scholarly journals Evaluation of Microbial Activity for Long-Term Performance Assessments of Deep Geologic Nuclear Waste Repositories

2005 ◽  
Vol 6 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Yifeng Wang ◽  
Arokiasamy J. Francis
Keyword(s):  
Microbial Activity ◽  
Nuclear Waste ◽  
Performance Assessments ◽  
Long Term Performance ◽  
Term Performance ◽  
Waste Repositories

Materials Research in Nuclear Waste Management: Reflections on Twenty-Five MRS Symposia

2002 ◽  
Vol 713 ◽  
Author(s):  
Rodney C. Ewing
Keyword(s):  
Waste Management ◽  
Nuclear Waste ◽  
Scientific Basis ◽  
Nuclear Waste Management ◽  
The Past ◽  
Materials Research ◽  
Long Term Performance ◽  
Term Performance ◽  
Selection Of

ABSTRACTThe MRS symposium, “Scientific Basis for Nuclear Waste Management” was first held in Boston, November 28th to December 1st, 1978. This symposium marks the twenty-fifth in a series that now rotate to meeting sites around the world. During the past 24 years, there has been considerable progress in the development and understanding of the behavior of materials that are used in the processing, transport, containment and disposal of radioactive waste. The design and selection of materials for long-term performance has required a uniquely interdisciplinary effort. Over the same period, there have been important developments in the regulatory framework that guides the scientific and engineering needs of nuclear waste management. This paper provides a subjective commentary on the major developments and innovations during the past 25 symposia. The future challenge will be the proper and constructive integration of the science into the development of nuclear waste disposal strategies.

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.

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.

Development of a reactive transport code MC-CEMENT ver. 2 and its verification using 15-year in situ concrete/clay interactions at the Tournemire URL

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 185-197 ◽  
Author(s):  
T. Yamaguchi ◽  
M. Kataoka ◽  
T. Sawaguchi ◽  
M. Mukai ◽  
S. Hoshino ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Chemical Properties ◽  
Bentonite Buffer ◽  
Alkaline Environments ◽  
Radioactive Waste Repositories ◽  
Long Term Performance ◽  
Term Performance ◽  
Waste Repositories

AbstractHighly alkaline environments induced by cement-based materials are likely to cause the physical and/or chemical properties of the bentonite buffer materials in radioactive waste repositories to deteriorate. Assessing long-term alteration of concrete/clay systems requires physicochemical models and a number of input parameters. In order to provide reliability in the assessment of the long-term performance of bentonite buffers under disposal conditions, it is necessary to develop and verify reactive transport codes for concrete/clay systems. In this study, a PHREEQC-based, reactive transport analysis code (MC-CEMENT ver. 2) was developed and was verified by comparing results of the calculations with in situ observations of the mineralogical evolution at the concrete/argillite interface. The calculation reproduced the observations such as the mineralogical changes in the argillite limited to within 1 cm in thickness from the interface, formation of CaCO3 and CSH, dissolution of quartz, decrease of porosity in the argillite and an increase in the concrete. These agreements indicate a possibility that models based on lab-scale (∼1 year) experiments can be applied to longer time scales although confidence in the models is necessary for much longer timescales. The fact that the calculations did not reproduce the dissolution of clays and the formation of gypsum indicates that there is still room for improvement in our model.

The Role of Metal Ion Solubility in Leaching of Nuclear Waste Glasses

1981 ◽  
Vol 11 ◽  
Author(s):  
B. Grambow
Keyword(s):  
Nuclear Waste ◽  
Metal Ion ◽  
Short Term ◽  
Long Term Performance ◽  
Term Performance ◽  
Kinetics Of ◽  
Elemental Release ◽  
Nuclear Waste Forms

The leachability of solid nuclear waste forms has been studied by many investigators to evaluate the short-term kinetics of elemental release or to determine the effects of leachant composition or other system parameters. Some general observations from these studies have included: incongruent leaching; formation of reaction layers that contain rare-earth, alkaline-earth, or transition metal elements; and apparent saturation of some elements in solution while others continue to be leached. Before these observations can be used to predict long-term performance of waste glasses under repository conditions, the mechanisms controlling the release of elements from the solid must be understood.

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