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King F.,Integrity Corrosion Consulting | Kolar M.,LS Computing Ltd. | Keech P.G.,Nuclear Waste Management Organization of Canada
Corrosion Engineering Science and Technology | Year: 2014

Carbon steel is a candidate container material for the disposal of used fuel in a deep geological repository in sedimentary host rock in Canada. Prediction of the long term anaerobic corrosion behaviour of the container is important, not only because it partly determines the container lifetime but also because the products of the corrosion reaction, Fe(II) and H2, can impact the properties of the clay based sealing materials and host rock. A mechanistically based numerical model is described that predicts both the long term corrosion rate and the effects on the repository environment, including the periodic build-up and release of H2, the precipitation of Fe3O4within the bentonite buffer, and the alteration of montmorillonite to a non-swelling clay. The results of a reference simulation for a repository in shale host rock are described. © 2014 Institute of Materials, Minerals and Mining.


King F.,Integrity Corrosion Consulting | Lilja C.,Swedish Nuclear Fuel and Waste Management Company
Corrosion Engineering Science and Technology | Year: 2014

Copper canisters in a KBS-3-type underground repository will be subject to general corrosion and minor localised attack. The form of the localised corrosion will depend on the composition of the bentonite pore water in contact with the canister surface and, in particular, the pH and chloride, sulphate, and bicarbonate ion concentrations. The presence of a passive Cu2O/Cu(OH)2layer is a pre-requisite for film breakdown and pitting. Literature pitting data have been used to determine whether pitting is possible or whether the environmental conditions will favour active dissolution of the canister. It is concluded that the canister surface will corrode generally and will be subject to only minor localised corrosion in the form of surface roughening. © 2014 Institute of Materials, Minerals and Mining.


King F.,Integrity Corrosion Consulting | Kolar M.,LS Computing Ltd | Vahanen M.,Posiva Oy | Lilja C.,Swedish Nuclear Fuel and Waste Management Company
Corrosion Engineering Science and Technology | Year: 2011

The well known KBS-3 repository design involves the disposal of spent fuel in copper canisters in a deep geological repository sealed with clay based buffer and backfill materials. A onedimensional reactive transport model has been developed to predict the evolution of the general corrosion behaviour of the copper canisters by the initially trapped O2 and by sulphide ions. Various sources of sulphide are considered, including the microbial reduction of sulphate, the dissolution of pyrite impurities and the ground water itself. The model has been used to simulate the evolution of the canister corrosion behaviour for various scenarios, including both the Olkiluoto and Forsmark proposed repository locations, the vertical and horizontal KBS-3 design variants, increased ground water sulphide or chloride concentrations, different microbial scenarios, different rates of repository saturation, and with and without the dissolution of pyrite. Following a brief description of the model, the results of these and other simulations are described. © 2011 Institute of Materials, Minerals and Mining.


King F.,Integrity Corrosion Consulting | Lilja C.,Swedish Nuclear Fuel and Waste Management Company
Corrosion Engineering Science and Technology | Year: 2011

The Swedish Nuclear Fuel and Waste Management Company has developed a method for safely disposing spent nuclear fuel, which involves encapsulation of the waste in copper canisters and burying it deep in the stable crystalline rock of the Fenno-Scandian shield. The design life of the canisters in the so called KBS-3 design is in excess of 100 000 years. These long canister lifetimes are a consequence of a number of factors involving the properties of the material and the nature of the near field environment in the KBS-3 repository. One of these factors, namely the thermodynamic stability of copper in O2 free water in the absence of sulphide, has been questioned. This paper critically reviews the evidence for and against the claim that water oxidises copper, and discusses the implications for canister lifetimes even if the proposed mechanism is correct. Even though the evidence presented in support of the proposed mechanism is not compelling, the Swedish Nuclear Fuel and Waste Management Company is actively engaged in ongoing research and development on the topic. © 2011 Institute of Materials, Minerals and Mining.


Sherar B.W.A.,University of Western Ontario | Keech P.G.,University of Western Ontario | Qin Z.,University of Western Ontario | King F.,Integrity Corrosion Consulting | Shoesmith D.W.,University of Western Ontario
Corrosion | Year: 2010

Gas transmission pipeline corrosion commences when coatings disbond, exposing the steel to groundwater. When this occurs, a number of anaerobic and aerobic corrosion scenarios can be envisaged. The initial nominally anaerobic corrosion period has been investigated by applying a combination of electrochemical methods (i.e., corrosion potential, linear polarization resistance, and electrochemical impedance spectroscopy [EIS] measurements) and surface analytical techniques (scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Raman spectroscopy). An evolution in film properties was observed and attributed to the entry of adventitious oxygen into faults within the preformed film. This leads to an increase in overall corrosion and a change in properties of the film as detected by EIS and Raman analysis. This article describes the mechanism involved in this transition, and provides a basis for a more extensive study of the corrosion process encountered on switching between anaerobic and aerobic conditions. The overall goal of this study was to provide a mechanistic basis for the corrosion scenarios possible on gas transmission pipelines. © 2010, NACE International.


King F.,Integrity Corrosion Consulting | Padovani C.,Campus Management
Corrosion Engineering Science and Technology | Year: 2011

A review of the corrosion performance of selected canister materials for the disposal of high activity waste in the UK is presented. The canister materials considered are carbon steel, copper, stainless steels, titanium alloys and nickel alloys. The purpose of the review is to provide a high level overview of the technical and scientific issues relating to the use of each of these materials for the disposal of high level waste and spent nuclear fuel in the UK. The advantages and disadvantages of each material are described, as are limiting or 'critical' conditions for which the use of a given material is questionable or not recommended. © 2011 Institute of Materials, Minerals and Mining.


King F.,Integrity Corrosion Consulting | Lilja C.,Svensk Karnbranslehantering AB | Vahanen M.,Posiva Oy
Journal of Nuclear Materials | Year: 2013

Copper has been proposed as a canister material for the disposal of spent nuclear fuel in a deep geologic repository in a number of countries worldwide. Since it was first proposed for this purpose in 1978, a significant number of studies have been performed to assess the corrosion performance of copper under repository conditions. These studies are critically reviewed and the suitability of copper as a canister material for nuclear waste is re-assessed. Over the past 30-35 years there has been considerable progress in our understanding of the expected corrosion behaviour of copper canisters. Crucial to this progress has been the improvement in the understanding of the nature of the repository environment and how it will evolve over time. With this improved understanding, it has been possible to predict the evolution of the corrosion behaviour from the initial period of warm, aerobic conditions in the repository to the long-term phase of cool, anoxic conditions dominated by the presence of sulphide. An historical review of the treatment of the corrosion behaviour of copper canisters is presented, from the initial corrosion assessment in 1978, through a major review of the corrosion behaviour in 2001, through to the current level of understanding based on the results of on-going studies. Compared with the initial corrosion assessment, there has been considerable progress in the treatment of localised corrosion, stress corrosion cracking, and microbiologically influenced corrosion of the canisters. Progress in the mechanistic modelling of the evolution of the corrosion behaviour of the canister is also reviewed, as is the continuing debate about the thermodynamic stability of copper in pure water. The overall conclusion of this critical review is that copper is a suitable material for the disposal of spent nuclear fuel and offers the prospect of containment of the waste for an extended period of time.© 2013 Elsevier Ltd. All rights reserved.


King F.,Integrity Corrosion Consulting
Corrosion | Year: 2013

A wide range of alloys have been considered as candidate container materials for the storage and disposal of nuclear waste. The goal of the majority of national nuclear waste management programs is the ultimate disposal of the waste, although, depending upon the strategy being followed, disposal may come only after an extended period of storage. The management strategy depends on the nature of the waste, with intermediate level waste (ILW) generally being stored for a longer period before disposal than is the case for higher activity wastes, such as high-level waste (HLW) from reprocessing activities or spent fuel (SF). This review describes the corrosion issues associated with the storage and disposal of both ILW and HLW/SF. Various factors enter into the decision of which material to select for the container, of which the corrosion behavior in the expected service environment is only one. The corrosion behavior of the container material(s) is closely tied to the nature of the environment to which the containers will be exposed and how that environment changes with time. A general discussion of the corrosion behavior of the materials selected or proposed as container materials is provided, and the specific corrosion issues associated with each class of material highlighted. The classes of material considered for the storage and/or disposal of ILW and HLW/SF include copper, carbon steel and cast iron, stainless steels, titanium alloys, and nickel-based alloys. © 2013, NACE International.


King F.,Integrity Corrosion Consulting
JOM | Year: 2014

As for many aspects of the disposal of nuclear waste, the greatest challenge we have in the study of container materials is the prediction of the long-term performance over periods of tens to hundreds of thousands of years. Various methods have been used for predicting the lifetime of containers for the disposal of high-level waste or spent fuel in deep geological repositories. Both mechanical and corrosion-related failure mechanisms need to be considered, although until recently the interactions of mechanical and corrosion degradation modes have not been considered in detail. Failure from mechanical degradation modes has tended to be treated through suitable container design. In comparison, the inevitable loss of container integrity due to corrosion has been treated by developing specific corrosion models. The most important aspect, however, is to be able to justify the long-term predictions by demonstrating a mechanistic understanding of the various degradation modes. © 2014 The Minerals, Metals & Materials Society.


King F.,Integrity Corrosion Consulting
50th Annual Conference of the Australasian Corrosion Association 2010: Corrosion and Prevention 2010 | Year: 2010

The corrosion behaviour of a range of materials for the disposal of high-level waste and spent nuclear fuel is reviewed. The candidate container materials considered include: oxygen-free copper, carbon (or mild) steel, stainless steels, titanium alloys, and nickel-based alloys. The range of environmental conditions in various international repository designs and host rock formations is also briefly reviewed. Each class of material offers certain advantages and disadvantages for this purpose, which are also discussed. Ultimately, the choice of which material to use depends on the nature of the disposal environment, the required service life, the effect of the container material on other barriers, the robustness of the lifetime predictions, the flexibility in repository siting and design that the choice of material allows, the ease of fabrication and sealing of the container, and the level of experience from international programmes.

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