Enrichment of Uranium inside Wood: a Natural Analog from a Sandstone-hosted Roll-type Uranium Ore Deposit

2004 ◽  
Vol 824 ◽  
Author(s):  
Huifang X ◽  
Maozhong Min ◽  
Jia Zhen ◽  
Xinjian Peng ◽  
Jinping Wang ◽  
...  
Keyword(s):  
Anaerobic Bacteria ◽  
Ore Deposit ◽  
Uranium Ore ◽  
Natural Analog ◽  
Geological Repository ◽  
Roll Type ◽  
Wooden Furniture ◽  
Carbonized Wood ◽  
Long Term Behavior

AbstractFurniture contaminated with uranium will be disposed of, together with U-bearing waste, in ageological repository such as the WIPP site in New Mexico. It is important to understand the effect of the wooden furniture on the migration of uranium in order to predict long-term behavior of uranium in a geological repository environment. In this paper, we present natural uraninite-bearing carbonized wood pieces from a sandstone-hosted roll-type uranium ore deposit in NW China. Results from SEM and TEM observations show that there are nanometer sized, and micron-sized, uraninite crystals that have accumulated on cell walls of the carbonized wood. Some uranitite crystrals display oval and round shapes that may be the result of microbial-induced reduction of uranium from groundwater. The wood carbonized fragments are the most uranium-rich “phase.” In some areas, aggregates of pyrite crystals occur withthe uraninite. It is proposed that organic components from the decay of the wood cells provide nutrientsfor the anaerobic bacteria to grow. The wood pieces with the bacteria inside may serve as scavengers of uranium because of the local reducing chemical environment.

Evaluation of the long-term behavior of potential plutonium waste forms in a geological repository

2014 ◽  
Vol 1665 ◽  
pp. 23-30 ◽  
Author(s):  
Guido Deissmann ◽  
Stefan Neumeier ◽  
Felix Brandt ◽  
Giuseppe Modolo ◽  
Dirk Bosbach
Keyword(s):  
Current Knowledge ◽  
Geological Disposal ◽  
Ceramic Waste ◽  
Corrosion Rates ◽  
Waste Forms ◽  
Safety Margins ◽  
Geological Repository ◽  
Closure Conditions ◽  
Long Term Behavior

ABSTRACTVarious candidate waste matrices such as nuclear waste glasses, ceramic waste forms and low-specification “storage” MOX have been considered within the current UK geological disposal program for the immobilization of separated civilian plutonium, in the case this material is declared as waste. A review and evaluation of the long-term performance of potential plutonium waste forms in a deep geological repository showed that (i) the current knowledge base on the behavior and durability of plutonium waste forms under post-closure conditions is relatively limited compared to HLW-glasses from reprocessing and spent nuclear fuels, and (ii) the relevant processes and factors that govern plutonium waste form corrosion, radionuclide release and total systems behavior in the repository environment are not yet fully understood in detail on a molecular level. Bounding values for the corrosion rates of potential plutonium waste forms under repository conditions were derived from available experimental data and analogue evidence, taking into account that the current UK disposal program is in a generic stage, i.e. no preferred host rock type or disposal concept has yet been selected. The derived expected corrosion rates for potential plutonium waste forms under conditions relevant for a UK geological disposal facility are in the range of 10-4 to 10-2 g m-2 d-1 and 10-5 to 10-4 g m-2 d-1 for borosilicate glasses, and generic ceramic waste forms, respectively, and ∼5·10-6 g m-2 d-1 for storage MOX. More realistic assessments of the long-term behavior of the waste forms under post-closure conditions would require additional systematic studies regarding the corrosion and leaching behavior under more realistic post-closure conditions, to explore the safety margins of the various potential waste forms and to build confidence in long-term safety assessments for geological disposal.

Long-term behavior of R7T7-type nuclear glass: Current state of knowledge and outlook

2004 ◽  
Vol 824 ◽  
Author(s):  
S. Gin ◽  
N. Godon ◽  
I. Ribet ◽  
P. Jollivet ◽  
Y. Minet ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Influential Factors ◽  
Future Research ◽  
Operational Model ◽  
Geological Repository ◽  
Glass Current ◽  
Interim Storage ◽  
Parameter Values ◽  
Long Term Behavior

AbstractThis article reviews current knowledge of the long-term behavior of R7T7-type glass during the thermal phase and in geological repository conditions (aqueous alteration). In interim storage R7T7 glass can be considered to conserve its integrity over time. In geological repository conditions, the mechanisms of glass alteration by water have been identified and parameter values have been assigned to the reaction kinetics for wide variations of the influential factors (temperature, pH, flow rate, S/V ratio, etc.). CEA has developed an operational model to obtain robust and reasonably conservative predictions of the glass quantities altered after disposal. Examples of applications of the operational model are discussed, future research topics are also proposed to consolidate this approach.

Use of Archaeological Glass to Predict the Long-Term Behavior of HLW

2009 ◽  
Vol 1193 ◽  
Author(s):  
S. Gin ◽  
A. Verney-Carron ◽  
G. Libourel
Keyword(s):  
Internal Crack ◽  
Secondary Phases ◽  
Crack Network ◽  
Geochemical Model ◽  
Kinetic And Thermodynamic Parameters ◽  
Geological Repository ◽  
Mediterranean Island ◽  
Leaching Experiments ◽  
Long Term Behavior

AbstractThe predictability of models describing long-term nuclear glass behavior in a geological repository can be tested by means of natural or archaeological analogs. This study covers fractured archaeological glass blocks from a shipwreck discovered near the Mediterranean island of Embiez (France). The blocks were examined mainly because of their morphological analogy with nuclear glasses. Fractured after production (as in the case of nuclear glass), these blocks had been leached for 1800 years in seawater. The laboratory investigation led to the development and subsequent validation on archaeological objects of a geochemical model capable of accurately simulating the coupling between chemistry and transport to account for the alteration state of the cracks according to their geometric characteristics. Laboratory experiments allowed us to determine the kinetic and thermodynamic parameters for modeling glass alteration. The model was then tested against short-term experiments before simulating the crack alteration over 1800 years. We show that cracks in the outer regions of the block are the most severely altered because of rapid solution renewal, whereas internal cracks are very slightly altered because of a rate-limiting effect of water transport due to the formation of secondary phases. This study also establishes a direct link between data obtained at lab scale and the long-term evolution of a complex system in a natural environment, indicating that the key phenomena have been identified experimentally. The analogous behavior of archaeological and nuclear glass during leaching experiments and the similarities in their crack networks allow us to consider applying the model to nuclear glasses under geological repository conditions. This study clearly shows that the internal crack network does not play a major role in the overall long-term alteration of archeological glass blocks. The issue of the transposition studies will be to determine whether this conclusion can be generalized to nuclear glasses.

Radionuclides containment in nuclear glasses: an overview

2017 ◽  
Vol 105 (11) ◽  
Author(s):  
Stephane Gin ◽  
Patrick Jollivet ◽  
Magaly Tribet ◽  
Sylvain Peuget ◽  
Sophie Schuller
Keyword(s):  
Current Knowledge ◽  
Special Focus ◽  
Geological Time ◽  
Water Contact ◽  
Glass Processing ◽  
Waste Vitrification ◽  
Geological Repository ◽  
Glass Matrices ◽  
Long Term Behavior

AbstractRadioactive waste vitrification has been carried out industrially in several countries for nearly 40 years. Research into the formulation and long term behavior of high and intermediate level waste glasses, mainly borosilicate compositions, is still continuing in order to (i) safely condition new types of wastes and (ii) design and demonstrate the safety of the disposal of these long-lived waste forms in a deep geological repository. This article presents a summary of current knowledge on the formulation, irradiation resistance and the chemical durability of these conditioning materials, with a special focus on the fate of radionuclides during glass processing and aging. It is shown that, apart from the situation for certain elements with very low incorporation rate in glass matrices, vitrification in borosilicate glass can enable waste loadings of up to ~20 wt% while maintaining the glass homogeneity for geological time scales and guaranteeing a high stability level in spite of irradiation and water contact.

Distribution of Enteric Viruses and Microorganisms in Long-Term Sewage-Treated Soil

1983 ◽  
Vol 15 (5) ◽  
pp. 129-135 ◽  
Author(s):  
Z Filip ◽  
K Seidel ◽  
H Dizer
Keyword(s):  
Soil Bacteria ◽  
Pathogenic Bacteria ◽  
Sewage Treatment ◽  
Anaerobic Bacteria ◽  
Enteric Viruses ◽  
Sewage Irrigation ◽  
Groundwater Samples ◽  
West Berlin ◽  
Aerobic Soil

To determine whether long-term sewage treatment can take place without a pollution risk for soil and groundwater, samples from sewage irrigation fields in West Berlin which have been in use since about 1890 were analyzed for enteric viruses and microorganisms. Enteric viruses were detected in only seven samples from a total number of eighty seven taken from different soil depths. With only one exception, no viruses were found below 60 cm. No viruses were detected in groundwater samples. Long-term sewage irrigation did not result in significant changes in the colony courts of aerobic soil bacteria, but the counts of anaerobic bacteria and actinomycetes were slightly elevated and those of microscopic fungi slightly decreased. Potentially pathogenic bacteria were not detected in soil below 90 cm.

Effects of acute seizures on cell proliferation, synaptic plasticity and long-term behavior in adult zebrafish

2021 ◽  
Vol 1756 ◽  
pp. 147334
Author(s):  
Charles Budaszewski Pinto ◽  
Natividade de Sá Couto-Pereira ◽  
Felipe Kawa Odorcyk ◽  
Kamila Cagliari Zenki ◽  
Carla Dalmaz ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Synaptic Plasticity ◽  
Adult Zebrafish ◽  
Acute Seizures ◽  
Long Term Behavior

Using Generalized Cell Mapping to Approximate Invariant Measures on Compact Manifolds

1997 ◽  
Vol 07 (11) ◽  
pp. 2487-2499 ◽  
Author(s):  
Rabbijah Guder ◽  
Edwin Kreuzer
Keyword(s):  
Dynamical Systems ◽  
Invariant Measures ◽  
Nonlinear Dynamical Systems ◽  
Powerful Method ◽  
Cell Mapping ◽  
Generalized Cell Mapping ◽  
Nonlinear Dynamical ◽  
Long Term Behavior ◽  
Mapping Theory

In order to predict the long term behavior of nonlinear dynamical systems the generalized cell mapping is an efficient and powerful method for numerical analysis. For this reason it is of interest to know under what circumstances dynamical quantities of the generalized cell mapping (like persistent groups, stationary densities, …) reflect the dynamics of the system (attractors, invariant measures, …). In this article we develop such connections between the generalized cell mapping theory and the theory of nonlinear dynamical systems. We prove that the generalized cell mapping is a discretization of the Frobenius–Perron operator. By applying the results obtained for the Frobenius–Perron operator to the generalized cell mapping we outline for some classes of transformations that the stationary densities of the generalized cell mapping converges to an invariant measure of the system. Furthermore, we discuss what kind of measures and attractors can be approximated by this method.

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