Strengthening Model of Particle Deposits for Tube Support Plate Flow Blockage in Steam Generators
| Autor: | Prusek, T., Moleiro, Edgar, Oukacine, F., Adobes, A., Jaeger, Marc, Grandotto, Marc |
|---|---|
| Přispěvatelé: | Fluid Dynamics, Power Generation and Environment, EDF (EDF), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Département Etude des Réacteurs (DER), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Jaeger, Marc |
| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
[PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn]
[SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering Nuclear Power Plant [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment [PHYS.PHYS.PHYS-COMP-PH] Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph] [SPI.FLUID] Engineering Sciences [physics]/Reactive fluid environment [PHYS.PHYS.PHYS-FLU-DYN] Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn] [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph] [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering [INFO.INFO-MO] Computer Science [cs]/Modeling and Simulation [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] Steam generators Fouling mechanisms |
| Zdroj: | Nuclear Plant Chemistry Conference (NPC-2012) Nuclear Plant Chemistry Conference (NPC-2012), Sep 2012, Paris, France |
| Popis: | International audience; Corrosion product deposits in the secondary side of nuclear power plant Steam Generators may result in Tube Support Plate flow blockage, and tube fouling. Tube fouling is a deposit on the tube surfaces which is penalizing for the heat exchanges between the primary and the secondary circuits. Tube Support Plate flow blockage is a deposit at the inlet of Tube Support Plate flow holes which can induce high velocity zones and transverse velocities in the secondary flow, then flow induced vibrations and tube cracks in some cases. Indeed three significant primary to secondary leaks occurred at one nuclear plant in France between 2004 and 2006. The thermal-hydraulic and vibration studies confirmed a cracking mechanism caused by flow induced vibrations resulting in a circumferential crack. Those studies pointed out the role of an important flow blockage distribution at the upper Tube Support Plate as an aggravating factor.In order to simulate those two phenomena in the whole Steam Generator, a solid deposit growth model on the sec- ondary side of Steam Generators has been developed by the EDF R&D Division. This model is implemented in the frame of THYC, which is the EDF’s reference code for the modelling of two-phase thermal-hydraulic phenomena at the subchannel scale. A subchannel scale is a mesoscale which has the advantage to calculate thermal-hydraulic flows and deposition in whole nuclear components with reasonable CPU times. The deposit model aims to predict the localization and the growth rate of deposits in order to simulate tube fouling as well as Tube Support Plate flow blockage at this scale. This work specifically describes the efforts performed by the EDF R&D Division to develop and implement models for Tube Support Plate flow blockage.A new deposit process, based on Tube Support Plate flow blockage studies, has been developed and implemented in the model, and is presented in this work. It can be defined by two main steps : particle deposition, and strengthening process called “flashing” due to soluble species precipitation in the pores of the particle deposit. This process is calibrated on blockage rates observed in Steam Generators by using an inverse method also developed in this work. The relevance of this process is tested by comparing the simulation results to the actual levels of flow blockage observed in some nuclear plants. Two dominant trends are showed in this work : the flow blockage is more important on the hot leg than on the cold leg and at the top than at the bottom of Steam Generators. Moreover the flow blockage distribution at the upper Tube Support Plate has the special feature to be more important at the periphery than at the center. These results are in agreement with observed data in some nuclear plants.A sensitivity analysis of soluble species solubility, and more specifically magnetite solubility, has been performed. The “flashing” phenomenon allows one to underline the magnetite solubility dependence of flow blockage phenomenon. A reduction of magnetite solubility in Steam Generators seems to be an interesting remedy for reducing the Tube Support Plate flow blockage phenomenon, and more specifically for Tube Support Plates at the top of Steam Generators. Ac- cording to the deposit process developed in this work, this reduction would be more effective in cold leg than in hot leg. In practice, such a magnetite solubility reduction could be obtained by increasing the pH of the secondary circuit. This pH elevation is one of the remedy considered at short term on EDF fleet for its potential benefit on both tube fouling and Tube Support Plate flow blockage. Indeed the operational pH of secondary circuits were planned to raise at certain nuclear plants. This remedy is in agreement with the results obtained in this work. |
| Databáze: | OpenAIRE |
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