Effect of Thiosulfate on the SCC Behavior of Carbon Steel Welds Exposed to Concrete Pore Water Under Anoxic Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (19) ◽  
pp. 1019-1029 ◽  
Author(s):  
B. Kursten ◽  
S. Caes ◽  
R. Gaggiano
Keyword(s):  
Carbon Steel ◽  
Strain Rate ◽  
Pore Water ◽  
Water Solution ◽  
Weld Zone ◽  
Constant Strain Rate ◽  
Open Circuit ◽  
Spent Fuel ◽  
Anoxic Conditions ◽  
High Level

ABSTRACTThe Supercontainer (SC) is the reference concept for the post-conditioning of vitrified high-level nuclear waste and spent fuel in Belgium. It comprises a prefabricated concrete buffer that completely surrounds a carbon steel overpack. Welding is being considered as a final closure technique of the carbon steel overpack in order to ensure its water tightness. Welding is known to induce residual stresses near the weld zone, which may lead to an increased susceptibility to stress corrosion cracking (SCC). In this study, slow strain rate tests were conducted to study the SCC behavior of plain and welded P355 QL2 grade carbon steel exposed to an artificial concrete pore water solution that is representative of the SC concrete buffer environment. The tests were performed at 140°C, a constant strain rate of 5 × 10-7s-1and at open circuit potential under anoxic conditions. The effect of thiosulfate on the SCC behavior was investigated up to levels of 600 mg/L S2O32-.

scholarly journals Effect of Carbon Partitioning, Carbide Precipitation, and Grain Size on Brittle Fracture of Ultra-High-Strength, Low-Carbon Steel after Welding by a Quenching and Partitioning Process

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 747 ◽  
Author(s):  
Farnoosh Forouzan ◽  
M. Guitar ◽  
Esa Vuorinen ◽  
Frank Mücklich
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Weld Zone ◽  
Low Carbon Steel ◽  
High Strength ◽  
Precipitate Size ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
High Level ◽  
The Impact

To improve the weld zone properties of Advanced High Strength Steel (AHSS), quenching and partitioning (Q&P) has been used immediately after laser welding of a low-carbon steel. However, the mechanical properties can be affected for several reasons: (i) The carbon content and amount of retained austenite, bainite, and fresh martensite; (ii) Precipitate size and distribution; (iii) Grain size. In this work, carbon movements during the partitioning stage and prediction of Ti (C, N), and MoC precipitation at different partitioning temperatures have been simulated by using Thermocalc, Dictra, and TC-PRISMA. Verification and comparison of the experimental results were performed by optical microscopy, X-ray diffraction (XRD), Scanning Electron Microscop (SEM), and Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Scanning Diffraction (EBSD) analysis were used to investigate the effect of martensitic/bainitic packet size. Results show that the increase in the number density of small precipitates in the sample partitioned at 640 °C compensates for the increase in crystallographic packets size. The strength and ductility values are kept at a high level, but the impact toughness will decrease considerably.

Refined Modeling of Projectile Impact Onto Submerged Structure

2008 ◽  
Author(s):  
Justin Onisoru ◽  
Ovidiu Coman ◽  
Paul Wilson ◽  
George Thomas
Keyword(s):  
Strain Rate ◽  
Structural Integrity ◽  
Initial Conditions ◽  
Safety Issue ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Material Behavior ◽  
Spent Fuel ◽  
The Impact

Structural integrity of spent fuel racks is a critical safety issue in nuclear power stations. The standard approach of evaluating the effects of an impact projectile on a submerged structure, which constitute the start point of the current study, involves three main steps: determination of the conditions just prior to the impact (that are considered as initial conditions for the analysis), setting the mechanism of transferring energy from the projectile to the target structure, and determining how that energy is absorbed by the impacted structure. Usually, the dynamics of the projectile are ideally considered, the influence of the fluid presence is restricted to the determination of the impact velocity and strain rate dependency is limited to choosing a true stress vs. strain curve corresponding to some constant strain rate. Starting from the standard engineering approach, the authors have refined the model considering more realistic dynamics of the projectile, extending the influence of the fluid to the entire analysis and using a more accurate strain rate dependant material behavior. Explicit Finite Element analyses are used in order to incorporate the desired effects.

The Boom Clay geochemistry: Natural evidence

2006 ◽  
Vol 932 ◽  
Author(s):  
M. De Craen
Keyword(s):  
Pore Water ◽  
Point Of View ◽  
Water Sampling ◽  
Spent Fuel ◽  
Geochemical Composition ◽  
Boom Clay ◽  
Water Composition ◽  
Geological Processes ◽  
Long Time ◽  
High Level

ABSTRACTIn Belgium, the Boom Clay is studied as the reference formation for geological disposal of high-level radioactive waste and spent fuel. As the Boom Clay is considered as the main barrier for radionuclide migration/retention, a thorough characterisation of the clay and its pore water was done. This facilitates better understanding of the long-term geological processes and the distribution of the trace elements and radionuclides.From a mineralogical/geochemical point of view, the Boom Clay is considered as a rather homogeneous sediment, vertically as well as laterally. It is composed of detrital minerals, organic matter and fossils. Minerals are mainly clay minerals, quartz and feldspars. Minor amounts of pyrite and carbonates are also present. Small variations in mineralogical/geochemical composition are related to granulometrical variations. The radiochemical study indicates that the Boom Clay is in a state of secular radioactive equilibrium, meaning that the Boom Clay has not been disturbed for a very long time.Pore water sampling is done in situ from various piezometers, or by the squeezing or leaching of clay cores in the laboratory. These three pore water sampling techniques have been compared and evaluated. Boom Clay pore water is a NaHCO3 solution of 15 mM, containing 115 mg·1−1 of dissolved natural organic carbon. Some slight variations in pore water composition have been observed and can be explained by principles of chemical equilibrium.

Corrosion Behavior of Container Materials in Grande Ronde Basalt Groundwater

1986 ◽  
Vol 84 ◽  
Author(s):  
R. P. Anantatmula ◽  
R. L. Fish
Keyword(s):  
Carbon Steel ◽  
General Corrosion ◽  
Iron And Steel ◽  
Anoxic Conditions ◽  
Corrosion Rates ◽  
Speci Mens ◽  
Synthetic Groundwater ◽  
American Society ◽  
Average Size ◽  
High Level

AbstractThree candidate waste package container materials were tested for 5 mo at 200 °C in Hanford Site Grande Ronde Basalt groundwater (9.75 pH) under anoxic conditions (<0.1 mg/L dissolved oxygen in water). The materials were cast carbon steel (American Society for Testing and Materials (ASTM) A27), wrought carbon steel (American Iron and Steel Institute (AISI) 1020), cupro- nickel 90-10, and Fe9CrlMo steel. Testing was performed in 1-L titanium autoclaves at a pressure of 6.9 MPa and a flow rate of ∼O.02 mL/min. Anoxic conditions were achieved by constantly sparging the synthetic groundwater in the reservoir with argon. In addition, the groundwater was conditioned by placing a 2.54-cm layer of crushed basalt (∼O.635 cm average size) at the bottom of each autoclave. The average corrosion rates at 200 °C were 0.9 μm/yr for cupronickel 90-10 and Fe9CrlMo steel, 1.1 μm/yr for cast carbon steel, and 1.4 μm/yr for wrought carbon steel. Pitting was not detected in any of the specimens. Posttest analysis of the corrosion speci- mens indicated the formation of a thin film of iron smectite clay on the surface of all specimens. In addition, magnetite formation immediately adjacent to the specimen surface was observed in the iron-base alloys, consistent with previous investigations. Based on the present investiga- tions, all the materials exhibited significantly lower corrosion rates than were used in the Environmental Assessment (∼5 μm/yr) [1] for calculating acceptable container lifetimes. However, longer term general corrosion tests and tests to study the container materials susceptibility to other degradation modes are necessary prior to making a final evaluation of the suitability of these materials for use in fabricating high-level nuclear waste containers.

Geochemical Processes at the Carbon steel/bentonite Interface in Repository Conditions

2006 ◽  
Vol 985 ◽  
Author(s):  
Elena Torres ◽  
María Jesús Turrero ◽  
Pedro Luis Martin
Keyword(s):  
Carbon Steel ◽  
Exchange Capacity ◽  
Spent Fuel ◽  
Compacted Bentonite ◽  
Bentonite Buffer ◽  
Geological Repository ◽  
Geological Formation ◽  
Gaseous Corrosion ◽  
High Level

AbstractThe Deep Geological Repository (DGR) is currently the most accepted management option for the isolation of high level radioactive wastes. The DGR is based on a multibarrier system, which will limit releases of mobile radionuclides to the biosphere. In the design of the repository the spent fuel is encapsulated in canisters of carbon-steel. The space between the canister and the host geological formation will be filled with bentonite buffer clay. Under the prevailing conditions in a DGR, both localized and generalized corrosion phenomena are possible.Corrosion of the canister will result in formation of solid and gaseous corrosion products, which can influence the behaviour of both the canister and the bentonite. Many studies have been carried out in order to improve the knowledge on the reactivity of these barriers. Most of them have focused on the mineralogical alteration of the bentonite as a function of temperature, time, iron/clay and liquid/rock ratio in batch conditions. The aim of this study is to provide experimental evidences, at repository conditions, on chemical and mineralogical changes during the canister-compacted bentonite interaction: determination of secondary minerals and their alteration reactions, the advance of the corrosion front in the compacted bentonite, and changes in porosity, permeability and cation exchange capacity.

Effect of Strain Rate on Dynamic Recrystallization Behavior for V Micro-Alloy High-Carbon Steel

2012 ◽  
Vol 602-604 ◽  
pp. 401-404
Author(s):  
An Chao Ren ◽  
Yu Ji ◽  
Gui Feng Zhou ◽  
Ze Xi Yuan
Keyword(s):  
Carbon Steel ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
High Carbon Steel ◽  
Constant Strain Rate ◽  
Grain Morphology ◽  
Peak Stress ◽  
Compression Tests ◽  
High Carbon ◽  
Before And After

Isothermal constant strain rate compression tests on high-carbon steel are carried out under strain rate of 1s-1, 10s-1 and 50s-1 respectively and deformation of 0.7 using the THERMECMASTOR-Z thermal simulator at a temperature of 1000°C. The austenite grain morphology before and after deformation and the true stress-strain curves during the deformation process are analyzed. The experimental results show that increased strain rate can obviously contribute to the grain refinement, and when the strain rate is at low level (e.g. 1s-1)，increased strain rate can further help refine the grains. And under the same temperature conditions, as the deformation rate rises, peak stress will move toward the direction of strain increment，thus the dynamic recrystallization is not apt to occur.

Diffusion of Uranium in Compacted Bentonite in the Presence of Carbon Steel

1993 ◽  
Vol 333 ◽  
Author(s):  
K. Idemitsu ◽  
H. Furuya ◽  
Y. Tachi ◽  
Y. Inagaki
Keyword(s):  
Carbon Steel ◽  
Pore Water ◽  
Silica Sand ◽  
High Level Waste ◽  
Dry Density ◽  
Compacted Bentonite ◽  
Reducing Conditions ◽  
Order Of Magnitude ◽  
The Difference ◽  
High Level

ABSTRACTIn a high-level waste repository, a carbon steel overpack will be corroded by consuming oxygen trapped in the repository after closure. This will create a reducing environment in the vicinity of repository. Reducing conditions are expected to retard the migration of redox-sensitive radionuclides such as uranium.The apparent diffusivities of uranium were measured in compacted bentonite (Kunigel VI®, Japan) in contact with carbon steel under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusivities of uranium were 3.5 × 10-14 to 1.1 × 10-13 m2/s under reducing conditions and 9.0 × 10-13 to 1.4 × 10-12 m2/s under oxidizing conditions. There was no significant effect of dry density (1.6 to 1.8 g/cm3) and silica sand (0 or 40%) on the apparent diffusivities.Since the bentonite pore water would be buffered at a pH between 8 and 9, uranium in the bentonite pore water would probably exist as a neutral hydroxide complex under reducing conditions and as an anioníc carbonate or hydroxide complex under oxidizing conditions. The anion exclusion theory cannot explain the difference of diffusivities between the two conditions. The uranium concentrations in bentonite under oxidizing conditions were one order of magnitude higher than those under the reducing conditions. The uranium concentration in the bentonite pore water under the reducing condition is estimated to be two orders of magnitude lower than that under the oxidizing conditions under the assumption of diffusion in porous media.

Corrosion Considerations Related to Carbon Steel Radioactive Waste Packages Exposed to Cementitious Materials

MRS Advances ◽  
2016 ◽  
Vol 1 (63-64) ◽  
pp. 4193-4199 ◽  
Author(s):  
Bruno Kursten ◽  
Frank Druyts ◽  
Nick R. Smart ◽  
Digby D. Macdonald ◽  
Robert Gens
Keyword(s):  
Carbon Steel ◽  
Radioactive Waste ◽  
Cementitious Materials ◽  
Uniform Corrosion ◽  
Spent Fuel ◽  
Corrosion Rates ◽  
The Status ◽  
Corrosion Pitting ◽  
High Level ◽  
Passive Oxide Film

ABSTRACTThe Supercontainer is the reference concept for the post-conditioning of vitrified high-level radioactive waste and spent fuel in Belgium. It consists of a prefabricated concrete buffer that completely surrounds a carbon steel overpack. In this highly alkaline environment (pH ∼ 13.6) and under normal conditions (i.e. without the ingress of aggressive species), the carbon steel overpack will be protected by a passive oxide film, which is believed to result in very low uniform corrosion rates.This paper gives an overview of the status of the uniform corrosion, pitting corrosion and stress corrosion cracking behaviour of carbon steel expected during the waste disposal period.

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