Flow accelerated corrosion study in feeder pipes
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P. Goyal
Abstract
The Indian Pressurized Heavy Water Reactor (PHWR) core consists of a number of horizontal channels containing nuclear fuel bundles. Parallel coolant channels are connected to Inlet and Outlet header through feeder pipes. Coolant from Reactor Inlet Header is distributed to the coolant channels and after removing heat combines at Reactor Outlet Header. Due to space constraints the feeder pipes are joined to the channel with one or two elbows close to the end fittings of the coolant channels. The carbon steel feeder pipes carry high temperature fluid at higher velocity and are liable to undergo Flow Accelerated Corrosion (FAC). In the recent inspection it has been found that feeders having double elbow are more susceptible to FAC on the intrados of second elbow. But it was found that in some of the elbows maximum thinning due to FAC was observed on the intrados of the first elbow. Hence to resolve this, effect of first bend orientation with respect of upstream direction has been studied. Two different approaches are used for predicting the FAC rate from calculated value of wall shear stress by CFD. One method is based on evaluating of wear rate using Colburn analogy and the other using an empirical equation between wear rate and shear stress. In Colburn analogy, mass transfer coefficient is evaluated by knowing shear stress and equilibrium concentration. For a case study, wall shear stress obtained from k-∊ turbulence model was compared with k-ω SST turbulence model and no appreciable change in the wall shear stress has been found. Hence for subsequent analysis k-∊ turbulence model was chosen because large mesh size near to the surface (first layer thickness) is permitted due to higher y+ value.
Kurzfassung
Der Kern indischer Druckwasserreaktoren (mit schwerem Wasser als Moderator) besteht aus einer Vielzahl horizontaler Kanäle. Das Kühlmittel wird durch parallele Kühlmittelkanäle geführt und in einem Eintrittssammler und einem Austrittssammler zusammengeführt. Diese Zuführungen erfolgen nicht durch gerade Rohre, sondern sind aus Platzgründen in Rohrleitungen mit Krümmern ausgeführt. Dies führt bei hohen Temperaturen und hohen Geschwindigkeiten zum Auftreten von strömungsinduzierter Korrosion. Bei Inspektionen wurde festgestellt, dass bei Leitungen mit zwei Krümmern der Eintrittsbereich in den zweiten Krümmer am anfälligsten ist, aber es wurden auch durch strömungsinduzierte Korrosion stark geschwächte Bereich im Eintrittsbereich des ersten Krümmers gefunden. Um diese Befunde zu untersuchen, wurde der Einfluss der Orientierung des ersten Krümmers mit Hilfe von CFD Berechnungen untersucht. Dazu wurde zum einen die Colburn Analogie und zum anderen eine empirische Korrelation zwischen Abnutzungsrate und Scherspannung herangezogen. Die Ergebnisse werden im Beitrag vorgestellt.
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© 2014, Carl Hanser Verlag, München
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Decomposition analysis of the sodium void reactivity of the Korean sodium-cooled fast reactor
- Flow accelerated corrosion study in feeder pipes
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- Experimental investigation of the MSFR molten salt reactor concept
- Investigation of neutronic behavior in a CANDU reactor with different (Am, Th, 235U)O2 fuel matrixes
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Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Decomposition analysis of the sodium void reactivity of the Korean sodium-cooled fast reactor
- Flow accelerated corrosion study in feeder pipes
- Analysis of the flow instability among channels of the OTSG in the naval craft NPP
- Experimental investigation of the MSFR molten salt reactor concept
- Investigation of neutronic behavior in a CANDU reactor with different (Am, Th, 235U)O2 fuel matrixes
- Atomistic nano-scale 3D simulations about effects of Cr percentage on the molecular dynamics parameters of Fe-9–12% Cr alloys at fusion reactor temperature conditions
- On an analytical evaluation of the flux and dominant eigenvalue problem for the steady state multi-group multi-layer neutron diffusion equation
- A finite volume approach to the problem of heat transfer in axisymmetric annulus geometry with internal heating element using local analytical solution techniques
- CO2 doped γ-irradiated hydroxyapatite for EPR dosimetry
- An investigation of the effect of the upper beryllium reflector on the moderator temperature coefficient of reactivity of miniature neutron source reactors
