Localized corrosion and stress corrosion cracking of candidate materials for high-level radioactive waste disposal containers in U.S

International Nuclear Information System (INIS)

Farmer, J.C.; McCright, R.D.

1989-01-01

Three ion-based to nickel-based austenitic alloys and three copper-based alloys are being considered in the United States as candidate materials for the fabrication of high-level radioactive waste containers. The austenitic alloys are Types 304L and 316L stainless steels as well as the high-nickel material Alloy 825. The copper-based alloys are CDA 102 (oxygen-free copper) CDA 613 (Cu7Al), and CDA 715 (Cu-30Ni). Waste in the forms of spent fuel assemblies from reactors and borosilicate glass will be sent to a proposed repository at Yucca Mountain, Nevada. The decay of radionuclides will result in the generation of substantial heat and in gamma radiation. Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to a lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys

Open site tests on corrosion of carbon steel containers for radioactive waste forms

International Nuclear Information System (INIS)

Barinov, A.S.; Ojovan, M.I.; Ojovan, N.V.; Startceva, I.V.; Chujkova, G.N.

1999-01-01

Testing of waste containers under open field conditions is a component part of the research program that is being carried out at SIA Radon for more than 20 years to understand the long-term behavior of radioactive waste forms and waste packages. This paper presents the preliminary results of these ongoing studies. The authors used a typical NPP operational waste, containing 137 Cs, 134 Cs, and 60 Co as the dominant radioactive constituents. Bituminized and vitrified waste samples with 30--50 wt.% waste loading were prepared. Combined effects of climatic factors on corrosion behavior of carbon steel containers were estimated using gravimetric and chemical analyses. The observations suggest that uniform corrosion of containers prevails under open field conditions. The upper limits for the lifetime of containers were derived from calculations based on the model of atmospheric steel corrosion. Estimated lifetime values range from 300 to 600 years for carbon steel containers with the wall thickness of 2 mm containing vitrified waste, and from 450 to 500 years for containers with the wall thickness of 2.5 mm that were used for bituminized waste. However, following the most conservative method, pitting corrosion may cause container integrity failure after 60 to 90 years of exposure

Container material for the disposal of highly radioactive wastes: corrosion chemistry aspects

International Nuclear Information System (INIS)

Grauer, R.

1984-08-01

Prior to disposal in crystalline formations it is planned to enclose vitrified highly radioactive waste from nuclear power plants in metallic containers ensuring their isolation from the groundwater for at least 1,000 years. Appropriate metals can be either thermodynamically stable in the repository environment (such as copper), passive materials with very low corrosion rates (titanium, nickel alloys), or metals such as cast iron or unalloyed cast steels which, although they corrode, can be used in sections thick enough to allow for this corrosion. The first part of the report presents the essentials of corrosion science in order to enable even a non-specialist to follow the considerations and arguments necessary to choose the material and design the container against corrosion. Following this, the principles of the long-term extrapolation of corrosion behaviour are discussed. The second part summarizes and comments upon the literature search carried out to identify published results relevant to corrosion in a repository environment. Results of archeaological studies are included wherever possible. Not only the general corrosion behaviour but also localized corrosion and stress corrosion cracking are considered, and the influence of hydrogen on the material behaviour is discussed. Taking the corrosion behaviour as criterion, the author suggests the use either of copper or of cast iron or steel as an appropriate container material. The report concludes with proposals for further studies. (Auth.)

Radioactive corrosion products in circuit of fast reactor loop with dissociating coolant

International Nuclear Information System (INIS)

Dolgov, V.M.; Katanaev, A.O.

1982-01-01

The results of experimental investigation into depositions of radionuclides of corrosion origin on the surfaces of a reactor-in-pile loop facility with a dissociating coolant are presented. It is stated that the ratio of radionuclides in fixed depositions linearly decreases with decrease of the coolant temperature at the core-condenser section. The element composition of non-fixed compositions quantitatively and qualitatively differs from the composition of structural material, and it is more vividly displayed for the core-condenser section. The main mechanism of circuit contamination with radioactive corrosion products is substantiated: material corrosion in the zones of coolant phase transfer, their remove by the coolant in the core, deposition, activation and wash-out by the coolant from the core surfaces

Coupling between corrosion and biphasic transport in porous media: Application to the evolution of a radioactive wastes disposal

International Nuclear Information System (INIS)

Dridi, W.

2005-04-01

In the actual concepts of geological disposal, high level radioactive wastes are packed in metallic containers surrounded by a partially or totally saturated clay media. In contact with the interstitial water, anoxic corrosion of this container will start producing hydrogen. In the scope of safety assessment, the present study deals with two main topics: prediction of the long-term corrosion of carbon steel with respect to clay water content and evaluation of the risk of damage of the clay barrier related to gas production. Elementary processes controlling the kinetics of corrosion are limited to oxide growth and mass transfer through the porosity of this film. Thanks to a macroscopic description of theses processes, followed by an interfacial kinetic law, a mechanistic modeling of the anoxic corrosion in partially saturated porous media is proposed. This approach is validated when confronted to the long-term corrosion tests performed in saturated clay. Both modeling and laboratory experiments have confirmed that kinetics of anoxic corrosion in partially saturated clay is mainly controlled by the surrounding relative humidity as in the case of aerated or atmospheric corrosion. In the gas generation topic, some numerical simulations are performed concerning the oedometric and triaxial test dealing with gas migration in saturated clay. Finally, long-term calculations are conducted concerning hydro-mechanical impact of corrosion in deep geological repositories. Due to a more realistic prediction of the long-term corrosion, the risks of gas overpressures, local desaturation and mechanical damage are reduced. (author)

5l/h pump for dosing corrosion radioactive liquids

International Nuclear Information System (INIS)

Przybylovich, S.; Shraer, V.; Chermak, R.

1977-01-01

The technical requirements, design and main technical characteristics of the pump for dosing corrosion and radioactive liquids with capacity up to 5 l/h are described. The design is based on the popular sixvertical split casing pump. The pump has four separate pump membrane type blocks with nonstraight hydraulic membrane control. The membranes are made of the cold worked CrNi(18/10)type stainless steel with thickness up to 0.1 mm and have the lifetime up to 3000 hours. The remote pump heads are used for pumping radioactive fluids when the pumping goes behind the safe wall, separating the pump from a hot lab. The tests showed that the pump secures the satisfactory accuracy of dozing and uniformity of pumping and that it is really possible to achieve the required life time of 10000 hours by this pump

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

International Nuclear Information System (INIS)

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

1991-07-01

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

Effect of radioactive chromate on the corrosion and polarisation of mild steel in sodium chloride solution

International Nuclear Information System (INIS)

Subramanyan, N.; Ramakrishnaiah, K.; Iyer, S.V.; Kapali, V.

1980-01-01

Corrosion tests of mild steel in 0.01% sodium chloride containing radioactive chromate and non-radioactive chromate have been carried out. It has been observed that the labelled sodium chromate has a deleterious effect on the inhibitive action of non-radioactive chromate. The effect of radioactive chromate on the potentiostatic polarization of m.s. in sodium chloride solution containing non-radioactive sodium chromate has also been studied. It is observed that both the cathodic and the anodic polarisation of the metal is diminished in the presence of radioactive chromate. The behaviour of the system in the presence of radioactive chromate is attributed both to the action of depolarisers produced by radiolysis of water and to the effect of gamma radiation on the metal. (author)

Mechanisms of leaching and corrosions of vitrified radioactive waste forms

International Nuclear Information System (INIS)

Lanza, F.; Conradt, R.; Hall, A.R.; Malow, G.; Trocellier, P.; Van Iseghem, P.

1985-01-01

The estimation of the risk connected with the storage of radioactive waste in geological formations asks for reliable extrapolation of the data for leaching and corrosion of glasses to very long times. As a consequence the knowledge of the physico-chemical mechanisms which dominate the leaching phenomena can be very useful. In the corrosion due to aqueous solution three main mechanisms can be identified: ion exchange, matrix dissolution and formation of a surface layer. The work performed in the different laboratories has allowed to evaluate the relative importance of the various mechanism. The alkali ion exchange does not seems to be predominant in defining the release of the various elements, the matrix dissolution being the most important. The surface composition is important as the compounds present could dominate the matrix dissolution kinetic. Besides the surface layer could form an impervious layer, which, if stable in time, could protect effectively the glass

Corrosion in the off-gas system of a radioactive-waste incinerator

International Nuclear Information System (INIS)

Jenkins, C.F.; Peters, J.J.

1987-01-01

Corrosion in a low-level radioactive-waste incinerator off-gas system at the Department of Energy's Savannah River Plant is discussed. Severe corrosive attack and failure of an alloy 600 part exposed to high-temperature (>1000 0 C) gases was observed. Rapid attack of carbon steel components, and cracking of austenitic stainless steel parts also occurred at locations where lower gas temperatures and periodic condensate exposure occurred. Investigation showed HCl, SO 2 , SO 3 and phosphorus-oxides were present and contributed to the failures. Mechanisms of high-temperature failure include alloy separation and reactions with phosphorus. Coupons placed in the exhaust stream have provided information for selection of future materials of construction for system components. Several nickel- and iron-base alloys, and a stainless steel with an aluminum-diffusion coating were investigated

Corrosion of high-level radioactive waste iron-canisters in contact with bentonite

Energy Technology Data Exchange (ETDEWEB)

Kaufhold, Stephan, E-mail: s.kaufhold@bgr.de [BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover (Germany); Hassel, Achim Walter [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, D-40237 Düsseldorf (Germany); Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Sanders, Daniel [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, D-40237 Düsseldorf (Germany); Dohrmann, Reiner [BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover (Germany); LBEG, Landesamt für Bergbau, Energie und Geologie, Stilleweg 2, D-30655 Hannover (Germany)

2015-03-21

Graphical abstract: Corrosion at the bentonite iron interface proceeds unaerobically with formation of an 1:1 Fe silicate mineral. A series of exposure tests with different types of bentonites showed that Na–bentonites are slightly less corrosive than Ca–bentonites and highly charges smectites are less corrosive compared to low charged ones. The formation of a patina was observed in some cases and has to be investigated further. - Highlights: • At the iron bentonite interface a 1:1 Fe layer silicate forms upon corrosion. • A series of iron–bentonite corrosion products showed slightly less corrosion for Na-rich and high-charged bentonites. • In some tests the formation of a patina was observed consisting of Fe–silicate, which has to be investigated further. - Abstract: Several countries favor the encapsulation of high-level radioactive waste (HLRW) in iron or steel canisters surrounded by highly compacted bentonite. In the present study the corrosion of iron in contact with different bentonites was investigated. The corrosion product was a 1:1 Fe layer silicate already described in literature (sometimes referred to as berthierine). Seven exposition test series (60 °C, 5 months) showed slightly less corrosion for the Na–bentonites compared to the Ca–bentonites. Two independent exposition tests with iron pellets and 38 different bentonites clearly proved the role of the layer charge density of the swelling clay minerals (smectites). Bentonites with high charged smectites are less corrosive than bentonites dominated by low charged ones. The type of counterion is additionally important because it determines the density of the gel and hence the solid/liquid ratio at the contact to the canister. The present study proves that the integrity of the multibarrier-system is seriously affected by the choice of the bentonite buffer encasing the metal canisters in most of the concepts. In some tests the formation of a patina was observed consisting of Fe�

Corrosion behaviour of container materials for geological disposal of high level radioactive waste

International Nuclear Information System (INIS)

Accary, A.

1985-01-01

The disposal of high level radioactive waste in geological formations, based on the multibarrier concept, may include the use of a container as one of the engineered barriers. In this report the requirements imposed on this container and the possible degradation processes are reviewed. Further on an overview is given of the research being carried out by various research centres in the European Community on the assessment of the corrosion behaviour of candidate container materials. The results obtained on a number of materials under various testing conditions are summarized and evaluated. As a result, three promising materials have been selected for a detailed joint testing programme. It concerns two highly corrosion resistant alloys, resp. Ti-Pd (0.2 Pd%) and Hastelloy C4 and one consumable material namely a low carbon steel. Finally the possibilities of modelling the corrosion phenomena are discussed

Corrosion on reinforced concrete structures. An application for the intermediate level radioactive waste container

International Nuclear Information System (INIS)

Arva, Alejandro; Alvarez, Marta G.; Duffo, Gustavo S.

2003-01-01

The behavior of steel reinforcement bars (rebars) for a high performance reinforced concrete made of sulfate resistant portland cement was evaluated from the rebars corrosion point of view. The results from the present work will be used to evaluate the materials properties to be used in the construction of the intermediate level radioactive waste disposal containers. The study is carried out evaluating the incidence of chloride and sulfate ions, as well as, concrete carbonation in the rebar corrosion process. The electrochemical parameters that characterize the corrosion process (corrosion potential [E corr ], polarisation resistance [Rp] and concrete electrical resistivity [ρ]) were monitored on specially designed reinforced concrete specimens. The results up to date (about 1000 days of exposure) reveal that the concrete under study provides to the steel reinforcement bars of a passive state against corrosion under the test conditions. An increasing tendency as a function of time of ρ is observed that corroborates the continuous curing process of concrete. The chloride and carbonation diffusion coefficients were also determined, and their values are comparable with those of high quality concrete. (author)

Corrosion of high-level radioactive waste iron-canisters in contact with bentonite.

Science.gov (United States)

Kaufhold, Stephan; Hassel, Achim Walter; Sanders, Daniel; Dohrmann, Reiner

2015-03-21

Several countries favor the encapsulation of high-level radioactive waste (HLRW) in iron or steel canisters surrounded by highly compacted bentonite. In the present study the corrosion of iron in contact with different bentonites was investigated. The corrosion product was a 1:1 Fe layer silicate already described in literature (sometimes referred to as berthierine). Seven exposition test series (60 °C, 5 months) showed slightly less corrosion for the Na-bentonites compared to the Ca-bentonites. Two independent exposition tests with iron pellets and 38 different bentonites clearly proved the role of the layer charge density of the swelling clay minerals (smectites). Bentonites with high charged smectites are less corrosive than bentonites dominated by low charged ones. The type of counterion is additionally important because it determines the density of the gel and hence the solid/liquid ratio at the contact to the canister. The present study proves that the integrity of the multibarrier-system is seriously affected by the choice of the bentonite buffer encasing the metal canisters in most of the concepts. In some tests the formation of a patina was observed consisting of Fe-silicate. Up to now it is not clear why and how the patina formed. It, however, may be relevant as a corrosion inhibitor. Copyright © 2014 Elsevier B.V. All rights reserved.

The study on the magnetic filter using the rotation of permanent magnets for separation of radioactive corrosion products

International Nuclear Information System (INIS)

Song, M.C.; Lee, K.J.

2004-01-01

Most of the insoluble radioactive corrosion products have the characteristic of showing strong ferrimagnetism. Along with the new development and production of permanent magnets which generate much stronger magnetic field than conventional permanent magnets, new type of magnetic filter that can separate radioactive corrosion products efficiently and eventually reduce the radiation exposure of the personnel at a nuclear power plant is suggested. This new type of separator with novel geometry consists of an inner and an outer magnet assembly, a coolant channel and a container surrounding the outer magnet assembly. The particulates are separated from the coolant by the alternating magnetic fields that are generated by shift arrangement of permanent magnets. This study describes of experimental results performed with the different flow rates, rotation velocities of magnet assemblies, particle size and various materials. The efficiency of magnetic filter tends to increase as the flow rate is lower, and particle size is bigger. The rotating velocity of magnet assembly has also some influences on the separation efficiency. This new magnetic filter shows good performance results in filtering magnetite, cobalt ferrite and nickel ferrite except hematite, which is a kind of anti-ferromagnetic material, from aqueous coolant simulation. At the above 5 μm of particle size, the separation efficiencies are over than 90%. (author)

Method of reducing the radioactivity in nuclear power plants

International Nuclear Information System (INIS)

Ohashi, Kenya; Honda, Takashi; Furutani, Yasumasa; Kashimura, Eiji; Minato, Akira; Osumi, Katsumi.

1986-01-01

Purpose: To reduce the radioactivity in nuclear power plants in contact with pure water at high temperature and high pressure. Method: For suppressing the deposition of radioactive materials in nuclear reactor coolants to the structural materials, oxide layers which are relatively porous but have a sufficient layer thickness are formed as the primary treatment and then thin but dense layers are formed as the secondary treatment. Oxidization is applied by means of heated water or steams with less oxidizing property in the first treatment, while oxidizing treatment is applied with heated water and steams at high oxidizing property in the second treatment, because the effect of suppressing corrosion is insufficient only by means of the membranes in the primary treatment, while the layers formed by the secondary treatment alone are liable to be injured and degraded. Since coolants for use in BWR type reactors usually contain about 200 ppb of dissolved oxygen, it is desirably from 40 to 100 ppb for the primary treatment and from 400 ppb to 8 ppb for the secondary treatment, and non-oxidating heated gases at high purity such as Ar, N 2 , He may be used in addition to heated water and steams. (Kawakami, Y.)

Integrated Corrosion Facility for long-term testing of candidate materials for high-level radioactive waste containment

International Nuclear Information System (INIS)

Estill, J.C.; Dalder, E.N.C.; Gdowski, G.E.; McCright, R.D.

1994-10-01

A long-term-testing facility, the Integrated Corrosion Facility (I.C.F.), is being developed to investigate the corrosion behavior of candidate construction materials for high-level-radioactive waste packages for the potential repository at Yucca Mountain, Nevada. Corrosion phenomena will be characterized in environments considered possible under various scenarios of water contact with the waste packages. The testing of the materials will be conducted both in the liquid and high humidity vapor phases at 60 and 90 degrees C. Three classes of materials with different degrees of corrosion resistance will be investigated in order to encompass the various design configurations of waste packages. The facility is expected to be in operation for a minimum of five years, and operation could be extended to longer times if warranted. A sufficient number of specimens will be emplaced in the test environments so that some can be removed and characterized periodically. The corrosion phenomena to be characterized are general, localized, galvanic, and stress corrosion cracking. The long-term data obtained from this study will be used in corrosion mechanism modeling, performance assessment, and waste package design. Three classes of materials are under consideration. The corrosion resistant materials are high-nickel alloys and titanium alloys; the corrosion allowance materials are low-alloy and carbon steels; and the intermediate corrosion resistant materials are copper-nickel alloys

Inhibition of Bio corrosion of steel coupon by sulphate reducing ...

African Journals Online (AJOL)

ADOWIE PERE

Inhibition of Bio corrosion of steel coupon by sulphate reducing bacteria and Iron oxidizing bacteria using .... Ethanol for 24 h. The extract was ... with distilled water to get a zero reading from the meter before .... Ethanol extract of musa species peels as a green corrosion ... Eco friendly extract of banana peel as corrosion ...

Bacterial corrosion in low-temperature geothermal. Mechanisms of corrosion by sulphate-reducing bacteria

International Nuclear Information System (INIS)

Daumas, Sylvie

1987-01-01

Within the frame of researches aimed at determining the causes of damages noticed on geothermal equipment, this research thesis aims at assessing the respective importance of physical-chemical processes and bacterial intervention in corrosion phenomena. It proposes an ecological approach of the fluid sampled in the Creil geothermal power station. The aim is to define the adaptation and activity degree of isolated sulphate-reducing bacteria with respect to their environment conditions. The author studied the effect of the development of these bacteria on the corrosion of carbon steel used in geothermal. Thus, he proposes a contribution to the understanding of mechanisms related to iron attack by these bacteria. Electrochemical techniques have been adapted to biological processes and used to measure corrosion [fr

Method of inhibiting concentration of radioactive corrosion products in cooling water or nuclear power plants

International Nuclear Information System (INIS)

Takabayashi, Jun-ichi; Hishida, Mamoru; Ishikura, Takeshi.

1979-01-01

Purpose: To suppress the increase in the concentration of the radioactive corrosion products in cooling water, which increase is accompanied by the transference of the corrosion products activated and accumulated in the core due to dissolution and exfoliation into the core water, and inhibit the flowing of said products out of the core and the diffusion thereof into the cooling system, thereby to prevent the accumulation of said products in the cooling system and prevent radioactive contaminations. Method: In a nuclear power plant of a BWR type light water reactor, when the temperature of the pile water is t 0 C, hydrogen is injected in cooling water in a period of time from immediately before starting of the drive stopping operation of the nuclear power plant to immediately after the termination of restarting operation, whereby the concentration of hydrogen in the reactor water through said period is maintained at a value more than 2exp (0.013 t) cm 3 N.T.P./kg H 2 O. (Aizawa, K.)

Reinforcement corrosion in alkaline chloride media with reduced oxygen concentrations

International Nuclear Information System (INIS)

Andrade, C.; Fullea, J.; Toro, L.; Martinez, I.; Rebolledo, N.

2013-01-01

It is commonly considered that the corrosion of steel in concrete is controlled by the oxygen content of the pore solution and there are service life models that relate the corrosion rate to the amount of oxygen. It is also commonly believed that in water saturated conditions the oxygen content in the pores is negligible and that underwater there is no risk of depassivation and the corrosion rate is very low. However, the available data on corrosion rates in immersed conditions do not indicate such performance; on the contrary corrosion develops when sufficient chloride reaches the reinforcement. In the present paper, results are presented for tests performed in alkaline chloride solutions that were purged with nitrogen to reduce the oxygen content. The results indicate that at very low oxygen concentrations, corrosion may develop in the presence of chlorides. The presence or absence of corrosion is influenced by the amount of chloride, the corrosion potential and the steel surface condition. (authors)

Sulphur recirculation for reduced boiler corrosion; Minskad pannkorrosion med svavelrecirkulation

Energy Technology Data Exchange (ETDEWEB)

Andersson, Sven; Karlsson, Martin (Goetaverken Miljoe AB, Goeteborg (Sweden)); Blomqvist, Evalena; Baefver, Linda; Claesson, Frida; Davidsson, Kent (SP Sveriges Tekniska Forskningsinstitut, Boraas (Sweden)); Froitzheim, Jan; Pettersson, Jesper; Steenari, Britt-Marie (Chalmers Tekniska Hoegskola, Oorganisk miljoekemi, Goeteborg (Sweden))

2010-03-15

Sulphur recirculation is a new technology for reducing boiler corrosion and dioxin formation, which was demonstrated in full-scale tests performed at the Renova Waste to Energy plant at Saevenaes in Goeteborg (Sweden). Sulphur is recirculated from the flue gas cleaning back to the boiler, which reduces the chloride content of the deposits, which in turn reduces boiler corrosion and dioxin formation. Sulphur dioxide was separated from the flue gas in a wet scrubber by adding hydrogen peroxide, producing sulphuric acid. The sulphuric acid was injected into the furnace using nozzles with atomization air, surrounded by recirculated flue gas for improved mixing. By recirculating the sulphur, the sulphur dioxide concentration was increased in the boiler. Each sulphur atom passed the boiler several times and no external sulphur had to be added. Dioxin, ash, deposits and particle samplings together with 1000 h corrosion probe measurements were performed for normal operation (reference) and with sulphur recirculation respectively. During spring 2009, reference measurements were made and the recirculation system was installed and tested. During autumn 2009, a long term test with sulphur recirculation was made. An SO{sub 2} concentration of approximately 800 mg/m3 (n, d.g.) was maintained in the boiler by the system except during a period of extremely low sulphur content in the waste. The sulphur dioxide stack concentrations have been far below the emission limit. Sulphuric acid dew point measurements have shown that the sulphuric acid dosage did not lead to elevated SO{sub 3} concentrations, which may otherwise lead to low temperature corrosion. The chlorine content of both fly ash and boiler ash decreased and the sulphur content increased during the sulphur recirculation tests. The molar chlorine/sulphur ratio (Cl/S) decreased by two thirds in the fly ash as well as in the boiler ash, except for one sample. With sulphur recirculation in operation, the deposit growth was

Improved management of SG BD demineralizer for reduced generation of low-level radioactive spent resin in Korean nuclear power plants

International Nuclear Information System (INIS)

Rhee, I.; Cho, D.; Yeon, J.

2003-01-01

Most nuclear power plants in Korea have adopted Ethanolamine(ETA) as a secondary pH control agent to increase the pH at the liquid phase, which may reduce the corrosion in steam generator tubes and moisture separator/reheat system. Along with its beneficial effect of SG protection from corrosion and degradation, the replacement of ammonia with ETA causes the increased generation of spent resin and the reduced run time of demineralizer in steam generator blowdown(SG BD) system. The composition ratio of cation- to anion- exchange resin in SG BD mixed bed should be increased in the ETA chemistry environment to meet the ratio of cation to anion in the aqueous solution, which results in the simultaneous exhaustion of cation and anion exchange resins. The utilization rate of mixed bed is greatest at the cation-to-anion ratio of 95:1 on the theoretical equivalent basis in the solution, but practically highest at that of 22:1 due to the possible inhomogeneous distribution of cation and anion exchange resins in SG BD bed. The run time of the bed could be extended by 30% such that, at that much, the purchase cost of new resin is saved and the production rate of spent resin is reduced. The guideline on the replacement of resin in SG BD bed is not necessary to secure the removal of radioactive particles without the leakage of the primary coolant into the secondary side since all the radioactive ions can be eliminated by SG BD bed with the sufficient time. They are retained during more than one month after their ingress into the SG BD bed without leakage. With the reduced replacement, thus, the SG BD spent resin that comprises 65% of low-level radioactive solid waste can be much cut down

Simulation of radioactive corrosion product in primary cooling system of Japanese sodium-cooled fast breeder reactor

International Nuclear Information System (INIS)

Matuo, Youichirou; Miyahara, Shinya; Izumi, Yoshinobu

2012-01-01

Radioactive Corrosion Product (CP) is a main cause of personal radiation exposure during maintenance with no breached fuel in fast breeder reactor (FBR) plants. The most important CP is 54 Mn and 60 Co. In order to establish techniques of radiation dose estimation for radiation workers in radiation-controlled areas of the FBR, the PSYCHE (Program SYstem for Corrosion Hazard Evaluation) code was developed. We add the Particle Model to the conventional PSYCHE analytical model. In this paper, we performed calculation of CP transfer in JOYO using an improved calculation code in which the Particle Model was added to the PSYCHE. The C/E (calculated / experimentally observed) value for CP deposition was improved through use of this improved PSYCHE incorporating the Particle Model. Moreover, among the percentage of total radioactive deposition accounted for by CP in particle form, 54 Mn was estimated to constitute approximately 20% and 60 Co approximately 40% in the cold-leg region. These calculation results are consistent with the measured results for the actual cold-leg piping in the JOYO. (author)

Coupling between corrosion and biphasic transport in porous media: Application to the evolution of a radioactive wastes disposal; Couplage entre corrosion et comportement diphasique dans un milieu poreux: Application a l'evolution d'un stockage des dechets radioactifs

Energy Technology Data Exchange (ETDEWEB)

Dridi, W

2005-04-15

In the actual concepts of geological disposal, high level radioactive wastes are packed in metallic containers surrounded by a partially or totally saturated clay media. In contact with the interstitial water, anoxic corrosion of this container will start producing hydrogen. In the scope of safety assessment, the present study deals with two main topics: prediction of the long-term corrosion of carbon steel with respect to clay water content and evaluation of the risk of damage of the clay barrier related to gas production. Elementary processes controlling the kinetics of corrosion are limited to oxide growth and mass transfer through the porosity of this film. Thanks to a macroscopic description of theses processes, followed by an interfacial kinetic law, a mechanistic modeling of the anoxic corrosion in partially saturated porous media is proposed. This approach is validated when confronted to the long-term corrosion tests performed in saturated clay. Both modeling and laboratory experiments have confirmed that kinetics of anoxic corrosion in partially saturated clay is mainly controlled by the surrounding relative humidity as in the case of aerated or atmospheric corrosion. In the gas generation topic, some numerical simulations are performed concerning the oedometric and triaxial test dealing with gas migration in saturated clay. Finally, long-term calculations are conducted concerning hydro-mechanical impact of corrosion in deep geological repositories. Due to a more realistic prediction of the long-term corrosion, the risks of gas overpressures, local desaturation and mechanical damage are reduced. (author)

Reducing the risk from radioactive sources

International Nuclear Information System (INIS)

MacKenzie, C.

2006-01-01

Each year the IAEA receives reports of serious injuries or deaths due to misuse or accidents involving sealed radioactive sources. Sealed radioactive sources are used widely in medicine, industry, and agriculture - by doctors to treat cancer, by radiographers to check welds in pipelines, or by specialists to irradiate food to prevent it from spoiling, for example. If these sources are lost or improperly discarded, a serious accident may result. In addition, the security of sealed sources has become a growing concern, particularly the potential that such a source could be used as a radioactive dispersal device or 'dirty bomb'. Preventing the loss or theft of sealed radioactive sources reduces both the risk of accidents and the risk that such sources could become an instrument of misuse. In most countries, radioactive materials and activities that produce radiation are regulated. Those working with sealed radioactive sources are required not just to have proper credentials, but also the needed training and support to deal with unexpected circumstances that may arise when a source is used. Despite these measures, accidents involving sealed sources continue to be reported to the IAEA. Among its many activities to improve the safety and security of sealed sources, the IAEA has been investigating the root causes of major accidents since the 1980s and publishing the findings so that others can learn from them. This information needs to be in the hands of those whose actions and decisions can reduce accidents by preventing a lost source from making it's way into scrap metal. The IAEA has also developed an international catalogue of sealed radioactive sources, and provides assistance to countries to safely contain sources no longer in use. To raise awareness, a Sealed Radioactive Sources Toolkit was issued that focuses on the long-term issues in safely and securely managing radioactive sealed sources. The target audiences are government agencies, radioactive sealed source

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)

Inhibiting pitting corrosion in carbon steel exposed to dilute radioactive waste slurries

International Nuclear Information System (INIS)

Zapp, P.E.; Hobbs, D.T.

1991-01-01

Dilute caustic high-level radioactive waste slurries can induce pitting corrosion in carbon steel. Cyclic potentiodynamic polarization tests were conducted in simulated and actual waste solutions to determine minimum concentrations of sodium nitrate which inhibit pitting in ASTM A537 class 1 steel exposed to these solutions. Susceptibility to pitting was assessed through microscopic inspection of specimens and inspection of polarization scans. Long-term coupon immersion tests were conducted to verify the nitrite concentrations established by the cyclic potentiodynamic polarization tests. The minimum effective nitrite concentration is expressed as a function of the waste nitrate concentration and temperature

Archaeological analogs and corrosion; Analogues archeologiques et corrosion

Energy Technology Data Exchange (ETDEWEB)

David, D

2008-07-01

In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

Sulfate-reducing bacteria inhabiting natural corrosion depostis from marine steel structures

NARCIS (Netherlands)

Païssé, S.; Ghiglione, J.-F.; Marty, F.; Abbas, B.; Gueuné, H.; Sanchez Amaya, J.; Muyzer, G.; Quillet, L.

2013-01-01

In the present study, investigations were conducted on natural corrosion deposits to better understand the role of sulfate-reducing bacteria (SRB) in the accelerated corrosion process of carbon steel sheet piles in port environments. We describe the abundance and diversity of total and metabolically

Evaluation of CRUDTRAN code to predict transport of corrosion products and radioactivity in the PWR primary coolant system

International Nuclear Information System (INIS)

Lee, C.B.

2002-01-01

CRUDTRAN code is to predict transport of the corrosion products and their radio-activated nuclides such as cobalt-58 and cobalt-60 in the PWR primary coolant system. In CRUDTRAN code the PWR primary circuit is divided into three principal sections such as the core, the coolant and the steam generator. The main driving force for corrosion product transport in the PWR primary coolant comes from coolant temperature change throughout the system and a subsequent change in corrosion product solubility. As the coolant temperature changes around the PWR primary circuit, saturation status of the corrosion products in the coolant also changes such that under-saturation in steam generator and super-saturation in the core. CRUDTRAN code was evaluated by comparison with the results of the in-reactor loop tests simulating the PWR primary coolant system and PWR plant data. It showed that CRUDTRAN could predict variations of cobalt-58 and cobalt-60 radioactivity with time, plant cycle and coolant chemistry in the PWR plant. (author)

The incineration of radioactive waste

International Nuclear Information System (INIS)

Thegerstroem, C.

1980-03-01

In this study, made on contract for the Swedish Nuclear Power Inspectorate, different methods for incineration of radioactive wastes are reviewed. Operation experiences and methods under development are also discussed. The aim of incineration of radioactive wastes is to reduce the volume and weight of the wastes. Waste categories most commonly treated by incineration are burnable solid low level wastes like trash wastes consisting of plastic, paper, protective clothing, isolating material etc. Primarily, techniques for the incineration of this type of waste are described but incineration of other types of low level wastes like oil or solvents and medium level wastes like ion-exchange resins is also briefly discussed. The report contains tables with condensed data on incineration plants in different countries. Problems encountered, experiences and new developments are reviewed. The most important problems in incineration of radioactive wastes have been plugging and corrosion of offgas systems, due to incomplete combustion of combustion of materials like rubber and PVC giving rise to corrosive gases, combined with inadequate materials of construction in heat-exchangers, channels and filter housings. (author)

Are underground clay disposal conditions favorable for microbial activity and bio-corrosion?

Energy Technology Data Exchange (ETDEWEB)

Libert, M.; Kerber-Schuetz, M.; Bildstein, O. [CEA, DEN/DTN/SMTM/LMTE, bat. 307, 13108 Saint Paul Lez Durance Cedex (France); Esnault, L. [ECOGEOSAFE, Technopole de l' Environnement Arbois- Mediterranee, BP 90027 Aix en Provence (France)

2013-07-01

The French concept for geological disposal of high-level radioactive waste is based on a multi-barrier system including metallic containers confined in a clay-stone layer. The main alteration vector is water coming from the host rock and triggering corrosion of metallic components. Despite extreme conditions, microorganisms can adapt and survive in these environments. Anoxic corrosion of metallic containers and water radiolysis produce H{sub 2}, which potentially represents an abundant energetic source for microbial development, especially in this type of environment containing low amounts of biodegradable organic matter. Moreover, formation of Fe(III)-bearing corrosion products such as magnetite (Fe{sub 3}O{sub 4}) can provide electron acceptors for microbial development. Therefore, bio-corrosion studies are needed in order to investigate the activity of hydrogenotrophic bacteria able to reduce sulphates or Fe(III) from iron oxides (passive layer). These studies help in evaluating such microbial impacts on the long-term stability of metallic components involved in radioactive waste disposal. (authors)

Development of experimental method to simulate the corrosion products in the primary system of nuclear power plant

International Nuclear Information System (INIS)

Kim, Sang Hyun; Kim, In Sup; Jang, Chang Heui

2005-01-01

Corrosion products are recognized as one of the major sources of occupational radiation exposure for nuclear power plant workers. Numerous studies have been conducted on the primary water chemistry to reduce the amount of crud in the primary circuit to avoid the radioactivity build-up in the plant. However, experiments with crud are restricted in laboratory because the crud is highly radioactive material. The objective of this study is to develop the simulating method of corrosion product in nuclear power plant

Evaluation of the corrosion of reinforced concrete designed for low and medium activity level radioactive waste containers

International Nuclear Information System (INIS)

Duffo, G.S.; Arva, E.A; Schulz, F.M; Vasquez, D.R

2010-01-01

The National Atomic Energy Commission of Argentina (CNEA) is responsible for the design and construction of a monolithic repository for the final disposal of low and medium level radioactive wastes. In order to ensure the protection of people and the environment, the useful life of the repository should be 300 years and the conceptual design selected is based on the use of multiple, independent and redundant barriers. These barriers consist mainly of reinforced concrete. This work aims to establish a methodology to determine the concrete's useful life, evaluating parameters of interest using chemical and electrochemical techniques. For this purpose, reinforced concrete test pieces were made with two formulations - blast furnace cement (BFC) and with BFC plus silica fume admixture (BFC+SF)- and in each of the test pieces segments of reinforcement were included. The development over time of the corrosion potential and speed were evaluated, together with the resistivity of the concrete in the test pieces exposed to the laboratory environment, with an average relative humidity of 50%, a condition that favors the carbonation process. The diffusion coefficients of aggressive species, such as chloride and carbon dioxide, were also determined in test pieces made with the two formulations. In the test pieces exposed to the laboratory environment the reinforcements embedded in the BFC+SF concrete showed a lower corrosion speed compared to the BFC concrete. These results agree with the lower values for the speeds of carbonation and of chloride diffusion that show that the concrete with BFC+SF is more resistant to incoming aggressive species compared with the BFC. A container prototype for mid-level radioactive wastes was built and outfitted with instruments in order to monitor the development over time of the corrosion speed of the reinforcement rods by using corrosion sensors developed by the group. The prototype, exposed to atmospheric conditions, was manufactured with BFC

Influence of Sulfate-Reducing Bacteria on the Corrosion Residual Strength of an AZ91D Magnesium Alloy

Science.gov (United States)

Zhu, Xianyong; Liu, Yaohui; Wang, Qiang; Liu, Jiaan

2014-01-01

In this paper, the corrosion residual strength of the AZ91D magnesium alloy in the presence of sulfate-reducing bacteria is studied. In the experiments, the chemical composition of corrosion film was analyzed by a scanning electron microscope with energy dispersive X-ray spectroscopy. In addition, a series of instruments, such as scanning electronic microscope, pH-meter and an AG-10TA materials test machine, were applied to test and record the morphology of the corrosion product, fracture texture and mechanical properties of the AZ91D magnesium alloy. The experiments show that the sulfate-reducing bacteria (SRB) play an important role in the corrosion process of the AZ91D magnesium alloy. Pitting corrosion was enhanced by sulfate-reducing bacteria. Corrosion pits are important defects that could lead to a significant stress concentration in the tensile process. As a result, sulfate-reducing bacteria influence the corrosion residual strength of the AZ91D magnesium alloy by accelerating pitting corrosion. PMID:28788236

Corrosion of Iron by Sulfate-Reducing Bacteria: New Views of an Old Problem

Science.gov (United States)

Garrelfs, Julia

2014-01-01

About a century ago, researchers first recognized a connection between the activity of environmental microorganisms and cases of anaerobic iron corrosion. Since then, such microbially influenced corrosion (MIC) has gained prominence and its technical and economic implications are now widely recognized. Under anoxic conditions (e.g., in oil and gas pipelines), sulfate-reducing bacteria (SRB) are commonly considered the main culprits of MIC. This perception largely stems from three recurrent observations. First, anoxic sulfate-rich environments (e.g., anoxic seawater) are particularly corrosive. Second, SRB and their characteristic corrosion product iron sulfide are ubiquitously associated with anaerobic corrosion damage, and third, no other physiological group produces comparably severe corrosion damage in laboratory-grown pure cultures. However, there remain many open questions as to the underlying mechanisms and their relative contributions to corrosion. On the one hand, SRB damage iron constructions indirectly through a corrosive chemical agent, hydrogen sulfide, formed by the organisms as a dissimilatory product from sulfate reduction with organic compounds or hydrogen (“chemical microbially influenced corrosion”; CMIC). On the other hand, certain SRB can also attack iron via withdrawal of electrons (“electrical microbially influenced corrosion”; EMIC), viz., directly by metabolic coupling. Corrosion of iron by SRB is typically associated with the formation of iron sulfides (FeS) which, paradoxically, may reduce corrosion in some cases while they increase it in others. This brief review traces the historical twists in the perception of SRB-induced corrosion, considering the presently most plausible explanations as well as possible early misconceptions in the understanding of severe corrosion in anoxic, sulfate-rich environments. PMID:24317078

Development of corrosion testing equipment under heat transfer and irradiation conditions to evaluate corrosion resistance of materials used in acid recovery evaporator. Contract research

International Nuclear Information System (INIS)

Motooka, Takafumi; Numata, Masami; Kiuchi, Kiyoshi

2002-01-01

We have been evaluated the safety for corrosion of various metals applied to acid recovery evaporators by the mock-up tests using small scaled equipment and the reference tests in laboratories with small specimens. These tests have been conducted under-radioactive environment. The environment in practical reprocessing plants has many radioactive species. Therefore, the effect of irradiation on corrosion should be evaluated in detail. In this study, we have developed the corrosion testing equipment, which is employed to simulate environments in the acid recovery evaporators. This report describes the specification of corrosion testing equipment and the results of primary, reference and hot tests. Using the equipment, the corrosion test under heat transfer and irradiation conditions have been carried out for 930 hours in safety. It is expectable that useful corrosion test data in radioactive environment are accumulated with this equipment in future, and help the adequate choice of corrosion test condition in laboratories. (author)

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Effect of zinc injection on BWR fuel cladding corrosion. Pt. 1. Study on an accelerated corrosion condition to evaluate corrosion resistance of zircaloy-2 fuel cladding

International Nuclear Information System (INIS)

Kawamura, Hirotaka; Kanbe, Hiromu; Furuya, Masahiro

2002-01-01

Japanese BWR utilities have a plan to apply zinc injection to the primary coolant in order to reduce radioactivity accumulation on the structure. Prior to applying the zinc injection to BWR plants, it is necessary to evaluate the effect of zinc injection on corrosion resistance of fuel cladding. The objective of this report was to examine the accelerated corrosion condition for evaluation of BWR fuel cladding corrosion resistance under non-irradiated conditions, as the first step of a zinc injection evaluation study. A heat transfer corrosion test facility, in which a two phase flow condition could be achieved, was designed and constructed. The effects of heat flux, void fraction and solution temperature on BWR fuel cladding corrosion resistance were quantitatively investigated. The main findings were as follows. (1) In situ measurements using high speed camera and a void sensor together with one dimensional two phase flow analysis results showed that a two phase flow simulated BWR core condition can be obtained in the corrosion test facility. (2) The heat transfer corrosion test results showed that the thickness of the zirconium oxide layer increased with increasing solution temperature and was independent of heat flux and void fraction. The corrosion accelerating factor was about 2.5 times in the case of a temperature increase from 288degC to 350degC. (author)

Considerations for reduction of gas generation in a low-level radioactive waste repository

International Nuclear Information System (INIS)

Cho, Chan Hee; Son, Jung Kwon; Lee, Myung Chan; Song, Myung Jae

1997-01-01

In a low-level radioactive waste repository, H 2 , CO 2 , and CH 4 will be generated principally by the coupled processes of metal corrosion and microbial degradation of cellulosic waste. The metal corrosion model incorporates a three-stage process encompassing aerobic and anaerobic corrosion regimes; the microbial degradation model simulates the activities of eight different microbial populations, which are maintained as functions both of pH and of the concentrations of particular chemical species. A prediction is made for gas concentrations and generation rates over an assessment period of ten thousand years in a radioactive waste repository. The results suggest that H 2 is the principal gas generated within the radioactive waste cavern. The generation rates of CO 2 and CH 4 are likely to be insignificant by comparison with H 2 . Therefore, an effective way to decrease gas generation in a radioactive waste repository seems to be to reduce metal content since the generation rate of H 2 is most sensitive to the concentration of steel

Study of the Effect of Sulfide Ions on the Corrosion Resistance of Copper for Use in Containers for High Level radioactive waste

International Nuclear Information System (INIS)

Urbal Espinoza, Andrea Elizabeth

2000-01-01

The work 'Study of sulfide ion on Resisting Copper Corrosion' is part of the project 'Study of Copper Corrosion in Underground Water Solution in Reducer Conditions', which the Department of Nuclear Materials, Chilean Nuclear Energy Commission is carrying out. These activities are important because of this metal's potential applications for handling and controlling contaminating wastes that are a product of using nuclear energy in electric generation. Copper has important mechanical properties and is also resistant to disintegration in corrosive environments, which is an important condition for its use in manufacturing of high level radioactive waste containers. This work is based on a study of cyclic volta metric curves, anodic and cathodic polarization and potentiostatic measurements, with which the potential range, sweep speed system, electrochemical reactions involved and corrosion speed could be defined. The microstructural characterization of the films was done by Scanning Electron Microscopy (SEM), and the chemical composition and surface contamination of the film were studied by photoelectron spectroscopy induced by X- rays (XPS), and the crystalline structure by X- ray Diffraction (XRD). Some noticeable results, such as low potentials (less than .7 V, in cathode direction) and high concentrations of sulfur make the formation of copper sulfides (I) and (II) possible; unlike the potential over .6 V, in anodic direction, where copper oxides (I) and (II) are formed, but they are inhibited by high sulfur concentrations. The morphological study of the copper surface has shown that the film that forms is more abundant and granular at higher cathodic potentials, forming small pits on the surface. The effect of the presence of sulfur ions is minimal, and the metal's deterioration is inhibited by other ions in the groundwater. The corrosion rate is greater as the sulfur concentration rises, and a time period of 20,000 years can be predicted for the total corrosion of

Effects of iron-reducing bacteria and nitrate-reducing bacteria on the transformations of iron corrosion products, magnetite and siderite, formed at the surface of non-alloy steel

International Nuclear Information System (INIS)

Etique, Marjorie

2014-01-01

Radioactive waste is one of the major problems facing the nuclear industry. To circumvent this issue France plans to store vitrified high-level nuclear waste in a stainless steel container, placed into a non-alloy steel overpack, at a depth of 500 m in an argillaceous formation. The main iron corrosion products formed at the surface of the non-alloy steel are siderite (Fe II CO 3 ) and magnetite (Fe II Fe III 2 O 4 ). These compounds are formed in the anoxic conditions present in the nuclear waste repository and play a protective role against corrosion as a passive layer. This work aims to investigate the activity of nitrate-reducing bacteria (NRB, Klebsiella mobilis) and iron-reducing bacteria (IRB, Shewanella putrefaciens) during the transformation of siderite and magnetite, especially those involved in anoxic iron biogeochemical cycle. Klebsiella mobilis and Shewanella putrefaciens were first incubated with siderite or magnetite suspensions (high surface specific area) in order to exacerbate the microbial iron transformation, subsequently incubated with a magnetite/siderite film synthesized by anodic polarization at applied current density. The transformation of siderite and magnetite by direct or indirect microbial processes led to the formation of carbonated green rust (Fe II 4 Fe III 2 (OH) 12 CO 3 ). As a transient phase shared by several bacterial reactions involving Fe II and Fe III , this compound is the cornerstone of the anoxic iron biogeochemical cycle. The novelty of this thesis is the consideration of bacterial metabolisms of NRB and IRB often overlooked in bio-corrosion processes. (author) [fr

Containers and overpacks for high-level radioactive waste in deep geological disposal. Conditions: French Corrosion Programme

International Nuclear Information System (INIS)

Crusset, D.; Plas, F.; Santarini, G.

2003-01-01

Within the framework of the act of French law dated 31 December, 1991, ANDRA (National Radioactive Waste Management Agency) is responsible for conducting the feasibility study on disposal of reversible and irreversible high-level or long-life radioactive waste in deep geological formations. Consequently, ANDRA is carrying out research on corrosion of the metallic materials envisaged for the possible construction of overpacks for vitrified waste packages or containers for spent nuclear fuel. Low-alloy or unalloyed steels and the passive alloys (Fe-Ni-Cr-Mo) constitute the two families of materials studied and ANDRA has set up a research programme in partnership with other research organisations. The 'broad outlines' of the programme, which includes experimental and modelling operations, are presented. (authors)

Process for reducing radioactive contamination in waste product gypsum

International Nuclear Information System (INIS)

Lange, P.H. Jr.

1979-01-01

A process is described for reducing the radioactive contamination in waste product gypsum in which waste product gypsum is reacted with a dilute sulfuric acid containing barium sulfate to form an acid slurry at an elevated temperature, the slurry is preferably cooled, the acid component is separated from the solid, and the resulting solid is separated into a fine fraction and a coarse fraction. The fine fraction predominates in barium sulfate and radioactive contamination. The coarse fraction predominates in a purified gypsum product of reduced radioactive contamination

Microbial impact on metallic corrosion processes: case of iron reducing bacteria

International Nuclear Information System (INIS)

Esnault, Loic; Jullien, Michel; Libert, Marie; Mustin, Christian

2010-01-01

corrosion product alteration, magnetite and hematite mainly (c). For that, an optimised method of H2 measure at weak pressure has been realised by gaseous phase chromatography coupled with a sensitive pressure captor. - H 2 + Fe 3+ magnetite → Fe 2+ solution + 2H + (c) The interest of this study is to determine and to understand the reactivity of one model microbe species, the ferric-reducing bacterium 'Schewanella oneidensis strain MR-1', on a Fe(0) corrosion and these corrosion products (magnetite, hematite mainly) in presence or not of clay minerals (bentonite MX80). The introduction of short-term experiments in the scattered environment (batch) over reactivity Iron-bacteria with or without clay mineral is here studied through a kinetic study of H 2 bio-consumed or product, chemical analysis in solution, and by use a crystallo-chemistry tool (XRD and SEM). The main results are bio-alteration of corrosion products with development of ferri-reducing bacterial community. This microbial alteration entails an increase of aqueous corrosion by consumption of corrosion products (passivation layer). In such condition, corrosion process could be reactivated. (authors)

Potential for erosion corrosion of SRS high level waste tanks

International Nuclear Information System (INIS)

Zapp, P.E.

1994-01-01

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

Process for reducing radioactive contamination in phosphogypsum

International Nuclear Information System (INIS)

Palmer, J.W.; Gaynor, J.C.

1983-01-01

In a process for reducing radioactive contamination of phosphogypsum, anhydrite crystals are obtained through dehydration of the phosphogypsum in strong sulfuric acid: a portion of the anhydrite crystals is converted to subtantially radiation free gypsum by crystallizing out on radiation free gypsum seed crystals. These coarse radiation free gypsum crystals are then separated from the small anhydrite crystal relics containing substantially all of the radioactive contamination

Alternatives to reduce corrosion of carbon steel storage drums

International Nuclear Information System (INIS)

Zirker, L.R.; Beitel, G.A.

1995-11-01

The major tasks of this research were (a) pollution prevention opportunity assessments on the overpacking operations for failed or corroded drums, (b) research on existing container corrosion data, (c) investigation of the storage environment of the new Resource Conservation and Recovery Act Type II storage modules, (d) identification of waste streams that demonstrate deleterious corrosion affects on drum storage life, and (e) corrosion test cell program development. Twenty-one waste streams from five US Department of Energy (DOE) sites within the DOE Complex were identified to demonstrate a deleterious effect to steel storage drums. The major components of these waste streams include acids, salts, and solvent liquids, sludges, and still bottoms. The solvent-based waste streams typically had the shortest time to failure: 0.5 to 2 years. The results of this research support the position that pollution prevention evaluations at the front end of a project or process will reduce pollution on the back end

Stainless steel waste containers: an assessment of the probability of stress corrosion cracking

International Nuclear Information System (INIS)

Wanklyn, J.N.; Naish, C.C.

1991-06-01

The paper summarises information obtained from the literature and discussions held with corrosion experts from universities and industry, relevant to the possibility that stainless steel radioactive waste containers containing low level and intermediate level radioactive waste (LLW and ILW) could, when buried in concrete, suffer one or more of the forms of stress corrosion cracking (SCC). Stress corrosion cracking is caused by the simultaneous and synergistic action of a corrosive environment and stress. The initiation and propagation of SCC depend on a number of factors being present, namely a certain level of stress, an environment which will cause cracking and a susceptible metal or alloy. Generally the susceptibility of a metal or alloy to SCC increases as its strength level increases. The susceptibility in a specific environment will depend on: solution concentration, pH, temperature, and electrochemical potential of the metal/alloy. It is concluded that alkaline stress corrosion cracking is unlikely to occur under even the worst case conditions, that chloride stress corrosion cracking is a distinct possibility at the higher end of the temperature range (25-80 o C) and that stress corrosion related to sensitization of the steel will not be a problem for the majority of container material which is less than 5 mm in cross section. Thicker section material could become sensitized leading to a local problem in these areas. Contact with metals that are electrochemically more negative in corrosion potential is likely to reduce the incidence of SCC, at least locally. Measurement of repassivation potentials and rest potentials in solutions of relevant composition would provide a firmer prediction of the extent to which a high pH could reduce the likelihood of SCC caused by chlorides. (author)

Development of moving alternating magnetic filter using permanent magnet for removal of radioactive corrosion product from nuclear power plant

International Nuclear Information System (INIS)

Song, M. C.; Kim, S. I.; Lee, K. J.

2002-01-01

Radioactive Corrosion Products (CRUD) which are generated by the neutron activation of general corrosion products at the nuclear power plant are the major source of occupational radiation exposure. Most of the CRUD has a characteristic of showing strong ferrimagnetisms. Along with the new development and production of permanent magnet (rare earth magnet) which generates much stronger magnetic field than the conventional magnet, new type of magnetic filter that can separate CRUD efficiently and eventually reduce radiation exposure of personnel at nuclear power plant is suggested. This separator consists of inner and outer magnet assemblies, coolant channel and container surrounding the outer magnet assembly. The rotational motion of the inner and outer permanent magnet assemblies surrounding the coolant channel by driving motor system produces moving alternating magnetic fields in the coolant channel. The CRUD can be separated from the coolant by the moving alternating magnetic field. This study describes the results of preliminary experiment performed with the different flow rates of coolant and rotation velocities of magnet assemblies. This new magnetic filter shows better performance results of filtering the magnetite at coolant (water). Flow rates, rotating velocities of magnet assemblies and particle sizes turn out to be very important design parameters

A mechanism for corrosion product deposition on the carbon steel piping in the residual heat removal system of BWRs

International Nuclear Information System (INIS)

Aizawa, Motohiro; Chiba, Yoshinori; Hosokawa, Hideyuki; Ohsumi, Katsumi; Uchida, Shunsuke; Ishizawa, Noboru

2002-01-01

The dose rate of the residual heat removal (RHR) piping has been considered to be caused by accumulation of insoluble (crud) radioactive corrosion products on carbon steel surfaces. Soft shutdown procedures (i.e., plant shutdown with moderate coolant temperature reduction rate) used to be applied to reduce crud radioactivity release from the fuel surface, but these are no longer used because of the need for shorter plant shutdown times. In order to apply other suitable countermeasures to reduce RHR dose rate, assessment of plant data, experiments on deposition of crud and ion species on carbon steel, and mass balance evaluation of radioactive corrosion products based on plant and laboratory data were carried out and the following findings were made. (1) Deposits of ion species on carbon steel surfaces of the RHR piping was much more numerous than for crud. (2) Ion species accumulation behavior on RHR piping, which is temperature dependent, can be evaluated with the calculation model used for the dehydration reaction of corrosion products generated during the wet lay-up period. (3) Deposition amounts could be reduced to 1/2.5 when the starting RHR system operation temperature was lowered from 155degC to 120degC. (author)

Bio-corrosion for underground disposal of radioactive waste; Biocorrosion en conditions de stockage geologique de dechets radioactifs

Energy Technology Data Exchange (ETDEWEB)

Libert, M.; Esnault, L. [CEA, DEN/DTN/SMTM/LMTE, 13108 St Paul lez Durance, (France); Esnault, L. [ECOGEOSAFE, Technopole environnement Arbois-Mediterranee, avenue Louis Philibert, 13545 Aix-en-Provence Cedex, (France); Feron, D. [CEA, DEN/DANS/DPC, 91191 Gif-sur-Yvette, (France)

2011-07-01

The safety disposal of high level nuclear waste (HLNW) is the major breakthrough allowing socially acceptable development of nuclear energy over the coming decades. The French concept for geological disposal of HLNW is based on a multi-barrier system made by metallic containers confined in natural clay. The main alteration parameter is water arriving on waste after the corrosion of metallic components. The anoxic aqueous corrosion phenomena are studied in order to evaluate the confinement capacity of metallic barriers. The discover of active micro-organisms in deep clayey environments raises the question of the impact of micro-organisms on corrosion parameters due to processes such as 'biologically induced corrosion'. Despite of extreme conditions in deep nuclear geological disposal (redox conditions, high pressure and temperature, irradiation), bacterial activity will adapt and survive in these environments. Anoxic corrosion of nuclear waste containers and radiolysis will produce H{sub 2}, which represents a new energetic source for bacterial development, especially in this environment that contains a low amount of biodegradable organic matter. Besides, the formation of Fe(III)-bearing minerals such as magnetite (Fe{sub 3}O{sub 4}) as corrosion products will provide electron acceptors favouring the development of bacteria. Bio-corrosion studies of nuclear waste disposal need to investigate the activity of hydrogenotrophic bacteria able to reduce iron oxides (passivation layer) or sulfates (iron reducing bacteria and sulfate reducing bacteria) in order to evaluate their impact on the long-term stability of metallic compounds involved in multi-barrier system for high-level nuclear waste containment. (authors)

Archaeological analogs and corrosion

International Nuclear Information System (INIS)

David, D.

2008-01-01

In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

Evaluation of nitrogen containing reducing agents for the corrosion control of materials relevant to nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Kumar, Padma S. [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India); Mohan, D. [Department of Chemistry, Anna University, Chennai, Tamilnadu (India); Chandran, Sinu; Rajesh, Puspalata; Rangarajan, S. [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India); Velmurugan, S., E-mail: svelu@igcar.gov.in [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India)

2017-02-01

Materials undergo enhanced corrosion in the presence of oxidants in aqueous media. Usually, hydrogen gas or water soluble reducing agents are used for inhibiting corrosion. In the present study, the feasibility of using alternate reducing agents such as hydrazine, aqueous ammonia, and hydroxylamine that can stay in the liquid phase was investigated. A comparative study of corrosion behavior of the structural materials of the nuclear reactor viz. carbon steel (CS), stainless steel (SS-304 LN), monel-400 and incoloy-800 in the oxidizing and reducing conditions was also made. In nuclear industry, the presence of radiation field adds to the corrosion problems. The radiolysis products of water such as oxygen and hydrogen peroxide create an oxidizing environment that enhances the corrosion. Electrochemical studies at 90 °C showed that the reducing agents investigated were efficient in controlling corrosion processes in the presence of oxygen and hydrogen peroxide. Evaluation of thermal stability of hydrazine and its effect on corrosion potential of SS-304 LN were also investigated in the temperature range of 200–280 °C. The results showed that the thermal decomposition of hydrazine followed a first order kinetics. Besides, a change in electrochemical corrosion potential (ECP) was observed from −0.4 V (Vs SHE) to −0.67 V (Vs SHE) on addition of 5 ppm of hydrazine at 240 °C. Investigations were also made to understand the distribution behavior of hydrogen peroxide and hydrazine in water-steam phases and it was found that both the phases showed identical behavior. - Highlights: • Hydrazine was found to be a promising reducing agent for oxidant control. • In presence of hydrazine corrosion potential of SS304 LN was well below −230 mV. • SS304LN could be protected from IGSCC by hydrazine addition. • Thermal and radiation stability of hydrazine at 285 °C was found satisfactory.

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

Science.gov (United States)

Bellanger, G.; Rameau, J. J.

1996-02-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive -transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique.

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

Energy Technology Data Exchange (ETDEWEB)

Bellanger, G. [CEA Centre d`Etudes de Valduc, 21 - Is-sur-Tille (France); Rameau, J.J. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Saint-Martin-d`Heres (France)

1996-02-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive-transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique. (orig.).

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

International Nuclear Information System (INIS)

Bellanger, G.; Rameau, J.J.

1996-01-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive-transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique. (orig.)

Microbiologically influenced corrosion of carbon steel in the presence of sulphate reducing bacteria

International Nuclear Information System (INIS)

Tunaru, M.; Velciu, L.; Mihalache, M.; Laurentiu, P.

2016-01-01

Sulphate-reducing bacteria (SRB) are the most important organisms in microbiologically induced corrosion. In this context, the paper presents an assessment (by experimental tests) of the behaviour of carbon steel samples (SA106gr.B) in SRB media. Some of samples were immersed in microbial environment in order microbiological analysis of their surface and another part was used to perform accelerated electrochemical tests to determine electrochemical parameters for the system carbon steel / microbial medium (corrosion rate, the polarization resistance of the surface, susceptibility to pitting corrosion). The surfaces of the tested samples were analyzed using the optical and electronic microscope, and emphasized the role of bacteria in the development of biofilms under which appeared characteristics of corrosion attack. The correlation of all results confirmed that SRB accelerated the localized corrosion of the surfaces of SA 106gr.B carbon steel. (authors)

Process for dissolving the radioactive corrosion products from internal surfaces in nuclear reactors

International Nuclear Information System (INIS)

Brown, W.W.

1976-01-01

This invention concerns a process for dissolving in the coolant flowing in a reactor the radioactive substances from the corrosion of the internal surfaces of the reactor to which they cling. When a reactor is operating, the fission occurring in the fuel generates gases and fission substances, such as iodine 131 and 133, cesium 134 and 137, molybdenum 99, xenon 133 and activates the structural materials of the reactor such as nickel by giving off cobalt 58 and similar substances. Under this invention an oxygen rich solution is injected in the reactor coolant after the temperature and pressure reduction stage, during the preparation prior to refuelling and repairs. The oxygen in the solution speeds up the release of cobalt 58 and other radioactive substances from the internal surfaces of the reactor and their dissolving in the oxygenated cold coolant at the start of the cooling procedures of the installation. This allows them to be removed by an ion exchanger before the reactor is emptied. By utilising this process, about half a day may be gained in refuelling time when this has to be done once a week [fr

Slippery liquid-infused porous surfaces fabricated on aluminum as a barrier to corrosion induced by sulfate reducing bacteria

International Nuclear Information System (INIS)

Wang, Peng; Lu, Zhou; Zhang, Dun

2015-01-01

Highlights: • Slippery liquid-infused porous surfaces (SLIPS) were fabricated over aluminum. • SLIPS depress the adherence of sulfate reducing bacteria in static seawater. • SLIPS inhibit the microbiological corrosion of aluminum in static seawater. • The possible microbiological corrosion protection mechanism of SLIPS is proposed. - Abstract: Microbiological corrosion induced by sulfate reducing bacteria (SRB) is one of the main threatens to the safety of marine structure. To reduce microbiological corrosion, slippery liquid infused porous surfaces (SLIPS) were designed and fabricated on aluminum substrate by constructing rough aluminum oxide layer, followed by fluorination of the rough layer and infiltration with lubricant. The as-fabricated SLIPS were characterized with wettability measurement, SEM and XPS. Their resistances to microbiological corrosion induced by SRB were evaluated with fluorescence microscopy and electrochemical measurement. It was demonstrated that they present high resistance to bacteria adherence and the resultant microbiological corrosion in static seawater

Active Waste Materials Corrosion and Decontamination Tests

International Nuclear Information System (INIS)

Danielson, M.J.; Elmore, M.R.; Pitman, S.G.

2000-01-01

Stainless steel alloys, 304L and 316L, were corrosion tested in representative radioactive samples of three actual Hanford tank waste solutions (Tanks AW-101, C-104, AN-107). Both the 304L and 316L exhibited good corrosion performance when immersed in boiling waste solutions. The maximum general corrosion rate was 0.015 mm/y (0.60 mils per year). Generally, the 304L had a slightly higher rate than the 316L. No localized attack was observed after 122 days of testing in the liquid phase, liquid/vapor phase, or vapor phase. Radioactive plate-out decontamination tests indicated that a 24-hour exposure to 1 und M HNO 3 could remove about 99% of the radioactive components in the metal film when exposed to the C-104 and AN-107 solutions. The decontamination results are less certain for the AW-101 solution, since the initial contamination readings exceeded the capacity of the meter used for this test

Bio-corrosion of water pipeline by sulphate-reducing bacteria in a ...

African Journals Online (AJOL)

esiri

2013-11-13

Nov 13, 2013 ... Key words: Sulphate-reducing bacteria, corrosion, water pipeline, biocide. INTRODUCTION ... small amount of organic material required to produce biomass):. )1(. 3. 2 .... Oil, gas and shipping industries are seriously affected.

Status of Database for Electrochemical Noise Based Corrosion Monitoring

International Nuclear Information System (INIS)

EDGEMON, G.L.

1999-01-01

Underground storage tanks made of mild steel are used to contain radioactive waste generated by plutonium production at the Hanford Site. Corrosion of the walls of these tanks is a major issue. Corrosion-related failure of waste tank walls could lead to the leakage of radioactive contaminants to the soil and groundwater. It is essential to monitor corrosion conditions of the tank walls to determine tank integrity and ensure safe waste storage until retrieval and final waste disposal can be accomplished. Corrosion monitoring/control is currently provided at the Hanford Site through a waste chemistry sampling and analysis program. In this process, tank waste is sampled, analyzed and compared to a selection of laboratory exposures of coupons in simulated waste. Tank wall corrosion is inferred by matching measured tank chemistries to the results of the laboratory simulant testing. This method is expensive, time consuming, and does not yield real-time data. A project to improve the Hanford Site's corrosion monitoring strategy was started in 1995

Finite element evaluation of erosion/corrosion affected reducing elbow

International Nuclear Information System (INIS)

Basavaraju, C.

1996-01-01

Erosion/corrosion is a primary source for wall thinning or degradation of carbon steel piping systems in service. A number of piping failures in the power industry have been attributed to erosion/corrosion. Piping elbow is one of such susceptible components for erosion/corrosion because of increased flow turbulence due to its geometry. In this paper, the acceptability of a 12 in. x 8 in. reducing elbow in RHR service water pump discharge piping, which experienced significant degradation due to wall thinning in localized areas, was evaluated using finite element analysis methodology. Since the simplified methods showed very small margin and recommended replacement of the elbow, a detailed 3-D finite element model was built using shell elements and analyzed for internal pressure and moment loadings. The finite element analysis incorporated the U.T. measured wall thickness data at various spots that experienced wall thinning. The results showed that the elbow is acceptable as-is until the next fuel cycle. FEA, though cumbersome, and time consuming is a valuable analytical tool in making critical decisions with regard to component replacement of border line situation cases, eliminating some conservatism while not compromising the safety

Contribution of the characterization of radioactive surfaces after sodium corrosion

International Nuclear Information System (INIS)

Menken, G.; Holl, M.

1978-01-01

Since 1972 INTERATOM is performing sodium mass and activity transfer investigations in an SNR-corrosion mockup loop which allows to study the transport of activated corrosion products in the primary heat transfer system of a sodium cooled reactor. The loop simulates the temperature and flow conditions and the materials combination of the SNR 300. The mass transfer examinations were aimed at the determination of the following: the linear corrosion and deposition rates; the selective corrosion of the alloying elements; the transfer of activated corrosion products. The results of a number of corrosion runs will be used in the following contribution to characterize the contaminated and corroded surface layers of reactor components. The loop reached a total operation time of 12300 h while the cold trap temperature was changed between 105 deg. C and 165 deg. C in successive runs

Role of sulphide species on the behaviour of carbon steel envisioned for high-level radioactive disposal: interaction between sulphide and corrosion products

International Nuclear Information System (INIS)

Bourdoiseau, Jacques-Andre

2011-01-01

This PhD work deals with the nuclear waste disposal. In France, it is envisaged by Andra (French national radioactive waste management agency) that high-level radioactive wastes will be confined in a glass matrix, stored in a stainless steel canister, it self placed in a carbon steel overpack. The wastes will then be stored at a depth of ∼500 m in a deep geological repository, drilled in a very stiff (indurated) clay (argillite) formation. The kinetics of corrosion expected for the overpack in this disposal concept are low and will stay low if the somehow protective rust layer that will develop initially on the steel surface remains undamaged. Local changes of the physico-chemical conditions may however degrade this layer and induce accelerated kinetics of corrosion. In particular, the growth of sulphate reducing bacteria (SRB) close to the steel overpack cannot be excluded and the sulphide species these micro-organisms produce may modify the corrosion process. The aim of this work was then to achieve a better understanding of the corrosion system constituted with steel, its rust layer mainly made of siderite FeCO 3 , and a sulphide-containing electrolyte. First, it proved necessary to characterise the iron sulphides involved in the corrosion processes by Raman micro-spectroscopy so as to study their formation and transformation mechanisms in various conditions of Fe(II) and S(-II) concentration, pH, temperature and aeration. It could be demonstrated that the Raman spectrum of mackinawite FeS, the compound that precipitated in any case from dissolved Fe(II) and S(-II) species with the experimental conditions considered here, depended on the crystallinity and oxidation state. Moreover, the mechanisms of the oxidation of mackinawite into greigite Fe 3 S 4 in acidic anoxic solutions at 80 C could be described. Finally, iron sulphides, often present on archaeological artefacts, could be identified using Raman micro-spectroscopy. The compounds present were mainly

Carbon steel corrosion induced by sulphate-reducing bacteria in artificial seawater: electrochemical and morphological characterizations

International Nuclear Information System (INIS)

Paula, Mariana Silva de; Goncalves, Marcia Monteiro Machado; Rola, Monick Alves da Cruz; Maciel, Diana Jose; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista do

2016-01-01

In this work, the corrosion behavior of carbon steel AISI 1020 was evaluated in artificial seawater in the presence of mixed sulfate-reducing bacteria (SRB) culture isolated from the rust of a pipeline. The corrosion evaluation was performed by electrochemical techniques (open circuit potential (E_o_c_p), polarization curves and electrochemical impedance spectroscopy (EIS)), while the formation of a biofilm and corrosion products were observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The presence of SRB in the medium shifted the open circuit potential to more positive values and increased the corrosion rate of the steel. Electrochemical and morphological techniques confirmed the presence of a biofilm on the steel surface. EDS spectra data showed the presence of sulfur in the corrosion products. After removing the biofilm, localized corrosion was observed on the surface, confirming that localized corrosion had occurred. The biogenic sulfide may lead to the formation of galvanic cells and contributes to cathodic depolarization. (author)

Carbon steel corrosion induced by sulphate-reducing bacteria in artificial seawater: electrochemical and morphological characterizations

Energy Technology Data Exchange (ETDEWEB)

Paula, Mariana Silva de; Goncalves, Marcia Monteiro Machado; Rola, Monick Alves da Cruz; Maciel, Diana Jose; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista do, E-mail: sdp.mari@gmail.com, E-mail: marciamg@uerj.br, E-mail: monickcruz@yahoo.com.br, E-mail: dijmaciel@gmail.com, E-mail: lsenna@uerj.br, E-mail: dalva@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Quimica

2016-10-15

In this work, the corrosion behavior of carbon steel AISI 1020 was evaluated in artificial seawater in the presence of mixed sulfate-reducing bacteria (SRB) culture isolated from the rust of a pipeline. The corrosion evaluation was performed by electrochemical techniques (open circuit potential (E{sub ocp}), polarization curves and electrochemical impedance spectroscopy (EIS)), while the formation of a biofilm and corrosion products were observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The presence of SRB in the medium shifted the open circuit potential to more positive values and increased the corrosion rate of the steel. Electrochemical and morphological techniques confirmed the presence of a biofilm on the steel surface. EDS spectra data showed the presence of sulfur in the corrosion products. After removing the biofilm, localized corrosion was observed on the surface, confirming that localized corrosion had occurred. The biogenic sulfide may lead to the formation of galvanic cells and contributes to cathodic depolarization. (author)

Marine sulfate-reducing bacteria cause serious corrosion of iron under electroconductive biogenic mineral crust

Science.gov (United States)

Enning, Dennis; Venzlaff, Hendrik; Garrelfs, Julia; Dinh, Hang T; Meyer, Volker; Mayrhofer, Karl; Hassel, Achim W; Stratmann, Martin; Widdel, Friedrich

2012-01-01

Iron (Fe0) corrosion in anoxic environments (e.g. inside pipelines), a process entailing considerable economic costs, is largely influenced by microorganisms, in particular sulfate-reducing bacteria (SRB). The process is characterized by formation of black crusts and metal pitting. The mechanism is usually explained by the corrosiveness of formed H2S, and scavenge of ‘cathodic’ H2 from chemical reaction of Fe0 with H2O. Here we studied peculiar marine SRB that grew lithotrophically with metallic iron as the only electron donor. They degraded up to 72% of iron coupons (10 mm × 10 mm × 1 mm) within five months, which is a technologically highly relevant corrosion rate (0.7 mm Fe0 year−1), while conventional H2-scavenging control strains were not corrosive. The black, hard mineral crust (FeS, FeCO3, Mg/CaCO3) deposited on the corroding metal exhibited electrical conductivity (50 S m−1). This was sufficient to explain the corrosion rate by electron flow from the metal (4Fe0 → 4Fe2+ + 8e−) through semiconductive sulfides to the crust-colonizing cells reducing sulfate (8e− + SO42− + 9H+ → HS− + 4H2O). Hence, anaerobic microbial iron corrosion obviously bypasses H2 rather than depends on it. SRB with such corrosive potential were revealed at naturally high numbers at a coastal marine sediment site. Iron coupons buried there were corroded and covered by the characteristic mineral crust. It is speculated that anaerobic biocorrosion is due to the promiscuous use of an ecophysiologically relevant catabolic trait for uptake of external electrons from abiotic or biotic sources in sediments. PMID:22616633

Underground Corrosion by Microorganisms Part II : Role of Anaerobic Sulphate Reducing Bacteria-Desulfotomaculum SP

OpenAIRE

H. M. Dayal; K. C. Tiwari; Kamlesh Mehta; Mr. Chandrashekhar

1988-01-01

During the course of studies on the corrosion causing soil microflora from different geoclimatic regions of India, several strains of anaerobic sulphate reducing bacteria belonging to genus Desulfotomaculum were isolated and characterised. Their corrosive action on mild steel, galvanised iron and structural aluminium, the three main metals of construction of underground structures, have been studied under laboratory conditions.

Corrosivity of solutions from evaporation of radioactive liquid wastes. Final report

International Nuclear Information System (INIS)

Payer, H.; Kolic, E.S.; Boyd, W.K.

1977-01-01

New double-shell storage tanks are constructed with ASTM A-516 Grade 65 steel. This study had two main objectives: To characterize the corrosivity of synthetic nonradioactive terminal waste solutions to ASTM A-516 Grade 65 steel and to determine the severity of stress-corrosion cracking of carbon steel in terminal waste solutions. The information developed provides guidance in the characterization of the aggressiveness of actual terminal liquors and in the design and operation of fail-safe tanks. Corrosion behavior was measured over a range of oxidizing conditions by the potentiodynamic polarization technique. Oxidizing conditions in a solution likely to promote general corrosion, pitting or stress-corrosion cracking (SCC) were identified. Absolute stress-corrosion cracking susceptibility was determined by constant strain rate procedure for ASTM A-516 Grade 65 steel for conditions identified by polarization experiments as likely to promote SCC. Based on the results of this study, terminal waste storage tanks are safe from stress-corrosion cracking under freely corroding conditions. Corrosion potential of steel in solutions within anticipated compositions is at the positive end of the critical range for stress-corrosion cracking, and no conditions were observed which would lower the potential to more negative values within the cracking range under freely corroding conditions. Measurement of corrosion potential and hydroxide concentration provides a means to extend these results to compositions outside of the composition range studied

Electrodeposited Reduced Graphene Oxide Films on Stainless Steel, Copper, and Aluminum for Corrosion Protection Enhancement

OpenAIRE

Abdulkareem Mohammed Ali Al-Sammarraie; Mazin Hasan Raheema

2017-01-01

The enhancement of corrosion protection of metals and alloys by coating with simple, low cost, and highly adhered layer is still a main goal of many workers. In this research graphite flakes converted into graphene oxide using modified Hammers method and then reduced graphene oxide was electrodeposited on stainless steel 316, copper, and aluminum for corrosion protection application in seawater at four temperatures, namely, 20, 30, 40, and 50°C. All corrosion measurements, kinetics, and therm...

A computer analysis code of radioactive corrosion product behaviour in primary circuits of LMFBRs (PSYCHE)

International Nuclear Information System (INIS)

Iizawa, Katsuyuki; Seki, Seiichi; Kawasaki, Yuji; Kano, Shigeki; Nihei, Isao

1986-01-01

Recently it has become an important subject to reduce exposure to radiation from radioactive corrosion products (CPs) during maintenance and repair works in reactor plants. Metallic sodium is used as cooling material in fast reactor plants, leading to different CP behaviours compared to light water reactors. In the present study, a computer code for analyzing behaviours of CPs in fast reactor plants is developed. The analysis code, called PSYCHE, makes it possible to perform consistent analysis of production, migration and deposition of CPs in primary circuits together with dose rate around piping of apparatus in cooling systems. An analysis model is developed based on test results on CP behaviour in out-pile sodium. The model, called the ''dissolution-deposition model'', can reproduce atom-selective behaviour, transient phenomenon and downstream effect of CPs, which represent mass transfer phenomena in sodium. Verification of this code is carried out on the basis of CP measurements made in ''Joyo''. The calculation vs. measurement ratio is found to be 0.5 - 2 for CP deposition density in piping for cooling systems and 0.7 - 1.3 for dose rate, demonstrating that this code can give reasonable results. Analysis is also made to predict future changes in total amount of deposited CP in ''Joyo''. (Nogami, K.)

Influence of calcareous deposit on corrosion behavior of Q235 carbon steel with sulfate-reducing bacteria

Science.gov (United States)

Zhang, Jie; Li, Xiaolong; Wang, Jiangwei; Xu, Weichen; Duan, Jizhou; Chen, Shougang; Hou, Baorong

2017-12-01

Cathodic protection is a very effective method to protect metals, which can form calcareous deposits on metal surface. Research on the interrelationship between fouling organism and calcareous deposits is very important but very limited, especially sulfate-reducing bacteria (SRB). SRB is a kind of very important fouling organism that causes microbial corrosion of metals. A study of the influence of calcareous deposit on corrosion behavior of Q235 carbon steel in SRB-containing culture medium was carried out using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and surface spectroscopy (EDS). The calcareous deposit was formed with good crystallinity and smooth surface under the gradient current density of -30 μA cm-2 in natural seawater for 72 h. Our results can help elucidate the formation of calcareous deposits and reveal the interrelationship between SRB and calcareous deposits under cathodic protection. The results indicate that the corrosion tendency of carbon steel was obviously affected by Sulfate-reducing Bacteria (SRB) metabolic activity and the calcareous deposit formed on the surface of carbon steel under cathodic protection was favourable to reduce the corrosion rate. Calcareous deposits can promote bacterial adhesion before biofilm formation. The results revealed the interaction between biofouling and calcareous deposits, and the anti-corrosion ability was enhanced by a kind of inorganic and organic composite membranes formed by biofilm and calcareous deposits.

Calculated model of radioactive fission and corrosion product accumulation and distribution in a fast reactor sodium coolant circuit

International Nuclear Information System (INIS)

Kizin, V.D.; Konyashov, V.V.

1987-01-01

A simple calculation procedure of radioactive products accumulation and distribution in a primary circuit has been developed on the basis of experimental investigations at the BOR-60 reactor. Common knowledge on the impurity products transfer at the liquid-solid and liquid-gas phase boundary is taken. Use is made of the typical in reactor physics relationships for the description of the products transition to the equipment surfaces, of fission products release, metal corrosion and others. Satisfactory agreement of the calculation data with the experimental ones has been obtained. (orig.)

Sealing method and sealing device for radioactive waste containing vessel

International Nuclear Information System (INIS)

Ishiwatari, Koji; Otsuki, Akira

1998-01-01

A radioactive waste-containing body is hoisted down into a strong-material vessel opened upwardly, and a strong-material lid is hoisted down to the opening of the strong-material-vessel and welded. The strong material vessel is hoisted up and loaded on a corrosion resistant-material bottom plate placed horizontally. A corrosion resistant-material vessel having one opening end and having a corrosion resistant-material flange on the other end and previously agreed with the strong material-vessel main body is hoisted up by a hoisting device having an inserting device so that the opening of the corrosion resistant vessel is directed downwardly. The corrosion resistant vessel is press-fitted to the outside of the strong material-vessel by the inserting device while being heated by a preheater to shrink. Subsequently, the lower end of the corrosion resistant-material vessel and the corrosion resistant-material bottom plate are welded to constitute a corrosion resistant-material vessel. Then, the radioactive waste containing body can be sealed in a sealing vessel comprising the strong-material vessel and the corrosion resistant-material vessel. (N.H.)

Measurement and evaluation of radioactive corrosion product behaviour in primary sodium circuits of JOYO

International Nuclear Information System (INIS)

Ito, K.; Iizawa, K.; Takahashi, K.; Zulquarnain, M.A.; Suzuki, S.; Kinjo, K.

1992-01-01

In the experimental fast reactor JOYO, the radioactive corrosion product (CP) measurement has been conducted in the primary sodium circuits during each annual inspection. The measured data has been analyzed by the computer code 'PSYCHE', which has been developed by PNC. Main results obtained from the measurements and/or calculations are as follows; (1) The dominant CP nuclide is 54 Mn followed by 60 Co and 58 Co. (2) Average surface gamma dose rate around the primary piping system at the 8th annual inspection is 0.96 mSv/h. The increasing rate of this value is 0.25 (mSv/h)/EFPY. (3) The calculated deposition densities of 54 Mn and 60 Co agree with measured ones within factor of 0.7 ∼ 1.7. (author)

Development for low-activation concrete design reducing radioactive waste

International Nuclear Information System (INIS)

Kimura, Ken-ichi; Kinno, Masaharu; Hasegawa, Akira

2008-01-01

Full text: Concrete is very valuable and inexpensive material, however it can be changed to be expensive and hard to deal with in use of a nuclear plant after long operation. One of the counter plans for the above is to use low-activation concrete instead of the ordinary concrete, that will reduce radioactive waste and could be even below clearance level in decommissioning and that is very useful in term of life cycle cost. Radioactive analysis showed that Co and Eu were the major target elements which decide the radioactivity level of reinforced concrete in decommissioning stage, and a several material were selected as a low-activation raw material from wide survey of raw materials for concrete (typically aggregates and cements). With the canditate of raw materials, several low-activation concrete were proposed for various portion of light water reactor plant, which reduction ratio were 1/10 to 1/30 which were mainly consist of limestone and low heat cement or white cement, and 1/100 to 1/300 which were mainly consist of alumina aggregate or quartz and high almina cement, comparing to the ordinary concrete in ΣDi/Ci unit, where 'Di' indicates concentration of each residual radioisotope, Ci defined by IAEA as a clearance level, and suffition of 'i' indicates each radioisotope. National funded project for development of low-activation design method for reduction of radioactive waste below clearance level were started from 2005 with aiming (1) development of a database on the content of target elements, which transform radioactive nuclides, in raw materials of reinforced concrete, (2) development of calculation tools for estimation of residual radioactivity of plant components, and (3) development of low-activation materials for concrete such as cements and reinforcing steel bars for structural components. For the optimized design for applying low-activation concrete to the reactor portion, effective evaluation of neutron spectrum in the certain portion including

Method of reducing the volume of radioactive waste

International Nuclear Information System (INIS)

Buckley, L.P.; Burrill, K.A.; Desjardins, C.D.; Salter, R.S.

1984-01-01

There is provided a method of reducing the volume of radioactive waste, comprising: pyrolyzing the radioactive waste in the interior of a vessel, while passing superheated steam through the vessel at a temperature in the range 500 to 700 degrees C, a pressure in the range 1.0 to 3.5 MPa, and at a flow rate in the range 4 to 50 mL/s/m 3 of the volume of the vessel interior, to cause pyrohydrolysis of the waste and to remove carbon-containing components of the pyrolyzed waste from the vessel as gaseous oxides, leaving an ash residue in the vessel. Entrained particles present with the gaseous oxides are filtered and acidic vapours present with the gaseous oxides are removed by solid sorbent. Steam and any organic substances present with the gaseous oxides are condensed and the ash is removed from the vessel. The radioactive waste may be deposited upon an upper screen in the vessel, so that a substantial portion of the pyrolysis of the radioactive waste takes place while the radioactive waste is on the upper screen, and pyrolyzed waste falls through the upper screen onto a lower screen, where another substantial portion of the pyrohydrolysis takes place. The ash residue falls through the lower screen

A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS

International Nuclear Information System (INIS)

BOOMER, K.D.

2007-01-01

The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed

Improvement of Corrosion Inhibitors of Primary and Secondary Closed Cooling Water System

International Nuclear Information System (INIS)

Choi, Byung Seon; Kim, K. M.; Kim, K. H.

2010-08-01

In nuclear power plants, the Closed Cooling Water (CCW) system provide cooling to both safety-related and non-safety-related heat exchange equipment. Various chemicals are used to mitigate corrosion, fouling, and microbiological growth in the CCW systems. In nuclear plants, these inhibitors have included chromates, nitrites, molybdates, hydrazine, and silicate. In the case of the CCW of some domestic nuclear power plants, there is during the overhaul period, a saturation of ion exchange resin caused by an inhibitor which has high conductivity for an increase in radiation exposure and radioactive waste. The objective of this study is to evaluate the corrosion behavior of structural materials with various corrosion inhibitors. In the present study, more than 50 ppm hydrazine concentration is needed to reduce the corrosion rate of carbon steel to satisfy the CCW operational guidelines. However, if hydrazine is continuously injected into the CCW system, the critical concentration of hydrazine will be lower. Hydrazine might be an alternative corrosion inhibitor for nitrite in the CCW system of nuclear power plant

Radioactive waste removing device

International Nuclear Information System (INIS)

Sakai, Takuhiko.

1982-01-01

Purpose: To cleanup primary coolants for LMFBR type reactors by magnetically generating a high speed rotational flow in the flow of liquid metal, and adsorbing radioactive corrosion products and fission products onto capturing material of a complicated shape. Constitution: Three-phase AC coils for generating a rotational magnetic field are provided to the outside of a container through which liquid sodium is passed to thereby generate a high speed rotational stream in the liquid sodium flowing into the container. A radioactive substance capturing material made of a metal plate such as of nickel and stainless steel in the corrugated shape with shape edges is secured within a flow channel. Magnetic field at a great slope is generated in the flow channel by the capturing material to adsorb radioactive corrosion products and fission products present in the liquid sodium onto the capturing material and removing therefrom. This enables to capture the ferri-magnetic impurities by adsorption. (Moriyama, K.)

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

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

DEFF Research Database (Denmark)

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

2009-01-01

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

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

DEFF Research Database (Denmark)

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

2017-01-01

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

Priorities for technology development and policy to reduce the risk from radioactive materials

International Nuclear Information System (INIS)

Duggan, Ruth Ann

2010-01-01

The Standing Committee on International Security of Radioactive and Nuclear Materials in the Nonproliferation and Arms Control Division conducted its fourth annual workshop in February 2010 on Reducing the Risk from Radioactive and Nuclear Materials. This workshop examined new technologies in real-time tracking of radioactive materials, new risks and policy issues in transportation security, the best practices and challenges found in addressing illicit radioactive materials trafficking, industry leadership in reducing proliferation risk, and verification of the Nuclear Nonproliferation Treaty, Article VI. Technology gaps, policy gaps, and prioritization for addressing the identified gaps were discussed. Participants included academia, policy makers, radioactive materials users, physical security and safeguards specialists, and vendors of radioactive sources and transportation services. This paper summarizes the results of this workshop with the recommendations and calls to action for the Institute of Nuclear Materials Management (INMM) membership community.

Corrosion engineering in nuclear power industry

International Nuclear Information System (INIS)

Prazak, M.; Tlamsa, J.; Jirousova, D.; Silber, K.

1990-01-01

Corrosion problems in nuclear power industry are discussed from the point of view of anticorrosion measures, whose aim is not only increasing the lifetime of the equipment but, first of all, securing ecological safety. A brief description is given of causes of corrosion damage that occurred at Czechoslovak nuclear power plants and which could have been prevented. These involve the corrosion of large-volume radioactive waste tanks made of the CSN 17247 steel and of waste piping of an ion exchange station made of the same material, a crack in a steam generator collector, contamination of primary circuit water with iron, and corrosion of CrNi corrosion-resistant steel in a spent fuel store. It is concluded that if a sufficient insight into the corrosion relationships exists and a reasonable volume of data is available concerning the corrosion state during the nuclear facility performance, the required safety can be achieved without adopting extremely costly anticorrosion measures. (Z.M.)

New technologies - new corrosion problems

International Nuclear Information System (INIS)

Heitz, E.

1994-01-01

Adequate resistance of materials to corrosion is equally important for classical and for new technologies. This article considers the economic consequences of corrosion damage and, in addition to the long-known GNP orientation, presents a new approach to the estimation of the costs of corrosion and corrosion protection via maintenance and especially corrosion-related maintenance. The significance of ''high-tech'', ''medium-tech'' and ''low-tech'' material and corrosion problems is assessed. Selected examples taken from new technologies in the areas of power engineering, environmental engineering, chemical engineering, and biotechnology demonstrate the great significance of the problems. It is concluded that corrosion research and corrosion prevention technology will never come to an end but will constantly face new problems. Two technologies are of particular interest since they focus attention on new methods of investigation: microelectronics and final disposal of radioactive wastes. The article closes by considering the importance of the transfer of experience and technology. Since the manufacturs and operators of machines and plant do not generally have access to the very latest knowledge, they should be kept informed through advisory services, experimental studies, databases, and further education. (orig.) [de

Activity of corrosion products in pool type reactors with ascending flow in the core

International Nuclear Information System (INIS)

Andrade e Silva, Graciete S. de; Queiroz Bogado Leite, Sergio de

1995-01-01

A model for the activity of corrosion products in the water of a pool type reactor with ascending flow is presented. The problem is described by a set of coupled differential equations relating the radioisotope concentrations in the core and pool circuits and taking into account two types of radioactive sources: i) those from radioactive species formed in the fuel cladding, control elements, reflector, etc, and afterwards released to the primary stream by corrosion (named reactor sources) and ii) those formed from non radioactive isotopes entering the primary stream by corrosion of the circuit components and being activated when passing through the core (named circuit sources). (author). 6 refs, 3 figs, 4 tabs

Method of disposing radioactive wastes

International Nuclear Information System (INIS)

Isozaki, Kei.

1983-01-01

Purpose : To enable safety ocean disposal of radioactive wastes by decreasing the leaching rate of radioactive nucleides, improving the quick-curing nature and increasing the durability. Method : A mixture comprising 2 - 20 parts by weight of alkali metal hydroxide and 100 parts by weight of finely powdered aqueous slags from a blast furnace is added to radioactive wastes to solidify them. In the case of medium or low level radioactive wastes, the solidification agent is added by 200 parts by weight to 100 parts by weight of the wastes and, in the case of high level wastes, the solidification agent is added in such an amount that the wastes occupy about 20% by weight in the total of the wastes and the solidification agent. Sodium hydroxide used as the alkali metal hydroxide is partially replaced with sodium carbonate, a water-reducing agent such as lignin sulfonate is added to improve the fluidity and suppress the leaching rate and the wastes are solidified in a drum can. In this way, corrosions of the vessel can be suppressed by the alkaline nature and the compression strength, heat stability and the like of the product also become excellent. (Sekiya, K.)

Quantitative assessment of the effect of corrosion product buildup on occupational exposure

International Nuclear Information System (INIS)

Divine, J.R.

1982-10-01

The program was developed to provide a method for predicting occupational exposures caused by the deposition of radioactive corrosion products outside the core of the primary system of an operating power reactor. This predictive capability will be useful in forecasting total occupational doses during maintenance, inspection, decontamination, waste treatment, and disposal. In developing a reliable predictive model, a better understanding of the parameters important to corrosion product film formation, corrosion product transport, and corrosion product film removal will be developed. This understanding can lead to new concepts in reactor design to minimize the buildup and transport of radioactive corrosion products or to improve methods of operation. To achieve this goal, three objectives were established to provide: (1) criteria for acceptable coolant sampling procedures and sampling equipment that will provide data which will be used in the model development; (2) a quantitative assessment of the effect of corrosion product deposits on occupational exposure; and (3) a model which describes the influence of flow, temperature, coolant chemistry, construction materials, radiation, and other operating parameters on the transport and buildup of corrosion products

Real time nanogravimetric monitoring of corrosion in radioactive environments

OpenAIRE

Tzagkaroulakis, Ioannis; Boxall, Colin

2017-01-01

Monitoring and understanding the mechanism of metal corrosion throughout the nuclear fuel cycle play a key role in the safe asset management of facilities. They also provide information essential for making an informed choice regarding the selection of decontamination methods for steel plant and equipment scheduled for decommissioning. Recent advances in Quartz Crystal Nanobalance (QCN) technology offer the means of monitoring corrosion in-situ, in radiologically harsh environments, in real t...

Radioactive substance separation systems

International Nuclear Information System (INIS)

Sakai, Takuhiko.

1981-01-01

Purpose: To enable separation of fission products, radioactive corrosion products and the likes in primary coolants with no requirement for the replacement of separation system during plant service life, by providing protruded magnetic pole plates in a liquid metal flow channel to thereby form slopes magnetic fields. Constitution: A plurality of magnetic pole plates are disposed vertically in a comb-like arrangement so as not to contact with each other along the direction of flow in a rectangular primary coolant pipeway at the exit of the reactor core in an LMFBR type reactor. Large magnetic poles are provided to the upper and lower sides of the pipeway and coils are wound on the side opposed to the pipeway. When electrical current is supplied to the coils, the magnetic pole is magnetized intensely and thus the magnetic pole plates are also magnetized intensely and thus the magnetic pole plates are also magnetized intensely to form large gradient in the magnetic fields between the upper and lower magnetic plates, whereby ferromagnetic and ferrimagnetic fission products and radioactive corrosion products in the coolants are intensely adsorbed and not detached by the flow of the coolants. Accordingly, the fission products and the radioactive corrosion products can surely be removed with no requirement for the exchange of separation system during plant service life. (Horiuchi, T.)

Corrosion of carbon steel in clay environments relevant to radioactive waste geological disposals, Mont Terri rock laboratory (Switzerland)

Energy Technology Data Exchange (ETDEWEB)

Necib, S. [Agence Nationale pour la Gestion des Déchets Radioactifs ANDRA, Meuse Haute-Marne, Center RD 960, Bure (France); Diomidis, N. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); Keech, P. [Nuclear Waste Management Organisation NWMO, Toronto (Canada); Nakayama, M. [Japan Atomic Energy Agency JAEA, Horonobe-Cho (Japan)

2017-04-15

Carbon steel is widely considered as a candidate material for the construction of spent fuel and high-level waste disposal canisters. In order to investigate corrosion processes representative of the long term evolution of deep geological repositories, two in situ experiments are being conducted in the Mont Terri rock laboratory. The iron corrosion (IC) experiment, aims to measure the evolution of the instantaneous corrosion rate of carbon steel in contact with Opalinus Clay as a function of time, by using electrochemical impedance spectroscopy measurements. The Iron Corrosion in Bentonite (IC-A) experiment intends to determine the evolution of the average corrosion rate of carbon steel in contact with bentonite of different densities, by using gravimetric and surface analysis measurements, post exposure. Both experiments investigate the effect of microbial activity on corrosion. In the IC experiment, carbon steel showed a gradual decrease of the corrosion rate over a period of 7 years, which is consistent with the ongoing formation of protective corrosion products. Corrosion product layers composed of magnetite, mackinawite, hydroxychloride and siderite with some traces of oxidising species such as goethite were identified on the steel surface. Microbial investigations revealed thermophilic bacteria (sulphate and thiosulphate reducing bacteria) at the metal surface in low concentrations. In the IC-A experiment, carbon steel samples in direct contact with bentonite exhibited corrosion rates in the range of 2 µm/year after 20 months of exposure, in agreement with measurements in absence of microbes. Microstructural and chemical characterisation of the samples identified a complex corrosion product consisting mainly of magnetite. Microbial investigations confirmed the limited viability of microbes in highly compacted bentonite. (authors)

The evolution of carbon-14 and tritium containing gases in a radioactive waste repository

International Nuclear Information System (INIS)

Jefferies, N.L.

1990-04-01

The principal processes which well lead to the formation of gases in a repository containing low- and intermediate-level radioactive waste have been identified as corrosion, microbiological activity and radiolysis. The largest contribution to gas production is from hydrogen, generated from anaerobic corrosion of metallic components of the waste. Substitution of the active isotopes carbon-14 and hydrogen-3 (tritium) into the bulk gases, H 2 CO 2 and CH 4 may result in a radiological hazard to man. The purpose of this paper is to assess the mechanisms by which C-14 and tritium in solid low- and intermediate-level wastes are partitioned into gases reduced by corrosion and microbial processes. (author)

Process for ultimate storage of radioactive fission products

International Nuclear Information System (INIS)

Baukal, W.; Gruenthaler, K.H.; Neumann, K.

1980-01-01

In order to exclude cracking in the cooling phase during sealing of radioactive oxidic fission products in glass melts, metallic filling elements - e.g. wires, tissues - are proposed to be incorporated in the mould before the glass melt is poured in. Especially nickel alloys with corrosion proof surface layers, e.g. titanium nitride, silicon carbide, silicon nitride, aluminium oxide, suit best. These elements reduce thermal stresses and effect high thermal conductance towards the mould wall. (UWI) [de

Waste Tank Corrosion Program at Savannah River Site

International Nuclear Information System (INIS)

Chandler, J.R.; Hsu, T.C.; Hobbs, D.T.; Iyer, N.C.; Marra, J.E.; Zapp, P.E.

1993-01-01

The Savannah River Site (SRS) has approximately 30 million gallons of high level radioactive waste stored in 51 underground tanks. SRS has maintained an active corrosion research and corrosion control and monitoring program throughout the operating history of SRS nuclear waste storage tanks. This program is largely responsible for the successful waste storage experience at SRS. The program has consisted of extensive monitoring of the tanks and surrounding environment for evidence of leaks, extensive research to understand the potential corrosion processes, and development and implementation of corrosion chemistry control. Current issues associated with waste tank corrosion are primarily focused on waste processing operations and are being addressed by a number of active programs and initiatives

Corrosion susceptibility of steel drums containing cemented intermediate level nuclear wastes

Science.gov (United States)

Duffó, Gustavo S.; Farina, Silvia B.; Schulz, Fátima M.; Marotta, Francesca

2010-10-01

Cementation processes are used as immobilization techniques for low or intermediate level radioactive waste for economical and safety reasons and for being a simple operation. In particular, ion-exchange resins commonly used for purification of radioactive liquid waste from nuclear reactors are immobilized before being stored to improve the leach resistance of the waste matrix and to maintain mechanical stability. Combustible solid radioactive waste can be incinerated and the resulting ashes can also be immobilized before storage. The immobilized resins and ashes are then contained in steel drums that may undergo corrosion depending on the presence of certain contaminants. The work described in this paper was aimed at evaluating the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins and incineration ashes containing different concentrations of aggressive species (mostly chloride and sulphate ions). A special type of specimen was designed to simulate the cemented waste in the drum. The evolution of the corrosion potential and the corrosion current density of the steel, as well as the electrical resistivity of the matrix were monitored over a time period of 1 year. The results show the deleterious effect of chloride on the expected lifespan of the waste containers.

Corrosion susceptibility of steel drums containing cemented intermediate level nuclear wastes

International Nuclear Information System (INIS)

Duffo, Gustavo S.; Farina, Silvia B.; Schulz, Fatima M.; Marotta, Francesca

2010-01-01

Cementation processes are used as immobilization techniques for low or intermediate level radioactive waste for economical and safety reasons and for being a simple operation. In particular, ion-exchange resins commonly used for purification of radioactive liquid waste from nuclear reactors are immobilized before being stored to improve the leach resistance of the waste matrix and to maintain mechanical stability. Combustible solid radioactive waste can be incinerated and the resulting ashes can also be immobilized before storage. The immobilized resins and ashes are then contained in steel drums that may undergo corrosion depending on the presence of certain contaminants. The work described in this paper was aimed at evaluating the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins and incineration ashes containing different concentrations of aggressive species (mostly chloride and sulphate ions). A special type of specimen was designed to simulate the cemented waste in the drum. The evolution of the corrosion potential and the corrosion current density of the steel, as well as the electrical resistivity of the matrix were monitored over a time period of 1 year. The results show the deleterious effect of chloride on the expected lifespan of the waste containers.

Deposition of radioactive corrosion products on the internal surfaces of tube elements in gaseous phase of dissociating system N2O4 reversible 2NO2 reversible 2NO+O2

International Nuclear Information System (INIS)

Gol'tsev, V.P.; Dolgov, V.M.; Katanaev, A.O.

1979-01-01

Analysis of experimental data, obtained as a result of γ-scanning of tube element samples of loop assembling with dissociating coolant contacting with N 2 O 4 gaseous phase is presented. Radioactive depositions are differentiated on fixed and unfixed ones by the method of radiochemical analysis. The data obtained have made it possible to establish the analytical form of radioactive element distribution functions along the piping length. It is noted, that relative quantities of radioactive isotopes, existing in fixed and unfixed depositions vary with temperature. The fraction of soluble forms of corrosion radioactive products in unfixed depositions increases both with the decrease of temperature and after passing of radioactive impurity through the zone of liquid coolant

Corrosion of canister materials for radioactive waste disposal

International Nuclear Information System (INIS)

Kienzler, Bernhard

2017-01-01

In the period between 1980 and 2004, corrosion studies on various metallic materials have been performed at the Research Center Karlsruhe. The objectives of these experimental studies addressed mainly the performance of canister materials for heat producing, high-level wastes and spent nuclear fuels for a repository in a German salt dome. Additional studies covered the performance of steels for packaging wastes with negligible heat production under conditions to be expected in rocksalt and in the Konrad iron ore mine. The results of the investigations have been published in journals and conference proceedings but also in ''grey literature''. This paper presents a summary of the results of corrosion experiments with fine-grained steels and nodular cast steel.

Study of sulphate-reducing bacteria corrosion in the weld joint for API X-70 steel

Energy Technology Data Exchange (ETDEWEB)

Flores, J. E.; Patino-Carachure, C.; Alfonso, I.; Rodriguez, J. A.; Rosas, G.

2012-11-01

The corrosion behavior originated by sulfate-reducing bacteria (SRB) was studied in two regions of welded API X-70 steel pipeline. The studies were focused on base material (BM) and heat affected zone (HAZ), from the internal region of the pipe. SRB were extracted from oil and grown in a Postgate medium. Corrosion was evaluated at 60 degree centigrade for times between 5 and 64 days. Potentiodynamic polarization curves, obtained by electrochemical techniques, indicated surface activation at short times. Structural and morphological characterizations were carried out by scanning electron microscopy (SEM) and optical microscopy (OM). H{sub 2}S concentration and pH were also measured. Results showed an important increase in the corrosion damage up to 20 days, influenced by the SRB activity, which lead to a maximum of H{sub 2}S (pH minimum). It was found a localized corrosion attack in the HAZ in a higher quantity compared to BM; and the formation of a thin film on the steel surface, originated by corrosion products and bacterial activity. (Author) 15 refs.

Modelling aqueous corrosion of nuclear waste phosphate glass

Energy Technology Data Exchange (ETDEWEB)

Poluektov, Pavel P.; Schmidt, Olga V.; Kascheev, Vladimir A. [Bochvar All-Russian Scientific Research Institute for Inorganic Materials (VNIINM), Moscow (Russian Federation); Ojovan, Michael I., E-mail: m.ojovan@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2017-02-15

A model is presented on nuclear sodium alumina phosphate (NAP) glass aqueous corrosion accounting for dissolution of radioactive glass and formation of corrosion products surface layer on the glass contacting ground water of a disposal environment. Modelling is used to process available experimental data demonstrating the generic inhibiting role of corrosion products on the NAP glass surface. - Highlights: • The radionuclides yield is determined by the transport from the glass through the surface corrosion layer. • Formation of the surface layer is due to the dissolution of the glass network and the formation of insoluble compounds. • The model proposed accounts for glass dissolution, formation of corrosion layer, specie diffusion and chemical reactions. • Analytical solutions are found for corrosion layer growth rate and glass components component leaching rates.

Residual stresses and stress corrosion effects in cast steel nuclear waste overpacks

International Nuclear Information System (INIS)

Attinger, R.O.; Mercier, O.; Knecht, B.; Rosselet, A.; Simpson, J.P.

1991-01-01

In the concepts for final disposal of high-level radioactive waste in Switzerland, one engineered barrier consists of an overpack made out of cast steel GS-40. Whenever tensile stresses are expected in the overpack, the issue of stress corrosion cracking must be expected. A low-strength steel was chosen to minimize potential problems associated with stress corrosion cracking. A series of measurements on stress corrosion cracking under the conditions as expected in the repository confirmed that the corrosion allowance of 50 mm used for the design of the reference overpack is sufficient over the 1000 years design lifetime. Tensile stresses are introduced by the welding process when the overpack is closed. For a multipass welding, the evolution of deformations, strains and stresses were determined in a finite-element calculation. Assuming an elastic-plastic material behavior without creep, the residual stresses are high; considering creep would reduce them. A series of creep tests revealed that the initial creep rate is important for cast steel already at 400deg C. (orig.)

Electrodeposited Reduced Graphene Oxide Films on Stainless Steel, Copper, and Aluminum for Corrosion Protection Enhancement

Directory of Open Access Journals (Sweden)

Abdulkareem Mohammed Ali Al-Sammarraie

2017-01-01

Full Text Available The enhancement of corrosion protection of metals and alloys by coating with simple, low cost, and highly adhered layer is still a main goal of many workers. In this research graphite flakes converted into graphene oxide using modified Hammers method and then reduced graphene oxide was electrodeposited on stainless steel 316, copper, and aluminum for corrosion protection application in seawater at four temperatures, namely, 20, 30, 40, and 50°C. All corrosion measurements, kinetics, and thermodynamics parameters were established from Tafel plots using three-electrode potentiostat. The deposited films were examined by FTIR, Raman, XRD, SEM, and AFM techniques; they revealed high percentages of conversion to the few layers of graphene with confirmed defects.

Corrosion of canister materials for radioactive waste disposal

Energy Technology Data Exchange (ETDEWEB)

Kienzler, Bernhard [KIT Karlsruhe (Germany). Institut fuer Nukleare Entsorgung (INE)

2017-08-15

In the period between 1980 and 2004, corrosion studies on various metallic materials have been performed at the Research Center Karlsruhe. The objectives of these experimental studies addressed mainly the performance of canister materials for heat producing, high-level wastes and spent nuclear fuels for a repository in a German salt dome. Additional studies covered the performance of steels for packaging wastes with negligible heat production under conditions to be expected in rocksalt and in the Konrad iron ore mine. The results of the investigations have been published in journals and conference proceedings but also in ''grey literature''. This paper presents a summary of the results of corrosion experiments with fine-grained steels and nodular cast steel.

Treatment of Uranium-Contaminated Concrete for Reducing Secondary Radioactive Waste

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung Soo; Han, G. S; Park, U. K; Kim, G. N.; Moon, J. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

A volume reduction of the concrete waste by appropriate treatment technologies will decrease the amount of waste to be disposed of and result in a reduction of the disposal cost and an enhancement of the efficiency of the disposal site. Our group has developed a decontamination process for uranium-contaminated (U-contaminated) concrete, and some experiments were performed to reduce the second radioactive waste. A decontamination process was developed to remove uranium from concrete waste. The yellow or brown colored surface of the wall brick with high concentration of uranium was removed by a chisel until the radioactivity of remaining block reached less than 1 Bq/g. The concrete waste coated with epoxy was directly burned by an oil flame, and the burned surface was then removed using the same method as the treatment of the brick. The selective mechanical removal of the concrete block reduced the amount of secondary radioactive waste. The concrete blocks without an epoxy were crushed to below 30 mm and sifted to 1 mm. When the concrete pieces larger than 1 mm were sequentially washed with a clear recycle solution and 1.0 M of nitric acid, their radioactivity reached below the limit value of uranium for self-disposal. For the concrete pieces smaller than 1 mm, a rotary washing machine and electrokinetic equipment were also used.

Treatment of Uranium-Contaminated Concrete for Reducing Secondary Radioactive Waste

International Nuclear Information System (INIS)

Kim, Seung Soo; Han, G. S; Park, U. K; Kim, G. N.; Moon, J. K.

2014-01-01

A volume reduction of the concrete waste by appropriate treatment technologies will decrease the amount of waste to be disposed of and result in a reduction of the disposal cost and an enhancement of the efficiency of the disposal site. Our group has developed a decontamination process for uranium-contaminated (U-contaminated) concrete, and some experiments were performed to reduce the second radioactive waste. A decontamination process was developed to remove uranium from concrete waste. The yellow or brown colored surface of the wall brick with high concentration of uranium was removed by a chisel until the radioactivity of remaining block reached less than 1 Bq/g. The concrete waste coated with epoxy was directly burned by an oil flame, and the burned surface was then removed using the same method as the treatment of the brick. The selective mechanical removal of the concrete block reduced the amount of secondary radioactive waste. The concrete blocks without an epoxy were crushed to below 30 mm and sifted to 1 mm. When the concrete pieces larger than 1 mm were sequentially washed with a clear recycle solution and 1.0 M of nitric acid, their radioactivity reached below the limit value of uranium for self-disposal. For the concrete pieces smaller than 1 mm, a rotary washing machine and electrokinetic equipment were also used

Corrosion behaviour of steel rebars embedded in a concrete designed for the construction of an intermediate-level radioactive waste disposal facility

Directory of Open Access Journals (Sweden)

Schulz F.M.

2013-07-01

Full Text Available The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on an instrumented reinforced concrete prototype specifically designed for this purpose, to study the behaviour of an intermediate level radioactive waste disposal facility from the rebar corrosion point of view. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

Localized Corrosion Behavior of Type 304SS with a Silica Layer Under Atmospheric Corrosion Environments

International Nuclear Information System (INIS)

E. Tada; G.S. Frankel

2006-01-01

The U.S. Department of Energy (DOE) has proposed a potential repository for spent nuclear fuel and high-level radioactive waste at the Yucca Mountain site in Nevada. [I] The temperature could be high on the waste packages, and it is possible that dripping water or humidity could interact with rock dust particulate to form a thin electrolyte layer with concentrated ionic species. Under these conditions, it is possible that highly corrosion-resistant alloys (CRAs) used as packages to dispose the nuclear waste could suffer localized corrosion. Therefore, to better understand long-term corrosion performance of CRAs in the repository, it is important to investigate localized corrosion under a simulated repository environment. We measured open circuit potential (OCP) and galvanic current (i g ) for silica-coated Type 304SS during drying of salt solutions under controlled RH environments to clarify the effect of silica layer as a dust layer simulant on localized corrosion under atmospheric environments. Type 304SS was used as a relatively susceptible model CRA instead of the much more corrosion resistant alloys, such as Alloy 22, that are being considered as, waste package materials

Activation of aluminum as an effective reducing agent by pitting corrosion for wet-chemical synthesis.

Science.gov (United States)

Li, Wei; Cochell, Thomas; Manthiram, Arumugam

2013-01-01

Metallic aluminum (Al) is of interest as a reducing agent because of its low standard reduction potential. However, its surface is invariably covered with a dense aluminum oxide film, which prevents its effective use as a reducing agent in wet-chemical synthesis. Pitting corrosion, known as an undesired reaction destroying Al and is enhanced by anions such as F⁻, Cl⁻, and Br⁻ in aqueous solutions, is applied here for the first time to activate Al as a reducing agent for wet-chemical synthesis of a diverse array of metals and alloys. Specifically, we demonstrate the synthesis of highly dispersed palladium nanoparticles on carbon black with stabilizers and the intermetallic Cu₂Sb/C, which are promising candidates, respectively, for fuel cell catalysts and lithium-ion battery anodes. Atomic hydrogen, an intermediate during the pitting corrosion of Al in protonic solvents (e.g., water and ethylene glycol), is validated as the actual reducing agent.

Contribution to the study of the role of sulfate-reducing bacteria in bio-corrosion phenomenon

International Nuclear Information System (INIS)

Chatelus, C.

1987-11-01

By their metabolic activities of hydrogen consumption and of sulfides production, the sulfate-reducing bacteria are the main bacteria responsible of the metallic corrosion phenomena in the absence of oxygen. A physiological and enzymatic study of some Desulfovibrio has contributed to the understanding of the role of these bacteria in the anaerobic bio-corrosion phenomena. Desulfovibrio (D.) vulgaris in organic medium, after having oxidized the lactate, consumes the hydrogen formed by the electrochemical reaction of iron dissolution. The Desulfovibrio can be responsible either of a corrosion by a direct contact with the metal in using the H 2 layer formed at its surface, (bacteria are then adsorbed at the surface because of an iron sulfide crystalline lattice), or of a distant corrosion in consuming the dissolved or gaseous hydrogen. As their hydrogenases can be stable in time independently of the cellular structure (D. vulparis) and active at high temperatures (to 70 C - 75 C) (D. baculatus), these bacteria can act in conditions incompatible with the viability of cells but compatible with the enzymatic expression. A study in terms of temperature has shown that inside the mesophilic group of the Desulfovibrio, the behaviour towards this parameter is specific to each bacteria, that accounts for the permanent presence of the representatives of this population in sites where the temperature variations are important. A change of some degrees Celsius can induce modifications in the yields of bacteria growth and by a consequence in variations in the corrosion intensity. Moreover, sulfate D. multispirans can reduce with specific velocities of different growth, the nitrate, the nitrite and the fumarate. Some sulfato-reducing could then adapt themselves to the variations of concentrations in electron acceptors and metabolize the oxidized substances used as biocides too. The choice of an electron acceptor rather than another do not depend uniquely of the specificity of the

The influence of introduced micro-organisms on corrosion of repository construction materials

International Nuclear Information System (INIS)

West, J.M.

1985-01-01

The work described in this report forms part of a wider project on the role of geomicrobiology in radioactive waste containment. This has established the presence of microbes in relevant geological formations including several groups of significance to waste containment. Microbial groups demonstrated have included those which could influence deterioration of repository structural materials, eg. sulphate reducing bacteria (SRB). This report describes work carried out to assess this role. More specifically the objectives of this phase of the project are: identification of suitable microbial isolates; to ascertain the growth characteristics of the isolates; to develop and construct experimental cells for use in corrosion rate tests; and to conduct preliminary short term experiments in static conditions designed to assess corrosion rates of mild steel in an ideal growth environment for SRB. Using information gained from these experiments to initiate long term corrosion experiments of steel in an SRB inoculated bentonite simulating near-field conditions in a backfill/canister system. (author)

Annual Report, Fall 2016: Alternative Chemical Cleaning of Radioactive High Level Waste Tanks - Corrosion Test Results

International Nuclear Information System (INIS)

Wyrwas, R. B.

2016-01-01

The testing presented in this report is in support of the investigation of the Alternative Chemical Cleaning program to aid in developing strategies and technologies to chemically clean radioactive High Level Waste tanks prior to tank closure. The data and conclusions presented here were the examination of the corrosion rates of A285 carbon steel and 304L stainless steel exposed to two proposed chemical cleaning solutions: acidic permanganate (0.18 M nitric acid and 0.05M sodium permanganate) and caustic permanganate. (10 M sodium hydroxide and 0.05M sodium permanganate). These solutions have been proposed as a chemical cleaning solution for the retrieval of actinides in the sludge in the waste tanks, and were tested with both HM and PUREX sludge simulants at a 20:1 ratio.

Annual Report, Fall 2016: Alternative Chemical Cleaning of Radioactive High Level Waste Tanks - Corrosion Test Results

Energy Technology Data Exchange (ETDEWEB)

Wyrwas, R. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-09-01

The testing presented in this report is in support of the investigation of the Alternative Chemical Cleaning program to aid in developing strategies and technologies to chemically clean radioactive High Level Waste tanks prior to tank closure. The data and conclusions presented here were the examination of the corrosion rates of A285 carbon steel and 304L stainless steel exposed to two proposed chemical cleaning solutions: acidic permanganate (0.18 M nitric acid and 0.05M sodium permanganate) and caustic permanganate. (10 M sodium hydroxide and 0.05M sodium permanganate). These solutions have been proposed as a chemical cleaning solution for the retrieval of actinides in the sludge in the waste tanks, and were tested with both HM and PUREX sludge simulants at a 20:1 ratio.

Mobile evaporator corrosion test results

International Nuclear Information System (INIS)

Rozeveld, A.; Chamberlain, D.B.

1997-05-01

Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80 degrees C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either open-quotes satisfactoryclose quotes (2-20 mpy) or open-quotes excellentclose quotes (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment

Development of Advanced In-Situ Techniques for Chemistry Monitoring and Corrosion Mitigation in SCWO Environments

International Nuclear Information System (INIS)

Macdonald, D. D.; Lvov, S. N.

2000-01-01

This project is developing sensing technologies and corrosion monitoring techniques for use in super critical water oxidation (SCWO) systems to reduce the volume of mixed low-level nuclear waste by oxidizing organic components in a closed cycle system where CO2 and other gaseous oxides are produced, leaving the radioactive elements concentrated in ash. The technique uses water at supercritical temperatures under highly oxidized conditions by maintaining a high fugacity of molecular oxygen in the system, which causes high corrosion rates of even the most corrosive resistant reactor materials. This project significantly addresses the high corrosion shortcoming through development of (a) advanced electrodes and sensors for in situ potentiometric monitoring of pH in high subcritical and supercritical aqueous solutions, (b) an approach for evaluating the association constants for 1-1 aqueous electrolytes using a flow-through electrochemical thermocell; (c) an electrochemical noise sensor for the in situ measurement of corrosion rate in subcritical and supercritical aqueous systems; (d) a model for estimating the effect of pressure on reaction rates, including corrosion reactions, in high subcritical and supercritical aqueous systems. The project achieved all objectives, except for installing some of the sensors into a fully operating SCWO system

Development of Advanced In-Situ Techniques for Chemistry Monitoring and Corrosion Mitigation in SCWO Environments

Energy Technology Data Exchange (ETDEWEB)

Macdonald, D. D.; Lvov, S. N.

2000-03-31

This project is developing sensing technologies and corrosion monitoring techniques for use in super critical water oxidation (SCWO) systems to reduce the volume of mixed low-level nuclear waste by oxidizing organic components in a closed cycle system where CO2 and other gaseous oxides are produced, leaving the radioactive elements concentrated in ash. The technique uses water at supercritical temperatures under highly oxidized conditions by maintaining a high fugacity of molecular oxygen in the system, which causes high corrosion rates of even the most corrosive resistant reactor materials. This project significantly addresses the high corrosion shortcoming through development of (a) advanced electrodes and sensors for in situ potentiometric monitoring of pH in high subcritical and supercritical aqueous solutions, (b) an approach for evaluating the association constants for 1-1 aqueous electrolytes using a flow-through electrochemical thermocell; (c) an electrochemical noise sensor for the in situ measurement of corrosion rate in subcritical and supercritical aqueous systems; (d) a model for estimating the effect of pressure on reaction rates, including corrosion reactions, in high subcritical and supercritical aqueous systems. The project achieved all objectives, except for installing some of the sensors into a fully operating SCWO system.

Released radioactivity reducing facility

International Nuclear Information System (INIS)

Tanaka, Takeaki.

1992-01-01

Upon occurrence of a reactor accident, penetration portions of a reactor container, as a main leakage source from a reactor container, are surrounded by a plurality of gas-tight chambers, the outside of which is surrounded by highly gas-tightly buildings. Branched pipelines of an emergency gas processing system are introduced to each of the gas-tight chambers and they are joined and in communication with an emergency gas processing device. With such a constitution, radioactive materials are prevented from leaking directly from the buildings. Further, pipeline openings of the emergency gas processing facility are disposed in the plurality highly gas-tight penetration chambers. If the radioactive materials are leaked from the reactor to elevate the pressure in the penetration chambers, the radioactive materials are introduced to a filter device in the emergency gas processing facility by way of the branched pipelines, filtered and then released to the atmosphere. Accordingly, the reliability and safety of the system can be improved. (T.M.)

Conditioning of radioactive aluminium generated by the VVR-S Nuclear Reactor Decommissioning Laboratory Inactive Tests

International Nuclear Information System (INIS)

Nicu, M.; Ionascu, L.; Turcau, C.; Dragolici, F.; Rotarescu, G.

2015-01-01

Aluminium is a reactive amphoteric metal, readily forming a protective oxide layer on contact with air or water. However, as the oxides are amphoteric, aluminium is not resistant to corrosion in acidic and alkaline conditions, because the protective films dissolve. As a consequence radioactive waste containing bulk aluminium alloys can not be embedded in Ordinary Portland Cement (OPC). A potential encapsulating material for the radioactive aluminium is potassium magnesium phosphate (MKP). This paper presents the characterization results obtained from analyzing the potential magnesium phosphate formulations and assesses its potential to reduce the corrosion of aluminium. A series of experiments have been performed. The main conclusions of the paper are as follows. First, the pH values of magnesium phosphate formulation investigated increased gradually over the test duration, with pH measurement ranging from 8.1 - 9.1, indicating lower values compared with the reference composite OPC (pH ∼ 13). The reduction of pH is an important controlling factor for the corrosion of aluminium. Secondly, according to XRD, the hardened magnesium phosphate matrix is polycrystalline and the main reaction product of magnesium phosphate cement formulations was confirmed as MgKPO 4 -6H 2 O, which was found to dominate the crystalline phase composition. Thirdly, the compressive strengths obtained for magnesium phosphate matrices investigated are included in the accepted limits for the embedding matrix with cement (above 5 N/mm 2 ). And fourthly, the corrosion of metallic aluminium in magnesium phosphate matrix is markedly reduced in comparison with the composite OPC

Hot-wall corrosion testing of simulated high level nuclear waste

International Nuclear Information System (INIS)

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

1995-01-01

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

The corrosion behavior of iron and aluminum under waste disposal conditions

International Nuclear Information System (INIS)

Fujisawa, R.; Cho, T.; Sugahara, K.; Takizawa, Y.; Hironaga, M.

1997-01-01

The generation of hydrogen gas from metallic waste in corrosive disposal environment is an important issue for the safety analysis of low-level radioactive waste disposal facilities in Japan. In particular iron and aluminum are the possibly important elements regarding the gas generation. However, the corrosion behavior of these metals has not been sufficiently investigated under the highly alkaline non-oxidizing disposal conditions yet. The authors studied the corrosion behavior of iron and aluminum under simulated disposal environments. The quantity of hydrogen gas generated from iron was measured in a closed cell under highly alkaline non-oxidizing conditions. The observed corrosion rate of iron in the initial period of immersion was 4 nm/year at 15 C, 20 nm/year at 30 C, and 200 nm/year at 45 C. The activation energy was found to be 100 kJ/mol from Arrhenius plotting of the above corrosion rates. The corrosion behavior of aluminum was studied under an environment simulating conditions in which aluminum was solidified with mortar. In the initial period aluminum corroded rapidly with a corrosion rate of 20 mm/year. However, the corrosion rate decreased with time, and after 1,000 hours the rate reached 0.001 to 0.01 mm/year. Thus the authors obtained data on hydrogen gas generation from iron and aluminum under the disposal environment relevant to the safety analysis of low-level radioactive disposal facilities in Japan

A critical review of measures to reduce radioactive doses from drinking water and consumption of freshwater foodstuffs

International Nuclear Information System (INIS)

Smith, J.T.; Voitsekhovitch, O.V.; Haakanson, L.; Hilton, J.

2001-01-01

Following a radioactive fallout event, there are a number of possible intervention measures to reduce radioactive doses to the public via the surface water pathway. We have critically reviewed the options available to decision-makers in the event of radioactive contamination of surface waters. We believe that the most effective and viable measures to reduce radioactivity in drinking water are those which operate at the water treatment and distribution stage. Intervention measures to reduce concentrations of radioactivity in rivers and reservoirs are expected to be much less viable and efficient at reducing doses via the drinking water pathway. Bans on consumption of freshwater fish can be effective, but there are few viable measures to reduce radioactivity in fish prior to the preparation stage. Lake liming and biomanipulation have been found to be ineffective for radiocaesium, although the addition of potassium to lakewaters appears promising in some situations. Lake liming may be effective in reducing radiostrontium in fish, though this has not, to our knowledge, been tested. De-boning fish contaminated by strontium is probably the most effective food preparation measure, but salting and freezing can also reduce radiocaesium concentrations in fish. The provision of accurate information to the public is highlighted as a key element of countermeasure implementation

Research activities at nuclear research institute in water chemistry and corrosion

International Nuclear Information System (INIS)

Kysela, Jan

2000-01-01

Research activities at Nuclear Research Institute Rez (NRI) are presented. They are based on former heavy water reactor program and now on pressurized reactors VVER types which are operated on Czech republic. There is LVR-15 research reactor operated in NRI. The reactor and its experimental facilities is utilized for water chemistry and corrosion studies. NRI services for power plants involve water chemistry optimalization, radioactivity build-up, fuel corrosion and structural materials corrosion tests. (author)

Radiation-induced corrosion of stellite-6

International Nuclear Information System (INIS)

Behazin, M.; Wren, J.C.

2012-09-01

Stellite-6 is a Co-based (58%) alloy that is used for components that require high wear-resistance, such as valve facings and ball bearings in nuclear reactors. In the reactor core, stable 59 Co can be neutron activated by absorption of a neutron to become the radioactive isotope, 60 Co. The 60 Co that is created constitutes a safety hazard for plant workers who have to perform maintenance on the reactor. One of the operational and safety issues in a nuclear reactor is the potential corrosion of Co-based alloys and the introduction of dissolved Co ions into the reactor core. While the corrosion of Stellite-6 has been studied its corrosion behaviour with ionizing radiation present has not been well established. Corrosion kinetics depend on both the aqueous redox conditions and the physical and chemical nature of the alloy surface. The high radiation fields present in a reactor core will cause water to decompose to a range of redox-active species (both highly oxidizing (e.g., ·OH, H 2 O 2 ) and highly reducing (e.g., ·eaq - , ·O 2 - )). These species can significantly influence corrosion kinetics. The effect of γ-radiation on the corrosion of Stellite-6 at pH 10.6 was investigated at temperatures ≤ 150 deg. C. Since the corrosion rate depends strongly on the type of oxide that is present on the material surface, the focus of this corrosion study was to establish the mechanism by which radiolysis affects the nature of the oxide that is present on Stellite-6. The results show that γ-radiation (at a dose rate of 5.5 kGy.h -1 ) increases the corrosion potential on Stellite-6 from -0.7 VSCE to 0.12 VSCE . The corrosion potential without irradiation present is in a potential range where oxidation is limited to the formation of a Co (OH) 2 and CoCr 2 O 4 outer oxide layer on a pre-existing Cr 2 O 3 film. The corrosion potential with irradiation is in a potential range where further oxidation of Co (OH) 2 to CoOOH also occurs. However, since CoOOH is less soluble than

Physical-chemical model for the mechanism of glass corrosion with particular consideration of simulated radioactive waste glasses

International Nuclear Information System (INIS)

Grambow, B.

1985-01-01

A physical-chemical model for the mechanism of glass corrosion is described. This model can be used for predicting, interpreting, and extrapolating experimental results. In static leaching tests the rate of corrosion generally decreases with time. Some authors assume that the surface layer, which grows during the course of the reaction, protects the underlying glass from further attack by the aqueous phase. Other authors assume that the saturation effects in solution are responsible for reducing the rate of the reaction. It is demonstrated within the scope of this work that examples can be found for both concepts; however, transport processes in the surface layer and/or in solution can be excluded as rate-determining processes within a majority of the examined cases. The location of the corrosion reaction is the boundary surface between the surface layer and the not yet attacked glass (transition zone)

Corrosion behavior of Si-enriched steels for nuclear applications in liquid lead–bismuth

Energy Technology Data Exchange (ETDEWEB)

Kurata, Yuji, E-mail: kurata.yuji@jaea.go.jp [Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken 319-1195 (Japan)

2013-06-15

Highlights: ► The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied. ► The corrosion tests were conducted at the two controlled oxygen levels. ► The Si addition reduces the scale thickness under the high oxygen condition. ► The Si addition has no significant effect under the low oxygen condition. -- Abstract: The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied in order to develop accelerator driven systems for transmutation of long-lived radioactive wastes and lead–bismuth cooled fast reactors. The corrosion tests of 316SS, Si-enriched 316SS, Mod.9Cr–1Mo steel (T91) and Si-enriched T91 were conducted at 550 °C in liquid lead–bismuth at the two controlled oxygen levels. Both the additions of 2.5 wt.% Si to 316SS and 1.5 wt.% Si to T91 had the effect of reducing the thickness of oxide layer in liquid lead–bismuth at the high oxygen concentration (2.5 × 10{sup −5} wt.%). Although the Si addition to 316SS reduced the depth of ferritization caused by Ni dissolution in liquid lead–bismuth at the low oxygen concentration (4.4 × 10{sup −8} wt.%), it could not suppress the ferritization and the penetration of Pb and Bi completely. The Si addition to T91 did not have the effect of preventing the penetration of Pb and Bi in the liquid lead–bismuth at the low oxygen concentration. The oxide scales formed on both Si-enriched steels did not have sufficient corrosion resistance under the low oxygen condition.

Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

International Nuclear Information System (INIS)

Bickford, D.F.; Congdon, J.W.; Oblath, S.B.

1986-12-01

At the US Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assess the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition. Transition metal hydroxide sludge contains strong passivating species for carbon steel. Washed precipitate contains organic species that lower solution pH and tend to reduce passivating films, requiring higher inhibitor concentrations than the 0.01 molar nitrite required for reactor fuel reprocessing wastes. Periodic agitation, to keep the organic phase suspended, or cathodic protection are possible alternatives to higher nitrite inhibitor concentrations

Research of radioactive waste storage cask/canister materials, spent nuclear fuels and various radioactive waste forms and development of their assessment methods. Final report for Stage 3

International Nuclear Information System (INIS)

Dobrev, D.; Balek, V.; Červinka, R.; Večerník, P.; Člupek, M.; Kouřil, M.; Novák, P.; Stoulil, J.; Silber, R.

2013-08-01

The main topics treated are: Research and development of methodologies for canister/cask material degradation assessment; Laboratory research of selected materials of canister/cask with radioactive waste; and Research and assessment of canister/cask materials in natural granite rocks. Two additional documents are appended: Corrosion rate determination for samples in compacted bentonite in anaerobic conditions (methodology), and Roll test for corrosion test in an occluded solution at the interface between a radioactive waste disposal canister and the bentonite cover. (P.A.)

Corrosion behavior of the aluminum under the simulated environmental condition of low-level waste. Part 1. Effect of dry storage on the corrosion behavior of pre-filmed specimen

International Nuclear Information System (INIS)

Fujiwara, Kazutoshi; Tani, Junichi; Tanaka, Yukihisa

2016-01-01

Aluminum alloy remains in the Low-level Radioactive Waste (LLW) generated at nuclear facilities. It is well known that aluminum reactors to the alkaline component of cement, or water, generating hydrogen gas. For the saft management of radioactive waste disposal facilities, it is necessary to evaluate the corrosion behavior of aluminum and the hydrogen generation behavior in consideration with transition of the burial environment. In the present study, the corrosion behaviors of aluminum in the alkaline solutions at 15degC were evaluated. Pure aluminium was used as specimen. The test solutions used in this study were water in equilibrium with the cement paste grain produced from ordinary portland cement (OPC). The temperature and pH of solutions were 15degC and 11.5-12.5, respectively. In order to make a corrosion product on the surface, the specimens were immersed in the solution for about 3000 hours as pretreatment. The corrosion behaviors of pre-filmed specimen were evaluated after drying. The test results shows that the maximum in a corrosion rate appeared in early stages and it decrease to less than 1x10 -3 mm/y. The maximum did not appear when the corrosion products were formed in the OPC grain as conditions similar to actual environment. (author)

Remote measurement of corrosion using ultrasonic techniques

International Nuclear Information System (INIS)

Garcia, K.M.; Porter, A.M.

1995-02-01

Supercritical water oxidation (SCWO) technology has the potential of meeting the US Department of Energy's treatment requirements for mixed radioactive waste. A major technical constraint of the SCWO process is corrosion. Safe operation of a pilot plant requires monitoring of the corrosion rate of the materials of construction. A method is needed for measurement of the corrosion rate taking place during operation. One approach is to directly measure the change in wall thickness or growth of oxide layer at critical points in the SCWO process. In FY-93, a brief survey of the industry was performed to evaluate nondestructive evaluation (NDE) methods for remote corrosion monitoring in supercritical vessels. As a result of this survey, it was determined that ultrasonic testing (UT) methods would be the most cost-effective and suitable method of achieving this. Therefore, the objective for FY-94 was to prove the feasibility of using UT to monitor corrosion of supercritical vessels remotely during operation without removal of the insulation

Experiments and models of general corrosion and flow-assisted corrosion of materials in nuclear reactor environments

Science.gov (United States)

Cook, William Gordon

Corrosion and material degradation issues are of concern to all industries. However, the nuclear power industry must conform to more stringent construction, fabrication and operational guidelines due to the perceived additional risk of operating with radioactive components. Thus corrosion and material integrity are of considerable concern for the operators of nuclear power plants and the bodies that govern their operations. In order to keep corrosion low and maintain adequate material integrity, knowledge of the processes that govern the material's breakdown and failure in a given environment are essential. The work presented here details the current understanding of the general corrosion of stainless steel and carbon steel in nuclear reactor primary heat transport systems (PHTS) and examines the mechanisms and possible mitigation techniques for flow-assisted corrosion (FAC) in CANDU outlet feeder pipes. Mechanistic models have been developed based on first principles and a 'solution-pores' mechanism of metal corrosion. The models predict corrosion rates and material transport in the PHTS of a pressurized water reactor (PWR) and the influence of electrochemistry on the corrosion and flow-assisted corrosion of carbon steel in the CANDU outlet feeders. In-situ probes, based on an electrical resistance technique, were developed to measure the real-time corrosion rate of reactor materials in high-temperature water. The probes were used to evaluate the effects of coolant pH and flow on FAC of carbon steel as well as demonstrate of the use of titanium dioxide as a coolant additive to mitigated FAC in CANDU outlet feeder pipes.

Corrosion resistance testing of high-boron-content stainless steels

International Nuclear Information System (INIS)

Petrman, I.; Safek, V.

1994-01-01

Boron steels, i.e. stainless steels with boron contents of 0.2 to 2.25 wt.%, are employed in nuclear engineering for the manufacture of baskets or wells in which radioactive fissile materials are stored, mostly spent nuclear fuel elements. The resistance of such steels to intergranular corrosion and uniform corrosion was examined in the Strauss solution and in boric acid; the dependence of the corrosion rate of the steels on their chemical composition was investigated, and their resistance was compared with that of AISI 304 type steel. Corrosion resistance tests in actual conditions of ''wet'' compact storage (demineralized water or a weak boric acid solution) gave evidence that boron steels undergo nearly no uniform corrosion and, as electrochemical measurements indicated, match standard corrosion-resistant steels. Corrosion resistance was confirmed to decrease slightly with increasing boron content and to increase somewhat with increasing molybdenum content. (Z.S.). 3 tabs., 4 figs., 7 refs

Microbial Corrosion of API 5L X-70 Carbon Steel by ATCC 7757 and Consortium of Sulfate-Reducing Bacteria

OpenAIRE

Abdullah, Arman; Yahaya, Nordin; Md Noor, Norhazilan; Mohd Rasol, Rosilawati

2014-01-01

Various cases of accidents involving microbiology influenced corrosion (MIC) were reported by the oil and gas industry. Sulfate reducing bacteria (SRB) have always been linked to MIC mechanisms as one of the major causes of localized corrosion problems. In this study, SRB colonies were isolated from the soil in suspected areas near the natural gas transmission pipeline in Malaysia. The effects of ATCC 7757 and consortium of isolated SRB upon corrosion on API 5L X-70 carbon steel coupon were i...

Iron/argillite interactions in radioactive waste disposal context: Oxidising transient and bacterial activities influence

International Nuclear Information System (INIS)

Chautard, Camille; Dauzeres, Alexandre; Maillet, Anais

2014-01-01

The design of a high-level radioactive waste (HLW) disposal facility developed by Andra (2005) in France involves emplacing metallic materials (containers, overpacks, liner) into a geological argillaceous formation. During the operational phase, ventilation of handling drifts will keep oxidising conditions at the front of disposal tunnels. Therefore, an oxidising transient may take place in parts of these tunnels in the post-closure phase possibly over several years. During this transient period, the environment of the disposal cell will evolve towards reducing and saturated conditions close to the equilibrium state of the original underground argillaceous formation. Moreover, high temperature conditions above 50 deg. C may be encountered in this environment over a few hundred years. Uniform corrosion represents the main type of degradation of metallic materials for the long term. The oxidising transient will be characterised by high corrosion rates (e.g. localised corrosion) due to the presence of oxygen whereas during the following anoxic stage, the main alteration factor will originate from the pore water associated with lower corrosion rates. In any case, metallic materials corrosion will lead to the release of aqueous iron, which may induce alteration of the favourable confining properties of the clayey materials. In this context, reactive pathways related to the metal corrosion under oxidising conditions and then followed by reducing conditions remain to be further understood (evolution of pH, redox and influence of temperature). Furthermore, some other significant issues remain open, in particular the dissolution/precipitation processes, the argillite perturbation extent and the effects of these transformations on the confining properties of materials. The presence of micro-organisms in deep argillaceous environment and the introduction of new bacterial species in the repository during the operational phase raise the question of their survival under real

Transport of radioactive corrosion products in primary system of sodium-cooled fast breeder reactor 'MONJU'

International Nuclear Information System (INIS)

Matuo, Youichirou; Hasegawa, Masanori; Maegawa, Yoshiharu; Miyahara, Shinya

2011-01-01

Radioactive corrosion products (CP) are primary cause of personal radiation exposure during maintenance work at FBR plants with no breached fuel. The PSYCHE code has been developed based on the Solution-Precipitation model for analysis of CP transfer behavior. We predicted and analyzed the CP solution and precipitation behavior of MONJU to evaluate the applicability of the PSYCHE code to MONJU, using the parameters verified in the calculations for JOYO. From the calculation result pertaining to the MONJU system, distribution of 54 Mn deposited in the primary cooling system over 20 years of operation is predicted to be approximately 7 times larger than that of 60 Co. In particular, predictions show a notable tendency for 54 Mn precipitation to be distributed in the primary pump and cold-leg. The calculated distribution of 54 Mn and 60 Co in the primary cooling system of MONJU agreed with tendencies of measured distribution of JOYO. (author)

Protecting solar collector systems from corrosion

Energy Technology Data Exchange (ETDEWEB)

1978-01-01

The main cause of the reduced life of a solar heating system is corrosion of the exterior parts and the internal components. This report outlines ways of reducing the cost of solar heating by reducing the corrosion in solar heating systems, and hence increasing the system's service life. Mechanisms for corrosion are discussed: these include galvanic corrosion and crevice corrosion. Means of minimizing corrosion at the design stage are then described. Such methods, when designing the solar collector, involve ensuring proper drainage of exterior water; eliminating situations where moisture, dirt and pollutants may collect; preventing condensation inside the collector; using proper gaskets and sealants at appropriate places; and selecting optimum materials and coatings. Interior corrosion can be minimized at the design stage by choosing a good heat transfer fluid and corrosion inhibitor, in the case of systems where liquids are used; ensuring a low enough flow rate to avoid erosion; designing the system to avoid crevices; and avoiding situations where galvanic corrosion could occur. Other procedures are given for minimizing corrosion in the construction and operation of solar heating systems. 7 figs., 7 tabs.

Modeling pitting corrosion damage of high-level radioactive-waste containers, with emphasis on the stochastic approach

Energy Technology Data Exchange (ETDEWEB)

Henshall, G.A.; Halsey, W.G.; Clarke, W.L.; McCright, R.D.

1993-01-01

Recent efforts to identify methods of modeling pitting corrosion damage of high-level radioactive-waste containers are described. The need to develop models that can provide information useful to higher level system performance assessment models is emphasized, and examples of how this could be accomplished are described. Work to date has focused upon physically-based phenomenological stochastic models of pit initiation and growth. These models may provide a way to distill information from mechanistic theories in a way that provides the necessary information to the less detailed performance assessment models. Monte Carlo implementations of the stochastic theory have resulted in simulations that are, at least qualitatively, consistent with a wide variety of experimental data. The effects of environment on pitting corrosion have been included in the model using a set of simple phenomenological equations relating the parameters of the stochastic model to key environmental variables. The results suggest that stochastic models might be useful for extrapolating accelerated test data and for predicting the effects of changes in the environment on pit initiation and growth. Preliminary ideas for integrating pitting models with performance assessment models are discussed. These ideas include improving the concept of container ``failure``, and the use of ``rules-of-thumb`` to take information from the detailed process models and provide it to the higher level system and subsystem models. Finally, directions for future work are described, with emphasis on additional experimental work since it is an integral part of the modeling process.

Modeling pitting corrosion damage of high-level radioactive-waste containers, with emphasis on the stochastic approach

International Nuclear Information System (INIS)

Henshall, G.A.; Halsey, W.G.; Clarke, W.L.; McCright, R.D.

1993-01-01

Recent efforts to identify methods of modeling pitting corrosion damage of high-level radioactive-waste containers are described. The need to develop models that can provide information useful to higher level system performance assessment models is emphasized, and examples of how this could be accomplished are described. Work to date has focused upon physically-based phenomenological stochastic models of pit initiation and growth. These models may provide a way to distill information from mechanistic theories in a way that provides the necessary information to the less detailed performance assessment models. Monte Carlo implementations of the stochastic theory have resulted in simulations that are, at least qualitatively, consistent with a wide variety of experimental data. The effects of environment on pitting corrosion have been included in the model using a set of simple phenomenological equations relating the parameters of the stochastic model to key environmental variables. The results suggest that stochastic models might be useful for extrapolating accelerated test data and for predicting the effects of changes in the environment on pit initiation and growth. Preliminary ideas for integrating pitting models with performance assessment models are discussed. These ideas include improving the concept of container ''failure'', and the use of ''rules-of-thumb'' to take information from the detailed process models and provide it to the higher level system and subsystem models. Finally, directions for future work are described, with emphasis on additional experimental work since it is an integral part of the modeling process

Corrosion susceptibility of steel drums to be used as containers for intermediate level nuclear waste

Science.gov (United States)

Farina, S.; Schulz Rodriguez, F.; Duffó, G.

2013-07-01

The present work is a study of the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins contaminated with different types and concentrations of aggressive species. A special type of specimen was manufactured to simulate the cemented ion-exchange resins in the drum. The evolution of the corrosion potential and the corrosion rate of the steel, as well as the electrical resistivity of the matrix were monitored over a time period of 900 days. The aggressive species studied were chloride ions (the main ionic species of concern) and sulphate ions (produced during radiolysis of the cationic exchange-resins after cementation). The work was complemented with an analysis of the corrosion products formed on the steel in each condition, as well as the morphology of the corrosion products. When applying the results obtained in the present work to estimate the corrosion depth of the steel drumscontaining the cemented radioactive waste after a period of 300 years (foreseen durability of the Intermediate Level Radioactive Waste facility in Argentina) , it is found that in the most unfavourable case (high chloride contamination), the corrosion penetration will be considerably lower than the thickness of the wall of the steel drums.

Microbiologically induced corrosion

International Nuclear Information System (INIS)

Stein, A.A.

1988-01-01

Biological attack is a problem that can affect all metallic materials in a variety of environments and systems. In the power industry, corrosion studies have focused on condensers and service water systems where slime, barnacles, clams, and other macro-organisms are easily detected. Efforts have been made to eliminate the effect of these organisms through the use of chlorination, backflushing, organic coating, or thermal shock. The objective is to maintain component performance by eliminating biofouling and reducing metallic corrosion. Recently, corrosion of power plant components by micro-organisms (bacteria) has been identified even in very clean systems. A system's first exposure to microbiologically induced corrosion (MIC) occurs during its first exposure to an aqueous environment, such as during hydrotest or wet layup. Corrosion of buried pipelines by sulfate-reducing bacteria has been studied by the petrochemical industry for years. This paper discusses various methods of diagnosing, monitoring, and controlling MIC in a variety of systems, as well as indicates areas where further study is needed

Corrosion and failure processes in high-level waste tanks

International Nuclear Information System (INIS)

Mahidhara, R.K.; Elleman, T.S.; Murty, K.L.

1992-11-01

A large amount of radioactive waste has been stored safely at the Savannah River and Hanford sites over the past 46 years. The aim of this report is to review the experimental corrosion studies at Savannah River and Hanford with the intention of identifying the types and rates of corrosion encountered and indicate how these data contribute to tank failure predictions. The compositions of the High-Level Wastes, mild steels used in the construction of the waste tanks and degradation-modes particularly stress corrosion cracking and pitting are discussed. Current concerns at the Hanford Site are highlighted

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

Electrochemical impedance spectroscopy and Surface Studies of Steel Corrosion by Sulphate-Reducing Bacteria

International Nuclear Information System (INIS)

Fathul Karim Sahrani; Zaharah Ibrahim; Madzlan Aziz; Adibah Yahya

2009-01-01

Sulphate-reducing bacteria (SRB), implicated in microbiologically influenced corrosion were isolated from the deep subsurface at the vicinity of Pasir Gudang, Johor, Malaysia. Electrochemical impedance spectroscopic (EIS) study was carried out to determine the polarization resistance in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 and SRB2 and without SRBs inoculated (control). EIS results showed that in the presence of SRB1, SRB2 and mixed culture SRB1 and SRB2, polarisation resistance values were 7170, 6370 and 7190 ohms respectively compared to that of control, 92400 ohm. X-ray analysis (EDS) of the specimens indicated high sulphur content in the medium containing SRBs. Localized corrosion was observed on the metal surface which was associated with the SRB activity. (author)

Corrosion study of the graphene oxide and reduced graphene oxide-based epoxy coatings

Science.gov (United States)

Ghauri, Faizan Ali; Raza, Mohsin Ali; Saad Baig, Muhammad; Ibrahim, Shoaib

2017-12-01

This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers’ method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

Science.gov (United States)

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-03-01

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Performace Of Multi-Probe Corrosion Monitoring Systems At The Hanford Site

International Nuclear Information System (INIS)

Carothers, K.D.; Boomer, K.D.; Anda, V.S.; Dahl, M.M.; Edgemon, G.L.

2010-01-01

Between 2007 and 2009, several different multi-probe corrosion monitoring systems were designed and installed in high-level nuclear waste tanks at the U.S. Department of Energy's Hanford Site in WaShington State. The probe systems are being monitored to ensure waste tanks operate in regions that minimize localized corrosion (i.e., pitting) and stress corrosion cracking. The corrosion monitoring systems have been installed in wastes with different chemistry types. An ongoing effort during the same time period has generated non-radioactive simulants that are tested in the laboratory to establish baseline corrosion monitoring system performance and characterize data to allow interpretation of readings from the multiple corrosion monitoring systems. Data collection from these monitoring systems has reached the point where the results allow comparison with the laboratory testing. This paper presents analytical results from the corrosion monitoring system development program.

Analysis of corrosion product transport in PWR primary system under non-convective condition

International Nuclear Information System (INIS)

Han, Byoung Sub

1992-02-01

The increase of occupational radiation exposure (ORE) due to the increase of the operational period at existing nuclear power plant and also the publication of the new version of ICRP recommendation (ICRP publication No. 60) for radiological protection require much more strict reduction of radiation buildup in the nuclear power plant. The major sources of the radiation, i.e. the radioactive corrosion-products, are generated by the neutron activation of the corrosion products at the reactor core, and then the radioactive corrosion products are transported to the outside of the core, and accumulated near the steam generator side at PWR. Major radioactive corrosion-products of interest in PWR are Cr 51 ,: Mn 54 ,: Co 58 ,: Fe 59 and Co 60 . Among them Co 58 and Co 60 are known to contribute approximately more than 70% of the total ORE. Thus our main concerns are focused on predicting the transport and deposition of the Co radionuclides and suggesting the optimizing method which can minimize and control the ORE of the nuclear power plant. It is well known that Co-source is most effectively controlled by pH-solubility radiation control, and also some complex computer codes such as CORA and PACTOLE have been developed and revised to predict the corrosion product behavior. However these codes still imply some intrisic problems in simulating the real behavior of corrosion products in the reactor because of 1) the lack of important experimental data, coefficients and parameters of the transport and reactions under actual high temperature and pressure conditions, 2) no general theoretical modelling which can describe such many different mechanisms involved in the corrosion product movements, 3) the newly developed and measured behavior of the corrosion product transport mechanism. Since no sufficient and detailed information is available from the above-mentioned codes (also due to propriority problems), we concentrate on developing a new computer code, CP-TRAN (Corrosion

Electrochemistry study of the influence of local hydrogen generation in carbon steel bio-corrosion mechanisms in presence of iron reducing bacteria (Shewanella oneidensis)

International Nuclear Information System (INIS)

Moreira, R.; Libert, M.; Tribollet, B.; Vivier, V.

2012-01-01

Document available in extended abstract form only. The safe disposal of nuclear waste is a major concern for the nuclear energy industry. The high-level long-lived waste (HLNW) should be maintained for millions of years in clay formations at 500 metres depth in order to prevent the migration of radionuclides. Thence, different kinds of materials such as, carbon steel, stainless steel, concrete, clay, etc., are chosen aiming to last as long as possible and to preserve the radioactivity properties. In contrast, the anoxic corrosion of the different metallic envelopes is an expected phenomenon due to the changes on the environmental conditions (such as re-saturation) within HLNW repositories. In this context, corrosion products like iron oxides (i.e. magnetite, Fe 3 O 4 ), and hydrogen will be also expected. On the one hand, hydrogen poses a significant threat to the nuclear waste repository when it is accumulated for a long time in the surrounding clay - such hydrogen production may damage the barrier properties of the geological formation, affecting the safety of the repository. On the other hand, hydrogen production represents a new energy source for bacterial growth, especially in such environments with low content of biodegradable organic matter. Moreover, some hydrogeno-trophic bacteria can also use Fe 3+ as an electron acceptor for their development. Therefore, the biological activity and biofilm formation could interfere in the metal corrosion behaviour. This phenomenon is widely known by MIC (Microbiologically Influenced Corrosion), which can represent a huge problem when promoting local corrosion. The objective of this study is to better understand the influence of local hydrogen formation in the carbon steel bio-corrosion process in the presence of Shewanella oneidensis MR-1, a model of Iron Reducing Bacteria (IRB), in order to evaluate the impact of the bacterial activity in terms of long term behaviour of geological disposal materials. In this study

Predicting corrosion of 316L stainless steel capsule by low level radioactive wastes (Am-241 and Co-60) in underground repository

International Nuclear Information System (INIS)

Nunoo, R.

2013-07-01

Most of radioactive wastes in Ghana are of low level in activity, (i.e LLRW) and are currently kept under lock in a secured room. The proposed plan by the Ghana Atomic Energy Commission is to seal the LLRW In 316L stainless steel disposal capsule for borehole repository. The research presented in this thesis was aimed at predicting the rate of both uniform and pitting corrosion of the 316L stainless steel disposal capsule by LLRW that will be kept in the capsule as a function of temperature, PH and chloride concentration for a period of up to 1000 years of disposal. The prediction analysis was based on the point defect deterministic model which assumed Schottky defects as the defect of the oxide formed on the surfaces of the disposal capsule. Faradays law and Fick first law of diffusion were used to determine the current across the internal and external surfaces of the capsule used to predict the uniform corrosion rate and corrosion loss of the 316L stainless steel disposal capsule. By imposing chlorine on the external environment of the disposal capsule, pit growth rate and pit depth of capsule were also predicted over a period of 1000 years. The capsule containing disused Am-241 source at activity level of 1.67×10 3 Bq had an average uniform corrosion rate of 3.65×10 -7 m/year and average pit growth rate of 1.79×10 -6 m/year while the corrosion rate and pit growth rate of the capsule containing disused Co-60 with activity level of 2.78×10 8 Bq were 6.9×10 -7 m/year and 2.1×10 -6 m/year respectively at PH value of 8 and repository temperature of 75°C and chloride concentration of 0.5 M. The uniform corrosion rate indicated that at PH=8 and T=75°C, 80.04% of the disposal capsule containing disused Am-241 would remain whiles 62.34% of that containing Co-60 disused source would remain after 1000 years when undergoing uniform corrosion, and an arbitrary position on the disposal capsule will have a pit depth of 1.98×10 -3 m after 100 years. Hence the integrity

Electrochemical and corrosion properties of carbon steel in simulated geological disposal environments

International Nuclear Information System (INIS)

Sugimoto, Katsuhisa

2011-01-01

This paper reviews electrochemical and corrosion studies on the application of carbon steel to an overpack container, which is used for the geological disposal of radioactive wastes. Deaerated alkaline Na 2 SO 4 -NaHCO 3 - NaCl solutions and bentonite soaked with the solutions are used as simulated geological disposal environments. Electrochemical studies show the corrosion of the steel in an early stage is the activation control. Corrosion rates are controlled by the composition of the solutions, alloying elements, and the structure of the steel. The rates decrease with time due to the formation of FeCO 3 (siderite) film on the steel. Immersion corrosion tests show general corrosion morphology. Average corrosion rates of long duration have been evaluated. Clear proofs of the initiation of localized corrosion, such as pitting, crevice corrosion, hydrogen embrittlement and stress-corrosion cracking, have not been reported. (author)

Processing and Pre-Treatment of Solid Radioactive Waste

Energy Technology Data Exchange (ETDEWEB)

Cerre, P. [Service de Controle des Radiations et de Genie Radioactif, Commissariat a L' Energie Atomique, Saclay (France)

1960-07-01

As solid radioactive waste varies in form, dimensions and volume, the Atomic Energy Commission first of all reduces the volume by breaking up and compressing the waste. Since the temporary storage of such waste is always attended by the risk of contamination, an efficient packing system has been devised and adopted. This consists of embedding the waste in the heart of a specially-designed block of concrete possessing the following characteristics: Great strength Maximum insolubility Resistance to corrosion Maximum imperviousness Protection against radiation. It is thus quite safe to store these blocks with a view to final dumping. (author)

Exposure testing of fasteners in preservative treated wood: Gravimetric corrosion rates and corrosion product analyses

Energy Technology Data Exchange (ETDEWEB)

Zelinka, Samuel L., E-mail: szelinka@fs.fed.u [USDA Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726 (United States); Sichel, Rebecca J. [College of Engineering, University of Wisconsin, Madison, WI 53706 (United States); Stone, Donald S. [Department of Materials Science and Engineering, College of Engineering, University of Wisconsin, Madison, WI 53706 (United States)

2010-12-15

Research highlights: {yields} The composition of the corrosion products was similar for the nail head and shank. {yields} Reduced copper was not detected on any of the fasteners. {yields} Measured corrosion rates were between 1 and 35 {mu}m year{sup -1}. - Abstract: Research was conducted to determine the corrosion rates of metals in preservative treated wood and also understand the mechanism of metal corrosion in treated wood. Steel and hot-dip galvanized steel fasteners were embedded in wood treated with one of six preservative treatments and exposed to 27 {sup o}C at 100% relative humidity for 1 year. The corrosion rate was determined gravimetrically and the corrosion products were analyzed with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Although the accepted mechanism of corrosion in treated wood involves the reduction of cupric ions from the wood preservative, no reduced copper was found on the corrosion surfaces. The galvanized corrosion products contained sulfates, whereas the steel corrosion products consisted of iron oxides and hydroxides. The possible implications and limitations of this research on fasteners used in building applications are discussed.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Chemically reducing decontamination method for radioactive metal

International Nuclear Information System (INIS)

Tanaka, Akio; Onuma, Tsutomu; Sato, Hitoshi.

1994-01-01

The present invention concerns a decontamination method of electrolytically reducing radioactive metal wastes, then chemically dissolving the surface thereof with a strong acid decontaminating solution. This method utilizes dissolving characteristics of stainless steels in the strong acid solution. That is, in the electrolytic reduction operation, a portion of the metal wastes is brought into contact with a strong acid decontaminating solution, and voltage and current are applied to the portion and keep it for a long period of time so as to make the potential of the immersed portion of the metal wastes to an active soluble region. Then, the electrolytic reduction operation is stopped, and the metal wastes are entirely immersed in the decontaminating solution to decontaminate by chemical dissolution. As the decontaminating solution, strong acid such as sulfuric acid, nitric acid is used. Since DC current power source capacity required for causing reaction in the active soluble region can be decreased, the decontamination facility can be minimized and simplified, and necessary electric power can be saved even upon decontamination of radioactive metal wastes made of stainless steels and having a great area. Further, chemical dissolution can be conducted without adding an expensive oxidizing agent. (N.H.)

Air corrosion in storing

International Nuclear Information System (INIS)

Mazaudier, F.; Feron, D.; Baklouti, M.; Midoux, N.

2001-01-01

The air corrosiveness of a radioactive waste package has been estimated in a store inside which the environmental conditions are supposed to be rather close to the outside ones. It is expressed according to the ISO 9223 standard, from the humidification value and the amounts of sulfur dioxide and chlorine ions. A computer code has been perfected too; the thermal behaviour of the package can then been determined. (O.M.)

Prevention of stress corrosion cracking in nuclear waste storage tanks

International Nuclear Information System (INIS)

Ondrejcin, R.S.

1983-01-01

At the Savannah River Plant, stress corrosion of carbon steel storage tanks containing alkaline nitrate radioactive waste is prevented by stress relief and specification of limits on waste composition and temperature. Actual cases of cracking have occurred in the primary steel shell of tanks designed and built before 1960 and were attributed to a combination of high residual stresses from fabrication welding and aggressiveness of fresh wastes from the reactor fuel reprocessing plants. The fresh wastes have the highest concentration of nitrate, which has been shown to be the cracking agent. Also, as the waste solutions age and are reduced in volume by evaporation of water, nitrite and hydroxide ions become more concentrated and inhibit stress corrosion. Thus, by providing a heel of aged evaporated waste in tanks that receive fresh wastes, concentrations of the inhibitor ions are maintained within specific ranges to protect against nitrate cracking. The concentration and temperature range limits to prevent cracking were determined by a series of statistically designed experiments

Radioactive waste management

International Nuclear Information System (INIS)

Blomek, D.

1980-01-01

The prospects of nuclear power development in the USA up to 2000 and the problems of the fuel cycle high-level radioactive waste processing and storage are considered. The problems of liquid and solidified radioactive waste transportation and their disposal in salt deposits and other geologic formations are discussed. It is pointed out that the main part of the high-level radioactive wastes are produced at spent fuel reprocessing plants in the form of complex aqueous mixtures. These mixtures contain the decay products of about 35 isotopes which are the nuclear fuel fission products, about 18 actinides and their daughter products as well as corrosion products of fuel cans and structural materials and chemical reagents added in the process of fuel reprocessing. The high-level radioactive waste management includes the liquid waste cooling which is necessary for the short and middle living isotope decay, separation of some most dangerous components from the waste mixture, waste solidification, their storage and disposal. The conclusion is drawn that the seccessful solution of the high-level radioactive waste management problem will permit to solve the problem of the fuel cycle radioactive waste management as a whole. The salt deposits, shales and clays are the most suitable for radioactive waste disposal [ru

Microbially induced corrosion of carbon steel in deep groundwater environment

Directory of Open Access Journals (Sweden)

Pauliina eRajala

2015-07-01

Full Text Available The metallic low and intermediate level radioactive waste generally consists of carbon steel and stainless steels. The corrosion rate of carbon steel in deep groundwater is typically low, unless the water is very acidic or microbial activity in the environment is high. Therefore, the assessment of microbially induced corrosion of carbon steel in deep bedrock environment has become important for evaluating the safety of disposal of radioactive waste. Here we studied the corrosion inducing ability of indigenous microbial community from a deep bedrock aquifer. Carbon steel coupons were exposed to anoxic groundwater from repository site 100 m depth (Olkiluoto, Finland for periods of three and eight months. The experiments were conducted at both in situ temperature and room temperature to investigate the response of microbial population to elevated temperature. Our results demonstrate that microorganisms from the deep bedrock aquifer benefit from carbon steel introduced to the nutrient poor anoxic deep groundwater environment. In the groundwater incubated with carbon steel the planktonic microbial community was more diverse and 100-fold more abundant compared to the environment without carbon steel. The betaproteobacteria were the most dominant bacterial class in all samples where carbon steel was present, whereas in groundwater incubated without carbon steel the microbial community had clearly less diversity. Microorganisms induced pitting corrosion and were found to cluster inside the corrosion pits. Temperature had an effect on the species composition of microbial community and also affected the corrosion deposits layer formed on the surface of carbon steel.

Corrosion susceptibility of steel drums to be used as containers for intermediate level nuclear waste

International Nuclear Information System (INIS)

Farina, S.; Schulz Rodriguez, F.; Duffo, G.

2013-01-01

The present work is a study of the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins contaminated with different types and concentrations of aggressive species. A special type of specimen was manufactured to simulate the cemented ion-exchange resins in the drum. The evolution of the corrosion potential and the corrosion rate of the steel, as well as the electrical resistivity of the matrix were monitored over a time period of 900 days. The aggressive species studied were chloride ions (the main ionic species of concern) and sulphate ions (produced during radiolysis of the cationic exchange-resins after cementation). The work was complemented with an analysis of the corrosion products formed on the steel in each condition, as well as the morphology of the corrosion products. When applying the results obtained in the present work to estimate the corrosion depth of the steel drums containing the cemented radioactive waste after a period of 300 years (foreseen durability of the Intermediate Level Radioactive Waste facility in Argentina), it is found that in the most unfavourable case (high chloride contamination), the corrosion penetration will be considerably lower than the thickness of the wall of the steel drums. (authors)

Corrosion of candidate materials in Lake Rotokawa geothermal exposure

Energy Technology Data Exchange (ETDEWEB)

Estill, J.C.; McCright, R.D.

1995-05-01

Corrosion rates were determined for CDA 613, CDA 715, A-36 carbon steel, 1020 carbon steel, and Alloy 825 flat coupons which were exposed to geothermal spring water at Paraiki site number 9 near Lake Rotokawa, New Zealand. Qualitative observations of the corrosion performance of Type 304L stainless steel and CDA 102 exposed to the same environment were noted. CDA 715, Alloy 825, 1020 carbon steel, and other alloys are being considered for the materials of construction for high-level radioactive waste containers for the United States civilian radioactive waste disposal program. Alloys CDA 613 and CDA 102 were tested to provide copper-based materials for corrosion performance comparison purposes. A36 was tested to provide a carbon steel baseline material for comparison purposes, and alloy 304L stainless steel was tested to provide an austenitic stainless steel baseline material for comparison purposes. In an effort to gather corrosion data from an environment that is rooted in natural sources of water and rock, samples of some of the proposed container materials were exposed to a geothermal spring environment. At the proposed site at Yucca Mountain, Nevada, currently under consideration for high-level nuclear waste disposal, transient groundwater may come in contact with waste containers over the course of a 10,000-year disposal period. The geothermal springs environment, while extremely more aggressive than the anticipated general environment at Yucca Mountain, Nevada, could have similarities to the environment that arises at selected local sites on a container as a result of crevice corrosion, pitting corrosion, microbiologically influenced corrosion (MIC), or the concentration of the ionic species due to repetitive evaporation or boiling of the groundwater near the containers. The corrosion rates were based on weight loss data obtained after six weeks exposure in a 90{degrees}C, low-pH spring with relatively high concentrations of SO{sub 4}{sup 2-} and Cl{sup -}.

Studies of corrosion in metallic container for storage of high level radioactive wastes

International Nuclear Information System (INIS)

Azkarate, I.; Madina, V.; Insausti, M.

1999-01-01

The metallic container is one of the most important barriers that, along with engineered and natural barriers, will isolate high level nuclear waste in saline and granite geological formations from the geosphere. However, general and localized corrosion modes such as stress corrosion cracking (SCC), pitting, crevice corrosion and hydrogen damage can be active under disposal conditions, so the corrosion behaviour of the metal container material must be carefully studied. Several metals and their alloys have been proposed for the fabrication of nuclear waste containers including carbon steels, stainless steels, titanium and titanium alloys and copper and copper-base alloys. Carbon steels and copper alloys are considered for the two rock formations, titanium is considered for salt environments and the stainless steel only in the case of a granite formation. (Author)

The corrosion rate and the hydrogen absorption behavior of titanium under reducing condition-III. Research document

International Nuclear Information System (INIS)

Suzuki, H.; Taniguchi, N.; Kawakami, S.

2005-03-01

Titanium is one of the candidate materials for overpacks as a high corrosion resistance metal. At the initial stage of repository, oxidizing condition will be given around the overpack because oxygen will be brought from the ground. The oxygen will be consumed by the reaction with impurities in buffer material or corrosion of overpack, and reducing condition will be achieved around the overpack. With the changing of redox condition, the water reduction becomes to dominate the cathodic reaction accompanying hydrogen generation. Crevice corrosion and hydrogen embrittlement are main causes of the damage of long term integrity of titanium overpack. However, it is not known about the corrosion resistance and hydrogen absorption behavior of titanium under reduction condition. In this study, the completely sealed ampoule test and the immersion test of titanium in aqueous solution and bentonite was carried out. In order to obtain reliable data about the hydrogen generation rate and the ratio of hydrogen absorption in titanium. From the result of 3 years immersion tests, corrosion rate of titanium were estimated to be in the order of 10 -2 ∼10 -1 μm/y in the aqueous solution, and 10 -3 ∼10 -2 μm/y in bentonite. This value is almost the same as the last report. Almost all the hydrogen generated by corrosion was absorbed in titanium in the immersion tests in completely sealed ampoule. In the examination that changed each parameter, it was suggested that the amount of the hydrogen absorption become 2∼3 times in 1M HCO 3- and pH13. (author)

Evaluation of Nitrate and Nitrite Reduction Kinetics Related to Liquid-Air-Interface Corrosion

International Nuclear Information System (INIS)

Li, Xiaoji; Gui, F.; Cong, Hongbo; Brossia, C.S.; Frankel, G.S.

2014-01-01

Liquid-air interface (LAI) corrosion has been a concern for causing leaks in the carbon steel tanks used for holding high-level radioactive liquid waste. To assist in understanding the mechanism of LAI corrosion, the kinetics of nitrate and nitrite reduction reactions were investigated electrochemically. Cyclic voltammetry and cathodic polarization measurements indicated that the nitrite reduction reaction exhibited faster kinetics than the nitrate reduction reaction at higher cathodic overpotential. However, the primary reduction reaction at the open circuit potential under aerated conditions was the oxygen reduction reaction. The reduction of residual oxygen was also the dominant cathodic reaction at open circuit potential in deaerated conditions. Moreover, the kinetics of oxygen reduction on steel electrodes were significantly influenced by the sample immersion conditions (partial vs. full) for aerated liquid nuclear waste simulants, but not for deaerated conditions. Lastly, the gaseous products formed during LAI corrosion were analyzed using the gas detector tube method and gas chromatography-mass spectrometry and found to contain NH 3 , NO 2 and NO. However, the results suggested that these products were caused by the local acidification generated by the hydrolysis of cations after LAI corrosion underwent extensive propagation, instead of being directly reduced in alkaline conditions. Thus, the results in this work showed that the kinetics of nitrate and nitrite reduction could not generate a salt concentration cell in the meniscus region to cause LAI corrosion

Modelling the behaviour of corrosion products in the primary heat transfer circuits of pressurised water reactors

International Nuclear Information System (INIS)

Rodliffe, R.S.; Polley, M.V.; Thornton, E.W.

1985-05-01

The redistribution of corrosion products from the primary circuit surfaces of a water reactor can result in increased flow resistance, poorer heat transfer performance, fuel failure and radioactive contamination of circuit surfaces. The environment is generally sufficiently well controlled to ensure that the first three effects are not limiting. The last effect is of particular importance since radioactive corrosion products are major contributors to shutdown fields and since it is necessary to ensure that the radiation exposure of personnel is as low as reasonably achievable. This review focusses attention on the principles which must form the basis for any mechanistic model describing the formation, transport and deposition of radioactive corrosion products. It is relevant to all water reactors in which the primary heat transfer medium is predominantly single-phase water and in which steam is generated in a secondary circuit, i.e. including CANDU pressurised heavy water reactors, Sovient VVERs, etc. (author)

Analysis of Gamma Dose Rate Caused by Corrosion Products inside the Containment Building of Yonngwang Nuclear Power Plant Unit 3 During Shutdown Period

Energy Technology Data Exchange (ETDEWEB)

Ha, Wi Ho; Kim, Jae Cheon; Kim, Soon Young; Kim, Jong Kyung [Hanyang Univ., Seoul (Korea, Republic of)

2005-07-01

Occupational radiation exposure(ORE) of nuclear power plant(NPP) workers mainly occurs during the shutdown period. Major radioactive sources are the corrosion products released from the reactor coolant system(RCS). The corrosion products consist of circulating crud and deposited crud. Major radioactive corrosion products, {sup 58}Co and {sup 60}Co, are known to contribute approximately more than 70% of the total ORE. In this study, the corrosion products regarding cobalt were evaluated during the shutdown period, and gamma dose rates caused by them were calculated at the main working area inside the containment building of the Yonggwang NPP Unit 3.

Long term corrosion protection sleeve for tightly closed barrels with highly radioactive contents

International Nuclear Information System (INIS)

Koester, R.; Smailos, E.; Schwarzkopf, W.; Kiesow, A.

1986-01-01

The application of the corrosion resistant layer on the container body is achieved by blasting plating and by a special design of weld seams on the lid or floor stopper. The corrosion protection layer completely surrounds the container, is additionally applied to the layers in the area of the lid and bottom surface of one floor or lid plate, which consists of another material as corrosion protection layer and which has a diameter a little greater than the hollow cylinder container body. (orig./PW) [de

Corrosion of alloy 22 in phosphate ions effect and chloride containing solutions

International Nuclear Information System (INIS)

Carranza, Ricardo M.

2009-01-01

Alloy 22 belongs to Ni-Cr-Mo family. This alloy resists the most aggressive environments for industrial applications, in oxidizing as well as reducing conditions, because exhibits an excellent uniform and localized corrosion resistance in aqueous solution. Because of its outstanding corrosion resistant, this alloy is one of the candidate to be considered for the outer shell of the canister that would contain high level radioactive nuclear wastes in a geological repository. The aim of this work is to study ion phosphate influence over Alloy 22 corrosion behavior under aggressive conditions, such as high temperature and high ion chloride concentration, where this material might be susceptible to crevice corrosion. Two different types of samples were used: cylinder specimens for uniform corrosion behavior studies and Prismatic Crevice Assembly (PCA) specimens for localized corrosion studies. Electrochemical tests were performed in deaerated aqueous solution of 1 M NaCl and 1 M NaCl with different phosphate additions at 90 C degrees and pH near neutral. The anodic film and corrosion products obtained were studied by SEM/EDS. Cyclic Potentiodynamic Polarization (CPP) curves obtained for uniform corrosion studies, showed an increase of the passivity range in phosphate containing solutions. The passive current value was 1 μA/cm 2 approximately in all the tests. PCA electrochemical tests, that combined a CPP with a potentiostatic polarization step for 2 hours in between the forward and reverse scan, showed crevice corrosion development in some cases. The repassivation potential value, determined by the intersection of the forward and the reverse scan, increased with phosphate addition. A complete crevice corrosion inhibition effect was found for phosphate concentration higher than 0.3 M. These results indicate that the passivity potential range depend on phosphate presence and might be related with the incorporation of the anion in the passive film. Results of the tests

The role of hydrogenotrophic iron-reducing bacteria on the corrosion process in the context of geological disposal

International Nuclear Information System (INIS)

Kerber-Schutz, Marta

2013-01-01

The nuclear industry must to demonstrate the feasibility and safety of high level nuclear waste (HLNW) disposal. The generally recognised strategy for HLNW disposal is based on a multi-barrier system made by metallic packages surrounded by geological formation. The nuclear waste repository will be water re-saturated with time, and then the metallic corrosion process will take place. The aqueous corrosion will produce dihydrogen (H 2 ) that represents a new energetic source (electron donor) for microbial development. Moreover, the formation of Fe(II,III) solid corrosion products, such as magnetite (Fe 3 O 4 ), will provide electron acceptors favoring the development of iron-reducing bacteria (IRB). The activity of hydrogenotrophic and IRB can potentially alter the protective properties of passivating oxide layers (i.e. magnetite) which could reactivate corrosion. The main objective of this study is to evaluate the role of hydrogenotrophic and IRB activities on anoxic corrosion process by using geochemical indicators. Shewanella oneidensis strain MR-1 was chosen as model organism, and both abiotic and biotic conditions were investigated. In a first setup of experiments, our results indicate that synthetic magnetite is destabilized in the presence of hydrogenotrophic IRB due to structural Fe(III) reduction coupled to H 2 oxidation. The extent of Fe(III) bioreduction is notably enhanced with the increase in the H 2 concentration in the system: 4% H 2 ≤ 10% H 2 ≤ 60% H 2 . In a second setup of experiments, our results indicate that corrosion extent changes according to the solution composition and the surface of metallic sample (iron powder and carbon steel coupon). Moreover, the solid corrosion products are different for each sample: vivianite, siderite and chukanovite are the main mineral phases identified in the experiments with iron powder, while vivianite and magnetite are identified with carbon steel coupons. Our results demonstrate that corrosion rate is

Chemical and electrochemical aspects of the corrosion of stainless steels in the presence of sulphate reducing bacteria

International Nuclear Information System (INIS)

Feron, D.

1990-01-01

The corrosion behaviour of austenitic and ferritic stainless steels (316 L and 430Ti) in the presence of sulfate reducing bacteria, was investigated by several electrochemical techniques which were coupled with corrosion measurements on coupons and chemical analyses. Experiments were performed with 'Desulfovibrio vulgaris' and 'Desulfovibrio gigas' in three growth media containing lactate and sulfate. The decreases in corrosion potentials were correlated to the increase in sulphide content. The polarization curves showed also the major influence of sulphides on the passivity of stainless steels. Electrochemical impedance measurements were used to provide information in understanding the interactions between growth media or bacteria and stainless steels surfaces. The behaviour of the tested stainless steels in these conditions was mainly dependent on sulphide concentrations. (Author). 7 refs., 8 figs., 4 tabs

Research and development activities at INE concerning corrosion of final repository container materials

International Nuclear Information System (INIS)

Kienzler, Bernhard

2017-01-01

The present work provides a historical overview of the research and development activities carried out at the (Nuclear) Research Center Karlsruhe (today KIT) since the beginning of the 1980s on the corrosion of materials which might be suitable for construction of containers for highly radioactive wastes. The report relates almost exclusively to the work performed by Dr. Emmanuel Smailos, who elaborated the corrosion of various materials at the Institute for Nuclear Waste Disposal (INE). The requirements for the containers and materials, which were subject to changes in time, are presented. The changes were strongly influenced by the changed perception of the use of nuclear energy. The selection of the materials under investigations, the boundary conditions for the corrosion experiments and the analytical methods are described. Results of the corrosion of the materials such as finegrained steel, Hastelloy C4, nodular cast iron, titanium-palladium and copper or copper-nickel alloys in typical salt solutions are summarized. The findings of special investigations, e.g. corrosion under irradiation or the influence of sulfide on the corrosion rates are shown. For construction of disposal canisters, experiments were conducted to determine the contact corrosion, the influence of the hydrogen embrittlement of Ti-Pd and fine-grained steels on the corrosion behavior as well as the corrosion behavior of welding and the influence of different welding processes with the resulting heat-affected zones on the corrosion behavior. The work was contributed to several European research programs and was well recognized in the USA. Investigations on the corrosion of steels in non-saline solutions and corrosion under interim storage conditions as well as under the expected conditions of the Konrad repository for low-level radioactive wastes are also described. In addition, the experiments on ceramic materials are presented and the results of the corrosion of Al 2 O 3 and ZrO 2 ceramics

Influence of sulfate-reducing bacteria on the corrosion of steel in seawater: laboratory and in situ study

International Nuclear Information System (INIS)

Benbouzid-Rollet, N.

1993-01-01

A fouling reactor was designed to study, the influence of a mixed bio-film on AISI 316 L stainless steel. The bio-film was formed on the steel surface by the fermentative bacterium Vibrio natriegens. The sulfate-reducing bacterium Desulfovibrio vulgaris was then introduced in the reactor and colonized the surface, constituting approximately 5 % of the total population. The settlement of an anaerobic bacterium in the bio-film shows in it the existence of anaerobic micro-niches. Stainless steel electrochemical behavior was analyzed using open circuit potential and potentiodynamic polarization curves. Growth of the bio-film does not induce corrosion, but seems to change the cathodic oxygen reduction kinetics, diminishing the corrosion hazard. This effect increases when D. vulgaris grows in the bio-film. An ennobling of the open circuit potential was observed, similar to field cases already described. A case of drilling corrosion of carbon steel in a harbour area showed the characteristics of anaerobic corrosion related to sulfate-reducing bacteria. The total cultivatable SRB population was quantified and metabolic types were enumerated using specific electron donors. A maximum cell density of 1,1 x 10 8 cells/ cm 2 was estimated, revealing a very important growth of SRB on surfaces. Population structure was different in corroded and non-corroded areas. In corroded area, SRB utilizing benzoate and propionate were more abundant. A strain belonging to the sporulating genus Desulfotomaculum was isolated using these substrates, suggesting a partial aeration in the area of hole appearance. However, in vitro corrosion assays showed that the bacterial population sampled in this area induced a consequent weight loss of steel coupons, in the absence of oxygen. This was observed only with a diversified population, similar to that present in situ. It could not be reproduced with a mixed culture of two purified strains. (author)

Localized corrosion and stress corrosion cracking of candidate materials for high-level radioactive waste disposal containers in the US: A literature review

International Nuclear Information System (INIS)

Farmer, J.C.; McCright, R.D.

1988-01-01

Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys. Though all three austenitic candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these forms of localized attack. Both types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented for Alloy 825 under comparable conditions. Gamma irradiation has been found to enhance SCC of Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while microbiologically induced corrosion effects have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. Of the copper-based alloys, CDA 715 has the best overall resistance to localized attack. Its resistance to pitting is comparable to that of CDA 613 and superior to that of CDA 102. Observed rates of dealloying in CDA 715 are less than those observed in CDA 613 by orders of magnitude. The resistance of CDA 715 to SCC in tarnishing ammonical environments is comparable to that of CDA 102 and superior to that of CDA 613. Its resistance to SCC in nontarnishing ammonical environments is comparable to that of CDA 613 and superior to that of CDA 102. 22 refs., 8 figs., 4 tabs

Task E container corrosion studies: Annual report

International Nuclear Information System (INIS)

Bunnell, L.R.; Doremus, L.A.; Topping, J.B.; Duncan, D.R.

1994-06-01

The Pacific Northwest Laboratory is conducting the Solid Waste Technology Support Program (SWTSP) for Westinghouse Hanford Company (WHC). Task E is the Container Corrosion Study Portion of the SWTSP that will perform testing to provide defensible data on the corrosion of low-carbon steel, as used in drums to contain chemical and radioactive wastes at the Hanford Site. A second objective of Task E is to provide and test practical alternative materials that have higher corrosion resistance than low-carbon steel. The scope of work for fiscal year (FY) 1993 included initial testing of mild steel specimens buried in Hanford soils or exposed to atmospheric corrosion in metal storage sheds. During FY 1993, progress was made in three areas of Task E. First, exposure of test materials began at the Soil Corrosion Test Site where low-carbon steel specimens were placed in the soil in five test shafts at depths of 9 m (30 ft). Second, the corrosion measurement of low-carbon steel in the soil of two solid waste trenches continued. The total exposure time is ∼ 500 days. Third, an atmospheric corrosion test of low-carbon steel was put initiated in a metal shed (Building 2401-W) in the 200 West Area. This annual report describes the Task E efforts and provides a current status

Natural analogues of nuclear waste glass corrosion

International Nuclear Information System (INIS)

Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

1999-01-01

This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses

Natural analogues of nuclear waste glass corrosion.

Energy Technology Data Exchange (ETDEWEB)

Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

1999-01-06

This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

Overpack for processing radioactive waste

International Nuclear Information System (INIS)

Asano, Hidekazu.

1997-01-01

A glass solidification material in which radioactive wastes are sealed and solidified in glass is covered by an inner layer vessel made of corrosion resistant materials, and the outer side thereof is covered with an outer layer vessel made of a reinforced material. The inner layer vessel made of corrosion materials comprises corrosion materials such as titanium, copper, stainless steel and nickel based alloy, and the outer layer vessel made of a reinforced material comprises a reinforced material such as carbon steel. If it is constituted by using carbon steel having a thickness as much as of from 50 to 200mm, it is durable sufficiently under ground of about 1000m. Although the outer layer vessel made of the reinforced material is corroded by oxidation by oxygen contained in underwater after lapse of time of several years, it is endurable sufficiently to initial oxidative corrosion by determined the thickness to 50mm or more, and after oxygen is consumed, reductive corrosion with extremely slow progressing speed begins. Since the inner vessel made of the corrosion resistant material is formed, the lifetime is extended, and the glass solidification materials can be confined stably for a long period of time. (N.H.)

Corrosion of steel tanks in liquid nuclear wastes

International Nuclear Information System (INIS)

Carranza, Ricardo M.; Giordano, Celia M.; Saenz, Eduardo

2005-01-01

The objective of this work is to understand how solution chemistry would impact on the corrosion of waste storage steel tanks at the Hanford Site. Future tank waste operations are expected to process wastes that are more dilute with respect to some current corrosion inhibiting waste constituents. Assessment of corrosion damage and of the influence of exposure time and electrolyte composition, using simulated (non-radioactive) wastes, of the double-shell tank wall carbon steel alloys is being conducted in a statistically designed long-term immersion experiment. Corrosion rates at different times of immersion were determined using both weight-loss determinations and electrochemical impedance spectroscopy measurements. Localized corrosion susceptibility was assessed using short-term cyclic potentiodynamic polarization curves. The results presented in this paper correspond to electrochemical and weight-loss measurements of the immersed coupons during the first year of immersion from a two year immersion plan. A good correlation was obtained between electrochemical measurements, weight-loss determinations and visual observations. Very low general corrosion rates ( -1 ) were estimated using EIS measurements, indicating that general corrosion rate of the steel in contact with liquid wastes would no be a cause of tank failure even for these out-of-chemistry limit wastes. (author) [es

Microbial Corrosion of API 5L X-70 Carbon Steel by ATCC 7757 and Consortium of Sulfate-Reducing Bacteria

Directory of Open Access Journals (Sweden)

Arman Abdullah

2014-01-01

Full Text Available Various cases of accidents involving microbiology influenced corrosion (MIC were reported by the oil and gas industry. Sulfate reducing bacteria (SRB have always been linked to MIC mechanisms as one of the major causes of localized corrosion problems. In this study, SRB colonies were isolated from the soil in suspected areas near the natural gas transmission pipeline in Malaysia. The effects of ATCC 7757 and consortium of isolated SRB upon corrosion on API 5L X-70 carbon steel coupon were investigated using a weight loss method, an open circuit potential method (OCP, and a potentiodynamic polarization curves method in anaerobic conditions. Scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDS were then used to determine the corrosion morphology in verifying the SRB activity and corrosion products formation. Results from the study show that the corrosion rate (CR of weight loss method for the isolated SRB is recorded as 0.2017 mm/yr compared to 0.2530 mm/yr for ATCC 7757. The Tafel plot recorded the corrosion rate of 0.3290 mm/yr for Sg. Ular SRB and 0.2500 mm/yr for Desulfovibrio vulgaris. The results showed that the consortia of isolated SRB were of comparable effects and features with the single ATCC 7757 strain.

Released radioactivity reducing device

International Nuclear Information System (INIS)

Miyamoto, Yumi.

1995-01-01

A water scrubber is disposed in a scrubber tank and a stainless steel fiber filter is disposed above the water scrubber. The upper end of the scrubber tank is connected by way of a second bent tube to a capturing vessel incorporating a moisture removing layer and an activated carbon filter. The exit of the capturing vessel is connected to a stack. Upon occurrence of an accident of a BWR-type power plant, gases containing radioactive materials released from a reactor container are discharged into the water scrubber from a first bent tube through a venturi tube nozzle, and water soluble and aerosol-like radioactive materials are captured in the water. Aerosol and splashes of water droplets which can not be captured thoroughly by the water scrubber are captured by the stainless steel fiber filter. Gases passing through the scrubber tank are introduced to a capturing vessel through a second bent tube, and organic iodine is captured by the activated carbon filter. (I.N.)

78 FR 45579 - Request for a License to Import Radioactive Waste

Science.gov (United States)

2013-07-29

... NUCLEAR REGULATORY COMMISSION Request for a License to Import Radioactive Waste Pursuant to 10 CFR... Technologies, Inc., Class A Up to a maximum Laundering and Canada June 4, 2013, June 5, 2013, radioactive total of 0.074 decontamination IW032. waste consisting TBq (2 Ci) per of protective 11006100 of corrosion...

Long-term corrosion behaviour of low-/medium-level waste packages

International Nuclear Information System (INIS)

Jendras, M.; Bach, F.W.; Behrens, S.; Birr, Ch.; Hassel, Th.

2009-01-01

Full text of publication follows: Storage of low- and medium-level radioactive waste requires safe packages. This means that all materials used for the manufacturing of such packages have to show a sufficient resistance especially against corrosive attacks. Since these packages are generally made from carbon steel an additional coating for corrosion protection - mainly solvent-based polymers - is necessary. However, it is not enough to consider the selection and combination of the materials. Regarding the construction and manufacturing of corrosion-resistant drums for low- and medium-level radioactive waste there also has to be paid closer attention to the joining technologies such as welding. For lifetime prediction of low-/medium-level waste packages reliable experimental data concerning the long-term corrosion behaviour of each material as well as of the components is needed. Therefore sheet metals from carbon steel were galvanized or coated with different solvent-based and water-based corrosion protection materials (epoxy as well as silicone resins). After damaging the anti-corrosion coating of some of these sheets with predefined scratches sets of these samples were stored at higher temperatures in climatic chamber, in simulated waste or aged according to standard DIN EN ISO 9227. All corrosion damages were analyzed by means of metallography (light microscopy as well as scanning electron microscopy of micro-sections). The quantitative influence of the corrosive attacks on the mechanical properties of the materials was examined by mechanical testing according to DIN EN 10002. Besides reduction of tensile strength drastic reduction of percentage of elongation after fracture (from 30 % to 10 %) was found. Further experiments were carried out using components or scaled-down drums joined by means of innovative welding techniques such as Cold Arc or Force Arc. The relevant welding parameters (e.g. welding current, proper volume of shielding gas or wire feed) were

The Proposed Yucca Mountain Repository From A Corrosion Perspective

International Nuclear Information System (INIS)

J.H. Payer

2005-01-01

Corrosion is a primary determinant of waste package performance at the proposed Yucca Mountain Repository and will control the delay time for radionuclide transport from the waste package. Corrosion is the most probable and most likely degradation process that will determine when packages will be penetrated and the shape, size, and distribution of those penetrations. The general issues in corrosion science, materials science and electrochemistry are well defined, and the knowledge base is substantial for understanding corrosion processes. In this paper, the Yucca Mountain Repository is viewed from a corrosion perspective. A major component of the long-term strategy for safe disposal of nuclear waste at the Yucca Mountain Repository is first to completely isolate the radionuclides in the waste packages for long times and to greatly retard the egress and transport of radionuclides from penetrated packages. Therefore, long-lived waste packages are important. The corrosion resistance of the waste package outer canister is reviewed, and a framework for the analysis of localized corrosion processes is presented. An overview is presented of the Materials Performance targeted thrust of the U.S. Department of Energy/Office of Civilian Radioactive Waste Management's Office of Science and Technology and International. The thrust program strives for increased scientific understanding, enhanced process models and advanced technologies for corrosion control

Italian experience on the processing of solid radioactive wastes

International Nuclear Information System (INIS)

Costa, A.; De Angelis, G.

1989-12-01

Experimental work is under way in Italy for treatment and conditioning of different types of solid radioactive wastes. The following wastes are taken into account in this paper: Magnox fuel element debris, solid compactable wastes, radiation sources and contaminated carcasses. The metallic debris, consisting of Magnox splitters and braces, are conditioned, after drying and separation of corrosion products, by means of a two component epoxy system (base product + hardener). Solid compactable wastes are reduced in volume by using a press. The resulting pellets are transferred to a final container and conditioned with a cement mortar of a suitable consistency. As to the radiation sources, mainly contained in lightning-rods, gas detectors and radioactive thickness gauges, the encapsulation in a cementitious grout is a common practice for their incorporation. Early experiments, with satisfactory results, have also been conducted for the cementation of contaminated carcasses. (author)

Localized corrosion of carbon steels due to sulfate-reducing bacteria. Development of a specific sensor; Corrosion localisee des aciers au carbone induite par des bacteries sulfato-reductrices. Developpement d'un capteur specifique

Energy Technology Data Exchange (ETDEWEB)

Monfort Moros, N.

2001-11-01

This work concerns the microbiologically influenced corrosion of carbon steels in saline anaerobic media (3% of NaCl) containing sulfato-reducing bacteria (Desulfovibrio gabonensis, DSM 10636). In these media, extreme localised corrosion occurs by pitting under the bio-film covering the metallic substrate. A sensor with concentric electrodes was designed to initiate the phenomenon of bio-corrosion, recreating the favourable conditions for growth of a corrosion pit, and then measuring the corrosion current maintained by bacterial activity. The pit initiation was achieved through either of two methods. The electrochemical conditioning involved driving the potential difference between inner and outer electrodes to values corresponding to a galvanic corrosion that can be maintained by the bacterial metabolism. The mechanical process involved removal of a portion of the bio-film by scratching, yielding galvanic potential differences equivalent to that found by the conditioning technique. This protocol was found to be applicable to a bio-corrosion study on industrial site for the monitoring of the metallic structures deterioration (patent EN 00/06114, May 2000). Thereafter, a fundamental application uses the bio-corrosion sensor for Electrochemical Impedance Spectroscopy (EIS), Electrochemical Noise Analysis (ENA) and current density cartography by the means of micro-electrodes. Thus, the EIS technique reveals the importance of the FeS corrosion products for initiation of bio-corrosion start on carbon steel. In addition, depending on the method used to create a pit, the ENA gives rise to supplementary processes (gaseous release) disturbing the bio-corrosion detection. The beginning of a bio-corrosion process on a clean surface surrounded with bio-film was confirmed by the current density cartography. These different results establish the sensor with concentric electrodes as an indispensable tool for bio-corrosion studies, both in the laboratory and on industrial sites

Storage container for radioactive wastes

International Nuclear Information System (INIS)

Catalayoud, L.; Gerard, M.

1990-01-01

Tightness, shock resistance and corrosion resistance of containers for storage of radioactive wastes it obtained by complete fabrication with concrete reinforced with metal fibers. This material is used for molding the cask, the cover and the joint connecting both parts. Dovetail grooves are provided on the cask and the cover for the closure [fr

Studies on the effects of sulphate-reducing bacteria on mild carbon-steel relevant to radioactive waste disposal in the UK

International Nuclear Information System (INIS)

Philp, J.C.; Christofi, N.; Taylor, K.J.; West, J.M.

1987-01-01

Sulphate-reducing bacteria (SRB) have been used to determine their maximum effect on mild carbon-steel (BS4360 grade 43A) of relevance to waste disposal. Batch (static) and continuous culture studies were carried out and corrosion effects monitored by measuring weight loss and pitting. Results show that corrosion increases linearly with increased ferrous iron concentrations. Maximum corrosion was obtained in continuous culture where the organisms were maintained in the exponential phase of growth. Corrosion by SRB has been monitored in model systems mimicking low groundwater flow, deep rock formations in which steel coupons were subjected to a synthetic granitic water/bentonite environment with or without microorganisms. At termination of the experiment corrosion in the presence of SRB was almost three times higher than in their absence. (author)

Corrosion and deposition behaviour of 60Co and 54Mn in the SNR mockup loop for the primary sodium system

International Nuclear Information System (INIS)

Menken, G.; Reichel, H.

1976-01-01

The SNR corrosion mockup loop, simulating the SNR primary system is described. The influence of hydraulic conditions and temperature on the deposition behaviour is studied. γ-spectroscopy measurements at the pipe-work and removable samples allowed to determine the distribution of radioactive corrosion products in the loop and by-pass system. The release rate of Mn 54 could be reduced by a factor of 3 by decreasing the cold trap temperature from 165 0 C to 105 0 C while the Co 60 release rate could be reduced by a factor of 14, respectively. High temperature loop sections (873K) representing 13% of the loop surface absorbed 50-60% of the released Co 60 and only 8 - 18% of the Mn 54. The cold trap absorbed not more than 1% of the Co 60 and 10% of the Mn 54 inventory. (author)

Time-dependent radioactivity distribution in MAFF

International Nuclear Information System (INIS)

Nebel, F.; Zech, E.; Faestermann, T.; Kruecken, R.; Maier-Komor, P.; Assmann, W.; Szerypo, J.; Gross, M.; Kester, O.; Thirolf, P.G.; Groetzschel, R.

2006-01-01

The Munich Accelerator for Fission Fragments is planned to be installed at the FRM II in Garching. It will operate a uranium-carbide-loaded graphite matrix as a target for neutron-induced fission. The radioactive reaction fragments leave the ion source as both, atoms and ions. For radiation safety it is imperative to have a basic understanding of the fragment distribution within the beam line. Atoms leaving the graphite matrix will spread like a gas and stick to surfaces depending on their species. A probabilistic Monte-Carlo approach is used to predict the surface coating of internal surfaces of the beam line for all fission nuclides. To decrease calculation time, the problem is reduced to two dimensions with the surface areas being a measure for the probability, that they are hit by a particle. The program is completely time dependent to implement radioactive decay. Ions leaving the fission ion source are transported by electrostatic means towards the mass pre-separator, a low-resolution dipole magnet with a complex slit system in the focal plane. All unwanted ions are stopped at the slits, resulting in a high level of radioactive contamination. While it is advantageous for shielding purposes to have the majority of the contamination in one point, precautions must be taken to ensure that it stays that way. Material corrosion caused by sputtering will release previously implanted radionuclides. To reduce this effect, different methods are under investigation, one of which is changing the slit geometry. The considered designs will be described and experimental results will be shown

The anaerobic corrosion of carbon steel and cast iron in artificial groundwaters

Energy Technology Data Exchange (ETDEWEB)

Smart, N.R. [AEA Technology plc, Culham Science Centre (United Kingdom); Blackwood, D.J. [National Univ. of Singapore (Singapore); Werme, L. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

2001-07-01

In Sweden, high level radioactive waste will be disposed of in a canister with a copper outer and a cast iron or carbon steel inner. If the iron insert comes into contact with anoxic geological water, anaerobic corrosion leading to the generation of hydrogen will occur. This paper presents a study of the anaerobic corrosion of carbon steel and cast iron in artificial Swedish granitic groundwaters. Electrochemical methods and gas collection techniques were used to assess the mechanisms and rates of corrosion and the associated hydrogen gas production over a range of conditions. The corrosion rate is high initially but is anodically limited by the slow formation of a duplex magnetite film. The effects of key environmental parameters such as temperature and ionic strength on the anaerobic corrosion rate are discussed.

The anaerobic corrosion of carbon steel and cast iron in artificial groundwaters

International Nuclear Information System (INIS)

Smart, N.R.; Blackwood, D.J.; Werme, L.

2001-07-01

In Sweden, high level radioactive waste will be disposed of in a canister with a copper outer and a cast iron or carbon steel inner. If the iron insert comes into contact with anoxic geological water, anaerobic corrosion leading to the generation of hydrogen will occur. This paper presents a study of the anaerobic corrosion of carbon steel and cast iron in artificial Swedish granitic groundwaters. Electrochemical methods and gas collection techniques were used to assess the mechanisms and rates of corrosion and the associated hydrogen gas production over a range of conditions. The corrosion rate is high initially but is anodically limited by the slow formation of a duplex magnetite film. The effects of key environmental parameters such as temperature and ionic strength on the anaerobic corrosion rate are discussed

Monitoring Microbially Influenced Corrosion

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques......Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

Carbon-14 speciation during anoxic corrosion of activated steel in a repository environment

Energy Technology Data Exchange (ETDEWEB)

Wieland, E.; Cvetkovic, B.Z.; Kunz, D. [Paul Scherrer Institute, Villigen (Switzerland). Lab. for Waste Management; Salazar, G.; Szidat, S. [Bern Univ. (Switzerland). Dept. of Chemistry and Biochemistry and Oeschger Centre for Climate Change Research

2018-01-15

Radioactive waste contains significant amounts of {sup 14}C which has been identified a key radionuclide in safety assessments. In Switzerland, the {sup 14}C inventory of a cement-based repository for low- and intermediate-level radioactive waste (L/ILW) is mainly associated with activated steel (∝85 %). {sup 14}C is produced by {sup 14}N activation in steel parts exposed to thermal neutron flux in light water reactors. Release of {sup 14}C occurs in the near field of a deep geological repository due to anoxic corrosion of activated steel. Although the {sup 14}C inventory of the L/ILW repository and the sources of {sup 14}C are well known, the formation of {sup 14}C species during steel corrosion is only poorly understood. The aim of the present study was to identify and quantify the {sup 14}C-bearing carbon species formed during the anoxic corrosion of iron and steel and further to determine the {sup 14}C speciation in a corrosion experiment with activated steel. All experiments were conducted in conditions similar to those anticipated in the near field of a cement-based repository.

Hanford double shell tank corrosion monitoring instrument tree prototype

International Nuclear Information System (INIS)

Nelson, J.L.; Edgemon, G.L.; Ohl, P.C.

1995-11-01

High-level nuclear wastes at the Hanford site are stored underground in carbon steel double-shell and single-shell tanks (DSTs and SSTs). The installation of a prototype corrosion monitoring instrument tree into DST 241-A-101 was completed in December 1995. The instrument tree has the ability to detect and discriminate between uniform corrosion, pitting, and stress corrosion cracking (SCC) through the use of electrochemical noise measurements and a unique stressed element, three-electrode probe. The tree itself is constructed of AISI 304L stainless steel (UNS S30403), with probes in the vapor space, vapor/liquid interface and liquid. Successful development of these trees will allow their application to single shell tanks and the transfer of technology to other US Department of Energy (DOE) sites. Keywords: Hanford, radioactive waste, high-level waste tanks, electrochemical noise, probes, double-shell tanks, single-shell tanks, corrosion

Effect of noble metals on the corrosion of AISI 316L stainless steel in nitric acid

International Nuclear Information System (INIS)

Robin, R.; Andreoletti, G.; Fauvet, P.; Terlain, A.

2004-01-01

In the spent fuel treatment, the solutions of fission products contain dissolution fines, in particular platinoids. These solutions are stored into AISI 316L stainless steel tanks, and the contact of noble metallic particles such as platinoids with austenitic stainless steels may induce a shift of the steel corrosion potential towards the trans-passive domain by galvanic coupling. In that case, the steel may be polarized up to a potential value above the range of passive domain, that induces an increase of the corrosion current. The galvanic corrosion of AISI 316L stainless steel in contact with different platinoids has been investigated by electrochemical and gravimetric techniques. Two types of tests were conducted in 1 mol/L nitric acid media at 80 deg C: (1) polarization curves and (2) immersion tests with either platinoid powders (Ru, Rh, Pd) or true insoluble dissolution fines (radioactive laboratory test). The results of the study have shown that even if galvanic coupling enhances the corrosion rate by about a factor 10 in these conditions, the corrosion behavior of AISI 316L remains low (a corrosion rate below 6 μm/year, few small intergranular indentations). No specific effect of irradiation and of elements contained in radioactive fines (other than Ru, Rh and Pd) was observed on corrosion behavior. A platinoids-ranking has also been established according to their coupling potential: Ru > Pd > Rh. (authors)

Corrosion by sulfate-reducing bacteria in a HP gas line under a detached weld cladding; Korrosion durch sulfatreduzierende Bakterien an einer Hochdruckgasleitung unter abgeloester Schweissnahtnachumhuellung

Energy Technology Data Exchange (ETDEWEB)

Bette, Ulrich [Technische Akademie Wuppertal (Germany)

2011-07-01

Intelligent pig measurements detected several points of corrosion in a HP gas pipeline in northern Germany. Corrosion occurred in a pipe section buried in clay soil, under detached weld claddings. It was not detected in regular measurements and additional intensive measurements. When the pipes were dug up, sulfate-reducing bacteria were found as the cause of corrosion. Due to the location of the corrosion processes, cathodic protection was impossible, and IFO measurements were ineffective in the low-ohmic soil.

Reducing Stress-Corrosion Cracking in Bearing Alloys

Science.gov (United States)

Paton, N. E.; Dennies, D. P.; Lumsden, I., J.b.

1986-01-01

Resistance to stress-corrosion cracking in some stainless-steel alloys increased by addition of small amounts of noble metals. 0.75 to 1.00 percent by weight of palladium or platinum added to alloy melt sufficient to improve properties of certain stainless steels so they could be used in manufacture of high-speed bearings.

Deposition and incorporation of corrosion product to primary coolant suppressing method

International Nuclear Information System (INIS)

Tsuzuki, Yasuo; Hasegawa, Naoyoshi; Fujioka, Tsunaaki.

1992-01-01

In a PWR type nuclear power plant, the concentration of dissolved nitrogen in primary coolants is increased by controlling the nitrogen partial pressure in a volume controlling tank gas phase portion or addition of water in a primary system water supply tank containing dissolved nitrogen to a primary system. Then ammonium is formed by a reaction with hydrogen dissolved in the primary coolants in the field of radiation rays, to control the concentration of ammonium in the coolants within a range from 0.5 to 3.5 ppm, and operate the power plant. As a result, deposition and incorporation of corrosion products to the structural materials of the primary system equipments during plant operation (pH 6.8 to 8.0) are suppressed. In other words, deposition of particulate corrosion products on the surface of fuel cladding tubes and the inner surface of pipelines in the primary system main equipments is prevented and incorporation of ionic radioactive corrosion products to the oxide membranes on the inner surface of the pipelines of the primary system main equipments is suppressed, to greatly reduce the radiation dose rate of the primary system pipelines. Thus, operator's radiation exposure can be decreased upon shut down of the plant. (N.H.)

Corrosion of Alloy 690 process pot by sulfate containing high level radioactive waste at feed stage

International Nuclear Information System (INIS)

Sengupta, P.; Soudamini, N.; Kaushik, C.P.; Jagannath; Mishra, R.K.; Kale, G.B.; Raj, K.; Das, D.; Sharma, B.P.

2008-01-01

Prolonged exposure of Alloy 690 process pot to sulfate containing high level radioactive waste leads to (a) depletion of Cr from the alloy, (b) intergranular attack and (c) building up of Cr 2 O 3 -Ni 2 O 3 -Fe 2 O 3 mixed oxide surface layer containing Na and Cs sulfate precipitates. Time dependence of material loss from Alloy 690 is found to follow a linear relationship of the type Δw (material loss) = -7.05 + 0.05t. Corrosion rate calculated for 2400 h exposure is 3.66 mpy. Cr and Ni leach rates obtained for the same sample are 1.61 g m -2 d -1 and 2.52 g m -2 d -1 , respectively. Ni leach rates followed a linear time dependence relationship of the type dNL Ni /dt (leach rate) = -0.09 + 0.027t, whereas Cr leach rates obeyed a non-linear relationship of the type dNL Cr /dt (leach rate) = 0.241 + 0.027t - 1.33 x 10 -4 t 1/2

A phenomenological approach to simulating the evolution of radioactive-waste container damage due to pitting corrosion

International Nuclear Information System (INIS)

Henshall, G.A.

1995-01-01

The damage to high-level radioactive-waste containers by pitting corrosion is an important design and performance assessment consideration. It is desirable to calculate the evolution of the pit depth distribution, not just the time required for initial penetration of the containers, so that the area available for advective of diffusive release of radionuclides through the container can be estimated. A phenomenological approach for computing the time evolution of these distributions is presented which combines elements of the deterministic and stochastic aspects of pit growth. The consistency of this approach with the mechanisms believed to control the evolution of the pit depth distribution is discussed. Qualitative comparisons of preliminary model predictions with a variety of experimental data from the literature are shown to be generally favorable. The sensitivity of the simulated distributions to changes in the input parameters is discussed. Finally, the results of the current model are compared to those of existing approaches based on extreme-value statistics, particularly regarding the extrapolation of laboratory data to large exposed surface areas

Erosion/corrosion concerns in feed preparation systems at the Defense Waste Processing Facility

International Nuclear Information System (INIS)

Gee, J.T.; Chandler, C.T.; Daugherty, W.L.; Imrich, K.J.; Jenkins, C.F.

1997-01-01

The Savannah River Site (SRS) has been operating a nuclear fuel cycle since the 1950's to produce nuclear materials in support of the national defense effort. The Department of Energy authorized the construction of the Defense Waste Processing Facility (DWPF) to immobilize the high level radioactive waste resulting from these processes as a durable borosilicate glass. The DWPF, after having undergone extensive testing, has been approved for operations and is currently immobilizing radioactive waste. To ensure reliability of the DWPF remote canyon processing equipment, a materials evaluation program was performed prior to radioactive operations to determine to what extent erosion/corrosion would impact design life of equipment. The program consisted of performing pre-service baseline inspections on critical equipment and follow-up inspections after completion of DWPF cold chemical demonstration runs. Non-destructive examination (NDE) techniques were used to assess erosion/corrosion as well as evaluation of corrosion coupon racks. These results were used to arrive at predicted equipment life for selected feed preparation equipment. It was concluded with the exception of the coil and agitator for the slurry mix evaporator (SME), which are exposed to erosive glass frit particles, all of the equipment should meet its design life

Operational improvement to the flue gas cleaning system in radioactive waste incineration facilities

International Nuclear Information System (INIS)

Zheng Bowen; Li Xiaohai; Wang Peiyi

2012-01-01

After years of operation, some problems, such as corrosion and waste water treatment, have been found in the first domestic whole-scale radioactive waste incineration facility. According to the origin of the problems, the flue gas cleaning system has been optimized and improved in terms of technical process, material and structure. It improves the operational stability, extends the equipment life-time, and also reduces the amount of secondary waste. In addition, as major sources of problems, waste management, operational experiences and information exchange deserve more attention. (authors)

Improvements in zirconium alloy corrosion resistance

International Nuclear Information System (INIS)

Kilp, G.R.; Thornburg, D.R.; Comstock, R.J.

1990-01-01

The corrosion rates of a series of Zircaloy 4 and Zr-Nb alloys were evaluated in long-term (exceeding 500 days in some cases) autoclave tests. The testing was done at various conditions including 633 K (680 F) water, 633 K (650 F) water, 633 k (680 F) lithiated water (70 PPM/0.01 molal lithium), and 673 K (750 F) steam. Materials evaluated are from the following three groups: (1) standard Zircaloy 4; (2) Zircaloy 4 with tightened controls on chemistry limits and heat-treatment history; and (3) Zr-Nb alloys. To optimize the corrosion resistance of the Zircaloy 4 material, the effects of specific chemistry controls (tighter limits on nitrogen, oxygen, silicon, carbon and tin) were evaluated. Also the effects of the thermal history, as measured by integrated annealing of ''A'' time were determined. The ''A'' times ranged from 0.1x10 -18 (h) to 46x10 -18 (h). A material referred to as ''Improved Zircaloy 4'', having optimized chemistry and ''A'' time levels for reduced corrosion, has been developed and tested. This material has a reduced and more uniform corrosion rate compared to the prior Zircaloy 4 material. Alternative alloys were also evaluated for potential improvement in cladding corrosion resistance. ZIRLO TM material was chosen for development and has been included in the long-term corrosion testing. Demonstration fuel assemblies using ZIRLO cladding are now operating in a commercial reactor. The results for the various test conditions and compositions are reported and the relative corrosion characteristics summarized. Based on the BR-3 data, there is a ranking correspondence between in-reactor corrosion and autoclave testing in lithiated water. In particular, the ZIRLO material has significantly improved relative corrosion resistance in the lithiated water tests. Reduced Zircaloy-4 corrosion rates are also obtained from the tighter controls on the chemistry (specifically lower tin, nitrogen, and carbon; higher silicon; and reduced oxygen variability) and ''A

Radiochemical studies on corrosion products of oral biomaterials

International Nuclear Information System (INIS)

Madbouly, H.A.Abdallah

1998-01-01

The work given in this thesis deals with a radioactive tracer study of the sorption of the corrosion products of dental amalgams and antimony on human teeth, porcelain and acrylic materials, used as dental restorative material. Sorption was investigated in presence of water and liquids commonly intaken by man; namely tea with or without sugar, soluble coffee ( Nescaffee) with or without sugar and/or milk, red tea (karkadeh or hibiscus) with or without sugar and chicken soup. The radioactive isotopes of Ag, Sn, Zn (amalgam components) and antimony were prepared by their irradiation in the nuclear reactor; 110m Ag, 113 Sn, 65 Zn and 124 Sb were thereby produced. The percent uptake of each studied element was evaluated from the depletion of radioactivity of the corresponding radioactive tracer in the given medium containing a tooth (human or artificial)

The formation, composition and structure of corrosion products in CANDU nuclear power reactors

International Nuclear Information System (INIS)

Rummery, T.E.

1978-01-01

To gain a better understanding of the formation and transport of corrosion products in CANDU-PHW power reactors, and the role played by these products in the generation and subsequent fixation of radioactive species, we have examined in detail several surfaces removed from the Douglas Point Generating Station (Douglas Point, Ontario). Results are given for the surface of the primary-side of a Monel-400 boiler tube, and surfaces of carbon steel piping at the inlet and outlet of the boiler. The experimental techniques that were used included sequential acid stripping, X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The corrosion products on the Monel-400 were mainly nickel, copper, nickel oxide and nickel-deficient nickel ferrite and varied in composition and quantity as a function of both distance from the boiler inlet, and depth in the corrosion layer. The radioactive cobalt ( 60 Co) content was localized in 'streaks' deposited in the straight sections of the boiler tube, but distributed uniformly over the whole surface in the downstream bend section. The material covering the carbon steel surface comprised three phases: magnetite, aluminosilicate particles at the outermost surface, and a mixed cation spinel phase uniformly distributed over the surface at the corrosion film-water interface. The formation, composition and structure of the corrosion products are discussed. (author)

Technical development for geological disposal of high-level radioactive wastes

International Nuclear Information System (INIS)

Asano, Hidekazu; Sugino, Hiroyuki; Kawakami, Susumu; Yamanaka, Yumiko

1997-01-01

Technical developments for geological disposal of high-level radioactive wastes materials research and design technique for engineered barriers (overpack and buffer material) were studied to evaluate more reliable disposal systems for high-level radioactive wastes. A lifetime prediction model for the maximum corrosion depth of carbon steel was developed. A preferable alloys evaluation method for crevice corrosion was established for titanium. Swelling pressure and water permeability of bentonite as a buffer material was measured, and coupled hydro-thermo-mechanical analysis code for bentonite was also studied. The CIP (cold isostatic pressing) method for monolithically formed buffer material was tested. A concept study on operation equipment for the disposal site was performed. Activities of microorganisms involved in underground performance were investigated. (author)

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

Case studies of corrosion of mixed waste and transuranic waste drums

International Nuclear Information System (INIS)

Kosiewicz, S.T.

1993-01-01

This paper presents three case studies of corrosion of waste drums at the Los Alamos National Laboratory (LANL). Corrosion was not anticipated by the waste generators, but occurred because of subtle chemical or physical mechanisms. In one case, drums of a cemented transuranic (TRU) sludge experienced general and pitting corrosion. In the second instance, a chemical from a commercial paint stripper migrated from its primary containment drums to chemically attack overpack drums made of mild carbon steel. In the third case, drums of mixed low level waste (MLLW) soil corroded drum packaging even though the waste appeared to be dry when it was placed in the drums. These case studies are jointly discussed as ''lessons learned'' to enhance awareness of subtle mechanisms that can contribute to the corrosion of radioactive waste drums during interim storage

Impact of microbial activity on the radioactive waste disposal: long term prediction of biocorrosion processes.

Science.gov (United States)

Libert, Marie; Schütz, Marta Kerber; Esnault, Loïc; Féron, Damien; Bildstein, Olivier

2014-06-01

This study emphasizes different experimental approaches and provides perspectives to apprehend biocorrosion phenomena in the specific disposal environment by investigating microbial activity with regard to the modification of corrosion rate, which in turn can have an impact on the safety of radioactive waste geological disposal. It is found that iron-reducing bacteria are able to use corrosion products such as iron oxides and "dihydrogen" as new energy sources, especially in the disposal environment which contains low amounts of organic matter. Moreover, in the case of sulphate-reducing bacteria, the results show that mixed aerobic and anaerobic conditions are the most hazardous for stainless steel materials, a situation which is likely to occur in the early stage of a geological disposal. Finally, an integrated methodological approach is applied to validate the understanding of the complex processes and to design experiments aiming at the acquisition of kinetic data used in long term predictive modelling of biocorrosion processes. © 2013.

A study on Prediction of Radioactive Source-term from the Decommissioning of Domestic NPPs by using CRUDTRAN Code

Energy Technology Data Exchange (ETDEWEB)

Song, Jong Soon; Lee, Sang Heon; Cho, Hoon Jo [Department of Nuclear Engineering Chosun University, Gwangju (Korea, Republic of)

2016-10-15

For the study, the behavior mechanism of corrosion products in the primary system of the Kori no.1 was analyzed, and the volume of activated corrosion products in the primary system was assessed based on domestic plant data with the CRUDTRAN code used to predict the volume. It is expected that the study would be utilized in predicting radiation exposure of workers performing maintenance and repairs in high radiation areas and in selecting the process of decontaminations and decommissioning in the primary system. It is also expected that in the future it would be used as the baseline data to estimate the volume of radioactive wastes when decommissioning a nuclear plant in the future, which would be an important criterion in setting the level of radioactive wastes used to compute the quantity of radioactive wastes. The results of prediction of the radioactive nuclide inventory in the primary system performed in this study would be used as baseline data for the estimation of the volume of radioactive wastes when decommissioning NPPs in the future. It is also expected that the data would be important criteria used to classify the level of radioactive wastes to calculate the volume. In addition, it is expected that the data would be utilized in reducing radiation exposure of workers in charge of system maintenance and repairing in high radiation zones and also predicting the selection of decontaminations and decommissioning processes in the primary systems. In future researches, it is planned to conduct the source term assessment against other NPP types such as CANDU and OPR-1000, in addition to the Westinghouse type nuclear plants.

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 ...

Microbially influenced corrosion: studies on enterobacteria isolated from seawater environment and influence of toxic metals on bacterial biofilm and bio-corrosion

Energy Technology Data Exchange (ETDEWEB)

Bermond-Tilly, D.; Pineau, S.; Dupont-Morral, I. [Corrodys, 50 - Equeurdreville (France); Janvier, M.; Grimont, P.A.D. [Institut Pasteur, Unite BBPE, 75 - Paris (France)

2004-07-01

Full text of publication follows: The most widely involved bacteria in Microbially Induced Corrosion (MIC usually called bio-corrosion) are sulfate/thiosulfate-reducing bacteria. The sulfate-reducing bacteria (SRB) are major contributors to the anaerobic bio-corrosion of steel. However, corrosion process of pipelines (or off shores platforms) was found to be associated with many other bacteria. These bacteria are able to produce sulfides from the reduction of thiosulfate in anaerobic conditions. By this way, a thiosulfate-reducing non sulfate-reducing bacteria, Dethiosulfovibrio peptidovorans, showed a significant corrosive activity similar to or higher than that recorded for SRB involved in bio-corrosion, (Magot et al., 1997). Furthermore, a bacteria, Citrobacter amalonaticus, which belongs to the family of the Enterobacteriaceae, is involved in severe pitting corrosion process (Angeles Chavez et al., 2002). Recently, some bacteria (Citrobacter freundii, Proteus mirabilis and Klebsiella planticola characterized as belonging to the family of Enterobacteriaceae) were isolated from biofilm developed on carbon steel coupons immersed in natural seawater. The latter bacteria were also associated in severe pitting corrosion process on carbon steel coupons (Bermond-Tilly et al., 2003). Biofilm forms a protective layer, reducing the exposure of the metal surface to the external environment. However, bacteria included in the biofilm could also cause localized corrosion by consuming cathodic hydrogen from the steel or by producing corrosive metabolic end products and by the Extracellular Polymeric Substances (EPS) production. Thus, EPS can also play an important role in the corrosion of the metals (e.g. can complex metal ions). However, sulfate/thiosulfate-reducing bacteria and some Enterobacteria are highly efficient to bioremediation by precipitation of toxic metals from wastewater as metal sulfides. Recently it was shown that toxic metal may be involved in the formation

Study on radioactive corrosion products behaviour in primary circuits of JOYO

International Nuclear Information System (INIS)

Iizawa, Katsuyuki; Suzuki, Soju; Tamura, Masaaki; Seki, Seiichi; Hikichi, Takayoshi

1987-01-01

Radioactive CP deposition and distribution, and the resulting radiation fields along the JOYO primary circuit piping have been measured. The measurement results have been compared with calculations for estimating radioactive CP behaviour and the resulting radiation fields in an LMFBR primary circuit using a computer code which is named PSYCHE. The deposited radioactivity of CPs calculated by using PSYCHE agreed well with the measured results within a factor of 0.5-2. The gamma dose rate distribution calculated from the PSYCHE results reproduced measured values within a factor of 0.6-2 over the piping system, using the JOANDARC modification of the QAD-CG code. Using these verified codes, a prediction of radiation levels for future plant operation, and an evaluation of methods for the reduction of radioactive CPs have been conducted. (orig./DG)

Effect of self-glazing on reducing the radioactivity levels of red mud based ceramic materials

Energy Technology Data Exchange (ETDEWEB)

Qin, Shuo [College of Material Science and Engineering, Guilin University of Technology, Guilin, Guangxi 541004 (China); Wu, Bolin, E-mail: wubolin3211@gmail.com [College of Material Science and Engineering, Guilin University of Technology, Guilin, Guangxi 541004 (China)

2011-12-30

Graphical abstract: Self-glazing red mud based ceramic materials (RMCM) were produced by normal pressure sintering process using the main raw materials of red mud. The properties of the RMCM samples were investigated by the measurements of mechanical properties, radiation measurement, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the self-glazing RMCM have good mechanical properties (water absorption and apparent porosity approached zero; bulk density, 2.94 g/cm{sup 3}; compressive strength, 78.12 MPa). The radiation level has clear change regularity that the radioactivity levels of red mud (6360 Bq) are obvious declined, and can be reduced to that of the natural radioactive background of Guilin Karst landform, China (3600 Bq). It will not only consume large quantities of red mud, but also decrease the production cost of self-glazing RMCM. And the statement of this paper will offer effective ways to reduce the radioactivity level of red mud. Highlights: Black-Right-Pointing-Pointer The self-glazing phenomenon in red mud system was first discovered in our research. Black-Right-Pointing-Pointer Radiation levels of red mud can be reduced efficiently by self-glazing layer. Black-Right-Pointing-Pointer Red mud based ceramic materials will not cause harm to environment and humans. Black-Right-Pointing-Pointer This research possesses important economic significances to aluminum companies. - Abstract: Self-glazing red mud based ceramic materials (RMCM) were produced by normal pressure sintering process using the main raw materials of red mud. The properties of the RMCM samples were investigated by the measurements of mechanical properties, radiation measurement, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the self-glazing RMCM have good mechanical properties (water absorption and apparent porosity approached zero; bulk density, 2.94 g/cm{sup 3}; compressive strength, 78.12 MPa). The radiation

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

International Nuclear Information System (INIS)

Kursten, B.

2009-01-01

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

TRU drum corrosion task team report

Energy Technology Data Exchange (ETDEWEB)

Kooda, K.E.; Lavery, C.A.; Zeek, D.P.

1996-05-01

During routine inspections in March 1996, transuranic (TRU) waste drums stored at the Radioactive Waste Management Complex (RWMC) were found with pinholes and leaking fluid. These drums were overpacked, and further inspection discovered over 200 drums with similar corrosion. A task team was assigned to investigate the problem with four specific objectives: to identify any other drums in RWMC TRU storage with pinhole corrosion; to evaluate the adequacy of the RWMC inspection process; to determine the precise mechanism(s) generating the pinhole drum corrosion; and to assess the implications of this event for WIPP certifiability of waste drums. The task team investigations analyzed the source of the pinholes to be Hcl-induced localized pitting corrosion. Hcl formation is directly related to the polychlorinated hydrocarbon volatile organic compounds (VOCs) in the waste. Most of the drums showing pinhole corrosion are from Content Code-003 (CC-003) because they contain the highest amounts of polychlorinated VOCs as determined by headspace gas analysis. CC-001 drums represent the only other content code with a significant number of pinhole corrosion drums because their headspace gas VOC content, although significantly less than CC-003, is far greater than that of the other content codes. The exact mechanisms of Hcl formation could not be determined, but radiolytic and reductive dechlorination and direct reduction of halocarbons were analyzed as the likely operable reactions. The team considered the entire range of feasible options, ranked and prioritized the alternatives, and recommended the optimal solution that maximizes protection of worker and public safety while minimizing impacts on RWMC and TRU program operations.

TRU drum corrosion task team report

International Nuclear Information System (INIS)

Kooda, K.E.; Lavery, C.A.; Zeek, D.P.

1996-05-01

During routine inspections in March 1996, transuranic (TRU) waste drums stored at the Radioactive Waste Management Complex (RWMC) were found with pinholes and leaking fluid. These drums were overpacked, and further inspection discovered over 200 drums with similar corrosion. A task team was assigned to investigate the problem with four specific objectives: to identify any other drums in RWMC TRU storage with pinhole corrosion; to evaluate the adequacy of the RWMC inspection process; to determine the precise mechanism(s) generating the pinhole drum corrosion; and to assess the implications of this event for WIPP certifiability of waste drums. The task team investigations analyzed the source of the pinholes to be Hcl-induced localized pitting corrosion. Hcl formation is directly related to the polychlorinated hydrocarbon volatile organic compounds (VOCs) in the waste. Most of the drums showing pinhole corrosion are from Content Code-003 (CC-003) because they contain the highest amounts of polychlorinated VOCs as determined by headspace gas analysis. CC-001 drums represent the only other content code with a significant number of pinhole corrosion drums because their headspace gas VOC content, although significantly less than CC-003, is far greater than that of the other content codes. The exact mechanisms of Hcl formation could not be determined, but radiolytic and reductive dechlorination and direct reduction of halocarbons were analyzed as the likely operable reactions. The team considered the entire range of feasible options, ranked and prioritized the alternatives, and recommended the optimal solution that maximizes protection of worker and public safety while minimizing impacts on RWMC and TRU program operations

Corrosion particles in the primary coolant of VVER-440 reactors

International Nuclear Information System (INIS)

Vajda, N.; Molnar, Z.; Macsik, Z.; Szeles, E.; Hargittai, P.; Csordas, A.; Pinter, T.; Pinter, T.

2010-01-01

Corrosion and activity build-up processes are of major concern in ageing and life-extension of nuclear power reactors. Researches to study the migration of radioactive corrosion particles have been initiated at Paks Nuclear Power Plant (NPP), Hungary in order to better understand the corrosion of the primary circuit surfaces, the transport and activation of the particles of corrosion origin and their deposition on in-core and out-of-core surfaces. Radioactive corrosion particles were collected from the primary coolant and the steam generator surfaces of the 4 reactor units and subjected to detailed microanalytical and radioanalytical investigations. Scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX) were used to study the morphology and the composition of the matrix elements in the particles and the deposited corrosion layers. Particles identified by SEM-EDX were re-located under optical microscope by means of a coordinate transformation algorithm and were separated with a micromanipulator for further studies. Activities of γ emitting radionuclides were determined by high resolution γ spectrometry, and those of β decaying isotopes were measured by liquid scintillation (LS) spectrometry after radiochemical processing. High sensitivity of the nuclear measuring techniques allowed us to determine the low activity concentrations of the long-lived radionuclides, i.e. 60 Co, 54 Mn, 63 Ni, 55 Fe in the individual particles. Finally, high resolution sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) was applied to determine the ultralow concentrations of Co, Fe, Ni in the same particles. Specific activities of 60 Co/Co, 54 Mn/Fe, 55 Fe/Fe and 63 Ni/Ni were derived from the measured activity and concentration data. Specific activities of the radioactive corrosion products reveal the history of activity buildup processes in the particle. Typically, Fe-Cr-Ni oxide particles formed as a result of corrosion of the steel

Corrosion of a carbon steel in simulated liquid nuclear wastes

International Nuclear Information System (INIS)

Saenz Gonzalez, Eduardo

2005-01-01

This work is part of a collaboration agreement between CNEA (National Atomic Energy Commission of Argentina) and USDOE (Department of Energy of the United States of America), entitled 'Tank Corrosion Chemistry Cooperation', to study the corrosion behavior of carbon steel A537 class 1 in different simulated non-radioactive wastes in order to establish the safety concentration limits of the tank waste chemistry at Hanford site (Richland-US). Liquid high level nuclear wastes are stored in tanks made of carbon steel A537 (ASTM nomenclature) that were designed for a service life of 20 to 50 years. A thickness reduction of some tank walls, due to corrosion processes, was detected at Hanford site, beyond the existing predicted values. Two year long-term immersion tests were started using non radioactive simulated liquid nuclear waste solutions at 40 C degrees. This work extends throughout the first year of immersion. The simulated solutions consist basically in combinations of the 10 most corrosion significant chemical components: 5 main components (NaNO 3 , NaCl, NaF, NaNO 2 and NaOH) at three concentration levels and 5 secondary components at two concentration levels. Measurements of the general corrosion rate with time were performed for carbon steel coupons, both immersed in the solutions and in the vapor phases, using weight loss and electrochemistry impedance spectroscopy techniques. Optic and scanning electron microscopy examination, analysis of U-bend samples and corrosion potential measurements, were also done. Localized corrosion susceptibility (pitting and crevice corrosion) was assessed in isolated short-term tests by means of cyclic potentiodynamic polarization curves. The effect of the simulated waste composition on the corrosion behavior of A537 steel was studied based on statistical analyses. The Surface Response Model could be successfully applied to the statistical analysis of the A537 steel corrosion in the studied solutions. General corrosion was not

Study on transition behavior of corrosion related environment near disposal site

International Nuclear Information System (INIS)

Masuda, K.; Nakanishi, T.; Kato, O.; Wada, R.

2005-01-01

Full text of publication follows: Disposal vessels are desired to stand for a certain period of time to stabilize radioactive wastes containing heat-generating substances. Besides, in case of wastes containing irradiated metal, which is a source of long-lived 14 C, long-term capability to enclose such long-life species is desired to the vessels. Since endurance of vessels is very affected by surrounding environment, evaluation of long-term environmental transition is important. In this study, we focused on the behavior of red-ox conditions and pH by reactive transport modeling in order to obtain fundamental knowledge about long-term transition of corrosion-related environment around metal vessels or metal-containing radioactive wastes. A two-dimensional reactive transport simulation was applied to a modeled repository site with engineering barrier system including cement and bentonite, etc., in consideration of following chemical models: - The metal corrosion rate was modeled to consider its effect on red-ox conditions. - The corrosion rate of carbon steel was modeled as kinetic reaction rate of production of ferrous ion and electrons as a function of pH and oxygen concentration, based on the experimental results observed under highly-controlled reducing conditions (1). - Formation of corrosion products was modeled by solubility products of iron oxides, such as magnetite, according to analytical results by in-situ XPS (2). - Cement composition and its reaction with groundwater were modeled by chemical equilibrium of primary and secondary minerals, for example, calcium silicates with several C/S ratios to consider the long-term transition of pH with cement degradations. According to the simulation results, the variation of red-ox conditions and pH around the disposal vessels has been estimated. Main component of cement composition slowly changes to calcium silicate having lower C/S ratios, resulting in decrease of pH. Although it depends on the bentonite efficiency

Corrosion resistance of tank material for flock storage in the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Sano, Yuichi; Anbai, Hiromu; Takeuchi, Masayuki; Ogino, Hideki; Koizumi, Kenji

2014-01-01

The installation of the storage tank made of SS400 is under planning in the Fukushima Daiichi nuclear power plant for the flock which was generated in the coagulation process for radioactive contaminated water. The flock contains the seawater and has a possibility to make a crevice and local corrosion on the surface of the tank. Air agitation will be applied in the storage tank to prevent the accumulation of the flock and hydrogen generated by radiolysis, which will increase the diffusion of oxygen and the corrosion of SS400. In addition, the effect of radiation from the flock on the corrosion should be considered. In this study, we investigated the corrosion behavior of SS400 in the flock under the aeration-agitation condition with γ-ray irradiation. Based on the flock storage condition announced by Tokyo Electric Power Company (TEPCO), immersion tests were performed with SS400 coupons under several conditions and corrosion rates were estimated by the weight loss of the coupons. After the immersion tests, the surfaces of the coupons were observed by microscopy for evaluating the local corrosion. To evaluate corrosion mechanism in detail, electrochemical tests were also carried out. In all of these tests, the non-radioactive flock as a surrogate and artificial seawater were used. Corrosion rates of SS400 increased significantly with aeration flow rates in the seawater with/without the flock, but this tendency was weaker in the seawater with the flock, especially under the condition where coupons were buried in the flock. The electrochemical tests indicated the suppression of the cathodic reaction, i.e. dissolved oxygen reduction, in the seawater with the flock. The effect of γ-ray irradiation on the corrosion rates was not remarkable under the assumed dose rate. Microscopic analysis of the immersed coupons showed no severe corrosion including local corrosion occurred. The corrosion rate could be decreased effectively by suppressing the dissolved oxygen reduction

Factors affecting the release of radioactivity to the biosphere during deep geologic disposal of radioactive solids through underground water

International Nuclear Information System (INIS)

Solomah, A.G.

1984-01-01

The chemical alteration formed by ground water on the solidified radioactive waste during deep geologic disposal represents the most likely mechanism by which dangerous radioactive species could be reintroduced into the biosphere. Knowing the geologic history of the repository, the chemistry of the ground water and the mechanisms involved in the corrosion of the radioactive solids can provide help to predict the long-term stability of these materials. The factors that must be considered in order to assess the safety and the risk associated with such a disposal strategy are presented. The leaching behavior of a solidified radioactive waste form called SYNROC-B (SYNthetic ROCks) is discussed. Different simulated ground water brines similar to those of the repository sites were prepared and used as the leaching media in leaching experiments

Inhibiting mild steel corrosion from sulfate-reducing bacteria using antimicrobial-producing biofilms in Three-Mile-Island process water.

Science.gov (United States)

Zuo, R; Ornek, D; Syrett, B C; Green, R M; Hsu, C-H; Mansfeld, F B; Wood, T K

2004-04-01

Biofilms were used to produce gramicidin S (a cyclic decapeptide) to inhibit corrosion-causing, sulfate-reducing bacteria (SRB). In laboratory studies these biofilms protected mild steel 1010 continuously from corrosion in the aggressive, cooling service water of the AmerGen Three-Mile-Island (TMI) nuclear plant, which was augmented with reference SRB. The growth of both reference SRB (Gram-positive Desulfosporosinus orientis and Gram-negative Desulfovibrio vulgaris) was shown to be inhibited by supernatants of the gramicidin-S-producing bacteria as well as by purified gramicidin S. Electrochemical impedance spectroscopy and mass loss measurements showed that the protective biofilms decreased the corrosion rate of mild steel by 2- to 10-fold when challenged with the natural SRB of the TMI process water supplemented with D. orientis or D. vulgaris. The relative corrosion inhibition efficiency was 50-90% in continuous reactors, compared to a biofilm control which did not produce the antimicrobial gramicidin S. Scanning electron microscope and reactor images also revealed that SRB attack was thwarted by protective biofilms that secrete gramicidin S. A consortium of beneficial bacteria (GGPST consortium, producing gramicidin S and other antimicrobials) also protected the mild steel.

Study of the accumulation and distribution of the radioactivity in the cooling circuit of the BOR-60 reactor

International Nuclear Information System (INIS)

Kizin, V.D.; Konyashov, V.V.; Lisitsyn, E.S.; Polyakov, V.I.; Chechetkin, Yu.V.

1976-04-01

The results of measurements of the radioactivity of the coolant and the deposits in the primary circuit of the BOR-60 reactor during its five years of operation are discussed. The values calculated for the exposure dose rate from the piping system and the contribution of the γ-radiation from the corrosion and fission product nuclides are given. The efficiency of coolant draining from the pipes in reducing the dose rate is estimated. (orig.) [de

Radioactivity of long-lived nuclides in the primary circuit of the reactor BOR-60 during operation with defective fuel elements

International Nuclear Information System (INIS)

Gryazev, V.M.; Kizin, V.D.; Lisitsyn, E.S.; Polyakov, V.I.; Chechetkin, Y.V.

1978-06-01

The summarized results of measurements of the enrichment and distribution of radioactive nuclides from corrosion and of fission products during the four years of operation of BOR-60, including a longer period of operation with detective fuel elements in the core, are presented. It is shown that for operation with approximately 1% leaking fuel rods radiation exposure becomes worse manily because of release and enrichment of cesium isotopes in the coolant. Of the other fission products, the largest contribution to the dose rate in pipework and components is given by 140 Ba / 140 La and 95 Nb. On operation with 0.1 to 0.2% of leaking fuel rods, this contribution is comparable to that of the corrosion products 60 Co and 54 Mn. The radioactivity of corrosion products in the circuit has not increased within the last three years and was about one order of magnitude lower than the theoretical values. The corrosion and fission products are nonuniformly distributed over the circuit. Concentration of 95 Nb and 60 Co in the pipe for 'cold' sodium is larger by a factor of 2 - 5 and of 140 Ba and 54 Mn by a factor of 10-20 than in the pipes for 'hot' sodium. Most of the cobalt was found to deposit in the heat exchanges. The effectiveness of emptying the pipes from coolant in order to reduce the dose sate is assessed. (orig.) [de

Corrosion of barrier materials in seawater environments

International Nuclear Information System (INIS)

Heiser, J.H.; Soo, P.

1995-07-01

A brief review has been carried out on the performance of barrier materials for low-level radioactive wastes in seawater environments. The environments include those for shallower coastal waters as well as the deep ocean (down to 3800 m). The review is mainly focused on metallic materials since they are the most common for seawater service and they have the largest data base. Information from the literature is usually pertinent to shallower coastal locations, but there is a valuable source of corrosion data obtained from several studies of metallic specimens exposed to ocean-bed conditions. In addition, the corrosion of carbon steel barriers has been evaluated for actual waste containers that were retrieved from previously-used disposal sites in the Atlantic and Pacific Oceans. Of the metallic materials studied, carbon steel showed the least corrosion resistance. Failure by non-uniform attack in a typical waste container could occur in as little as 25 y in some ocean environments ' Penetration by local attack, such as pitting and crevice corrosion resistance was also observed for more expensive materials such as low-alloy steels, stainless steels, titanium alloys, zirconium alloys, copper alloys, nickel alloys, aluminum alloys, and lead alloys

Aspects of a Co-free hardfacing Materials Development to Reduce the Radioactivity in NPPs

Energy Technology Data Exchange (ETDEWEB)

Kim, Joung Soo; Kim, Hong Pyo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Suh, Jeong Hun [Inss Tek Co., Daejeon (Korea, Republic of)

2007-07-01

For the last one or two decades, active researches to develop Co-free hardfacing materials in order to replace Co-base stellite alloys have been done to reduce the radioactivity in the primary systems in nuclear power plants(NPPs). However, Co-free materials having superior mechanical properties to stellite alloys have not been developed up to now. There are two ways to increase the performance characteristics of the key parts needed to be coated with hardfacing materials, thus resulting in replacing the Co-base stellite alloys with superior mechanical properties; one of them is to develop new Co-free materials with a better quality in performance than that of satellite alloys. The other is to use new coating techniques developed to increase the coated surface properties of already developed Co-free materials. In this study, the aspect of newly developed Co-free materials is reviewed and the necessity of the development of new Co-free materials is emphasized for the replacement of Co-base satellite alloys. In addition, a new coating technique, which is called a laser hardfacing(cladding) technique(LHT), is introduced and its advantage and applicability to the key parts in NPPs are discussed using our experimental results to improve the properties of a surface coated with existing Co-free hardfacing materials. The coating technique using a laser beam having a high energy density has unique advantages to obtain various microstructures such as crystalline, amorphous, porous, and nano structures and also to get coating layers having high a hardness to result in an excellent resistance to erosion corrosion and wear.

On the corrosion behaviour of stainless steel, nickel-chromium and zirconium-alloys in pore water of Portland cement

International Nuclear Information System (INIS)

Heitz, E.; Graefen, H.

1991-12-01

On the basis of an extensive review of literature and available experience, an evaluation was made of the corrosion of a metallic matrix for radioactive nuclides embedded in porous, water containing Portland cement. As a metallic matrix, austenitic high-alloy steel, nickel-base alloys and zirconium alloys are discussed. Pore waters in Portland cement have low aggressivity. However, through contact with formation water, chloride and sulphate enrichment can occur. Although corrosion is principally possible on the basis of purely thermodynamic considerations, it can be assumed that local corrosion (pitting, stress corrosion cracking, intergranular corrosion) is highly improbable under the given boundary conditions. This is valid for all three groups of alloys and means that only low release rates of corrosion products are to be expected. As a result of the discussion on radiolysis-induced corrosion, additional corrosion activity can be excluded. Final conclusions concerning the stimulation of corrosion processes by microbial action cannot be drawn and, therefore, additional experiments are proposed. The release rates of radioactive products are controlled by a very low dissolution rate of the materials in the passive state. All three groups of alloys show this type of general dissolution. From a survey of literature data it can be concluded that release rates greater than 250 mg/m 2 per day are not exceeded. Since these data were mainly obtained by electrochemical methods, it is proposed that quantitative analytical investigations of the corrosion products in pore water be made. On the whole the release rates determined are far below corrosion rates which are generally technically relevant. (author) 13 figs., 9 tabs., 61 refs

Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

International Nuclear Information System (INIS)

Bickford, D.F.; Congdon, J.W.; Oblath, S.B.

1987-01-01

At the U.S. Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assess the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition

Corrosion assessment of refractory materials for high temperature waste vitrification

International Nuclear Information System (INIS)

Marra, J.C.; Congdon, J.W.; Kielpinski, A.L.

1995-01-01

A variety of vitrification technologies are being evaluated to immobilize radioactive and hazardous wastes following years of nuclear materials production throughout the Department of Energy (DOE) complex. The compositions and physical forms of these wastes are diverse ranging from inorganic sludges to organic liquids to heterogeneous debris. Melt and off-gas products can be very corrosive at the high temperatures required to melt many of these waste streams. Ensuring material durability is required to develop viable treatment processes. Corrosion testing of materials in some of the anticipated severe environments is an important aspect of the materials identification and selection process. Corrosion coupon tests on typical materials used in Joule heated melters were completed using glass compositions with high salt contents. The presence of chloride in the melts caused the most severe attack. In the metal alloys, oxidation was the predominant corrosion mechanism, while in the tested refractory material enhanced dissolution of the refractory into the glass was observed. Corrosion testing of numerous different refractory materials was performed in a plasma vitrification system using a surrogate heterogeneous debris waste. Extensive corrosion was observed in all tested materials

Corrosion of container and infrastructure materials under clay repository conditions

International Nuclear Information System (INIS)

Debruyn, W.; Dresselaers, J.; Vermeiren, P.; Kelchtermans, J.; Tas, H.

1991-01-01

With regard to the disposal of high-level radioactive waste, it was recommended in a IAEA Technical Committee meeting to perform tests in realistic environments corresponding with normal and accidental conditions, to qualify and apply corrosion monitoring techniques for corrosion evaluation under real repository conditions and to develop corrosion and near-field evolution models. The actual Belgian experimental programme for the qualification of a container for long-term HLW storage in clay formations complies with these recommendations. The emphasis in the programme is indeed on in situ corrosion testing and monitoring and on in situ control of the near-field chemistry. Initial field experiments were performed in a near-surface clay quarry at Terhaegen. Based on a broad laboratory material screening programme and in agreement with the Commission of the European Communities, three reference materials were chosen for extensive in situ overpack testing. Ti/0.2 Pd and Hastelloy C-4 were chosen as reference corrosion resistant materials and a low-carbon steel as corrosion allowance reference material. This report summarizes progress made in the material qualification programme since the CEC contract of 1983-84. 57 Figs.; 15 Tabs.; 18 Refs

Task E container corrosion studies: Annual report. Revision 1

International Nuclear Information System (INIS)

Bunnell, L.R.; Doremus, L.A.; Topping, J.B.; Duncan, D.R.

1994-06-01

The Pacific Northwest Laboratory is conducting the Solid Waste Technology Support Program (SWTSP) for Westinghouse Hanford Company (WHC). Task E is the Container Corrosion Study Portion of the SWTSP that will perform testing to provide defensible data on the corrosion of low-carbon steel, as used in drums to contain chemical and radioactive wastes at the Hanford Site. A second objective of Task E is to provide and test practical alternative materials that have higher corrosion resistance than low-carbon steel. The scope of work for fiscal year (FY) 1993 included initial testing of mild steel specimens buried in Hanford soils or exposed to atmospheric corrosion in metal storage sheds. During FY 1993, progress was made in three areas of Task E. First, exposure of test materials began at the Soil Corrosion Test Site where low-carbon steel specimens were placed in the soil in five test shafts at depths of 9 m (30 ft). Second, the corrosion measurement of low-carbon steel in the soil of two solid waste trenches continued. The total exposure time is ∼ 500 days. Third, an atmospheric corrosion test of low-carbon steel was initiated in a metal shed (Building 2401-W) in the 200 West Area. This annual report describes the Task E efforts and provides a current status

The roles of the micro-organisms and chromium content in the corrosion of iron-chromium steels in the presence of sulfate-reducing bacteria

International Nuclear Information System (INIS)

Ferrante, V.

1991-09-01

If it is widely accepted that the presence of sulfate-reducing bacteria can increase the aqueous corrosion of steels, the induced mechanisms are still not definitively established. The aim of this work is to specify the roles, for corrosion, of the presence of bacteria (D. Vulgaris) in one part and of chemical parameters as the composition of the material and the accumulation of sulfides in another part. The use of experimental techniques coming from microbiology, electrochemistry or chemical analysis has revealed the interdependence which exists between the bacteria and the material, and the importance of the steel composition towards the adhesion of microorganisms and the generalized corrosion. The bacteria and the dissolved sulfides do not seem to influence remarkably the generalized corrosion. Nevertheless, the alterations of the surface state they induce could be the cause of localized corrosion phenomena. (O.M.)

The roles of the micro-organisms and chromium content in the corrosion of iron-chromium steels in the presence of sulfate-reducing bacteria

International Nuclear Information System (INIS)

Ferrante, V.

1991-12-01

Although the ability of sulfate-reducing bacteria to enhance the corrosion of steel is now widely accepted, the actual processes involved in such phenomena are still discussed. This work is dedicated to the study of the exact roles played in corrosion processes firstly, by the presence of D. vulgaris cells and, secondly, by chemical factors such as the material composition and the accumulation of sulfide ions in the solution. The use of microbiological, electrochemical and analytical experimental techniques lead to results that show the interdependence of the bacteria and the material as well as the importance of the steel composition in the adhesion of the micro-organisms and the general corrosion rates. The bacteria cells and dissolved sulfide ions do not markedly influence the general corrosion rates. They however induce surface state modifications that can result in localized corrosion phenomena

Analysis of corrosion products of carbon steel in wet bentonite

International Nuclear Information System (INIS)

Osada, Kazuo; Nagano, Tetsushi; Nakayama, Shinichi; Muraoka, Susumu

1992-02-01

As a part of evaluation of the long-term durability for the overpack containers for high-level radioactive waste, we have conducted corrosion tests for carbon steel in wet bentonite, a candidate buffer material. The corrosion rates were evaluated by weight difference of carbon steel and corrosion products were analyzed by Fourier transform infrared spectroscopy (FT-IR) and colorimetry. At 40degC, the corrosion rate of carbon steel in wet bentonite was smaller than that in pure water. At 95degC, however, the corrosion rate in wet bentonite was much higher than that in pure water. This high corrosion rate in wet bentonite at 95degC was considered to result from evaporation of moisture in bentonite in contact with the metal. This evaporation led to dryness and then to shrinkage of the bentonite, which generated ununiform contact of the metal with bentonite. Probably, this ununiform contact promoted the local corrosion. The locally corroded parts of specimen in wet bentonite at 95degC were analyzed by Fourier transform infrared microspectroscopy (micro-FT-IR), and lepidocrocite γ-FeO(OH) was found as well as goethite α-FeO(OH). In wet bentonite at 95degC, hematite α-Fe 2 O 3 was identified by means of colorimetry. (author)

LIQUID AIR INTERFACE CORROSION TESTING FOR FY2010

International Nuclear Information System (INIS)

Zapp, P.

2010-01-01

An experimental study was undertaken to investigate the corrosivity to carbon steel of the liquid-air interface of dilute simulated radioactive waste solutions. Open-circuit potentials were measured on ASTM A537 carbon steel specimens located slightly above, at, and below the liquid-air interface of simulated waste solutions. The 0.12-inch-diameter specimens used in the study were sized to respond to the assumed distinctive chemical environment of the liquid-air interface, where localized corrosion in poorly inhibited solutions may frequently be observed. The practical inhibition of such localized corrosion in liquid radioactive waste storage tanks is based on empirical testing and a model of a liquid-air interface environment that is made more corrosive than the underlying bulk liquid due to chemical changes brought about by absorbed atmospheric carbon dioxide. The chemical changes were assumed to create a more corrosive open-circuit potential in carbon in contact with the liquid-air interface. Arrays of 4 small specimens spaced about 0.3 in. apart were partially immersed so that one specimen contacted the top of the meniscus of the test solution. Two specimens contacted the bulk liquid below the meniscus and one specimen was positioned in the vapor space above the meniscus. Measurements were carried out for up to 16 hours to ensure steady-state had been obtained. The results showed that there was no significant difference in open-circuit potentials between the meniscus-contact specimens and the bulk-liquid-contact specimens. With the measurement technique employed, no difference was detected between the electrochemical conditions of the meniscus versus the bulk liquid. Stable open-circuit potentials were measured on the specimen located in the vapor space above the meniscus, showing that there existed an electrochemical connection through a thin film of solution extending up from the meniscus. This observation supports the Hobbs-Wallace model of the development

Ultra thin layer activation by recoil implantation of radioactive heavy ions. Applicability in wear and corrosion studies

International Nuclear Information System (INIS)

Lacroix, O.; Sauvage, T.; Blondiaux, G.; Guinard, L.

1997-07-01

A new calibration procedure is proposed for the application of recoil implantation of radioactive heavy ions (energies between a few hundred keV and a few MeV) into the near surface of materials as part of a research programme on sub-micrometric wear or corrosion phenomena. The depth profile of implanted radioelements is performed by using ultra thin deposited films obtained by cathode sputtering under argon plasma. Two curves for 56 Co ion in nickel have been determined for implantation depths of 110 and 200 nm, respectively, and stress the feasibility and reproducibility of this method for such activated depths. The achieved surface loss detection sensitivities are about 1 and 2 nm respectively. The on line detection mode is performed directly on the sample of interest. A general description of the method is presented. A study of the reaction kinematics followed by a general treatment on the irradiation parameters to be adopted are also developed with the intention of using the ultra thin layer activation method (UTLA) to further applications in research and industry. (author)

WASTE PACKAGE CORROSION STUDIES USING SMALL MOCKUP EXPERIMENTS

International Nuclear Information System (INIS)

B.E. Anderson; K.B. Helean; C.R. Bryan; P.V. Brady; R.C. Ewing

2005-01-01

The corrosion of spent nuclear fuel and subsequent mobilization of radionuclides is of great concern in a geologic repository, particularly if conditions are oxidizing. Corroding A516 steel may offset these transport processes within the proposed waste packages at the Yucca Mountain Repository (YMR) by retaining radionuclides, creating locally reducing conditions, and reducing porosity. Ferrous iron, Fe 2+ , has been shown to reduce UO 2 2+ to UO 2(s) [1], and some ferrous iron-bearing ion-exchange materials adsorb radionuclides and heavy metals [2]. Of particular interest is magnetite, a potential corrosion product that has been shown to remove TcO 4 - from solution [3]. Furthermore, if Fe 2+ minerals, rather than fully oxidized minerals such as goethite, are produced during corrosion, then locally reducing conditions may be present. High electron availability leads to the reduction and subsequent immobilization of problematic dissolved species such as TcO 4 - , NpO 2 + , and UO 2 2+ and can also inhibit corrosion of spent nuclear fuel. Finally, because the molar volume of iron material increases during corrosion due to oxygen and water incorporation, pore space may be significantly reduced over long time periods. The more water is occluded, the bulkier the corrosion products, and the less porosity is available for water and radionuclide transport. The focus of this paper is on the nature of Yucca Mountain waste package steel corrosion products and their effects on local redox state, radionuclide transport, and porosity

A Theoretical Model for Metal Corrosion Degradation

Directory of Open Access Journals (Sweden)

David V. Svintradze

2010-01-01

Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.

Radioactive recontamination on mechanically polished piping at Shimane-1 Nuclear Power Plant

International Nuclear Information System (INIS)

Umeda, K.; Komoto, I.; Imamura, K.; Kataoka, I.; Uchida, S.

1998-01-01

In a series of preventive maintenance tasks for an aging plant, recirculation pipes of Shimane-1 NPP have been replaced by newly fabricated type 316 NG stainless steel pipes. Suppression of shutdown dose rate caused by 60 Co recontamination on the newly replaced piping was one of the major concerns in the recirculation pipe replacement. In order to suppress the shutdown dose rate, control of the 60 Co deposition rate coefficient as well as 60 Co radioactivity in the reactor water are essential. The deposition rate coefficient depends on surface roughness. The coefficient is suppressed by reduction of the effective surface area of pipes through mechanical polishing. Then the inner surface of the pipes was polished mechanically to reduce roughness prior to application in the plant. After measuring and evaluating radioactive recontamination, it was estimated that deposited amounts of radioactive corrosion products on the pipe inner surface would reach the saturated value in a few years, and would not exceed the level before replacement unless water chemistry is degraded. (author)

Colloids from the aqueous corrosion of uranium nuclear fuel

Science.gov (United States)

Kaminski, M. D.; Dimitrijevic, N. M.; Mertz, C. J.; Goldberg, M. M.

2005-12-01

Colloids may enhance the subsurface transport of radionuclides and potentially compromise the long-term safe operation of the proposed radioactive waste repository at Yucca Mountain. Little data is available on colloid formation for the many different waste forms expected to be buried in the repository. This work expands the sparse database on colloids formed during the corrosion of metallic uranium nuclear fuel. We characterized spherical UO 2 and nickel-rich montmorilonite smectite-clay colloids formed during the corrosion of uranium metal fuel under bathtub conditions at 90 °C. Iron and chromium oxides and calcium carbonate colloids were present but were a minor population. The estimated upper concentration of the UO 2 and clays was 4 × 10 11 and 7 × 10 11-3 × 10 12 particles/L, respectively. However, oxygen eventually oxidized the UO 2 colloids, forming long filaments of weeksite K 2(UO 2) 2Si 6O 15 · 4H 2O that settled from solution, reducing the UO 2 colloid population and leaving predominantly clay colloids. The smectite colloids were not affected by oxygen. Plutonium was not directly observed within the UO 2 colloids but partitioned completely to the colloid size fraction. The plutonium concentration in the colloidal fraction was slightly higher than the value used in the viability assessment model, and does not change in concentration with exposure to oxygen. This paper provides conclusive evidence for single-phase radioactive colloids composed of UO 2. However, its impact on repository safety is probably small since oxygen and silica availability will oxidize and effectively precipitate the UO 2 colloids from concentrated solutions.

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)

A new method for decontamination of radioactive waste using low-pressure arc discharge

International Nuclear Information System (INIS)

Fujiwara, Kazutoshi; Furukawa, Shizue; Adachi, Kazuo; Amakawa, Tadashi; Kanbe, Hiromi

2006-01-01

In this paper, the decontamination features of the low-pressure arc-discharge method for radioactive waste generated in the operation and maintenance of nuclear power plants were examined. The low-pressure arc-discharge method was applied to type 304 stainless-steel, type 316L stainless-steel, alloy 600 and carbon-steel covered with radioactive corrosion products. Approximately, 80% of the radioactivity build up on stainless-steels could be removed by the low-pressure arc discharge

Design considerations of fission and corrosion product in primary system of MONJU

International Nuclear Information System (INIS)

Yanagisawa, T.; Akagane, K.; Yamamoto, K.; Kawashima, K.

1976-01-01

General influence of fission and corrosion products in primary system on MONJU plant design is reviewed. Various research and development works are now in progress to decrease the generation rate, to remove the products more effectively and to develop the methods of evaluation the behaviour of radioactive products. The inventory and distribution of fission and corrosion products in the primary circuit of MONJU are given. The radiation levels on the primary components are estimated to be several roentgens per hour. (author)

Geological disposal of heat generating radioactive waste

International Nuclear Information System (INIS)

1986-03-01

A number of options for the disposal of vitrified heat-generating radioactive waste are being studied to ensure that safe methods are available when the time comes for disposal operations to commence. This study has considered the feasibility of three designs for containers which would isolate the waste from the environment for a minimum period of 500 to 1000 years. The study was sub-divided into the following major sections: manufacturing feasibility; stress analysis; integrity in accidents; cost benefit review. The candidate container designs were taken from the results of a previous study by Ove Arup and Partners (1985) and were developed as the study progressed. Their major features can be summarised as follows: (A) a thin-walled corrosion-resistant metal shell filled with lead or cement grout. (B) an unfilled thick-walled carbon steel shell. (C) an unfilled carbon steel shell planted externally with corrosion-resistant metal. Reference repository conditions in clay, granite and salt, reference disposal operations and metals corrosion data have been taken from various European Community radioactive waste management research and engineering projects. The study concludes that design Types A and B are feasible in manufacturing terms but design Type C is not. It is recommended that model containers should be produced to demonstrate the proposed methods of manufacture and that they should be tested to validate the analytical techniques used. (author)

Corrosion resistance of titanium alloy on the overpack for high-level radioactive waste disposal

International Nuclear Information System (INIS)

Nishimura, Toshiyasu

2008-01-01

Crevice corrosion of titanium and its alloys were investigated in 10% sodium chloride at 100 degC simulating the environment of the overpack near the seaside. The pH and Chloride ion concentration inside the crevice were monitored by using W/WO 3 and Ag/AgCl microelectrode, respectively. The pH and Cl - concentration within the crevice were calculated from the standard potential-pH and potential-log [Cl - ] calibration curves. The effect of Mo on the crevice corrosion of titanium was mainly studied. The passivation behavior of the titanium and Ti-15% Mo alloy were also studied using electrochemical impedance studies. A marginal decrease in pH and increase in Cl - ion concentration were observed for pure titanium at 100 degC, where there was large increase of the crevice current. On other hand, there was no apparent change in pH and Cl - ion activity inside the crevice for Ti-15% Mo alloy, where there was no increase of the crevice current. Based on the results, it has been documented that the Ti-15% Mo alloy was not susceptible to crevice corrosion in 10% NaCl solutions at 100 degC. The corrosion reaction resistance (R t ) was found to increase with addition of Mo as an alloying element and also increase with applied anodic potential. Hence, Mo is able to be an effective alloying element, which enhanced the crevice corrosion resistance of titanium under the environment simulating the overpack near the seaside. (author)

Geological disposal of heat generating radioactive waste

International Nuclear Information System (INIS)

1985-02-01

A study has been made of the requirements and design features for containers to isolate vitrified heat generating radioactive waste from the environment for a period of 500 to 1000 years. The requirements for handling, storing and transporting containers have been identified following a study of disposal operations, and the pressures and temperatures which may possibly be experienced in clay, granite and salt formations have been estimated. A range of possible container designs have been proposed to satisfy the requirements of each of the disposal environments. Alternative design concepts in corrosion resistant or corrosion allowance material have been suggested. Potentially suitable container shell materials have been selected following a review of corrosion studies and although metals have not been specified in detail, titanium alloys and low carbon steels are thought to be appropriate for corrosion resistant and corrosion allowance designs respectively. Performance requirements for container filler materials have been identified and candidate materials assessed. A preliminary container stress analysis has shown the importance of thermal modelling and that if lead is used as a filler it dominates the stress response of the container. Possible methods of manufacturing disposal containers have been assessed and found to be generally feasible. (author)

Ocean disposal of heat generating radioactive waste

International Nuclear Information System (INIS)

1984-12-01

A study of container designs for heat generating radioactive waste disposal in the deep ocean sediments is presented. The purpose of the container would be to isolate the waste from the environment for a period of 500 to 1000 years. The container designs proposed are based on the use of either corrosion allowance or corrosion resistant metals. Appropriate overpack wall thicknesses are suggested for each design using the results of corrosion studies and experiments but these are necessarily preliminary and data relevant to corrosion in deep ocean sediments remain sparse. It is concluded that the most promising design concept involves a thin titanium alloy overpack in which all internal void spaces are filled with lead or cement grout. In situ temperatures for the sediment adjacent to the emplaced 50 year cooled waste containers are calculated to reach about 260 deg C. The behaviour of the sediments at such a high temperature is not well understood and the possibility of 100 years interim storage is recommended for consideration to allow further cooling. Further corrosion data and sediment thermal studies would be required to fully confirm the engineering feasibility of these designs. (author)

Corrosion Cost and Corrosion Map of Korea - Based on the Data from 2005 to 2010

International Nuclear Information System (INIS)

Kim, Y. S.; Lim, H. K.; Kim, J. J.; Hwang, W. S.; Park, Y. S.

2011-01-01

Corrosion of metallic materials occurs by the reaction with corrosive environment such as atmosphere, marine, soil, urban, high temperature etc. In general, reduction of thickness and cracking and degradation are resulted from corrosion. Corrosion in all industrial facilities and infrastructure causes large economic losses as well as a large number of accidents. Economic loss by corrosion has been reported to be nearly 1-6% of GNP or GDP. In order to reduce corrosion damage of industrial facilities, corrosion map as well as a systematic investigation of the loss of corrosion in each industrial sector is needed. The Corrosion Science Society of Korea in collaboration with 15 universities and institutes has started to survey on the cost of corrosion and corrosion map of Korea since 2005. This work presents the results of the survey on cost of corrosion by Uhlig, Hoar, and input-output methods, and the evaluation of atmospheric corrosion rate of carbon steel, weathering steel, galvanized steel, copper, and aluminum in Korea. The total corrosion cost was estimated in terms of the percentage of the GDP of industry sectors and the total GDP of Korea. According to the result of Input/output method, corrosion cost of Korea was calculated as 2.9% to GDP (2005). Time of wetness was shown to be categories 3 to 4 in all exposure areas. A definite seasonal difference was observed in Korea. In summer and fall, time of wetness was higher than in other seasons. Because of short exposure period (12 months), significant corrosion trends depending upon materials and exposure corrosion environments were not revealed even though increased mass loss and decreased corrosion rate by exposure time

DPC materials and corrosion environments.

Energy Technology Data Exchange (ETDEWEB)

Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

2014-10-01

After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

Modelling gas generation in radioactive waste repositories

International Nuclear Information System (INIS)

Agg, P.J.

1993-02-01

In a repository containing low- and intermediate-level waste, gas generation will occur principally by the coupled processes of metal corrosion and microbial degradation of cellulosic waste. This Paper describes a mathematical model design to address gas generation by these mechanisms. The metal corrosion model incorporates a three-stage process encompassing both aerobic and anaerobic corrosion regimes; the microbial degradation model simulates the activities of eight different microbial populations, which are maintained as functions both of pH and of the concentrations of particular chemical species. Gas concentrations have been measured over a period of three years in large-scale drum experiments designed to simulate repository conditions. Model predictions are confirmed against the experimental measurements, and a prediction is then made of gas concentrations and generation rates over an assessment period of one million years in a radioactive waste repository. (author)

Modelling gas generation in radioactive waste repositories

International Nuclear Information System (INIS)

Agg, P.J.

1992-07-01

In a repository containing low- and intermediate-level waste, gas generation will occur principally by the coupled processes of metal corrosion and microbial degradation of cellulosic waste. This paper describes a mathematical model designed to address gas generation by these mechanisms. The metal corrosion model incorporates a three-stage process encompassing both aerobic and anaerobic corrosion regimes; the microbial degradation model simulates the activities of eight different microbial populations, which are maintained as functions both of pH and of the concentrations of particular chemical species. Gas concentrations have been measured over a period of three years in large-scale drum experiments designed to simulate repository conditions. Model predictions are confirmed against the experimental measurements, and a prediction is then made of gas concentrations and generation rates over an assessment period of one million years in a radioactive waste repository. (Author)

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

The characteristics of corrosion, radiation degradation and dissolution of titanium alloys

International Nuclear Information System (INIS)

Sung, K. W.; Na, J. W.; Choi, B. S.; Lee, D. J.; Chang, M. H.

2001-12-01

In order to establish the technical bases of water chemistry design requirement related titanium alloys, we investigated the characteristics of corrosion, activation, radiation degradation, radiation hydrogen embrittlement of titanium alloys and dissolution of titanium dioxide. Titanium alloys generally have high corrosion resistance. Corrosion product release from PT-7M and PT-3V titanium alloy surface for 18 months of operation is negligible, and the corrosion penetration for about 30 years is about 1 μm, while the corrosion rates is not higher than one third of that of austenitic steel. Titanium only converts into Sc-46 with 85 day halflife after neutron irradiation, and its radioactivity is not higher than one thousandth of that produced from nickel. Therefore, under the condition without any neutron irradiation, the radiation damage of titanium alloys would have no problem. Titanium dioxide, that protects the metals from the corrosion, has retrograde solubility in neutral solutions. It does not form any complexes with ligands such as ammonia, but Ti(IV) gets more stable by complexing with water molecules. In conclusion, it is estimated that titanium alloys such as PT-7M would be applicable to steam generator materials

Radioactive wastes processing and disposing container

International Nuclear Information System (INIS)

Wada, Jiro; Kato, Hiroaki.

1987-01-01

Purpose: To obtain a processing and disposing container at low level radioactive wastes, excellent in corrosion and water resistance, as well as impact shock resistance for the retrieval storage over a long period of time. Constitution: The container is constituted with sands and pebbles as aggregates and glass fiber-added unsaturated polyester resins as binders. The container may entirely be formed with such material or only the entire inner surface may be formed with the material as liners. A container having excellent resistance to water, chemicals, freezing or melting, whether impact shock, etc. can be obtained, thereby enabling retrieval storage for radioactive wastes at the optimum low level. (Takahashi, M.)

Suppression of aqueous corrosion of La(Fe0.88Si0.12)13 by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

International Nuclear Information System (INIS)

Fujieda, S.; Fukamichi, K.; Suzuki, S.

2014-01-01

Highlights: • The aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe 0.88 Si 0.12 ) 13 becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe 0.88 Si 0.12 ) 13 in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration

Corrosion life-time assessment of carbon steel and stainless alloys for geological disposal facility

International Nuclear Information System (INIS)

Kosaki, Akio; Komada, Hiroya

1993-01-01

The disposal facility for radioactive wastes requires long-term integrity. Metal is being considered for use as the engineered barrier which constructs the outer walls in such a facility, in order to prevent groundwater percolation. Thus, the most important problem for the integrity of the engineered barrier is corrosion by groundwater. There are two ways for using metal as an engineered barrier; one is as a structural material; and the other is as the inner-lining material of a concrete wall. This report discusses the corrosion lifetime assessment of carbon steel used as a structural and lining material, and stainless alloys, Type 304 steel and Titanium alloys used as lining materials. Corrosion potential and crevice corrosion are measured in the environment of neutral and alkalized water

Treatment of radioactive silts and soils with organic materials

International Nuclear Information System (INIS)

Sobolev, I.A.; Barinov, A.S.; Dmitriev, S.A.; Lifanov, F.A.; Varlakov, A.P.; Karlin, S.V.

1997-01-01

Moscow SIA RADON is developing the ''Clinker'' method to treat radioactive silts and grounds. The ''Clinker'' method consists of radioactive silt (ground) mixed with lime and other components. This mixture is calcined at 800 to 1000 o C. The product is ground to a surface area size of 2500 to 4500 cm 2 /g, mixed with water at a water-to-cement ratio not less than 0.25, and aged to form a solid monolith. The ''Clinker'' method was compared to the traditional cementation methods. The ''Clinker'' method reduces the final volume and enhance the strength characteristics of the final product. The ''Clinker'' cement compound has higher hardening rate. Preliminary data show that it has higher cold resistance, sulfate and leaching corrosion durability in comparison to one prepared by the traditional cementation method. The range of applicability of the ''Clinker'' method is increased by the possibility of treating materials containing up to 80% (mass) of organic materials, such as turf, flora and fauna decomposition products, and manmade material, including natural materials, such as petroleum products and polymers. In addition, the ''Clinker'' method does not require expensive waste binders, i.e., cement. The ''Clinker'' cement can be used for cementation of other radioactive waste. (author)

Long Term Corrosion/Degradation Test Six Year Results

Energy Technology Data Exchange (ETDEWEB)

M. K. Adler Flitton; C. W. Bishop; M. E. Delwiche; T. S. Yoder

2004-09-01

The Subsurface Disposal Area (SDA) of the Radioactive Waste Management Complex (RWMC) located at the Idaho National Engineering and Environmental Laboratory (INEEL) contains neutron-activated metals from non-fuel, nuclear reactor core components. The Long-Term Corrosion/Degradation (LTCD) Test is designed to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements to the environment. The test is using two proven, industry-standard methods—direct corrosion testing using metal coupons, and monitored corrosion testing using electrical/resistance probes—to determine corrosion rates for various metal alloys generally representing the metals of interest buried at the SDA, including Type 304L stainless steel, Type 316L stainless steel, Inconel 718, Beryllium S200F, Aluminum 6061, Zircaloy-4, low-carbon steel, and Ferralium 255. In the direct testing, metal coupons are retrieved for corrosion evaluation after having been buried in SDA backfill soil and exposed to natural SDA environmental conditions for times ranging from one year to as many as 32 years, depending on research needs and funding availability. In the monitored testing, electrical/resistance probes buried in SDA backfill soil will provide corrosion data for the duration of the test or until the probes fail. This report provides an update describing the current status of the test and documents results to date. Data from the one-year and three-year results are also included, for comparison and evaluation of trends. In the six-year results, most metals being tested showed extremely low measurable rates of general corrosion. For Type 304L stainless steel, Type 316L stainless steel, Inconel 718, and Ferralium 255, corrosion rates fell in the range of “no reportable” to 0.0002 mils per year (MPY). Corrosion rates for Zircaloy-4 ranged from no measurable corrosion to 0.0001 MPY. These rates are two orders of magnitude lower than those specified in

Rail base corrosion and cracking prevention

Science.gov (United States)

2014-07-01

Rail base corrosion combined with fatigue or damage can significantly reduce rail life. Studies were done to examine the relative contribution of damage, corrosion, and fatigue on rail life. The combined effects can be separated into constituent fact...

Electrochemical noise based corrosion monitoring: FY 2001 final report

International Nuclear Information System (INIS)

EDGAR, C.

2001-01-01

Underground storage tanks made of mild steel are used to contain radioactive waste generated by plutonium production at the Hanford Site. Corrosion of the walls of these tanks is a major issue. Corrosion monitoring and control are currently provided at the Hanford Site through a waste chemistry sampling and analysis program. In this process, tank waste is sampled, analyzed and compared to a selection of laboratory exposures of coupons in simulated waste. Tank wall corrosion is inferred by matching measured tank chemistries to the results of the laboratory simulant testing. This method is expensive, time consuming, and does not yield real-time data. Corrosion can be monitored through coupon exposure studies and a variety of electrochemical techniques. A small number of these techniques have been tried at Hanford and elsewhere within the DOE complex to determine the corrosivity of nuclear waste stored in underground tanks [1]. Coupon exposure programs, linear polarization resistance (LPR), and electrical resistance techniques have all been tried with limited degrees of success. These techniques are most effective for monitoring uniform corrosion, but are not well suited for early detection of localized forms of corrosion such as pitting and stress corrosion cracking (SCC). Pitting and SCC have been identified as the most likely modes of corrosion failure for Hanford Double Shell Tanks (DST'S) [2-3]. Over the last 20 years, a new corrosion monitoring system has shown promise in detecting localized corrosion and measuring uniform corrosion rates in process industries [4-20]. The system measures electrochemical noise (EN) generated by corrosion. The term EN is used to describe low frequency fluctuations in current and voltage associated with corrosion. In their most basic form, EN-based corrosion monitoring systems monitor and record fluctuations in current and voltage over time from electrodes immersed in an environment of interest. Laboratory studies and field

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

International Nuclear Information System (INIS)

Helie, Max

2015-01-01

This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the

Development of a process to reduce the uranium concentration of liquid radioactive waste

International Nuclear Information System (INIS)

Fuentealba Toro, Edgardo David

2015-01-01

The purpose of radioactive waste management is to prevent the discharge of waste into the biosphere, a function carried out in Chile by the Chilean Nuclear Energy Commission (CCHEN), which stores around 500 [L] of these organic and inorganic waste in cans coming from research of Universities and CCHEN' laboratories. Within the inorganic liquid waste are concentrations of Uranyl salts with sulfates, chlorides and phosphates. The purpose of this work is to develop at laboratory level a process to concentrate and precipitate uranium salts (Sulfate and Uranyl Chloride) present in radioactive liquid effluents, because in the case of these very long period wastes in liquid state, the most widely used processes are aimed at concentrating or extracting radioactive compounds through separation processes, for their conditioning and final storage under conditions whose radiological risk is minimized. The selected process is liquid-liquid extraction, being evaluated solvents such as benzene and kerosene with the following extractants: tri-n-octylphosphine oxide (TOPO), di-2-ethylhexyl phosphoric acid (DEHPA) and Cyanex© 923. To determine the extraction conditions, which allow to reduce the concentration of uranium to values lower than 10 ppm, the extractant concentration was modified from 0.05 to 0.41 [M] with solvent volume / residue (VO/VA) ratios of 0.2 to 0.5, at an initial concentration of 8,446 [gU/L] and subsequent precipitation of uranium extracted by a reaction with ammonium carbonate. From these experimental tests the maximum extraction conditions were determined. To the generated effluents, a second stage of extraction was necessary in order to reduce its concentration below 10 [mg / L]. The experimental tests allowed to reduce the concentration under 2.5 [mgU/L], equivalent to 99.97% extraction efficiency. The tests with Cyanex© 923 in replacement of the TOPO, allowed to obtain similar results and even better in some cases, due to the fact that final

Sedimentibacter sp. With corrosive capability, Ferric-reducing, isolated from an oil separation tank

International Nuclear Information System (INIS)

Lopez-Jimenez, G.; Loera, O.; Ramirez, F.; Monroy, O.; Fernandez-Linares, L. C.

2009-01-01

Bio corrosion is a common problem in oil and gas industry facilities. characterization of the microbial populations responsible for bio corrosion and the interactions between different microorganisms with metallic surfaces is required in order to implemented efficient monitoring and control strategies. (Author)

Design of second generation Hanford tank corrosion monitoring system

International Nuclear Information System (INIS)

Edgemon, G.L.

1998-01-01

The Hanford Site has 177 underground waste tanks that store approximately 253 million liters of radioactive waste from 50 years of plutonium production. Twenty-eight tanks have a double shell and are constructed of welded ASTM A537-Class 1 (UNS K02400), ASTM A515-Grade 60 (UNS K02401), or ASTM A516-Grade 60 (UNS K02100) material. The inner tanks of the double-shell tanks (DSTS) were stress relieved following fabrication. One hundred and forty-nine tanks have a single shell, also constructed of welded mild steel, but not stress relieved following fabrication. Tank waste is in liquid, solid, and sludge forms. Tanks also contain a vapor space above the solid and liquid waste regions. The composition of the waste varies from tank to tank but generally has a high pH (>12) and contains sodium nitrate, sodium hydroxide, sodium nitrite, and other minor radioactive constituents resulting from plutonium separation processes. Leaks began to appear in the single-shell tanks shortly after the introduction of nitrate-based wastes in the 1950s. Leaks are now confirmed or suspected to be present in a significant number of single-shell tanks. The probable modes of corrosion failures are reported as nitrate stress corrosion cracking (SCC) and pitting. Previous efforts to monitor internal corrosion of waste tank systems have included linear polarization resistance (LPR) and electrical resistance techniques. These techniques are most effective for monitoring uniform corrosion, but are not well suited for detection of localized corrosion (pitting and SCC). The Savannah River Site (SRS) investigated the characterization of electrochemical noise (EN) for monitoring waste tank corrosion in 1993, but the tests were not conclusive. The SRS effort has recently been revived and additional testing is underway. For many years, EN has been observed during corrosion and other electrochemical reactions, and the phenomenon is well established. Typically, EN consists of low frequency (< 1 Hz) and

Redesign of negatively charged 111In-DTPA-octreotide derivative to reduce renal radioactivity.

Science.gov (United States)

Oshima, Nobuhiro; Akizawa, Hiromichi; Kawashima, Hidekazu; Zhao, Songji; Zhao, Yan; Nishijima, Ken-Ichi; Kitamura, Yoji; Arano, Yasushi; Kuge, Yuji; Ohkura, Kazue

2017-05-01

Radiolabeled octreotide derivatives have been studied as diagnostic and therapeutic agents for somatostatin receptor-positive tumors. To prevent unnecessary radiation exposure during their clinical application, the present study aimed to develop radiolabeled peptides which could reduce radioactivity levels in the kidney at both early and late post-injection time points by introducing a negative charge with an acidic amino acid such as L-aspartic acid (Asp) at a suitable position in 111 In-DTPA-conjugated octreotide derivatives. Biodistribution of the radioactivity was evaluated in normal mice after administration of a novel radiolabeled peptide by a counting method. The radiolabeled species remaining in the kidney were identified by comparing their HPLC data with those obtained by alternative synthesis. The designed and synthesized radiolabeled peptide 111 In-DTPA-d-Phe -1 -Asp 0 -d-Phe 1 -octreotide exhibited significantly lower renal radioactivity levels than those of the known 111 In-DTPA-d-Phe 1 -octreotide at 3 and 24h post-injection. The radiolabeled species in the kidney at 24h after the injection of new octreotide derivative represented 111 In-DTPA-d-Phe-OH and 111 In-DTPA-d-Phe-Asp-OH as the metabolites. Their radiometabolites and intact 111 In-DTPA-conjugated octreotide derivative were observed in urine within 24h post-injection. The present study provided a new example of an 111 In-DTPA-conjugated octreotide derivative having the characteristics of both reduced renal uptake and shortened residence time of radioactivity in the kidney. It is considered that this kinetic control was achieved by introducing a negative charge on the octreotide derivative thereby suppressing the reabsorption in the renal tubules and affording the radiometabolites with appropriate lipophilicity. Copyright © 2017 Elsevier Inc. All rights reserved.

Redesign of negatively charged 111In-DTPA-octreotide derivative to reduce renal radioactivity

International Nuclear Information System (INIS)

Oshima, Nobuhiro; Akizawa, Hiromichi; Kawashima, Hidekazu; Zhao, Songji; Zhao, Yan; Nishijima, Ken-ichi; Kitamura, Yoji; Arano, Yasushi; Kuge, Yuji; Ohkura, Kazue

2017-01-01

Introduction: Radiolabeled octreotide derivatives have been studied as diagnostic and therapeutic agents for somatostatin receptor-positive tumors. To prevent unnecessary radiation exposure during their clinical application, the present study aimed to develop radiolabeled peptides which could reduce radioactivity levels in the kidney at both early and late post-injection time points by introducing a negative charge with an acidic amino acid such as L-aspartic acid (Asp) at a suitable position in 111 In-DTPA-conjugated octreotide derivatives. Methods: Biodistribution of the radioactivity was evaluated in normal mice after administration of a novel radiolabeled peptide by a counting method. The radiolabeled species remaining in the kidney were identified by comparing their HPLC data with those obtained by alternative synthesis. Results: The designed and synthesized radiolabeled peptide 111 In-DTPA-D-Phe −1 -Asp 0 -D-Phe 1 -octreotide exhibited significantly lower renal radioactivity levels than those of the known 111 In-DTPA-D-Phe 1 -octreotide at 3 and 24 h post-injection. The radiolabeled species in the kidney at 24 h after the injection of new octreotide derivative represented 111 In-DTPA-D-Phe-OH and 111 In-DTPA-D-Phe-Asp-OH as the metabolites. Their radiometabolites and intact 111 In-DTPA-conjugated octreotide derivative were observed in urine within 24 h post-injection. Conclusion: The present study provided a new example of an 111 In-DTPA-conjugated octreotide derivative having the characteristics of both reduced renal uptake and shortened residence time of radioactivity in the kidney. It is considered that this kinetic control was achieved by introducing a negative charge on the octreotide derivative thereby suppressing the reabsorption in the renal tubules and affording the radiometabolites with appropriate lipophilicity.

Pitting corrosion of copper. Further model studies

International Nuclear Information System (INIS)

Taxen, C.

2002-08-01

The work presented in this report is a continuation and expansion of a previous study. The aim of the work is to provide background information about pitting corrosion of copper for a safety analysis of copper canisters for final deposition of radioactive waste. A mathematical model for the propagation of corrosion pits is used to estimate the conditions required for stationary propagation of a localised anodic corrosion process. The model uses equilibrium data for copper and its corrosion products and parameters for the aqueous mass transport of dissolved species. In the present work we have, in the model, used a more extensive set of aqueous and solid compounds and equilibrium data from a different source. The potential dependence of pitting in waters with different compositions is studied in greater detail. More waters have been studied and single parameter variations in the composition of the water have been studied over wider ranges of concentration. The conclusions drawn in the previous study are not contradicted by the present results. However, the combined effect of potential and water composition on the possibility of pitting corrosion is more complex than was realised. In the previous study we found what seemed to be a continuous aggravation of a pitting situation by increasing potentials. The present results indicate that pitting corrosion can take place only over a certain potential range and that there is an upper potential limit for pitting as well as a lower. A sensitivity analysis indicates that the model gives meaningful predictions of the minimum pitting potential also when relatively large errors in the input parameters are allowed for

The effects of sulphate reducing bacteria on the corrosion of mild steel embedded in a bentonite-granitic groundwater paste

International Nuclear Information System (INIS)

Philp, J.C.; Taylor, K.J.

1987-08-01

Preliminary experiments were set up to investigate how the corrosion of forged 0.2% carbon steel is affected by the presence of sulphate reducing bacteria (SRB). The tests used cultures of a thermophilic bacterium Desulphotomaculum nigrificans mixed with bentonite and synthetic groundwater, to simulate a bacteria contaminated backfill, and placed in contact with carbon steel disc specimens held in perspex cells at 50 0 C under anaerobic conditions. The rate of corrosion with exposure was monitored by electrochemical techniques, together with changes in near field redox potential, during the course of the tests. After 340 days exposure the test cells were dismantled to measure the nature and extent of any corrosion that had occurred and to assess the residual SRB content of the bentonite. Recovery of relatively large numbers of bacteria after almost a year's incubation at 50 0 C in this moderately alkaline (pH 9.5) medium has confirmed the pH tolerance of the strain. There was evidence of the initiation of enhanced corrosion occurring in at least two of the five cells that contained SRB, at about three times the rate of the control. This was probably associated with the presence of SRB despite the nutritionally poor environment which existed in the bentonite gel. (author)

The effects of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1991-11-01

This report assesses the possible effects of colloidal corrosion products on the transport of actinides from the near field of radioactive waste repositories. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium was studied under conditions simulating a transition from near-field to far-field environmental conditions. Desorption of actinides occurred slowly from the colloids under far-field conditions. Measurements of particle stability showed all the colloids to be unstable in the near field. Stability increased under far-field conditions or as a result of the evolution of the near field. Migration of colloids from the near field is unlikely except in the presence of organic materials. (Author)

Reducing Risks from Sealed Radioactive Sources in Medicine

International Nuclear Information System (INIS)

2014-01-01

Sealed radioactive sources are commonly used in a variety of medical applications for both diagnosis and therapy. The sources used in medical applications usually have high levels of radioactivity and, therefore, have the potential to cause serious and life threatening injuries if used improperly or maliciously, or risky if they become lost or are stolen

Method of solidifying radioactive waste by plastics

International Nuclear Information System (INIS)

Yasumura, Keijiro; Tomita, Toshihide.

1976-01-01

Purpose: To prevent leakage of radioactivity by providing corrosion-resistant layer on the inner surface of a waste container for radioactive waste. Constitution: The inner periphery and bottom of a drum can is lined with an non-flammable cloth of such material as asbestos. This drum is filled with a radioactive waste in the form of powder or pellets. Then, a mixture of a liquid plastic monomer and a polymerization starting agent is poured at a normal temperature, and the surface is covered with a non-flammable cloth. The plastic monomer and radioactive waste are permitted to impregnate the non-flammable cloth and are solidified there. Thus, even if the drum can is corroded at the sea bottom after disposal it in the ocean, it is possible to prevent the waste from permeating into the outer sea water because of the presence of the plastic layer on the inside. Styrene is used as the monomer. (Aizawa, K.)

Corrosion behavior of corrosion resistant alloys in stimulation acids

Energy Technology Data Exchange (ETDEWEB)

Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

2004-07-01

some superficial cracks at the highest test temperature (140 deg. C), which may have been environmentally induced. A sensible increment of general corrosion was observed in the test with spent mud acid when the pH was reduced from 5 to 4 and 3.5, respectively. (authors)

Coating NiTi archwires with diamond-like carbon films: reducing fluoride-induced corrosion and improving frictional properties.

Science.gov (United States)

Huang, S Y; Huang, J J; Kang, T; Diao, D F; Duan, Y Z

2013-10-01

This study aims to coat diamond-like carbon (DLC) films onto nickel-titanium (NiTi) orthodontic archwires. The film protects against fluoride-induced corrosion and will improve orthodontic friction. 'Mirror-confinement-type electron cyclotron resonance plasma sputtering' was utilized to deposit DLC films onto NiTi archwires. The influence of a fluoride-containing environment on the surface topography and the friction force between the brackets and archwires were investigated. The results confirmed the superior nature of the DLC coating, with less surface roughness variation for DLC-coated archwires after immersion in a high fluoride ion environment. Friction tests also showed that applying a DLC coating significantly decreased the fretting wear and the coefficient of friction, both in ambient air and artificial saliva. Thus, DLC coatings are recommended to reduce fluoride-induced corrosion and improve orthodontic friction.

In-pile loop experiments in water chemistry and corrosion

International Nuclear Information System (INIS)

Kysela, J.

1986-09-01

Results on the study of Zr-1% Nb alloy corrosion, in out-of and in-pile loops simulating the working conditions of the VVER-440 reactor (Soviet, PWR type), covered the time period May 1982-April 1986 were reported, as well as, results on transport and filtration of corrosion products. Methods and techniques used in the study included remote measurement of corrosion rate by polarizing resistance, out-of-pile loop at the temperature 350 deg. C, pressure 19 MPa, circulation 20 kgs/h and in-pile water loop with constant flow rate 10,000 kgs/h, pressure 16 MPa, temperature 330 deg. C and neutron flux 7x10 13 n/cm 2 .s. It was shown that solid suspended particles with chemical composition corresponding most frequently to magnetite or nickelous ferrite, though with non-stoichiometric composition Me x 2+ Fe 3- x 3+ O 4 were found. Continuous filtration of water by means of electromagnetic filter leads to a decrease of radioactivity of the outer epitactic layer only. Effect of filtration on the inner topotactic layer is negligible. The corrosion rates for the above-mentioned parameters are given

Corrosion of steel drums containing immobilized ion exchange-resins and incineration ashes

International Nuclear Information System (INIS)

Marotta, F.; Schulz Rodriguez, F.M.; Farina, Silvia B.; Duffo, Gustavo S.

2009-01-01

The Argentine Atomic Energy Commission (CNEA) is responsible for developing the management nuclear waste disposal programme. This programme contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The proposed model is a near-surface monolithic repository similar to those in operation in El Cabril, Spain. The design of this type of repository is based on the use of multiple, independent and redundant barriers. The intermediate radioactive waste consists mostly in spent ionic exchange resins and filters from the nuclear power plants, research reactors and radioisotopes production facilities. The spent resins, as well as the incineration ashes, have to be immobilized before being stored to improve leach resistance of waste matrix and to maintain mechanical stability for safety requirements. Generally, cementation processes have been used as immobilization techniques for economical reasons as well as for being a simple operation. The immobilized resins and incineration ashes are thus contained in steel drums that, in turn, can undergo corrosion depending on the ionic content of the matrix. This work is a part of a systematic study of the corrosion susceptibility of steel drums in contact with immobilized cemented exchange-resins with different types and contents of aggressive species and incineration ashes. To this purpose, a special type of specimen was manufactured to simulate the cemented waste in the drum. The evolution of the corrosion potential and the corrosion current density of the steel, as well as the electrical resistivity of the matrix are being monitored along time. The aggressive species studied were chloride ions (the main ionic species present in nature) and sulphate ions (produced during the radiolysis process of the cationic exchange-resins after cementation). Preliminary results show the strong effect of chloride on the corrosion susceptibility of the steel. Monitoring will continue for

Numerical simulation of a metal corrosion for a point defect for a organic protection layer

International Nuclear Information System (INIS)

Vautrin-Ul, Ch.; Chausse, A.; Stafiej, J.; Badiali, J.P.

2005-01-01

The safety of radioactive wastes disposal requires a big knowledge on their aging facing a corrosive environment. The corrosion is a complex phenomenon which implies many processes bound to the physic and the chemistry of the system. This approach proposes, from a little number of simple processes, numerical simulation which will define theses complex phenomenon. The presented model is a 2 dimension model at a mesoscopic scale and based on cellular automates. It allows the simulation of a metal evolution, protected by a polymer layer and in contact at one point with a corrosive media at a defect of the layer. (A.L.B.)

Research on A3 steel corrosion behavior of basic magnesium sulfate cement

Science.gov (United States)

Xing, Sainan; Wu, Chengyou; Yu, Hongfa; Jiang, Ningshan; Zhang, Wuyu

2017-11-01

In this paper, Tafel polarization technique is used to study the corrosion behavior of A3 steel basic magnesium sulfate, and then analyzing the ratio of raw materials cement, nitrites rust inhibitor and wet-dry cycle of basic magnesium sulfate corrosion of reinforced influence, and the steel corrosion behavior of basic magnesium sulfate compared with magnesium oxychloride cement and Portland cement. The results show that: the higher MgO/MgSO4 mole ratio will reduce the corrosion rate of steel; Too high and too low H2O/MgSO4 mole ratio may speed up the reinforcement corrosion effect; Adding a small amount of nitrite rust and corrosion inhibitor, not only can obviously reduce the alkali type magnesium sulfate in the early hydration of cement steel bar corrosion rate, but also can significantly reduce dry-wet circulation under the action of alkali type magnesium sulfate cement corrosion of reinforcement effect. Basic magnesium sulfate cement has excellent ability to protect reinforced, its long-term corrosion of reinforcement effect and was equal to that of Portland cement. Basic magnesium sulfate corrosion of reinforced is far below the level in the MOC in the case.

Container for processing and disposing radioactive wastes and industrial wastes

International Nuclear Information System (INIS)

Araki, Kunio; Kasahara, Yuko; Kasai, Noboru; Sudo, Giichi; Ishizaki, Kanjiro.

1978-01-01

Purpose: To improve the performance of containers for radioactive wastes for ocean disposal and on-land disposal such as impact strength, chemical resistance, fire resistance, corrosion resistance, water impermeability and the like. Constitution: Steel fiber-reinforced concrete previously molded in a shape of a container is impregnated with polymerizable impregnating agent selected from the group consisting of a polymerizable monomer, liquid mixture of a polymerizable monomer and an oligomer, a polymer solution, a copolymer solution and the liquid mixture thereof. Then, the polymerizable impregnating agent is polymerized to solidify in the concrete by way of heat-polymerization or radiation-induced polymerization to form a waste container. The container thus obtained can be improved with the impact resistance and wear resistance and further improved with salt water resistance, acid resistance, corrosion resistance and solidity by the impregnation of the polymer, as well as can effectively be prevented from leaching out of radioactive substances. (Furukawa, Y.)

Process for cleaning radioactively contaminated metal surfaces

International Nuclear Information System (INIS)

Mihram, R.G.; Snyder, G.A.

1975-01-01

A process is described for removing radioactive scale from a ferrous metal surface, including the steps of initially preconditioning the surface by contacting it with an oxidizing solution (such as an aqueous solution of an alkali metal permanganate or hydrogen peroxide), then, after removal or decomposition of the oxidizing solution, the metallic surface is contacted with a cleaning solution which is a mixture of a mineral acid and a complexing agent (such as sulfuric acid and oxalic acid), and which preferably contains a corrosion inhibitor. A final step in the process is the treatment of the spent cleaning solution containing radioactive waste materials in solution by adding a reagent selected from the group consisting of calcium hydroxide or potassium permanganate and an alkali metal hydroxide to thereby form easily recovered metallic compounds containing substantially all of the dissolved metals and radioactivity. (auth)

Method of storing radioactive wastes

International Nuclear Information System (INIS)

Adachi, Toshio; Hiratake, Susumu.

1980-01-01

Purpose: To reduce the radiation doses externally irradiated from treated radioactive waste and also reduce the separation of radioactive nuclide due to external environmental factors such as air, water or the like. Method: Radioactive waste adhered with radioactive nuclide to solid material is molten to mix and submerge the radioactive nuclide adhered to the surface of the solid material into molten material. Then, the radioactive nuclide thus mixed is solidified to store the waste in solidified state. (Aizawa, K.)

The improvement of Pilot-scale Electrokinetic for Radioactive Soil Decontamination

International Nuclear Information System (INIS)

Park, Hye Min; Kim, Gye Nam; Kim, Wan Suk; Moon, Jai Kwon

2012-01-01

Most nuclear facility sites have been contaminated by leakage of radioactive waste-solution due to corrosion of the waste-solution tanks and connection pipes by their long-term operation, set up around underground nuclear facilities. Therefore it was needed that the method to remediate a large volume of radioactive soil should be developed. Until now the soil washing method has studied to remediate soil contaminated with uranium, cobalt, cesium, and so on. But it has a lower removal efficiency of nuclide from soils and generated a large volume of waste-solution. And its application to the soil composed of fine particle is impossible. So, the electrokinetic method has been studied as a new technology for soil remediation recently. In this study, the original electrokinetic equipment of 50L suitable to soil contamination characteristics of Korean nuclear facility sites was manufactured for the remediation of soil contaminated with uranium. During experiment with the original electrokinetic equipment, many metal oxides were generated and were stuck on the cathod plate. Several methods to reduce the generation quantity of metal oxides in the electrokinetic equipment and to take off metal oxides from the cathod plate were improved. The soil with uranium was remediated with the improved electrokinetic equipment. The required time to remediate a radioactive soil to under a clearance concentration level was yielded through demonstration experiment with the improved electrokinetic equipment for its different radioactivity concentration

The improvement of Pilot-scale Electrokinetic for Radioactive Soil Decontamination

Energy Technology Data Exchange (ETDEWEB)

Park, Hye Min; Kim, Gye Nam; Kim, Wan Suk; Moon, Jai Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

Most nuclear facility sites have been contaminated by leakage of radioactive waste-solution due to corrosion of the waste-solution tanks and connection pipes by their long-term operation, set up around underground nuclear facilities. Therefore it was needed that the method to remediate a large volume of radioactive soil should be developed. Until now the soil washing method has studied to remediate soil contaminated with uranium, cobalt, cesium, and so on. But it has a lower removal efficiency of nuclide from soils and generated a large volume of waste-solution. And its application to the soil composed of fine particle is impossible. So, the electrokinetic method has been studied as a new technology for soil remediation recently. In this study, the original electrokinetic equipment of 50L suitable to soil contamination characteristics of Korean nuclear facility sites was manufactured for the remediation of soil contaminated with uranium. During experiment with the original electrokinetic equipment, many metal oxides were generated and were stuck on the cathod plate. Several methods to reduce the generation quantity of metal oxides in the electrokinetic equipment and to take off metal oxides from the cathod plate were improved. The soil with uranium was remediated with the improved electrokinetic equipment. The required time to remediate a radioactive soil to under a clearance concentration level was yielded through demonstration experiment with the improved electrokinetic equipment for its different radioactivity concentration

The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor.

Science.gov (United States)

Minnoş, Bihter; Ilhan-Sungur, Esra; Çotuk, Ayşın; Güngör, Nihal Doğruöz; Cansever, Nurhan

2013-01-01

The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor was investigated over a 10-month period in a hotel. Planktonic and sessile numbers of sulphate reducing bacteria (SRB) and heterotrophic bacteria were monitored. The corrosion rate was determined by the weight loss method. The corrosion products were analyzed by energy dispersive X-ray spectroscopy and X-ray diffraction. A mineralized, heterogeneous biofilm was observed on the coupons. Although a biocide and a corrosion inhibitor were regularly added to the cooling water, the results showed that microorganisms, such as SRB in the mixed species biofilm, caused corrosion of galvanized steel. It was observed that Zn layers on the test coupons were completely depleted after 3 months. The Fe concentrations in the biofilm showed significant correlations with the weight loss and carbohydrate concentration (respectively, p < 0.01 and p < 0.01).

Method for burning radioactive wastes

International Nuclear Information System (INIS)

Hattori, Akinori; Tejima, Takaya.

1987-01-01

Purpose: To completely process less combustible radioactive wastes with no excess loads on discharge gas processing systems and without causing corrosions to furnace walls. Method: Among combustible radioactive wastes, chlorine-containing less combustible wastes such as chlorine-containing rubbers and vinyl chlorides, and highly heat generating wastes not containing chloride such as polyethylene are selectively packed into packages. While on the other hand, packages of less combustible wastes are charged into a water-cooled jacket type incinerator intermittently while controlling the amount and the interval of charging so that the temperature in the furnace will be kept to lower than 850 deg C for burning treatment. Directly after the completion of the burning, the packed highly heat calorie producing wastes are charged and subjected to combustion treatment. (Yoshihara, H.)

Radioactive battery

International Nuclear Information System (INIS)

Deaton, R.L.; Silver, G.L.

1975-01-01

A radioactive battery is described that is comprised of a container housing an electrolyte, two electrodes immersed in the electrolyte and insoluble radioactive material disposed adjacent one electrode. Insoluble radioactive material of different intensity of radioactivity may be disposed adjacent the second electrode. If hydrobromic acid is used as the electrolyte, Br 2 will be generated by the radioactivity and is reduced at the cathode: Br 2 + 2e = 2 Br - . At the anode Br - is oxidized: 2Br - = Br 2 + 2e. (U.S.)

Passive Corrosion Behavior of Alloy 22

International Nuclear Information System (INIS)

R.B. Rebak; J.H. Payer

2006-01-01

Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids

Detection of corrosion by radiographic techniques

International Nuclear Information System (INIS)

Ahmad, M.; Ashraf, M.M.; Khurshid, U.

2004-01-01

Radiation processing technologies are playing an increasing role during manufacturing and subsequent use of everyday products. These technologies are now well established and are extensively practiced in industries, to ensure quality and safety of machinery. Corrosion reduces the operational life of the component, its efficiency and helps generate waste. There is an increasing need to detect and characterize the formation of corrosion in industrial components and assemblies at an early stage. Radiation methods and techniques are applied worldwide to examine defects and corrosion-formation in industrial components. For safety and economic reason, appropriate monitoring of the machinery and industrial components would help reduce accidental risks during operation and avoid production-losses. In the present study, X-ray and neutron-radiography techniques were applied for the inspection and evaluation of corrosion in metallic samples for thickness values of the order of 5 mm or less. Relative contrast at various degrees of metal corrosion product loss was computed theoretical and also measured experimentally by applying radiographic techniques. The relative contrast-sensitivity was also measured in two different ways by X-ray and neutron radiography, to compare the visibility of coarse and fine features. Thick metallic areas, free from sealant and variable paint thickness, were imaged with thermal neutrons beam. Low KV X-rays were also applied for imaging corrosion in metallic components. To optimize exposure-time at low KV in X-ray radiography, a medical film/screen combination was used. X-ray radiography approved to be the more promising technique for imaging of corrosion, as compared to neutron radiography. (author)

Corrosion evaluation of alloys for nuclear waste processing

International Nuclear Information System (INIS)

Corbett, R.A.; Bickford, D.F.; Morrison, W.S.

1986-01-01

Corrosion scouting tests were performed on stainless steel and nickel-based alloys in simulated process solutions to be used in a facility to immobilize high-level radioactive waste by incorporating it into borosilicate glass. Alloys with combined chromium plus molybdenum contents >30% and also >9% molybdenum, were the most resistant to general and local attack. Alloy C-276 was selected as the reference process equipment material, with Alloy 690 and ALLCORR selected for specific applications

Hanford transuranic storage corrosion review

International Nuclear Information System (INIS)

Nelson, J.L.; Divine, J.R.

1980-12-01

The rate of atmospheric corrosion of the transuranic (TRU) waste drums at the US Department of Energy's Hanford Project, near Richland, Washington, was evaluated by Pacific Northwest Laboratory (PNL). The rate of corrosion is principally contingent upon the effects of humidity, airborne pollutants, and temperature. Results of the study indicate that actual penetration of barrels due to atmospheric corrosion will probably not occur within the 20-year specified recovery period. Several other US burial sites were surveyed, and it appears that there is sufficient uncertainty in the available data to prevent a clearcut statement of the corrosion rate at a specific site. Laboratory and site tests are recommended before any definite conclusions can be made. The corrosion potential at the Hanford TRU waste site could be reduced by a combination of changes in drum materials (for example, using galvanized barrels instead of the currently used mild steel barrels), environmental exposure conditions (for example, covering the barrels in one of numerous possible ways), and storage conditions

Method of preventing contaminations in radioactive material handling facilities

International Nuclear Information System (INIS)

Inoue, Shunji.

1986-01-01

Purpose: To prevent the contamination on the floor surface of working places by laying polyvinyl butyral sheets over the floor surface, replacing when the sheets are contaminated, followed by burning. Method: Polyvinyl butyral sheets comprising 50 - 70 mol% of butyral component are laid in a radioactive material handling facility, radioactive materials are handled on the polyvinyl butyral sheets and the sheets are replaced when contaminated. The polyvinyl butyral sheets used contain 62 - 68 mol% of butyral component and has 0.03 - 0.2 mm thickness. The contaminated sheets are subjected to burning processing. This can surely collect radioactive materials and the sheets have favorable burnability, releasing no corrosive or deleterious gases. In addition, they are inexpensive and give no hindrance to the workers walking. (Takahashi, M.)

Current status of studies on nodular corrosion

International Nuclear Information System (INIS)

Yasuda, Takayoshi; Kawasaki, Satoru; Echigoya, Hironori; Kinoshita, Yutaka; Kubota, Hiroyuki; Konishi, Takao; Yamanaka, Tuneyasu.

1993-01-01

The studies on nodular corrosion formed on the outer surface of BWR fuel cladding tubes were reviewed. Main factors affecting the corrosion behavior were material and environmental conditions and combined effect. The effects of such material conditions as fabrication process, alloy elements, texture and surface treatment and environmental factors as neutron irradiation, thermo-hydrodynamic, water chemistry, purity of the coolant and contact with foreign metals on the corrosion phenomena were surveyed. Out-of-reactor corrosion test methods and models for the corrosion mechanism were also reviewed. Suppression of the accumulated annealing temperature during tube reduction process improved the nodular corrosion resistance of Zircaloys. Improved resistance for the nodular corrosion was reported for the unirradiated Zircaloys with some additives. Detailed irradiation test under the BWR conditions is needed to confirm the trend. Concerning the environmental factors, boiling on the cladding surface due to heat flux reduces the nodular corrosion susceptibility, while oxidizing radical generated from dissolved oxygen accelerates the corrosion. Concerning corrosion mechanisms, importance of such phenomena as the depleted zone of alloying elements in zirconium matrix, reduction of H + to H 2 in oxide layer, electrochemical property of precipitates, crystallographic anisotropy of oxidation rates were revealed. (author) 59 refs

Effects of climate and corrosion on concrete behaviour

Science.gov (United States)

Ismail, Mohammad; Egba, Ernest Ituma

2017-11-01

Corrosion of steel is a damaging agent that reduces the functional and structural responsibilities of reinforced concrete structures. Accordingly, reinforced concrete members in the environments that are prone to concrete carbonation or chloride attack coupled with high temperature and relative humidity suffer from accelerated corrosion of reinforcing material. Also, literature proves that climate influences corrosion of concrete, and suggests investigation of impact of corrosion on concrete based on climate zone. Therefore, this paper presents the effects of climate and corrosion on concrete behavior, using bond strength of concrete as a case study. Concrete specimens were prepared form concrete mix that was infested with 3.5 kgm-3 of sodium chloride to accelerate corrosion. The specimens were cured sodium chloride solution 3.5% by weight of water for 28 days before placing them in the exposure conditions. Pull-out tests were conducted at time intervals for one year to measure the impact of exposure condition and corrosion on bond strength of concrete. The results show reduction of bond strength of concrete by 32%, 28% and 8% after one year of subjection of the specimens to the unsheltered natural climate, sheltered natural climate, and laboratory ambient environment respectively. The findings indicate that the climate influences corrosion, which reduces the interlocking bond between the reinforcing bar and the adjacent concrete.

Research Opportunities in Corrosion Science for Long-Term Prediction of Materials Performance: A Report of the DOE Workshop on “Corrosion Issues of Relevance to the Yucca Mountain Waste Repository”.

Energy Technology Data Exchange (ETDEWEB)

Payer, Joe H. [Case Western Reserve Univ., Cleveland, OH (United States); Scully, John R. [Univ. of Virginia, Charlottesville, VA (United States)

2003-07-29

The report summarizes the findings of a U.S. Department of Energy workshop on “Corrosion Issues of Relevance to the Yucca Mountain Waste Repository”. The workshop was held on July 29-30, 2003 in Bethesda, MD, and was co-sponsored by the Office of Basic Energy Sciences and Office of Civilian Radioactive Waste Management. The workshop focus was corrosion science relevant to long-term prediction of materials performance in hostile environments, with special focus on relevance to the permanent disposal of nuclear waste at the Yucca Mountain Repository. The culmination of the workshop is this report that identifies both generic and Yucca Mountain Project-specific research opportunities in basic and applied topic areas. The research opportunities would be realized well after the U.S. Nuclear Regulatory Commission’s initial construction-authorization licensing process. At the workshop, twenty-three invited scientists deliberated on basic and applied science opportunities in corrosion science relevant to long-term prediction of damage accumulation by corrosive processes that affect materials performance.

Technique for characterizing crevice corrosion under hydrothermal conditions

International Nuclear Information System (INIS)

Jain, H.; Ahn, T.M.; Soo, P.

1983-01-01

The current/potential results show that the crevice corrosion incubation period for a Grade-12 titanium crevice formed between two Teflon plates is about two days at 150 0 C. Optical and SEM observations show that the corrosion starts as isolated pitting which spreads along the surface as shallow pits. The corrosion conditions change significantly as the TiO 2 corrosion product fills the crevice, and the rate of corrosion may be greatly reduced after several days. The rate of crevice corrosion of commercial purity (Grade-2) titanium under similar consitions is approximately three orders of magnitude higher. In this case, active dissolution of metal starts during the initial heating of the autoclave and the incubation period is negligible

Corrosion and microstructural aspects of dissimilar joints of titanium and type 304L stainless steel

International Nuclear Information System (INIS)

Mudali, U. Kamachi.; Ananda Rao, B.M.; Shanmugam, K.; Natarajan, R.; Raj, Baldev

2003-01-01

To link titanium and zirconium metal based (Ti, Zr-2, Ti-5%Ta, Ti-5%Ta-1.8Nb) dissolver vessels containing highly radioactive and concentrated corrosive nitric acid solution to other nuclear fuel reprocessing plant components made of AISI type 304L stainless steel (SS), high integrity and corrosion resistant dissimilar joints between them are necessary. Fusion welding processes produce secondary precipitates which dissolve in nitric acid, and hence solid-state processes are proposed. In this work, various dissimilar joining processes available for producing titanium-304L SS joints with adequate strength, ductility and corrosion resistance for this critical application are highlighted. Developmental efforts made at IGCAR, Kalpakkam are outlined. The possible methods and the microstructural-metallurgical properties of the joints along with corrosion results obtained with three phase (liquid, vapour, condensate) corrosion testing are discussed. Based on the results, dissimilar joint produced by the explosive joining process was adopted for plant application

Research of reducing the shielding effect caused by vehicles passing the radioactivity monitor system

International Nuclear Information System (INIS)

Deng Xianqi; Li Jianmin; Wang Xiaobing

2008-01-01

A kind of Radioactivity Monitor System with Vehicle Contour Acquisition Module based on Optical Screen is developed. The system can reduce the shielding effect caused by the passing vehicles, so that the alarming sensitivity is improved. This paper introduces the work situation of the system and preliminary experimental results. (authors)

Fundamental corrosion characterization of high-strength titanium alloys

International Nuclear Information System (INIS)

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

1984-01-01

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

TREATMENT TANK CORROSION STUDIES FOR THE ENHANCED CHEMICAL CLEANING PROCESS

Energy Technology Data Exchange (ETDEWEB)

Wiersma, B.

2011-08-24

Radioactive waste is stored in high level waste tanks on the Savannah River Site (SRS). Savannah River Remediation (SRR) is aggressively seeking to close the non-compliant Type I and II waste tanks. The removal of sludge (i.e., metal oxide) heels from the tank is the final stage in the waste removal process. The Enhanced Chemical Cleaning (ECC) process is being developed and investigated by SRR to aid in Savannah River Site (SRS) High-Level Waste (HLW) as an option for sludge heel removal. Corrosion rate data for carbon steel exposed to the ECC treatment tank environment was obtained to evaluate the degree of corrosion that occurs. These tests were also designed to determine the effect of various environmental variables such as temperature, agitation and sludge slurry type on the corrosion behavior of carbon steel. Coupon tests were performed to estimate the corrosion rate during the ECC process, as well as determine any susceptibility to localized corrosion. Electrochemical studies were performed to develop a better understanding of the corrosion mechanism. The tests were performed in 1 wt.% and 2.5 wt.% oxalic acid with HM and PUREX sludge simulants. The following results and conclusions were made based on this testing: (1) In 1 wt.% oxalic acid with a sludge simulant, carbon steel corroded at a rate of less than 25 mpy within the temperature and agitation levels of the test. No susceptibility to localized corrosion was observed. (2) In 2.5 wt.% oxalic acid with a sludge simulant, the carbon steel corrosion rates ranged between 15 and 88 mpy. The most severe corrosion was observed at 75 C in the HM/2.5 wt.% oxalic acid simulant. Pitting and general corrosion increased with the agitation level at this condition. No pitting and lower general corrosion rates were observed with the PUREX/2.5 wt.% oxalic acid simulant. The electrochemical and coupon tests both indicated that carbon steel is more susceptible to localized corrosion in the HM/oxalic acid environment than

Treatment Tank Corrosion Studies For The Enhanced Chemical Cleaning Process

International Nuclear Information System (INIS)

Wiersma, B.

2011-01-01

Radioactive waste is stored in high level waste tanks on the Savannah River Site (SRS). Savannah River Remediation (SRR) is aggressively seeking to close the non-compliant Type I and II waste tanks. The removal of sludge (i.e., metal oxide) heels from the tank is the final stage in the waste removal process. The Enhanced Chemical Cleaning (ECC) process is being developed and investigated by SRR to aid in Savannah River Site (SRS) High-Level Waste (HLW) as an option for sludge heel removal. Corrosion rate data for carbon steel exposed to the ECC treatment tank environment was obtained to evaluate the degree of corrosion that occurs. These tests were also designed to determine the effect of various environmental variables such as temperature, agitation and sludge slurry type on the corrosion behavior of carbon steel. Coupon tests were performed to estimate the corrosion rate during the ECC process, as well as determine any susceptibility to localized corrosion. Electrochemical studies were performed to develop a better understanding of the corrosion mechanism. The tests were performed in 1 wt.% and 2.5 wt.% oxalic acid with HM and PUREX sludge simulants. The following results and conclusions were made based on this testing: (1) In 1 wt.% oxalic acid with a sludge simulant, carbon steel corroded at a rate of less than 25 mpy within the temperature and agitation levels of the test. No susceptibility to localized corrosion was observed. (2) In 2.5 wt.% oxalic acid with a sludge simulant, the carbon steel corrosion rates ranged between 15 and 88 mpy. The most severe corrosion was observed at 75 C in the HM/2.5 wt.% oxalic acid simulant. Pitting and general corrosion increased with the agitation level at this condition. No pitting and lower general corrosion rates were observed with the PUREX/2.5 wt.% oxalic acid simulant. The electrochemical and coupon tests both indicated that carbon steel is more susceptible to localized corrosion in the HM/oxalic acid environment than

On-line corrosion monitoring in district heating systems

DEFF Research Database (Denmark)

Richter, Sonja; Thorarinsdottir, R.I.; Hilbert, Lisbeth Rischel

2004-01-01

), Electrochemical Noise (EN) and Zero Resistance Ammetry (ZRA). Electrochemical Resistance (ER) has also been used to measure corrosion. The method traditionally only measures corrosion off-line but with newly developed high-sensitive ER technique developed by MetriCorr in Denmark, on-line monitoring is possible...... complicates the chemistry of the environment. Hydrogen sulphide is present in geothermal systems and can be formed as a by-product of sulphate-reducing-bacteria (SRB). The application of electrochemical methods makes on-line monitoring possible. These methods include: Linear Polarization Resistance (LPR....... In order to assess both general corrosion and localized corrosion, it is necessary to apply more than one monitoring technique simultaneously, ZRA or EN for measuring localized corrosion and LPR or ER for measuring general corrosion rate. The advantage of monitoring localized corrosion is indisputable...

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Application of thin layer activation technique for monitoring corrosion of carbon steel in hydrocarbon processing environment.

Science.gov (United States)

Saxena, R C; Biswal, Jayashree; Pant, H J; Samantray, J S; Sharma, S C; Gupta, A K; Ray, S S

2018-05-01

Acidic crude oil transportation and processing in petroleum refining and petrochemical operations cause corrosion in the pipelines and associated components. Corrosion monitoring is invariably required to test and prove operational reliability. Thin Layer Activation (TLA) technique is a nuclear technique used for measurement of corrosion and erosion of materials. The technique involves irradiation of material with high energy ion beam from an accelerator and measurement of loss of radioactivity after the material is subjected to corrosive environment. In the present study, TLA technique has been used to monitor corrosion of carbon steel (CS) in crude oil environment at high temperature. Different CS coupons were irradiated with a 13 MeV proton beam to produce Cobalt-56 radioisotope on the surface of the coupons. The corrosion studies were carried out by subjecting the irradiated coupons to a corrosive environment, i.e, uninhibited straight run gas oil (SRGO) containing known amount of naphthenic acid (NA) at high temperature. The effects of different parameters, such as, concentration of NA, temperature and fluid velocity (rpm) on corrosion behaviour of CS were studied. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electron transfer mediators accelerated the microbiologically influence corrosion against carbon steel by nitrate reducing Pseudomonas aeruginosa biofilm.

Science.gov (United States)

Jia, Ru; Yang, Dongqing; Xu, Dake; Gu, Tingyue

2017-12-01

Electron transfer is a rate-limiting step in microbiologically influenced corrosion (MIC) caused by microbes that utilize extracellular electrons. Cross-cell wall electron transfer is necessary to transport the electrons released from extracellular iron oxidation into the cytoplasm of cells. Electron transfer mediators were found to accelerate the MIC caused by sulfate reducing bacteria. However, there is no publication in the literature showing the effect of electron transfer mediators on MIC caused by nitrate reducing bacteria (NRB). This work demonstrated that the corrosion of anaerobic Pseudomonas aeruginosa (PAO1) grown as a nitrate reducing bacterium biofilm on C1018 carbon steel was enhanced by two electron transfer mediators, riboflavin and flavin adenine dinucleotide (FAD) separately during a 7-day incubation period. The addition of either 10ppm (w/w) (26.6μM) riboflavin or 10ppm (12.7μM) FAD did not increase planktonic cell counts, but they increased the maximum pit depth on carbon steel coupons considerably from 17.5μm to 24.4μm and 25.0μm, respectively. Riboflavin and FAD also increased the specific weight loss of carbon steel from 2.06mg/cm 2 to 2.34mg/cm 2 and 2.61mg/cm 2 , respectively. Linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization curves all corroborated the pitting and weight loss data. Copyright © 2017 Elsevier B.V. All rights reserved.

Significance of chemotoxic admixtures in radioactive wastes

International Nuclear Information System (INIS)

Merz, E.R.

1989-01-01

The double hazard potential of mixed wastes is characterized by several criteria: radioactivity on the one hand, and chemical toxicity, in flammability, corrosiveness as well as chemical reactivity on the other. The author argues that mixed wastes assigned for ultimate disposal should therefore be thoroughly detoxified, inertized, or mineralized, prior to conditioning and packaging. Strategies and techniques are presented which ensure the elimination of hazardous organic chemicals and minimizing waste volumes to be disposed of. Advantage can be taken of mixing mineralized filter dusts, arising in the combustion of hazardous chemical wastes with low-activity inertized radioactive wastes as a solidifying reagent. Simultaneous geological disposal of such mixed waste is feasible without any drawbacks

Influence of biofilm formation on corrosion and scaling in geothermal plants

Science.gov (United States)

Kleyböcker, Anne; Lerm, Stephanie; Monika, Kasina; Tobias, Lienen; Florian, Eichinger; Andrea, Seibt; Markus, Wolfgramm; Hilke, Würdemann

2017-04-01

Process failures may occur due to corrosion and scaling processes in open loop geothermal systems. Especially after heat extraction, sulfate reducing bacteria (SRB) contribute to corrosion processes due to a more favorable temperature for their growth. In biofilms containing FeS scales, corrosion processes are enhanced. Furthermore, scales can lead to reduced pipe profiles, to a diminished heat transfer and a decrease in the wellbore injectivity. Inhibitors are frequently applied to minimize scaling in technical systems. A prerequisite for the application of inhibitors in geothermal plants located in the Molasse basin is their degradability under reservoir conditions, e. g. in a reduced environment. In order to determine the effects of scale-inhibitors on the subsurface and microbial processes, laboratory experiments were performed focusing on the microbial inhibitor degradation. First results indicate that the inhibitor degradation under anaerobic conditions is possible. Besides the inhibitor application also other techniques are investigated to economically reduce corrosion and scaling in geothermal plants. In a mobile bypass system, the influence of biofilm formation on corrosion and scaling was investigated. The bypass system was tested at a geothermal heat store in the North German Basin. The plant is operated with highly saline fluid (salinity 130 g/L) and known to be affected by SRB. The SRB contributed to corrosion damages especially at the pump in the well on the cold side. Heat shocks were successfully used in the bypass system to reduce biofilm formation as well as corrosion and scaling processes.

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

International Nuclear Information System (INIS)

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

2005-01-01

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

System for corrosion monitoring in pipeline applying fuzzy logic mathematics

Science.gov (United States)

Kuzyakov, O. N.; Kolosova, A. L.; Andreeva, M. A.

2018-05-01

A list of factors influencing corrosion rate on the external side of underground pipeline is determined. Principles of constructing a corrosion monitoring system are described; the system performance algorithm and program are elaborated. A comparative analysis of methods for calculating corrosion rate is undertaken. Fuzzy logic mathematics is applied to reduce calculations while considering a wider range of corrosion factors.

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

Science.gov (United States)

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

Monitoring corrosion of steel bars in reinforced concrete structures.

Science.gov (United States)

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

Directory of Open Access Journals (Sweden)

Sanjeev Kumar Verma

2014-01-01

Full Text Available Corrosion of steel bars embedded in reinforced concrete (RC structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP method. This paper also presents few techniques to protect concrete from corrosion.

Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

International Nuclear Information System (INIS)

Blunt, J.; Jen, G.; Ostertag, C.P.

2015-01-01

Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

Surface treatment and history-dependent corrosion in lead alloys

International Nuclear Information System (INIS)

Li Ning; Zhang Jinsuo; Sencer, Bulent H.; Koury, Daniel

2006-01-01

In oxygen-controlled lead and lead-bismuth eutectic (LBE), steel corrosion may be strongly history dependent. This is due to the competition between liquid metal dissolution corrosion and oxidation as a 'self-healing' protection barrier. Such effects can be observed from corrosion testing of a variety of surface-treated materials, such as cold working, shot peening, pre-oxidation, etc. Shot peening of austenitic steels produces surface-layer microstructural damages and grain compression, which could contribute to increased Cr migration to the surface and enhance the protection through an impervious oxide. Pre-oxidation under conditions different from operating ones may form more protective oxides, reduce oxygen and metal ion migration through the oxides, and achieve better protection for longer durations. Corrosion and oxidation modeling and analysis reveal the potential for significantly reducing long-term corrosion rates by initial and early-stage conditioning of steels for Pb/LBE services

Surface treatment and history-dependent corrosion in lead alloys

Energy Technology Data Exchange (ETDEWEB)

Li Ning [Los Alamos National Laboratory, Los Alamos, NM (United States)]. E-mail: ningli@lanl.gov; Zhang Jinsuo [Los Alamos National Laboratory, Los Alamos, NM (United States); Sencer, Bulent H. [Los Alamos National Laboratory, Los Alamos, NM (United States); Koury, Daniel [University of Nevada, Las Vegas, NV (United States)

2006-06-23

In oxygen-controlled lead and lead-bismuth eutectic (LBE), steel corrosion may be strongly history dependent. This is due to the competition between liquid metal dissolution corrosion and oxidation as a 'self-healing' protection barrier. Such effects can be observed from corrosion testing of a variety of surface-treated materials, such as cold working, shot peening, pre-oxidation, etc. Shot peening of austenitic steels produces surface-layer microstructural damages and grain compression, which could contribute to increased Cr migration to the surface and enhance the protection through an impervious oxide. Pre-oxidation under conditions different from operating ones may form more protective oxides, reduce oxygen and metal ion migration through the oxides, and achieve better protection for longer durations. Corrosion and oxidation modeling and analysis reveal the potential for significantly reducing long-term corrosion rates by initial and early-stage conditioning of steels for Pb/LBE services.

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

Real-time monitoring of copper corrosion at the Aespoe HRL

Energy Technology Data Exchange (ETDEWEB)

Rosborg, Bo; Pan, Jinshan [Div. Corrosion Science, Royal Institute of Technology, Drottning Kristinas vaeg 51, SE - 100 44 Stockholm (Sweden); Eden, David [InterCorr International, Inc., 14503 Bammel-N Houston, Suite 300, Houston, TX 77014 (United States); Karnland, Ola [Clay Technology AB, Ideon Research Center, SE - 223 70 Lund (Sweden); Werme, Lars [Svensk Kaernbraenslehantering AB, P.O. Box 5864, SE - 102 40 Stockholm (Sweden)

2004-07-01

In Sweden the principal strategy for high-level radioactive waste disposal is to enclose the spent nuclear fuel in tightly sealed copper canisters that are embedded in bentonite clay about 500 m down in the Swedish bed-rock. Initially, a limited amount of air will be left in a repository after emplacement. The entrapped oxygen will be consumed through reactions with minerals in the rock and the bentonite and also through microbial activity. After the oxygen has been consumed in the repository, after a few hundred years at the very most, corrosion will be controlled completely by the supply of dissolved sulphide to the canister. The present work concerns the oxic period after emplacement. The main hypothesis is that the average corrosion rate of the canister under oxic conditions will be less than 7 {mu}m/year, and that pitting will only be possible under these conditions. The Aespoe Hard Rock Laboratory offers a realistic environment for different experiments and tests under the conditions that will prevail in a deep repository. Real-time monitoring of copper corrosion is presently performed with polarization resistance, harmonic distortion analysis and electrochemical noise techniques. The first two techniques are used to derive information regarding the general corrosion rate and the third to derive information regarding localized corrosion. In order to support these measurements at Aespoe, laboratory work is also performed at the Royal Institute of Technology in Stockholm using the very same corrosion monitoring equipment and also other equipment and techniques. Copper coupons are also exposed at Aespoe. Results from the work at Aespoe and in Stockholm are presented with an emphasis on the gained information concerning localized corrosion. The recorded corrosion rates at Aespoe are well below the value given above, and the recorded localization factors are interpreted as indicating only a slight tendency to local attack. (authors)

Real-time monitoring of copper corrosion at the Aespoe HRL

International Nuclear Information System (INIS)

Rosborg, Bo; Pan, Jinshan; Eden, David; Karnland, Ola; Werme, Lars

2004-01-01

In Sweden the principal strategy for high-level radioactive waste disposal is to enclose the spent nuclear fuel in tightly sealed copper canisters that are embedded in bentonite clay about 500 m down in the Swedish bed-rock. Initially, a limited amount of air will be left in a repository after emplacement. The entrapped oxygen will be consumed through reactions with minerals in the rock and the bentonite and also through microbial activity. After the oxygen has been consumed in the repository, after a few hundred years at the very most, corrosion will be controlled completely by the supply of dissolved sulphide to the canister. The present work concerns the oxic period after emplacement. The main hypothesis is that the average corrosion rate of the canister under oxic conditions will be less than 7 μm/year, and that pitting will only be possible under these conditions. The Aespoe Hard Rock Laboratory offers a realistic environment for different experiments and tests under the conditions that will prevail in a deep repository. Real-time monitoring of copper corrosion is presently performed with polarization resistance, harmonic distortion analysis and electrochemical noise techniques. The first two techniques are used to derive information regarding the general corrosion rate and the third to derive information regarding localized corrosion. In order to support these measurements at Aespoe, laboratory work is also performed at the Royal Institute of Technology in Stockholm using the very same corrosion monitoring equipment and also other equipment and techniques. Copper coupons are also exposed at Aespoe. Results from the work at Aespoe and in Stockholm are presented with an emphasis on the gained information concerning localized corrosion. The recorded corrosion rates at Aespoe are well below the value given above, and the recorded localization factors are interpreted as indicating only a slight tendency to local attack. (authors)

Laboratory investigation of microbiologically influenced corrosion of C1018 carbon steel by nitrate reducing bacterium Bacillus licheniformis

International Nuclear Information System (INIS)

Xu, Dake; Li, Yingchao; Song, Fengmei; Gu, Tingyue

2013-01-01

Nitrate injection is used to suppress reservoir souring in oil and gas fields caused by Sulfate Reducing Bacteria (SRB) through promotion of nitrate respiration by Nitrate Reducing Bacteria (NRB). However, it is not well publicized that nitrate reduction by NRB can cause Microbiologically Influenced Corrosion (MIC) because nitrate reduction coupled with iron oxidation is thermodynamically favorable. NRB benefits bioenergetically from this redox reaction under biocatalysis. This work showed that the Bacillus licheniformis biofilm, when grown as an NRB biofilm, caused a 14.5 μm maximum pit depth and 0.89 mg/cm 2 normalized weight loss against C1018 carbon steel in one-week lab tests

Effects of two main metabolites of sulphate-reducing bacteria on the corrosion of Q235 steels in 3.5 wt.% NaCl media

International Nuclear Information System (INIS)

Bao, Qi; Zhang, Dun; Lv, Dandan; Wang, Peng

2012-01-01

Highlights: ► Extracellular polymeric substances have been isolated from a batch culture of sulphate-reducing bacteria successfully. ► Sulphide and extracellular polymeric substances have triggered distinct electrochemical characteristics. ► ATR-IR analysis has confirmed the Fe 2+ -complexing capability of extracellular polymeric substances. ► In situ AFM results show extracellular polymeric substances can form a densely packed film on Q235 steels. ► The adsorbed extracellular polymeric substances film has protected the Q235 steels to a certain degree. - Abstract: The electrochemical corrosion behaviour of Q235 steels in 3.5 wt.% NaCl solutions with sulphide and extracellular polymeric substances (EPS), the two main metabolites of sulphate-reducing bacteria, was separately investigated through potentiodynamic polarisation and electrochemical impedance spectroscopy. Either sulphide or EPS increased the anodic current density by nearly one order of magnitude and negatively shifted the corrosion potential. The effects of EPS at the initial stage of corrosion may be ascribed to the Fe 2+ -complexing capability and the quickly adsorbed film. Moreover, the feeble protective effect of EPS after 16 d of immersion was observed through scanning electron microscopy.

Method of volume-reducing processing for radioactive wastes

International Nuclear Information System (INIS)

Sato, Koei; Yamauchi, Noriyuki; Hirayama, Toshihiko.

1985-01-01

Purpose: To process the processing products of radioactive liquid wastes and burnable solid wastes produced from nuclear facilities into stable solidification products by heat melting. Method: At first, glass fiber wastes of contaminated air filters are charged in a melting furnace. Then, waste products obtained through drying, sintering, incineration, etc. are mixed with a proper amount of glass fibers and charged into the melting furnace. Both of the charged components are heated to a temperature at which the glass fibers are melted. The burnable materials are burnt out to provide a highly volume-reduced products. When the products are further heated to a temperature at which metals or metal oxides of a higher melting point than the glass fiber, the glass fibers and the metals or metal oxides are fused to each other to be combined in a molecular structure into more stabilized products. The products are excellent in strength, stability, durability and leaching resistance at ambient temperature. (Kamimura, M.)

Actions to reduce radioactive emissions: prevention of containment failure by flooding Containment and Reactor Cavity

International Nuclear Information System (INIS)

Fornos Herrando, J.

2013-01-01

The reactor cavity of Asco and Vandellos II is dry type, thus a severe accident leading to vessel failure might potentially end up resulting in the loss of containment integrity, depending on the viability to cool the molten core. Therefore, significant radioactive emissions could be released to outside. In the framework of Fukushima Stress Tests, ANAV has analyzed the convenience of carrying out different actions to prevent failure of the containment integrity in order to reduce radioactive emissions. The aim of this paper is to present and describe the main phenomenological aspects associated with two of these actions: containment flooding and reactor cavity flooding.

CORROSION RATE OF STEELS DX51D AND S220GD IN DIFFERENT CORROSION ENVIRONMENT

Directory of Open Access Journals (Sweden)

Alina Crina CIUBOTARIU

2016-06-01

Full Text Available Corrosion in the marine environment is an important issue because the costs causes by marine corrosion increased year upon year. It is necessary a correctly approach to materials selection, protection and corrosion control to reduce this burden of wasted materials, wasted energy and wasted money. Many different types of corrosion attack can be observed to structures, ships and other equipment used in sea water service. Shipping containers are exposed to various corrosive mediums like as airborne salt, industrial pollutants, rain and saltwater. Transport damage during loading onto and unloading off trucks, train beds and ships breaches the paint coating which further contributes to corrosion. The result is shortened container life and high costs for container repair or replacement. The paper intends to evaluate, by gravimetric method, the corrosion rate and corrosion penetration rate of two types of carbon steel DX51D and S220GD. Carbon steel DX51D and hot-dip galvanized steel S220GD are used in marine and industrial applications for buildings cargo vessels, container ships and oil tankers. For testing it was used different corrosive environments: 5% NaOH solution; 5% HCL solution and 0.5M NaCl solution. The samples were immersed in 400mL of testing solution for exposure period of 28 days. Periodically at 3 days, 7 days, 14 days, 21 days and 28 days was measured de mass loss and evaluate the corrosion rate and corrosion stability coefficient. The steel DX51D was stable in 5% NaOH solution for 28 days, the values of corrosion stability coefficient was 7 after 3 days and 6 after 28 days of immersion in corrosive medium. In 5% HCL solution steels DX51D and S220GD was completely corroded in 21 days with a corrosion stability coefficient equal with 9 for 7 days and 8 for 21 days of immersion in corrosive solution. It was observed a good resistance for 3 days in 0.5M NaCl solution with a corrosion stability coefficient equal with 5, but after that

Prediction of crack due to corrosion of reinforcing bar in low alkali concrete

International Nuclear Information System (INIS)

Takeda, Nobufumi; Iriya, Keishiro; Hitomi, Takashi; Konishi, Kazuhiro; Kurihara, Yuji

2008-01-01

Steel-reinforced low alkaline concrete containing pozzolan has been examined for application in high level radioactive waste disposal. Marine exposure examinations a period of six years were performed for concrete with 30% water-cement ratio, and the reduction in its compressive strength, the intrusion depth of chloride ions, and the corrosion of the reinforcing bar were investigated. On the basis of these results, the progress of corrosion of the reinforcing bar and the outbreak time of a corrosion crack in the reinforcing bar were predicted. The following results are obtained. 1) There was no decrease in the compressive strength of the test pieces during the marine exposure examinations. 2) There was little penetration of the chloride ions in comparison with ordinary Portland cement. 3) Although the corrosion of the reinforcing bar commenced at an early stage with a little quantity of chloride ion intrusion, the progress over the period of six years was extremely small. 4) The corrosion rate of the reinforcing bar in groundwater including sea water was estimated as 0.30-0.55 mg/(cm 2 ·year). In the case of a reinforcing bar with a thickness of 100 mm and diameter of 22 mm, the outbreak time of the reinforcing corrosion crack was predicted as 50-100 years after construction. (author)

Study for reducing radioactive solid waste at ITER decommissioning period

Energy Technology Data Exchange (ETDEWEB)

Sato, Shinichi; Araki, Masanori; Ohmori, Junji; Ohno, Isamu; Sato, Satoshi; Yamauchi, Michinori; Nishitani, Takeo [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

2002-11-01

It is one of the foremost goals for ITER to demonstrate the attractiveness with regard to safety and environmental potential. This implies that the radioactive materials and waste at decommissioning phase should carefully be treated with prescribed regulations. As possible activities during the Coordinated Technical Activity (CTA), the authors have performed a feasibility study for searching the possibility of effective reduction in the activated level as reasonably achievable as possible by taking account of minimum material changes while keeping original design concept and structure. Major induced activation in ITER comes from activated nickel and cobalt so that it is effective for the major structural components to minimize their material contents. Employing less Ni and Co steel in place of high-Ni austenitic stainless steel for blanket shield block, vacuum vessel shield material and TF coil casing has been considered as one of the effective plans to reduce the activated materials at the decommissioning phase. In this study, two less-Ni austenitic stainless steels are evaluated; one is high-Mn austenitic stainless steel JK2 which is developing for jacket material of ITER CS coil and the other is SS204L/ASTM-XM-11 which is also high-Mn steel specified in the popular standards such as American Society of Testing and Material (ASTM). Based on the material changes, activation analyses have been performed to investigate the possibility of reducing radioactive wastes. As a most impressive result, at 40 years after the termination some of main components such as a TF coil casing will reach to the clearance level which is specified by IAEA, and most components will be categorized into extremely low level waste except for limited components. These results will give the appropriate short decommissioning period that is assumed to start at 100 years after the termination in the original design. (author)

Studies of corrosion in metallic container for storage of high level radioactive wastes; Estudios de corrosion de materiales metalicos para capsulas de almacenamiento de residuos de alta actividad

Energy Technology Data Exchange (ETDEWEB)

Azkarate, I; Madina, V; Insausti, M

1999-11-01

The metallic container is one of the most important barriers that, along with engineered and natural barriers, will isolate high level nuclear waste in saline and granite geological formations from the geosphere. However, general and localized corrosion modes such as stress corrosion cracking (SCC), pitting, crevice corrosion and hydrogen damage can be active under disposal conditions, so the corrosion behaviour of the metal container material must be carefully studied. Several metals and their alloys have been proposed for the fabrication of nuclear waste containers including carbon steels, stainless steels, titanium and titanium alloys and copper and copper-base alloys. Carbon steels and copper alloys are considered for the two rock formations, titanium is considered for salt environments and the stainless steel only in the case of a granite formation. (Author)

Corrosive wear. Evaluation of wear and corrosive resistant materials; Noetningskorrosion. Utvaerdering av noetnings- och korrosionsbestaendiga material

Energy Technology Data Exchange (ETDEWEB)

Persson, H.; Hjertsen, D.; Waara, P.; Prakash, B.; Hardell, J.

2007-12-15

With a new purchase of a waste conveyer screw at hand, for the 'A-warehouse' at the combined power and heating plant at E.ON Norrkoeping, the request for improved construction materials was raised. The previous screw required maintenance with very short intervals due to the difficult operation conditions. With the new screw the expectation is to manage 6 months of operation without interruption. The environment for the screw has two main components that sets the demand on the materials, on one hand the corrosive products that comes along and which forms at digestion of the waste and on the other hand the abrasive content in the waste. The term of the mechanism is wear-corrosion and can give considerably higher material loss than the two mechanisms wear and corrosion separately. Combination of a strong corrosive environment together with extensive wear is something that we today have limited knowledge about. The overall objective of the project has been to establish better wear and corrosive resistant construction materials for a waste conveyer screw that will lead to reduced operational disturbance costs. The evaluation has been performed in both controlled laboratory environments and in field tests, which has given us a better understanding of what materials are more suitable in this tough environment and has given us a tool for future predictions of the wear rate of the different material. The new conveyer screw, installed in February 2007 and with which the field test have been performed, has considerably reduced the wear of the construction and the target of 6 month maintenance-free operation is met with this screw for all the evaluated materials. The wear along the screw varies very much and with a clear trend for all the materials to increase towards the feeding direction of the screw. As an example, the wear plate SS2377 (stainless duplex steel) has a useful life at the most affected areas that is calculated to be 1077 days of operation with the

Corrosion Evaluation of INTEC Waste Storage Tank WM-182

International Nuclear Information System (INIS)

Dirk, W. J.; Anderson, P. A.

1999-01-01

Irradiated nuclear fuel has been stored and reprocessed at the Idaho National Engineering and Environmental Laboratory since 1953 using facilities located at the Idaho Nuclear Technology and Engineering Center (INTEC). This reprocessing produced radioactive liquid waste which was stored in the Tank Farm. The INTEC Tank Farm consists of eleven vaulted 300,000-gallon underground tanks including Tank WM-182. Tank WM-182 was put into service in 1955, has been filled four times, and has contained aluminum and zirconium fuel reprocessing wastes as well as sodium bearing waste. A program to monitor corrosion in the waste tanks was initiated in 1953 when the first of the eleven Tank Farm tanks was placed in service. Austenitic stainless steel coupons representative of the materials of construction of the tanks are used to monitor internal tank corrosion. This report documents the final inspection of the WM-182 corrosion coupons. Physical examination of the welded corrosion test coupons exposed to the tank bottom conditions of Tank WM-182 revealed very light uniform corrosion. Examination of the external surfaces of the extruded pipe samples showed very light uniform corrosion with slight indications of preferential attack parallel to extrusion marks and start of end grain attack of the cut edges. These indications were only evident when examined under stereo microscope at magnifications of 20X and above. There were no definite indications of localized corrosion, such as cracking, pitting, preferential weld attack, or weld heat affected zone attack on either the welded or extruded coupons. Visual examination of the coupon support cables, where they were not encased in plastic, failed to reveal any indication of liquid-liquid interface attack of any crevice corrosion. Based on the WM-182 coupon evaluations, which have occurred throughout the life of the tank, the metal loss from the tank wall due to uniform corrosion is not expected to exceed 5.5 x 10-1 mil (0.00 055 inch

Principles for disposal of radioactive and chemical hazardous wastes

International Nuclear Information System (INIS)

Merz, E. R.

1991-01-01

The double hazard of mixed wastes is characterized by several criteria: radioactivity on the one hand, and chemical toxicity, flammability, corrosiveness as well as chemical reactivity on the other hand. Chemotoxic waste normally has a much more complex composition than radioactive waste and appears in much larger quantities. However, the two types of waste have some properties in common when it comes to their long-term impact on health and the environment. In order to minimize the risk associated with mixed waste management, the material assigned for ultimate disposal should be thoroughly detoxified, inertized, or mineralized prior to conditioning and packaging. Good control over the environmental consequence of waste disposal requires that detailed criteria for tolerable contamination should be established, and that compliance with these criteria can be demonstrated. For radioactive waste, there has been an extensive international development of criteria to protect human health. For non-radioactive waste, derived criteria exist only for a limited number of substances

Modeling of oxygen gas diffusion and consumption during the oxic transient in a disposal cell of radioactive waste

International Nuclear Information System (INIS)

De Windt, Laurent; Marsal, François; Corvisier, Jérôme; Pellegrini, Delphine

2014-01-01

Highlights: • This paper deals with the geochemistry of underground HLW disposals. • The oxic transient is a key issue in performance assessment (e.g. corrosion, redox). • A reactive transport model is explicitly coupled to gas diffusion and reactivity. • Application to in situ experiment (Tournemire laboratory) and HLW disposal cell. • Extent of the oxidizing/reducing front is investigated by sensitivity analysis. - Abstract: The oxic transient in geological radioactive waste disposals is a key issue for the performance of metallic components that may undergo high corrosion rates under such conditions. A previous study carried out in situ in the argillite formation of Tournemire (France) has suggested that oxic conditions could have lasted several years. In this study, a multiphase reactive transport model is performed with the code HYTEC to analyze the balance between the kinetics of pyrite oxidative dissolution, the kinetics of carbon steel corrosion and oxygen gas diffusion when carbon steel components are emplaced in the geological medium. Two cases were modeled: firstly, the observations made in situ have been reproduced, and the model established was then applied to a disposal cell for high-level waste (HLW) in an argillaceous formation, taking into account carbon steel components and excavated damaged zones (EDZ). In a closed system, modeling leads to a complete and fast consumption of oxygen in both cases. Modeling results are more consistent with the in situ test while considering residual voids between materials and/or a water unsaturated state allowing for oxygen gas diffusion (open conditions). Under similar open conditions and considering ventilation of the handling drifts, a redox contrast occurs between reducing conditions at the back of the disposal cell (with anoxic corrosion of steel and H 2 production) and oxidizing conditions at the front of the cell (with oxic corrosion of steel). The extent of the oxidizing/reducing front in the

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

Glass containing radioactive nuclear waste

International Nuclear Information System (INIS)

Boatner, L.A.; Sales, B.C.

1985-01-01

Lead-iron phosphate glasses containing a high level of Fe 2 O 3 for use as a storage medium for high-level-radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste, a highly corrosion resistant, homogeneous, easily processed glass can be formed. For corroding solutions at 90 C, with solution pH values in the range between 5 and 9, the corrosion rate of the lead-iron phosphate nuclear waste glass is at least 10 2 to 10 3 times lower than the corrosion rate of a comparable borosilicate nuclear waste glass. The presence of Fe 2 O 3 in forming the lead-iron phosphate glass is critical. Lead-iron phosphate nuclear waste glass can be prepared at temperatures as low as 800 C, since they exhibit very low melt viscosities in the 800 to 1050 C temperature range. These waste-loaded glasses do not readily devitrify at temperatures as high as 550 C and are not adversely affected by large doses of gamma radiation in H 2 O at 135 C. The lead-iron phosphate waste glasses can be prepared with minimal modification of the technology developed for processing borosilicate glass nuclear waste forms. (author)

Corrosion in seawater systems

International Nuclear Information System (INIS)

Henrikson, S.

1988-01-01

Highly alloyed stainless steels have been exposed to natural chlorinated and chlorine-free seawater at 35 deg. C. Simulated tube-tubesheet joints, weld joints and galvanic couples with titanium, 90/10 CuNi and NiAl bronze were tested and evaluated for corrosion. The corrosion rates of various anode materials - zinc, aluminium and soft iron - were also determined. Finally the risk of hydrogen embrittlement of tubes of ferritic stainless steels and titanium as a consequence of cathodic protection was studied. An attempt was also made to explain the cracking mechanism of the ferritic steels by means of transmission electron microscopy. One important conclusion of the project is that chlorinated seawater is considerably more corrosive to stainless steels than chlorine-free water, whereas chlorination reduces the rate of galvanic corrosion of copper materials coupled to stainless steels. Hydrogen embrittlement of ferritic stainless steels and titanium as a consequence of cathodic protection of carbon steel or cast iron in the same structure can be avoided by strict potentiostatic control of the applied potential. (author)

Underground Corrosion of Activated Metals in an Arid Vadose Zone Environment

International Nuclear Information System (INIS)

Adler Flitton, M.K; Mizia, R.E.; Bishop, C.W.

2001-01-01

The subsurface radioactive disposal site located at the Idaho National Engineering and Environmental Laboratory contains neutron-activated metals from nonfuel nuclear-reactor- core components. A long-term corrosion test is being conducted to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements in an arid vadose zone environment. The tests use nonradioactive metal coupons representing the prominent neutron-activated material buried at the disposal location, namely, Type 304L stainless steel, Type 315L stainless steel, nickel-chromium alloy (UNS NO7718), beryllium, aluminum 6061-T6, and a zirconium alloy, (UNS R60804). In addition, carbon steel (the material presently used in the cask disposal liners and other disposal containers) and a duplex stainless steel (UNS S32550) (the proposed material for the high- integrity disposal containers) are also included in the test program. This paper briefly describes the test program and presents the early corrosion rate results after 1 year and 3 years of underground exposure

Applications in the Nuclear Industry for Corrosion-Resistant Amorphous-Metal Thermal-Spray Coatings

International Nuclear Information System (INIS)

Farmer, J; Choi, J

2007-01-01

Amorphous metal and ceramic thermal spray coatings have been developed that can be used to enhance the corrosion resistance of containers for the transportation, aging and disposal of spent nuclear fuel and high-level radioactive wastes. Fe-based amorphous metal formulations with chromium, molybdenum and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials, and their stability at high neutron doses, enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for container applications, though the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas atomized powders and applied as near full density, non-porous coatings with the high-velocity oxy-fuel process. This paper summarizes the performance of these coatings as corrosion-resistant barriers, and as neutron absorbers. Relevant corrosion models are also discussed, as well as a cost model to quantify the economic benefits possible with these new materials

Corrosion of porous silicon in tetramethylammonium hydroxide solution

International Nuclear Information System (INIS)

Lai, Chuan; Li, Xue-Ming; Zou, Li-Ke; Chen, Qiang; Xie, Bin; Li, Yu-Lian; Li, Xiao-Lin; Tao, Zhi

2014-01-01

Highlights: • The corrosion of porous silicon in (CH 3 ) 4 NOH solution was studied. • The residue of corrosion products was a mixture of [(CH 3 ) 4 N] 2 SiO 3 and SiO 2 . • The effect factors for porous silicon corrosion were elaborately investigated. • The additive of ethanol in (CH 3 ) 4 NOH solution could reduce the corrosion rate. • The 1.0 M (CH 3 ) 4 NOH could act as an applicable and novel corrosion solution. - Abstract: Corrosion of porous silicon in tetramethylammonium hydroxide (TMAH) solution was studied using weight loss measurements and scanning electron microscope. The effects of temperature, concentration of TMAH and volume ratio of ethanol in 1.0 M TMAH on corrosion rate and corrosion time were elaborately investigated. The residue of corrosion products were characterized as a mixture of [(CH 3 ) 4 N] 2 SiO 3 and SiO 2 . A comparative test among TMAH, KOH and NaOH illustrated that the 1.0 M TMAH could act as an applicable and novel corrosion solution to remove porous silicon layer for determining the porosity of porous silicon

Microbial corrosion of steel in Toarcian argillite: potential influence of bio-films

International Nuclear Information System (INIS)

Urios, L.; Desneux, J.; Magot, M.; Perez, A.; Mercier, F.; Dillmann, P.; Wittebroodt, C.; Dauzeres, A.; Marsal, F.

2012-01-01

Document available in extended abstract form only. In the context of a geological disposal of radioactive waste in clayey formations, the consequences of microbial activity are of concern regarding the corrosion of metallic components, such as the overpack surrounding vitrified waste. Generalized corrosion is one of the main processes taken into account in the dimensioning of these overpacks. However, the presence of microorganisms such as sulfate- or thiosulfate-reducing bacteria in the host rock in contact with these non-alloy materials may enhance localized corrosion processes, leading to a premature and undesirable loss of watertightness. Moreover, the passive corrosion layer, which is formed progressively during the generalized corrosion process and induces a decrease of corrosion rates, may react with iron-reducing bacteria and thus reactivate corrosion. The formation of bio-films may also lead to significant modifications of environment at the biofilm/metal interface in terms of pH, dissolved oxygen, organic and inorganic species, that may lead to electrochemical reactions that could potentially increase corrosion rates. There is thus a need for further investigations of the potential consequences on the physico-chemical conditions within geological disposal facilities. The French Institute for Radiological Protection and Nuclear Safety (IRSN) has been conducting research programs since 1991 in the Tournemire Underground Research Laboratory (URL), a railway tunnel which crosses a Toarcian argillaceous formation. This geological layer is particularly interesting for its physical and chemical properties close to those of Callovo-Oxfordian argillite. The importance of microbial processes in this formation was first shown by the study of time evolution of the chemical and isotopic compositions of fracture groundwaters collected in several boreholes. These investigations suggested that aqueous sulphates and their isotopic composition were controlled by bacterial

Corrosion and protection of aluminum alloys in seawater

Energy Technology Data Exchange (ETDEWEB)

Nisancioglu Kemal [Department of Materials Technology, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

2004-07-01

The paper deals with pitting and uniform corrosion and effectiveness of cathodic protection in reducing these corrosion forms. In stagnant waters or presence of low flow rates, pitting may occur. However, pitting corrosion, driven by the Fe-rich cathodic intermetallic compounds, is often of superficial nature. The pits tend to passivate as a result of etching or passivation of the intermetallics with time. Cathodic protection is an effective way of preventing pitting. It also requires low current densities since the cathodic area, defined by the Fe-rich intermetallics, is small in contrast to steel, which is uniformly accessible to the cathodic reaction. Although thermodynamic calculations suggest possible instability of the oxide in slightly alkaline solutions, such as seawater, protective nature of the oxide in practice is attributed to the presence of alloying elements such as Mg and Mn. Thus, the passivity of both the aluminum matrix alloy (the anode) and the intermetallics (cathodes) have to be considered in evaluating the corrosion and protection of aluminum alloys. With increasing flow rate, the possibility of pitting corrosion reduces with increase in the rate of uniform corrosion, which is controlled by the flow dependent chemical dissolution of the oxide. Cathodic protection does not stop this phenomenon, and coatings have to be used. (authors)

USDOE radioactive waste incineration technology: status review

International Nuclear Information System (INIS)

Borduin, L.C.; Taboas, A.L.

1980-01-01

Early attempts were made to incinerate radioactive wastes met with operation and equipment problems such as feed preparation, corrosion, inadequate off-gas cleanup, incomplete combustion, and isotope containment. The US Department of Energy (DOE) continues to sponsor research, development, and the eventual demonstration of radioactive waste incineration. In addition, several industries are developing proprietary incineration system designs to meet other specific radwaste processing requirements. Although development efforts continue, significant results are available for the nuclear community and the general public to draw on in planning. This paper presents an introduction to incineration concerns, and an overview of the prominent radwaste incineration processes being developed within DOE. Brief process descriptions, status and goals of individual incineration systems, and planned or potential applications are also included

Effects of Alloyed Carbon on the General Corrosion and the Pitting Corrosion Behavior of FeCrMnN Stainless Steels

Energy Technology Data Exchange (ETDEWEB)

Ha, Heon-Young; Lee, Tae-Ho; Kim, Sung-Joon [Korea Institute of Materials Science, Changwon (Korea, Republic of)

2011-10-15

The effects of alloyed carbon on the pitting corrosion, the general corrosion, and the passivity behavior of Fe{sub 1}8Cr{sub 1}0Mn{sub 0}.4Nx{sub C} (x=0 ⁓ 0.38 wt%) alloys were investigated by various electrochemical methods and XPS analysis. The alloyed carbon increased the general corrosion resistance of the FeCrMnN matrix. Carbon enhanced the corrosion potential, reduced the metal dissolution rate, and accelerated the hydrogen evolution reaction rate in various acidic solutions. In addition, carbon promoted the pitting corrosion resistance of the matrix in a chloride solution. The alloyed carbon in the matrix increased the chromium content in the passive film, and thus the passive film became more protective.

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Corrosion products, activity transport and deposition in boiling water reactor recirculation systems

International Nuclear Information System (INIS)

Alder, H.P.; Buckley, D.; Grauer, R.; Wiedemann, K.H.

1992-01-01

The deposition of activated corrosion products in the recirculation loops of Boiling Water Reactors produces increased radiation levels which lead to a corresponding increase in personnel radiation dose during shut down and maintenance. The major part of this dose rate is due to cobalt-60. Based on a comprehensive literature study concerning this theme, it has been attempted to identify the individual stages of the activity build-up and to classify their importance. The following areas are discussed in detail: The origins of the corrosion products and of cobalt-59 in the reactor feedwaters; the consolidation of the cobalt in the fuel pins deposits (activation); the release and transport of cobalt-60; the build-up of cobalt-60 in the corrosion products in the recirculation loops. Existing models of the build-up of circuit radioactivity are discussed and the operating experiences from selected reactors are summarized. 90 refs, figs and tabs

Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

2000-01-01

corrosion rates, when biofilm and corrosion products cover the steel surface. However, EIS might be used for detection of MIC. EN is a suitable technique to characterise the type of corrosion attack, but is unsuitable for corrosion rate estimation. The concentric electrodes galvanic probe arrangement......Abstract Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC...... of carbon steel must be monitored on-line in order to provide an efficient protection and control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic...

Mechanism of pitting corrosion prevention by nitrite in carbon steel exposed to dilute salt solutions. 1998 annual progress report

International Nuclear Information System (INIS)

Zapp, P.E.; Zee, J. van.

1998-01-01

'The overall goal of this project is to develop a fundamental understanding of the role of nitrite in preventing the breakdown of protective oxide(s) on carbon steel and the onset of pitting. Pitting corrosion of carbon steel exposed to dilute alkaline salt solutions can be induced by nitrate, sulfate, and chloride ions and is prevented by sufficient concentration of nitrite. A significant example of this material/electrolyte system is the storage and processing of DOE''s high-level radioactive liquid waste in carbon steel tanks. Added nitrite in the waste has a considerable downstream impact on the immobilization of the waste in a stable glass form. Waste tank integrity and glass production efficiency may benefit from the fundamental understanding of nitrite''s role in preventing pitting. This report summarizes progress after approximately six months of effort in this three-year EMSP project. Initial experimental and theoretical work has focused on the electrochemical behavior of carbon steel in simplified non-radioactive solutions that simulate complex dilute radioactive waste solutions. These solutions contain corrosion-inducing species such as nitrate and chloride and the corrosion-inhibiting nitrite at moderately alkaline pHs. The electrochemical behavior of interest here is that of the open-circuit potential of the steel specimen at equilibrium in the experimental electrolyte and the measures of the steel''s passivity and passivity breakdown.'

Cask for radioactive material and method for preventing release of neutrons from radioactive material

International Nuclear Information System (INIS)

Gaffney, M.F.; Shaffer, P.T.

1981-01-01

A cask for radioactive material, such as nuclear reactor fuel or spent nuclear reactor fuel, includes a plurality of associated walled internal compartments for containing such radioactive material, with neutron absorbing material present to absorb neutrons emitted by the radioactive material, and a plurality of thermally conductive members, such as longitudinal copper or aluminum castings, about the compartment and in thermal contact with the compartment walls and with other such thermally conductive members and having thermal contact surfaces between such members extending, preferably radially, from the compartment walls to external surfaces of the thermally conductive members, which surfaces are preferably in the form of a cylinder. The ends of the shipping cask also preferably include a neutron absorber and a conductive metal covering to dissipate heat released by decay of the radioactive material. A preferred neutron absorber utilized is boron carbide, preferably as plasma sprayed with metal powder or as particles in a matrix of phenolic polymer, and the compartment walls are preferably of stainless steel, copper or other corrosion resistant and heat conductive metal or alloy. The invention also relates to shipping casks, storage casks and other containers for radioactive materials in which a plurality of internal compartments for such material, e.g., nuclear reactor fuel rods, are joined together, preferably in modular construction with surrounding heat conductive metal members, and the modules are joined together to form a major part of a finished shipping cask, which is preferably of cylindrical shape. Also within the invention are methods of safely storing radioactive materials which emit neutrons, while dissipating the heat thereof, and of manufacturing the present shipping casks

Steamgenerators corrosion monitoring and chemical cleanings

International Nuclear Information System (INIS)

Otchenashev, G.

2001-01-01

One of the most important secondary side water chemistry objectives is optimization of chemistry conditions to reduce materials corrosion and their products transport into steam generators. Corrosion products (mainly iron and copper oxides) can form deposits on the SG's tubes and essentially decrease their operating resource. The transport of corrosion products by the constant flowrate of feed and blowdown water depends only on their content in these streams. All the internal surfaces (walls, collectors, tubes) were covered with the tough deposit firmly connected with the surface. Corrosion under this deposit was not detected. In some places sludge unconnected with the surface was detected. The lower tubes are located the more unconnected sludge was detected. On SG bottom near the hatch the sludge thickness was about 3 cm. (R.P.)

Suppression of aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

Energy Technology Data Exchange (ETDEWEB)

Fujieda, S., E-mail: fujieda@tagen.tohoku.ac.jp; Fukamichi, K.; Suzuki, S.

2014-07-05

Highlights: • The aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration.

Biological fate of cobalt-60 released during the corrosion of neutron-activated stanless steel in seawater

International Nuclear Information System (INIS)

Young, J.S.

1982-03-01

Passing seawater over radioactive Type 347 stainless steel in a sediment/seawater laboratory system and exposing marine animals to this environment provided information on the bioaccumulation of 60 Co from radioactive structural material. Exposure of marine organisms to radioactive corrosion products and directly to radioactive stainless steel in seawater simulated some of the possible conditions which could arise from the deposition of radioactive stainless steel on the ocean floor. Detectable levels of 60 Co in marine animals were not observed on a short term basis (5 weeks). Longterm (13 months) exposure of marine animals in a sediment/seawater system resulted in 60 Co bioaccumulation. The specific activity of 60 Co in the organisms was as much as one million times less than that initially present in the radioactive stainless steel. This was due to the dilution of 60 Co by stable cobalt in the seawater, sediments and organisms. As expected the 60 Co specific activity of the organisms never increased above that of the radioactive source. This is because 60 Co is chemicaly indistinguishable from stable Co. Increasing 60 Co concentration factors with decreasing 60 Co concentrations in the seawater and sediment media coupled with relatively constant 60 Co specific activities suggest a possible homeostatic control of cobalt concentrations in certain marine organisms. The evidence indicates that the marine animals derived more of the accumulated 60 Co from the sediments and interstitial water than from seawater. Cobalt-60 concentration factors were generally found to be lower than published cobalt concentration factors due to the predominantly insoluble nature of the corrosion products. Baseline information is provided on trace element concentrations in deep-sea organisms. Stable Co and twenty other elements were measured in abyssal invertebrates and a fish

Research and development activities at INE concerning corrosion of final repository container materials; F and E-Arbeiten zur Korrosion von Endlager-Behaelterwerkstoffen im INE

Energy Technology Data Exchange (ETDEWEB)

Kienzler, Bernhard

2017-10-01

The present work provides a historical overview of the research and development activities carried out at the (Nuclear) Research Center Karlsruhe (today KIT) since the beginning of the 1980s on the corrosion of materials which might be suitable for construction of containers for highly radioactive wastes. The report relates almost exclusively to the work performed by Dr. Emmanuel Smailos, who elaborated the corrosion of various materials at the Institute for Nuclear Waste Disposal (INE). The requirements for the containers and materials, which were subject to changes in time, are presented. The changes were strongly influenced by the changed perception of the use of nuclear energy. The selection of the materials under investigations, the boundary conditions for the corrosion experiments and the analytical methods are described. Results of the corrosion of the materials such as finegrained steel, Hastelloy C4, nodular cast iron, titanium-palladium and copper or copper-nickel alloys in typical salt solutions are summarized. The findings of special investigations, e.g. corrosion under irradiation or the influence of sulfide on the corrosion rates are shown. For construction of disposal canisters, experiments were conducted to determine the contact corrosion, the influence of the hydrogen embrittlement of Ti-Pd and fine-grained steels on the corrosion behavior as well as the corrosion behavior of welding and the influence of different welding processes with the resulting heat-affected zones on the corrosion behavior. The work was contributed to several European research programs and was well recognized in the USA. Investigations on the corrosion of steels in non-saline solutions and corrosion under interim storage conditions as well as under the expected conditions of the Konrad repository for low-level radioactive wastes are also described. In addition, the experiments on ceramic materials are presented and the results of the corrosion of Al{sub 2}O{sub 3} and Zr

Evaluation of S-type fiberglass composites for use in high-level radioactive waste environments

International Nuclear Information System (INIS)

Parra, S.A.

1996-01-01

Two types of S-type fiberglass materials were evaluated for use in a high-level radioactive waste environment. The S-type fiberglass composites tested were in the form of tubes and were exposed to a simulated high-level radioactive waste environment consisting of corrosive chemicals, high gamma radiation, and elevated temperatures. The physical properties of the exposed and unexposed tube samples were compared to determine the effects of the simulated environment on the S-type fiberglass composites

A new corrosion monitoring technique

International Nuclear Information System (INIS)

Brown, Gerald K.

2000-01-01

Internal Corrosion Monitoring has relied upon 5 basic techniques. Little improvement in performance has been achieved in any of these. Many newer internal corrosion monitoring techniques have proved of little value in the field although some have instances of success in the laboratory. Industry has many high value hydrocarbon applications requiring corrosion rate monitoring for real-time problem solving and control. The high value of assets and the cost of asset replacement makes it necessary to practice cost effective process and corrosion control with sensitivity beyond the 5 basic techniques. This new metal loss technology offers this sensitivity. Traditional metal loss technology today provides either high sensitivity with short life, or conversely, long life but with substantially reduced sensitivity. The new metal loss technology offers an improved working life of sensors without significantly compromising performance. The paper discusses the limitations of existing on-line technologies and describes the performance of a new technology. This new metal loss technology was introduced at NACE Corrosion 99'. Since that time several field projects have been completed or are ongoing. This paper will discuss the new metal loss technology and report on some of the data that has been obtained.(author)

Conditioning of solid radioactive wastes (1960); Conditionnement des dechets radioactifs solides (1960)

Energy Technology Data Exchange (ETDEWEB)

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

1960-07-01

Since solid radioactive wastes are of varied forms, dimensions and volumes, the C.E.A. first reduces the volume by breaking up and compacting. Since these wastes cannot be temporarily stored without contamination risk, an effective packing process has been devised and carried through. This consists in burying the wastes in a specially planned concrete with the following characteristics: - high mechanical resistance; - maximum insolubility; - resistance to corrosion; - maximum imperviousness; - providing protection against radiation. It is then possible to store the blocks safely, with a view to eventual definitive rejection. (author) [French] Les dechets actifs solides etant de formes, de dimensions et de volumes varies, le C.E.A. procede en premier lieu a une reduction de volume par fractionnement et compactage. L'emmagasinage provisoire de tels dechets ne pouvant se concevoir sans risques de contamination, un procede efficace d'emballage a ete etudie et realise. Il consiste a noyer les dechets dans un beton specialement etudie qui presente les caracteristiques suivantes: - forte resistance mecanique; - insolubilite maximum; - resistance a la corrosion; - etancheite maximum; - protection contre le rayonnement. Il est alors possible de conserver sans danger les blocs formes en vue d'un rejet definitif ulterieur. (auteur)

An assessment of corrosion life of copper overpack

International Nuclear Information System (INIS)

Honda, A.; Taniguchi, N.

1999-08-01

Corrosion life of copper overpack is estimated on the basis of current understandings of copper corrosion processes. The assessment is based on the mass balance. Oxygen and sulfide were taken into account as corrosive species. The sulfate existing in bentonite is assumed to be reduced to sulfide by sulfate reducing bacteria and corrodes copper overpacks. Pitting is involved in the assesment using two methods. One method is use of pitting factor acquired from analysis of archeological artifacts. The other is use of extreme value statistical technique. The time evolution of parameters for cumulative probability distribution function, Gumbel distribution, was estimated using the data from copper specimens buried in various soil and archeological artifacts of the bronze age. The pitting depth for 1000 years is estimated using the parameters for probability distribution function. The result of estimation shows 39-mm is the maximum penetration for 1000 years. Natural analogue data suggest the corrosion rate of 3 mm/1000 years. Therefore the estimation is considered to be conservative. (author)

Enhanced Biodegradability, Lubricity and Corrosiveness of Lubricating Oil by Oleic Acid Diethanolamide Phosphate

Directory of Open Access Journals (Sweden)

Fang Jianhua

2012-09-01

Full Text Available Impacts of oleic acid diethanolamide phosphate (abbreviated as ODAP as an additive on biodegradability, anti-wear capacity, friction-reducing ability and corrosiveness of an unreadily biodegradable HVI 350 mineral lubricating oil was studied. The biodegradabilities of neat lubricating oil and its formulations with ODAP were evaluated on a biodegradation tester. Furthermore, the anti-wear and friction-reducing abilities and the corrosiveness of neat oil and the formulated oils were determined on a four-ball tribotester and a copper strip corrosion tester, respectively. The results indicated that ODAP markedly enhanced biodegradability as well as anti-wear and friction-reducing abilities of the lubricating oil. On the other hand, excellent color ratings of copper strips for both neat oil and the ODAP-doped oil were obtained in the corrosion tests, demonstrating that the corrosiveness of neat oil and the doped oil was negligible, although the latter seemed to provide slightly better anti-corrosion ability.

Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

Science.gov (United States)

Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

2018-04-01

In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

Decontaminating method for radioactive contaminant

International Nuclear Information System (INIS)

Suzuki, Ken-ichi.

1994-01-01

After decontamination of radioactive contaminates with d-limonene, a radioactive material separating agent not compatible with liquid wastes caused by decontamination is added to the liquid wastes. Then after stirring, they are stood still to be separated into two phases, and the radioactive materials in the liquid waste phase caused by decontamination are transferred to the phase of the radioactive material separating agent. With such procedures, they can satisfactorily be separated into two phases of d-limonene and the radioactive material separating agent. Further, d-limonene remaining after the separation can be used again as a decontaminating agent for radioactive contaminates. Therefore, the amount of d-limonene to be used can be reduced, to lower the cost for cleaning, thereby enabling to reduce the amount of radioactive wastes formed. (T.M.)

Corrosion of steel drums containing cemented ion-exchange resins as intermediate level nuclear waste

Science.gov (United States)

Duffó, G. S.; Farina, S. B.; Schulz, F. M.

2013-07-01

Exhausted ion-exchange resins used in nuclear reactors are immobilized by cementation before being stored. They are contained in steel drums that may undergo internal corrosion depending on the presence of certain contaminants. The objective of this work is to evaluate the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins with different aggressive species. The corrosion potential and the corrosion rate of the steel, and the electrical resistivity of the matrix were monitored for 900 days. Results show that the cementation of ion-exchange resins seems not to pose special risks regarding the corrosion of the steel drums. The corrosion rate of the steel in contact with cemented ion-exchange resins in the absence of contaminants or in the presence of 2.3 wt.% sulphate content remains low (less than 0.1 μm/year) during the whole period of the study (900 days). The presence of chloride ions increases the corrosion rate of the steel at the beginning of the exposure but, after 1 year, the corrosion rate drops abruptly reaching a value close to 0.1 μm/year. This is probably due to the lack of water to sustain the corrosion process. When applying the results obtained in the present work to estimate the corrosion depth of the steel drums containing the cemented radioactive waste after a period of 300 years, it is found that in the most unfavourable case (high chloride contamination), the corrosion penetration will be considerably lower than the thickness of the wall of the steel drums. Cementation of ion-exchange resins does not seem to pose special risks regarding the corrosion of the steel drums that contained them; even in the case the matrix is highly contaminated with chloride ions.

Leak test of the pipe line for radioactive liquid waste

International Nuclear Information System (INIS)

Machida, Chuji; Mori, Shoji.

1976-01-01

In the Tokai Research Establishment, most of the radioactive liquid waste is transferred to a wastes treatment facility through pipe lines. As part of the pipe lines a cast iron pipe for town gas is used. Leak test has been performed on all joints of the lines. For the joints buried underground, the test was made by radioactivity measurement of the soil; and for the joints in drainage ditch by the pressure and bubble methods. There were no leakage at all, indicating integrity of all the joints. On the other hand, it is also known by the other test that the corrosion of inner surface of the piping due to liquid waste is only slight. The pipe lines for transferring radioactive liquid waste are thus still usable. (auth.)

Study of sulphate-reducing bacteria corrosion in the weld joint for API X-70 steel

Directory of Open Access Journals (Sweden)

Flores, J. E.

2012-10-01

Full Text Available The corrosion behavior originated by sulfate-reducing bacteria (SRB was studied in two regions of welded API X-70 steel pipeline. The studies were focused on base material (BM and heat affected zone (HAZ, from the internal region of the pipe. SRB were extracted from oil and grown in a Postgate medium. Corrosion was evaluated at 60 °C for times between 5 and 64 days. Potentiodynamic polarization curves, obtained by electrochemical techniques, indicated surface activation at short times. Structural and morphological characterizations were carried out by scanning electron microscopy (SEM and optical microscopy (OM. H₂S concentration and pH were also measured. Results showed an important increase in the corrosion damage up to 20 days, influenced by the SRB activity, which lead to a maximum of H₂S (pH minimum. It was found a localized corrosion attack in the HAZ in a higher quantity compared to BM; and the formation of a thin film on the steel surface, originated by corrosion products and bacterial activity.

El comportamiento ante la corrosión, originada por bacterias sulfato-reductoras (SRB, fue estudiado en dos regiones de un tubo de acero soldado API X-70. Los estudios se enfocaron en el material base (BM y la zona afectada térmicamente (HAZ, en la parte interna del tubo. Las SRB fueron extraídas del petróleo y cultivadas en un medio Postgate. El comportamiento a la corrosión fue evaluado a una temperatura de 60 °C, por periodos comprendidos entre 5 y 64 días. El análisis de las curvas de polarización potenciodinámicas, obtenidas por técnicas electroquímicas, indicó la activación de la superficie para tiempos cortos. La superficie fue caracterizada estructural y morfológicamente mediante microscopia electrónica de barrido (SEM, así como mediante microscopía óptica (OM. La concentración de H₂S y el pH también fueron medidos. Los resultados mostraron un aumento importante de la corrosi

Analysis of corrosion-product transport using nondestructive XRF and MS techniques

International Nuclear Information System (INIS)

Sawicka, B.D.; Sawicki, J.A.

1998-01-01

This paper describes the application of X-ray fluorescence (XRF) and Moessbauer spectroscopy (MS) techniques to monitor corrosion-product transport (CPT) in water circuits of nuclear reactors. The combination of XRF and MS techniques was applied in studies of CPT crud filters from both primary- and secondary-side water circuits (i.e., radioactive and nonradioactive specimens) of CANDU reactors. The XRF-MS method allows nondestructive analysis of species collected on filters and provides more complete information about corrosion products than commonly used digestive methods of chemical analysis. Recent analyses of CPT specimens from the Darlington Nuclear Generating Station (NGS) primary side and the Bruce B NGS feedwater system are shown as examples. Some characteristics of primary and secondary water circuits are discussed using these new data. (author)

General Atomic's radioactive gas recovery system

International Nuclear Information System (INIS)

Mahn, J.A.; Perry, C.A.

1975-01-01

General Atomic Company has developed a Radioactive Gas Recovery System for the HTGR which separates, for purposes of retention, the radioactive components from the non-radioactive reactor plant waste gases. This provides the capability for reducing to an insignificant level the amount of radioactivity released from the gas waste system to the atmosphere--a most significant improvement in reducing total activity release to the environment. (U.S.)

Assessment of Corrosion Characteristics and Development of Remedial Technologies in Nuclear Materials

Energy Technology Data Exchange (ETDEWEB)

Kim, Hong Pyo; Kim, J. S.; Lim, Y. S. (and others)

2007-04-15

In general, materials having superior resistance to corrosion are used for main components and structures in nuclear power plants (NPPs) to improve their safety. During long-term operations in the high temperature and pressure environment, however, localized-corrosion related degradations occur frequently in those materials, leading to unexpected shutdown of the plants. The unexpected shutdowns may lower the operating efficiency of the power generation and expand the repair period, which results in a huge economical loss. Moreover, since the damages may cause a leakage of the primary coolant that brings about a contamination by radioactive substances, the corrosion related degradations of structural materials have become a menace to the safety of NPPs. The steam generator tubes forming a boundary between the primary and secondary sides of NPPs are one of the main components that are most damaged by corrosion. Therefore, it is strongly required to verify the degradation mechanisms of Alloy 182 and Alloy 600 materials used in the steam generator tubes and primary systems, to establish remedial techniques for the degradations, to manage the damages, and to develop techniques for the extension of the plant's life. In this study, (1) the assessment techniques of corrosion damages were improved and the database of the obtained results were established. (2) The basic technologies of the management of corrosion damages were developed for the practical use. (3) The fundamental technologies for inhibition and repair of corrosion damages were also developed. The results of this project are applicable to the assessment, failure analysis and life estimation of the materials against corrosion damages. The assessment data obtained in this work are available for the technical references of the corrosion failures of components in NPPs during operation. Furthermore, it is applicable to establish materials design requirements, to establish the optimum operation condition and to

A probabilistic approach to assessing radioactive waste container lifetimes

International Nuclear Information System (INIS)

Porter, F.M.; Naish, C.C.; Sharland, S.M.

1994-01-01

A general methodology has been developed to make assessments of the lifetime of specific radioactive waste container designs in a repository environment. The methodology employs a statistical approach, which aims to reflect uncertainty in the corrosion rates, and the evolution of the environmental conditions. In this paper, the methodology is demonstrated for an intermediate-level waste (ILW) container in the anticipated UK repository situation

Corrosion

Science.gov (United States)

Slabaugh, W. H.

1974-01-01

Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

Role and efforts of T3C in corrosion economics

International Nuclear Information System (INIS)

Perrigo, L.D.; Appleman, B.R.; Pamer, R.I.; Thompson, J.L.

1979-11-01

The basic purpose of T3C activity is to show how to acquire specific corrosion cost information so that overall costs for doing business can be reduced. The scope of T3C is to accumulate data, appraise methods, develop recommended practices, promote knowledge and communicate relative to the economic evaluation of corrosion and counter corrosion techniques

The aluminum chemistry and corrosion in alkaline solutions

International Nuclear Information System (INIS)

Zhang Jinsuo; Klasky, Marc; Letellier, Bruce C.

2009-01-01

Aluminum-alkaline solution systems are very common in engineering applications including nuclear engineering. Consequently, a thorough knowledge of the chemistry of aluminum and susceptibility to corrosion in alkaline solutions is reviewed. The aluminum corrosion mechanism and corrosion rate are examined based on current experimental data. A review of the phase transitions with aging time and change of environment is also performed. Particular attention is given to effect of organic and inorganic ions. As an example, the effect of boron is examined in detail because of the application in nuclear reactor power systems. Methods on how to reduce the corrosion rate of aluminum in alkaline solutions are also highlighted

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

Corrosion and indices of operating reliability of steam-water circuits of foreign NPP

International Nuclear Information System (INIS)

Martynova, O.I.

1983-01-01

Corrosion failures in circuits of foreign NPPs are considered. According to American statistics there are more corrosion failures in two-circuit NPPs than in NPPs with one circuit. Steam generators mostly suffer from ''corrosion denting''. Lately pitting corrosion becomes a potentially serious problem. Steam generator vertical tubes are maiply subjected to this corrosion type. Attention is drawn to intercrystalline corrosion. The causes of corrosion are described. The problem of optimization of structural materials is discussed to reduce corrosion failures as well as other methods of decreasing corrosion failures. Organization of nondestructive testing, increased requirements to water and steam purity are of great importance

Regional cooperation to reduce the safety and security risks of Orphan radioactive sources

International Nuclear Information System (INIS)

Howard, Geoffrey; Hacker, Celia; Murray, Allan; Romallosa, Kristine; Caseria, Estrella; Africa del Castillo, Lorena

2008-01-01

ANSTO's Regional Security of Radioactive Sources (RSRS) Project, in cooperation with the Philippine Nuclear Research Institute (PNRI), has initiated a program to reduce the safety and security risks of orphan radioactive sources in the Philippines. Collaborative work commenced in February 2006 during the Regional Orphan Source Search and Methods Workshop, co-hosted by ANSTO and the US National Nuclear Security Administration. Further professional development activities have occurred following requests by PNRI to ANSTO to support improvements in PNRI's capability and training programs to use a range of radiation survey equipment and on the planning and methods for conducting orphan source searches. The activities, methods and outcomes of the PNRI-ANSTO cooperative program are described, including: i.) Delivering a training workshop which incorporates use of source search and nuclide identification equipment and search methodology; and train-the-trainer techniques for effective development and delivery of custom designed training in the Philippines; ii.) Support and peer review of course work on Orphan Source Search Equipment and Methodology developed by PNRI Fellows; iii.) Supporting the delivery of the inaugural National Training Workshop on Orphan Source Search hosted by PNRI in the Philippines; iv.) Partnering in searching for orphan sources in Luzon, Philippines, in May 2007. The methods employed during these international cooperation activities are establishing a new model of regional engagement that emphasises sustainability of outcomes for safety and security of radioactive sources. (author)

Corrosion of tungsten microelectrodes used in neural recording applications.

Science.gov (United States)

Patrick, Erin; Orazem, Mark E; Sanchez, Justin C; Nishida, Toshikazu

2011-06-15

In neuroprosthetic applications, long-term electrode viability is necessary for robust recording of the activity of neural populations used for generating communication and control signals. The corrosion of tungsten microwire electrodes used for intracortical recording applications was analyzed in a controlled bench-top study and compared to the corrosion of tungsten microwires used in an in vivo study. Two electrolytes were investigated for the bench-top electrochemical analysis: 0.9% phosphate buffered saline (PBS) and 0.9% PBS containing 30 mM of hydrogen peroxide. The oxidation and reduction reactions responsible for corrosion were found by measurement of the open circuit potential and analysis of Pourbaix diagrams. Dissolution of tungsten to form the tungstic ion was found to be the corrosion mechanism. The corrosion rate was estimated from the polarization resistance, which was extrapolated from the electrochemical impedance spectroscopy data. The results show that tungsten microwires in an electrolyte of PBS have a corrosion rate of 300-700 μm/yr. The corrosion rate for tungsten microwires in an electrolyte containing PBS and 30 mM H₂O₂ is accelerated to 10,000-20,000 μm/yr. The corrosion rate was found to be controlled by the concentration of the reacting species in the cathodic reaction (e.g. O₂ and H₂O₂). The in vivo corrosion rate, averaged over the duration of implantation, was estimated to be 100 μm/yr. The reduced in vivo corrosion rate as compared to the bench-top rate is attributed to decreased rate of oxygen diffusion caused by the presence of a biological film and a reduced concentration of available oxygen in the brain. Copyright © 2011 Elsevier B.V. All rights reserved.

Multibarrier system preventing migration of radionuclides from radioactive waste repository

Directory of Open Access Journals (Sweden)

Olszewska Wioleta

2015-09-01

Full Text Available Safety of radioactive waste repositories operation is associated with a multibarrier system designed and constructed to isolate and contain the waste from the biosphere. Each of radioactive waste repositories is equipped with system of barriers, which reduces the possibility of release of radionuclides from the storage site. Safety systems may differ from each other depending on the type of repository. They consist of the natural geological barrier provided by host rocks of the repository and its surroundings, and an engineered barrier system (EBS. The EBS may itself comprise a variety of sub-systems or components, such as waste forms, canisters, buffers, backfills, seals and plugs. The EBS plays a major role in providing the required disposal system performance. It is assumed that the metal canisters and system of barriers adequately isolate waste from the biosphere. The evaluation of the multibarrier system is carried out after detailed tests to determine its parameters, and after analysis including mathematical modeling of migration of contaminants. To provide an assurance of safety of radioactive waste repository multibarrier system, detailed long term safety assessments are developed. Usually they comprise modeling of EBS stability, corrosion rate and radionuclide migration in near field in geosphere and biosphere. The principal goal of radionuclide migration modeling is assessment of the radionuclides release paths and rate from the repository, radionuclides concentration in geosphere in time and human exposure to ionizing radiation

A modelling study for long-term life prediction of carbon steel overpack for geological isolation of High-Level Radioactive Waste

International Nuclear Information System (INIS)

Taniguchi, Naoki; Honda, Akira; Ishikawa, Hirohisa

1996-01-01

Current plans for the geological disposal of High-Level Radioactive Waste (HLW) in Japan include metal overpacks which contain HLW. Overpacks may be required to remain intact for more than several hundred years in order to provide containment of radio nuclides. The main factor limiting the performance of overpacks is considered to be corrosion by groundwater. Carbon steel is one of the candidate material for overpacks. A mathematical model for life prediction of carbon steel overpack has been developed based on corrosion mechanism. General corrosion and localized corrosion are considered because these are likely to initiate in repository conditions. In general corrosion model, the reduction of oxygen and water are considered as cathodic reaction. In localized corrosion model, we have constructed a model which predict the period for localized corrosion based on oxygen transport in bentonite. We also developed a model which predict the propagation rate of localized corrosion that is based on mass balance within the corroding cavity. (author)

Prevention of nuclear fuel cladding materials corrosion

International Nuclear Information System (INIS)

Yang, K.R.; Yang, J.C.; Lee, I.C.; Kang, H.D.; Cho, S.W.; Whang, C.K.

1983-01-01

The only way which could be performed by the operator of nuclear power plant to minimizing the degradation of nuclear fuel cladding material is to control the water quality of primary coolant as specified standard conditions which dose not attack the cladding material. If the water quality of reactor coolant does not meet far from the specification, the failure will occure not only cladding material itself but construction material of primary system which contact with the coolant. The corrosion product of system material are circulate through the whole primary system with the coolant and activated by the neutron near the reactor core. The activated corrosion products and fission products which released from fuel rod to the coolant, so called crud, will repeate deposition and redeposition continuously on the fuel rod and construction material surface. As a result we should consider heat transfer problem. In this study following activities were performed; 1. The crud sample was taken from the spent fuel rod surface of Kori unit one and analized for radioactive element and non radioactive chemical species. 2. The failure mode of nuclear fuel cladding material was estimated by the investigation of releasing type of fission products from the fuel rod to the reactor coolant using the iodine isotopes concentration of reactor coolants. 3. A study was carried out on the sipping test results of spent fuel and a discussion was made on the water quality control records through the past three cycle operation period of Kori unit one plant. (Author)

Treating radioactive effluent

International Nuclear Information System (INIS)

Kirkham, I.A.

1981-01-01

In the treatment of radioactive effluent it is known to produce a floc being a suspension of precipitates carrying radioactive species in a mother liquor containing dissolved non-radioactive salts. It is also known and accepted practice to encapsulate the floc in a solid matrix by treatment with bitumen, cement and the like. In the present invention the floc is washed with water prior to encapsulation in the solid matrix whereby to displace the mother liquor containing the dissolved non-radioactive salts. This serves to reduce the final amount of solidified radioactive waste with consequent advantages in the storage and disposal thereof. (author)

Laboratory testing of waste glass aqueous corrosion; effects of experimental parameters

International Nuclear Information System (INIS)

Ebert, W.L.; Mazer, J.J.

1993-01-01

A literature survey has been performed to assess the effects of the temperature, glass surface area/leachate volume ratio, leachant composition, leachant flow rate, and glass composition (actual radioactive vs. simulated glass) used in laboratory tests on the measured glass reaction rate. The effects of these parameters must be accounted for in mechanistic models used to project glass durability over long times. Test parameters can also be utilized to highlight particular processes in laboratory tests. Waste glass corrosion results as water diffusion, ion-exchange, and hydrolysis reactions occur simultaneously to devitrify the glass and release soluble glass components into solution. The rates of these processes are interrelated by the affects of the solution chemistry and glass alteration phases on each process, and the dominant (fastest) process may change as the reaction progresses. Transport of components from the release sites into solution may also affect the observed corrosion rate. The reaction temperature will affect the rate of each process, while other parameters will affect the solution chemistry and which processes are observed during the test. The early stages of corrosion will be observed under test conditions which maintain dilute leachates and the later stages will be observed under conditions that generate more concentrated leachate solutions. Typically, water diffusion and ion-exchange reactions dominate the observed glass corrosion in dilute solutions while hydrolysis reactions dominant in more concentrated solutions. Which process(es) controls the long-term glass corrosion is not fully understood, and the long-term corrosion rate may be either transport- or reaction-limited

Aqueous radioactive waste bituminization

International Nuclear Information System (INIS)

Williamson, A.S.

1980-08-01

The bituminzation of decontamination and ion exchange resin stripping wastes with four grades of asphalt was investigated to determine the effects of asphalt type on the properties of the final products. All waste forms deformed readily under light loads indicating they would flow if not restrained. It was observed in all cases that product leaching rates increased as the hardness of the asphalt used to treat the waste increased. If bituminization is adopted for any Ontario Hydro aqueous radioactive wastes they should be treated with soft asphalt to obtain optimum leaching resistance and mechanical stability during interim storage should be provided by a corrosion resistant container

Corrosion in airframes

OpenAIRE

PETROVIC ZORAN C.

2016-01-01

The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

Corrosion engineering

Energy Technology Data Exchange (ETDEWEB)

Fontana, M.G.

1986-01-01

This book emphasizes the engineering approach to handling corrosion. It presents corrosion data by corrosives or environments rather than by materials. It discusses the corrosion engineering of noble metals, ''exotic'' metals, non-metallics, coatings, mechanical properties, and corrosion testing, as well as modern concepts. New sections have been added on fracture mechanics, laser alloying, nuclear waste isolation, solar energy, geothermal energy, and the Statue of Liberty. Special isocorrosion charts, developed by the author, are introduced as a quick way to look at candidates for a particular corrosive.

Radioactive waste storage: historical outlook and socio technical analysis

International Nuclear Information System (INIS)

Petit, J.C.

1993-07-01

The radioactive waste storage remains, in most of the industrialized concerned countries, one extremely debated question. This problem may, if an acceptable socially answer is not found, to create obstacles to the whole nuclear path. This study aim was to analyze the controversy in an historical outlook. The large technological plans have always economical, political, sociological, , psychological and so on aspects, that the experts may be inclined to neglect. ''Escape of radioactivity is unlikely, as long as surveillance of the waste is maintained, that is, as long as someone is present to check for leaks or corrosion or malfunctioning of and to take action, if any of these occur. 444 refs., 32 figs

Achievments of corrosion science and corrosion protection technology

International Nuclear Information System (INIS)

Fontana, M.; Stehjl, R.

1985-01-01

Problems of corrosion-mechanical strength of metals, effect of corrosive media on creep characteristics are presented. New concepts of the mechanism of corrosion cracking and its relation to hydrogen embrittlement are described. Kinetics and mechanism of hydrogen embrittlement effect on the process of corrosion cracking of different steels and alloys are considered. The dependence of such types of failure on various structural factors is shown. Data on corrosion cracking of high-strength aluminium and titanium alloys, mechanism of the processes and protective methods are given

Selection of Corrosion Resistant Materials for Nuclear Waste Repositories

International Nuclear Information System (INIS)

R.B. Rebak

2006-01-01

Several countries are considering geological repositories to dispose of nuclear waste. The environment of most of the currently considered repositories will be reducing in nature, except for the repository in the US, which is going to be oxidizing. For the reducing repositories, alloys such as carbon steel, stainless steels and titanium are being evaluated. For the repository in the US, some of the most corrosion resistant commercially available alloys are being investigated. This paper presents a summary of the behavior of the different materials under consideration for the repositories and the current understanding of the degradation modes of the proposed alloys in ground water environments from the point of view of general corrosion, localized corrosion and environmentally assisted cracking

Corrosion behavior of 2205 duplex stainless steel.

Science.gov (United States)

Platt, J A; Guzman, A; Zuccari, A; Thornburg, D W; Rhodes, B F; Oshida, Y; Moore, B K

1997-07-01

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires.

KTA 625 alloy tube with excellent corrosion resistance and heat resistance

International Nuclear Information System (INIS)

Fujiwara, Kazuo; Kadonaga, Toshiki; Kikuma, Seiji.

1982-01-01

The problems when seamless tubes are produced by using nickel base 625 alloy (61Ni-22Cr-9Mo-Cb) which is known as a corrosion resistant and heat resistant alloyF were examined, and the confirmation experiment was carried out on its corrosion resistance and heat resistance. Various difficulties have been experienced in the tube making owing to the characteristics due to the chemical composition, but they were able to be solved by the repeated experiments. As for the characteristics of the product, the corrosion resistance was excellent particularly in the environment containing high temperature, high concentration chloride, and also the heat resistance was excellent in the wide temperature range from normal temperature to 1000 deg C. From these facts, the wide fields of application are expected for these alloy tubes, including the evaporation and concentration equipment for radioactive wastes in atomic energy field. Expecting the increase of demand hereafter, Kobe Steel Ltd. examined the problems when seamless tubes are produced from the 625 alloy by Ugine Sejournet process. The aptitude for tube production such as the chemical composition, production process and the product characteristics, the corrosion resistance against chloride, hydrogen sulfide, polythionic and other acids,F the high temperature strength and oxidation resistance are reported. (Kako, I.)

Method of processing radioactive wastes

International Nuclear Information System (INIS)

Katada, Katsuo.

1986-01-01

Purpose: To improve the management for radioactive wastes containers thereby decrease the amount of stored matters by arranging the radioactive wastes containers in the order of their radioactivity levels. Method: The radiation doses of radioactive wastes containers arranged in the storing area before volume-reducing treatment are previously measured by a dosemeter. Then, a classifying machine is actuated to hoist the containers in the order to their radiation levels and the containers are sent out passing through conveyor, surface contamination gage, weight measuring device and switcher to a volume-reducing processing machine. The volume-reduced products are packed each by several units to the storing containers. Thus, the storing containers after stored for a certain period of time can be transferred in an assembled state. (Kawakami, Y.)

Corrosion products in the primary circuits of PWRs

International Nuclear Information System (INIS)

Darras, R.

1983-01-01

The characteristics of PWR primary circuits are recalled, particularly the chemical specifications of the medium and the various materials used (austenitic steel, nickel alloys, cobalt-based alloys and zirconium alloys). The behaviour of these materials as regards general corrosion in nominal and transient conditions is then outlined briefly, special emphasis being laid on the effect of the determining parameters on the quantity of corrosion products formed. The release of the latter into the primary coolant is caused by two main processes: solubilization and erosion. Particular attention was given therefore to the laws governing the solubility of the oxides involved, especially as a function of temperature and pH. Erosion, or release in the form of solid particles, is relatively severe during transient events. As these corrosion products are then carried through all circuits, they cause deposits to form in favourable places on the walls as a result either of precipitation of soluble species or of sedimentation followed by consolidation of suspended particles. The presence of corrosion products in the primary circuits creates a particular impact since they become radioactive as they pass through the core and especially when they remain in it in the form of deposits; as a result, the products are capable of contaminating the entire system. Finally, although long-term reliability is obviously an essential condition for materials developed, attention must also be given to problems associated with a build-up of corrosion products in the cooling circuits and efforts made to minimize them. To that end, a number of precautions are recommended, and various remedies can be applied: selecting materials which are not readily activated, keeping structures clean, purifying fluids properly, restricting solubilization and precipitation, and perhaps, periodic decontamination. (author)

Research Opportunities in Corrosion Science for Long-Term Prediction of Materials Performance: A Report of the DOE Workshop on ''Corrosion Issues of Relevance to the Yucca Mountain Waste Repository''

International Nuclear Information System (INIS)

Payer, Joe H.; Scully, John R.

2003-01-01

The report summarizes the findings of a U.S. Department of Energy workshop on ''Corrosion Issues of Relevance to the Yucca Mountain Waste Repository''. The workshop was held on July 29-30, 2003 in Bethesda, MD, and was co-sponsored by the Office of Basic Energy Sciences and Office of Civilian Radioactive Waste Management. The workshop focus was corrosion science relevant to long-term prediction of materials performance in hostile environments, with special focus on relevance to the permanent disposal of nuclear waste at the Yucca Mountain Repository. The culmination of the workshop is this report that identifies both generic and Yucca Mountain Project-specific research opportunities in basic and applied topic areas. The research opportunities would be realized well after the U.S. Nuclear Regulatory Commission's initial construction-authorization licensing process. At the workshop, twenty-three invited scientists deliberated on basic and applied science opportunities in corrosion science relevant to long-term prediction of damage accumulation by corrosive processes that affect materials performance.

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

Combating corrosion in biomass and waste fired plant

Energy Technology Data Exchange (ETDEWEB)

Henderson, Pamela [Vattenfall AB, Stockholm (Sweden). Research and Development; Hjoernhede, Anders [Vattenfall AB, Gothenburg (Sweden). Power Consultant

2010-07-01

Many biomass- or waste-fired plants have problems with high temperature corrosion especially if the steam temperature is greater than 500 C. An increase in the combustion of waste fuels means that an increasing number of boilers have had problems. Therefore, there is great interest in reducing the costs associated with high temperature corrosion and at the same time there exists a desire to improve the electrical efficiency of a plant by the use of higher steam temperatures. Assuming that the fuel is well-mixed and that there is good combustion control, there are in addition a number of other measures which can be used to reduce superheater corrosion in biomass and waste fired plants, and these are described in this paper. These include the use of fuel additives, specifically sulphur-containing ones; design aspects like placing superheaters in less corrosive positions in a boiler, using tube shielding, a wider pitch between the tubes; operational considerations such as more controlled soot-blowing and the use of better materials. (orig.)

In-pile loop experiments in water chemistry and corrosion

International Nuclear Information System (INIS)

Kysela, J.; Jindrich, K.; Masarik, V.; Fric, Z.; Chotivka, V.; Hamerska, H.; Vsolak, R.; Erben, O.

1986-08-01

Methods and techniques used were as follows: (a) Method of polarizing resistance for remote monitoring of instantaneous rate of uniform corrosion. (b) Out-of-pile loop at the temperature 350 degC, pressure 19 MPa, circulation 20 kgs/h, testing time 1000 h. (c) High temperature electromagnetic filter with classical solenoid and ball matrix for high pressure filtration tests. (d) High pressure and high temperature in-pile water loop with coolant flow rate 10 000 kgs/h, neutron flux in active channel 7x10 13 n/cm 2 .s, 16 MPa, 330 degC. (e) Evaluation of experimental results by chemical and radiochemical analysis of coolant, corrosion products and corrosion layer on surface. The results of measurements carried out in loop facilities can be summarized into the following conclusions: (a) In-pile and out-of-pile loops are suitable means of investigating corrosion processes and mass transport in the nuclear power plant primary circuit. (b) In studying transport phenomena in the loop, it is necessary to consider the differences in geometry of the loop and the primary circuit, mainly the ratio of irradiated and non-irradiated surfaces and volumes. (c) In the experimental facility simulating the WWER-type nuclear power plant primary circuit, solid suspended particles of a chemical composition corresponding most frequently to magnetite or nickel ferrite, though with non-stoichiometric composition Me x 2+ Fe 3-x 3+ O 4 , were found. (d) Continuous filtration of water by means of an electromagnetic filter removing large particles of corrosion products leads to a decrease in radioactivity of the outer epitactic layer only. The effect of filtration on the inner topotactic layer is negligible

Removal of corrosion products of construction materials in heat carrier

International Nuclear Information System (INIS)

1975-01-01

A review of reported data has been made on the removal of structural material corrosion products into the heat-carrying agent of power reactors. The corrosion rate, and at the same time, removal of corrosion products into the heat-carrying agent (water) decreases with time. Thus, for example, the corrosion rate of carbon steel in boiling water at 250 deg C and O 2 concentration of 0.1 mg/1 after 3000 hr is 0.083 g/m 2 . day; after 9000 hr the corrosion rate has been reduced 2.5 times. Under static conditions the transfer rate of corrosion products into water has been smaller than in the stream and also depends on time. The corrosion rate of carbon steel under nuclear plant operating conditions is almost an order higher over that of steel Kh18N10T

Study on decontamination of radioactive ruthenium by steel wool in waste solution

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, S; Sakaki, T [Radia Industry Co. Ltd., Takasaki, Gunma (Japan)

1979-06-01

Tracer experiments were done in order to establish a decontamination process of /sup 106/Ru in radioactive waste solution by column method paying special attention on the solution of nitrato-nitrosyl complex of Ru which is often encountered as a low level radioactive solution. It turned out that metallic iron was the most effective decontaminating agent among the several tens of materials tested. The decontamination factor (DF) of /sup 106/Ru increased in proportion to the total surface area of iron and it sensitively depended on the oxidation state of the surface as revealed by the batchwise and columnwise tests. Iron samples with high corrosiveness gave a much larger DF than those with low corrosiveness. The decontamination process proceeded as iron was being oxidized via Fe(metal) ..-->.. Fe(II) ..-->.. Fe(III). As the results, the DF initially increased after initiating the passage of water through the column but it then decreased as the oxidation process became inactive. An excellent durability up to 10000 bed volumes was demonstrated by the column method at a high average DF of 150.

Evaluation of the reinforcing steel corrosion in concrete mixes that will be used for constructing mid activity disposal repositories

International Nuclear Information System (INIS)

Moreno, Manuel; Alvarez, Marta G.; Duffo, Gustavo S.

2000-01-01

This study presents an evaluation of the reinforcing steel bars (rebars) corrosion behavior embedded in high performance concrete's prepared with three different cement types (normal Portland, Sulfate resistant and with furnace slag). The results of the study will provide the basis to select the materials used for constructing the mid activity radioactive disposals containers. The effect of aggressive ions such as chlorides and sulfates, as well as concrete carbonation, on the rebar corrosion process is evaluated using concrete specimens containing rebar segments. The electrochemical parameters that characterize the rebar corrosion process (corrosion potential (E corr ), polarization resistance (Rp) and electrical resistivity of concrete (ρ)) where periodically monitored after a conditioning period of 100 days. The results show that under all exposure conditions evaluated the rebar segments in contact with the three concrete mixes achieve a passive state of corrosion. Due to the continuos curing process of concrete the values of ρ present an increasing trend within time, even in the specimens exposed to the immersed conditions. (author)

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

Corrosion behaviour of container materials for geological disposal of high-level waste. Joint annual progress report 1983

International Nuclear Information System (INIS)

1985-01-01

Within the framework of the Community R and D programme on management and storage of radioactive waste (shared-cost action), a research activity is aiming at the assessment of corrosion behaviour of potential container materials for geological disposal of vitrified high-level wastes. In this report, the results obtained during the year 1983 are described. Research performed at the Studiecentrum voor Kernenergie/Centre d'Etudes de l'Energie Nucleaire (SCK/CEN) at Mol (B), concerns the corrosion behaviour in clay environments. The behaviour in salt is tested by the Kernforschungszentrum (KfK) at Karlsruhe (D). Corrosion behaviour in granitic environments is being examined by the Commissariat a l'Energie Atomique (CEA) at Fontenay-aux-Roses (F) and the Atomic Energy Research Establishment (AERE) at Harwell (UK); the first is concentrating on corrosion-resistant materials and the latter on corrosion-allowance materials. Finally, the Centre National de la Recherche Scientifique (CNRS) at Vitry (F) is examining the formation and behaviour of passive layers on the metal alloys in the various environments

Canisters for spent-fuel disposal: Design measures against localized corrosion

International Nuclear Information System (INIS)

Werme, L.O.; Oversby, V.M.

2000-01-01

Common to all high-level-waste disposal concepts is the encapsulation of the waste into metal canisters. The purpose of this waste canister is to isolate the radioactive waste from contact with its surroundings for a desired time period. The design service life ranges from hundreds to thousands of years depending on the disposal concept. After the isolation has been breached, other barriers in the disposal system will delay and attenuate the radioactive releases to acceptable levels. In a deep geologic repository, the waste package will be exposed to chemical attack and, depending on the type of repository, to mechanical stresses. Each of these factors will by itself or in combination inevitably lead to loss of confinement some time in the future. In the design of the Swedish waste canister, the corrosion resistance is provided by an outer shell of pure copper while an insert supplies the mechanical strength cast nodular iron. The close fit between the insert and the copper results in very small tensile stresses in the copper over very limited areas once the repository has been saturated. Measurements of stress corrosion crack growth show that annealed copper cannot maintain sufficiently high stress intensity factors for cracks to grow. For annealed copper, the stress intensity factor was limited to 25 MPa·m 1/2 because of extensive plastic deformation. For cold-worked copper, no crack growth could be observed for stress intensity factors 1/2 . Through the choices of canister material, canister, and repository design, and considering the expected chemical conditions, the risks for localized corrosion can be lowered to an acceptable level, if not eliminated altogether, and the releases from prematurely failed canisters can be kept well within acceptable dose levels

Control of corrosion in an aqueous nuclear fuel storage basin

International Nuclear Information System (INIS)

Zimmerman, C.A.

1981-01-01

Observations made during thirty years of experience in operating a nuclear fuel storage basin, used for storing a wide variety of spent nuclear fuels underwater have identified several forms of corrosion such as galvanic, pitting and crevice attack. Examples of some of the forms of corrosion observed and their causes are discussed, along with the measures taken to mitigate the corrosive attack. The paper also describes the procedure used to reduce corrosion by: surveillance of design, selection of materials for application in the basin, and inspection of items in the storage basin

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 cracking

International Nuclear Information System (INIS)

Goel, V.S.