Corrosion of silicon nitride in high temperature alkaline solutions

Energy Technology Data Exchange (ETDEWEB)

Qiu, Liyan, E-mail: liyan.qiu@cnl.ca; Guzonas, Dave A.; Qian, Jing

2016-08-01

The corrosion of silicon nitride (Si{sub 3}N{sub 4}) in alkaline solutions was studied at temperatures from 60 to 300 °C. Si{sub 3}N{sub 4} experienced significant corrosion above 100 °C. The release rates of silicon and nitrogen follow zero order reaction kinetics and increase with increasing temperature. The molar ratio of dissolved silicon and nitrogen species in the high temperature solutions is the same as that in the solid phase (congruent dissolution). The activation energy for silicon and nitrogen release rates is 75 kJ/mol which agrees well with that of silica dissolution. At 300 °C, the release of aluminum is observed and follows first order reaction kinetics while other minor constituents including Ti and Y are highly enriched on the corrosion films due to the low solubility of their oxides.

Corrosion Resistant Coatings for High Temperature Applications

Energy Technology Data Exchange (ETDEWEB)

Besman, T.M.; Cooley, K.M.; Haynes, J.A.; Lee, W.Y.; Vaubert, V.M.

1998-12-01

Efforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of higher-temperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

Energy Technology Data Exchange (ETDEWEB)

Lee, Jung Gu, E-mail: jglee88@ulsan.ac.kr [School of Materials Science and Engineering, University of Ulsan, Ulsan 44610 (Korea, Republic of); Lee, Gyoung-Ja; Park, Jin-Ju [Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 34057 (Korea, Republic of); Lee, Min-Ku, E-mail: leeminku@kaeri.re.kr [Nuclear Materials Development Division, Korea Atomic Energy Research Institute (KAERI), Yuseong, Daejeon 34057 (Korea, Republic of)

2017-05-15

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments. - Highlights: •Corrosion of Zircaloy-4 joints brazed with Zr-Cu-X filler alloys was investigated. •Alloyed Al deteriorated the overall nobility of joints by microgalvanic reaction. •Compositional gradient of Al in joints was the driving force for galvanic corrosion. •Cu and Fe did not influence the electrochemical stability of joints. •Zr-Cu-Fe filler alloy yielded excellent high-temperature corrosion resistance.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

International Nuclear Information System (INIS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-01-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments. - Highlights: •Corrosion of Zircaloy-4 joints brazed with Zr-Cu-X filler alloys was investigated. •Alloyed Al deteriorated the overall nobility of joints by microgalvanic reaction. •Compositional gradient of Al in joints was the driving force for galvanic corrosion. •Cu and Fe did not influence the electrochemical stability of joints. •Zr-Cu-Fe filler alloy yielded excellent high-temperature corrosion resistance.

HIGH TEMPERATURE CORROSION RESISTANCE OF METALLIC MATERIALS IN HARSH CONDITIONS

OpenAIRE

Novello, Frederic; Dedry, Olivier; De Noose, Vincent; Lecomte-Beckers, Jacqueline

2014-01-01

Highly efficient energy recovery from renewable sources and from waste incineration causes new problems of corrosion at high temperature. A similar situation exists for new recycling processes and new energy storage units. These corrosions are generally considered to be caused by ashes or molten salts, the composition of which differs considerably from one plant to another. Therefore, for the assessment of corrosion-resistance of advanced materials, it is essential to precisely evaluate the c...

Corrosion behaviour of high temperature alloys in the cooling gas of high temperature reactors

International Nuclear Information System (INIS)

Quadakkers, W.J.; Schuster, H.

1989-01-01

The reactive impurities in the primary cooling helium of advanced high temperature gas cooled reactors (HTGR) can cause oxidation, carburization or decarburization of the heat exchanging metallic components. By studies of the fundamental aspects of the corrosion mechanisms it became possible to define operating conditions under which the metallic construction materials show, from the viewpoint of technical application, acceptable corrosion behaviour. By extensive test programmes with exposure times of up to 30,000 hours, a data base has been obtained which allows a reliable extrapolation of the corrosion effects up to the envisaged service lives of the heat exchanging components. (author). 6 refs, 7 figs

High Temperature Corrosion in Biomass Incineration Plants

DEFF Research Database (Denmark)

Montgomery, Melanie; Maahn, Ernst emanuel; Gotthjælp, K.

1997-01-01

The aim of the project is to study the role of ash deposits in high temperature corrosion of superheater materials in biomass and refuse fire combined heat and power plants. The project has included the two main activities: a) A chemical characterisation of ash deposits collected from a major...

Corrosion of Ferritic-Martensitic steels in high temperature water: A literature Review

International Nuclear Information System (INIS)

Fernandez, P.; Lapena, J.; Blazquez, F.

2001-01-01

Available literature concerning corrosion of high-chromium ferritic/martensitic steel in high temperature water as reviewed. The subjects considered are general corrosion, effect of irradiation on corrosion, environmentally assisted cracking (EAC) including stress corrosion cracking (SCC), corrosion fatigue and irradiation-assisted stress corrosion cracking (IASCC). In addition some investigations about radiation induced segregation (RIS). Are shown in order to know the compositional changes at grain boundaries of these alloys and their influence on corrosion properties. (Author)

Corrosion resistance of high-performance materials titanium, tantalum, zirconium

CERN Document Server

2012-01-01

Corrosion resistance is the property of a material to resist corrosion attack in a particular aggressive environment. Although titanium, tantalum and zirconium are not noble metals, they are the best choice whenever high corrosion resistance is required. The exceptionally good corrosion resistance of these high–performance metals and their alloys results from the formation of a very stable, dense, highly adherent, and self–healing protective oxide film on the metal surface. This naturally occurring oxide layer prevents chemical attack of the underlying metal surface. This behavior also means, however, that high corrosion resistance can be expected only under neutral or oxidizing conditions. Under reducing conditions, a lower resistance must be reckoned with. Only very few inorganic and organic substances are able to attack titanium, tantalum or zirconium at ambient temperature. As the extraordinary corrosion resistance is coupled with an excellent formability and weldability these materials are very valua...

High temperature corrosion in straw-fired power plants: Influence of steam/metal temperature on corrosion rates for TP347H

DEFF Research Database (Denmark)

Montgomery, Melanie; Biede, O; Larsen, OH

2002-01-01

The corrosion in straw-fired boilers has been investigated at various straw-fired power plants in Denmark. Water/air-cooled probes, a test superheater and test sections removed from the actual superheater have been utilised to characterise corrosion and corrosion rates. This paper describes...... the corrosion rates measured for the TP347H type steel. The corrosion morphology at high temperature consists of grain boundary attack and selective attack of chromium. The corrosion rate increases with calculated metal temperature (based on steam temperature), however there is great variation within....... The difference in the results could be traced back to a lower flue gas temperature on one side of the boiler. Although metal temperature is the most important parameter with respect to corrosion rate, flue gas temperature also plays an important role. Efforts to quantify the effect of flue gas temperature...

Materials and coatings to resist high temperature oxidation and corrosion

International Nuclear Information System (INIS)

1977-01-01

Object of the given papers are the oxidation and corrosion behaviour of several materials (such as stainless steels, iron-, or nickel-, or cobalt-base alloys, Si-based ceramics) used at high temperatures and various investigations on high-temperature protective coatings. (IHoe) [de

Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

Science.gov (United States)

Wang, Tao; Reddy, Ramana G.

2017-03-01

MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

Very-high-temperature reactors for future use

International Nuclear Information System (INIS)

Kasten, P.R.

1988-01-01

Very-High-Temperature Reactors (VHTRs) show promise for economic generation of electricity and of high-temperature process heat. The key is the development of high-temperature materials which permit gas turbine VHTRs to generate electricity economically, at helium temperatures which can be used for fossil fuel conversion processes. 7 refs., 5 figs

Very-high-temperature reactors for future use

International Nuclear Information System (INIS)

Kasten, P.R.

1988-08-01

Very-high-temperature reactors (VHTRs) show promise for economic generation of electricity and of high-temperature process heat. The key is the development of high-temperature materials which permit gas turbine VHTRs to generate electricity economically, at reactor coolant temperatures which can be used for fossil fuel conversion processes. 7 refs., 5 figs

Corrosion of metallic materials by uranium hexafluoride at high temperatures (1963)

International Nuclear Information System (INIS)

Langlois, G.

1963-01-01

The corrosion of the following metals or alloys by UF 6 : nickel, monel, Inconel, gold, platinum, stainless steel, is studied in the temperature range from 300 to 1000 deg. C. The test method, designed to avoid heating the apparatus containing the corrosive fluid to a high temperature, consists in using threadlike samples heated by the Joule effect, the rest of the apparatus being maintained close to room temperature. This technique makes it possible also to determine continuously the penetration of the corrosion by measuring the electrical resistance of the sample with a double Thomson bridge. A series of rapid comparison tests shows that stainless steel, precious metals and Inconel are attacked far too rapidly to be used above 500 deg. C; only monel and especially nickel appear capable of resisting at high temperatures. The detailed examination of the behaviour of nickel shows that the metallic fluoride is volatilized and that this influences the corrosion rate. It shows also the existence of a temperature zone situated between 550 and 700 deg. C in which occurs A strong intergranular corrosion the cause of which appears to be the presence of impurities in the metal. (author) [fr

Corrosion behaviour of construction materials for high temperature steam electrolysers

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

2011-01-01

temperature proton exchange membrane (PEM) steam electrolysers. Steady-state voltammetry was used in combination with scanning electron microscopy and energy-dispersive X-ray spectroscopy to evaluate the stability of the mentioned materials. It was found that stainless steels were the least resistant...... to corrosion under strong anodic polarisation. Among alloys, Ni-based showed the highest corrosion resistance in the simulated PEM electrolyser medium. In particular, Inconel 625 was the most promising among the tested corrosion-resistant alloys for the anodic compartment in high temperature steam electrolysis...

Corrosion Behaviors of Structural Materials in High Temperature S-CO{sub 2} Environments

Energy Technology Data Exchange (ETDEWEB)

Lee, Ho Jung; Kim, Hyunmyung; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

2014-04-15

The isothermal corrosion tests of several types of stainless steels, Ni-based alloys, and ferritic-martensitic steels (FMS) were carried out at the temperature of 550 and 650 .deg. C in SFR S-CO{sub 2} environment (200 bar) for 1000 h. The weight gain was greater in the order of FMSs, stainless steels, and Ni-based alloys. For the FMSs (Fe-based with low Cr content), a thick outer Fe oxide, a middle (Fe,Cr)-rich oxide, and an inner (Cr,Fe)-rich oxide were formed. They showed significant weight gains at both 550 and 650 .deg. C. In the case of austenitic stainless steels (Fe-based) such as SS 316H and 316LN (18 wt.% Cr), the corrosion resistance was dependent on test temperatures except SS 310S (25 wt.% Cr). After corrosion test at 650 .deg. C, a large increase in weight gain was observed with the formation of outer thick Fe oxide and inner (Cr,Fe)-rich oxide. However, at 550 .deg. C, a thin Cr-rich oxide was mainly developed along with partially distributed small and nodular shaped Fe oxides. Meanwhile, for the Ni-based alloys (16-28 wt.% Cr), a very thin Cr-rich oxide was developed at both test temperatures. The superior corrosion resistance of high Cr or Ni-based alloys in the high temperature S-CO{sub 2} environment was attributed to the formation of thin Cr-rich oxide on the surface of the materials.

High temperature corrosion of superheater materials for power production through biomass

Energy Technology Data Exchange (ETDEWEB)

Gotthjaelp, K.; Broendsted, P. [Forskningscenter Risoe (Denmark); Jansen, P. [FORCE Institute (Denmark); Montgomery, M.; Nielsen, K.; Maahn, E. [Technical Univ. of Denmark, Corrosion and Surface Techn. Inst. of Manufacturing Engineering (Denmark)

1996-08-01

The aim of the present study has been to establish a fundamental knowledge of the corrosion mechanisms acting on materials for use in biomass fired power plants. The knowledge is created based on laboratory exposures of selected materials in well-defined corrosive gas environments. The experiments using this facility includes corrosion studies of two types of high temperature resistant steels, Sanvik 8LR30 (18Cr 10Ni Ti) and Sanicro 28 (27Cr 31Ni 4Mo), investigated at 600 deg. C in time intervals up to 300 hours. The influence of HCl (200 ppm) and of SO{sub 2} (300 ppm) on the corrosion progress has been investigated. In addition the corrosion behaviour of the same materials was investigated after having been exposed under a cover of ash in air in a furnace at temperatures of 525 deg. C, 600 deg. C, and 700 deg. C. The ashes utilised are from a straw fired power plant and a synthetic ash composed of potassium chloride (KCl) and potassium sulphate (K{sub 2}SO{sub 4}). Different analysis techniques to characterise the composition of the ash coatings have been investigated in order to judge the reliability and accuracy of the SEM-EDX method. The results are considered as an important step towards a better understanding of the high temperature corrosion under the conditions found in biomass fired power plants. One of the problems to solve in a suggested subsequent project is to combine the effect of the aggressive gases (SO{sub 2} and HCl) and the active ash coatings on high temperature corrosion of materials. (EG) 20 refs.

Potential uses of high gradient magnetic filtration for high-temperature water purification in boiling water reactors

International Nuclear Information System (INIS)

Elliott, H.H.; Holloway, J.H.; Abbott, D.G.

1979-01-01

Studies of various high-temperature filter devices indicate a potentially positive impact for high gradient magnetic filtration on boiling water reactor radiation level reduction. Test results on in-plant water composition and impurity crystallography are presented for several typical boiling water reactors (BWRs) on plant streams where high-temperature filtration may be particularly beneficial. An experimental model on the removal of red iron oxide (hematite) from simulated reactor water with a high gradient magnetic filter is presented, as well as the scale-up parameters used to predict the filtration efficiency on various high temperature, in-plant streams. Numerical examples are given to illustrate the crud removal potential of high gradient magnetic filters installed at alternative stream locations under typical, steady-state, plant operating conditions

CERN/KEK: Very high accelerating gradients

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-01-15

Full text: A world-wide effort is under way to develop linear electron-positron colliders so that physics experiments can be extended into a range of energies where circular machines (necessarily much larger than CERN's 27-kilometre LEP machine) would be crippled by synchrotron radiation. CERN is studying the feasibility of building a 2 TeV machine called CLIC powered not by individual klystrons, but by a high intensity electron 'drive' linac running parallel to the main linac (November 1990, page 7). This drive linac will itself be powered by similar superconducting cavities to those developed for LEP. A high gradient is an obvious design aim for any future high energy linear collider because it makes it shorter and therefore cheaper - the design figure for the CLIC machine is 80 MV/m. The CLIC study group has taken a significant step forward in demonstrating the technical feasibility of their machine by achieving peak and average accelerating gradients of 137 MV/m and 84 MV/m respectively in a short section of accelerating structure during high gradient tests at the Japanese KEK Laboratory last year. This result obtained within the framework of a CERN/KEK collaboration on linear colliders was obtained using a 20-cell accelerating section built at CERN using state-of the- art technology which served both as a model for CLIC studies as well as a prototype for the Japanese Linear Collider studies. The operating frequency of the model accelerating section is 2.6 times lower than the CLIC frequency but was chosen because a high power r.f. source and pulse compression scheme has been developed for this frequency at KEK. Testing CLIC models at 11.4 GHz is however more stringent than at 30 GHz because the chance of electrical breakdown increases as the frequency is lowered. This recent result clearly demonstrates that a gradient of 80 MV/m is feasible.

CERN/KEK: Very high accelerating gradients

International Nuclear Information System (INIS)

Anon.

1993-01-01

Full text: A world-wide effort is under way to develop linear electron-positron colliders so that physics experiments can be extended into a range of energies where circular machines (necessarily much larger than CERN's 27-kilometre LEP machine) would be crippled by synchrotron radiation. CERN is studying the feasibility of building a 2 TeV machine called CLIC powered not by individual klystrons, but by a high intensity electron 'drive' linac running parallel to the main linac (November 1990, page 7). This drive linac will itself be powered by similar superconducting cavities to those developed for LEP. A high gradient is an obvious design aim for any future high energy linear collider because it makes it shorter and therefore cheaper - the design figure for the CLIC machine is 80 MV/m. The CLIC study group has taken a significant step forward in demonstrating the technical feasibility of their machine by achieving peak and average accelerating gradients of 137 MV/m and 84 MV/m respectively in a short section of accelerating structure during high gradient tests at the Japanese KEK Laboratory last year. This result obtained within the framework of a CERN/KEK collaboration on linear colliders was obtained using a 20-cell accelerating section built at CERN using state-of the- art technology which served both as a model for CLIC studies as well as a prototype for the Japanese Linear Collider studies. The operating frequency of the model accelerating section is 2.6 times lower than the CLIC frequency but was chosen because a high power r.f. source and pulse compression scheme has been developed for this frequency at KEK. Testing CLIC models at 11.4 GHz is however more stringent than at 30 GHz because the chance of electrical breakdown increases as the frequency is lowered. This recent result clearly demonstrates that a gradient of 80 MV/m is feasible

Coal-fired power plants and the causes of high temperature corrosion

Energy Technology Data Exchange (ETDEWEB)

Oakey, J E; Simms, N J [British Coal Corporation, Coal Technology Development Div., Cheltenham, Glos (United Kingdom); Tomkings, A B [ERA Technology Ltd., Leatherhead, Surrey (United Kingdom)

1996-12-01

The heat exchangers in all types of coal-fired power plant operate in aggressive, high temperature environments where high temperature corrosion can severely limit their service lives. The extent of this corrosion is governed by the combined effects of the operating conditions of the heat exchanger and the presence of corrosive species released from the coal during operation. This paper reviews the coal-related factors, such as ash deposition, which influence the operating environments of heat exchangers in three types of coal-fired power plant - conventional pulverized coal boilers, fluidized bed boilers and coal gasification systems. The effects on the performance of the materials used for these heat exchangers are then compared. (au) 35 refs.

Corrosion of structural materials and electrochemistry in high temperature water of nuclear power systems

International Nuclear Information System (INIS)

Uchida, Shunsuke

2008-01-01

The latest experiences with corrosion in the cooling systems of nuclear power plants are reviewed. High temperature cooling water causes corrosion of structural materials, which often leads to adverse effects in the plants, e.g., increased shutdown radiation, generation of defects in materials of major components and fuel claddings, and increased volume of radwaste sources. Corrosion behavior is greatly affected by water quality and differs according to the water quality values and the materials themselves. In order to establish reliable operation, each plant requires its own unique optimal water chemistry control based on careful consideration of its system, materials and operational history. Electrochemistry is one of the key issues that determine corrosion-related problems, but it is not the only issue. Most corrosion-related phenomena, e.g., flow accelerated corrosion (FAC), intergranular stress corrosion cracking (IGSCC), primary water stress corrosion cracking (PWSCC) and thinning of fuel cladding materials, can be understood based on an electrochemical index, e.g., the electrochemical corrosion potential (ECP), conductivities and pH. The most important electrochemical index, the ECP, can be measured at elevated temperature and applied to in situ sensors of corrosion conditions to detect anomalous conditions of structural materials at their very early stages. (orig.)

High temperature oxidation and corrosion behavior of Ni-base superalloy in He environment

International Nuclear Information System (INIS)

Lee, Gyoeng Geun; Park, Ji Yeon; Jung, Su jin

2010-11-01

Ni-base superalloy is considered as a IHX (Intermediate Heat Exchanger) material for VHTR (Very High Temperature Gas-Cooled Reactor). The helium environment in VHTR contains small amounts of impure gases, which cause oxidation, carburization, and decarburization. In this report, we conducted the literature survey about the high temperature behavior of Ni-base superalloys in air and He environments. The basic information of Ni-base superalloy and the basic metal-oxidation theory were briefly stated. The He effect on the corrosion of Ni-base superalloy was also summarized. This works would provide a brief suggestion for the next research topic for the application of Ni-base superalloy to VHTR

The synergy of corrosion and fretting wear process on Inconel 690 in the high temperature high pressure water environment

Science.gov (United States)

Wang, Zihao; Xu, Jian; Li, Jie; Xin, Long; Lu, Yonghao; Shoji, Tetsuo; Takeda, Yoichi; Otsuka, Yuichi; Mutoh, Yoshiharu

2018-04-01

The synergistic effect of corrosion and fretting process of the steam generator (SG) tube was investigated by using a self-designed high temperature test rig in this paper. The experiments were performed at 100°C , 200°C and 288°C , respectively. The fretting corrosion damage was studied by optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Raman spectroscopy and auger electron spectroscopy (AES). The results demonstrated that the corrosion process in high temperature high pressure (HTHP) water environment had a distinct interaction with the fretting process of Inconel 690. With the increment of temperature, the damage mechanism changed from a simple mechanical process to a mechanochemical process.

Corrosion Behavior of Nickel-Plated Alloy 600 in High Temperature Water

International Nuclear Information System (INIS)

Kim, Ji Hyun; Hwang, Il Soon

2008-01-01

In this paper, electrochemical and microstructural characteristics of nickel-plated Alloy 600 wee investigated in order to identify the performance of electroless Ni-plating on Alloy 600 in high-temperature aqueous condition with the comparison of electrolytic nickel-plating. For high temperature corrosion test of nickel-plated Alloy 600, specimens were exposed for 770 hours to typical PWR primary water condition. During the test, open circuit potentials (OCP's) of all specimens were measured using a reference electrode. Also, resistance to flow accelerated corrosion (FAC) test was examined in order to check the durability of plated layers in high-velocity flow environment at high temperature. After exposures to high flow rate aqueous condition, the integrity of surfaces was confirmed by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the field application, a remote process for electroless nickel-plating was demonstrated using a plate specimen with narrow gap on a laboratory scale. Finally, a practical seal design was suggested for more convenient application

High temperature aqueous stress corrosion testing device

International Nuclear Information System (INIS)

Bornstein, A.N.; Indig, M.E.

1975-01-01

A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston

Electrochemical corrosion potential and noise measurement in high temperature water

International Nuclear Information System (INIS)

Fong, Clinton; Chen, Yaw-Ming; Chu, Fang; Huang, Chia-Shen

2000-01-01

Hydrogen water chemistry (HWC) is one of the most important methods in boiling water reactor(BWR) system to mitigate and prevent stress corrosion cracking (SCC) problems of stainless steel components. Currently, the effectiveness of HWC in each BWR is mainly evaluated by the measurement of electrochemical corrosion potentials (ECP) and on-line monitoring of SCC behaviors of stainless steels. The objective of this work was to evaluate the characteristics and performance of commercially available high temperature reference electrodes. In addition, SCC monitoring technique based on electrochemical noise analysis (ECN) was also tested to examine its crack detection capability. The experimental work on electrochemical corrosion potential (ECP) measurements reveals that high temperature external Ag/AgCl reference electrode of highly dilute KCl electrolyte can adequately function in both NWC and HWC environments. The high dilution external Ag/AgCl electrode can work in conjunction with internal Ag/AgCl reference electrode, and Pt electrode to ensure the ECP measurement reliability. In simulated BWR environment, the electrochemical noise tests of SCC were carried out with both actively and passively loaded specimens of type 304 stainless steel with various electrode arrangements. From the coupling current and corrosion potential behaviors of the passive loading tests during immersion test, it is difficult to interpret the general state of stress corrosion cracking based on the analytical results of overall current and potential variations, local pulse patterns, statistical characteristics, or power spectral density of electrochemical noise signals. However, more positive SCC indication was observed in the power spectral density analysis. For aqueous environments of high solution impedance, successful application of electrochemical noise technique for SCC monitoring may require further improvement in specimen designs and analytical methods to enhance detection sensitivity

General corrosion of carbon steels in high temperature water

International Nuclear Information System (INIS)

Gras, J.M.

1994-04-01

This short paper seeks to provide a summary of the main knowledge about the general corrosion of carbon steels in high temperature water. In pure water or slightly alkaline deaerated water, steels develop a protective coating of magnetite in a double layer (Potter and Mann oxide) or a single layer (Bloom oxide). The morphology of the oxide layer and the kinetics of corrosion depend on the test parameters controlling the solubility of iron. The parameters exercising the greatest influence are partial hydrogen pressure and mass transfer: hydrogen favours the solubilization of the magnetite; the entrainment of the dissolved iron prevents a redeposition of magnetite on the surface of the steel. Cubic or parabolic in static conditions, the kinetics of corrosion tends to be linear in dynamic conditions. In dynamic operation, corrosion is at least one order of magnitude lower in water with a pH of 10 than in pure water with a pH of 7. The activation energy of corrosion is 130 kJ/mol (31 kcal/mol). This results in the doubling of corrosion at around 300 deg C for a temperature increase of 15 deg C. Present in small quantities (100-200 ppb), oxygen decreases general corrosion but increases the risk of pitting corrosion - even for a low chloride content - and stress corrosion cracking or corrosion-fatigue. The steel composition has probably an influence on the kinetics of corrosion in dynamic conditions; further work would be required to clarify the effect of some residual elements. (author). 31 refs., 9 figs., 2 tabs

High temperature corrosion of separator materials for MCFC

Energy Technology Data Exchange (ETDEWEB)

Yanagida, Masahiro; Tanimoto, Kazumi; Kojima, Toshikatsu [Osaka National Research Institute (Japan)] [and others

1996-12-31

The Molten Carbonate Fuel Cell (MCFC) is one of promising high efficiency power generation devices with low emission. Molten carbonate used for its electrolyte plays an important role in MCFC. It separates between anode and cathode gas environment and provides ionic conductivity on MCFC operation. Stainless steel is conventionally used as separator/current collector materials in MCFC cathode environment. As corrosion of the components of MCFC caused by the electrolyte proceeds with the electrolyte consumption, the corrosion in the MCFC is related to its performance and life. To understand and inhibit the corrosion in the MCFC is important to realize MCFC power generation system. We have studied the effect of alkaline earth carbonate addition into carbonate on corrosion of type 316L stainless steel. In this paper, we describe the effect of the temperature on corrosion behavior of type 316L stainless steel with carbonate mixture, (Li{sub 0.62}K{sub 0.38}){sub 2}CO{sub 3}, under the cathode environment in out-of-cell test.

High temperature chlorosilane corrosion of iron and AISI 316L stainless steel

Science.gov (United States)

Aller, Joshua Loren

Chlorosilane gas streams are used at high temperatures (>500°C) throughout the semiconductor, polycrystalline silicon, and fumed silica industries, primarily as a way to refine, deposit, and produce silicon and silicon containing materials. The presence of both chlorine and silicon in chlorosilane species creates unique corrosion environments due to the ability of many metals to form both metal-chlorides and metal-silicides, and it is further complicated by the fact that many metal-chlorides are volatile at high-temperatures while metal-silicides are generally stable. To withstand the uniquely corrosive environments, expensive alloys are often utilized, which increases the cost of final products. This work focuses on the corrosion behavior of iron, the primary component of low-cost alloys, and AISI 316L, a common low-cost stainless steel, in environments representative of industrial processes. The experiments were conducted using a customized high temperature chlorosilane corrosion system that exposed samples to an atmospheric pressure, high temperature, chlorosilane environment with variable input amounts of hydrogen, silicon tetrachloride, and hydrogen chloride plus the option of embedding samples in silicon during the exposure. Pre and post exposure sample analysis including scanning electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, and gravimetric analysis showed the surface corrosion products varied depending on the time, temperature, and environment that the samples were exposed to. Most commonly, a volatile chloride product formed first, followed by a stratified metal silicide layer. The chlorine and silicon activities in the corrosion environment were changed independently and were found to significantly alter the corrosion behavior; a phenomenon supported by computational thermodynamic equilibrium simulations. It was found that in comparable environments, the stainless steel corroded significantly less than the pure iron. This

Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures

Science.gov (United States)

Jin, Peng

Due to the law of supply and demand, the last decade has witnessed a skyrocketing in the price of light sweet crude oil. Therefore, refineries are increasingly interested in "opportunity crudes", characterized by their discounted price and relative ease of procurement. However, the attractive economics of opportunity crudes come with the disadvantage of high acid/organosulfur compound content, which could lead to corrosion and even failure of facilities in refineries. However, it is generally accepted that organosulfur compounds may form protective iron sulfide layers on the metal surface and decrease the corrosion rate. Therefore, it is necessary to investigate the corrosive property of crudes at high temperatures, the mechanism of corrosion by acids (naphthenic acids) in the presence of organosulfur compounds, and methods to mitigate its corrosive effect. In 2004, an industrial project was initiated at the Institute for Corrosion and Multiphase Technology to investigate the corrosion by naphthenic acids and organosulfur compounds. In this project, for each experiment there were two experimentation phases: pretreatment and challenge. In the first pretreatment phase, a stirred autoclave was filled with a real crude oil fraction or model oil of different acidity and organosulfur compound concentration. Then, the stirred autoclave was heated to high temperatures to examine the corrosivity of the oil to different materials (specimens made from CS and 5% Cr containing steel were used). During the pretreatment, corrosion product layers were formed on the metal surface. In the second challenge phase, the steel specimens pretreated in the first phase were inserted into a rotating cylinder autoclave, called High Velocity Rig (HVR). The HVR was fed with a high-temperature oil solution of naphthenic acids to attack the iron sulfide layers. Based on the difference of specimen weight loss between the two steps, the net corrosion rate could be calculated and the protectiveness

Design and Fabrication Technique of the Key Components for Very High Temperature Reactor

Energy Technology Data Exchange (ETDEWEB)

Lee, Ho Jin; Song, Ki Nam; Kim, Yong Wan

2006-12-15

The gas outlet temperature of Very High Temperature Reactor (VHTR) may be beyond the capability of conventional metallic materials. The requirement of the gas outlet temperature of 950 .deg. C will result in operating temperatures for metallic core components that will approach very high temperature on some cases. The materials that are capable of withstanding this temperature should be prepared, or nonmetallic materials will be required for limited components. The Ni-base alloys such as Alloy 617, Hastelloy X, XR, Incoloy 800H, and Haynes 230 are being investigated to apply them on components operated in high temperature. Currently available national and international codes and procedures are needed reviewed to design the components for HTGR/VHTR. Seven codes and procedures, including five ASME Codes and Code cases, one French code (RCC-MR), and on British Procedure (R5) were reviewed. The scope of the code and code cases needs to be expanded to include the materials with allowable temperatures of 950 .deg. C and higher. The selection of compact heat exchangers technology depends on the operating conditions such as pressure, flow rates, temperature, but also on other parameters such as fouling, corrosion, compactness, weight, maintenance and reliability. Welding, brazing, and diffusion bonding are considered proper joining processes for the heat exchanger operating in the high temperature and high pressure conditions without leakage. Because VHTRs require high temperature operations, various controlled materials, thick vessels, dissimilar metal joints, and precise controls of microstructure in weldment, the more advanced joining processes are needed than PWRs. The improved solid joining techniques are considered for the IHX fabrication. The weldability for Alloy 617 and Haynes 230 using GTAW and SMAW processes was investigated by CEA.

Design and Fabrication Technique of the Key Components for Very High Temperature Reactor

International Nuclear Information System (INIS)

Lee, Ho Jin; Song, Ki Nam; Kim, Yong Wan

2006-12-01

The gas outlet temperature of Very High Temperature Reactor (VHTR) may be beyond the capability of conventional metallic materials. The requirement of the gas outlet temperature of 950 .deg. C will result in operating temperatures for metallic core components that will approach very high temperature on some cases. The materials that are capable of withstanding this temperature should be prepared, or nonmetallic materials will be required for limited components. The Ni-base alloys such as Alloy 617, Hastelloy X, XR, Incoloy 800H, and Haynes 230 are being investigated to apply them on components operated in high temperature. Currently available national and international codes and procedures are needed reviewed to design the components for HTGR/VHTR. Seven codes and procedures, including five ASME Codes and Code cases, one French code (RCC-MR), and on British Procedure (R5) were reviewed. The scope of the code and code cases needs to be expanded to include the materials with allowable temperatures of 950 .deg. C and higher. The selection of compact heat exchangers technology depends on the operating conditions such as pressure, flow rates, temperature, but also on other parameters such as fouling, corrosion, compactness, weight, maintenance and reliability. Welding, brazing, and diffusion bonding are considered proper joining processes for the heat exchanger operating in the high temperature and high pressure conditions without leakage. Because VHTRs require high temperature operations, various controlled materials, thick vessels, dissimilar metal joints, and precise controls of microstructure in weldment, the more advanced joining processes are needed than PWRs. The improved solid joining techniques are considered for the IHX fabrication. The weldability for Alloy 617 and Haynes 230 using GTAW and SMAW processes was investigated by CEA

Corrosion of structural materials and electrochemistry in high temperature water of nuclear power systems

International Nuclear Information System (INIS)

Uchida, Shunsuke

2014-01-01

The latest experiences with corrosion in the cooling systems of nuclear power plants are reviewed. High temperature cooling water causes corrosion of structural materials, which often leads to adverse effects in the plants, e.g., generating defects in materials of major components and fuel claddings, increasing shutdown radiation and increasing the volume of radwaste sources. Corrosion behaviors are much affected by water qualities and differ according to the values of water qualities and the materials themselves. In order to establish reliable operation, each plant requires its own unique optimal water chemistry control based on careful consideration of its system, materials and operational history. Electrochemistry is one of key issues that determine corrosion related problems but it is not the only issue. Most phenomena for corrosion related problems, e.g., flow-accelerated corrosion (FAC), intergranular stress corrosion cracking (IGSCC), primary water stress corrosion cracking (PWSCC) and thinning of fuel cladding materials, can be understood based on an electrochemical index, e.g., electrochemical corrosion potential (ECP), conductivities and pH. The most important electrochemical index, ECP, can be measured at elevated temperature and applied to in situ sensors of corrosion conditions to detect anomalous conditions of structural materials at their very early stages. In the paper, theoretical models based on electrochemistry to estimate wall thinning rate of carbon steel piping due to flow-accelerated corrosion and corrosive conditions determining IGSCC crack initiation and growth rate are introduced. (author)

Corrosion behaviour of construction materials for high temperature water electrolysers

Energy Technology Data Exchange (ETDEWEB)

Nikiforov, A.; Petruchina, I.; Christensen, E.; Bjerrum, N.J.; Tomas-Garcya, A.L. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemistry, Materials Science Group

2010-07-01

This presentation reported on a study in which the feasibility of using different corrosion resistant stainless steels as a possible metallic bipolar plate and construction material was evaluated in terms of corrosion resistance under conditions corresponding to the conditions in high temperature proton exchange membrane (PEM) water electrolysers (HTPEMWE). PEM water electrolysis technology has been touted as an effective alternative to more conventional alkaline water electrolysis. Although the energy efficiency of this technology can be increased considerably at temperatures above 100 degrees C, this increases the demands to all the used materials with respect to corrosion stability and thermal stability. In this study, Ni-based alloys as well as titanium and tantalum samples were exposed to anodic polarization in 85 per cent phosphoric acid electrolyte solution. Tests were performed at 80 and 120 degrees C to determine the dependence of corrosion speed and working temperature. Platinum and gold plates were also tested for a comparative evaluation. Steady-state voltammetry was used along with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Titanium showed the poorest corrosion resistance, while Ni-based alloys showed the highest corrosion resistance, with Inconel R 625 being the most promising alloy for the bipolar plate of an HTPEMWE. 3 refs., 1 tab., 2 figs.

HTGR fuel behavior at very high temperature

International Nuclear Information System (INIS)

Kashimura, Satoru; Ogawa, Touru; Fukuda, Kousaku; Iwamoto, Kazumi

1986-03-01

Fuel behavior at very high temperature simulating abnormal transient of the reactor operation and accidents have been investigated on TRISO coating LEU oxide particle fuels at JAERI. The test simulating the abnormal transient was carried out by irradiation of loose coated particles above 1600 deg C. The irradiation test indicated that particle failure was principally caused by kernel migration. For simulation of the core heat-up accident, two experiments of out-of-pile heating were made. Survival temperature limits were measured and fuel performance at very high temperature were investigated by the heatings. Study on the fuel behavior under reactivity initiated accident was made by NSRR(Nuclear Safety Research Reactor) pulse irradiation, where maximum temperature was higher than 2800 deg C. It was found in the pulse irradiation experiments that the coated particles incorporated in the compacts did not so severely fail unlike the loose coated particles at ultra high temperature above 2800 deg C. In the former particles UO 2 material at the center of the kernel vaporized, leaving a spherical void. (author)

Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels

DEFF Research Database (Denmark)

Montgomery, Melanie; Vilhelmsen, T.; Jensen, S.A.

2007-01-01

Over the past years, considerable high temperature corrosion problems have been encountered when firing biomass in power plants due to the high content of potassium chloride in the deposits. Therefore to combat chloride corrosion problems co-firing of biomass with a fossil fuel has been undertaken....... This results in potassium chloride being converted to potassium sulphate in the combustion chamber and it is sulphate rich deposits that are deposited on the vulnerable metallic surfaces such as high temperature superheaters. Although this removes the problem of chloride corrosion, other corrosion mechanisms...... appear such as sulphidation and hot corrosion due to sulphate deposits. At Studstrup power plant Unit 4, based on trials with exposure times of 3000 hours using 0-20% straw co-firing with coal, the plant now runs with a fuel of 10% straw + coal. After three years exposure in this environment...

High Temperature Corrosion Problem of Boiler Components in presence of Sulfur and Alkali based Fuels

Science.gov (United States)

Ghosh, Debashis; Mitra, Swapan Kumar

2011-04-01

Material degradation and ageing is of particular concern for fossil fuel fired power plant components. New techniques/approaches have been explored in recent years for Residual Life assessment of aged components and material degradation due to different damage mechanism like creep, fatigue, corrosion and erosion etc. Apart from the creep, the high temperature corrosion problem in a fossil fuel fired boiler is a matter of great concern if the fuel contains sulfur, chlorine sodium, potassium and vanadium etc. This paper discusses the material degradation due to high temperature corrosion in different critical components of boiler like water wall, superheater and reheater tubes and also remedial measures to avoid the premature failure. This paper also high lights the Residual Life Assessment (RLA) methodology of the components based on high temperature fireside corrosion. of different critical components of boiler.

Effect of heat treatment conditions on stress corrosion cracking resistance of alloy X-750 in high temperature water

International Nuclear Information System (INIS)

Yonezawa, Toshio; Onimura, Kichiro; Sakamoto, Naruo; Sasaguri, Nobuya; Susukida, Hiroshi; Nakata, Hidenori.

1984-01-01

In order to improve the resistance of the Alloy X-750 in high temperature and high purity water, the authors investigated the influence of heat treatment condition on the stress corrosion cracking resistance of the alloy. This paper describes results of the stress corrosion cracking test and some discussion on the mechanism of the stress corrosion cracking of Alloy X-750 in deaerated high temperature water. The following results were obtained. (1) The stress corrosion cracking resistance of Alloy X-750 in deaerated high temperature water remarkably depended upon the heat treatment condition. The materials solution heat treated and aged within temperature ranges from 1065 to 1100 0 C and from 704 to 732 0 C, respectively, have a good resistance to the stress corrosion cracking in deaerated high temperature water. Especially, water cooling after the solution heat treatment gives an excellent resistance to the stress corrosion cracking in deaerated high temperature water. (2) Any correlations were not observed between the stress corrosion cracking susceptibility of Alloy X-750 in deaerated high temperature water and grain boundary chromium depleted zones, precipitate free zones and the grain boundary segregation of impurity elements and so on. It appears that there are good correlations between the stress corrosion cracking resistance of the alloy in the environment and the kinds, morphology and coherency of precipitates along the grain boundaries. (author)

Corrosion tests of high temperature alloys in impure helium

International Nuclear Information System (INIS)

Berka, Jan; Kalivodova, Jana; Vilemova, Monika; Skoumalova, Zuzana; Brabec, Petr

2014-01-01

Czech research organizations take part several projects concerning technologies and materials for advanced gas cooled reactors, as an example international project ARCHER supported by EU within FP7, also several national projects supported by Technology Agency of the Czech Republic are solved in cooperation with industrial and research organization. Within these projects the material testing program is performed. The results presented in these paper concerning high temperature corrosion and degradation of alloys (800 H, SS 316 and P91) in helium containing minor impurities (H_2, CO, CH_4, HZO) at temperatures up to 760°C. After corrosion tests (up to 1500 hours) the specimens was investigated by several methods (gravimetry, SEM-EDX, optical microscopy, hardness and micro-hardness testing etc. (author)

Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels

DEFF Research Database (Denmark)

Montgomery, Melanie; Vilhelmsen, T.; Jensen, S.A.

2008-01-01

Over the past few years, considerable high temperature corrosion problems have been encountered when firing biomass in power plants due to the high content of potassium chloride in the deposits. Therefore, to combat chloride corrosion problems cofiring of biomass with a fossil fuel has been...... undertaken. This results in potassium chloride being converted to potassium sulphate in the combustion chamber and it is sulphate rich deposits that are deposited on the vulnerable metallic surfaces such as high temperature superheaters. Although this removes the problem of chloride corrosion, other...... corrosion mechanisms appear such as sulphidation and hot corrosion due to sulphate deposits. At Studstrup power plant Unit 4, based on trials with exposure times of 3000 h using 0–20% straw co-firing with coal, the plant now runs with a fuel mix of 10% strawþcoal. Based on results from a 3 years exposure...

Resistance of various coatings to high temperature corrosion in HCl and SO{sub 2} containing environments

Energy Technology Data Exchange (ETDEWEB)

Cizner, Josef; Mlnarik, Jakub; Hruska, Jan [SVUM a.s., Prague (Czech Republic). Lab. of High Temperature Corrosion

2010-07-01

For high efficiency of the steam turbines it is necessary to produce steam of temperature at least 400 C, which in conjunction with specific composition of combustion gases causes fireside corrosion problems. The combustion gases contain aggressive compounds ike HCl and SO{sub 2} and some other elements which can form deposits on heat exchanging surfaces e.g. calcium, potassium salts etc. Using of high-alloy steels or nickel-based alloys is very costly and also these materials could have lower thermal conductivity. A cheaper solution is to produce a coating on low (medium)-alloy steel. Common heat-resistant steels show very short lifetime under these conditions. The solution is then to use the appropriate coatings. Some types of coatings can be applied even inside older boilers. In this work we tested many coatings composition (nickel-based, aluminium-based etc. As well as with different processing method - arc sprayed coating, weld deposits, HVOF, etc.) on 16Mo3 steel. In particular their high temperature corrosion behaviour in model atmosphere containing SO{sub 2} and HCl and also under deposit of fly ash was studied. (orig.)

High Temperature Corrosion on Biodust Firing

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi

The high content of alkali metals and chlorine in biomass gives rise to fouling/slagging and corrosion of heat exchange components, such as superheaters, in biomass fired power plants. Increasing the lifetime of these components, and in addition, preventing unwarranted plant shutdowns due...... to their failure, requires understanding of the complex corrosion mechanisms, as well as development of materials that are resistant to corrosion under biomass firing conditions, thereby motivating the current work. To understand the mechanisms of corrosion attack, comprehensive analysis of corrosion products...... by the combined use of complementary information from microscopy, energy dispersive X-ray spectroscopy and various X-ray diffraction characterization techniques. In light of the wide variation in operating conditions in biomass fired power plants, systematic and well-controlled, but realistic laboratory scale...

Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

Science.gov (United States)

Oksa, M.; Metsäjoki, J.; Kärki, J.

2015-01-01

There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

Intergranular corrosion of 13Cr and 17Cr martensitic stainless steels in accelerated corrosive solution and high-temperature, high-purity water

International Nuclear Information System (INIS)

Ozaki, Toshinori; Ishikawa, Yuichi

1988-01-01

Intergranular corrosion behavior of 13Cr and 17Cr martensitic stainless steels was studied by electrochemical and immersing corrosion tests. Effects of the mEtallurgical and environmental conditions on the intergranular corrosion of various tempered steels were examined by the following tests and discussed. (a) Anodic polarization measurement and electrolytical etching test in 0.5 kmol/m 3 H 2 SO 4 solution at 293 K. (b) Immersion corrosion test in 0.88 kmol/m 3 HNO 3 solution at 293 K. (c) Long-time immersion test for specimens with a crevice in a high purity water at 473 K∼561 K. It was found from the anodic polarization curves in 0.5 kmol/m 3 H 2 SO 4 solution-at 293 K that the steels tempered at 773∼873 K had susceptibility to intergranular corrosion in the potential region indicating a second current maximum (around-0.1 V. vs. SCE). But the steel became passive in the more noble potential region than the second current peak potential, while in the less noble potential region general corrosion occurred independent of its microstructure. The intergranular corrosion occurred due to the localized dissolution along the pre-austenitic grain boundary and the martensitic lath boundary. It could be explained by the same dissolution model of the chromium depleted zone as proposed for the intergranular corrosion of austenitic and ferritic stainless steels. The intergranular corrosion occurred entirely at the free surface in 0.88 kmol/m 3 HNO 3 solution, while in the high temperature and high purity water only the entrance of the crevice corroded. It was also suggested that this intergranular corrosion might serve as the initiation site for stress corrosion cracking of the martensitic stainless steel. (author)

High temperature materials

International Nuclear Information System (INIS)

2003-01-01

The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

Nuclear fuels for very high temperature applications

International Nuclear Information System (INIS)

Lundberg, L.B.; Hobbins, R.R.

1992-01-01

The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO 2 or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures

Corrosion behavior of low energy, high temperature nitrogen ion ...

Indian Academy of Sciences (India)

Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel. M GHORANNEVISS1, A SHOKOUHY1,∗, M M LARIJANI1,2,. S H HAJI HOSSEINI 1, M YARI1, A ANVARI4, M GHOLIPUR SHAHRAKI1,3,. A H SARI1 and M R HANTEHZADEH1. 1Plasma Physics Research Center, Science ...

Research and development on is process components for hydrogen production. (2) Corrosion resistance of glass lining in high temperature sulfuric acid

International Nuclear Information System (INIS)

Tanaka, Nobuyuki; Iwatsuki, Jin; Kubo, Shinji; Terada, Atsuhiko; Onuki, Kaoru

2009-01-01

Japan Atomic Energy Agency has been conducting a research and development on hydrogen production system using High Temperature Gas-Cooled Reactor. As a part of this effort, thermochemical water-splitting cycle featuring iodine- and sulfur-compounds (IS process) is under development considering its potential of large-scale economical hydrogen production. The IS process constitutes very severe environments on the materials of construction because of the corrosive nature of process chemicals, especially of the high temperature acidic solution of sulfuric acid and hydriodic acid dissolving iodine. Therefore, selection of the corrosion-resistant materials and development of the components has been studied as a crucial subject of the process development. This paper discusses corrosion resistance of commercially available glass-lining material in high temperature sulfuric acid. Corrosion resistance of a soda glass used for glass-lining was examined by immersion tests. The experiments were performed in 47-90wt% sulfuric acids at temperatures of up to 400degC and for the maximum immersion time of 100 hours using an autoclave designed for the concerned tests. In every condition tested, no indication of localized corrosion such as defect formation or pitting corrosion was observed. Also, the corrosion rates decreased with the progress of immersion, and were low enough (≅0.1 mm/year) after 60-90 hours of immersion probably due to formation of a silica rich surface. (author)

High temperature corrosion during biomass firing: improved understanding by depth resolved characterisation of corrosion products

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

2015-01-01

changes within the near surface region (covering both the deposit and the steel surface). Such cross-section analysis was further complemented by plan view investigations (additionally involving X-ray diffraction) combined with removal of the corrosion products. Improved insights into the nature......The high temperature corrosion of an austenitic stainless steel (TP 347H FG), widely utilised as a superheater tube material in Danish power stations, was investigated to verify the corrosion mechanisms related to biomass firing. KCl coated samples were exposed isothermally to 560 degrees C...... of the corrosion products as a function of distance from the deposit surface were revealed through this comprehensive characterisation. Corrosion attack during simulated straw-firing conditions was observed to occur through both active oxidation and sulphidation mechanisms....

The corrosion rate measurement of Inconel 690 on high temperature and pressure by using CMS100

International Nuclear Information System (INIS)

Sriyono; Satmoko, Ari; Febrianto; Hidayati, N R; Arifal; Sumarno, Ady; Handoyo, Ismu; Prasetjo, Joko

1999-01-01

The corrosion rate measurement of Inconel 690 on high temperature and pressure had been done. By using an Autoclave, and temperature can be simulated. For reducing the pressure on Autoclave so its can be measure by Corrosion Measurement System 100(CMS100), the electrodes placement had designed and fabrication on the cover of Autoclave. The electrodes of CMS100 are reference electrode, working electrodes and counter electrodes. The electrodes placement are made and and designed on two packages, these are Salt bridge and Counter-specimen placement. From the result of testing these both of placement are able to 90 bar (pressure) and 280 C (temperature) operation rate measurement was done on temperature variation from 150 0C, 190 0C, 200 0C, 210 0C, 220 0C and 230 0C, and the solution is 0.1 ppm chloride. The pressure experiment is the pressure, which occurred in Autoclave. From the Tafel analysis, even through very little The corrosion current increased from 150 C to 230 C it is 2,54x10-10 a/cm2 to 1,62x10-9 A/cm2, but the the corrosion rate is still zero

General and localized corrosion of carbon and low-alloy steels in oxygenated high-temperature water. Final report

International Nuclear Information System (INIS)

Macdonald, D.D.; Smialowska, S.; Pednekar, S.

1983-02-01

The susceptibilities to stress corrosion cracking (SCC) of two carbon steels, SA106-grB and SA333-gr6, which are used in seamless BWR piping, and a low-alloy pressure vessel steel, A508-C12, were studied in high purity water as a function of oxygen concentration (0.16 to 8 ppM) and temperature (50 to 288 0 C) . The susceptibility to SCC was measured using the slow strain rate technique. The fracture surfaces of the test specimens were also examined using SEM to determine the mode of failure. In water containing 1 and 8 ppM oxygen and at temperatures above 135 0 C, transgranular stress corrosion cracking (TGSCC) was observed to occur in A508-C12, SA333-gr6 and SA106grB steels at very high stresses. The susceptibility to SCC increased with temperature

Solubility of corrosion products in high temperature water

International Nuclear Information System (INIS)

Srinivasan, M.P.; Narasimhan, S.V.

1995-01-01

A short review of solubility of corrosion products at high temperature in either neutral or alkaline water as encountered in BWR, PHWR and PWR primary coolant reactor circuits is presented in this report. Based on the available literature, various experimental techniques involved in the study of the solubility, theory for fitting the solubility data to the thermodynamic model and discussion of the published results with a scope for future work have been brought out. (author). 17 refs., 7 figs

An assessment of thermal spray coating technologies for high temperature corrosion protection

International Nuclear Information System (INIS)

Heath, G.R.; Heimgartner, P.; Gustafsson, S.; Irons, G.; Miller, R.

1997-01-01

The use of thermally sprayed coatings in combating high temperature corrosion continues to grow in the major industries of chemical, waste incineration, power generation and pulp and paper. This has been driven partially by the development of corrosion resistant alloys, improved knowledge and quality in the thermal spray industry and continued innovation in thermal spray equipment. There exists today an extensive range of thermal spray process options, often with the same alloy solution. In demanding corrosion applications it is not sufficient to just specify alloy and coating method. For the production of reliable coatings the whole coating production envelope needs to be considered, including alloy selection, spray parameters, surface preparation, base metal properties, heat input etc. Combustion, arc-wire, plasma, HVOF and spray+fuse techniques are reviewed and compared in terms of their strengths and limitations to provide cost-effective solutions for high temperature corrosion protection. Arc wire spraying, HP/HVOF and spray+fuse are emerging as the most promising techniques to optimise both coating properties and economic/practical aspects. (orig.)

In-situ electrochemical study of Zr1nb alloy corrosion in high temperature Li{sup +} containing water

Energy Technology Data Exchange (ETDEWEB)

Krausová, Aneta [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Macák, Jan, E-mail: macakj@vscht.cz [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Sajdl, Petr [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Novotný, Radek [JRC-IET, Westerduinveg 3, 1755 LE Petten (Netherlands); Renčiuková, Veronika [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Vrtílková, Věra [ÚJP a.s., Nad Kamínkou 1345, 156 10 Prague 5 (Czech Republic)

2015-12-15

Long-term in-situ corrosion tests were performed in order to evaluate the influence of lithium ions on the corrosion of zirconium alloy. Experiments were carried out in a high-pressure high-temperature loop (280 °C, 8 MPa) in a high concentration water solution of LiOH (70 and 200 ppm Li{sup +}) and in a simulated WWER primary coolant environment. The kinetic parameters characterising the oxidation process have been explored using in-situ electrochemical impedance spectroscopy and slow potentiodynamic polarization. Also, a suitable equivalent circuit was suggested, which would approximate the impedance characteristics of the corrosion of Zr–1Nb alloy. The Mott–Schottky approach was used to determine the semiconducting character of the passive film. - Highlights: • Zr1Nb alloy was tested in WWER coolant and in LiOH solutions at 280 °C. • Corrosion rates were estimated in-situ from electrochemical data. • Electrochemical data agreed well with weight gains and metallography data. • Increase of corrosion rate in LiOH appeared after short exposure (300–500 h). • Very high donor densities (1.1–1.2 × 10{sup 20} cm{sup −3}) of Zr oxide grown in LiOH were found.

Conjugate-Gradient Neural Networks in Classification of Multisource and Very-High-Dimensional Remote Sensing Data

Science.gov (United States)

Benediktsson, J. A.; Swain, P. H.; Ersoy, O. K.

1993-01-01

Application of neural networks to classification of remote sensing data is discussed. Conventional two-layer backpropagation is found to give good results in classification of remote sensing data but is not efficient in training. A more efficient variant, based on conjugate-gradient optimization, is used for classification of multisource remote sensing and geographic data and very-high-dimensional data. The conjugate-gradient neural networks give excellent performance in classification of multisource data, but do not compare as well with statistical methods in classification of very-high-dimentional data.

High Temperature Corrosion of Nickel in NaVO3-V2O5 Melts

Directory of Open Access Journals (Sweden)

J. Porcayo-Calderon

2017-01-01

Full Text Available Many alloys used at high temperature in industrial processes are Ni-based and many others contain it in appreciable quantities, so it is of interest to evaluate the performance of pure nickel in order to determine the behavior of its alloys once the elements responsible for their protection have been depleted due to accelerated corrosion processes in the presence of vanadium-rich molten salts. Due to this, this work presents the study of Ni behavior in NaVO3-V2O5 mixtures at different temperatures. The behavior of pure nickel was determined by both electrochemical and mass loss measurements. The results show that the aggressiveness of the vanadium salts is increased by increasing both the V2O5 content and temperature. V2O5 addition considerably increases the current densities of the anodic and cathodic reactions. The corrosion process of Ni is modified due to the presence of its corrosion products, and its presence increases the activation energy by at least one order of magnitude. Although nickel shows a high reactivity in vanadium-rich salts, its reaction products are highly stable and protect it from the corrosive medium because the corrosion reactions trap the vanadium and block the migration of nickel ions.

Corrosion of high temperature alloys in the primary circuit helium of high temperature gas cooled reactors. Pt. 2

International Nuclear Information System (INIS)

Quadakkers, W.J.

1985-01-01

The reactive impurities H 2 O, CO, H 2 and CH 4 which are present in the primary coolant helium of high temperature gas-cooled reactors can cause scale formation, internal oxidation and carburization or decarburization of the high temperature structural alloys. In Part 1 of this contribution a theoretical model was presented, which allows the explanation and prediction of the observed corrosion effects. The model is based on a classical stability diagram for chromium, modified to account for deviations from equilibrium conditions caused by kinetic factors. In this paper it is shown how a stability diagram for a commercial alloy can be constructed and how this can be used to correlate the corrosion results with the main experimental parameters, temperature, gas and alloy composition. Using the theoretical model and the presented experimental results, conditions are derived under which a protective chromia based surface scale will be formed which prevents a rapid transfer of carbon between alloy and gas atmosphere. It is shown that this protective surface oxide can only be formed if the carbon monoxide pressure in the gas exceeds a critical value. Psub(CO), which depends on temperature and alloy composition. Additions of methane only have a limited effect provided that the methane/water ratio is not near to, or greater than, a critical value of around 100/1. The influence of minor alloying additions of strong oxide forming elements, commonly present in high temperature alloys, on the protective properties of the chromia surface scales and the kinetics of carbon transfer is illustrated. (orig.) [de

Effect of water chemistry on corrosion of stainless steel and deposition of corrosion products in high temperature pressurised water

International Nuclear Information System (INIS)

Morrison, Jonathan; Cooper, Christopher; Ponton, Clive; Connolly, Brian; Banks, Andrew

2012-09-01

In any water-cooled nuclear reactor, the corrosion of the structural materials in contact with the coolant and the deposition of the resulting oxidised species has long been an operational concern within the power generation industry. Corrosion of the structural materials at all points in the reactor leads to low concentrations of oxidised metal species in the coolant water. The oxidised metal species can subsequently be deposited out as CRUD deposits at various points around the reactor's primary and secondary loops. The deposition of soluble oxidised material at any location in the reactor cooling system is undesirable due to several effects; deposits have a porous structure, capable of incorporating radiologically active material (forming out of core radiation fields) and concentrating aggressively corrosive chemicals, which exacerbate environmental degradation of structural and fuel-cladding materials. Deposits on heat transfer surfaces also limit efficiency of the system as a whole. The work in this programme is an attempt to determine and understand the fundamental corrosion and deposition behaviour under controlled, simulated reactor conditions. The rates of corrosion of structural materials within pressurised water reactors are heavily dependent on the condition of the exposed surface. The effect of mechanical grinding and of electropolishing on the corrosion rate and structure of the resultant oxide film formed on grade 316L stainless steel exposed to high purity water, modified to pH 9.5 and 10.5 at temperatures between 200 and 300 deg. C and pressures of up to 100 bar will be investigated. The corrosion of stainless steel in water via electrochemical oxidation leads to the formation of surface iron, nickel and chromium based spinels. Low concentrations of these spinels can be found dissolved in the coolant water. The solubility of magnetite, stainless steels' major corrosion product, in high purity water will be studied at pH 9.5 to 10.5 at

Phase Stability Diagrams for High Temperature Corrosion Processes

Directory of Open Access Journals (Sweden)

J. J. Ramos-Hernandez

2013-01-01

Full Text Available Corrosion phenomena of metals by fused salts depend on chemical composition of the melt and environmental conditions of the system. Detail knowledge of chemistry and thermodynamic of aggressive species formed during the corrosion process is essential for a better understanding of materials degradation exposed to high temperature. When there is a lack of kinetic data for the corrosion processes, an alternative to understand the thermodynamic behavior of chemical species is to utilize phase stability diagrams. Nowadays, there are several specialized software programs to calculate phase stability diagrams. These programs are based on thermodynamics of chemical reactions. Using a thermodynamic data base allows the calculation of different types of phase diagrams. However, sometimes it is difficult to have access to such data bases. In this work, an alternative way to calculate phase stability diagrams is presented. The work is exemplified in the Na-V-S-O and Al-Na-V-S-O systems. This system was chosen because vanadium salts is one of the more aggressive system for all engineering alloys, especially in those processes where fossil fuels are used.

Effect of high temperature filtration on out-core corrosion product activity

International Nuclear Information System (INIS)

Horvath, G.L.; Bogancs, J.

1983-01-01

Investigation of the effect of high temperature filtration on corrosion product transport and out-core corrosion product activity has been carried out for VVER-440 plants. In the physico-chemical model applied particulate and dissolved corrosion products were taken into account. We supposed 100% effectivity for the particulate filter. It was found that about 0,5% 160 t/h/ of the main flow would result in an approx.50% reduction of the out-core corrosion product activity. Investigation of the details of the physico-chemical model in Nuclear Power Plant Paks showed a particle deposition rate measured during power transients fairly agreeing with other measurements and data used in the calculations. (author)

Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L.

1996-09-01

Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

Science.gov (United States)

Gannon, Paul; Amendola, Roberta

2012-12-01

High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

Influence of yttria surface modification on high temperature corrosion of porous Ni22Cr alloy

DEFF Research Database (Denmark)

Karczewski, Jakub; Dunst, Katarzyna; Jasinski, Piotr

2017-01-01

Protective coatings for porous alloys for high temperature use are relatively new materials. Their main drawback is high temperature corrosion. In this work protective coatings based the on Y-precursor infiltrated into the sintered Ni22Cr alloys are studied at 700°C. Effects of the amount...... of the protective phase on the resulting corrosion properties are evaluated in air and humidified hydrogen. Weight gain of the samples, their open porosities and microstructures are analyzed and compared. Results show, that by the addition of even a minor amount of the Y-precursor corrosion rates can be decreased...

Topographical, microstructural, and chemical effects of simulated high heat flux on the corrosion of Type 316 stainless steel in flowing sodium

International Nuclear Information System (INIS)

Bagnall, C.; Shiels, S.A.; Orbon, S.J.

1976-01-01

Earlier work, performed in sodium test facilities around the world, have produced corrosion data for Type 306 SS which has been used to estimate metal loss rates from the core of a LMFBR. Practical difficulties precluded evaluation of the influence on corrosion of irradiation, a high heat flux and the high axial temperature gradient the latter produces. Downstream effects in isothermal regions were, however, documented in some tests. This paper presents recent results of corrosion experiments conducted in a test facility designed to produce a temperature rise in the fluid equivalent to a heat flux in the primary heater of about 0.5 x 10 6 Btu/(h-ft 2 ). The axial temperature gradient was such that the sodium temperature was increased over a distance of three feet from 820F at the inlet, to 1360F at the outlet. The secondary ion mass spectrometer, electron probe microanalyzer, scanning electron microscope, and optical microscope were used individually to characterize the various compositional, topographical, and structural changes that occurred in the stainless steel as a result of the sodium exposure. Several important effects attributable to the high axial temperature gradient were noted

Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

International Nuclear Information System (INIS)

Liu, Yan; Xu, Lining; Lu, Minxu; Meng, Yao; Zhu, Jinyang; Zhang, Lei

2014-01-01

Highlights: • The corrosion behavior of 13Cr steel exposed to bromine salt completion fluid containing high concentration bromine ions was investigated. • There are passive circles around pits on the 13Cr steel surface after 7 d of exposure. • Macroscopic galvanic corrosion formed between the passive halo and the pit. • The mechanism of pitting corrosion on 13Cr stainless steel exposed to heavy bromine brine was established. - Abstract: A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH − ligand generates and adsorbs in a certain scale because of abundant OH − on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs

Corrosion aspects of high-level waste disposal in salt domes

International Nuclear Information System (INIS)

Roerbo, K.

1979-12-01

In the ELSAM/ELKRAT waste management project it is planned that the high-level waste is glassified, encapsuled in canisters and finally deposited in a deep hole drilled in a salt dome. In the present report corrosion aspects of the canisters after deposition are discussed. The chemical environment will probably be a limited amount of brine coming from brine inclusions in the surrounding salt and moving up against the temperature gradient, the temperature at the canister surface being in the range of 100-150degC. The possible types of corrosion and the expected corrosion rates for a number of potential canister materials (mild steel, austenitic and ferritic stainless steels, Ni-base alloys, copper, titanium and a few combinations of materials) are discussed. Mild steel (possibly combined with an inner layer of copper or titanium) might possibly be an appropriate choice of material for the canister. (author)

Responses of Microbial Community Composition to Temperature Gradient and Carbon Steel Corrosion in Production Water of Petroleum Reservoir

Directory of Open Access Journals (Sweden)

Xiao-Xiao Li

2017-12-01

Full Text Available Oil reservoir production systems are usually associated with a temperature gradient and oil production facilities frequently suffer from pipeline corrosion failures. Both bacteria and archaea potentially contribute to biocorrosion of the oil production equipment. Here the response of microbial populations from the petroleum reservoir to temperature gradient and corrosion of carbon steel coupons were investigated under laboratory condition. Carbon steel coupons were exposed to production water from a depth of 1809 m of Jiangsu petroleum reservoir (China and incubated for periods of 160 and 300 days. The incubation temperatures were set at 37, 55, and 65°C to monitoring mesophilic, thermophilic and hyperthermophilic microorganisms associated with anaerobic carbon steel corrosion. The results showed that corrosion rate at 55°C (0.162 ± 0.013 mm year-1 and 37°C (0.138 ± 0.008 mm year-1 were higher than that at 65°C (0.105 ± 0.007 mm year-1, and a dense biofilm was observed on the surface of coupons under all biotic incubations. The microbial community analysis suggests a high frequency of bacterial taxa associated with families Porphyromonadaceae, Enterobacteriaceae, and Spirochaetaceae at all three temperatures. While the majority of known sulfate-reducing bacteria, in particular Desulfotignum, Desulfobulbus and Desulfovibrio spp., were predominantly observed at 37°C; Desulfotomaculum spp., Thermotoga spp. and Thermanaeromonas spp. as well as archaeal members closely related to Thermococcus and Archaeoglobus spp. were substantially enriched at 65°C. Hydrogenotrophic methanogens of the family Methanobacteriaceae were dominant at both 37 and 55°C; acetoclastic Methanosaeta spp. and methyltrophic Methanolobus spp. were enriched at 37°C. These observations show that temperature changes significantly alter the microbial community structure in production fluids and also affected the biocorrosion of carbon steel under anaerobic conditions.

High Accuracy, Miniature Pressure Sensor for Very High Temperatures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — SiWave proposes to develop a compact, low-cost MEMS-based pressure sensor for very high temperatures and low pressures in hypersonic wind tunnels. Most currently...

High-Temperature Oxidation and Smelt Deposit Corrosion of Ni-Cr-Ti Arc-Sprayed Coatings

Science.gov (United States)

Matthews, S.; Schweizer, M.

2013-08-01

High Cr content Ni-Cr-Ti arc-sprayed coatings have been extensively applied to mitigate corrosion in black liquor recovery boilers in the pulp and paper industry. In a previous article, the effects of key spray parameters on the coating's microstructure and its composition were investigated. Three coating microstructures were selected from that previous study to produce a dense, oxidized coating (coating A), a porous, low oxide content coating (coating B), and an optimized coating (coating C) for corrosion testing. Isothermal oxidation trials were performed in air at 550 and 900 °C for 30 days. Additional trials were performed under industrial smelt deposits at 400 and 800 °C for 30 days. The effect of the variation in coating microstructure on the oxidation and smelt's corrosion response was investigated through the characterization of the surface corrosion products, and the internal coating microstructural developments with time at high temperature. The effect of long-term, high-temperature exposure on the interaction between the coating and substrate was characterized, and the mechanism of interdiffusion was discussed.

High temperature corrosion under conditions simulating biomass firing: depth-resolved phase identification

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

2014-01-01

) were coated with KCl and is o-thermally exposed at 560 o C for 168 h under a flue gas corresponding to straw firing. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD) characterization techniques were employed for comprehensive characterization......Both cross-sectional and plan view, ‘top-down’ characterization methods were employed , for a depth-resolved characterization of corrosion products resulting from high temperature corrosion under laboratory conditions simulating biomass firing. Samples of an austenitic stainless steel (TP 347H FG...... of the corrosion product. Results from this comprehensive characterization revealed more details on the morphology and composition of the corrosion product....

Studies of the corrosion and cracking behavior of steels in high temperature water by electrochemical techniques

International Nuclear Information System (INIS)

Cheng, Y.F.; Bullerwell, J.; Steward, F.R.

2003-01-01

Electrochemical methods were used to study the corrosion and cracking behavior of five Fe-Cr alloy steels and 304L stainless steel in high temperature water. A layer of magnetite film forms on the metal surface, which decreases the corrosion rate in high temperature water. Passivity can be achieved on A-106 B carbon steel with a small content of chromium, which cannot be passivated at room temperature. The formation rate and the stability of the passive film (magnetite film) increased with increasing Cr-content in the steels. A mechanistic model was developed to simulate the corrosion and cracking processes of steels in high temperature water. The crack growth rate on steels was calculated from the maximum current of the repassivation current curves according to the slip-oxidation model. The highest crack growth rate was found for 304L stainless steel in high temperature water. Of the four Fe-Cr alloys, the crack growth rate was lower on 0.236% Cr- and 0.33% Cr-steels than on 0.406% Cr-steel and 2.5% Cr-1% Mo steel. The crack growth rate on 0.33% Cr-steel was the smallest over the tested potential range. A higher temperature of the electrolyte led to a higher rate of electrochemical dissolution of steel and a higher susceptibility of steel to cracking, as shown by the positive increase of the electrochemical potential. An increase in Cr-content in the steel is predicted to reduce the corrosion rate of steel at high temperatures. However, this increase in Cr-content is predicted not to reduce the susceptibility of steel to cracking at high temperatures. (author)

High temperature materials; Materiaux a hautes temperatures

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-07-01

The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

The development of an adsorbent for corrosion products in high-temperature water

International Nuclear Information System (INIS)

Kim, Yong Ik; Sung, Ki Woung; Kim, Kwang Rag; Kim, Yu Hwan; Koo, Jae Hyoo

1996-08-01

In order to use as adsorbent for removal of the soluble corrosion products, mainly Co 60 under PWR reactor coolant conditions (300 deg C, 160 kg/cm 2 ), stable ZrO 2 adsorbent was prepared using sol-gel process from zirconyl nitrate, AlO adsorbent was prepared by hydrolysis of aluminum isopropoxide, and titanium tetraisopropoxide, respectively. The prepared adsorbents were calcined at various temperature and analyzed by physical properties and the Co 2+ adsorption capacity. And it was shown that the Co 2+ adsorption capacity of the TiO 2 -Al 2 O 3 adsorbents were found to have larger than that of ZrO 2 and Al 2 O 3 adsorbents in high-temperature water. ZrO 2 , Al 2 O 3 and TiO 2 -Al 2 O 3 adsorbents were found to be suitable high-temperature adsorbents for the removal of dissolved corrosion products, mainly Co in PWR reactor coolant conditions. 15 tabs., 51 figs., 55 refs. (Author)

Effect of dissolved hydrogen on corrosion of 316NG stainless steel in high temperature water

Energy Technology Data Exchange (ETDEWEB)

Dong, Lijin [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China); Peng, Qunjia, E-mail: qunjiapeng@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Shoji, Tetsuo [Frontier Research Initiative, New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Han, En-Hou; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Wang, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China)

2015-12-15

Highlights: • Dissolved hydrogen (DH) effect on corrosion of stainless steel in high temperature water. • Increasing DH caused decrease of Cr- but increase of Fe-concentrations in the inner oxide layer. • Concentration gradient of Cr and Fe in the inner oxide layer. • DH effect was attributed to the accelerated diffusion of Fe ion in the inner oxide layer. - Abstract: Characterizations of oxide films formed on 316 stainless steel in high temperature, hydrogenated water were conducted. The results show the oxide film consists of an outer layer with oxide particles of Fe–Ni spinel and hematite, and an inner continuous layer of Fe–Cr–Ni spinel. Increasing dissolved hydrogen (DH) concentrations causes decrease of Cr- and increase of Fe-concentrations in the inner layer. A continuous decrease of Cr- and increase of Fe-concentrations was observed from the surface of the inner layer to the oxide/substrate interface. The DH effect is attributed to the enhanced diffusion of Fe ions in the oxide film by hydrogen.

High temperature corrosion behaviour of a new Ni-30Fe-10Ar-Cr-alloy

International Nuclear Information System (INIS)

Kloewer, J.; Sauthoff, G.

1997-01-01

The high temperature corrosion behaviour of a new duplex nickel-base alloy containing about 30 mass% iron, 10 mass% aluminium and 8 mass% chromium was determined in both air and hot process gases containing methane/hydrogen, sulphur dioxide and hydrogen sulphide, respectively. It was found that the corrosion resistance against carburisation, sulphidation and oxidation was excellent due to the formation of a dense, protective alumina scale. The adherence of the alumina scale was increased by an addition of 0.1 mass% hafnium. The concentration of chromium was found to have a remarkable impact on the oxidation and high temperature corrosion resistance. Alloys without chromium showed increased corrosion rates in both air and sulphur-containing gas atmospheres due to the initial formation of nickel oxides. In sulphidising SO 2 -and H 2 S- containing gases at least 4 mass% chromium are required to stabilise the formation of alumina and to prevent the formation of nickel/sulphur compounds. (orig.)

Very high temperature chemistry: Science justification for containerless experimentation in space

Science.gov (United States)

Hofmeister, William H.; Nordine, Paul

1990-01-01

A summary is presented of the justification for application of containerless processing in space to high temperature science. Low earth orbit offers a gravitational environment that allows samples to be positioned in an experimental apparatus by very small forces. Well controlled experiments become possible on reactive materials at high temperatures in a reasonably quiescent state and without container contamination. This provides an opportunity to advance the science of high temperature chemistry that can only be realized with a commitment by NASA to provide advanced facilities for in-space containerless study of materials at very high temperature.

Lifetime evaluation of superheater tubes exposed to steam oxidation, high temperature corrosion and creep

Energy Technology Data Exchange (ETDEWEB)

Henriksen, N [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark); Hede Larsen, O; Blum, R [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark)

1996-12-01

Advanced fossil fired plants operating at high steam temperatures require careful design of the superheaters. The German TRD design code normally used in Denmark is not precise enough for the design of superheaters with long lifetimes. The authors have developed a computer program to be used in the evaluation of superheater tube lifetime based on input related to tube dimensions, material, pressure, steam temperature, mass flux, heat flux and estimated corrosion rates. The program is described in the paper. As far as practically feasible, the model seems to give a true picture of the reality. For superheaters exposed to high heat fluxes or low internal heat transfer coefficients as is the case for superheaters located in fluidized bed environments or radiant environments, the program has been extremely useful for evaluation of surface temperature, oxide formation and lifetime. The total uncertainty of the method is mainly influenced by the uncertainty of the determination of the corrosion rate. More precise models describing the corrosion rate as a function of tube surface temperature, fuel parameters and boiler parameters need to be developed. (au) 21 refs.

Effects of metallurgical factors on stress corrosion cracking of Ni-base alloys in high temperature water

International Nuclear Information System (INIS)

Yonezawa, T.; Sasaguri, N.; Onimura, K.

1988-01-01

Nickel-base Alloy 600 is the principal material used for the steam generator tubes of PWRs. Generally, this alloy has been proven to be satisfactory for this application, however when it is subjected to extremely high stress level in PWR primary water, it may suffer from stress corrosion cracking. The authors have systematically studied the effects of test temperature and such metallurgical factors as cold working, chemical composition and heat treatment on the stress corrosion cracking of Alloy 600 in high temperature water, and also on that of Alloy 690 which is a promising material for the tubes and may provide improved crrosion resistance for steam generators. The test materials, the stress corrosion cracking test and the test results are reported. When the test temperature was raise, the stress corrosion cracking of the nickel-base alloys was accelerated. The time of stress corrosion cracking occurrence decreased with increasing applied stress, and it occurred at the stress level higher than the 0.2 % offset proof stress of Alloy 600. In Alloy 690, stress corrosion cracking was not observed at such stress level. Cold worked Alloy 600 showed higher resistance to stress corrosion cracking than the annealed alloy. (Kako, I.)

Center of Competence in High Temperature Corrosion, HTC. Report of activities during stage 3, 2000-10-01--2003-12-31

Energy Technology Data Exchange (ETDEWEB)

Johansson, Lars-Gunnar [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Inorganic Chemistry

2004-09-01

HTC, the Swedish High Temperature Corrosion Centre, is a Swedish national competence centre jointly financed by the Swedish National Energy Agency, Chalmers Univ. of Technology and twelve member companies. HTC research has the following objectives: Improved materials performance resulting in increased service life of installations leading to lower maintenance and repair costs. Improved process performance resulting in improved energy efficiency and decreased emissions to the environment To achieve this, HTC aims to establish new and fundamental knowledge on High-Temperature Corrosion. The following research themes are pursued: High temperature corrosion in combustion gases and under deposits; Interaction of corrosion and mechanical factors such as erosion and fatigue. Main achievements during stage 3: HTC is at the cutting edge of science in certain areas of high temperature corrosion research. e.g., on the effect of water vapor on the corrosion of FeCr alloys, on the oxidation of platinum aluminide coatings and on the kinetics of the reactions at the oxide-gas interface.

Tensile stress corrosion cracking of type 304 stainless steel irradiated to very high dose

Energy Technology Data Exchange (ETDEWEB)

Chung, H. M.; Ruther, W. E.; Strain, R. V.; Shack, W. J.

2001-09-01

Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to {approximately}50 dpa at {approximately}370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility.

Development of self-powered wireless high temperature electrochemical sensor for in situ corrosion monitoring of coal-fired power plant.

Science.gov (United States)

Aung, Naing Naing; Crowe, Edward; Liu, Xingbo

2015-03-01

Reliable wireless high temperature electrochemical sensor technology is needed to provide in situ corrosion information for optimal predictive maintenance to ensure a high level of operational effectiveness under the harsh conditions present in coal-fired power generation systems. This research highlights the effectiveness of our novel high temperature electrochemical sensor for in situ coal ash hot corrosion monitoring in combination with the application of wireless communication and an energy harvesting thermoelectric generator (TEG). This self-powered sensor demonstrates the successful wireless transmission of both corrosion potential and corrosion current signals to a simulated control room environment. Copyright © 2014 ISA. All rights reserved.

Corrosion of metallic materials by uranium hexafluoride at high temperatures (1963); Corrosion de materiaux metalliques par l'hexafluorure d'uranium a haute temperature (1963)

Energy Technology Data Exchange (ETDEWEB)

Langlois, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The corrosion of the following metals or alloys by UF{sub 6}: nickel, monel, Inconel, gold, platinum, stainless steel, is studied in the temperature range from 300 to 1000 deg. C. The test method, designed to avoid heating the apparatus containing the corrosive fluid to a high temperature, consists in using threadlike samples heated by the Joule effect, the rest of the apparatus being maintained close to room temperature. This technique makes it possible also to determine continuously the penetration of the corrosion by measuring the electrical resistance of the sample with a double Thomson bridge. A series of rapid comparison tests shows that stainless steel, precious metals and Inconel are attacked far too rapidly to be used above 500 deg. C; only monel and especially nickel appear capable of resisting at high temperatures. The detailed examination of the behaviour of nickel shows that the metallic fluoride is volatilized and that this influences the corrosion rate. It shows also the existence of a temperature zone situated between 550 and 700 deg. C in which occurs A strong intergranular corrosion the cause of which appears to be the presence of impurities in the metal. (author) [French] La corrosion par l'UF{sub 6} des metaux ou alliages suivants: lickel, monel, inconel, or, platine, acier inoxydable, est etudiee dans le un domaine de temperature compris entre 300 et 1000 deg. C. La methode d'essai, destinee a eviter le chauffage de l'enceinte contenant le fluide corrosif a temperature elevee, consiste a utiliser des eprouvettes filiformes, echauffees par effet Joule, le reste de l'appareillage etant maintenu a une temperature proche de l'ambiance. Cette technique permet en outre de determiner en continu la penetration de la corrosion, par mesure de la resistance electrique de l'eprouvette, au moyen d'un pont double de Thomson. Une serie d'essais comparatifs, assez sommaires, montre que l'acier inoxydable, les metaux precieux et l'inconel sont attaques beaucoup

The development of an adsorbent for corrosion products in high-temperature water

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Ik; Sung, Ki Woung; Kim, Kwang Rag; Kim, Yu Hwan; Koo, Jae Hyoo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-08-01

In order to use as adsorbent for removal of the soluble corrosion products, mainly Co{sup 60} under PWR reactor coolant conditions (300 deg C, 160 kg/cm{sup 2}), stable ZrO{sub 2} adsorbent was prepared using sol-gel process from zirconyl nitrate, AlO adsorbent was prepared by hydrolysis of aluminum isopropoxide, and titanium tetraisopropoxide, respectively. The prepared adsorbents were calcined at various temperature and analyzed by physical properties and the Co{sup 2+} adsorption capacity. And it was shown that the Co{sup 2+} adsorption capacity of the TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to have larger than that of ZrO{sub 2} and Al{sub 2}O{sub 3} adsorbents in high-temperature water. ZrO{sub 2}, Al{sub 2}O{sub 3} and TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to be suitable high-temperature adsorbents for the removal of dissolved corrosion products, mainly Co in PWR reactor coolant conditions. 15 tabs., 51 figs., 55 refs. (Author).

Optimization of Arc-Sprayed Ni-Cr-Ti Coatings for High Temperature Corrosion Applications

Science.gov (United States)

Matthews, S.; Schweizer, M.

2013-04-01

High Cr content Ni-Cr-Ti arc-spray coatings have proven successful in resisting the high temperature sulfidizing conditions found in black liquor recovery boilers in the pulp and paper industry. The corrosion resistance of the coatings is dependent upon the coating composition, to form chromium sulfides and oxides to seal the coating, and on the coating microstructure. Selection of the arc-spray parameters influences the size, temperature and velocity of the molten droplets generated during spraying, which in turn dictates the coating composition and formation of the critical coating microstructural features—splat size, porosity and oxide content. Hence it is critical to optimize the arc-spray parameters in order to maximize the corrosion resistance of the coating. In this work the effect of key spray parameters (current, voltage, spray distance and gas atomizing pressure) on the coating splat thickness, porosity content, oxide content, microhardness, thickness, and surface profile were investigated using a full factorial design of experiment. Based on these results a set of oxidized, porous and optimized coatings were prepared and characterized in detail for follow-up corrosion testing.

Parameters of straining-induced corrosion cracking in low-alloy steels in high temperature water

International Nuclear Information System (INIS)

Lenz, E.; Liebert, A.; Stellwag, B.; Wieling, N.

Tensile tests with slow deformation speed determine parameters of corrosion cracking at low strain rates of low-alloy steels in high-temperature water. Besides the strain rate the temperature and oxygen content of the water prove to be important for the deformation behaviour of the investigated steels 17MnMoV64, 20 MnMoNi55 and 15NiCuMoNb 5. Temperatures about 240 0 C, increased oxygen contents in the water and low strain rates cause a decrease of the material ductility as against the behaviour in air. Tests on the number of stress cycles until incipient cracking show that the parameters important for corrosion cracking at low strain velocities apply also to low-frequency cyclic loads with high strain amplitude. In knowledge of these influencing parameters the strain-induced corrosion cracking is counteracted by concerted measures taken in design, construction and operation of nuclear power stations. Essential aims in this matter are to avoid as far as possible inelastic strains and to fix and control suitable media conditions. (orig.) [de

Development of Very High Temperature Reactor Technology

International Nuclear Information System (INIS)

Lee, Won Jae; Noh, J. M.; Kim, Y. H.

2009-04-01

For an efficient production of nuclear hydrogen, the VHTR (Very High Temperature Gas-cooled Reactor) of 950 .deg. C outlet temperature and the interfacing system for the hydrogen production are required. We have developed various evaluation technologies for the performance and safety of VHTR through the accomplishment of this project. First, to evaluate the performance of VHTR, a series of analyses has been performed such as core characteristics at 950 .deg. C, applicability of cooled-vessel, intermediate loop system and high temperature structural integrity. Through the analyses of major accidents such as HPCC and LPCC and the analysis of the risk/performance-informed method, VHTR safety evaluation has been also performed. In addition, various design analysis codes have been developed for a nuclear design, system loop design, system performance analysis, air-ingress accident analysis, fission product/tritium transport analysis, graphite structure seismic analysis and hydrogen explosion analysis, and they are being verified and validated through a lot of international collaborations

The corrosion resistance of Zr-Nb and Zr-Nb-Sn alloys in high-temperature water and steam

International Nuclear Information System (INIS)

Dalgaard, S.B.

1960-03-01

An alloy of reactor-grade sponge zirconium-2.5 wt. % niobium was exposed to water and steam at high temperature. The corrosion was twice that of Zircaloy-2 while hydrogen pickup was found to be equal to that of Zircaloy-2. Ternary additions of tin to this alloy in the range 0.5-1.5 had no effect on the corrosion resistance in water at 315 o C up to 100 days. At higher temperatures, tin increased the corrosion, the effect varying with temperature. Heat treatment of the alloys was shown to affect corrosion resistance. (author)

The corrosion resistance of Zr-Nb and Zr-Nb-Sn alloys in high-temperature water and steam

Energy Technology Data Exchange (ETDEWEB)

Dalgaard, S B

1960-03-15

An alloy of reactor-grade sponge zirconium-2.5 wt. % niobium was exposed to water and steam at high temperature. The corrosion was twice that of Zircaloy-2 while hydrogen pickup was found to be equal to that of Zircaloy-2. Ternary additions of tin to this alloy in the range 0.5-1.5 had no effect on the corrosion resistance in water at 315{sup o}C up to 100 days. At higher temperatures, tin increased the corrosion, the effect varying with temperature. Heat treatment of the alloys was shown to affect corrosion resistance. (author)

Tensile and stress corrosion cracking properties of type 304 stainless steel irradiated to a very high dose

International Nuclear Information System (INIS)

Chung, H.M.; Strain, R.V.; Shack, W.J.

2001-01-01

Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20-100 displacement per atom or dpa) by the end of life. Our databases and mechanistic understanding of the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high doses, i.e. is it purely mechanical failure or is it stress-corrosion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-II reactor after irradiation to ∼50 dpa at ∼370 deg. C. Slow-strain-rate tensile tests were conducted at 289 degree sign C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microscopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at a low ECP, and this susceptibility led to a poor work-hardening capability and low ductility

Lateral Temperature-Gradient Method for High-Throughput Characterization of Material Processing by Millisecond Laser Annealing.

Science.gov (United States)

Bell, Robert T; Jacobs, Alan G; Sorg, Victoria C; Jung, Byungki; Hill, Megan O; Treml, Benjamin E; Thompson, Michael O

2016-09-12

A high-throughput method for characterizing the temperature dependence of material properties following microsecond to millisecond thermal annealing, exploiting the temperature gradients created by a lateral gradient laser spike anneal (lgLSA), is presented. Laser scans generate spatial thermal gradients of up to 5 °C/μm with peak temperatures ranging from ambient to in excess of 1400 °C, limited only by laser power and materials thermal limits. Discrete spatial property measurements across the temperature gradient are then equivalent to independent measurements after varying temperature anneals. Accurate temperature calibrations, essential to quantitative analysis, are critical and methods for both peak temperature and spatial/temporal temperature profile characterization are presented. These include absolute temperature calibrations based on melting and thermal decomposition, and time-resolved profiles measured using platinum thermistors. A variety of spatially resolved measurement probes, ranging from point-like continuous profiling to large area sampling, are discussed. Examples from annealing of III-V semiconductors, CdSe quantum dots, low-κ dielectrics, and block copolymers are included to demonstrate the flexibility, high throughput, and precision of this technique.

High temperature cyclic oxidation and hot corrosion behaviours of ...

Indian Academy of Sciences (India)

Administrator

eutectic reaction below 600°C. When the temperature ... blades, consequently corrosion rate rapidly increases due ... the corrosion run. ... Figure 1. Surface macrographs of superalloys subjected to hot corrosion and oxidation .... show the oxide scales of three different chemical compo- .... Li J and Wahi R P 1995 Acta Metall.

Evaluation of the IGSCC(Intergranular Stress Corrosion Cracking) resistance of inconel alloys by static potential method in high temperature and high pressure environment

International Nuclear Information System (INIS)

Maeng, Wan Young; Nam, Tae Woon

1997-01-01

Inconel alloys which have good high temperature mechanical properties and corrosion resistance have been used extensively as steam generator tube of nuclear power plants. There have been some reports on the intergranular stress corrosion cracking (IGSCC) failure problems in steam generator tubes of nuclear reactors. In order to evaluate the effects of heat treatment and composition on the IGSCC behavior of inconel alloys in simulated nuclear reactor environment, four different specimens (inconel 600 MA, 600 TT, 690 MA and 690 TT) were prepared and tested by eletrochemical method. Static potential tests for stressed C-ring type inconel specimens were carried out in 10% NaOH solution at 300 deg C (75 atm). It was found that IGSCC was initiated in inconel 600 MA specimen, but the other three specimens were not cracked. Based on the gradients of corrosion current density of the four specimens as a function of test time, thermally treated alloys show better IGSCC resistance than mull-annealed alloys, and inconel 690 TT has better passivation characteristic than inconel 600 MA. Inconel 690 TT shows clear periodic passivation that indicates good SCC resistance. The good IGSCC resistance of inconel 690 TT is due to periodic passivation characteristics of surface layer. (author)

High temperature corrosion of nickel-base alloys in environments containing alkali sulphate

Energy Technology Data Exchange (ETDEWEB)

Pettersson, Rachel; Flyg, Jesper; Caddeo, Sophie [Corrosion and Metals Research Institute, KIMAB, Stockholm (Sweden); Karlsson, Fredrik [Siemens Industrial Turbomachinery, Finspong (Sweden)

2007-02-15

This work is directed towards producing data to assist in lifetime assessment of components in gas turbines run in severely polluted industrial environments where the main corrosive species is SO{sub 2}, which can condense to form alkali sulphates. Corrosion rates have been measured for the base materials, in order to assess the worst-case scenario, in which cracks or other damage has occurred to the protective coating. The information is expected to be of value to manufacturers, owners and inspectors of gas turbines. Six nickel-base superalloys were subject to thermal cycles of 160 hours duration, and 0.8mg/cm{sup 2} of 20 mol % Na{sub 2}SO{sub 4} + 80mol% K{sub 2}SO{sub 4} was applied before each cycle. The test temperatures were 850 deg C and 900 deg C, with maximum test durations of 24 cycles and 12 cycles respectively. The metal loss was assessed by metallography of cross sections and the sulphidation attack was found to be very uneven. Mass change data indicated that the corrosion process was largely linear in character, and probability plots and estimations of the propagation rate of corrosion based on the linear growth assumption were produced. The performance of the alloys increased with increasing chromium content. The single crystal materials CMSX4 and MD2 showed such high corrosion rates that their use in severely contaminated industrial environments is considered inadvisable. The best performance was shown by Inconel 939 and Inconel 6203, so that even if cracks occur in the protective coating, a reasonable remaining lifetime can be expected for these materials. Sulphide formation occurred at the reaction front in all cases and mixed sulphides such as Ta-Ni or Ti-Nb sulphides were often present. The work has news value since very little long-term data is currently available for materials performance in severely sulphidising environments. The project goals in terms of exposures and metrology have been fully realised. Contributions have been made to the

Corrosion behavior of Al-Fe-sputtering-coated steel, high chromium steels, refractory metals and ceramics in high temperature Pb-Bi

International Nuclear Information System (INIS)

Abu Khalid, Rivai; Minoru, Takahashi

2007-01-01

Corrosion tests of Al-Fe-coated steel, high chromium steels, refractory metals and ceramics were carried out in high temperature Pb-Bi at 700 C degrees. Oxygen concentrations in this experiment were 6.8*10 -7 wt.% for Al-Fe-coated steels and 5*10 -6 wt.% for high chromium steels, refractory metals and ceramics. All specimens were immersed in molten Pb-Bi in a corrosion test pot for 1.000 hours. Coating was done with using the unbalanced magnetron sputtering (UBMS) technique to protect the steel from corrosion. Sputtering targets were Al and SUS-304. Al-Fe alloy was coated on STBA26 samples. The Al-Fe alloy-coated layer could be a good protection layer on the surface of steel. The whole of the Al-Fe-coated layer still remained on the base surface of specimen. No penetration of Pb-Bi into this layer and the matrix of the specimen. For high chromium steels i.e. SUS430 and Recloy10, the oxide layer formed in the early time could not prevent the penetration of Pb-Bi into the base of the steels. Refractory metals of tungsten (W) and molybdenum (Mo) had high corrosion resistance with no penetration of Pb-Bi into their matrix. Penetration of Pb-Bi into the matrix of niobium (Nb) was observed. Ceramic materials were SiC and Ti 3 SiC 2 . The ceramic materials of SiC and Ti 3 SiC 2 had high corrosion resistance with no penetration of Pb-Bi into their matrix. (authors)

Topographical, microstructural and chemical effects of simulated high heat flux on the corrosion of Type 316 stainless steel in flowing sodium

International Nuclear Information System (INIS)

Bagnall, C.; Shiels, S.A.; Orbon, S.J.

1976-01-01

Earlier work, performed in sodium test facilities around the world, have produced corrosion data for Type 316 SS which has been used to estimate metal loss rates from the core of a liquid metal fast breeder reactor. Practical difficulties precluded evaluation of the influence on corrosion of irradiation, a high heat flux and the high axial temperature gradient the latter produces. Downstream effects in isothermal regions were, however, documented in some tests. This paper presents recent results of corrosion experiments conducted in a test facility designed to produce a temperature rise in the fluid equivalent to a heat flux in the primary heater of about 0.5 x10 6 Btu/(h-ft 2 ). The axial temperature gradient was such that the sodium temperature was increased over a distance of three feet from 820F at the inlet, to 1360F at the outlet. The secondary ion mass spectrometer, the electron probe microanalyzer, the scanning electron microscope, and the optical microscope were used individually to characterize the various compositional, topographical and structural changes that occurred in the stainless steel as a result of the sodium exposure. Several important effects attributable to the high axial temperature gradient were noted. The collective results presented provide a clarified picture of material reaction to this environment and permit a more meaningful prediction of the behavior of critical components within the core of a liquid metal fast breeder reactor. (Auth.)

Silicon coating treatment to improve high temperature corrosion resistance of 9%Cr steels

International Nuclear Information System (INIS)

Hill, M.P.

1989-01-01

A silicon coating process is described which confers good protection on 9%Cr steels and alloys in CO 2 based atmospheres at high temperatures and pressures. The coatings are formed by decomposition of silane at temperatures above 720 K. Protective layers are typically up to 1 μm thick. The optimum coating conditions are discussed. The chemical state of the coatings has been investigated by X-ray photoelectron spectroscopy and has demonstrated the importance of avoiding silicon oxide formation during processing. Corrosion testing has been carried out for extended periods, up to 20 000 h, at temperatures between 753 and 853 K, in a simulated advanced gas cooled reactor gas at 4 MPa pressure. Benefit factors of up to 60 times have been measured for 9%Cr steels. Even higher values have been measured for 9Cr-Fe binary alloy on which a 1 μm coating was sufficient to eliminate significant oxidation over 19 000 h except at the specimen edges. The mechanism of protection is discussed. It is suggested that a silicon surface coating for protecting steels from high temperature corrosion has some advantages over adding silicon to the bulk metal. (author)

Corrosion of metallic materials by uranium hexafluoride at high temperatures (1963); Corrosion de materiaux metalliques par l'hexafluorure d'uranium a haute temperature (1963)

Energy Technology Data Exchange (ETDEWEB)

Langlois, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The corrosion of the following metals or alloys by UF{sub 6}: nickel, monel, Inconel, gold, platinum, stainless steel, is studied in the temperature range from 300 to 1000 deg. C. The test method, designed to avoid heating the apparatus containing the corrosive fluid to a high temperature, consists in using threadlike samples heated by the Joule effect, the rest of the apparatus being maintained close to room temperature. This technique makes it possible also to determine continuously the penetration of the corrosion by measuring the electrical resistance of the sample with a double Thomson bridge. A series of rapid comparison tests shows that stainless steel, precious metals and Inconel are attacked far too rapidly to be used above 500 deg. C; only monel and especially nickel appear capable of resisting at high temperatures. The detailed examination of the behaviour of nickel shows that the metallic fluoride is volatilized and that this influences the corrosion rate. It shows also the existence of a temperature zone situated between 550 and 700 deg. C in which occurs A strong intergranular corrosion the cause of which appears to be the presence of impurities in the metal. (author) [French] La corrosion par l'UF{sub 6} des metaux ou alliages suivants: lickel, monel, inconel, or, platine, acier inoxydable, est etudiee dans le un domaine de temperature compris entre 300 et 1000 deg. C. La methode d'essai, destinee a eviter le chauffage de l'enceinte contenant le fluide corrosif a temperature elevee, consiste a utiliser des eprouvettes filiformes, echauffees par effet Joule, le reste de l'appareillage etant maintenu a une temperature proche de l'ambiance. Cette technique permet en outre de determiner en continu la penetration de la corrosion, par mesure de la resistance electrique de l'eprouvette, au moyen d'un pont double de Thomson. Une serie d'essais comparatifs, assez sommaires, montre que l'acier inoxydable, les metaux

High temperature (salt melt) corrosion tests with ceramic-coated steel

Energy Technology Data Exchange (ETDEWEB)

Schütz, Adelheid [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Günthner, Martin; Motz, Günter [University Bayreuth, Ceramic Materials Engineering, L.-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Greißl, Oliver [EnBW Kraftwerke AG, Schelmenwasenstraße 13-15, D-70567 Stuttgart (Germany); Glatzel, Uwe, E-mail: uwe.glatzel@uni-bayreuth.de [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany)

2015-06-01

Thermal recycling of refuse in waste-to-energy plants reduces the problems connected to waste disposal, and is an alternative source of electric energy. However, the combustion process in waste incinerators results in a fast degradation of the steam-carrying superheater steel tubes by corrosive attack and abrasive wear. Higher firing temperatures are used to increase their efficiency but lead to higher corrosion rates. It is more economical to apply protective coatings on the superheater steel tubes than to replace the base material. In-situ tests were conducted in a waste-to-energy plant first in order to identify and quantify all involved corrosive elements. Laboratory scale experiments with salt melts were developed accordingly. The unprotected low-alloyed steel displayed substantial local corrosion. Corrosion was predominant along the grain boundaries of α-ferrite. The corrosion rate was further increased by FeCl{sub 3} and a mixture of HCL and FeCl{sub 3}. Coatings based on pre-ceramic polymers with specific filler particles were engineered to protect superheater tubes. Tests proved their suitability to protect low-alloYed steel tubes from corrosive attack under conditions typical for superheaterS in waste incinerators, rendering higher firing temperatures in waste-to-energy plants possible. - Highlights: • Corrosion wall thickness losses of 400 μm/2 weeks occurred in a waste incinerator. • Abrasion is a major problem on superheater tubes in waste incinerators. • Laboratory salt melt tests can simulate metal corrosion in waste incinerators. • Corrosion protection coatings for steel (temperature: max. 530 °C) were developed. • Higher steam temperatures are possible in WIs with the developed coatings.

The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks

International Nuclear Information System (INIS)

Kleva, Robert G.; Guzdar, Parvez N.

2009-01-01

Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.

The Corrosion Rate Measurement of Inconel 690 on High Temperature andPressure by Using CMS100

International Nuclear Information System (INIS)

Sriyono; Febrianto

2000-01-01

The corrosion rate measurement of Inconel 690 on high temperature andpressure had been done. By using an Autoclave, pressure and temperature canbe simulated. The environment of this experiment is 0.1 ppm of chloridesolution, which permit to dissolved in secondary cooling of steam generator.The corrosion rate measurement was done on temperature between 150 o C and230 o C with step 10 o C. Pressure experiment is the pressure, which occurredin Autoclave. Corrosion rate is measured by CMS100. From the Tafel analysis,corrosion rate of Inconel 690 linearity increased from 6.548 x 10 -5 mpy to4.331 x 10 -4 mpy. It concludes that Inconel 690 is resist on corrosionenvironment, so it's most using on the fabrication of steam generator tubeson the advanced power plant. (author)

The probability distribution of intergranular stress corrosion cracking life for sensitized 304 stainless steels in high temperature, high purity water

International Nuclear Information System (INIS)

Akashi, Masatsune; Kenjyo, Takao; Matsukura, Shinji; Kawamoto, Teruaki

1984-01-01

In order to discuss the probability distribution of intergranular stress corrsion carcking life for sensitized 304 stainless steels, a series of the creviced bent beem (CBB) and the uni-axial constant load tests were carried out in oxygenated high temperature, high purity water. The following concludions were resulted; (1) The initiation process of intergranular stress corrosion cracking has been assumed to be approximated by the Poisson stochastic process, based on the CBB test results. (2) The probability distribution of intergranular stress corrosion cracking life may consequently be approximated by the exponential probability distribution. (3) The experimental data could be fitted to the exponential probability distribution. (author)

Manufacture and evaluation of integrated metal-oxide electrode prototype for corrosion monitoring in high temperature water

International Nuclear Information System (INIS)

Hashimoto, Yoshinori; Tani, Jun-ichi

2014-01-01

We have developed an integrated metal-oxide (M/O) electrode based on an yttria-stabilized-zirconia-(YSZ)-membrane M/O electrode, which was used as a reference electrode for corrosion monitoring in high temperature water. The YSZ-membrane M/O electrode can operate at high temperatures because of the conductivity of YSZ membrane tube. We cannot utilize it for long term monitoring at a wide range of temperatures. It also has a braze juncture between the YSZ membrane and metal tubes, which may corrode in high-temperature water. This corrosion should be prevented to improve the performance of the M/O electrode. An integrated M/O electrode was developed (i.e., integrated metal-oxide electrode, IMOE) to eliminate the braze juncture and increase the conductivity of YSZ. These issues should be overcome to improve the performance of M/O electrode. So we have developed two type of IMOE prototype with sputter - deposition or thermal oxidation. In this paper we will present and discuss the performance of our IMOEs in buffer solution at room temperature. (author)

High temperature corrosion in the service environments of a nuclear process heat plant

International Nuclear Information System (INIS)

Quadakkers, W.J.

1987-01-01

In a nuclear process heat plant the heat-exchanging components fabricated from nickel- and Fe-Ni-based alloys are subjected to corrosive service environments at temperatures up to 950 0 C for service lives of up to 140 000 h. In this paper the corrosion behaviour of the high temperature alloys in the different service environments will be described. It is shown that the degree of protection provided by Cr 2 O 3 -based surface oxide scales against carburization and decarburization of the alloys is primarily determined not by the oxidation potential of the atmospheres but by a dynamic process involving, on the one hand, the oxidizing gas species and the metal and, on the other hand, the carbon in the alloy and the oxide scale. (orig.)

Very high temperature measurements: Applications to nuclear reactor safety tests; Mesures des tres hautes temperatures: Applications a des essais de surete des reacteurs nucleaires

Energy Technology Data Exchange (ETDEWEB)

Parga, Clemente-Jose

2013-09-27

This PhD dissertation focuses on the improvement of very high temperature thermometry (1100 deg. C to 2480 deg. C), with special emphasis on the application to the field of nuclear reactor safety and severe accident research. Two main projects were undertaken to achieve this objective: - The development, testing and transposition of high-temperature fixed point (HTFP) metal-carbon eutectic cells, from metrology laboratory precision (±0.001 deg. C) to applied research with a reasonable degradation of uncertainties (±3-5 deg. C). - The corrosion study and metallurgical characterization of Type-C thermocouple (service temp. 2300 deg. C) prospective sheath material was undertaken to extend the survivability of TCs used for molten metallic/oxide corium thermometry (below 2000 deg. C)

Application of aluminum diffusion coatings to mitigate the KCl-induced high-temperature corrosion

DEFF Research Database (Denmark)

Kiamehr, Saeed; Lomholt, T. N.; Dahl, Kristian Vinter

2017-01-01

Pack cementation was used to produce Fe1−xAl and Fe2Al5 diffusion coatings on ferritic-martensitic steel P91 and a Ni2Al3 diffusion coating on pure nickel. The performance of diffusion coatings against high-temperature corrosion induced by potassium chloride (KCl) was evaluated by exposing...

Development of very high temperature reactor design technology

International Nuclear Information System (INIS)

Lee, Won Jae; Noh, Jan Man

2012-04-01

or an efficient production of nuclear hydrogen, the VHTR (Very High Temperature Gas-cooled Reactor) of 950 .deg. C outlet temperature and the interfacing system for the hydrogen production are required. We have developed various evaluation technologies for the performance and safety of VHTR through the accomplishment of this project. First, to evaluate the performance of VHTR, a series of analyses has been performed such as core characteristics at 950 .deg. C, applicability of cooled-vessel, intermediate loop system and high temperature structural integrity. Through the analyses of major accidents such as HPCC and LPCC and the analysis of the risk/performance-informed method, VHTR safety evaluation has been also performed. In addition, various design analysis codes have been developed for a nuclear design, system loop design, system performance analysis, fission product/tritium transport analysis, core thermo-fluid analysis, system layout analysis, graphite structure seismic analysis and hydrogen exposion analysis, and they are being verified and validated through a lot of international collaborations

Development of Very High Temperature Reactor Design Technology

International Nuclear Information System (INIS)

Lee, Won Jae; Noh, J. M.; Kim, K. S.

2007-05-01

To develop design technologies for the VHTR (Very High Temperature Gas-cooled Reactor) of 950 .deg. C outlet temperature for an efficient hydrogen production, key studies were performed, which include evaluation technology for the performance and safety of VHTR, and development of design and analysis codes. First, to evaluate the performance of VHTR, a series of analyses has been carried out for core characteristics at 950 .deg. C, cooled-vessel adopting internal flow path through the graphite structure, compact heat exchanger with periodic channel configuration, intermediate loop system, risk/performance-informed method, and high temperature structural integrity. Through the analyses of major accidents such as HPCC and LPCC, safety evaluation of both VHTR and RCCS has been also performed. In addition, prototype codes have been developed for a nuclear design, system loop design, system performance analysis, air-ingress accident analysis, fission product/tritium transport analysis, graphite structure seismic analysis and hydrogen explosion analysis, and they are being verified and validated through a lot of international collaborations

High temperature corrosion in biomass- and waste fired boilers. A status report; Kunskapslaeget betraeffande hoegtemperaturkorrosion i aangpannor foer biobraensle och avfall

Energy Technology Data Exchange (ETDEWEB)

Henderson, P; Ifwer, K; Staalenheim, A; Montgomery, M; Hoegberg, J; Hjoernhede, A

2006-12-15

Many biomass- or waste-fired plants have problems with high temperature corrosion on the furnace walls or at the superheaters, especially if the steam temperature is greater than 500 deg C. An increase in the combustion of waste fuels means that an increasing number of boilers have had problems. Therefore, there is great interest from plant owners to reduce the costs associated with high temperature corrosion. At the same time there exists a considerable driving force towards improving the electrical efficiency of a plant by the use of more advanced steam data. The purpose of the work presented here was to answer three main questions: What can be done to reduce high temperature corrosion with current fuel blends and steam temperatures? How can more waste fuels be burnt without an increased risk for corrosion? What needs to be done to reach higher steam temperatures in the future? The level of knowledge of high temperature corrosion in biomass- and waste-fired boilers has been described and summarised. The following measures are recommended to reduce corrosion in existing plant: Make sure that the fuel is well mixed and improve fuel feeding to obtain a more even spread of the fuel over the cross-section of the boiler. Use combustion technology methods to stabilize the oxygen content of the flue gases near the membrane walls and other heat transfer surfaces. Experiment with additives and/or supplementary fuels which contain sulphur in some form, for example peat. Reduce the flue gas temperature at the superheaters. Review soot-blowing procedures or protect heat transfer surfaces from soot blowers. Evaluate coated membrane wall panels in parts of the furnace that experience the worst corrosion. Test more highly alloyed steels suitable for superheaters and when replacing a superheater change to a more highly alloyed steel. For the future, the following should be considered: The role of sulphur needs to be investigated more and other additives should be investigated

Structural instabilities of high temperature alloys and their use in advanced high temperature gas cooled reactors

International Nuclear Information System (INIS)

Schuster, H.; Ennis, P.J.; Nickel, H.; Czyrska-Filemonowicz, A.

1989-01-01

High-temperature, iron-nickel and nickel based alloys are the candidate heat exchanger materials for advanced high temperature gas-cooled reactors supplying process heat for coal gasification, where operation temperatures can reach 850-950 deg. C and service lives of more than 100,000 h are necessary. In the present paper, typical examples of structural changes which occur in two representative alloys (Alloy 800 H, Fe-32Ni-20Cr and Alloy 617, Ni-22Cr-12Co-9Mo-1Al) during high temperature exposure will be given and the effects on the creep rupture properties discussed. At service temperatures, precipitation of carbides occurs which has a significant effect on the creep behaviour, especially in the early stages of creep when the precipitate particles are very fine. During coarsening of the carbides, carbides at grain boundaries restrict grain boundary sliding which retards the development of creep damage. In the service environments, enhanced carbide precipitation may occur due to the ingress of carbon from the environment (carburization). Although the creep rate is not adversely affected, the ductility of the carburized material at low and intermediate temperatures is very low. During simulated service exposures, the formation of surface corrosion scales, the precipitation of carbides and the formation of internal oxides below the surface leads to depletion of the matrix in the alloying elements involved in the corrosion processes. In thin-walled tubes the depletion of Cr due to Cr 2 O 3 formation on the surface can lead to a loss of creep strength. An additional depletion effect resulting from environmental-metal reactions is the loss of carbon (decarburization) which may occur in specific environments. The compositions of the cooling gases which decarburize the material have been determined; they are to be avoided during reactor operation

A fundamental study on stress corrosion cracking of SUS 304 steel in high temperature water

International Nuclear Information System (INIS)

Mukai, Yoshihiko; Murata, Masato

1985-01-01

SCC susceptibility of sensitized SUS 304 stainless steel in high temperature water was studied. The results obtained are as follows. SCC susceptibility was increased by adding crevices to the tensile specimen surface, for the corrodent became acidified by hydrolysis in crevices. SCC susceptibility was best fit to TTS curve obtained by EPR test, not by other corrosion tests such as Strauss test or the grain boundary corrosion test in high temperature water. In addition, by giving a simulated weld thermal cycle before the sensitizing heat treatment, the sensitization was clearly promoted. This seemed to be caused by the reason that nucleation of carbide occured in the simulated weld thermal cycle process and it promoted the carbide growth and the formation of Cr poor layer around carbide in the subsequent sensitization process. (author)

1982 Annual status report: high-temperature materials

International Nuclear Information System (INIS)

Van de Voorde, M.

1983-01-01

The High Temperature Materials Programme is executed at the JRC, Petten Establishment and has for the 1980/83 programme period the objective to promote within the European Community the development of high temperature materials required for future energy technologies. Materials and engineering studies include: corrosion with or without load, mechanical properties under static or dynamic loads, surface protection creep of tubular components in corrosive environments and high temperature materials data bank

High temperature corrosion of metallic interconnects in solid oxide fuel cells

International Nuclear Information System (INIS)

Bastidas, D. M.

2006-01-01

Research and development has made it possible to use metallic interconnects in solid oxide fuel cells (SOFC) instead of ceramic materials. The use of metallic interconnects was formerly hindered by the high operating temperature, which made the interconnect degrade too much and too fast to be an efficient alternative. When the operating temperature was lowered, the use of metallic interconnects proved to be favourable since they are easier and cheaper to produce than ceramic interconnects. However, metallic interconnects continue to be degraded despite the lowered temperature, and their corrosion products contribute to electrical degradation in the fuel cell. coatings of nickel, chromium, aluminium, zinc, manganese, yttrium or lanthanum between the interconnect and the electrodes reduce this degradation during operation. (Author) 66 refs

Recent improvements in the filtration of corrosion products in high temperature water and application to reactor circuits

International Nuclear Information System (INIS)

Darras, R.; Dolle, L.; Chenouard, J.; Laylavoix, F.

1977-01-01

The nature and physico-chemical behavior of corrosion products released by structural materials into high temperature water flowing in power reactor circuits have been investigated in test loops and different power plants. The results improve more particularly the knowledge of probable rate constants governing their disappearance through deposition of crud on the fuel cladding. It appears that a considerable limitation of radioactivity transportation in the primary circuit components of pressurized water reactors is in a general way only possible through extraction of the corrosion products by filtration at a rate adequate to minimize the amount of crud deposited in the core. This extraction rate has been estimated; its magnitude implicates a filtration operating on the high temperature water in the primary circuit which allows the necessary high flows. The application of magnetic and electromagnetic so as deep granular graphite bed filters has been studied. The results concerning efficiencies and limiting yields at high temperatures are given. Estimates concerning technological feasibility and corresponding investments are discussed

Yield strength of molybdenum, tantalum and tungsten at high strain rates and very high temperatures

International Nuclear Information System (INIS)

Škoro, G.P.; Bennett, J.R.J.; Edgecock, T.R.; Booth, C.N.

2012-01-01

Highlights: ► New experimental data on the yield strength of molybdenum, tantalum and tungsten. ► High strain rate effects at record high temperatures (up to 2700 K). ► Test of the consistency of the Zerilli–Armstrong model at very high temperatures. - Abstract: Recently reported results of the high strain rate, high temperature measurements of the yield strength of tantalum and tungsten have been analyzed along with new experimental results on the yield strength of molybdenum. Thin wires are subjected to high stress by passing a short, fast, high current pulse through a thin wire; the amplitude of the current governs the stress and the repetition rate of the pulses determines the temperature of the wire. The highest temperatures reached in the experiments were 2100 °C (for molybdenum), 2250 °C (for tantalum) and 2450 °C (for tungsten). The strain-rates in the tests were in the range from 500 to 1500 s −1 . The parameters for the constitutive equation developed by Zerilli and Armstrong have been determined from the experimental data and the results have been compared with the data obtained at lower temperatures. An exceptionally good fit is obtained for the deformation of tungsten.

9% Cr steel high temperature oxidation. Solutions investigated for improving corrosion resistance of the steel

Energy Technology Data Exchange (ETDEWEB)

Evin, Harold Nicolas; Heintz, Olivier; Chevalier, Sebastien [UMR 5209 CNRS-Bourgogne Univ. (France). Lab. Interdisciplinaire Carnot de Bourgogne; Foejer, Cecilia; Jakani, Saad; Dhont, Annick; Claessens, Serge [OCAS N.V. ArcelorMittal Global R and D, Gent (Belgium)

2010-07-01

The improvement of high temperature oxidation resistance of low chromium content steels, such as T/P91, is of great interest in regards with their application in thermal power generating plants. Indeed, they possess good creep properties, but are facing their limits of use at temperature higher than 600 C, due to accelerated corrosion phenomena. Good knowledge of the mechanisms involved during their oxidation process is needed to prevent the degradation of the materials and to extend life time of the power plants components. Oxide layers thermally grown, on 9% Cr steels (provided by OCAS N.V), during isothermal tests between 600 C and 750 C in laboratory air under atmospheric pressure were investigated, by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The oxidation behaviour appeared very limited at 750 C, due to the presence of a breakaway, which can be linked to iron porous oxide grown over the surface of the samples. ''In situ'' X-ray Photoelectron spectroscopy (XPS) analyses were performed in air at 600 C after short exposures (between 5 min and 25 h). A complex mixture of iron oxide, Cr{sub 2}O{sub 3} and Cr (VI) species were characterized in the scales. The in-situ analyses were compared and related to XPS analyses performed on thick oxide scales formed on samples oxidized in air at 600 C for 100h. An oxidation mechanism is then proposed to understand the oxide scale growth in the temperature range 600 - 750 C. The second step of this study consists in improving the high temperature corrosion resistance of these steels without modifying their mechanical properties. Thus several solutions were investigated such as MOCVD coatings, pack cementation coatings, and tested in cycle conditions prior. (orig.)

Assessment of very high-temperature reactors in process applications

International Nuclear Information System (INIS)

Spiewak, I.; Jones, J.E. Jr.; Gambill, W.R.; Fox, E.C.

1976-11-01

An overview is presented of the technical and economic feasibility for the development of a very high-temperature reactor (VHTR) and associated processes. A critical evaluation of VHTR technology for process temperatures of 1400 and 2000 0 F is made. Additionally, an assessment of potential market impact is made to determine the commercial viability of the reactor system. It is concluded that VHTR process heat in the range of 1400 to 1500 0 F is attainable with near-term technology. However, process heat in excess of 1600 0 F would require considerably more materials development. The potential for the VHTR could include a major contribution to synthetic fuel, hydrogen, steel, and fertilizer production and to systems for transport and storage of high-temperature heat. A recommended development program including projected costs is presented

Galvanic corrosion evaluation of high activity nuclear waste container metals components

International Nuclear Information System (INIS)

Semino, C.J.

1990-04-01

The final disposal container for vitrified high-level waste is assumed to have three metallic layers: a stainless steel inner layer, and external one of a metal to be selected and a thick lead layer (10 cm) in the middle. As design limit, the container shall act as an engineering barrier, granting the isolation of the radionuclides for approximately 1000 years. Preliminary titanium-lead galvanic couple tests showed that titanium behaved always as a cathode in the galvanic couple, promoting the galvanic corrosion of lead. This corrosion study focused on the behaviour of lead-AISI 304 stainless steel and lead-carbon steel (SAE 1010 and 1020) galvanic couples with different area relationships, temperature and media composition. High purity lead (99,999%) and commercial lead (99,9%) were used for galvanic couples tests. Tests were performed at 75, 50, 45 and 40 deg. C. Test solution was either synthetic groundwater, a suspension of 10% bentonite in groundwater, or synthetic sea water. The synthetic sea water was used at 100, 50 and 25% concentration by dilution with distilled water. Tests with lead-304 stainless steel galvanic couples showed that lead always behaves as an anode, corroding preferentially. Very low lead corrosion rates were found in lead-carbon steel galvanic couple in 10% bentonite suspension in synthetic groundwater test at 75 deg. C. An increase of carbon content in steel has very little influence on steel corrosion rate. Commercial lead has a higher corrosion rate and presented a more pronounced attack than high purity lead. Its corrosion rate is at least twice when lead-carbon steel area relationship increases from 1:10 to 1:40. There are higher steel corrosion rates in sea water than in groundwater. Lead behaves as a cathode to the end of the test. 8 refs, 85 figs, 10 tabs

Corrosion considerations of high-nickel alloys and titanium alloys for high-level radioactive waste disposal containers

International Nuclear Information System (INIS)

Gdowski, G.E.; McCright, R.D.

1991-07-01

Corrosion resistant materials are being considered for the metallic barrier of the Yucca Mountain Project's high-level radioactive waste disposal containers. High nickel alloys and titanium alloys have good corrosion resistance properties and are considered good candidates for the metallic barrier. The localized corrosion phenomena, pitting and crevice corrosion, are considered as potentially limiting for the barrier lifetime. An understanding of the mechanisms of localized corrosion of how various parameters affect it will be necessary for adequate performance assessments of candidate container materials. Examples of some of the concerns involving candidate container materials. Examples of some of the concerns of involving localized corrosion are discussed. The effects of various parameters, such as temperature and concentration of halide species, on localized corrosion are given. In addition concerns about aging of the protective oxide layer in the expected service temperature range (50 to 250 degrees C) are presented. Also some mechanistic considerations of localized corrosion are given. 31 refs., 1 tab

KCl-induced high temperature corrosion of selected commercial alloys. Part I: chromia-formers

DEFF Research Database (Denmark)

Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie

2015-01-01

-grained), Sanicro 28 and the nickel-based alloys 625, 263 and C276. Exposure was performed at 600 °C for 168 h in flowing N2(g)+5%O2(g)+15% H2O(g) (vol.%). Samples were covered with KCl powder prior to exposure. A salt-free exposure was also performed for comparison. Corrosion morphology and products were studied......Laboratory testing of selected chromia-forming alloys was performed to rank the materials and gain further knowledge on the mechanism of KCl-induced high temperature corrosion. The investigated alloys were stainless steels EN1.4021, EN1.4057, EN1.4521, TP347H (coarse-grained), TP347HFG (fine....... In the presence of solid KCl, all the alloys showed significant corrosion. Measurement of corrosion extent indicated that alloys EN1.4057, Sanicro 28 and 625 show a better performance compared to the industrial state of the art material TP347HFG under laboratory conditions. An additional test was performed...

Evaluation of High Temperature Corrosion Resistance of Finned Tubes Made of Austenitic Steel And Nickel Alloys

Directory of Open Access Journals (Sweden)

Turowska A.

2016-06-01

Full Text Available The purpose of the paper was to evaluate the resistance to high temperature corrosion of laser welded joints of finned tubes made of austenitic steel (304,304H and nickel alloys (Inconel 600, Inconel 625. The scope of the paper covered the performance of corrosion resistance tests in the atmosphere of simulated exhaust gases of the following chemical composition: 0.2% HCl, 0.08% SO2, 9.0% O2 and N2 in the temperature of 800°C for 1000 hours. One found out that both tubes made of austenitic steel and those made of nickel alloy displayed good resistance to corrosion and could be applied in the energy industry.

Stress corrosion of very high purity stainless steels in alkaline media

International Nuclear Information System (INIS)

Hechmat-Dehcordi, Ebrahim

1981-01-01

This research thesis reports the study of stress corrosion resistance of stainless steels in caustic environments. It notably concerns the electronuclear industrial sector, the production of soda by electrolysis, and the preparation of hydrogen as energy vector. After a presentation of the experimental conditions, the author highlights the influence of purity on stress corrosion cracking of 20Cr-25Ni-type austenitic alloys. The specific action of a high number of addition metallic and non-metallic elements has been studied. Stress corrosion tests have been also performed in autoclave on austeno-ferritic (21 to 25 pc Cr - 6 to 10 pc Ni) as well as ferritic (26 pc Cr) grades. The author reports the study of electrochemical properties of stainless steel in soda by means of potentiostatic techniques with an application of Pourbaix thermodynamic equilibrium diagrams, and the study of the chemical composition of passivation thin layers by Auger spectroscopy. He more particularly studies the influence of electrode potential and of some addition elements on the chemical characteristics of oxides developed at the surface of austenite. Then, the author tries to establish correlations between strain hardening microstructure of the various steels and their sensitivity to stress corrosion [fr

A concept of wireless and passive very-high temperature sensor

Science.gov (United States)

Nicolay, P.; Matloub, R.; Bardong, J.; Mazzalai, A.; Muralt, P.

2017-05-01

There is a need for sensors capable operating at temperatures above 1000 °C. We describe an innovative sensor that might achieve this goal. The sensor comprises two main elements: a thermocouple and a surface acoustic wave (SAW) strain sensor. The cold junction of the thermocouple is electrically connected to a highly piezoelectric thin layer, deposited on top of a SAW substrate. In operation, the voltage generated by the temperature gradient between the hot (>1000 °C) and cold junction (PZT), which could increase the sensitivity by factors of 3 and 20, as estimated from their transverse piezoelectric coefficients. As a first step in this direction, thin PZT layers have been deposited on Y-Z LN.

High resolution temperature mapping of gas turbine combustor simulator exhaust with femtosecond laser induced fiber Bragg gratings

Science.gov (United States)

Walker, Robert B.; Yun, Sangsig; Ding, Huimin; Charbonneau, Michel; Coulas, David; Lu, Ping; Mihailov, Stephen J.; Ramachandran, Nanthan

2017-04-01

Femtosecond infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent in advanced gas turbine engines under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring exhaust temperature gradients of a gas turbine combustor simulator. Results include: contour plots of measured temperature gradients, contrast with thermocouple data.

Experience with conventional inelastic analysis procedures in very high temperature applications

International Nuclear Information System (INIS)

Mallett, R.H.; Thompson, J.M.; Swindeman, R.W.

1991-01-01

Conventional incremental plasticity and creep analysis procedures for inelastic analysis are applied to hot flue gas cleanup system components. These flue gas systems operate at temperatures where plasticity and creep are very much intertwined while the two phenomena are treated separately in the conventional inelastic analysis procedure. Data for RA333 material are represented in forms appropriate for the conventional inelastic analysis procedures. Behavior is predicted for typical operating cycles. Creep-fatigue damage is estimated based upon usage fractions. Excessive creep damage is predicted; the major contributions occur during high stress short term intervals caused by rapid temperature changes. In this paper these results are presented for discussion of the results and their interpretation in terms of creep-fatigue damage for very high temperature applications

A general strategy for performing temperature-programming in high performance liquid chromatography--prediction of segmented temperature gradients.

Science.gov (United States)

Wiese, Steffen; Teutenberg, Thorsten; Schmidt, Torsten C

2011-09-28

In the present work it is shown that the linear elution strength (LES) model which was adapted from temperature-programming gas chromatography (GC) can also be employed to predict retention times for segmented-temperature gradients based on temperature-gradient input data in liquid chromatography (LC) with high accuracy. The LES model assumes that retention times for isothermal separations can be predicted based on two temperature gradients and is employed to calculate the retention factor of an analyte when changing the start temperature of the temperature gradient. In this study it was investigated whether this approach can also be employed in LC. It was shown that this approximation cannot be transferred to temperature-programmed LC where a temperature range from 60°C up to 180°C is investigated. Major relative errors up to 169.6% were observed for isothermal retention factor predictions. In order to predict retention times for temperature gradients with different start temperatures in LC, another relationship is required to describe the influence of temperature on retention. Therefore, retention times for isothermal separations based on isothermal input runs were predicted using a plot of the natural logarithm of the retention factor vs. the inverse temperature and a plot of the natural logarithm of the retention factor vs. temperature. It could be shown that a plot of lnk vs. T yields more reliable isothermal/isocratic retention time predictions than a plot of lnk vs. 1/T which is usually employed. Hence, in order to predict retention times for temperature-gradients with different start temperatures in LC, two temperature gradient and two isothermal measurements have been employed. In this case, retention times can be predicted with a maximal relative error of 5.5% (average relative error: 2.9%). In comparison, if the start temperature of the simulated temperature gradient is equal to the start temperature of the input data, only two temperature-gradient

Corrosion Performance of Inconel 625 in High Sulphate Content

Science.gov (United States)

Ismail, Azzura

2016-05-01

Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

Hot-wall corrosion testing of simulated high level nuclear waste

International Nuclear Information System (INIS)

Chandler, G.T.; Zapp, P.E.; Mickalonis, J.I.

1995-01-01

Three materials of construction for steam tubes used in the evaporation of high level radioactive waste were tested under heat flux conditions, referred to as hot-wall tests. The materials were type 304L stainless steel alloy C276, and alloy G3. Non-radioactive acidic and alkaline salt solutions containing halides and mercury simulated different high level waste solutions stored or processed at the United States Department of Energy's Savannah River Site. Alloy C276 was also tested for corrosion susceptibility under steady-state conditions. The nickel-based alloys C276 and G3 exhibited excellent corrosion resistance under the conditions studied. Alloy C276 was not susceptible to localized corrosion and had a corrosion rate of 0.01 mpy (0.25 μm/y) when exposed to acidic waste sludge and precipitate slurry at a hot-wall temperature of 150 degrees C. Type 304L was susceptible to localized corrosion under the same conditions. Alloy G3 had a corrosion rate of 0.1 mpy (2.5 μm/y) when exposed to caustic high level waste evaporator solution at a hot-wall temperature of 220 degrees C compared to 1.1 mpy (28.0 μ/y) for type 304L. Under extreme caustic conditions (45 weight percent sodium hydroxide) G3 had a corrosion rate of 0.1 mpy (2.5 μm/y) at a hot-wall temperature of 180 degrees C while type 304L had a high corrosion rate of 69.4 mpy (1.8 mm/y)

Very heavily electron-doped CrSi2 as a high-performance high-temperature thermoelectric material

International Nuclear Information System (INIS)

Parker, David; Singh, David J

2012-01-01

We analyze the thermoelectric behavior, using first principles and Boltzmann transport calculations, of very heavily electron-doped CrSi 2 and find that at temperatures of 900-1250 K and electron dopings of 1-4 × 10 21 cm -3 , thermopowers as large in magnitude as 200 μV K -1 may be found. Such high thermopowers at such high carrier concentrations are extremely rare, and suggest that excellent thermoelectric performance may be found in these ranges of temperature and doping. (paper)

Corrosion of titanium alloys in high temperature near anaerobic seawater

International Nuclear Information System (INIS)

Pang, Jianjun; Blackwood, Daniel J.

2016-01-01

Highlights: • In absence of CO 2 Ti grades 2 and 5 suffer crevice corrosion at temperatures 80 °C and 200 °C. • For Ti grade 5 crevice corrosion can occur as low as 80 °C in the presence of CO 2 . • Ti grade 7 is immune to crevice corrosion in test conditions. • All grades resistant to SCC and pitting in presence of CO 2 . • Rare earth yttrium additions below 0.2 wt%. for improved mechanical properties are detrimental to corrosions performance. • Analysis of threat of hydrogen induced cracking suggest this is not a threat at a deepsea well head. - Abstract: Grades 2, 5 and Grade 7 were investigated in near anaerobic (<1 ppm oxygen) seawater up to 200 °C with and without CO 2 . All three grades were found to resist stress corrosion cracking and pitting corrosion. Grades 2 and 5 suffer crevice corrosion at temperatures 80 °C and 200 °C respectively. In the presence of CO 2 Grade 5 becomes more vulnerable to crevice corrosion, with attack starting at 80 °C with preferential dissolution of the beta phase. An analysis of the threat of hydrogen induced cracking leads to the conclusion that this was not a likely threat to any of the Ti alloys investigated.

High temperature corrosion investigations at AW2-bio. Final report; Biomass boiler

Energy Technology Data Exchange (ETDEWEB)

Borg, U.

2011-01-15

The measured corrosion rates in the test superheaters and ordinary superheaters of Avedoere 2 biomass boiler reveal that the corrosion rate increases with metal temperature and is significantly accelerated above steam temperatures of 540 deg. C. For the boiler with a live steam temperature of 540 deg. C, the measured corrosion rates in superheater 2 and 3 were up to 1mm pr. 10000 hours. It was observed that the flue gas temperature and heat flux had a significant effect on the corrosion rates through the surface metal temperature. Thus, the highest corrosion rates in the ordinary superheaters were not found at the position of the highest steam temperature in the outlet of superheater 3, but at the outlet of superheater 2. A steam temperature of approximately 580 deg. C at the outlet of one of the test superheater loops caused a tube fracture after a few months. A HVOF coating was applied to a section of superheater 2 and at a higher temperature in the test superheater loop. Analyses of the tube section after exposure showed that parts of the coating were not present and corrosion of the underlying TP347H FG was apparent. This indicates that the coating had spalled during operation. Furthermore, chlorine diffusion through the coating was observed causing attack at the coating-alloy interface. The project work has shown that it is not possible to increase the live steam temperature of the biomass fired boiler to more than 540 deg. C without a significant increase in superheater corrosion rates for the applied tube materials and coatings. (Author)

Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

Energy Technology Data Exchange (ETDEWEB)

Seifert, H.P

2002-02-01

The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

Stress corrosion cracking of austenitic stainless steel in high temperature and high pressure water

International Nuclear Information System (INIS)

Uragami, Ken

1977-01-01

Austenitic stainless steels used in for equipment in chemical plants have failed owing to stress corrosion cracking (SCC). These failures brought about great problems in some cases. The failures were caused by chloride, sulfide and alkali solution environment, in particular, by chloride solution environment. It was known that SCC was caused not only by high content chloride solution such as 42% MgCl 2 solution but also by high temperature water containing Cl - ions as NaCl. In order to estimate quantitatively the effects of some factors on SCC in high temperature water environment, the effects of Cl - ion contents, oxygen partial pressure (increasing in proportion to dissolved oxygen), pH and temperature were investigated. Moreover SCC sensitivity owing to the difference of materials and heat treatments was also investigated. The experimental results obtained are summarized as follows: (1) Regarding the effect of contaminant Cl - ions in proportion as Cl - ion contents increased, the material life extremely decreased owing to SCC. The tendency of decreasing was affected by the level of oxygen partial pressure. (2) Three regions of SCC sensitivity existed and they depended upon oxygen partial pressure. These were a region that did not show SCC sensitivity, a region of the highest SCC sensitivity and a region of somewhat lower SCC sensitivity. (3) In the case of SUS304 steel and 500 ppm Cl - ion contents SCC did not occur at 150 0 C, but it occurred and caused failures at 200 0 C and 250 0 C. (auth.)

Analysis of corrosion data for carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures

International Nuclear Information System (INIS)

Diercks, D.R.; Hull, A.B.; Kassner, T.F.

1988-03-01

Carbon steel is currently the leading candidate material for fabrication of a container for isolation of high level nuclear waste in a salt repository. Since brine entrapped in the bedded salt can migrate to the container by several transport processes, corrosion is an important consideration in the long-term performance of the waste package. A detailed literature search was performed to compile relevant corrosion data for carbon steels in anoxic acid chloride solutions, and simulated salt repository brines at temperatures between ∼ 20 and 400 0 C. The hydrolysis of Mg 2+ ions in simulated repository brines containing high magnesium concentrations causes acidification at temperatures above 25 0 C, which, in turn, influences the protective nature of the magnetite corrosion product layer on carbon steel. The corrosion data for the steels were analyzed, and an analytical model for general corrosion was developed to calculate the amount of penetration (i.e., wall thinning) as a function of time, temperature, and the pressure of corrosion product hydrogen than can build up during exposure in a closed system (e.g., a sealed capsule). Both the temperature and pressure dependence of the corrosion rate of steels in anoxic acid chloride solutions indicate that the rate-controlling partial reaction is the cathodic reduction of water to form hydrogen. Variations in the composition and microstructure of the steels or the concentration of the ionic species in the chloride solutions (provided that they do not change the pH significantly) do not appear to strongly influence the corrosion rate

Determination of sulfonamides and trimethoprim using high temperature HPLC with simultaneous temperature and solvent gradient.

Science.gov (United States)

Giegold, Sascha; Teutenberg, Thorsten; Tuerk, Jochen; Kiffmeyer, Thekla; Wenclawiak, Bernd

2008-10-01

A fast HPLC method for the analysis of eight selected sulfonamides (SA) and trimethoprim has been developed with the use of high temperature HPLC. The separation could be achieved in less than 1.5 min on a 50 mm sub 2 microm column with simultaneous solvent and temperature gradient programming. Due to the lower viscosity of the mobile phase and the increased mass transfer at higher temperatures, the separation could be performed on a conventional HPLC system obtaining peak widths at half height between 0.6 and 1.3 s.

Very high cycle fatigue crack initiation in electroplated Ni films under extreme stress gradients

International Nuclear Information System (INIS)

Baumert, E.K.; Pierron, O.N.

2012-01-01

A characterization technique based on kilohertz micro-resonators is presented to investigate the very high cycle fatigue behavior of 20 μm thick electroplated Ni films with a columnar microstructure (grain diameter less than 2 μm). The films exhibit superior fatigue resistance due to the extreme stress gradients at the surface. The effects of stress amplitude and environment on the formation of fatigue extrusions and micro-cracks are discussed based on scanning electron microscopy and the tracking of the specimens’ resonant frequency.

Burner rig alkali salt corrosion of several high temperature alloys

Science.gov (United States)

Deadmore, D. L.; Lowell, C. E.

1977-01-01

The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

Directory of Open Access Journals (Sweden)

Jianbo Sun

2016-03-01

Full Text Available The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.

Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

Science.gov (United States)

Sun, Jianbo; Sun, Chong; Lin, Xueqiang; Cheng, Xiangkun; Liu, Huifeng

2016-01-01

The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH)3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels. PMID:28773328

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

Science.gov (United States)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

High temperature materials and mechanisms

CERN Document Server

2014-01-01

The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues related to high-temperature materials and mechanisms that operate in harsh conditions. While some applications involve the use of materials at high temperatures, others require materials processed at high temperatures for use at room temperature. High-temperature materials must also be resistant to related causes of damage, such as oxidation and corrosion, which are accelerated with increased temperatures. This book examines high-temperature materials and mechanisms from many angles. It covers the topics of processes, materials characterization methods, and the nondestructive evaluation and health monitoring of high-temperature materials and structures. It describes the ...

Corrosion kinetics at high pressure and temperature of Zr-2.5 Nb with different heat treatments

International Nuclear Information System (INIS)

Jaime Solis, F.; Bordoni, Roberto; Olmedo, Ana M.; Villegas, Marina; Miyagusuku, Marcela

2003-01-01

The corrosion behaviour of Zr-2.5 Nb pressure tube (PT) specimens, with ageing treatments at 400 and 500 C degrees for different times, was studied. The results were analyzed using the corrosion behavior of Zr-20 Nb and Zr-1 Nb samples heat treated during 1 hour at 850 C degrees, cooled in air and aged at the same temperature and times than the PT specimens. The comparison between the corrosion behaviour of Zr-1 Nb and Zr-20 Nb aged coupons with the aged pressure tube specimens, together with the metal/oxide interface morphology of Zr-2.5 Nb specimens, suggest that the increase in the corrosion resistance in the latter coupons is associated with the decomposition of the β-Zr phase. There is also a contribution of α-Zr phase when the ageing temperatures are high enough or the ageing times are long enough, due to a decrease in the Nb content of this phase. This last contribution is associated with an increase in the corrosion resistance of the central zone of pressure tube in the reactor. (author)

High temperature corrosion of advanced ceramic materials for hot gas filters. Topical report for part 1 of high temperature corrosion of advanced ceramic materials for hot gas filters and heat exchangers

Energy Technology Data Exchange (ETDEWEB)

Spear, K.E.; Crossland, C.E.; Shelleman, D.L.; Tressler, R.E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

1997-12-11

This program consists of two separate research areas. Part 1, for which this report is written, studied the high temperature corrosion of advanced ceramic hot gas filters, while Part 2 studied the long-term durability of ceramic heat exchangers to coal combustion environments. The objectives of Part 1 were to select two candidate ceramic filter materials for flow-through hot corrosion studies and subsequent corrosion and mechanical properties characterization. In addition, a thermodynamic database was developed so that thermochemical modeling studies could be performed to simulate operating conditions of laboratory reactors and existing coal combustion power plants, and to predict the reactions of new filter materials with coal combustion environments. The latter would make it possible to gain insight into problems that could develop during actual operation of filters in coal combustion power plants so that potential problems could be addressed before they arise.

Assessment of very high temperature reactors in process applications

International Nuclear Information System (INIS)

Jones, J.E. Jr.; Spiewak, I.; Gambill, W.R.

1976-01-01

In April 1974, the United States Energy Research and Development Administration (ERDA) authorized General Atomic Company, General Electric Company, and Westinghouse Astronuclear Laboratory to assess the available technology for producing process heat utilizing a very high temperature nuclear reactor (VHTR). The VHTR is defined as a gas-cooled graphite-moderated reactor. Oak Ridge National Laboratory has been given a lead role in evaluating the VHTR reactor studies and potential applications of the VHTR. Process temperatures up to the 760 to 871 0 C range appear to be achievable with near-term technology. The major development considerations are high temperature materials, the safety questions (especially regarding the need for an intermediate heat exchanger) and the process heat exchanger. The potential advantages of the VHTR over competing fossil energy sources are conservation of fossil fuels and reduced atmospheric impacts. Costs are developed for nuclear process heat supplied from a 3000-MW(th) VHTR. The range of cost in process applications is competitive with current fossil fuel alternatives

Corrosion resistance of Fe-Al alloy-coated steel under bending stress in high temperature lead-bismuth eutectic

International Nuclear Information System (INIS)

Yamaki, Eriko; Takahashi, Minoru

2009-01-01

Formation of thin Fe-Al alloy layers on the surface of cladding and structural materials is effective to protect a base material from corrosion in high temperature LBE. However, it is concerned that these protective layers may be damaged under various stress conditions. This study on Fe-Al alloy coatings deposited by unbalanced magnetron sputtering (UBMS) is focused to evaluate corrosion resistance and integrity of the Fe-Al coating layers with thickness of 0.5 mm under bending stress in high temperature LBE. High chromium steel specimens (HCM12A, Recloy10) with Fe-Al alloy coating were exposed to LBE pool with low oxygen concentration (up to 5.2x10 -8 wt%) at 550 and 650degC under 45kg-loading for 240 and 500 h. No LBE corrosion was observed in the base metal and coating layer after the tests at 550degC for 550 h. The coating layers could be barrier for corrosion resistance from LBE at 550degC, although the coating scales are cracked by the load. At 650degC, because the base metal was contoccured directly with LBE through cracks across the coating layer. Penetration of LBE to base metal and dissolution of beset metal into LBE occurred. Fe-Al coating layer was not corroded by LBE. (author)

Rules for design of Alloy 617 nuclear components to very high temperatures

International Nuclear Information System (INIS)

Corum, J.M.; Blass, J.J.

1991-01-01

Very-high-temperature gas-cooled reactors provide attractive options for electric power generation using a direct gas-turbine cycle and for process-heat applications. For the latter, temperatures of at least 950 degree C (1742 degree F) are desirable. As a first step to providing rules for the design of nuclear components operating at very high temperatures, a draft ASME Boiler and Pressure Vessel Code Case has been prepared by an ad hoc Code task force. The Case, which is patterned after the high-temperature nuclear Code Case N-47, covers Ni-Cr-Co-Mo Alloy 617 for temperatures to 982 degree C (1800 degree F). The purpose of this paper is to provide a synopsis of the draft Case and the significant differences between it and Case N-47. Particular emphasis is placed on the material behavior and allowables. The paper also recommends some materials and structures development activities that are needed to place the design methodology on a sound and defensible footing. 4 refs., 9 figs., 1 tab

Effects of zinc injection on electrochemical corrosion and cracking behavior of stainless steels in borated and lithiated high temperature water

International Nuclear Information System (INIS)

Wu Xinqiang; Liu Xiahe; Han Enhou; Ke Wei

2014-01-01

Zinc (Zn) injection water chemistry (ZWC) adopted in primary coolant system in pressurized water reactors (PWRs) is to reduce the radiation buildup as well as retard the corrosion degradation in high temperature pressurized water through improving the characteristics of oxide scales formed on components materials. However, Zn injection involved corrosion and cracking behavior and related mechanisms are still under discussion. The understanding of Zn-bearing oxide scale characteristics and their protective property is of significance to clarify the environmentally assisted material failure problems in PWRs power plants. In the present work, in-situ potentiodynamic polarization curves and electrochemical impedance spectra measurements in high temperature borated and lithiated water as well as ex-situ X-ray photoelectron spectroscopy analyses have been done to investigate the effects of temperature (R.T.-603 K), pH T value at 573 K (6.9-7.4) and Zn-injection concentration (0-150 ppb) on electrochemical corrosion behavior and oxide scale characteristics of nuclear-grade stainless steels. The protective property of oxide scales under Zn-free and Zn-injected conditions degraded with increasing temperature, with Cr-rich oxide layer playing a key role on retarding further corrosion. The composition of oxide scales appeared slightly pH T dependent: rich in chromites and ferrites at pH T =6.9 and pH T =7.4, respectively. The corrosion rate decreased significantly in the high pH T value solution with Zn injection due to the formation of thin and compact oxide scales. The ≤50 ppb Zn injection could significantly affect the formation of Zn-bearing oxides on the surfaces, while >50 ppb Zn injection showed no obvious influence on the oxide scales. A modified point defect model was proposed to discuss the effects of injected Zn concentrations on the oxide scales in high temperature water. A 10 ppb Zn injection obviously decreased the intergranular cracking susceptibility of

Very High Cycle Fatigue of Ni-Based Single-Crystal Superalloys at High Temperature

Science.gov (United States)

Cervellon, A.; Cormier, J.; Mauget, F.; Hervier, Z.; Nadot, Y.

2018-05-01

Very high cycle fatigue (VHCF) properties at high temperature of Ni-based single-crystal (SX) superalloys and of a directionally solidified (DS) superalloy have been investigated at 20 kHz and a temperature of 1000 °C. Under fully reversed conditions (R = - 1), no noticeable difference in VHCF lifetimes between all investigated alloys has been observed. Internal casting pores size is the main VHCF lifetime-controlling factor whatever the chemical composition of the alloys. Other types of microstructural defects (eutectics, carbides), if present, may act as stress concentration sites when the number of cycles exceed 109 cycles or when porosity is absent by applying a prior hot isostatic pressing treatment. For longer tests (> 30 hours), oxidation also controls the main crack initiation sites leading to a mode I crack initiation from oxidized layer. Under such conditions, alloy's resistance to oxidation has a prominent role in controlling the VHCF. When creep damage is present at high ratios (R ≥ 0.8), creep resistance of SX/DS alloys governs VHCF lifetime. Under such high mean stress conditions, SX alloys developed to retard the initiation and creep propagation of mode I micro-cracks from pores have better VHCF lifetimes.

Effect of Carbide Dissolution on Chlorine Induced High Temperature Corrosion of HVOF and HVAF Sprayed Cr3C2-NiCrMoNb Coatings

Science.gov (United States)

Fantozzi, D.; Matikainen, V.; Uusitalo, M.; Koivuluoto, H.; Vuoristo, P.

2018-01-01

Highly corrosion- and wear-resistant thermally sprayed chromium carbide (Cr3C2)-based cermet coatings are nowadays a potential highly durable solution to allow traditional fluidized bed combustors (FBC) to be operated with ecological waste and biomass fuels. However, the heat input of thermal spray causes carbide dissolution in the metal binder. This results in the formation of carbon saturated metastable phases, which can affect the behavior of the materials during exposure. This study analyses the effect of carbide dissolution in the metal matrix of Cr3C2-50NiCrMoNb coatings and its effect on chlorine-induced high-temperature corrosion. Four coatings were thermally sprayed with HVAF and HVOF techniques in order to obtain microstructures with increasing amount of carbide dissolution in the metal matrix. The coatings were heat-treated in an inert argon atmosphere to induce secondary carbide precipitation. As-sprayed and heat-treated self-standing coatings were covered with KCl, and their corrosion resistance was investigated with thermogravimetric analysis (TGA) and ordinary high-temperature corrosion test at 550 °C for 4 and 72 h, respectively. High carbon dissolution in the metal matrix appeared to be detrimental against chlorine-induced high-temperature corrosion. The microstructural changes induced by the heat treatment hindered the corrosion onset in the coatings.

High Temperature Chemistry at NASA: Hot Topics

Science.gov (United States)

Jacobson, Nathan S.

2014-01-01

High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

Stress corrosion cracking behaviour of Alloy 600 in high temperature water

International Nuclear Information System (INIS)

Webb, G.L.; Burke, M.G.

1995-01-01

The stress corrosion cracking (SCC) susceptibility of Alloy 600 in deaerated water at 360 deg. C, as measured with statistically-loaded U-bend specimens, is dependent upon microstructure and whether the material was cold-worked and annealed (CWA) or hot-worked and annealed (HWA). All cracking was intergranular, and materials lacking grain boundary carbides were most susceptible to SCC initiation. CWA tubing materials are more susceptible to SCC initiation than HWA ring-rolled forging materials with similar microstructures, as determined by light optical metallography (LOM). In CWA tubing materials one crack dominated and grew to a large size that was observable by visual inspection. HWA materials with a low hot-working finishing temperature (below 925 deg. C) and final anneals at temperatures ranging from 1010 deg. C to 1065 deg. C developed both large cracks, similar to those found in CWA materials, and also small intergranular microcracks, which are detectable only by destructive metallographic examination. HWA materials with a high hot-working finishing temperature (above 980 deg. C) and high-temperature final anneal (above 1040 deg. C), with grain boundaries that are fully decorated, developed only microcracks, which were observed in all specimens examined. These materials developed no large, visually detectable cracks, even after more than 300 weeks exposure. A low-temperature thermal treatment (610 deg. C for 7h), which reduced or eliminates SCC in Alloy 600, did not eliminate microcrack formation in the high temperature processed HWA materials. Detailed microstructural characterization using conventional metallographic and analytical electron microscopy (AEM) techniques was performed on selected materials to identify the factors responsible for the observed differences in cracking behaviour. 11 refs, 12 figs, 3 tabs

Is KCl(g) corrosive at temperatures above its dew point? Influence of KCl(g) on initial stages of the high temperature corrosion of 11% Cr steel at 600 C

Energy Technology Data Exchange (ETDEWEB)

Segerdahl, K.; Pettersson, J.; Svensson, J.E.; Johansson, L.G. [Dept. of Environmental Inorganic Chemistry, High Temperature Corrosion Centre, Chalmers Univ. of Technology, Goeteborg (Sweden)

2004-07-01

The influence of gaseous KCl on the high temperature oxidation of CrMoV11 1 (X20) steel at 600 C is reported. The sample temperature was above the dew point of KCl, the partial pressure of KCl being about 5ppm. The samples were investigated by a number of surface analytical techniques including grazing angle XRD, SEM/EDX, and SAM. CrMoV11 1 steel shows protective behaviour in clean dry O{sub 2} and O{sub 2}/H{sub 2}O environment because of the formation of a chromium-rich oxide ({alpha}-(Fe,Cr){sub 2}O{sub 3}). It is often considered that alkali salts accelerate the corrosion of steel only when present on the surface in solid or liquid form. In contrast, the present result shows that gaseous KCl is very corrosive, also in the absence of condensation. KCl(g) reacts with chromium in the scale, forming K{sub 2}CrO{sub 4}(s). This depletes the protective oxide in chromium and leads to the formation of non-protective hematite, Fe{sub 2}O{sub 3}. (orig.)

Electrochemical cell and electrode designs for high-temperature/high-pressure kinetic measurements

International Nuclear Information System (INIS)

Nagy, Z.; Yonco, R.M.

1987-05-01

Many corrosion processes of interest to the nuclear power industry occur in high-temperature/high-pressure aqueous systems. The investigation of the kinetics of the appropriate electrode reactions is a serious experimental challenge, partially because of the high temperatures and pressures and partially because many of these reactions are very rapid, requiring fast relaxation measurements. An electrochemical measuring system is described which is suitable for measurements of the kinetics of fast electrode reactions at temperatures extending to at least 300 0 C and pressures to at least 10 MPa (100 atmospheres). The system includes solution preparation and handling equipment, the electrochemical cell, and several electrode designs. One of the new designs is a coaxial working electrode-counter electrode assembly; this electrode can be used with very fast-rising pulses, and it provides a well defined, repeatedly-polishable working surface. Low-impedance reference electrodes are also described, based on electrode concepts responding to the pH or the redox potential of the test solution. Additionally, a novel, long-life primary reference electrode design is reported, based on a modification of the external, pressure-balanced Ag/AgCl reference electrode

Electrochemical cell and electrode designs for high-temperature/high-pressure kinetic measurements

International Nuclear Information System (INIS)

Nagy, Z.; Yonco, R.M.

1988-01-01

Many corrosion processes of interest to the nuclear power industry occur in high-temperature/high-pressure aqueous systems. The investigation of the kinetics of the appropriate electrode reactions is a serious experimental challenge, partially because of the high temperatures and pressures and partially because many of these reactions are very rapid, requiring fast relaxation measurements. An electrochemical measuring system is described which is suitable for measurements of the kinetics of fast electrode reactions at temperatures extending to at least 300 0 C and pressures to at least 10 MPa (100 atmospheres). The system includes solution preparation and handling equipment, the electrochemical cell, and several electrode designs. One of the new designs is a coaxial working electrode-counter electrode assembly; this electrode can be used with very fast-rising pulses, and it provides a well defined, repeatedly-polishable working surface. Low-impedance reference electrodes are also described, based on electrode concepts responding to the pH or the redox potential of the test solution. Additionally, a novel, long-life primary reference electrode design is reported, based on a modification of the external, pressure-balanced Ag/AgCl reference electrode

High temperature vapors science and technology

CERN Document Server

Hastie, John

2012-01-01

High Temperature Vapors: Science and Technology focuses on the relationship of the basic science of high-temperature vapors to some areas of discernible practical importance in modern science and technology. The major high-temperature problem areas selected for discussion include chemical vapor transport and deposition; the vapor phase aspects of corrosion, combustion, and energy systems; and extraterrestrial high-temperature species. This book is comprised of seven chapters and begins with an introduction to the nature of the high-temperature vapor state, the scope and literature of high-temp

High Temperature Corrosion of Superheater Materials for Power Production through Biomass

DEFF Research Database (Denmark)

Montgomery, Melanie; Maahn, Ernst emanuel; Nielsen, Karsten agersted

The aim of the present study has been to establish a fundamental knowledge of the corrosion mechanisms acting on materials for use in biomass fired power plants. The knowledge is created based on laboratory exposures on selected materials in well-defined corrosive gas environments. An experimental...... facility has been established wherein the planned exposures are completed. Specimens were exposed in combined synthetic flue gas at temperatures up to 900C. The specimens could be cooled to 300C below the gas temperature. Gas flow and gas mixture can be varied according to the conditions found in a power......) on the corrosion progress has been investigated.In addition the corrosion behaviour of the same materials was investigated after having been exposed under a cover of ash in air in a furnace at temperatures of 525C, 600C and 700C. The ashes utilised are from a straw-fired power plant and a synthetic ash composed...

Thermo chemical calculations applied to the study of ceramic corrosion at high temperature - Steel-making applications; Apport de la thermodynamique a l'etude de la corrosion des ceramiques a haute temperature - Applications siderurgiques

Energy Technology Data Exchange (ETDEWEB)

Poirier, J. [Orleans Univ., Polytechnique, 45 (France); Centre National de la Recherche Scientifique (CNRS/CEMHTI), 45 - Orleans-la-Source (France)

2008-05-15

At high temperature, corrosion by gas, slag or metal is recognized in many cases as the essential degradation mode of ceramics. The reaction between the ceramic and the corrosive agent should be described taking into account both the kinetic aspects (rates and mechanisms of the reactions) and the thermodynamic aspects (equilibrium conditions). After a short description of the thermodynamic tools, we will show how some thermo chemical calculations, involving complex multi-component systems at high temperature, can be applied to explain some practical situations. Different examples, from steel making, will be considered: effects of composition changes upon the stability of the refractories and reactions of corrosion between the refractories, the gas and the liquid oxides. (author)

Supercritical water corrosion of high Cr steels and Ni-base alloys

International Nuclear Information System (INIS)

Jang, Jin Sung; Han, Chang Hee; Hwang, Seong Sik

2004-01-01

High Cr steels (9 to 12% Cr) have been widely used for high temperature high pressure components in fossil power plants. Recently the concept of SCWR (supercritical water-cooled reactor) has aroused a keen interest as one of the next generation (Generation IV) reactors. Consequently Ni-base (or high Ni) alloys as well as high Cr steels that have already many experiences in the field are among the potential candidate alloys for the cladding or reactor internals. Tentative inlet and outlet temperatures of the anticipated SCWR are 280 and 510 .deg. C respectively. Among many candidate alloys there are austenitic stainless steels, Ni base alloys, ODS alloys as well as high Cr steels. In this study the corrosion behavior of the high Cr steels and Ni base (or high Ni) alloys in the supercritical water were investigated. The corrosion behavior of the unirradiated base metals could be used in the near future as a guideline for the out-of-pile or in-pile corrosion evaluation tests

Localized corrosion information using high resolution measurement devices

DEFF Research Database (Denmark)

Ambat, Rajan

2005-01-01

High performance demand for several engineering alloys and components, and miniaturization of electronics and development of MEMS requires better understanding of local corrosion characteristics frequently down to µm scale. This is because in metallic materials corrosion is a sensitive function...... in conjunction with microstructural analysis, using advanced microscopic tools, becomes very important. Corrosion of microelectronics circuits and MEMs is also a recent problem, which demands measurement resolution down to few microns as the components are extremely small, and measurement needs to be carried out...

Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: Electrochemical studies

International Nuclear Information System (INIS)

Olmedo, A.M.; Villegas, M.; Alvarez, M.G.

1996-01-01

The anodic behaviour and passivity breakdown of Alloy 800 in aqueous solutions of sodium chloride, sodium sulphate and sodium bicarbonate were studied by electrochemical techniques in the temperature range from 60 C to 280 C. The pitting resistance and pitting morphology of the alloy in chloride plus sulphate and chloride plus bicarbonate mixtures, at 60 C and 280 C, were also examined. Increasing bicarbonate or sulphate additions to chloride solutions shift the characteristic pitting potential of Alloy 800 to higher values, both at low and high temperatures. Changes in pitting morphology were observed in sulphate containing solutions while the morphology of the attack found in bicarbonate containing solutions was similar to that in pure chloride solutions. Finally, no localized or substantial generalized corrosion was detected in pure sulphate or bicarbonate solutions at any temperature. (orig.)

Acoustic emission analysis coupled with thermogravimetric experiments dedicated to high temperature corrosion studies on metallic alloys

International Nuclear Information System (INIS)

Serris, Eric; Al Haj, Omar; Peres, Veronique; Cournil, Michel; Kittel, Jean; Grosjean, Francois; Ropital, Francois

2014-01-01

High temperature corrosion of metallic alloys (like iron, nickel, zirconium alloys) can damage equipment of many industrial fields (refinery, petrochemical, nuclear..). Acoustic emission (AE) is an interesting method owing to its sensitivity and its non-destructive aspect to quantify the level of damage in use of these alloys under various environmental conditions. High temperature corrosive phenomena create stresses in the materials; the relaxation by cracks of these stresses can be recorded and analyzed using the AE system. The goal of our study is to establish an acoustic signals database which assigns the acoustic signals to the specific corrosion phenomena. For this purpose, thermogravimetric analysis (TGA) is coupled with acoustic emission (AE) devices. The oxidation of a zirconium alloy, zircaloy-4, is first studied using thermogravimetric experiment coupled to acoustic emission analysis at 900 C. An inward zirconium oxide scale, preliminary dense, then porous, grow during the isothermal isobaric step. The kinetic rate increases significantly after a kinetic transition (breakaway). This acceleration occurs with an increase of acoustic emission activity. Most of the acoustic emission bursts are recorded after the kinetic transition. Acoustic emission signals are also observed during the cooling of the sample. AE numerical treatments (using wavelet transform) completed by SEM microscopy characterizations allows us to distinguish the different populations of cracks. Metal dusting represents also a severe form of corrosive degradation of metal alloy. Iron metal dusting corrosion is studied by AE coupled with TGA at 650 C under C 4 H 10 + H 2 + He atmosphere. Acoustic emission signals are detected after a significant increase of the sample mass.

Tailoring a High Temperature Corrosion Resistant FeNiCrAl for Oxy-Combustion Application by Thermal Spray Coating and HIP

Directory of Open Access Journals (Sweden)

Jarkko Metsäjoki

2015-10-01

Full Text Available Oxy-fuel combustion combined with CCS (carbon capture and storage aims to decrease CO2 emissions in energy production using fossil fuels. Oxygen firing changes power plant boiler conditions compared to conventional firing. Higher material temperatures and harsher and more variable environmental conditions cause new degradation processes that are inadequately understood at the moment. In this study, an Fe-Ni-Cr-Al alloy was developed based on thermodynamic simulations. The chosen composition was manufactured as powder by gas atomization. The powder was sieved into two fractions: The finer was used to produce thermal spray coatings by high velocity oxy-fuel (HVOF and the coarser to manufacture bulk specimens by hot isostatic pressing (HIP. The high temperature corrosion properties of the manufactured FeNiCrAl coating and bulk material were tested in laboratory conditions simulating oxy-combustion. The manufacturing methods and the results of high temperature corrosion performance are presented. The corrosion performance of the coating was on average between the bulk steel references Sanicro 25 and TP347HFG.

Effect of Water Vapor on High-Temperature Corrosion under Conditions Mimicking Biomass Firing

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

2015-01-01

The variable flue gas composition in biomass-fired plants, among other parameters, contributes to the complexityof high-temperature corrosion of materials. Systematic parameter studies are thus necessary to understand the underlyingcorrosion mechanisms. This paper investigates the effect of water...... (H2O) vapor content in the flue gas on the high-temperaturecorrosion of austenitic stainless steel (TP 347H FG) under laboratory conditions, to improve the understanding of corrosionmechanisms. Deposit-coated and deposit-free samples were isothermally exposed for 72 h in a synthetic flue gas...... previouslyreported findings suggest that an increase in the water vapor content will cause competitive adsorption on active sites....

Deposition and high temperature corrosion in a 10 MW straw

DEFF Research Database (Denmark)

Michelsen, Hanne Philbert; Frandsen, Flemming; Dam-Johansen, Kim

1998-01-01

Deposition and corrosion measurements were conducted at a 10 MW wheat straw fired stoker boiler used for combined power and heat production. The plant experiences major problems with deposits on the heat transfer surfaces, and test probes have shown enhanced corrosion due to selective corrosion...... for metal temperatures above 520 C. Deposition measurements carried out at a position equal to the secondary superheater showed deposits rich in potassium and chlorine and to a lesser extent in silicon, calcium, and sulfur. Potassium and chlorine make up 40-80 wt% of the deposits. Mechanisms of deposit...

Very High Temperature Test of Alloy617 Compact Heat Exchanger in Helium Experimental Loop

Energy Technology Data Exchange (ETDEWEB)

Kim, Chan Soo; Park, Byung-Ha; Kim, Eung-Seon [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The Intermediate Heat eXchanger (IHX) is a key-challenged high temperature component which determines the efficiency and the economy of VHTR system. Heat generated in the VHTR fuel block is transferred from the VHTR to the intermediate loop through IHX. In the present, the shell-helical tube heat exchanger is generally used as IHX of the helium cooled reactor. Recently, a Printed Circuit Heat Exchanger (PCHE) is one of the candidates for the IHX in a VHTR because its operation temperature and pressure are larger than any other compact heat exchanger types. These test results show that there is no problem in operation of HELP at the very high temperature experimental condition and the alloy617 compact heat exchanger can be operated in the very high temperature condition above 850℃. In the future, the high temperature structural analysis will be studied to estimate the thermal stress during transient and thermal shock condition. The conditions and evaluation standard for the alloy 617 diffusion bonding will be minutely studied to fabricate the large-scale PCHE for the high temperature condition.

Pressure pressure-balanced pH sensing system for high temperature and high pressure water

International Nuclear Information System (INIS)

Tachibana, Koji

1995-01-01

As for the pH measurement system for high temperature, high pressure water, there have been the circumstances that first the reference electrodes for monitoring corrosion potential were developed, and subsequently, it was developed for the purpose of maintaining the soundness of metallic materials in high temperature, high pressure water in nuclear power generation. In the process of developing the reference electrodes for high temperature water, it was clarified that the occurrence of stress corrosion cracking in BWRs is closely related to the corrosion potential determined by dissolved oxygen concentration. As the types of pH electrodes, there are metal-hydrogen electrodes, glass electrodes, ZrO 2 diaphragm electrodes and TiO 2 semiconductor electrodes. The principle of pH measurement using ZrO 2 diaphragms is explained. The pH measuring system is composed of YSZ element, pressure-balanced type external reference electrode, pressure balancer and compressed air vessel. The stability and pH response of YSZ elements are reported. (K.I.)

Purification of power plant waters with high gradient magnetic filters

International Nuclear Information System (INIS)

Rosenberg, R.

1993-04-01

This is a report of a literature survey. Magnetic high gradient filtration is suitable for separations in difficult surroundings because it can be used in high pressure and temperature, the filtration can be automated and the filter does not contain components which have to be replaced. Magnetic separators for purification of power plant waters have been manufactured commercially for a long time, but they have not always worked satisfactorily especially when separating small particles. The corrosion products in power plant waters are usually ferrimagnetic or paramagnetic and are well suited for magnetic separation. The particle sizes varies considerable but at least in nuclear power plants they are mostly in the range 0.1-30 μ, some even smaller. According to different publications most 60 Co is in particles, while other publications indicate that more than 70 % is in solution. Similarly the data on the purification efficiency of 60 Co varies significantly. Even small magnetic fields are sufficient to separate large ferrimagnetic particles, but the separation of small and paramagnetic particles requires a field more than 20 kT and the high gradient. Presently available commercial separators are so efficient that its seems not to be economically worthwhile to develop them further to improve the filtration efficiency for small particles. Instead it might be worthwhile to investigate methods to increase the particle size by water chemistry methods. (Au). (25 refs., 2 figs.)

The precious metal effect in high temperature corrosion

Energy Technology Data Exchange (ETDEWEB)

Wit, J.H.W. de (Lab. for Materials Science, Delft Univ. of Technology (Netherlands)); Manen, P.A. van (Lab. for Materials Science, Delft Univ. of Technology (Netherlands))

1994-01-01

Additions of platinum and to a smaller extent rhodium, to aluminium oxide forming alloys are known to improve the high temperature corrosion resistance of the alloys. This effect is known as the ''precious metal effect''. The expensive Pt-additions are used because of the increased lifetime of turbine-vanes especially in marine environments. Only a limited number of coating systems is commercially available, as JML-1, LDC-2 and RT22. Normally Pt is deposited electrochemically or by a fused salt method. After deposition the high or low activity pack-cementation-process is applied to obtain a PtNiAl-coating. In this paper the effect of platinum on the oxidation mechanism is discussed by comparing the oxidation mechanism of [beta]-NiAl and Pt20Ni30Al50. This composition agrees with the average composition of a platinum modified aluminide coating. The alloys were oxidized at temperatures from 1000 to 1200 C. The growth of the oxide scale on the NiAl alloy proceeds both by aluminium and by oxygen diffusion through the scale resulting in growth within the scale. On Pt20Ni30Al50 the growth of the scale is limited to the oxide/gas interface due to a predominant aluminium transport through the scale. The morphology of the oxide scales did not show large differences. However, the extensive void formation at the [beta]-NiAl/oxide interface was not observed on the Pt20Ni30Al50 samples. The absence of voids at the interface and the reduction of growth stresses, as a result of the outward growth of the scale, are the two likely reasons for the improved oxide scale adherence and can thus be considered, to be two elements of the ''precious metal effect''. (orig.)

Effect of corrosion potential on the corrosion fatigue crack growth behaviour of low-alloy steels in high-temperature water

International Nuclear Information System (INIS)

Ritter, S.; Seifert, H.P.

2008-01-01

The low-frequency corrosion fatigue (CF) crack growth behaviour of different low-alloy reactor pressure vessel steels was characterized under simulated boiling water reactor conditions by cyclic fatigue tests with pre-cracked fracture mechanics specimens. The experiments were performed in the temperature range of 240-288 deg. C with different loading parameters at different electrochemical corrosion potentials (ECPs). Modern high-temperature water loops, on-line crack growth monitoring (DCPD) and fractographical analysis by SEM were used to quantify the cracking response. In this paper the effect of ECP on the CF crack growth behaviour is discussed and compared with the crack growth model of General Electric (GE). The ECP mainly affected the transition from fast ('high-sulphur') to slow ('low-sulphur') CF crack growth, which appeared as critical frequencies ν crit = f(ΔK, R, ECP) and ΔK-thresholds ΔK EAC f(ν, R, ECP) in the cycle-based form and as a critical air fatigue crack growth rate da/dt Air,crit in the time-domain form. The critical crack growth rates, frequencies, and ΔK EAC -thresholds were shifted to lower values with increasing ECP. The CF crack growth rates of all materials were conservatively covered by the 'high-sulphur' CF line of the GE-model for all investigated temperatures and frequencies. Under most system conditions, the model seems to reasonably well predict the experimentally observed parameter trends. Only under highly oxidizing conditions (ECP ≥ 0 mV SHE ) and slow strain rates/low loading frequencies the GE-model does not conservatively cover the experimentally gathered crack growth rate data. Based on the GE-model and the observed cracking behaviour a simple time-domain superposition-model could be used to develop improved reference CF crack growth curves for codes

The metallurgy of high temperature alloys

Science.gov (United States)

Tien, J. K.; Purushothaman, S.

1976-01-01

Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

KCl-induced high temperature corrosion of selected commercial alloys. Part II: alumina and silica-formers

DEFF Research Database (Denmark)

Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie

2016-01-01

for 168 h in flowing N2(g)+5%O2(g)+15%H2O(g) (vol.%) with samples covered under KCl powder. A KCl-free exposure was also performed for comparison.Corrosion morphology and products were studied with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD......Laboratory testing on selected alumina and silica-forming alloys was performed to evaluate their performance against high temperature corrosion induced by potassium chloride (KCl). The alloys studied were FeCrAlY, Kanthal APM, Nimonic 80A, 214, 153MA and HR160. Exposure was conducted at 600 °C......-chromium-silicon-oxygen containing layer forms as the innermost corrosion product. The layer was uniformly distributed over the surface and appears to render some protection as this alloy exhibited the best performance among the investigated alloys. To reveal further aspects of the corrosion mechanism, Nimonic 80A was exposed...

Novel, Functionally Graded Coating System for Reusable, Very High Temperature Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This proposal addresses some of the most challenging materials issues with respect to multi-mission, very high temperature, up to 4000°F, applications. The very...

Laboratory Study of High Temperature Corrosion in Straw-fired Power Plants

DEFF Research Database (Denmark)

Montgomery, Melanie; Maahn, Ernst emanuel

1997-01-01

The components contributing to corrosion, HCl(g)SO2(g), KCl and K2SO4 were studied in the laboratory for Sandvik 8LR30 and Sanicro 28. The influence of HCl and SO2 was investigated at 600C material temperature and 600/800C flue gas temperature at time intervals up to 300 hours. The influence of ash...... deposits in air was examined at 525C-700C. Finally exposures were undertaken combining the aforementioned aggressive gas environment with the ash deposits. Thus the corrosion potential of individual components were evaluated and also whether they had a synergistic, antagonistic or additive effect on one...... another to influence the overall corrosion rate....

Design and proof of concept of an innovative very high temperature ceramic solar absorber

Science.gov (United States)

Leray, Cédric; Ferriere, Alain; Toutant, Adrien; Olalde, Gabriel; Peroy, Jean-Yves; Chéreau, Patrick; Ferrato, Marc

2017-06-01

Hybrid solar gas-turbine (HSGT) is an attractive technology to foster market penetration of CSP. HSGT offers some major advantages like for example high solar-to-electric conversion efficiency, reduced water requirement and low capital cost. A very high temperature solar receiver is needed when elevated solar share is claimed. A few research works, as reported by Karni et al. [8] and by Buck et al. [1], have been dedicated to solar receiver technologies able to deliver pressurized air at temperature above 750°C. The present work focuses on research aiming at developing an efficient and reliable solar absorber able to provide pressurized air at temperature up to 1000°C and more. A surface absorber technology is selected and a modular design of receiver is proposed in which each absorber module is made of BOOSTEC® SiC ceramic (silicon carbide) as bulk material with straight air channels inside. Early stage experimental works done at CNRS/PROMES on lab-scale absorbers showed that the thermo-mechanical behavior of this material is a critical issue, resulting in elevated probability of failure under severe conditions like large temperature gradient or steep variation of solar flux density in situations of cloud covering. This paper reports on recent progress made at CNRS/PROMES to address this critical issue. The design of the absorber has been revised and optimized according to thermo-mechanical numerical simulations, and an experimental proof of concept has been done on a pilot-scale absorber module at Themis solar tower facility.

A study on heat resistance of high temperature resistant coating

Energy Technology Data Exchange (ETDEWEB)

Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu [Research Institute of Engineering Technology of CNPC, Tianjin (China)

2005-04-15

A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

A study on heat resistance of high temperature resistant coating

International Nuclear Information System (INIS)

Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu

2005-01-01

A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings

International Nuclear Information System (INIS)

Farmer, J C; Haslam, J J; Wong, F; Ji, X; Day, S D; Branagan, D J; Marshall, M C; Meacham, B E; Buffa, E J; Blue, C A; Rivard, J K; Beardsley, M B; Weaver, D T; Aprigliano, L F; Kohler, L; Bayles, R; Lemieux, E J; Wolejsza, T M; Martin, F J; Yang, N; Lucadamo, G; Perepezko, J H; Hildal, K; Kaufman, L; Heuer, A H; Ernst, F; Michal, G M; Kahn, H; Lavernia, E J

2004-01-01

The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an ''integral drip shield'' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent

Thermoelectric properties of high electron concentration materials under large temperature gradients

International Nuclear Information System (INIS)

Bulat, L.P.; Stefansky, V.A.

1994-01-01

Theoretical methods of investigating of transport properties in solids under large temperature gradients are grounded. The nonlinear and non-local expressions for current density and heat flow are obtained with degenerated of current carriers gas. A number of new effects with large temperature gradients have been tested. Use of large temperature gradients leads to the increasing of the thermoelectric figure of merit. copyright 1995 American Institute of Physics

Application of new design methodologies to very high-temperature metallic components of the HTTR

International Nuclear Information System (INIS)

Hada, Kazuhiko; Ohkubo, Minoru; Baba, Osamu

1991-01-01

The high-temperature piping and helium-to-helium intermediate heat exchanger of the High-Temperature Engineering Test Reactor (HTTR) are designed to be operating at very high temperatures of about 900deg C among the class 1 components of the HTTR. At such a high temperature, mechanical strength of heat-resistant metallic materials is very low and thermal expansions of structural members are large. Therefore, innovative design methodologies are needed to reduce both mechanical and thermal loads acting on these components. To the HTTR, the design methodologies which can separate the heat-resistant function from the pressure-retaining functions and allow them to expand freely are applied to reduce pressure and thermal loads. Since these design methodologies need to verify their applicability, the Japan Atomic Energy Research Institute (JAERI) has been performing many design and research works on their verifications. The details of the design methodologies and their verifications are given in this paper. (orig.)

Corrosion of high temperature resisting alloys exposed to heavy fuel ash; Corrosion de aleaciones resistentes a altas temperaturas expuestas a ceniza de combustoleo pesado

Energy Technology Data Exchange (ETDEWEB)

Wong Moreno, Adriana del Carmen

1998-03-01

The objective of the performed research was to study the degradation process by high temperature corrosion of alloys exposed to heavy fuel oil ashes through a comparative experimental evaluation of its performance that allowed to establish the mechanisms involved in the phenomenon. The experimentation carried out involved the determination of the resistance to the corrosion of 14 alloys of different type (low and medium alloy steels, ferritic and austenitic stainless steels, nickel base alloys and a FeCrAl alloy of type ODS) exposed to high temperatures (580 Celsius degrees - 900 Celsius degrees) in 15 ash deposits with different corrosive potential, which were collected in the high temperature zone of boilers of thermoelectric power stations. The later studies to the corrosion tests consisted of the analysis by sweeping electron microscopy supported by microanalysis of the corroded probes, with the purpose of determining the effect of Na, V and S on the corrosivity of the ash deposits and the effect of the main alloying elements on the corrosion resistance of the alloys. Such effects are widely documented to support the proposed mechanisms of degradation that are occurring. The global analysis of the generated results has allowed to propose a model to explain the global mechanism of corrosion of alloys exposed to the high temperatures of ash deposits. The proposed model, complements the processed one by Wilson, widely accepted for fused vanadates, as far as on one hand, it considers the effect of the sodium sulfate presence (in addition to the vanadium compounds) in the deposits, and on the other hand, it extends it to temperatures higher than the point of fusion of constituent vanadium compounds of the deposits. Both aspects involve considering the roll that the process of diffusion of species has on the degradation and the capacity of protection of the alloy. The research performed allowed to confirm what the Wilson model had established for deposits with high

A probabilistic consequence assessment for a very high temperature reactor

Energy Technology Data Exchange (ETDEWEB)

Lee, Joeun; Kim, Jintae; Jae, Moosung [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Nuclear Engineering

2017-02-15

Currently, fossil fuel is globally running out. If current trends continue, crude oil will be depleted in 20 years and natural gas in 40 years. In addition, the use of fossil resource has increased emissions of green gas such as carbon dioxide. Therefore, there has been a strong demand in recent years for producing large amounts of hydrogen as an alternative energy [1]. To generate hydrogen energy, very high temperature more than 900 C is required but this level is not easy to reach. Because a Very High Temperature Reactor (VHTR), one of next generation reactor, is able to make the temperature, it is regarded as a solution of the problem. Also, VHTR has an excellent safety in comparison with existing and other next generation reactors. Especially, a passive system, Reactor Cavity Cooling System (RCCS), is adopted to get rid of radiant heat in case of accidents. To achieve variety requirements of new designed-reactors, however, it needs to develop new methodologies and definitions different with existing method. At the same time, an application of probability safety assessment (PSA) has been proposed to ensure the safety of next generation NPPs. For this, risk-informed designs of structures have to be developed and verified. Particularly, the passive system requires to be evaluated for its reliability. The objective of this study is to improve safety of VIITR by conducting risk profile.

High temperature electrochemistry related to light water reactor corrosion

International Nuclear Information System (INIS)

Nagy, Gabor; Kerner, Zsolt; Balog, Janos; Schiller, Robert

2004-01-01

The present work deals with corrosion problems related to conditions which prevail in a WWER primary circuit. We had a two-fold aim: (A) electrochemical methods were applied to characterise the hydrothermally produced oxides of the cladding material (Zr-1%Nb) of nuclear fuel elements used in Russian made power reactors of WWER type, and (B) a number of possible reference electrodes were investigated with a view to high temperature applications. (A) Test specimens made of the cladding material, Zr-1%Nb, were immersed into an autoclave, filled with an aqueous solution typical to a WWER primary circuit, and were treated for different periods of time up to 28 weeks. The electrode potentials were measured and electrochemical impedance spectra (EIS) were taken regularly both as a function of oxidation time and temperature. This rendered information on the overall kinetics of oxide growth. By combining in situ and ex situ impedance measurements, with a particular view of the temperature dependence of EIS, we concluded that the high frequency region of impedance spectra is relevant to the presence of oxide layer on the alloy. This part of the spectra was treated in terms of a parallel CPE||R ox equivalent circuit (CPE denoting constant phase element, R ox ohmic resistor). The CPE element was understood as a dispersive resistance in terms of the continuous time random walk theory by Scher and Lax. This enabled us to tell apart electrical conductance and oxide growth with a model of charge transfer and recombination within the oxide layer as rate determining steps. (B) Three types of reference electrodes were tested within the framework of the LIRES EU5 project: (i) external Ag/AgCl, (ii) Pt/Ir alloy and (iii) Pd(Pt) double polarised active electrode. The most stable of the electrodes was found to be the Pt/Ir one. The Ag/AgCl electrode showed good stability after an initial period of some days, while substantial drifts were found for the Pd(Pt) electrode. EIS spectra of the

High-resolution fast temperature mapping of a gas turbine combustor simulator with femtosecond infrared laser written fiber Bragg gratings

Science.gov (United States)

Walker, Robert B.; Yun, Sangsig; Ding, Huimin; Charbonneau, Michel; Coulas, David; Ramachandran, Nanthan; Mihailov, Stephen J.

2017-02-01

Femtosecond infrared (fs-IR) written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent to the advanced gas turbine engines under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring the sidewall and exhaust temperature gradients of a gas turbine combustor simulator. Results include: contour plots of measured temperature gradients contrasted with thermocouple data, discussion of deployment strategies and comments on reliability.

Localized corrosion of high performance metal alloys in an acid/salt environment

Science.gov (United States)

Macdowell, L. G.; Ontiveros, C.

1991-01-01

Various vacuum jacketed cryogenic supply lines at the Space Shuttle launch site at Kennedy Space Center use convoluted flexible expansion joints. The atmosphere at the launch site has a very high salt content, and during a launch, fuel combustion products include hydrochloric acid. This extremely corrosive environment has caused pitting corrosion failure in the thin walled 304L stainless steel flex hoses. A search was done to find a more corrosion resistant replacement material. The study focussed on 19 metal alloys. Tests which were performed include electrochemical corrosion testing, accelerated corrosion testing in a salt fog chamber, and long term exposure at a beach corrosion testing site. Based on the results of these tests, several nickel based alloys were found to have very high resistance to this corrosive environment. Also, there was excellent agreement between the electrochemical tests and the actual beach exposure tests. This suggests that electrochemical testing may be useful for narrowing the field of potential candidate alloys before subjecting samples to long term beach exposure.

Analysis of the corrosion of carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures

International Nuclear Information System (INIS)

Diercks, D.R.; Kassner, T.F.

1988-04-01

An analysis of literature data on the corrosion of carbon steels in anoxic brines and acid chloride solutions was performed, and the results were used to assess the expected life of high-level nuclear waste package containers in a salt repository environment. The corrosion rate of carbon steels in moderately acidic aqueous chloride environments obeys an Arrhenius dependence on temperature and a (pH 2 ) -1/2 dependence on hydrogen partial pressure. The cathodic reduction of water to produce hydrogen is the rate-controlling step in the corrosion process. An expression for the corrosion rate incorporating these two dependencies was used to estimate the corrosion life of several proposed waste package configurations. 42 refs., 11 figs., 2 tabs

Corrosion testing of NiCrAl(Y) coating alloys in high-temperature and supercritical water

International Nuclear Information System (INIS)

Biljan, S.; Huang, X.; Qian, Y.; Guzonas, D.

2011-01-01

With the development of Generation IV (Gen IV) nuclear power reactors, materials capable of operating in high-temperature and supercritical water environment are essential. This study focuses on the corrosion behavior of five alloys with compositions of Ni20Cr, Ni5Al, Ni50Cr, Ni20Cr5Al and Ni20Cr10AlY above and below the critical point of water. Corrosion tests were conducted at three different pressures, while the temperature was maintained at 460 o C, in order to examine the effects of water density on the corrosion. From the preliminary test results, it was found that the binary alloys Ni20Cr and Ni50Cr showed weight loss above the critical point (23.7 MPa and 460 o C). The higher Cr content alloy Ni50Cr suffered more weight loss than Ni-20Cr under the same conditions. Accelerated weight gain was observed above the critical point for the binary alloy Ni5Al. The combination of Cr, Al and Y in Ni20Cr10AlY provides stable scale formation under all testing conditions employed in this study. (author)

Understanding Fundamental Material Degradation Processes in High Temperature Aggressive Chemomechanical Environments

International Nuclear Information System (INIS)

2014-01-01

The objective of this project is to develop a fundamental understanding of the mechanisms that limit materials durability for very high-temperature applications. Current design limitations are based on material strength and corrosion resistance. This project will characterize the interactions of high-temperature creep, fatigue, and environmental attack in structural metallic alloys of interest for the very high-temperature gas-cooled reactor (VHTR) or Next Generation Nuclear Plant (NGNP) and for the associated thermo-chemical processing systems for hydrogen generation. Each of these degradation processes presents a major materials design challenge on its own, but in combination, they can act synergistically to rapidly degrade materials and limit component lives. This research and development effort will provide experimental results to characterize creep-fatigue-environment interactions and develop predictive models to define operation limits for high-temperature structural material applications. Researchers will study individually and in combination creep-fatigue-environmental attack processes in Alloys 617, 230, and 800H, as well as in an advanced Ni-Cr oxide dispersion strengthened steel (ODS) system. For comparison, the study will also examine basic degradation processes in nichrome (Ni-20Cr), which is a basis for most high-temperature structural materials, as well as many of the superalloys. These materials are selected to represent primary candidate alloys, one advanced developmental alloy that may have superior high-temperature durability, and one model system on which basic performance and modeling efforts can be based. The research program is presented in four parts, which all complement each other. The first three are primarily experimental in nature, and the last will tie the work together in a coordinated modeling effort. The sections are (1) dynamic creep-fatigue-environment process, (2) subcritical crack processes, (3) dynamic corrosion crack

Understanding Fundamental Material Degradation Processes in High Temperature Aggressive Chemomechanical Environments

Energy Technology Data Exchange (ETDEWEB)

Stubbins, James; Gewirth, Andrew; Sehitoglu, Huseyin; Sofronis, Petros; Robertson, Ian

2014-01-16

The objective of this project is to develop a fundamental understanding of the mechanisms that limit materials durability for very high-temperature applications. Current design limitations are based on material strength and corrosion resistance. This project will characterize the interactions of high-temperature creep, fatigue, and environmental attack in structural metallic alloys of interest for the very high-temperature gas-cooled reactor (VHTR) or Next–Generation Nuclear Plant (NGNP) and for the associated thermo-chemical processing systems for hydrogen generation. Each of these degradation processes presents a major materials design challenge on its own, but in combination, they can act synergistically to rapidly degrade materials and limit component lives. This research and development effort will provide experimental results to characterize creep-fatigue-environment interactions and develop predictive models to define operation limits for high-temperature structural material applications. Researchers will study individually and in combination creep-fatigue-environmental attack processes in Alloys 617, 230, and 800H, as well as in an advanced Ni-Cr oxide dispersion strengthened steel (ODS) system. For comparison, the study will also examine basic degradation processes in nichrome (Ni-20Cr), which is a basis for most high-temperature structural materials, as well as many of the superalloys. These materials are selected to represent primary candidate alloys, one advanced developmental alloy that may have superior high-temperature durability, and one model system on which basic performance and modeling efforts can be based. The research program is presented in four parts, which all complement each other. The first three are primarily experimental in nature, and the last will tie the work together in a coordinated modeling effort. The sections are (1) dynamic creep-fatigue-environment process, (2) subcritical crack processes, (3) dynamic corrosion – crack

High-temperature Corrosion Resistance of Composite Coating Prepared by Micro-arc Oxidation Combined with Pack Cementation Aluminizing

Directory of Open Access Journals (Sweden)

HUANG Zu-jiang

2018-01-01

Full Text Available Al2O3 ceramic film was obtained by micro-arc oxidation (MAO process on Al/C103 specimen, which was prepared by pack cementation aluminizing technology on C103 niobium alloy. With the aid of XRD and SEM equipped with EDS, chemical compositions and microstructures of the composite coatings before and after high-temperature corrosion were analyzed. The behavior and mechanism of the composite coatings in high-temperature oxidation and hot corrosion were also investigated. The results indicate that oxidation mass gain at 1000℃ for 10h of the Al/C103 specimen is 6.98mg/cm2, and it is 2.89mg/cm2 of the MAO/Al/C103 specimen. However, the mass gain of MAO/Al/C103 specimen (57.52mg/cm2 is higher than that of Al/C103 specimen (28.08mg/cm2 after oxidation 20h. After hot corrosion in 75%Na2SO4 and 25%NaCl at 900℃ for 50h, the mass gain of Al/C103 and MAO/Al/C103 specimens are 70.54mg/cm2 and 55.71mg/cm2 respectively, Al2O3 and perovskite NaNbO3 phases are formed on the surface; the diffusion of molten salt is suppressed, due to part of NaNbO3 accumulated in the MAO micropores. Therefore, MAO/Al/C103 specimen exhibits better hot corrosion resistance.

High corrosion-resistant fuel spacers

International Nuclear Information System (INIS)

Yoshida, Toshimi; Takase, Iwao; Ikeda, Shinzo; Masaoka, Isao; Nakajima, Junjiro.

1986-01-01

Purpose: To enable manufacturing BWR fuel spacers by prior-art production process, using a zirconium-base alloy having very excellent corrosion resistance. Method: A highly improved nodular-resistant, corrosion-resistant zirconium alloy is devised by adding a slight amount of niobium, titanium and vanadium to zircaloy, of which fuel spacers are produced. That is, there can be obtained an alloy having much more excellent nodular resistance than conventional zircaloy, and free from a large change in plasticity, workability, and weldability, by adding to zirconium about 1.5 % of tin, about 0.15 % of iron, about 0.05 % of chromium, about 0.05 % of nickel, and 0.05 to 0.5 % of at least one or two kinds of niobium, titanium and vanadium. Using this zirconium-base alloy can manufacture fuel spacers by the same manufacturing process, thus improving economy and reliability. (Kamimura, M.)

Ageing temperature effect on inclination of martensite high strength steels EhP699, EhP678, EhP679 to corrosion cracking

International Nuclear Information System (INIS)

Rozenfel'd, I.L.; Spiridonov, V.B.; Konradi, M.V.; Krasnorutskaya, I.B.; Fridman, V.S.

1979-01-01

Stated are the data permitting to judge of the role of ageing temperature in the total number of factors, determining the inclination to corrosion cracking of high strength maraging steels, which contain chromium as a main alloying element. The inclination of the EhP699, EhP678, EhP679 steels to corrosion cracking was estimated on smooth stressed specimens in 3 % NaCl solution with the use of electrochemical polarization. The tensile stress resulted from deflection; anode and cathode current density was 10 mA/cm 2 . It is shown, that resistance to corrosion cracking depends on the ageing temperature: maximum sensitivity to corrosion cracking the steels manifest at the ageing temperatures, providing for maximum strength (470-500 deg). At the ageing temperatures by 20-30 deg over the temperature of this maximum the sensitivity to corrosion cracking disappears, which may result from the loss of coherence of strengthening phase in a matrix, from particle coagulation and stress relaxation in the crack peak

Laboratory Investigation of High Temperature Corrosion in Straw fired Power Plants

DEFF Research Database (Denmark)

Montgomery, Melanie

1998-01-01

Corrosion in straw-fired power plants has been studied in the laboratory for Sandvik 8LR30 and Sanicro 28. The influence of HCl and SO2 was investigated at 600C metal temperature for upto 300 hours.In addition the corrosion behaviour of the same materials was examined in ash taken from a straw-fired...

Experiences with high temperature corrosion at straw‐firing power plants in Denmark

DEFF Research Database (Denmark)

Montgomery, Melanie; Jensen, S. A.; Borg, U.

2011-01-01

to enable better lifetime prediction of vulnerable components in straw‐firing plants since the corrosion rates are so much faster than in coal firing plants. Therefore, there are continued investigations in recently commissioned plants with test tubes installed into actual superheaters. In addition...... temperature is measured on the specific tube loops where there are test tube sections. Thus a corrosion rate can be coupled to a temperature histogram. This is important since although a superheater has a defined steam outlet temperature, there is variation in the tube bundle due to variations of heat flux...

Intergranular stress corrosion cracking of low alloy and carbon steels in high temperature pure water

International Nuclear Information System (INIS)

Tsubota, M.; Sakamoto, H.; Tsuzuki, R.

1993-01-01

Stress corrosion cracking (SCC) behavior of low alloy steels (A508 and SNCM630) and a carbon steel (SGV480) in high temperature water has been examined with relation to the heat treatment condition, including a long time aging, and the mechanical properties. Intergranular stress corrosion cracking (IGSCC) as observed in the highly hardened specimens, and there was observed in the highly hardened specimens, and there was observed in the highly hardened specimens, and there was observed a close relationship between hardness and SCC susceptibility. From the engineering point of view, it was concluded that adequate SR (stress relief) or tempering heat treatment is necessary to avoid the IGSCC of the welded structures made of low alloy and carbon steels. A508 heat treated with specified quench and temper did not show the SCC susceptibility, even after aging 10000 hours at 350, 400 and 450 degrees C. Tensile properties corresponding to the critical hardness for SSC susceptibility coincided with the values at the 'necking point' in the true stress-strain curve. Ductile-brittle transition observed in the fracture toughness test also occurred at around the critical hardness for SCC susceptibility. Therefore, it was conjectured that the limitation of plasticity was an absolute cause for the SCC susceptibility of the steels

Potential for erosion corrosion of SRS high level waste tanks

International Nuclear Information System (INIS)

Zapp, P.E.

1994-01-01

SRS high-level radioactive waste tanks will not experience erosion corrosion to any significant degree during slurry pump operations. Erosion corrosion in carbon steel structures at reported pump discharge velocities is dominated by electrochemical (corrosion) processes. Interruption of those processes, as by the addition of corrosion inhibitors, sharply reduces the rate of metal loss from erosion corrosion. The well-inhibited SRS waste tanks have a near-zero general corrosion rate, and therefore will be essentially immune to erosion corrosion. The experimental data on carbon steel erosion corrosion most relevant to SRS operations was obtained at the Hanford Site on simulated Purex waste. A metal loss rate of 2.4 mils per year was measured at a temperature of 102 C and a slurry velocity comparable to calculated SRS slurry velocities on ground specimens of the same carbon steel used in SRS waste tanks. Based on these data and the much lower expected temperatures, the metal loss rate of SRS tanks under waste removal and processing conditions should be insignificant, i.e. less than 1 mil per year

Alkali activated slag mortars provide high resistance to chloride-induced corrosion of steel

Science.gov (United States)

Criado, Maria; Provis, John L.

2018-06-01

The pore solutions of alkali-activated slag cements and Portland-based cements are very different in terms of their chemical and redox characteristics, particularly due to the high alkalinity and high sulfide content of alkali-activated slag cement. Therefore, differences in corrosion mechanisms of steel elements embedded in these cements could be expected, with important implications for the durability of reinforced concrete elements. This study assesses the corrosion behaviour of steel embedded in alkali-activated blast furnace slag (BFS) mortars exposed to alkaline solution, alkaline chloride-rich solution, water, and standard laboratory conditions, using electrochemical techniques. White Portland cement (WPC) mortars and blended cement mortars (white Portland cement and blast furnace slag) were also tested for comparative purposes. The steel elements embedded in immersed alkali-activated slag mortars presented very negative redox potentials and high apparent corrosion current values; the presence of sulfide reduced the redox potential, and the oxidation of the reduced sulfur-containing species within the cement itself gave an electrochemical signal that classical electrochemical tests for reinforced concrete durability would interpret as being due to steel corrosion processes. However, the actual observed resistance to chloride-induced corrosion was very high, as measured by extraction and characterisation of the steel at the end of a 9-month exposure period, whereas the steel embedded in white Portland cement mortars was significantly damaged under the same conditions.

Elevated temperature erosion studies on some materials for high temperature applications

International Nuclear Information System (INIS)

Zhou Jianren.

1991-01-01

The surface degradation of materials due to high temperature erosion or combined erosion corrosion is a serious problem in many industrial and aeronautical applications. As such, it has become an important design consideration in many situations. The materials investigated in the present studies are stainless steels, Ti-6Al-4V, alumina ceramics, with and without silicate glassy phase, and zirconia. These are some of the potential materials for use in the high temperature erosive-corrosive environments. The erosion or erosion-corrosion experiments were performed in a high temperature sand-blast type of test rig. The variables studied included the temperature, material composition, heat treatment condition, impingement velocity and angle, erodent concentration, etc. The morphological features of the eroded or eroded-corroded surfaces, substrate deformation, and oxide characteristics were studied by optical and scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis. The scratch test, single ball impact, and indentation tests were used to understand the behavior of oxide film in particle impacts. Based on these studies, the understanding of the mechanisms involved in the mechanical or combined mechanical and chemical actions in erosion was developed

High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

Science.gov (United States)

2010-06-02

description of high temperature oxidation processes of composite ceramic materials of ZrB2 - SiC and ZrB2-SiC-Zr(Mo)Si2 systems up to high (~1300 °C...analysis was applied using MІN-7 mineralogical microscope and a set of standard immersion liquids with the known values of refraction coefficients...2.0 V) corresponds to the simultaneous formation of ZrO2 zirconium dioxide of monoclinic modification and Zr(OH)4 zirconium hydroxide which is

Study on Increasing High Temperature pH(t) to Reduce Iron Corrosion Products

International Nuclear Information System (INIS)

Shin, Dong Man; Hur, Nam Yong; Kim, Waang Bae

2011-01-01

The transportation and deposition of iron corrosion products are important elements that affect both the steam generator (SG) integrity and secondary system in pressurized water reactor (PWR) nuclear power plants. Most of iron corrosion products are generated on carbon steel materials due to flow accelerated corrosion (FAC). The several parameters like water chemistry, temperature, hydrodynamic, and steel composition affect FAC. It is well established that the at-temperature pH of the deaerated water system has a first order effect on the FAC rate of carbon steels through nuclear industry researches. In order to reduce transportation and deposition of iron corrosion products, increasing pH(t) tests were applied on secondary system of A, B units. Increasing pH(t) successfully reduced flow accelerated corrosion. The effect of increasing pH(t) to inhibit FAC was identified through the experiment and pH(t) evaluation in this paper

Aspects of alkali chloride chemistry on deposit formation and high temperature corrosion in biomass and waste fired boilers

OpenAIRE

Broström, Markus

2010-01-01

Combustion of biomass and waste has several environmental, economical and political advantages over the use of fossil fuels for the generation of heat and electricity. However, these fuels often have a significantly different composition and the combustion is therefore associated with additional operational problems. A high content of chlorine and alkali metals (potassium and sodium) often causes problems with deposit formation and high temperature corrosion. Some different aspects of these i...

Specific-heat measurement of single metallic, carbon, and ceramic fibers at very high temperature

International Nuclear Information System (INIS)

Pradere, C.; Goyheneche, J.M.; Batsale, J.C.; Dilhaire, S.; Pailler, R.

2005-01-01

The main objective of this work is to present a method for measuring the specific heat of single metallic, carbon, and ceramic fibers at very high temperature. The difficulty of the measurement is due to the microscale of the fiber (≅10 μm) and the important range of temperature (700-2700 K). An experimental device, a modelization of the thermal behavior, and an analytic model have been developed. A discussion on the measurement accuracy yields a global uncertainty lower than 10%. The characterization of a tungsten filament with thermal properties identical to those of the bulk allows the validation of the device and the thermal estimation method. Finally, measurements on carbon and ceramic fibers have been done at very high temperature

Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

International Nuclear Information System (INIS)

Yamanaka, Kazuo

1992-01-01

Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na 2 SO 4 +H 2 SO 4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

Corrosion evaluation technology

International Nuclear Information System (INIS)

Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo.

1997-09-01

A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of ± 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs

Influence of pre-deformation, sensitization and oxidation in high temperature water on corrosion resistance of AISI 304 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Lv, Jinlong, E-mail: ljltsinghua@126.com [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Liang, Tongxiang [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Luo, Hongyun [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing 100191 (China)

2016-12-01

Highlights: • The pre-strain accelerated desensitization and sensitization for austenitic stainless steels. • Low temperature sensitization (carbide precipitation) induced α′-martensite. • The sensitization level could affect directly corrosion resistance of the oxide film. - Abstract: The effects of pre-deformation on sensitization of AISI 304 stainless steel were investigated by the double loop electrochemical potentiokinetic reactivation test. The effects of pre-deformation and sensitization on high temperature oxidized film formed in high temperature water were analyzed by a XRD and SEM. The electrochemical impedance spectroscopy at room temperature was used to study corrosion resistance of oxidized film. The point defect density of oxidized film was calculated by Mott–Schottky plots. The results showed that the value of the degree of sensitization first decreased and then slight increased with the increasing of engineering strain. Moreover, low temperature promoted to form sensitization induced “secondary” α′-martensite. The sample with 20% engineering strain had higher impedance value than other samples. The result was supported by further Mott–Schottky experiments. Considering increased α′-martensite with the increasing of strain, the results of the impedance were more consistent with values of the degree of sensitization.

Corrosion of high purity Fe-Cr-Ni alloys in 13 N boiling nitric acid

International Nuclear Information System (INIS)

Ohta, Joji; Mayuzumi, Masami; Kusanagi, Hideo; Takaku, Hiroshi

1998-01-01

Corrosion in boiling nitric acid was investigated for high purity Fe-18%Cr-12%Ni alloys and type 304L stainless steels (SS). Owing to very low impurity concentration, the solution treated high purity alloys show almost no intergranular corrosion while the type 304L SS show severe intergranular corrosion. Both in the high purity alloys and type 304L SS, aging treatments ranging from 873 K to 1073 K for 1 h enhance intergranular corrosion. During the aging treatments, impurities should be segregated to the grain boundaries. The corrosion behaviors were discussed from a standpoint of impurity segregation to grain boundaries. This study is of importance for purex reprocessing of spent fuels

High Gradient Accelerator Research

International Nuclear Information System (INIS)

Temkin, Richard

2016-01-01

The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

High temperature corrosion studies on friction-welded dissimilar metals

International Nuclear Information System (INIS)

Arivazhagan, N.; Singh, Surendra; Prakash, Satya; Reddy, G.M.

2006-01-01

Understanding the behaviour of weldment at elevated temperatures and especially their corrosion behaviour has become an object of scientific investigation recently. Investigation has been carried out on friction-welded AISI 4140 and AISI 304 under molten salt of Na 2 SO 4 + V 2 O 5 (60%) environment at 500 and 550 deg. C under cyclic condition. The influences of welding parameters on the hot corrosion have been discussed. The resulting oxide scales in the weldment have been characterized systematically using surface analytical techniques. Scale thickness on low alloy steel side was found to be more and was prone to spalling. Weld region has been found to be more prone to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound

High temperature corrosion studies on friction-welded dissimilar metals

Energy Technology Data Exchange (ETDEWEB)

Arivazhagan, N. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India)]. E-mail: arivadmt@iitr.ernet.in; Singh, Surendra [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India); Prakash, Satya [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India); Reddy, G.M. [Defense Metallurgical and Research Laboratory, Hyderabad (India)

2006-07-25

Understanding the behaviour of weldment at elevated temperatures and especially their corrosion behaviour has become an object of scientific investigation recently. Investigation has been carried out on friction-welded AISI 4140 and AISI 304 under molten salt of Na{sub 2}SO{sub 4} + V{sub 2}O{sub 5} (60%) environment at 500 and 550 deg. C under cyclic condition. The influences of welding parameters on the hot corrosion have been discussed. The resulting oxide scales in the weldment have been characterized systematically using surface analytical techniques. Scale thickness on low alloy steel side was found to be more and was prone to spalling. Weld region has been found to be more prone to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound.

High-temperature materials and structural ceramics

International Nuclear Information System (INIS)

1990-01-01

This report gives a survey of research work in the area of high-temperature materials and structural ceramics of the KFA (Juelich Nuclear Research Center). The following topics are treated: (1) For energy facilities: ODS materials for gas turbine blades and heat exchangers; assessment of the remaining life of main steam pipes, material characterization and material stress limits for First-Wall components; metallic and graphitic materials for high-temperature reactors. (2) For process engineering plants: composites for reformer tubes and cracking tubes; ceramic/ceramic joints and metal/ceramic and metal/metal joints; Composites and alloys for rolling bearing and sliding systems up to application temperatures of 1000deg C; high-temperature corrosion of metal and ceramic material; porous ceramic high-temperature filters and moulding coat-mix techniques; electrically conducting ceramic material (superconductors, fuel cells, solid electrolytes); high-temperature light sources (high-temperature chemistry); oil vapor engines with caramic components; ODS materials for components in diesel engines and vehicle gas turbines. (MM) [de

Influence of LMFBR fuel pin temperature profiles on corrosion rate

International Nuclear Information System (INIS)

Shiels, S.A.; Bagnall, C.; Schrock, S.L.; Orbon, S.J.

1976-01-01

The paper describes the sodium corrosion behavior of 20 percent cold worked Type 316 stainless steel fuel pin cladding under a simulated reactor thermal environment. A temperature gradient, typical of a fuel pin, was generated in a 0.9 m long heater section by direct resistance heating. Specimens were located in an isothermal test section immediately downstream of the heater. A comparison of the measured corrosion rates with available data showed an enhancement factor of between 1.5 and 2 which was attributed to the severe axial temperature gradient through the heater. Differences in structure and surface chemistry were also noted

Application of an empirical model in CFD simulations to predict the local high temperature corrosion potential in biomass fired boilers

International Nuclear Information System (INIS)

Gruber, Thomas; Scharler, Robert; Obernberger, Ingwald

2015-01-01

To gain reliable data for the development of an empirical model for the prediction of the local high temperature corrosion potential in biomass fired boilers, online corrosion probe measurements have been carried out. The measurements have been performed in a specially designed fixed bed/drop tube reactor in order to simulate a superheater boiler tube under well-controlled conditions. The investigated boiler steel 13CrMo4-5 is commonly used as steel for superheater tube bundles in biomass fired boilers. Within the test runs the flue gas temperature at the corrosion probe has been varied between 625 °C and 880 °C, while the steel temperature has been varied between 450 °C and 550 °C to simulate typical current and future live steam temperatures of biomass fired steam boilers. To investigate the dependence on the flue gas velocity, variations from 2 m·s −1 to 8 m·s −1 have been considered. The empirical model developed fits the measured data sufficiently well. Therefore, the model has been applied within a Computational Fluid Dynamics (CFD) simulation of flue gas flow and heat transfer to estimate the local corrosion potential of a wood chips fired 38 MW steam boiler. Additionally to the actual state analysis two further simulations have been carried out to investigate the influence of enhanced steam temperatures and a change of the flow direction of the final superheater tube bundle from parallel to counter-flow on the local corrosion potential. - Highlights: • Online corrosion probe measurements in a fixed bed/drop tube reactor. • Development of an empirical corrosion model. • Application of the model in a CFD simulation of flow and heat transfer. • Variation of boundary conditions and their effects on the corrosion potential

High temperature filtration of radioactivable corrosion products in the primary circuit of PWR type reactors

International Nuclear Information System (INIS)

Dolle, L.

1976-01-01

A effective limitation to the deposition of radioactive corrosion products in the core of a reactor at power operation, is to be obtained by filtering the water of the primary circuit at a flow rate upper than 1% of the coolant flow rate. However, in view of accounting for more important release of corrosion products during the reactor start-up and also for some possible variations in the efficiency of the system, it is better that the flow rate to be treated by the cleaning circuit is stated at 5%. Filtration must be effected at the temperature of the primary circuit and preferably on each loop. To this end, the feasibility of electromagnetic filtration or filtration through a deep bed of granulated graphite has been studied. The on-loop tests effected on each filter gave efficiencies and yields respectively upper than 90% and 99% for magnetite and ferrite particles in suspension in water at 250 deg C. Such results confirm the interest lying in high temperature filtration and lead to envisage its application to reactors [fr

Detection and evaluation of corrosion zones at high temperature in steam generators; Deteccion y evaluacion de zonas de corrosion en alta temperatura de generadoras de vapor

Energy Technology Data Exchange (ETDEWEB)

Martinez Villafane, Alberto; Chacon Nava, Jose G; Huerta Espino, Mario; Mojica Calderon, Cecilio; Castillo Viveros, Antonio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1991-12-31

This paper presents the methodology for the detection and evaluation of high corrosion zones at high temperature. The results found up to now, show a critical zone in the Babcock Hitachi design, specifically in the high temperature reheater in the zone nearby the outlet header. In the normalized design CE (Mitsubishi) of 300 MW and CE (Canada) of 300 MW, the results found in recent years show small thickness reduction, therefore a good operation of these steam generators is recognized. [Espanol] En este trabajo se presenta la metodologia para la deteccion y evaluacion de zonas de corrosion en alta temperatura. Los resultados encontrados hasta el momento muestran una zona critica en el diseno Babcock Hitachi, especificamente en el recalentador de alta temperatura en la zona cercana al cabezal de salida. En el diseno normalizado CE (Mitsubishi) de 300 MW y CE (Canada) de 300 MW, los resultados encontrados en anos recientes muestran poca disminucion de espesor, por lo que se considera una buena operacion de estos generadores de vapor.

Detection and evaluation of corrosion zones at high temperature in steam generators; Deteccion y evaluacion de zonas de corrosion en alta temperatura de generadoras de vapor

Energy Technology Data Exchange (ETDEWEB)

Martinez Villafane, Alberto; Chacon Nava, Jose G.; Huerta Espino, Mario; Mojica Calderon, Cecilio; Castillo Viveros, Antonio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1990-12-31

This paper presents the methodology for the detection and evaluation of high corrosion zones at high temperature. The results found up to now, show a critical zone in the Babcock Hitachi design, specifically in the high temperature reheater in the zone nearby the outlet header. In the normalized design CE (Mitsubishi) of 300 MW and CE (Canada) of 300 MW, the results found in recent years show small thickness reduction, therefore a good operation of these steam generators is recognized. [Espanol] En este trabajo se presenta la metodologia para la deteccion y evaluacion de zonas de corrosion en alta temperatura. Los resultados encontrados hasta el momento muestran una zona critica en el diseno Babcock Hitachi, especificamente en el recalentador de alta temperatura en la zona cercana al cabezal de salida. En el diseno normalizado CE (Mitsubishi) de 300 MW y CE (Canada) de 300 MW, los resultados encontrados en anos recientes muestran poca disminucion de espesor, por lo que se considera una buena operacion de estos generadores de vapor.

Grain boundary segregation and intergranular stress corrosion cracking susceptibility of austenitic stainless steels in high temperature water

International Nuclear Information System (INIS)

Shoji, T.; Yamaki, K.; Ballinger, R.G.; Hwang, I.S.

1992-01-01

The effects of grain boundary segregation on intergranular stress corrosion cracking of austenitic stainless steels in high temperature water have been examined as a function of heat treatment. The materials investigated were: (1) two commercial purity Type 304; (2) low sulfur Type 304; (3) nuclear grade Type 304; (4) ultra high purity Type 304L; and (5) Type 316L and Type 347L. Specimens were solution treated at 1050 degrees C for 0.5 hour and given a sensitization heat treatment at 650 degrees C for 50 hours. Some of the specimens were then subjected to an aging heat treatment at 850 degrees C for from one to ten hours to cause Cr recovery at the grain boundaries. The effects of heat treatments on degree of sensitization and grain boundary segregation were evaluated by Electrochemical Potentiokinetic Reactivation (EPR) and Coriou tests, respectively. The susceptibility to stress corrosion (SCC) was evaluated using slow strain rate tests technique (SSRT) in high temperature water. SSRT tests were performed in an aerated pure water (8 ppm dissolved oxygen) at 288 degrees C at a strain rate of 1.33 x 10 -6 /sec. Susceptibility to intergranular stress corrosion cracking was compared with degree of sensitization and grain boundary segregation. The results of the investigation indicate that EPR is not always an accurate indicator of SCC susceptibility. The Coriou test provides a more reliable measure of SCC susceptibility especially for 304L, 304NG, 316L, and 347L stainless steels. The results also indicate that grain boundary segregation as well as degree of sensitization must be considered in the determination of SCC susceptibility

Corrosion-Resistant High-Entropy Alloys: A Review

Directory of Open Access Journals (Sweden)

Yunzhu Shi

2017-02-01

Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Advanced multi-physics simulation capability for very high temperature reactors

International Nuclear Information System (INIS)

Lee, Hyun Chul; Tak, Nam Il; Jo Chang Keun; Noh, Jae Man; Cho, Bong Hyun; Cho, Jin Woung; Hong, Ser Gi

2012-01-01

The purpose of this research is to develop methodologies and computer code for high-fidelity multi-physics analysis of very high temperature gas-cooled reactors(VHTRs). The research project was performed through Korea-US I-NERI program. The main research topic was development of methodologies for high-fidelity 3-D whole core transport calculation, development of DeCART code for VHTR reactor physics analysis, generation of VHTR specific 190-group cross-section library for DeCART code, development of DeCART/CORONA coupled code system for neutronics/thermo-fluid multi-physics analysis, and benchmark analysis against various benchmark problems derived from PMR200 reactor. The methodologies and the code systems will be utilized a key technologies in the Nuclear Hydrogen Development and Demonstration program. Export of code system is expected in the near future and the code systems developed in this project are expected to contribute to development and export of nuclear hydrogen production system

Novel high-resolution temperature probe for radiofrequency dosimetry

Energy Technology Data Exchange (ETDEWEB)

Schuderer, Juergen [Foundation for Research on Information Technologies in Society (IT' IS), Integrated Systems Laboratory IIS, Swiss Federal Institute of Technology (ETH), CH-8092 Zurich (Switzerland); Schmid, Thomas [Schmid and Partner Engineering AG, 8004 Zurich (Switzerland); Urban, Gerald [IMTEK, Albert-Ludwigs University Freiburg, 79110 Freiburg (Germany); Samaras, Theodoros [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Kuster, Niels [Foundation for Research on Information Technologies in Society (IT' IS), Integrated Systems Laboratory IIS, Swiss Federal Institute of Technology (ETH), CH-8092 Zurich (Switzerland)

2004-03-21

A novel integrated thermistor probe for temperature evaluations in radiofrequency-heated environments was realized. The probe's sensitive area is based on a highly resistive 50 {mu}m x 100 {mu}m layer of amorphous germanium processed on a glass tip. The small dimensions allow measurements with a distance as close as 150 {mu}m from solid boundaries. Due to its high temperature resolution of 4 mK and its short response time of the order of 10 ms, the sensor is very well suited for dosimetric measurements in strong absorption gradients. The influence of radiofrequency (RF) electric fields on the signal is minimized due to the high resistance of the sensor and the leads. The probe was successfully used to determine the highly nonuniform absorption distribution resulting from the RF exposure of cell cultures placed in Petri dishes. (note)

Novel high-resolution temperature probe for radiofrequency dosimetry

International Nuclear Information System (INIS)

Schuderer, Juergen; Schmid, Thomas; Urban, Gerald; Samaras, Theodoros; Kuster, Niels

2004-01-01

A novel integrated thermistor probe for temperature evaluations in radiofrequency-heated environments was realized. The probe's sensitive area is based on a highly resistive 50 μm x 100 μm layer of amorphous germanium processed on a glass tip. The small dimensions allow measurements with a distance as close as 150 μm from solid boundaries. Due to its high temperature resolution of 4 mK and its short response time of the order of 10 ms, the sensor is very well suited for dosimetric measurements in strong absorption gradients. The influence of radiofrequency (RF) electric fields on the signal is minimized due to the high resistance of the sensor and the leads. The probe was successfully used to determine the highly nonuniform absorption distribution resulting from the RF exposure of cell cultures placed in Petri dishes. (note)

High temperature mechanical properties of iron aluminides

International Nuclear Information System (INIS)

Morris, D. G.; Munoz-Morris, M. A.

2001-01-01

Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the materials, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered. (Author)

Modelling of zircaloy-4 corrosion in nitrogen and oxygen mixtures at high temperature

International Nuclear Information System (INIS)

Lasserre, M.; Peres, V.; Pijolat, M.; Coindreau, O.; Duriez, C.; Mardon, J.P.

2015-01-01

Previous studies of zircaloy-4 corrosion in air have shown accelerated corrosion in the 600-1000 Celsius degrees temperature range with Zr nitrides precipitating near the metal/oxide surface. The aim of this series of slides is to assess the influence of N 2 and O 2 partial pressures on the kinetic rate of growth of a new phase and to propose a kinetic modelling of zircaloy-4 corrosion

The effect of Co-firing with Straw and Coal on High Temperature Corrosion

DEFF Research Database (Denmark)

Montgomery, Melanie; Frandsen, Flemming; Larsen, OH

2001-01-01

As a part of ELSAMS development programme into alternative energy sources, various concepts of straw-firing have been investigated. This paper concerns co-firing of straw with coal to reduce the corrosion rate observed in straw-fired power plants. Co-firing with coal reduces the amount of potassium......: a) the exposure of metal rings on water/air cooled probes, and b) the exposure of a range of materials built into the existing superheaters. A range of austenitic and ferritic steels was exposed in the steam temperature region of 520-580°C. The flue gas temperature ranged from 925-1100°C....... The corrosion products for the various steel types were investigated using light optical and scanning electron microscopy. Corrosion mechanisms for the austenitic and ferritic steels are presented. These are discussed in relation to temperature and deposit composition. Co-firing with coal has removed potassium...

High temperature radioisotope capsule

International Nuclear Information System (INIS)

Bradshaw, G.B.

1976-01-01

A high temperature radioisotope capsule made up of three concentric cylinders, with the isotope fuel located within the innermost cylinder is described. The innermost cylinder has hemispherical ends and is constructed of a tantalum alloy. The intermediate cylinder is made of a molybdenum alloy and is capable of withstanding the pressure generated by the alpha particle decay of the fuel. The outer cylinder is made of a platinum alloy of high resistance to corrosion. A gas separates the innermost cylinder from the intermediate cylinder and the intermediate cylinder from the outer cylinder

Improvement of corrosion resistance of vanadium alloys in high-temperature pressurized water

International Nuclear Information System (INIS)

Fujiwara, Mitsuhiro; Sakamoto, Toshiya; Satou, Manabu; Hasegawa, Akira; Abe, Katsunori; Kaiuchi, Kazuo; Furuya, Takemi

2005-01-01

Corrosion tests in pressurized and vaporized water were conducted for V-based high Cr and Ti alloys and V-4Cr-4Ti type alloys containing minor elements such as Si, Al and Y. Weight losses were observed for every alloy after corrosion tests in pressurized water. It was apparent that addition of Cr effectively reduced the weight change in pressurized water. The weight loss of V-4Cr-4Ti type alloys in corrosion tests in vaporized water was also reduced as Cr content increased. The V-20Cr-4Ti alloy had a slight weight gain, almost same as that of SUS316, which had the best corrosion properties in the tested alloys. The elongation of alloys with in excess of 10% Cr was reduced as Cr content increased. The elongations of the V-12Cr-4Ti and the V-15Cr-4Ti alloys were significantly reduced by corrosion and cleavage fracture was observed reflecting hydrogen embrittlement. The reduced elongations of the alloys of the alloys were recovered to the same level of as annealed conditions after hydrogen degassing. After corrosion, the V-15Cr-4Ti-0.5Y alloy still kept enough elongation, suggesting that the addition of Y is effective to reduce the hydrogen embrittlement. (author)

High temperature corrosion in chloridizing atmospheres: development of material quasi-stability diagrams and coatings

Energy Technology Data Exchange (ETDEWEB)

Doublet, S.; Schuetze, M. [Karl-Winnacker-Institut der DECHEMA e.V., Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany)

2004-07-01

Chlorine gas is widely encountered in chemical industries, e. g. in waste incinerators and plastic/polymer decomposition mills. The presence of chlorine may significantly reduce the life-time of the components. Although metallic materials have been widely used under such conditions there is still a need for data on the role of the different alloying elements in commercial alloys. The purpose of this work is to produce a clear picture of which alloying elements play a detrimental role and which elements are beneficial. These results can be used as a tool for general assessment of metallic alloys with regard to their performance in chloridizing high temperature environments. A previous study has already been performed in oxidizing-chloridizing atmospheres and led to the elaboration of material quasi-stability diagrams. As a follow-up the present work has been performed in reducing-chloridizing atmospheres in order to validate these diagrams at low partial pressures of oxygen. The behaviour of 9 commercial materials where the content of the major alloying elements was varied in a systematic manner was investigated in reducing-chloridizing atmospheres (in Ar containing up to 2 vol.% Cl{sub 2} and down to 1 ppm O{sub 2}) at 800 deg. C. As the thermodynamical approach to corrosion in such atmospheres could not explain all the phenomena which occur, kinetics calculations i.e. diffusion calculations were carried out. Pack cementation and High Velocity Oxy-Fuel (HVOF) coatings were also developed from the best alloying elements previously found by the calculations and the corrosion experiments. Corrosion tests on the coated materials were then performed in the same conditions as the commercial alloys. (authors)

Effects of solution temperature on localized corrosion of high nickel content stainless steels and nickel in chromated LiBr solution

International Nuclear Information System (INIS)

Munoz, A. Igual; Anton, J. Garcia; Guinon, J.L.; Perez Herranz, V.

2006-01-01

The potentiodynamic technique has been used to study the general and localized corrosion resistance of high-alloyed stainless steels (UNS N02031 and UNS R20033) and nickel (UNS N02205) at different temperatures (from 25 deg. C to 80 deg. C) in a heavy brine Lithium Bromide solution. The engineering question of concern is the compatibility of the LiBr fluid with the structural materials of refrigeration systems which use absorption technology. The results of potentiodynamic polarization studies indicate excellent corrosion resistance for stainless steels in LiBr solution at room temperature and no big differences at temperatures above 50 deg. C. In the temperature range of 25-80 deg. C, a linear relationship exists between logarithmic of corrosion rate and reciprocal of absolute temperature (Arrhenius plot). The linear plots showed that the mechanism of the corresponding passivation process is the same for the three investigated alloys, essentially due to the presence of nickel. Tests indicated that stainless steels UNS N02031 and UNS R20033 were the most suitable for use to be used in the construction of absorption units for refrigeration purposes

Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same

Science.gov (United States)

Angell, C Austen [Mesa, AZ; Xu, Wu [Broadview Heights, OH; Belieres, Jean-Philippe [Chandler, AZ; Yoshizawa, Masahiro [Tokyo, JP

2011-01-11

Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the high performance of the non-corrosive proton-transfer ionic liquids as high temperature fuel cell electrolytes. Performance of simple H.sub.2(g) electrolyte/O.sub.2(g) fuel cells with the new electrolytes is described. Superior performance both at ambient temperature and temperatures up to and above 200.degree. C. are achieved. Both neutral proton transfer salts and the acid salts with HSO.sup.-.sub.4 anions, give good results, the bisulphate case being particularly good at low temperatures and very high temperatures. The performance of all electrolytes is improved by the addition of a small amount of involatile base of pK.sub.a value intermediate between those of the acid and base that make the bulk electrolyte. The preferred case is the imidazole-doped ethylammonium hydrogensulfate which yields behavior superior in all respects to that of the industry standard phosphoric acid electrolyte.

Materials for advanced high temperature reactors

International Nuclear Information System (INIS)

Graham, L.W.

1977-01-01

Materials are studied in advanced applications of high temperature reactors: helium gas turbine and process heat. Long term creep behavior and corrosion tests are conducted in simulated HTR helium up to 1000 deg C with impurities additions in the furnace atmosphere. Corrosion studies on AISI 321 steels at 800-1000 deg C have shown that the O 2 partial pressure is as low as 10 -24+-3 atm, Ni and Fe cannot be oxidised above about 500 and 600 deg C, Cr cease to oxidise at 800 to 900 deg C and Ti at 900 to 1000 deg C depending on alloy composition γ' strengthened superalloys must depend on a protective corrosion mechanism assisted by the presence of Ti and possibly Cr. Carburisation has been identified metallographically in several high temperature materials: Hastelloy X and M21Z. Alloy TZM appears to be inert in HTR Helium at 900 and 1000 deg C. In alloy 800 and Inconel 625 surface cracks initiation is suppressed but crack propagation is accelerated but this was not apparent in AISI steels, Hastelloy X or fine grain Inconel at 750 deg C

Investigation on multilayer failure mechanism of RPV with a high temperature gradient from core meltdown scenario

Energy Technology Data Exchange (ETDEWEB)

Jianfeng, Mao, E-mail: jianfeng-mao@163.com [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310032 (China); Engineering Research Center of Process Equipment and Remanufacturing, Ministry of Education (China); Xiangqing, Li [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310032 (China); Shiyi, Bao, E-mail: bsy@zjut.edu.cn [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310032 (China); Engineering Research Center of Process Equipment and Remanufacturing, Ministry of Education (China); Lijia, Luo [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310032 (China); Zengliang, Gao [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310032 (China); Engineering Research Center of Process Equipment and Remanufacturing, Ministry of Education (China)

2016-12-15

Highlights: • The multilayer failure mechanism is investigated for RPV under CHF. • Failure time and location of RPV are predicted under various SA scenarios. • The structural behaviors are analyzed in depth for creep and plasticity. • The effect of internal pressure and temperature gradient is considered. • The structural integrity of RPV is secured within the required 72 creep hours. - Abstract: The Fukushima accident shows that in-vessel retention (IVR) of molten core debris has not been appropriately assessed, and a certain pressure (up to 8.0 MPa) still exists inside the reactor pressure vessel (RPV). In the traditional concept of IVR, the pressure is supposed to successfully be released, and the temperature distributed among the wall thickness is assumed to be uniform. However, this concept is seriously challenged by reality of Fukushima accident with regard to the existence of both internal pressure and high temperature gradient. Therefore, in order to make the IVR mitigation strategy succeed, the numerical investigation of the lower head behavior and its failure has been performed for several internal pressures under high temperature gradient. According to some requirements in severe accident (SA) management of RPV, it should be ensured that the IVR mitigation takes effect in preventing the failure of the structure within a period of 72 h. Subsequently, the failure time and location have to be predicted under the critical heat flux (CHF) loading condition for lower head, since the CHF is limit thermal boundary before the melt-through of RPV. In illustrating the so called ‘multilayer failure mechanism’, the structural behaviors of RPV are analyzed in terms of the stress, creep strain, deformation, damage on selected paths.

Investigation on multilayer failure mechanism of RPV with a high temperature gradient from core meltdown scenario

International Nuclear Information System (INIS)

Jianfeng, Mao; Xiangqing, Li; Shiyi, Bao; Lijia, Luo; Zengliang, Gao

2016-01-01

Highlights: • The multilayer failure mechanism is investigated for RPV under CHF. • Failure time and location of RPV are predicted under various SA scenarios. • The structural behaviors are analyzed in depth for creep and plasticity. • The effect of internal pressure and temperature gradient is considered. • The structural integrity of RPV is secured within the required 72 creep hours. - Abstract: The Fukushima accident shows that in-vessel retention (IVR) of molten core debris has not been appropriately assessed, and a certain pressure (up to 8.0 MPa) still exists inside the reactor pressure vessel (RPV). In the traditional concept of IVR, the pressure is supposed to successfully be released, and the temperature distributed among the wall thickness is assumed to be uniform. However, this concept is seriously challenged by reality of Fukushima accident with regard to the existence of both internal pressure and high temperature gradient. Therefore, in order to make the IVR mitigation strategy succeed, the numerical investigation of the lower head behavior and its failure has been performed for several internal pressures under high temperature gradient. According to some requirements in severe accident (SA) management of RPV, it should be ensured that the IVR mitigation takes effect in preventing the failure of the structure within a period of 72 h. Subsequently, the failure time and location have to be predicted under the critical heat flux (CHF) loading condition for lower head, since the CHF is limit thermal boundary before the melt-through of RPV. In illustrating the so called ‘multilayer failure mechanism’, the structural behaviors of RPV are analyzed in terms of the stress, creep strain, deformation, damage on selected paths.

HIGH-GRADIENT, HIGH-TRANSFORMER-RATIO, DIELECTRIC WAKE FIELD ACCELERATOR

Energy Technology Data Exchange (ETDEWEB)

Hirshfield, Jay L

2012-04-12

The Phase I work reported here responds to DoE'ss stated need "...to develop improved accelerator designs that can provide very high gradient (>200 MV/m for electrons...) acceleration of intense bunches of particles." Omega-P's approach to this goal is through use of a ramped train of annular electron bunches to drive a coaxial dielectric wakefield accelerator (CDWA) structure. This approach is a direct extension of the CDWA concept from acceleration in wake fields caused by a single drive bunch, to the more efficient acceleration that we predict can be realized from a tailored (or ramped) train of several drive bunches. This is possible because of a much higher transformer ratio for the latter. The CDWA structure itself has a number of unique features, including: a high accelerating gradient G, potentially with G > 1 GeV/m; continuous energy coupling from drive to test bunches without transfer structures; inherent transverse focusing forces for particles in the accelerated bunch; highly stable motion of high charge annular drive bunches; acceptable alignment tolerances for a multi-section system. What is new in the present approach is that the coaxial dielectric structure is now to be energized by-not one-but by a short train of ramped annular-shaped drive bunches moving in the outer coaxial channel of the structure. We have shown that this allows acceleration of an electron bunch traveling along the axis in the inner channel with a markedly higher transformer ratio T than for a single drive bunch. As described in this report, the structure will be a GHz-scale prototype with cm-scale transverse dimensions that is expected to confirm principles that can be applied to the design of a future THz-scale high gradient (> 500 MV/m) accelerator with mm-scale transverse dimensions. We show here a new means to significantly increase the transformer ratio T of the device, and thereby to significantly improve its suitability as a flexible and effective component in

Very high geothermal gradient in near surface of the Whataroa Valley adjacent to the Alpine Fault: topographic driving forces and permeable mountains

Science.gov (United States)

Upton, P.; Sutherland, R.; Townend, J.; Coussens, J.; Capova, L.

2015-12-01

The first phase of the Deep Fault Drilling Project (DFDP-1B) yielded a geothermal gradient of 62.6 ± 2.1 °C/km from a depth of 126 m where it intersected the Alpine Fault principal slip surface beneath Gaunt Creek (Sutherland et al. 2012). Ambient fluid pressures in DFDP-2B at Whataroa River were 8-10% above hydrostatic and a geothermal gradient of >130°C/km was determined, the geothermal gradient being considerably higher than we had predicted previously. 3D coupled thermal/fluid flow models have been generated of the Whataroa Valley and the DFDP-2 drill site. Modelling confirms that the following features, present in the Whataroa Valley, are a requirement for a geothermal gradient of >130°C/km at a depth of 1km beneath the valley; high topography, permeability on the order of 10-15 m2 in both the mountains and beneath the valleys to depths of > 1km below the valley floor, and abundant fluid. The high permeability and large topographic driving force leads to abundant meteoric water flowing downward through the mountains, hitting the permeability barrier of the Alpine Fault and being pushed upward into the valleys. The high geothermal gradient of the DFDP-2B borehole implies that the valleys also have a very high permeability which is likely a result of rock damage along the Alpine Fault.

Influence of Zn injection on corrosion behavior and oxide film characteristics of 304 stainless steel in borated and lithiated high temperature water

International Nuclear Information System (INIS)

Wu, Xinqiang; Liu, Xiahe; Han, En-Hou; Ke, Wei

2012-09-01

Water chemistry of the reactor coolant system plays a major role in maintaining safety and reliability of light water reactor nuclear power plants (NPPs). Zn water chemistry into pressurized water reactors (PWRs) in order to reduce the radiation buildup in primary coolant system has been widely applied, and the reduction effect has been experimentally confirmed. Zn injection can also lessen the corrosion phenomena in high temperature pressurized water by changing oxide films formed on components materials. Both the radiation buildup and material corrosion resistance in PWR coolant system are closely dependent on the oxide films formed. However, the influence of Zn injection on the chemical composition and structure of the oxide films on their protective properties is still a matter of considerable debate. The influence of Zn injection on corrosion inhibition and environmental degradation has not been fully clarified yet. Therefore, the understanding of corrosion behaviour, oxide film characteristics and their protective property is of significance to clarify the environmentally assisted material failure problems in NPPs. In the present work, oxide films formed on nuclear-grade 304 SS exposed to borated and lithiated high temperature water environments at 300 deg. C up to 4000 h with or without 10 ppb Zn injection were investigated ex-situ. Without Zn injection, the oxide films mainly consisted of Fe 3 O 4 and FeCr 2 O 4 . With Zn injection, ZnFe 2 O 4 and ZnCr 2 O 4 were detected in the oxide films at the initial stage of immersion and ZnCr 2 O 4 became dominant after long-term immersion. It was believed that the above Zn-Fe and Zn-Cr spinel oxides were formed by substitution reactions between Zn 2+ and Fe 2+ . At the initial stage of immersion, water chemistry significantly affected the formation of the oxide films. Once a stable oxide film formed, it is rather difficult to change its structure through changing water chemistry. The potential-pH diagrams for Zn

Investigations of Very High Enthalpy Geothermal Resources in Iceland.

Science.gov (United States)

Elders, W. A.; Fridleifsson, G. O.

2012-12-01

The Iceland Deep Drilling Project (IDDP) is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs. Earlier modeling indicates that the power output of a geothermal well producing from a supercritical reservoir could potentially be an order of magnitude greater than that from a conventional hot geothermal reservoir, at the same volumetric flow rate. However, even in areas with an unusually high geothermal gradient, for normal hydrostatic pressure gradients reaching supercritical temperatures and pressures will require drilling to depths >4 km. In 2009 the IDDP attempted to drill the first deep supercritical well, IDDP-01, in the caldera of the Krafla volcano, in NE Iceland. However drilling had to be terminated at only 2.1 km depth when ~900°C rhyolite magma flowed into the well. Our studies indicate that this magma formed by partial melting of hydrothermally altered basalts within the Krafla caldera. Although this well was too shallow to reach supercritical pressures, it is highly productive, and is estimated to be capable of generating up to 36 MWe from the high-pressure, superheated steam produced from the upper contact zone of the intrusion. With a well-head temperature of ~440°C, it is at present apparently the hottest producing geothermal well in the world. A pilot plant is investigating the optimal utilization of this magmatically heated resource. A special issue of the journal Geothermics with 16 papers reporting on the IDDP-01 is in preparation. However, in order to continue the search for supercritical geothermal resources, planning is underway to drill a 4.5 km deep well at Reykjanes in SW Iceland in 2013-14. Although drilling deeper towards the heat source of this already developed high-temperature geothermal field will be more expensive, if a supercritical resource is found, this cost increase should be offset by the considerable increase in the power output and lifetime of the Reykjanes geothermal

Diffusion barrier coatings for high temperature corrosion resistance of advanced carbon/carbon composites

International Nuclear Information System (INIS)

Singh Raman, K.S.

2000-01-01

Carbon possesses an excellent combination of mechanical and thermal properties, viz., excellent creep resistance at temperatures up to 2400 deg C in non-oxidizing environment and a low thermal expansion coefficient. These properties make carbon a potential material for very high temperature applications. However, the use of carbon materials at high temperatures is considerably restricted due to their extremely poor oxidation resistance at temperatures above 400 deg C. The obvious choice for improving high temperature oxidation resistance of such materials is a suitable diffusion barrier coating. This paper presents an overview of recent developments in advanced diffusion- and thermal-barrier coatings for ceramic composites, with particular reference to C/C composites. The paper discusses the development of multiphase and multi-component ceramic coatings, and recent investigations on the oxidation resistance of the coated C/C composites. The paper also discusses the cases of innovative engineering solutions for traditional problems with the ceramic coatings, and the scope of intelligent processing in developing coatings for the C/C composites. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

Development of Self-Powered Wireless-Ready High Temperature Electrochemical Sensors for In-Situ Corrosion Monitoring for Boiler Tubes in Next Generation Coal-based Power Systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)

2015-06-30

The key innovation of this project is the synergy of the high temperature sensor technology based on the science of electrochemical measurement and state-of-the-art wireless communication technology. A novel self-powered wireless high temperature electrochemical sensor system has been developed for coal-fired boilers used for power generation. An initial prototype of the in-situ sensor demonstrated the capability of the wireless communication system in the laboratory and in a pilot plant (Industrial USC Boiler Setting) environment to acquire electrochemical potential and current signals during the corrosion process. Uniform and localized under-coal ash deposit corrosion behavior of Inconel 740 superalloy has been studied at different simulated coal ash hot corrosion environments using the developed sensor. Two typical potential noise patterns were found to correlate with the oxidation and sulfidation stages in the hot coal ash corrosion process. Two characteristic current noise patterns indicate the extent of the corrosion. There was a good correlation between the responses of electrochemical test data and the results from corroded surface analysis. Wireless electrochemical potential and current noise signals from a simulated coal ash hot corrosion process were concurrently transmitted and recorded. The results from the performance evaluation of the sensor confirm a high accuracy in the thermodynamic and kinetic response represented by the electrochemical noise and impedance test data.

Application of zirconia membranes as high-temperature PH sensors

International Nuclear Information System (INIS)

Neidrach, L.W.

1983-01-01

The zirconia pH sensor behaves much like the classical glass electrode, but it extends the range of measurement to much higher temperatures - about 300 0 vs 120 0 C. It also has virtues over the glass electrode at lower temperatures because of the absence of an ''alkaline error.'' Like the glass electrode, it is insensitive to changes in the redox potential of the environment and, in turn, it exerts no influence on the environment. Such sensors have been finding application in the direct measurement of the pH of geothermal brines, of water in nuclear reactors, and in high-temperature corrosion studies. The sensors can also be used as ''pseudoreference'' electrodes for the measurement of redox and corrosion potentials in high-temperature media

Development and high temperature sealing performance study of double sealing flange

International Nuclear Information System (INIS)

Zhang Qinhua; Fu Yuan; Xie Leidong; Li Zhong; Tang Zhongfeng

2013-01-01

Background: Flange is an important component used in the connection between pipes or between pipe and equipment. It is widely used in mechanical industry, petrochemical industry and nuclear industry. Ordinary flange could be oxidized oi corroded under high temperature and strong corrosion condition, which leads to flange's failure. Purpose: The aim is to design and validate the double sealing flange which could be used in high temperature and strong corrosion condition stably and supplied as a reliable detachable connection for petrochemical industry and nuclear industry under high temperature and strong corrosion environment. Methods: New flange is designed using flexible graphite spiral wound gaskets and C style metal ring double sealing structure. The unique protection gas design ensures the graphite spiral wound gasket used in high temperature reliably. Test bed is built to verify the stability of the flange. Results: Pressure reducing of graphite spiral wound gasket is only 0.01 MPa at 750℃, 0.7 MPa for 43 h, there is not obvious oxidation phenomenon at the same time. The leakage rate of metal C sealing ring is 11.51×10 -4 atm cc/s, and the metal C ring sealing's performance meets the engineering requirements. Conclusion: The leakage rate of double sealing flange is almost zero under 0.7 MPa at 750℃, which meets the engineering requirements. It avoids oxidizing at high temperature and corroding under strong corrosion condition. (authors)

Microstructural Changes during High Temperature Service of a Cobalt-Based Superalloy First Stage Nozzle

Directory of Open Access Journals (Sweden)

A. Luna Ramírez

2016-01-01

Full Text Available Superalloys are a group of alloys based on nickel, iron, or cobalt, which are used to operate at high temperatures (T > 540°C and in situations involving very high stresses like in gas turbines, particularly in the manufacture of blades, nozzles, combustors, and discs. Besides keeping its high resistance to temperatures which may approach 85% of their melting temperature, these materials have excellent corrosion resistance and oxidation. However, after long service, these components undergo mechanical and microstructural degradation; the latter is considered a major cause for replacement of the main components of gas turbines. After certain operating time, these components are very expensive to replace, so the microstructural analysis is an important tool to determine the mode of microstructure degradation, residual lifetime estimation, and operating temperature and most important to determine the method of rehabilitation for extending its life. Microstructural analysis can avoid catastrophic failures and optimize the operating mode of the turbine. A case study is presented in this paper.

Assessment of very high-temperature reactors in process application. Appendix I. Evaluation of the reactor system

International Nuclear Information System (INIS)

Jones, J.E. Jr.; Spiewak, I.

1976-12-01

In April 1974, the U.S. Atomic Energy Commission [now the Energy Research and Development Administration (ERDA)] authorized General Atomic Company, General Electric Company, and Westinghouse Electric Corp., Astronuclear Laboratory, to assess the available technology for producing heat using very high-temperature nuclear reactors. An evaulation of these studies and of the technical and economic potential of very high-temperature reactors (VHTR) is presented. The VHTR is a helium-cooled graphite-moderated reactor. The concepts and technology are evaluated for producing process stream temperatures of 649, 760, 871, 982, and 1093 0 C (1200, 1400, 1600, 1800, and 2000 0 F). There are a number of large industrial process heat applications that could utilize the VHTR

High-temperature geothermal cableheads

Science.gov (United States)

Coquat, J. A.; Eifert, R. W.

1981-11-01

Two high temperature, corrosion resistant logging cable heads which use metal seals and a stable fluid to achieve proper electrical terminations and cable sonde interfacings are described. A tensile bar provides a calibrated yield point, and a cone assembly anchors the cable armor to the head. Electrical problems of the sort generally ascribable to the cable sonde interface were absent during demonstration hostile environment loggings in which these cable heads were used.

High-temperature corrosion of metals in the salt and metallic melts containing rare earths

Science.gov (United States)

Karpov, V. V.; Abramov, A. V.; Zhilyakov, A. Yu.; Belikov, S. V.; Volkovich, V. A.; Polovov, I. B.; Rebrin, O. I.

2016-09-01

A complex of independent methods was employed to study the corrosion resistance of molybdenum, zirconium, tantalum and tungsten in chloride, chloride-fluoride and fluoride-oxide melts based on LiCl, CaCl2, NaCl- KCl, LiF, and containing rare earths. Tests were conducted for 30 h at 750-1050 °C. The metals showed excellent corrosion resistance in fused chlorides (the corrosion rates were below 0.0005 g/(m2 h). Despite the presence of chemically active fluoride ions in the chloride-fluoride melts, the metals studied also showed very low corrosion rates, except molybdenum, for which the rate of corrosion was 0,8 g/(m2 h). The corrosion resistance of tantalum was considerably reduced in the fluoride-oxide melts; the corrosion rate was over 1 g/(m2 h) corresponding to the 8-th grade of stability and placing tantalum to the group of "low stability" materials.

Task 20 - Prevention of Chloride Corrosion in High-Temperature Waste Treatment Systems (Corrosives Removals from Vitrification Slurries)

International Nuclear Information System (INIS)

Timpe, R.C.; Aulich, T.R.

1998-01-01

GTS Duratek is working with BNFL Incorporated on a US Department of Energy (DOE) contract to develop a facility to treat and immobilize radioactive waste at the Hanford site in southeast Washington. Development of the 10-ton/day Hanford facility will be based on findings from work at Duratek's 3.3-ton/day pilot plant in Columbia, Maryland, which is in the final stage of construction and scheduled for shakedown testing in early 1999. In prior work with the Catholic University of America Vitreous State Laboratory, Duratek has found that slurrying is the most efficient way to introduce low-level radioactive, hazardous, and mixed wastes into vitrification melters. However, many of the Hanford tank wastes to be vitrified contain species (primarily chloride and sulfate) that are corrosive to the vitrifier or the downstream air pollution control equipment, especially under the elevated temperature conditions existent in these components. Removal of these corrosives presents a significant challenge because most tank wastes contain high (up to 10-molar) concentrations of sodium hydroxide (NaOH) along with significant levels of nitrate, nitrite, and other anions, which render standard ion-exchange, membrane filtration, and other separation technologies relatively ineffective. In Task 20, the Energy and Environmental Research Center (EERC) will work with Duratek to develop and optimize a vitrification pretreatment process for consistent, quantitative removal of chloride and sulfate prior to vitrifier injection

Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction.

Science.gov (United States)

García-Robledo, Carlos; Kuprewicz, Erin K; Staines, Charles L; Erwin, Terry L; Kress, W John

2016-01-19

The critical thermal maximum (CTmax), the temperature at which motor control is lost in animals, has the potential to determine if species will tolerate global warming. For insects, tolerance to high temperatures decreases with latitude, suggesting that similar patterns may exist along elevational gradients as well. This study explored how CTmax varies among species and populations of a group of diverse tropical insect herbivores, the rolled-leaf beetles, across both broad and narrow elevational gradients. Data from 6,948 field observations and 8,700 museum specimens were used to map the elevational distributions of rolled-leaf beetles on two mountains in Costa Rica. CTmax was determined for 1,252 individual beetles representing all populations across the gradients. Initial morphological identifications suggested a total of 26 species with populations at different elevations displaying contrasting upper thermal limits. However, compared with morphological identifications, DNA barcodes (cytochrome oxidase I) revealed significant cryptic species diversity. DNA barcodes identified 42 species and haplotypes across 11 species complexes. These 42 species displayed much narrower elevational distributions and values of CTmax than the 26 morphologically defined species. In general, species found at middle elevations and on mountaintops are less tolerant to high temperatures than species restricted to lowland habitats. Species with broad elevational distributions display high CTmax throughout their ranges. We found no significant phylogenetic signal in CTmax, geography, or elevational range. The narrow variance in CTmax values for most rolled-leaf beetles, especially high-elevation species, suggests that the risk of extinction of insects may be substantial under some projected rates of global warming.

Effect of temperature and ionic impurities at very low concentrations on stress corrosion cracking of type 304 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Ruther, W.E.; Soppet, W.K.; Kassner, T.F.

1984-11-01

The relative effect of approx. 12 anion species, in conjunction with hydrogen and sodium cations, on the stress-corrosion-cracking (SCC) behavior of lightly sensitized Type 304 stainless steel was investigated in constant-extension-rate-tensile (CERT) tests at 289/sup 0/C in water with 0.2 ppM dissolved oxygen at total conductivity values of less than or equal to 1 ..mu..S/cm. The results show that the sulfur species, either in acid or sodium form, produce the highest degree of IGSCC relative to other anions. The effect of temperature on the SCC behavior of the material was investigated in CERT tests over the range 110 to 320/sup 0/C in high-purity water and in water containing 0.1 and 1.0 ppM sulfate as H/sub 2/SO/sub 4/ at a dissolved oxygen concentration of 0.2 ppM. The CERT parameters were correlated with impurity concentration (i.e., conductivity) and the electrochemical potential of platinum and Type 304 stainless steel electrodes in the high-temperature environments. Maximum IGSCC occurred at temperatures between approx. 200 and 250/sup 0/C in high-purity water, and the addition of sulfate increased the average crack growth rates and the temperature range over which maximum susceptibility occurred. A distinct transition from intergranular to transgranular and ultimately to a ductile failure mode was observed as the temperature increased from approx. 270 to 320/sup 0/C in high-purity water. This transition was attributed to a decrease in the open-circuit corrosion potential of the steel below a critical value of approx. 0 mV(SHE) at the higher temperature. A large decrease in the crack growth rates of fracture-mechanics-type specimens of the steel was also found when the temperature was increased from 289 to 320/sup 0/C in high-purity water with 0.2 ppM dissolved oxygen. 26 references, 8 figures, 6 tables.

Effect of temperature and ionic impurities at very low concentrations on stress corrosion cracking of type 304 stainless steel

International Nuclear Information System (INIS)

Ruther, W.E.; Soppet, W.K.; Kassner, T.F.

1984-11-01

The relative effect of approx. 12 anion species, in conjunction with hydrogen and sodium cations, on the stress-corrosion-cracking (SCC) behavior of lightly sensitized Type 304 stainless steel was investigated in constant-extension-rate-tensile (CERT) tests at 289 0 C in water with 0.2 ppM dissolved oxygen at total conductivity values of less than or equal to 1 μS/cm. The results show that the sulfur species, either in acid or sodium form, produce the highest degree of IGSCC relative to other anions. The effect of temperature on the SCC behavior of the material was investigated in CERT tests over the range 110 to 320 0 C in high-purity water and in water containing 0.1 and 1.0 ppM sulfate as H 2 SO 4 at a dissolved oxygen concentration of 0.2 ppM. The CERT parameters were correlated with impurity concentration (i.e., conductivity) and the electrochemical potential of platinum and Type 304 stainless steel electrodes in the high-temperature environments. Maximum IGSCC occurred at temperatures between approx. 200 and 250 0 C in high-purity water, and the addition of sulfate increased the average crack growth rates and the temperature range over which maximum susceptibility occurred. A distinct transition from intergranular to transgranular and ultimately to a ductile failure mode was observed as the temperature increased from approx. 270 to 320 0 C in high-purity water. This transition was attributed to a decrease in the open-circuit corrosion potential of the steel below a critical value of approx. 0 mV(SHE) at the higher temperature. A large decrease in the crack growth rates of fracture-mechanics-type specimens of the steel was also found when the temperature was increased from 289 to 320 0 C in high-purity water with 0.2 ppM dissolved oxygen. 26 references, 8 figures, 6 tables

Stability of very-high pressure arc discharges against perturbations of the electron temperature

Energy Technology Data Exchange (ETDEWEB)

Benilov, M. S. [Departamento de Fisica, Ciencias Exactas e Engenharia, Universidade da Madeira, Largo do Municipio, Funchal 9000 (Portugal); Hechtfischer, U. [Philips Lighting, BU Automotive Lamps, Technology, Philipsstrasse 8, Aachen 52068 (Germany)

2012-04-01

We study the stability of the energy balance of the electron gas in very high-pressure plasmas against longitudinal perturbations, using a local dispersion analysis. After deriving a dispersion equation, we apply the model to a very high-pressure (100 bar) xenon plasma and find instability for electron temperatures, T{sub e}, in a window between 2400 K and 5500-7000 K x 10{sup 3} K, depending on the current density (10{sup 6}-10{sup 8} A/m{sup 2}). The instability can be traced back to the Joule heating of the electron gas being a growing function of T{sub e}, which is due to a rising dependence of the electron-atom collision frequency on T{sub e}. We then analyze the T{sub e} range occurring in very high-pressure xenon lamps and conclude that only the near-anode region exhibits T{sub e} sufficiently low for this instability to occur. Indeed, previous experiments have revealed that such lamps develop, under certain conditions, voltage oscillations accompanied by electromagnetic interference, and this instability has been pinned down to the plasma-anode interaction. A relation between the mechanisms of the considered instability and multiple anodic attachments of high-pressure arcs is discussed.

High Ra, high Pr convection with viscosity gradients

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. High Ra, high Pr convection with viscosity gradients. Weak upward flow through mesh. Top fluid more viscous. Unstable layer Instability Convection.

Zircaloy behaviour in high temperature irradiated water

International Nuclear Information System (INIS)

Urbanic, V.F.

1982-04-01

The corrosion and hydriding of Zircaloy during irradiation in high temperature water is strongly dependent on the oxygen concentration of the water. Corrosion tests in the NRX and NRU research reactors using small samples have demonstrated the importance of water chemistry in maintaining Zircaloy corrosion and hydriding within acceptable limits. Zircaloy fuel cladding develops non-uniform, patch-type oxides during irradiation in hich temperature water containing dissolved oxygen. Results from examinations of prototype fuel cladding irradiated in the research reactors are presented to show how local variations in coolant flow, fast neutron flux, metallurgical structure and surface condition can influence the onset of non-uniform corrosion under these conditions. Destructive examinations of CANDU-PHW reactor fuel cladding have emphasized the importance of good chemistry control, especially the dissolved oxygen concentration of the water. When reactor coolants are maintained under normal reducing conditions at high pH (5 to 10 cm 3 D 2 /kg D 2 O; 2 /kg D 2 O; pH > 10 with LiOD), Zircaloy cladding develops non-uniform, patch-type oxides. These patch-type oxides tend to coalesce with time to form a thick, uniform oxide layer after extended exposure. Under reducing coolant conditions, Zircaloy cladding absorbs less than 200 mg D/kg Zr (approximately 2.5 mg/dm 2 equivalent hydrogen) in about 500 days. With oxygen in the coolant, deuterium absorption is considerably less despite the significant increase in corrosion under such conditions

Corrosion kinetic of 2 and 4 zircaloys in air at high temperatures

International Nuclear Information System (INIS)

Goncalves, A.C.; Goncalves, Z.C.

1986-01-01

The corrosion results of 2 and 4 zircaloys obtained in a thermal balance between 500 and 850 0 C are discussed based on the model of 'reduction of diffusion path'. The behaviour of both alloys has shown almost similar in this interval of temperature, proving that the corrosion is processed by an identical kinetic mechanism. It is still analysed the formation of superposed layer of porous oxide and the possible influence of the oxygen partial pressure in inversion velocities between 750 and 800 0 C. (Author) [pt

Central-peripheral temperature gradient: an early diagnostic sign of late-onset neonatal sepsis in very low birth weight infants.

Science.gov (United States)

Leante-Castellanos, José Luis; Lloreda-García, José M; García-González, Ana; Llopis-Baño, Caridad; Fuentes-Gutiérrez, Carmen; Alonso-Gallego, José Ángel; Martínez-Gimeno, Antonio

2012-04-22

We assessed central-peripheral temperature gradient alteration for the diagnosis of late-onset neonatal sepsis and compared earliness detection of this sign with altered blood cell count and C-reactive protein. Thirty-one preterm babies (peripheral) temperatures were continuously monitored with a thermal probe (ThermoTracer; Dräger Medical AGF & Co. KgaA, Lübeck, Germany) adjusting incubator air temperature for a thermal gradient peripheral temperature alteration was defined as a thermal gradient >2°C that could not be corrected with protocolized air temperature modifications. Proven (positive blood culture) sepsis and probable late-onset sepsis were recorded. Late-onset sepsis was diagnosed in 11 neonates (proven, 9; probable, 2). Thermal gradient alteration was present in 12 cases, in association with the onset of sepsis in 10 and concomitantly with a ductus arteriosus and stage 1 necrotizing enterocolitis in 2. Thermal gradient alteration had a sensitivity of 90.9% [95% confidence interval (CI), 62.3-98.4] and specificity of 90% (95% CI, 69.9-97.2%), and in 80% of cases, it occurred before abnormal laboratory findings. Central-peripheral temperature gradient monitoring is a feasible, non-invasive, and simple tool easily applicable in daily practice. An increase of >2°C showed a high-sensitivity and specificity for the diagnosis of late-onset sepsis.

Stress corrosion cracking behaviour of low alloy steels in high temperature water: Description and results from modelling

International Nuclear Information System (INIS)

Tirbonod, B.

2001-01-01

The initiation and growth of a crack by stress and corrosion in the low alloy steels used for the pressure vessels of Boiling Water Reactors may affect the availability and safety of the plant. This paper presents a new model for stress corrosion cracking of the low alloy steels in high temperature water. The model, based on observations, assumes the crack growth mechanism to be based on an anodic dissolution and cleavage. The main results deal with the position of the dissolution cell found at the crack tip, and with the identification of the parameters sensitive to crack growth, among which are the electrolyte composition and the cleavage length. The model is conservative, in qualitative agreement with measurements conducted at PSI, and may be extended to other metal-environment systems. (author)

Low temperature corrosion in bark fuelled, small boilers

Energy Technology Data Exchange (ETDEWEB)

Lindau, Leif; Goldschmidt, Barbara

2008-05-15

A number of small (3-12 MW), new biofuel boiler plants in southern Sweden, and (at least) in Austria, have suffered a high (wastage of mm/yrs) corrosion rate on the low temperature boiler side. This problem has been investigated with respect to its occurrence and its character by contacts with operators, by plant inspections, and by analysis of cold-side deposits. The plants affected have low feed water temperatures (< 100 deg C). The plants fire most types of Swedish biofuel: chips, bark, hog fuel, and 'GROT' (=twigs and tops). The results found give basis for a hypothesis that the corrosion results from the presence of an aqueous phase in the deposits, this phase being stabilized by dissolved salts having high solubility. It then follows that for each salt, there is a critical relative humidity (calculated from the flue gas water partial pressure and the cooling surface temperature as is common practice among boiler engineers) for both the presence of the aqueous phase and the corrosion. Some critical single salts, ZnCl{sub 2} and CaCl{sub 2} have been identified, and they give critical 'relative humidities' of 5% and 18% respectively. These figures are a lower bound. The corresponding figure, derived from the practical experience and the reported plant operational data, is between 20 and 30%. Corrosion tests have been carried out by exposing an air-cooled probe in the flue gases at a 12 MW boiler at Saevelundsverket in Alingsaas, and the material wastage at different temperatures has been measured with a profilometer. The high corrosion rates were reproduced in the tests for high relative humidities. The corrosion rate was small and not measurable (<0.1 mm/year) for relative humidity <22%. The work shows by means of indirect evidence that the corrosion critical components are ZnCl{sub 2} and possibly CaCl{sub 2} as well. The practical engineering design criterion derived from the work is that the relative humidity (calculated from the flue

Polymer concrete composites for the production of high strength pipe and linings in high temperature corrosive environments

Science.gov (United States)

Zeldin, A.; Carciello, N.; Fontana, J.; Kukacka, L.

High temperature corrosive resistant, non-aqueous polymer concrete composites are described. They comprise about 12 to 20% by weight of a water-insoluble polymer binder polymerized in situ from a liquid monomer mixture consisting essentially of about 40 to 70% by weight of styrene, about 25 to 45% by weight acrylonitrile and about 2.5 to 7.5% by weight acrylamide or methacrylamide and about 1 to 10% by weight of a crosslinking agent. This agent is selected from the group consisting of trimethylolpropane trimethacrylate and divinyl benzene; and about 80 to 88% by weight of an inert inorganic filler system containing silica sand and portland cement, and optionally Fe/sub 2/O/sub 3/ or carbon black or mica. A free radical initiator such as di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, other organic peroxides and combinations thereof to initiate crosspolymerization of the monomer mixture in the presence of said inorganic filler.

Air temperature gradient in large industrial hall

Science.gov (United States)

Karpuk, Michał; Pełech, Aleksander; Przydróżny, Edward; Walaszczyk, Juliusz; Szczęśniak, Sylwia

2017-11-01

In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature gradient above working zone should be taken into consideration. In this regard, experimental research of the vertical air temperature gradient in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature gradient in the area between 2.0 and 7.0 m above the floor was calculated and analysed.

High temperature corrosion studies on friction welded low alloy steel and stainless steel in air and molten salt environment at 650 oC

International Nuclear Information System (INIS)

Arivazhagan, N.; Narayanan, S.; Singh, Surendra; Prakash, Satya; Reddy, G.M.

2012-01-01

Highlights: → Thermogravimetric analysis on friction welded AISI 304 with AISI 4140 exposed in air and molten salt environment. → Comparative study on friction welded AISI 4140 with AISI 304 exposed in air, Na 2 SO 4 -60%V 2 O 5 and NaCl-50%Na 2 SO 4 at 650 o C. → SEM/EDAX, XRD analysis on corroded dissimilar AISI 304 and AISI 4140 materials. -- Abstract: The investigation on high-temperature corrosion resistance of the weldments is necessary for prolonged service lifetime of the components used in corrosive environments. This paper reports on the performance of friction welded low alloy steel AISI 4140 and stainless steel AISI 304 in air as well as molten salt environment of Na 2 SO 4 -60%V 2 O 5 and NaCl-50%Na 2 SO 4 at 650 o C. This paper reports several studies carried out for characterizing the weldments corrosion behavior. Initially thermogravimetric technique was used to establish the kinetics of corrosion. For analyzing the corrosion products, X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe micro analysis techniques were used. From the results of the experiments, it is observed that the weldments suffered accelerated corrosion in NaCl-Na 2 SO 4 environment and showed spalling/sputtering of the oxide scale. Furthermore, corrosion resistance of weld interface was found to be lower than that of parent metals in molten salt environment. Weight gain kinetics in air oxidation studies reveals a steady-state parabolic rate law while the kinetics with salt deposits displays multi-stage growth rates. Moreover NaCl is the main corrosive species in high temperature corrosion, involving mixtures of NaCl and Na 2 SO 4 which is responsible for formation of internal attack.

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

Science.gov (United States)

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

2018-02-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

Science.gov (United States)

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

2018-01-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

High resolution estimates of the corrosion risk for cultural heritage in Italy

International Nuclear Information System (INIS)

De Marco, Alessandra; Screpanti, Augusto; Mircea, Mihaela; Piersanti, Antonio; Proietti, Chiara; Fornasier, M. Francesca

2017-01-01

Air pollution plays a pivotal role in the deterioration of many materials used in buildings and cultural monuments causing an inestimable damage. This study aims to estimate the impacts of air pollution (SO 2 , HNO 3 , O 3 , PM 10 ) and meteorological conditions (temperature, precipitation, relative humidity) on limestone, copper and bronze based on high resolution air quality data-base produced with AMS-MINNI modelling system over the Italian territory over the time period 2003–2010. A comparison between high resolution data (AMS-MINNI grid, 4 × 4 km) and low resolution data (EMEP grid, 50 × 50 km) has been performed. Our results pointed out that the corrosion levels for limestone, copper and bronze are decreased in Italy from 2003 to 2010 in relation to decrease of pollutant concentrations. However, some problem related to air pollution persists especially in Northern and Southern Italy. In particular, PM 10 and HNO 3 are considered the main responsible for limestone corrosion. Moreover, the high resolution data (AMS-MINNI) allowed the identification of risk areas that are not visible with the low resolution data (EMEP modelling system) in all considered years and, especially, in the limestone case. Consequently, high resolution air quality simulations are suitable to provide concrete benefits in providing information for national effective policy against corrosion risk for cultural heritage, also in the context of climate changes that are affecting strongly Mediterranean basin. - Highlights: • Air pollution plays a pivotal role in the deterioration of cultural materials. • Limestone, copper and bronze corrosion levels decreased in Italy from 2003 to 2010. • PM 10 is considered the main responsible for limestone corrosion in Northern Italy. • HNO3 is considered the main responsible for limestone corrosion in all analyzed years. • High-resolution data are particularly useful to define area at risk for corrosion. - Importance of the high

High temperature corrosion investigation in an oxyfuel combustion test rig

DEFF Research Database (Denmark)

Montgomery, Melanie; Bjurman, M.; Hjörnhede, A

2014-01-01

Oxyfuel firing and subsequent capture of CO2 is a way to reduce CO2 emissions from coal‐fired boilers. Literature is summarized highlighting results which may contribute to understanding of the corrosion processes in an oxyfuel boiler.Tests were conducted in a 500 kWth oxyfuel test facility...... constructed by Brandenburg Technical University to gain understanding into oxyfuel firing. Two air‐cooled corrosion probes were exposed in this oxyfuel combustion chamber where the fuel was lignite. Gas composition was measured at the location of testing. Various alloys from a 2½ Cr steel, austenitic steels...... to nickel alloys were exposed at set metal temperatures of 570 and 630 °C for 287 h. The specimens were investigated using light optical and scanning electron microscopy and X‐ray diffraction.The deposit on the probe contained predominantly CaSO4 and Fe2O3. Oxide thickness and depth of the precipitated...

Pumping liquid metal at high temperatures up to 1,673 kelvin

Science.gov (United States)

Amy, C.; Budenstein, D.; Bagepalli, M.; England, D.; Deangelis, F.; Wilk, G.; Jarrett, C.; Kelsall, C.; Hirschey, J.; Wen, H.; Chavan, A.; Gilleland, B.; Yuan, C.; Chueh, W. C.; Sandhage, K. H.; Kawajiri, Y.; Henry, A.

2017-10-01

Heat is fundamental to power generation and many industrial processes, and is most useful at high temperatures because it can be converted more efficiently to other types of energy. However, efficient transportation, storage and conversion of heat at extreme temperatures (more than about 1,300 kelvin) is impractical for many applications. Liquid metals can be very effective media for transferring heat at high temperatures, but liquid-metal pumping has been limited by the corrosion of metal infrastructures. Here we demonstrate a ceramic, mechanical pump that can be used to continuously circulate liquid tin at temperatures of around 1,473-1,673 kelvin. Our approach to liquid-metal pumping is enabled by the use of ceramics for the mechanical and sealing components, but owing to the brittle nature of ceramics their use requires careful engineering. Our set-up enables effective heat transfer using a liquid at previously unattainable temperatures, and could be used for thermal storage and transport, electric power production, and chemical or materials processing.

Study of the corrosion of metallic coatings and alloys containing aluminum in a mixed atmosphere - sulphur, oxygen - at high temperatures

International Nuclear Information System (INIS)

Fellmann, Daniel

1982-01-01

The objective of this research thesis is the development of materials for a sulphur experimental loop allowing the thermodynamic properties of such an energy cycle to be checked. As solutions must comply with industrial methods, rare materials are excluded as they are too expensive or difficult to implement. Iron-based materials have been tested but could not have at the same time a good corrosion resistance and high temperature forming and mechanical toughness properties. Therefore, metallic coatings have been chosen, specifically alumina. After having reported a bibliographical study on corrosion by sulphur vapour and by oxygen and by sulphur-oxygen, the author presents the experimental materials and methods. Then, the author reports the study of mixed corrosion (by sulphur and oxygen together) of metallic alloys (ferritic and austeno-ferritic alloys, aluminium and titanium alloys), and of the corrosion of FeAlx coatings, of AlTix alloys [fr

Peculiar high temperature corrosion of martensite alloy under impact of Estonian oil shale fly ash

Energy Technology Data Exchange (ETDEWEB)

Tallermo, H; Klevtsov, I [Thermal Engineering Department of Tallinn Technical University, Tallinn (Estonia)

1999-12-31

The superheaters` surfaces of oil shale steam boiler made of pearlitic and austenitic alloys, are subject to intensive corrosion, mainly due to presence of chlorine in external deposits. The applicability of martensitic alloys X1OCrMoVNb91 and X20CrMoV121 for superheaters is examined here and empirical equations allowing to predict alloys` corrosion resistance in the range of operational temperatures are established. Alloy X1OCrMoVNb91 is found been most perspective for superheaters of boilers firing fossil fuel that contain alkaline metals and chlorine. The abnormal dependence of corrosion resistance of martensitic alloys on temperature is revealed, namely, corrosion at 580 deg C in presence of oil shale fly ash is more intensive than at 620 deg C. (orig.) 2 refs.

Peculiar high temperature corrosion of martensite alloy under impact of Estonian oil shale fly ash

Energy Technology Data Exchange (ETDEWEB)

Tallermo, H.; Klevtsov, I. [Thermal Engineering Department of Tallinn Technical University, Tallinn (Estonia)

1998-12-31

The superheaters` surfaces of oil shale steam boiler made of pearlitic and austenitic alloys, are subject to intensive corrosion, mainly due to presence of chlorine in external deposits. The applicability of martensitic alloys X1OCrMoVNb91 and X20CrMoV121 for superheaters is examined here and empirical equations allowing to predict alloys` corrosion resistance in the range of operational temperatures are established. Alloy X1OCrMoVNb91 is found been most perspective for superheaters of boilers firing fossil fuel that contain alkaline metals and chlorine. The abnormal dependence of corrosion resistance of martensitic alloys on temperature is revealed, namely, corrosion at 580 deg C in presence of oil shale fly ash is more intensive than at 620 deg C. (orig.) 2 refs.

Studies of Corrosion Resistant Materials Being Considered for High-Level Nuclear Waste Containment in Yucca Mountain Relevant Environments

International Nuclear Information System (INIS)

McCright, R.D.; Ilevbare, G.; Estill, J.; Rebak, R.

2001-01-01

Containment of spent nuclear fuel and vitrified forms of high level nuclear waste require use of materials that are highly corrosion resistant to all of the anticipated environmental scenarios that can occur in a geological repository. Ni-Cr-Mo Alloy 22 (UNS N60622) is proposed for the corrosion resistant outer barrier of a two-layer waste package container at the potential repository site at Yucca Mountain. A range of water compositions that may contact the outer barrier is under consideration, and a testing program is underway to characterize the forms of corrosion and to quantify the corrosion rates. Results from the testing support models for long term prediction of the performance of the container. Results obtained to date indicate a very low general corrosion rate for Alloy 22 and very high resistance to all forms of localized and environmentally assisted cracking in environments tested to date

Corrosion of Zircaloy-clad fuel rods in high-temperature PWRs: Measurement of waterside corrosion in North Anna Unit 1

International Nuclear Information System (INIS)

Balfour, M.G.; Kilp, G.R.; Comstock, R.J.; McAtee, K.R.; Thornburg, D.R.

1992-03-01

Twenty-four peripheral rods and two interior rods from North Anna Unit 1, End-of-Cycle 7, were measured at poolside for waterside corrosion on four-cycle Region 6 assemblies F35 and F66, with rod average burnups of 60 GWD/MTU. Similar measurements were obtained on 24 two-cycle fuel rods from Region 8A assemblies H02 and H10 with average burnups of about 40 GWD/MTU. The Region 6 peripheral rods had been corrosion measured previously after three cycles, at 45 GWD/MTU average burnup. The four-cycle Region 6 fuel rods showed high corrosion, compared to only intermediate corrosion level after three cycles. The accelerated corrosion rate in the fourth cycle was accompanied by extensive laminar cracking and spalling of the oxide film in the thickest regions. The peak corrosion of the two-cycle region 8A rods was 32 μm to 53 μm, with some isolated incipient oxide spalling. In conjunction with the in-reactor corrosion measurements, extensive characterization tests plus long-term autoclave corrosion tests were performed on archive samples of the three major tubing lots represented in the North Anna measurements. The autoclave tests generally showed the same ordering of corrosion by tubing lot as in the reactor; the chief difference between the archive tubing samples was a lower tin content (1.38 percent) for the lot with the lowest corrosion rate compared with a higher tin content (1.58) for the lot with the highest corrosion rate. There was no indication in the autoclave tests of an accelerated rate of corrosion as observed in the reactor

Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

International Nuclear Information System (INIS)

Moon, Joonoh; Ha, Heon-Young; Lee, Tae-Ho

2013-01-01

The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr 2 N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite

Corrosion properties of HLW and spent fuel overpacks in highly alkaline environments

International Nuclear Information System (INIS)

Kursten, B.

2009-01-01

Throughout the world, deep geological disposal in stable rocks with low groundwater flow is considered for the long-term management of long-lived radioactive waste (vitrified high-level waste - VHLW - and spent fuel - SF).The main advantage of the SC design, with respect to corrosion, is that under the predicted conditions (i.e. highly alkaline concrete buffer), the carbon steel overpack is expected to undergo uniform corrosion (passive dissolution). The key objective of this study is to demonstrate that the carbon steel overpack will be able to ensure complete containment of the radioactivity at least during the thermal phase, this is the period during which the temperature of the host rock is expected to lie above the range of temperatures within which nominal radionuclide migration properties can be relied upon

Determination of boundaries between ranges of high and low gradient of beam profile.

Science.gov (United States)

Wendykier, Jacek; Bieniasiewicz, Marcin; Grządziel, Aleksandra; Jedynak, Tadeusz; Kośniewski, Wiktor; Reudelsdorf, Marta; Wendykier, Piotr

2016-01-01

This work addresses the problem of treatment planning system commissioning by introducing a new method of determination of boundaries between high and low gradient in beam profile. The commissioning of a treatment planning system is a very important task in the radiation therapy. One of the main goals of this task is to compare two field profiles: measured and calculated. Applying points of 80% and 120% of nominal field size can lead to the incorrect determination of boundaries, especially for small field sizes. The method that is based on the beam profile gradient allows for proper assignment of boundaries between high and low gradient regions even for small fields. TRS 430 recommendations for commissioning were used. The described method allows a separation between high and low gradient, because it directly uses the value of the gradient of a profile. For small fields, the boundaries determined by the new method allow a commissioning of a treatment planning system according to the TRS 430, while the point of 80% of nominal field size is already in the high gradient region. The method of determining the boundaries by using the beam profile gradient can be extremely helpful during the commissioning of the treatment planning system for Intensity Modulated Radiation Therapy or for other techniques which require very small field sizes.

Corrosion of high purity copper as engineering barrier in deep geological repositories

International Nuclear Information System (INIS)

Ochoa, Maité; Rodríguez Martín, A.; Farina Silvia, B.

2013-01-01

Pure copper with oxygen content below 5 ppm (to minimize segregation at grain boundaries) and doped with phosphorus (to increase creep resistance) is the chosen material for the corrosion-resistant barrier of the High Level Radioactive 2 Wastecontainers in the Swedish and Finnish repository models. These models include the construction of the repository below the water table, which is a reducing environment in which copper has excellent resistance to general and localized corrosion in aqueous electrolytes. The aim of this work is contribute to determine the durability of the material, given that deep geological repositories of HLW are designed to ensure the protection of the environment for periods of hundreds of thousands years. As a first step in a more general analysis the effects of chloride, one of the main aggressive species of corrosion, are evaluated. To this purpose corrosion potential was determined and anodic polarization curves were performed in deaerated solutions varying the chloride concentration between 0.01 and 1M and the temperature between 30 and 90°C. Several electrochemical techniques were used: the evolution of corrosion potential was measured, anodic polarization curves were obtained and electrochemical impedance tests were performed. The analysis was complemented with microscopic observations of the type of corrosive attack, as well as determinations of the eventual corrosion products formed using Energy-Dispersive X-ray Analysis (EDS). Results show that the corrosion potential decreases with the increase of temperature and with the increase of chloride concentration. A correlation of the corrosion potential as a function of temperature and chloride concentration was obtained, with the purpose of making predictions in variable conditions.The current density increases both with temperature and with chloride concentration. A pitting potential is observed in certain conditions. (author)

submitter Quench Protection of Very Large, 50-GJ-Class, and High-Temperature-Superconductor-Based Detector Magnets

CERN Document Server

Mentink, Matthias; Mulder, Tim; Van Nugteren, Jeroen; ten Kate, Herman

2016-01-01

An investigation is performed on the quench behavior of a conceptual 50-GJ 8-T high-temperature-superconductor-based solenoid. In this design, a 50-kA conductor-on-round-core cable-in-conduit conductor utilizing ReBCO technology is envisioned, operating at 40 K. Various properties such as resistivity, thermal conductivity, and heat capacity are very different at this temperature, which affects the quench behavior. It is found that the envisioned conductor is very stable with a minimum quench energy of about 2 kJ. However, the quench propagation velocity is typically about 20 mm/s, so that creating a wide-spread normal zone throughout the coil is very challenging. Moreover, an extraction voltage exceeding 20 kV would be required to ensure a hot-spot temperature below 100 K once a thermal runaway occurs. A novel concept dubbed “rapid quench transformation” is proposed whereby the superconducting conductor is co-wound with a normal conductor to achieve a high degree of inductive coupling. This geometry allow...

Pitting corrosion resistance of high alloy OCTG in ferric chloride solution

International Nuclear Information System (INIS)

Masamura, K.; Yamamoto, S.; Matsushima, I.

1986-01-01

The effects of alloying elements and precipitated phases on the corrosion rate of high alloy OCTG in the ferric chloride solution have been evaluated. The corrosion rate of Fe-Cr-Ni-Mo alloys without precipitated phases, e.g. carbides and sigma phase, can be estimated from the composition using the following equation: log(C.R.)=-0.144xPRE-7690/(273+T)+28.6 where C.R. is the corrosion rate in g/m/sup 2//hr; PRE is Cr+3Mo+16N in percent and T is the test temperature in 0 C. The activation energies of the ferric chloride test are almost the same regardless of PRE or Ni content when no detrimental phase precipitates. When carbides or the sigma phase precipitate, the corrosion rate is higher and the activation energy is lowered. This suggests that secondary phases give preferential sites for initiation of pitting corrosion

NATO Advanced Research Workshop on Boron Rich Solids Sensors for Biological and Chemical Detection, Ultra High Temperature Ceramics, Thermoelectrics, Armor

CERN Document Server

Orlovskaya, Nina

2011-01-01

The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •boron-rich solids: science and technology; •synthesis and sintering strategies of boron rich solids; •microcantileve...

Relativistic klystrons for high-gradient accelerators

International Nuclear Information System (INIS)

Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S.; Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W.; Hopkins, D.B.; Sessler, A.M.; Haimson, J.; Mecklenburg, B.

1991-01-01

Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. The authors have learned how to overcome their previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power

Strain rate dependent environmental cracking of ferritic steels in high temperature water

International Nuclear Information System (INIS)

Tice, D.R.

1989-01-01

Corrosion fatigue crack growth testing demonstrates that a pre-existing defect which might be inadvertently present in the wall of a thick walled component such as the main reactor pressure vessel would not grow in service under transient loading to reach a critical size which would threaten vessel integrity. Steady load stress corrosion has received renewed attention following publication of data showing that stress corrosion cracking can occur in high temperature aqueous environments. Evidence shows that stress corrosion cracking cannot occur in normal pressurized water reactor (PWR) operating conditions. Environmental cracking of ferritic steels in high temperature aqueous environments is influenced by a range of material and environmental variables, amongst the most important being dissolved oxygen (or other oxidants) in the water, water purity and the sulphur content of the steel

Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

DEFF Research Database (Denmark)

Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

2009-01-01

of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium....

High temperature oxidation and corrosion in marine environments of thermal spray deposited coatings

International Nuclear Information System (INIS)

Chaliampalias, D.; Vourlias, G.; Pavlidou, E.; Stergioudis, G.; Skolianos, S.; Chrissafis, K.

2008-01-01

Flame spraying is a widely used technique for depositing a great variety of materials in order to enforce the mechanical or the anticorrosion characteristics of the substrate. Its high rate application is due to the rapidity of the process, its effectiveness and its low cost. In this work, flame-sprayed Al coatings are deposited on low carbon steels in order to enhance their anticorrosion performance. The main adhesion mechanism of the coating is mechanical anchorage, which can provide the necessary protection to steel used in several industrial and constructive applications. To evaluate the corrosion resistance of the coating, the as-coated samples are subjected in a salt spray chamber and in elevated temperature environments. The examination and characterization of the corroded samples is done by scanning electron microscopy and X-ray diffraction analysis. The as-formed coatings are extremely rough and have a lamellic homogeneous morphology. It is also found that Al coatings provide better protection in marine atmospheres, while at elevated temperatures a thick oxide layer is formed, which can delaminate after long oxidation periods due to its low adherence to the underlying coating, thus eliminating the substrate protection

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures.

Science.gov (United States)

Douglas, Peter M J; Affek, Hagit P; Ivany, Linda C; Houben, Alexander J P; Sijp, Willem P; Sluijs, Appy; Schouten, Stefan; Pagani, Mark

2014-05-06

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10-17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

Coreless Concept for High Gradient Induction Cell

International Nuclear Information System (INIS)

Krasnykh, Anatoly

2008-01-01

An induction linac cell for a high gradient is discussed. The proposed solid state coreless approach for the induction linac topology (SLIM(reg s ign)) is based on nanosecond mode operation. This mode may have an acceleration gradient comparable with gradients of rf- accelerator structures. The discussed induction system has the high electric efficiency. The key elements are a solid state semiconductor switch and a high electric density dielectric with a thin section length. The energy in the induction system is storied in the magnetic field. The nanosecond current break-up produces the high voltage. The induced voltage is used for acceleration. This manner of an operation allows the use of low voltage elements in the booster part and achieves a high accelerating gradient. The proposed topology was tested in POP (proof of principle) experiments

Platform for high temperature materials (PHiTEM)

International Nuclear Information System (INIS)

Baluc, N.; Hoffelner, W.; Michler, J.

2007-01-01

Advanced energy power systems like Generation IV fission reactors, thermonuclear fusion reactors, solar thermal/solar chemical reactors, gas turbines and coal gasification systems require materials that can operate at high temperatures in extreme environments: irradiation, corrosion, unidirectional and cyclic loads. On the path to development of new and adequate high temperature materials, understanding of damage formation and evolution and of damage effects is indispensable. Damage of materials in components takes place on different time and length scales. Component failure is usually a macroscopic event. Macroscopic material properties and their changes with time (e.g., hardening, creep embrittlement, corrosion) are determined by the micro- to nano-properties of the material. The multi scale is an ambitious and challenging attempt to take these facts into consideration by developing an unified model of the material behaviour. This requires, however, dedicated tools to test and analyse materials on different scales. The platform for high temperatures materials is being set up within the framework of collaboration between the EPFL, the PSI and the EMPA. It has three main goals: 1) Establish a platform that allows the multi scale characterization of relationships between microstructure and mechanical properties of advanced, high temperature materials, with a focus on irradiated, i.e. radioactive, materials, by combining the use of a focused ion beam and a nano indentation device with multi scale modelling and simulations. 2) Use the methods developed and the results gained for existing materials for developing improved high temperature materials to be used in advanced and sustainable future energy power plants. 3) Become an attractive partner for industry by providing a wide knowledge base, flexibility in answering technical questions and skills to better understand damage in already existing plants and to support development of new products at the industrial scale

Array-type sensor to determine corrosive conditions in high temperature water under gamma rays irradiation

International Nuclear Information System (INIS)

Satoh, T.; Tsukada, T.; Uchida, S.; Katoh, C.

2010-01-01

One of the problems to determine electrochemical corrosion potential (ECP) in high temperature water under irradiation is to apply long-lived and reliable reference electrodes. In order to avoid troubles due to the reference electrode, a new concept to determine ECP without the reference electrode has been proposed. Several metal plates are applied as working electrodes and at the same time as the reference electrodes. Potential of the metal plates with stable oxide films on their surfaces show stable values in high temperature water. As a result of the combination of their potential values, ECP of each metal can be determined without any specific reference electrode. Array-type sensors consisting of several metal plates, e.g., Fe, Ni, Cr, Zr, Pt, Pd, Re, Ir, with well developed oxide films on their surface were prepared for ECP measurement in high temperature water under neutron/gamma ray irradiations. In order to confirm the feasibility of this concept, responses of the redox potentials of the pure metals to changes in the simulated BWR reactor water conditions were measured and the ECP was determined by the differences in potentials between a couple of metal plates. Major conclusions of the study are as follows: 1) The redox potentials of the Fe, Pt, Zr, Ir, Pd, and Re electrodes showed the different dependences on the changes in O 2 and H 2 O 2 concentrations. The redox potentials of the electrodes increased as the oxidant concentrations increased except for Zr electrode. The potential of the Zr electrode was kept the very low potential at the wide range of O 2 and H 2 O 2 concentrations differed form the other electrodes. 2) It was estimated that the redox potential of highly soluble metal may be increased, while that of low soluble metal may be decreased by an oxide film. The stable oxide film would cause the stable potential response of the electrode with oxide film. 3) The relationship between the oxidant concentrations and the redox potentials of the

Methods for very high temperature design

International Nuclear Information System (INIS)

Blass, J.J.; Corum, J.M.; Chang, S.J.

1989-01-01

Design rules and procedures for high-temperature, gas-cooled reactor components are being formulated as an ASME Boiler and Pressure Vessel Code Case. A draft of the Case, patterned after Code Case N-47, and limited to Inconel 617 and temperatures of 982/degree/C (1800/degree/F) or less, will be completed in 1989 for consideration by relevant Code committees. The purpose of this paper is to provide a synopsis of the significant differences between the draft Case and N-47, and to provide more complete accounts of the development of allowable stress and stress rupture values and the development of isochronous stress vs strain curves, in both of which Oak Ridge National Laboratory (ORNL) played a principal role. The isochronous curves, which represent average behavior for many heats of Inconel 617, were based in part on a unified constitutive model developed at ORNL. Details are also provided of this model of inelastic deformation behavior, which does not distinguish between rate-dependent plasticity and time-dependent creep, along with comparisons between calculated and observed results of tests conducted on a typical heat of Inconel 617 by the General Electric Company for the Department of Energy. 4 refs., 15 figs., 1 tab

Stress corrosion cracking susceptibilities of various stainless steels in high temperature water

International Nuclear Information System (INIS)

Shoji, Saburo; Ohnaka, Noriyuki; Kikuchi, Eiji; Minato, Akira; Tanno, Kazuo.

1980-01-01

The intergranular stress corrosion cracking (IGSCC) behaviors of several austenitic stainless steels in high temperature water were evaluated using three types of SCC tests, i.e., single U-bend test in chloride containing water, uniaxial constant load and constant extension rate tests (CERT) in pure water. The steels used were SUS 304, 304L, 316, 316L, 321 and 347 and several heats of them to examine heat to heat variations. The three test methods gave the same relative ranking of the steels. The CERT is the most sensitive method to detect the relative IGSCC susceptibilities. The CERT result for relative ranking from poor to good is: SUS 304 - 0.07% C, 304 - 0.06% C, 304L - 0.028% C, 316 - 0.07% C. The IGSCC susceptibilities of SUS 304L - 0.020% C, 316L - 0.023% C, 321 and 347 were not detected. These test results suggest that the use of the low carbon, molybdenum bearing, or stabilized austenitic stainless steel is beneficial for eliminating the IGSCC problem in boiling water reactor environment. (author)

Hydrofluoric Acid Corrosion Study of High-Alloy Materials

International Nuclear Information System (INIS)

Osborne, P.E.

2002-01-01

A corrosion study involving high-alloy materials and concentrated hydrofluoric acid (HF) was conducted in support of the Molten Salt Reactor Experiment Conversion Project (CP). The purpose of the test was to obtain a greater understanding of the corrosion rates of materials of construction currently used in the CP vs those of proposed replacement parts. Results of the study will help formulate a change-out schedule for CP parts. The CP will convert slightly less than 40 kg of 233 U from a gas (UF 6 ) sorbed on sodium fluoride pellets to a more stable oxide (U 3 O 8 ). One by-product of the conversion is the formation of concentrated HF. Six moles of highly corrosive HF are produced for each mole of UF 6 converted. This acid is particularly corrosive to most metals, elastomers, and silica-containing materials. A common impurity found in 233 U is 232 U. This impurity isotope has several daughters that make the handling of the 233 U difficult. Traps of 233 U may have radiation fields of up to 400 R at contact, a situation that makes the process of changing valves or working on the CP more challenging. It is also for this reason that a comprehensive part change-out schedule must be established. Laboratory experiments involving the repeated transfer of HF through 1/2-in. metal tubing and valves have proven difficult due to the corrosivity of the HF upon contact with all wetted parts. Each batch of HF is approximately 1.5 L of 33 wt% HF and is transferred most often as a vapor under vacuum and at temperatures of up to 250 C. Materials used in the HF side of the CP include Hastelloy C-276 and Monel 400 tubing, Haynes 230 and alloy C-276 vessels, and alloy 400 valve bodies with Inconel (alloy 600) bellows. The chemical compositions of the metals discussed in this report are displayed in Table 1. Of particular concern are the almost 30 vendor-supplied UG valves that have the potential for exposure to HF. These valves have been proven to have a finite life due to failure

High-temperature compatibility between liquid metal as PWR fuel gap filler and stainless steel and high-density concrete

Science.gov (United States)

Wongsawaeng, Doonyapong; Jumpee, Chayanit; Jitpukdee, Manit

2014-08-01

In conventional nuclear fuel rods for light-water reactors, a helium-filled as-fabricated gap between the fuel and the cladding inner surface accommodates fuel swelling and cladding creep down. Because helium exhibits a very low thermal conductivity, it results in a large temperature rise in the gap. Liquid metal (LM; 1/3 weight portion each of lead, tin, and bismuth) has been proposed to be a gap filler because of its high thermal conductivity (∼100 times that of He), low melting point (∼100 °C), and lack of chemical reactivity with UO2 and water. With the presence of LM, the temperature drop across the gap is virtually eliminated and the fuel is operated at a lower temperature at the same power output, resulting in safer fuel, delayed fission gas release and prevention of massive secondary hydriding. During normal reactor operation, should an LM-bonded fuel rod failure occurs resulting in a discharge of liquid metal into the bottom of the reactor pressure vessel, it should not corrode stainless steel. An experiment was conducted to confirm that at 315 °C, LM in contact with 304 stainless steel in the PWR water chemistry environment for up to 30 days resulted in no observable corrosion. Moreover, during a hypothetical core-melt accident assuming that the liquid metal with elevated temperature between 1000 and 1600 °C is spread on a high-density concrete basement of the power plant, a small-scale experiment was performed to demonstrate that the LM-concrete interaction at 1000 °C for as long as 12 h resulted in no penetration. At 1200 °C for 5 h, the LM penetrated a distance of ∼1.3 cm, but the penetration appeared to stop. At 1400 °C the penetration rate was ∼0.7 cm/h. At 1600 °C, the penetration rate was ∼17 cm/h. No corrosion based on chemical reactions with high-density concrete occurred, and, hence, the only physical interaction between high-temperature LM and high-density concrete was from tiny cracks generated from thermal stress. Moreover

High temperature corrosion of thermally sprayed NiCr- and amorphous Fe-based coatings covered with a KCl-K{sub 2}SO{sub 4} salt

Energy Technology Data Exchange (ETDEWEB)

Varis, T.; Suhonen, T.; Tuurna, S.; Ruusuvuori, K.; Holmstroem, S.; Salonen, J. [VTT, Espoo (Finland); Bankiewicz, D.; Yrjas, P. [Aabo Akademi Univ., Turku (Finland)

2010-07-01

New process conditions due to the requirement of higher efficiency together with the use of high-chlorine and alkali containing fuels such as biomass and waste fuels for heat and electricity production will challenge the resistance and life of tube materials. In conventional materials the addition of alloying elements to increase the corrosion resistance in aggressive combustion conditions increases costs relatively rapidly. Thermally sprayed coating offer promising, effective, flexible and cost efficient solutions to fulfill the material needs for the future. Some heat exchanger design alteractions before global commercialization have to be overcome, though. High temperature corrosion in combustion plants can occur by a variety of mechanisms including passive scale degradation with subsequent rapid scaling, loss of adhesion and scale detachment, attack by melted or partly melted deposits via fluxing reactions and intergranular-/interlamellar corrosion. A generally accepted model of the ''active oxidation'' attributes the responsibility for inducing corrosion to chlorine. The active oxidation mechanism plays a key role in the thermally sprayed coatings due to their unique lamellar structure. In this study, the corrosion behaviour of NiCr (HVOF and Wire Arc), amorphous Fe-based, and Fe13Cr (Wire Arc) thermally sprayed coatings, were tested in the laboratory under simplified biomass combustion conditions. The tests were carried out by using a KCl-K{sub 2}SO{sub 4} salt mixture as a synthetic biomass ash, which was placed on the materials and then heat treated for one week (168h) at two different temperatures (550{sup 0}C and 600 C) and in two different gas atmospheres (air and air+30%H{sub 2}O). After the exposures, the metallographic cross sections of the coatings were studied with SEM/EDX analyzer. The results showed that the coatings behaved relatively well at the lower test temperature while critical corrosion through the lamella boundaries

The steam pressure effect on high temperature corrosion of zircaloy-4

International Nuclear Information System (INIS)

Kim, K. P.; Park, G. H.

1998-01-01

To find the effect of pressure on the high temperature oxidation of zircaloy-4, an autoclave capable of measuring the degree of oxidation at high temperatures and high pressure was manufactured. The degree of high temperature oxidation of zircaloy-4 was measured at three different conditions, high pressure steam, high pressure Ar gas with small amount of steam, and 1 atm steam. All the measurements were done at 750 deg C. The oxide thickness is much thicker in high pressure steam, comparing to that in the 1 atm steam. And, the higher is the steam pressure, the thicker becomes the oxide. No effect was observed in the case of high pressure Ar containing small amount of steam. Many cracks exist on the surface of specimens oxidized at high pressure steam, which come from the enhanced tetragonal to monoclinic phase transformation due to high pressure steam. The enhanced oxidation seems to oxide cracking

Corrosion of carbon steel in saturated high-level waste salt solutions

International Nuclear Information System (INIS)

Wiersma, B.J.; Parish, W.R.

1997-01-01

High level waste stored as crystallized salts is to be removed from carbon steel tanks by water dissolution. Dissolution of the saltcake must be performed in a manner which will not impact the integrity of the tank. Corrosion testing was performed to determine the amount of corrosion inhibitor that must be added to the dissolution water in order to ensure that the salt solution formed would not induce corrosion degradation of the tank materials. The corrosion testing performed included controlled potential slow strain rate, coupon immersion, and potentiodynamic polarization tests. These tests were utilized to investigate the susceptibility of the cooling coil material to stress corrosion cracking in the anticipated environments. No evidence of SCC was observed in any of the tests. Based on these results, the recommended corrosion requirements were that the temperature of the salt solution be less than 50 degrees C and that the minimum hydroxide concentration be 0.4 molar. It was also recommended that the hydroxide concentration not stay below 0.4 molar for longer than 45 days

Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy.

Science.gov (United States)

Nair, R B; Arora, H S; Mukherjee, Sundeep; Singh, S; Singh, H; Grewal, H S

2018-03-01

Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al 0.1 CoCrFeNi HEA in two different media: distilled water with and without 3.5wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al 0.1 CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA. Copyright © 2017 Elsevier B.V. All rights reserved.

Stress corrosion in high-strength aluminum alloys

Science.gov (United States)

Dorward, R. C.; Hasse, K. R.

1980-01-01

Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

A high-gradient high-duty-factor Rf photo-cathode electron gun

International Nuclear Information System (INIS)

Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

2002-01-01

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

A high-gradient high-duty-factor RF photo-cathode electron gun

International Nuclear Information System (INIS)

Rimmer, Robert; Hartman, N.; Lidia, S.; Wang, S.H.

2002-01-01

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

Failure analysis of high strength pipeline with single and multiple corrosions

International Nuclear Information System (INIS)

Chen, Yanfei; Zhang, Hong; Zhang, Juan; Li, Xin; Zhou, Jing

2015-01-01

Highlights: • We study failure of high strength pipelines with single corrosion. • We give regression equations for failure pressure prediction. • We propose assessment procedure for pipelines with multiple corrosions. - Abstract: Corrosion will compromise safety operation of oil and gas pipelines, accurate determination of failure pressure finds importance in residual strength assessment and corrosion allowance design of onshore and offshore pipelines. This paper investigates failure pressure of high strength pipeline with single and multiple corrosions using nonlinear finite element analysis. On the basis of developed regression equations for failure pressure prediction of high strength pipeline with single corrosion, the paper proposes an assessment procedure for predicting failure pressure of high strength pipeline with multiple corrosions. Furthermore, failure pressures predicted by proposed solutions are compared with experimental results and various assessment methods available in literature, where accuracy and versatility are demonstrated

Corrosion and hydriding behaviour of some Zr 2.5 wt% Nb alloys in water, steam and various gases at high temperature

Energy Technology Data Exchange (ETDEWEB)

Dalgaard, S. B.

1962-05-15

Fuel sheaths and pressure tubes in Canadian power reactors are at present made from Zircaloy-2. Mechanical properties of a suitably heat treated Zr 2.5 wt% Nb alloy are superior to those of Zircaloy-2, but any new alloy must have resistance to corrosion and hydriding by the coolant and by the gas that insulates the pressure tube from the cold moderator. Exposed to water at temperatures up to 325{sup o}C, the Zr 2.5 wt% Nb alloy has corrosion resistance acceptable for power reactors. Resistance to air and carbon dioxide is less favourable. Addition of tin, or iron and chromium, to the base alloy have little effect on the corrosion resistance, but the addition of copper reduces corrosion in water and steam to some extent and in air and carbon dioxide to a greater extent. Studies of the effect of heat treatment suggest that the amount of niobium in a solid-solution controls the rate of oxidation and hydriding and that concentration, size and distribution of second phase is of little importance. Initial results obtained in NRX indicate that a thermal flux of 3-7 x 10{sup 13} n/cm{sup 2}/sec has little or no effect on oxidation and hydriding in high temperature water. (author)

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi; Kvisgaard, M.; Montgomery, Melanie

2017-01-01

Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre......-oxidised Al and Ti-containing alloys (Kanthal APM and Nimonic 80A, respectively) was investigated under laboratory conditions mimicking biomass firing. The alloys were pre-oxidised at 900°C for 1 week. Afterwards, pre-oxidised samples, and virgin non-pre-oxidised samples as reference, were coated...... with a synthetic deposit of KCl and exposed at 560°C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre...

Improving corrosion resistance of post-tensioned substructures emphasizing high performance grouts

Science.gov (United States)

Schokker, Andrea Jeanne

The use of post-tensioning in bridges can provide durability and structural benefits to the system while expediting the construction process. When post-tensioning is combined with precast elements, traffic interference can be greatly reduced through rapid construction. Post-tensioned concrete substructure elements such as bridge piers, hammerhead bents, and straddle bents have become more prevalent in recent years. Chloride induced corrosion of steel in concrete is one of the most costly forms of corrosion each year. Coastal substructure elements are exposed to seawater by immersion or spray, and inland bridges may also be at risk due to the application of deicing salts. Corrosion protection of the post-tensioning system is vital to the integrity of the structure because loss of post-tensioning can result in catastrophic failure. Documentation for durability design of the grout, ducts, and anchorage systems is very limited. The objective of this research is to evaluate the effectiveness of corrosion protection measures for post-tensioned concrete substructures by designing and testing specimens representative of typical substructure elements using state-of-the-art practices in aggressive chloride exposure environments. This was accomplished through exposure testing of twenty-seven large-scale beam specimens and ten large-scale column specimens. High performance grout for post-tensioning tendon injection was also developed through a series of fresh property tests, accelerated exposure tests, and a large-scale pumping test to simulate field conditions. A high performance fly ash grout was developed for applications with small vertical rises, and a high performance anti-bleed grout was developed for applications involving large vertical rises such as tall bridge piers. Long-term exposure testing of the beam and column specimens is ongoing, but preliminary findings indicate increased corrosion protection with increasing levels of post-tensioning, although traditional

Fundamental corrosion characterization of high-strength titanium alloys

International Nuclear Information System (INIS)

Schutz, R.W.; Grauman, J.S.

1984-01-01

Many commercially available and several developmental high-strength titanium alloys were evaluated for application in chloride-containing environments with respect to general, crevice, and stress corrosion resistance. Studies in boiling reducing and oxidizing acid chloride media permitted identification of certain high-strength titanium alloys, containing ≥4 weight % molybdenum, which are significantly more resistant than unalloyed titanium with respect to general and crevice attack. Data regression analysis suggests that molybdenum and vanadium impart a significant positive effect on alloy corrosion resistance under reducing acid chloride conditions, whereas aluminum is detrimental. Little effect of metallurgical condition (that is, annealed versus aged) on corrosion behavior of the higher molybdenum-containing alloys was noted. No obvious susceptibility to chloride and sulfide stress corrosion cracking (SCC) was detected utilizing U-bend specimens at 177 0 C

Corrosion of 316 stainless steel in high temperature molten Li{sub 2}BeF{sub 4} (FLiBe) salt

Energy Technology Data Exchange (ETDEWEB)

Zheng, Guiqiu, E-mail: guiqiuzheng@gmail.com; Kelleher, Brian; Cao, Guoping; Anderson, Mark; Allen, Todd; Sridharan, Kumar

2015-06-15

In support of structural material development for the fluoride-salt-cooled high-temperature reactor (FHR), corrosion tests of 316 stainless steel were performed in the potential primary coolant, molten Li{sub 2}BeF{sub 4} (FLiBe) at 700 °C for an exposure duration up to 3000 h. Tests were performed in both 316 stainless steel and graphite capsules. Corrosion in both capsule materials occurred by the dissolution of chromium from the stainless steel into the salt which led to the depletion of chromium predominantly along the grain boundaries of the test samples. The samples tested in graphite capsules showed a factor of two greater depth of corrosion attack as measured in terms of chromium depletion, compared to those tested in 316 stainless steel capsules. The samples tested in graphite capsules showed the formation of Cr{sub 7}C{sub 3} particulate phases throughout the depth of the corrosion layer. Samples tested in both types of capsule materials showed the formation of MoSi{sub 2} phase due to increased activity of Mo and Si as a result of Cr depletion, and furthermore corrosion promoted the formation of a α-ferrite phase in the near-surface regions of the 316 stainless steel. Based on the corrosion tests, the corrosion attack depth in FLiBe salt was predicted as 17.1 μm/year and 31.2 μm/year for 316 stainless steel tested in 316 stainless steel and in graphite capsules respectively. It is in an acceptable range compared to the Hastelloy-N corrosion in the Molten Salt Reactor Experiment (MSRE) fuel salt.

High Temperature Operational Experiences of Helium Experimental Loop

International Nuclear Information System (INIS)

Kim, Chan Soo; Hong, Sung-Deok; Kim, Eung-Seon; Kim, Min Hwan

2015-01-01

The development of high temperature components of VHTR is very important because of its higher operation temperature than that of a common light water reactor and high pressure industrial process. The development of high temperature components requires the large helium loop. Many countries have high temperature helium loops or a plan for its construction. Table 1 shows various international state-of-the-art of high temperature and high pressure gas loops. HELP performance test results show that there is no problem in operation of HELP at the very high temperature experimental condition. These experimental results also provide the basic information for very high temperature operation with bench-scale intermediate heat exchanger prototype in HELP. In the future, various heat exchanger tests will give us the experimental data for GAMMA+ validation about transient T/H behavior of the IHX prototype and the optimization of the working fluid in the intermediate loop

Promising materials for HTGR high temperature heat exchangers

International Nuclear Information System (INIS)

Kuznetsov, E.V.; Tokareva, T.B.; Ryabchenkov, A.V.; Novichkova, O.V.; Starostin, Yu.D.

1989-01-01

The service conditions for high-temperature heat-exchangers with helium coolant of HTGRs and requirements imposed on materials for their production are discussed. The choice of nickel-base alloys with solid-solution hardening for long-term service at high temperatures is grounded. Results of study on properties and structure of types Ni-25Cr-5W-5Mo and Ni-20Cr-20W alloy in the temperature range of 900 deg. - 1,000 deg. C are given. The ageing of Ni-25Cr-5W-5Mo alloy at 900 deg. - 950 deg. C results in decreased corrosion-mechanical properties and is caused by the change of structural metal stability. Alloy with 20% tungsten retains a high stability of both structure and properties after prolonged exposure in helium at above temperatures. The alloy has also increased resistance to delayed fracture and low-cycle fatigue at high temperatures. The developed alloy of type Ni-20Cr-20W with microalloying is recommended for production of tubes for HTGR high-temperature heat-exchangers with helium coolant. (author). 3 refs, 8 figs

MODELING THE CORROSION OF HIGH-LEVEL WASTE CONTAINERS CAM-CRM INTERFACE

International Nuclear Information System (INIS)

JOSEPH C. FARMER, PETER J. BEDROSSIAN, R. DANIEL MCCRIGHT

1998-01-01

A key component of the Engineered Barrier System (EBS) being designed for containment of spent-fuel and high-level waste at the proposed geological repository at Yucca Mountain, Nevada is a two-layer canister. In this particular design, the inner barrier is made of a corrosion resistant material (CRM) such as Alloy 625 or C-22, while the outer barrier is made of a corrosion-allowance material (CAM) such as carbon steel or Monel400. Initially, the containers will be hot and dry due to the heat generated by radioactive decay. However, the temperature will eventually drop to levels where both humid air and aqueous phase corrosion will be possible. As the outer barrier is penetrated, uniform corrosion of the CRM will be possible in exfoliated areas. The possibility for crevice formation between the CAM and CRM will also exist. In the case of either Alloy 625 or C-22, a crevice will have to form before significant penetration of the CRM can occur. Crevice corrosion of the CRMs has been well documented. Lillard and Scully have induced crevice corrosion in Alloy 625 during exposure to artificial sea water. Jones and Wilde have prepared simulated crevice solutions of FeCl 2 , NiCl 2 and CrCl 3 , and measured substantial pH suppression. Asphahani measured the dissolution rates of Alloys 625 and C-22 in such artificial crevice solutions at various temperatures. Others have observed no significant localized attack in less severe environments

High-temperature corrosion of lanthanum in equimole mixture of sodium and potassium chlorides

International Nuclear Information System (INIS)

Kochergin, V.P.; Obozhina, R.N.; Dragoshanskaya, T.I.; Startsev, B.P.

1984-01-01

Results of investigation into the process of lanthanum corrosion in the molted equimole NaCl-KCl mixture after the change of test time, temperature and lanthanum trichloride were summarized. It was shown that polarization of lanthanum anode in equimole NaCl-KCl melt is controlled by La 3+ diffusion from near-electrode layer to electrolyte depth, which results in decrease of corrosion rate in time. The established electrochemical properties of metallic lanthanum in equimole NaCl-KCl mixture must be considered when improving the technology of electrochemical production of lanthanum or its alloys of molten chlorides of lanthanum and alkaline metals

Gradient twinned 304 stainless steels for high strength and high ductility

Energy Technology Data Exchange (ETDEWEB)

Chen, Aiying [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai (China); Liu, Jiabin; Wang, Hongtao [Institute of Applied Mechanics, Zhejiang University, Hangzhou (China); Lu, Jian, E-mail: jianlu@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Wang, Y. Morris, E-mail: ymwang@llnl.gov [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA (United States)

2016-06-14

Gradient materials often have attractive mechanical properties that outperform uniform microstructure counterparts. It remains a difficult task to investigate and compare the performance of various gradient microstructures due to the difficulty of fabrication, the wide range of length scales involved, and their respective volume percentage variations. We have investigated four types of gradient microstructures in 304 stainless steels that utilize submicrotwins, nanotwins, nanocrystalline-, ultrafine- and coarse-grains as building blocks. Tensile tests reveal that the gradient microstructure consisting of submicrotwins and nanotwins has a persistent and stable work hardening rate and yields an impressive combination of high strength and high ductility, leading to a toughness that is nearly 50% higher than that of the coarse-grained counterpart. Ex- and in-situ transmission electron microscopy indicates that nanoscale and submicroscale twins help to suppress and limit martensitic phase transformation via the confinement of martensite within the twin lamellar. Twinning and detwinning remain active during tensile deformation and contribute to the work hardening behavior. We discuss the advantageous properties of using submicrotwins as the main load carrier and nanotwins as the strengthening layers over those coarse and nanocrystalline grains. Our work uncovers a new gradient design strategy to help metals and alloys achieve high strength and high ductility.

Sound beam manipulation based on temperature gradients

Energy Technology Data Exchange (ETDEWEB)

Qian, Feng [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Quan, Li; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

2015-10-28

Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

Subsurface temperatures and geothermal gradients on the north slope of Alaska

Science.gov (United States)

Collett, T.S.; Bird, K.J.; Magoon, L.B.

1993-01-01

On the North Slope of Alaska, geothermal gradient data are available from high-resolution, equilibrated well-bore surveys and from estimates based on well-log identification of the base of ice-bearing permafrost. A total of 46 North Slope wells, considered to be in or near thermal equilibrium, have been surveyed with high-resolution temperatures devices and geothermal gradients can be interpreted directly from these recorded temperature profiles. To augment the limited North Slope temperature data base, a new method of evaluating local geothermal gradients has been developed. In this method, a series of well-log picks for the base of the ice-bearing permafrost from 102 wells have been used, along with regional temperature constants derived from the high-resolution stabilized well-bore temperature surveys, to project geothermal gradients. Geothermal gradients calculated from the high-resolution temperature surveys generally agree with those projected from known ice-bearing permafrost depths over most of the North Slope. Values in the ice-bearing permafrost range from ??? 1.5??C 100 m in the Prudhoe Bay area to ??? 4.5??C 100 m in the east-central portion of the National Petroleum Reserve in Alaska. Geothermal gradients below the ice-bearing permafrost sequence range from ??? 1.6??C 100 m to ??? 5.2??C 100 m. ?? 1993.

Corrosion monitoring using high-frequency guided waves

Science.gov (United States)

Fromme, P.

2016-04-01

Corrosion can develop due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Generalized corrosion leading to wall thickness loss can cause the reduction of the strength and thus degradation of the structural integrity. The monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic wedge transducers with single sided access to the structure, guided wave modes were selectively generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted for wall thickness reduction due to milling of the steel structure. From the measured signal changes due to the wave mode interference the reduced wall thickness was monitored. Good agreement with theoretical predictions was achieved. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Double shell slurry low-temperature corrosion tests

International Nuclear Information System (INIS)

Divine, J.R.; Bowen, W.M.; McPartland, S.A.; Elmore, R.P.; Engel, D.W.

1983-09-01

A series of year-long tests have been completed on potential double shell slurry (DSS) compositions at temperatures up to 100 0 C. These tests have sought data on uniform corrosion, pitting, and stress-corrosion cracking. No indication of the latter two types of corrosion were observed within the test matrix. Corrosion rates after four months were generally below the 1 mpy (25 μm/y) design limit. By the end of twelve months all results were below this limit and, except for very concentrated mixtures, all were below 0.5 mpy. Prediction equations were generated from a model fitted to the data. The equations provide a rapid means of estimating the corrosion rate for proposed DSS compositions

High gradient superconducting quadrupoles

International Nuclear Information System (INIS)

Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

1987-07-01

Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

High temperature corrosion in the thermochemical hydrogen production from nuclear heat

International Nuclear Information System (INIS)

Coen-Porisini, F.; Imarisio, G.

1976-01-01

In the production of hydrogen by water decomposition utilizing nuclear heat, a multistep process has to be employed. Water and the intermediate chemical products reach in chemical cycles giving hydrogen and oxygen with regeneration of the primary products used. Three cycles are examined, characterized by the presence of halide compounds and particularly hydracids at temperatures up to 800 0 C. Corrosion tests were carried out in hydrobromic acid, hydrochloric acid, ferric chloride solutions, and hydriodic acid

Experimental and numerical study of the effects of a nanocrystallisation treatment on high-temperature oxidation of a zirconium alloy

International Nuclear Information System (INIS)

Panicaud, B.; Retraint, D.; Grosseau-Poussard, J.-L.; Li, L.; Guérain, M.; Goudeau, P.; Tamura, N.; Kunz, M.

2012-01-01

Highlights: ► SMAT leads to a modification of surface properties of an M5 zirconium alloy (grain size and roughness. ► SMAT induces a change in the oxidation kinetics during high temperature oxidation. ► A diffusion model is able to reproduce kinetics and emphasise the consequences of SMAT on dissolution of oxygen in Zr. - Abstract: In the present work, the effects of a nanocrystallisation treatment on the high-temperature oxidation of a zirconium alloy are investigated. Surface Mechanical Attrition Treatment is a recent process designed to nanocrystallise the surface of materials. The particular effects of this treatment on an M5 zirconium alloy are studied using different experimental techniques at several scales. This material is of considerable interest, especially to the nuclear industry where very stringent conditions apply. High temperature oxidation was performed in order to show the benefits of this type of nanocrystallisation on the corrosion resistance of the alloy concerned. Microstructure development mechanisms, which improve the oxidation resistance of zirconium alloys have been identified during high-temperature corrosion. Those mechanisms have been discussed in further detail in relation to numerical calculations concerning the oxidation kinetics.

Analysis and description of high temperature alloy data and their representation in the high temperature materials data bank of the Joint Research Centre

International Nuclear Information System (INIS)

Krefeld, R.; Kroeckel, H.; Fattori, G.; Maurandy, C.

1985-01-01

In the frame of the high temperature materials programme the JRC has set up a pilot data bank for mechanical and corrosion properties of materials for high temperature application in energy conversion and chemical systems. The scope of the data bank content embraces mechanical properties and corrosion tests with emphasis on 600 to 1000 0 C test temperature and C-O-H type test environments. The basic information on materials properties obtained by test is analysed and the data items and their structure are described. The logical structure of the 250 data items involved and their organization in the data bank by file and record using ADABAS dbms is presented. The design is discussed with respect to its adaptability to changes in the scope of data content and to its versatile data access resulting in easy handling of complex structured queries which represent the interest of materials scientists and engineers as well as those of non-specialist users. (orig.)

Solubilities of iron and nickel oxides under high temperature and high pressure conditions

International Nuclear Information System (INIS)

Choi, Ke-Chon; Jung, Yong-Ju; Yeon, Jei-Won; Jee, Kwang-Yong

2007-01-01

The purposes of primary coolant chemistry are to assure fuel and material integrity and to minimize out of core radiation fields. During the PWR operation, crud deposits are expected on the cladding, leading to cladding failure and raising the radioactivity. Such deposits come from the corrosion products of system surface. To achieve optimal conditions for primary coolant, basic researches on mass transfer, deposition and solubility of corrosion products are needed. The initial stage of crud formation could be the studies on the solubility of a structural material. It has been known that the solubility of metal oxides in boric acid under high temperature and high pressure condition depends on the pH and dissolved hydrogen. Thus, the effect of various pH on the solubility of metal oxide in boric acid solution was investigated in this work

Numerical simulations of helium flow through prismatic fuel elements of very high temperature reactors

International Nuclear Information System (INIS)

Ribeiro, Felipe Lopes; Pinto, Joao Pedro C.T.A.

2013-01-01

The 4 th generation Very High Temperature Reactor (VHTR) most popular concept uses a graphite-moderated and helium cooled core with an outlet gas temperature of approximately 1000 deg C. The high output temperature allows the use of the process heat and the production of hydrogen through the thermochemical iodine-sulfur process as well as highly efficient electricity generation. There are two concepts of VHTR core: the prismatic block and the pebble bed core. The prismatic block core has two popular concepts for the fuel element: multihole and annular. In the multi-hole fuel element, prismatic graphite blocks contain cylindrical flow channels where the helium coolant flows removing heat from cylindrical fuel rods positioned in the graphite. In the other hand, the annular type fuel element has annular channels around the fuel. This paper shows the numerical evaluations of prismatic multi-hole and annular VHTR fuel elements and does a comparison between the results of these assembly reactors. In this study the analysis were performed using the CFD code ANSYS CFX 14.0. The simulations were made in 1/12 fuel element models. A numerical validation was performed through the energy balance, where the theoretical and the numerical generated heat were compared for each model. (author)

Corrosion Inhibition of High Speed Steel by Biopolymer HPMC Derivatives

Directory of Open Access Journals (Sweden)

Shih-Chen Shi

2016-07-01

Full Text Available The corrosion inhibition characteristics of the derivatives of biopolymer hydroxypropyl methylcellulose (HPMC, hydroxypropyl methylcellulose phthalate (HPMCP, and hydroxypropyl methylcellulose acetate succinate (HPMCAS film are investigated. Based on electrochemical impedance spectroscopic measurements and potentiodynamic polarization, the corrosion inhibition performance of high speed steel coated with HPMC derivatives is evaluated. The Nyquist plot and Tafel polarization demonstrate promising anti-corrosion performance of HPMC and HPMCP. With increasing film thickness, both materials reveal improvement in corrosion inhibition. Moreover, because of a hydrophobic surface and lower moisture content, HPMCP shows better anti-corrosion performance than HPMCAS. The study is of certain importance for designing green corrosion inhibitors of high speed steel surfaces by the use of biopolymer derivatives.

High temperature reactions between molybdenum and metal halides

International Nuclear Information System (INIS)

Boeroeczki, A.; Dobos, G.; Josepovits, V.K.; Hars, Gy.

2006-01-01

Good colour rendering properties, high intensity and efficacy are of vital importance for high-end lighting applications. These requirements can be achieved by high intensity discharge lamps doped with different metal halide additives (metal halide lamps). To improve their reliability, it is very important to understand the different failure processes of the lamps. In this paper, the corrosion reactions between different metal halides and the molybdenum electrical feed-through electrode are discussed. The reactions were studied in the feed-through of real lamps and on model samples too. X-ray photoelectron spectroscopy (XPS) was used to establish the chemical states. In case of the model samples we have also used atomic absorption spectroscopy (AAS) to measure the reaction product amounts. Based on the measurement results we were able to determine the most corrosive metal halide components and to understand the mechanism of the reactions

Corrosion monitoring using high-frequency guided ultrasonic waves

Science.gov (United States)

Fromme, Paul

2014-02-01

Corrosion develops due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, guided wave modes were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted and the wall thickness reduced by consecutive milling of the steel structure. Further measurements were conducted using accelerated corrosion in a salt water bath and the damage severity monitored. From the measured signal change due to the wave mode interference the wall thickness reduction was monitored. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Nanoscale coatings for erosion and corrosion protection of copper microchannel coolers for high powered laser diodes

Science.gov (United States)

Flannery, Matthew; Fan, Angie; Desai, Tapan G.

2014-03-01

High powered laser diodes are used in a wide variety of applications ranging from telecommunications to industrial applications. Copper microchannel coolers (MCCs) utilizing high velocity, de-ionized water coolant are used to maintain diode temperatures in the recommended range to produce stable optical power output and control output wavelength. However, aggressive erosion and corrosion attack from the coolant limits the lifetime of the cooler to only 6 months of operation. Currently, gold plating is the industry standard for corrosion and erosion protection in MCCs. However, this technique cannot perform a pin-hole free coating and furthermore cannot uniformly cover the complex geometries of current MCCs involving small diameter primary and secondary channels. Advanced Cooling Technologies, Inc., presents a corrosion and erosion resistant coating (ANCERTM) applied by a vapor phase deposition process for enhanced protection of MCCs. To optimize the coating formation and thickness, coated copper samples were tested in 0.125% NaCl solution and high purity de-ionized (DIW) flow loop. The effects of DIW flow rates and qualities on erosion and corrosion of the ANCERTM coated samples were evaluated in long-term erosion and corrosion testing. The robustness of the coating was also evaluated in thermal cycles between 30°C - 75°C. After 1000 hours flow testing and 30 thermal cycles, the ANCERTM coated copper MCCs showed a corrosion rate 100 times lower than the gold plated ones and furthermore were barely affected by flow rates or temperatures thus demonstrating superior corrosion and erosion protection and long term reliability.

Superconducting niobium cavities with high gradients

International Nuclear Information System (INIS)

Kneisel, P.; Saito, K.

1992-01-01

Present accelerator projects making use of superconducting cavity technology are constructed with design accelerating gradients E acc ranging between 5 MV/m and 8 MV/m and Q-values of several 10 9 . Future plans for upgrades of existing accelerators or for linear colliders call for gradients greater than 15 MV/m corresponding to peak surface electric fields above 30 MV/m. These demands challenge state-of-the-art production technology and require improvements in processing and handling of these cavities to overcome the major performance limitation of field emission loading. This paper reports on efforts to improve the performance of cavities made from niobium from different suppliers by using improved cleaning techniques after processing and ultrahigh vacuum annealing at temperatures of 1400 C. In single cell L-band cavities peak surface electric fields as high as 50 MV/m have been measured without significant field emission loading. (Author) 8 refs., fig

HG2006 Workshop on High-Gradient Radio Frequency

CERN Multimedia

2006-01-01

Meeting to be held at CERN on 25-27 September 2006 in Room 40/S2-B01 (Building 40). The objective of the workshop is to bring the high-gradient RF community together to present and discuss recent theoretical and experimental developments. Significant progress has recently been made in understanding the basic physics of rf breakdown and developing techniques for achieving higher gradients. This workshop should contribute to maintaining these efforts and to promoting contacts and collaboration. The scientific programme will be organized in half day sessions dedicated to: High-gradient rf experimental results Theory and computation High-gradient technology, materials and processing Specialized experiments on related high-gradient or high-power phenomenon like dc discharge and pulsed surface heating Reports from collaborations and projects. Each session will consist of selected presentations followed by a dedicated discussion. Information about the meeting and participant registration is available at http...

Development of low-temperature galvanizing and its application for corrosion protection of high-strength steels; Entwicklung einer niedrigschmelzenden Legierung und deren Applikation zum Korrosionsschutz hochfester Staehle

Energy Technology Data Exchange (ETDEWEB)

Wielage, B.; Lampke, T.; Steinhaeuser, S. [Technische Universitaet Chemnitz (Germany). Institut fuer Werkstoffwissenschaft und Werkstofftechnik; Strobel, C. [Fachhochschule Ingolstadt (Germany); Merklinger, V.

2008-12-15

Apart from reliability and quality, vehicle safety and cost efficiency are the decisive criteria for automobile manufacturers. Corrosion protection plays a decisive role because it increases the service life. The ultra-high-strength steels are materials which exhibit high lightweight potential as well as a very good energy absorption capacity because of their mechanical properties. In connection with the possibility of hot forming, they are predestined for the fabrication of complicated, load-compatible shapes in the crash-relevant frame and body construction. The application of these steel qualities has been carried out in structural parts which are protected from corrosion by a hot-dip coat of FeAl7 - the so-called Usibor. However, at the moment there is no ready-for-production solution for later corrosion protection of already hot-formed parts. Therefore, a corrosion protection system on the basis of conventional low-temperature galvanizing processes has been developed and utilized. First, the softening behavior of the highly-resistant 22MnB5 substrate was analyzed. Afterwards, a galvanizing system was developed and applied. The corrosion protection coatings were characterized with regard to their structure and corrosion protection potential. As a result, a significant improvement of the corrosion behaviour has occurred. (Abstract Copyright [2008], Wiley Periodicals, Inc.) [German] Neben Zuverlaessigkeit und Qualitaet sind vor allem Fahrzeugsicherheit und Wirtschaftlichkeit entscheidende Kriterien fuer den Automobilhersteller. Der Korrosionsschutz spielt dabei eine herausragende Rolle, da hierdurch die Lebens- und Gebrauchsdauer erhoeht wird. Mit der Bereitstellung hoechstfester Stahlqualitaeten stehen Werkstoffe zur Verfuegung, die auf Grund ihrer mechanischen Eigenschaften ein hohes Leichtbaupotenzial sowie ein sehr gutes Energieabsorptionsvermoegen aufweisen. In Verbindung mit der Moeglichkeit der Warmformgebung sind sie damit praedestiniert fuer die

Testing of Performance of Optical Fibers Under Irradiation in Intense Radiation Fields, When Subjected to Very High Temperatures

Energy Technology Data Exchange (ETDEWEB)

Blue, Thomas [The Ohio State Univ., Columbus, OH (United States); Windl, Wolfgang [The Ohio State Univ., Columbus, OH (United States); Dickerson, Bryan [Luna Innovations, Inc. (United States)

2013-01-03

The primary objective of this project is to measure and model the performance of optical fibers in intense radiation fields when subjected to very high temperatures. This research will pave the way for fiber optic and optically based sensors under conditions expected in future high-temperature gas-cooled reactors. Sensor life and signal-to-noise ratios are susceptible to attenuation of the light signal due to scattering and absorbance in the fibers. This project will provide an experimental and theoretical study of the darkening of optical fibers in high-radiation and high-temperature environments. Although optical fibers have been studied for moderate radiation fluence and flux levels, the results of irradiation at very high temperatures have not been published for extended in-core exposures. Several previous multi-scale modeling efforts have studied irradiation effects on the mechanical properties of materials. However, model-based prediction of irradiation-induced changes in silica's optical transport properties has only recently started to receive attention due to possible applications as optical transmission components in fusion reactors. Nearly all damage-modeling studies have been performed in the molecular-dynamics domain, limited to very short times and small systems. Extended-time modeling, however, is crucial to predicting the long-term effects of irradiation at high temperatures, since the experimental testing may not encompass the displacement rate that the fibers will encounter if they are deployed in the VHTR. The project team will pursue such extended-time modeling, including the effects of the ambient and recrystallization. The process will be based on kinetic MC modeling using the concept of amorphous material consisting of building blocks of defect-pairs or clusters, which has been successfully applied to kinetic modeling in amorphized and recrystallized silicon. Using this procedure, the team will model compensation for rate effects, and

Metallic materials corrosion problems in molten salt reactors

International Nuclear Information System (INIS)

Chauvin, G.; Dixmier, J.; Jarny, P.

1977-01-01

The USA forecastings concerning the molten salt reactors are reviewed (mixtures of fluorides containing the fuel, operating between 560 and 700 0 C). Corrosion problems are important in these reactors. The effects of certain characteristic factors on corrosion are analyzed: humidity and metallic impurities in the salts, temperature gradients, speed of circulation of salts, tellurium from fission products, coupling. In the molten fluorides and experimental conditions, the materials with high Ni content are particularly corrosion resistant alloys (hastelloy N). The corrosion of this material is about 2.6 mg.cm -2 at 700 0 C [fr

Summary of the experimental multi-purpose very high temperature gas cooled reactor design

International Nuclear Information System (INIS)

1984-12-01

The report presents the design of Multi-purpose Very High Temperature Gas Cooled Reactor (the Experimental VHTR) based on the second stage of detailed design which was completed on March 1984, in the from of ''An application of reactor construction permit Appendix 8''. The Experimental VHTR is designed to satisfy with the design specification for the reactor thermal output 50 MW and reactor outlet temperature 950 0 C. The adequacy of the design is also checked by the safety analysis. The planning of plant system and safety is summarized such as safety design requirements and conformance with them, seismic design and plant arrangement. Concerning with the system of the Experimental VHTR the design basis, design data and components are described in the order. (author)

High-Temperature Corrosion of AlCrSiN Film in Ar-1%SO2 Gas

Directory of Open Access Journals (Sweden)

Poonam Yadav

2017-03-01

Full Text Available AlCrSiN film with a composition of 29.1Al-17.1Cr-2.1Si-51.7N in at. % was deposited on a steel substrate by cathodic arc ion plating at a thickness of 1.8 μm. It consisted of nanocrystalline hcp-AlN and fcc-CrN, where a small amount of Si was dissolved. Corrosion tests were carried out at 800 °C for 5–200 h in Ar-1%SO2 gas. The major corrosion reaction was oxidation owing to the high oxygen affinity of Al and Cr in the film. The formed oxide scale consisted primarily of (Al,Cr2O3, within which Fe, Si, and S were dissolved. Even after corrosion for 200 h, the thickness of the scale was about 0.7–1.2 μm, indicating that the film had good corrosion resistance in the SO2-containing atmosphere.

Three-dimensional study of grain boundary engineering effects on intergranular stress corrosion cracking of 316 stainless steel in high temperature water

Science.gov (United States)

Liu, Tingguang; Xia, Shuang; Bai, Qin; Zhou, Bangxin; Zhang, Lefu; Lu, Yonghao; Shoji, Tetsuo

2018-01-01

The intergranular cracks and grain boundary (GB) network of a GB-engineered 316 stainless steel after stress corrosion cracking (SCC) test in high temperature high pressure water of reactor environment were investigated by two-dimensional and three-dimensional (3D) characterization in order to expose the mechanism that GB-engineering mitigates intergranular SCC. The 3D microstructure shown that the essential characteristic of the GB-engineered microstructure is formation of many large twin-boundaries as a result of multiple-twinning, which results in the formation of large grain-clusters. The large grain-clusters played a key role to the improvement of intergranular SCC resistance by GB-engineering. The main intergranular cracks propagated in a zigzag along the outer boundaries of these large grain-clusters because all inner boundaries of the grain-clusters were twin-boundaries (∑3) or twin-related boundaries (∑3n) which had much lower susceptibility to SCC than random boundaries. These large grain-clusters had tree-ring-shaped topology structure and very complex morphology. They got tangled so that difficult to be separated during SCC, resulting in some large crack-bridges retained in the crack surface.

Development of safety analysis codes and experimental validation for a very high temperature gas-cooled reactor Final report

Energy Technology Data Exchange (ETDEWEB)

Chang Oh

2006-03-01

The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR’s higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-of-coolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of toxic gasses (CO and CO2) and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were available that had been sufficiently developed and validated to reliably simulate a LOCA in the VHTR. Therefore, we have worked for the past three years on developing and validating advanced computational methods for simulating LOCAs in a VHTR. Research Objectives As described above, a pipe break may lead to significant fuel damage and fission product release in the VHTR. The objectives of this Korean/United States collaboration were to develop and validate advanced computational methods for VHTR safety analysis. The methods that have been developed are now

Development of safety analysis codes and experimental validation for a very high temperature gas-cooled reactor Final report

International Nuclear Information System (INIS)

Chang Oh

2006-01-01

The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 900 C and operational fuel temperatures above 1250 C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR's higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-of-coolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of toxic gases (CO and CO2) and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were available that had been sufficiently developed and validated to reliably simulate a LOCA in the VHTR. Therefore, we have worked for the past three years on developing and validating advanced computational methods for simulating LOCAs in a VHTR. Research Objectives As described above, a pipe break may lead to significant fuel damage and fission product release in the VHTR. The objectives of this Korean/United States collaboration were to develop and validate advanced computational methods for VHTR safety analysis. The methods that have been developed are now

Hydrofluoric Acid Corrosion Study of High-Alloy Materials

Energy Technology Data Exchange (ETDEWEB)

Osborne, P.E.

2002-09-11

A corrosion study involving high-alloy materials and concentrated hydrofluoric acid (HF) was conducted in support of the Molten Salt Reactor Experiment Conversion Project (CP). The purpose of the test was to obtain a greater understanding of the corrosion rates of materials of construction currently used in the CP vs those of proposed replacement parts. Results of the study will help formulate a change-out schedule for CP parts. The CP will convert slightly less than 40 kg of {sup 233}U from a gas (UF{sub 6}) sorbed on sodium fluoride pellets to a more stable oxide (U{sub 3}O{sub 8}). One by-product of the conversion is the formation of concentrated HF. Six moles of highly corrosive HF are produced for each mole of UF{sub 6} converted. This acid is particularly corrosive to most metals, elastomers, and silica-containing materials. A common impurity found in {sup 233}U is {sup 232}U. This impurity isotope has several daughters that make the handling of the {sup 233}U difficult. Traps of {sup 233}U may have radiation fields of up to 400 R at contact, a situation that makes the process of changing valves or working on the CP more challenging. It is also for this reason that a comprehensive part change-out schedule must be established. Laboratory experiments involving the repeated transfer of HF through 1/2-in. metal tubing and valves have proven difficult due to the corrosivity of the HF upon contact with all wetted parts. Each batch of HF is approximately 1.5 L of 33 wt% HF and is transferred most often as a vapor under vacuum and at temperatures of up to 250 C. Materials used in the HF side of the CP include Hastelloy C-276 and Monel 400 tubing, Haynes 230 and alloy C-276 vessels, and alloy 400 valve bodies with Inconel (alloy 600) bellows. The chemical compositions of the metals discussed in this report are displayed in Table 1. Of particular concern are the almost 30 vendor-supplied UG valves that have the potential for exposure to HF. These valves have been

Investigation on the Core Bypass Flow in a Very High Temperature Reactor

Energy Technology Data Exchange (ETDEWEB)

Hassan, Yassin

2013-10-22

Uncertainties associated with the core bypass flow are some of the key issues that directly influence the coolant mass flow distribution and magnitude, and thus the operational core temperature profiles, in the very high-temperature reactor (VHTR). Designers will attempt to configure the core geometry so the core cooling flow rate magnitude and distribution conform to the design values. The objective of this project is to study the bypass flow both experimentally and computationally. Researchers will develop experimental data using state-of-the-art particle image velocimetry in a small test facility. The team will attempt to obtain full field temperature distribution using racks of thermocouples. The experimental data are intended to benchmark computational fluid dynamics (CFD) codes by providing detailed information. These experimental data are urgently needed for validation of the CFD codes. The following are the project tasks: • Construct a small-scale bench-top experiment to resemble the bypass flow between the graphite blocks, varying parameters to address their impact on bypass flow. Wall roughness of the graphite block walls, spacing between the blocks, and temperature of the blocks are some of the parameters to be tested. • Perform CFD to evaluate pre- and post-test calculations and turbulence models, including sensitivity studies to achieve high accuracy. • Develop the state-of-the art large eddy simulation (LES) using appropriate subgrid modeling. • Develop models to be used in systems thermal hydraulics codes to account and estimate the bypass flows. These computer programs include, among others, RELAP3D, MELCOR, GAMMA, and GAS-NET. Actual core bypass flow rate may vary considerably from the design value. Although the uncertainty of the bypass flow rate is not known, some sources have stated that the bypass flow rates in the Fort St. Vrain reactor were between 8 and 25 percent of the total reactor mass flow rate. If bypass flow rates are on the

Study on applicability of highly corrosion-resistant amorphous coating techniques to components of reprocessing plant

International Nuclear Information System (INIS)

Ebata, Makoto; Okuyama, Gen; Chiba, Shigeru; Matsunaga, Tsunebumi

1991-01-01

In view of the growing need for prolongation of lives of reprocessing plant installations, we recently investigated the applicability of highly corrosion-resistant amorphous coating techniques to such plant components as to be subjected to a badly corrosive environment created by high temperatures, boiling nitric acid (HNO 3 ), etc. As the result, giving a preference to the Ta-based amorphous alloys exhibiting high corrosion-resistance in HNO 3 solutions, we made specimens of stainless steel plates coated with the above amorphous alloys through the sputtering process thereof. To our satisfaction, these specimens successfully passed various HNO 3 corrosion tests as described later on. Ta-based amorphous films give cathodic protection to 310 Nb stainless steel plates, and that with extremely low corrosion rates of themselves as protecting agents. For these reasons, we are confident that there will be no practical problems at all, in case we adopt stainless steel plates partially coated with such amorphous alloys for use in a nitric-acid environment. In this paper, we explain the comparative tests for various amorphous alloys with different compositions, referring also to the thus-selected Ta-based amorphous alloy along with several kinds of corrosion tests specially arranged for the same alloy. (author)

Stress corrosion cracking of 316 SS and Incoloy-800 in high temperature aqueous containing sulfate and chloride

International Nuclear Information System (INIS)

Zhang Weiguo; Lin Fangliang; Gao Fengqin; Zhou Hongyi; Cao Xiaoning

1992-03-01

The stress corrosion cracking (SCC) susceptibility of 316 stainless steel (SS) which was welded for primary pipe and Incoloy-800 (shot peening) for steam generator (SG) tube have been investigated by a slow strain rate test (SSRT) at a strain rate of 4.2 x 10 -6 /s. Tests were conducted at 315 C degree for 316 SS and 270 C degree for In-800 in the oxygenated simulated resin intrusion environment (acidic sulfate). Tests of the effect of combination of SO 4 2- and Cl - on SCC of Incoloy-800 were also carried out. The results indicate that Incoloy-800 is unsusceptible to SCC either in the environment with SO 4 2- (from a few ppm to 1000 ppm, pH 3 ∼ 4) or in the environment of combination of SO 4 2- (1000 ppm) and Cl - (from 2 to 1000 ppm). The 316 NG SS is susceptible to transgranular stress corrosion cracking (TGSCC) in the resin intrusion environment with SO 4 2- in high temperature water

Iron-niobium-aluminum alloy having high-temperature corrosion resistance

Science.gov (United States)

Hsu, Huey S.

1988-04-14

An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

Monitoring of corrosion damage using high-frequency guided ultrasonic waves

Science.gov (United States)

Chew, D.; Fromme, P.