Effect of Containment Vessel’s Size Scale on the Aerosol Spray Scavenging Efficiency With Water Mist

2020 ◽  
Author(s):  
Hui Liang ◽  
Qian Zhou ◽  
Nejdet Erkan ◽  
Shunichi Suzuki ◽  
Yohan Leblois ◽  
...  
Keyword(s):  
Collection Efficiency ◽  
Removal Rate ◽  
Aerosol Particles ◽  
Water Mist ◽  
Radioactive Aerosol ◽  
Internal Diameter ◽  
Size Scale ◽  
Spray System ◽  
Aerosol Spray ◽  
Scavenging Efficiency

Abstract In the foreseen decommissioning and debris removal plans of the damaged Fukushima Daiichi reactors, the fuel debris will be broken into small pieces using laser or mechanical cutting techniques prior to removing them from the reactor buildings. Regardless of the technique to be employed, submicron radioactive aerosol particles will be generated and dispersed in the gas space of primary containment vessel during cutting operations. The water spray system has been proven to be an applicable method in removing aerosol particles. However, it cannot remove Greenfield-gap aerosol particles (with diameters between 0.1–1 μm) so effectively. To solve this problem, a new agglomeration method by addition of water mist before spray injection was developed. With preexisting water mist, aerosol particles were expected to aggregate with water mist and form larger-sized agglomerated aerosol-mist particles, which increased the effect of inertial impaction mechanism leading to higher scavenging efficiency. The new method has been verified to be capable of improving the spray scavenging efficiency for the Greenfield gap particles by conducting aerosol scavenging experiments without and with mist in the newly built UTARTS facility in the University of Tokyo. The experiment results showed that the aerosol removal rate increased along with the increasing of mist concentration level. To verify the new agglomeration method in different experiment facilities and to investigate the effects of vessel’s size scale on aerosol collection efficiency, similar experiments were repeated in the TOSQAN facility of IRSN, France. Though the cylindrical vessel in two facilities have same internal diameter, the vessel’s height of TOSQAN facility is 4.8 m, which is larger than the one in the UTARTS facility (2.5 m). The experiment results in TOSQAN facility also showed that water mist has potential to improve aerosol spray scavenging efficiency. The corresponding numerical simulations about aerosol removal by spray droplets without mist in both UTARTS and TOSQAN facilities were conducted to better understand the aerosol removal process, including time evolution of aerosol mass fraction and flow field of the gas phase.

Effect of Containment Vessel\u2019s Size Scale on the Aerosol Spray Scavenging Efficiency With Water Mist

2021 ◽  
Author(s):  
Hui Liang ◽  
Qian Zhou ◽  
Nejdet Erkan ◽  
Shunichi Suzuki ◽  
Yohan Leblois ◽  
...  
Keyword(s):  
Water Mist ◽  
Size Scale ◽  
Containment Vessel ◽  
Aerosol Spray ◽  
Scavenging Efficiency

Effect of vessel size scale on the aerosol spray scavenging efficiency with water mist

2021 ◽  
pp. 105853
Author(s):  
Hui Liang ◽  
Nejdet Erkan ◽  
Qian Zhou ◽  
Emmanuel Porcheron ◽  
Thomas Gelain ◽  
...  
Keyword(s):  
Water Mist ◽  
Vessel Size ◽  
Size Scale ◽  
Aerosol Spray ◽  
Scavenging Efficiency

Improvement of aerosol spray scavenging efficiency with water mist

2020 ◽  
pp. 105697
Author(s):  
Hui Liang ◽  
Qian Zhou ◽  
Nejdet Erkan ◽  
Shunichi Suzuki
Keyword(s):  
Water Mist ◽  
Aerosol Spray ◽  
Scavenging Efficiency

Study of Aerosol Scavenging by Rain in Case of a Radioactive Contamination of the Atmosphere

2012 ◽  
Author(s):  
Arnaud Quérel ◽  
Pascal Lemaitre ◽  
Marie Monier ◽  
Emmanuel Porcheron ◽  
Andrea Flossmann
Keyword(s):  
Experimental Study ◽  
Atmospheric Aerosols ◽  
Chernobyl Accident ◽  
Aerosol Particles ◽  
Radioactive Aerosol ◽  
Single Drop ◽  
Modelling Studies ◽  
Aerosol Scavenging ◽  
Scavenging Efficiency ◽  
The Impact

The analysis of the radioactive aerosol scavenging by rain after the Chernobyl accident highlights some differences between the modelling studies and the environmental measurements. Part of this gap is due to the uncertainties on the scavenging efficiency of aerosol particles by raindrops, in particular for drops with a diameter larger than one millimeter. The IRSN (Institut de Radioprotection et de Sûreté Nucléaire) has decided to launch an experimental study to measure with a better accuracy the scavenging efficiency of large raindrops. The scavenging efficiency of aerosol has been determined by measuring precisely the mass of aerosol particles collected by a single drop after its path through an atmosphere loaded with particles. The collection efficiencies for drop diameters of 2 mm and 2.6 mm (previously unknown for atmospheric aerosols) are measured. The impact of these new data on modeling of the washout of the atmosphere by the rain is noticed.

scholarly journals Bio-inspired Fog Harvesting Materials: Basic Research and Bionic Potential Applications

2021 ◽  
Vol 18 (3) ◽  
pp. 501-533
Author(s):  
Kui Wan ◽  
Xuelian Gou ◽  
Zhiguang Guo
Keyword(s):  
Collection Efficiency ◽  
Basic Research ◽  
Development Trend ◽  
Water Mist ◽  
Long Distance ◽  
Biological Water ◽  
Water Collection ◽  
Transmission Area ◽  
Potential Applications ◽  
Water Transmission

AbstractWith the explosive growth of the world’s population and the rapid increase in industrial water consumption, the world’s water supply has fallen into crisis. The shortage of fresh water resources has become a global problem, especially in arid regions. In nature, many organisms can collect water from foggy water under harsh conditions, which provides us with inspiration for the development of new functional fog harvesting materials. A large number of bionic special wettable synthetic surfaces are synthesized for water mist collection. In this review, we introduce some water collection phenomena in nature, outline the basic theories of biological water harvesting, and summarize six mechanisms of biological water collection: increased surface wettability, increased water transmission area, long-distance water delivery, water accumulation and storage, condensation promotion, and gravity-driven. Then, the water collection mechanisms of three typical organisms and their synthesis are discussed. And their function, water collection efficiency, new developments in their biomimetic materials are narrated, which are cactus, spider and desert beetles. The study of multiple bionics was inspired by the discovery of Nepenthes’ moist and smooth peristome. The excellent characteristics of a variety of biological water collection structures, combined with each other, are far superior to other single synthetic surfaces. Furthermore, the main problems in the preparation and application of biomimetic fog harvesting materials and the future development trend of materials fog harvesting are prospected.

scholarly journals Influence of a Surface Finishing Method on Light Collection Behaviour of PWO Scintillator Crystals

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 47 ◽  
Author(s):  
Daniele Rinaldi ◽  
Luigi Montalto ◽  
Michel Lebeau ◽  
Paolo Mengucci
Keyword(s):  
High Energy Physics ◽  
Collection Efficiency ◽  
Removal Rate ◽  
Light Yield ◽  
Grazing Incidence ◽  
Structural Condition ◽  
High Energy ◽  
Production Performance ◽  
Surface Finishing ◽  
Light Collection

In the field of scintillators, high scintillation and light production performance require high-quality crystals. Although the composition and structure of crystals are fundamental in this direction, their ultimate optical performance is strongly dependent on the surface finishing treatment. This paper compares two surface finishing methods in terms of the final structural condition of the surface and the relative light yield performances. The first polishing method is the conventional “Mechanical Diamond Polishing” (MDP) technique. The second polishing technique is a method applied in the electronics industry which is envisaged for finishing the surface treatment of scintillator crystals. This method, named “Chemical Mechanical Polishing” (CMP), is efficient in terms of the cost and material removal rate and is expected to produce low perturbed surface layers, with a possible improvement of the internal reflectivity and, in turn, the light collection efficiency. The two methods have been applied to a lead tungstate PbWO4 (PWO) single crystal due to the wide diffusion of this material in high energy physics (CERN, PANDA project) and diagnostic medical applications. The light yield (LY) values of both the MDP and CMP treated crystals were measured by using the facilities at CERN while their surface structure was investigated by Scanning Electron Microscopy (SEM) and Grazing Incidence X-ray Diffraction (GID). We present here the corresponding optical results and their relationship with the processing conditions and subsurface structure.

scholarly journals Numerical Simulation of Decontamination of Airborne Fission Products during In-Vessel Release Phase by Containment Spray

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Khurram Mehboob
Keyword(s):  
Droplet Size ◽  
Failure Time ◽  
Ph Value ◽  
Removal Rate ◽  
Droplet Diameter ◽  
Fission Products ◽  
Product Release ◽  
Spray System ◽  
Spray Solution ◽  
Proposed Model

The containment spray system (CSS) has a significant role in limiting the risk of radioactive exposure to the environment. In this work, the optimal droplet size and pH value of spray water to prevent the fission product release have been evaluated to improve the performance of the spray system during in-vessel release phase. A semikinetic model has been developed and implemented in MATLAB. The sensitivity and removal rate of airborne isotopes with the spray system have been simulated versus the spray activation and failure time, droplet size, and pH value. The alkaline (Na2S2O3) spray solution and spray water with pH 9.5 have similar scrubbing properties for iodine. However, the removal rate from the CSS has been found to be an approximately inverse square of droplet diameter (1/d2) for Na2S2O3 and higher pH of spray water. The numerical results showed that 450 μm–850 μm droplet with 9.5 pH and higher or the alkaline (Na2S2O3) solution with 0.2 m3/s–0.35 m3/s flow rate is optimal for effective scrubbing of in-containment fission products. The proposed model has been validated with TOSQAN experimental data.

Development of a Simplified Model for Aerosol Removal by Spray System of Containment

2020 ◽  
Author(s):  
Yu Huiyu ◽  
Gu Haifeng ◽  
Chen Junyan ◽  
Sun Zhongning
Keyword(s):  
Gas Flow ◽  
Present Model ◽  
Removal Rate ◽  
Reactor Core ◽  
Severe Accident ◽  
Experimental Result ◽  
Simplified Model ◽  
Full Coverage ◽  
Spray System ◽  
Coverage Model

Abstract The containment spray system is of great importance for the nuclear power plant to reduce the pressure and temperature, as well as concentration of radioactive aerosols released from reactor core under the severe accident. The main aim of present study is to develop a simplified model for aerosol removal by spray system, the model is employed to predict the variation of aerosol concentration in containment and reveal the key mechanism influencing aerosol removal. In the present model, the air flow entrained by spraying droplet is considered which is computed by solving simplified one-dimension momentum equations rather than the standard N-S equation. For the validation of the model, a small size sprinkle experiment facility is built. The facility is equipped with non-intrusive instruments such as particle size spectrometer for aerosol spectrum measurement, HELOS/R for measuring the droplet spectrum. The result of aerosol removal of the present model is compared with the result of the full coverage model and the experimental result. In the experiment, polydisperse aerosol is used and the removal rate of aerosols with different sizes is compared against the result of the present model and the full coverage model. The velocity of entrained gas flow and the distribution of droplets are displayed. The computational result reveals the aerosol removal constant distribution along the height.

scholarly journals Experimental evidence of the rear capture of aerosol particles by raindrops

2017 ◽  
Vol 17 (6) ◽  
pp. 4159-4176 ◽  
Author(s):  
Pascal Lemaitre ◽  
Arnaud Querel ◽  
Marie Monier ◽  
Thibault Menard ◽  
Emmanuel Porcheron ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Size Range ◽  
Collection Efficiency ◽  
Aerosol Particles ◽  
Experimental Studies ◽  
Laboratory Measurements ◽  
Experimental Proof ◽  
Theoretical Approaches ◽  
Capture Mechanism ◽  
Mode Size

Abstract. This article presents new measurements of the efficiency with which aerosol particles of accumulation mode size are collected by a 1.25 mm sized raindrop. These laboratory measurements provide the link to reconcile the scavenging coefficients obtained from theoretical approaches with those from experimental studies. We provide here experimental proof of the rear capture mechanism in the flow around drops, which has a fundamental effect on submicroscopic particles. These experiments thus confirm the efficiencies theoretically simulated by Beard (1974). Finally, we propose a semi-analytical expression to take into account this essential mechanism to calculate the collection efficiency for drops within the rain size range.

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