Reduction of hydrocarbon impurities in 200 L/H helium liquefier-refrigerator system

International Nuclear Information System (INIS)

Yamada, Shuichi; Mito, Toshiyuki; Nishimura, Arata

1993-11-01

A cryogenic system with the capacity of 200 1/h or 500 W at 4.4 K has been operated to develop the superconducting conductors and coils for the LHD. The system has contributed in various superconducting technologies along with the dc 75kA power supply and 10 MN mechanical testing machine, and completed the basic R and D works of the LHD. On the way of operating the cryogenic system, impurity densities of hydrocarbon gases in circulating helium gas became much larger than the expected values for this cryogenic system, so that the densities of some impurity gases were carefully monitored in reference to the operational conditions of circulating compressor by using a gas chromatography. Impurity gas densities of oxygen, nitrogen and ethane increased obviously, when the output capacity of the compressor was reduced. In a two-stage oil injected compression system with a variable stroke mechanism for a first stage, a reduction in the capacity of the first stage leads to a larger compression ratio for the second stage, and the temperature of the injected oil becomes higher. The production of the impurities in the helium might be caused by cracking a part of injected oil in the compressor. The compressor, therefore, was reconstructed such that the injection oil is supplied sufficiently and the compression ratio division becomes even for each stage. It was confirmed that the impurities are not produced now after modification. (author)

Creep properties of superalloys for the HTGR in impure helium environments

International Nuclear Information System (INIS)

Kawakami, H.; Nakanishi, T.

1981-01-01

This paper describes creep behaviors of two heat resistant alloys, Hastelloy X and Incoloy 800, in helium environments of the HTGR. In impure helium environments, these alloys are susceptible to carburization and oxidization. We have investigated these effects separately, and related them to the creep behaviors of the alloys. Experiments were carried out at 900 0 C both in helium and in air. Carburization results in decrease of secondary creep strain rate and delay of tertiary creep initiation. Oxidization caused decrease in tertiary creep strain rate of Hastelloy X, but did not that of Incoloy 800. Enhancement in tertiary creep strain rate of Hastelloy X in a very weakly oxidizing environment was confirmed in creep crack growth experiment using notched plate specimens. The rupture time of Hastelloy X in helium was short when compared with in air. Stress versus rupture time curves for both environments were parallel up to 5000 hours test, and a ratio of rupture stress in helium to that in air was about 0.9. In case of Incoloy 800, rupture time in helium was markedly prolonged as compared with that in air. (orig.)

Control of oxygen impurity and hydrogen recycling in the compact helical system (CHS)

International Nuclear Information System (INIS)

Noda, N.; Okamura, S.; Aoki, T.; Yamada, H.; Tsuzuki, K.; Matsuoka, K.; Iguchi, H.; Hosokawa, M.; Kaneko, O.; Kubo, S.; Morita, S.; Nishimura, K.; Sagara, A.; Shoji, T.; Takahashi, C.; Takeiri, Y.; Takita, Y.; Amemiya, H.; Okazaki, K.; Oyama, Y.; Shimizu, K.; Yano, K.

1990-01-01

In order to reduce oxygen impurity and hydrogen recycling, ECR discharge cleaning with hydrogen, glow discharge with helium, and titanium gettering have been applied. The ECR discharge cleaning was found to be effective in reducing oxygen impurities in ECRH discharges. However, it was not sufficiently effective to give a wide operational density range in NBI heated discharges. Titanium gettering is essential for this purpose, and controllable discharges have been achieved in the density range 1-10x10 19 m -3 , with discharge length more than 850 ms with the aid of titanium gettering. Both helium-glow discharge and Ti gettering are useful to control hydrogen recycling even with a stainless steel wall. (orig.)

Effects of a range of machined and ground surface finishes on the simulated reactor helium corrosion of several candidate structural materials

International Nuclear Information System (INIS)

Thompson, L.D.

1981-02-01

This report discusses the corrosion behavior of several candidate reactor structural alloys in a simulated advanced high-temperature gas-cooled reactor (HTGR) environment over a range of lathe-machined and centerless-ground surface finishes. The helium environment contained 50 Pa H 2 /5 Pa CO/5 Pa CH 4 / 2 O (500 μatm H 2 /50 μatm CO/50 μatm CH 4 / 2 O) at 900 0 C for a total exposure of 3000 h. The test alloys included two vacuum-cast superalloys (IN 100 and IN 713LC); a centrifugally cast austenitic alloy (HK 40); three wrought high-temperature alloys (Alloy 800H, Hastelloy X, and Inconel 617); and a nickel-base oxide-dispersion-strengthened alloy (Inconel MA 754). Surface finish variations did not affect the simulated advanced-HTGR corrosion behavior of these materials. Under these conditions, the availability of reactant gaseous impurities controls the kinetics of the observed gas-metal interactions. Variations in the near-surface activities and mobilities of reactive solute elements, such as chromium, which might be expected to be affected by changes in surface finish, do not seem to greatly influence corrosion in this simulated advanced HTGR environment. 18 figures, 4 tables

Corrosion behavior of pyroclore-rich titanate ceramics for plutonium disposition; impurity effects

International Nuclear Information System (INIS)

Bakel, A. J.

1999-01-01

The baseline ceramic contains Ti, U, Ca, Hf, Gd, and Ce, and is made up of only four phases, pyrochlore, zirconolite, rutile, and brannerite. The impurities present in the three other ceramics represent impurities expected in the feed, and result in different phase distributions. The results from 3 day, 90 C MCC-1 tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics alters the phase distributions, which in turn, affects the corrosion behavior

Influence of impurities and ion surface alloying on the corrosion resistance of E110 alloy

International Nuclear Information System (INIS)

Kalin, B. A.; Volkov, N. V.; Valikov, R. A.; Novikov, V. V.; Markelov, V. A.; Pimenov, Yu. V.

2013-01-01

The corrosion resistance of zirconium alloys depends on their structural-phase state, the type of core coolant and operating factors. The formation of a protective oxide film on the zirconium alloys is sensitive to the content of impurity atoms present in the charge base of alloys and accumulating in them in the manufacture of products. The impurity composition of the initial zirconium is determined by the method of its manufacture and generally remains unchanged in the products, deter-mining their properties, including their corrosion resistance. An increased content of impurities (C, N, Al, Mo, Fe) both individually and in their combination negatively affects the corrosion resistance of zirconium and its alloys. One of the potentially effective methods to increase the protective properties of oxide films on zirconium alloys is a surface alloying using the regime of mixing the atoms of a film, preliminarily coated on the surface, and the atoms of a target. This method makes it possible to form a given structural-phase state in the thin surface layer with unique physicochemical properties and thus to in-crease the corrosion resistance and wear resistance of fuel claddings. In this context, the object of investigation was samples of cladding tubes from alloy E110 with various content of impurity elements (nitrogen, aluminum, and carbon) with the aim to reduce the negative influence of impurities on the corrosion resistance by changing the structural-phase state of the surface layer of fuel claddings and fuel assembly components with alloying in the regime of ion mixing of atoms

Corrosion of pipe steel in CO2 containing impurities and possible solutions

NARCIS (Netherlands)

Zhang, X.; Zevenbergen, J.F.; Spruijt, M.P.N.; Borys, M.

2013-01-01

CO2 flue gases acquired from different sources contain a significant amount of impurities and water, which are corrosive to the pipeline steel. To design the pipelines for large scale of CO2 flue gas transport, the corrosion of pipeline steels has to be investigated in the realistic conditions. In

Novel sound phenomena in superfluid helium in aerogel and other impure superfluids

International Nuclear Information System (INIS)

Brusov, Peter; Brusov, Paul; Lawes, Gavin; Lee, Chong; Matsubara, Akira; Ishikawa, Osamu; Majumdar, Pinaki

2003-01-01

During the last decade new techniques for producing impure superfluids with unique properties have been developed. This new class of systems includes superfluid helium confined to aerogel, HeII with different impurities (D 2 , N 2 , Ne, Kr), superfluids in Vycor glasses, and watergel. These systems exhibit very unusual properties including unexpected acoustic features. We discuss the sound properties of these systems and show that sound phenomena in impure superfluids are modified from those in pure superfluids. We calculate the coupling between temperature and pressure oscillations for impure superfluids and for superfluid He in aerogel. We show that the coupling between these two sound modes is governed either by c∂ρ/∂c or σρ a ρ s (for aerogel) rather than thermal expansion coefficient ∂ρ/∂T, which is enormously small in pure superfluids. This replacement plays a fundamental role in all sound phenomena in impure superfluids. It enhances the coupling between the two sound modes that leads to the existence of such phenomena as the slow mode and heat pulse propagation with the velocity of first sound observed in superfluids in aerogel. This means that it is possible to observe in impure superfluids such unusual sound phenomena as slow pressure (density) waves and fast temperature (entropy) waves. The enhancement of the coupling between the two sound modes decreases the threshold values for nonlinear processes as compared to pure superfluids. Sound conversion, which has been observed in pure superfluids only by shock waves should be observed at moderate sound amplitude in impure superfluids. Cerenkov emission of second sound by first sound (which never been observed in pure superfluids) could be observed in impure superfluids

Stress corrosion cracking of U-0.1% Cr in humid helium atmosphere

International Nuclear Information System (INIS)

Zalkind, S.; Eshkenazy, R.; Harush, S.; Halperin, D.; Moreno, D.; Abramov, E.; Venkert, A.

1994-01-01

Rivets were matched into adapted drilled holes in plates, both made of U-0.1% Cr alloy and were placed in different environments containing dry air and helium and humid air and helium for a variety of exposure times. After opening, the most significant amounts of corrosion products were detected in the specimens that stayed for three years in humid helium (5% RH) environment. Radial cracks, developed in the bore edge, were detected in the specimens. X-ray diffraction patterns of the corrosion products gave the composition of UH 3 and UO 2 . The microstructure was examined using light and electron microscopy techniques. The hydride phase that was observed, formed mainly beneath the oxide layer and penetrated into the metal matrix as needle-like forms. The formation of a lower density hydride phase, yielded in a large volume change causing the development of high stresses at the rivet-bore interface. The combination of the high stress and the weakening of the bore edge due to the presence of the brittle hydride phase led to radial crack formation around the bore edge. (orig.)

Steady-state tokamak reactor with non-divertor impurity control: STARFIRE

International Nuclear Information System (INIS)

Baker, C.C.

1980-01-01

STARFIRE is a conceptual design study of a commercial tokamak fusion electric power plant. Particular emphasis has been placed on simplifying the reactor concept by developing design concepts to produce a steady-state tokamak with non-divertor impurity control and helium ash removal. The concepts of plasma current drive using lower hybrid rf waves and a limiter/vacuum system for reactor applications are described

Corrosion and alteration of materials from the nuclear industry; La Corrosion et l'alteration des materiaux du nucleaire

Energy Technology Data Exchange (ETDEWEB)

Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Feron, D.; Guerin, Y.; Latge, C.; Limoge, Y.; Madic, C.; Santarini, G.; Seiler, J.M.; Vernaz, E.; Richet, C.

2010-07-01

The control of the corrosion phenomenon is of prime importance for the nuclear industry. The efficiency and the safety of facilities can be affected by this phenomenon. The nuclear industry has to face corrosion for a large variety of materials submitted to various environments. Metallic corrosion operates in the hot and aqueous environment of water reactors which represent the most common reactor type in the world. Progresses made in the control of the corrosion of the different components of these reactors allow to improve their safety. Corrosion is present in the facilities of the back-end of the fuel cycle as well (corrosion in acid environment in fuel reprocessing plants, corrosion of waste containers in disposal and storage facilities, etc). The future nuclear systems will widen even more the range of materials to be studied and the situations in which they will be placed (corrosion by liquid metals or by helium impurities). Very often, corrosion looks like a patchwork of particular cases in its description. The encountered corrosion problems and their study are presented in this book according to chapters representing the main sectors of the nuclear industry and classified with respect to their phenomenology. This monograph illustrates the researches in progress and presents some results of particular importance obtained recently. Content: 1 - Introduction: context, stakes and goals; definition of corrosion; a complex science; corrosion in the nuclear industry; 2 - corrosion in water reactors - phenomenology, mechanisms, remedies: A - uniform corrosion: mechanisms, uniform corrosion of fuel cladding, in-situ measurement of generalized corrosion rate by electrochemical methods, uniform corrosion of nickel alloys, characterization of the passive layer and growth mechanisms, the PACTOLE code - an integrating tool, influence of water chemistry on corrosion and contamination, radiolysis impact on uniform corrosion; B - stress corrosion: stress corrosion cracking

Effect of impurity elements Al, Mn, and N2 on the corrosion resistance of zircaloy-2 in high temperature water and steam

International Nuclear Information System (INIS)

Gadiyar, H.S.

1978-01-01

Although the impurity limits are specified in standard zircaloy-2, it is possible that during its manufacture some of the impurities may exceed by a few ppm than the normally set values. It is necessary to understand the corrosion behaviour of such zircaloy-2 which contain a small amount of excessive impurities. This report summarizes some such data of the impurities aluminium, manganese and nitrogen. It is seen that the common impurities which can affect the corrosion of zircaloy-2 significantly are Al and N 2 and to a lesser extent Mn. (author)

Oxygen control systems and impurity purification in LBE: Learning from DEMETRA project

Energy Technology Data Exchange (ETDEWEB)

Brissonneau, L., E-mail: laurent.brissonneau@cea.fr [CEA/DEN, Cadarache, DTN/STPA/LIPC, F-13108 Saint-Paul-lez-Durance (France); Beauchamp, F.; Morier, O. [CEA/DEN, Cadarache, DTN/STPA/LIPC, F-13108 Saint-Paul-lez-Durance (France); Schroer, C.; Konys, J. [Karlsruher Institut fuer Technologie (KIT), Institut fuer Materialforschung III, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Kobzova, A.; Di Gabriele, F. [NRI, UJV Husinec-Rez 130, Rez 25068 (Czech Republic); Courouau, J.-L. [CEA/DEN, Saclay, DPC/SCCME/LECNA, F-919191 Gif-sur-Yvette (France)

2011-08-31

Operating a system using Lead-Bismuth Eutectic (LBE) requires a control of the dissolved oxygen concentration to avoid corrosion of structural materials and oxide build-up in the coolant. Reliable devices are therefore needed to monitor and adjust the oxygen concentration and to remove impurities during operation. In this article, we describe the learning gained from experiments run in the framework of the DEMETRA project (IP-EUROTRANS 6th FP contract) on the oxygen supply in LBE and on impurity filtration and management in different European facilities. An oxygen control device should supply oxygen in LBE at sufficient rate to compensate loss by surface oxidation, otherwise local dissolution of oxide layers might lead to the loss of steel protection against dissolution. Oxygen can be supplied by gas phase H{sub 2}O or O{sub 2}, or by solid phase, PbO dissolution. Each of these systems has substantial advantages and drawbacks. Considerations are given on devices for large scale facilities. The management of impurities (lead oxides and corrosion products) is also a crucial issue as their presence in the liquid phase or in the aerosols is likely to impair the facility, instrumentation and mechanical devices. To avoid impurity build-up on the long-term, purification of LBE is required to keep the impurity inventory low by trapping oxide and metallic impurities in specific filter units. On the basis of impurities characterisation and experimental results gained through filtration tests in different loops, this paper gives a description of the state-of-art knowledge of LBE purification with different filter media. It is now understood that the nature and behaviour of impurities formed in LBE will change according to the operating modes as well as the method to propose to remove impurities. This experience can be used to validate the basis filtration process, define the operating procedures and evaluate perspectives for the design of purification units for long

Corrosion and alteration of materials from the nuclear industry

International Nuclear Information System (INIS)

Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Feron, D.; Guerin, Y.; Latge, C.; Limoge, Y.; Madic, C.; Santarini, G.; Seiler, J.M.; Vernaz, E.; Richet, C.

2010-01-01

The control of the corrosion phenomenon is of prime importance for the nuclear industry. The efficiency and the safety of facilities can be affected by this phenomenon. The nuclear industry has to face corrosion for a large variety of materials submitted to various environments. Metallic corrosion operates in the hot and aqueous environment of water reactors which represent the most common reactor type in the world. Progresses made in the control of the corrosion of the different components of these reactors allow to improve their safety. Corrosion is present in the facilities of the back-end of the fuel cycle as well (corrosion in acid environment in fuel reprocessing plants, corrosion of waste containers in disposal and storage facilities, etc). The future nuclear systems will widen even more the range of materials to be studied and the situations in which they will be placed (corrosion by liquid metals or by helium impurities). Very often, corrosion looks like a patchwork of particular cases in its description. The encountered corrosion problems and their study are presented in this book according to chapters representing the main sectors of the nuclear industry and classified with respect to their phenomenology. This monograph illustrates the researches in progress and presents some results of particular importance obtained recently. Content: 1 - Introduction: context, stakes and goals; definition of corrosion; a complex science; corrosion in the nuclear industry; 2 - corrosion in water reactors - phenomenology, mechanisms, remedies: A - uniform corrosion: mechanisms, uniform corrosion of fuel cladding, in-situ measurement of generalized corrosion rate by electrochemical methods, uniform corrosion of nickel alloys, characterization of the passive layer and growth mechanisms, the PACTOLE code - an integrating tool, influence of water chemistry on corrosion and contamination, radiolysis impact on uniform corrosion; B - stress corrosion: stress corrosion cracking

Trace impurity analyzer

International Nuclear Information System (INIS)

Schneider, W.J.; Edwards, D. Jr.

1979-01-01

The desirability for long-term reliability of large scale helium refrigerator systems used on superconducting accelerator magnets has necessitated detection of impurities to levels of a few ppM. An analyzer that measures trace impurity levels of condensable contaminants in concentrations of less than a ppM in 15 atm of He is described. The instrument makes use of the desorption temperature at an indicated pressure of the various impurities to determine the type of contaminant. The pressure rise at that temperature yields a measure of the contaminant level of the impurity. A LN 2 cryogenic charcoal trap is also employed to measure air impurities (nitrogen and oxygen) to obtain the full range of contaminant possibilities. The results of this detector which will be in use on the research and development helium refrigerator of the ISABELLE First-Cell is described

Effects of alloys elements, impurities and microstructural factors in austenitic stainless steel to utilize in fuel rod of nuclear reactors

International Nuclear Information System (INIS)

Yoshimoto, A.

1988-08-01

Austenitic Stainless Steel is used as cladding material of pressurized water reactor fuel rods because of its good performance. The addition of alloy elements and the control of impurities make this to happen. Fission products do not contribute to corrosion. Dimensional changes are not critical up to 1,0 x 10 22 n/cm 2 (E>0,1 MeV) of neutronic doses. The hydrogen does not cause embrittlement in the reactor operation temperatures, and helium contributes to embrittlement if the material is warmed upon 650 0 C. (author) [pt

Particle control in DIII-D with helium glow discharge conditioning

International Nuclear Information System (INIS)

Jackson, G.L.; Taylor, T.S.; Taylor, P.L.

1990-01-01

Helium glow discharge conditioning of DIII-D is routinely used before every tokamak discharge to desorb hydrogen from the graphite tiles, which are the plasma facing surfaces for the floor, inner wall and top of the vessel. In addition to reducing hydrogen fuelling of the plasma by the graphite surfaces, helium glow discharges are also effective in removing low-Z impurities, primarily in the form of carbon monoxide and hydrocarbons, and this has permitted higher current divertor operation and more rapid recovery from tokamak disruptions. Since the implementation of repetitive helium glow wall conditioning, the parameter space in which tokamak discharges in DIII-D can be obtained has been expanded to include the first observations of limiter H-mode confinement, the Ohmic H-mode with periods of up to 150 ms that are free of edge localized modes, more reliable low q operation with volume averaged beta of up to 9.3%, improved control over locked modes and plasma discharges at lower electron density. (author). 37 refs, 12 figs, 1 tab

On the improvement of HTGR fuel elements corrosion resistance

International Nuclear Information System (INIS)

Chernikov, A.S.; Kurbakov, S.D.

1996-01-01

The results of corrosion tests of matrix graphite based on calcinated (30PG graphite) and non-calcinated (MPG graphite) petroleum cokes in helium containing 0.01-1 vol.% water vapour in the temperature range 600-1200degC are presented. The results of investigation of matrix graphite components reactivity are considered. It is shown that the filler graphite 30PG has the minimum activity towards the water vapour. The influence of impurities content on the oxidation rate are considered. The results of corrosion tests of matrix graphite coated with protective layers (silicon carbide and aluminium phosphates) in the air environment at 1600degC, 1 h, are given. (author)

Material compatibility and corrosion control of the KWU chemical cleaning process

International Nuclear Information System (INIS)

Odar, S.

1994-01-01

The concentrations of salt impurities within the deposits on the tube sheet and in the tube to tube-support-plate crevices can induce a variety of corrosion mechanisms on steam generator tubes. One of the most effective ways of counteracting corrosion mechanisms and thus of improving steam generator performance is to clean the steam generators and keep them in a clean condition. As shown by field results chemical cleaning is a way of removing hazardous deposits from steam generators. All available chemical cleaning processes use inhibitors to control the corrosion except the KWU chemical cleaning process. In this article the corrosion control technique of KWU Chemical Cleaning Process without using conventional inhibitors will be explained and the state of the field experience with respect to material compatibility will be presented. (author). 4 figs., 1 tab., 8 refs

High-temperature helium-loop facility

International Nuclear Information System (INIS)

Tokarz, R.D.

1981-09-01

The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100 0 F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system. The experimental capabilities and test conand presents the results that have been obtained. The study has been conducted using a four-phase approach. The first phase develops the solution to the steady-state radon-diffusion equation in one-dimensieered barriers; disposal charge analysis; analysis of spent fuel policy implementation; spent f water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Uranium concentrations in the sediments which were above detection limits ranged from 0.10 t 51.2 ppM. The mean of the logarithms of the uranium concentrations was 0.53. A group of high uranium concentrations occurs near the junctions of quadrangles AB, AC, BB, a 200 mK. In case 2), x-ray studies of isotopic phase separation in 3 He-- 4 He bcc solids were carried out by B. A. Fraass

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

Low-cycle fatigue of heat-resistant alloys in high-temperature gas-cooled reactor helium

International Nuclear Information System (INIS)

Tsuji, H.; Kondo, T.

1984-01-01

Strain controlled low-cycle fatigue tests were conducted on four nickel-base heat-resistant alloys at 900 0 C in simulated high-temperature gas-cooled reactor (HTGR) environments and high vacuums of about 10 -6 Pa. The observed behaviors of the materials were different and divided into two groups when tests were made in simulated HTGR helium, while all materials behaved similarly in vacuums. The materials that have relatively high ductility and compatibility with impure helium at test temperature showed considerable resistance to the fatigue damage in impure helium. On the other hand, the alloys qualified with their high creep strength were seen to suffer from the adverse effects of impure helium and the trend of intergranular cracking as well. The results were analyzed in terms of their susceptibility to the environmentenhanced fatigue damage by examining the ratios of the performance in impure helium to in vacuum. The materials that showed rather unsatisfactory resistance were considered to be characterized by their limited ductility partly due to their coarse grain structure and susceptibility to intergranular oxidation. Moderate carburization was commonly noted in all materials, particularly at the cracked portions, indicating that carbon intrusion had occurred during the crack growth stage

Evaluation of materials for heat exchanging components in advanced helium-cooled reactors

International Nuclear Information System (INIS)

Schubert, F.

1984-01-01

The qualification of metallic materials for advanced HTR applications is based on creep behaviour, fatigue properties, structural stability and corrosion resistance. A brief state of the art is provided for the materials for heat exchanging components. The experimental results are treated with respect to the importance for the design, the characteristic of time-depend materials behaviour are evaluated. Of specific interest are the possible effects of helium on the mechanical properties. Helium, which serves as primary coolant, contains traces of reactive impurities such as hydrogen, methane, carbon monoxide and water vapor. The evaluation of the HTR materials program serves as basis for structural design rules of components with operation temperatures above 800 deg C. The materials mechanical topics are discussed. Alloy improvement and the progress in development of new alloys are reviewed. (author)

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

Dictionary corrosion and corrosion control

International Nuclear Information System (INIS)

1985-01-01

This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods. (orig./HP) [de

Effect of carburizing helium environment on creep behavior of Ni-base heat-resistant alloys for high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

Kurata, Yuji; Ogawa, Yutaka; Nakajima, Hajime

1988-01-01

Creep tests were conducted on Ni-base heat-resistant alloys Hastelloy XR and XR-II, i.e. versions of Hastelloy X modified for nuclear applications, at 950degC using four types of helium environment with different impurity compositions, and mainly the effect of carburization was examined. For all the materials tested, the values of creep rupture time obtained under the carburizing conditions were similar to or longer than those in the commonly used, standard test environment (JAERI Type B helium). The difference among the results was interpreted by the counterbalancing effects of the strengthening due to carburization and possible weakening caused under very low oxidizing potential. In the corrosion monitoring specimens pronounced carbon pick-up was observed in the environment with high carbon activity and very low oxidizing potential. Based on the results obtained in the present and the previous works, it is suggested that a moderate control of the impurity chemistry is important rather than simple purification of the coolant in protecting the material from the environment-enhanced degradation. Either condition with high or low extremes in the oxidizing and carburizing potentials may cause enhanced degradation and thus are desirable to be avoided at the elevated temperatures. (author)

Phase transition of DNA-linked gold nanoparticles: Creation of a high concentration of atomic hydrogen in impurity-helium solids

International Nuclear Information System (INIS)

Kiselev, S.I.; Khmelenko, V.V.; Bernard, E.P.; Lee, C.Y.; Lee, D.M.

2003-01-01

The exchange tunneling reactions D+H 2 →HD+H and D+HD→D 2 +H were used to generate high concentrations of atomic hydrogen in impurity-helium solids. The dependence of atom concentration on the content of hydrogen in the injected gas mixture gave a maximum concentration of 7.5x10 17 cm -3 hydrogen atoms for an initial gas ratio H 2 :D 2 :He=1:4:100

Impurity production and transport at limiters

International Nuclear Information System (INIS)

Matthews, G.F.

1989-01-01

This paper concentrates on the description and evaluation of experiments on the DITE tokamak. These are designed to characterise the processes involved in the production and transport of neutral and ionised impurities near carbon limiters. The need for good diagnostics in the scrape-off layer is highlighted. Langmuir probes are used to provide input data for models of impurity production at limiters. Observations of the radial profiles of carbon and oxygen impurities are compared with the code predictions. Changeover experiments involving hydrogen and helium plasmas are used as a means for investigating the role of the atomic physics and chemistry. The impurity control limiter (ICL) experiment is described which shows how geometry plays an important role in determining the spatial distributions of the neutral and ionised carbon. New diagnostics are required to study the flux and charge state distribution of impurities in the boundary. Preliminary results from an in-situ plasma ion mass-spectrometer are presented. The role of oxygen and the importance of evaluating the wall sources of impurity are emphasised. (orig.)

New water guidelines developed to battle nuclear corrosion

International Nuclear Information System (INIS)

Strauss, S.D.

1983-01-01

Discusses methods of preventing degradation of nuclear steam generators due to a combination of impurities and corrosion products in the secondary system. Explains that tube and support-plate corrosion has been the main concern, manifesting itself primarily in the recirculating units used in PWR systems. Points out that the battle against corrosion is closely linked to control of ionic impurities, alkalinity, oxidants, and sludge-copper and iron corrosion products, primarily-in condensate and feedwater systems. Examines a set of secondary-water-chemistry guidelines developed by the Steam Generator Owners Group (SGOG). Presents diagram showing changes at Salem 1 to arrest corrosion, including condenser retubing, addition of condensate polisher and recirculation loop. Table indicates how preventive measures at Salem 1, affected secondary-water chemistry

Automated-process gas-chromatograph system for use in accelerated corrosion testing of HTGR core-support posts

International Nuclear Information System (INIS)

Harper, R.E.; Herndon, P.G.

1982-01-01

An automated-process gas chromatograph is the heart of a gaseous-impurities-analysis system developed for the Oak Ridge National Laboratory Core Support Performance Test, at which graphite core-support posts for high-temperature gas-cooled fission reactors are being subjected to accelerated corrosion tests under tightly controlled conditions of atmosphere and temperature. Realistic estimation of in-core corrosion rates is critically dependent upon the accurate measurement of low concentrations of CO, CO 2 , CH 4 , H 2 , and O 2 in the predominantly helium atmosphere. In addition, the capital and labor investment associated with each test puts a premium upon the reliability of the analytical system, as excessive downtime or failure to obtain accurate data would result in unacceptable costs and schedule delays. After an extensive survey of available measurement techniques, gas chromatography was chosen for reasons of accuracy, flexibility, good-performance record, and cost

Corrosion and corrosion control

International Nuclear Information System (INIS)

Khanna, A.S.; Totlani, M.K.

1995-01-01

Corrosion has always been associated with structures, plants, installations and equipment exposed to aggressive environments. It effects economy, safety and product reliability. Monitoring of component corrosion has thus become an essential requirement for the plant health and safety. Protection methods such as appropriate coatings, cathodic protection and use of inhibitors have become essential design parameters. High temperature corrosion, especially hot corrosion, is still a difficult concept to accommodate in corrosion allowance; there is a lack of harmonized system of performance testing of materials at high temperatures. In order to discuss and deliberate on these aspects, National Association for Corrosion Engineers International organised a National Conference on Corrosion and its Control in Bombay during November 28-30, 1995. This volume contains papers presented at the symposium. Paper relevant to INIS is indexed separately. refs., figs., tabs

Measuring and controlling method for organic impurities

International Nuclear Information System (INIS)

Aizawa, Motohiro; Igarashi, Hiroo

1995-01-01

The present invention concerns measurement and control for organic impurities contained in ultrapurified water for use in a nuclear power plant. A specimen containing organic impurities leached out of anionic exchange resins and cationic exchange resins is introduced to an organic material decomposing section to decompose organic impurities into organic carbon and other decomposed products. Sulfate ions, nitrate ions, nitrite ions and carbon dioxide are produced by the decomposition of the organic impurities. As a next step, carbon dioxide in the decomposed products is separated by deaerating with a nitrogen gas or an argon gas and then a TOC concentration is measured by a non-dispersion-type infrared spectrometer. Further, a specimen from which carbon dioxide was separated is introduced to a column filled with ion exchange resins and, after concentrating inorganic ion impurities, the inorganic ion impurities are identified by using a measuring theory of an ion chromatographic method of eluting and separating inorganic ion impurities and detecting them based on the change of electroconductivity depending on the kinds of the inorganic ion impurities. Organic impurities can be measured and controlled, to improve the reliability of water quality control. (N.H.)

Device for removing impurities from liquid metals

International Nuclear Information System (INIS)

Naito, Kesahiro; Yokota, Norikatsu; Shimoyashiki, Shigehiro; Takahashi, Kazuo; Ishida, Tomio.

1984-01-01

Purpose: To attain highly reliable and efficient impurity removal by forming temperature distribution the impurity removing device thereby providing the function of corrosion product trap, nuclear fission product trap and cold trap under the conditions suitable to the impurity removing materials. Constitution: The impurity removing device comprises a container containing impurity removing fillers. The fillers comprise material for removing corrosion products, material for removing nuclear fission products and material for removing depositions from liquid sodium. The positions for the respective materials are determined such that the materials are placed under the temperature conditions easy to attain their function depending on the temperature distribution formed in the removing device, whereby appropriate temperature condition is set to each of the materials. (Yoshino, Y.)

Influence of impurities on the fuel retention in fusion reactors

International Nuclear Information System (INIS)

Reinhart, Michael

2015-01-01

The topic of this thesis is the influence of plasma impurities on the hydrogen retention in metals, in the scope of plasma-wall-interaction research for fusion reactors. This is addressed experimentally and by modelling. The mechanisms of the hydrogen retention are influenced by various parameters like the wall temperature, ion energy, flux and fluence as well as the plasma composition. The plasma composition is a relevant factor for hydrogen retention in fusion reactors, as their plasma will also contain impurities like helium or seeded impurities like argon. The experiments treated in this thesis were performed in the linear plasma generator PSI-2 at Forschungszentrum Juelich, and are divided in 3 parts: The first experiments cover the plasma diagnostics, most importantly the measurement of the impurity ion concentration in the plasma by optical emission spectroscopy. This is a requirement for the later experiments with mixed plasmas. Diagnostics like Langmuir probe measurements are not applicable for this task because they do not distinguish different ionic species. The results also show that the impurity ion concentrations cannot be simply concluded from the neutral gas input to the plasma source, because the relation between the neutral gas concentration and impurity ion concentration is not linear. The second and main part of the experiments covers the exposure of tungsten samples to deuterium plasmas. In the experiments, the impurity ion type and concentration is variated, to verify the general influence of helium and argon on the deuterium retention in tungsten samples exposed at low temperatures. It shows that helium impurities reduce the amount of retained deuterium by a factor of 3, while argon impurities slightly increase the total retention, compared to exposures to a pure deuterium plasma. Cross-sections of the exposed tungsten surfaces via TEM-imaging reveal a 12-15 nm deep helium nanobubble layer at the surface of the sample, while for the cases of

Influence of impurities on the fuel retention in fusion reactors

Energy Technology Data Exchange (ETDEWEB)

Reinhart, Michael

2015-07-01

The topic of this thesis is the influence of plasma impurities on the hydrogen retention in metals, in the scope of plasma-wall-interaction research for fusion reactors. This is addressed experimentally and by modelling. The mechanisms of the hydrogen retention are influenced by various parameters like the wall temperature, ion energy, flux and fluence as well as the plasma composition. The plasma composition is a relevant factor for hydrogen retention in fusion reactors, as their plasma will also contain impurities like helium or seeded impurities like argon. The experiments treated in this thesis were performed in the linear plasma generator PSI-2 at Forschungszentrum Juelich, and are divided in 3 parts: The first experiments cover the plasma diagnostics, most importantly the measurement of the impurity ion concentration in the plasma by optical emission spectroscopy. This is a requirement for the later experiments with mixed plasmas. Diagnostics like Langmuir probe measurements are not applicable for this task because they do not distinguish different ionic species. The results also show that the impurity ion concentrations cannot be simply concluded from the neutral gas input to the plasma source, because the relation between the neutral gas concentration and impurity ion concentration is not linear. The second and main part of the experiments covers the exposure of tungsten samples to deuterium plasmas. In the experiments, the impurity ion type and concentration is variated, to verify the general influence of helium and argon on the deuterium retention in tungsten samples exposed at low temperatures. It shows that helium impurities reduce the amount of retained deuterium by a factor of 3, while argon impurities slightly increase the total retention, compared to exposures to a pure deuterium plasma. Cross-sections of the exposed tungsten surfaces via TEM-imaging reveal a 12-15 nm deep helium nanobubble layer at the surface of the sample, while for the cases of

Effects of alloying and transmutation impurities on stability and mobility of helium in tungsten under a fusion environment

International Nuclear Information System (INIS)

Wu Xuebang; Kong Xiangshan; You Yuwei; Liu, C.S.; Fang, Q.F.; Chen Junling; Luo, G.-N.; Wang Zhiguang

2013-01-01

The behaviour of helium in metals is particularly significant in fusion research due to the He-induced degradation of materials. A small amount of impurities introduced either by intentional alloying or by transmutation reactions, will interact with He and lead the microstructure and mechanical properties of materials to change. In this paper, we present the results of first-principles calculations on the interactions of He with impurities and He diffusion around them in tungsten (W), including the interstitials Be, C, N, O, and substitutional solutes Re, Ta, Tc, Nb, V, Os, Ti, Si, Zr, Y and Sc. We find that the trapping radii of interstitial atoms on He are much larger than those of substitutional solutes. The binding energies between the substitutional impurities and He increase linearly with the relative charge densities at the He occupation site, indicating that He atoms easily aggregate at the low charge density site. The sequence of diffusion energy barriers of He around the possible alloying elements is Ti > V > Os > Ta > Re. The present results suggest that Ta might be chosen as a relatively suitable alloying element compared with other possible ones. (paper)

Effect of titanium impurities on helium bubble growth in nickel

International Nuclear Information System (INIS)

Amarendra, G.; Viswanathan, B.; Rajaraman, R.; Srinivasan, S.; Gopinathan, K.P.

1992-01-01

Positron lifetime measurements in He-implanted Ni and Ni-Ti alloys containing dilute concentrations of Ti, during isochronal annealing, are reported. In the initial annealing stage of Ni-Ti alloys, only a single lifetime ranging from 160 to 180 ps is observed, in contrast with the two lifetimes seen in pure Ni. This indicates saturation positron trapping at helium-bound Ti-vacancy complexes, formed in high concentrations. Lattice statics calculations of the He binding energy at various defect complexes in Ni-containing Ti give credence to the above interpretation. Above 800K, two lifetimes are resolved in Ni-Ti alloys, where the longer lifetime τ 2 increases with a sharp reduction in its intensity. This is indicative of He bubble growth. The bubble radius r B and bubble concentration C B are obtained from an analysis of positron lifetime parameters. These results indicate that, for a given annealing temperature, r B is smaller by a factor of two and C B higher by nearly an order of magnitude in Ni-Ti than the corresponding values in pure Ni. This is explained as due to significant retardation of bubble growth on the addition of Ti to Ni, where the Ti impurities cause an impediment to bubble migration and coalescence. (author)

Two-dimensional impurity transport calculations for a high recycling divertor

International Nuclear Information System (INIS)

Brooks, J.N.

1986-04-01

Two dimensional analysis of impurity transport in a high recycling divertor shows asymmetric particle fluxes to the divertor plate, low helium pumping efficiency, and high scrapeoff zone shielding for sputtered impurities

Control of molten salt corrosion of fusion structural materials by metallic beryllium

International Nuclear Information System (INIS)

Calderoni, P.; Sharpe, P.; Nishimura, H.; Terai, T.

2009-01-01

A series of tests have been performed between 2001 and 2006 at the Safety and Tritium Applied Research facility of the Idaho National Laboratory to demonstrate chemical compatibility between the molten salt flibe (2LiF + BeF 2 in moles) and fusion structural materials once suitable fluoride potential control methods are established. The tests adopted metallic beryllium contact as main fluoride potential control, and the results have been published in recent years. A further step was to expose two specimens of low activation ferritic/martensitic steel 9Cr-2W to static corrosion tests that include an active corrosion agent (hydrofluoric gas) in controlled conditions at 530 deg. C, and the results of the tests are presented in this paper. The results confirmed the expected correlation of the HF recovery with the concentration of metallic impurities dissolved in the salt because of specimen corrosion. The metals concentration dropped to levels close to the detectable limit when the beryllium rod was inserted and increased once the content of excess beryllium in the system had been consumed by HF reduction and specimen corrosion progressed. Metallographic analysis of the samples after 500 h exposure in reactive conditions showed evidence of the formation of unstable chromium oxide layers on the specimen's surface.

Operating Manual of Helium Refrigerator (Rev. 2)

Energy Technology Data Exchange (ETDEWEB)

Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

2002-07-01

A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

Tokamak impurity-control techniques

International Nuclear Information System (INIS)

Schmidt, J.A.

1980-01-01

A brief review is given of the impurity-control functions in tokamaks, their relative merits and disadvantages and some prominent edge-interaction-control techniques, and there is a discussion of a new proposal, the particle scraper, and its potential advantages. (author)

Effect of impurities and electrolyte thickness on degradation of pure magnesium: A finite element study

International Nuclear Information System (INIS)

Montoya, R.; Escudero, M.L.; García-Alonso, M.C.

2011-01-01

Highlights: ► Degradation of Mg due to the presence of impurities by finite element method. ► A thin film of electrolyte causes galvanic corrosion focused only close on impurities. ► A thick layer of electrolyte provokes galvanic corrosion extended the whole surface. ► A higher number of impurities causes galvanic corrosion on the Mg surface independently of electrolyte thickness. ► The electrolyte thickness is an important variable that affects the in vivo degradation. - Abstract: The aim of this work is to study the degradation of magnesium due to the presence of impurities, by finite element method (FEM), when different thickness of physiological medium bathes the surface. The electrochemical experimental data obtained from polarization curves are used to model mathematically the corrosion process by solving the Laplace equation and the proper boundary conditions by means of FEM. The results show that when Mg is covered by a thin film of electrolyte, galvanic corrosion is focused only on the areas located really close to the cathodic sites, and far from the impurities, the Mg matrix remains near to its corrosion potential with a natural corrosion process. However, if the Mg matrix is completely covered by a thick layer of electrolyte the potentials obtained in the Mg surface far from the impurity are higher than its corrosion potential, so the Mg suffers more severe galvanic corrosion. On the other hand, when a higher number of impurities is considered, the Mg matrix is anodically polarized and it suffers severe galvanic corrosion, independently of h. The thickness of the electrolyte h must be considered as an important variable that affects the in vivo degradation.

Friction and wear studies of graphite and a carbon-carbon composite in air and in helium

International Nuclear Information System (INIS)

Li, C.C.; Sheehan, J.E.

1980-10-01

Sliding friction and wear tests were conducted on a commercial isotropic graphite and a carbon-carbon composite in air, purified helium, and a helium environment containing controlled amounts of impurities simulating the primary coolant chemistry of a high-temperature gas-cooled reactor (HTGR). The friction and wear characteristics of the materials investigated were stable and were found to be very sensitive to the testing temperature. In general, friction and wear decreased with increasing temperature in the range from ambient to 950 0 C. This temperature dependence is concluded to be due to chemisorption of impurities to form lubricating films and oxidation at higher temperatures, which reduce friction and wear. Graphite and carbon-carbon composites are concluded to be favorable candidate materials for high-temperature sliding service in helium-cooled reactors

Erosion-corrosion of structural materials of wet steam turbines

International Nuclear Information System (INIS)

Tomarov, G.V.

1989-01-01

A model of erosion-corrosion wear of elements of a wet steam zone and a condensate-feeding path of turbines is considered. It is shown that diffusion of impurities and corrosion products in pores of an oxide layer is the control mechanism under conditions of laminar flow of a media. Processes of mass transfer are controlling factors in turbulent flow

Effect of impurities and electrolyte thickness on degradation of pure magnesium: A finite element study

Energy Technology Data Exchange (ETDEWEB)

Montoya, R., E-mail: rodrigo.montoya@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Departamento de Matematicas, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Departamento de Ingenieria Metalurgica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. Mexico (Mexico); Escudero, M.L., E-mail: escudero@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Garcia-Alonso, M.C., E-mail: crisga@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Degradation of Mg due to the presence of impurities by finite element method. Black-Right-Pointing-Pointer A thin film of electrolyte causes galvanic corrosion focused only close on impurities. Black-Right-Pointing-Pointer A thick layer of electrolyte provokes galvanic corrosion extended the whole surface. Black-Right-Pointing-Pointer A higher number of impurities causes galvanic corrosion on the Mg surface independently of electrolyte thickness. Black-Right-Pointing-Pointer The electrolyte thickness is an important variable that affects the in vivo degradation. - Abstract: The aim of this work is to study the degradation of magnesium due to the presence of impurities, by finite element method (FEM), when different thickness of physiological medium bathes the surface. The electrochemical experimental data obtained from polarization curves are used to model mathematically the corrosion process by solving the Laplace equation and the proper boundary conditions by means of FEM. The results show that when Mg is covered by a thin film of electrolyte, galvanic corrosion is focused only on the areas located really close to the cathodic sites, and far from the impurities, the Mg matrix remains near to its corrosion potential with a natural corrosion process. However, if the Mg matrix is completely covered by a thick layer of electrolyte the potentials obtained in the Mg surface far from the impurity are higher than its corrosion potential, so the Mg suffers more severe galvanic corrosion. On the other hand, when a higher number of impurities is considered, the Mg matrix is anodically polarized and it suffers severe galvanic corrosion, independently of h. The thickness of the electrolyte h must be considered as an important variable that affects the in vivo degradation.

Influence of impurities on the transition from minority to mode conversion heating in ({sup 3}He)-H)- plasmas

Energy Technology Data Exchange (ETDEWEB)

Kazakov, Ye. O. [LPP-ERM/KMS, Association EURATOM-Belgian State, Trilateral Euregio Cluster Partner, Brussels (Belgium); Fülöp, T. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Göteborg (Sweden); Van Eester, D. [LPP-ERM/KMS, Association ' EURATOM-Belgian State' , Trilateral Euregio Cluster Partner, Brussels (Belgium)

2014-02-12

Ion cyclotron resonance heating (ICRH) is one of the main auxiliary heating systems used in present-day tokamaks and is planned to be installed in ITER. In the initial full-field phase of ITER operating with hydrogen majority plasmas, fundamental resonance heating of helium-3 ions is one of a few ICRH schemes available. Past JET experiments with the carbon wall revealed a significant impact of impurities on the ICRH performance in ({sup 3}He)-H plasmas. A significant reduction of the helium-3 concentration, at which the transition from minority ion to mode conversion heating occurs, was found to be due to a high plasma contamination with carbon ions. In this paper we discuss the effect of Be and another impurity species present at JET after the installation of a new ITER-like wall on the transition helium-3 concentration in ({sup 3}He)-H plasmas. We suggest a potential method for controlling helium-3 level needed for a specific ICRH regime by puffing an extra helium-4 gas to the plasma.

The compatibility of candidate first wall metallic materials with impure helium

International Nuclear Information System (INIS)

Noda, T.; Okada, M.; Watanabe, R.

1979-01-01

The compatibilities of SUS 316 stainless steels, Nimonic PE 16, Nb-1% Zr, V-25% Mo, Mo, and TZM with the commercial grade helium (> 99.995%) and the helium containing oxygen of 13 vpm at temperatures from 873 to 1273 K were studied. SUS 316 and PE 16 were internally oxidized above 1100 K. The marked depletion of Cr and Mn in SUS 316 specimens was observed in the commercial grade helium above around 1100 K. Nb-1% Zr and V-25% Mo extremely absorbed oxygen and nitrogen from the helium gases and were deteriorated in the range of test temperatures. Mo and TZM appeared not to be affected by the exposure to the commercial grade helium at temperature up to 1273 K. However, Mo and TZM lost ductility at room temperature after exposure to helium above 1100 and 900 K respectively. (orig.)

Impurity control in TFTR

International Nuclear Information System (INIS)

Cecchi, J.L.

1980-06-01

The control of impurities in TFTR will be a particularly difficult problem due to the large energy and particle fluxes expected in the device. As part of the TFTR Flexibility Modification (TEM) project, a program has been implemented to address this problem. Transport code simulations are used to infer an impurity limit criterion as a function of the impurity atomic number. The configurational designs of the limiters and associated protective plates are discussed along with the consideration of thermal and mechanical loads due to normal plasma operation, neutral beams, and plasma disruptions. A summary is given of the materials-related research, which has been a collaborative effort involving groups at Argonne National Laboratory, Sandia Laboratories, and Princeton Plasma Physics Laboratory. Conceptual designs are shown for getterng systems capable of regenerating absorbed tritium. Research on this topic by groups at the previously mentioned laboratories and SAES Research Laboratory is reviewed

Friction, adhesion and corrosion performance of metallurgical coatings in HTGR-helium

International Nuclear Information System (INIS)

Engel, R.; Kleemann, W.

1981-01-01

The friction-, adhesion-, thermal cycling- and corrosion performance of several metallurgical coating systems have been tested in a simulated HTGR-test atmosphere at elevated temperatures. The coatings were applied to a solid solution strengthened Ni-based superalloy. Component design requires coatings for the protection of mating surfaces, since under reactor operating conditions, contacting surfaces of metallic components under high pressures are prone to friction and wear damage. The coatings will have to protect the metal surface for 30 years up to 950 0 C in HTGR-helium. The materials tested were various refractory carbides with or without metallic binders and intermetallic compounds. The coatings evaluated were applied by plasma spraying-, detonation gun- and chemical vapor deposition techniques. These yielded two types of coatings which employ different mechanisms to improve the tribiological properties and maintain coating integrity. (Auth.)

Impurity and particle control for INTOR

International Nuclear Information System (INIS)

Post, D.

1985-02-01

The INTOR impurity control system studies have been focused on the development of an impurity control system which would be able to provide the necessary heat removal and He pumping while satisfying the requirements for (1) minimum plasma contamination by impurities, (2) reasonable component lifetime (approx. 1 year), and (3) minimum size and cost. The major systems examined were poloidal divertors and pumped limiters. The poloidal divertor was chosen as the reference option since it offered the possibility of low sputtering rates due to the formation of a cool, dense plasma near the collector plates. Estimates of the sputtering rates associated with pumped limiters indicated that they would be too high for a reasonable system. Development of an engineering design concept was done for both the poloidal divertor and the pumped limiter

Hydrogen and helium recycling from stirred liquid lithium under steady state plasma bombardment

Energy Technology Data Exchange (ETDEWEB)

Hirooka, Yoshi, E-mail: hirooka.yoshihiko@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); The Graduate School for Advanced Studies, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Zhou, Haishan [The Graduate School for Advanced Studies, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Ono, Masa [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ 08543 (United States)

2014-12-15

For improved core performance via edge plasma-wall boundary control, solid and liquid lithium has been used as a plasma-facing material in a number of confinement experiments over the past several decades. Unfortunately, it is unavoidable that lithium is saturated in the surface region with implanted hydrogenic species as well as oxygen-containing impurities. For steady state operation, a flowing liquid lithium divertor with forced convection would probably be required. In the present work, the effects of liquid stirring to simulate forced convection have been investigated on the behavior of hydrogen and helium recycling from molten lithium at temperatures up to ∼350 °C. Data indicate that liquid stirring reactivates hydrogen pumping via surface de-saturation and/or uncovering impurity films, but can also induce helium release via surface temperature change.

Water quality control system and water quality control method

International Nuclear Information System (INIS)

Itsumi, Sachio; Ichikawa, Nagayoshi; Uruma, Hiroshi; Yamada, Kazuya; Seki, Shuji

1998-01-01

In the water quality control system of the present invention, portions in contact with water comprise a metal material having a controlled content of iron or chromium, and the chromium content on the surface is increased than that of mother material in a state where compression stresses remain on the surface by mechanical polishing to form an uniform corrosion resistant coating film. In addition, equipments and/or pipelines to which a material controlling corrosion potential stably is applied on the surface are used. There are disposed a cleaning device made of a material less forming impurities, and detecting intrusion of impurities and removing them selectively depending on chemical species and/or a cleaning device for recovering drain from various kinds of equipment to feedwater, connecting a feedwater pipeline and a condensate pipeline and removing impurities and corrosion products. Then, water can be kept to neutral purified water, and the concentrations of oxygen and hydrogen in water are controlled within an optimum range to suppress occurrence of corrosion products. (N.H.)

Divertor experiment for impurity control in DIVA

International Nuclear Information System (INIS)

Nagami, Masayuki

1979-04-01

Divertor actions of controlling the impurities and the transport of impurity ions in the plasma have been investigated in the DIVA device. Following are the results: (1) The radial transport of impurity ions is not described only by neoclassical theory, but it is strongly influenced by anomalous process. Radial diffusion of impurity ions across the whole minor radius is well described by a neoclassical diffusion superposed by the anomalous diffusion for protons. Due to this anomalous process, which spreads the radial density profile of impurity ions, 80 to 90% of the impurity flux in the plasma outer edge is shielded even in a nondiverted discharge. (2) The divertor reduces the impurity flux entering the main plasma by a factor of 2 to 4. The impurity ions shielded by the scrape-off plasma are rapidly guided into the burial chamber with a poloidal excursion time roughly equal to that of the scrape-off plasma. (3) The divertor reduces the impurity ion flux onto the main vacuum chamber by guiding the impurity ions diffusing from the main plasma into the burial chamber, thereby reducing the plasma-wall interaction caused by diffusing impurity ions at the main vacuum chamber. The impurity ions produced in the burial chamber may flow back to the main plasma through the scrape-off layer. However, roughly only 0.3% of the impurity flux into the scrape-off plasma in the burial chamber penetrates into the main plasma due to the impurity backflow. (4) A slight cooling of the scrape-off plasma with light-impurity injection effectively reduces the metal impurity production at the first wall by reducing the potential difference between the plasma and the wall, thereby reducing the accumulation of the metal impurity in the discharge. Radiation cooling by low-Z impurities in the plasma outer edge, which may become an important feature in future large tokamaks both with and without divertor, is numerically evaluated for carbon, oxygen and neon. (author)

Corrosion protection and control using nanomaterials

CERN Document Server

Cook, R

2012-01-01

This book covers the use of nanomaterials to prevent corrosion. The first section deals with the fundamentals of corrosion prevention using nanomaterials. Part two includes a series of case studies and applications of nanomaterials for corrosion control.$bCorrosion is an expensive and potentially dangerous problem in many industries. The potential application of different nanostructured materials in corrosion protection, prevention and control is a subject of increasing interest. Corrosion protection and control using nanomaterials explores the potential use of nanotechnology in corrosion control. The book is divided into two parts. Part one looks at the fundamentals of corrosion behaviour and the manufacture of nanocrystalline materials. Chapters discuss the impact of nanotechnology in reducing corrosion cost, and investigate the influence of various factors including thermodynamics, kinetics and grain size on the corrosion behaviour of nanocrystalline materials. There are also chapters on electrodeposition ...

Alternating current techniques for corrosion monitoring in water reactor systems

International Nuclear Information System (INIS)

Isaacs, H.S.; Weeks, J.R.

1977-01-01

Corrosion in both nuclear and fossil fueled steam generators is generally a consequence of the presence of aggressive impurities introduced into the coolant system through condenser leakage. The impurities concentrate in regions of the steam generator protected from coolant flow, in crevices or under deposited corrosion products and adjacent to heat transfer surfaces. These three factors, the aggressive impurity, crevice type areas and heat transfer surfaces appear to be the requirements for the onset of rapid corrosion. Under conditions where coolant impurities do not concentrate the corrosion rates are low, easily measured and can be accounted for by allowances in the design of the steam generator. Rapid corrosion conditions cannot be designed for and must be suppressed. The condition of the surfaces when rapid corrosion develops must be markedly different from those during normal operation and these changes should be observable using electrochemical techniques. This background formed the basis of a design of a corrosion monitoring device, work on which was initiated at BNL. The basic principles of the technique are described. The object of the work is to develop a corrosion monitoring device which can be operated with PWR steam generator secondary coolant feed water

The assessment of the impurities concentration into CANDU steam generator crevices

International Nuclear Information System (INIS)

Lucan, D.; Fulger, M.; Florea, S.; Jinescu, Ghe.; Woinaroschy, Al.

2001-01-01

Crevice corrosion involves a number of simultaneous and interacting operations, including mass transfer processes, production of metal ions within the crevice and hydrolysis reactions, resulting in a very aggressive solution from the point of view of corrosion. These intermediary corrosion processes are in a complex interdependence and they imply a number of important parameters, including both the crevice gap and depth. The major goal of this paper was development of a mathematical model for the calculation of the concentrations of impurities (Na + , Cl - , Fe 2+ ) into crevices and experimental research related to this process. There were identified the important experimental parameters that require further experimental research. This model considers all the processes that interfere in the impurities concentration mechanism achieved into the crevice but it also makes some assumptions for the easy solving of mathematical equations. Because the measurement of the impurities concentration into the steam generator and/or deposition in the crevices solutions is not achievable, one cannot estimate the corrosion intensity inside these locations. The mathematical model presented in this paper may predict the impurities concentration in the crevices. Based on the results obtained in the study of corrosion one can appreciate the corrosion intensity in the materials with crevices or conceive an experimental program, which could lead to results. The predictive quality of the model may contribute to the choice of new design solutions, development of new alloys and criteria of material selection. (authors)

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

Observation of visible emission from the molecular helium ion in the afterglow of a dense helium Z-pinch plasma

International Nuclear Information System (INIS)

Tucker, J.E.; Brake, M.L.; Gilgenbach, R.M.

1986-01-01

The authors present the results of axial and radial time resolved visible emission spectroscopy from the afterglow of a dense helium Z-pinch. These results show that the visible emissions in the pinch afterglow are dominated by line emissions from molecular helium and He II. Axial spectroscopy measurements show the occurrence of several absorption bands which cannot be identified as molecular or atomic helium nor impurities from the discharge chamber materials. The authors believe that these absorption bands are attributable to the molecular helium ion which is present in the discharge. The molecular ion has been observed by others in low pressure and temperature helium discharges directly by means of mass spectrometry and indirectly by the presence of helium atoms in the 2/sup 3/S state, (the He 2/sup 3/S state is believed to result from molecular helium ion recombination). However, the molecular helium ion has not previously been observed spectroscopically

A Multifunctional Coating for Autonomous Corrosion Control

Science.gov (United States)

Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

2011-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

CHECWORKS integrated software for corrosion control

International Nuclear Information System (INIS)

Schefski, C.; Pietralik; Hazelton, T.

1997-01-01

CHECWORKS, a comprehensive software package for managing Flow-Accelerated Corrosion (FAC, also called erosion-corrosion and flow-assisted corrosion) concerns, is expanding to include other systems and other aspects of corrosion control in CANDU reactors. This paper will outline CHECWORKS applications at various CANDU stations and further plans for CHECWORKS to become a code for comprehensive corrosion control management. (author)

Corrosion control. 2. ed.

International Nuclear Information System (INIS)

Bradford, S.A.

2001-01-01

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible for corrosion summed up in only five simple half-cell reactions. When these are combined on a polarization diagram, which is also explained in detail, the electrochemical processes become obvious. For those who want a text stripped bare of electrochemical theory, several noted sections can be omitted without loss of continuity. However, the author has presented the material in such a manner that these sections are not beyond the abilities of any high school graduate who is interested in technology

Evaluation of US demo helium-cooled blanket options

International Nuclear Information System (INIS)

Wong, C.P.C.; McQuillan, B.W.; Schleicher, R.W.

1995-10-01

A He-V-Li blanket design was developed as a candidate for the U.S. fusion demonstration power plant. This paper presents an 18 MPa helium-cooled, lithium breeder, V-alloy design that can be coupled to the Brayton cycle with a gross efficiency of 46%. The critical issue of designing to high gas pressure and the compatibility between helium impurities and V-alloy are addressed

Review of corrosion causes and corrosion control in a technical facility

International Nuclear Information System (INIS)

Charng, T.; Lansing, F.

1982-06-01

Causes of corrosion of metals and their alloys are reviewed. The corrosion mechanism is explained by electrochemical reaction theory. The causes and methods of controlling of both physiochemical corrosion and biological corrosion are presented. Factors which influence the rate of corrosion are also discussed

Internal corrosion control of northern pipelines

Energy Technology Data Exchange (ETDEWEB)

Papavinasam, S.

2005-02-01

The general causes of internal corrosion in pipelines were discussed along with the methods to control them. Efficient methods are needed to determine chemical efficiency for mitigating internal corrosion in transmission pipelines, particularly those used in environmentally sensitive regions in the Arctic where harsh environmental conditions prevail. According to the Office of Pipeline Safety, 15 per cent of pipeline failures in the United States from 1994 to 2000 were caused by internal corrosion. Since pipelines in the United States are slightly older than Canadian pipelines, internal corrosion is a significant issue from a Canadian perspective. There are 306,618 km of energy-related pipelines in western Canada. Between April 2001 and March 2002 there were 808 failures, of which 425 failures resulted from internal corrosion. The approach to control internal corrosion comprises of dehydrating the gases at production facilities; controlling the quality of corrosive gases such as carbon dioxide and hydrogen sulphide; and, using internal coatings. The approaches to control internal corrosion are appropriate, when supplemented by adequate integrity management program to ensure that corrosive liquids do not collect, over the operational lifetime of the pipelines, at localized areas. It was suggested that modeling of pipeline operations may need improvement. This paper described the causes, prediction and control of internal pitting corrosion. It was concluded that carbon steel equipment can continue to be used reliably and safely as pipeline materials for northern pipelines if the causes that lead to internal corrosion are scientifically and accurately predicted, and if corrosion inhibitors are properly evaluated and applied. 5 figs.

Impurity production and transport at the JET belt limiter

International Nuclear Information System (INIS)

Pitcher, C.S.; McCracken, G.M.; Strangeby, P.C.; Toronto Univ., ON; Summers, D.D.R.

1989-01-01

Under certain operating conditions in JET the impurity content of the discharge can be high, thus reducing the fusion reaction rate through the dilution of the hydrogenic fuel. The dilution in most discharges is predominantly due to carbon impurities. In order to understand how carbon impurities are produced and transported into the plasma, detailed measurements with interference filters centered on intense spectral lines of the low ionization states of carbon (C I, C II, C III) as well as the fuel species (Dα) and helium (He I). (author) 6 refs., 4 figs

Relative Humidity and the Susceptibility of Austenitic Stainless Steel to Stress Corrosion Cracking in an impure Plutonium Oxide Environment

Energy Technology Data Exchange (ETDEWEB)

Zapp, P.; Duffey, J.; Lam, P.; Dunn, K.

2010-05-05

Laboratory tests to investigate the corrosivity of moist plutonium oxide/chloride salt mixtures on 304L and 316L stainless steel coupons showed that corrosion occurred in selected samples. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The exposures were conducted in sealed containers in which the oxide-salt mixtures were loaded with about 0.6 wt % water from a humidified helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration, the composition of the salt and the moisture present in the test environment. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride and 0.6 wt% water. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas above the solid mixture, or in coupons exposed to other mixtures with either no CaCl{sub 2} or 0.92 wt% CaCl{sub 2}. SCC was present where the 0.6 wt % water content exceeded the value needed to fully hydrate the available CaCl{sub 2}, but was absent where the water content was insufficient. These results reveal the significance of the relative humidity in the austenitic stainless steels environment to their susceptibility to corrosion. The relative humidity in the test environment was controlled by the water loading and the concentration of the hydrating salts such as CaCl{sub 2}. For each salt or salt mixture there is a threshold

Fractal growth in impurity-controlled solidification in lipid monolayers

DEFF Research Database (Denmark)

Fogedby, Hans C.; Sørensen, Erik Schwartz; Mouritsen, Ole G.

1987-01-01

A simple two-dimensional microscopic model is proposed to describe solidifcation processes in systems with impurities which are miscible only in the fluid phase. Computer simulation of the model shows that the resulting solids are fractal over a wide range of impurity concentrations and impurity...... diffusional constants. A fractal-forming mechanism is suggested for impurity-controlled solidification which is consistent with recent experimental observations of fractal growth of solid phospholipid domains in monolayers. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

Helium storage and control system for the PBMR

International Nuclear Information System (INIS)

Verkerk, E.C.

1997-01-01

The power conversion unit will convert the heat energy in the reactor core to electrical power. The direct-closed cycle recuperated Brayton Cycle employed for this concept consists of a primary helium cycle with helium powered turbo compressors and a power turbine. The helium is actively cooled with water before the compression stages. A recuperator is used to preheat the helium before entering the core. The start of the direct cycle is initiated by a mass flow from the helium inventory and control system via a jet pump. When the PBMR is connected to the grid, changes in power demand can be followed by changing the helium flow and pressure inside the primary loop. Small rapid adjustments can be performed without changing the helium inventory of the primary loop. The stator blade settings on the turbines and compressors are adjustable and it is possible to bypass reactor and turbine. This temporarily reduces the efficiency at which the power conversion unit is operating. Larger or long term adjustments require storage or addition of helium in order to maintain a sufficient level of efficiency in the power conversion unit. The helium will be temporarily stored in high pressure tanks. After a rise in power demand it will be injected back into the system. Some possibilities how to store the helium are presented in this paper. The change of helium inventory will cause transients in the primary helium loop in order to acquire the desired power level. At this stage, it seems that the change of helium inventory does not strongly effect the stability of the power conversion unit. (author)

Engineering and material aspects of impurity control systems

International Nuclear Information System (INIS)

Koski, J.A.

1985-01-01

The design of impurity control devices for fusion energy devices is discussed from the engineering and materials viewpoint. First, examples of impurity control devices are presented, and the plasma edge environment for which they are designed is briefly described. Materials concerns related to the design of the components are discussed and some currently proposed designs presented. Engineering tools available to the designer are listed, and some commonly encountered engineering analysis problems described

Corrosion Control in the Aerospace Industry

Science.gov (United States)

Calle, Luz Marina; Li, Wenyan; Buhrow, Jerry W.; Johnsey, Marissa N.

2016-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it..

Steam generator degradation: Current mitigation strategies for controlling corrosion

International Nuclear Information System (INIS)

Millett, P.

1997-01-01

Steam Generator degradation has caused substantial losses of power generation, resulted in large repair and maintenance costs, and contributed to significant personnel radiation exposures in Pressurized Water Reactors (PWRs) operating throughout the world. EPRI has just published the revised Steam Generator Reference Book, which reviews all of the major forms of SG degradation. This paper discusses the types of SG degradation that have been experienced with emphasis on the mitigation strategies that have been developed and implemented in the field. SG degradation is presented from a world wide perspective as all countries operating PWRs have been effected to one degree or another. The paper is written from a US. perspective where the utility industry is currently undergoing tremendous change as a result of deregulation of the electricity marketplace. Competitive pressures are causing utilities to strive to reduce Operations and Maintenance (O ampersand M) and capital costs. SG corrosion is a major contributor to the O ampersand M costs of PWR plants, and therefore US utilities are evaluating and implementing the most cost effective solutions to their corrosion problems. Mitigation strategies developed over the past few years reflect a trend towards plant specific solutions to SG corrosion problems. Since SG degradation is in most cases an economic problem and not a safety problem, utilities can focus their mitigation strategies on their unique financial situation. Accordingly, the focus of R ampersand D has shifted from the development of more expensive, prescriptive solutions (e.g. reduced impurity limits) to corrosion problems to providing the utilities with a number of cost effective mitigation options (e.g. molar ratio control, boric acid treatment)

Separation of compressor oil from helium

International Nuclear Information System (INIS)

Strauss, R.; Perrotta, K.A.

1982-01-01

Compression of helium by an oil-sealed rorary screw compressor entrains as much as 4000 parts per million by weight of liquid and vapor oil impurities in the gas. The reduction below about 0.1 ppm for cryogenic applications is discussed. Oil seperation equipment designed for compressed air must be modified significantly to produce the desired results with helium. The main differences between air and helium filtration are described. A description of the coalescers is given with the continuous coalescing of liquid mist from air or other gas illustrated. Oil vapor in helium is discussed in terms of typical compressor oils, experimental procedure for measuring oil vapor concentration, measured volatile hydrocarbons in the lubricants, and calculated concentration of oil vapor in Helium. Liquid oil contamination in helium gas can be reduced well below 0.1 ppm by a properly designed multiple state coalescing filter system containing graded efficiency filter elements. The oil vapor problem is best attached by efficiently treating the oil to remove most of the colatiles before charging the compressor

Magnesium secondary alloys: Alloy design for magnesium alloys with improved tolerance limits against impurities

Energy Technology Data Exchange (ETDEWEB)

Blawert, C., E-mail: carsten.blawert@gkss.d [GKSS Forschungszentrum Geesthacht GmbH, Max-Planck-Str. 1, 21502 Geesthacht (Germany); Fechner, D.; Hoeche, D.; Heitmann, V.; Dietzel, W.; Kainer, K.U. [GKSS Forschungszentrum Geesthacht GmbH, Max-Planck-Str. 1, 21502 Geesthacht (Germany); Zivanovic, P.; Scharf, C.; Ditze, A.; Groebner, J.; Schmid-Fetzer, R. [TU Clausthal, Institut fuer Metallurgie, Robert-Koch-Str. 42, 38678 Clausthal-Zellerfeld (Germany)

2010-07-15

The development of secondary magnesium alloys requires a completely different concept compared with standard alloys which obtain their corrosion resistance by reducing the levels of impurities below certain alloy and process depending limits. The present approach suitable for Mg-Al based cast and wrought alloys uses a new concept replacing the {beta}-phase by {tau}-phase, which is able to incorporate more impurities while being electro-chemically less detrimental to the matrix. The overall experimental effort correlating composition, microstructure and corrosion resistance was reduced by using thermodynamic calculations to optimise the alloy composition. The outcome is a new, more impurity tolerant alloy class with a composition between the standard AZ and ZC systems having sufficient ductility and corrosion properties comparable to the high purity standard alloys.

Virtual Instrumentation Corrosion Controller for Natural Gas Pipelines

Science.gov (United States)

Gopalakrishnan, J.; Agnihotri, G.; Deshpande, D. M.

2012-12-01

Corrosion is an electrochemical process. Corrosion in natural gas (methane) pipelines leads to leakages. Corrosion occurs when anode and cathode are connected through electrolyte. Rate of corrosion in metallic pipeline can be controlled by impressing current to it and thereby making it to act as cathode of corrosion cell. Technologically advanced and energy efficient corrosion controller is required to protect natural gas pipelines. Proposed virtual instrumentation (VI) based corrosion controller precisely controls the external corrosion in underground metallic pipelines, enhances its life and ensures safety. Designing and development of proportional-integral-differential (PID) corrosion controller using VI (LabVIEW) is carried out. When the designed controller is deployed at field, it maintains the pipe to soil potential (PSP) within safe operating limit and not entering into over/under protection zone. Horizontal deployment of this technique can be done to protect all metallic structure, oil pipelines, which need corrosion protection.

49 CFR 192.477 - Internal corrosion control: Monitoring.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: Monitoring. 192.477... Control § 192.477 Internal corrosion control: Monitoring. If corrosive gas is being transported, coupons... internal corrosion. Each coupon or other means of monitoring internal corrosion must be checked two times...

Summary of IAEA technical committee meeting on impurity control

International Nuclear Information System (INIS)

Itoh, Kimitaka.

1989-03-01

Presentations given in the IAEA technical committee meeting on impurity control (held in JAERI from 13 to 15 February, 1989) are summarized, putting the emphasis on the physics modelling of the plasma related to the impurity production and confinement. (author)

A Multifunctional Smart Coating for Autonomous Corrosion Control

Science.gov (United States)

Calle, Luz Marina; Buhrow, Jerry W.; Jolley, Scott T.

2012-01-01

Corrosion is a destructive process that often causes failure in metallic components and structures. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to control it. The multi-functionality of the coating is based on micro-encapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of other existing microcapsules designs, the corrosion controlled release function that allows the delivery of corrosion indicators and inhibitors on demand only when and where needed. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection efficacy. This

49 CFR 193.2631 - Internal corrosion control.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control. 193.2631 Section 193... GAS FACILITIES: FEDERAL SAFETY STANDARDS Maintenance § 193.2631 Internal corrosion control. Each component that is subject to internal corrosive attack must be protected from internal corrosion by— (a...

Self-consistent gyrokinetic modeling of neoclassical and turbulent impurity transport

Science.gov (United States)

Estève, D.; Sarazin, Y.; Garbet, X.; Grandgirard, V.; Breton, S.; Donnel, P.; Asahi, Y.; Bourdelle, C.; Dif-Pradalier, G.; Ehrlacher, C.; Emeriau, C.; Ghendrih, Ph.; Gillot, C.; Latu, G.; Passeron, C.

2018-03-01

Trace impurity transport is studied with the flux-driven gyrokinetic GYSELA code (Grandgirard et al 2016 Comput. Phys. Commun. 207 35). A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical and turbulent transport channels can be treated self-consistently on an equal footing. In the Pfirsch-Schlüter regime that is probably relevant for tungsten, the standard expression for the neoclassical impurity flux is shown to be recovered from gyrokinetics with the employed collision operator. Purely neoclassical simulations of deuterium plasma with trace impurities of helium, carbon and tungsten lead to impurity diffusion coefficients, inward pinch velocities due to density peaking, and thermo-diffusion terms which quantitatively agree with neoclassical predictions and NEO simulations (Belli et al 2012 Plasma Phys. Control. Fusion 54 015015). The thermal screening factor appears to be less than predicted analytically in the Pfirsch-Schlüter regime, which can be detrimental to fusion performance. Finally, self-consistent nonlinear simulations have revealed that the tungsten impurity flux is not the sum of turbulent and neoclassical fluxes computed separately, as is usually assumed. The synergy partly results from the turbulence-driven in-out poloidal asymmetry of tungsten density. This result suggests the need for self-consistent simulations of impurity transport, i.e. including both turbulence and neoclassical physics, in view of quantitative predictions for ITER.

Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

Directory of Open Access Journals (Sweden)

Marko Chigondo

2016-01-01

Full Text Available Traditionally, reduction of corrosion has been managed by various methods including cathodic protection, process control, reduction of the metal impurity content, and application of surface treatment techniques, as well as incorporation of suitable alloys. However, the use of corrosion inhibitors has proven to be the easiest and cheapest method for corrosion protection and prevention in acidic media. These inhibitors slow down the corrosion rate and thus prevent monetary losses due to metallic corrosion on industrial vessels, equipment, or surfaces. Inorganic and organic inhibitors are toxic and costly and thus recent focus has been turned to develop environmentally benign methods for corrosion retardation. Many researchers have recently focused on corrosion prevention methods using green inhibitors for mild steel in acidic solutions to mimic industrial processes. This paper provides an overview of types of corrosion, corrosion process, and mainly recent work done on the application of natural plant extracts as corrosion inhibitors for mild steel.

Corrosion of stainless and carbon steels in molten mixtures of industrial nitrates

Energy Technology Data Exchange (ETDEWEB)

Goods, S.H.; Bradshaw, R.W. [Sandia National Labs., Livermore, CA (United States); Prairie, M.R.; Chavez, J.M. [Sandia National Labs., Albuquerque, NM (United States)

1994-03-01

Corrosion behavior of two stainless steels and carbon steel in mixtures of NaNO{sub 3} and KNO{sub 3} was evaluated to determine if impurities found in commodity grades of alkali nitrates aggravate corrosivity as applicable to an advanced solar thermal energy system. Corrosion tests were conducted for 7000 hours with Types 304 and 316 stainless steels at 570C and A36 carbon steel at 316C in seven mixtures of NaNO{sub 3} and KNO{sub 3} containing variations in impurity concentrations. Corrosion tests were also conducted in a ternary mixture of NaNO{sub 3}, KNO{sub 3}, and Ca(NO{sub 3}){sub 2}. Corrosion rates were determined by descaled weight losses while oxidation products were examined by scanning electron microscopy, electron microprobe analysis, and X-ray diffraction. The nitrate mixtures were periodically analyzed for changes in impurity concentrations and for soluble corrosion products.

Demystifying Controlling Copper Corrosion

Science.gov (United States)

The LCR systematically misses the highest health and corrosion risk sites for copper. Additionally, there are growing concerns for WWTP copper in sludges and discharge levels. There are many corrosion control differences between copper and lead. This talk explains the sometimes c...

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

Control Strategy for Small Molecule Impurities in Antibody-Drug Conjugates.

Science.gov (United States)

Gong, Hai H; Ihle, Nathan; Jones, Michael T; Kelly, Kathleen; Kott, Laila; Raglione, Thomas; Whitlock, Scott; Zhang, Qunying; Zheng, Jie

2018-04-01

Antibody-drug conjugates (ADCs) are an emerging class of biopharmaceuticals. As such, there are no specific guidelines addressing impurity limits and qualification requirements. The current ICH guidelines on impurities, Q3A (Impurities in New Drug Substances), Q3B (Impurities in New Drug Products), and Q6B (Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products) do not adequately address how to assess small molecule impurities in ADCs. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) formed an impurities working group (IWG) to discuss this issue. This white paper presents a strategy for evaluating the impact of small molecule impurities in ADCs. This strategy suggests a science-based approach that can be applied to the design of control systems for ADC therapeutics. The key principles that form the basis for this strategy include the significant difference in molecular weights between small molecule impurities and the ADC, the conjugation potential of the small molecule impurities, and the typical dosing concentrations and dosing schedule. The result is that exposure to small impurities in ADCs is so low as to often pose little or no significant safety risk.

Fission neutron irradiation of copper containing implanted and transmutation produced helium

DEFF Research Database (Denmark)

Singh, B.N.; Horsewell, A.; Eldrup, Morten Mostgaard

1992-01-01

High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K. The distribut......High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K...... as well as the effect of the presence of other transmutation produced impurity atoms in the 800 MeV proton irradiated copper will be discussed....

Impurity bubbles in a BEC

Science.gov (United States)

Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

2013-05-01

Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

49 CFR 192.475 - Internal corrosion control: General.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: General. 192.475... Control § 192.475 Internal corrosion control: General. (a) Corrosive gas may not be transported by... taken to minimize internal corrosion. (b) Whenever any pipe is removed from a pipeline for any reason...

49 CFR 192.461 - External corrosion control: Protective coating.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion control...

Effects of alloying elements on nodular and uniform corrosion resistance of zirconium-based alloys

International Nuclear Information System (INIS)

Abe, Katsuhiro

1992-01-01

The effects of alloying and impurity elements (tin, iron, chromium, nickel, niobium, tantalum, oxygen, aluminum, carbon, nitrogen, silicon, and phosphorus) on the nodular and uniform corrosion resistance of zirconium-based alloys were studied. The improving effect of iron, nickel and niobium in nodular corrosion resistance were observed. The uniform corrosion resistance was also improved by nickel, niobium and tantalum. The effects of impurity elements, nitrogen, aluminum and phosphorus were negligibly small but increasing the silicon content seemed to improve slightly the uniform corrosion resistance. Hydrogen pick-up fraction were not changed by alloying and impurity elements except nickel. Nickel addition increased remarkably hydrogen pick-up fraction. Although the composition of secondary precipitates changed with contents of alloying elements, the correlation of composition of secondary precipitates to corrosion resistance was not observed. (author)

Oxidation characteristics of the electron beam surface-treated Alloy 617 in high temperature helium environments

International Nuclear Information System (INIS)

Lee, Ho Jung; Sah, Injin; Kim, Donghoon; Kim, Hyunmyung; Jang, Changheui

2015-01-01

The oxidation characteristics of the electron beam surface-treated Alloy 617, which has an Al-rich surface layer, were evaluated in high temperature helium environments. Isothermal oxidation tests were performed in helium (99.999% purity) and VHTR-helium (helium of prototypical VHTR chemistry containing impurities like CO, CO 2 , CH 4 , and H 2 ) environments at 900 °C for up to 1000 h. The surface-treated Alloy 617 showed an initial transient oxidation stage followed by the steady-state oxidation in all test environments. In addition, the steady-state oxidation kinetics of the surface-treated Alloy 617 was 2-order of magnitude lower than that of the as-received Alloy 617 in both helium environments as well as in air. The improvement in oxidation resistance was primarily due to the formation of the protective Al 2 O 3 layer on the surface. The weight gain was larger in the order of air, helium, and VHTR-helium, while the parabolic rate constants (k p ) at steady-state were similar for all test environments. In both helium environments, the oxide structure consisted of the outer transition Al 2 O 3 with a small amount of Cr 2 O 3 and inner columnar structured Al 2 O 3 without an internal oxide. In the VHTR-helium environment, where the impurities were added to helium, the initial transient oxidation increased but the steady state kinetics was not affected

Method of plasma impurity control without magnetic divertor

International Nuclear Information System (INIS)

Schivell, J.F.

1977-06-01

A method is proposed for controlling impurity generation in a tokomak by skimming and pumping the scrape-off. This method avoids many of the complications of a magnetic divertor, such as specially configured magnetic fields, toroidal symmetry, and inefficient use of toroidal field volume. Estimates are given for operating parameters. Impurity reductions of as much as a factor of 10 should be achievable. The necessary high-capacity pump would employ either titanium gettering or cryocondensation

Preventing Corrosion by Controlling Cathodic Reaction Kinetics

Science.gov (United States)

2016-03-25

3. DATES COVERED (From - To) 09/23/15 - 04/22/16 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Preventing Corrosion by Controlling Cathodic Reaction...Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith

Effect of Alloying Element and Heat Treatment on Mechanical and Corrosion Property of Ni-Cr-Co-Mo Alloy at 950 .deg. C

International Nuclear Information System (INIS)

Kim, Dong Jin; Jung, Su Jin; Moon, Byung Hak; Kim, Sung Woo; Lim, Yun Soo; Kim, Hong Pyo

2013-01-01

Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. The carbon monoxide, methane, hydrogen, and water that are formed by the reaction with the graphite in the core induce various surface reactions that lead to material property changes over time. According to previous reports it was predicted that the outer oxide layer thickness, internal oxide depth, and carbidedepleted zone depth increase to 116 μm, 600 μm, and 1000 μm, respectively, when Alloy 617 is exposed to a plausible impure helium environment at 950 .deg. C for 20 years, based on the reaction rate constant determined from the short time experiment. These values are large enough to pay attention to the material degradation at high temperature, i. e., the life of the IHX. Therefore, finding the range of impurity concentration at which the material is stable, based on the thermodynamics and kinetics determined by a long-term experiment, is very important to the optimum chemistry control for a life extension. Another countermeasure is to improve the material performance through alloy development. Commercial nickel-based wrought alloy is strengthened by a solid solution and precipitation hardening mechanism in a wide temperature range of 500 to 900 .deg. C. The γ' significantly contributes to the strengthening by forming an anti-phase boundary and preventing a dislocation motion at an intermediate temperature range of 700 to 800 .deg. C, but is no longer stable above this temperature range. However, the material for an IHX needs to fulfill the mechanical property requirements in a narrow, very high temperature range of 850 to 950 .deg. C rather than in a wide temperature range. Therefore, it is worth making the effort to find an optimum combination of alloying elements and processing

Effect of Alloying Element and Heat Treatment on Mechanical and Corrosion Property of Ni-Cr-Co-Mo Alloy at 950 .deg. C

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Jin; Jung, Su Jin; Moon, Byung Hak; Kim, Sung Woo; Lim, Yun Soo; Kim, Hong Pyo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. The carbon monoxide, methane, hydrogen, and water that are formed by the reaction with the graphite in the core induce various surface reactions that lead to material property changes over time. According to previous reports it was predicted that the outer oxide layer thickness, internal oxide depth, and carbidedepleted zone depth increase to 116 μm, 600 μm, and 1000 μm, respectively, when Alloy 617 is exposed to a plausible impure helium environment at 950 .deg. C for 20 years, based on the reaction rate constant determined from the short time experiment. These values are large enough to pay attention to the material degradation at high temperature, i. e., the life of the IHX. Therefore, finding the range of impurity concentration at which the material is stable, based on the thermodynamics and kinetics determined by a long-term experiment, is very important to the optimum chemistry control for a life extension. Another countermeasure is to improve the material performance through alloy development. Commercial nickel-based wrought alloy is strengthened by a solid solution and precipitation hardening mechanism in a wide temperature range of 500 to 900 .deg. C. The γ' significantly contributes to the strengthening by forming an anti-phase boundary and preventing a dislocation motion at an intermediate temperature range of 700 to 800 .deg. C, but is no longer stable above this temperature range. However, the material for an IHX needs to fulfill the mechanical property requirements in a narrow, very high temperature range of 850 to 950 .deg. C rather than in a wide temperature range. Therefore, it is worth making the effort to find an optimum combination of alloying elements and processing

Environmentally Friendly Coating Technology for Autonomous Corrosion Control

Science.gov (United States)

Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Johnsey, Marissa N.; Jolley, Scott T.; Pearman, Benjamin P.; Zhang, Xuejun; Fitzpatrick, Lilliana; Gillis, Mathew; Blanton, Michael;

Disruption mitigation with high-pressure helium gas injection on EAST tokamak

Science.gov (United States)

Chen, D. L.; Shen, B.; Granetz, R. S.; Qian, J. P.; Zhuang, H. D.; Zeng, L.; Duan, Y.; Shi, T.; Wang, H.; Sun, Y.; Xiao, B. J.

2018-03-01

High pressure noble gas injection is a promising technique to mitigate the effect of disruptions in tokamaks. In this paper, results of mitigation experiments with low-Z massive gas injection (helium) on the EAST tokamak are reported. A fast valve has been developed and successfully implemented on EAST, with valve response time  ⩽150 μs, capable of injecting up to 7 × 1022 particles, corresponding to 300 times the plasma inventory. Different amounts of helium gas were injected into stable plasmas in the preliminary experiments. It is seen that a small amount of helium gas (N_He≃ N_plasma ) can not terminate a discharge, but can trigger MHD activity. Injection of 40 times the plasma inventory impurity (N_He≃ 40× N_plasma ) can effectively radiate away part of the thermal energy and make the electron density increase rapidly. The mitigation result is that the current quench time and vertical displacement can both be reduced significantly, without resulting in significantly higher loop voltage. This also reduces the risk of runaway electron generation. As the amount of injected impurity gas increases, the gas penetration time decreases slowly and asymptotes to (˜7 ms). In addition, the impurity gas jet has also been injected into VDEs, which are more challenging to mitigate that stable plasmas.

Corrosion aspects in steam generators of nuclear power plants

International Nuclear Information System (INIS)

Visoni, E.; Santos Pinto, M. dos

1988-01-01

Steam generators of pressurized water reactors (PWR), transfer heat from a primary coolant system to a secondary coolant system. Primary coolant water is heated in the core and passes through the steam generator that transfer heat to the secondary coolant water. However, the steam generator is dead for ionic impurities, corrosion products and fabrication/maintenence residues. These impurities concentrate between crevice and cracks. Many types of degradation mechanisms affect the tubes. The tubes are dented, craked, ovalized, wasted, etc. This paper describes the main corrosion problems in steam generators and includes the corrective actions to considered to reduce or eliminate these corrosion problems. (author) [pt

The assessment of helium purification system of small power HTGR

International Nuclear Information System (INIS)

Siti Alimah; Sriyono

2016-01-01

The helium purification system (HPS) is one of safety system of High Temperature Gas-cooled Reactor. HPS removes impurities in the primary coolant, so that the impact on structure, system and component (SSC) is minimized. The two impurity types are particulates (carbon dust, fission products (Kr, Xe, Cs etc.) and the gases (O_2, N_2, H_2O, CH_4, CO, CO_2 and H_2). Every reactor has a different impurity limit during normal operation, depends on the reactor power, energy conversion system and fuel type. This paper discusses the HPS on HTR-10, HTTR and Indonesian RDE conceptual design. The purpose of this assessment is to determine the optimum HPS design as a role model for Indonesian RDE. The utilized methodology is a literature study based on the operating experiences of both HTR-10 and HTTR as well as the evaluation of RDE conceptual design. This study focuses on the impurities limit during normal operation, the main components of HPS, mass flow-rate and regeneration process. The main component that used in HPS for HTR-10, HTTR and RDE are similar i.e. filter, CuO column, water cooler, molecular sieve bed and cryogenic activated carbon bed. Refer to the HTR-10 and HTTR operational experiences, both of those reactors have a purification systems that capable to maintain the helium purity, even though the impurities limit are different. The HPS of HTTR Japan has a stricter impurities limit that N_2, CH_4, and O_2 should not be contained at all during normal operation and the pre-charcoal trap is used to adsorb the fine dust below 0.1 micron. Both of these parameters can be adopted to the RDE's HPS design to minimize the effect of impurities to SSC. (author)

Irradiation-assisted stress corrosion cracking of austenitic alloys

International Nuclear Information System (INIS)

Was, G.S.; Atzmon, M.

1991-01-01

An experimental program has been conducted to determine the mechanism of irradiation-assisted stress-corrosion cracking (IASCC) in austenitic stainless steel. High-energy protons have been used to produce grain boundary segregation and microstructural damage in samples of controlled impurity content. The densities of network dislocations and dislocation loops were determined by transmission electron microscopy and found to resemble those for neutron irradiation under LWR conditions. Grain boundary compositions were determined by in situ fracture and Auger spectroscopy, as well as by scanning transmission electron microscopy. Cr depletion and Ni segregation were observed in all irradiated samples, with the degree of segregation depending on the type and amount of impurities present. P, and to a lesser extent P, impurities were observed to segregate to the grain boundaries. Irradiation was found to increase the susceptibility of ultra-high-purity (UHP), and to a much lesser extent of UHP+P and UHP+S, alloys to intergranular SCC in 288 degree C water at 2 ppm O 2 and 0.5 μS/cm. No intergranular fracture was observed in arcon atmosphere, indicating the important role of corrosion in the embrittlement of irradiated samples. The absence of intergranular fracture in 288 degree C argon and room temperature tests also suggest that the embrittlement is not caused by hydrogen introduced by irradiation. Contrary to common belief, the presence of P impurities led to a significant improvement in IASCC over the ultrahigh purity alloy

Liquid metal corrosion considerations in alloy development

International Nuclear Information System (INIS)

Tortorelli, P.F.; DeVan, J.H.

1984-01-01

Liquid metal corrosion can be an important consideration in developing alloys for fusion and fast breeder reactors and other applications. Because of the many different forms of liquid metal corrosion (dissolution, alloying, carbon transfer, etc.), alloy optimization based on corrosion resistance depends on a number of factors such as the application temperatures, the particular liquid metal, and the level and nature of impurities in the liquid and solid metals. The present paper reviews the various forms of corrosion by lithium, lead, and sodium and indicates how such corrosion reactions can influence the alloy development process

Helium-Cooled Refractory Alloys First Wall and Blanket Evaluation

International Nuclear Information System (INIS)

Wong, C.P.C.; Nygren, R.E.; Baxi, C.B.; Fogarty, P.; Ghoniem, N.; Khater, H.; McCarthy, K.; Merrill, B.; Nelson, B.; Reis, E.E.; Sharafat, S.; Schleicher, R.; Sze, D.K.; Ulrickson, M.; Willms, S.; Youssef, M.; Zinkel, S.

1999-01-01

Under the APEX program the He-cooled system design task is to evaluate and recommend high power density refractory alloy first wall and blanket designs and to recommend and initiate tests to address critical issues. We completed the preliminary design of a helium-cooled, W-5Re alloy, lithium breeder design and the results are reported in this paper. Many areas of the design were assessed, including material selection, helium impurity control, and mechanical, nuclear and thermal hydraulics design, and waste disposal, tritium and safety design. System study results show that at a closed cycle gas turbine (CCGT) gross thermal efficiency of 57.5%, a superconducting coil tokamak reactor, with an aspect ratio of 4, and an output power of 2 GWe, can be projected to have a cost of electricity at 54.6 mill/kWh. Critical issues were identified and we plan to continue the design on some of the critical issues during the next phase of the APEX design study

Manufacturing cycle for pure neon-helium mixture production

International Nuclear Information System (INIS)

Batrakov, B.P.; Kravchenko, V.A.

1980-01-01

The manufacturing cycle for pure neon-helium mixture production with JA-300 nitrogen air distributing device has been developed. Gas mixture containing 2-3% of neon-helium mixture (the rest is mainly nitrogen 96-97%) is selected out of the cover of the JA-300 column condensator and enters the deflegmator under the 2.3-2.5 atm. pressure. The diflegmator presents a heat exchange apparatus in which at 78 K liquid nitrogen the condensation of nitrogen from the mixture of gases entering from the JA-300 column takes place. The enriched gas mixture containing 65-70% of neon-helium mixture and 30-35% of nitrogen goes out from the deflegmator. This enriched neon-helium mixture enters the gasgoeder for impure (65-70%) neon-helium mixture. Full cleaning of-neon helium mixture of nitrogen is performed by means of an adsorber. As adsorbent an activated coal has been used. Adsorption occurs at the 78 K temperature of liquid nitrogen and pressure P=0.1 atm. As activated coal cooled down to nitrogen temperature adsorbs nitrogen better than neon and helium, the nitrogen from the mixture is completely adsorbed. Pure neon-helium mixture from the adsorber comes into a separate gasgolder. In one campaign the cycle allows obtaining 2 m 3 of the mixture. The mixture contains 0.14% of nitrogen, 0.01% of oxygen and 0.06% of hydrogen

Advanced Gas Cooled Reactor Materials Program. Reducing helium impurity depletion in HTGR materials testing

International Nuclear Information System (INIS)

Baldwin, D.H.

1984-08-01

Moisture depletion in HTGR materials testing rigs has been empirically studied in the GE High Temperature Reactor Materials Testing Laboratory (HTRMTL). Tests have shown that increased helium flow rates and reduction in reactive (oxidizable) surface area are effective means of reducing depletion. Further, a portion of the depletion has been shown to be due to the presence of free C released by the dissociation of CH 4 . This depletion component can be reduced by reducing the helium residence time (increasing the helium flow rate) or by reducing the CH 4 concentration in the test gas. Equipment modifications to reduce depletion have been developed, tested, and in most cases implemented in the HTRMTL to date. These include increasing the Helium Loop No. 1 pumping capacity, conversion of metallic retorts and radiation shields to alumina, isolation of thermocouple probes from the test gas by alumina thermowells, and substitution of non-reactive Mo-TZM for reactive metallic structural components

Identification and control of unspecified impurity in trimetazidine dihydrochloride tablet formulation

Science.gov (United States)

Jefri; Puspitasari, A. D.; Talpaneni, J. S. R.; Tjandrawinata, R. R.

2018-04-01

Trimetazidine dihydrochloride is an anti-ischemic metabolic agent which is used as drug for angina pectoris treatment. The drug substance monograph is available in European Pharmacopoeia and British Pharmacopoeia, while the drug product monograph is not available in any of the pharmacopoeias. During development of trimetazidine dihydrochloride tablet formulation, we found increase of an unspecified impurity during preliminary stability study. The unspecified impurity was identified by high performance liquid chromatography coupled with mass spectrometry (LC-MS) and the molecular weight obtained was matching with the molecular weight of N-formyl trimetazidine (m/z 295). Further experiments were performed to confirm the suspected result by injecting the impurity standard and spiking formic acid into the drug substance. The retention time of N-formyl trimetazidine was similar to the unspecified impurity in drug product. Even spiking of formic acid into drug substance showed that the suspected impurity increased with increasing concentration of formic acid. The proposed mechanism of impurity formation is via amidation of piperazine moiety of trimetazidine by formic acid which present as residual solvent in tablet binder used in the formulation. Subsequently, the impurity in our product was controlled by choosing the primary packaging which could minimize the formation of impurity.

Hydrogen and helium trapping in tungsten deposition layers formed by RF plasma sputtering

International Nuclear Information System (INIS)

Kazunari Katayama; Kazumi Imaoka; Takayuki Okamura; Masabumi Nishikawa

2006-01-01

Understanding of tritium behavior in plasma facing materials is an important issue for fusion reactor from viewpoints of fuel control and radiation safety. Tungsten is used as a plasma facing material in the divertor region of ITER. However, investigation of hydrogen isotope behavior in tungsten deposition layer is not sufficient so far. It is also necessary to evaluate an effect of helium on a formation of deposition layer and an accumulation of hydrogen isotopes because helium generated by fusion reaction exists in fusion plasma. In this study, tungsten deposition layers were formed by sputtering method using hydrogen and helium RF plasma. An erosion rate and a deposition rate of tungsten were estimated by weight measurement. Hydrogen and helium retention were investigated by thermal desorption method. Tungsten deposition was performed using a capacitively-coupled RF plasma device equipped with parallel-plate electrodes. A tungsten target was mounted on one electrode which is supplied with RF power at 200 W. Tungsten substrates were mounted on the other electrode which is at ground potential. The plasma discharge was continued for 120 hours where pressure of hydrogen or helium was controlled to be 10 Pa. The amounts of hydrogen and helium released from deposition layers was quantified by a gas chromatograph. The erosion rate of target tungsten under helium plasma was estimated to be 1.8 times larger than that under hydrogen plasma. The deposition rate on tungsten substrate under helium plasma was estimated to be 4.1 times larger than that under hydrogen plasma. Atomic ratio of hydrogen to tungsten in a deposition layer formed by hydrogen plasma was estimated to be 0.17 by heating to 600 o C. From a deposition layer formed by helium plasma, not only helium but also hydrogen was released by heating to 500 o C. Atomic ratios of helium and hydrogen to tungsten were estimated to be 0.080 and 0.075, respectively. The trapped hydrogen is probably impurity hydrogen

Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium

Energy Technology Data Exchange (ETDEWEB)

Guenbour, Abdellah [Laboratory of Electrochemistry-Corrosion, Av. Ibn Batouta, BP1014-Faculty of Science, Rabat (Morocco)]. E-mail: guenbour@fsr.ac.ma; Hajji, Mohamed-Adil [Group Corrosion and Protection of Materials, ENIM, Rabat (Morocco); Jallouli, El Miloudi [Group Corrosion and Protection of Materials, ENIM, Rabat (Morocco); Bachir, Ali Ben [Laboratory of Electrochemistry-Corrosion, Av. Ibn Batouta, BP1014-Faculty of Science, Rabat (Morocco)

2006-12-30

The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P{sub 2}O{sub 5} has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content.

Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium

International Nuclear Information System (INIS)

Guenbour, Abdellah; Hajji, Mohamed-Adil; Jallouli, El Miloudi; Bachir, Ali Ben

2006-01-01

The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P 2 O 5 has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content

Corrosion control for low-cost reliability: Preceedings

International Nuclear Information System (INIS)

Anon.

1993-01-01

This book is Volume 6 of the preceedings from the 12th International Corrosion Congress. The electric power industry workshop dealt with water chemistry control; monitoring of chemical, electrochemical, and biological corrosion; corrosion product analyses; and nuclear and fossil-fuel power plants. All papers have been processed separately for inclusion on the data base

Self-pumping inpurity control systems for INTOR

International Nuclear Information System (INIS)

Brooks, J.N.; Mattas, R.F.; Smith, D.L.; Hassanein, A.M.

1987-01-01

Two self-pumping systems have been examined for use as the INTOR impurity control system. The systems work by trapping helium in freshly deposited metal surface layers on or near the divertor plate. A slot divertor concept using vanadium or other trapping material appears to be both feasible and mechanically simple, and offers significant advantages in cost, reduced complexity, and helium pumping efficiency for the INTOR design

Application of secondary ion emission to impurity control in tokamaks

International Nuclear Information System (INIS)

Krauss, A.R.; Gruen, D.M.

1979-01-01

The extent to which high Z impurities enter the plasma of a magnetic confinement fusion device depends on the kinetic energy, angle of emission, and very importantly, the charge state of the ejected material. We have been studying both the fundamental process of secondary ion emission and possible techniques for producing surfaces which give rise to high ion fractions during sputtering, with a view to assessing the potential of this approach to impurity control in tokamaks. By carefully choosing materials exposed to fusion plasmas and by properly modifying the surface it may be possible to insure that nearly all the impurities are ejected as ions. As long as certain gas blanket configurations are avoided and especially if a divertor is used, it should then be possible to remove the impurities before they reach the plasma. The relative merits of a variety of materials are considered with regard to this application

Dictionary corrosion and corrosion control. English-German/German-English. Fachwoerterbuch Korrosion und Korrosionsschutz. Englisch-Deutsch/Deutsch-Englisch

Energy Technology Data Exchange (ETDEWEB)

1985-01-01

This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods.

A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning

International Nuclear Information System (INIS)

Dylla, H.F.

1989-09-01

Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates, such as H 2 O, CO, and CH 4 , and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H 2 O, CO, and CO 2 ; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling. 38 refs., 6 figs

Phenomenological studies and modelling of the gaseous impurities oxidation and adsorption mechanisms in helium: application for the purification system optimization in gas cooled nuclear reactors

International Nuclear Information System (INIS)

Legros, F.

2008-01-01

In GEN IV studies on future fission nuclear reactors, two concepts using helium as a coolant have been selected: GFR and VHTR. Among radioactive impurities and dusts, helium can contain H 2 , CO, CH 4 , CO 2 , H 2 O, O 2 , as well as nitrogenous species. To optimize the reactor functioning and lifespan, it is necessary to control the coolant chemical composition using a dedicated purification system. A pilot designed at the CEA allows studying this purification system. Its design includes three unit operations: H 2 and CO oxidation on CuO, then two adsorption steps. This study aims at providing a detailed analysis of the first and second purification steps, which have both been widely studied experimentally at laboratory scale. A first modelling based on a macroscopic approach was developed to represent the behaviour of the reactor and has shown that the CuO fixed bed conversion is dependent on the chemistry (mass transfer is not an issue) and is complete. The results of the structural analysis of the solids allow considering the CuO as particles made of 200 nm diameter grains. Hence, a new model at grain scale is proposed. It is highlighted that the kinetic constants from these two models are related with a scale factor which depends on geometry. A competition between carbon monoxide and hydrogen oxidation has been shown. Activation energies are around 30 kJ.mol-1. Simulation of the simultaneous oxidations leads to consider CO preferential adsorption. A similar methodology has been applied for CO 2 and H 2 O adsorption. The experimental isotherms showed a Langmuir type adsorption. Using this model, experimental and theoretical results agree. (author) [fr

Development of NSTX Particle Control Techniques

International Nuclear Information System (INIS)

Kugel, H.W.; Maingi, R.; Bell, M.; Gates, D.; Hill, K.; LeBlanc, B.; Mueller, D.; Kaita, R.; Paul, S.; Sabbagh, S.; Skinner, C.H.; Soukhanovskii, V.; Stratton, B.; Raman, R.

2004-01-01

The National Spherical Torus Experiment (NSTX) High Harmonic Fast Wave (HHFW) current-drive discharges will require density control for acceptable efficiency. In NSTX, this involves primarily controlling impurity influxes and recycling. We have compared boronization on hot and cold surfaces, varying helium glow discharge conditioning (HeGDC) durations, helium discharge cleaning, brief daily boronization, and between discharge boronization to reduce and control spontaneous density rises. Access to Ohmic H-modes was enabled by boronization on hot surfaces, however, the duration of the effectiveness of hot and cold boronization was comparable. A 15 minute HeGDC between discharges was needed for reproducible L-H transitions. Helium discharge conditioning yielded slower density rises than 15 minutes of HeGDC. Brief daily boronization followed by a comparable duration of applied HeGDC restored and enhanced good conditions. Additional brief boronizations between discharges did not improve plasma performance (reduced recycling, reduced impurity luminosities, earlier L-H transitions, longer plasma current flattops, higher stored energies) if conditions were already good. Between discharge boronization required increases in the NSTX duty cycle due to the need for additional HeGDC to remove codeposited D

Control of helium effects in irradiated materials based on theory and experiment

International Nuclear Information System (INIS)

Mansur, L.K.; Lee, E.H.; Maziasz, P.J.; Rowcliffe, A.F.

1986-01-01

Helium produced in materials by (n,α) transmutation reactions during neutron irradiations or subjected in ion bombardment experiments causes substantial changes in the response to displacement damage. In particular, swelling, phase transformations and embrittlement are strongly affected. Present understanding of the mechanisms underlying these effects is reviewed. Key theoretical relationships describing helium effects on swelling and helium diffusion are described. Experimental data in the areas of helium effects on swelling and precipitation is reviewed with emphasis on critical experiments that have been designed and evaluated in conjunction with theory. Confirmed principles for alloy design to control irradiation performance are described

Heavy impurity collection at the plasma edge of the stellarator W VII A

International Nuclear Information System (INIS)

Schou, J.

1981-12-01

The presence of impurities at the plasma edge of the Wendelstein VII-A stellarator was studied by means of carbon probes that were exposed to up to 200 plasma discharges in helium. The probes were subsequently analysed with 1 MeV 4 He + Rutherford Backscattering. The average impurity deposition for Ti, Mo and wall components (Fe, Cr, Ni) was 2-4 x 10 12 atoms/cm 2 , 6 x 10 10 atoms/cm 2 and 1 x 10 11 atoms/cm 2 per discharge, respectively. With the exception of Ti this impurity deposition is more than one order of magnitude smaller than the corresponding results from comparable tokamaks. (orig.)

Influence of heating rate on corrosion behavior of Ni-base heat resistant alloys in simulated VHTR helium environment

International Nuclear Information System (INIS)

Kurata, Yuji; Kondo, Tatsuo

1985-04-01

The influence of heating rate on corrosion and carbon transfer was studied for Ni-base heat resistant alloys exposed to simulated VHTR(very high temperature reactor) coolant environment. Special attention was focused to relationship between oxidation and carburization at early stage of exposure. Tests were conducted on two heats of Hastelloy XR with different boron(B) content and the developmental alloys, 113MA and KSN. Two kinds of heating rates, i.e. 80 0 C/min and 2 0 C/min, were employed. Corrosion tests were carried out at 900 0 C up to 500 h in JAERI Type B helium, one of the simulated VHTR primary coolant specifications. Under higher heating rate, oxidation resistance of both heats of Hastelloy XR(2.8 ppmB and 40 ppmB) were equivalent and among the best, then KSN and 113MA followed in the order. Under lower heating rate only alloy, i.e. Hastelloy XR with 2.8 ppmB, showed some deteriorated oxidation resistance while all others being unaffected by the heating rate. On the other hand the carbon transfer behavior showed strong dependence on the heating rate. In case of higher heating rate, significant carburization occured at early stage of exposure and thereafter the progress of carburization was slow in all the alloys. On the other hand only slow carburization was the case throughout the exposure in case of lower heating rate. The carburization in VHTR helium environment was interpreted as to be affected by oxide film formation in the early stage of exposure. The carbon pick-up was largest in Hastelloy XR with 40 ppmB and it was followed by Hastelloy XR with 2.8 ppmB. 113MA and KSN were carburized only slightly. The observed difference of carbon pick-up among the alloys tested was interpreted to be attributed mainly to the difference of the carbon activity, the carbide precipitation characteristics among the alloys tested. (author)

Analytical model of impurity concentration during steam generation in permeable porous structures

International Nuclear Information System (INIS)

Polonskii, V.S.; Orlov, A.V.

1993-01-01

A model is proposed to describe the mass transfer of impurities during steam generation on a surface covered by porous deposits of corrosion products. The model is based on replacement of the actual structure of the deposits by a system of cylindrical fluid and vapor channels in which the flow of vapor and a liquid film is described by the Navier-Stokes equations. The driving force in the process is assumed to be the difference in the Laplacian pressures due to surface tension on the front and back sides of elongated vapor bubbles. Calculations performed for the operating conditions of the drums of the steam generators of nuclear power plants with water-moderated water-cooled reactors show that the mass transfer rate is extremely low in the gaps in cold drums and that the concentration of aggressive impurities deep within these channels may reach two or more orders of magnitude-thus leading to rapid corrosion. Almost complete vaporization occurs in the capillary channels of hot drums with deposits, which probably precludes corrosion in the channel depths. However, corrosion damage remains a possibility at the entrance to the channels (on the side of the second loop)

TEM study of impurity segregations in beryllium pebbles

Energy Technology Data Exchange (ETDEWEB)

Klimenkov, M., E-mail: michael.klimenkov@kit.edu [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chakin, V.; Moeslang, A. [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rolli, R. [Institute for Applied Materials – Materials and Biomechanics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2014-12-15

Beryllium is planned to be used as a neutron multiplier in the Helium-cooled Pebble Bed European concept of a breeding blanket of demonstration power reactor DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron-irradiated at temperatures typical of fusion blankets. Beryllium pebbles 1 mm in diameter produced by the rotating electrode method were subjected to a TEM study before and after irradiation at High Flux Reactor, Petten, Netherlands at 861 K. The grain size varied in a wide range from sub-micron size up to several tens of micrometers, which indicated formation bimodal grain size distribution. Based on the application of combined electron energy loss spectroscopy and energy dispersive X-ray spectroscopy methods, we suggest that impurity precipitates play an important role in controlling the mechanical properties of beryllium. The impurity elements were present in beryllium at a sub-percent concentration form beryllide particles of a complex (Fe/Al/Mn/Cr)B composition. These particles are often ordered along dislocations lines, forming several micron-long chains. It can be suggested that fracture surfaces often extended along these chains in irradiated material.

Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

Energy Technology Data Exchange (ETDEWEB)

Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

2014-10-15

Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.

Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

International Nuclear Information System (INIS)

Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

1998-01-01

The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

Effect of impurities on vacancy migration energy in Fe-based alloys

International Nuclear Information System (INIS)

Hashimoto, N.; Sakuraya, S.; Tanimoto, J.; Ohnuki, S.

2014-01-01

Effects of impurities, such as carbon, nitrogen, helium and hydrogen, on microstructural evolution in pure iron were investigated by means of a multi-beam electron microscope. Growth rate of dislocation loops were measured to calculate vacancy migration energies. In all irradiation temperature conditions, both the size and the number density of dislocation loops were increased as a function of dose. Irradiation with more impurities showed an increase in the temperature dependence of the dislocation loop growth rate compared to irradiation with little impurities. The in situ experiment indicated that the net migration energy of vacancies could be increased due to trapping by impurities, and the effect of C and N on the migration energy of vacancy would be larger than that of W, V, Ta. Furthermore, H and He would increase vacancy migration energy greater than C and N, as well as W, V, Ta. The density functional theory (DFT), applied to the atomic models of BCC iron, indicated an increase in vacancy migration energy by the trapping of impurity atoms, that is a good agreement with this in situ experiment

Effective Kα x-ray excitation rates for plasma impurity measurements

International Nuclear Information System (INIS)

Hill, K.W.; Bitter, M.; von Goeler, S.; Hiroe, S.; Hulse, R.; Ramsey, A.T.; Sesnic, S.; Shimada, M.; Stratton, B.C.

1986-06-01

Metal impurity concentrations are measured by the Pulse-Height-Analyzer (PHA) diagnostic from Kα x-ray peak intensities by use of an averaged excitation rate . Low-Z impurity concentrations are inferred from the continuum enhancement (relative to a pure plasma) minus the enhancement due to metals. Since the PHA does not resolve lines from different charge states, is a weighted sum of rates; coronal equilibrium is usually assumed. The used earlier omitted the intercombination and forbidden lines from the dominant helium-like state. The result was an overestimate of metals and an underestimate of low-Z impurities in cases where metals were significant. Improved values of using recent calculations for H-, He-, and Li-like Fe range from 10 to 50% larger than the earlier rates and yield metal concentrations in better agreement with those from VUV spectroscopy

Trapping of He clusters by inert-gas impurities in tungsten: First-principles predictions and experimental validation

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Manh, Duc, E-mail: duc.nguyen@ccfe.ac.uk; Dudarev, S.L.

2015-06-01

Properties of point defects resulting from the incorporation of inert-gas atoms in bcc tungsten are investigated systematically using first-principles density functional theory (DFT) calculations. The most stable configuration for the interstitial neon, argon, krypton and xenon atoms is the tetrahedral site, similarly to what was found earlier for helium in W. The calculated formation energies for single inert-gas atoms at interstitial sites as well as at substitutional sites are much larger for Ne, Ar, Kr and Xe than for He. While the variation of the energy of insertion of inert-gas defects into interstitial configurations can be explained by a strong effect of their large atomic size, the trend exhibited by their substitutional energies is more likely related to the covalent interaction between the noble gas impurity atoms and the tungsten atoms. There is a remarkable variation exhibited by the energy of interaction between inert-gas impurities and vacancies, where a pronounced size effect is observed when going from He to Ne, Ar, Kr, Xe. The origin of this trend is explained by electronic structure calculations showing that p-orbitals play an important part in the formation of chemical bonds between a vacancy and an atom of any of the four inert-gas elements in comparison with helium, where the latter contains only 1s{sup 2} electrons in the outer shell. The binding energies of a helium atom trapped by five different defects (He-v, Ne-v, Ar-v, Kr-v, Xe-v, where v denotes a vacancy in bcc-W) are all in excellent agreement with experimental data derived from thermal desorption spectroscopy. Attachment of He clusters to inert gas impurity atom traps in tungsten is analysed as a function of the number of successive trapping helium atoms. Variation of the Young modulus due to inert-gas impurities is analysed on the basis of data derived from DFT calculations.

49 CFR 195.589 - What corrosion control information do I have to maintain?

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false What corrosion control information do I have to... SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.589 What corrosion control... sufficient detail to demonstrate the adequacy of corrosion control measures or that corrosion requiring...

Investigation of corrosion behavior of biodegradable magnesium alloys using an online-micro-flow capillary flow injection inductively coupled plasma mass spectrometry setup with electrochemical control

Energy Technology Data Exchange (ETDEWEB)

Ulrich, A., E-mail: andrea.ulrich@empa.ch [Laboratory for Analytical Chemistry, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Ott, N. [Laboratory for Analytical Chemistry, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); EPFL-Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Tournier-Fillon, A. [Laboratory for Corrosion and Material Integrity, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Homazava, N. [Laboratory for Analytical Chemistry, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Swiss Centre for Applied Ecotoxicology, Eawag/EPFL, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); Schmutz, P. [Laboratory for Corrosion and Material Integrity, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland)

2011-07-15

The development of biodegradable metallic materials designed for implants or medical stents is new and is one of the most interesting new fields in material science. Besides biocompatibility, a detailed understanding of corrosion mechanisms and dissolution processes is required to develop materials with tailored degradation behavior. The materials need to be sufficiently stable as long as they have to fulfill their medical task. However, subsequently they should dissolve completely in a controlled manner in terms of maximum body burden. This study focuses on the elemental and time resolved dissolution processes of a magnesium rare earth elements alloy which has been compared to pure magnesium with different impurity level. The here described investigations were performed using a novel analytical setup based on a micro-flow capillary online-coupled via a flow injection system to a plasma mass spectrometer. Differences in element-specific and time-dependent dissolution were monitored for various magnesium alloys in contact with sodium chloride or mixtures of sodium and calcium chloride as corrosive media. The dissolution behavior strongly depends on bulk matrix elements, secondary alloying elements and impurities, which are usually present even in pure magnesium.

Investigation of corrosion behavior of biodegradable magnesium alloys using an online-micro-flow capillary flow injection inductively coupled plasma mass spectrometry setup with electrochemical control

International Nuclear Information System (INIS)

Ulrich, A.; Ott, N.; Tournier-Fillon, A.; Homazava, N.; Schmutz, P.

2011-01-01

The development of biodegradable metallic materials designed for implants or medical stents is new and is one of the most interesting new fields in material science. Besides biocompatibility, a detailed understanding of corrosion mechanisms and dissolution processes is required to develop materials with tailored degradation behavior. The materials need to be sufficiently stable as long as they have to fulfill their medical task. However, subsequently they should dissolve completely in a controlled manner in terms of maximum body burden. This study focuses on the elemental and time resolved dissolution processes of a magnesium rare earth elements alloy which has been compared to pure magnesium with different impurity level. The here described investigations were performed using a novel analytical setup based on a micro-flow capillary online-coupled via a flow injection system to a plasma mass spectrometer. Differences in element-specific and time-dependent dissolution were monitored for various magnesium alloys in contact with sodium chloride or mixtures of sodium and calcium chloride as corrosive media. The dissolution behavior strongly depends on bulk matrix elements, secondary alloying elements and impurities, which are usually present even in pure magnesium.

Investigation of corrosion behavior of biodegradable magnesium alloys using an online-micro-flow capillary flow injection inductively coupled plasma mass spectrometry setup with electrochemical control

Science.gov (United States)

Ulrich, A.; Ott, N.; Tournier-Fillon, A.; Homazava, N.; Schmutz, P.

2011-07-01

The development of biodegradable metallic materials designed for implants or medical stents is new and is one of the most interesting new fields in material science. Besides biocompatibility, a detailed understanding of corrosion mechanisms and dissolution processes is required to develop materials with tailored degradation behavior. The materials need to be sufficiently stable as long as they have to fulfill their medical task. However, subsequently they should dissolve completely in a controlled manner in terms of maximum body burden. This study focuses on the elemental and time resolved dissolution processes of a magnesium rare earth elements alloy which has been compared to pure magnesium with different impurity level. The here described investigations were performed using a novel analytical setup based on a micro-flow capillary online-coupled via a flow injection system to a plasma mass spectrometer. Differences in element-specific and time-dependent dissolution were monitored for various magnesium alloys in contact with sodium chloride or mixtures of sodium and calcium chloride as corrosive media. The dissolution behavior strongly depends on bulk matrix elements, secondary alloying elements and impurities, which are usually present even in pure magnesium.

Study of the corrosion behavior and the corrosion films formed on the surfaces of Mg–xSn alloys in 3.5 wt.% NaCl solution

International Nuclear Information System (INIS)

Wang, Jingfeng; Li, Yang; Huang, Song; Zhou, Xiaoen

2014-01-01

Highlights: • Corrosion of four cast Mg–xSn alloys in 3.5 wt.% NaCl solution was investigated. • Both Mg(OH) 2 /SnO 2 corrosion product film and Mg(OH) 2 /MgSnO 3 clusters formed on Mg–1.5Sn. • Compact Mg(OH) 2 /MgSnO 3 film suppressed the cathodic effect of the impurity inclusions. • Mg–xSn (x = 0.5, 1.0, 2.0 wt.%) alloys only formed loose Mg(OH) 2 /SnO 2 corrosion product film. - Abstract: The corrosion behavior and the corrosion films formed on the surfaces of Mg–xSn (x = 0.5, 1.0, 1.5, and 2.0 wt.%) alloys in 3.5 wt.% NaCl solution were investigated by immersion tests, electrochemical measurements, corrosion morphology observations, and X-ray diffraction analysis. Immersion tests and electrochemical measurements illustrated that the best corrosion resistance was reported for the Mg–1.5Sn alloy. Both Mg(OH) 2 /SnO 2 corrosion product film and Mg(OH) 2 /MgSnO 3 clusters formed on Mg–1.5Sn alloy surface. Mg(OH) 2 /MgSnO 3 clusters were compact and suppressed the cathodic effect of the impurity inclusions greatly. The Mg–xSn (x = 0.5, 1.0, and 2.0 wt.%) alloys only formed loose Mg(OH) 2 /SnO 2 corrosion product film during the corrosion process

Launch Pad Coatings for Smart Corrosion Control

Science.gov (United States)

Calle, Luz M.; Hintze, Paul E.; Bucherl, Cori N.; Li, Wenyan; Buhrow, Jerry W.; Curran, Jerome P.; Whitten, Mary C.

2010-01-01

Corrosion is the degradation of a material as a result of its interaction with the environment. The environment at the KSC launch pads has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the US. The 70 tons of highly corrosive hydrochloric acid that are generated by the solid rocket boosters during a launch exacerbate the corrosiveness of the environment at the pads. Numerous failures at the pads are caused by the pitting of stainless steels, rebar corrosion, and the degradation of concrete. Corrosion control of launch pad structures relies on the use of coatings selected from the qualified products list (QPL) of the NASA Standard 5008A for Protective Coating of Carbon Steel, Stainless Steel, and Aluminum on Launch Structures, Facilities, and Ground Support Equipment. This standard was developed to establish uniform engineering practices and methods and to ensure the inclusion of essential criteria in the coating of ground support equipment (GSE) and facilities used by or for NASA. This standard is applicable to GSE and facilities that support space vehicle or payload programs or projects and to critical facilities at all NASA locations worldwide. Environmental regulation changes have dramatically reduced the production, handling, use, and availability of conventional protective coatings for application to KSC launch structures and ground support equipment. Current attrition rate of qualified KSC coatings will drastically limit the number of commercial off the shelf (COTS) products available for the Constellation Program (CxP) ground operations (GO). CxP GO identified corrosion detection and control technologies as a critical, initial capability technology need for ground processing of Ares I and Ares V to meet Constellation Architecture Requirements Document (CARD) CxP 70000 operability requirements for reduced ground processing complexity, streamlined integrated testing, and operations phase affordability

Radiolytic reactions in the coolant of helium cooled reactors

International Nuclear Information System (INIS)

Tingey, G.L.; Morgan, W.C.

1975-01-01

The success of helium cooled reactors is dependent upon the ability to prevent significant reaction between the coolant and the other components in the reactor primary circuit. Since the thermal reaction of graphite with oxidizing gases is rapid at temperatures of interest, the thermal reactions are limited primarily by the concentration of impurity gases in the helium coolant. On the other hand, the rates of radiolytic reactions in helium are shown to be independent of reactive gas concentration until that concentration reaches a very low level. Calculated steady-state concentrations of reactive species in the reactor coolant and core burnoff rates are presented for current U. S. designed, helium cooled reactors. Since precise base data are not currently available for radiolytic rates of some reactions and thermal reaction rate data are often variable, the accuracy of the predicted gas composition is being compared with the actual gas compositions measured during startup tests of the Fort Saint Vrain high temperature gas-cooled reactor. The current status of these confirmatory tests is discussed. 12 references

Applied methods for mitigation of damage by stress corrosion in BWR type reactors; Metodos aplicados para la mitigacion del dano por corrosion bajo esfuerzo en reactores BWR

Energy Technology Data Exchange (ETDEWEB)

Hernandez C, R.; Diaz S, A.; Gachuz M, M.; Arganis J, C. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencia de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

Accurate Determination of the Volume of an Irregular Helium Balloon

Science.gov (United States)

Blumenthal, Jack; Bradvica, Rafaela; Karl, Katherine

2013-01-01

In a recent paper, Zable described an experiment with a near-spherical balloon filled with impure helium. Measuring the temperature and the pressure inside and outside the balloon, the lift of the balloon, and the mass of the balloon materials, he described how to use the ideal gas laws and Archimedes' principal to compute the average molecular…

Design and operation of thermal-convection loops for corrosion measurements in LiF--LiCl--LiBr

International Nuclear Information System (INIS)

Keiser, J.R.; DeVan, J.H.

1979-01-01

Using a most sophisticated design of a thermal-convection loop to study the corrosion behavior of type 316 stainless steel and the salt mixture LiF--LiCl--LiBr is reported. The corrosion rate is being determined as a function of time and temperature through weight change measurements. The maximum corrosion rate measured is about 20 μm/year on removable corrosion specimens. Controlled potential voltammetry has been found to be satisfactory and is being used to monitor the oxidation potential of the salt. Measurements demonstrate the effect on the oxidation potential of impurities introduced during specimen insertion, and techniques should show the effect of a lithium addition on the oxidation potential

Investigation by the Rutherford backscattering method of impurity deposited on the T-3M tokamak diaphragm

International Nuclear Information System (INIS)

Danelyan, L.S.; Egorova, I.M.; Kulikauskas, V.S.; Baratov, D.G.; Belykh, T.A.

1994-01-01

The Rutherford backscattering of helium-4 ions was used for investigation of impurity deposited on the annular graphite diaphragm as a result of the interaction between hydrogen plasma and liquid-metal spray limiter. The experimental RBS spectra distributions of the impurity elements surface densities along the direction from plasma to the chamber wall are presented as depth of the elements. The erosion coefficient of the main liquid-metal limiter element has been estimated

Water chemistry: cause and control of corrosion degradation in nuclear power plants

International Nuclear Information System (INIS)

Kain, Vivekanand

2008-01-01

The corrosion degradation of a material is directly determined by the water chemistry, material (composition, fabrication procedure and microstructure) and by the stress/strain in the material under operating conditions. Water chemistry plays an important role in both uniform corrosion and localized forms of corrosion of materials. Once we understand how water chemistry is contributing to corrosion of a material, it is logical to modify/change that water chemistry to control the corrosion degradation. In nuclear power plants, different water chemistries have been used in different components/systems. This paper will cover the origin of corrosion degradation in the Primary Heat Transport system of different reactor types, Steam Generator tubing, secondary circuit pipelines, service water pipelines and auxiliary systems and establish the role of water chemistry in causing corrosion degradation. The history of changes in water chemistry adopted in these systems to control corrosion degradation is also described. It is shown by examples that there is an obvious limitation in changing water chemistry to control corrosion degradation and in those cases, a change of material or change of the state of stresses/fabrication procedure becomes necessary. The role of water chemistry as a causative factor and also as a controlling parameter on particular types of corrosion degradation e.g. stress corrosion cracking, flow accelerated corrosion, pitting, crevice corrosion is illustrated. It will be shown that increase in dissolved oxygen content (due to radiolysis in nuclear reactors) is sufficient to make even the de-mineralized water to cause stress corrosion cracking in Boiling Water Reactors. Hydrogen Water Chemistry (by hydrogen injection) to control dissolved oxygen is shown to control the stress corrosion cracking. However, it is not possible to control dissolved oxygen at all parts of the Boiling Water Reactors. Therefore, a further refinement in terms of noble metal

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

Corrosion Control 101: A Journey in Rediscovery | Science ...

Science.gov (United States)

The presentation covers the general water chemistry of lead and copper, how contamination originates from home plumbing systems, what treatments are appropriate for controlling lead and copper to meet the Lead and Copper Rule, and what water quality and treatment factors directly impact the success and failure of corrosion control treatment. This talk re-introduces the overriding principles of corrosion control treatment to a water industry audience

Fighting corrosion in air pollution control systems

International Nuclear Information System (INIS)

Rittenhouse, R.C.

1991-01-01

This paper reports that materials is the name of the game for corrosion prevention in air pollution control equipment. Whether the system is already in place, a retrofit, are specified for a new power pant, preventing corrosion is critical, because such deterioration easily undermines reliability. Hence, materials can heavily influence power plant compliance to the 1990 Clean Air Act amendments. Flue gas desulfurization (FGD) systems, perhaps the most vulnerable area to corrosion, are expected to be the method of choice for sulfur removal in many power plants in the near term. Components of these systems have various degrees of susceptibility to corrosion and related problems

Noble gas atoms as chemical impurities in silicon

International Nuclear Information System (INIS)

Tkachev, V.D.; Mudryi, A.V.; Minaev, N.S.

1984-01-01

The behaviour of noble gas atoms implanted in silicon is studied by the luminescence method. The energy position of Moessbauer-type luminescence bands with zero-phonon lines 1.0148, 1.0120, 1.0097, 1.0048 eV and others connected with implanted atoms of neon, helium, argon, krypton, respectively, indicates the formation of deep energy levels in the forbidden gap of silicon. Implantation of the noble gas isotopes confirms their participation in formation processes of the luminescence centers in silicon. The temperature range of existence and the symmetry of defects incorporating the noble gas atoms are found. It is noted that noble gas atoms form impurity complexes with deep energy levels and their behaviour in crystals does not differ from that of main doped or residual technological impurity atoms. (author)

INTOR impurity control and first wall system

International Nuclear Information System (INIS)

Abdou, M.A.

1983-04-01

The highlights of the recent INTOR effort on examining the key issues of the impurity control/first wall system are summarized. The emphasis of the work was an integrated study of the edge-region physics, plasma-wall interaction, materials, engineering and magnetic considerations associated with the poloidal divertor and pump limiter. The development of limiter and divertor collector plate designs with an acceptable lifetime was a major part of the work

Corrosion control in CANDU nuclear power reactors

International Nuclear Information System (INIS)

Lesurf, J.E.

1974-01-01

Corrosion control in CANDU reactors which use pressurized heavy water (PHW) and boiling light water (BLW) coolants is discussed. Discussions are included on pressure tubes, primary water chemistry, fuel sheath oxidation and hydriding, and crud transport. It is noted that corrosion has not been a significant problem in CANDU nuclear power reactors which is a tribute to design, material selection, and chemistry control. This is particularly notable at the Pickering Nuclear Generating Station which will have four CANDU-PHW reactors of 540 MWe each. The net capacity factor for Pickering-I from first full power (May 1971) to March 1972 was 79.5 percent, and for Pickering II (first full power November 1971) to March 1972 was 83.5 percent. Pickering III has just reached full power operation (May 1972) and Pickering IV is still under construction. Gentilly CANDU-BLW reached full power operation in May 1972 after extensive commissioning tests at lower power levels with no major corrosion or chemistry problems appearing. Experience and operating data confirm that the value of careful attention to all aspects of corrosion control and augur well for future CANDU reactors. (U.S.)

Process Control Migration of 50 LPH Helium Liquefier

Science.gov (United States)

Panda, U.; Mandal, A.; Das, A.; Behera, M.; Pal, Sandip

2017-02-01

Two helium liquefier/refrigerators are operational at VECC while one is dedicated for the Superconducting Cyclotron. The first helium liquefier of 50 LPH capacity from Air Liquide has already completed fifteen years of operation without any major trouble. This liquefier is being controlled by Eurotherm PC3000 make PLC. This PLC has become obsolete since last seven years or so. Though we can still manage to run the PLC system with existing spares, risk of discontinuation of the operation is always there due to unavailability of spare. In order to eliminate the risk, an equivalent PLC control system based on Siemens S7-300 was thought of. For smooth migration, total programming was done keeping the same field input and output interface, nomenclature and graphset. New program is a mix of S7-300 Graph, STL and LAD languages. One to one program verification of the entire process graph was done manually. The total program was run in simulation mode. Matlab mathematical model was also used for plant control simulations. EPICS based SCADA was used for process monitoring. As of now the entire hardware and software is ready for direct replacement with minimum required set up time.

Corrosion Processes of the CANDU Steam Generator Materials in the Presence of Silicon Compounds

International Nuclear Information System (INIS)

Lucan, Dumitra; Fulger, Manuela; Velciu, Lucian; Lucan, Georgiana; Jinescu, Gheorghita

2006-01-01

The feedwater that enters the steam generators (SG) under normal operating conditions is extremely pure but, however, it contains low levels (generally in the μg/l concentration range) of impurities such as iron, chloride, sulphate, silicate, etc. When water is converted into steam and exits the steam generator, the non-volatile impurities are left behind. As a result of their concentration, the bulk steam generator water is considerably higher than the one in the feedwater. Nevertheless, the concentrations of corrosive impurities are in general sufficiently low so that the bulk water is not significantly aggressive towards steam generator materials. The impurities and corrosion products existing in the steam generator concentrate in the porous deposits on the steam generator tubesheet. The chemical reactions that take place between the components of concentrated solutions generate an aggressive environment. The presence of this environment and of the tubesheet crevices lead to localized corrosion and thus the same tubes cannot ensure the heat transfer between the fluids of the primary and secondary circuits. Thus, it becomes necessary the understanding of the corrosion process that develops into SG secondary side. The purpose of this paper is the assessment of corrosion behavior of the tubes materials (Incoloy-800) at the normal secondary circuit parameters (temperature = 2600 deg C, pressure = 5.1 MPa). The testing environment was demineralized water containing silicon compounds, at a pH=9.5 regulated with morpholine and cyclohexyl-amine (all volatile treatment - AVT). The paper presents the results of metallographic examinations as well as the results of electrochemical measurements. (authors)

Environmental degradation of materials and corrosion control in metals

International Nuclear Information System (INIS)

Lou, J.; Elboujdaini, M.; Shoesmith, D.; Patnaik, P.C.

2003-01-01

The first International Symposium on Environmental Degradation of Materials and Corrosion Control In Metals (EDMCCM), held in Quebec City in 1999, was very successful. Encouraged by this success. the Metallurgical Society of CIM organized the Second International Conference in what is hoped will be an on-going series. This meeting was held in Vancouver, British Columbia, Canada, in August 2003. The objective of this conference was to provide a wide-ranging forum for the discussion of recent developments in the study and understanding of corrosion degradation of metals and alloys and the variety of processes by which corrosion damage accumulates. The scope of the meeting ranged from the fundamental to the very applied with a primary emphasis on the inter-relationships between chemical, electrochemical, mechanical and metallurgical features of corrosion. This symposium was an excellent forum for the exchange of ideas and approaches between generally disparate fields of endeavour. The success of the symposium can be gauged from the large number of papers presented and the outstanding level of international participation, with authors from China, Iran, Japan, North America, Russia, United Kingdom and Venezuela. In addition authors from six Canadian provinces (Alberta, British Columbia, New Brunswick, Ontario, Quebec, Saskatchewan) participated. Six keynote presentations covered a wide range of topics and industries in corrosion and corrosion control, and a total 45 papers were presented, spread over three days in six individual sessions; Electrochemistry and Corrosion of Metals, Corrosion and Cracking Behaviour. Hydrogen in Steel and Pipeline Corrosion, Corrosion Case Studies and Applications, Characterization of Corrosion Behaviour, and Corrosion Protection Coatings. (author)

Corrosion of the CANDU steam generator tubesheet due to aqueous environment pH

International Nuclear Information System (INIS)

Lucan, D.; Fulger, M.; Velciu, L.

2009-01-01

There is a side environment that is known to be affected significantly by several factors dependent on the balance of plant conditions (condenser leaks, condensate polishing, and coolant system materials) as well on the operational conditions, particularly through their thermal-hydraulic effects. The presence of tube-tubesheet crevices and restricted flow areas within sludge or surface deposits provides for local concentration sites for various impurities, including the acidic ones. The generalized corrosion can occur and can affect the steam generator performances. It is very important to understand the generalized corrosion mechanism with the purpose of evaluating the amount of corrosion products which exist in the steam generator after a determined period of operation. The purpose of this work consists in the assessment of corrosion behavior of the tubesheet material (carbon steel SA508 cl.2) at normal secondary circuit parameters (temperature, 260 deg. C, pressure, 5.1 MPa). The testing environment was the demineralized water without impurities, at different pH values regulated with morpholine and cyclohexylamine (all volatile treatment - AVT). The results are presented like micrographs, potentiodynamic curves and graphics representing loss of metal by corrosion, corrosion rate, the total corrosion products, the adherent corrosion products, the released corrosion products and the release of the metal. (authors)

Impurity doping: a novel strategy for controllable synthesis of functional lanthanide nanomaterials.

Science.gov (United States)

Chen, Daqin; Wang, Yuansheng

2013-06-07

Many technological nanomaterials are intentionally 'doped' by introducing appropriate amounts of foreign elements into hosts to impart electronic, magnetic and optical properties. In fact, impurity doping was recently found to have significant influence on nucleation and growth of many functional nanocrystals (NCs), and provide a fundamental approach to modify the crystallographic phase, size, morphology, and electronic configuration of nanomaterials. In this feature article, we provide an overview of the most recent progresses in doping-induced control of phase structures, sizes, shapes, as well as performances of functional nanomaterials for the first time. Two kinds of impurity doping strategies, including the homo-valence ion doping and hetero-valence ion doping, are discussed in detail. We lay emphases on impurity doping induced modifications of microstructures and optical properties of upconversion (UC) lanthanide (Ln(3+)) NCs, but do not limit to them. In addition, we also illustrate the control of Ln(3+) activator distribution in the core@shell architecture, which has recently provided scientists with new opportunities for designing and tuning the multi-color emissions of Ln(3+)-doped UC NCs. Finally, the challenges and future perspectives of this novel impurity doping strategy are pointed out.

Corrosion mechanism applicable to biodegradable magnesium implants

Energy Technology Data Exchange (ETDEWEB)

Atrens, Andrej, E-mail: Andrejs.Atrens@uq.edu.au [University of Queensland, Division of Materials, Brisbane, Qld 4072 (Australia); Liu Ming; Zainal Abidin, Nor Ishida [University of Queensland, Division of Materials, Brisbane, Qld 4072 (Australia)

2011-12-15

Much of our understanding of the Mg corrosion mechanism is based on research using aggressive chloride based solutions like 3% NaCl, which are appropriate for understand the corrosion for applications such as auto construction. The chloride ions tend to cause break down of the partly protective surface film on the Mg alloy surface. The corrosion rate increases with exposure time until steady state is reached, which may take several weeks. An overview is provided of the aspects which determine the corrosion of Mg alloys: (i) measurement details; (ii) impurity elements Fe, Ni, Cu and Co; (iii) second phases; (iv) surface films and surface condition and (v) stress corrosion cracking (SCC). This understanding is used to help understand Mg corrosion for Mg as a biodegradable implant for medical applications. Solutions that elucidate these applications tend to form surface films and the corrosion rate tends to decrease with immersion time.

Corrosion Evaluation and Corrosion Control of Steam Generators

International Nuclear Information System (INIS)

Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M.

2008-06-01

Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants

Corrosion of aluminum alloys in a reactor disassembly basin

International Nuclear Information System (INIS)

Howell, J.P.; Zapp, P.E.; Nelson, D.Z.

1992-01-01

This document discusses storage of aluminum clad fuel and target tubes of the Mark 22 assembly takes place in the concrete-lined, light-water-filled, disassembly basins located within each reactor area at the Savannah River Site (SRS). A corrosion test program has been conducted in the K-Reactor disassembly basin to assess the storage performance of the assemblies and other aluminum clad components in the current basin environment. Aluminum clad alloys cut from the ends of actual fuel and target tubes were originally placed in the disassembly water basin in December 1991. After time intervals varying from 45--182 days, the components were removed from the basin, photographed, and evaluated metallographically for corrosion performance. Results indicated that pitting of the 8001 aluminum fuel clad alloy exceeded the 30-mil (0.076 cm) cladding thickness within the 45-day exposure period. Pitting of the 1100 aluminum target clad alloy exceeded the 30-mil (0.076 cm) clad thickness in 107--182 days exposure. The existing basin water chemistry is within limits established during early site operations. Impurities such as Cl - , NO 3 - and SO 4 - are controlled to the parts per million level and basin water conductivity is currently 170--190 μmho/cm. The test program has demonstrated that the basin water is aggressive to the aluminum components at these levels. Other storage basins at SRS and around the US have successfully stored aluminum components for greater than ten years without pitting corrosion. These basins have impurity levels controlled to the parts per billion level (1000X lower) and conductivity less than 1.0 μmho/cm

QM/MM study of dislocation—hydrogen/helium interactions in α-Fe

International Nuclear Information System (INIS)

Zhao, Yi; Lu, Gang

2011-01-01

Impurities such as hydrogen (H) and helium (He) interact strongly with dislocations in metals. Using a multiscale quantum-mechanics/molecular-mechanics (QM/MM) approach, we have examined the interactions between the impurities (H and He) with dislocations (edge and screw) in α-Fe. The impurity trapping at the dislocation core is examined by calculating the impurity-dislocation binding energy and the impurity solution energy. We find that in general both H and He prefer the tetrahedral sites at the dislocation core, as well as in the bulk; the exceptions are due to deformed structures at the dislocation cores. Both H and He have a greater solution energy and binding energy to the edge dislocation than to the screw dislocation. The impurity pipe diffusion along the dislocation core is investigated using the QM/MM nudged-elastic-band method. We find that the diffusion barrier along the screw dislocation is lower than the bulk value for both H and He impurities. For the edge dislocation, although H has similar diffusion barriers as in the bulk, He has much higher diffusion energy barriers compared with the bulk. Finally we have examined the impurity effect on the dislocation mobility. We find that both H and He can lower the Peierls energy barrier for the screw dislocation significantly. The H enhanced dislocation mobility is consistent with experimental observations

Corrosion and Corrosion-Fatigue Behavior of 7075 Aluminum Alloys Studied by In Situ X-Ray Tomography

Science.gov (United States)

Stannard, Tyler

for samples of multiple aging conditions and impurity concentrations. Additionally, chemical reactions between the 3.5 wt% NaCl solution and the crack surfaces were quantified by observing the evolution of hydrogen bubbles from the crack. The effects of the impurity particles and age-hardening particles on the corrosion and fatigue properties were examined in 4D.

Thermal hydraulics of the impurity control system for FED/INTOR

International Nuclear Information System (INIS)

Cha, Y.S.; Mattas, R.F.; Abdou, M.A.; Haines, J.R.

1983-01-01

This paper addresses two important aspects of thermal hydraulics related to the design of the impurity control system (limiter and divertor) of the Fusion Engineering Device (FED) and the International Tokamak Reactor (INTOR). The first part of the paper is devoted to the determination of temperature distributions in various combinations of the coating/structural materials proposed for the limiter/divertor of FED and INTOR. The second part of the paper describes the analysis of the tangential motion of the melt layer under the influence of magnetic force during plasma disruption. The results of both analysis provide inputs to the determination of the life time of the limiter (or divertor) which is the most critical problem for the impurity control system as far as engineering and materials consideration is concerned

Creep and fatigue of alloy 800 in helium

International Nuclear Information System (INIS)

Cook, R.H.

1975-01-01

Proposals for use of Alloy 800 as a H.T.R. boiler material have prompted studies of its creep and high temperature fatigue properties in impure helium with comparative tests in air. In impure helium, as expected in a H.T.R., reactions of potential importance are selective oxidation (of chromium, aluminium and titanium) and possibly carburisation from carbon monoxide or methane. In air, general oxidation will occur, possibly accompanied by nitridation. The effects of these reactions will depend on specimen geometry and the nature of the deformation. Two important possibilities are: (i) that environment affects the structure and properties of a surface zone of material undegoing uniform deformation (this may modify creep rate and crack nucleation); and (ii) that environment affects behaviour of a small region (e.g. at the root of a notch or ahead of a crack) in a specimen undergoing non-uniform deformation (this will modify crack growth and hence rupture life or fatigue endurance). This paper summarises experimental work demonstrating an influence of the above reactions on mechanical properties of austenitic steels and nickel-based alloys, drawing examples where possible from the limited data available on Alloy 800. Whilst nitridation and carburisation may simply increase creep resistance at the expense of ductility (and possibly of fatigue resistance), the effects of oxidation are complex. A high oxygen pressures (as in air) oxygen may reduce creep and fatigue resistance by promoting cavitation but formation of oxide in cracks can reduce their propagation rate. At low oxygen pressures, as expected in H.T.R. helium, oxygen enhanced cavitation is less likely, but selective oxidation along grain boundaries can sometimes assist crack nucleation. (author)

Survey of atomic data base needs and accuracies for helium beam stopping and alpha particle diagnostics for ITER

International Nuclear Information System (INIS)

Summers, H.P.; Hellermann, M. von.

1992-01-01

This report is concerned with establishing a recommended collection of atomic collision data for the modelling, experimental investigation and exploitation of helium beams. The motivation stems from proposals for diagnostic beams for the ITER tokamak, targeted at alpha particle measurement via double charge transfer, neutralized alpha particle analysis and spectroscopic analysis of recombination radiation. The report discusses the beam energies, species involved in collisions with the helium atom beam (fuel, helium ash and plasma impurities) and plasma conditions prevailing in large tokamak devices. It also lists the required cross-section data

Corrosion Evaluation and Corrosion Control of Steam Generators

Energy Technology Data Exchange (ETDEWEB)

Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M

2008-06-15

Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants.

Corrosion control for open cooling water system

International Nuclear Information System (INIS)

Karweer, S.B.; Ramchandran, R.

2000-01-01

Frequent stoppage of water circulation due to shut down of the Detritiation Plant in Heavy Water Division, Trombay resulted in considerable algae growth. As polyphosphate is a nutrient to algae growth, studies were directed in the evaluation of a nonpolyphosphate formulation for controlling corrosion and scale formation of carbon-steel, copper and aluminium. A blend of HEDP, polyacrylate, zinc, and benzotriazole was used and the optimum condition was determined. In presence of 25 ppm kw-1002 [proprietary formulation, containing HEDP and polyacrylate], 10 ppm kw-201 [active ingredient benzotriazole] and 2 ppm zinc (as zinc sulphate), the corrosion rate of carbon-steel in Mumbai Municipal Corporation (MMC) water at pH 7.5 ± 0.1 for a period of 31 days was 10.4 x 10 -3 μm/h. When MMC water concentrated to half its original volume was used, the corrosion rate was still 9.74 x 10 -3 μm/h close to the original value without concentration. Hence, this formulation was used for controlling scale and corrosion. The results were satisfactory. (author)

Effect of density control and impurity transport on internal transport barrier formation in tokamak plasma

International Nuclear Information System (INIS)

Yamakami, Tomoyuki; Fujita, Takaaki; Arimoto, Hideki; Yamazaki, Kozo

2014-01-01

In future fusion reactors, density control, such as fueling by pellet injection, is an effective method to control the formation of the internal transport barrier (ITB) in reversed magnetic shear plasma, which can improve plasma performance. On the other hand, an operation with ITB can cause accumulation of impurities inside the core ITB region. We studied the relation between pellet injection and ITB formation and the effect of impurity transport on the core of ITB for tokamak plasmas by using the toroidal transport analysis linkage. For ITB formation, we showed that the pellet has to be injected beyond the position where the safety factor q takes the minimum value. We confirmed that the accumulation of impurities causes the attenuation of ITB owing to radiation loss inside the ITB region. Moreover, in terms of the divertor heat flux reduction by impurity gas, the line radiation loss is high for high-Z noble gas impurities, such as Kr, whereas factor Q decreases slightly. (author)

Use of nonlocal helium microplasma for gas impurities detection by the collisional electron spectroscopy method

Energy Technology Data Exchange (ETDEWEB)

Kudryavtsev, Anatoly A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, Margarita S.; Pramatarov, Petko M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

2015-10-15

The collisional electron spectroscopy (CES) method, which lays the ground for a new field for analytical detection of gas impurities at high pressures, has been verified. The CES method enables the identification of gas impurities in the collisional mode of electron movement, where the advantages of nonlocal formation of the electron energy distribution function (EEDF) are fulfilled. Important features of dc negative glow microplasma and probe method for plasma diagnostics are applied. A new microplasma gas analyzer design is proposed. Admixtures of 0.2% Ar, 0.6% Kr, 0.1% N{sub 2}, and 0.05% CO{sub 2} are used as examples of atomic and molecular impurities to prove the possibility for detecting and identifying their presence in high pressure He plasma (50–250 Torr). The identification of the particles under analysis is made from the measurements of the high energy part of the EEDF, where maxima appear, resulting from the characteristic electrons released in Penning reactions of He metastable atoms with impurity particles. Considerable progress in the development of a novel miniature gas analyzer for chemical sensing in gas phase environments has been made.

A confocal optical microscope for detection of single impurities in a bulk crystal at cryogenic temperatures.

Science.gov (United States)

Karlsson, Jenny; Rippe, Lars; Kröll, Stefan

2016-03-01

A compact sample-scanning confocal optical microscope for detection of single impurities below the surface of a bulk crystal at cryogenic temperatures is described. The sample, lens, and scanners are mounted inside a helium bath cryostat and have a footprint of only 19 × 19 mm. Wide field imaging and confocal imaging using a Blu-ray lens immersed in liquid helium are demonstrated with excitation at 370 nm. A spatial resolution of 300 nm and a detection efficiency of 1.6% were achieved.

Creep-rupture behavior of 2-1/4 Cr-1 Mo steel, Alloy 800H and Hastelloy Alloy X in a simulated HTGR helium environment

International Nuclear Information System (INIS)

Lai, G.Y.; Wolwowicz, R.J.

1979-12-01

Creep-rupture testing was conducted on 1 1/4 Cr-1 Mo steel, Alloy 800H and Hastelloy Alloy X in flowing helium containing nominal concentration of following gases: 1500 μatm H 2 , 450 μatm CO, 50 μatm CH 4 , 50 μatm H 2 O and 5 μatm CO 2 . This environment is believed to represent maximum permissible levels of impurities in the primary coolant for the steam-cycle system of a high-temperature gas-cooled reactor (HTGR) when it is operating continuously with a water and/or steam leak at technical specification limits. Two or three heats of material for each alloy were investigated. Tests were conducted at 482 0 C and 760 0 C (1200 0 F and 1400 0 F) for Alloy 800H, and at 760 0 C and 871 0 C (1400 0 F and 1600 0 F) for Hastelloy Alloy X for times up to 10,000 h. Selected tests were performed on same heat of material in both air and helium environments to make a direct comparison of creep-rupture behaviors between two environments. Metallurgical evaluation was performed on selected post test specimens with respect to gas-metal interactions which included oxidation, carburization and/or decarburization. Correlation between gaseous corrosion and creep-rupture behavior was attempted. Limited tests were also performed to investigate the specimen size effects on creep-rupture behavior in the helium environment

49 CFR 192.476 - Internal corrosion control: Design and construction of transmission line.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: Design and... STANDARDS Requirements for Corrosion Control § 192.476 Internal corrosion control: Design and construction... the risk of internal corrosion. At a minimum, unless it is impracticable or unnecessary to do so, each...

Applied methods for mitigation of damage by stress corrosion in BWR type reactors

International Nuclear Information System (INIS)

Hernandez C, R.; Diaz S, A.; Gachuz M, M.; Arganis J, C.

1998-01-01

The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

Creep properties of heat-resistant superalloys for nuclear plants in helium

International Nuclear Information System (INIS)

Shimizu, Shigeki; Satoh, Keisuke; Matsuda, Shozo; Murase, Hirokazu; Fujioka, Junzo.

1979-01-01

In order to estimate the creep and rupture strengths of candidate alloys for the intermediate heat exchanger of VHTR, creep and stress rupture tests in impure helium were conducted on Hastelloy X, Inconel 617, Inconel 625, Incoloy 800 and Incoloy 807 at 900 0 C. The results were discussed in comparison with those in air and the alloys were examined from the point of view of the elevated temperature structural design. The main results obtained are summarized as follows: (1) No appreciable decrease in creep and rupture strengths in helium as compared with those in air is observed on Hastelloy X and Inconel 625. On the contrary, the creep and rupture strengths of Inconel 617 in helium decrease slightly as compared with those in air. In the case of Incoloy 807, the creep strength to cause 1 percent total strain and that to initiate secondary creep increase remarkably in helium as compared with those in air. However, the creep strength to cause initiation of tertiary creep and the rupture strength in helium remarkably decrease as compared with those in air. (2) The order of magnitude of the S 0 value for each material in helium is as follows; Hastelloy X > Inconel 617 > Incoloy 807 > Inconel 625 > Incoloy 800 Meanwhile, that of the S sub(t) value in helium is; Inconel 617 > Hastelloy X > Incoloy 807 > Inconel 625 > Incoloy 800. (author)

BWR water chemistry impurity studies

International Nuclear Information System (INIS)

Ljungberg, L.G.; Korhonen, S.; Renstroem, K.; Hofling, C.G.; Rebensdorff, B.

1990-03-01

Laboratory studies were made on the effect of water impurities on environmental cracking in simulated BWR water of stainless steel, low alloy steel and nickel-base alloys. Constant elongation rate tensile (CERT) tests were run in simulated normal water chemistry (NWC), hydrogen water chemistry (HWC), or start-up environment. Sulfate, chloride and copper with chloride added to the water at levels of a fraction of a ppM were found to be extremely deleterious to all kinds of materials except Type 316 NG. Other detrimental impurities were fluoride, silica and some organic acids, although acetic acid was beneficial. Nitrate and carbon dioxide were fairly inoccuous. Corrosion fatigue and constant load tests on compact tension specimens were run in simulated normal BWR water chemistry (NWC) or hydrogen water chemistry (HWC), without impurities or with added sulfate or carbon dioxide. For sensitized Type 304 SS in NWC, 0.1 ppM sulfate increased crack propagation rates in constant load tests by up to a factor of 100, and in fatigue tests up to a factor of 10. Also, cracking in Type 316 nuclear grade SS and Alloy 600 was enhanced, but to a smaller degree. Carbon dioxide was less detrimental than sulfate. 3 figs., 4 tabs

Hot corrosion behavior of Ni-Cr-W-C alloys in impure He gas

International Nuclear Information System (INIS)

Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

1977-01-01

Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995%He gas at 1,000 0 C, in comparison with the behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure He gas usually causes selective oxidation of the elements described above and the growth of oxide whiskers on the surface of specimen at elevated temperatures. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by additions of Mn and Si, providing tough spinel type oxide film on the surface and 'keys' on the oxide-matrix interface respectively. The amount and morphology of the oxide whiskers depended on Si and Mn contents. Si of more than 0.29% without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changes the whiskers to thicker ones of spinel type oxide (MnCr 2 O 4 ) with rough surface. On the basis of these results, the optimum contents of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack, and the spalling of oxide film were discussed. (auth.)

PIPELINE CORROSION CONTROL IN OIL AND GAS INDUSTRY: A ...

African Journals Online (AJOL)

Corrosion in pipelines is one of the major challenges faced by oil and gas industries all over the world. This has made corrosion control or management a major factor to consider before setting up any industry that will transport products via pipelines. In this study the types of corrosion found on system 2A pipeline were; ...

HeREF-2003: Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

HeREF-2003 : Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF
...

An overview of materials degradation by stress corrosion in PWRs

Energy Technology Data Exchange (ETDEWEB)

Scott, P. M. [Framatome ANP, Tour Areva, 92084 Paris La Defense Cedex (France)

2004-07-01

The aging of water cooled and moderated nuclear steam supply systems has given rise to many material corrosion problems of which stress corrosion cracking has proved to be one of the most serious. The aim of this paper is to review some examples of corrosion and particularly stress corrosion problems from the author's experience of interpreting and modelling these phenomena in PWR systems. Examples of stress corrosion cracking in PWR systems described include the major issue of Alloy 600 intergranular cracking in primary PWR coolants, for which it is generally perceived that both adequate life prediction models and remedial measures now exist. Intergranular corrosion and stress corrosion cracking of Alloy 600 steam generator tubes that occur in occluded superheated crevices on the secondary side of steam generators due to hide-out and concentration of water borne impurities are also addressed. Rather less extensive or well known examples are discussed such as the stress corrosion cracking of carbon and low alloy steels and of stainless steels in occluded dead-leg situations where it is sometimes difficult to guarantee adequate control of water chemistry, particularly at plant start-up. Reference is also be made to the use of high strength fastener materials in PWR systems as well as to the emerging issue of the effect of high neutron doses on the stress corrosion resistance of core structural components fabricated from austenitic stainless steels. (authors)

An overview of materials degradation by stress corrosion in PWRs

International Nuclear Information System (INIS)

Scott, P. M.

2004-01-01

The aging of water cooled and moderated nuclear steam supply systems has given rise to many material corrosion problems of which stress corrosion cracking has proved to be one of the most serious. The aim of this paper is to review some examples of corrosion and particularly stress corrosion problems from the author's experience of interpreting and modelling these phenomena in PWR systems. Examples of stress corrosion cracking in PWR systems described include the major issue of Alloy 600 intergranular cracking in primary PWR coolants, for which it is generally perceived that both adequate life prediction models and remedial measures now exist. Intergranular corrosion and stress corrosion cracking of Alloy 600 steam generator tubes that occur in occluded superheated crevices on the secondary side of steam generators due to hide-out and concentration of water borne impurities are also addressed. Rather less extensive or well known examples are discussed such as the stress corrosion cracking of carbon and low alloy steels and of stainless steels in occluded dead-leg situations where it is sometimes difficult to guarantee adequate control of water chemistry, particularly at plant start-up. Reference is also be made to the use of high strength fastener materials in PWR systems as well as to the emerging issue of the effect of high neutron doses on the stress corrosion resistance of core structural components fabricated from austenitic stainless steels. (authors)

Binding of Helium to Metallic Impurities in Tungsten; Experiments and Computer Simulations

NARCIS (Netherlands)

Kolk, G.J. van der; Veen, A. van; Caspers, L.M.; Hosson, J.Th.M. de

1985-01-01

A W(100) single crystal was implanted with low doses Ag, Cu, Mn, Cr, Al or In. Subsequent heating to 1600 K removed all vacancies and left the implants in substitutional positions. Low energy He was injected, and binding of He to the substitutional impurities was observed. Binding energies were

Helium-cooled nuclear reactor

International Nuclear Information System (INIS)

Longton, P.B.; Cowen, H.C.

1975-01-01

In helium cooled HTR's there is a by-pass circuit for cleaning purposes in addition to the main cooling circuit. This is to remove such impurities as hydrogen, methane, carbon monoxide and water from the coolant. In this system, part of the coolant successively flows first through an oxidation bed of copper oxide and an absorption bed of silica gel, then through activated charcoal or a molecular sieve. The hydrogen and carbon monoxide impurities are absorbed and the dry gas is returned to the main cooling circuit. To lower the hydrogen/water ratio without increasing the hydrogen fraction in the main cooling circuit, some of the hydrogen fraction converted into water is added to the cooling circuit. This is done, inter alia, by bypassing the water produced in the oxidation bed before it enters the absorption bed. The rest of the by-pass circuit, however, also includes an absorption bed with a molecular sieve. This absorbs the oxidized carbon monoxide fraction. In this way, such side effects as the formation of additional methane, carburization of the materials of the by-pass circuit or loss of graphite are avoided. (DG/RF) [de

Smart Multifunctional Coatings for Corrosion Detection and Control in the Aerospace Industry

Science.gov (United States)

Calle, Luz Marina

2015-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

Studies on impurity control and hydrogen pumping with chromium gettering in ISX-B

International Nuclear Information System (INIS)

Mioduszewski, P.; Simpkins, J.E.; Edmonds, P.H.; Isler, R.C.; Lazarus, E.A.; Ma, C.H.; Murakami, M.; Wootton, A.J.

1984-01-01

Chromium gettering has been proven to be a trouble-free and efficient method of surface pumping in tokamaks. The impurity control capabilities are excellent and comparable to that of titanium. The hydrogen uptake is reduced to monolayer quantities on the surface. The expansion of the operating space is similar to that seen with titanium without the disadvantage of strongly increased hydrogen fluxes. Possible applications of chromium gettering are: impurity control in contemporary tokamaks; surface pumping in short pulse DT-burning devices to minimize tritium inventory, and wall conditioning of future large machines prior to operation

Helium gas purity monitor based on low frequency acoustic resonance

Science.gov (United States)

Kasthurirengan, S.; Jacob, S.; Karunanithi, R.; Karthikeyan, A.

1996-05-01

Monitoring gas purity is an important aspect of gas recovery stations where air is usually one of the major impurities. Purity monitors of Katherometric type are commercially available for this purpose. Alternatively, we discuss here a helium gas purity monitor based on acoustic resonance of a cavity at audio frequencies. It measures the purity by monitoring the resonant frequency of a cylindrical cavity filled with the gas under test and excited by conventional telephone transducers fixed at the ends. The use of the latter simplifies the design considerably. The paper discusses the details of the resonant cavity and the electronic circuit along with temperature compensation. The unit has been calibrated with helium gas of known purities. The unit has a response time of the order of 10 minutes and measures the gas purity to an accuracy of 0.02%. The unit has been installed in our helium recovery system and is found to perform satisfactorily.

A simple and rapid method of purification of impure plutonium oxide

International Nuclear Information System (INIS)

Michael, K.M.; Rakshe, P.R.; Dharmpurikar, G.R.; Thite, B.S.; Lokhande, Manisha; Sinalkar, Nitin; Dakshinamoorthy, A.; Munshi, S.K.; Dey, P.K.

2007-01-01

Impure plutonium oxides are conventionally purified by dissolution in HNO 3 in presence of HF followed by ion exchange separation and oxalate precipitation. The method is tedious and use of HF enhances corrosion of the plant equipment's. A simple and rapid method has been developed for the purification of the oxide by leaching with various reagents like DM water, NaOH and oxalic acid. A combination of DM water followed by hot leaching with 0.4 M oxalic acid could bring down the impurity levels in the oxide to the desired level required for fuel fabrication. (author)

Experimental research regarding the corrosion of incoloy-800 and SA 508 cl.2 in the CANDU steam generator

International Nuclear Information System (INIS)

Lucan, D.; Fulger, M.; Savu, G.; Velciu, L.

2004-01-01

Steam generators (SGs) are crucial components of pressurized water reactors. The failure of the steam generator as a result of tube degradation by corrosion has been a major cause of Pressurized Water Reactor (PWR) plant unavailability. Steam generator problems have caused major economic losses in terms of lost electricity production through forced unit outages and, in cases of extreme damage, as additional direct cost for large-scale repair or replacement of steam generators. Steam generator tubes are susceptible to failure by a variety of mechanisms, the vast majority of which are related a corrosion. The feedwater that enters into the steam generators under normal operating conditions is extremely pure, but nevertheless contains low levels (generally in the μg/l concentration range) of impurities such as iron, chloride, sulphate, silicate, etc. When water is converted to steam and exits the steam generator, the non-volatile impurities are left behind. As a result, their concentration in the bulk steam generator water is considerably higher than those in the feedwater. Nevertheless, the concentrations of corrosive impurities are still generally sufficiently low that the bulk water is not significantly aggressive towards steam generator materials. The excellent performance to date of CANDU steam generators can be attributed, in part, to their design and performance characteristics, which typically involve higher recirculation ratios and lower heat fluxes and temperatures. The purpose of this paper consists in assessment of generalized corrosion behaviour of the tubes materials (Incoloy-800) and tubesheet material (carbon steel SA 508 cl.2) at the normal secondary circuit parameters (temperature-260 deg C, pressure-5.1MPa). The testing environment was the demineralized water without impurities, at pH=9.5 regulated with morpholine and ciclohexilamine (all volatile treatment - AVT). The results are presented like micrographies and graphics representing loss of metal

Rotation characteristics of main ions and impurity ions in H-mode tokamak plasma

International Nuclear Information System (INIS)

Kim, J.; Burrell, K.H.; Gohil, P.; Groebner, R.J.; Kim, Y.; St. John, H.E.; Seraydarian, R.P.; Wade, M.R.

1994-01-01

Poloidal and toroidal rotation of the main ions (He 2+ ) and the impurity ions (C 6+ and B 5+ ) in H-mode helium plasmas have been measured via charge exchange recombination spectroscopy in the DIII-D tokamak. It was discovered that the main ion poloidal rotation is in the ion diamagnetic drift direction while the impurity ion rotation is in the electron diamagnetic drift direction, in qualitative agreement with the neoclassical theory. The deduced radial electric field in the edge is of the same negative-well shape regardless of which ion species is used, validating the fundamental nature of the electric field in L-H transition phenomenology

Prompt ignition of a unipolar arc on helium irradiated tungsten

International Nuclear Information System (INIS)

Kajita, Shin; Takamura, Shuichi; Ohno, Noriyasu

2009-01-01

A fibreform nanostructured layer is formed on a tungsten surface by helium plasma bombardment. The helium fluence was of the order of 10 26 m -2 , and the surface temperature and incident ion energy during helium irradiation were, respectively, 1900 K and 75 eV. By irradiating a laser pulse to the surface in the plasma, a unipolar arc, which many people have tried to verify in well-defined experiments, is promptly initiated and continued for a much longer time than the laser pulse width. The laser pulse width (∼0.6 ms) and power (∼5 MJ m -2 ) are similar to the heat load accompanied by type-I edge localized modes (ELMs) in ITER. The unipolar arc is verified from an increase in the floating potential, a moving arc spot detected by a fast camera and arcing traces on the surface. This result suggests that the nanostructure on the tungsten surface formed by the bombardment of helium, which is a fusion product, could significantly change the ignition property of arcing, and ELMs become a trigger of unipolar arcing, which would be a great impurity source in fusion devices. (letter)

Effect of water impurities on stress corrosion cracking in a boiling water reactor

International Nuclear Information System (INIS)

Ljungbery, L.G.; Cubicciotti, D

1985-01-01

A series of stress corrosion tests, including corrosion potential and water chemistry measurements, has been performed in the Swedish Ringhals-1 boiling water reactor. Tests have been run under reactor start-up and reactor power operation with normal reactor water conditions and with alternate water chemistry in which hydrogen is added to the feedwater to suppress stress corrosion cracking. During one alternate water chemistry test, there was significant intergranular corrosion cracking of sensitized stainless specimens. It is shown that nitrate and sulfate, arising from an accidental resin intrusion, are likely causes. Nitrate increases the oxidizing power of the water, and sulfate enhances cracking under oxidizing conditions. During another test under start-up conditions, enhanced transgranular stress corrosion cracking in low alloy steels and possibly initiation of cracking in a nickel base alloy was observed as a result of resin intrusion into the reactor water. The intrusion produced acid and sulfate, which are believed to enhance hydrogen cracking conditions

Investigations of impurity control in JET using fuelling, and interpretation of experiments using the LIM impurity code

International Nuclear Information System (INIS)

Gondhalekar, A.; Stangeby, P.C.; Elder, J.D.

1994-01-01

Inhibition of contamination of the plasma core in JET by edge impurities during high power heating of deuterium plasmas in limiter configuration using fuelling is demonstrated. By injecting deuterium gas during heating, in the presence of a much larger recycling deuterium flux, a reduction of more than a factor of 2 was effected in n z (0)/Φ z , the ratio of central impurity density to impurity influx at the plasma edge. The reduction in n z (0) was obtained without much effect on peak electron temperature and density. Reduction of plasma contamination by gas fuelling was observed also when hot spots formed on the limiter, a condition that without simultaneous gas fuelling culminated in runaway plasma contamination. Detailed analysis of the experiments is undertaken with the purpose of identifying the processes by which plasma contamination was inhibited, employing standard limiter plasma contamination modelling. Processes which might produce the observed impurity inhibiting effects of gas injection include: (a) reduction in impurity production at the limiter; (b) increase in impurity screening in the scrape-off layer; (c) increase in radial impurity transport at the plasma edge; (d) increase in average deuteron flow velocity to the limiter along the scrape-off layer. These are examined in detail using the Monte Carlo limiter impurity transport code LIM. Bearing in mind that uncertainties exist both in the choice of appropriate modelling assumptions to be used and in the measurement of required edge plasma parameters, changes in n z (0)/Φ z by a factor of 2 are at the limit of the present modelling capability. However, comparison between LIM code simulations and measurements of plasma impurity content indicate that the standard limiter plasma contamination model may not be adequate and that other processes need to be added in order to be able to describe the experiments in JET. (author). 24 refs, 2 figs, 8 tabs

The Liquefaction of Hydrogen and Helium Using Small Coolers

International Nuclear Information System (INIS)

Green, Michael A.

2006-01-01

This report discusses the history of the liquefaction of hydrogen and helium using small coolers. This history dates form the 1960's when two stage GM coolers capable of reaching 7 K were used to liquefy helium and hydrogen by suing an added compressor and J-T circuit. Liquefaction using the added circuit failed to become mainstream because the J-T valve and heat exchanger clogged because of impurities in the gas being liquefied. Liquefaction using a GM cooler without an added J-T circuit proved to be difficult because the first stage was not used to pre-cool the gas coming to the second stage of the cooler. Once the gas being liquefied was pre-cooled using the cooler first stage, improvements in the liquefaction rates were noted. The advent of low temperature pulse tube cooler (down to 2.5 K) permitted one to achieve dramatic improvement is the liquefactions rates for helium. Similar but less dramatic improvements are expected for hydrogen as well. Using the PT-415 cooler, one can expect liquefaction rates of 15 to 20 liters per day for helium or hydrogen provided the heat leak into the cooler and the storage vessel is low. A hydrogen liquefier for MICE is presented at the end of this report

Technology for sodium purity control

Energy Technology Data Exchange (ETDEWEB)

Jeong, Ji Young; Kim, B. H.; Kim, T. J. [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-10-01

When sodium is used as heat transfer fluid, the plugging in coolant flow, the corrosion of structure material and the transfer of radioactive material caused by the impurities in sodium are worth considerable. Accordingly, these impurities must be monitored and controlled continuously by sodium purification devices in the heat transfer system which sodium is used as coolant. Sodium purification loop was constructed for the purpose of accumulating the technology for purity control of the coolant, developing and verifying further efficient instruments for sodium purification. The plugging meter and the cold trap is used as the implement for measuring and controlling the oxygen and the hydrogen, the main impurities in sodium coolant. They are capable of excellent performance as the implements which could detect and monitor the impurities to the concentration limit required for nuclear reactor. Sodium purification loop could be used variably according to the experimental purpose. 18 refs., 34 figs., 8 tabs. (Author)

Microencapsulation of Self Healing Agents for Corrosion Control Coatings

Science.gov (United States)

Jolley, S. T.; Li, W.; Buhrow, J. W.; Calle, L. M.

2011-01-01

Corrosion, the environmentally induced degradation of materials, is a very costly problem that has a major impact on the global economy. Results from a 2-year breakthrough study released in 2002 by the U.S. Federal Highway Administration (FHWA) showed that the total annual estimated direct cost associated with metallic corrosion in nearly every U.S. industry sector was a staggering $276 billion, approximately 3.1% of the nation's Gross Domestic Product (GOP). Corrosion protective coatings are widely used to protect metallic structures from the detrimental effects of corrosion but their effectiveness can be seriously compromised by mechanical damage, such as a scratch, that exposes the metallic substrate. The incorporation of a self healing mechanism into a corrosion control coating would have the potential to significantly increase its effectiveness and useful lifetime. This paper describes work performed to incorporate a number of microcapsule-based self healing systems into corrosion control coatings. The work includes the preparation and evaluation of self-healing systems based on curable epoxy, acrylate, and siloxane resins, as well as, microencapsulated systems based on passive, solvent born, healing agent delivery. The synthesis and optimization of microcapsule-based self healing systems for thin coating (less than 100 micron) will be presented.

Corrosion and oxidation of vanadium-base alloys

International Nuclear Information System (INIS)

Loomis, B.A.; Wiggins, G.

1983-10-01

The corrosion of several V-base alloys on exposure at elevated temperatures to helium environments containing hydrogen and/or water vapor are presented. These results are utilized to discuss the consequences of the selection of certain radiation-damage resistant, V-base alloys for structural materials applications in a fusion reactor

Multilayer mirror based monitors for impurity controls in large fusion reactor type devices

International Nuclear Information System (INIS)

Regan, S.P.; May, M.J.; Soukhanovskii, V.; Finkenthal, M.; Moos, H.W.

1995-01-01

Multilayer Mirror (MLM) based monitors are compact, high throughput diagnostics capable of extracting XUV emissions (the wavelength range including the soft-x-ray and the extreme ultraviolet, 10 angstrom to 304 angstrom) of impurities from the harsh environment of large fusion reactor type devices. For several years the Plasma Spectroscopy Group at Johns Hopkins University has investigated the application of MLM based XUV spectroscopic diagnostics for magnetically confined fusion plasmas. MLM based monitors have been constructed for and extensively used on DIII-D, Alcator C-mod, TEXT, Phaedrus-T, and CDX-U tokamaks to study the impurity behavior of elements ranging from He to Mo. On ITER MLM based devices would be used to monitor the spectral line emissions from Li I-like to F I-like charge states of Fe, Cr, and Ni, as well as extractors for the bands of emissions from high Z elements such as Mo or W for impurity controls of the fusion plasma. In addition to monitoring the impurity emissions from the main plasma, MLM based devices can also be adapted for radiation measurements of low Z elements in the divertor. The concepts and designs of these MLM based monitors for impurity controls in ITER will be presented. The results of neutron irradiation experiments of the MLMs performed in the Los Alamos Spallation Radiation Effects Facility (LASREF) at the Los Alamos National Laboratory will also be discussed. These preliminary neutron exposure studies show that the dispersive and reflective qualities of the MLMs were not affected in a significant manner

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 2: Materials considerations. [materials used in boilers and heat exchangers of energy conversion systems for electric power plants using coal

Science.gov (United States)

Thomas, D. E.

1976-01-01

Extensive studies are presented which were carried out on materials behavior in nine advanced energy conversion systems employing coal and coal-derived fuels. The areas of materials behavior receiving particular attention in this regard are: (1) fireside corrosion and erosion in boiler and heat exchanger materials, (2) oxidation and hot corrosion of gas turbine materials, (3) liquid metal corrosion and mass transport, (4) high temperature steam corrosion, (5) compatability of materials with coal slag and MHD seed, (6) reaction of materials with impure helium, (7) allowable stresses for boiler and heat exchanger materials, (8) environmental effects on mechanical properties, and (9) liquid metal purity control and instrumentation. Such information was then utilized in recommending materials for use in the critical components of the power systems, and at the same time to identify materials problem areas and to evaluate qualitatively the difficulty of solving those problems. Specific materials recommendations for critical components of the nine advanced systems under study are contained in summary tables.

Nonlinear Power-Level Control of the MHTGR Only with the Feedback Loop of Helium Temperature

Directory of Open Access Journals (Sweden)

Zhe Dong

2013-02-01

Full Text Available Power-level control is a crucial technique for the safe, stable and efficient operation of modular high temperature gas-cooled nuclear reactors (MHTGRs, which have strong inherent safety features and high outlet temperatures. The current power-level controllers of the MHTGRs need measurements of both the nuclear power and the helium temperature, which cannot provide satisfactory control performance and can even induce large oscillations when the neutron sensors are in error. In order to improve the fault tolerance of the control system, it is important to develop a power-level control strategy that only requires the helium temperature. The basis for developing this kind of control law is to give a state-observer of the MHTGR a relationship that only needs the measurement of helium temperature. With this in mind, a novel nonlinear state observer which only needs the measurement of helium temperature is proposed. This observer is globally convergent if there is no disturbance, and has the L2 disturbance attenuation performance if the disturbance is nonzero. The separation principle of this observer is also proven, which denotes that this observer can recover the performance of both globally asymptotic stabilizers and L2 disturbance attenuators. Then, a new dynamic output feedback power-level control strategy is established, which is composed of this observer and the well-built static state-feedback power-level control based upon iterative dissipation assignment (IDA-PLC. Finally, numerical simulation results show the high performance and feasibility of this newly-built dynamic output feedback power-level controller.

An Atomistic Modeling Study of Alloying Element Impurity Element, and Transmutation Products on the cohesion of A Nickel E5 {001} Twist Grain Boundary

International Nuclear Information System (INIS)

Young, G.A. Jr.; Najafabadi, R.; Strohmayer, W.; Baldrey, D.G.; Hamm, B.; Harris, J.; Sticht, J.; Wimmer, E.

2003-01-01

Atomistic modeling methods were employed to investigate the effects of impurity elements on the metallurgy, irradiation embrittlement, and environmentally assisted cracking of nickel-base alloys exposed to nuclear environments. Calculations were performed via ab initio atomistic modeling methods to ensure the accuracy and reliability of the results. A Griffith-type fracture criterion was used to quantitatively assess the effect of elements or element pairs on the grain boundary cohesive strength. In order of most embrittling to most strengthening, the elements are ranked as: He, Li, S, H, C, Zr, P, Fe, Mn, Nb, Cr, and B. Helium is strongly embrittling (-2.04 eV/atom lowering of the Griffith energy), phosphorus has little effect on the grain boundary (0.1 eV/atom), and boron offers appreciable strengthening (1.03 eV/atom increase in the Griffith energy). Calculations for pairs of elements (H-Li, H-B, H-C, H-P, and H-S) show little interaction on the grain boundary cohesive energy, so that for the conditions studied, linear superposition of elemental effects is a good approximation. These calculations help explain metallurgical effects (e.g. why boron can strengthen grain boundaries), irradiation embrittlement (e.g. how boron transmutation results in grain boundary embrittlement), as well as how grain boundary impurity elements can affect environmentally assisted cracking (i.e. low temperature crack propagation and stress corrosion cracking) of nickel-base alloys

A Review of Field Corrosion Control and Monitoring Techniques of ...

African Journals Online (AJOL)

AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... to make informed decision and timely respond to corrosion threat before failures. Keywords: cathodic protection, corrosion mechanism, control and monitoring, ...

Service life investigations of ball bearings at 1200C in a helium atmosphere

International Nuclear Information System (INIS)

Haas, H.

1984-04-01

The generally known rules for the layout of ball bearings do not yield in the case the bearings run in an helium atmosphere contaminated with impurities in the range of microbars. Therefore the layout of bearings put into action in helium has to be supported by tests carried out in a similar environment and for similar loads. With the aim to support the selection of lubricants and the design of the bearings in regard to the economical point of view, the basic principles of tribology in helium have been compiled and forty ball bearings have been tested at 90 0 C and 120 0 C in helium. The applied loads comply with the usual values in machine construction. The tests show as result that ball bearings suitable for the different fields of applications in helium can be produced by simply exchanging the cages of standardized bearings. Reliable 10 7 revolutions have been obtained for different materials, also for cages made out of soft metals such as lead bronze, suitable in a radiation environment. In addition lubricants have been tested in order to find out the limits of suitability. (orig.) [de

Raman scattering signatures of the unusual vibronic interaction of molecules in liquid helium-3

Energy Technology Data Exchange (ETDEWEB)

Tehver, I., E-mail: imbi.tehver@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Benedek, G. [Donostia International Physics Center (DIPC) and University of the Basque Country (EHU), Paseo de Lardizabal 4, 20018 Donostia/San Sebastian (Spain); Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Hizhnyakov, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

2015-10-16

Highlights: • Theory of resonance Raman scattering (RRS) of molecules in {sup 3}He liquid is proposed. • Fermi excitations give essential contribution to RRS. • RRS spectra of glyoxal molecule in {sup 3}He droplets are calculated. - Abstract: Light scattering in quantum liquid helium-3 may involve a unique mechanism – the creation and annihilation of atom excitations across the Fermi level. The density of states of particle–hole excitations in the low-energy limit is strongly enhanced as compared to that of collective excitations of phonons in helium-3. This makes possible to directly observe Fermi excitations in the resonant Raman scattering (RRS) by {sup 3}He droplets doped by impurity molecules. The RRS spectra essentially depend on the excitation frequency. In case of excitation in the anti-Stokes side of absorption the first order RRS is directly determined by the particle–hole excitations in the vicinity of the impurity molecule and the contribution of phonons mainly given by the localized spherical vibration. The calculations are made for a {sup 3}He droplet doped by a glyoxal molecule.

Impurity-generated non-Abelions

Science.gov (United States)

Simion, G.; Kazakov, A.; Rokhinson, L. P.; Wojtowicz, T.; Lyanda-Geller, Y. B.

2018-06-01

Two classes of topological superconductors and Majorana modes in condensed matter systems are known to date: one in which disorder induced by impurities strongly suppresses topological superconducting gap and is detrimental to Majorana modes, and another where Majorana fermions are protected by a disorder-robust topological superconductor gap. Observation and control of Majorana fermions and other non-Abelions often requires a symmetry of an underlying system leading to a gap in the single-particle or quasiparticle spectra. In semiconductor structures, impurities that provide charge carriers introduce states into the gap and enable conductance and proximity-induced superconductivity via the in-gap states. Thus a third class of topological superconductivity and Majorana modes emerges, in which topological superconductivity and Majorana fermions appear exclusively when impurities generate in-gap states. We show that impurity-enabled topological superconductivity is realized in a quantum Hall ferromagnet, when a helical domain wall is coupled to an s -wave superconductor. As an example of emergence of topological superconductivity in quantum Hall ferromagnets, we consider the integer quantum Hall effect in Mn-doped CdTe quantum wells. Recent experiments on transport through the quantum Hall ferromagnet domain wall in this system indicated a vital role of impurities in the conductance, but left unresolved the question whether impurities preclude generation of Majorana fermions and other non-Abelions in such systems in general. Here, solving a general quantum-mechanical problem of impurity bound states in a system of spin-orbit coupled Landau levels, we demonstrate that impurity-induced Majorana modes emerge at boundaries between topological and conventional superconducting states generated in a domain wall due to proximity to an s superconductor. We consider both short-range disorder and a smooth random potential. The phase diagram of the system is defined by

Particle fueling and impurity control in PDX

International Nuclear Information System (INIS)

Fonck, R.J.; Bell, M.; Bol, K.

1984-12-01

Fueling requirements and impurity levels in neutral-beam-heated discharges in the PDX tokamak have been compared for plasmas formed with conventional graphite rail limiters, a particle scoop limiter, and an open or closed poloidal divertor. Gas flows necessary to obtain a given density are highest for diverted discharges and lowest for the scoop limiter. Hydrogen pellet injection provides an efficient alternate fueling technique, and a multiple pellet injector has produced high density discharges for an absorbed neutral beam power of up to 600 kW, above which higher speeds or more massive pellets are required for penetration to the plasma core. Power balance studies indicate that 30 to 40% of the total input power is radiated while approx. 15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Z/sub eff/ usually rises at the onset of neutral beam injection. Both open divertor plasmas and those formed on a well conditioned water-cooled limiter have Z/sub eff/ less than or equal to 2 at the end of neutral injection. A definitive comparison of divertors and limiters for impurity control purposes requires longer beam pulses or higher power levels than available on present machines

Plasma impurity-control studies in CTX

International Nuclear Information System (INIS)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 μs and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 μs. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver

Plasma impurity-control studies in CTX

Energy Technology Data Exchange (ETDEWEB)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 ..mu..s and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 ..mu..s. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver.

Internal Corrosion Direct Assessment Detection of Water (WP #205)

Science.gov (United States)

2010-12-12

Internal corrosion of natural gas pipelines is the result of interaction between the inside pipe wall and impurities in the product being transported. Such interactions can lead to an overall loss of material thereby thinning the pipe wall and thus r...

The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

International Nuclear Information System (INIS)

Tripathi, J.K.; Novakowski, T.J.; Gonderman, S.; Bharadwaj, N.; Hassanein, A.

2016-01-01

We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He + ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C + ion impurities in He + ion irradiations. For introducing such tiny C + ion impurities, gas mixtures of He and CH 4 have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He + ion (for Mo fuzz growth due to only He + ions) and 100% H + ion (for confirming the significance of tiny 0.04–2.0% H + ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 × 10 24  ions m −2 ), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He + ion irradiation case. Enhancement of C + ion impurities in He + ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C + ion impurity concentrations. Additionally, no fuzz formation for 100% H + ion irradiation at all, were seen (apart from some tiny nano-structuring, in very limited regions). This indicates that there is no significant role of H + ions in Mo fuzz evolutions (at least for such tiny amount, 0.04–2.0% H + ions). The study is significant to understand the behavior of potential high-Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications. - Highlights: • Mo Fuzz evolutions due to low-energy high-flux 100% He + ion irradiation. • Sequential reduction in Mo fuzz evolutions with increasing C + ion impurities in He + ions. • Almost complete prevention of Mo fuzz evolutions for 0.5% C + ion impurity in He + ions. • No Mo fuzz formation for 100% H + ion

Improvement of corrosion resistance in austenitic stainless steel by grain boundary character distribution control

International Nuclear Information System (INIS)

Wang, Yun; Kaneda, Junya; Kasahara, Shigeki; Shigenaka, Naoto

2012-01-01

Strauss test, Coriou test and Huey test were conducted on a Type 316L austenitic stainless steel. Improvement in grain boundary corrosion resistance was verified after raising low Σ coincidence site lattice (CSL) grain boundary (GB) frequency by controlling grain boundary character distribution (GBCD). During crevice corrosion test under gamma-ray irradiation, initiation frequency of GB corrosion after GBCD controlled specimens decreased to 1/10 of GBCD uncontrolled counterpart along with lower depth of corrosion. Stress corrosion cracking (SCC) propagation rate of GBCD controlled specimen decreased to less than 1/2 of GBCD uncontrolled specimen in high temperature and high pressure water. Based on these results, we expect that GBCD control will improve corrosion resistance of austenitic material in a wide range of application and environment. (author)

System design description of forced-convection molten-salt corrosion loops MSR-FCL-3 and MSR-FCL-4

International Nuclear Information System (INIS)

Huntley, W.R.; Silverman, M.D.

1976-11-01

Molten-salt corrosion loops MSR-FCL-3 and MSR-FCL-4 are high-temperature test facilities designed to evaluate corrosion and mass transfer of modified Hastelloy N alloys for future use in Molten-Salt Breeder Reactors. Salt is circulated by a centrifugal sump pump to evaluate material compatibility with LiF-BeF 2 -ThF 4 -UF 4 fuel salt at velocities up to 6 m/s (20 fps) and at salt temperatures from 566 to 705 0 C (1050 to 1300 0 F). The report presents the design description of the various components and systems that make up each corrosion facility, such as the salt pump, corrosion specimens, salt piping, main heaters, salt coolers, salt sampling equipment, and helium cover-gas system, etc. The electrical systems and instrumentation and controls are described, and operational procedures, system limitations, and maintenance philosophy are discussed

The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Gonderman, S.; Bharadwaj, N.; Hassanein, A.

2016-09-15

We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He{sup +} ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C{sup +} ion impurities in He{sup +} ion irradiations. For introducing such tiny C{sup +} ion impurities, gas mixtures of He and CH{sub 4} have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He{sup +} ion (for Mo fuzz growth due to only He{sup +} ions) and 100% H{sup +} ion (for confirming the significance of tiny 0.04–2.0% H{sup +} ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 × 10{sup 24} ions m{sup −2}), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He{sup +} ion irradiation case. Enhancement of C{sup +} ion impurities in He{sup +} ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C{sup +} ion impurity concentrations. Additionally, no fuzz formation for 100% H{sup +} ion irradiation at all, were seen (apart from some tiny nano-structuring, in very limited regions). This indicates that there is no significant role of H{sup +} ions in Mo fuzz evolutions (at least for such tiny amount, 0.04–2.0% H{sup +} ions). The study is significant to understand the behavior of potential high-Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications. - Highlights: • Mo Fuzz evolutions due to low-energy high-flux 100% He{sup +} ion irradiation. • Sequential reduction in Mo fuzz evolutions with increasing C{sup +} ion impurities in He{sup +} ions. • Almost complete prevention of Mo

Numerical modelling of the effect of dry air traces in a helium parallel plate dielectric barrier discharge

Science.gov (United States)

Lazarou, C.; Belmonte, T.; Chiper, A. S.; Georghiou, G. E.

2016-10-01

A validated numerical model developed for the study of helium barrier discharges in the presence of dry air impurities is presented in this paper. The model was used to numerically investigate the influence of air traces on the evolution of the helium dielectric barrier discharge (DBD). The level of dry air used as impurity was in the range from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. The results presented in this study clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities in the mixture. In particular, it was observed that air traces assist the discharge ignition at low concentration levels (~55 ppm), while on the other hand, they increase the burning voltage at higher concentration levels (~1000 ppm). Furthermore, it was found that the discharge symmetry during the voltage cycle highly depends on the concentration of air. For the interpretation of the results, a detailed analysis of the processes that occur in the discharge gap is performed and the main reaction pathways of ion production are described. Thanks to this approach, useful insight into the physics behind the evolution of the discharge is obtained.

Plasma Interactions with Mixed Materials and Impurity Transport

Energy Technology Data Exchange (ETDEWEB)

Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beiersdorfer, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chernov, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frolov, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magee, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rudd, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Umansky, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-28

The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

Plasma Interactions with Mixed Materials and Impurity Transport

International Nuclear Information System (INIS)

Rognlien, T. D.; Beiersdorfer, Peter; Chernov, A.; Frolov, T.; Magee, E.; Rudd, R.; Umansky, M.

2016-01-01

The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

Condensate polisher application for PWR steam generator corrosion control

International Nuclear Information System (INIS)

Sawochka, S.G.; Leibovitz, J.; Siegwarth, D.P.; Pearl, W.L.

1981-01-01

The evolution of corrosion attack modes particularly in recirculating U-tube PWR steam generators has dictated a thorough review of the advantages and disadvantages of condensate polishing. Analytical modeling techniques to qualitatively predict crevice chemistry variations resulting from steam generator bulk water variations have allowed valuable insights to be developed. Modeling results complemented by steam generator and laboratory corrosion data will be employed to set condensate demineralizer effluent specifications consistent with control of steam generator corrosion. Laboratory and plant studies are being performed to demonstrate achievability of necessary effluent specifications. (author)

Impurity radiation from a beam-plasma neutron source

International Nuclear Information System (INIS)

Molvik, A.W.

1995-01-01

Impurity radiation, in a worst case evaluation for a beam-plasma neutron source (BPNS), does not limit performance. Impurities originate from four sources: (a) sputtering from walls by charge exchange or alpha particle bombardment, (b) sputtering from limiters, (c) plasma desorption of gas from walls and (d) injection with neutral beams. Sources (c) and (d) are negligible; adsorbed gas on the walls of the confinement chamber and the neutral beam sources is removed by the steady state discharge. Source (b) is negligible for impinging ion energies below the sputtering threshold (T i ≤ 0.025 keV on tungsten) and for power densities to the limiter within the capabilities of water cooling (30-40 MW/m 2 ); both conditions can be satisfied in the BPNS. Source (a) radiates 0.025 MW/m 2 to the neutron irradiation samples, compared with 5 to 10 MW/m 2 of neutrons; and radiates a total of 0.08 MW from the plasma column, compared with 60 MW of injected power. The particle bombardment that yields source (a) deposits an average of 2.7 MW/m 2 on the samples, within the capabilities of helium gas cooling (10 MW/m 2 ). An additional worst case for source (d) is evaluated for present day 2 to 5 s pulsed neutral beams with 0.1% impurity density and is benchmarked against 2XIIB. The total radiation would increase a factor of 1.5 to ≤ 0.12 MW, supporting the conclusion that impurities will not have a significant impact on a BPN. (author). 61 refs, 7 figs, 2 tabs

EUROCORR 2007 - The European corrosion congress - Progress by corrosion control. Book of Abstracts

International Nuclear Information System (INIS)

2007-01-01

This book of abstracts contains lectures, workshops and posters which were held on the European Corrosion Congress 2007 in Freiburg (Germany). The main topics of the sessions and posters are: 1. Corrosion and scale inhibition; 2. Corrosion by hot gases and combustion products; 3. Nuclear corrosion; 4. Environment sensitive fracture; 5. Surface Science; 6. Physico-chemical methods of corrosion testing; 7. Marine corrosion; 8. Microbial corrosion; 9. Corrosion of steel in concrete; 10. Corrosion in oil and gas production; 11. Coatings; 12. Corrosion in the refinery industry; 13. Cathodic protection; 14. Automotive Corrosion; 15. Corrosion of polymer materials. The main topics of the workshops are: 1. High temperature corrosion in the chemical, refinery and petrochemical industries; 2. Bio-Tribocorrosion; 3. Stress corrosion cracking in nuclear power plants; 4. Corrosion monitoring in nuclear systems; 5. Cathodic protection for marine and offshore environments; 6. Self-healing properties of new surface treatments; 7. Bio-Tribocorrosion - Cost 533/Eureka-ENIWEP-Meeting; 8. Drinking water systems; 9. Heat exchangers for seawater cooling

Corrosion/95 conference papers

International Nuclear Information System (INIS)

Anon.

1995-01-01

The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

Molecular dynamics study of the role of symmetric tilt grain boundaries on the helium distribution in nickel

Science.gov (United States)

Torres, E.; Pencer, J.

2018-04-01

Helium impurities, from either direct implantation or transmutation reactions, have been associated with embrittlement in nickel-based alloys. Helium has very low solubility in nickel, and has been found to aggregate at lattice defects such as vacancies, dislocations, and grain boundaries. The retention and precipitation of helium in nickel-based alloys have deleterious effects on the material mechanical properties. However, the underlying mechanisms that lead to helium effects in the host metal are not fully understood. In the present work, we investigate the role of symmetric tilt grain boundary (STGB) structures on the distribution of helium in nickel using molecular dynamics simulations. We investigate the family of STGBs specific to the 〈 110 〉 tilt axis. The present results indicate that accumulation of helium at the grain boundary may be modulated by details of grain boundary geometry. A plausible correlation between the grain boundary energy and misorientation with the accumulation and mobility of helium is proposed. Small clusters with up to 6 helium atoms show significant interstitial mobility in the nickel bulk, but also become sites for nucleation and grow of more stable helium clusters. High-energy GBs are found mainly populated with small helium clusters. The high mobility of small clusters along the GBs indicates the role of these GBs as fast two-dimensional channels for diffusion. In contrast, the accumulation of helium in large helium clusters at low-energy STGB creates a favorable environment for the formation of large helium bubbles, indicating a potential role for low-energy STGB in promoting helium-induced GB embrittlement.

Improvement of RFX performances by field and impurity control

International Nuclear Information System (INIS)

Buffa, A.; Gnesotto, F.

1995-01-01

The Reverse Field Pinch experiment RFX has been operated since 1992 with the principal objective of extending the knowledge of RFP confinement to larger dimensions and higher plasma currents. Experiments have been run between 500 and 900 kA; confinement parameters are mainly determined by magnetic field quality and plasma density behavior. Significant improvements were obtained by feedback controlling the poloidal field configuration and by reducing the impurities produced by plasma-wall interactions

Corrosion in Supercritical carbon Dioxide: Materials, Environmental Purity, Surface Treatments, and Flow Issues

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Kumar; Anderson, Mark

2013-12-10

The supercritical CO{sub 2} Brayton cycle is gaining importance for power conversion in the Generation IV fast reactor system because of its high conversion efficiencies. When used in conjunction with a sodium fast reactor, the supercritical CO{sub 2} cycle offers additional safety advantages by eliminating potential sodium-water interactions that may occur in a steam cycle. In power conversion systems for Generation IV fast reactors, supercritical CO{sub 2} temperatures could be in the range of 30°C to 650°C, depending on the specific component in the system. Materials corrosion primarily at high temperatures will be an important issue. Therefore, the corrosion performance limits for materials at various temperatures must be established. The proposed research will have four objectives centered on addressing corrosion issues in a high-temperature supercritical CO{sub 2} environment: Task 1: Evaluation of corrosion performance of candidate alloys in high-purity supercritical CO{sub 2}: The following alloys will be tested: Ferritic-martensitic Steels NF616 and HCM12A, austenitic alloys Incoloy 800H and 347 stainless steel, and two advanced concept alloys, AFA (alumina forming austenitic) steel and MA754. Supercritical CO{sub 2} testing will be performed at 450°C, 550°C, and 650°C at a pressure of 20 MPa, in a test facility that is already in place at the proposing university. High purity CO{sub 2} (99.9998%) will be used for these tests. Task 2: Investigation of the effects of CO, H{sub 2}O, and O{sub 2} impurities in supercritical CO{sub 2} on corrosion: Impurities that will inevitably present in the CO{sub 2} will play a critical role in dictating the extent of corrosion and corrosion mechanisms. These effects must be understood to identify the level of CO{sub 2} chemistry control needed to maintain sufficient levels of purity to manage corrosion. The individual effects of important impurities CO, H{sub 2}O, and O{sub 2} will be investigated by adding them

Corrosion and protection of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Ghali, E. [Laval Univ., Quebec City, PQ (Canada). Dept. of Mining and Metallurgy

2000-07-01

The oxide film on magnesium offers considerable surface protection in rural and some industrial environments and the corrosion rate lies between that of aluminum and low carbon steels. Galvanic coupling of magnesium alloys, high impurity content such as Ni, Fe, Cu and surface contamination are detrimental for corrosion resistance of magnesium alloys. Alloying elements can form secondary particles which are noble to the Mg matrix, thereby facilitating corrosion, or enrich the corrosion product thereby possibly inhibiting the corrosion rate. Bimetallic corrosion resistance can be increased by fluxless melt protection, choice of compatible alloys, insulating materials, and new high-purity alloys. Magnesium is relatively insensible to oxygen concentration. Pitting, corrosion in the crevices, filiform corrosion are observed. Granular corrosion of magnesium alloys is possible due to the cathodic grain-boundary constituent. More homogeneous microstructures tend to improve corrosion resistance. Under fatigue loading conditions, microcrack initiation in Mg alloys is related to slip in preferentially oriented grains. Coating that exclude the corrosive environments can provide the primary defense against corrosion fatigue. Magnesium alloys that contain neither aluminum nor zinc are the most SCC resistant. Compressive surface residual stresses as that created by short peening increase SCC resistance. Cathodic polarization or cladding with a SCC resistant sheet alloy are good alternatives. Effective corrosion prevention for magnesium alloy components and assemblies should start at the design stage. Selective surface preparation, chemical treatment and coatings are recommended. Oil application, wax coating, anodizing, electroplating, and painting are possible alternatives. Recently, it is found that a magnesium hydride layer, created on the magnesium surface by cathodic charging in aqueous solution is a good base for painting. (orig.)

Mitigation of corrosion product ingress into SG's

International Nuclear Information System (INIS)

Han, S.H.

1988-01-01

Design and operation experiences to mitigate corrosion product ingress into SGs in Korea nuclear power plants are briefly reviewed. Maintaining the feedwater pH above 9.6 with morpholine seems to contribute significantly to reduction of iron transport to SGs. Measured iron transport rates were 4.8 g/hr/100 MWe at pH 9.8 and 2.8 g/hr/100 MWe at 9.3, respectively. Removal of corrosion products through SG blowdown is very limited. Its removal efficiency at the higher pH plant was in the neighborhood of 10 %. In one of the Korea Nuclear Units, a large amount of sludge piles were found in the middle of tube bundles especially on the cold leg side. Damaged tubes were identified by the multi-frequency eddy current tests and plugged later during the refueling period. Intermittent blowdown-rate increase was tried to enhance ionic impurity removal through SG blowdown. Even though it was not effective against Na, removal other impurity was improved, resulting in prolonged condensate polisher operation periods by 1 - 2 days. Two-bed polisher design, a cation bed followed by a mixed bed, was chosen for future PWR plants to enhance corrosion product filtering capability of the polishers. Condensate pump discharge polishing and divided hot well polishing methods are currently in consideration. (Nogami, K.)

Particle and impurity control in toroidal fusion devices

International Nuclear Information System (INIS)

Wootton, A.J.

1986-01-01

A review of working particle and impurity control techniques used in and proposed for magnetic fusion devices is presented. The requirements of both present-day machines and envisaged fusion reactors are considered. The various techniques which have been proposed are characterized by whether they affect sources, sinks, or fluxes; in many cases a particular method or device can appear in more than one category. Examples are drawn from published results. The solutions proposed for the large devices which will be operating during the next 5 years are discussed

Recent work on graphite corrosion in dragon HTR

International Nuclear Information System (INIS)

Wilkinson, V.J.; Parsons, P.D.; Lind, R.

1976-01-01

Recent studies are described of graphite corrosion in the Dragon reactor as a consequence of a programme of moisture additions to the helium coolant. The pattern of oxidation was significantly different from that expected from out-of-pile studies. Explanations are suggested in terms of flow and pore structure effects. (orig.) [de

Maintenance free gas bearing helium blower for nuclear plant

Science.gov (United States)

Molyneaux, A., Dr; Harris, M., Prof; Sharkh, S., Prof; Hill, S.; de Graaff, T.

2017-08-01

This paper describes the design, testing and operation of novel helium blowers used to recirculate the helium blanketing gas in the nuclear reactor used as a neutron source at the Institut Laue Langevan, Grenoble, France. The laser sintered shrouded centrifugal wheel operates at speeds up to 45000 rpm supported on helium lubricated hydrodynamic spiral groove bearings, and is driven by a sensorless permanent magnet motor. The entire machine is designed to keep the helium gas (polluted by a small amount of D2O) out of contact with any iron or copper materials which would contribute to the corrosion of parts of the circuit. It is designed to have zero maintenance during a lifetime of 40,000 hours of continuous operation. This paper will describe the spiral groove journal and thrust bearings. Design and manufacture of the 1 kW motor and centrifugal wheel will be explained including their CFD and FEA analyses. Measurements of rotor displacement will be presented showing the behaviour under factory testing as well as details of the measured centrifugal wheel and motor performances. Two machines are incorporated into the circuit to provide redundancy and the first blower has been in continuous operation since Jan 2015. The blower was designed, manufactured, assembled and tested in the UK using predominantly UK suppliers.

Corrosion control for low-cost reliability

International Nuclear Information System (INIS)

Anon.

1993-01-01

This conference was held September 19-24, 1993 in Houston, Texas to provide a forum for exchange of state-of-the-art information on corrosion. Topics of interest focus on the following: atmospheric corrosion; chemical process industry corrosion; high temperature corrosion; and corrosion of plant materials. Individual papers have been processed separately for inclusion in the appropriate data bases

Corrosion/96 conference papers

International Nuclear Information System (INIS)

Anon.

1996-01-01

Topics covered by this conference include: cathodic protection in natural waters; cleaning and repassivation of building HVAC systems; worldwide opportunities in flue gas desulfurization; advancements in materials technology for use in oil and gas service; fossil fuel combustion and conversion; technology of corrosion inhibitors; computers in corrosion control--modeling and information processing; recent experiences and advances of austenitic alloys; managing corrosion with plastics; corrosion measurement technology; corrosion inhibitors for concrete; refining industry; advances in corrosion control for rail and tank trailer equipment; CO 2 corrosion--mechanisms and control; microbiologically influenced corrosion; corrosion in nuclear systems; role of corrosion in boiler failures; effects of water reuse on monitoring and control technology in cooling water applications; methods and mechanisms of scale and deposit control; corrosion detection in petroleum production lines; underground corrosion control; environmental cracking--relating laboratory results and field behavior; corrosion control in reinforced concrete structures; corrosion and its control in aerospace and military hardware; injection and process addition facilities; progress reports on the results of reinspection of deaerators inspected or repaired per RP0590 criteria; near 100% volume solids coating technology and application methods; materials performance in high temperature environments containing halides; impact of toxicity studies on use of corrosion/scale inhibitors; mineral scale deposit control in oilfield related operations; corrosion in gas treating; marine corrosion; cold climate corrosion; corrosion in the pulp and paper industry; gaseous chlorine alternatives in cooling water systems; practical applications of ozone in recirculating cooling water systems; and water reuse in industry. Over 400 papers from this conference have been processed separately for inclusion on the data base

Limiter/vacuum system for plasma impurity control and exhaust in tokamaks

International Nuclear Information System (INIS)

Abdou, M.; Brooks, J.; Mattas, R.

1980-01-01

A detailed design of a limiter/vacuum system for plasma impurity control and exhaust has been developed for the STARFIRE tokamak power plant. It is shown that the limiter/vacuum concept is a very attractive option for power reactors. It is relatively simple and inexpensive and deserves serious experimental verification

Automatic kinetic Monte-Carlo modeling for impurity atom diffusion in grain boundary structure of tungsten material

Directory of Open Access Journals (Sweden)

Atsushi M. Ito

2017-08-01

Full Text Available The diffusion process of hydrogen and helium in plasma-facing material depends on the grain boundary structures. Whether a grain boundary accelerates or limits the diffusion speed of these impurity atoms is not well understood. In the present work, we proposed the automatic modeling of a kinetic Monte-Carlo (KMC simulation to treat an asymmetric grain boundary structure that corresponds to target samples used in fusion material experiments for retention and permeation. In this method, local minimum energy sites and migration paths for impurity atoms in the grain boundary structure are automatically found using localized molecular dynamics. The grain boundary structure was generated with the Voronoi diagram. Consequently, we demonstrate that the KMC simulation for the diffusion process of impurity atoms in the generated grain boundary structure of tungsten material can be performed.

Corrosion control of carbon steel radioactive-liquid storage tanks

International Nuclear Information System (INIS)

Chang, Ji Young.

1997-05-01

As the West Valley Demonstration Project (WVDP) continues vitrification operation and begins decontamination activities, it is vital to continue to maintain the integrity of the high-level waste tanks and prevent further corrosion that may disrupt the operation. This report describes the current operational status and some corrosion concerns with corresponding control measure recommendations. 14 refs., 5 figs., 6 tabs

Effect of Water Chemistry Variations on Corrosion of Zr-Alloys for BWR Applications

International Nuclear Information System (INIS)

Kim, Young-Jin; Yang- Lin, Pi; Lutz, Dan; Kucuk, Aylin; Cheng, Bo

2012-09-01

Two reference water chemistry conditions (60 ppb Zn and 60 μg/cm 2 Pt/Rh with either 500 ppb O 2 and 500 ppb H 2 O 2 , or 150 ppb H 2 ) were chosen for testing at 300 deg. C in refreshed autoclaves. For each reference water chemistry, the potential effects due to three chemical impurities of interest to BWRs (33 ppm Na, 10 ppm Li, and 10 ppm EHC fluid) were evaluated. Zircaloy-2 and GNF-Ziron (a Zr-based alloy with higher Fe additions than Zircaloy-2) cladding tubes were tested and the effects of tubing process variation and pre-filming were investigated. Tested channel materials included Zircaloy-2, Zircaloy-4, GNF-Ziron and NSF (a Zr-based alloy with Sn, Nb and Fe additions). The corrosion weight gain and hydrogen absorption were measured up to 12 months of exposure for a given water chemistry condition. Tests under 150 ppb H 2 based water chemistry, with or without chemical impurities, generally resulted in greater amounts of corrosion after 12 month exposure compared with 500 ppb O 2 and 500 ppb H 2 O 2 based water chemistries. Of the added chemical impurities, only 33 ppm Na addition produced slightly increased corrosion. Under various test conditions, the presence of a thin pre-film resulted in some initial corrosion benefits, but the benefits were no longer evident after 12 months exposure; however, slight hydrogen benefits remained. For GNF-Ziron cladding, hydrogen absorption was generally lower compared with similarly processed Zircaloy-2 under 150 ppb H 2 based water chemistry, when corrosion was generally higher. Of the channel material tested, NSF developed the lowest level of hydrogen absorption, particularly under 150 ppb H 2 based water chemistries. (authors)

Overview of impurity control and wall conditioning in NSTX

International Nuclear Information System (INIS)

Kugel, H.W.; Maingi, R.; Wampler, W.; Barry, R.E.; Bell, M.; Blanchard, W.; Gates, D.; Johnson, D.; Kaita, R.; Kaye, S.; Maqueda, R.; Menard, J.; Menon, M.M.; Mueller, D.; Ono, M.; Paul, S.; Peng, Y-K.M.; Raman, R.; Roquemore, A.; Skinner, C. H.; Sabbagh, S.; Stratton, B.; Stutman, D.; Wilson, J. R.; Zweben, S.

2000-01-01

The National Spherical Torus Experiment (NSTX) started plasma operations i n February 1999. In the first extended period of experiments, NSTX achieved high current, inner wall limited, double null, and single null plasma discharges, initial Coaxial Helicity Injection, and High Harmonic Fast Wave results. As expected, discharge reproducibility and performance were strongly affected by wall conditions. In this paper, the authors describe the internal geometry, and initial plasma discharge, impurity control, wall conditioning, erosion, and deposition results

Power and particle control for ITER

Energy Technology Data Exchange (ETDEWEB)

Cohen, S A; Cummings, J; Post, D E; Redi, M H [Princeton Univ., NJ (USA). Plasma Physics Lab.; Braams, B J [New York Univ., NY (USA). Courant Inst. of Mathematical Sciences; Brooks, J [Argonne National Lab., IL (USA); Engelmann, F; Pacher, G W; Pacher, H D [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.). NET Design Team; Harrison, M; Hotston, E [AEA Fusion, Culham (UK).

1990-12-15

Achievement of ITER's objectives, long-pulse ignited operation and nuclear component testing in quasi-steady-state, requires exhaust of power and helium ash, control of impurity content, and long lifetimes for plasma-facing components. In this paper we describe the data base and modeling results used to extrapolate present edge plasma parameters to ITER. Particular emphasis has been given to determining the uncertainties in predicted divertor performance. These analyses have been applied to four typical scenarios: A1 (ignited, reference Physics Phase), B1 (long pulse, hybrid, Technology Phase), B6 (steady-state, Technology Phase, impurity seeded) and B4 (steady-state, Technology Phase). 43 refs., 3 tabs.

Helium turbo-expander with an alternator

International Nuclear Information System (INIS)

Akiyama, Yoshitane

1980-01-01

Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

Corrosion/94 conference papers

International Nuclear Information System (INIS)

Anon.

1994-01-01

The approximately 500 papers from this conference are divided into the following sections: Rail transit systems--stray current corrosion problems and control; Total quality in the coatings industry; Deterioration mechanisms of alloys at high temperatures--prevention and remediation; Research needs and new developments in oxygen scavengers; Computers in corrosion control--knowledge based system; Corrosion and corrosivity sensors; Corrosion and corrosion control of steel reinforced concrete structures; Microbiologically influenced corrosion; Practical applications in mitigating CO 2 corrosion; Mineral scale deposit control in oilfield-related operations; Corrosion of materials in nuclear systems; Testing nonmetallics for life prediction; Refinery industry corrosion; Underground corrosion control; Mechanisms and applications of deposit and scale control additives; Corrosion in power transmission and distribution systems; Corrosion inhibitor testing and field application in oil and gas systems; Decontamination technology; Ozone in cooling water applications, testing, and mechanisms; Corrosion of water and sewage treatment, collection, and distribution systems; Environmental cracking of materials; Metallurgy of oil and gas field equipment; Corrosion measurement technology; Duplex stainless steels in the chemical process industries; Corrosion in the pulp and paper industry; Advances in cooling water treatment; Marine corrosion; Performance of materials in environments applicable to fossil energy systems; Environmental degradation of and methods of protection for military and aerospace materials; Rail equipment corrosion; Cathodic protection in natural waters; Characterization of air pollution control system environments; and Deposit-related problems in industrial boilers. Papers have been processed separately for inclusion on the data base

Pressurized helium II-cooled magnet test facility

International Nuclear Information System (INIS)

Warren, R.P.; Lambertson, G.R.; Gilbert, W.S.; Meuser, R.B.; Caspi, S.; Schafer, R.V.

1980-06-01

A facility for testing superconducting magnets in a pressurized bath of helium II has been constructed and operated. The cryostat accepts magnets up to 0.32 m diameter and 1.32 m length with current to 3000 A. In initial tests, the volume of helium II surrounding the superconducting magnet was 90 liters. Minimum temperature reached was 1.7 K at which point the pumping system was throttled to maintain steady temperature. Helium II reservoir temperatures were easily controlled as long as the temperature upstream of the JT valve remained above T lambda; at lower temperatures control became difficult. Positive control of the temperature difference between the liquid and cold sink by means of an internal heat source appears necessary to avoid this problem. The epoxy-sealed vessel closures, with which we have had considerable experience with normal helium vacuum, also worked well in the helium II/vacuum environment

Treatment screening for internal corrosion control of PETROBRAS oil pipelines; Selecao de tratamento para controle da corrosao interna de oleodutos da PETROBRAS

Energy Technology Data Exchange (ETDEWEB)

Andrade, Cynthia de Azevedo; Muller, Eduardo Gullo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Antunes, Warlley Ligorio; Shioya, Nilce Hiromi; Salvador, Angelica Dias [PETROBRAS, RJ (Brazil). Unidade de Negocios da Bacia de Campos

2005-07-01

The use of corrosion inhibitors is spread out in oil and gas industry and is the most common methodology to control pipeline internal corrosion. However, their effectiveness depends on the pipeline material, inhibitor composition, flow type and scale characteristics. When a pipeline has heavy scale deposits, thick bacterial biofilm, or oxygen contamination, the corrosion control via filmic inhibitors is not effective. So, the only way to control internal corrosion of an oil pipeline is to primary identifies the corrosive agent and the main corrosion mechanism. The monitoring of the inhibitor efficiency and the determination of minimal residual concentration to prevent corrosion, are also fundamental. In this paper, is presented the criteria used to identify the main corrosion mechanism of oil pipelines, the treatment proposed in each case and the techniques employed in real time corrosion monitoring. (author)

Review of hot corrosion of thermal barrier coatings of gas turbine

Directory of Open Access Journals (Sweden)

LIU Yongbao

2017-03-01

Full Text Available The review was done in order to make clear the problem of the hot corrosion of the Thermal Barrier Coatings(TBCsduring gas turbine serving. This paper summarizes the factors resulting from the hot corrosion of TBCs during turbine service and classifies methods for enhancing the corrosive resistance of TBCs. A prospective methodology for improving corrosion resistance is also formulated. The main types of corrosion coating include phase reaction, oxidizing of the bond coating, salt-fog corrosion, CMAS corrosion and fuel impurity corrosion. So far, methods for improving the corrosion resistance of TBCs include developing new coating materials, anticorrosive treatment on the surface of TBCs, modifying the stacking configuration and improving the cleansing functions of the gas turbines. In the future, developing new materials with excellent performance will still be the main direction for boosting the improvement of the hot corrosion resistance of TBCs. Simultaneously, improving the tacking configuration and nanotechnology of TBC coatings are potential approaches for improving corrosion resistance. With the development of a Ceramic Matrix Composite (CMC, the focus of the hot corrosion of TBCs may turn to that of Environmental Barrier Coatings (EBCs.

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

Corrosion control in nuclear fuel reprocessing

International Nuclear Information System (INIS)

Steele, D.F.

1986-01-01

This article looks in detail at tribology-related hazards of corrosion in irradiated fuel reprocessing plants and tries to identify and minimize problems which could contribute to disaster. First, the corrosion process is explained. Then the corrosion aspects at each of four stages in reprocessing are examined, with particular reference to oxide fuel reprocessing. The four stages are fuel receipt and storage, fuel breakdown and dissolution, solvent extraction and product concentration and waste management. Results from laboratory and plant corrosion trails are used at the plant design stage to prevent corrosion problems arising. Operational procedures which minimize corrosion if it cannot be prevented at the design stage, are used. (UK)

Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD

Energy Technology Data Exchange (ETDEWEB)

Mikkelsen, David R. [PPPL; Tanaka, K. [NIFS; Nunami, M. [NIFS; Watanabe, T-H. [Nagoya University; Sugama, H. [NIFS; Yoshinuma, M. [NIFS; Suzuki, Y. [NIFS; Goto, M. [NIFS; Morita, S. [NIFS; Wieland, B. [NIFS; Yamada, I. [NIFS; Yashura, R. [NIFS; Akiyama, T. [NIFS; Pablant, Novimir A. [PPPL

2014-04-01

Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

NASA's Beachside Corrosion Test Site and Current Environmentally Friendly Corrosion Control Initiatives

Science.gov (United States)

Russell, Richard W.; Calle, Luz Marina; Johnston, Frederick; Montgomery, Eliza L.; Curran, Jerome P.; Kolody, Mark R.

2013-01-01

NASA began corrosion studies at the Kennedy Space Center (KSC) in 1966 during the Gemini/Apollo Programs with the evaluation of long-term corrosion protective coatings for carbon steel. KSC's Beachside Corrosion Test Site (BCTS), which has been documented by the American Society of Materials (ASM) as one of the most corrosive, naturally occurring, environments in the world, was established at that time. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pad were rendered even more severe by the acid ic exhaust from the solid rocket boosters. In the years that followed, numerous studies have identified materials, coatings, and maintenance procedures for launch hardware and equipment exposed to the highly corrosive environment at the launch pad. This paper presents a historical overview of over 45 years of corrosion and coating evaluation studies and a description of the BCTS's current capabilities. Additionally, current research and testing programs involving chromium free coatings, environmentally friendly corrosion preventative compounds, and alternates to nitric acid passivation will be discussed.

Studies of the fluorescent excited state of impurities in ionic crystals

International Nuclear Information System (INIS)

Romestain, Robert

1972-01-01

The author of this research thesis first presents experimental methods used in this research: principles (recall on the optical spectrum of an impurity in a solid, use of fluorescence polarization) and techniques (sample preparation, liquid helium cryostat, application of a disturbance, optical detection). Then, he reports the study of the Mn ++ ion in a tetrahedron crystalline field, the study of the Jahn Teller effect on the excited state of the F + centre in CaO, and the study by double resonance of a specific excited state of this same centre in CaO

THE CORROSION CONTROL-WATER QUALITY SPIDER WEB

Science.gov (United States)

This presentation provides an overview of new research results and emerging research needs with respect to both corrosion control issues, (lead, copper, iron) and to issues of inorganic contaminants that can form or accumulate in distribution system, water, pipe scales and distri...

Evaluation of the current status of hydrogen embrittlement and stress-corrosion cracking in steels

Energy Technology Data Exchange (ETDEWEB)

Moody, N.R.

1981-12-01

A review of recent studies on hydrogen embrittlement and stress-corrosion cracking in steels shows there are several critical areas where data is either ambiguous, contradictory, or non-existent. A relationship exists between impurity segregation and hydrogen embrittlement effects but it is not known if the impurities sensitize a preferred crack path for hydrogen-induced failure or if impurity and hydrogen effects are additive. Furthermore, grain boundary impurities may enhance susceptibility through interactions with some environments. Some studies show that an increase in grain size increases susceptibility; at least one study shows an opposite effect. Recent work also shows that fracture initiates at different locations for external and internal hydrogen environments. How this influences susceptibility is unknown.

Helium exhaust and forced flow effects with both-leg pumping in W-shaped divertor of JT-60U

International Nuclear Information System (INIS)

Sakasai, A.; Takenaga, H.; Higashijima, S.; Kubo, H.; Nakano, T.; Tamai, H.; Sakurai, S.; Akino, N.; Fujita, T.; Asakura, N.; Itami, K.; Shimizu, K.

2001-01-01

The W-shaped divertor of JT-60U was modified from inner-leg pumping to both-leg pumping. After the modification, the pumping rate was improved from 3% with inner-leg pumping to 5% with both-leg pumping in a divertor-closure configuration, which means both separatrixes close to the divertor slots. Efficient helium exhaust was realized in the divertor-closure configuration with both-leg pumping. A global particle confinement time of τ* He =0.4s and τ* He /τ E =3 was achieved in attached ELMy H-mode plasmas. The helium exhaust efficiency with both-leg pumping was extended by 45% as compared with inner-leg pumping. By using central helium fueling with He-beam injection, the helium removal from the core plasma inside the internal transport barrier (ITB) in reversed shear plasmas in the divertor-closure configuration was investigated for the first time. The helium density profiles inside the ITB were peaked as compared with those in ELMy H-mode plasmas. In the case of low recycling divertor, it was difficult to achieve good helium exhaust capability in reversed shear plasmas with ITB. However, the helium exhaust efficiency was improved with high recycling divertor. Carbon impurity reduction was observed by the forced flow with gas puff and effective divertor pumping. (author)

CALPHAD simulation of the Mg–(Mn, Zr)–Fe system and experimental comparison with as-cast alloy microstructures as relevant to impurity driven corrosion of Mg-alloys

Energy Technology Data Exchange (ETDEWEB)

Gandel, D.S., E-mail: darren.gandel@monash.edu [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Easton, M.A. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Gibson, M.A. [CAST Cooperative Research Centre (Australia); CSIRO Process Science and Engineering, Clayton, VIC 3168 (Australia); Birbilis, N. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

2014-02-14

Four Mg alloys with variations in the ratio of Mn, Zr and Fe additions were cast and their microstructures analysed via electron microscopy. Thermodynamic calculations of the expected phases using PANDAT were evaluated with actual as-cast microstructures. Some of the as-cast alloys did appear to form phases similar to those anticipated from the PANDAT calculations. Furthermore, there was a new Mn–Fe particle interaction observed that was not predicted, but which is posited to be responsible for the increase in corrosion resistance among Mn containing Mg alloys with Fe impurities. The experimental work herein has been shown to be invaluable in the understanding of this practically important system with sparingly soluble Fe and its potential influence on the corrosion of Mg alloys. - Highlights: • Alloy microstructure of the Mg-(Mn,Zr, Fe) system was analysed and reported. • CALPHAD analysis was used in conjunction with traditional SEM analysis techniques in this study. • A proposed Mn–Fe interaction within Mg has been observed for the first time. • Experimental validation of calculated phases is required to understand the effect of Mn and Zr on Mg.

Electro chemical studies on stress corrosion cracking of Incoloy-800 in caustic solution, part I: As received samples

Directory of Open Access Journals (Sweden)

Dinu Alice

2005-01-01

Full Text Available Many non-volatile impurities accidentally introduced into the steam generator tend to Concentrate on its surface in restricted flow areas. In this way these impurities can lead to stress corrosion cracking (SCC on stressed tubes of the steam generator. Such impurities can be strong alkaline or acid solutions. To evaluate the effect of alkaline concentrated environments on SCC of steam generator tubes, the tests were con ducted on stressed samples of Incoloy-800 in 10% NaOH solution. To accelerate the SCC process, stressed specimens were anodically polarised in a caustic solution in an electro chemical cell. The method of stressing of Incoloy-800 tubes used in our experiments was the C-ring. Using the cathodic zone of the potentiodynamic curves it was possible to calculate the most important electrochemical parameters: the corrosion current, the corrosion rate, and the polarization resistance. We found that the value of the corrosion potential to initiate the SCC microcracks was -100 mV. The tested samples were examined using the metallographic method. The main experimental results showed that the in crease of the stress state promoted the in crease of the SCC susceptibility of Incoloy-800 samples tested under the same conditions, and that the length of the SCC-type microcracks in creased with the growth of the stress value.

Determination of the corrosion mechanisms of high level waste containing glass

International Nuclear Information System (INIS)

Conradt, R.; Roggendorf, H.

1985-01-01

The purpose of the reported work was to determine the corrosion behaviour of the inactive HLW glass SM 58 LW 11 in Q-solution at temperatures up to 200 0 C and elevated pressures up to 13 MPa. In particular, a parametric study on the effects of time, temperature, pressure, crystallization, metallic impurities a.o. was performed. Further tests helped to identify the rate determining steps in the entire process and the most likely long-term corrosion law. (orig./RB)

Study of the morphology of corrosion features of natural graphite oxidised by dry and humid air

International Nuclear Information System (INIS)

Senevat, Jean

1965-12-01

The author reports a study which aimed at highlighting the morphology differences between corrosion features which affect flakes of natural graphite oxidised by dry air and by humid air. The study is based on observations made by optical and transmission electronic microscopy, this last one being performed on replicates. As the so-called 'Hennig' replicates did not result in a sufficient resolution of corrosion feature details, another method has been developed. Three classes of samples (in relationship with the rate of impurities present in samples) have been studied. Flakes have thus been sorted and each flake has then been oxidised at different wear rates. This highlights the influence of damages created by impurities in the lattice [fr

Pipeline corrosion prevention by pH stabilization or corrosion inhibitors

Energy Technology Data Exchange (ETDEWEB)

Nyborg, Rolf [Institute for Energy Technology, Oslo (Norway)

2009-07-01

In many offshore oil and gas projects the pipeline costs are a considerable part of the investment and can become prohibitively high if the corrosivity of the fluid necessitates the use of corrosion resistant alloys instead of carbon steel. Development of more robust and reliable methods for internal corrosion control can increase the application range of carbon steel and therefore have a large economic impact. Corrosion control of carbon steel pipelines has traditionally often been managed by the use of corrosion inhibitors. The pH stabilization technique has been successfully used for corrosion control of several large wet gas pipelines in the last years. This method has advantages over film forming corrosion inhibitors when no or little formation water is produced. The use of corrosion inhibitors in multiphase pipelines implies several challenges which are not fully accounted for in traditional corrosion inhibitor testing procedures. Specialized test procedures have been developed to take account for the presence of emulsions dispersions and sand and clay particles in corrosion inhibitor testing. (author)

Nucleation path of helium bubbles in metals during irradiation

International Nuclear Information System (INIS)

Morishita, Kazunori

2008-01-01

Thermodynamical formalization is made for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available or evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion divertor materials where helium particles with low energy are directly implanted. Calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barrier without helium. With the proposed thermodynamical formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte-Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He , N V ) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the number of helium atoms and vacancies in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion. (author)

Real Time Implementation of Incremental Fuzzy Logic Controller for Gas Pipeline Corrosion Control

Directory of Open Access Journals (Sweden)

Gopalakrishnan Jayapalan

2014-01-01

Full Text Available A robust virtual instrumentation based fuzzy incremental corrosion controller is presented to protect metallic gas pipelines. Controller output depends on error and change in error of the controlled variable. For corrosion control purpose pipe to soil potential is considered as process variable. The proposed fuzzy incremental controller is designed using a very simple control rule base and the most natural and unbiased membership functions. The proposed scheme is tested for a wide range of pipe to soil potential control. Performance comparison between the conventional proportional integral type and proposed fuzzy incremental controller is made in terms of several performance criteria such as peak overshoot, settling time, and rise time. Result shows that the proposed controller outperforms its conventional counterpart in each case. Designed controller can be taken in automode without waiting for initial polarization to stabilize. Initial startup curve of proportional integral controller and fuzzy incremental controller is reported. This controller can be used to protect any metallic structures such as pipelines, tanks, concrete structures, ship, and offshore structures.

Al-based anti-corrosion and T-permeation barrier development for future DEMO blankets

International Nuclear Information System (INIS)

Krauss, W.; Konys, J.; Holstein, N.; Zimmermann, H.

2011-01-01

In the Helium-Cooled-Liquid-Lead (HCLL) design of Test-Blanket-Modules (TBM's) for a future fusion power plant Pb-15.7Li is used as liquid breeder which is in direct contact with the structure material, e.g. EUROFER steel. Compatibility testing showed that high corrosion attack appears and that the dissolved steel components form precipitates with a high risk of system blockages. A reliable operation needs coatings as corrosion barriers. The earlier developed Hot-Dip Aluminisation (HDA) process has shown that Al-based scales can act as anti-corrosion as well as T-permeation barriers. Meanwhile two advanced electro-chemically based processes for deposition of Al-scales were successfully developed. The first (ECA = Electro-Chemical Al-deposition) is working with an organic electrolyte and the second one (ECX = Electro-Chemical-X-metal-deposition) is based on ionic liquids. Coatings in the μm-range were deposited homogeneously with exact controllable thicknesses. Metallurgical investigations showed the successful generation of protective scales and compatibility testing demonstrated the barrier function.

Al-based anti-corrosion and T-permeation barrier development for future DEMO blankets

Energy Technology Data Exchange (ETDEWEB)

Krauss, W., E-mail: wolfgang.krauss@kit.edu [Karlsruhe Institute of Technology, Hermann von Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Konys, J.; Holstein, N.; Zimmermann, H. [Karlsruhe Institute of Technology, Hermann von Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2011-10-01

In the Helium-Cooled-Liquid-Lead (HCLL) design of Test-Blanket-Modules (TBM's) for a future fusion power plant Pb-15.7Li is used as liquid breeder which is in direct contact with the structure material, e.g. EUROFER steel. Compatibility testing showed that high corrosion attack appears and that the dissolved steel components form precipitates with a high risk of system blockages. A reliable operation needs coatings as corrosion barriers. The earlier developed Hot-Dip Aluminisation (HDA) process has shown that Al-based scales can act as anti-corrosion as well as T-permeation barriers. Meanwhile two advanced electro-chemically based processes for deposition of Al-scales were successfully developed. The first (ECA = Electro-Chemical Al-deposition) is working with an organic electrolyte and the second one (ECX = Electro-Chemical-X-metal-deposition) is based on ionic liquids. Coatings in the {mu}m-range were deposited homogeneously with exact controllable thicknesses. Metallurgical investigations showed the successful generation of protective scales and compatibility testing demonstrated the barrier function.

Control of molten salt corrosion of reduced activation steel for fusion applications by metallic beryllium

International Nuclear Information System (INIS)

Calderoni, P.; Sharpe, P.; Nishimura, H.; Terai, T.

2007-01-01

Full text of publication follows: In 2001 the INL started a research program as a part of the 2. Japan/US Program on Irradiation Tests for Fusion Energy Research (JUPITER-II collaboration) aimed at the characterization of the 2LiF-BeF2 (Flibe) molten salt as a breeder and coolant material for fusion applications. A key objective of the work was to demonstrate chemical compatibility between Flibe and potential fusion structural materials once suitable fluoride potential control methods are established. A series of tests performed at INL demonstrated that this can be achieved by contacting the salt with metallic beryllium, and the results have been published in recent years. A further step was to expose two specimens of low activation ferritic/martensitic steel 9Cr-2W JLF-1 to static corrosion tests that include an active corrosion agent (hydrofluoric gas) and fluoride potential control (metallic Be) at 530 C, and the results of the tests are presented in this paper. The specimen and a beryllium rod were simultaneously immersed in the molten salt through gas tight fittings mounted on risers extending from the top lid of the test vessel; the beryllium rod was extracted after 5 hours, while the sample was left in the salt for 250 hours during which salt samples were withdrawn from the melt at fixed intervals. A diagnostic system based on the measurement of reacting HF through on-line titration was coupled with the analysis of metallic components in the salt samples that were dissolved and analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Impurity levels of oxygen, nitrogen and carbon were determined from pieces of the solidified melt using Leco analytical systems. The results confirmed the expected correlation of the HF recovery with the concentration of metallic elements dissolved in the salt because of specimen corrosion. The metals concentration falls below the detectable limit when the beryllium rod is inserted and increases when the

Problems of technology and corrosion in sodium coolant and cover gas

International Nuclear Information System (INIS)

Kuenstler, K.; Ullmann, H.

1977-07-01

The meeting encloses the following themes: (i) Reactions in the system sodium-steel-cover gas (ii) Corrosion behaviour of structural and cladding materials (iii) Determination of impurities in sodium and cover gas (iv) Technology of sodium and cover gas (v) Testing equipments (vi) Safety problems

Thirty years of screw compressors for helium; Dreissig Jahre Schraubenkompressoren fuer Helium

Energy Technology Data Exchange (ETDEWEB)

Wahl, H. [Kaeser Kompressoren GmbH, Coburg (Germany). Technisches Buero/Auftragskonstruktion

2007-07-01

KAESER helium compressors, as well as their other industrial compressors, will be further developed with the intention to improve the availability and reliability of helium liquefaction systems. Further improvement of compressor and control system efficiency will ensure a low and sustainable operating cost. Fast supply of replacement parts with several years of warranty is ensured by a world-wide distribution system and is also worked on continuously. (orig.)

The behaviour of impurities in a steady-state DT gas-blanket reactor

International Nuclear Information System (INIS)

Markvoort, J.A.

1975-11-01

A four-fluid model of a cylindrical steady-state DT gas-blanket reactor is analysed. The four fluids are electrons, deuterium-tritium, helium and a high -Z impurity. The behaviour of the plasma is described by the multifluid MHD-equations which are numerically solved with the aid of a Runge Kutta method. Whether impurities tend to concentrate on the axis is found to depend on how, in the collision term, the Nernst effect is taken into account. In order to show the influence of the Nernst terms arising from electron-ion collisions and the Nernst terms due to ion-ion collisions separately, the thermal force is dealt with in two ways. In model A, only the contribution from electron-ion collisions was considered. The computer calculations show that the impurities have their maximum concentration on the axis. A theoretical analysis explains this result. In model B, which is more realistic, these ion-ion collisions are included. The computer calculations as well as the theoretical analysis show that the influence of the thermoforce due to ion-ion collisions on the density profiles dominates over the force due to electron collisions, and lead to a minimum in the impurity density on the axis. As in model A, the analytical analysis yields relationships between the various density profiles and the temperature profile

Highly corrosion resistant zirconium based alloy for reactor structural material

International Nuclear Information System (INIS)

Ito, Yoichi.

1996-01-01

The alloy of the present invention is a zirconium based alloy comprising tin (Sn), chromium (Cr), nickel (Ni) and iron (Fe) in zirconium (Zr). The amount of silicon (Si) as an impurity is not more than 60ppm. It is preferred that Sn is from 0.9 to 1.5wt%, that of Cr is from 0.05 to 0.15wt%, and (Fe + Ni) is from 0.17 to 0.5wt%. If not less than 0.12wt% of Fe is added, resistance against nodular corrosion is improved. The upper limit of Fe is preferably 0.40wt% from a view point of uniform suppression for the corrosion. The nodular corrosion can be suppressed by reducing the amount of Si-rich deposition product in the zirconium based alloy. Accordingly, a highly corrosion resistant zirconium based alloy improved for the corrosion resistance of zircaloy-2 and usable for a fuel cladding tube of a BWR type reactor can be obtained. (I.N.)

Effects of nitrogen and nitrogen getters in lithium on the corrosion of type 316 stainless steel

International Nuclear Information System (INIS)

Tortorelli, P.F.; DeVan, J.H.; Selle, J.E.

1979-01-01

This paper presents preliminary results on the corrosion of type 316 stainless steel in nitrogen-contaminated lithium. Nitrogen is a principal interstitial impurity in lithium and has a significant detrimental effect on compatibility, while O, H, and C in lithium do not enhance corrosion of type 316 stainless steel. Because of this, there is a need to understand the corrosion mechanisms and kinetics associated with nitrogen-induced attack in lithium. Results from experiments with getters in nitrogen-contaminated lithium are also reported

Contribution to the study of solid helium-3 by nuclear magnetic resonance; Contribution a l'etude de l'helium trois solide par resonance magnetique nucleaire

Energy Technology Data Exchange (ETDEWEB)

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

1968-07-01

Due to the unusually large zero point motion of helium three atoms in the solid, the overlap of the atomic wave functions is very important. As a consequence, there are exchange interactions, the theoretical calculation and the experimental measurement of which are discussed. Nuclear magnetic resonance is especially well suited for the latter.A detailed theory is given for both exchange narrowing and Zeeman-exchange cross relaxation, which phenomena are used to measure the exchange interaction as a function of molar volume. The alignment temperature is thus known; it goes down when the pressure goes up and is never higher than three milli degrees. An influence of helium four impurities on the exchange interactions between helium three atoms which are neighbours of the substitutional He is shown. (author) [French] Par suite de l'amplitude exceptionnelle des mouvements de point zero dans l'helium trois solide, le recouvrement des fonctions d'onde atomiques est tres important. Il en resulte des interactions d' echange dont on discute l'evaluation theorique et la mise en evidence experimentale. Cette derniere peut se faire par resonance magnetique; on etudie theoriquement les phenomenes de retrecissement par echange et de relaxation Zeeman-echange que l'on met a profit pour determiner les interactions d'echange en fonction du volume molaire. On en deduit que la temperature d'alignement nucleaire diminue quand on comprime le solide et est au plus de 3x10{sup -3} K. L'influence des impuretes d'helium quatre sur les interactions d'echange entre atomes {sup 3}He voisins de {sup 4}He est mise en evidence. (auteur)

Galvanic corrosion of metals and coatings when coupled to uranium in severe environments

International Nuclear Information System (INIS)

Winkle, J.R.; Childs, E.L.

1982-01-01

The results of galvanic testing were varied in each environment. The position of metals in the galvanic series was not fixed, but changed with environment. In all cases where high general and galvanic corrosion rates were observed, the conditions of potential, pH, and impurity content could be correlated with regions of oxide surface film instability outlined by Pourbaix Diagrams. The majority of the severe corrosion reactions were observed in the acidic environment, although a few were noted in the caustic environment. The presence of chlorides tended to enhance galvanic corrosion rates at the neutral environment. 10 tables

Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

Science.gov (United States)

Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

2016-01-01

This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

Helium release from radioisotope heat sources

Energy Technology Data Exchange (ETDEWEB)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.

Helium release from radioisotope heat sources

International Nuclear Information System (INIS)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in 238 PuO 2 fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel

Helium heater design for the helium direct cycle component test facility. [for gas-cooled nuclear reactor power plant

Science.gov (United States)

Larson, V. R.; Gunn, S. V.; Lee, J. C.

1975-01-01

The paper describes a helium heater to be used to conduct non-nuclear demonstration tests of the complete power conversion loop for a direct-cycle gas-cooled nuclear reactor power plant. Requirements for the heater include: heating the helium to a 1500 F temperature, operating at a 1000 psia helium pressure, providing a thermal response capability and helium volume similar to that of the nuclear reactor, and a total heater system helium pressure drop of not more than 15 psi. The unique compact heater system design proposed consists of 18 heater modules; air preheaters, compressors, and compressor drive systems; an integral control system; piping; and auxiliary equipment. The heater modules incorporate the dual-concentric-tube 'Variflux' heat exchanger design which provides a controlled heat flux along the entire length of the tube element. The heater design as proposed will meet all system requirements. The heater uses pressurized combustion (50 psia) to provide intensive heat transfer, and to minimize furnace volume and heat storage mass.

Corrosion properties of cladding materials from Zr1Nb alloy

International Nuclear Information System (INIS)

Kloc, K.; Kosler, S.

1975-01-01

The corrosion behaviour was observed of the Zr1Nb alloy in hot water and superheated steam and the effects of impurity content, of the purity of the corrosion environment and of the heat treatment of the alloy were studied on the alloy corrosion resistance. Also studied were the absorption of hydrogen by the alloy and its behaviour in reactor situations. It was ascertained that the alloy has a good corrosion resistance up to a temperature of 350 degC. The corrosion resistance is reduced by the presence of nitrogen above 50 to 70 ppm and of carbon above 50 to 90 ppm. A graphic representation is given of the dependence of corrosion resistance on the temperature of annealing, the nitrogen content of the alloy and the time of the action of hot water or steam, as well as the dependence of the hydrogen content in the alloy on the peripheral tension of the cladding in hot water both in non-active environment and at irradiation with a neutron flux of approximately 10 20 n/cm 2 . (J.B.)

Corrosion of silicon-containing austenitic stainless steels under trans-passive conditions

International Nuclear Information System (INIS)

Stolarz, Jacek

1989-01-01

This research thesis addresses austenitic stainless steels which are used in installations for the chemical treatment of nuclear fuels, and are there in contact with nitric acid solutions the oxidising character of which generally promotes metal passivity. However, if this nitric environment becomes too oxidising, these steels may face severe corrosion problems. More particularly, this thesis addresses the study of intergranular corrosion, and aims at analysing various aspects of the corrosion of these austenitic stainless steels in trans-passive conditions. The author aims at determining and distinguishing the contributions due to silicon and those related to the presence of other impurities and addition elements by comparing the behaviours of industrial grade steels and high purity alloys in rigorously controlled electrochemical conditions. Another objective is to study the influence of the intergranular structure on silicon segregation by means of an attack technique in trans-passive conditions. After a report of a bibliographical study on the addressed topics and a presentation of the studied materials and implemented experimental techniques, the author reports the study of steel behaviour with respect to generalised dissolution in trans-passive conditions, as well in the nitric environment as in a sulphuric acid solution at imposed potential. Localised intragranular corrosion phenomena are discussed. A trans-passive intragranular corrosion model is proposed, and its possibilities in the analysis of intergranular segregation analysis are discussed. Experimental results of trans-passive intergranular corrosion of stainless steels are presented and interpreted by using the McLean segregation model. The influence of steel composition and of experimental conditions is discussed, as well as the role of grain boundary structure in the corrosion process [fr

49 CFR 195.573 - What must I do to monitor external corrosion control?

Science.gov (United States)

2010-10-01

... SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.573 What must I do to... 49 Transportation 3 2010-10-01 2010-10-01 false What must I do to monitor external corrosion control? 195.573 Section 195.573 Transportation Other Regulations Relating to Transportation (Continued...

49 CFR 195.583 - What must I do to monitor atmospheric corrosion control?

Science.gov (United States)

2010-10-01

... SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.583 What must I do to... 49 Transportation 3 2010-10-01 2010-10-01 false What must I do to monitor atmospheric corrosion control? 195.583 Section 195.583 Transportation Other Regulations Relating to Transportation (Continued...

Variational method for magnetic impurities in metals: impurity pairs

Energy Technology Data Exchange (ETDEWEB)

Oles, A M [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany, F.R.); Chao, K A [Linkoeping Univ. (Sweden). Dept. of Physics and Measurement Technology

1980-01-01

Applying a variational method to the generalized Wolff model, we have investigated the effect of impurity-impurity interaction on the formation of local moments in the ground state. The direct coupling between the impurities is found to be more important than the interaction between the impurities and the host conduction electrons, as far as the formation of local moments is concerned. Under certain conditions we also observe different valences on different impurities.

Corrosion penetration monitoring of advanced ceramics in hot aqueous fluids

Directory of Open Access Journals (Sweden)

Klaus G. Nickel

2004-03-01

Full Text Available Advanced ceramics are considered as components in energy related systems, because they are known to be strong, wear and corrosion resistant in many environments, even at temperatures well exceeding 1000 °C. However, the presence of additives or impurities in important ceramics, for example those based on Silicon Nitride (Si3N4 or Al2O3 makes them vulnerable to the corrosion by hot aqueous fluids. The temperatures in this type of corrosion range from several tens of centigrade to hydrothermal conditions above 100 °C. The corrosion processes in such media depend on both pH and temperature and include often partial leaching of the ceramics, which cannot be monitored easily by classical gravimetric or electrochemical methods. Successful corrosion penetration depth monitoring by polarized reflected light optical microscopy (color changes, Micro Raman Spectroscopy (luminescence changes and SEM (porosity changes will be outlined. The corrosion process and its kinetics are monitored best by microanalysis of cross sections, Raman spectroscopy and eluate chemistry changes in addition to mass changes. Direct cross-calibrations between corrosion penetration and mechanical strength is only possible for severe corrosion. The methods outlined should be applicable to any ceramics corrosion process with partial leaching by fluids, melts or slags.

Control of helium activity in the fuel reactor channels; Kontrola aktivnosti heliuma u tehnoloskim kanalima

Energy Technology Data Exchange (ETDEWEB)

Vidmar, M; Milosevic, M; Hadzic, S [Institute of Nuclear Sciences Boris Kidric, Reaktor RA, Vinca, Beograd (Yugoslavia)

1961-02-15

The objective of this task was to study the possibility of detecting a damaged fuel channel, and to introduce automated procedure for continuous control of reactor channels during operation. The existing control systems at the RA reactor (permanent control of heavy water and helium activity, radiation monitoring of heavy water and helium system, measurements of fire damp gas percent) are not sufficient for fast detection of fuel element failures. Since a 'hot' fuel channel cannot be removed from the core because it should be cooled in the core by heavy water circulation, it is not possible to prevent contamination of heavy water by fission products. It is concluded that it is not indispensable to detect the failed fuel element promptly, i.e. that tome is not a critical issue.

Isotope effects of trapped electron modes in the presence of impurities in tokamak plasmas

Science.gov (United States)

Shen, Yong; Dong, J. Q.; Sun, A. P.; Qu, H. P.; Lu, G. M.; He, Z. X.; He, H. D.; Wang, L. F.

2016-04-01

The trapped electron modes (TEMs) are numerically investigated in toroidal magnetized hydrogen, deuterium and tritium plasmas, taking into account the effects of impurity ions such as carbon, oxygen, helium, tungsten and others with positive and negative density gradients with the rigorous integral eigenmode equation. The effects of impurity ions on TEMs are investigated in detail. It is shown that impurity ions have substantially-destabilizing (stabilizing) effects on TEMs in isotope plasmas for {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 (TEM turbulences in hydrogenic isotope plasmas with and without impurities are performed. The relations between the maximum growth rate of the TEMs with respect to the poloidal wave number and the ion mass number are given in the presence of the impurity ions. The results demonstrate that the maximum growth rates scale as {γ\\max}\\propto Mi-0.5 in pure hydrogenic plasmas. The scale depends on the sign of its density gradient and charge number when there is a second species of (impurity) ions. When impurity ions have density profiles peaking inwardly (i.e. {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 ), the scaling also depends on ITG parameter {ηi} . The maximum growth rates scale as {γ\\max}\\propto M\\text{eff}-0.5 for the case without ITG ({ηi}=0 ) or the ITG parameter is positive ({ηi}>0 ) but the impurity ion charge number is low (Z≤slant 5.0 ). However, when {ηi}>0 and the impurity ion charge number is moderate (Z=6.0-8.0 ), the scaling law is found as {γ\\max}\\propto M\\text{eff}-1.0 . Here, Z is impurity ion charge number, and the effective mass number, {{M}\\text{eff}}=≤ft(1-{{f}z}\\right){{M}i}+{{f}z}{{M}z} , with {{M}i} and {{M}Z} being the mass numbers of the hydrogenic and impurity ions, respectively, and {{f}z}=Z{{n}0z}/{{n}0e} being the charge concentration of impurity ions. In addition, with regard to the case of {{L}ez}<0 , the maximum growth rate scaling is {γ\\max}\\propto Mi-0.5 . The possible relations of the results

Corrosion and oxidation of vanadium-base alloys in helium environments

International Nuclear Information System (INIS)

Loomis, B.A.; Smith, D.L.

1984-01-01

The increase in weight of unalloyed V and V-5Ti, V-15Cr and V-15Cr-5Ti alloys at 725, 825 and 925 K was determined for exposure times ranging up to 1000 hours in He containing H 2 and/or H 2 O impurity. The microhardness of the specimens in a transverse section was also determined after exposure for 1000 hours. These results were utilized to discuss the consequences of the selection of certain radiation-damage resistant, V-base alloys for structural materials applications in a fusion reactor

Dispersion of breakdown voltage of liquid helium

International Nuclear Information System (INIS)

Ishii, Itaru; Noguchi, Takuya

1978-01-01

As for the electrical insulation characteristics of liquid helium, the discrepancy among the measured values by each person is very large even in the fundamental DC breakdown voltage in uniform electric field. The dispersion of experimental values obtained in the experiments by the same person is also large. Hereafter, the difference among the mean values obtained by each experimenter will be referred to as ''deviation of mean values'', and the dispersion of measured values around the mean value obtained by the same person as ''deviation around the man value''. The authors have mainly investigated on the latter experimentally. The cryostat was made of stainless steel, and the innermost helium chamber was of 500 mm I.D. and approximately 1200 mm deep. The high voltage electrode was of brass sphere of 25 mm diameter, and the low voltage electrode was of brass plate. The experiment was conducted for liquid helium boiling at 4.2 K and 1 atm, and the breakdown voltage and time lag were measured by applying the approximately square wave impulses of fast rise and long tail, ramp and DC voltages. The cause of the deviation of mean values may be the presence of impurity particles or the effect of electrode shape. As for the deviation around the mean value, the dispersion is large, and its standard deviation may amount to 10 to 20% of the man value. The dispersion is not due to the statistical time lag, but is due to parameters that vary with breakdown. (Wakatsuki, Y.)

Controlled Cold Helium Spill Test in the LHC Tunnel at CERN

Science.gov (United States)

Koettig, T.; Casas-Cubillos, J.; Chorowski, M.; Dufay-Chanat, L.; Grabowski, M.; Jedrusyna, A.; Lindell, G.; Nonis, M.; Vauthier, N.; van Weelderen, R.; Winkler, T.; Bremer, J.

The helium cooled magnets of the LHC particle accelerator are installed in a confined space, formed by a 27 km circumference 3.8 m diameter underground tunnel. The vacuum enclosures of the superconducting LHC magnets are protected by a lift plate against excessive overpressure created by eventual leaks from the magnet helium bath, or from the helium supply headers. A three-meter long no stay zone has been defined centered to these plates, based on earlier scale model studies, to protect the personnel against the consequences of an eventual opening of such a lift plate. More recently several simulation studies have been carried out modelling the propagation of the resulting helium/air mixture along the tunnel in case of such a cold helium release at a rate in the range of 1 kg/s. To validate the different scale models and simulation studies, real life mock-up tests have been performed in the LHC, releasing about 1000 liter of liquid helium under standard operational tunnel conditions. Data recorded during these tests include oxygen level, temperature and flow speed as well as video recordings, taken up- and downstream of the spill point (-100 m to +200 m) with respect to the ventilation direction in the LHC tunnel. The experimental set-up and measurement results are presented. Generic effects found during the tests will be discussed to allow the transposal to possible cold helium release cases in similar facilities.

Effect of boron control of environment on corrosion and resistance to low-cycle corrosion fatigue in structural steels

International Nuclear Information System (INIS)

Babej, Yu.I.; Zhitkov, V.V.; Zvezdin, Yu.I.; Liskevich, I.Yu.; Nazarov, A.A.

1982-01-01

Tests of the specimens on total, contact and crevice corrosion, corrosion cracking and low-cycle fatigue are conducted for determination of corrosion and corrosion-fatigue characteristics in the 15Kh3NMFA, 10N3MFA, 10Kh16N4B, 05Kh13N6M2 structural steels, used in energetics. The environment is subjected to boron control and contacting with atmosphere for simulation of stop and operation modes of the facility. The experiments are carried out in the distilled water with 12g/l H 3 BO 3 and 10 mg/l Cl' at 25, 60, 100 deg C under contacting with atmosphere. It is established, that the pearlitic steels 15Kh3NMFA, 10N3MFA, as well as transition and martensitic 05Kh13N6M2 and 10Kh16N4B steels are highly stable to total, crevice and contact corrosion at the high parameters of aqueous boron-containing medium. Steel resistance to low-cycle fracture decreases slightly under the conditions similar to the operation ones, in the water with 12 g/l H 3 BO 3 . Durability of the pearlitic steels at the simulation of stop conditions decreases more noticeably, crack formation as a rule, initiating from corrosion spots

Laboratory Assessment of Select Methods of Corrosion Control and Repair in Reinforced Concrete Bridges

Directory of Open Access Journals (Sweden)

Matthew D. Pritzl

2014-01-01

Full Text Available Fourteen reinforced concrete laboratory test specimens were used to evaluate a number of corrosion control (CoC procedures to prolong the life of patch repairs in corrosion-damaged reinforced concrete. These specimens included layered mixed-in chlorides to represent chloride contamination due to deicing salts. All specimens were exposed to accelerated corrosion testing for three months, subjected to patch repairs with various treatments, and further subjected to additional three months of exposure to accelerated corrosion. The use of thermal sprayed zinc, galvanic embedded anodes, epoxy/polyurethane coating, acrylic coating, and an epoxy patch repair material was evaluated individually or in combination. The specimens were assessed with respect to corrosion currents (estimated mass loss, chloride ingress, surface rust staining, and corrosion of the reinforcing steel observed after dissection. Results indicated that when used in patch repair applications, the embedded galvanic anode with top surface coating, galvanic thermal sprayed zinc, and galvanic thermal sprayed zinc with surface coating were more effective in controlling corrosion than the other treatments tested.

Insight into point defects and impurities in titanium from first principles

Science.gov (United States)

Nayak, Sanjeev K.; Hung, Cain J.; Sharma, Vinit; Alpay, S. Pamir; Dongare, Avinash M.; Brindley, William J.; Hebert, Rainer J.

2018-03-01

Titanium alloys find extensive use in the aerospace and biomedical industries due to a unique combination of strength, density, and corrosion resistance. Decades of mostly experimental research has led to a large body of knowledge of the processing-microstructure-properties linkages. But much of the existing understanding of point defects that play a significant role in the mechanical properties of titanium is based on semi-empirical rules. In this work, we present the results of a detailed self-consistent first-principles study that was developed to determine formation energies of intrinsic point defects including vacancies, self-interstitials, and extrinsic point defects, such as, interstitial and substitutional impurities/dopants. We find that most elements, regardless of size, prefer substitutional positions, but highly electronegative elements, such as C, N, O, F, S, and Cl, some of which are common impurities in Ti, occupy interstitial positions.

Pitting corrosion resistant austenite stainless steel

Science.gov (United States)

van Rooyen, D.; Bandy, R.

A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

Development of wall conditioning and impurity monitoring systems in Versatile Experiment Spherical Torus (VEST)

Energy Technology Data Exchange (ETDEWEB)

Lee, H.Y., E-mail: brbbebbero@snu.ac.kr [Seoul National University, Seoul (Korea, Republic of); Yang, J.; Kim, Y.G.; Yang, S.M.; Kim, Y.S.; Lee, K.H. [Seoul National University, Seoul (Korea, Republic of); An, Y.H. [National Fusion Research Institute, Daejon (Korea, Republic of); Chung, K.J.; Na, Y.S. [Seoul National University, Seoul (Korea, Republic of); Hwang, Y.S., E-mail: yhwang@snu.ac.kr [Seoul National University, Seoul (Korea, Republic of)

2016-11-01

Highlights: • The baking for partial wall heating and H{sub 2}/He GDC systems are developed in VEST. • The RGA and OES systems for monitoring impurities are constructed in VEST. • The partial baking and He GDC show limited effects on plasma characteristics. • H{sub 2} GDC above 4 h enables the longer plasma current duration up to ∼15 ms. • After H{sub 2} GDC, the discharge should be conducted within 3 h from treatment. - Abstract: Wall conditioning and impurity monitoring systems are developed in Versatile Experiment Spherical Torus (VEST). As a wall conditioning system, a baking system covering the vacuum vessel wall partially and a glow discharge cleaning (GDC) system using two electrodes with dc and 50 kHz power supplies are installed. The GDC system operates with hydrogen and helium gases for both chemical and physical desorption. The impurity monitoring system with residual gas analyzer (RGA), operating at <10{sup −5} Torr with a differential pumping system, is installed along with the optical emission spectroscopy (OES) system to monitor the hydrogen and impurity radiation lines. Effects of these wall conditioning techniques are investigated with the impurity monitoring system for ohmic discharges of VEST. The partial baking and He GDC show limited effects on plasma characteristics but sufficient H{sub 2} GDC above 4 h enables the longer plasma current duration up to ∼15 ms within 3 h from the end of treatment.

Development of wall conditioning and impurity monitoring systems in Versatile Experiment Spherical Torus (VEST)

International Nuclear Information System (INIS)

Lee, H.Y.; Yang, J.; Kim, Y.G.; Yang, S.M.; Kim, Y.S.; Lee, K.H.; An, Y.H.; Chung, K.J.; Na, Y.S.; Hwang, Y.S.

2016-01-01

Highlights: • The baking for partial wall heating and H_2/He GDC systems are developed in VEST. • The RGA and OES systems for monitoring impurities are constructed in VEST. • The partial baking and He GDC show limited effects on plasma characteristics. • H_2 GDC above 4 h enables the longer plasma current duration up to ∼15 ms. • After H_2 GDC, the discharge should be conducted within 3 h from treatment. - Abstract: Wall conditioning and impurity monitoring systems are developed in Versatile Experiment Spherical Torus (VEST). As a wall conditioning system, a baking system covering the vacuum vessel wall partially and a glow discharge cleaning (GDC) system using two electrodes with dc and 50 kHz power supplies are installed. The GDC system operates with hydrogen and helium gases for both chemical and physical desorption. The impurity monitoring system with residual gas analyzer (RGA), operating at <10"−"5 Torr with a differential pumping system, is installed along with the optical emission spectroscopy (OES) system to monitor the hydrogen and impurity radiation lines. Effects of these wall conditioning techniques are investigated with the impurity monitoring system for ohmic discharges of VEST. The partial baking and He GDC show limited effects on plasma characteristics but sufficient H_2 GDC above 4 h enables the longer plasma current duration up to ∼15 ms within 3 h from the end of treatment.

Checking the sealing of fuel elements by helium sweating - case of the reactors G2 (1960); Controle de l'etancheite des elements combustibles par ressuage d'helium - cas du reacteur G2 (1960)

Energy Technology Data Exchange (ETDEWEB)

Blanc, B; D' Orival, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Choumoff, S [Compagnie Francaise Thomson-Houston, 75 - Paris (France)

1960-07-01

The G2 slug is a welded, hermetically sealed unit; the seal is checked by placing the fuel element in a helium atmosphere under pressure, then measuring the quantity of helium it releases in a vessel under vacuum. The theoretical aspect and the conditions of industrial application are reviewed, and the installations described. (author) [French] La cartouche G2 se presente comme un ensemble soude, hermetique; le controle d'etancheite s'effectue en immergeant l'element combustible dans une atmosphere d'helium sous pression puis en mesurant la quantite d'helium qu'il restitue dans une enceinte sous vide. L'aspect theorique et les conditions d'exploitation industrielle sont evoques et les installations decrites. (auteur)

Dynamical impurity problems

International Nuclear Information System (INIS)

Emery, V.J.; Kivelson, S.A.

1993-01-01

In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class

Dynamical impurity problems

Energy Technology Data Exchange (ETDEWEB)

Emery, V.J. [Brookhaven National Lab., Upton, NY (United States); Kivelson, S.A. [California Univ., Los Angeles, CA (United States). Dept. of Physics

1993-12-31

In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class.

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

Energy Technology Data Exchange (ETDEWEB)

Bill W. Bogan; Brigid M. Lamb; John J. Kilbane II

2004-10-30

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing indicated that the growth, and the metal corrosion caused by pure cultures of sulfate reducing bacteria were inhibited by hexane extracts of some pepper plants. This quarter tests were performed to determine if chemical compounds other than pepper extracts could inhibit the growth of corrosion-associated microbes and to determine if pepper extracts and other compounds can inhibit corrosion when mature biofilms are present. Several chemical compounds were shown to be capable of inhibiting the growth of corrosion-associated microorganisms, and all of these compounds limited the amount of corrosion caused by mature biofilms to a similar extent. It is difficult to control corrosion caused by mature biofilms, but any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion.

Hydrogen and helium in metals: positron lifetime experiments. Quarterly report 3. quarter 1987

International Nuclear Information System (INIS)

Rajainmaeki, Hannu.

1987-09-01

This thesis reviews a new approach to studying the role of hydrogen and helium in defect recovery of metals by the positron lifetime technique. A cryostat has been built at the University of Jyvaeskylae for irradiating and/or implaning solids by high-energy proton or helium beams from the MC-20 cyclotron. The samples can be kept continuously below 20 K and the isochronal annealings and the subsequent positron lifetime measurements are carried ou in the same cryostat after the irradiations. During the implantations below 20 K both impuities (H or He) and Frenkel pairs are produced simultaneously. By measuring positron lifetimes during the annealing detailed information is obtained about radiation damage, impurity-defect interactions, lattice defect annealing, void nucleation and formation of helium bubbles. In this work positron lifetime spectroscopy has been utilized for the first time to study defect recovery below the liquid nitrogen temperature (77 K). The annealing stages are investigated in aluminium, nickel and molybdenum in the temperature range 20-700 K. Hydrogen is found to get trapped at vacancies in all the studied metals with binding energies 0.53+-0.04 and 1.6+-0.1 eV, respectively. Trapped hydrogen retards the vacancy migration in Al and Mo, while H-vancancy pairs dissociate in Ni below the free vacancy migration stage. helium gets deeply trapped at vacancies in Al and migrates substitutionally with the activation energy of 1.3+-0.1 eV. Helium-vacancy pairs are observed to nucleate into clusters and form helium bubbles which are stable up to the Al melting temperature. The growth mechanisms for the bubbles are established as thermal vacancy absorption and bubble migration/coalescence

49 CFR 195.559 - What coating material may I use for external corrosion control?

Science.gov (United States)

2010-10-01

...) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.559 What coating... 49 Transportation 3 2010-10-01 2010-10-01 false What coating material may I use for external corrosion control? 195.559 Section 195.559 Transportation Other Regulations Relating to Transportation...

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

Corrosion characteristics of copper and leaded bronze in palm biodiesel

Energy Technology Data Exchange (ETDEWEB)

Haseeb, A.S.M.A.; Masjuki, H.H.; Ann, L.J.; Fazal, M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2010-03-15

Biodiesel has become more attractive as alternative fuel for automobiles because of its environmental benefits and the fact that it is made from renewable sources. However, corrosion of metals in biodiesel is one of the concerns related to biodiesel compatibility issues. This study aims to characterize the corrosion behavior of commercial pure copper and leaded bronze commonly encountered in the automotive fuel system in diesel engine. Static immersion tests in B0, B50 and B100 fuels were carried out at room temperature for 2640 h. Similar immersion tests in B0, B100 and B100 (oxidized) fuels were also conducted at 60 C for 840 h. At the end of the test, corrosion behavior was investigated by weight loss measurements and changes in surface morphology. Fuels were analyzed by using TAN analyzer, FTIR, MOA (multi-element oil analyzer) to investigate acid concentration, oxidation level with water content and corrosive impurities respectively. Results showed that under the experimental conditions, pure copper was more susceptible to corrosion in biodiesel as compared to leaded bronze. (author)

The installation of helium auxiliary systems in HTGR

International Nuclear Information System (INIS)

Qin Zhenya; Fu Xiaodong

1993-01-01

The inert gas Helium was chosen as reactor coolant in high temperature gas coolant reactor, therefore a set of Special and uncomplex helium auxiliary systems will be installed, the safe operation of HTR-10 can be safeguarded. It does not effect the inherent safety of HTR-10 MW if any one of all those systems were damaged during operation condition. This article introduces the design function and the system principle of all helium auxiliary systems to be installed in HTR-10. Those systems include: helium purification and its regeneration system, helium supply and storage system, pressure control and release system of primary system, dump system for helium auxiliary system and fuel handling, gaseous waste storage system, water extraction system for helium auxiliary systems and evacuation system for primary system

Corrosion of nickel and stainless steels in concentrated lithium hydroxide solutions

International Nuclear Information System (INIS)

Graydon, J.W.; Kirk, D.W.

1990-06-01

The corrosion behaviour of four alloys in 3 and 5 mol/L lithium hydroxide solutions under a hydrogen atmosphere at 95 degrees C was investigated. Corrosion of Nickel 200 and the stainless steels 316, 316L, and E-Brite 26-1 was assessed in two sets of immersion tests lasting 10 and 136 days. Corrosion rates were determined by weight loss, susceptibility to stress corrosion cracking was evaluated using U-bends, and the details of the corrosion process were studied on specimens with a mirror finish using light and electron microscopy, x-ray spectrometry and mapping, and x-ray diffraction. The long term corrosion rates were low for all alloys ( 2 , β-LiFeO 2 , and a very iron-rich β-LiFe 5 0 8 . The passivating layer on the nickel was Ni(OH) 2 . The underlying metal corroded evenly except for the 316 stainless steels. These showed a uniform intergranular corrosion with minor drop-out of smaller grains likely because of segregation of impurities to the grain boundaries. The walls of these intergranular crevices were covered with a passivating layer of chromium oxide. (8 figs., 5 tabs., 11 refs.)

Creep and fatigue properties of Incoloy 800H in a high-temperature gas-cooled reactor (HTGR) helium environment

International Nuclear Information System (INIS)

Chow, J.G.Y.; Soo, P.; Epel, L.

1978-01-01

A mechanical test program to assess the effects of a simulated HTGR helium environment on the fatigue and creep properties of Incoloy 800H and other primary-circuit metals is described. The emphasis and the objectives of this work are directed toward obtaining information to assess the integrity and safety of an HTGR throughout its service life. The helium test environment selected for study contained 40 μ atm H 2 O, 200 μ atm H 2 , 40 μ atm CO, 10 μ atm CO 2 , and 20 μ atm CH 4 . It is believed that this ''wet'' environment simulates that which could exist in a steam-cycle HTGR containing some leaking steam-generator tubes. A recirculating helium loop operating at about 4 psi in which impurities can be maintained at a constant level, has been constructed to supply the desired environment for fatigue and creep testing

Control of corrosive bacterial community by bronopol in industrial water system.

Science.gov (United States)

Narenkumar, Jayaraman; Ramesh, Nachimuthu; Rajasekar, Aruliah

2018-01-01

Ten aerobic corrosive bacterial strains were isolated from a cooling tower water system (CWS) which were identified based on the biochemical characterization and 16S rRNA gene sequencing. Out of them, dominant corrosion-causing bacteria, namely, Bacillus thuringiensis EN2, Terribacillus aidingensis EN3, and Bacillus oleronius EN9, were selected for biocorrosion studies on mild steel 1010 (MS) in a CWS. The biocorrosion behaviour of EN2, EN3, and EN9 strains was studied using immersion test (weight loss method), electrochemical analysis, and surface analysis. To address the corrosion problems, an anti-corrosive study using a biocide, bronopol was also demonstrated. Scanning electron microscopy and Fourier-transform infrared spectroscopy analyses of the MS coupons with biofilm developed after exposure to CWS confirmed the accumulation of extracellular polymeric substances and revealed that biofilms was formed as microcolonies, which subsequently cause pitting corrosion. In contrast, the biocide system, no pitting type of corrosion, was observed and weight loss was reduced about 32 ± 2 mg over biotic system (286 ± 2 mg). FTIR results confirmed the adsorption of bronopol on the MS metal surface as protective layer (co-ordination of NH 2 -Fe 3+ ) to prevent the biofilm formation and inhibit the corrosive chemical compounds and thus led to reduction of corrosion rate (10 ± 1 mm/year). Overall, the results from WL, EIS, SEM, XRD, and FTIR concluded that bronopol was identified as effective biocide and corrosion inhibitor which controls the both chemical and biocorrosion of MS in CWS.

Effects of organic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

2010-01-01

mu m of the contaminated surface was required to reach corrosion rates less than 1 mm/year in salt spray condition. Among the three organic acids examined, acetic acid is the best choice. Oxalic acid can be an alternative while citric acid is not suitable for cleaning AZ31 sheet, because......Organic acids were used to clean AZ31 magnesium alloy sheet and the effect of the cleaning processes on the surface condition and corrosion performance of the alloy was investigated. Organic acid cleanings reduced the surface impurities and enhanced the corrosion resistance. Removal of at least 4...

Study on cryogenic adsorption capability of trace nitrogen and methane by activated carbon for cooIant helium purification

International Nuclear Information System (INIS)

Chang Hua; Wu Zongxin

2014-01-01

A fixed-bed apparatus with dynamic two-route proportional gas mixing system was designed to investigate the cryogenic adsorption behavior of nitrogen and methane on activated carbon for designing the helium purification system of high-temperature gas-cooled reactors (HTGR). With helium as carrier gas and at the impurity partial pressure of tens Pa, experiments were performed at near atmospheric pressure and by dynamic column breakthrough method at -196°C. The breakthrough curves and desorption curves were measured. By analyzing the breakthrough curve, both the equilibrium adsorption capacity and the kinetic adsorption capacity at breakthrough point were determined. Based on mass-transfer zone model, the experimental breakthrough curves were analyzed. (author)

Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum

Directory of Open Access Journals (Sweden)

Injoon Son

2012-01-01

Full Text Available The effect of equal-channel angular pressing (ECAP on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3 of Na2SO4 and 8.46 mol·dm−3 of NaCl (300 ppm Cl− and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2 revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films.

Investigation of a Plugging Meter for Measuring Impurity Content in Liquid Sodium (I)

International Nuclear Information System (INIS)

Choi, Jong Hyeun; Kim, Jong Man; Choi, Byoung Hae; Jeong, Ji Young; Lee, Yong Bum

2010-01-01

In a Sodium-cooled Fast Reactor (SFR), liquid sodium is subject to the formation of impurities by its high chemical reactivity with so many elements and common compounds used in nuclear reactor construction materials. The impurities are mainly in the form of hydrides, oxides, metallic compounds, metallic and carbon particles, which originate primarily from steam generator corrosion, moisture from system component surface, and leakage of air into the system. These are finally deposited in the form of the crystallization of sodium hydride (NaH) or sodium oxide (Na 2 O) at the cold points of the circuit, which may lead to the clogging of the narrowed sections or may damage the pump. Therefore, the sodium must be purified and analyzed in order to prevent from the detrimental influence. The analysis of hydrogen and oxygen is very important. There are many chemical methods for analyzing the impurities, but these methods are time-consuming, troublesome and contamination of samples from air and containers, that is the reason why the countries develop the instruments of impurity on-line measurement. The plugging meter is one of the most important on-line measuring instruments and it is a reliable instrument which has been widely used on sodium loops

Investigation of helium plasma stream parameters in experiments on surface modification

International Nuclear Information System (INIS)

Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Garkusha, I.E.; Tsarenko, A.V. and eds.

2005-01-01

The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. With use of optical spectroscopy, detailed information about the basic plasma parameters - electron density, electron and ion temperatures, plasma stream duration and velocity, was obtained. Integrated spectra of plasma radiation were analyzed. The majority of helium and impurity spectral lines were investigated on a subject of Stark broadening. Plasma pressure and energy density values measured with piezodetectors and calorimeters are in good agreement with plasma parameters obtained by optical techniques

Developing a Systematic Corrosion Control Evaluation Approach in Flint

Science.gov (United States)

Presentation covers what the projects were that were recommended by the Flint Safe Drinking Water Task Force for corrosion control assessment for Flint, focusing on the sequential sampling project, the pipe rigs, and pipe scale analyses.

PIPELINE CORROSION CONTROL IN OIL AND GAS INDUSTRY: A ...

African Journals Online (AJOL)

user

protection technique as a method of controlling corrosion in oil and gas pipelines is effective and efficient when compared to ... In the field of crude oil production and associated engineering .... Industrial/Mechanical Systems, Joen Printing and.

Semiconductor analysis with a channeled helium microbeam

International Nuclear Information System (INIS)

Ingarfield, S.A.; McKenzie, C.D.; Short, K.T.; Williams, J.S.

1981-01-01

This paper describes the use of a channeled helium microbeam for analysis of damage and dopant distributions in semiconductors. Practical difficulties and potential problems associated with the channeling of microbeams in semiconductors have been examined. In particular, the following factors have been characterised: i) the effect of both convergence of focused beam and beam scanning on the quality of channeling; ii) damage produced by the probe ions; and iii) local beam heating effects arising from high current densities. Acceptable channeling has been obtained (minimum yield approaching 4%) under a variety of focusing and scanning conditions which are suitable for analysis of device structures. The capabilities of the technique are demonstrated by monitoring variations in local damage and impurity depth distributions across a narrow (<2mm) region of an ion implanted silicon wafer

On helium cluster dynamics in tungsten plasma facing components of fusion devices

International Nuclear Information System (INIS)

Krasheninnikov, S.I.; Faney, T.; Wirth, B.D.

2014-01-01

This paper describes the dynamics of helium clustering behaviour within either a nanometer-sized tendril of fuzz, or a half-space domain, as predicted by a reaction–diffusion model. This analysis has identified a dimensionless parameter, P Δ , which is a balance of the reaction and diffusion actions of insoluble He in a metal matrix and which governs the self-trapping effects of He into growing bubbles within a tendril. The impact of He self-trapping, as well as trapping caused by pre-existing traps in the form of lattice defects or clusters of impurities, within a half-space domain results in the formation of a densely packed layer of nanometer-sized bubbles with high number density. This prediction is consistent with available experimental observations in which a dense zone of helium bubbles is observed in tungsten, which are compared to estimates of the layer characteristics. Direct numerical simulation of the reaction–diffusion cluster dynamics supports the analysis presented here. (paper)

Spectroscopic study of sources and control of impurities in TMX-U. Revision 1

International Nuclear Information System (INIS)

Yu, T.L.; Allen, S.L.; Moos, H.W.

1984-11-01

Two absolutely calibrated euv instruments have been used to study the impurity characteristics in the Tandem Mirror Experiment-Upgrade (TMX-U). One instrument is a spectrograph that measures the time histories of several impurity emission lines in a single plasma shot. The other instrument is a monochromator that measures time-resolved radial profiles of a particular impurity emission line. The common intrinsic impurities found in TMX-U are C, N, O, and Ti. It has been shown that a large fraction of oxygen and nitrogen in the plasma is associated with the neutral beams. The plasma wall is the main source of carbon. In general, the concentration of each of the impurities is low (<1%), and the power radiated by them is less than 10 kW, which is a small portion of the total input power to the plasma. The concentrations of the impurities can be reduced substantially by glow discharge cleaning and titanium gettering

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

Energy Technology Data Exchange (ETDEWEB)

Bill W. Bogan; Brigid M. Lamb; Gemma Husmillo; Kristine Lowe; J. Robert Paterek; John J. Kilbane II

2004-12-01

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Various chemicals that inhibit the growth and/or the metabolism of corrosion-associated microbes such as sulfate reducing bacteria, denitrifying bacteria, and methanogenic bacteria were evaluated to determine their ability to inhibit corrosion in experiments utilizing pure and mixed bacterial cultures, and planktonic cultures as well as mature biofilms. Planktonic cultures are easier to inhibit than mature biofilms but several compounds were shown to be effective in decreasing the amount of metal corrosion. Of the compounds tested hexane extracts of Capsicum pepper plants and molybdate were the most effective inhibitors of sulfate reducing bacteria, bismuth nitrate was the most effective inhibitor of nitrate reducing bacteria, and 4-((pyridine-2-yl)methylamino)benzoic acid (PMBA) was the most effective inhibitor of methanogenic bacteria. All of these compounds were demonstrated to minimize corrosion due to MIC, at least in some circumstances. The results obtained in this project are consistent with the hypothesis that any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion. This approach of controlling MIC by controlling the metabolism of biofilms is more environmentally benign than the current approach involving the use of potent biocides, and warrants further investigation.

Glow discharge mass spectrometry study of chemical impurities diffusion in zirconium oxide layers

International Nuclear Information System (INIS)

Actis-Dato, L.O.

2000-02-01

In the Pressurised Water Reactors (PWR) the primary cooling system is water at 350 deg C and 16 Mpa. In these extreme conditions the corrosion of the out-of-pile components of the reactor and in particular of the Zircaloy cladding containing the nuclear fuel pellets is accelerated. The formation of a growing oxide layer is observed on the elements of the nuclear reactor core. When the thickness of the oxide layer reaches a critical value, problems like structural malfunction and material failure can occur. At this stage the danger of the release of radioactivity in the coolant becomes effective. In this work a glow discharge mass spectrometer is used to study the diffusion of impurities like lithium, zinc and boron in oxide layers growing on Zircaloy samples. After a brief description of the different technique used the preparation and analysis of Zircaloy samples on which oxide layers of different thickness have been produced will be described. The analysis of these samples will allow the determination and evaluation the depth profiles of the impurities absorbed by the oxide. The analysis of the shape of the crater produced during the mass spectrometric analysis will give additional informations on the quality of the results obtained. The technique developed will finally be applied to the study of samples produced during reactor operation under real irradiation conditions. The results obtained show a lithium intake in the oxide layer and confirm the beneficial effect on the corrosion produced by boron. The influence of zinc on the corrosion behaviour of Zircaloy has not been established. The technique developed has also shown interesting capabilities concerning the analysis of irradiated samples. (author)

Effect of lithium PFC coatings on NSTX density control

International Nuclear Information System (INIS)

Kugel, H.W.; Bell, M.G.; Bell, R.; Bush, C.; Gates, D.; Gray, T.; Kaita, R.; Leblanc, B.; Maingi, R.; Majeski, R.; Mansfield, D.; Mueller, D.; Paul, S.; Raman, R.; Roquemore, A.L.; Sabbagh, S.; Skinner, C.H.; Soukhanovskii, V.; Stevenson, T.; Zakharov, L.

2007-01-01

Lithium coatings on the graphite plasma facing components (PFCs) in NSTX are being investigated as a tool for density profile control and reducing the recycling of hydrogen isotopes. Repeated lithium pellet injection into Center Stack Limited and Lower Single Null ohmic helium discharges were used to coat graphite surfaces that had been pre-conditioned with ohmic helium discharges of the same shape to reduce their contribution to hydrogen isotope recycling. The following deuterium NBI reference discharges exhibited a reduction in density by a factor of about 3 for limited and 2 for diverted plasmas, respectively, and peaked density profiles. Recently, a lithium evaporator has been used to apply thin coatings on conditioned and unconditioned PFCs. Effects on the plasma density and the impurities were obtained by pre-conditioning the PFCs with ohmic helium discharges, and performing the first deuterium NBI discharge as soon as possible after applying the lithium coating

Electrochemical corrosion studies of the TStE 355 fine-grained structural steel in sulfide containing brine

International Nuclear Information System (INIS)

Farvaque-Bera, A.M.; Berg, H. von.

1994-04-01

Previous corrosion studies have shown that the unalloyed fine-grained steel TStE 355 (Material No. 1.0566) is a promising material for the manufacturing of long-lived high-level waste (HLW) containers that could act as a barrier in a rock-salt repository. Considering this fact, further electrochemical corrosion tests were performed in order to determine the influence of sulfide ions (1 -200 ppm), present as salt impurities in disposal relevant NaCl-brine (T = 55 -90 C), on the corrosion behaviour of this steel grade. For comparison, tests were carried out in the sulfide-free brine, too. (orig.) [de

Baking and helium glow discharge cleaning of SST-1 tokamak with graphite plasma facing components

International Nuclear Information System (INIS)

Semwal, Pratibha; Khan, Ziauddin; Raval, Dilip

2015-01-01

Graphite plasma facing components (PFCs) were installed inside SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 X 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium (He) glow discharge cleaning (GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nanometers from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.48. In this paper, the results of effect of baking and He-GDC experiments of SST-1 will be presented in detail. (author)

Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

Science.gov (United States)

Semwal, P.; Khan, Z.; Raval, D. C.; Dhanani, K. R.; George, S.; Paravastu, Y.; Prakash, A.; Thankey, P.; Ramesh, G.; Khan, M. S.; Saikia, P.; Pradhan, S.

2017-04-01

Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10-5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail.

Process and system for removing impurities from a gas

Science.gov (United States)

Henningsen, Gunnar; Knowlton, Teddy Merrill; Findlay, John George; Schlather, Jerry Neal; Turk, Brian S

2014-04-15

A fluidized reactor system for removing impurities from a gas and an associated process are provided. The system includes a fluidized absorber for contacting a feed gas with a sorbent stream to reduce the impurity content of the feed gas; a fluidized solids regenerator for contacting an impurity loaded sorbent stream with a regeneration gas to reduce the impurity content of the sorbent stream; a first non-mechanical gas seal forming solids transfer device adapted to receive an impurity loaded sorbent stream from the absorber and transport the impurity loaded sorbent stream to the regenerator at a controllable flow rate in response to an aeration gas; and a second non-mechanical gas seal forming solids transfer device adapted to receive a sorbent stream of reduced impurity content from the regenerator and transfer the sorbent stream of reduced impurity content to the absorber without changing the flow rate of the sorbent stream.

Effect of niobium element on the electrochemical corrosion behavior of depleted uranium

Energy Technology Data Exchange (ETDEWEB)

Wu, Yanping, E-mail: wuyanping-2@126.com; Wu, Quanwen; Zhu, Shengfa, E-mail: zhushf-306@163.com; Pu, Zhen; Zhang, Yanzhi; Wang, Qinguo; Lang, Dingmu; Zhang, Yuping

2016-09-15

Depleted uranium (DU) has many military and civilian uses. However, its high chemical reactivity limits its application. The effect of Nb content on corrosion behavior of DU is evaluated by scanning Kelvin probe and electrochemical corrosion measurements. The Volta potential value of DU and U-2.5 wt% Nb is about the same level, the Volta potential value of U-5.7 wt% Nb has a rise of 370mV{sub SHE} in comparison with DU. The polarization current of U-5.7 wt% Nb alloy is about an order of magnitude of that of DU. The Nb{sub 2}O{sub 5} is the protective layer for the U-Nb alloys. The negative potential of Nb-depleted α phase is the main reason of the poor corrosion resistance of DU and U-2.5 wt% Nb alloy. - Highlights: • New method (scanning Kelvin probe) was used to study the corrosion property. • Three types of corrosion morphologies were found after potentiodynamic polarization. • The effect of impurity elements on corrosion property was mentioned. • The corrosion mechanism of DU and U-Nb alloys was discussed.

Impurity control in toroidal devices

International Nuclear Information System (INIS)

1990-01-01

This summary report on the Technical Committee Meeting organized by the IAEA and held in Naka-Gun, Japan, 13-15 February 1989, provides an overview of the results presented. Of the twenty-three papers presented, sixteen were devoted to tokamak experiments. These presented data of plasma behavior in the scrape-off layer and divertor regions, as well as effects of impurities on the core plasma; these are summarized here. Other papers summarized deal with plasma-wall interactions, including wall material behavior. Still others deal with theoretical work on physics modelling in the edge region. Refs, figs and tabs

Monitoring corrosion rates and localised corrosion in low conductivity water

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

2006-01-01

Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised...... corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating plants. Changes in the corrosion processes are best monitored in non-aggressive, low conductivity media...

EPICS based control system for cryogenic plant at VECC

International Nuclear Information System (INIS)

Panda, Umashankar; Pal, Sandip; Mandal, Anupam; Dey, Ranadhir

2012-01-01

Cryogenic Plant of Variable Energy Cyclotron Centre consists of two Helium refrigerators (250W and 415W at the rate 4.5K), valve box with sub-cooler and associated sub systems like pure gas storage, helium purifier and impure gas recovery etc. The system also consists of 3.1K liters of liquid Nitrogen (LN 2 ) storage and delivery system. Many of the systems are procured from different suppliers and some are also developed in house. Due to the variety of systems and suppliers the control philosophy, communication protocols and component is also different. So the Supervisory control and data acquisition (SCADA) module has to be such that it can take care of the variance and bring everything into a common control platform. To solve this purpose EPICS (Experimental Physics and Industrial Control System) architecture has been adopted. EPICS is having the advantage of being open source, flexible and unlimited as compared to the commercial SCADA packages. (author)

Initial assessment of environmental effects on SiC/SiC composites in helium-cooled nuclear systems

Energy Technology Data Exchange (ETDEWEB)

Contescu, Cristian I [ORNL

2013-09-01

This report summarized the information available in the literature on the chemical reactivity of SiC/SiC composites and of their components in contact with the helium coolant used in HTGR, VHTR and GFR designs. In normal operation conditions, ultra-high purity helium will have chemically controlled impurities (water, oxygen, carbon dioxide, carbon monoxide, methane, hydrogen) that will create a slightly oxidizing gas environment. Little is known from direct experiments on the reactivity of third generation (nuclear grade) SiC/SiC composites in contact with low concentrations of water or oxygen in inert gas, at high temperature. However, there is ample information about the oxidation in dry and moist air of SiC/SiC composites at high temperatures. This information is reviewed first in the next chapters. The emphasis is places on the improvement in material oxidation, thermal, and mechanical properties during three stages of development of SiC fibers and at least two stages of development of the fiber/matrix interphase. The chemical stability of SiC/SiC composites in contact with oxygen or steam at temperatures that may develop in off-normal reactor conditions supports the conclusion that most advanced composites (also known as nuclear grade SiC/SiC composites) have the chemical resistance that would allow them maintain mechanical properties at temperatures up to 1200 1300 oC in the extreme conditions of an air or water ingress accident scenario. Further research is needed to assess the long-term stability of advanced SiC/SiC composites in inert gas (helium) in presence of very low concentrations (traces) of water and oxygen at the temperatures of normal operation of helium-cooled reactors. Another aspect that needs to be investigated is the effect of fast neutron irradiation on the oxidation stability of advanced SiC/SiC composites in normal operation conditions.

Helium behaviour in nuclear glasses

International Nuclear Information System (INIS)

Fares, T.

2011-01-01

The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

Determination of trace impurities in materials

International Nuclear Information System (INIS)

Parashar, D.C.

1991-01-01

Research work done at the National Physical Laboratory to develop new methods which are more specific and/or more sensitive has been reviewed. These methods are based on the use of existing facilities viz. atomic absorption spectrophotometry, uv-visible spectrophotometry, gas chromatography and conventional chemical methods. It is possible to determine impurities like boron at 5ppb level, phosphorus at 100 ppb and oxygen non-stoichiometry in 1:2:3 compounds with higher accuracy. Boron is determined spectrophotometrically by forming a complex with curcumin and phosphorus is determined indirectly by atomic absorption spectrophotometry by forming phosphomolybdate complex with antimony or bismuth which have 1:1 ratio with phosphorus in the complex. Gas chromatographic technique has been used to evaluate the oxygen non-stoichiometry in high temperature superconductors (1:2:3 compound) where the HTc sample is dissolved in dilute nitric acid in helium environment and the oxygen released is determined using thermal conductivity detector. (author). 19 refs., 3 figs., 4 tabs

Effect of steam corrosion on core post strength loss: I. Low, chronic steam ingress rates

International Nuclear Information System (INIS)

Wichner, R.P.

1976-10-01

The purpose of the study was to assess the effect of chronic, low levels of steam ingress into the primary system of the HTGR on the corrosion, and consequent strength loss of the core support posts. The assessment proceeded through the following three steps: (1) The impurity composition in the primary system was estimated as a function of a range of steady ingress rates of from 0.001 to 1.0 g/sec, both by means of an analysis of the Dragon steam ingress experiment and a computer code, TIMOX, which treats the primary system as a well-mixed pot. (2) The core post burnoffs which result from 40-year exposures to these determined impurity atmospheres were then estimated using a corrosion rate expression derived from published ATJ-graphite corrosion rate data. Burnoffs were determined for both the core posts at the nominal and the maximum sustained temperature, estimated to be 90 0 C above nominal. (3) The final step involved assessment of the degree of strength loss resulting from the estimated burnoffs. An empirical equation was developed for this purpose which compares reasonably well with strength loss data for a number of different graphites and specimen geometries

Overview of impurity control and wall conditioning in NSTX

Energy Technology Data Exchange (ETDEWEB)

KUGEL,H.W.; MAINGI,R.; BELL,M.; BLANCHARD,W.; GATES,D.; JOHNSON,D.; KAITA,R.; KAYE,S.; MARQUEDA,R.; MENARD,J.; MUELLER,D.; ONO,M.; PENG,Y-K.M.; RAMAN,R.; RAMSEY,A.; ROQUEMORE,A.; SKINNER,C.; SABBAGH,S.; STUTMAN,D.; WAMPLER,WILLIAM R.; WILSON,J.R.; ZWEBEN,S.

2000-05-25

The National Spherical Torus Experiment (NSTX) started plasma operations in February 1999, and promptly achieved high current, inner wall limited, double null, and single null plasma discharges, initial Coaxial Helicity Injection, and High Harmonic Fast Wave results. NSTX is designed to study the physics of Spherical Tori (ST) in a device that can produce non-inductively sustained high-{beta} discharges in the 1 MA regime and to explore approaches toward a small, economical high power density ST reactor core. As expected, discharge reproducibility and performance were strongly affected by wall conditions. In this paper, the authors describe the internal geometry, and initial plasma discharge, impurity control, wall conditioning, erosion, and deposition results.

Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak

Science.gov (United States)

Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

1993-03-01

Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

Helium, iron and electron particle transport and energy transport studies on the TFTR tokamak

International Nuclear Information System (INIS)

Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Grek, B.; Hill, K.W.; Hulse, R.A.; Johnson, D.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Redi, M.H.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.

1993-03-01

Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor

The Corrosion control in the Bolivia-Brazil Gas Pipeline; O controle da corrosao no Gasoduto Bolivia-Brasil

Energy Technology Data Exchange (ETDEWEB)

Coelho, Jorge Fernando Pereira [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Rio de Janeiro, RJ (Brazil)

2003-07-01

This paper presents the techniques and procedures adopted for the corrosion control of the Bolivia-Brazil Gas Pipeline. In buried pipes, the corrosion process may occur on the external surface in contact with the surrounding soil as well on the internal surface in contact with the conveyed fluid, being necessary the simultaneous mitigation of the both processes. (author)

The effect lead impurities on the corrosion resistance of alloy 600 and alloy 690 in high temperature water

International Nuclear Information System (INIS)

Sakai, T.; Nakagomi, N.; Kikuchi, T.; Aoki, K.; Nakayasu, F.; Yamakawa, K.

1998-01-01

Degradation of nickel-based alloy steam generator (SG) tubing caused by lead-induced corrosion has been reported recently in some PWR plants. Several laboratory studies also have shown that lead causes intergranular or transgranular stress corrosion cracking (IGSCC or TGSCC) of the tubing materials. Information from previous studies suggests two possible explanations for the mechanism of lead-induced corrosion. One is selective dissolution of tube metal elements, resulting in formation of a lead-containing nickel-depleted oxide film as observed in mildly acidic environments. The other explanation is an increase in potential, as has been observed in lead-contaminated caustic environments, although not in all volatile treatment (AVT) water such as the ammonium-hydrazine water chemistry. These observation suggest that an electrochemical reaction between metal elements and dissolved lead might be the cause of lead-induced corrosion. The present work was undertaken to clarify the lead-induced corrosion mechanism of nickel-based alloys from an electrochemical viewpoint, focusing on mildly acidic and basic environments. These are the probable pH conditions in the crevice region between the tube and tube support plate of the SG where corrosion damage could occur. Measurements of corrosion potential and electrochemical polarization of nickel-based alloys were performed to investigate the effect of lead on electrochemical behavior of the alloys. Then, constant extension rate tests (CERT) were carried out to determine the corrosion susceptibility of the alloys in a lead-contaminated environment. (J.P.N.)

Electrochemical investigations for understanding and controlling corrosion in nuclear reactor materials

International Nuclear Information System (INIS)

Gnanamoorthy, J.B.

1998-01-01

Electrochemical techniques such as potentiodynamic polarization have been used at the Indira Gandhi Centre for Atomic Research at Kalpakkam for understanding and controlling the corrosion of nuclear reactor materials such as austenitic stainless steels and chrome-moly steels. Results on the measurements of critical potentials for pitting and crevice corrosion of stainless steels and their weldments and of laser surface modified stainless steels in aqueous chloride solutions are discussed. Investigations carried out to correlate the degree of sensitization in types 304 and 316 stainless steels, measured by the electrochemical potentiokinetic reactivation technique, with the susceptibility to intergranular corrosion and intergranular stress corrosion cracking have been discussed. The stress corrosion cracking behaviour of weldments of type 316 stainless steel was studied in a boiling solution of a mixture of 5 M NaCl and 0.15 M Na 2 SO 4 acidified to give a pH of 1.3 by monitoring of the open circuit potential with time as well as by anodic polarization. Interesting information could also been obtained on the microbiologically influenced corrosion of type 304 stainless steels in a fresh water system by carrying out cyclic potentiodynamic polarization measurements as well as by monitoring the open circuit potential measurements with exposure time. Since secondary phases present (or developed during thermal ageing) in stainless steels have a significant influence on their corrosion behaviour, the estimation of these secondary phases by electrochemical methods has also been discussed. (author)

On LMFBR corrosion. Part II: Consideration of the in-reactor fuel-cladding system

International Nuclear Information System (INIS)

Bradbury, M.H.; Pickering, S.; Walker, C.T.; Whitlow, W.H.

1976-05-01

The scientific and technological aspects of LMFBR cladding corrosion are discussed in detail. Emphasis is placed on the influence of the irradiation environment and the effect of fuel and filler-gas impurities on the corrosion process. These studies are complemented by a concise review of out-of-pile simulation experiments that endeavour to clarify the role of the aggressive fission products cesium, tellurium and iodine. The principal models for cladding corrosion are presented and critically assessed. Areas of uncertainty are exposed and some pertinent experiments are suggested. Consideration is also given to some new observations regarding the role of stress in fuel-cladding reactions and the formation of ferrite in the corrosion zone of the cladding during irradiation. Finally, two technological solutions to the problem of cladding corrosion are proposed. These are based on the use of an oxygen buffer in the fuel and the application of a protective coating to the inner surface of the cladding

The influence of interstitial impurities on temperature ranges of deuterium retention in austenitic stainless steel 18Cr10NiTi

International Nuclear Information System (INIS)

Neklyudov, I.M.; Morozov, O.M.; Kulish, V.G.; Zhurba, V.I.; Galytsky, A.G.; Piatenko, E.V.

2009-01-01

The influence of nitrogen, oxygen and helium on the temperature range of deuterium retention in 18Cr10NiTi stainless steel (of AISI304L type) has been investigated. It is demonstrated that the introduction of oxygen, nitrogen or helium into 18Cr10NiTi steel extends the upper limit in the high-temperature range of deuterium retention. It has been found that for 18Cr10NiTi stainless steel, pre-irradiated with helium ions, the increase in the temperature range of deuterium retention occurs in steps: on attainment of helium concentration of ∼0.5 at.% He the temperature range increases by ∼100 K, and on attainment of helium concentration of ∼2.5 at.% He the temperature range increases by ∼350 K. The introduction of oxygen into 18Cr10NiTi stainless steel results in the increase of the temperature range of deuterium retention in the direction of rise in temperature. In the deuterium thermodesorption spectrum, this manifests itself by the occurrence of an additional low-amplitude peak with the maximum temperature T m ∼ 560 K. The introduction of nitric impurity into 18Cr10NiTi stainless steel results in the extension of the temperature range of deuterium retention towards higher temperatures.

Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

Energy Technology Data Exchange (ETDEWEB)

Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

2015-07-01

This work investigates strategies to mitigate stress corrosion cracking (SCC) in Zircaloy-4 sheathing materials. The CANLUB coatings currently used in CANDU reactors contain both alkali metal and alkaline earth metal impurities, which can exist as oxides (e.g., Na{sub 2}O and CaO). It is believed that when the corrosive fission product iodine reacts with these oxides, the iodine can be sequestered through the formation of an iodide (e.g.,NaI and CaI{sub 2}). The subsequent O{sub 2} release may repair cracks in the protective ZrO{sub 2} layer on the sheathing, shielding the Zircaloy-4 sheathing from further corrosive fission product attack. For this investigation, O{sub 2} gas, Na{sub 2}O, and CaO were separately introduced into an environment wherein slotted Zircaloy-4 rings endure mechanical stresses in iodine vapour at high temperatures. Controlled additions of O{sub 2} gas created a slight reduction in the corrosive attack on Zircaloy-4 sheathing, while the inclusion of Na{sub 2}O and CaO lead to greater reductions. (author)

Quantitative measures of corrosion and prevention: application to corrosion in agriculture

NARCIS (Netherlands)

Schouten, J.C.; Gellings, P.J.

1987-01-01

The corrosion protection factor (c.p.f.) and the corrosion condition (c.c.) are simple instruments for the study and evaluation of the contribution and efficiency of several methods of corrosion prevention and control. The application of c.p.f. and c.c. to corrosion and prevention in agriculture in

Corrosion of research reactor aluminium clad spent fuel in water

International Nuclear Information System (INIS)

2003-01-01

This report describes research performed in ten laboratories within the framework of the IAEA Co-ordinated Research Project on Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water. The project consisted of exposure of standard racks of corrosion coupons in the spent fuel pools of the participating research reactor laboratories and the evaluation of the coupons after predetermined exposure times, along with periodic monitoring of the storage water. A group of experts in the field contributed a state of the art review and provided technical supervision of the project. Localized corrosion mechanisms are notoriously difficult to understand, and it was clear from the outset that obtaining consistency in the results and their interpretation from laboratory to laboratory would depend on the development of an excellent set of experimental protocols. These experimental protocols are described in the report together with guidelines for the maintenance of optimum water chemistry to minimize the corrosion of aluminium clad research reactor fuel in wet storage. A large database on corrosion of aluminium clad materials has been generated from the CRP and the SRS corrosion surveillance programme. An evaluation of these data indicates that the most important factors contributing to the corrosion of the aluminium are: (1) High water conductivity (100-200 μS/cm); (2) Aggressive impurity ion concentrations (Cl - ); (3) Deposition of cathodic particles on aluminium (Fe, etc.); (4) Sludge (containing Fe, Cl - and other ions in concentrations greater than ten times the concentrations in the water); (5) Galvanic couples between dissimilar metals (stainless steel-aluminium, aluminium-uranium, etc); (6) Scratches and imperfections (in protective oxide coating on cladding); (7) Poor water circulation. These factors operating both independently and synergistically may cause corrosion of the aluminium. The single most important key to preventing corrosion is maintaining good

Determination of Ionization Coefficient of Atmospheric Helium in Dielectric Barrier Discharge

International Nuclear Information System (INIS)

Zhuo, Liang; Hai-Yun, Luo; Xin-Xin, Wang; Bo, Lv; Zhi-Cheng, Guan; Li-Ming, Wang

2008-01-01

A weakly luminous layer close to the anode is observed at time far ahead of the current pulse in dielectric barrier discharge of helium at atmospheric pressure and it is considered as the result of a very weak Townsend discharge. Based on the assumption that the space charge produced by this Townsend discharge is too small to distort the uniform electric field in the gas gap, the electrons have more or less the same energy over the entire gap and the spatial distribution of the discharge light is proportional to the distribution of electron density. This light distribution is obtained by processing side-view photograph of discharge gap using an intensified charge coupled device camera with an exposure time of 20 ns. By fitting a theoretically derived formula with the measured curve of light distribution, the Townsend electron ionization coefficient a is determined to be 31 cm −1 at E/p = 3.6 V·cm −1 ·Torr −1 , which is much higher than that obtained by solving the Boltzmann equation of pure helium. It is believed that penning ionization of helium metastables with impurity of nitrogen molecules makes great contribution to the experimentally determined α value. The contribution of this penning ionization to α is roughly estimated. (physics of gases, plasmas, and electric discharges)

Duct corrosion in the ventilating air conditioning system for Main Control Room

International Nuclear Information System (INIS)

Yamada, Kohei; Kobayashi, Takashi; Minami, Akiko; Fukuba, Kazushi

2014-01-01

Higashidori Nuclear Power Station, start-of-operation in December 2005, is a relatively new plant. We decided to get original data of air duct condition to determine maintenance policy of air duct, because planned maintenance of air duct has never been done and the corrosion of air duct has occurred in other plant. In January 2014, we found a corrosion-hole at the downstream of the inlet damper in the ventilating air conditioning system for Main Control Room (MCR). We supposed that the cause of rapid corrosion is related to the characteristic environment of this site. (author)

Study of hot corrosion of flakes of non purified graphite and of purified graphite

International Nuclear Information System (INIS)

Boule, Michel

1967-01-01

The author reports the study of hot corrosion of the Ticonderoga graphite. He reports the study of the defects of graphite flakes (structure defects due to impurities), the dosing of these impurities, and then their removal by purification. Flakes have then been oxidised by means of a specially designed apparatus. Based on photographs taken by optical and electronic microscopy, the author compares the oxidation features obtained in dry air and in humid air, between purified and non purified flakes. He also reports the study of the evolution of oxidation with respect to the initial rate of impurities, and the study of the evolution of oxidation features in humid air during oxidation. All these comparisons are made while taking the oxidation rate into account [fr

Parametric tests of the effects of water chemistry impurities on corrosion of Zr-alloys under simulated BWR condition

Energy Technology Data Exchange (ETDEWEB)

Shimada, S; Ito, K [Nippon Nuclear Fuel Development Co. Ltd., Oarai, Ibaraki (Japan); Lin, C C [GE Nucklear Energy (United States); Cheng, B [Electric Power Research Inst. (United States); Ikeda, T [Toshiba Corp. (Japan); Oguma, M [Hitachi, Ltd (Japan); Takei, T [Tokyo Electric Power Co., Inc. (Japan); Vitanza, C; Karlsen, T M [Institutt for Energiteknikk, Halden (Norway). OECD Halden Reaktor Projekt

1997-02-01

The Halden BWR corrosion test loop was constructed to evaluate the impact of water chemistry variables, heat flux and boiling condition on corrosion performance of Zr-alloys in a simulated BWR environment. The loop consists of two in-core rigs, one for testing fuel rod segments and the other for evaluating water chemistry variables utilizing four miniautoclaves. Ten coupon specimens are enclosed in each miniautoclave. The Zr-alloys for the test include Zircaloy-2 having different nodular corrosion resistance and five new alloys. The first and second of the six irradiation tests planned in this program were completed. Post-irradiation examination of those test specimens have shown that the test loop is capable of producing nodular corrosion on the fuel rod cladding tested under the reference chemistry condition. The miniautoclave tests showed that nodular corrosion could be formed without flux and boiling under some water chemistry conditions and the new alloys, generally, had higher corrosion resistance than the Zircaloy in high oxygen environments. (author). 5 refs, 4 figs, 5 tabs.

Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

Science.gov (United States)

Volkova, E. F.

2017-07-01

Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg - Mn, Mg - Al, Mg - Al - Mn, and Mg - Al - Zn - Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

Numerical studies of impurities in fusion plasmas

International Nuclear Information System (INIS)

Hulse, R.A.

1982-09-01

The coupled partial differential equations used to describe the behavior of impurity ions in magnetically confined controlled fusion plasmas require numerical solution for cases of practical interest. Computer codes developed for impurity modeling at the Princeton Plasma Physics Laboratory are used as examples of the types of codes employed for this purpose. These codes solve for the impurity ionization state densities and associated radiation rates using atomic physics appropriate for these low-density, high-temperature plasmas. The simpler codes solve local equations in zero spatial dimensions while more complex cases require codes which explicitly include transport of the impurity ions simultaneously with the atomic processes of ionization and recombination. Typical applications are discussed and computational results are presented for selected cases of interest

Long-time corrosion and high-temperature oxidation of zirconium alloys applied on NPP like fuel elements cover

International Nuclear Information System (INIS)

Vrtilkova, V.; Novotny, L.; Lingart, S.; Doukha, R.; Yarosh, Ya.; Kolenchik, Ya.

2007-01-01

Zirconium is applying in nuclear energy since 50-th of last century in capacity of material for cover production for fuel elements, reactor fuel and structural parts, and mainly due to both corrosion stability and low effective cross section for thermal neutrons capture. Impurities in doping elements form and alloy production technology has influence on mechanical and corrosion properties of finite alloy. Long-time corrosion tests for several zirconium alloys in forcing autoclave under different reaction conditions were carried out. After that process kinetics was studied, mass increase, hydrogen formation, zirconium hydride forming morphology, zirconium oxide layer thickness have been determined as well

Control of welding residual stress for ensuring integrity against fatigue and stress-corrosion cracking

International Nuclear Information System (INIS)

Mochizuki, Masahito

2007-01-01

The availability of several techniques for residual stress control is discussed in this paper. The effectiveness of these techniques in protecting from fatigue and stress-corrosion cracking is verified by numerical analysis and actual experiment. In-process control during welding for residual stress reduction is easier to apply than using post-weld treatment. As an example, control of the welding pass sequence for multi-pass welding is applied to cruciform joints and butt-joints with an X-shaped groove. However, residual stress improvement is confirmed for post-weld processes. Water jet peening is useful for obtaining a compressive residual stress on the surface, and the tolerance against both fatigue and stress-corrosion cracking is verified. Because cladding with a corrosion-resistant material is also effective for preventing stress-corrosion cracking from a metallurgical perspective, the residual stress at the interface of the base metal is carefully considered. The residual stress of the base metal near the clad edge is confirmed to be within the tolerance of crack generation. Controlling methods both during and after welding processes are found to be effective for ensuring the integrity of welded components

Corrosion control in electric power plants

International Nuclear Information System (INIS)

Syrett, B.C.

1992-01-01

This paper reports that corrosion of components in power plants costs the US electric power utility industry billions of dollars each year. Through the Electric Power Research Institute's (EPRI) research and development, several approaches have been developed to reduce these huge costs. They include improved materials selection procedures, coatings, cathodic protection, inhibitors, removal of aggressive species from the environment, and on-line corrosion monitoring. In addition, as part of an on-going technology transfer effort, EPRI is developing databases and expert systems that will help utilities obtain corrosion information and guide them in materials selection and failure analysis

Corrosion evaluation and control of cooling systems of nuclear power plants

International Nuclear Information System (INIS)

Kim, U. C.; Sung, K. W.; Na, J. W.

2002-04-01

We supplemented a database for evaluation of problems in high temperature corrosion degradation at domestic NPPs, and investigated corrosion mitigation methodologies for modification of water chemistry guidelines and operating conditions for life extension as follows: 1) crevice chemistry evaluation by using CAP code, hide-out return tests in a Crevice Test Apparatus, analysis of water chemistry guideline revision history; 2) analysis on main steam generator tube damages, H 2 -dependent crack propagation rate tests of Alloy 600 CRDM material, SCC test of Ni-based alloy in mid-ranged pH by electrochemical polarization and of reduced sulfur influence by corrosion potential measurement, Pb-and CuO-SCC behavior tests, TiO 2 inhibitor penetration test, SCC evaluation, electrochemical observation; 3) loop tests on erosion-corrosion resistance of piping material with ICr-1/2Mo and 21/4 Cr-1Mo, evaluation of current pH-controlling agents based on thermodynamic analysis of amines; 4) SCC susceptibility and H 2 -embrittlement tests of turbine material(3.5NiCrMoV); 5) analyses of Zn-compound for radioactivity reduction and of hydrolysis equilibrium with adsorption test against resins, CERT tests on PWSCC susceptibility of Alloy 600, evaluation of operation mode-dependent radiation level by using CRUSIM code; 6) solubility calculation of radiolysis products of NH 3 , the pH-controlling agent of small-and medium-sized reactors, temperature estimation for obtaining lowest N 2 solubility and of NH 3 content required for optimum pH control, fatigue crack growth test of SG materials(ASTM Grade 2 Ti)

Corrosion technology. V. 1

International Nuclear Information System (INIS)

Khan, I.H.

1989-01-01

This book has been produced for dissemination of information on corrosion technology, corrosion hazards and its control. Chapter one of this book presents an overall view of the subject and chapter 2-5 deals with electrochemical basics, types of corrosion, pourbaix diagrams and form of corrosion. The author explains polarization/kinetics of corrosion, passivity, aqueous corrosion and corrosion testing and monitoring in 6-11 chapters. The author hopes it will provide incentive to all those interested in the corrosion technology. (A.B.)

Zirconium alloy barrier having improved corrosion resistance

International Nuclear Information System (INIS)

Adamson, R.B.; Rosenbaum, H.S.

1983-01-01

A nuclear fuel element for use in the core of a nuclear reactor has a composite cladding container having a substrate and a dilute zirconium alloy liner bonded to the inside surface of the substrate. The dilute zirconium alloy liner forms about 1 to about 20 percent of the thickness of the cladding and is comprised of zirconium and a metal selected from the group consisting of iron, chromium, iron plus chromium, and copper. The dilute zirconium alloy liner shields the substrate from impurities or fission products from the nuclear fuel material and protects the substrate from stress corrosion and stress cracking. The dilute zirconium alloy liner displays greater corrosion resistance, especially to oxidation by hot water or steam than unalloyed zirconium. The substrate material is selected from conventional cladding materials, and preferably is a zirconium alloy. (author)

The influence of impurity and particle control on TMX-U [Tandem Mirror Experiment Upgrade] plasma operation

International Nuclear Information System (INIS)

Allen, S.L.; Yu, T.L.; Foote, J.H.; Pickles, W.L.

1985-11-01

A variety of techniques are used in TMX-U to control impurities and reflux: repeated plasma pulses, glow discharge cleaning (GDC), and gettering. A series of experiments under three different plasma-wall conditions was performed: no wall conditioning after a machine maintenance cycle, a glow-discharge-cleaned wall, and a gettered wall. Several plasma diagnostics to determine the effect of these procedures on TMX-U plasma parameters were used. Spectroscopic measurements indicated that GDC reduced impurities and increased the electron temperature, enabling full-duration beam-sustained plasma operation without a large number of repeated plasma pulses. Gettering further reduced the impurities and the neutral pressure, and this improved condition persisted for several shots after gettering was stopped. Measurements from residual gas analyzers and an end-loss ion spectrometer indicated that hydrogen is present in the plasma during the initial deuterium operation after pumpdown; the hydrogen level decreased after plasma operation with gettering, indicating reduced wall recycling

Corrosion characteristics of an aqueous self-cooled fusion blanket

International Nuclear Information System (INIS)

Bogaerts, W.F.; Embrechts, M.J.; Steiner, D.; Deutsch, L.; Jackson, D.

1986-01-01

A novel aqueous self-cooled blanket concept (ASCB) has recently been proposed. This blanket concept, as applied to a MARS-like tandem mirror reactor, consists of disks of spiraling tubes of Zircaloy-4 housed in a structural container of vanadium alloy (V-15 Ti-5 Cr). The Zircaloy tubes are cooled by a mixture of light and heavy water with 9 g of LiOH per 100 cm 3 of water dissolved in the coolant. A major issue for the feasibility of the integrated blanket coil concept is the chemical compatibility of the coolant and Zircaloy. Initial corrosion tests have been undertaken in order to resolve this question. Results clearly show that successful alloy heats can be prepared, for which corrosion problems will probably not be the limiting factor of the ASCB design concept. As is quite well known from fission engineering studies, small variations in the alloy compositions or in the metallurgical structure may, however, be able to cause significant alterations in the oxidation or corrosion rates. Further tests will be necessary to resolve the remaining uncertainties and to determine the behavior of successful alloy heats in the presence of trace impurities in order to address the sensitivity to localized corrosion phenomena such as pitting, stress corrosion cracking, and intergranular attack

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2015-01-01

The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in North America. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the highly corrosive hydrochloric acid (HCl) generated by the solid rocket boosters (SRBs). Numerous failures at the launch pads are caused by corrosion. The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. NASA has over fifty years of experience dealing with unexpected failures caused by corrosion and has developed expertise in corrosion control in the launch and other environments. The Corrosion Technology Laboratory at KSC evolved, from what started as an atmospheric exposure test site near NASAs launch pads, into a capability that provides technical innovations and engineering services in all areas of corrosion for NASA, external partners, and customers.This paper provides a chronological overview of NASAs role in anticipating, managing, and preventing corrosion in highly corrosive environments. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

Corrosion control of carbon steel using inhibitor of banana peel extract in acid diluted solutions

Science.gov (United States)

Komalasari; Utami, S. P.; Fermi, M. I.; Aziz, Y.; Irianti, R. S.

2018-04-01

Issues of corrosion happened in pipes, it was used as fluid transportation in the chemical industry. Corrosion cannot be preventing, however it could be controlled or blocked. Inhibitor addition is one of the method to control the corrosion inside the pipe. Corrosion inhibitors consisted of inorganic and organic compound inhibitors. Organic inhibitor is composed from synthetic and natural material. This study focused to evaluate the inhibition’s efficiency from banana peel to carbon steel in different concentration of inhibitor and immersing time in acid solution variation. The research employed inhibitor concentration of 0 gram/liter, 2 gram/liter, 4 gram/liter and 6 gram/liter, immersed time of carbon steel for 2, 4, 6, 8 and 10 hours. It was immersed in chloride acid solution of 0.5 M and 1.5 M. Carbon Steel AISI 4041 was used as specimen steel. Results were analyzed using corrosion rate evaluation for each specimens and inhibitor efficiencies determination. It was found that the specimen without inhibitor yielded fast corrosion rate in long immersing time and high concentration of HCl. However, the specimens with inhibitor gave lowest corrosion rate which was 78.59% for 6 gram/litre and 10 hours in 0.5 M HCl.

The effect of brazing parameters on corrosion behavior of brazed aluminum joints

Science.gov (United States)

Ghasimakbari, Farzam; Hadian, Ali Mohammad; Ershadrad, Soheil; Omidazad, Amir Mansour

2018-01-01

Fluid transmission pipes made of aluminum are widely used in petrochemical industries. For many applications, they have to be brazed to each other. The brazed joints, in many cases, are encountered with corrosive medias. This paper reports a part of a work to investigate the corrosion behavior of brazed AA6061 using AA4047 as filler metal with and without the use of flux under different brazing atmospheres. The samples brazed under air, vacuum, argon, and hydrogen atmospheres. The interfacial area of the joints was examined to ensure being free of any defects. The sides of each test piece were covered with an insulator and the surface of the joint was encountered to polarization test. The results revealed a significant difference of corrosion resistance. The samples that brazed under argon and hydrogen atmospheres had better corrosion resistance than other samples. The microstructure of the corroded joints revealed that the presence of defects, impurities due to use of flux and depth of filter metal penetration in base metal are crucial variables on the corrosion resistance of the joints.

Helium mobility in advanced nuclear ceramics

International Nuclear Information System (INIS)

Agarwal, Shradha

2014-01-01

The main goal of this work is to improve our knowledge on the mechanisms able to drive the helium behaviour in transition metal carbides and nitrides submitted to thermal annealing or ion irradiation. TiC, TiN and ZrC polycrystals were implanted with 3 MeV 3 He ions at room temperature in the fluence range 2 * 10 15 et 6 * 10 16 cm -2 . Some of them have been pre-irradiated with self-ions (14 MeV Ti or Zr). Fully controlled thermal annealing tests were subsequently carried out in the temperature range 1000 - 1600 C for two hours. The evolution of the helium depth distribution in function of implantation dose, temperature and pre-irradiation dose was measured thanks to the deuteron-induced nuclear reaction 3 He(d, p 0 ) 4 He between 900 keV and 1.8 MeV. The microstructure of implanted and annealed samples was investigated by transmission electron microscopy on thin foils prepared using the FIB technique. Additional characterization tools, as X-ray diffraction and Raman microspectrometry, have been also applied in order to obtain complementary information. Among the most relevant results obtained, the following have to be outlined: - double-peak helium depth profile was measured on as implanted sample for the three compounds. The first peak is located near the end of range and includes the major part of helium, a second peak located close to the surface corresponds to the helium atoms trapped by the native vacancies; - the helium retention capacity in transition metal carbides and nitrides submitted to fully controlled thermal treatments varies according to ZrC 0.92 ≤ TiC 0.96 ≤ TiN 0.96 ; - whatever the investigated material, a self-ion-induced pre-damaging does not modify the initial helium profile extent. The influence of the post-implantation thermal treatment remains preponderant in any case; - the apparent diffusion coefficient of helium is in the range 4 * 10 -18 - 2 * 10 -17 m 2 s -1 in TiC0.96 and 3.5 * 10 -19 - 5.3 * 10 -18 m 2 s -1 in TiN 0.96 between

The optimisation of limiter geometry to reduce impurity influx in tokamaks

International Nuclear Information System (INIS)

Matthews, G.F.; McCracken, G.M.; Sewell, P.; Goodall, D.H.J.; Stangeby, P.C.; Pitcher, C.S.

1987-01-01

Conventional limiters are designed to withstand large power loadings and hence are constructed with surfaces at grazing angles to the toroidal magnetic field. As a result any impurities released from the limiter surface are projected towards the centre of the plasma and are poorly screened from it. The impurity control limiter (ICL), an alternative concept which has an inverted geometry is discussed. The ICL shape is designed to direct the impurities towards the wall. Results are presented from a two-dimensional neutral particle code which maps the ionisation of carbon physically sputtered by deuterons from a carbon limiter. This ionisation source is coupled to a one-dimensional impurity transport code which calculates the implied central impurity density. The results demonstrate that the ICL achieves impurity control in two ways. Firstly, many of the sputtered impurities directed towards the wall are not ionised and return to the wall as neutrals. Secondly, much of the ionisation which does occur is located in the scrape-off layer. Here there is a strong ion sink which may also be enhanced by the flow of hydrogenic ions entraining impurity ions created close to the limiter surface. We conclude that a reduction in central impurity density of a factor of 10 is possible in a Tokamak such as DITE provided that the limiter is the main source of impurities. (author)

Recycling and particle control in DIII-D

International Nuclear Information System (INIS)

Jackson, G.L.

1991-11-01

Particle control of both hydrogen and impurity atoms is important in obtaining reproducible discharges with a low fraction of radiated power in the DIII-D tokamak. The main DIII-D plasma facing components are graphite tiles and Inconel. Hydrogenic species desorbed from graphite during a tokamak discharge can be a major fueling source, especially in unconditioned graphite where these species can saturate the surface regions. In this case the recycling coefficient can exceed unity, leading to an uncontrolled density rise. In addition to removing volatile hydrocarbons and oxygen, DIII-D vessel conditioning efforts have been directed at the reduction of particle fueling from the graphite tiles. Conditioning techniques include: baking to ≤ 400 degrees C, low power pulsed discharge cleaning, and glow discharges in deuterium, helium, neon, or argon. Helium glow wall conditioning, is now routinely performed before every tokamak discharge. The effects of these techniques on hydrogen recycling and impurity influxes will be presented. The Inconel walls, while not generally exposed to high heat fluxes, nevertheless represent a source of metal impurities which can lead to impurity accumulation in the discharge and a high fraction of radiated power, particularly in H-mode discharges at higher plasma currents, I p > 1.5 MA. To reduce metal influx a thin (∼100 nm) low Z film has been applied on all plasma facing surfaces in DIII-D. The application of the boron film, referred to as boronization has the additional benefit over a carbon film of further reducing the oxygen influx. Following the first boronization in DIII-D a regime of very high confinement (VH-mode) was observed, characterized by low ohmic target density, low Z eff , and low radiated power

Erosion-corrosion

International Nuclear Information System (INIS)

Aghili, B.

1999-05-01

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

Corrosion Thermodynamics of Magnesium and Alloys from First Principles as a Function of Solvation

Science.gov (United States)

Limmer, Krista; Williams, Kristen; Andzelm, Jan

Thermodynamics of corrosion processes occurring on magnesium surfaces, such as hydrogen evolution and water dissociation, have been examined with density functional theory (DFT) to evaluate the effect of impurities and dilute alloying additions. The modeling of corrosion thermodynamics requires examination of species in a variety of chemical and electronic states in order to accurately represent the complex electrochemical corrosion process. In this study, DFT calculations for magnesium corrosion thermodynamics were performed with two DFT codes (VASP and DMol3), with multiple exchange-correlation functionals for chemical accuracy, as well as with various levels of implicit and explicit solvation for surfaces and solvated ions. The accuracy of the first principles calculations has been validated against Pourbaix diagrams constructed from solid, gas and solvated charged ion calculations. For aqueous corrosion, it is shown that a well parameterized implicit solvent is capable of accurately representing all but the first coordinating layer of explicit water for charged ions.

Impurities in radioactive solutions for gamma spectroscopy

International Nuclear Information System (INIS)

Delgado, J.U.

1990-01-01

The absolute and relative methods for radioactive sources calibration, like 4 Πβ-γ and 4Πγ ionization chamber respectively, allows to reach 0,1% of exactiness in activity measurement, but cannot distinguish radioactive impurities that interfere in the activity. Then, one of the problems associated to a quality control of calibrated sources furnished to users is the identification and quantification of the impurities. In this work, a routine technical procedure, using the facilities of gamma spectrometry method that allows to identify and to determine the impurities relative contribution to the source main radionuclide activity, is described. (author) [pt

Cryogenic filter method produces super-pure helium and helium isotopes

Science.gov (United States)

Hildebrandt, A. F.

1964-01-01

Helium is purified when cooled in a low pressure environment until it becomes superfluid. The liquid helium is then filtered through iron oxide particles. Heating, cooling and filtering processes continue until the purified liquid helium is heated to a gas.

Six Sigma Evaluation of the High Level Waste Tank Farm Corrosion Control Program at the Savannah River Site

International Nuclear Information System (INIS)

Hill, P. J.

2003-01-01

Six Sigma is a disciplined approach to process improvement based on customer requirements and data. The goal is to develop or improve processes with defects that are measured at only a few parts per million. The process includes five phases: Identify, Measure, Analyze, Improve, and Control. This report describes the application of the Six Sigma process to improving the High Level Waste (HLW) Tank Farm Corrosion Control Program. The report documents the work performed and the tools utilized while applying the Six Sigma process from September 28, 2001 to April 1, 2002. During Fiscal Year 2001, the High Level Waste Division spent $5.9 million to analyze samples from the F and H Tank Farms. The largest portion of these analytical costs was $2.45 million that was spent to analyze samples taken to support the Corrosion Control Program. The objective of the Process Improvement Project (PIP) team was to reduce the number of analytical tasks required to support the Corrosion Control Program by 50 percent. Based on the data collected, the corrosion control decision process flowchart, and the use of the X-Y Matrix tool, the team determined that analyses in excess of the requirements of the corrosion control program were being performed. Only two of the seven analytical tasks currently performed are required for the 40 waste tanks governed by the Corrosion Control Program. Two additional analytical tasks are required for a small subset of the waste tanks resulting in an average of 2.7 tasks per sample compared to the current 7 tasks per sample. Forty HLW tanks are sampled periodically as part of the Corrosion Control Program. For each of these tanks, an analysis was performed to evaluate the stability of the chemistry in the tank and then to determine the statistical capability of the tank to meet minimum corrosion inhibitor limits. The analyses proved that most of the tanks were being sampled too frequently. Based on the results of these analyses and th e use of additional

CERN Technical Training 2002: Learning for the LHC! HEREF-2002 : HELIUM REFRIGERATION TECHNIQUES

CERN Multimedia

Davide Vitè

2002-01-01

Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2002 is a new course, in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2002 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2002 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (5 mornings and 2 afternoons), 21-25 October, 2002. Estimated cost: 300.- CHF Language: Bilingual English-French. The course support will be in English, the ...

Identification of controlling factors for the initiation of corrosion of fresh concrete sewers.

Science.gov (United States)

Jiang, Guangming; Sun, Xiaoyan; Keller, Jurg; Bond, Philip L

2015-09-01

The development of concrete corrosion in new sewer pipes undergoes an initiation process before reaching an active corrosion stage. This initiation period is assumed to last several months to years but the key factors affecting the process, and its duration, are not well understood. This study is therefore focused on this initial stage of the corrosion process and the effect of key environmental factors. Such knowledge is important for the effective management of corrosion in new sewers, as every year of life extension of such systems has a very high financial benefit. This long-term (4.5 year) study has been conducted in purpose-built corrosion chambers that closely simulated the sewer environment, but with control of three key environmental factors being hydrogen sulfide (H2S) gas phase concentration, relative humidity and air temperature. Fresh concrete coupons, cut from an industry-standard sewer pipe, were exposed to the corrosive conditions in the chambers, both in the gas phase and partially submerged in wastewater. A total of 36 exposure conditions were investigated to determine the controlling factors by regular retrieval of concrete coupons for detailed analysis of surface pH, sulfur compounds (elemental sulfur and sulfate) and concrete mass loss. Corrosion initiation times were thus determined for different exposure conditions. It was found that the corrosion initiation time of both gas-phase and partially-submerged coupons was positively correlated with the gas phase H2S concentration, but only at levels of 10 ppm or below, indicating that sulfide oxidation rate rather than the H2S concentration was the limiting factor during the initiation stage. Relative humidity also played a role for the corrosion initiation of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as these coupons were in direct contact with the sewage and hence did have sufficient moisture to enable the microbial processes to proceed. The

Smart Coatings for Corrosion Protection

Science.gov (United States)

Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

2016-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

Impurity production and transport in the boundary layer of tokamaks

International Nuclear Information System (INIS)

McCracken, G.M.

1987-01-01

The processes by which impurities are produced and enter the discharge are discussed. Emphasis is placed on sputtering at the limiter and an analytical global model is described which incorporates the self-stabilizing effects whch control the edge temperature. Predictions of the scaling of edge temperature and of total radiated power are compared with experimental data from JET and other tokamaks operating with limiters. Under many conditions the scaling of the edge conditions and of the radiated power is accurately predicted. Impurity transport in the boundary and the question of how to control the boundary layer is then discussed. The example of the Impurity Control Limiter on DITE is described. (author)

Final report on the Controlled Cold Helium Spill Test in the LHC tunnel at CERN

CERN Document Server

Dufay-Chanat, L; Casas-Cubillos, J; Chorowski, M; Grabowski, M; Jedrusyna, A; Lindell, G; Nonis, M; Koettig, T; Vauthier, N; van Weelderen, R; Winkler, T

2015-01-01

The 27 km circumference LHC underground tunnel is a space in which the helium cooled LHC magnets are installed. The vacuum enclosures of the superconducting magnets are protected by over-pressure safety relief devices that open whenever cold helium escapes either from the magnet cold enclosure or from the helium supply headers, into this vacuum enclosure. A 3-m long no stay zone around these devices is defined based on scale model studies, protecting the personnel against cold burns or asphyxia caused by such a helium release event. Recently, several simulation studies have been carried out modelling the propagation of the helium/air mixture, resulting from the opening of such a safety device, along the tunnel. The released helium flows vary in the range between 1 kg/s and 0.1 kg/s. To validate these different simulation studies, real life mock-up tests have been performed inside the LHC tunnel, releasing helium flow rates of 1 kg/s, 0.3 kg/s and 0.1 kg/s. For each test, up to 1000 liters of liquid helium wer...

Helium-induced weld degradation of HT-9 steel

International Nuclear Information System (INIS)

Wang, Chin-An; Chin, B.A.; Lin, Hua T.; Grossbeck, M.L.

1992-01-01

Helium-bearing Sandvik HT-9 ferritic steel was tested for weldability to simulate the welding of structural components of a fusion reactor after irradiation. Helium was introduced into HT-9 steel to 0.3 and 1 atomic parts per million (appm) by tritium doping and decay. Autogenous single pass full penetration welds were produced using the gas tungsten arc (GTA) welding process under laterally constrained conditions. Macroscopic examination showed no sign of any weld defect in HT-9 steel containing 0.3 appm helium. However, intergranular micro cracks were observed in the HAZ of HT-9 steel containing 1 appm helium. The microcracking was attributed to helium bubble growth at grain boundaries under the influence of high stresses and temperatures that were present during welding. Mechanical test results showed that both yield strength (YS) and ultimate tensile strength (UTS) decreased with increasing temperature, while the total elongation increased with increasing temperature for all control and helium-bearing HT-9 steels

Diffusion-controlled regime of surface-wave-produced plasmas in helium gas

International Nuclear Information System (INIS)

Berndt, J; Makasheva, K; Schlueter, H; Shivarova, A

2002-01-01

The study presents a numerical fluid-plasma model of diffusion-controlled surface-wave-sustained discharges in helium gas. The self-consistent behaviour of the discharge based on the interrelation between plasma density and Θ, the power absorbed on average by one electron, is described. The nonlinear process of step ionization in the charged particle balance equation is the main factor, which ensures the self-consistency. However, it is shown that in helium discharges, the ionization frequencies enter the dependence of Θ on the plasma density also through the ambipolar-diffusion coefficient. Results at two different values of the gas pressure and of the wave frequency are discussed. The lower value of the gas pressure is chosen according to the condition to have a pure diffusion-controlled regime without interference with a transition to the free-fall regime. The boundary condition for the ion flux at the wall sheath is used for determination of the value of μ, the quantity denoting the degree of the radial plasma-density inhomogeneity which, together with the electron-neutral elastic collision frequency, influences the wave propagation characteristics. The two values of the wave frequency chosen provide descriptions of high-frequency and microwave discharges. The model results in the self-consistent structure of the discharge: interrelated variations along the discharge length of wavenumber, space damping rate, Θ, plasma density and electron temperature. The power necessary for sustaining discharges of a given length is also calculated. Comparisons with argon discharges are shown

Effect of HEH[EHP] impurities on the ALSEP solvent extraction process

Energy Technology Data Exchange (ETDEWEB)

Holfeltz, Vanessa E. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR, USA; Campbell, Emily L. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; Peterman, Dean R. [Aqueous Separations and Radiochemistry Department, Idaho National Laboratory, Idaho Falls, ID, USA; Standaert, Robert F. [Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Biochemistry & amp, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA; Biology & amp, Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Shull Wollan Center — a Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Paulenova, Alena [School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR, USA; Lumetta, Gregg J. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; Levitskaia, Tatiana G. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA

2017-12-20

In solvent extraction processes, organic phase impurities can negatively impact separation factors, hydrolytic performance, and overall system robustness. This affects the process-level viability of a separation concept and necessitates knowledge of the behavior and mechanisms to control impurities in the solvent. The most widespread way through which impurities are introduced into a system is through impure extractants and/or diluents used to prepare the solvent, and often development of new purification schemes to achieve the desired level of purity is needed. In this work, the acidic extractant, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP])—proposed for application in extractive processes aimed at separating trivalent minor actinides from lanthanides and other fission products—is characterized with respect to its common impurities and their impact on Am(III) stripping in the Actinide Lanthanide SEParation (ALSEP) system. To control impurities in HEH[EHP], existing purification technologies commonly applied for the acidic organophosphorus reagents are reviewed, and a new method specific to HEH[EHP] purification is presented.

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

Alkali Metal Coolants. Proceedings of the Symposium on Alkali Metal Coolants - Corrosion Studies and System Operating Experience

Energy Technology Data Exchange (ETDEWEB)

NONE

1967-06-15

Proceedings of a Symposium organized by the IAEA and held in Vienna, 28 November - 2 December 1966. The meeting was attended by 107 participants from 16 countries and two international organizations. Contents: Review papers (2 papers); Corrosion of steels and metal alloys (6 papers); Mass transfer in alkali metal systems, behaviour of carbon (5 papers); Effects of sodium environment on mechanical properties of materials (3 papers); Effect of water leakage into sodium systems (2 papers); Design-and operation of testing apparatus (6 papers); Control, measurements and removal of impurities (13 papers); Corrosion by other alkali metals: NaK, K, Li, Cs (6 papers); Behaviour of fission products (3 papers). Each paper is in its original language (32 English, 6 French and 8 Russian) and is preceded by an abstract in English and one in the original language if this is not English. Discussions are in English. (author)

Alkali Metal Coolants. Proceedings of the Symposium on Alkali Metal Coolants - Corrosion Studies and System Operating Experience

International Nuclear Information System (INIS)

1967-01-01

Proceedings of a Symposium organized by the IAEA and held in Vienna, 28 November - 2 December 1966. The meeting was attended by 107 participants from 16 countries and two international organizations. Contents: Review papers (2 papers); Corrosion of steels and metal alloys (6 papers); Mass transfer in alkali metal systems, behaviour of carbon (5 papers); Effects of sodium environment on mechanical properties of materials (3 papers); Effect of water leakage into sodium systems (2 papers); Design-and operation of testing apparatus (6 papers); Control, measurements and removal of impurities (13 papers); Corrosion by other alkali metals: NaK, K, Li, Cs (6 papers); Behaviour of fission products (3 papers). Each paper is in its original language (32 English, 6 French and 8 Russian) and is preceded by an abstract in English and one in the original language if this is not English. Discussions are in English. (author)

Technical basis for hydrogen-water chemistry: Laboratory studies of water chemistry effects on SCC [stress-corrosion-cracking

International Nuclear Information System (INIS)

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

1986-10-01

The influence of different impurities, viz., oxyacids and several chloride salts, on the stress-corrosion-cracking (SCC) of sensitized Type 304 stainless steel (SS) was investigated in constant-extension-rate-tensile (CERT) tests in 289 0 C water at a low dissolved-oxygen concentration ( 0 C in low-oxygen environments with and without sulfate at low concentrations. In these experiments, the crack growth behavior of the materials was correlated with the type and concentration of the impurities and the electrochemical potentials of Type 304 SS and platinum electrodes in the simulated hydrogen-water chemistry environments. The information suggests that better characterization of water quality, through measurement of the concentrations of individual species (SO 4 2- , NO 3 - , Cu 2+ , etc.) coupled with measurements of the corrosion and redox potentials at high temperatures will provide a viable means to monitor and ultimately improve the performance of BWR system materials

Helium cryogenics

CERN Document Server

Van Sciver, Steven W

2012-01-01

Twenty five years have elapsed since the original publication of Helium Cryogenics. During this time, a considerable amount of research and development involving helium fluids has been carried out culminating in several large-scale projects. Furthermore, the field has matured through these efforts so that there is now a broad engineering base to assist the development of future projects. Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspe...

Low corrosive chemical decontamination method using pH control. 1. Basic system

International Nuclear Information System (INIS)

Nagase, Makoto; Ishida, Kazushige; Uetake, Naohito; Anazawa, Kazumi; Nakamura, Fumito; Yoshikawa, Hiroo; Tamagawa, Tadashi; Furukawa, Kiyoharu

2001-01-01

A new low corrosive decontamination method was developed which uses both oxalic acid and hydrazine as the reducing agent and potassium permanganate as the oxidizing agent. Less corrosion of structural materials during the decontamination is realized by pH control of the reducing agent. The pH of 2.5, attained by adding hydrazine to oxalic acid, was the optimum pH for maintaining a high decontamination effect and lowering the corrosion at the same time. As this reducing agent can be decomposed into carbon dioxide, nitrogen and water by using a catalyst column with hydrogen peroxide, the amount of secondary radioactive waste is small. These good features were demonstrated through actual plant decontamination tasks. (author)

KSTAR Helium Refrigeration System Design and Manufacturing

International Nuclear Information System (INIS)

Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

2006-01-01

The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

Effects of hydrogen and helium irradiation on optical property of tungsten

International Nuclear Information System (INIS)

Kazutoshi Tokunaga; Tadashi Fujiwara; Naoaki Yoahida; Koichiro Ezato; Satoshi Suzuki; Masato Akiba

2006-01-01

Plasma-wall interactions cause surface modification, compositional and structural change on material surface due to sputtering, impurity deposition and radiation damage, etc. As a result, optical property (response of electron and lattice on material for electromagnetic wave) on surface of the plasma facing components would be changed. In particular, diagnostic components, such as metallic mirrors, mounted close to the plasma will be subjected by plasma particles such as hydrogen isotope and helium in the fusion devices. It is well recognized that decrease of optical reflectivity of the metallic mirrors due to the plasma-material interaction will be critical issues for the plasma diagnosis. In the present work, tungsten has been irradiated by hydrogen and helium beam. After that, optical reflectivity and surface modification have been measured to investigate fundamental process of optical property change due to hydrogen and helium beam irradiation. Samples used in the present experiment are powder metallurgy tungsten. Hydrogen and helium irradiations are performed in an ion beam facility at JAEA, the Particle Beam Engineering Facility (PBEF). The energy of hydrogen and helium is 19.0 and 18.7 keV, respectively. Beam duration is 1.3 - 3.5 s. The samples are irradiated up to a fluence of the orders between 10 22 and 10 24 He/m 2 by the repeated pulse irradiations of 14-450 cycles. The surface temperature is measured with an optical pyrometer. After the repeated irradiation experiments, surface modification and composition are examined with a scanning electron microscope (SEM) and a scanning probe microscope (SPM), etc. In addition, the optical reflectivity is measured in the wavelength range of 190 - 2400 nm using an ultraviolet-visible and near-infrared spectrophotometer. The reflectivity after the irradiation decreases depending on fluence and a peak temperature of the samples during the irradiation. In addition, their reflectivity spectra also change. This means

Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

International Nuclear Information System (INIS)

Semwal, P; Khan, Z; Raval, D C; Dhanani, K R; George, S; Paravastu, Y; Prakash, A; Thankey, P; Ramesh, G; Khan, M S; Saikia, P; Pradhan, S

2017-01-01

Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail. (paper)

Corrosion '98: 53. annual conference and exposition, proceedings

International Nuclear Information System (INIS)

Anon.

1998-01-01

This conference was divided into the following sections: Corrosion in Gas Treating; Problems and Solutions in Commercial Building Water Systems; Green Corrosion/Scale Inhibitors; Atmospheric Corrosion; AIRPOL Update/98; Rubber Lining--Answers to Many Problems; Interference Problems; Environmental Assisted Cracking: Fundamental Research and Industrial Applications; Corrosion in Nuclear Systems; New Developments in Scale and Deposit Control; Corrosion and Corrosion Protection in the Transportation Industries; What's All the Noise About--Electrochemical That Is; Refining Industry Corrosion; Corrosion Problems in Military Hardware: Case Histories, Fixes and Lessons Learned; Cathodic Protection Test Methods and Instrumentation for Underground and On-grade Pipelines and Tanks; Recent Developments in Volatile Corrosion Inhibitors; Corrosion in Supercritical Fluids; Microbiologically Influenced Corrosion; Advances in Understanding and Controlling CO 2 Corrosion; Managing Corrosion with Plastics; Material Developments for Use in Exploration and Production Environments; Corrosion in Cold Regions; The Effect of Downsizing and Outsourcing on Cooling System Monitoring and Control Practices; New Developments in Mechanical and Chemical Industrial Cleaning; Mineral Scale Deposit Control in Oilfield Related Operations; Biocides in Cooling Water; Corrosion and Corrosion Control of Reinforced Concrete Structures; Materials Performance for Fossil Energy Conversion Systems; Marine corrosion; Thermal Spray--Coating and Corrosion Control; Flow Effects on Corrosion in Oil and Gas Production; Corrosion Measurement Technologies; Internal Pipeline Monitoring--Corrosion Monitoring, Intelligent Pigging and Leak Detection; Cathodic Protection in Natural Waters; Corrosion in Radioactive Liquid Waste Systems; On-line Hydrogen Permeation Monitoring Equipment and Techniques, State of the Art; Water Reuse and Recovery; Performance of Materials in High Temperature Environments; Advances in Motor

Particle and energy transport studies on TFTR and implications for helium ash in future fusion devices

International Nuclear Information System (INIS)

Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Bell, R.E.; Grek, B.; Hulse, R.A.; Johnson, D.W.; Hill, K.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.

1992-01-01

Particle and energy transport in tokamak plasmas have long been subjects of vigorous investigation. Present-day measurement techniques permit radially resolved studies of the transport of electron perturbations, low- and high-Z impurities, and energy. In addition, developments in transport theory provide tools that can be brought to bear on transport issues. Here, we examine local particle transport measurements of electrons, fully-stripped thermal helium, and helium-like iron in balanced-injection L-mode and enhanced confinement deuterium plasmas on TFTR of the same plasma current, toroidal field, and auxiliary heating power. He 2+ and Fe 24+ transport has been studied with charge exchange recombination spectroscopy, while electron transport has been studied by analyzing the perturbed electron flux following the same helium puff used for the He 2+ studies. By examining the electron and He 2+ responses following the same gas puff in the same plasmas, an unambiguous comparison of the transport of the two species has been made. The local energy transport has been examined with power balance analysis, allowing for comparisons to the local thermal fluxes. Some particle and energy transport results from the Supershot have been compared to a transport model based on a quasilinear picture of electrostatic toroidal drift-type microinstabilities. Finally, implications for future fusion reactors of the observed correlation between thermal transport and helium particle transport is discussed

Controlling Thermodynamic Properties of Ferromagnetic Group-IV Graphene-Like Nanosheets by Dilute Charged Impurity

Science.gov (United States)

Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos

2017-05-01

Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-IV elements including silicene, germanene and stanene within the Green’s function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene (stanene) has the maximum (minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases (decreases) with impurity concentration in silicene (germanene and stanene) structure.

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2014-01-01

Corrosion is the degradation of a material that results from its interaction with the environment. The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the 70 tons of highly corrosive hydrochloric acid that were generated by the solid rocket boosters. Numerous failures at the launch pads are caused by corrosion.The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. As a result of fifty years of experience with launch and ground operations in a natural marine environment that is highly corrosive, NASAs Corrosion Technology Laboratory at KSC is a major source of corrosion control expertise in the launch and other environments. Throughout its history, the Laboratory has evolved from what started as an atmospheric exposure facility near NASAs launch pads into a world-wide recognized capability that provides technical innovations and engineering services in all areas of corrosion for NASA and external customers.This presentation will provide a historical overview of the role of NASAs Corrosion Technology in anticipating, managing, and preventing corrosion. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

On use of beryllium in fusion reactors: Resources, impurities and necessity of detritiation after irradiation

Energy Technology Data Exchange (ETDEWEB)

Kolbasov, B.N., E-mail: b.kolbasov@yandex.ru; Khripunov, V.I., E-mail: Khripunov_VI@nrcki.ru; Biryukov, A.Yu.

2016-11-01

Highlights: • Potential needs in Be for fusion power engineering may exceed Be resources. • Be recycling after its operation in a fusion power plant (FPP) seems inevitable. • U impurity in Be seriously impairs environmental properties of fusion power plants. • Upon burial of irradiated Be the main problems are caused by U and {sup 3}H impurities. • Clearance of Be extracted from a FPP is impossible due to U impurity. - Abstract: Worldwide identified resources of beryllium somewhat exceed 80 000 t. Beryllium production in all the countries of the world in 2012 was about 230 t. At the same time, some conceptual designs of fusion power reactors envisage utilization of several hundred tons of this metal. Therefore return of beryllium into the production cycle (recycling) will be necessary. The beryllium ore from some main deposits has uranium content inadmissible for fusion reactors. This fact raises a question on the need to develop and apply an economically acceptable technology for beryllium purification from the uranium. Practically any technological procedure with beryllium used in fusion reactors requires its detritiation. A study of tritium and helium release from irradiated beryllium at different temperatures and rates of temperature increase was performed at Kurchatov Institute.

Liquid helium

CERN Document Server

Atkins, K R

1959-01-01

Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

Evaluation of cover gas impurities and their effects on the dry storage of LWR [light-water reactor] spent fuel

International Nuclear Information System (INIS)

Knoll, R.W.; Gilbert, E.R.

1987-11-01

The purposes of this report are to (1) identify the sources of impurity gases in spent fuel storage casks; (2) identify the expected concentrations and types of reactive impurity gases from these sources over an operating lifetime of 40 years; and (3) determine whether these impurities could significantly degrade cladding or exposed fuel during this period. Four potential sources of impurity gases in the helium cover gas in operating casks were identified and evaluated. Several different bounding cases have been considered, where the reactive gas inventory is either assumed to be completely gettered by the cladding or where all oxygen is assumed to react completely with the exposed fuel. It is concluded that the reactive gas inventory will have no significant effect on the cladding unless all available oxygen reacts with the UO 2 fuel to produce U 3 O 8 at one or two cladding breaches. Based on Zircaloy oxidation data, the oxygen inventory in a fully loaded pressurized water reactor cask such as the Castor-V/21 will be gettered by the Zircaloy cladding in about 1 year if the peak cladding temperature within the task is ≥300 0 C. Only a negligible decrease in the thickness of the cladding would result. 24 refs., 4 tabs

Mitigation of caustic stress corrosion cracking of steam generator tube materials by blowdown -a case study

International Nuclear Information System (INIS)

Dutta, Anu; Patwegar, I.A.; Chaki, S.K.; Venkat Raj, V.

2000-01-01

The vertical U-tube steam generators are among the most important equipment in nuclear power plants as they form the vital link between the reactor and the turbogenerator. Over ∼ 35 years of operating experience of water cooled reactor has demonstrated that steam generator tubes are susceptible to various forms of degradation. This degradation leads to failure and outages of the power plant. A majority of these failures have been attributed to concentrated alkali attacks in the low flow areas such as crevices in the tube to tube sheet joints, baffle plate location and the areas of sludge deposits. Free hydroxides can be produced by improper maintenance of phosphate chemical control in the secondary side of the steam generators and also by the thermal decomposition of impurities present in the condenser cooling water which may leak into the feed water through the condenser tubes. The free hydroxides concentrate in the low flow areas. This buildup of free hydroxide in combination with residual stress leads to caustic stress corrosion cracking. In order to mitigate caustic stress corrosion cracking of Inconel 600 tubes, the trend is to avoid phosphate dosing. Instead All Volatile Treatment (AVT) for secondary water is used backed by full flow condensate polishing. Sodium hydroxide concentration is now being considered as the basis for steam generator blowdown. A methodology has been established for determining the blowdown requirement in order to mitigate caustic stress corrosion cracking in the secondary side of the vertical U-tube natural circulation steam generator. A case study has been carried out for zero solid treatment (AVT coupled with full flow condensate polishing plant) water chemistry. Only continuous blowdown schemes have been studied based on maximum caustic concentration permissible in the secondary side of the steam generator. The methodology established can also be used for deciding concentration of any other impurities

Corrosion control for the Hanford site waste transfer system

International Nuclear Information System (INIS)

Haberman, J.H.

1995-01-01

Processing large volumes of spent reactor fuel and other related waste management activities produced radioactive wastes which have been stored in underground high-level waste storage tanks since the 1940s. The effluent waste streams from the processing facilities were stored underground in high-level waste storage tanks. The waste was transferred between storage tanks and from the tanks to waste processing facilities in a complex network of underground piping. The underground waste transfer system consists of process piping, catch tanks, lift tanks, diversion boxes, pump pits, valves, and jumpers. Corrosion of the process piping from contact with the soil is a primary concern. The other transfer system components are made of corrosion-resistant alloys or they are isolated from the underground environment and experience little degradation. Corrosion control of the underground transfer system is necessary to ensure that transfer routes will be available for future waste retrieval, processing,a nd disposal. Today, most waste transfer lines are protected by an active impressed-current cathodic protection (CP) system. The original system has been updated. Energization surveys and a recent base-line survey demonstrate that system operational goals are met

Automatic PID Control Loops Design for Performance Improvement of Cryogenic Turboexpander

International Nuclear Information System (INIS)

Joshi, D.M.; Patel, H.K.; Shah, D.K.

2015-01-01

Cryogenics field involves temperature below 123 K which is much less than ambient temperature. In addition, many industrially important physical processes—from fulfilling the needs of National Thermonuclear Fusion programs, superconducting magnets to treatment of cutting tools and preservation of blood cells, require extreme low temperature. The low temperature required for liquefaction of common gases can be obtained by several processes. Liquefaction is the process of cooling or refrigerating a gas to a temperature below its critical temperature so that liquid can be formed at some suitable pressure which is below the critical pressure. Helium liquefier is used for the liquefaction process of helium gas. In general, the Helium Refrigerator/Liquefier (HRL) needs turboexpander as expansion machine to produce cooling effect which is further used for the production of liquid helium. Turboexpanders, a high speed device that is supported on gas bearings, are the most critical component in many helium refrigeration systems. A very minor fault in the operation and manufacturing or impurities in the helium gas can destroy the turboexpander. However, since the performance of expanders is dependent on a number of operating parameters and the relations between them are quite complex, the instrumentation and control system design for turboexpander needs special attention. The inefficiency of manual control leads to the need of designing automatic control loops for turboexpander. Proper design and implementation of the control loops plays an important role in the successful operation of the cryogenic turboexpander. The PID control loops has to be implemented with accurate interlocks and logic to enhance the performance of the cryogenic turboexpander. For different normal and off-normal operations, speeds will be different and hence a proper control method for critical rotational speed avoidance is must. This paper presents the design of PID control loops needed for the

Protection of type 316 austenitic stainless steel from intergranular stress corrosion cracking by thermo-mechanical treatment

International Nuclear Information System (INIS)

Kiuchi, Kiyoshi; Tsuji, Hirokazu; Kondo, Tatsuo

1980-03-01

Thermomechanical treatment that causes carbide stabilizing aging of cold worked material followed by recrystallization heating made standard stainless steels highly resistant to intergranular corrosion and stress corrosion cracking in different test environments. After a typical thermal history of simulated welding, several IGSCC susceptibility tests were made. The results showed that the treatment was successful in type 316 steel in wide range of conditions, while type 304 was protected only to a small extent even by closely controlled treatment. Response of the materials to the sensitizing heating in terms of impurity segregation at grain boundaries was also examined by means of microchemical analysis. Advantage of method is that no special care is required in selecting heats of material, so that conventional type 316 is usable by improving the mechanical properties substantially through the treatment. In some optimized cases the mechanical property improvement was typically recognized by the yield strength by about 20% higher at room temperature, compared with the material mill annealed. (author)

Nonlinear hydrodynamic equations for superfluid helium in aerogel

International Nuclear Information System (INIS)

Brusov, Peter N.; Brusov, Paul P.

2003-01-01

Aerogel in superfluids is studied very intensively during last decade. The importance of these systems is connected to the fact that this allows to investigate the influence of impurities on superfluidity. We have derived for the first time nonlinear hydrodynamic equations for superfluid helium in aerogel. These equations are generalization of McKenna et al. equations for nonlinear hydrodynamics case and could be used to study sound propagation phenomena in aerogel-superfluid system, in particular--to study sound conversion phenomena. We have obtained two alternative sets of equations, one of which is a generalization of a traditional set of nonlinear hydrodynamics equations for the case of an aerogel-superfluid system and, the other one represents a la Putterman equations (equation for v→ s is replaced by equation for A→=((ρ n )/(ρσ))w→, where w→=v→ n -v→ s )

Corrosion of graphitic high temperature reactor materials in steam/helium mixtures at total pessures of 3-55 bar and temperatures of 900-1150 C (1173-1423K)

International Nuclear Information System (INIS)

Hinssen, H.K.; Loenissen, K.J.; Katscher, W.; Moormann, R.

1993-03-01

In course of accident examination for (HTR), experiments on the corrosion behavior of graphitic reactor materials in steam have been performed a total pressures of 3-55bar and temperatures of 900-1150 C (1173-1423K); these experiments and their evaluation are documented here. Reactor materials examined are the structure graphite V483T2 and the fuel element matrices A3-27 and A3-3. In all experiments, the steam partial pressure was 474mbar (inert gas helium). The dependence of reaction rates and density profiles on burn-off, total pressure and temperature has been examined. Experimental reaction rates depending on burn-off are fitted by theoretical curves, a procedure, which allows rate comparison for a well defined burn-off. Comparing rates as a function of total pressure, V483T2 shows a linear dependence on 1√p total , whereas for matrix materials a pressure independent rate was found for p total 4mm for A3-3. (orig.) [de

Corrosion in CO2 Post-Combustion Capture with Alkanolamines – A Review

Directory of Open Access Journals (Sweden)

Kittel J.

2014-09-01

Full Text Available CO2 capture and storage plays an important part in industrial strategies for the mitigation of greenhouse gas emissions. CO2 post-combustion capture with alkanolamines is well adapted for the treatment of large industrial point sources using combustion of fossil fuels for power generation, like coal or gas fired power plants, or the steel and cement industries. It is also one of the most mature technologies to date, since similar applications are already found in other types of industries like acid gas separation, although not at the same scale. Operation of alkanolamine units for CO2 capture in combustion fumes presents several challenges, among which corrosion control plays a great part. It is the aim of this paper to present a review of current knowledge on this specific aspect. In a first part, lessons learnt from several decades of use of alkanolamines for natural gas separation in the oil and gas industry are discussed. Then, the specificities of CO2 post-combustion capture are presented, and their consequences on corrosion risks are discussed. Corrosion mitigation strategies, and research and development efforts to find new and more efficient solvents are also highlighted. In a last part, concerns about CO2 transport and geological storage are discussed, with recommendations on CO2 quality and concentration of impurities.

CALCULATED REGENERATOR PERFORMANCE AT 4 K WITH HELIUM-4 AND HELIUM-3

International Nuclear Information System (INIS)

Radebaugh, Ray; Huang Yonghua; O'Gallagher, Agnes; Gary, John

2008-01-01

The helium-4 working fluid in regenerative cryocoolers operating with the cold end near 4 K deviates considerably from an ideal gas. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature. Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators. An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power. The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN3.3, which was used to model regenerator performance with either helium-4 or helium-3. With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers. The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared. The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies

CERN Technical Training 2002: Learning for the LHC ! HeREF-2002 : Helium Refrigeration Techniques

CERN Multimedia

Davide Vitè

2002-01-01

Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2002 is a new course, in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2002 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2002 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (5 mornings and 2 afternoons), 21-25 October 2002. Estimated cost: 300.- CHF Language: Bilingual English-French. The course support will be in English, the...

Corrosion of carbon steel in the [P_1_4_6_6_6][Br] ionic liquid: The effects of γ-radiation and cover gas

International Nuclear Information System (INIS)

Morco, Ryan P.; Musa, Ahmed Y.; Momeni, Mojtaba; Wren, J.C.

2016-01-01

Highlights: • Carbon steel corrosion in non-aqueous ionic liquid ([P_1_4_6_6_6] [Br]) electrolyte. • Gamma-irradiation results to less corrosion, forming protective oxides. • Substantial corrosion is seen in the absence of gamma-radiation. • A corrosion mechanism is proposed for the observed results. - Abstract: The corrosion of carbon steel in the ionic liquid (IL) [P_1_4_6_6_6] [Br] was studied with the IL in contact with an inert (Ar) or oxidizing (air) cover gas in the presence and absence of γ-radiation. Significant corrosion was observed for the tests performed in the absence of γ-radiation while a protective oxide layer is formed in the presence of γ-radiation. The corrosion is attributed to the presence of impurity H_2O and O_2 dissolved in the IL, and a corrosion mechanism is proposed.

Grain boundary corrosion of copper canister material

International Nuclear Information System (INIS)

Fennell, P.A.H.; Graham, A.J.; Smart, N.R.; Sofield, C.J.

2001-03-01

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters

Atomistic simulation of helium bubble nucleation in palladium

Energy Technology Data Exchange (ETDEWEB)

Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

2009-09-15

A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

Temperature dependent mobility measurements of alkali earth ions in superfluid helium

Science.gov (United States)

Putlitz, Gisbert Zu; Baumann, I.; Foerste, M.; Jungmann, K.; Riediger, O.; Tabbert, B.; Wiebe, J.; Zühlke, C.

1998-05-01

Mobility measurements of impurity ions in superfluid helium are reported. Alkali earth ions were produced with a laser sputtering technique and were drawn inside the liquid by an electric field. The experiments were carried out in the temperature region from 1.27 up to 1.66 K. The temperature dependence of the mobility of Be^+-ions (measured here for the first time) differs from that of the other alkali earth ions Mg^+, Ca^+, Sr^+ and Ba^+, but behaves similar to that of He^+ (M. Foerste, H. Günther, O. Riediger, J. Wiebe, G. zu Putlitz, Z. Phys. B) 104, 317 (1997). Theories of Atkins (A. Atkins, Phys. Rev.) 116, 1339 (1959) and Cole (M.W. Cole, R.A. Bachmann Phys. Rev. B) 15, 1388 (1977) predict a different defect structure for He^+ and the alkali earth ions: the helium ion is assumed to form a snowball like structure whereas for the alkali earth ions a bubble structure is assumed. If the temperature dependence is a characteristic feature for the different structures, then it seems likely that the Be^+ ion builds a snowball like structure.

Interaction of implanted deuterium and helium with beryllium: radiation enhanced oxidation

International Nuclear Information System (INIS)

Langley, R.A.

1979-01-01

The interaction of implanted deuterium and helium with beryllium is of significant interest in the application of first wall coatings and other components of fusion reactors. Electropolished polycrystalline beryllium was first implanted with an Xe backscatter marker at 1.98 MeV followed by either implantation with 5 keV diatomic deuterium or helium. A 2.0 MeV He beam was used to analyze for impurity buildup; namely oxygen. The oxide layer thickness was found to increase linearly with increasing implant fluence. A 2.5 MeV H + beam was used to depth profile the D and He by ion backscattering. In addition the retention of the implant was measured as a function of the implant fluence. The mean depth of the implant was found to agree with theoretical range calculations. Scanning electron microscopy was used to observe blister formation. No blisters were observed for implanted D but for implanted He blisters occurred at approx. 1.75 x 10 17 He cm -2 . The blister diameter increased with increasing implant fluence from about 0.8 μm at 10 18 He cm -2 to 5.5 μm at 3 x 10 18 He cm -2

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

Science.gov (United States)

Jung, Han Sae; Tsai, Hsin-Zon; Wong, Dillon; Germany, Chad; Kahn, Salman; Kim, Youngkyou; Aikawa, Andrew S.; Desai, Dhruv K.; Rodgers, Griffin F.; Bradley, Aaron J.; Velasco, Jairo; Watanabe, Kenji; Taniguchi, Takashi; Wang, Feng; Zettl, Alex; Crommie, Michael F.

2015-01-01

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene’s charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene's electronic structure in the presence of a charged impurity. The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene’s electronic properties.1-8 Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge2 and/or molecular5 states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies.2-5 These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices. PMID:26273961

Impurity Control Test Facility (ICTF) for the study of fusion reactor plasma/edge materials interactions

International Nuclear Information System (INIS)

Brooks, J.N.; Mattas, R.F.; Ehst, D.A.; Boley, C.D.; Hershkowitz, N.

1984-05-01

A test facility for investigating many of the impurity control issues associated with the interactions of materials with the plasma edge is outlined. Analysis indicates that the plasma edge conditions expected in TFCX, INTOR, etc. can be readily produced at the end cells of an rf stabilized mirror, similar in some respects to the Phaedrus device at the University of Wisconsin. A steady-state, Impurity Control Test Facility (ICTF) based on such a mirror device is expected to produce a plasma with typical parameters of n/sub e/ approx. 3 x 10 18 m -3 , T/sub e/ = 50 eV, and T/sub i/ = 100 eV at each end cell. A heat load of approx. 2 MW/m 2 over areas of approx. 1600 cm 2 could be produced at each end with 800 kW of ICRH power. These conditions would provide a unique capability for examining issues such as erosion/redeposition behavior, properties of redeposited materials, high recycling regimes, plasma edge operating limits for high-Z materials, and particle pumping efficiencies for limiter and divertor designs

Proton-conducting beta"-alumina via microwave-assisted synthesis and mechanism of enhanced corrosion prevention of a zinc rich coating with electronic control

Science.gov (United States)

Kirby, Brent William

Proton Conducting beta-alumina via Microwave Assisted Synthesis. The microwave assisted synthesis of proton conducting Mg- and Li-stabilized NH4+/H3O+ beta-alumina from a solution based gel precursor is reported. beta-alumina is a ceramic fast ion conductor containing two-dimensional sheets of mobile cations. Na +-beta-alumina is the most stable at the sintering temperatures (1740°C) reached in a modified microwave oven, and can be ion exchanged to the K+ form and then to the NH4+/H 3O+ form. beta-phase impurity is found to be 20% for Mg-stabilized material and 30-40% for Li-stabilized material. The composition of the proton conducting form produced here is deficient in NH4 + as compared to the target composition (NH4)1.00 (H3O)0.67Mg0.67Al10.33O 17. Average grain conductivity for Li-stabilized material at 150°C is 6.6x10-3 +/- 1.6x10-3 S/cm with 0.29 +/- 0.05 eV activation energy, in agreement with single crystal studies in the literature. Grain boundary conductivity is found to be higher in the Li-stabilized material. A hydrogen bond energy hypothesis is presented to explain these differences. Li-stabilized NH4+/H3O + beta-alumina is demonstrated as a fuel cell electrolyte, producing 28 muA/cm2 of electrical current at 0.5 V. Mechanism of Enhanced Corrosion Prevention of a Zinc Rich Coating with Electronic Control. A corrosion inhibition system consisting of high weight-loading zinc rich coating applied to steel panels is examined. An electronic control unit (ECU) consisting of a battery and a large capacitor in series with the panel is shown to improve corrosion protection upon immersion in 3% NaCl solution. Weekly solution changes to avoid zinc saturation in solution system were necessary to see well differentiated results. The corrosion product, hydrozincite [Zn5(CO3) 2(OH)6] is observed to deposit within the pores of the coating and on the surface as a barrier layer. Simonkolleite [Zn5(OH) 8Cl2·H2O] is found to form in place of the original zinc particles

The influence of phosphorus on the corrosion of iron in calcium nitrate

International Nuclear Information System (INIS)

Windisch, C.F. Jr.; Baer, D.R.; Jones, R.H.; Engelhard, M.H.

1992-01-01

This paper reports that intergranular stress corrosion cracking (IGSCC) of metallic alloys including iron is strongly influenced by the presence of grain boundary impurities such as phosphorus. In this study to determine how phosphorus affects the corrosion of ion, electrochemical polarization methods were used in conjunction with surface analyses employing ultrahigh vacuum transfer. Specifically, these methods were used to examine the corrosion of iron, iron/phosphorus alloys, and iron implanted with phosphorus in deaerated 55 weight percent Ca(NO 3 ) 2 solutions at 60 degrees C. The presence of phosphorus in iron accelerated corrosion in both the active and passive regions, with the effect being more pronounced in the passive region. In the active region, the phosphorus was oxidized to phosphate which, in turn, appeared to assist the dissolution of the semiprotective Fe 3 O 4 . In the passive region, the phosphorus (when unoxidized) accelerated corrosion by some other mechanism. The FePO 4 that formed in the passive region did not inhibit passivation by, rather, was incorporated in the passive film. The chemical transformations would appear to explain, at least partly, the high IGSCC rates observed for ion containing phosphorus segregated at grain boundaries