Evaluation of radionuclide migration in the homogeneous system of a geological repository

2005 ◽  
Vol 1 (4) ◽  
pp. 265 ◽  
Author(s):  
S. Prvakova ◽  
J. Duran ◽  
V. Necas
Keyword(s):  
Homogeneous System ◽  
Radionuclide Migration ◽  
Geological Repository

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.

scholarly journals Modeling radionuclide migration from activated metallic waste disposal in a generic geological repository in Lithuania

2020 ◽  
Vol 370 ◽  
pp. 110885
Author(s):  
Dalia Grigaliūnienė ◽  
Robertas Poškas ◽  
Raimondas Kilda ◽  
Hussam Jouhara ◽  
Povilas Poškas
Keyword(s):  
Waste Disposal ◽  
Radionuclide Migration ◽  
Geological Repository

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.

Modeling of Radionuclide Releases From the Geological Repository for RBMK-1500 Spent Nuclear Fuel in Crystalline Rocks in Lithuania

2007 ◽  
Author(s):  
Povilas Poskas ◽  
Asta Brazauskaite
Keyword(s):  
Nuclear Fuel ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Near Field ◽  
Crystalline Rocks ◽  
Far Field ◽  
Field Region ◽  
Radionuclide Migration ◽  
Channel Network ◽  
Geological Repository

During 2002–2005 the assessment of possibilities for disposal of spent nuclear fuel (SNF) in Lithuania was performed with support of Swedish experts. Potential geological formations for disposal of SNF were selected, disposal concept was developed, reference disposal site was defined and preliminary generic safety assessment was performed. Performing safety assessment the analysis of radionuclides migration from the repository as well as their impact to human and environment were also very important issues. In this paper results on the analysis of the radionuclide releases from the reference geological repository site for RBMK-1500 SNF in crystalline rocks in Lithuania are presented. For radionuclide migration in the near field region of the repository integrated finite difference method and the concept of compartments were used. For radionuclide migration in the far field the discrete channel network concept was used. The assessment of radionuclide migration in the near and far field region was performed using computer codes AMRER4.5 [1] and CHAN3D [2]. The results of analysis show that most of safety relevant radionuclides of RBMK-1500 SNF are effectively retarded in the near field region. The exposure due to possible release of the radionuclides from the crystalline rocks would be dominated by 129I firstly while after app. 250 thousand years 226Ra is dominating already.

Effects of Supersaturated Silicic Acid Concentration on Deposition Rate Around Geological Disposal System

2017 ◽  
Vol 3 (4) ◽  
Author(s):  
Tsuyoshi Sasagawa ◽  
Taiji Chida ◽  
Yuichi Niibori
Keyword(s):  
Deposition Rate ◽  
Silicic Acid ◽  
Dispersion Model ◽  
Cementitious Materials ◽  
Alkaline Condition ◽  
Radionuclide Migration ◽  
Flow Paths ◽  
Advection Dispersion ◽  
Geological Repository ◽  
The One

Cementitious materials for the construction of a geological repository of radioactive waste alter the pH of groundwater to a highly alkaline condition (pH ≈ 13). While this alkaline groundwater dissolves silicate minerals, the soluble silicic acid polymerizes or deposits on the surface of rock with the decrease in pH by mixing with the surrounding groundwater (pH = 8). In particular, the deposition of silicic acid leads to a clogging effect in flow-paths, which retards the migration of radionuclides. This study estimated the clogging of silicic acid in flow-paths with the one-dimensional advection–dispersion model considering the deposition rate constants evaluated in our previous study. As some of the most important parameters, these estimations focused on the initial supersaturated concentration of silicic acid and the density of deposited minerals. As a result, the aperture of flow-paths (initial width: 0.1 mm, flow-rate: 5 m/y, initial supersaturated concentration of silicic acid: 0.01, 0.1 and 1.0 mM) was almost clogged within about 200 y by the deposition of silicic acid. The period for the clogging became shorter under the conditions of higher initial supersaturated concentration and lower density of deposited minerals. In other words, the use of cementitious materials for constructing the repository might produce a retardation effect of radionuclide migration by the deposition/clogging processes of the supersaturated silicic acid.

EXPERIMENTAL AND SIMULATION INVESTIGATION OF RADIONUCLIDE MIGRATION IN FRACTURED GRANITE

2018 ◽  
Author(s):  
Funing Ma ◽  
◽  
Zhenxue Dai ◽  
Chaomei Wang ◽  
Mohamad Reza Soltanian
Keyword(s):  
Radionuclide Migration ◽  
Fractured Granite
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