Showing papers by "Westinghouse Electric published in 2020"
TL;DR: In this article, the effect of Zr and Mn on the microstructure and first hydrogenation kinetic of TiFe alloy is reported, and the rate limiting step for each activated alloy was found to be diffusion controlled with decreasing interface velocity.
48 citations
TL;DR: In this article, the effect of air exposure on first hydrogenation kinetics of TiFe +4.5% Zr + 2.2% Mn alloy was studied and it was found that the air exposed alloy could be successfully hydrogenated after ball milling and after cold rolling with some loss in hydrogen storage capacity.
27 citations
TL;DR: In this article, the synthesis and characterization of the U3Si2 and UO2 composites sintered by spark plasma sintering (SPS) with controlled microstructures for accident-tolerant fuel application is reported.
24 citations
TL;DR: This work investigates separation of signal from noise in thermography images using several machine learning (ML) methods, including new spatial–temporal blind source separation and spatial-temporal sparse dictionary learning methods.
Abstract: Additive manufacturing (AM) of high-strength metals is currently based on the laser powder bed fusion (LPBF) process, which can introduce internal material flaws, such as pores and anisotropy. Quality control (QC) requires nondestructive evaluation of actual AM structures. Flash thermography is a potentially promising QC technique because it is scalable to arbitrary structure size. However, the detection sensitivity of this method is limited by noise. We investigate separation of signal from noise in thermography images using several machine learning (ML) methods, including new spatial–temporal blind source separation and spatial–temporal sparse dictionary learning methods. Performance of the ML methods is benchmarked using thermography data obtained from imaging stainless steel 316L and Inconel 718 specimens produced by the LPBF method with imprinted calibrated porosity defects. The ML methods are ranked by F-score and execution runtime. The ML methods with higher accuracy require a longer runtime. However, this runtime is sufficiently short to perform QC within a realistic time frame.
24 citations
TL;DR: In this article, the authors present a DfAM worksheet to help engineers, drafters, and designers select good part candidates with little prior knowledge of the specific technology, and demonstrate the worksheet process.
Abstract: In industry, Design for Additive Manufacturing (DfAM) is currently synonymous with expert knowledge and external consultants for many companies. Particularly in higher cost technologies, such as metal powder bed fusion, component design requires extensive additive manufacturing (AM) knowledge. If a part is improperly designed, then it can cause thousands of dollars of lost time and material through a failed print. To avoid this situation, specialists must be consulted throughout the printing process; however, the shortage of trained personnel familiar with AM can create a bottleneck during design. In order to help businesses identify candidate parts for Powder Bed Fusion (PBF) AM, this paper presents a DfAM worksheet to help engineers, drafters, and designers select good part candidates with little prior knowledge of the specific technology. This worksheet uses data from the literature to support the values used for design guidance. Example components are shown to demonstrate the worksheet process. Ratings of these components are then compared with expert raters’ assessments of their suitability for fabrication with PBF from a geometric standpoint. In addition to introducing the worksheet, preliminary user feedback about the worksheet is presented, and future work is discussed.
23 citations
TL;DR: In this article, the deuterium distribution in oxide layers on a series of Zr alloys, including autoclave-oxidised Zircaloy-4, Zr-1Nb and Zr2.5Nb, was characterized by high-resolution SIMS analysis, and it was shown that the development of interconnected porosity in the oxide may be the critical rate-determining mechanism that controls HPU in the aqueous corrosion of zirconium alloys in water-cooled reactors.
19 citations
TL;DR: In this paper, a detailed investigation of the interaction between UN and UO2 is provided and a formation mechanism for the resulting α-U2N3 phase is proposed, which is driven by O diffusion into the UN phase and N diffusion in the opposite direction, forming a long-range solid solution in the UO 2 matrix.
18 citations
TL;DR: In this article, the effects of Cr-doped U3Si2 composite fuels were investigated by thermogravimetric analysis, which revealed significantly improved oxidation resistance with minimal doping of 3'wt% Cr.
17 citations
07 Sep 2020
TL;DR: The capabilities of additive manufacturing (AM) enable designers to generate and build creative solutions beyond the limitations of traditional manufacturing, however, designers must also accommoda... as discussed by the authors, and they must also accommodate designers' requirements.
Abstract: The capabilities of additive manufacturing (AM) enable designers to generate and build creative solutions beyond the limitations of traditional manufacturing. However, designers must also accommoda...
17 citations
14 citations
TL;DR: In this article, a double-layer coating consisting of an active and passive part to protect Zr alloy surface against high-temperature oxidation in a hot water environment is presented.
13 Feb 2020-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the failure mechanisms of chromium-coated zirconium-alloy claddings under expected, critical loading conditions were determined and a two-dimensional fracture model was also developed for the expanding plug loading condition based on inputs determined from mechanical testing.
Abstract: Coated nuclear fuel claddings offer a promising, near-term solution to address the demand for next-generation, accident-tolerant fuel systems. It is expected that they will possess superior mechanical properties and greater oxidation resistance compared to current cladding technology, allowing for improved performance during beyond design-basis accident conditions. Here, we present a methodology to determine the failure mechanisms of chromium-coated zirconium-alloy claddings under expected, critical loading conditions. Three-dimensional digital image correlation and acoustic emission techniques were used in situ to monitor spatial strain and crack development of the claddings under two key, de-coupled loading conditions: expanding plug and four-point bending. Critical strain levels, at which cracking initiated, were determined to be 0.4% ehoop and 0.4% exx for expanding plug and four-point bending, respectively. A two-dimensional fracture model was also developed for the expanding plug loading condition based on inputs determined from mechanical testing. It was concluded that coating fracture of expanding plug specimens was axisymmetric across the specimen circumference and occurred rapidly through the thickness of the chromium coating. Subsequent high temperature steam oxidation experiments on tested (cracked) expanding plug specimens showed no signs of oxidation degradation to the underlying zirconium alloy, thereby showcasing the effectiveness of the chromium coating. This comprehensive, multi-scale study is intended to inform future testing of next-generation, coated claddings and identify the resulting failure mechanisms that arise in beyond design basis accident conditions.
TL;DR: In this article, the authors investigate thermal tomography imaging and non-destructive evaluation of stainless steel and nickel super alloy metallic structures produced with the laser powder bed fusion (LPBF) additive manufacturing (AM) process.
Abstract: Thermal tomography is a computational method for heat diffusion-based imaging of solids, which provides 3D visualization of data from flash thermography measurements. We investigate thermal tomography imaging and nondestructive evaluation of stainless steel and nickel super alloy metallic structures produced with the laser powder bed fusion (LPBF) additive manufacturing (AM) process. Metallic structures produced with LPBF contain defects, and there are limited capabilities to evaluate these structures non-destructively. Thermal tomography reconstruction of 3D apparent spatial effusivity provides information about AM structure geometry and internal material flaws. We study performance of thermal tomography in imaging of metallic structures through COMSOL computer simulations of transient heat transfer and through reconstruction of data obtained from experimental measurements. Thermal tomography reconstructions of structure shape and dimensions are shown for the Inconel 718 AM structure which has variations in the horizontal plane but is uniform along the depth dimension. Reconstruction of internal defects is investigated using a stainless steel 316L specimen with flat bottom hole (FBH) indentations, and the Inconel 718 plate is produced with the LPBF method, which contains imprinted hemispherical shape low density regions containing non-sintered metallic powder. The FBHs have the same sizes as the imprinted defects in the LPBF specimens but offer better imaging contrast. Thermal tomography reconstructions provide visualizations of internal defects and allow for estimation of their sizes and locations. Results of this study demonstrate that thermal tomography can be used for visualization and quality control in AM.
TL;DR: In this paper, the variation in thermal conductivity with Gd concentration and accommodation mechanism has been modelled by combining experimental observations on Gd doped fuel with a theoretical understanding.
TL;DR: A systematic differential economics evaluation approach was developed through the use of the Code of Accounts guidelines to assess the costs of nuclear power plants and may serve as a template to evaluate direct costs for reactors of any size and design at any stage of developments.
TL;DR: This work evaluates computational design of experiment strategies, which execute a nuclear reactor equipment system finite element model to train and verify Gaussian Process (GP) surrogate models, and the significance of the sensitivity analysis for efficient modeling and simulation of nuclear reactor stochastic dynamics is discussed.
TL;DR: In this paper, the void fraction, mixture velocity, dispersed phase (bubble or drop) characteristic lengths and volumetric interfacial area were measured at the end of heated length using sapphire optical probes and Pitot tubes placed in various radial positions of the bundle.
TL;DR: The role of interface interaction between the U3Si2 fuel and SiC cladding in their use as an advanced concept in light water reactors is discussed, demonstrating the substantial stability of this fuel-cladding system.
Abstract: Triuranium disilicide (U3Si2) fuel with silicon carbide (SiC) composite cladding is being considered as an advanced concept/accident tolerant fuel for light water reactors thus, understanding their chemical compatibility under operational and accident conditions is paramount. Here we provide a comprehensive view of the interaction between U3Si2 and SiC by utilizing density functional theory calculations supported by diffusion couple experiments. From the calculated reaction energies, we demonstrate that triuranium pentasilicide (U3Si5), uranium carbide (UC), U20Si16C3, and uranium silicide (USi) phases can form at the interface. A detailed study of U3Si2 and SiC defect formation energies of the equilibrated materials yielding the interfacial phases U20Si16C3, U3Si5 and UC reveal a thermodynamic driving force for generating defects in both fuel and cladding. The absence of either the U3Si2 or SiC phase, however, causes the defect formation energies in the other phase to be positive, removing the driving force for additional interfacial reactions. The diffusion couple experiments confirm the conclusion with demonstrated restricted formation of U3Si5, UC, and U20Si16C3/USi phases at the interface. The resulting lack of continuous interaction between the U3Si2 and SiC, reflects the diminishing driving force for defect formation, demonstrating the substantial stability of this fuel-cladding system.
TL;DR: In this article, the influence of microstructure, stress and iodine concentration on I-SCC performances has been assessed by comparison between cold-worked and recrystallised material, with fractography and incipient cracks used as evidence.
TL;DR: In this study, a state-of-the-art experimental setup using electrical heating to study certain aspects of temperature driven fracture was built, and surrogate fuel materials such as ceria (CeO2) were used to validate the system.
Abstract: Temperature gradients in ceramic light water reactor (LWR) uranium dioxide (UO2) nuclear fuel pellets generate thermal stresses that cause fractures in the fuel, which begins early in the life of fresh fuel. The combination of heating due to fission and forced convective cooling on the exterior of LWR fuel rods generates a temperature profile that is difficult to replicate outside the reactor environment. In this study, a state-of-the-art experimental setup using electrical heating to study certain aspects of temperature driven fracture was built, and surrogate fuel materials such as ceria (CeO2) were used to validate the system. Cracking experiments were conducted on these surrogates by inducing reactivity-initiated-accident like temperature gradients in the pellets via induction and direct resistance heating. Induction heating was done using copper coils and molybdenum susceptors, which heated the surrogates to a threshold temperature that is sufficiently high for the fuel material to conduct current. Thereafter, direct resistance heating was achieved by passing current through the specimen using a DC power supply to introduce volumetric heating to replicate LWR operating conditions. The pellets were held against nickel electrodes and mounted on a boron nitride test-stand. All the tests were carried out in a stainless-steel vacuum chamber. Simultaneous real-time dual imaging of the surrogate pellet surface was implemented using an optical and infrared camera system that was mounted along axial and perpendicular directions to the pellet surface, respectively. A beam-splitter was used to split the incoming radiation from the sample into two halves. While one of the beams was transmitted from the splitter through a bandpass filter to obtain optical images, the other beam was reflected from the splitter to the thermal camera to capture full-field temperature gradients of the as-fabricated pellet surface during cracking. Some initial tests were conducted with a 2-color pyrometer that was later substituted with a forward-looking infrared thermal camera to capture the temperature profiles. A LabVIEW data acquisition system was set up for collecting useful data during experiments.
TL;DR: In this article, the authors show that the fatigue lifetime of NiTi shape memory alloys intrinsically depends on a combination of two factors: the transformation volume amplitude and the number of inclusions interacting with the phase transformation domains.
TL;DR: In this article, the authors investigated the impact of IASCC on the failure of Type 347 and Type 316 stainless steel baffle-former bolt failures at 4-loop downflow PWRs in the US.
TL;DR: In this article, a single edge notch (SEN) specimen has been validated and verified for tension-compression loading and compliance solutions have been developed for a single EN specimen using IN718 forged nickel base superalloy material.
TL;DR: The steady-state and depletion analysis of the I2S-LWR core using both UO2 and U3Si2 fuel designs is described, to include the generation of HELIOS cross sections and comparison with the WEC lattice code PARAGON and the Monte Carlo code SERPENT.
TL;DR: One option increases the short circuit capacity (SCC) at the motor bus; the other uses a synchronous machine (SM) in lieu of an induction machine (IM) to make choosing the appropriate cost-effective ac machine for a given application easier.
Abstract: This article presents two alternatives to make choosing the appropriate cost-effective ac machine for a given application easier. One option increases the short circuit capacity (SCC) at the motor bus; the other uses a synchronous machine (SM) in lieu of an induction machine (IM). Both methods have the potential to yield higher-efficiency designs with better transient ridethrough capability.
TL;DR: The Westinghouse Electric Company (Westinghouse) is developing its next generation of high-capacity nuclear power plants (NPPs) based on lead fast reactor (LFR) technology.
Abstract: Westinghouse Electric Company (Westinghouse) is developing its next generation of high-capacity nuclear power plants (NPPs) based on lead fast reactor (LFR) technology: a Generation IV comp...
TL;DR: The purpose of this article is to define the CZ and present the critical components that create it and an explanation of specific brush properties and their contribution to successful commutation is included.
Abstract: DC machines have been in operation for more than 100 years. Engineers and technicians understand the dc-motor structure and components since they have experience rebuilding, testing, and making performance adjustments to them. Those that understand commutation, [2], [4] the commutation zone (CZ), and the characteristics of the carbon brush are few in number. Traditionally, the lack of a visible arc has been the defining quality of good commutation; hence, the term "black." The knowledge gap and relatively high-level physical science involved with commutation have led to an art known as "black magic" for achieving the invisible-arc condition [5], [6]. Black magic refers to both the brush coloration and commutation. The purpose of this article is to define the CZ and present the critical components that create it. An explanation of specific brush properties and their contribution to successful commutation is included.
TL;DR: In this paper, the impact of nuclear data uncertainties based on ENDF/B-VII was quantified on lattice level using the generalized perturbation theory implemented with the Monte Carlo code Serpent and the deterministic code PERSENT of the Argonne Reactor Computational suite.
Abstract: In this study, the Best Estimate Plus Uncertainty (BEPU) approach is developed for the systematic quantification and propagation of uncertainties in the modelling and simulation of lead-cooled fast reactors (LFRs) and applied to the demonstration LFR (DLFR) initially investigated by Westinghouse. The impact of nuclear data uncertainties based on ENDF/B-VII.0 covariances is quantified on lattice level using the generalized perturbation theory implemented with the Monte Carlo code Serpent and the deterministic code PERSENT of the Argonne Reactor Computational (ARC) suite. The quantities of interest are the main eigenvalue and selected reactivity coefficients such as Doppler, radial expansion, and fuel/clad/coolant density coefficients. These uncertainties are then propagated through safety analysis, carried out using the MiniSAS code, following the stochastic sampling approach in DAKOTA. An unprotected transient overpower (UTOP) scenario is considered to assess the effect of input uncertainties on safety parameters such as peak fuel and clad temperatures. It is found that in steady state, the multiplication factor shows the most sensitivity to perturbations in 235U fission, 235U ν, and 238U capture cross sections. The uncertainties of 239Pu and 238U capture cross sections become more significant as the fuel is irradiated. The covariance of various reactivity feedback coefficients is constructed by tracing back to common uncertainty contributors (i.e., nuclide-reaction pairs), including 238U inelastic, 238U capture, and 239Pu capture cross sections. It is also observed that nuclear data uncertainty propagates to uncertainty on peak clad and fuel temperatures of 28.5 K and 70.0 K, respectively. Such uncertainties do not impose per se threat to the integrity of the fuel rod; however, they sum to other sources of uncertainties in verifying the compliance of the assumed safety margins, suggesting the developed BEPU method necessary to provide one of the required insights on the impact of uncertainties on core safety characteristics.
TL;DR: In this article, the impact of fission products (FPs) on the stability and performance of U3Si2 was investigated by doped with individual FPs to explore U-Si-FP interactions and phase equilibria that may impact the performance of the ATF during irradiation.
TL;DR: Fauske & Associates, LLC (FAI), Argonne National Laboratory (ANL), and Westinghouse Electric Company are collaborating within the program "Development of an Integrated Mechanistic Source Term Asses".
Abstract: Fauske & Associates, LLC (FAI), Argonne National Laboratory (ANL), and Westinghouse Electric Company are collaborating within the program “Development of an Integrated Mechanistic Source Term Asses...