Bulk powder prediction for increased efficacy of canister filling in a hot isostatic press system

Abstract

A method of maximizing at least one flow property of bulk powder in a Hot Isostatic Press (HIP) canister filling system is disclosed. The method includes a computer system for carrying out a contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM) to predict at least one flow property of the bulk powder through multiple sections of the canister filling system. At least one parameter for discharging or flow the bulk powder through the HIP canister filling system is based on the at least one material property or predicted flow property of the bulk powder. A HIP canister filling system for carrying out the disclosed method is also disclosed.

Description

BULK POWDER PREDICTION FOR INCREASED EFFICACY OF CANISTER FILLING IN A HOT ISOSTATIC PRESS SYSTEMDESCRIPTION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 624,910 filed January 25, 2024, the entire content of which is hereby incorporated by reference.Technical Field

[0002] The present disclosure relates generally to a process for filling canisters used in the hot isostatic pressing of bulk powders, including radioactive nuclear wastes, and in particular to the prediction and increased efficacy while filling the canisters. While the description specifically refers to the challenges of canister filling with different types of bulk powders, such as Idaho calcine, it should be appreciated that the description is not limited to this exemplary embodiment only and has general applicability to other forms of bulk powder in a canister filling process.Background

[0003] Developing nuclear waste treatment solutions often involves using high- fidelity, non-radioactive simulated waste to ensure safe handling during process development and technological demonstrations. However, utilizing high-fidelity nuclear waste simulants, such as calcined material from radioactive ores, can pose challenges due to their scarcity. One non-limiting embodiment of such a calcined material is referred to as "Idaho calcine," which is a calcined material from uranium ores that were historically processed in Idaho for their uranium content. As these calcines contain radioactive elements, there are expected concerns about environmental and health safety, and a corresponding need for their safe disposal.

[0004] Accordingly, there is a need for a method to model the flow properties of materials that contain radioactive, nuclear or other hazardous or toxic materials. There is also a need for using those modeled powder flow properties to improve the safe handling and efficient disposal of such materials. The present disclosure solves these needs and others in the prior art by modeling flow properties of bulk powders to predict restrictions or limitations in the flow of such powders in a filling process for canister that will be subsequently exposed to thermal and / or pressure treatments, such as with hot isostatic pressing.Summary

[0005] This disclosure provides an approach to bulk material handling of simulated radioactive material, focusing on the challenging Idaho calcine waste. Due to the limited availability of the simulant, virtual dynamic simulations were utilized to develop technology demonstration scale models to assess the efficacy of the Discrete Element Method (DEM) for process development studies. The DEM model was validated by historical experimental data, demonstrating its feasibility with affordable hardware.

[0006] According to one embodiment, there is disclosed a method of maximizing at least one flow property of bulk powder in a Hot Isostatic Press (HIP) canister filling system. In one embodiment, the method includes the steps of: in a computer system, carrying out a contact model analysis for the dynamic simulation of the flow properties of bulk powder through a multi-unit HIP canister filling system using a Discrete Element Method (DEM) to predict at least one flow property of said bulk powder.

[0007] In one embodiment, the method includes calibrating the contact model analysis using at least one variable associated with the bulk powder or the canisterfilling system, or both. The method next comprises discharging bulk powder from a storage hopper using a first valve; flowing the powder through the first valve and a second valve (Fl); flowing said powder through the second valve and into at least one process pipeline (F2). The method further comprises flowing the powder from the at least one process pipeline through at least one filling nozzle (F3) into the canister.

[0008] In some embodiments, the flow of powder, such as from the storage hopper discharge, or one or more of flow steps Fl, F2 or F3, is based on the at least one material property or predicted flow property of the bulk powder.

[0009] According to one embodiment, there is disclosed a hot isostatic press (HIP) canister filling system, for performing the disclosed method. For example, the (HIP) canister filling system may comprise a storage hopper for storing bulk powder, a first valve configured to discharge the bulk powder from the storage hopper when activated, a second valve configured to receive said bulk powder from the first valve, a process pipeline for transporting the bulk powder discharged from the second valve to a filling nozzle, a port connecting the filling nozzle to the canister.

[0010] In some embodiments, the disclosed system further includes a computer system including a main memory for storing computer readable code for a contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM), and at least one processor coupled to the main memory. In some embodiments, the at least one processor executing the computer readable code in the main memory to cause the application module to carry out contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM) prior to discharging said bulk powder from the storage hopper to predict at least one material property or flow property of the bulk powder through multiple sections of the canister filling system.Brief Description of Drawings

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate some disclosed embodiments and, together with the description, serve to explain the disclosed embodiments. The particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the present disclosure. The description taken with the drawings makes apparent to those skilled in the art how embodiments of the present disclosure may be practiced.

[0012] FIG. 1 is a HIP canister filling system consistent with some disclosed embodiments.

[0013] FIG. 2 is a DEM model of HIP canister filling system consistent with some disclosed embodiments.

[0014] FIG. 3 is a rotary valve for mass flow' rate control in the filling system, consistent with some disclosed embodiments.

[0015] FIGS. 4A, 4B and 4C are schematics of a hopper butterfly valve showing opening sequences, which are closed (FIG 4A), partially opened (FIG. 4B) and fully opened (FIG. 4C) consistent with some disclosed embodiments.

[0016] FIGS. 5A, 5B and 5C are schematics of a rotary valve metering cycle showing opening sequences, which are closed (FIG 5A). partially opened (FIG. 5B) and fully opened (FIG. 5C), consistent with some disclosed embodiments.

[0017] FIG. 6 is a schematic showing the flow of powder into the container consistent with some disclosed embodiments.

[0018] FIG. 7 is a bar chart showing cumulative powder mass [kg] collected in the container consistent with some disclosed embodiments.

[0019] FIGS 8A and 8B show 25% filled containers filled experimentally according to some disclosed embodiments (FIG. 8A), compared to DEM simulation (FIG. 8B), reference line indicating 90 mm powder bed height.

[0020] FIGS. 9A, 9B and 9C show image-processed photographs highlighting the surface profile formed by the powder bed for 25% filled (FIG. 9A), 50% filled (FIG. 9B) and 75% filled (FIG. 9C).

[0021] FIGS. 10A and 10B show emulated 75% filled material densified by vibratory compaction (FIG. 10A) and gas pulse compacted (FIG. 10B) Idaho calcine simulant where the reference line indicates 275 mm powder bed height.

[0022] FIGS. 11 A and 1 IB show DEM simulation of the overfilled container (FIG. 11A) and recovery container (FIG. 11B).

[0023] FIG. 13A shows current DEM model emulating 25% filled container. FIG. 13B shows the original DEM model emulating 25% filled container.

[0024] FIGS. 14A and 14B show representative photographs of gas pulse compaction (FIG. 14A) and vibratory compaction (FIG. 14B) filled canister processed by HIP.Detailed Description of the Disclosure

[0025] As disclosed herein, there is described a method of maximizing at least one flow property of bulk powder in a Hot Isostatic Press (HIP) canister filling system. According to some embodiments, the method includes the steps of, in a computer system, carrying out a contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM) to predict limitations in at least one flow property of the bulk powder through multiple sections of the canister filling system.

[0026] In some embodiments, there is a step of calibrating the contact model analysis using at least one variable associated with the bulk powder or the canister filling system, or both. For example, according to some embodiments, the contact model analysis can be calibrated using at least one of the following methods: loose poured bulk density; wall shear; uniaxial compressibility; flow energy; shear test; and hopper discharge.

[0027] In some embodiments, the method includes discharging bulk powder from a storage hopper, such as by actuating (or activating depending on the type of valve) a valve to cause powder in the hopper to flow from the storage hopper through at least one valve, such as a butterfly valve and eventually into a canister. In some embodiments, the bulk powder is gravity fed into the canister.

[0028] In some embodiments, the method includes flowing the powder from the at least one valve, and in some embodiments a second valve, such as a rotary valve, through at least one process pipeline. The least one process pipeline comprises a circular pipe, which may include one or more elbows to direct the flow of powder to a canister. In one embodiment, the process pipeline includes at least one, such as two 60° elbows for connecting the storage hopper to the canister, via both a butterfly valve and a subsequent rotary valve. The rotary valve may be activated by rotating or oscillating it up to 180° in forward and reverse directions to dispense bulk powder into the canister via the filling nozzle. In some embodiments, the filling nozzle further includes a port coupling system.

[0029] In some embodiments, the method includes flowing the powder from the at least one process pipeline through at least one filling nozzle into the canister, wherein the flow characteristics of at least one of the discharging step, or the flow steps throughthe at least one valve or through the pipeline is based on the predicted flow properties of the bulk powder.

[0030] In some embodiments, the rate of flow is based on the at least one predicted flow property of the bulk powder selected fronrthe rate of discharge from the storage hopper using a first valve; the rate of flow through at least one process pipeline using a second valve; the rate of flow through at least one filling nozzle into the canister; or combinations thereof.

[0031] In some embodiments, the first valve and the second valve comprise either a butterfly valve or a rotary valve. In some embodiments, the first valve comprises a butterfly valve and the second valve comprises a rotary valve. In some embodiments the butterfly valve is actuated in an amount to adjust the flow of the bulk powder out of the storage hopper based on the at least one predicted flow property of the bulk powder.

[0032] In some embodiments, the rotary valve is actuated in an amount to adjust the flow of the bulk powder based on the at least one predicted flow property of the bulk powder through the rotary valve and into the process pipeline.

[0033] In some embodiments, the method described herein can be used to model the flow properties of bulk powders that include nuclear waste, radioactive waste, or other toxic waste. For example, the nuclear waste includes calcined material from uranium ores.

[0034] In some embodiments, the method further comprises at least one powder densification step to enhance the efficiency of powder encapsulation, such as a gas pulse compaction process or a vibratory’ compaction process.

[0035] In some embodiments, the contact model analysis includes particleparticle analysis for modelling interactions with particles in the bulk powder, whereinthe contact model includes Poisson Ratio, Solid Density, Shear Modulus, Particle-Particle Coefficient of Restitution, Particle-Particle Coefficient of Static Friction,Particle-Particle Coefficient of Rolling Friction of the particles located in the bulk powder.

[0036] In some embodiments, the contact model analysis includes particleboundary analysis for modelling interactions with particles in the bulk powder and at least one surface of the multiple sections of the canister filling system in which the particles come into contact. In this embodiment, the contact model includes Poisson Ratio, Solid Density', Shear Modulus, Particle-Boundary Coefficient of Restitution, Particle- Boundary Coefficient of Static Friction, Particle- Boundary Coefficient of Rolling Friction.

[0037] In some embodiments, the contact model analysis includes both the contact model analysis that includes a particle-particle analysis for modelling interactions with particles in the bulk powder, and a particle-boundary analysis for modelling interactions with particles in the bulk powder and surfaces of the multiple sections of the canister filling system in which the particles come into contact.

[0038] According to one embodiment, there is disclosed a hot isostatic press (HIP) canister filling system, for performing the disclosed method. For example, the (HIP) canister filling system may comprise a storage hopper for storing bulk powder, a first valve configured to discharge the bulk powder from the storage hopper when activated, a second valve configured to receive said bulk powder from the first valve, a process pipeline for transporting the bulk powder discharged from the second valve to a filling nozzle, a port connecting the filling nozzle to the canister. A more detailed description of the filling nozzle can be found in US Patent No.: 1 l,393,605B2 (WO2018169594), which is herein incorporated by reference.

[0039] In some embodiments, the disclosed system further includes a computer system including a main memory for storing computer readable code for a contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM), and at least one processor coupled to the main memory. In some embodiments, the at least one processor executing the computer readable code in the main memory to cause the application module to carry out contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM) prior to discharging said bulk powder from the storage hopper to predict limitations in at least one flow property of said bulk powder through multiple sections of the canister fdling system.

[0040] In some embodiments, the hot isostatic press canister filling system is configured to execute a contact model analysis that includes particle-particle analysis for modelling interactions with particles in the bulk powder, wherein the contact model includes Poisson Ratio, Solid Density, Shear Modulus, Particle-Particle Coefficient of Restitution, Particle-Particle Coefficient of Static Friction, Particle-Particle Coefficient of Rolling Faction of the particles located in the bulk powder.

[0041] In some embodiments, the hot isostatic press canister filling system is configured to execute a contact model analysis that includes particle-boundary analysis for modelling interactions with particles in the bulk powder and at least one surface of the multiple sections of the canister filling system in which the particles come into contact, wherein the contact model includes Poisson Ratio. Solid Density, Shear Modulus, Particle-Boundary’ Coefficient of Restitution, Particle- Boundary’ Coefficient of Static Friction, Particle- Boundary Coefficient of Rolling Friction.

[0042] In some embodiments, the contact model analysis includes both the contact model analysis that includes a particle-particle analysis for modellinginteractions with particles in the bulk powder, and a particle-boundary' analysis for modelling interactions with particles in the bulk powder and surfaces of the multiple sections of the canister filling system in which the particles come into contact.

[0043] According to some embodiments, there is disclosed a contact model for simulating the flow properties of the Idaho calcine waste simulant using the Discrete Element Method (DEM). This was calibrated using at least one of the following six (6) methods:

[0044] (1) Loose poured bulk density method, as described in Standards Australia, ‘‘AS 3880:2017 Flow properties of coal.” Australian Standard, Aug. 30, 2017, which is herein incorporated by reference.

[0045] (2) Wall shear, as described in Standards Australia, “AS 3880:2017 Flow properties of coal.” Australian Standard, Aug. 30, 2017, which is herein incorporated by reference.

[0046] (3) Freeman uniaxial compressibility, as described in J. Yang, T. Bell, and M. Pasha, “Evaluation of a Uniaxial Powder Tester and Comparison with an Annular Shear Tester.” Powder Technol, vol. 403, p. 117405, May 2022, doi: 10. 1016 / j.powtec.2022. 117405. which is herein incorporated by reference.

[0047] (4) Freeman FT4 flow energy ASTM D7891. “Standard Test Method for Shear Testing of Powders Using the Freeman Technology FT4 Powder Rheometer Shear Cell,” 2015, doi: 10.1520 / D7891-15. which is herein incorporated by reference.

[0048] (5) Schulze RST XS shear test ASTM D6773-16. “Standard Test Method for Bulk Solids Using Schulze Ring Shear Tester.” ASTM International. West Conshohocken, PA www.astm.org, 2016. doi: 10.1520 / D6773-16, which is herein incorporated by reference.

[0049] (6) Hopper discharge A. P. Grima, “Quantifying and modelling mechanisms of flow in cohesionless and cohesive granular materials,” Doctor of Philosophy thesis, University of Wollongong, 2011. [Online]. Available: http: / / ro.uow.edu.au / theses / 3425, which is herein incorporated by reference.

[0050] These calibrated bulk material properties aligned well with experimental powder characterization results and within acceptable error margins. However, despite meticulous calibration, until the present study, the flow properties of the virtual Idaho calcine simulant remained unvalidated by an actual application. Based on this calibrated contact model, a full-scale three-dimensional model was developed to emulate the flow of the Idaho calcine simulant within a HIP canister filling system. Predictions from this model were then compared against historical data from past canister-filling experiments to assess its precision. A review of prior literature reveals that while single component flow properties have been simulated, there is a lack of research and no disclosures exploring the dynamic simulation of multi-unit operational processes, as described herein.

[0051] The following references discuss flow prediction models, and are incorporated by reference for such teaching: W. R. Ketterhagen, J. S. Curtis, C. R. Wassgren, and B. C. Hancock, “Predicting the flow mode from hoppers using the discrete element method,” Powder Technol, vol. 195, no. 1, pp. 1-10, Oct. 2009, doi: 10.1016 / j.powtec.2009.05.002: B. Xu, Z. Zhu, Z. Tin, and D. Wang, “Solid-liquid two- phase flow and erosion calculation of butterfly valves at small opening based on DEM method." Industrial Lubrication and Tribology, vol. 73, no. 3, 2020, doi: 10.1108 / ILT- 07-2020-0264; B. Xu, Z. Zhu, Z. Lin, D. Wang, and G. Ma, “Numerical and experimental research on the erosion of solid-liquid two-phase flow in transport butterfly valve based on DEM method,” Industrial Lubrication and Tribology, vol. 73,no. 4, 2021, doi: 10.1108 / ILT- 12-2020-0454; and G. S. Chadha, F. Westbrink, T. Schutte, and A. Schwung, “Optimal dosing of bulk material using mass-flow estimation and DEM simulation f in Proceedings of the IEEE International Conference on Industrial Technology, 2018. doi: 10. 1109 / ICIT.2018.8352186.

[0052] The filling system consists of elements frequently found in industrial powder filling processes, including a powder storage hopper, rotary valve and butterfly valve. While numerous studies have targeted single-component flow properties, there is a lack of research exploring the dynamic simulation of multi-unit operational processes. The variations in the various system parts, such as filling nozzle and port coupling device, and the scarcity of the Idaho calcine simulant further underscore the novelty of this work.

[0053] Although a preliminary contact model was developed, attempting to emulate the HIP canister filling process, failed to reproduce specific attributes, such as the filled level and angle of repose. The initial preliminary model underwent refinement with additional calibration measures in this research.

[0054] This research aims to validate the newly developed contact model, exploring its potential as an engineering tool for predicting the flow and behavior of the Idaho calcine simulant in an integrated system tailored for HIP canister filling.Calibrated Contact Model

[0055] The contact model parameters, which met the criteria of all six previously mentioned calibration models, are detailed in the subsequent tables. Particleparticle interactions are governed by the parameters listed in Table I, while the particleboundary interactions (stainless steel with Ra 12 pm surface finish) are governed by the parameters presented in

[0056] Table II. The current study used these specific contact model parameters to simulate the HIP canister-filling processes.

[0057] All process-contact boundaries in the filling system were made of stainless steel with a surface finish of Ra 12 pm, whereas the glass container was assumed to be made of low-friction borosilicate glass. As shown in

[0058] Table II, these particle-boundary interactions were governed by the calibrated contact model parameters.Table I. Particle-Particle Contact Model ParametersParticle PropertiesPoisson Ratio v 0.25Solid Density p 2.322 g / ccShear Modulus G 2E + 07 PaParticle-Particle Coefficient of Restitution e 0.6Particle-Particle Coefficient of Static Friction psp-P0.35Particle-Particle Coefficient of Rolling Friction r]>-P0.375EEPA Model ConfigurationConstant Pull-off Force fo IE - 06 NSurface Energy Ay 4 J / m2Contact Plasticity Ratio X 0.1Slope Exp n 1.5Tensile Exp X 20Tangential Stiff Multiplier (pm 0.666667Type C Rolling Friction Model ConfigurationCoefficient of Rolling Stiffness kr3Rolling Viscous Damping Ratio T| 0.3Table IL Particle-boundary Contact Model ParametersRa 12 jim Stainless SteelPoisson Ratio n 0.3Solid Densify p 7.8 g / ccShear Modulus G 7.3 E + 10 PaParticle-Boundary Coefficient of Restitution e 0.35Particle-Boundary Coefficient of Static Friction psp-P0.34Particle-Boundary Coefficient of Rolling Friction piP-P0.1Low-friction GlassPoisson Ratio D 0.3Solid Densify p 2.5 g / ccShear Modulus G 2.4 E + 10 PaParticle-Boundary Coefficient of Restitution e 0.5Particle-Boundary Coefficient of Static Friction psp-P0.1Particle-Boundary Coefficient of Rolling Friction piP-P0.01SIMULATION SOFTWARE AND HARDWARE

[0059] The DEM models discussed herein were developed using Altair EDEM®. The particle-particle interactions were governed by the Edinburgh Elasto- Plastic Adhesion model (EEPA), as described in J. P. Morrissey. J. Y. Ooi, J. F. Chen, K. Tano, and G. Horrigmoe, “Experimental and discrete element modelling of cohesive iron ore fines " in Proceedings of Particle-Based Methods III Fundamentals and Applications - Particles. Stuttgart, Germany: International Center for Numerical Methods in Engineering, 2013, pp. 224-235, which is incorporated by reference herein.

[0060] The particle-particle interactions were also governed by the Type C Rolling Friction model, as described in J. Ai, J. F. Chen, J. M. Rotter, and J. Y. Ooi. ‘'Assessment of rolling resistance models in discrete element simulations " Powder Technol, vol. 206. no. 3, 2011, doi: 10. 1016 / j.powtec.2010.09.030, which is incorporated by reference herein.

[0061] The particle-boundary' interactions were managed using the Hertz- Mindlin model, as described in Johnson K. L., Kendall K., and Roberts A. D., “Surface energy and the contact of elastic solids f Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, vol. 324, no. 1558, 1971, doi: 10. 1098 / rspa. 1971.0141, which is incorporated by reference herein.

[0062] One of the objectives of this disclosure is to evaluate the efficiency of executing DEM simulations using readily accessible hardware. The DEM models were processed on a custom-built desktop PC outfitted with consumer-grade hardware typical of an engineering analysis office. With the Nvidia RTX 4090 GPU, which boasts over 16,000 CUD A cores, there is a considerable decrease in processing time compared to DEM models predominantly solved by CPUs. This hardware setup facilitates the simulation of DEM models with a particle count exceeding 1 million. Details of the desktop PC configuration are provided in Error! Reference source not found..Table III. Custom-built Desktop PC SpecificationDEM Software Altair EDEM®) v2022.3Processor 12th Gen Intel®) Core™ i7- 12700F 2. 10 GHzGraphics Processor NVIDIA®) GeForce®) RTX 4090HIP CANISTER FILLING SYSTEM

[0063] The HIP canister filling system was built to demonstrate the encapsulation of the Idaho calcine simulant for hot isostatic pressing. As shown in Error! Reference source not found., the modularized demonstration unit has an overall dimension of 2.4 m tall xl.6 m wide x 1.0 m deep. FIG. 2 show an exemplary embodiment of the general assembly computer-aided design (CAD) model developedfor the construction of the filling system was subsequently imported into Altair EDEM® to simulate the boundary of the DEM model.

[0064] During the filling process, the powder is first discharged from the storage hopper, then channeled through a butterfly valve, followed by a powder metering process carried out by a six-cavity rotary valve. The powder flows through two 60- degree elbows and progresses via a filling nozzle and port coupling device before reaching a 10-liter container.

[0065] For better observation, the wall of the container was made of borosilicate glass, resembling a straight wall HIP canister. The process-contact surface features a 2B surface finish to minimize the powder holdup within the filling system, a standard and sanitary process equipment requirement, pursuant to ASTM A480, “Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip,” ASTM Standard. 2023. doi: 10.1520 / A0480_A0480M- 22A.

[0066] This fully automated filling process offers a unique bulk material handling and processing scenario consisting of multiple powder flow conditions, including:• Powder discharging from a hopper.• Powder flow through a butterfly valve.• Powder dispensing from a rotary valve.• Powder flow through a circular process pipeline with two 60° elbows.• Powder flow through a unique filling nozzle and port coupling system.Unassisted powder filling by gravity' into a container.

[0067] Since the powder underwent multiple flow scenarios, the simulation offered insight into the versatility of the contact model. In the current study, two operating procedures were simulated:• Scenario 1 : Standard filling operation• Scenario 2: Accidental overfill and recover}' process.

[0068] Historical data obtained from the experimental filling trials were compared with the results predicted by the DEM model to assess and validate the accuracy of the contact model.Scenario 1: Standard Filling Process

[0069] The experimental filling trial initially loaded the powder storage hopper with 8 kg of powder. After allowing dust particles to settle, the butterfly valve was activated to release the material into the rotary valve. The rotary valve was then actuated to oscillate 180° in forward and reverse directions, dispensing a set volume of powder into the container via the filling nozzle. Upon completing 20 cycles of the rotary valve (each cycle being a 2 x 180° rotation), a gas pulse compaction process was initiated. This method of powder densification uses compressed air to level the surface profile of the powder bed, enhancing the efficiency of powder encapsulation. Following this, the filling operation was halted, the container detached, and its weight was measured to ascertain the contained powder amount.

[0070] The resulting powder bed within the glass container was photographed for comparison with the DEM model. After recording the weight of the container, it was reattached to the filling nozzle, and the filling operation resumed. This sequence was carried out thrice, with the container partially filling to approximately 75% after 60 rotary valve cycles.Scenario 1: Standard Filling Process DEM Simulation

[0071] The multi -unit operation of the filling process was simulated by a full- scale three-dimensional DEM model, as illustrated in Error! Reference source not found.. The mass flow rate and exit trajectory of the powder are strongly influenced by the rotary valve's modeled size and angular velocity. The size of the rotor (such as shown in Error! Reference source not found.) was cross-referenced using a calibrated vernier against the manufacturer's drawings to ensure it is accurately represented in the model. Additionally, the angular velocity, specified as 360° per second in the manufacturer's datasheet, w as validated using a high-speed camera.

[0072] The gas pulse compaction process, a technique for pow der densification, such as described in Akiyama et al., “Densification of powders by means of air, vibratory and mechanical compactions f Powder Technol, vol. 46, no. 2-3, 1986, doi: 10.1016 / 0032-5910(86)80024-9, which is herein incorporated by references, was intentionally excluded from the simulation. This method involves an initial fluidization of the pow der through evacuation, leveraging a bubbling phenomenon to level the powder. Subsequently, the fluidized powder bed undergoes rapid densification via a burst of compressed air. resulting in an energy-efficient process for consolidating certain bulk materials.

[0073] As an alternative, the powder densification was approximated using a vibratory compaction process. It was simulated by applying a sinusoidal translational motion to the container along the vertical axis. The vibratory motion had an amplitude of 1 mm and a frequency of 50 Hz, set at 0.5-second intervals and repeated over five cycles.

[0074] A dynamic domain was implemented in the DEM model to optimize computational efficiency. This approach ensured that computing resources wereprioritized for moving particles while stationary7particles within the container were frozen to conserve computational capacity.Scenario 1: Standard Filling Process Simulation Validation

[0075] The standard filling process was modeled using over 1 million particles and required 224 hours to complete emulating 206.5 seconds of simulated time. To accurately emulate powder cohesion behavior governed by the EEPA model, the model was solved by a 10% Rayleigh time step (2 x 10'6seconds).

[0076] The valve actuation sequence, illustrated in Error! Reference source not found., was modeled according to the standard operating procedures. The model emulated the flow of particles from the powder storage hopper and proceeded through the butterfly isolation valve before entering the rotary valve. Given the weight of the total inventory, bridging was considered possible at this stage, especially since the material was pre-consolidated at the 2-inch hopper outlet. The bulk material discharged freely upon opening the isolation butterfly valve, achieving a favorable mass flow within the hopper. This behavior aligns with experimental observations.

[0077] The angular velocity and valve timing of the rotary valve were emulated in the model (Error! Reference source not found.). As the rotary valve steadily dispensed the material, there was a gradual reduction in the hopper powder level while maintaining a mass flow. This behavior is again consistent with experimental findings.

[0078] Once released by the rotary valve, the material flowed freely through the process line under gravity. Upon reaching the filling nozzle, the velocity of the particles was momentarily slowed but did not bridge. As it entered the container, it formed a powder bed exhibiting an asymmetrical surface profile, as shown in Error! Reference source not found..

[0079] Error! Reference source not found, illustrates the cumulative mass within the container, revealing that DEM predictions align closely with experimental results, with less than 1% deviation. This minor error falls within acceptable bounds, considering measurement errors and experimental variability. In this process, the quantity7of powder the container receives is controlled by the fixed amount of volume displaced by the rotary valve. Given that the cumulative masses predicted by the DEM model show good agreement with the experimental measurements, it indicates that the loose poured bulk density of the powder discharged from the hopper was accurately represented.

[0080] The simulation successfully emulated the preferential filling arising from the inclined upstream process line and valve geometry of the filling nozzle, leading to an asymmetrical surface profile, as shown in Error! Reference source not found.. The results underscore the correct representation of the powder's trajectory and interaction with the subsequent pipes.

[0081] By comparing the filled level on the front face of the container (Error! Reference source not found.), it was observed that the powder bed height predicted by the DEM model was, on average. 12% below the expected value (Table IV). It suggests that the bulk density of the emulated material in the filled state was slightly denser than expected.Table IV. Powder Bed HeightExperimental DEM Simulation Error25% Filled Level50% Filled Level 175 mm 160 mm 9%75% Filled Level 265 mm 241 mm 9%

[0082] The asymmetric surface profile of the powder bed was photographed and subsequently processed to determine the poured angle of repose, as show n in Error! Reference source not found.. The results were compared with the angle of repose emulated by the DEM model, with findings detailed in

[0083]

[0084] Table V below . The image-processed photographs of FIGS 9A, 9B and 9C highlight the surface profile formed by the powder bed when 25% filled (FIG. 9A),50% filled (FIG. 9B) and 75% filled (FIG. 9C).Table V. Poured Angle of ReposeExperimental DEM Simulation25% Filled Left: 19° Right: 32° Left: 25° Right: 30°50% Filled Left: 26° Right: 32° Left: 33° Right: 36°75% Filled Left: 28° Right: 30° Left: 33° Right: 36°

[0085] The emulated height and bulk density of the vibratory compacted material, as illustrated in Reference is made to FIG. 1, were determined using EDEM's analyst tool. Meanwhile, the bulk density of the powder densified through gas pulsing compaction was estimated from the powder bed height and the powder mass. A comparison of these results is presented in Table VI below.

[0086] The emulated vibratory bulk density (see Table VI) was found to be higher than the gas pulse compaction bulk density observed in the experiment, resulting in a lower filled level than anticipated (see Reference is made to FIG. 1).Table VI. Bulk density achieved by simulated vibratory compaction vs experimental gas pulse compactionDEM Vibratory Compaction Actual Gas Pulse compactionBulk Density7Bed Height Bulk Density725% Filled 1 .30 g / cc 95 mm 1. 14 g / cc50% Filled 1.32 g / cc 185 mm 1.17 g / cc75% Filled 1.37 g / cc 275 mm 1. 17 g / cc

[0087] Reference is made to FIG. 1A, which shows emulated 75% filled material densified by vibratory compaction, compared to FIG. 10B, showing gas pulse compacted Idaho calcine simulant. The reference line indicates 275 mm powder bed height.Scenario 2: Accidental Overfill & Recovery Process

[0088] Safety7is crucial in process developments involving radioactive materials. A Hazard and Operability7Study (HAZOP) highlighted concerns about the potential spread of radioactive contaminants due to overfilling. For this reason, several safety measures were implemented to interrupt powder flow in the event of overfilling. Additionally, provisions were made for automated excess powder removal. It ensures a seamless transition back to regular operations.

[0089] To simulate accidental overfilling, the control system was manually over-ridden to allow additional rotary valve cycles, intentionally causing an observable powder build-up through a sight glass. The presence of powder in the sight glass signaled an overfilling incident, prompting the operator to stop the rotary valve and initiate the recovery procedure.

[0090] The recovery7procedure is divided into two main phases: overfilled HIP canister removal; and transfer of excess material from the filling system to a recovery7container. Initially, the filling nozzle and port coupling device was securely closed, halting powder flow and sealing the filling nozzle and the filling port on the container. The automated conveying system then gently descended and removed the overfilled container.

[0091] Due to the unique disc-valve design of the filling nozzle and port coupling device, a small quantity of residual powder remained inside the filling port after an overfilling event (see Error! Reference source not found.). The amount of the exposed residual powder is vital for safety assessment, as it defines the upper limit of radioactive material contamination to the surroundings should the container tip over.

[0092] To precisely gauge this residual amount, the following procedure was followed. The weight of the overfilled container was first recorded. After that, the residual powder in the filling port was removed by vacuum cleaning, followed by a reweighing to determine the quantity of the residual powder.

[0093] An empty recovery container was loaded onto the automated conveying system and securely coupled with the filling nozzle. The filling nozzle was then opened, allowing the material to gravity flow into the canister. Once the powder flow had stopped, the filling nozzle was closed before removing the recovery container, marking the completion of the recovery process.Scenario 2: Accidental Overfill & Recovery Process DEM Simulation

[0094] The DEM model for simulating the accidental overfill and recovery process was developed based on the standard filling model. After the standard filling process, more particles were introduced into the powder storage hopper. Given the significant particle count in this model, various methods were applied to enhance computational efficiency. Firstly, a dynamic domain was used to freeze the particlesalready present in the container to conserve computational resources. Secondly, the rotary valve's rotor was removed, facilitating a steady flow of material rather than simulating the entire powder dosing process. This modification lets the particles “avoid” the rotary valve, shortening the overall duration of the simulation.

[0095] Once the particles had settled, excess powder above the center of the sight glass was "trimmed" by adjusting the dimensions of the model's domain. The filling nozzle was then closed, isolating the filling column and allowing the container (Error! Reference source not found. A) to be lowered.

[0096] The overfilled container was then converted into an empty recovery container by removing all the particles. It was carried out by adjusting the dimensions of the model's domain. Subsequently, the empty recovery container was raised to couple with the filling nozzle. The filling nozzle was opened to discharge the remaining material within the filling column. The simulation was completed after the residual material was fully released and settled in the recovery container (Error! Reference source not found. B).Scenario 2: Accidental Overfill & Recovery Process Simulation Validation

[0097] The simulation involved 2 million particles, which took 35 hours to complete emulating 50.5 seconds of simulated time. It continued to be solved with a 10% Rayleigh time step (2 x 10'6seconds) to ensure powder cohesion was correctly emulated. The software's analyst tools measured the predicted amount of material received by the overfilled container, the recovery container, and the residual powder within the port (FIG. 12). At the end of the simulation, the residual powder within the cleared filling column was also assessed, with results tabulated in Table VII below.

[0098] During recovery7, bridging is most likely to occur as a full column of material is consolidated within the processing pipeline. Nonetheless, similar to the hopper discharge in Scenario 1, the DEM model predicted a free-flowing stream of material discharging into the recovery container under gravity as soon as the filling nozzle was opened. This prediction is aligned with actual experimental observations

[0099] Once all the overfilled material had been released from the filling column, the DEM model predicted that most of the material holdup would be concentrated within the filling nozzle. This prediction aligns with real-world observations made during routine borescope inspections of the filling column.Table VII. Powder mass balanceExperimental DEM Simulation

[0100] In Scenario 1, the DEM model accurately predicted the mass displaced by the rotary7valve to be less than 1%. It indicates that the material's loose poured bulk density was correctly calibrated. As emulated by the DEM, the filled level was lower than anticipated. Despite utilizing six calibration methods, simulating the dynamic flow properties of the bulk materials with DEM remains challenging. Forsimplicity, certain environmental conditions that might affect the filled density of the material were not considered in the current study. Factors such as the influence of air, electrostatic charges within the bulk material, mechanical vibrations of the filling system and surface finish variations in pipelines were excluded from the DEM model. However, these factors could potentially influence the filled density of the powder.

[0101] The modeled angle of repose closely resembled the experimental outcome with an error of less than 6°. See S. Chung, A. Basu, K. Irvine, P. Wypych, D. Hastie, A. Grima and S. Moricca, “Modelling of Powder Filling of HIP Canisters (Manuscript submitted for publication),” in Hot Isostatic Pressing: HIP’22, 2022, which is incorporated herein.

[0102] It suggests an improvement over the preliminary contact model

[0018] , which predicted a steeper angle of repose and lower filled level (Error! Reference source not found.). The particle-particle friction of the preliminary contact model was deemed excessively high during the initial calibration using the Freeman FT4 flow energies and RST XS shear cell calibration models. Consequently, adjustments to the model were made by reducing the particle-particle static and rolling friction. It led to the optimized contact model parameters presented in the current study. It underscores the importance of incorporating calibration models that measure the internal friction between particles to simulate powder filling processes.

[0103] In the current study, gas pulse compaction was not modeled, and instead, the powder leveling and densification process was approximated by a vibratory compaction process. This approach provided valuable insights into the vibratory behavior of the emulated bulk material. While the vibratory behavior of the contact model was not explicitly calibrated, the emulated vibratory compacted bulk density wasfound to be, on average 1.33 g / cc, closely matching the 1.32 g / cc tapped bulk density of the Idaho calcine simulant.

[0104] The emulated vibratory compacted bulk density was 14% higher than the density achieved by gas pulse compaction. Although the data suggests gas pulse compaction might not be optimal for powder densification, this method can minimize powder segregation, vital in HIP canister filling. Vibration can lead to variations in particle size and inconsistencies in bulk density within the material. See, e.g., C. F. Harwood. “Powder segregation due to vibration,” Powder Technol, vol. 16, no. 1, pp. 51-57, Jan. 1977, doi: 10.1016 / 0032-5910(77)85020-1, which is herein incorporated by reference. Under elevated temperature and pressure in a HIP process, powder segregation can cause uneven HIP canister collapse and inhomogeneity in chemical composition, leading to inferior product quality7, as shown in Error! Reference source not found. B (compare to FIG. 14A).

[0105] In Scenario 2, the amount of powder in the overfilled container was predicted to be 4% higher than the experimental outcome, whereas it is 4% lower in the case of the recovery container. There are negligible differences (± 2 grams) in the prediction of the residual powder in the filling port and the filling column. These minor deviations are considered acceptable for preliminary engineering studies.

[0106] Powder bridging did not occur in Scenario 1 or Scenario 2 simulation. The RST XS shear cell model correctly calibrated the low cohesion, and the free-flowing properties of the Idaho calcine simulant was accurately emulated by the DEM model.

[0107] The foregoing description is presented for purposes of illustration. It is not exhaustive and is not limited to precise forms or embodiments disclosed. Modifications and adaptations of the embodiments will be apparent fromconsideration of the specification and practice of the disclosed embodiments. While certain components have been described as being coupled to one another, such components may be integrated with one another or distributed in any suitable fashion.

[0108] Moreover, while illustrative embodiments have been described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and / or alterations based on the present disclosure. The elements in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as nonexclusive. Further, the steps of the disclosed methods can be modified in any manner, including reordering steps and / or inserting or deleting steps.

[0109] The features and advantages of this disclosure are apparent from this detailed specification, and thus, it is intended that the appended claims cover all systems and methods falling within the true spirit and scope of the disclosure. As used herein, the indefinite articles "a” and “an7’ mean "one or more / ’ Similarly, the use of a plural term does not necessanly denote a plurality unless it is unambiguous in the given context. Words such as "and” or "or” mean “and / or” unless specifically directed otherwise. Further, since numerous modifications and variations will readily occur from studying the present disclosure, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure.

[0110] Throughout this application, various embodiments of the present disclosure may be presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the present disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numeric values within that range. For example, description of a range such as from 1 to 6 should be considered to include subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, and so forth, as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0111] Other embodiments will be apparent from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as example only, with a true scope and spirit of the disclosed embodiments being indicated by the following claims.

Claims

THE INVENTION CLAIMED IS:

1. A method of maximizing at least one flow property of bulk powder in a Hot Isostatic Press (HIP) canister filling system, including the steps of: in a computer system, carrying out a contact model analysis for the dynamic simulation of the flow properties of bulk powder through a multi-unit HIP canister filling system using a Discrete Element Method (DEM) to predict at least one flow property of said bulk powder; calibrating said contact model analysis using at least one variable associated with the bulk powder or the canister filling system, or both; discharging bulk powder from a storage hopper using a first valve; flowing said powder through the first valve and a second valve (Fl); flowing said powder through the second valve and into at least one process pipeline (F2); and flowing said powder through at least one process pipeline, through at least one filling nozzle (F3) and into the canister, wherein at least one parameter for discharging bulk powder from the storage hopper, or flow steps Fl, F2 or F3 is based on the predicted How property of the bulk powder.

2. The method of claim 1, wherein the contact model analysis was calibrated using at least one of the following methods: loose poured bulk density; wall shear; uniaxial compressibility'; flow energy; shear test; and hopper discharge.

3. The method according to claim 1, wherein the bulk powder includes nuclear waste, radioactive waste, or other toxic waste.

4. The method according to claim 3, wherein the nuclear waste includes calcined material from uranium ores.

5. The method according to claim 1, wherein the rate of flow is based on the at least one predicted flow property of the bulk powder selected from: the rate of discharge from the storage hopper using a first valve; the rate of flow through at least one process pipeline using a second valve; the rate of flow through at least one filling nozzle into the canister; or combinations thereof.

6. The method according to claim 5, wherein the first valve and the second valve comprises either a butterfly valve or a rotary valve.

7. The method according to claim 6. wherein the first valve comprises a butterfly valve and the second valve comprises a rotary valve.

8. The method according to claim 7, wherein the butterfly valve is actuated in an amount to adjust the flow of the bulk powder out of the storage hopper based on the at least one predicted flow property of the bulk powder.

9. The method according to claim 7, wherein the rotary valve is actuated in an amount to adjust the flow of the bulk powder based on the at least one predicted flow property of the bulk powder through the rotary valve and into the process pipeline.

10. The method according to claim 9, comprising activating the rotary valve to oscillate up to 180° in forward and reverse directions to dispense bulk powder into the canister via the filling nozzle.

11. The method according to claim 1, wherein at least one parameter for discharging bulk powder from the storage hopper, or flow steps Fl, F2 or F3 is based on a predicted material property of the bulk powder.

12. The method according to claim 11, wherein the at least one predicted material property of the bulk powder is powder packing density.

13. The method according to claim 12, further comprising at least one powder packing densification step to enhance the efficiency of powder encapsulation.

14. The method according to claim 13, wherein the at least one powder densification step is selected from a gas pulse compaction process or a vibratory compaction process.

15. The method according to claim 1, wherein the least one process pipeline comprises a circular process pipeline with two 60° elbows.

16. The method according to claim 1, wherein the filling nozzle further includes a port coupling system.

17. The method according to claim 1 , wherein said bulk powder is gravity fed into the canister.

18. The method according to claim 1, wherein the contact model analysis includes particle-particle analysis for modelling interactions with particles in the bulk powder.

19. The method according to claim 18, wherein the contact model includes Poisson Ratio. Solid Density. Shear Modulus, Particle-Particle Coefficient of Restitution, Particle-Particle Coefficient of Static Friction. Particle-Particle Coefficient of Rolling Friction of the particles located in the bulk powder.

20. The method according to claim 1, wherein the contact model analysis includes particle-boundary analysis for modelling interactions with particles in the bulk powder and at least one surface of the multiple sections of the canister filling system in which the particles come into contact.

21. The method according to claim 20, wherein the contact model includes Poisson Ratio. Solid Density. Shear Modulus, Particle-Boundary Coefficient of Restitution, Particle- Boundary Coefficient of Static Friction, Particle- Boundary Coefficient of Rolling Friction.

22. The method according to claim 1, wherein the contact model analysis includes: a particle-particle analysis for modelling interactions with particles in the bulk powder; and a particle-boundary analysis for modelling interactions with particles in the bulk powder and surfaces of the multiple sections of the canister filling system in which the particles come into contact.

23. A hot isostatic press (HIP) canister filling system, comprising: a storage hopper for storing bulk powder; a first valve configured to discharge said bulk powder from the storage hopper when activated; a second valve configured to receive said bulk powder from said first valve; a process pipeline for transporting said bulk powder discharged from said second valve to a filling nozzle; a port connecting the filling nozzle to the canister; anda computer system including: a main memory for storing computer readable code for a contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM); and at least one processor coupled to the main memory, said at least one processor executing the computer readable code in the main memory to cause the application module to carry out contact model analysis for simulating the flow properties of bulk powder using a Discrete Element Method (DEM) prior to discharging said bulk powder from the storage hopper to predict at least one flow property of said bulk powder through multiple sections of said canister filling system.

24. The hot isostatic press canister filling system according to claim 23, wherein the contact model analysis includes particle-particle analysis for modelling interactions with particles in the bulk powder.

25. The hot isostatic press canister filling system according to claim 24, wherein the contact model includes Poisson Ratio, Solid Density, Shear Modulus, Particle-Particle Coefficient of Restitution, Particle-Particle Coefficient of Static Friction, Particle-Particle Coefficient of Rolling Friction of the particles located in the bulk powder.

26. The hot isostatic press canister filling system according to claim 23, wherein the contact model analysis includes particle-boundary analysis for modelling interactions with particles in the bulk powder and at least one surface of the multiple sections of the canister filling system in which the particles come into contact.

27. The hot isostatic press canister filling system according to claim 26, wherein the contact model includes Poisson Ratio, Solid Density, Shear Modulus,Particle-Boundary Coefficient of Restitution, Particle- Boundary' Coefficient of Static Friction, Particle- Boundary Coefficient of Rolling Friction.

28. The hot isostatic press canister filling system according to claim 23, wherein the contact model analysis includes: a particle-particle analysis for modelling interactions with particles in the bulk powder; and a particle-boundary analysis for modelling interactions with particles in the bulk powder and surfaces of the multiple sections of the canister filling system in which the particles come into contact.

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