Deflections of Plates in Research Reactor Fuel by Disparities in Thicknesses of Flow Channels

2019 ◽  
Author(s):  
C. Bojanowski ◽  
G. L. Solbrekken ◽  
G. H. Schnieders ◽  
J. D. Rivers ◽  
E. H. Wilson ◽  
...  
Keyword(s):  
Fuel Element ◽  
Computational Models ◽  
Research Reactor ◽  
Mechanical Performance ◽  
Plate Thickness ◽  
Flow Channels ◽  
Test Loop ◽  
Enriched Uranium ◽  
The Impact ◽  
Plate Deflection

Abstract Low-enriched uranium (LEU) fuel element designs for the U.S. high performance research reactors LEU conversion cores have been optimized by each reactor facility to allow the reactors to meet mission, operational, and safety basis requirements using monolithic uranium-molybdenum fuel. As a part of work supporting the Preliminary Safety Analysis Report (PSAR) submitted to the NRC by the University of Missouri Research Reactor (MURR), the impact of thinner 1.12 mm LEU curved fuel plates, compared to the currently used highly-enriched uranium (HEU) curved plate thickness of 1.27 mm, has been assessed for hydro-mechanical performance. Plate deflection can be induced by the hydrodynamic pressure differential caused by differences in the thicknesses of surrounding coolant flow channels. An experimental study was conducted on relevant Materials Test Reactor-type (MTR-type) reactor plate geometries in a water flow test loop to validate computational models simulating flow-induced plate deflection. Three-dimensional fluid-structure interaction (FSI) simulations of the experiments were performed using several commercially available multi-physics simulation codes. Inclusion of as-built geometry of the plates and channels in the simulations was key to achieving good agreement with measured deflections. The validated computational methodology was applied to a model of the prototypic MURR LEU plate. For the nominal flow conditions, a small deflection of the plate on the order of 5 micrometers was predicted. That deflection is significantly less than the allowances in the PSAR for change in coolant channel thickness. The experimental model validation of plate deflection is important since conventional figures of merit for the robustness of MTR-type fuel plates under flow, such as the Miller critical velocity, often show a weak correlation with the prediction of stability. Subsequent to this work, irradiation qualification of the MURR LEU fuel element design has begun and will conclude with a full-size demonstration element test.

scholarly journals Braided composite stent for peripheral vascular applications

2020 ◽  
Vol 9 (1) ◽  
pp. 1137-1146
Author(s):  
Qingli Zheng ◽  
Pengfei Dong ◽  
Zhiqiang Li ◽  
Ying Lv ◽  
Meiwen An ◽  
...  
Keyword(s):  
Computational Models ◽  
Surface Coverage ◽  
Mechanical Performance ◽  
Wire Diameter ◽  
Orthogonal Experimental Design ◽  
Braided Composite ◽  
Nitinol Wire ◽  
Radial Strength ◽  
Braiding Angle ◽  
The Impact

AbstractBraided composite stent (BCS), woven with nitinol wires and polyethylene terephthalate (PET) strips, provides a hybrid design of stent. The mechanical performance of this novel stent has not been fully investigated yet. In this work, the influence of five main design factors (number of nitinol wires, braiding angle, diameter of nitinol wire, thickness and stiffness of the PET strip) on the surface coverage, radial strength, and flexibility of the BCS were systematically studied using computational models. The orthogonal experimental design was adopted to quantitatively analyze the sensitivity of multiple factors using the minimal number of study cases. Results have shown that the nitinol wire diameter and the braiding angle are two most important factors determining the mechanical performance of the BCS. A larger nitinol wire diameter led to a larger radial strength and less flexibility of the BCS. A larger braiding angle could provide a larger radial strength and better flexibility. In addition, the impact of the braiding angle decreased when the stent underwent a large deformation. At the same time, the impact of the PET strips increased due to the interaction with nitinol wires. Moreover, the number of PET strips played an important role in the surface coverage. This study could help understand the mechanical performance of BCS stent and provides guidance on the optimal design of the stent targeting less complications.

Design of U3Si2-Al Plate-Type Fuel Element for China Advanced Research Reactor

2010 ◽  
Author(s):  
Aimin Zhang ◽  
Yalun Kang
Keyword(s):  
Fuel Element ◽  
Neutron Flux ◽  
Research Reactor ◽  
High Heat ◽  
Reactor Power ◽  
High Heat Flux ◽  
Water Tank ◽  
Enriched Uranium ◽  
Fuel Elements ◽  
Plate Type

China Advanced Research Reactor (CARR), which will be critical in China Institute of Atomic Energy (CIAE) in 2010, is a multipurpose, high neutron flux and tank-type (inverse neutron trap) reactor with compact core. Its nominal reactor power is 60MW and the maximum thermal neutron flux is about 8.0×1014n/cm2·s in heavy water tank. It has a cylindrical core having a diameter of about 450mm and a height of 850mm. The CARR’s core consists of seventeen plate-type standard fuel elements and four follower fuel elements, initially loaded with 10.97 kg of 235U. The fuel element has been designed with U3S2-Al dispersion containing 235U of (19.75±0.20)wt.% low enriched uranium (LEU) and having a density of 4.3gU/cm3. The aluminum alloy is used as the cladding. There are twenty-one and seventeen fuel plates in the standard and follower fuel element, respectively. There are specific requirements for design of the fuel element and strict limitation for the operation parameters due to the high heat flux and high velocity of coolant in CARR. Irradiation test of fuel element had been carried out at fuel element power of 3.1±20%MW at Russia MIR reactor. Average burnup of fuel element is up to 40%. This paper deals with the detailed design of fuel element for CARR, out-pile and in-pile test projects, including selection of fuel and structure material, description of element structure, miniplates and fuel element irradiation experiment, measurement of properties of fuel plate, fabrication of fuel element and test results.

scholarly journals Startup, transition core, and molybdenum-99 production upgrade analyses for low-enriched uranium fuel conversion at the University of Missouri research reactor

2020 ◽  
Author(s):  
◽  
Wilson Cowherd
Keyword(s):  
Low Power ◽  
Research Reactor ◽  
The United States ◽  
Fuel Conversion ◽  
Reactor Physics ◽  
University Of Missouri ◽  
Safety Margins ◽  
Enriched Uranium ◽  
The University ◽  
The Impact

Under the direction of the United States Department of Energy (DOE) National Nuclear Security Administration (NNSA) Office of Material Management and Minimization (M3) Reactor Conversion Program, the University of Missouri Research Reactor (MURR®) plans to convert from highly enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Low power physics startup test predictions, transition core planning, and analysis for a proposed fission-based molybdenum-99 production upgrade were done in support of LEU fuel conversion. As a first step to LEU fuel conversion, low-power physics tests will be performed to calculate reactor physics parameters. These parameters include flux distributions, coefficients of reactivity, and critical assembly measurements. To facilitate this test, reactor physics calculations were performed using MCNP5 to predict the values of these parameters. Implications of these predictions and areas of uncertainty in the prediction analysis are also discussed. Once MURR completes the testing of the initial LEU core, MURR will enter into a series of transition cycles until steady-state mixed-burnup operation is reached. A Python program was developed that incorporated the constraints of MURR operation while minimizing the time MURR will have to operate atypically during the transition cycles. The impacts of the transition cycles on experiment performance are reported, as well as the number of fuel elements needed. Finally, preliminary analysis on a proposed molybdenum-99 production device at MURR was performed. This analysis shows the impact on the reactor power distribution with implications to predicted safety margins as a part of the larger scope of the experiment analysis.

scholarly journals Development and experimental benchmarking of numeric fluid structure interaction models for research reactor fuel analysis

2015 ◽  
Author(s):  
◽  
John Charles Kennedy
Keyword(s):  
High Velocity ◽  
Plate Thickness ◽  
Fluid Structure Interaction ◽  
Quality Data ◽  
Flow Rates ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Manufacturing Tolerances ◽  
Enriched Uranium ◽  
Plate Deflection

As part of the Global Threat Reduction Initiative (GTRI) reactor conversion program, five U.S. High Performance Research Reactors (HPRRs) are currently studying a novel Low Enriched Uranium (LEU) foil based fuel to replace their current High Enriched Uranium (HEU) dispersion fuel. The proposed fuel uses a monolithic U-10Mo foil meat clad in aluminum, whereas the current HEU fuel meat is comprised of Uranium dispersed in an aluminum matrix, before being clad in aluminum. Along with a change in the physical structure of the fuel, the fuel plate thickness has been significantly decreased. Given that these fuel plates are subject to high velocity coolant flow, these changes in the plate design have led to a need to characterize the structural response of the plates in presence of high velocity flow. The proposed method for completing this analysis is to use novel fluid-structure interaction (FSI) simulations. These simulations are carried out using commercial CFD and FEA solvers Star-CCM+ and Abaqus, and iteratively coupling their solutions together at the interface between the plate and the fluid. Given the unique nature of these simulations, it is necessary to first benchmark and qualify the codes for this analysis. To generate benchmark quality data, a flow loop and test section have been constructed for studying plate deflection and channel pressure drop under a variety of fluid flow conditions. Similar experimental analysis which considered equally sized fluid channels has been studied by a number of individuals in the past. The work presented here differs however, by intentionally offsetting the plate and creating fluid channels of different thickness. This offset effectively simulates manufacturing tolerances of a real fuel assembly. A method for generating 'As-Built' numeric models of the experiment geometry is presented. These As-Built numeric models have been shown to dramatically improve matching between experiment and numeric solutions, particularly at low- to mid-range flow rates. At higher flow rates, the experiment exhibited a dynamic 'snap' behavior that could not be replicated numerically. Additional interrogation of the boundary conditions revealed a possible explanation for this snap, however numeric methods do not yet exist for recreating this behavior. In earlier works which considered equally sized channels, plate deflection was not examined in detail and was found to be largely unpredictable and reliant upon the manufacturing tolerances of the experiment. In the numeric and experimental work presented here, plate deflection behavior at low to mid-range flow rates is qualitatively consistent with theoretical expectations.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

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