Spent fuel corrosion and the impact of iron corrosion – The effects of hydrogen generation and formation of iron corrosion products

ABSTRACTA ten-year-long laboratory experiment was recently started in order to study interactions between the groundwater, the bentonite, and the canister in the near-field of the planned Finnish repository for spent nuclear waste. The experimental set-up consists of a number of samples containing sodium MX-80 bentonite and cast iron cylinders placed in copper vessels. The bentonite stays in contact with an external solution, either distilled water or a 0.5 M NaCl solution, via metal sinters. The experiments are performed under anoxic conditions (N2 atmosphere) at ambient room temperature (∼30 °C). The experimental measurements focus mainly on the development of (1) the water chemistry, (2) the cast iron corrosion, and (3) the diffusion of corrosion products inside the bentonite, since these processes are the most likely ones to produce detectable changes during the ten-year-long programme.The first analyses, after 9 months, showed that the iron corrosion had started and that the corrosion products had migrated into the bentonite. The corrosion products could not be identified by XRD, which either meant that the material was amorphous or present in concentrations too low to be detectable. The analyses of the gas phase indicated the presence of hydrogen, which most probably was the result of the iron corrosion. The compositions of the external water and the porewater were determined with regard to the major species of interest. A closer evaluation of the results will not be given until more data are at hand.

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Modeling porosity loss in Fe0-based permeable reactive barriers with Faraday’s law

Scientific Reports ◽

10.1038/s41598-021-96599-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Huichen Yang ◽

Rui Hu ◽

Hans Ruppert ◽

Chicgoua Noubactep

Keyword(s):

Surface Passivation ◽

Corrosion Process ◽

Corrosion Products ◽

Permeable Reactive Barriers ◽

Iron Surface ◽

Iron Corrosion ◽

Corrosion Rates ◽

Faraday’S Law ◽

Reactive Barriers ◽

The Impact

AbstractSolid iron corrosion products (FeCPs), continuously generated from iron corrosion in Fe0-based permeable reactive barriers (PRB) at pH > 4.5, can lead to significant porosity loss and possibility of system’s failure. To avoid such failure and to estimate the long-term performance of PRBs, reliable models are required. In this study, a mathematical model is presented to describe the porosity change of a hypothetical Fe0-based PRB through-flowed by deionized water. The porosity loss is solely caused by iron corrosion process. The new model is based on Faraday’s Law and considers the iron surface passivation. Experimental results from literature were used to calibrate the parameters of the model. The derived iron corrosion rates (2.60 mmol/(kg day), 2.07 mmol/(kg day) and 1.77 mmol/(kg day)) are significantly larger than the corrosion rate used in previous modeling studies (0.4 mmol/(kg day)). This suggests that the previous models have underestimated the impact of in-situ generated FeCPs on the porosity loss. The model results show that the assumptions for the iron corrosion rates on basis of a first-order dependency on iron surface area are only valid when no iron surface passivation is considered. The simulations demonstrate that volume-expansion by Fe0 corrosion products alone can cause a great extent of porosity loss and suggests careful evaluation of the iron corrosion process in individual Fe0-based PRB.

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Uncertainty studies on hydrogen source term with MAAP5 code

Kerntechnik ◽

10.1515/kern-2019-0109 ◽

2021 ◽

Vol 86 (2) ◽

pp. 152-163

Author(s):

T.-C. Wang ◽

M. Lee

Keyword(s):

Hydrogen Production ◽

Nuclear Power ◽

Hydrogen Generation ◽

Pearson Correlation ◽

Latin Hypercube Sampling ◽

Severe Accident ◽

Model Parameters ◽

Power Company ◽

Sensitivity Studies ◽

The Impact

Abstract In the present study, a methodology is developed to quantify the uncertainties of special model parameters of the integral severe accident analysis code MAAP5. Here, the in-vessel hydrogen production during a core melt accident for Lungmen Nuclear Power Station of Taiwan Power Company, an advanced boiling water reactor, is analyzed. Sensitivity studies are performed to identify those parameters with an impact on the output parameter. For this, multiple calculations of MAAP5 are performed with input combinations generated from Latin Hypercube Sampling (LHS). The results are analyzed to determine the 95th percentile with 95% confidence level value of the amount of in-vessel hydrogen production. The calculations show that the default model options for IOXIDE and FGBYPA are recommended. The Pearson Correlation Coefficient (PCC) was used to determine the impact of model parameters on the target output parameters and showed that the three parameters TCLMAX, FCO, FOXBJ are highly influencing the in-vessel hydrogen generation. Suggestions of values of these three parameters are given.

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Sensitivity of the neutron multiplication factor to water ingress into a spent fuel cask

Kerntechnik ◽

10.1515/kern-2020-850107 ◽

2020 ◽

Vol 85 (1) ◽

pp. 38-53

Author(s):

M. J. Leotlela ◽

I. Petr ◽

A. Mathye

Keyword(s):

Gradual Increase ◽

Primary Objective ◽

Fuel Pellet ◽

Main Body ◽

Spent Fuel ◽

Reactivity Effect ◽

Water Ingress ◽

Accident Scenarios ◽

The Impact ◽

Gain Access

Abstract An essential component of safety analyses is the investigation of accident scenarios. In this paper water ingress scenarios of spent fuel containers, as they may occur during transport or storage, are examined. In the main body of this paper, a number of paths are studied through which water can gain access to the spent fuel cask and eventually reach the fuel pellet, potentially resulting in an increase in reactivity as a result of over-moderation. The primary objective of this project was to perform an assessment of what, in the unlikely event of a Fukushima- type accident, the impact would be on the reactivity of the cask by analyzing a gradual increase in water level in the spent fuel casks. In addition, the way the keff of the system responds to such an increase is discussed. The paper also provides the results of an assessment of the reactivity effect of water ingress via various pathways/channels.

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Spent UO2 TRISO coated particles – instant release fraction and microstructure evolution

Radiochimica Acta ◽

10.1515/ract-2014-2354 ◽

2015 ◽

Vol 103 (6) ◽

Cited By ~ 4

Author(s):

Hildegard Curtius ◽

Gabriele Kaiser ◽

Norman Lieck ◽

Murat Güngör ◽

Martina Klinkenberg ◽

...

Keyword(s):

Microstructure Evolution ◽

Spent Fuel ◽

Coated Particles ◽

The Impact ◽

Very High

AbstractThe impact of burn-up on the instant release fraction (IRF) from spent fuel was studied using very high burn-up UO

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Remedial Treatment of Corroded Iron Objects by EnvironmentalAeromonasIsolates

Applied and Environmental Microbiology ◽

10.1128/aem.02042-18 ◽

2018 ◽

Vol 85 (3) ◽

Cited By ~ 1

Author(s):

Wafa M. Kooli ◽

Thomas Junier ◽

Migun Shakya ◽

Mathilde Monachon ◽

Karen W. Davenport ◽

...

Keyword(s):

Iron Reduction ◽

Building Materials ◽

Solid Phase ◽

Corrosion Products ◽

Metal Corrosion ◽

Economic Losses ◽

Cytotoxic Activities ◽

Iron Corrosion ◽

Pathogenic Potential ◽

Wide Range

ABSTRACTUsing bacteria to transform reactive corrosion products into stable compounds represents an alternative to traditional methods employed in iron conservation. Two environmentalAeromonasstrains (CA23 and CU5) were used to transform ferric iron corrosion products (goethite and lepidocrocite) into stable ferrous iron-bearing minerals (vivianite and siderite). A genomic and transcriptomic approach was used to analyze the metabolic traits of these strains and to evaluate their pathogenic potential. Although genes involved in solid-phase iron reduction were identified, key genes present in other environmental iron-reducing species are missing from the genome of CU5. Several pathogenicity factors were identified in the genomes of both strains, but none of these was expressed under iron reduction conditions. Additionalin vivotests showed hemolytic and cytotoxic activities for strain CA23 but not for strain CU5. Both strains were easily inactivated using ethanol and heat. Nonetheless, given a lesser potential for a pathogenic lifestyle, CU5 is the most promising candidate for the development of a bio-based iron conservation method stabilizing iron corrosion. Based on all the results, a prototype treatment was established using archaeological items. On those, the conversion of reactive corrosion products and the formation of a homogenous layer of biogenic iron minerals were achieved. This study shows how naturally occurring microorganisms and their metabolic capabilities can be used to develop bio-inspired solutions to the problem of metal corrosion.IMPORTANCEMicrobiology can greatly help in the quest for a sustainable solution to the problem of iron corrosion, which causes important economic losses in a wide range of fields, including the protection of cultural heritage and building materials. Using bacteria to transform reactive and unstable corrosion products into more-stable compounds represents a promising approach. The overall aim of this study was to develop a method for the conservation and restoration of corroded iron items, starting from the isolation of iron-reducing bacteria from natural environments. This resulted in the identification of a suitable candidate (Aeromonassp. strain CU5) that mediates the formation of desirable minerals at the surfaces of the objects. This led to the proof of concept of an application method on real objects.

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Corrosive Environment Factors and their Influence on the Development of Weathering Steel Corrosion Products

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.832.137 ◽

2020 ◽

Vol 832 ◽

pp. 137-146

Author(s):

Monika Kubzová ◽

Vit Křivý ◽

Viktor Urban ◽

Katerina Kreislova

Keyword(s):

Atmospheric Corrosion ◽

Steel Surface ◽

Protective Layer ◽

Steel Structures ◽

Corrosion Products ◽

Outdoor Environment ◽

Weathering Steel ◽

Low Alloy Steels ◽

Time Of Wetness ◽

The Impact

This article deals with the topic of atmospheric corrosion. Atmospheric corrosion causes damage to nearly 80% of all existing steel structures. The main parameters of atmospheric corrosion are the time of wetness (TOW), air temperature and aggressive corrosive agents such as chlorides, sulfur dioxide and others. Currently, low alloy steels with improved atmospheric corrosion resistance called weathering steels are used for the steel structures located in outdoor environment. A protective layer of corrosion products is created on the steel surface and this layer can reduce continuation of corrosion of steel. The time of wetness together with the effect of aggressive corrosive agents are various for surfaces oriented vertically or horizontally. Experimental tests of atmospheric weathering steel were carried out to monitor the impact of location and position of surface on the different constructions. These tests allow monitoring the development of corrosion products in real exposures. The article presents a part of the research, which includes monitoring the development of the thickness of corrosion products with regard to the position on the structure. Research is developed to refine of prediction models with the aim of improving determination of corrosion losses during the service life of the structure. Second part of these experiments is dedicated to measuring the deposition rate of chlorides. Chlorides have a corrosive impact on the steel surface. Under normal conditions the chlorides does not create suitable environment for the development of a protective layer of corrosion products.

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Corrosion of High-Strength Steel Wires under Tensile Stress

Materials ◽

10.3390/ma13214790 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4790

Author(s):

Shanglin Lv ◽

Kefei Li ◽

Jie Chen ◽

Xiaobin Li

Keyword(s):

Tensile Stress ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Immersion Time ◽

High Strength ◽

Corrosion Cracking ◽

Corrosion Products ◽

Corrosive Solution ◽

Steel Wires ◽

The Impact

The stress corrosion cracking is the central issue for high-strength wires under high tensile stress used in civil engineering. This paper explores the resistance of stress corrosion cracking of three typical steel wires of high-strength carbon through a laboratory test, combining the actions of tensile stress and corrosive solution. Besides, the impact of tensile stress and immersion time are also investigated. During the tests, the wires were subject to electrochemical measurements of potentiodynamic polarization and electrochemical impedance spectroscopy, and the microstructure analysis was performed on the fractured cross sections. The obtained results show the following: the high-strength wire, conforming to GB/T 5224, has higher resistance to the combined actions of tensile stress and corrosive solution; tensile stress of 70% fracture strength and longer loading-immersion time make the film of corrosion products on steel surface unstable and weaken the corrosion resistance; the surface film consisted of the iron oxide film and the corrosion products film whose components are mainly iron thiocyanate and iron sulphide.

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Diffusion of Corrosion Products of Iron in Compacted Bentonite.

MRS Proceedings ◽

10.1557/proc-294-467 ◽

1992 ◽

Vol 294 ◽

Cited By ~ 2

Author(s):

K. Idemitsu ◽

H. Furuya ◽

Y. Inagaki

Keyword(s):

Carbon Steel ◽

Corrosion Product ◽

Hydrogen Generation ◽

Ferric Hydroxide ◽

Corrosion Products ◽

Ferrous Ion ◽

Silica Sand ◽

High Level Waste ◽

Buffer Material ◽

The Difference

ABSTRACTCarbon steel is one of the candidate overpack materials for high-level waste disposal. The corrosion rate of carbon steel is reduced by the presence of buffer materials such as bentonite and seems to be affected by the diffusion of corrosive materials and corrosion products through the buffer material.The apparent diffusivities of corrosion product of iron were measured in some bentonite specimens in contact with carbon steel. The apparent diffusivities of iron were also measured without carbon steel for comparison. The apparent diffusivities of corrosion product were on the order of 10−12 m2/s and showed a tendency to decrease with increasing density of the bentonite specimen. There was no significant effect of silica sand on the apparent diffusivities. The apparent diffusivities of iron in the system without carbon steel were in the range of 10−14 m2/s and showed a tendency to increase with increasing silica sand content. The difference of the diffusivities between corrosion product and iron without carbon steel seems to be due to the difference of diffusing species. The color of the corrosion product was dark-green during contact with bentonite specimens and became red on exposure to air in a few minutes. Gas bubbles were also observed in the corrosion product. This suggests hydrogen generation during corrosion of the carbon steel. Thus the diffusing species seems to be in a reduced state, probably ferrous ion. On the other hand, the diffusing species of iron without carbon steel was probably a ferric hydroxide complex that was negatively charged. This suggests that ferrous ion could diffuse in the surface water adsorbed on bentonite, while ferric complex was excluded.

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