Experimental Study of Boiling in Porous Media

2013 ◽  
Author(s):  
Paul Sapin ◽  
Paul Duru ◽  
Florian Fichot ◽  
Marc Prat ◽  
Michel Quintard
Keyword(s):  
Porous Media ◽  
Test Section ◽  
Cooling System ◽  
Macroscopic Model ◽  
Experimental Setup ◽  
Pore Scale ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Temperature Detector ◽  
Thermal Measurements

Following a long-lasting failure in the cooling system of a pressurized water reactor (PWR), the superheated core can be efficiently cooled down by reflooding. The macroscopic model used at the French Institute of Radioprotection and Nuclear Safety (IRSN) to simulate this process is based on strong assumptions on the microscopic flow patterns. This paper describes the experimental setup designed for the study of boiling in porous media with the emphasis on various pore-scale boiling regimes. The final experimental setup is a two-dimensional porous medium made of 392 cylinders randomly placed between two ceramic plates. Each heating cylinder is a RTD probe (Resistance Temperature Detector), that can give thermal measurements in every point of the test section as well as heat generation. This paper presents preliminary results: pool boiling is characterized for a single cylinder mounted in the test section and reflooding of a line of 9 cylinders is observed.

Sensitivity Study of LOCA-Generated Debris on the Pressure Drop of Fuel Assembly

2017 ◽  
Author(s):  
Hammad Aslam Bhatti ◽  
Zhangpeng Guo ◽  
Weiqian Zhuo ◽  
Shahroze Ahmed ◽  
Da Wang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Fuel Assembly ◽  
Cooling System ◽  
Safety Issue ◽  
Cooling Water ◽  
Sensitivity Study ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Loss Of Coolant Accident ◽  
Core Cooling

The coolant of emergency core cooling system (ECCS), for long-term core cooling (LTCC), comes from the containment sump under the loss-of-coolant accident (LOCA). In the event of LOCA, within the containment of the pressurized water reactor (PWR), thermal insulation of piping and other materials in the vicinity of the break could be dislodged. A fraction of these dislodged insulation and other materials would be transported to the floor of the containment by coolant. Some of these debris might get through strainer and eventually accumulate over the suction sump screens of the emergency core cooling systems (ECCS). So, these debris like fibrous glass, fibrous wool, chemical precipitates and other particles cause pressure drop across the sump screen to increase, affecting the cooling water recirculation. As to address this safety issue, the downstream effect tests were performed over full-scale mock up fuel assembly. Sensitivity studies on pressure drop through LOCA-generated debris, deposited on fuel assembly, were performed to evaluate the effects of debris type and flowrate. Fibrous debris is the most crucial material in terms of causing pressure drop, with fibrous wool (FW) debris being more efficacious than fibrous glass (FG) debris.

Modelling Pressurized Water Reactor cores in terms of porous media

2009 ◽  
Vol 25 (1) ◽  
pp. 112-133 ◽  
Author(s):  
G. Ricciardi ◽  
S. Bellizzi ◽  
B. Collard ◽  
B. Cochelin
Keyword(s):  
Porous Media ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Reactor Cores

PKL Tests on Heterogeneous Inherent Boron Dilution Following SB-LOCA: Applicability to Reactor Scale

2010 ◽  
Author(s):  
Klaus Umminger ◽  
Simon Philipp Schollenberger ◽  
Se´bastien Cornille ◽  
Claire Agnoux ◽  
Delphine Quintin ◽  
...  
Keyword(s):  
Cooling System ◽  
Natural Circulation ◽  
Limited Range ◽  
Test Facility ◽  
Test Results ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
The Core ◽  
Physical Phenomena ◽  
Boron Dilution

In the course of a small break LOCA in a Pressurized Water Reactor (PWR) the flow regime in the Reactor Cooling System (RCS) passes through a number of different phases and the filling level may decrease down to the point where the decay heat is transferred to the secondary side under Reflux-Condenser (RC) conditions. During RC, the steam formed in the core condensates in the Steam Generator (SG) U-tubes. For a limited range of break size and configuration, a continuous accumulation of condensate may cause the formation of boron-depleted slugs. If natural circulation reestablishes, as the RCS is refilled, boron-depleted slugs might be transported to the Reactor Pressure Vessel (RPV) and to the core. To draw conclusions on the risk of boron dilution processes in SB-LOCA transients, two important issues, the limitation of slug size and the onset of Natural Circulation (NC) have to be assessed on the basis of experimental data, as system Thermal-Hydraulic codes are limited in their capability to replicate the complex physical phenomena involved. The OECD PKL III tests were performed at AREVA’s PKL test facility in Erlangen, Germany, to evaluate important phases of the boron dilution transient in PWRs. Several integral and separate effect tests were conducted, addressing the inherent boron dilution issue. The PKL III integral transient test runs provide sufficient data to state major conclusions on the formation and maximum possible size of the boron-depleted slugs, their boron concentration and their transport into the RPV with the restart of NC. Some of these conclusions can be applied to reactor scale. It has to be mentioned, that even though this paper is based on PKL test results obtained within the OECD PKL project, the conclusions of this paper reflect the views of the authors and not necessarily of all the members of the OECD PKL project.

scholarly journals Macroscopic Model for Passive Mass Dispersion in Porous Media Including Knudsen and Diffusive Slip Effects

2021 ◽  
Vol 3 ◽  
Author(s):  
Francisco J. Valdés-Parada ◽  
Didier Lasseux
Keyword(s):  
Boundary Condition ◽  
Porous Media ◽  
Mass Transport ◽  
Gas Flow ◽  
Macroscopic Model ◽  
Type Model ◽  
Pore Scale ◽  
Advective Transport ◽  
Apparent Permeability ◽  
Slip Effects

In this work, a macroscopic model for incompressible and Newtonian gas flow coupled to Fickian and advective transport of a passive solute in rigid and homogeneous porous media is derived. At the pore-scale, both momentum and mass transport phenomena are coupled, not only by the convective mechanism in the mass transport equation, but also in the solid-fluid interfacial boundary condition. This boundary condition is a generalization of the Kramers-Kistemaker slip condition that includes the Knudsen effects. The resulting upscaled model, applicable in the bulk of the porous medium, corresponds to: 1) A Darcy-type model that involves an apparent permeability tensor, complemented by a dispersive term and 2) A macroscopic convection-dispersion equation for the solute, in which both the macroscopic velocity and the total dispersion tensor are influenced by the slip effects taking place at the pore-scale. The use of the model is restricted by the starting assumptions imposed in the governing equations at the pore scale and by the (spatial and temporal) constraints involved in the upscaling process. The different regimes of application of the model, in terms of the Péclet number values, are discussed as well as its extents and limitations. This new model generalizes previous attempts that only include either Knudsen or diffusive slip effects in porous media.

Structure Design of Pressure Equipment for Experimental Test on Steam Condensation on the Cold Surface

2012 ◽  
Author(s):  
Lin Yang ◽  
Lingyun Li ◽  
Liyong Han
Keyword(s):  
Cooling System ◽  
Heat Removal ◽  
Structure Design ◽  
Pressurized Water Reactor ◽  
Steam Condensation ◽  
Thermal Measurement ◽  
Cold Surface ◽  
Pressurized Water ◽  
University Of Wisconsin ◽  
Passive Safety System

The advanced pressurized water reactor (APWR) designed by Westinghouse uses a passive safety system which relies on heat removal by condensation to maintain the containment within the design limits of pressure and temperature. Steam condensation inside surface of the containment is one of the most important phenomena during heat removing process in the passive containment cooling system (PCCS). It is very significant for engineering design and code development to study the mechanism of steam condensation on cold surface. There was an experiment done by University of Wisconsin on this subject. However, the pressure equipment cannot support high pressure. In this paper, new pressure equipment was designed. It can support higher pressure and also meet other thermal measurement requirements.

Large Scale Pressurized Water Reactor Passive Containment Cooling System Wind Tunnel Test

2019 ◽  
Vol 5 (3) ◽  
Author(s):  
Huang Jingyu ◽  
Pan Xinxin ◽  
Song Chunjing
Keyword(s):  
Wind Tunnel ◽  
Large Scale ◽  
Cooling System ◽  
Air Flow ◽  
Wind Tunnel Test ◽  
Pressurized Water Reactor ◽  
Scaled Model ◽  
Pressurized Water ◽  
Water Reactor ◽  
Wind Speeds

The objective of the current work is to shed light on studying the air flow features of the air path which is part of the passive containment cooling system (PCS) in a pressurized water reactor design. A wind tunnel test using a 1:100 scaled model is established to study the characteristic called “wind-neutrality” of the air flow in the air path, which indicates that the environmental wind should not be beneficial or detrimental to the air flow for containment cooling. Test results show that the pressure distribution in the air path is uniform, and wind speeds, wind angles, and surroundings have little effect on air flow uniformity. These investigations show that it is possible to understand air flows in the air path of PCS with a scale wind tunnel test.

scholarly journals An improved macroscale model for gas slip flow in porous media

2016 ◽  
Vol 805 ◽  
pp. 118-146 ◽  
Author(s):  
Didier Lasseux ◽  
Francisco J. Valdés Parada ◽  
Mark L. Porter
Keyword(s):  
Porous Media ◽  
Knudsen Number ◽  
Slip Flow ◽  
Permeability Tensor ◽  
Flow In Porous Media ◽  
Macroscopic Model ◽  
Nonlinear Dependence ◽  
Pore Scale ◽  
First Order ◽  
Apparent Slip

We report on a refined macroscopic model for slightly compressible gas slip flow in porous media developed by upscaling the pore-scale boundary value problem. The macroscopic model is validated by comparisons with an analytic solution on a two-dimensional (2-D) ordered model structure and with direct numerical simulations on random microscale structures. The symmetry properties of the apparent slip-corrected permeability tensor in the macroscale momentum equation are analysed. Slip correction at the macroscopic scale is more accurately described if an expansion in the Knudsen number, beyond the first order considered so far, is employed at the closure level. Corrective terms beyond the first order are a signature of the curvature of solid–fluid interfaces at the pore scale that is incompletely captured by the classical first-order correction at the macroscale. With this expansion, the apparent slip-corrected permeability is shown to be the sum of the classical intrinsic permeability tensor and tensorial slip corrections at the successive orders of the Knudsen number. All the tensorial effective coefficients can be determined from intrinsic and coupled but easy-to-solve closure problems. It is further shown that the complete form of the slip boundary condition at the microscale must be considered and an important general feature of this slip condition at the different orders in the Knudsen number is highlighted. It justifies the importance of slip-flow correction terms beyond the first order in the Knudsen number in the macroscopic model and sheds more light on the physics of slip flow in the general case, especially for large porosity values. Nevertheless, this new nonlinear dependence of the apparent permeability with the Knudsen number should be further verified experimentally.

Structure Design of the Pressured Vessel in Experimental Test on Steam Condensation on the Cold Surface for CAP1400

2014 ◽  
Author(s):  
Lin Yang ◽  
Liyong Han
Keyword(s):  
Experimental Test ◽  
Cooling System ◽  
Heat Removal ◽  
Structure Design ◽  
Natural Phenomena ◽  
Pressurized Water Reactor ◽  
Steam Condensation ◽  
Cold Surface ◽  
Pressurized Water ◽  
Passive Safety System

The advanced pressurized water reactor (APWR) uses a passive safety system relying on heat removal by condensation to maintain the containment within the design limits of pressure and temperature. The passive containment cooling system (PCCS) includes many natural phenomena mechanisms. Steam condensation is one of the most important phenomena. It is very significant for engineering designing and code developing to study the mechanism of steam condensation on cold surface. In this paper, the test pressurized vessel in the experimental test on steam condensation on the cold surface for CAP1400 is designed, and the structure pressure is calculated.

Tightness Analysis of Pressured Equipment in Experimental Test on Steam Condensation on the Cold Surface

2013 ◽  
Author(s):  
Lin Yang ◽  
Liyong Han
Keyword(s):  
Experimental Test ◽  
Cooling System ◽  
Passive Safety ◽  
Natural Phenomena ◽  
Pressurized Water Reactor ◽  
Steam Condensation ◽  
Cold Surface ◽  
Pressurized Water ◽  
University Of Wisconsin ◽  
Passive Safety System

To maintain the containment within the design limits of pressure and temperature, the advanced pressurized water reactor (APWR) designed by Westinghouse uses a passive safety system to transfer the heat from inner containment to outside. The passive containment cooling system (PCCS) includes many natural phenomena mechanisms. Steam condensation is one of the most important phenomena. Most heat is removed by steam condensation on inside surface of the containment during the postulated design basic accidents (DBA). It is very significant for engineering designing and code developing to study the mechanism of steam condensation on cold surface. There was an experiment made by University of Wisconsin on it. In this paper, the structure pressure of the pressured equipment is calculated and the tightness is also analyzed.

Low Boron Level Loading Pattern

2008 ◽  
Author(s):  
Cenk Gu¨ler ◽  
Jeffery A. Brown
Keyword(s):  
Fuel Cycle ◽  
Cooling System ◽  
Pressurized Water Reactor ◽  
High Concentration ◽  
Reactor Plant ◽  
Pressurized Water ◽  
Tritium Production ◽  
Loading Pattern ◽  
Burnable Absorber ◽  
Level Loading

A new core loading pattern scheme has been developed with the objective of significantly reducing both the maximum and cycle average RCS (Reactor Cooling System) soluble boron requirements for a typical PWR (Pressurized Water Reactor) plant with 18 month cycle. This strategy has several advantages including reduced operational costs due to boron addition and subsequent dilution, less challenging coolant chemistry adjustments and decreased tritium production over the cycles. The core design utilizes a typical Westinghouse 4-Loop core with assemblies containing both ZrB2 Integral Fuel burnable Absorber (IFBA) and high concentration Gadolinium (Gd) burnable absorbers (BAs) in the same assembly. This combination achieves the boron reduction objectives while still maintaining good power margins and good fuel cycle economics. This paper describes the major characteristics of these cycles and compares these to a reference cycle design typical of those used in current Westinghouse 4-Loop type plants.

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