scholarly journals Applying laboratory methods for durability assessment of vitrified material to archaeological samples

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Lorena Nava-Farias ◽  
James J. Neeway ◽  
Michael J. Schweiger ◽  
José Marcial ◽  
Nathan L. Canfield ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Iron Age ◽  
Test Methods ◽  
Durability Test ◽  
Laboratory Methods ◽  
Near Surface ◽  
Glass Corrosion ◽  
Durability Assessment ◽  
Nuclear Waste Forms

AbstractLaboratory testing used to assess the long-term chemical durability of nuclear waste forms may not be applicable to disposal because the accelerated conditions may not represent disposal conditions. To address this, we examine the corrosion of vitrified archeological materials excavated from the near surface of a ~1500-year old Iron Age Swedish hillfort, Broborg, as an analog for the disposal of vitrified nuclear waste. We compare characterized site samples with corrosion characteristics generated by standard laboratory durability test methods including the product consistency test (PCT), the vapor hydration test (VHT), and the EPA Method 1313 test. Results show that the surficial layer of the Broborg samples resulting from VHT displays some similarities to the morphology of the surficial layer formed over longer timescales in the environment. This work provides improved understanding of long-term glass corrosion behavior in terms of the thickness, morphology, and chemistry of the surficial features that are formed.

About U(t) form of pH-dependence of glass corrosion rates at zero surface to volume ratio

2015 ◽  
Vol 1744 ◽  
pp. 153-161 ◽  
Author(s):  
Michael I. Ojovan ◽  
William E. Lee
Keyword(s):  
Nuclear Waste ◽  
Low Temperatures ◽  
Ph Dependence ◽  
Effective Diffusion ◽  
Volume Ratio ◽  
Surface Layers ◽  
Near Surface ◽  
Numerical Examples ◽  
Corrosion Rates ◽  
Glass Corrosion

ABSTRACTThe pH-dependence of glass corrosion rates has a well-known U-shaped form with minima for near-neutral solutions. This paper analyses the change of U-shaped form with time and reveals that the pH dependence evolves even for solutions that have pH not affected by glass corrosion mathematically corresponding to a zero surface to volume ratio. The U(t) dependence is due to changes of concentration profiles of elements in the near-surface layers of glasses in contact with water and is most evident within the initial stages of glass corrosion at relatively low temperatures. Numerical examples are given for the nuclear waste borosilicate glass K-26 which is experimentally characterised by an effective diffusion coefficient of caesium DCs = 4.5 10-12 cm2/day and by a rate of glass hydrolysis in non-saturated groundwater as high as rh = 100 nm/year The changes of U-shaped form need to be accounted when assessing the performance of glasses in contact with water solutions.

scholarly journals Facile incorporation of technetium into magnetite, magnesioferrite, and hematite by formation of ferrous nitrate in situ: precursors to iron oxide nuclear waste forms

2018 ◽  
Vol 47 (30) ◽  
pp. 10229-10239 ◽  
Author(s):  
Wayne W. Lukens ◽  
Sarah A. Saslow
Keyword(s):  
Iron Oxide ◽  
Fission Product ◽  
Nuclear Waste ◽  
Half Life ◽  
Fission Yield ◽  
Waste Forms ◽  
Nuclear Waste Forms

The fission product, 99Tc, presents significant challenges to the long-term disposal of nuclear waste due to its long half-life, high fission yield, and to the environmental mobility of pertechnetate (TcO4−), the stable Tc species in aerobic environments.

Natural Analogues: Their Application to the Prediction of the Long-Term Behavior of Nuclear Waste Forms

1986 ◽  
Vol 84 ◽  
Author(s):  
Rodney C. Ewing ◽  
Michael J. Jercinovic
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Large Scale ◽  
Laboratory Data ◽  
Waste Form ◽  
Long Time ◽  
Natural Analogues ◽  
Long Term Behavior ◽  
Nuclear Waste Forms

AbstractOne of the unique and scientifically most difficult aspects of nuclear waste isolation is the extrapolation ofshot-term laboratory data (hours to years) to the long time periods (103-105 years) required by regulatory agencies for performance assessment. The direct verification of these extrapolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the lay public that there is a demonstrable and reasonable basis for accepting the long-term extrapolations. Natural analogues of both the repository environment (e.g. radionuclide migration at Oklo) and nuclear waste form behavior (e.g. alteration of basaltic glasses and radiation damage in minerals) have been used to demonstrate the long-term behavior of large scale geologic systems and, on a smaller scale, waste form durability. This paper reviews the use of natural analogues to predict the long-term behavior of nuclear waste form glasses. Particular emphasis is placed on the inherent limitations of any conclusions that are based on “proof” by analogy. An example -- corrosion of borosilicate glass -- is discussed in detail with specific attention to the proper and successful use of natural analogues (basaltic glass) in understanding the long-term corrosion behavior of borosilicate glass.

Laboratory Testing of the Corrosion of Waste Glasses in Aqueous Environments - Effects of Experimental Parameters

1993 ◽  
Vol 333 ◽  
Author(s):  
AA. Barkatt ◽  
Jing C. Sang ◽  
S.-B. Xing ◽  
Yan Guo ◽  
I. L. Pegg ◽  
...  
Keyword(s):  
Test Methods ◽  
Waste Form ◽  
Test Duration ◽  
Leach Rate ◽  
Aqueous Environments ◽  
Experimental Parameters ◽  
Sensitive Function ◽  
Nuclear Waste Forms ◽  
Critical Aspects

ABSTRACTMany types of procedures have been developed for testing of the chemical durability of nuclear waste forms. These procedures differ from each other in critical aspects, such as duration, replenishment or non-replenishment of the leachates, and S/V ratio. As a result, different answers to basic questions, such as how waste-form leachability depends on its chemical composition, are obtained when different test methods are used. Furthermore, the possibility that some glasses may exhibit a leach rate excursion within the test period causes the composition dependence to be an even more sensitive function of test duration and of leachant replenishment. These factors also complicate the use of test data for the prediction of long-term waste form behavior.

Simulation of the Waste Glass Behavior in a Loamy Soil of the Wet Repository Site

2000 ◽  
Vol 663 ◽  
Author(s):  
M.I. Ojovan ◽  
N.V. Ojovan ◽  
I.V. Startceva ◽  
G.N. Chuikova ◽  
A.S. Barinov
Keyword(s):  
Borosilicate Glass ◽  
Field Data ◽  
Waste Glass ◽  
Loamy Soil ◽  
Model Calculations ◽  
Near Surface ◽  
Glass Corrosion ◽  
Radionuclide Release ◽  
Glass Behavior

ABSTRACTA model developed for description of waste glass corrosion has been applied to assess the radionuclide release from real radioactive (intermediate level) vitrified material over extended storage periods. Field data generated during the long-term testing of the prototype waste glass packages were mathematically processed and the derived parameters used in model calculations. Regardless of the corrosive saturated conditions of the wet near-surface repository, the fairly high safety of trench disposal has been demonstrated for borosilicate glass containing real NPP- operational waste.

On Alteration Rate Renewal Stage of Nuclear Waste Glass Corrosion

MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 111-120 ◽  
Author(s):  
Michael I. Ojovan
Keyword(s):  
Physical State ◽  
Leaching Rate ◽  
Surface Layers ◽  
Near Surface ◽  
High Sodium ◽  
Glass Corrosion ◽  
Initial Stage ◽  
Small Cracks ◽  
Physical Changes

Abstract:The three generically accepted stages of glass corrosion are reviewed with focus on final stage termed alteration rate renewal (or resumption) stage when the glass may re-start corroding with the rate similar to that at the initial stage. It is emphasized that physical state and physical changes that occur in the near-surface layers can readily lead to an effective increase of leaching rate which is similar to alteration rate renewals. Experimental data on long-term (during few decades) corrosion of radioactive borosilicate glass K26 designed to immobilize high-sodium operational NPP radioactive waste evidence on resumption-like effects of radionuclides (137,134Cs) leaching. The cause of that was however related not to chemical changes in the leaching environment but rather to physical state of glass surface due to formation of small cracks and new pristine glass areas in contact with water.

scholarly journals Durability Assessment of Clay-Bearing Soft Rocks By Using New Decay Index

2018 ◽  
Author(s):  
Mojtaba Heidari ◽  
Aliakbar Momeni ◽  
Yazdan Mohebbi
Keyword(s):  
Physical And Mechanical Properties ◽  
Test Methods ◽  
Index Test ◽  
Durability Test ◽  
Weak Rocks ◽  
Slake Durability ◽  
Decay Index ◽  
Durability Assessment ◽  
Engineering Projects ◽  
Slake Durability Test

Clay-bearing rocks are known as most important problematic weak rocks. Due to the importance of disintegration of clay-bearing rocks in engineering projects, several simple test methods have been proposed to assess durability of these rocks. In this study, a comprehensive research program was conducted on twenty different clay-bearing rocks to assess their disintegration characteristics under laboratory conditions. In order to carry out the research, at the first step some physical and mechanical properties of the studied rocks were measured. After that, three durability test methods were employed. These tests include the standard slake durability test to obtain index durability (Id2 ), slake durability test with sieving the remained materials in drum to obtain disintegration ratio (DR) and new time series slake durability test to obtain decay index (DI). The results of this research indicated that for most of samples, using the standardized slake durability index test (Id2 ) may not be adequate to understand the disintegration characteristics of clay-bearing rocks and shows overestimated values. The new decay index (DI) has overcome the most limitations of the standard slake durability test and clearly will realize deterioration potential of clay bearing rocks. Finally, based on the results of decay index a new durability classification was proposed.

A Flow Model for the Kinetics of Dissolution of Nuclear Waste Forms; A Comparison of Borosilicate Glass, Synroc and High-Silica Glass

1981 ◽  
Vol 11 ◽  
Author(s):  
Pedro B. Macedo ◽  
Aaron Barkatt ◽  
Joseoph H. Simmons
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Flow Model ◽  
Release Rates ◽  
Waste Forms ◽  
High Silica ◽  
Kinetics Of Dissolution ◽  
Kinetics Of ◽  
Nuclear Waste Forms

A model has been developed to predict the long-term leach or release rates of various waste-form materials under repository conditions.

The Long-Term Performance of Nuclear Waste Forms: Natural Materials - Three Case Studies

1992 ◽  
Vol 294 ◽  
Author(s):  
Rodney C. Ewing
Keyword(s):  
Case Studies ◽  
Nuclear Waste ◽  
Experimental Results ◽  
Waste Form ◽  
Short Term ◽  
Waste Forms ◽  
Long Term Performance ◽  
Term Performance ◽  
Nuclear Waste Forms

ABSTRACTNatural materials may be used to advantage in the evaluation of the long-term performance of nuclear waste forms. Three case studies are presented: (I) radiation effects in ceramic waste forms; (II) corrosion products of U02 under oxic conditions; (III) corrosion rate of nuclear waste glasses. For each case, a natural phase which is structurally and chemically analogous to the waste form is identified and used to evaluate the long-term behavior of a nuclear waste form. Short-term experimental results are compared to the observations made of analogous natural phases. The three case studies illustrate that results may range between providing fundamental data needed for the long-term evaluation of a waste form to only providing qualitative data of limited use. Although in the most rigorous view the long-term behaviour of a phase cannot be predicted, the correspondence between short-term experimental results and observations made of natural phases provides confidence in the “predicted” behavior of the waste form. The strength of this approach rests with the degree to which a mechanistic understanding of the phenomenon is attained.

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