The EL Berrocal Project: Geological Characterisation and Radionuclide Migration Studies in a Fractured Granitic Environment

1994 ◽  
Vol 353 ◽  
Author(s):  
W. M. Miller ◽  
L. Pérez Villar ◽  
P. Gómez ◽  
M. Ivanovich ◽  
B. de la Cruz ◽  
...  
Keyword(s):  
Quartz Vein ◽  
Fractured Rock ◽  
Calcium Sulphate ◽  
Uranium Mine ◽  
Radionuclide Migration ◽  
Central Spain ◽  
Sulphide Minerals ◽  
Mineral Growth ◽  
Geological Repository ◽  
And Migration

AbstractEl Berrocal is an abandoned uranium mine in a mineralised quartz vein hosted by a Hercynian granite in central Spain. This mine is the focus of an international project to characterise and model natural elemental migration in a fractured-rock environment as an aid to understanding and predicting processes that may occur in a geological repository for radioactive wastes.Uranium in the mineralised quartz vein has been shown to have originated from the orthomagmatic uraninite in the granite with the elemental removal and migration occurring predominately by hydrothermal fluids. Mobilisation of uranium from the mineralised quartz vein and from granite adjacent to hydraulically-active fractures away from the vein occurred over the geologically-recent past and in the present-day. The most recent mobilisation is evidenced by dissolution features seen in SEM photomicrographs; mineral growth and sorption signatures identified by enhanced uranium concentrations on the surfaces of preexisting minerals; and measured disequilibrium in the uranium series for whole rock close to fracture walls.Present-day groundwaters in the studied area are young meteoric waters. They are generally calcium-sulphate enriched, oxidising and mildly acidic near the surface, becoming more bicarbonate-rich with near neutral pH in the deeper zones, except around the mineralised vein where the waters are acid (pH around 3) due to oxidisation of the sulphide minerals. No deep, chemically-reducing groundwaters have yet been identified in the El Berrocal boreholes.

Mineral deposits and chalcogen gases

1993 ◽  
Vol 57 (389) ◽  
pp. 599-606 ◽  
Author(s):  
Martin Hale
Keyword(s):  
Ore Deposits ◽  
Anomalous Dispersion ◽  
Mineral Deposits ◽  
Oxidation Reactions ◽  
Sulphide Minerals ◽  
Sulphide Ore ◽  
Dispersion Patterns ◽  
Sulphide Deposits ◽  
High Concentrations ◽  
And Migration

AbstractSulphide minerals and their analogues yield gases as a result of oxidation reactions. Even where sulphide minerals are in contact with mildly reducing groundwaters, S2- ions pass into solution and their dispersion patterns can be detected in soil as acid-released H2S. In more oxidising conditions, the metastable gases COS and CS2 are generated. Anomalous dispersion patterns of COS have been reported in soils above more than ten sulphide ore deposits, many of them concealed beneath transported exotic overburden. High concentrations of CS2 occur in the soils over several of the same deposits and uniquely reflect others. Anomalies of SO2 over sulphide deposits are confined to arid terrains. Certain anomalous dispersion patterns of arsenic and tellurium in soils are attributed to the generation and migration of unspecified gases from the oxidation of arsenide and telluride minerals.

Leaching and migration of Np, Pu, and Am from α-doped SON68 HLW glass in contact with dense clay

2006 ◽  
Vol 932 ◽  
Author(s):  
Elie Valcke ◽  
Mireille Gysemans ◽  
Hugo Moors ◽  
Pierre Van Iseghem ◽  
Nicole Godon ◽  
...  
Keyword(s):  
Glass Frit ◽  
High Density ◽  
Radionuclide Migration ◽  
Colloidal Transport ◽  
Boom Clay ◽  
Backfill Materials ◽  
Powdered Glass ◽  
And Migration ◽  
Radionuclide Leaching

ABSTRACTIn the frame of an integrated in situ test on the alteration of the SON68 reference glass in realistic disposal conditions, the leaching of Np, Pu, and Am from α-doped SON68 glass samples and their migration in three clay-based backfill materials at high density was measured. The addition of powdered glass frit to a Ca-bentonite decreased the glass alteration by two orders of magnitude, and resulted in a concomitant decrease of the radionuclide leaching in comparison with dried Boom Clay, which is the more agressive backfill. All actinides were selectively retained in the alteration layer, but the retention degree was lower for Np than for Pu and Am. All backfill materials proved to be efficient barriers against radionuclide migration. For nearly all radionuclides and backfill materials, the migration profile showed a contribution of colloidal transport.

Effect of colloids on radionuclide migration for performance assessment of HLW disposal in Japan

2001 ◽  
Vol 73 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
S. Kurosawa ◽  
S. Ueta
Keyword(s):  
Performance Assessment ◽  
Metal Ion ◽  
Fractured Rock ◽  
Experimental Studies ◽  
Radionuclide Migration ◽  
Metal Ion Hydrolysis ◽  
Engineered Barrier ◽  
Bentonite Colloid ◽  
Major Factors ◽  
High Level

Colloidal effect is one of the major factors to enhance the migration of radionuclides in groundwater. The experimental and theoretical studies of colloid mobility and colloid-facilitated radionuclide transport for the performance assessment of high-level radioactive waste (HLW) geological disposal is presented in this paper. The major aims of the study are (1) to study the filtration effect on colloids by the engineered barrier system, (2) to study bentonite colloid generation by erosion of the engineered barrier system, and (3) to calculate radionuclide migration with groundwater colloids through fractured rock systems. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Mechanisms of cesium sorption onto magnetite

2006 ◽  
Vol 94 (9-11) ◽  
Author(s):  
Noelia Granizo ◽  
T. Missana
Keyword(s):  
Sorption Isotherms ◽  
Radionuclide Migration ◽  
Trace Impurities ◽  
Linear Sorption ◽  
Geological Repository ◽  
Maximum Sorption ◽  
Precipitation Phenomena ◽  
Co Precipitation ◽  
High Level ◽  
Oxide Electrolyte

One of the current options for the final disposal of high level radioactive wastes is the deep geological repository (DGR). The metal canisters represent the first physical barrier to radionuclide migration towards the geosphere and their corrosion products may play a significant role in sequestering radionuclides by sorption and/or (co)precipitation phenomena.In this work, the sorption ofSorption was negligible up to pH 8.5 and maximum sorption values were reached around pH 12. A significant increase in Cs sorption was observed when decreasing the ionic strength. Linear sorption isotherms were observed within the range of Cs concentration used (up to 10As expected, Cs showed very small sorption onto the oxide, but the whole experimental results could be satisfactorily fit with a simple model. In addition, the model developed in the oxide-electrolyte system was able to reproduce fairly well the sorption of Cs onto magnetite in two more complex waters (synthetic bentonite and cement porewaters).All the possible effects on sorption that could increase the uncertainties on the (small) sorption values were analysed in depth. In addition, the possible influence of mineral trace impurities on the sorption (for example silicates from experimental vessels), already discussed in the literature, was avoided.

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