STARDUST experimental campaign and numerical simulations: influence of obstacles and temperature on dust resuspension in a vacuum vessel under LOVA

We present the results of an experimental campaign conducted on the LULI2000 laser facility. Semi-infinite targets of a commercial grade of porous graphite were submitted to high-power laser irradiation inorder to generate craters. A 15 ns pulse duration was used along with a focal spot diameter of 900 µm to deliver energies up to 750 J. Numerical simulations of these shots have been performed following a specificmethodology which can be divided in three steps. Firstly, the mechanical loading induced by the laser iscalibrated by simulating the same shot on a thin aluminum target of which free surface velocity is measured byPDV and line-VISAR. Secondly, the same shot is performed on a thin graphite target to validate the materialmodel of graphite. Thirdly, the craterization shot on semi-infinite target is simulated. Numerical results arecompared to experimental measurements of craters obtained using an interferometric profilometer.

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Evaluation of the Performance of a Sirocco Fan Driven by a Diesel Engine in Mist Sprayer Applications

Volume 4: Cycle Innovations; Fans and Blowers; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Oil and Gas Applications ◽

10.1115/gt2011-45539 ◽

2011 ◽

Author(s):

Roberto Bettocchi ◽

Mirko Morini ◽

Michele Pinelli

Keyword(s):

Diesel Engine ◽

Numerical Simulations ◽

Electric Motor ◽

Rotational Speed ◽

A Priori ◽

Integrated System ◽

Pressure Drops ◽

Experimental Campaign ◽

Sirocco Fan ◽

Correct Design

The coupling of a sirocco fan, used to supply air to a mist sprayer, and a Diesel engine is studied in order to enhance the performance of the integrated system. In this case, the main problem for the correct design of the fan arises from the fact that it is not possible to define a priori the operating point. In fact, the rotational speed is not fixed as in the case of an electric motor driven fan, but is determined as an equilibrium of the power supplied by the engine and the power absorbed by the fan to recover the pressure drops of the mist sprayer system. In this paper, the experimental campaign performed to characterize the existent fans is presented. Moreover, the sprayer duct is characterized by using literature correlations and by performing numerical simulations. Then, the collected data are elaborated in order to scale the fans in order to enhance the performance of the system.

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The effect of train composition on the running safety of low-flatcar wagons in braking and curving manoeuvres

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409716636923 ◽

2016 ◽

Vol 231 (6) ◽

pp. 666-677 ◽

Cited By ~ 3

Author(s):

Egidio Di Gialleonardo ◽

Gabriele Cazzulani ◽

Stefano Melzi ◽

Francesco Braghin

Keyword(s):

Numerical Simulations ◽

Dynamic Behaviour ◽

Good Alternative ◽

Critical Conditions ◽

Railway Vehicle ◽

Freight Train ◽

Running Safety ◽

Experimental Campaign ◽

Important Impact ◽

Truck Transportation

Low-flatcar wagons represent a good alternative to freight truck transportation. In fact, the whole truck can be easily loaded on these wagons. However, due to the railway vehicle gauge, these vehicles present a particular design with an important impact on the dynamics of the trainset and on its derailment risk. The present work aims at analysing the dynamic behaviour of the trainset and the influence of the freight train composition on the derailment risk. Numerical simulations have been performed to identify the most critical conditions. Then, an experimental campaign has been carried out to evaluate the derailment risk associated to these conditions.

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Long Term Neutron Activation in JET DD Operation

EPJ Web of Conferences ◽

10.1051/epjconf/202125303005 ◽

2021 ◽

Vol 253 ◽

pp. 03005

Author(s):

Andrej Žohar ◽

Igor Lengar ◽

Paola Batistoni ◽

Sean Conroy ◽

Aljaž Čufar ◽

...

Keyword(s):

Computational Analysis ◽

Gamma Ray ◽

Irradiation Time ◽

Neutron Energy Spectrum ◽

Vacuum Vessel ◽

Experimental Campaign ◽

Fusion Neutrons ◽

Measured Activity ◽

Good Agreement

In the 2019 C38 Deuterium-Deuterium campaign at JET several different ITER-relevant materials and dosimetry foils were irradiated in a specially designed long-term irradiation station located inside the vacuum vessel with the purpose of testing the activation of ITER materials by fusion neutrons. The samples were exposed to a neutron fluence of 1.9E14 n/cm2 during JET discharges performed in the experimental campaign over a period of 5 months. Gamma ray spectroscopy measurements were performed on irradiated samples to determine the activation of different long-lived isotopes in the samples. Monte Carlo computational analysis was performed to support the experiment by using the measured neutron yield and irradiation time. In this paper we focus on the computational analysis of the dosimetry foils that are used in order to measure the local neutron energy spectrum and flux. The foils were chosen to cover different neutron energies: thus Yttrium and some of the Nickel and Cobalt reactions were used to determine the Deuterium-Tritium fusion fraction, while Scandium and Iron and some of the Nickel and Cobalt reactions were used for comparison of the computed activity with the experimental measurements. The obtained C/E values show a reasonably good agreement between calculated and measured activity, thus validating the computational methodology and providing the basis for the analysis of the ITER-relevant materials and future experiments performed at JET in the Deuterium-Tritium campaign.

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Safety Analysis in Large Volume Vacuum Systems Like Tokamak: Experiments and Numerical Simulation to Analyze Vacuum Ruptures Consequences

Advances in Materials Science and Engineering ◽

10.1155/2014/201831 ◽

2014 ◽

Vol 2014 ◽

pp. 1-29 ◽

Cited By ~ 11

Author(s):

A. Malizia ◽

I. Lupelli ◽

M. Richetta ◽

M. Gelfusa ◽

C. Bellecci ◽

...

Keyword(s):

Numerical Simulation ◽

Numerical Model ◽

Large Volume ◽

Safety Issue ◽

Numerical Code ◽

Vacuum Vessel ◽

Experimental Facility ◽

Industrial Operations ◽

Dust Resuspension ◽

Vacuum Systems

The large volume vacuum systems are used in many industrial operations and research laboratories. Accidents in these systems should have a relevant economical and safety impact. A loss of vacuum accident (LOVA) due to a failure of the main vacuum vessel can result in a fast pressurization of the vessel and consequent mobilization dispersion of hazardous internal material through the braches. It is clear that the influence of flow fields, consequence of accidents like LOVA, on dust resuspension is a key safety issue. In order to develop this analysis an experimental facility is been developed: STARDUST. This last facility has been used to improve the knowledge about LOVA to replicate a condition more similar to appropriate operative condition like to kamaks. By the experimental data the boundary conditions have been extrapolated to give the proper input for the 2D thermofluid-dynamics numerical simulations, developed by the commercial CFD numerical code. The benchmark of numerical simulation results with the experimental ones has been used to validate and tune the 2D thermofluid-dynamics numerical model that has been developed by the authors to replicate the LOVA conditions inside STARDUST. In present work, the facility, materials, numerical model, and relevant results will be presented.

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Numerical Simulations with RELAP5-3D and RELAP5/mod3.3 of the Second Experimental Campaign on In-Box LOCA Transients for HCLL TBS

Energies ◽

10.3390/en14154544 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4544

Author(s):

Alessandro Venturini ◽

Marco Utili ◽

and Nicola Forgione

Keyword(s):

Experimental Data ◽

Wave Propagation ◽

Literature Review ◽

Numerical Simulations ◽

Thermophysical Properties ◽

Pressure Wave ◽

Experimental Results ◽

Experimental Campaign ◽

Maximum Value ◽

Lead Bismuth Eutectic

In-box LOCA was identified as one of the worst accidental scenarios for the HCLL TBS (Helium Cooled Lithium-Lead Test Blanket System). Aiming to experimentally analyze the consequences of this transient, ENEA designed and built THALLIUM (Test HAmmer in Lead LIthiUM), a facility that reproduces the LiPb loop of the HCLL TBS. Two experimental campaigns were carried out by simulating the rupture of a stiffening plate and the related helium injection in the LiPb loop. The obtained experimental data were used to check the capabilities of RELAP5 system code to reproduce the pressure wave propagation that follows this accident. The first simulations were made with RELAP5-3D using LBE (Lead–Bismuth Eutectic) as a system fluid, as the thermophysical properties of LiPb are tabulated only up to a maximum value of 40 bar in this version of the code. Then, LiPb properties were implemented in RELAP5/mod3.3, after selecting the proper correlations from a literature review. This work summarizes the numerical simulations of the second experimental campaign, which was simulated with both versions of the code. The simulations highlight that the code is able to accurately reproduce the experimental results and that RELAP5-3D is slightly more precise than RELAP5/mod3.3 in predicting the pressure trends.

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Implementation of a Particle Resuspension Model in a CFD Code: Application to an Air Ingress Scenario in a Vacuum Toroidal Vessel

Volume 1: Beyond Design Basis; Codes and Standards; Computational Fluid Dynamics (CFD); Decontamination and Decommissioning; Nuclear Fuel and Engineering; Nuclear Plant Engineering ◽

10.1115/icone2020-16139 ◽

2020 ◽

Author(s):

Thomas Gelain ◽

Laurent Ricciardi ◽

François Gensdarmes

Keyword(s):

Initial Pressure ◽

Dust Particles ◽

Vacuum Vessel ◽

Particle Resuspension ◽

Ansys Cfx ◽

Constant Friction ◽

Airborne Concentration ◽

Airborne Contamination ◽

Dust Resuspension ◽

Air Ingress

Abstract During a loss of vacuum accident (LOVA), dust particles that will be present in the future tokamak ITER are likely to be resuspended, inducing a risk for explosion and airborne contamination. Evaluating the particle resuspension/deposition and resulting airborne concentration in case of a LOVA is therefore a major issue and it can be investigated by using a CFD code. To this end, this article presents the implementation of a resuspension model in a CFD code (ANSYS CFX) and its application to an air ingress in a vacuum toroidal vessel with a volume comparable to ITER one. In the first part of the article, the Rock’n Roll model and its operational version with the Biasi’s correlation is presented. The second part of the article will be devoted to the implementation of the Rock’n’Roll model in ANSYS CFX for constant friction velocities and its adaptation to non-constant friction velocities. Finally, the paper presents the simulations obtained on the particle resuspension for an air ingress scenario in a large vacuum vessel. This case is particularly interesting and non-intuitive because as the initial pressure is reduced, the particle behavior is different from that at atmospheric pressure. Further, a competition between airflow forces and gravitational force occurs, due to the low pressure environment, potentially restricting the resuspension, and the pressure influence also has to be taken into account in the particle transport and deposition (Nerisson, 2011). Three particle diameters were studied allowing to show the evolution of the resuspension with this parameter and to calculate dust resuspension rates and airborne fractions during the air ingress.

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Numerical Simulation of TIG Welding Distortions: Distortions of a Mock-Up Representative of ITER Vacuum Vessel

ASME 2011 Pressure Vessels and Piping Conference: Volume 6, Parts A and B ◽

10.1115/pvp2011-57579 ◽

2011 ◽

Author(s):

Denis Pont ◽

Mathieu Tisset ◽

Fre´de´ric Boitout ◽

Philippe Gilles

Keyword(s):

Numerical Simulation ◽

Residual Stress ◽

Numerical Simulations ◽

Nuclear Industry ◽

Local Fields ◽

Design Stage ◽

Strong Impact ◽

Vacuum Vessel ◽

Welding Simulation ◽

Welding Sequence

Welding problems encountered in the nuclear industry have been mainly addressed by weldability tests and the analysis, development of new techniques or improvements through lesson learning. Since a decade, AREVA is developing a complementary approach based on numerical simulation. Residual stresses present in reactors do not constitute a major problem at the design stage; even though they may have a strong impact on some types of damage. Numerical welding simulation in the nuclear industry has focused mainly on residual stress prediction, which constitutes an issue for engineering. PWR components are usually massive; nevertheless distortion may also be a source of concern in component design: some structures are slender in spite of their thickness; narrow gap welding requires a close control of the groove width. AREVA, also working on a fast breeder project, the distortion problem gains in importance. In this prospect, AREVA, world energy expert, paid special attention on the numerical simulation of Gas Tungsten Arc Welding (GTAW) of a mock-up relative to the International Thermonuclear Experimental Reactor (ITER) Vacuum Vessel (VV). One of the challenges of manufacturing the ITER vacuum vessel is the low value of acceptance level of distortion (∼ 10 mm) compared to the global dimensions of the structure (∼ 10 m). Welding simulations of a representative mock-up of VV pattern of the made of austenitic steel plates (316L(N) ITER GRADE) are carried out. The aim of the numerical simulations is to check the quality of the distortion prediction. Multi pass welding simulation reproduces the deposit of each bead by thermo-metallurgical and mechanical calculations. Distortions induced by each weld are computed using a simplified approach (local global method). This method aims at modeling long and numerous welding operations with an acceptable calculation time. Moreover, this method is improved in order to respect welding sequence with partial filling of grooves. After welding sequences, distortions are measured at some representative points of the mock-up. The paper presents the methodology of the numerical simulations and the relevant results: • Residual stress and strain fields in and near the welds (local fields), • Distortion prediction for the global structure. The comparison with experimental distortions shows that the trends of the experimental deformed shape are well represented by the simulations. Moreover, displacement magnitudes are in good agreement with measurements.

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Protection of the DIII-D Vessel, Diagnostics and Windows from Microwaves Injected by the ECH/ECCD System

EPJ Web of Conferences ◽

10.1051/epjconf/201920302006 ◽

2019 ◽

Vol 203 ◽

pp. 02006 ◽

Cited By ~ 1

Author(s):

Mirela Cengher ◽

John Lohr ◽

Yuri Gorelov ◽

Antonio Torrezan ◽

Dan Ponce ◽

...

Keyword(s):

Magnetic Field ◽

Visible Light ◽

Current Drive ◽

Vacuum Vessel ◽

Rf Power ◽

Langmuir Probes ◽

Protective Measures ◽

Experimental Campaign ◽

Overdense Plasma ◽

Reflected Power

The ECH/ECCD system on DIII-D benefits from protective measures set in place in order to reduce the likelihood of refracted rf power potentially reaching sensitive areas of the vacuum vessel or diagnostics. In addition to installation of shutters and valves, a density interlock prevents the rf injection into overdense plasma. Visible light cameras, light detectors, Langmuir probes and reflected power sniffers complete the array of diagnostics used for EC protection. Besides the 110 GHz gyrotron, a new higher frequency gyrotron at 117.5 GHz was added to the system during the 2018 experimental campaign. The new frequency allows for operation at higher plasma density and with better current drive efficiency at higher magnetic field than for 110 GHz. Injection in O-mode was used in some of the high density plasmas where the X-mode is refracted.

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