Analyses of Free Span Oxide Layers on SG Tubes of NPP Temelin

2008 ◽  
Author(s):  
A. Hojna ◽  
V. Hanus ◽  
V. Pisarik ◽  
M. Postler ◽  
J. Burda ◽  
...  
Keyword(s):  
Free Surface ◽  
Oxide Layer ◽  
Steam Generator ◽  
Feed Water ◽  
Oxide Layers ◽  
The Real ◽  
Secondary Side

The differences in deposit layers on steam generator (SG) tubes of WWER NPP Temelin have been observed, namely in compactness and adhesiveness. The samples of the oxide layers have been taken from different SG during outage of the two units and analyzed. Results of the analyses are compared to previous results on deposit layers created during operation of SG model. The model simulates secondary side of SG tubes operation; the original feed water from the NPP Temelin has been used for tests. Deposit built up on tubes inside the model on the free surface is related to the real SG tube deposits and differences of the oxide layer morphologies are discussed.

scholarly journals Analysis of Corrosion Products Transported through Secondary Side of Candu Steam Generator Using GIXRD

2020 ◽  
Vol 71 (2) ◽  
pp. 99-104
Author(s):  
Alice Dinu ◽  
Mariana Tunaru
Keyword(s):  
Iron Oxide ◽  
Steam Generator ◽  
Corrosion Products ◽  
Feed Water ◽  
X Ray Diffraction ◽  
Blow Down ◽  
X Ray ◽  
Oxide Hydroxide ◽  
Secondary Side ◽  
Millipore Filters

To verify the chemistry of secondary side of CANDU steam generators, Millipore filters are used to sampling from condensing extraction pump, feed water header and blow down of steam generator. These filters retain the corrosion products as very fine particles and are used as samples in chemistry water control. X-Ray diffraction (XRD) is the most used technique that can provide information about the phase composition of analyzed samples. Because the crud layers on the Millipore filters are very thin, to identify the corrosion products Grazing Incidence X-Ray diffraction (GIXRD) technique was used. The following compounds have identified: magnetite (Fe3O4), hematite (Fe2O3), and iron oxide hydroxide (FeOOH). It was observed a brown-reddish background specific to hematite and iron oxide hydroxide, especially for filters extracted from condensing extraction pump. The black colour of crud present on filters extracted from feed water header and blow down of steam generator shows the presence of magnetite.

Numerical Analysis of Subcooled Water Flashing Flow From a Pressurized Water Reactor Steam Generator Through an Abruptly Broken Main Feed Water Pipe

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Jong Chull Jo ◽  
Jae Jun Jeong ◽  
Byong Jo Yun ◽  
Jongkap Kim
Keyword(s):  
Flow Field ◽  
Steam Generator ◽  
Feed Water ◽  
Water Pipe ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Subcooled Water ◽  
Numerical Predictions ◽  
Secondary Side

A computational fluid dynamics (CFD) analysis was performed to investigate the hydraulic response of the flow field inside the pressurized water reactor (PWR) steam generator (SG) secondary side and the connected part of main feed water pipe to an abrupt main feed water line break (FWLB) accident. To realistically analyze the transient flow field situation, the flow field was assumed to be occupied initially by highly compressed subcooled water except that the upper part of the SG secondary side where steam occupied as in the practical case and the break was assumed to occur at the circumferential weld line between the feed water nozzle and the main feed water pipe. This would result in a subcooled water flashing flow from the SG through the short-broken pipe end to the surrounding atmosphere, which was numerically simulated in this study. Typical results of the prediction in terms of the fluid transient velocity and pressure were illustrated and discussed. To examine the physical validity of the present numerical simulation of the subcooled water flashing flow, the transient mass flow rates predicted in this study were compared with the other previous numerical predictions based on the subcooled water nonflashing (no phase change) flow or saturated water flashing flow assumptions and the prediction by a simple analysis method.

Applicability of Chemical Cleaning Process to Steam Generator Secondary Side, (I)

2004 ◽  
Vol 41 (1) ◽  
pp. 44-54 ◽  
Author(s):  
Kazutoshi FUJIWARA ◽  
Hirotaka KAWAMURA ◽  
Hiromi KANBE ◽  
Hideo HIRANO ◽  
Hideki TAKIGUCHI ◽  
...  
Keyword(s):  
Steam Generator ◽  
Cleaning Process ◽  
Chemical Cleaning ◽  
Secondary Side

Nucleation and Growth of Oxide Layers on Stainless Steels (FeCr) Using a Virtual Oxide Layer Model

2010 ◽  
Vol 114 (45) ◽  
pp. 19299-19307 ◽  
Author(s):  
Boubakar Diawara ◽  
Yves-Alain Beh ◽  
Philippe Marcus
Keyword(s):  
Oxide Layer ◽  
Stainless Steels ◽  
Nucleation And Growth ◽  
Layer Model ◽  
Oxide Layers

Transient Thermal-Hydraulic Responses of the Nuclear Steam Generator Secondary Side to a Main Steam Line Break1

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Jong Chull Jo ◽  
Frederick J. Moody
Keyword(s):  
Steam Generator ◽  
Steam Line ◽  
Analysis Model ◽  
Pressurized Water ◽  
Line Pipe ◽  
Short Period ◽  
Main Steam Line ◽  
Main Steam ◽  
Transient Thermal ◽  
Secondary Side

This paper presents a multidimensional numerical analysis of the transient thermal-hydraulic response of a steam generator (SG) secondary side to a double-ended guillotine break of the main steam line attached to the SG at a pressurized water reactor (PWR) plant. A simplified analysis model is designed to include both the SG upper space, which the steam occupies and a part of the main steam line between the SG outlet nozzle and the pipe break location upstream of the main steam isolation valve. The transient steam flow through the analysis model is simulated using the shear stress transport (SST) turbulence model. The steam is treated as a real gas. To model the steam generation by heat transfer from the primary coolant to the secondary side coolant for a short period during the blow down process following the main steam line break (MSLB) accident, a constant amount of steam is assumed to be generated from the bottom of the SG upper space part. Using the numerical approach mentioned above, calculations have been performed for the analysis model having the same physical dimensions of the main steam line pipe and initial operational conditions as those for an actual operating plant. The calculation results have been discussed in detail to investigate their physical meanings and validity. The results demonstrate that the present computational fluid dynamics (CFD) model is applicable for simulating the transient thermal-hydraulic responses in the event of the MSLB accident including the blowdown-induced dynamic pressure disturbance in the SG. In addition, it has been found that the dynamic hydraulic loads acting on the SG tubes can be increased by 2–8 times those loads during the normal reactor operation. This implies the need to re-assess the potential for single or multiple SG tube ruptures due to fluidelastic instability for ensuring the reactor safety.

scholarly journals Surface Oxidation of Nano-Silicon as a Method for Cycle Life Enhancement of Li-ion Active Materials

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4093
Author(s):  
Maciej Ratynski ◽  
Bartosz Hamankiewicz ◽  
Dominika A. Buchberger ◽  
Andrzej Czerwinski
Keyword(s):  
Oxide Layer ◽  
Silicon Nanoparticles ◽  
Specific Capacity ◽  
Single Step ◽  
Native Oxide ◽  
Electrochemical Characteristics ◽  
Active Materials ◽  
Silicon Oxide Layer ◽  
Oxide Layers ◽  
Li Ion

Among the many studied Li-ion active materials, silicon presents the highest specific capacity, however it suffers from a great volume change during lithiation. In this work, we present two methods for the chemical modification of silicon nanoparticles. Both methods change the materials’ electrochemical characteristics. The combined XPS and SEM results show that the properties of the generated silicon oxide layer depend on the modification procedure employed. Electrochemical characterization reveals that the formed oxide layers show different susceptibility to electro-reduction during the first lithiation. The single step oxidation procedure resulted in a thin and very stable oxide that acts as an artificial SEI layer during electrode operation. The removal of the native oxide prior to further reactions resulted in a very thick oxide layer formation. The created oxide layers (both thin and thick) greatly suppress the effect of silicon volume changes, which significantly reduces electrode degradation during cycling. Both modification techniques are relatively straightforward and scalable to an industrial level. The proposed modified materials reveal great applicability prospects in next generation Li-ion batteries due to their high specific capacity and remarkable cycling stability.

Steam Generator In-Service Inspections at Paks NPP

2008 ◽  
Author(s):  
Miklo´s Do´czi
Keyword(s):  
Heat Exchanger ◽  
Steam Generator ◽  
Eddy Current ◽  
Power Plants ◽  
Tube Bundle ◽  
Degradation Mechanism ◽  
Feed Water ◽  
Material Damage ◽  
Steam Generators ◽  
Service Inspection

Steam Generator is one of the most critical components in nuclear power plants. It has of overriding importance from point of view of safe and reliable operation of the whole plant. Variety of degradation mechanisms affecting SG tube bundle may cause different types of material damage. In Paks NPP eddy current in-service inspection have been performed since 1988. In the year 1997 higher number of defected tubes were found in case of Unit#2, compared to results of the previous years. A medium term SG inspection program had been performed in the time period between 1998–2004. Based on the results of eddy current inspections high number of heat exchanger tubes had been plugged. Chemical cleanings of all steam generators were performed aiming to reduce the magnetite, copper deposits and corrosion agents acting on the surface of the tubes. Replacement of the main condensers had been performed to stop the uncontrolled water income caused by the relatively frequent leakages of the condenser tubes. Several tube samples had been cut from the first row of the tube bundles of different steam generators to study the effectiveness of the cleaning process and to determine the composition of deposits on the tube outside surface. Also several tubes with eddy current indications had been pulled out from the steam generators to determine the acting degradation mechanism. Examination of removed tubes can provide opportunity to check the reliability of eddy current inspection using bobbin coil. Also there were tubes pulled out form SG with existing cracks. From the year 2005 new inspection program had been started. As the first results of the new inspection program shows, there is only a few new indications had been found and there is no measurable crack propagation in case of existing indications. During the recent years feed-water collectors were replaced in case of all units of the power plant, because of material damage (erosion corrosion). The paper summarizes the results of eddy current in-service inspection of heat exchanger tubes, results of examinations of removed tubes and also deals with results of visual examination of the feed-water distributor system.

Localized Corrosion of Nuclear Grade Alloy 800 Under Steam Generator Layup, Startup and Operating Conditions

2012 ◽  
Vol 1 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Y. Lu
Keyword(s):  
Corrosion Resistance ◽  
Steam Generator ◽  
Elevated Temperatures ◽  
Chloride Concentration ◽  
Operating Conditions ◽  
Nuclear Grade ◽  
Localized Corrosion ◽  
Pitting Potential ◽  
Alloy 800 ◽  
Secondary Side

The localized corrosion resistance of nuclear-grade Alloy 800, which is one of the preferred steam generator (SG) heat exchange tube materials of CANDU and PWR reactors, was studied under simulated SG secondary side crevice chemistry conditions at ambient temperature as well as at elevated temperatures. Series of cyclic potentiodynamic polarization tests were performed to study the localized corrosion resistance of Alloy 800 as a function of chloride ion concentration in the SG crevice solution at 40°C, 150°C and 300°C. Based on the experimental results, empirical equations were provided for calculating the pitting potential of nuclear grade Alloy 800 in the SG secondary side crevice chemistries with different levels of chloride concentration at SG layup, startup and operating temperatures.

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