A composition for additive manufacturing with modified photon propagation properties, and a method for additive manufacturing using the same.

Abstract

The present invention provides an additive manufacturing composition comprising a combination of particles having low or no absorption and particles having high absorption. [Solution] A slurry for additive manufacturing, wherein the slurry has a composition comprising, in proportion to the total volume of the slurry, 30% to 40% by volume of a plurality of first particles; 10% to 20% by volume of a plurality of second particles; more than 0% to 5% by volume of a dispersant; more than 0% by volume of a light absorber; more than 0% by volume of a photoinitiator; and 25% to less than 45% by volume of at least one monomer resin, wherein the total amount of the plurality of first particles and the plurality of second particles is a maximum of 60% by volume, the first particles have a composition containing a uranium-containing material, the second particles have an absorbance of more than 0 Au and less than or equal to 1.0 Au at wavelengths of 300 nm to 700 nm, and the light absorber and photoinitiator act at incident wavelengths of 300 nm to 700 nm.

Description

Technical Field

[0001] The present disclosure generally relates to compositions used in additive manufacturing and methods of additive manufacturing. In particular, the additive manufacturing compositions of the present disclosure include a combination of particles having low or non-absorbency and particles having high absorbency. In one aspect, the presence of the low or non-absorbent particles reduces absorption at the curing radiation wavelength, so that the curing radiation increases the penetration depth into the slurry used in the additive manufacturing process. In another aspect, the included low to non-absorbent particles have a lower absorbance than the high absorbent particles (e.g., uranium-containing particles). In yet another aspect, the low / non-absorbent particles are present in the additive manufacturing composition during the additive manufacturing process, e.g., during the printing phase, but they are removed during post-processing of the as-manufactured product, resulting in pores that form porosity in the as-manufactured product. In nuclear reactor applications, the pores and resulting porosity provide a volume for containing fissionable gas and / or enhance the transport of a particular heat pipe coolant, such as by wicking. In a further aspect, the low to non-absorbent particles can be functionalized to enhance properties, e.g., functionalized with a fissionable material to increase ceramic yield; functionalized with burnable poisons, moderators, or stabilizers to increase homogeneity; functionalized with a stabilizer for local transport of the stabilizer; or properties can be improved using combinations of these to combine property enhancements.

[0002] Slurries containing a combination of low-to-non-absorbent particles and highly absorbent particles can be introduced into additive manufacturing protocols for additive manufacturing processes to produce components. Such slurry can be used with appropriate highly absorbent materials, such as fuel assembly structure materials (e.g., Ni, W, Mo, or NW-Mo alloys), moderator materials (e.g., graphite, boron, or carbon-based materials), and nuclear fuel slurry materials (e.g., uranium, or uranium-molybdenum-based materials), to additively produce semi-final or final components, such as components used in the manufacture of nuclear reactors. In the context of nuclear reactor components, the slurry contains 10% to 20% by volume of low-to-non-absorbent particles and 30% to 40% by volume of particles having a composition containing uranium-containing material (e.g., uranium metal, uranium alloy, uranium ceramic, or uranium-molybdenum alloy, etc.). [Background technology]

[0003] The following description refers to specific structures and / or methods. However, the following references should not be construed as acknowledging that these structures and / or methods constitute prior art. The applicant expressly reserves the right to indicate that such structures and / or methods are not relevant prior art to the present invention.

[0004] To create three-dimensional objects, various methods can be used by joining or solidifying materials under computer control, for example, by adding combined materials (such as hardening liquid molecules or fusing powder particles). Various techniques based on melting / deposition or deposition / hardening exist, and these techniques can be used to manufacture objects of almost any shape or geometry using digital model data, such as 3D models, computer-aided design (CAD) models, or digital model data derived from other electronic data sources such as additive manufacturing files (AMF) (usually in continuous layers).

[0005] While many manufacturing methods are available, the main differences between them lie in the method of layering to create the component and the materials used. Some methods melt or soften the material to form layers. Examples include fused filament fabrication (FFF), fused deposition modeling (FDM), fused particle fabrication (FPF), or fused granular fabrication (FGF), which manufacture components by extruding small beads or streams of material that quickly harden and form layers. Other methods involve hardening liquid-based materials using various techniques to construct a manufactured object by solidifying one or more components contained in the liquid material using a layer-by-layer approach. An example is stereolithography, which utilizes various optical or chemical-based methods (using optically or chemically reactive materials). In each example, the manufactured object has properties depending on the manufacturing material.

[0006] In additive manufacturing using optical or chemical curing methods accompanied by a photoinitiation process, radiation penetrates the liquid material and is absorbed by a) the polymer phase, b) the particulate phase and refracted, c) the photoinitiation component, or d) the particulate phase. Absorption by the particulate phase prevents polymerization of the liquid material due to the attenuation of the curing radiation. However, if the particulate phase has high absorption properties (e.g., uranium-containing material) (with respect to the specific radiation used in the process), absorption by the particulate phase increases, while transmission and refraction decrease. This reduces the curing depth, i.e., the thickness of the liquid material that hardens to form a layer. The reduction in curing depth reduces the thickness of each continuous layer laminated by additive manufacturing, thereby reducing efficiency. In some cases, the reduction in curing depth may completely prevent sufficient curing, making deposition from such liquid material compositions using additive manufacturing impossible, for example, meaning "unprintable". While some of the reduction in hardening depth can be mitigated by decreasing the concentration of the particle phase, such a reduction in particle phase concentration negatively impacts the rheology of the liquid material and the post-printing process (i.e., sintering to total density). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent Application No. 16 / 835,370 [Non-patent literature]

[0008] [Non-Patent Document 1] J. Torrent et al., “Diffuse Reflectance Spectroscopy,” in Methods of Soil Analysis Part 5-Mineralogical Methods, Eds. A. Ulery et al., Number 5 in the Soil Science Society of America Book Series, Madison, Wisconsin: Soil Science Society of America, Inc. (2008), pages 367–385. [Overview of the project] [Problems that the invention aims to solve]

[0009] Considering the above, it is desirable to increase the penetration depth of curing radiation, particularly when the liquid material contains components with high absorbance to curing radiation (e.g., uranium-containing materials), to increase the penetration depth of curing radiation in the 300 nm to 700 nm range into the liquid material (also referred to herein as slurry). At the same time, in order to maintain the appropriate rheology of the liquid material used in additive manufacturing, especially stereolithography, it is desirable to minimize, or even avoid, the decrease in the concentration of the particle phase.

[0010] This disclosure generally relates to compositions used in additive manufacturing and methods of additive manufacturing based on deposition / curing techniques. More specifically, this disclosure relates to compositions and methods applicable to deposition / curing additive manufacturing techniques, particularly stereolithography. The slurry composition comprises a high-absorbance component (e.g., uranium-containing particles) and a low- or non-absorbance component (e.g., particles having lower absorbance under the same conditions as the high-absorbance component). In each of the high-absorbance and low- or non-absorbance components, the absorbance relates to the curing radiation used in the additive manufacturing method, for example, curing radiation of 300 nm to 700 nm, or alternatively, 400 nm to 600 nm, 390 nm to 415 nm, 490 nm to 510 nm, or 600 nm to 620 nm, etc.

[0011] Absorbance relates to the amount of light reflected or scattered by a sample, or the amount of light transmitted through a sample. If all light is transmitted through the sample, there is no absorption, so the absorbance is zero and the transmittance is 100%. On the other hand, if no light is transmitted through the sample, the absorbance is infinite and the transmittance is 0%. Absorbance (for example, the absorbance of hardening radiation) is expressed in "absorbance units," which are abbreviated as Au, are dimensionless, and are recorded on a logarithmic scale. Thus, in a logarithmic trend, 0 Au is equal to 0% absorbance (100% transmission), 1.0 Au is equal to 90% absorbance (10% transmission), 2.0 Au is equal to 99% absorbance (1% transmission), and 3.0 Au is equal to 99.9% absorbance (0.1% transmission).

[0012] Where used herein, absorbance (A) was measured by diffuse reflectance spectroscopy using a Shimadzu 2600 / 2700i UV / Vis Spectrometer with an integrating sphere attachment. The spectrometer was used to measure the diffuse reflectance of powder samples. Accurate system initialization and background data acquisition were performed according to the manual. The sample was loaded into a quartz sample container and pressurized to obtain a homogeneous surface. Measurements were performed in diffuse reflectance mode and collected within the range of interest, i.e., 185–1400 nm. The reflection patterns were then evaluated using the Kubelka-Munk transform in the spectrometer's software. Absorbance vs. wavelength was output within the above evaluation range. The above output was used for relative comparison with other target materials to classify the absorbance of the material against that of uranium-containing materials. Further details and aspects of diffuse reflectance spectroscopy are disclosed in J. Torrent et al., “Diffuse Reflectance Spectroscopy,” in Methods of Soil Analysis Part 5-Mineralogical Methods, Eds. A. Ulery et al., Number 5 in the Soil Science Society of America Book Series, Madison, Wisconsin: Soil Science Society of America, Inc. (2008), pp. 367-385, which are fully incorporated herein by reference. This disclosure describes an available laboratory method for recording diffuse reflectance spectra that can be readily applied to first-phase and second-phase powder samples, and this method was used with the liquid materials disclosed herein. Note that no dilution was performed on the samples when diffuse reflectance spectroscopy was performed on the materials disclosed herein.

[0013] Low-absorbance particles allow curing radiation to penetrate deeper into the slurry, giving properties that enable increased curing depth, thicker deposit layers, higher loading of ceramic materials (such as UO2) in the slurry, or a combination of these. Such particles do not react with the slurry material residue, and after curing, the particles can be removed in post-processing by hydrolysis or thermal decomposition.

[0014] As used herein, “non-absorbent particles” have an absorbance equal to 0 Au. As used herein, the absorbance of “low-absorbent particles” to hardening radiation is greater than 0 and lower than the absorbance of uranium-containing particles to hardening radiation. That is, 0Au < (absorbance of low-absorbance particles) < (absorbance of uranium-containing particles) In some embodiments, the absorbance of uranium-containing particles to hardening radiation is 1Au to 3Au, and the absorbance of low-absorbent particles to hardening radiation is 0.001Au or more, and less than or equal to the absorbance of uranium-containing particles to hardening radiation. That is, 0.001Au < (absorbance of low-absorbance particles) < (absorbance of uranium-containing particles) In some embodiments, the low-absorbent particles have an absorbance of less than 1.0 Au to the curing radiation, for example, an absorbance of 0.001 Au or more, or 0.01 Au or more, or 0.1 Au or more, up to 0.7 Au or less, or 0.6 Au or less, or 0.5 Au or less, to the curing radiation. In one particular embodiment, the low-absorbent particles have an absorbance of 0.001 Au or more, or 0.26 Au or less, to the curing radiation.

[0015] As used herein, curing radiation refers to the wavelength of radiation used to cure the resin of a slurry. The wavelength of radiation used to cure the resin of a slurry varies depending on the composition of the slurry. However, in examples of embodiments, the curing radiation has wavelengths of 300 nm to 700 nm, and otherwise has wavelengths of 390 nm to 415 nm, or 490 nm to 510 nm, or 600 nm to 620 nm. In certain examples, the curing radiation has wavelengths of 405 nm, or 500 nm, or 618 nm.

[0016] Due to its continuous, layer-by-layer manufacturing method, the additive manufacturing method of this disclosure is suitable for the manufacture of complex components. In the context of reactor components, examples of complex components include fuel assemblies (e.g., the arrangement of fuel elements (including fuel and flammable toxins), mechanical support for the fuel assembly structure, spacer grids (which maintain the spacing between components and guide the fuel elements), and non-fuel tubes such as control rods or core instrumentation) (also known as fuel bundles). Structural complexity also extends to other systems within the reactor, such as systems containing various components of the primary cycle (meaning systems exposed to, in contact with, or otherwise exposed to primary coolant), depending on the design, tubing, pumps, instrumentation, heat exchangers, and steam generators.

[0017] The use of the additive manufacturing methods of this disclosure has been found to be advantageous in the manufacture of these complex structures, particularly fuel elements and fuel assemblies, improving both the manufacturing method itself and the complex structures manufactured (including quality assurance of such structures). The use of the additive manufacturing methods of this disclosure in combination with the compositions of this disclosure has been found to be highly advantageous for these purposes.

[0018] The embodiments disclosed herein include a method for additive manufacturing of components, particularly components of a nuclear fission reactor, during both additive manufacturing method development and prototype development, as well as during final manufacturing of in-service components, and the composition of a slurry used in such additive manufacturing of components.

[0019] Embodiments of a method for manufacturing components of a reactor system include the use of a slurry containing low to non-absorbent particles in an additive manufacturing protocol and the manufacture of a green body of a component of a reactor system using the slurry in an additive manufacturing protocol of an additive manufacturing method.

[0020] Embodiments of a slurry for additive manufacturing include a composition that includes, based on the total volume of the powder, 30% to 40% by volume of a plurality of first particles; 10% to 20% by volume of a plurality of second particles; greater than 0% to 5% by volume of a dispersant; greater than 0% of a light absorber; greater than 0% of a photoinitiator; and 25% to less than 45% by volume of one or more monomer resin compositions. Here, the total amount of the first particles and the second particles is at most 60% by volume. The first particles include a composition containing a uranium-containing material. The second particles have an absorbance of less than 0 Au to 1.0 Au at a wavelength of 300 nm to 700 nm, and separately, an absorbance of 0.001 Au or 0.01 Au or 0.1 Au or more to 0.7 Au or 0.6 Au or 0.5 Au. The light absorber and the photoinitiator act at an incident wavelength of 300 nm to 700 nm.

[0021] Embodiments of a method for manufacturing components of a nuclear reactor system include manufacturing a green body of a component of the nuclear reactor system using an additive manufacturing protocol that uses a nuclear fuel slurry. Here, the nuclear fuel slurry includes a composition that includes, based on the total volume of the slurry, from 30% to 40% by volume of a plurality of first particles; from 10% to 20% by volume of a plurality of second particles; greater than 0% to 5% by volume of a dispersant; greater than 0% of a light absorber; greater than 0% of a photoinitiator; and from 25% to less than 45% by volume of one or more monomer resin compositions. Here, the total amount of the first particles and the second particles is at most 60% by volume. The first particles include a composition that includes a uranium-containing material. The second particles have an absorbance of less than 0 Au to 1.0 Au at a wavelength of 300 nm to 700 nm, and separately, have an absorbance of 0.001 Au or 0.01 Au or 0.1 Au or more to 0.7 Au or 0.6 Au or 0.5 Au. The light absorber and the photoinitiator act at an incident wavelength of 300 nm to 700 nm.

[0022] In some embodiments of the slurry and method, the uranium-containing material is uranium metal, a uranium alloy, a uranium ceramic, a uranium-molybdenum alloy, or a mixture thereof. In some embodiments, the uranium-containing material is uranium oxide, uranium dioxide, uranium carbide, uranium oxycarbide, uranium nitride, uranium silicide, uranium fluoride, uranium chloride, a cermet of uranium oxide and tungsten, a cermet of uranium dioxide and tungsten, a cermet of uranium oxide and molybdenum, a cermet of uranium dioxide and molybdenum, or a mixture thereof. However, other uranium-containing materials can also be used, including those containing inorganic species and those containing organic ligand / anion species.

[0023] In one particular embodiment, the nuclear fuel slurry for additive manufacturing comprises a composition comprising: 30% to 45% by volume of an acrylic acid-based monomer resin; 30% to 40% by volume of a composition comprising a uranium-containing material; 10% to 20% by volume of a composition having an absorbance of 0 Au to less than 1.0 Au at wavelengths of 300 nm to 700 nm, and separately having an absorbance of 0.001 Au, 0.01 Au, 0.1 Au to 0.7 Au, 0.6 Au, or 0.5 Au; more than 0% to 7% by volume of a dispersant suitable for dispersing particles in the nuclear fuel slurry; and more than 0% by volume of a photoactivated dye for subsequent activation during quality control inspection. The dye comprises a light absorber greater than 0% by volume that reduces crosslinking by stopping free radical polymerization of the slurry, a photoinitiator greater than 0% by volume that is selected to match the wavelength of radiation that may be used to cure the slurry composition, or vice versa, and methylnaphthalene in an amount of 0% to 18% by volume as a diluent.

[0024] Additive manufacturing protocols, such as those for stereolithography, can be developed using surrogate slurry modified to introduce low absorption cross-section particles (disclosed in U.S. Patent Application No. 16 / 835,370, filed March 31, 2020, the contents of which are fully incorporated herein by reference).

[0025] Despite the reactor and core of this disclosure including components with complex mechanical geometries, the integral and iterative fabrication of the fissile fuel material facilitates the fabrication of the components. [Brief explanation of the drawing]

[0026] The above overview and the following detailed descriptions of embodiments can be better understood by reading them in conjunction with the attached drawings. It should be understood that the embodiments described are not strictly limited to the arrangements and fixtures shown.

[0027] [Figure 1] Figure 1 schematically illustrates these various processes that occur when hardening radiation interacts with a slurry consisting of multiple non- / low-absorbing particles. [Figure 2] Figure 2 schematically shows the transmission of curing radiation into a slurry containing a uranium dioxide particle phase within the monomer phase. [Figure 3] Figure 3 schematically shows an embodiment that increases the penetration depth of curing radiation and the printable depth of the slurry by reducing the loading of the particle phase in the slurry. [Figure 4] Figure 4 schematically illustrates an embodiment in which the penetration depth of curing radiation and the printable depth of the slurry are increased by adding a second particle phase having low (or near-zero, or zero) absorbance. [Figure 5] [Figure 6] Figures 5 and 6 show examples of manufactured green bodies produced in accordance with the slurry compositions and addition processes disclosed herein. [Figure 7] Figure 7 is a graph showing the curing depth (μm) for the sample of the example as a function of the ratio of (low absorbance second particle phase):(first particle phase).

[0028] Detailed explanation Generally, slurries for additive manufacturing based on deposition / curing techniques include a monomer phase (typically containing one or more monomer resins), a particulate phase (typically containing ceramic material), a dispersant (to promote the dispersion of the particulate phase within the polymer phase), a photoinitiator (which interacts with curing radiation to initiate radical polymerization of the monomer phase), and a photoabsorbent (which absorbs incident radiation within a specific wavelength, stopping or reducing free radical polymerization of the slurry at that wavelength, thereby reducing crosslinking). In additive manufacturing based on deposition / curing techniques, when curing radiation interacts with a slurry, the curing radiation may (i) penetrate the monomer phase of the slurry, (ii) penetrate and refract through the particulate phase of the slurry, (iii) be absorbed by the photoinitiator or photoabsorbent in the slurry, or (iv) be absorbed by the particulate phase within the slurry. Figure 1 schematically illustrates these various processes that occur when curing radiation interacts with a slurry. Figure 1 shows the volume of slurry 100, which is a solution containing monomer phase 102 and particulate phase 104. In Figure 1, the particles in the particle phase have absorbances of 0 Au to less than 1.0 Au in response to incident curing radiation, and otherwise have absorbances of 0.001 Au, 0.01 Au, 0.1 Au to 0.7 Au, 0.6 Au, or 0.5 Au. The particles in the particle phase include, for example, cerium oxide (CeO2), but other particles, such as zirconium dioxide (ZrO2), beryllium oxide (BeO), and polyamides, may also be used or included in the particle phase. Dispersants, photoinitiators, and photoabsorbers are dissolved or mixed in the monomer phase 102, but are not shown in Figure 1. Curing radiation 110 (radiation with a wavelength range of 300 nm to 700 nm, or ultraviolet (UV) radiation; in certain examples, curing radiation of 405 nm, 500 nm, or 618 nm, etc.) is incident on the slurry 100, and several different phenomena may occur. For example, the first portion 120 of the hardening radiation 110 penetrates the monomer phase 102 and the slurry 100. Also, for example, the second portion 122 of the hardening radiation 110 penetrates the particle phase 104 of the slurry 100 and is refracted by the particle phase 104. Refraction occurs when the incident radiation interacts with the particles of the particle phase 104, changing its direction and / or wavelength.A further example is a third portion 124 of the hardening radiation 110, which is absorbed by the particle phase 104 present in the slurry 100. In some cases, a combination of these effects may occur, in which case the hardening radiation 110 may be transmitted and refracted one or more times (for each phenomenon) before being absorbed by the monomer phase 102. An example of hardening radiation 110 incident on slurry 100, and multiple transmissions and / or refractions occurring, is shown in Figure 1 (see, for example, incident radiation 126). A fourth portion of the hardening radiation 110 is absorbed by the photoinitiator or photoabsorber in slurry 100 (not shown in Figure 1).

[0029] In addition processes, a sufficient amount of curing radiation must penetrate the volume of the slurry 100 and be absorbed by the monomer phase 102 in the slurry 100 (either before or after refraction) in order to initiate a sufficient polymerization reaction and form interconnected solid articles. Thus, while the curing radiation 100 can penetrate the slurry to a depth D2, the depth D1 to which sufficient curing radiation 110 penetrates the slurry 100, initiates a sufficient polymerization reaction in the monomer phase 102, and forms interconnected solid articles is smaller than the depth D2. This difference is mainly due to the reduction in available curing radiation 110 as a result of absorption events, such as the third portion 124 of the curing radiation 110 absorbed by the particle phase 104 present in the slurry 100. Therefore, in Figure 1, depth D2 may be the penetration depth at which 90% of the curing radiation 110 disappears, while depth D1 represents the printable depth and the depth at which sufficient curing radiation 110 penetrates the slurry 100, initiating a sufficient polymerization reaction in the monomer phase 102 and forming interconnected solid articles. In one example, a slurry containing 4 μm diameter CeO2 particles and 405 nm incident curing radiation had a printable depth of approximately 30 μm.

[0030] At a given particle phase loading (also called concentration) in the slurry, the transmission depth D2 and printable depth D1 vary depending on the particle phase having a higher or lower absorbance value for a particular wavelength. For example, uranium dioxide (UO2) exhibits over 99% absorption at 405 nm. Therefore, a slurry containing a particle phase consisting of UO2 or a UO2 compound essentially annihilates all photons from the hardening radiation interacting with the particle phase, and refraction and transmission of less than 1% of the hardening radiation through UO2 is observed. Figure 2 schematically shows the transmission of hardening radiation into a slurry 200 containing a uranium dioxide particle phase 204 in a monomer phase 202. The incident hardening radiation 210 penetrates the monomer phase 202 of the slurry 200. Due to the absorption characteristics of uranium oxide such as UO2 at a wavelength of 405 nm (1.0Au to 3.0Au), as soon as interaction occurs between the hardening radiation 210 and the uranium dioxide particle phase 204, more than 90%, or even more than 99.9%, of the incident hardening radiation 210 is absorbed, and the refraction and / or transmission of the incident hardening radiation 210 is minimal (less than 1%). Consequently, the transmission of the incident hardening radiation 210 into the slurry 200 is limited to the path length where interaction with the particle phase 204 does not occur, and in effect, the transmission depth D2 and the printable depth D1 are almost the same (±3% to 5%).

[0031] Considering the above findings, we determined that in order to increase the transmission of hardening radiation into the slurry, it is necessary to increase the path length in which interaction of highly absorbent particles such as uranium dioxide does not occur.

[0032] In the first embodiment, embodiments of a slurry composition and embodiments of a manufacturing method using such a slurry composition increase the transmission depth D2 and printable depth D1 by reducing the loading of a particle phase having high absorbance. Reducing the loading of a particle phase such as uranium dioxide increases the spacing between particle phases. In these embodiments, it was found that a slurry containing 50 volume% of a particle phase consisting of uranium oxide has a transmission depth D2 of approximately 9 μm at 405 nm curing radiation, and a slurry containing 25 volume% of a particle phase consisting of uranium oxide has a transmission depth D2 of approximately 20 μm at 405 nm curing radiation. Generally, in particle phases consisting of 25 volume% to 50 volume% of uranium oxide, the light transmission depth D2 (μm) changed as a function of the volume% of the particle phase consisting of uranium oxide. For example, the following formula: I=I0e -αz This is the relationship between the intensity (I) of transmitted light at a given depth (z) as a function of the incident intensity (I0) and the attenuation coefficient α, where the light transmission depth D2 (μm) changed linearly with respect to the logarithm of the intensity (I), or changed logarithmically with respect to the intensity (I). Furthermore, it was found that reducing the loading of the particle phase forming a stable colloidal dispersion had a homogeneous effect on the entire slurry.

[0033] Figure 3 schematically illustrates an embodiment in which the penetration depth D2 and printable depth D1 of the slurry are increased by reducing the loading of the high-absorbent particle phase in the slurry. Figure 3 schematically illustrates the transmission of curing radiation 310 into a slurry 300 containing a uranium dioxide particle phase 304 in a monomer phase 302. Here, the volume loading of the high-absorbent particle phase 304 is approximately one-third of the volume loading depicted in Figure 2. In the following Mie theory, the absorption decay coefficient is directly proportional to the volume loading. Therefore, since the volume loading is lower in Figure 3 than in Figure 2, the light transmission depth D2 is higher compared to Figure 2. Furthermore, the curing depth also increases as a result, so the printable depth D1 is higher compared to the case where the volume loading is higher, as in Figure 2.

[0034] Reducing the volume loading of the high-absorbent particle phase may increase the curing depth and printable depth, but it has unfavorable effects on achieving the desired microstructure product in the sintering process. Thus, while reducing volume loading increases the feasibility of green body additive manufacturing, it also has unfavorable effects on post-process strengthening, for example, in areas where there is insufficient densification due to interconnected porosity resulting in a theoretical density (TD) of less than 65%, and / or in areas where significant shrinkage is observed, for example, in the form of stress cracking due to strain during shrinkage.

[0035] In a second embodiment, embodiments of a slurry composition and embodiments of a manufacturing method using such slurry composition increase the penetration depth D2 and printable depth D1 by adding a low-absorbent second particle phase (e.g., a low-absorbent particle phase having an absorbance close to or equal to 0Au). The second particle phase is dispersed in the first particle phase, i.e., the high-absorbent particle phase, and increases the spacing between particles of the first particle phase. At least a portion of this spacing is occupied by particles of the low-absorbent second particle phase (e.g., a low-absorbent particle phase having an absorbance close to or equal to 0Au), providing a transmission path for the incident curing radiation. Consequently, the particles of the second particle phase act as a transmittance window species for the incident curing radiation, allowing further transmission into the slurry. In non-limiting examples, the second particle phase may include, or otherwise consist of, organic particles that transmit curing radiation in the wavelength range of 300 nm to 700 nm. Suitable organic particles in the second particle phase include polyamides, polyactides (PLA), polyethylene glycol (PEG), and combinations thereof. The appropriate concentration of particles in the second particle phase (e.g., a low-absorbent particle phase with absorbance close to or equal to 0 Au) is approximately 5–25 volume%, otherwise 10–15 volume%, depending on the morphology and size of the low or non-absorbent particles. Furthermore, the upper limit of the concentration range is generally a balance between the increase in penetration depth of the curing radiation and the resulting increase in porosity within the product during manufacturing. On the other hand, the lower limit of the concentration range is governed by minimizing any effect on the penetration depth—in other words, concentrations that are too low have virtually no effect on the penetration depth. In these embodiments, a slurry containing (i) a 40 volume% high-absorbent particle phase consisting of uranium oxide with a particle size of 4 μm as the first particle phase, and (ii) a low / non-absorbent particle phase consisting of polyamide with a particle size of 9 μm as the second particle phase, had a penetration depth D2 of approximately 12 μm against 405 nm curing radiation. For comparison, a slurry containing only one particle phase consisting of 40 volume% uranium oxide with a particle size of 4 μm had a penetration depth D2 of approximately 5 μm against 405 nm curing radiation.

[0036] The particle size in the second particle phase results in an increase in penetration depth D2 and printable depth D1, even in slurry compositions that are otherwise unprintable, i.e., slurry compositions that have a printable depth of less than 9 μm under baseline conditions. This effect is additive. For example, even if the slurry composition of the first particle phase can only cure to a depth of 6 μm when used on its own without adding any low / non-absorbent particles, adding a second particle phase of low / non-absorbent particles with a particle size of 7 μm results in a penetration window through which curing radiation penetrates the slurry to a depth of 13 μm, i.e., [(curing depth of the first particle phase) + (particle size (diameter) of the second particle phase)]. This is a sufficiently thick, printable area. While theoretically perfectly additive, some losses are likely to reduce the penetration depth of curing radiation to less than the sum of [(curing depth of the first particle phase) + (particle size (diameter) of the second particle phase)].

[0037] When used herein, the baseline condition is a penetration depth of 1.5 times the printable depth. For example, when printing a 10 μm layer, the baseline condition is a penetration depth of 15 μm. When printing a 30 μm layer, the baseline condition is a penetration depth of 45 μm. To achieve 1.5 times the printable depth without using transparent particles, the volume% loading of the ceramic layer can be reduced and / or the average particle size can be increased. In one embodiment, this can be achieved by removing fine particles (such particles having a diameter of less than 2 μm). As an example, using ZrO2 with milled particles at 55 volume% loading or nanoparticles at 40 volume% loading, (i) a curing depth of 30–50 μm and (ii) a printable depth of 20–30 μm were observed under curing radiation at 405 nm. In TiO2, using a 50 vol% loading and 405 nm curing radiation, (i) a curing depth of 21 μm and (ii) a print depth of 10–15 μm were observed. In black zirconia, using a 45 vol% loading and 445 nm curing radiation, (i) a curing depth of 16 μm and (ii) a print depth of 10 μm were observed. In these examples, the monomer mixture and doctor blade thickness were identical, and the exposure conditions were 95% of maximum force for 15 seconds. The baseline conditions were slightly overexposed to promote layer adhesion.

[0038] The results of the examples suggest that the transmission depth D2 can be increased by the inclusion of low-absorbance particles in the second particle phase. Furthermore, the increase in transmission depth D2 is related to the following: Penetration depth (D2) = [(hardening depth of the first particle phase) + (particle size (diameter) of the second particle phase)] Based on this, it is expected that in some embodiments, the penetration depth may be twice or three times the hardening depth of the first particle phase. Although logically additive, some losses are expected to reduce the observed penetration depth to less than the theoretical penetration depth.

[0039] Figure 4 schematically illustrates an embodiment in which the penetration depth D2 and printable depth D1 of the slurry are increased by the addition of a second particle phase having low absorbance (e.g., a low-absorbance particle phase having an absorbance close to or equal to 0 Au). The embodiment in Figure 4 shows the transmission of curing radiation into a slurry 400 containing a first particle phase 404 of uranium dioxide and a second particle phase 406 of an organic polymer (which has an absorbance close to 0 for a wavelength of 405 nm) in a monomer phase 402. The incident curing radiation 410 penetrates the monomer phase 402 of the slurry 400. The incident curing radiation 410 can interact with the monomer phase 402 or with either the first particle phase 404 of uranium dioxide or the second particle phase 406 of the organic polymer. When incident hardening radiation 410 interacts with the first particle phase 404 of uranium dioxide, more than 99% of the incident hardening radiation 410 is absorbed, as explained with reference to Figure 2, and the refraction and / or transmission of the incident radiation 410 is minimal (less than 1%). However, when incident hardening radiation 410 interacts with the second particle phase 406 of an organic polymer, the hardening radiation 410 is transmitted through the second particle phase 406. In some cases, the hardening radiation 410 may be refracted by the second particle phase 406. In other examples, when a combination of these effects occurs, the hardening radiation 410 may be transmitted and refracted multiple times before being absorbed by the monomer phase 402 or the second particle phase 406 (in each phenomenon). Examples of hardening radiation 410 that is incident on slurry 400 and absorbed by the first particle phase 404 of uranium dioxide, or transmitted and / or refracted one or more times, and / or a combination thereof, are shown in Figure 4 (see, for example, incident hardening radiation 420 absorbed by the first particle phase 404 of uranium dioxide, incident hardening radiation 422 that penetrates the monomer phase 402 and the second particle phase 406 to a penetration depth D2, and incident hardening radiation 424 that penetrates the monomer phase 402 and the second particle phase 406 and is absorbed by the first particle phase 404 of uranium dioxide).

[0040] The effect of the transmissive window in the second embodiment described above can make resins that are themselves unprintable under baseline conditions printable. This technique substantially isolates the unfavorable effects of particle light interactions on printability and allows any material to be repeatedly manufactured to a green body state (in additive manufacturing) using a 10 μm layer.

[0041] Ultimately, it should be noted that the addition of a second particle phase has a less significant effect on homogeneity than it does on reducing particle phase loading.

[0042] The technologies and approaches in the first and second embodiments can be implemented individually or in combination.

[0043] As previously stated herein, the inclusion of a second particle phase with low (or near-zero, or zero) absorbance in a liquid material has rheological aspects. The addition of a secondary low-molar extinction coefficient phase results in a change in formulation rheology. According to the Kreiger-Dougherty equation, viscosity increases as the particle volume increases (as in the case of adding transparent particles). Furthermore, shear thinning behavior is hardly observed, and the onset of shear thickening (defined by critical shear stress) decreases to low shear rates. As loading increases and the spacing between particles decreases, the onset of shear thickening at low stresses is observed. When shear-induced flow is used in the production of thin films cast on tape, and in the removal of excess resin and bubbles when zeroing out the build plate to produce a new layer, the critical shear stress needs to be higher than the shear stress observed during the additive process to prevent build defects during additive manufacturing, for example, during printing. It should be noted that in some embodiments, viscosity is dynamic, starting very high as zero shear viscosity and decreasing to what is called the Newtonian plateau as the solution is sheared. Furthermore, the appropriate viscosity can be quantitatively assessed by a doctor blade, which provides insight into whether the shearing phenomenon is appropriate, based on the resin's ability to be processed into a continuous thin film.

[0044] The generalized effects on critical shear stress considered when reaching the processing parameters are as follows: As the volume loading (Φ) of the particles decreases, the critical shear stress increases; • As the particle radius (a) decreases, the critical shear stress increases (α -(2~3) Like that); • Theoretical maximum packing factor (Φ m As ) increases, the critical shear stress increases; • As the particle size distribution widens while Φ remains constant, the critical shear stress increases. As particle anisotropy and roughness decrease, the critical shear stress increases; • When the viscosity of the fluid layer decreases, the critical shear stress increases; • As repulsive forces (three-dimensional and electrostatic) increase, critical shear stress increases; and • As the compatibility between the stereodispersant and the solvent increases, the critical shear stress increases. Includes.

[0045] In a specific embodiment, a liquid material containing SR494 as a monomer and 4 μm diameter uranium dioxide particles at a concentration of 40% had a process viscosity of 10,000 cP and exhibited a curing depth of 9 μm. When 9 μm polyamide particles were used as a second particle phase with low (or near-zero, or zero) absorbance and added to the liquid material in this example up to a concentration of 15%, the viscosity of the liquid material increased, and the curing depth reached 18 μm.

[0046] The use of polyamide or PEG as the second particle phase provides beneficial secondary effects during post-processing. Such particles are present during the curing of the liquid material and are thereby incorporated into the body of the structure formed by the addition method using the liquid material; however, these particles can subsequently be removed from the green body prior to densification. Depending on the composition of the second particle phase, appropriate removal treatments may be applied prior to densification. For example, polyamide particles can be removed from the body by thermal decomposition. This thermal decomposition occurs at a temperature lower than the temperature at which densification of the polymer network occurs, for example, at least 20°C, otherwise about 100°C to 200°C lower, forming a residual network of interconnected microporosity. In other examples, PEG particles can be dissolved by hydrolysis and removed from the body before densification. This also forms a residual network of interconnected microporosity.

[0047] Other techniques can also be appropriately used to remove the second particle phase from the green body before densification. These include sonication and the use of solvents that are selective for the second particle phase without affecting the green body material. Furthermore, combinations of these techniques can also be used. For example, a combination of thermal decomposition and hydrolysis, or a combination of hydrolysis and sonication. In each example, whether used individually or in combination, the layer-by-layer network of microporosity provides a pathway for gases formed in the subsequent densification process to escape from the body, limiting the risk of cracking due to pressure on the body caused by the build-up of such gases.

[0048] Furthermore, interconnected microporosity networks offer secondary advantages during nuclear operations. In particular, interconnected microporosity networks formed during pre-densification are protected by the densification process and may persist in the final product. In the final product, these interconnected microporosity networks provide volume for accommodating fission gases generated during nuclear operations. The homogeneous dispersion of the second particle phase, which occurs during the liquid phase formation of the body during additive manufacturing, is reflected in the homogeneous dispersion of microporosity in the final product. Changing the size of the organic particles used in the second particle phase is another mechanism that can be used to influence the size of microporosity.

[0049] In one embodiment, the particles of the second particle phase are resin particles formed from a polymer derived from ceramic uranium bearing resin, which provide an additional stoichiometric amount of uranium to increase viscosity, transmit light, assist in debindering, and increase the yield of ceramics in reactor applications.

[0050] In another embodiment, the particles of the second particle phase are polymer materials doped with cerium, yttrium, gadolinium, or other stabilizers. In one embodiment, this embodiment enables the systematic dispersion of these stabilizers in fuel form without directly loading the stabilizers as powders into the ceramic slurry. Conventionally, the direct loading of stabilizers in a powder phase used in ceramic slurries often required considerable mixing of the powders to ensure homogeneity of dispersion. However, loading the same stabilizers as dopants into polymer particles of the second particle phase facilitates ensuring uniform dispersion of the stabilizers without requiring such mixing efforts.

[0051] Other embodiments of this model are applicable to nuclear energy propulsion (NTP) applications. For example, a stabilizer is loaded into resin particles and deposited in pores created in a body (such as a fuel element structure) manufactured by additive manufacturing. Iron is an example of a stabilizer that can be used in this method. In a highly reducing environment, oxygen begins to separate from UO2 at temperatures of 2200K (or above), forming uranium metal. Under these conditions, the uranium metal migrates to a location within a network of interconnected microporosities formed by the second particle phase. The iron (or other stabilizer) loaded into the resin particles exists as a residue within this network of interconnected microporosities (after the second particle phase has been removed from the green body, as discussed above). When the uranium metal interacts with the iron in the pores, the iron forms a eutectic with the uranium metal. This iron-uranium eutectic is resistant to the formation of hydrogen compounds during the cooldown of the reactor. However, if some uranium metals are not alloyed with iron, the volume of the interconnected microporosity network provides a volume that can form uranium hydride (UH3) without causing cracking throughout the UO2 fuel element. Since this volume expansion for uranium hydride formation is a major failure mode for UO2NTP fuel elements, increasing the volume that reduces crack formation can improve the NTP fuel element's resistance to this failure mode.

[0052] The polymer particles of the second particle phase can be used not only to introduce a secondary phase useful as a stabilizer, but more broadly, polymer particles can be used as carriers for anything that can be trapped or doped into a transparent organic phase. In this way, polymer particles can serve as a vehicle for introducing various materials into the green body and subsequently into the manufactured product.

[0053] Furthermore, interconnected, adjustable microporous networks can be used for capillary flow of liquid phase coolants in the design of heat pipe reactors and liquid material cermet reactors. Microporosity enhances wicking of certain heat pipe coolants, such as water, NaK, and liquid silver, to the fuel elements. Typical pore sizes range from 20 to 500 μm.

[0054] Examples of slurries (e.g., nuclear fuel slurries) in additive manufacturing include compositions comprising monomer resin, uranium-containing particles, low / non-absorbent particles (in the curing radiation used in additive manufacturing), dispersants, light absorbers, photoinitiators, and optionally one or both of a diluent and a photoactivating dye.

[0055] The slurry (e.g., nuclear fuel slurry) contains monomer resin present in an amount of 25% to less than 45% by volume, otherwise 25% to less than 35% by volume, otherwise 25% to 30% by volume. In certain embodiments, the monomer resin is an acrylic acid-based monomer resin, a methacrylic acid-based monomer resin, or a mixture thereof. In some embodiments, the monomer resin is at least 50% acrylic acid-based, otherwise 70-90% acrylic acid-based. In other embodiments, the acrylic acid-based monomer resin is functionalized, for example, monofunctional, difunctional, trifunctional, tetrafunctional, or a mixture thereof. The acrylic acid-based monomer resin may be at least 50% difunctional, otherwise at least 80% difunctional, otherwise 70-90% difunctional. One specific embodiment of a suitable acrylic acid-based monomer resin is hexane-diol diacrylate (available from Sartomer (Arkema Group) under the brand name SR238). Another example of a suitable acrylic acid-based monomer resin is ethoxylated (4) pentaerythritol tetraacrylate (available from Sartomer (Arkema Group) under the brand name SR494). Alternatively, oligomer-based resins may be used as alternatives to acrylic acid-based monomer resins. The use of oligomer-based resins may result in improvements in shrinkage control, polymerization rate, and viscosity compared to monomer resins.

[0056] The slurry (e.g., nuclear fuel slurry) contains particles of uranium-containing material present in amounts of 30% to 40% by volume, otherwise 32% or 34% or 36% to 38% or 40% by volume. Examples of uranium-containing materials include uranium metal, uranium alloy, uranium ceramic, and uranium-molybdenum alloy. In some embodiments, uranium-containing materials represented by surrogate particles include uranium oxide, uranium dioxide, uranium carbide, uranium oxycarbide, uranium nitride, uranium silicide, uranium fluoride, uranium chloride, uranium oxide and tungsten cermet, uranium dioxide and tungsten cermet, uranium oxide and molybdenum cermet, or uranium dioxide and molybdenum cermet. In other embodiments, the uranium-containing material can be represented by the chemical formula U(C,O,N,Si,F,Cl), and one or more of the following elements may exist together with uranium, either stoichiometrically or nonstoichiometrically: carbon (C), oxygen (O), nitrogen (N), silicon (Si), fluorine (F), chlorine (Cl), or any combination thereof.

[0057] Other non-limiting examples of uranium-containing materials include non-linear species such as U(OH,B,Sb,P,As,S,Se,Te,Cl,Br,I); uranium hydroxides and hydrides; uranium bromide; uranium iodide; uranium selenide; uranium telluride; uranium chloride; uranium sulfide; uranium boride; uranium phosphide; uranium arsenide; and uranium antimonide. Organic ligand / anionic species can also be used as uranium-containing materials. However, as the size of these polyatomic ions increases, the concentration of uranium mass decreases, creating an undesirable upper limit for fabrication into structures for nuclear fuel-related applications. Non-limiting examples of uranium-containing materials include organic ligands / anionic species such as ammonium urinates, uranium carbonyl, uranyl nitrate, uranyl oxalate, uranyl peroxide, uranyl acetate, uranyl benzoate, uranyl tannate, and uranyl quinolinate.

[0058] Furthermore, uranium-containing materials can be produced additively in certain forms and subsequently converted into other forms of uranium (e.g., by oxidation, reduction, carburization, and nitriding after the sintering process). For example, uranium derived from uranium-containing materials formed during additive manufacturing can be converted into uranium oxide through an oxidation process.

[0059] The slurry (e.g., nuclear fuel slurry) contains a dispersant present in amounts greater than 0% to 7% by volume, otherwise 1% to 5% by volume, or otherwise 4% to 6% by volume. The specific dispersant is selected for its ability to disperse in the slurry composition and in particles of the uranium-containing material. The amount of dispersant should be sufficient to produce a well-dispersed, not thixotropic, shear-thinning non-Newtonian fluid that is at least sufficient to completely coat the particles. In one example, the slurry has a viscosity of 100,000 centipoise (cP) or less, otherwise 10,000 cP or less. Excessively high zero-shear viscosity or insufficient shear-thinning behavior (thixotropic, or shear-thinning) hinders continuous, defect-free production.

[0060] In certain embodiments, the dispersant may be a composition containing quaternary ammonium chloride, such as VARIQUAT® CC-9 or VARIQUAT® CC-42 (both available from Evonik Industries AG in Germany), or a high molecular weight polymer dispersant, such as TEGO® Dispers 660C or TEGO® Dispers 670 (both available from Evonik Industries AG in Germany). In a further specific example, two different dispersants, or a mixture of dispersants, may be used. For example, the dispersant of the first composition and the dispersant of the second composition may be mixed in a ratio of the first component to the second component (first component:second component) in the range of 2 to 2.5, or otherwise in the range of 2.15 to 2.35.

[0061] Light absorbers absorb incident radiation within a specific wavelength, stopping or reducing free radical polymerization of the slurry occurring at this wavelength, thereby reducing crosslinking. In certain examples, the light absorber is a triazine-based light absorber, preferably a 2-hydroxyphenyl-s-triazine containing 18-20% 2-methoxy-1-propyl-acetate (e.g., Tinuven® 477 (available from BASF), which is a liquid triazine-based light absorber based on a redshifted triresorcinol triazine chromophore exhibiting high thermal stability, excellent photopermanence, and minimal interaction with metal catalysts and amine crosslinkers).

[0062] The photoinitiator is selected to be compatible with the incident radiation (i.e., curing radiation) used to cure the slurry composition, and vice versa. In certain examples, the photoinitiator is a type I or type II photoinitiator, preferably bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, such as OmniRad 819 (formerly Irgacure 819), available from IGM Resins in the United States. This is a photoinitiator for radical polymerization in which unsaturated resins are exposed to curing radiation.

[0063] Slurries (e.g., nuclear fuel slurries) optionally contain diluents. Diluents are typically used for their effect on the monomer phase and are added or applied for their effect on the as-manufactured part in the debindering process. For example, if the diluent is driven off during debindering, small voids remain in the as-manufactured part, and in reactor components, these small voids result in gas discharge volume, which contributes to minimizing or preventing cracking of the component. When diluents are used, they are present in amounts of 4% to 40% by volume, otherwise 4% to 20% by volume, otherwise 4% to 6% by volume, otherwise 8% to 40% by volume, or 10% to 30% by volume, otherwise 8% to 20% by volume, or 8% to 15% by volume. A suitable diluent is liquid at room temperature and has a sufficiently low boiling point so that the diluent can be driven off at temperatures below 400°C, otherwise below 300°C. In certain examples, the diluent is methylnaphthalene.

[0064] The slurry (e.g., nuclear fuel slurry) optionally contains a photoactivating dye. If a photoactivating dye is present, it is present in an amount greater than 0% by volume, otherwise in an amount of 0.05% to 0.10% by volume. The photoactivating dye makes the cured layer visible by changing the color of the cured layer during curing. Such visualization is detectable under specific wavelengths, for example, UV light, and can be used for fault detection or other inspection purposes. In certain embodiments, the photoactivating dye is a triarylmethane dye, preferably C 25 H 30 CIN3 (available under the brand name Crystal Violet from Sigma-Aldrich, USA). Crystal Violet is a blue, aniline-derived dye. In other specific examples, the photoactivating dye is present in an amount of 0.002 mol / liter of monomer resin.

[0065] In certain embodiments, the light absorber, photoinitiator, and photoactivating dye (if used) are selected to be effective with respect to the photosource. For example, the light absorber, photoinitiator, and photoactivating dye are selected to be effective in the range of 300–700 nm, or alternatively, 400–620 nm, or 400–560 nm.

[0066] The nuclear fuel slurry of this disclosure is usable in additive manufacturing processes. Suitable additive manufacturing equipment can be used that can accommodate the specific requirements of the materials used in the manufacture of the component (e.g., chemical resistance), the specific conditions for the use of the equipment itself (e.g., a specific atmosphere or vacuum conditions), and the size and shape of the manufactured component. Examples of suitable additive manufacturing equipment include SLA and DLP machines, electron beam-based additive manufacturing equipment, and DLP stereolithography equipment, any one of which may be modified or adopted for specific conditions.

[0067] The liquid materials and slurries of this disclosure, as well as the introduction of a second particle phase having low (or near-zero, or zero) absorbance, can be adapted for use in any suitable additive manufacturing process. Examples of suitable additive manufacturing processes are disclosed in ISO / ASTM 52900-15, which defines a category of additive manufacturing processes, including binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination, and photopolymerization. The contents of ISO / ASTM 52900-15 are incorporated herein by reference. Stereolithography is a form of additive manufacturing that uses photopolymerization. In examples of embodiments, the stereolithographic additive manufacturing technique includes photoinitiation by exposure to UV or beta radiation. In some embodiments, ultraviolet radiation is produced by a digital light processor (DLP) or a stereolithography apparatus (SLA). In other embodiments, beta radiation is produced by an electron beam (EBeam) or electron irradiation (EBI) apparatus. Although the methods and compositions disclosed herein are described within the context of stereography, it is clearly anticipated that such methods and compositions may be extended to or applied to other additive manufacturing methods.

[0068] An example of an additive manufacturing method may involve providing the controller of the additive manufacturing apparatus with a design for the component to be manufactured. Such a design can be incorporated into the additive manufacturing protocol. In one example of the method, a supply volume for the nuclear fuel slurry composition, such as a bath or reservoir, is established. The base portion of the component's green body is formed by curing a portion of the slurry composition that comes into contact with the movable base of the additive manufacturing apparatus. Alternatively, the base portion may be pre-assembled before the start of the additive manufacturing process. Additional portions of the component's green body are formed on the foundation of each layer (layer-by-layer) by first curing a portion of the slurry composition in contact with the base portion to form the first layer of the green body, and then curing a portion of the slurry composition in contact with the most recent deposit of the green body while moving the movable base to the interface between the surface of the supply volume and the most recently formed additional portion, thereby forming the additional portion. The movement of the movable base is usually carried out according to the design of the component and according to the instructions of the additive manufacturing protocol. In the example embodiment, moving the movable base relative to the interface between the surface of the supply volume and the most recently formed additional portion of the green body has an X-axis and Y-axis resolution of 50 μm or more, and a Z-axis resolution of 20 μm or more. In the example embodiment, each additional portion of the component green body formed on the base of each layer has a thickness of 10 μm or more, otherwise 25 μm to 50 μm. As soon as the manufacturing of each layer of the component green body is complete, the component green body can be removed from the additive manufacturing apparatus and sintered (or treated with other debinder / strengthening techniques) to form a high-density ceramic.

[0069] Subsequently, the manufactured green body can be sintered to form manufactured components (e.g., manufactured components for a nuclear reactor system). Other suitable forms of reinforcement (including combinations of temperature, pressure, and atmosphere) may be used to form the manufactured components. The reinforced manufactured components may be further processed by, for example, one or more machining processes, grinding, polishing, coating, carburizing, nitriding, oxidation, and etching.

[0070] Finally, Figures 5 and 6 show Green Bodies 500, 510, and 520, prepared using acrylic acid-based slurry materials, from two different angles. The acrylic acid-based slurry compositions are listed in Table 1 below, and a separate diluent component, namely polyethylene glycol or PRO14388 (an SR238 monomer / PEG-like diluent blend, commercially available from Sartomer), is used.

[0071] Table 1 - Slurry Compositions [Table 1]

[0072] Acrylic acid-based slurry compositions were used, as disclosed herein, particularly in addition processes using a digital light processor (DLP). While the green bodies shown herein are in the form of test structures, any structure can be formed using an appropriate addition process protocol.

[0073] Example Test A: The heterogeneous particle strategy was evaluated using both inorganic particles (Table 2) and low-absorbent organic particles (Table 3) in the test wavelength range (405 nm). SR238-based monomer formulations were used for each sample in Table 2. This basic formulation was used to eliminate the influence of advanced multi-monomer formulations and to focus solely on the effect of adding transparent particles, i.e., the effect of adding a second particle phase material. Furthermore, the SR238-based monomer formulation was used because the low base viscosity of SR238 resulted in the highest possible particle loading compared to mixed monomer formulations with higher base viscosity. Table 2 shows the change in curing depth (μm) as a function of loading (volume %) of low-absorbent particles and uranium particles for samples A-L. This was performed using the monomer formulations shown in Table 3 below for both organic and inorganic transparent layers.

[0074] Table 2 - Curing depth in various formulations [Table 2]

[0075] Table 3 - Formulation [Table 3]

[0076] The monomer formulations in Table 3 were used to evaluate the penetration depth as a function of the loading of low-absorbent particles. In the above formulations, the relative volumes of the monomer resin and dispersant changed as the concentration of the (uranium-containing or low-absorbent) powder increased. Therefore, in Table 3, the dispersant is given in relative terms to the powder, and the photoinitiator is given in relative terms to the monomer resin.

[0077] Formulas in volume percent from Table 3, and materials listed in Table 2, at 174 mW / cm² 2Samples were exposed to 405 nm curing radiation for 15 seconds, and the depth at which curing occurred in the slurry volume ("curing depth") was measured. A 3D printer was exposed to curing radiation, and its penetration depth was measured using a micrometer. Table 2 contains experimental measurements of curing depth for several samples, and Figure 7 shows the results of curing depth (μm) as a function of the ratio of (second particle phase with low absorbance):(first particle phase) in a larger sample set. As shown in Figure 7, the curing depth increased as the ratio of transparent resin particles:uranium particles increased. These data points are normalized by the transparent resin particle:uranium particle ratio, although they differ in monomer, photo-initiating system, and uranium volume loading. When normalized in this way, a clear trend is observed where the depth increases with increasing transparent particles. In other words, across various formulations, uranium particle loadings, and photo-initiating systems, Figure 7 shows that increasing the loading (volume %) of the second particle phase with low absorbance generally results in an increase in curing depth (μm). The above effect is linear up to a ratio of approximately 0.25, but asymptotically approaches the curing depth limit of 22 μm at a ratio of 1.0 between approximately 0.25 and 1.0. This asymptotic maximum value reflects the region where the effect originating from resin particles is superior to the effect originating from uranium particles.

[0078] Example Test B: In some embodiments, the polymer material for the second particle phase particles is replaced with a non-polymeric material having low, near-zero, or zero absorbance (compared to uranium-containing particles). For example, alumina (Al2O3) can be used as the second particle phase particles. Alumina is a viable material for second particle phase particles because it is highly transparent to curing radiation (having an absorbance of less than 0.25 Au) and has a low refractive index (about 1.8 at 400 nm). In typical examples, alumina particles have diameters of 3 μm to 12 μm, 6 μm to 10 μm, and 8 μm to 10 μm.

[0079] For the experimental investigation of this embodiment, two slurries were prepared using alumina at a 1200 grit (approximately 3 μm in diameter). The slurries were based on the slurry compositions described in Table 1, with the following modifications: Slurry A contained 25% uranium dioxide with a balance of SR238 / SR494 and no alumina; Slurry B contained 25% uranium dioxide with a balance of SR238 / SR294 and 25% alumina. The slurries were mixed similarly and subjected to a 174 mW / cm² load. 2 The penetration depth of the curing radiation at 405 nm was examined for 15 seconds. This penetration depth test was performed using the same procedure as recorded in relation to the slurries and results reported in relation to Tables 2-3 and Figure 7. In this example, the penetration depth of slurry A was 13 μm, and the penetration depth of slurry B was 18 μm. These penetration depth results demonstrate the effectiveness of using a second particle phase containing particles with low (or near-zero, or zero) absorbance (compared to uranium dioxide) to increase the penetration depth of the curing radiation.

[0080] While this application has described additive manufacturing components for nuclear reactors, particularly those related to fuel elements, the liquid materials, slurries, and additive manufacturing methods disclosed herein can be applied to the manufacture of other components for nuclear reactors, such as cladding materials, as well as to the manufacture of other technologies, such as petrochemicals (e.g., chemical reactors), the aerospace industry (e.g., for turbine blades and housing components, and for components in missiles and rockets, including combustion chambers, nozzles, valves, and cooling water pipes), and other complex manufactured articles. Furthermore, while this application has described fissile fuel materials, nuclear reactors, and related components, the principles, compositions, structures, features, arrangements, and processes disclosed herein can be applied to other materials, other compositions, other structures, other features, other arrangements, and other processes, and can be similarly applied to their manufacture and other types of reactors.

[0081] With regard to substantially all use of plural and / or singular terms herein, those skilled in the art will recognize that plural forms are convertible to singular forms and / or singular forms are convertible to plural forms as appropriate to the context and / or application. Various singular / plural permutations are not explicitly described herein for the purposes of clarity.

[0082] The subjects described herein sometimes refer to various components that are contained within or related to various other components. It should be understood that such depicted architectures are merely illustrative, and in practice, many other configurations that achieve similar functions are implementable. Conceptually, any arrangement of components to achieve similar functions is effectively “related” in such a way that the desired function is achieved. Therefore, any two components disclosed herein that are combined to achieve a particular function can be considered “related” to each other, regardless of the configuration or intervening components, in such a way that the desired function is achieved. Similarly, any two such related components can be considered “operably connected” or “operably coupled” to each other in order to achieve the desired function, and any two components that can be combined in such a way can be considered “operably coupleable” to each other in order to achieve the desired function. Specific embodiments that can be operationally combined include, but are not limited to, physically mateable and / or physically interacting components, and / or wirelessly interactable and / or theoretically interacting and / or theoretically interactable components.

[0083] In some cases, one or more components may be referred to herein as “configured to,” “configured by,” “configurable to,” “operable / operative to,” “adapted / adaptable,” “able to,” “conformable / conformed to,” etc. Unless otherwise specified in the context, a person skilled in the art will recognize that such terms (e.g., “configured to”) may generally encompass active components and / or inactive components and / or standby components.

[0084] While specific aspects of the subject matter described herein have been shown and explained, it will be apparent to those skilled in the art that changes and modifications can be made based on the description herein, provided that they do not deviate from the subject matter and its broader aspects. Accordingly, the appended claims encompass within their scope all such changes and modifications that fall within the true spirit and scope of the subject matter described herein. In general, those skilled in the art will understand that the terms used herein, and in particular in the appended claims (e.g., in the body of the appended claims), are generally "open" terms (for example, the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "at least having," and the term "includes" should be interpreted as "including, but not limited to," etc.). Furthermore, those skilled in the art will understand that if a particular number is intended in an introduced claim, such intention is explicitly stated in the claim, and if there is no such statement, there is no such intention. For example, for the purposes of understanding, the following claims would include the use of the prefatory phrases “at least one” and “one or more” to introduce the claim description. However, the use of such phrases should not be interpreted as meaning that the introduction of the claim description with the indefinite article “a” or “an” limits any particular claim containing such introduced claim description to a claim containing only one such description. The same applies if the same claim includes the prefatory phrase “one or more” or “at least one” and an indefinite article such as “a” or “an” (for example, “a” and / or “an” should normally be interpreted as meaning “at least one” or “one or more”); the same applies to the definite article used to introduce the claim description.Furthermore, even if specific numerical values ​​are explicitly stated in an introductory claim, a person skilled in the art will understand that such statements should generally be interpreted as meaning "at least" the stated numerical values ​​(for example, a bare statement of "two statements" without other modifiers generally means at least two statements, or two or more statements). Furthermore, where a convention similar to "at least one A, B, and C, etc." is used, such construction is generally intended to be understood by a person skilled in the art (for example, "a system having at least one of A, B, and C" includes, but is not limited to, a system having only A, only B, only C, both A and B, both A and C, both B and C, and / or a system having any of A, B, and C, etc.). Where a similar convention is used, such construction is generally intended to be understood by those skilled in the art (for example, “a system having at least one of A, B, or C” includes, but is not limited to, a system having only A, only B, only C, both A and B, both A and C, both B and C, and / or a system having any of A, B and C, etc.). Furthermore, those skilled in the art will understand that in the specification, claims, or drawings, the phrase “and / or,” which is a disjunctive word representing two or more alternative terms, should be considered to include one term, either term, or both terms, unless otherwise indicated in the context. For example, the phrase “A or B” is generally understood to include “A or B” or “A and B.”

[0085] With respect to the attached claims, those skilled in the art will understand that the operations described herein may generally be performed in any order. Furthermore, although various operation flows are described sequentially, it should be understood that various operations may be performed in any order other than those indicated, or simultaneously. Examples of such alternative orders include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orders, unless otherwise indicated in the context. Moreover, terms such as "responsive to," "related to," or other past tense adjectives are generally not intended to exclude such variants unless otherwise indicated in the context.

[0086] Those skilled in the art will understand that the specific exemplary processes, and / or devices, and / or techniques described above are representative of more general processes, and / or devices, and / or techniques taught elsewhere in this specification (e.g., the appended claims, and / or other parts of this application).

[0087] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will also be obvious to those skilled in the art. The various aspects and embodiments disclosed herein are for the purposes of disclosure only and are not intended to be limited to the true scope and spirit set forth by the following claims.

[0088] The exemplary embodiments described in the specification, drawings, and claims are not intended to be limiting. Other embodiments may be used and other modifications may be made, provided that they do not deviate from the spirit or scope of the subject matter described herein.

[0089] Those skilled in the art will recognize that the components (e.g., operations), devices, objects, and accompanying discussions described herein are used as examples for conceptual clarity, and that variations in their various configurations are expected. Consequently, when used herein, the specific examples and accompanying discussions described are intended to represent their more general classifications. Generally, the use of any particular example is intended to represent its classification, and specific components (e.g., operations), devices, and objects not described herein should not be considered limiting.

Claims

1. A slurry for additive manufacturing, wherein the slurry is such that, relative to the total volume of the slurry, it is as follows: Multiple first particles in an amount of 30% to 40% by volume; Multiple second particles in an amount of 10% to 20% by volume; Dispersant in an amount greater than 0% by volume and up to 5% by volume; Light absorber exceeding 0% by volume; Photoinitiators exceeding 0% by volume; and At least one monomer resin in an amount between 25% by volume and less than 45% by volume Having a composition containing, The total amount of the plurality of first particles and the plurality of second particles is a maximum of 60% by volume. The first particle has a composition containing a uranium-containing material, The uranium-containing material is uranium metal, uranium alloy, uranium ceramic, or uranium-molybdenum alloy. The plurality of first particles have a particle size D50 of 40 nm to 10 μm. The second particle has an absorbance of 0.001Au or more and 0.7Au or less at wavelengths of 300 nm to 700 nm. The second particle has a composition containing polyamide or polyethylene glycol, The light absorber and photoinitiator act at incident wavelengths of 300 nm to 700 nm. The monomer resin is an acrylic acid-based monomer resin, a methacrylic acid-based monomer, or a mixture thereof. Slurry for additive manufacturing.

2. The slurry for additive manufacturing according to claim 1, wherein the second particle comprises a composition further comprising 2% to 5% by volume of a neutron absorbent, and the neutron absorbent has a neutron absorption cross-section of 60,000 barns or more.

3. The slurry for additive manufacturing according to claim 2, wherein the neutron absorber has a composition comprising at least one element selected from the group consisting of cerium, yttrium, gadolinium, xenon, and samarium.

4. The slurry for additive manufacturing according to claim 2, wherein the second particles further comprise a composition containing 2% to 5% by volume of a localization stabilizer.

5. The slurry for additive manufacturing according to claim 4, wherein the localization stabilizer has a composition containing iron.

6. The slurry for addition manufacturing according to claim 1, wherein at least 50% of the monomer resin is acrylic acid-based.

7. The slurry for addition manufacturing according to claim 1, wherein the acrylic acid-based monomer resin is monofunctional, difunctional, trifunctional, tetrafunctional, or a mixture thereof.

8. The slurry for additive manufacturing according to claim 7, wherein at least 50% of the acrylic acid-based monomer resin is bifunctional.

9. The slurry for additive manufacturing according to claim 1, wherein the composition further comprises more than 0% to 15% by volume of a diluent, and the refractive index of the diluent is greater than or equal to the refractive index of the monomer resin.

10. The slurry for addition according to claim 9, wherein the diluent is methylnaphthalene.

11. A slurry for additive manufacturing, wherein the slurry is such that, relative to the total volume of the slurry, it is as follows: Multiple first particles in an amount of 30% to 40% by volume; Multiple second particles in an amount of 10% to 20% by volume; Dispersant in an amount greater than 0% by volume and up to 5% by volume; Light absorber exceeding 0% by volume; Photoinitiators exceeding 0% by volume; and At least one monomer resin in an amount between 25% by volume and less than 45% by volume Having a composition containing, The total amount of the plurality of first particles and the plurality of second particles is a maximum of 60% by volume. The first particle has a composition containing a uranium-containing material, The second particle has an absorbance of 0.001Au to 0.7Au, 0.01Au to 0.6Au, or 0.1Au to 0.5Au at wavelengths of 300 nm to 700 nm. The aforementioned light absorber and photoinitiator are slurry for additive manufacturing, acting at incident wavelengths of 300 nm to 700 nm.

12. The slurry for additive manufacturing according to claim 11, wherein the second particle has an absorbance of 0.001Au to 0.26Au at a wavelength of 300 nm to 700 nm.

13. The slurry for additive manufacturing according to claim 11 or 12, wherein the second particles have a composition comprising polyamide or polyethylene glycol.

14. The slurry for additive manufacturing according to any one of claims 11 to 13, wherein the second particle comprises a composition further comprising 2% to 5% by volume of a neutron absorbent, and the neutron absorbent has a neutron absorption cross-section of 60,000 barns or more.

15. The slurry for additive manufacturing according to claim 14, wherein the neutron absorber has a composition comprising at least one element selected from the group consisting of cerium, yttrium, gadolinium, xenon, and samarium.

16. The slurry for additive manufacturing according to any one of claims 11 to 15, wherein the second particles have a composition further comprising 2% to 5% by volume of a localization stabilizer.

17. The slurry for additive manufacturing according to claim 16, wherein the localization stabilizer has a composition containing iron.

18. The slurry for additive manufacturing according to any one of claims 11 to 17, wherein the uranium-containing material is uranium metal, uranium alloy, uranium ceramic, or uranium-molybdenum alloy.

19. The slurry for additive manufacturing according to any one of claims 11 to 17, wherein the uranium-containing material is uranium oxide, uranium dioxide, uranium carbide, uranium oxycarbide, uranium nitride, uranium silicide, uranium fluoride, uranium chloride, a cermet of uranium oxide and tungsten, a cermet of uranium dioxide and tungsten, a cermet of uranium oxide and molybdenum, or a cermet of uranium dioxide and molybdenum.

20. The slurry for additive manufacturing according to claim 19, wherein the uranium-containing material is uranium oxide, uranium dioxide, or uranium trioxide.

21. The slurry for additive manufacturing according to any one of claims 11 to 17, wherein the uranium-containing material is U(C, O, N, Si, F, Cl).

22. The slurry for additive manufacturing according to any one of claims 11 to 21, wherein the plurality of first particles have a particle size D50 of 40 nm to 10 μm.

23. The slurry for additive manufacturing according to any one of claims 11 to 22, wherein the monomer resin is an acrylic acid-based monomer resin, a methacrylic acid-based monomer, or a mixture thereof.

24. The slurry for additive manufacturing according to claim 23, wherein at least 50% of the monomer resin is acrylic acid-based, or 70-90% is acrylic acid-based.

25. The slurry for additive manufacturing according to any one of claims 11 to 24, wherein the acrylic acid-based monomer resin is monofunctional, difunctional, trifunctional, tetrafunctional, or a mixture thereof.

26. The slurry for additive manufacturing according to claim 25, wherein at least 50% of the acrylic acid-based monomer resin is bifunctional, or at least 80% is bifunctional, or 70% to 90% is bifunctional.

27. The slurry for additive manufacturing according to any one of claims 11 to 26, wherein the composition further comprises more than 0% to 15% by volume of a diluent.

28. The slurry for additive manufacturing according to claim 27, wherein the refractive index of the diluent is greater than or equal to the refractive index of the monomer resin.

29. The slurry for additive manufacturing according to claim 27 or 28, wherein the diluent is inert.

30. The slurry for addition according to any one of claims 27 to 29, wherein the diluent is methylnaphthalene.

31. The slurry for additive manufacturing according to any one of claims 1 to 30, wherein the composition is cured by photoinitiation or electron beam irradiation.

32. A method for manufacturing components of a nuclear reactor system, wherein the manufacturing method is: This includes using an additive manufacturing protocol with nuclear fuel slurry to produce green bodies for components of a nuclear reactor system. The nuclear fuel slurry, in relation to the total volume of the slurry, is as follows: Multiple first particles in an amount of 30% to 40% by volume; Multiple second particles in an amount of 10% to 20% by volume; Dispersant in an amount greater than 0% by volume and up to 5% by volume; Light absorber exceeding 0% by volume; Photoinitiators exceeding 0% by volume; and At least one monomer resin in an amount between 25% by volume and less than 45% by volume Having a composition containing, The total amount of the plurality of first particles and the plurality of second particles is a maximum of 60% by volume. The first particle has a composition containing a uranium-containing material, The uranium-containing material is uranium metal, uranium alloy, uranium ceramic, or uranium-molybdenum alloy. The plurality of first particles have a particle size D50 of 40 nm to 10 μm. The second particle has an absorbance of 0.001Au to 0.7Au at wavelengths of 300 nm to 700 nm. The second particle has a composition containing polyamide or polyethylene glycol, The aforementioned light absorber and photoinitiator act at incident wavelengths of 300 nm to 700 nm. The monomer resin is an acrylic acid-based monomer resin, a methacrylic acid-based monomer, or a mixture thereof. Manufacturing method.

33. A method for manufacturing components of a nuclear reactor system, wherein the manufacturing method is: This includes using an additive manufacturing protocol with nuclear fuel slurry to produce green bodies for components of a nuclear reactor system. The nuclear fuel slurry, in relation to the total volume of the slurry, is as follows: Multiple first particles in an amount of 30% to 40% by volume; Multiple second particles in an amount of 10% to 20% by volume; Dispersant in an amount greater than 0% by volume and up to 5% by volume; Light absorber exceeding 0% by volume; Photoinitiators exceeding 0% by volume; and At least one monomer resin in an amount between 25% by volume and less than 45% by volume Having a composition containing, The total amount of the plurality of first particles and the plurality of second particles is a maximum of 60% by volume. The first particle has a composition containing a uranium-containing material, The second particle has an absorbance of 0Au to less than 1.0Au, or otherwise 0.001Au to 0.7Au, 0.01Au to 0.6Au, or 0.1Au to 0.5Au at a wavelength of 300 nm to 700 nm. The aforementioned light absorber and photoinitiator act at incident wavelengths of 300 nm to 700 nm. Manufacturing method.

34. The manufacturing method according to claim 33, wherein the second particle has an absorbance of 0.001Au to 0.26Au at a wavelength of 300 nm to 700 nm.

35. The manufacturing method according to claim 33 or 34, wherein the second particle has a composition containing a flammable poison or a moderator.

36. The manufacturing method according to any one of claims 33 to 35, wherein the second particle comprises a composition further comprising 2% to 5% by volume of a neutron absorbent, and the neutron absorbent has a neutron absorption cross-section of 60,000 barns or more.

37. The manufacturing method according to claim 36, wherein the neutron absorber has a composition comprising at least one element selected from the group consisting of cerium, yttrium, gadolinium, xenon, and samarium.

38. The manufacturing method according to any one of claims 33 to 37, wherein the second particle comprises a composition further comprising 2% to 5% by volume of a localization stabilizer.

39. The manufacturing method according to claim 38, wherein the localization stabilizer has a composition containing iron.

40. The manufacturing method according to any one of claims 33 to 39, wherein the uranium-containing material is a uranium metal, a uranium alloy, a uranium ceramic, or a uranium-molybdenum alloy.

41. The manufacturing method according to any one of claims 33 to 39, wherein the uranium-containing material is uranium oxide, uranium dioxide, uranium carbide, uranium oxycarbide, uranium nitride, uranium silicide, uranium fluoride, uranium chloride, a cermet of uranium oxide and tungsten, a cermet of uranium dioxide and tungsten, a cermet of uranium oxide and molybdenum, or a cermet of uranium dioxide and molybdenum.

42. The manufacturing method according to claim 41, wherein the uranium-containing material is uranium oxide or uranium dioxide.

43. The manufacturing method according to any one of claims 33 to 39, wherein the uranium-containing material is U (C, O, N, Si, F, Cl).

44. The manufacturing method according to any one of claims 32 to 43, further comprising sintering the green body to form components of a nuclear reactor system.

45. The manufacturing method according to any one of claims 32 to 44, wherein the additive manufacturing protocol is developed using a surrogate slurry.

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