased in glass. The glass acts as a "constructed barrier," absorbing short-range nuclear radiation (e.g., alpha and beta particles) and partially containing radionuclides that may diffuse from the nuclear fuel. The glass cylinders are typically 30 to 45 cm in diameter and 3 meters long.

[0048] (4) Fragments of melted reactor core from a nuclear accident. This form of nuclear waste generally does not have a uniform shape or size.

[0049] (5) Calcined waste. This form of nuclear waste is formerly liquid but has been converted into a granular solid in any uniform shape or size.

[0050] (6) Generation IV Reactor Waste. This form of nuclear waste can appear in many types. One exemplary type includes fuel for "pebble bed" reactors, consisting of pellets 6.7 cm (2.6 inches) in diameter (e.g., about the size of a tennis ball). If this fuel is reprocessed (and some of it is intended for reprocessing), the final form of the fuel may be undetermined.

[0051] (7) Transuranic (or TRU) Waste. This form of nuclear waste is currently disposed of in 15- or 30-gallon drums (with diameters of 14 to 19 inches) at the Waste Isolation Pilot Plant in New Mexico.

[0052] As shown, hazardous waste repository 100 includes boreholes (or boreholes or well bores) 104 formed (e.g., drilled or otherwise) from a surface 102 through one or more subsurface formations 112, 114, 116, and 118. While surface 102 is illustrated as a surface on land, surface 102 may be a submarine or other underwater surface (such as a lake or ocean floor or other surface beneath a body of water). Accordingly, this disclosure acknowledges that boreholes 104 may be formed beneath a body of water from a drilling site on or adjacent to a body of water.

[0053] The illustrated wellbore 104, in this example, is a directional wellbore in the hazardous waste repository 100. For example, the wellbore 104 includes a generally vertical portion 106 connected to an arc or curved portion 108, which in turn is connected to a generally horizontal portion 110. As used in this disclosure, "approximately," in the context of wellbore orientation, refers to a wellbore that may not be exactly vertical (e.g., exactly perpendicular to the earth's surface 102) or exactly horizontal (e.g., exactly parallel to the earth's surface 102). In other words, those skilled in the drilling arts will recognize that vertical wellbores are often undulating and offset from a true vertical direction, that they are drilled at angles that deviate from a true vertical, and that horizontal wellbores are often undulating and offset from a true horizontal direction. Furthermore, the generally horizontal portion 110 may, in some aspects, be a deviated wellbore or other directional wellbore oriented between exactly vertical and exactly horizontal. Additionally, the generally horizontal portion 110 may, in some aspects, be a deviated or otherwise directional wellbore, for example, oriented to follow the dip of the subsurface formation 118. As illustrated in this example, the three portions of the borehole 104, namely, the vertical portion 106, the arc portion 108, and the horizontal portion 110, form a continuous borehole 104 extending into the earth. However, the borehole 104 can be any vertical, deviated, directional, horizontal wellbore, or combination thereof.

[0054] The illustrated borehole 104, in this example, has casing 120, which is positioned and configured from the surface 102 around the borehole 104 and may be comprised of one or more casing types or sizes; however, the present disclosure also contemplates that at least a portion of the borehole 104 may be open-hole completed as well. The surface formation 112, in this example, is a geological formation comprised of one or more layered rock formations. In some aspects, the surface formation 112, in this example, may or may not include a freshwater aquifer, a saltwater or brackish water source, or other mobile water source (e.g., water moving through a geological formation). In some aspects, the casing 120 may isolate the borehole 104 from such mobile water and may also provide a suspension location for other casing strings to be disposed within the borehole 104.

[0055] As shown, cement 130 is positioned (e.g., pumped) around casing 120 in an annulus between casing 120 and borehole 104. Cement 130 may, for example, anchor casing 120 (and any other casing or liner in borehole 104) through subterranean formations below surface 102. In some aspects, cement 130 may be disposed along the entire length of the casing (e.g., casing 120 and any other casing), or cement 130 may be used along a portion of the casing if appropriate for the particular borehole 104. Cement 130 may also provide an additional layer of containment for hazardous materials within HLWC 126.

[0056] This disclosure recognizes that many other layers may exist between or within the illustrated subsurface layers 112, 114, 116, and 118. For example, there may be a repeating pattern (e.g., vertically) of one or more of the mobile water layer 114, impermeable layer 116, and storage layer 118. Furthermore, in some cases, the storage layer 118 may be directly adjacent (e.g., vertically) to the mobile water layer 114, i.e., without an intervening impermeable layer 116.

[0057] In some aspects, the storage layer 118 can comprise, for example, shale or other rock formation containing a certain amount of clay material. Alternatively, the storage layer 118 can comprise a rock salt formation. However, other types of rock formations (e.g., granite, sediment, or other) are also permitted by the present disclosure as needed for storage of the vitrified waste 132. In some aspects, the borehole 104 can be lined with casing 120 or completed openhole, as described. Some formations, such as rock salt, can be sufficiently smooth that casing 120 is not required. In some cases, the casing 120 can be used during installation and for periods when the possibility of recovery of one or more of the HLWCs 126 is imposed. Since diffusion into the surrounding rock formations provides protection that prevents the waste from reaching the surface, the casing 120 can then be removed, providing further protection that prevents material from flowing back up into the borehole 104. Additionally, slotted casing may be used to allow any rising waste within the borehole 104 used to access the disposal area to be dispersed into the surrounding rock formation 118 or 116.

[0058] As shown, one or more HLWCs 126 are positioned within the generally horizontal portion 110 of the borehole 104. A seal 134 is installed within the borehole 104 between the location of the HLWC 126 within the generally horizontal portion 110 and the opening of the generally vertical portion 106 at the surface 102 (e.g., the wellhead). In this example, the seal 134 is installed at the uphole end of the generally vertical portion 108. Alternatively, the seal 134 may be positioned elsewhere within the generally vertical portion 106, within the arc portion 108, or even within the generally horizontal portion 110 above the canister 126. In some aspects, the seal 134 may be installed deeper than at least any movable water source, such as the movable water layer 114, within the borehole 104. In some aspects, the seal 134 may be formed substantially along the entire length of the generally vertical portion 106.

[0059] Prior to the retrieval operation, the seal 134 may be removed. For example, in the case of a cement or other permanently set seal 134, the seal 134 may be drilled through or otherwise broken up and removed. In the case of a semi-permanent or removable seal, such as a packer, the seal 134 may be removed from the borehole 104 through conventional processes as are known.

[0060] In this example, the HLWC 126 is not thick enough to withstand the hydrostatic pressures when placed in the wellbore 104 (e.g., in the reservoir formation 118) and will undergo at least some deformation (including crushing). However, in the exemplary implementation, the HLWC 126 itself is not enclosed within an outer thick canister that is thick enough to withstand the hydrostatic pressures present at the disposal depth.

[0061] 4 shows an example implementation of the HLWC 126. In this example, the HLWC 126 includes a relatively thin-walled (e.g., metal) housing 129 (i.e., a housing that is not sufficient to withstand the hydrostatic pressure within the storage formation 119 without at least some deformation, including crushing). A cap 131 can be secured to the housing 129 (e.g., by threading, welding, including spin welding, or otherwise) and define an interior volume 135 that is sized to receive the vitrified waste material 132. As illustrated in this example, the portion of the volume 135 not occupied by the vitrified waste material 132 can be filled with a fluid 137 (e.g., a gas, such as an inert gas, or a liquid, or a mixed-phase fluid). Fluid 137, together with vitrified waste material 132, can provide a means of crush resistance for housing 129 when MLWC 126 is positioned at a depth where hydrostatic pressure at that depth would deform or crush housing 129 (without vitrified waste material 132, fluid 127, or both).

[0062] As illustrated in this implementation, the cap 131 (or housing 129) can include a knob 133 that facilitates coupling to downhole transport equipment (such as wireline, coiled tubing, drill pipe, or other lowering means to be lowered into the borehole 104). For example, a grappler (not shown) can be coupled to the knob 133 (and can be uncoupled from the knob 133 to release the HLWC 126). In other exemplary implementations, a basket can be used to hold the HLWC 126. A rounded lower surface can be added to either the HLWC 126 or the basket to minimize the risk that the canister 126 will be obstructed by irregularities on the inner surface of the casing 120, or on the rock formation if no casing is used.

[0063] As some examples, the diameter of the borehole 104 can be reduced by using the HLWC 126 to store the vitrified waste 132 without using any additional canisters designed to withstand the hydrostatic pressure at the depth of the storage formation 118 without deformation. For example, the diameter D of the HLWC 126 can be about 45 cm or less. In comparison, as shown in FIG. 2, a heavy (i.e., thick-walled) canister 200 designed to withstand the hydrostatic pressure at the depth of the storage formation 118 without deformation can have a diameter D of up to 90 cm. T The reduction in size from the borehole required to receive and contain the heavy canister 200 (at least 90 cm) to the borehole required to receive and contain the HLWC 126 (at least 45 cm) can significantly reduce the cost of drilling the borehole 104. Furthermore, the reduced weight (from the thick canister 200 to the HLWC 126) reduces handling costs incurred in handling on the surface 102. When lowered into a directional, vertical, or inclined borehole (such as the borehole 104), several HLWCs 126 can be attached to each other, reducing the number of run cycles into the borehole 104 required.

[0064] 2 can be placed in the borehole 104, as well as one or more HLWCs 126. For example, as shown, the heavy canister 200 includes a housing 202 onto which a cap 204 is attached (e.g., by threading, welding, or otherwise) and defines an interior volume 206. In the example implementation, one or more (three, as shown in this implementation) HLWCs 126 can be inserted into the volume 206 and then enclosed therein. As described above, the heavy canister 200 can withstand the hydrostatic pressures encountered at the disposal depth (e.g., in the storage formation 118) without or with minimal deformation.

[0065] As an illustrative example, consider the vitrified waste 132 shown in FIG. 2 . A heavy canister 200 holds three HLWCs 126, each with a diameter of about 45 cm or less (e.g., 430 mm or 43 cm). These HLWCs 126 have thin metal walls into which a molten glass / waste combination is poured and then cooled. Prior to installation into the heavy canister 200, the glass / waste combination cools and becomes a glass-like solid referred to as vitrified waste 132. Because such vitrified waste 132 is solid, it is highly resistant to crushing. For that reason, additional canisters (including the heavy canister 200) are not required to prevent the HLWCs 126 from collapsing from hydrostatic pressure as they are lowered into the borehole 104. Thus, while the addition of a heavy canister 200 may provide more protection to the vitrified waste 132, such protection comes at a cost that is disproportionate to (i.e., exceeds) the corresponding added value.

[0066] An additional aspect of the challenge of disposing of vitrified waste 132 by using HLWC 126 enclosed within a heavy canister 200 is the large diameter of the heavy canister 200 shown in Figure 2. The enclosure 202 has a diameter D of 0.8 to 1 meter. TSuch a canister 200 requires a borehole that is substantially larger than the borehole formed to receive and enclose the HLWC 126 so as to contain both the canister 200 and the casing that typically surrounds the canister 200. Thus, a heavy canister 200 can be placed in the borehole 104, thereby emplacement of one or more HLWCs 126, but the HLWCs 126 can be placed in the borehole without the need for a heavy canister 200.

[0067] In some aspects, the HLWC 126 can be used to transport or store the vitrified waste 132, for example, in a conventional waste cask that may be used to store the waste in a labyrinth (i.e., human-accessible) waste repository. For example, Figure 3 shows the vitrified waste 132 as secured within the HLWC 126, which is in turn secured within an outer canister 350, which is in turn secured within a larger outer cask 300 intended for labyrinth (i.e., human-accessible) repository disposal.

[0068] For example, as shown in FIG. 3 , outer cask 300 can include a concrete (or other cementitious) housing 302 with a cap or lid 304 secured to housing 302 and defining an interior volume 306. As is typical, cask 300 is large compared to HLWC 126, e.g., having a height H of about 5.6 to 6.75 meters, and interior volume 306 has a width W of about 1.75 meters. Multiple plugs 308 (e.g., made from bentonite) can be stacked within interior volume 306 and, together with ring 310 (e.g., made from bentonite), can enclose outer canister 350. In FIG. 3 , plugs 308 and ring 310 can provide waste isolation, i.e., they retard the migration of external water or brine to the waste within heavy canister 350.

[0069] As further shown in FIG. 3 , heavy canister 350 includes a housing 351 (e.g., a copper housing) that defines a volume for receiving HLWC 126. Heavy canister 350 has a diameter d of approximately 90 cm in this example (still much larger than the 45 cm of HLWC 126). As shown in FIG. 3 (and cross section “AA”), a cast iron insert 353 can be installed within housing 351 and surround HLWC 126. Cast iron insert 353 is designed to provide protection for workers within the tunnel vault. As will be described, HLWC 126 is the innermost container that holds vitrified waste 132. This “package” (i.e., HLWC 126 within heavy canister 350 within cask 300) can be used to store vitrified waste 132 within the tunnel human-accessible vault.

[0070] In particular, in a tunnel repository, HLWC 126 (which may provide little or no barrier to radiation penetration therethrough) may need to be enclosed within, for example, outer canister 350 and waste cask 300 (one or both of which provide a barrier to radiation penetration therethrough) during and subsequent to placement within the tunnel repository, i.e., during human handling. In contrast, when placing HLWC 126 in a deep, directional (and inaccessible to humans) borehole, such radiation protection may be provided separately at the borehole entry (at the surface), but once inserted into the borehole, such radiation protection is not needed within the borehole. Thus, the lack of a requirement for radiation protection within the borehole may also be an advantage for the emplacement of HLWC 126 (without an outer or heavy canister or cask).

[0071] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features specific to particular implementations of particular inventions. Certain features described herein in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations, either separately or in any suitable subcombination. Also, while features may be described above as operative in a combination and may even be initially claimed as such, one or more features from a claimed combination can, in some cases, be deleted from the combination, and the claimed combination may be directed to subcombinations or variations of subcombinations.

[0072] Several implementations have been described. However, it should be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. For example, the example operations, methods, or processes described herein may include more or fewer steps than those described. Furthermore, the steps in such example operations, methods, or processes may be performed in a different order than described or illustrated in the figures. Accordingly, other implementations are within the scope of the following claims.

Claims

1. 1. A hazardous waste storage facility, comprising: a borehole formed from the earth's surface through one or more subterranean formations, the borehole comprising a reservoir portion formed within at least one of the one or more subterranean formations; a portion of vitrified hazardous waste enclosed within the enclosure of at least one high-level waste canister (HLWC), excluding an outer canister, said HLWC being positioned within said storage portion; Hazardous waste storage facilities, including:

2. 2. The hazardous waste storage facility of claim 1, wherein the housing of the HLWC is insufficient alone to withstand the hydrostatic pressure present in the storage portion without deformation, and the housing of the outer canister is sufficient alone to withstand the hydrostatic pressure present in the storage portion without deformation.

3. 10. The hazardous waste repository of claim 1, wherein the housing of the HLWC is approximately 45 cm in diameter.

4. 10. The hazardous waste repository of claim 1, wherein the vitrified hazardous waste comprises at least one of vitrified nuclear waste, vitrified chemical waste, vitrified biological waste, or crush-resistant waste packaging.

5. The nuclear waste is Cesium-137 or strontium-90 capsules, spent nuclear fuel pellets, vitrified nuclear waste, which comprises nuclear fuel encased in glass; one or more pieces of a melted nuclear reactor core; a calcined waste material comprising granular solids; Pebble Bed Reactor Pellets, or Part of transuranic waste 5. The hazardous waste repository of claim 4, comprising at least one of:

6. The hazardous waste repository of claim 1 , wherein the housing of the HLWC includes mounting members formed on or coupled to ends of the housing.

7. 7. The hazardous waste repository of claim 6, wherein the attachment member comprises a knob.

8. The hazardous waste repository of claim 6 , wherein the attachment member is configured to be attached to an underground transport device.

9. 10. The hazardous waste repository of claim 8, wherein the underground transport equipment comprises one of wireline, slickline, coiled tubing, drill pipe, or an underground tractor.

10. The hazardous waste repository of claim 1 further comprising a casing disposed within the borehole.

11. The hazardous waste repository of claim 1 further comprising a seal positioned within the borehole.

12. 1. A method for storing hazardous waste, comprising: identifying a borehole formed from the earth's surface through one or more subterranean formations, the borehole comprising a reservoir portion formed within at least one of the one or more subterranean formations; moving a portion of the vitrified hazardous waste enclosed within the high-level waste canister (HLWC) enclosure, excluding the outer canister, to a position within said storage portion; A method comprising:

13. 13. The method of claim 12, wherein the housing of the HLWC is insufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation, and the housing of the outer canister is sufficient, alone, to withstand the hydrostatic pressure present in the storage portion without deformation.

14. The method of claim 12 , wherein the housing of the HLWC is approximately 45 cm in diameter.

15. 13. The method of claim 12, wherein the vitrified hazardous waste comprises at least one of vitrified nuclear waste, vitrified chemical waste, vitrified biological waste, or crush-resistant waste packaging.

16. The nuclear waste is Cesium-137 or strontium-90 capsules, spent nuclear fuel pellets, vitrified nuclear waste, which comprises nuclear fuel encased in glass; one or more pieces of a melted nuclear reactor core; a calcined waste material comprising granular solids; Pebble Bed Reactor Pellets, or Part of transuranic waste The method of claim 15 , comprising at least one of:

17. The method of claim 12 , comprising coupling a downhole transport device to a mounting member formed on or coupled to an end of the housing of the HLWC.

18. The method of claim 17 , wherein the attachment member comprises a knob.

19. 18. The method of claim 17, comprising moving the HLWC on the downhole transport device through the wellbore while coupled to the attachment member.

20. 20. The method of claim 19, wherein the downhole transportation device comprises one of wireline, slickline, coiled tubing, drill pipe, or a downhole tractor.

21. The method of claim 12 , wherein the borehole further comprises a casing disposed within the borehole.

22. The method of claim 12 , wherein the borehole further comprises a seal positioned within the borehole.

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