Deposition of Iter Vacuum Vessel Dust Inside the Pressure Suppression System During a Loss of Coolant Accident: Experimental and Numerical Analyses

2021 ◽  
Author(s):  
Miriam Ibba ◽  
Alessio Pesetti ◽  
Michele Raucci ◽  
Flavio Parozzi ◽  
Roberta Lazzeri ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Numerical Analyses ◽  
Water Tank ◽  
Vacuum Vessel ◽  
Dust Deposition ◽  
Dust Mass ◽  
Water Container ◽  
Dust Distribution ◽  
Experimental Rig ◽  
Suppression System

Abstract This paper deals with an experimental and numerical analysis of the deposition of ITER dust simulant inside a reduced scale Vacuum Vessel Pressure Suppression System (VVPSS) of the International Thermonuclear Experimental Reactor (ITER). This research, funded by the ITER Organization, aims to analyse the dust deposition in a water container relevant for the ITER VVPSS, the dust removal by means of robotised apparatuses and their decontamination efficiency. The experimental rig, built at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa (Italy), is described and the results of a preliminary experimental test are illustrated, underlining that 2 and 82% of dust mass was strongly and lightly bound to the water container surfaces, respectively, and 16 % were not deposited in the water tank. Furthermore, three numerical analyses were carried out implementing a model of the experimental rig in the Enel Code for Analysis of Radionuclide Transport (ECART) to determine the relevance of different parameters on the deposition, resuspension and removal of dust. The numerical simulations allowed to specify dust mass deposition on the different rig components, revealing a strong dust retention (about 66%) in the first part of the injection piping in case of coarse granulometry. Finest lognormal dust distribution was instead able to reach the water container (about 90%). Moreover, the numerical simulations permitted to define more precisely the test matrix and to analyse the experimental results.

Experimental Study of Steam Pressure Suppression by Condensation in a Water Tank at Sub-Atmospheric Pressure

2016 ◽  
Author(s):  
Dahmane Mazed ◽  
Rosa Lo Frano ◽  
Donato Aquaro ◽  
Daniele Del Serra ◽  
Igor Sekachev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
High Efficiency ◽  
Saturation Pressure ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Water Tank ◽  
Vacuum Vessel ◽  
Steam Condensation ◽  
Suppression System

The Vacuum Vessel Pressure Suppression System (VVPSS), a key safety system of the ITER plant, is designed to protect the Vacuum Vessel (VV) from over pressure occurring in the case of LOCA (Loss Of Coolant Accident) or other pressurizing accidents such as LOVA (Loss Of Vacuum Accident). The steam condensation in the Suppression Tanks (main elements of the VVPSS system), occurs at sub-atmospheric pressure. The steam condensation, at pressures equal or greater than the atmospheric, has been numerically analyzed and experimentally investigated in the past in order to optimize the design of the pressure suppression system of boiling water nuclear reactors. However, very limited experimental data is available concerning the steam condensation in a water tank at sub-atmospheric pressure. In order to analyze the steam condensation in these operating conditions, an experimental study, funded by ITER Organization, is conducted at the Department of Civil and Industrial Engineering (DICI) of University of Pisa. The tests analyze the condensation of saturated or superheated steam at sub-atmospheric pressures (4.2 kPa and slightly above the water vapour saturation pressure), and pool temperature up to 50°C at several heights of water head. The experimental facility, to perform this study, has been set up with a significant scaling factor regarding the full size installation at ITER. In this paper the experimental rig, the conditions of the experiments, and the test matrix are presented. The temperature and pressure measurements with details of the data acquisition system are described. The tests were performed at different patterns of the sparger exit holes (1, 3 and 9) and for three steam mass flow rates per one hole. The results show very high efficiency of condensation for all examined conditions. Finally, a comparison between the condensation regimen at sub-atmospheric and at atmospheric pressure is discussed.

scholarly journals Numerical simulations of dust fluxes to the eastern Qinghai-Tibetan Plateau: Comparison of model results with a Holocene peat record of dust deposition

2013 ◽  
Vol 118 (10) ◽  
pp. 4597-4609 ◽  
Author(s):  
Marion Ferrat ◽  
Baerbel Langmann ◽  
Xuefeng Cui ◽  
Jefferson Gomes ◽  
Dominik J. Weiss
Keyword(s):  
Tibetan Plateau ◽  
Numerical Simulations ◽  
Dust Deposition

Large scale experimental facility for performance assessment of the vacuum vessel pressure suppression system of ITER

2021 ◽  
Vol 171 ◽  
pp. 112523
Author(s):  
A. Pesetti ◽  
A. Marini ◽  
M. Raucci ◽  
G. Giambartolomei ◽  
M. Olcese ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Large Scale ◽  
Vacuum Vessel ◽  
Experimental Facility ◽  
Suppression System

scholarly journals Dust emission size distribution impact on aerosol budget and radiative forcing over the Mediterranean region: a regional climate model approach

2012 ◽  
Vol 12 (21) ◽  
pp. 10545-10567 ◽  
Author(s):  
P. Nabat ◽  
F. Solmon ◽  
M. Mallet ◽  
J. F. Kok ◽  
S. Somot
Keyword(s):  
Size Distribution ◽  
Radiative Forcing ◽  
Mediterranean Basin ◽  
Climate Model ◽  
Regional Climate ◽  
Dust Emission ◽  
Dust Deposition ◽  
The Mediterranean ◽  
Dust Distribution ◽  
The Mediterranean Basin

Abstract. The present study investigates the dust emission and load over the Mediterranean basin using the coupled chemistry–aerosol–regional climate model RegCM-4. The first step of this work focuses on dust particle emission size distribution modeling. We compare a parameterization in which the emission is based on the individual kinetic energy of the aggregates striking the surface to a recent parameterization based on an analogy with the fragmentation of brittle materials. The main difference between the two dust schemes concerns the mass proportion of fine aerosol that is reduced in the case of the new dust parameterization, with consequences for optical properties. At the episodic scale, comparisons between RegCM-4 simulations, satellite and ground-based data show a clear improvement using the new dust distribution in terms of aerosol optical depth (AOD) values and geographic gradients. These results are confirmed at the seasonal scale for the investigated year 2008. This change of dust distribution has sensitive impacts on the simulated regional dust budget, notably dry dust deposition and the regional direct aerosol radiative forcing over the Mediterranean basin. In particular, we find that the new size distribution produces a higher dust deposition flux, and smaller top of atmosphere (TOA) dust radiative cooling. A multi-annual simulation is finally carried out using the new dust distribution over the period 2000–2009. The average SW radiative forcing over the Mediterranean Sea reaches −13.6 W m−2 at the surface, and −5.5 W m−2 at TOA. The LW radiative forcing is positive over the basin: 1.7 W m−2 on average over the Mediterranean Sea at the surface, and 0.6 W m−2 at TOA.

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

2011 ◽  
Vol 51 (5) ◽  
pp. 053017 ◽  
Author(s):  
C. Bellecci ◽  
P. Gaudio ◽  
I. Lupelli ◽  
A. Malizia ◽  
M.T. Porfiri ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Vacuum Vessel ◽  
Experimental Campaign ◽  
Dust Resuspension

Remote handling strategy and prototype tooling of the ITER vacuum vessel pressure suppression system bleed line valve assembly and rupture disk assembly

2020 ◽  
Vol 153 ◽  
pp. 111485
Author(s):  
Keelan Keogh ◽  
Chang-Hwan Choi ◽  
David Cooper ◽  
Steven Craig ◽  
David Hamilton ◽  
...  
Keyword(s):  
Vacuum Vessel ◽  
Remote Handling ◽  
Rupture Disk ◽  
Valve Assembly ◽  
Suppression System

Stress-Deformation State in the Rock Massif (Illustrated with the Example of Macedonia)

2015 ◽  
Vol 725-726 ◽  
pp. 214-219 ◽  
Author(s):  
Zlatko Zafirovski ◽  
Nikolay Vatin
Keyword(s):  
Geotechnical Properties ◽  
Rock Massif ◽  
Numerical Analyses ◽  
Water Tank ◽  
Surge Tank ◽  
Secondary Stress ◽  
Stability Analyses ◽  
Deformation State ◽  
Stress Deformation ◽  
The Stability

Main goal of this article is to introduce an used methodology of analyses for excavation of surge tank enlargement of HEC MATKA1. The way of combining of the methods for analyses of discontinual and continual media are explained. The main information’s about existing geological and geotechnical properties are also given, as a basis for analytical and numerical analyses. Some of the results from the stability analyses of structural controlled instabilities during excavation of water tank are presented. The newly secondary stress – deformation state as a result from enlargement (excavation) is analysed with program Z-SOIL.

scholarly journals Twelve thousand years of dust: the Holocene global dust cycle constrained by natural archives

2014 ◽  
Vol 10 (6) ◽  
pp. 4277-4363 ◽  
Author(s):  
S. Albani ◽  
N. M. Mahowald ◽  
G. Winckler ◽  
R. F. Anderson ◽  
L. I. Bradtmiller ◽  
...  
Keyword(s):  
North Atlantic ◽  
Accumulation Rates ◽  
Dust Deposition ◽  
The Holocene ◽  
The North ◽  
Dust Mass ◽  
The North Atlantic ◽  
Mass Accumulation Rates ◽  
Mass Accumulation ◽  
Natural Archives

Abstract. Mineral dust plays an important role in the climate system by interacting with radiation, clouds, and biogeochemical cycles. In addition, natural archives show that the dust cycle experienced variability in the past in response to global and local climate change. The compilation of the DIRTMAP paleodust datasets in the last two decades provided a target for paleoclimate models that include the dust cycle, following a time slice approach. We propose an innovative framework to organize a paleodust dataset that moves on from the positive experience of DIRTMAP and takes into account new scientific challenges, by providing a concise and accessible dataset of temporally resolved records of dust mass accumulation rates and particle grain-size distributions. We consider data from ice cores, marine sediments, loess/paleosol sequences, lake sediments, and peat bogs for this compilation, with a temporal focus on the Holocene period. This global compilation allows investigation of the potential, uncertainties and confidence level of dust mass accumulation rates reconstructions, and highlights the importance of dust particle size information for accurate and quantitative reconstructions of the dust cycle. After applying criteria that help to establish that the data considered represent changes in dust deposition, 43 paleodust records have been identified, with the highest density of dust deposition data occurring in the North Atlantic region. Although the temporal evolution of dust in the North Atlantic appears consistent across several cores and suggest that minimum dust fluxes are likely observed during the Early to mid-Holocene period (6000–8000 years ago), the magnitude of dust fluxes in these observations is not fully consistent, suggesting that more work needs to be done to synthesize datasets for the Holocene. Based on the data compilation, we used the Community Earth System Model to estimate the mass balance and variability of the global dust cycle during the Holocene, with dust load ranging from 17.1 to 20.5 Tg between 2000 and 10 000 years ago, and a minimum in the Early to Mid-Holocene (6000–8000 years ago).

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