Lifetimes of Titanium and Copper Containers for the Disposal of Used Nuclear Fuel

1991 ◽  
Vol 257 ◽  
Author(s):  
Lawrence H. Johnson ◽  
D.W. Shoesmith ◽  
B.M. Ikeda ◽  
F. King
Keyword(s):  
Nuclear Fuel ◽  
Bulk Solution ◽  
General Corrosion ◽  
Compacted Clay ◽  
Used Nuclear Fuel ◽  
Buffer Material ◽  
Using Data ◽  
Long Term Performance ◽  
Term Performance ◽  
Nuclear Fuel Waste

ABSTRACTTitanium and copper have been proposed as suitable container materials for disposal of nuclear fuel waste in plutonic rock of the Canadian Shield. Studies of the corrosion of these materials have led to the development of container failure models to predict long-term performance. Crevice corrosion and hydrogen-induced cracking of titanium have been identified as potential failure mechanisms, and these two processes have been studied in detail. Using data from these studies as well as a number of conservative assumptions, titanium container lifetimes of 1200 to 7000 a have been estimated. For copper, general corrosion has been studied in detail in bulk solution and in compacted clay-based buffer material. Results indicate that the copper corrosion rate is likely to be controlled by the rate of transport of copper species away from the container surface. An assessment of copper pitting data suggests that pitting is an extremely improbable failure mechanism. The copper container failure model predicts minimum container lifetimes of 30 000 a. The results demonstrate that long lifetime containment can be provided, should performance assessment studies indicate the need for such an option.

Demonstration of a System Performance Assessment Process

1990 ◽  
Vol 212 ◽  
Author(s):  
Kenneth W. Dormuth
Keyword(s):  
Performance Assessment ◽  
Nuclear Fuel ◽  
Research Area ◽  
Assessment Process ◽  
Conceptual Engineering ◽  
Disposal Facility ◽  
Long Term Performance ◽  
Term Performance ◽  
Nuclear Fuel Waste

ABSTRACTTo help evaluate the concept of nuclear fuel waste disposal in plutonic rock of the Canadian Shield, the long-term performance of a hypothetical disposal facility is being studied. This case study uses information from a Shield research area, laboratories, and conceptual engineering. It illustrates the use of performance assessment to derive constraints on the siting, construction, and operation of a disposal facility, and to demonstrate the feasibility of safe disposal of nuclear fuel waste.

scholarly journals A Practical and Adaptive Approach to Predicting Indoor CO2

2021 ◽  
Vol 11 (22) ◽  
pp. 10771
Author(s):  
Giacomo Segala ◽  
Roberto Doriguzzi-Corin ◽  
Claudio Peroni ◽  
Tommaso Gazzini ◽  
Domenico Siracusa
Keyword(s):  
Data Collection ◽  
Prediction Accuracy ◽  
Network Models ◽  
Window Size ◽  
Environmental Data ◽  
Neural Network Models ◽  
Using Data ◽  
Carbon Dioxide Co2 ◽  
Long Term Performance ◽  
Term Performance

COVID-19 has underlined the importance of monitoring indoor air quality (IAQ) to guarantee safe conditions in enclosed environments. Due to its strict correlation with human presence, carbon dioxide (CO2) represents one of the pollutants that most affects environmental health. Therefore, forecasting future indoor CO2 plays a central role in taking preventive measures to keep CO2 level as low as possible. Unlike other research that aims to maximize the prediction accuracy, typically using data collected over many days, in this work we propose a practical approach for predicting indoor CO2 using a limited window of recent environmental data (i.e., temperature; humidity; CO2 of, e.g., a room, office or shop) for training neural network models, without the need for any kind of model pre-training. After just a week of data collection, the error of predictions was around 15 parts per million (ppm), which should enable the system to regulate heating, ventilation and air conditioning (HVAC) systems accurately. After a month of data we reduced the error to about 10 ppm, thereby achieving a high prediction accuracy in a short time from the beginning of the data collection. Once the desired mobile window size is reached, the model can be continuously updated by sliding the window over time, in order to guarantee long-term performance.

Predicted Behavior of Technetium in a Geological Disposal Vault For Used Nuclear Fuel - Ramifications of a Recent Determination of the Enthalpy of Formation of TcO2(cr)

1995 ◽  
Vol 412 ◽  
Author(s):  
R. J. Lemire ◽  
D. J. Jobe
Keyword(s):  
Nuclear Fuel ◽  
Management Program ◽  
Heat Of Solution ◽  
Used Nuclear Fuel ◽  
A Value ◽  
Reducing Conditions ◽  
Congruent Dissolution ◽  
Nuclear Fuel Waste ◽  
The Enthalpy Of Formation

AbstractRecently, we reported a value of ΔH°(TcO2(cr)) = -(458 ± 6) kJ·mol-1based on heat of solution measurements. The implications of this value on the database used in the Canadian Nuclear Fuel Waste Management Program for the evaluation of the technetium released by congruent dissolution of used UO2 fuel have now been assessed.It is probable that the Tc(IV) oxides are more stable than previously predicted and, hence, they are less likely to be oxidized to TcO4(aq) under moderately reducing conditions. We have revised earlier calculations done to predict the solution concentrations of technetium species in a vault as a function of the oxidation conditions in model groundwaters.

Prediction of the Oxidative Dissolution Rates of Used Nuclear Fuel in a Geological Disposal Vault Due to the Alpha Radiolysis of Water

1994 ◽  
Vol 353 ◽  
Author(s):  
S. Sunder ◽  
D.W. Shoesmith ◽  
N.H. Miller
Keyword(s):  
Nuclear Fuel ◽  
Management Program ◽  
Oxidative Dissolution ◽  
Dissolution Rates ◽  
Used Nuclear Fuel ◽  
A Value ◽  
Thin Layer Cell ◽  
Alpha Radiolysis ◽  
Nuclear Fuel Waste ◽  
Electrochemical Model

AbstractEffects of alpha radiolysis of water on the corrosion of nuclear fuel (UO2) have been investigated in solutions at pH = 9.5, i.e., a value close to that expected in groundwaters at the depth of the disposal vault proposed in the Canadian nuclear fuel waste management program, CNFWMP. The corrosion potentials of UO2 electrodes exposed to the products of alpha radiolysis of water were monitored as a function of alpha flux and exposure time in a specially designed thin-layer cell. The oxidative dissolution rates of UO2 are calculated from the steady-state values of the corrosion potential using an electrochemical model. A procedure to predict the dissolution rate of used nuclear fuel in groundwater as a function of fuel cooling time is described, and illustrated by calculating the dissolution rates for the reference used fuel in the CNFWMP (Bruce CANDU reactor fuel, burnup 685 GJ/kg U). It is shown that the oxidative dissolution of used fuel in the CNFWMP will be important only for time periods ≤ 600 a at this burnup and assuming no decrease in pH.

Creep behaviour of a buffer material for nuclear fuel waste vault

1985 ◽  
Vol 22 (4) ◽  
pp. 541-550 ◽  
Author(s):  
Raymond N. Yong ◽  
Prapote Boonsinsuk ◽  
Demos Yiotis
Keyword(s):  
Finite Element ◽  
Nuclear Fuel ◽  
Host Rock ◽  
Creep Behaviour ◽  
Creep Model ◽  
Secondary Creep ◽  
Full Size ◽  
Waste Container ◽  
Buffer Material ◽  
Nuclear Fuel Waste

In the Canadian nuclear fuel waste disposal concept currently under study, one of the prime candidate procedures is the borehole emplacement technique. Each fuel waste container will be placed in a 1.1 m diameter hole in the floor of a disposal vault in deep plutonic rock. The container will be surrounded by buffer material consisting of a mixture of clay and sand. This study examines the creep behaviour of the buffer material in the borehole during interaction with the waste container and the host rock. It simulated the buffer – container – host rock interaction through a small-scale physical model using the loading pressures anticipated in the full-size system. The results from the model tests were compared with those predicted by a finite element analytical model. The creep behaviour of the full-size system was then predicted using the analytical model.From the results, it is evident that the creep behaviour of the buffer material depends significantly on interaction within the container – buffer – host rock system, overburden pressure, and water uptake. At relatively low overburden pressures, the waste container might settle, causing a separation between the buffer material and the container top. However, this could be alleviated by the swelling properties of the buffer material. The secondary creep rates are negligible, and creep in the buffer material is primarily governed by the primary creep stage. Key words: creep, model test, swelling soil, soil deformation, unsaturated soil, finite element analysis.

Compacted clay-industrial wastes blends: Long term performance under extreme freeze-thaw and wet-dry conditions

2017 ◽  
Vol 146 ◽  
pp. 404-410 ◽  
Author(s):  
Nilo Cesar Consoli ◽  
Koltermann da Silva ◽  
Scheuermann Filho ◽  
André Brum Rivoire
Keyword(s):  
Industrial Wastes ◽  
Compacted Clay ◽  
Freeze Thaw ◽  
Dry Conditions ◽  
Long Term Performance ◽  
Term Performance

An overview of microbial research related to high-level nuclear waste disposal with emphasis on the Canadian concept for the disposal of nuclear fuel waste

1996 ◽  
Vol 42 (4) ◽  
pp. 349-366 ◽  
Author(s):  
Simcha Stroes-Gascoyne ◽  
Julia M. West
Keyword(s):  
Nuclear Fuel ◽  
Nuclear Waste ◽  
Waste Disposal ◽  
Nuclear Waste Disposal ◽  
Gas Production ◽  
Compacted Clay ◽  
Radionuclide Migration ◽  
Microbially Influenced Corrosion ◽  
High Level ◽  
Nuclear Fuel Waste

Current research on the effects of microbiology on nuclear waste disposal, carried out in a number of countries, is summarized. Atomic Energy of Canada Limited has developed a concept for the permanent disposal of nuclear fuel waste in Canada. A program was initiated in 1991 to address and quantify the potential effects of microbial action on the integrity of the multibarrier system on which the disposal concept is based. This microbial program focuses on answering specific questions in areas such as the survival of bacteria under relevant radiation and desiccation conditions; growth and mobility of microbes in compacted clay buffer materials and the potential consequences for container corrosion and microbial gas production; the presence and activity of microbes in deep granitic groundwaters; and the effects of biofilms on radionuclide migration in the geosphere.Key words: nuclear waste disposal, radiation and desiccation effects, microbially influenced corrosion, radionuclide migration, gas production.

Application of electrochemical methods in the development of models for fuel dissolution and container corrosion under nuclear waste disposal conditions

1997 ◽  
Vol 75 (11) ◽  
pp. 1566-1584 ◽  
Author(s):  
D.W. Shoesmith ◽  
W.H. Hocking ◽  
B.M. Ikeda ◽  
F. King ◽  
J.J. Noël ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Anodic Dissolution ◽  
Nuclear Waste ◽  
Chloride Solutions ◽  
Long Term Stability ◽  
Waste Container ◽  
Transport Barriers ◽  
Long Term Performance ◽  
Term Performance

The permanent disposal of nuclear fuel wastes requires the development of models that can assess the performance of a disposal vault over long periods of time. Models to assess the long-term stability of the nuclear fuel (UO2) and the corrosion performance of the waste container (either copper or titanium) have been based on electrochemical principles. Here we review the chemical/electrochemical performance of fuel and the two candidate container materials, and describe some of the electrochemical studies undertaken either to develop the mechanistic understanding upon which these models are based or to measure the values of parameters required to evaluate long-term performance. These include the following: the anodic dissolution of UO2; the reduction of O2 on various specimens of UO2; the crevice corrosion of various titanium alloys; the impedance characteristics of passive films on Ti alloys; the anodic dissolution of copper in chloride solutions; the reduction of O2 on copper; the effect of various transport barriers on the corrosion of copper; and the prediction of the corrosion potential of copper in aerated chloride solutions. Keywords: uranium dioxide, copper, titanium, nuclear waste, oxygen.

Occurrence and identification of microorganisms in compacted clay-based buffer material designed for use in a nuclear fuel waste disposal vault

1997 ◽  
Vol 43 (12) ◽  
pp. 1133-1146 ◽  
Author(s):  
Simcha Stroes-Gascoyne ◽  
Shelley A. Haveman ◽  
Connie J. Hamon ◽  
Terri-Lynn Delaney ◽  
Karsten Pedersen ◽  
...  
Keyword(s):  
16S Rrna ◽  
Moisture Content ◽  
Nuclear Fuel ◽  
Dry Weight ◽  
Buffer Layers ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Buffer Material ◽  
Nuclear Fuel Waste

A full-scale nuclear fuel waste disposal container experiment was carried out 240 m below ground in an underground granitic rock research laboratory in Canada. An electric heater was surrounded by buffer material composed of sand and bentonite clay and provided heat equivalent to what is anticipated in a Canadian nuclear fuel waste repository. During the experiment, the heat caused a mass transport of water and moisture content gradients developed in the buffer ranging from 13% closest to the heater to 23% at the rock wall of the deposition hole. Upon decommissioning after 2.5 years, microorganisms could be cultured from all samples having a moisture content above 15% but not from samples with a moisture content below 15%. Heterotrophic aerobic and anaerobic bacteria were found in numbers ranging from 101to 106cells/g dry weight buffer. Approximately 102, or less, sulphate-reducing bacteria and methanogens per gram of dry weight buffer were also found. Identification of buffer population members was performed using Analytical Profile Index (API) strips for isolated bacteria and 16S rRNA gene sequencing for in situ samples. A total of 79 isolates from five buffer layers were identified with API strips as representing the beta, gamma and delta groups of Proteobacteria and Gram-positive bacteria. Sixty-seven 16S rRNA clones that were obtained from three buffer layers were classified into 21 clone groups representing alpha and gamma groups of Proteobacteria, Gram-positive bacteria, and a yeast. Approximately 20% of the population comprised Gram-positive bacteria. Members of the genera Amycolatopsis, Bacillus, and Nocardia predominated. Among Gram-negative bacteria, the genera Acinetobacter and Pseudomonas predominated. Analysis of lipid biomarker signatures and in situ leucine uptake demonstrated that the buffer population was viable. The results suggest that a nuclear fuel waste buffer will be populated by active microorganisms only if the moisture content is above a value where free water is available for active life.Key words: 16S rRNA, bacteria, bentonite, nuclear fuel waste, phospholipid fatty acids, water activity.

scholarly journals The Short- And Long-Term Performance Of Privatization Initial Public Offerings In Europe

2013 ◽  
Vol 29 (4) ◽  
pp. 1189
Author(s):  
Haykel Hamdi ◽  
Duc Khuong Nguyen ◽  
Hassan Obeid
Keyword(s):  
Initial Public Offerings ◽  
Abnormal Returns ◽  
Public Offerings ◽  
Market Index ◽  
Long Run ◽  
Short And Long Term ◽  
Using Data ◽  
Long Term Performance ◽  
Term Performance

This article investigates the return behaviorof privatization initial public offerings (PIPOs) in Europe over both theshort- and long-run horizons. Using data from a sample of 162 PIPOs over theperiod 1986-2008, we show that European PIPOs outperform, in terms ofrisk-adjusted abnormal returns, a benchmark market index and a portfoliocomposed of 162 European private IPOs, regardless of the horizon of analysis.Our results are important for both investors and policymakers with respect totheir investment and privatization decisions, and also allow a betterunderstanding of the financial performance behavior of the privatizedstate-owned enterprises.

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