Mobility of uranium in tertiary argillaceous sediments – a natural analogue study

Abstract

The aim of the Natural Analogue study at Ruprechtov site (CZ) is to investigate the potential mobility of uranium in tertiary argillaceous sediments under representative long-term conditions. Such sediments often build up the overburden of host rocks for deep geological waste repositories. The Ruprechtov site represents a tertiary basin with argillized volcano-detritic sediments, which is surrounded by granite and underlain by kaolin and granite. U-enrichment mainly occurs in distinct layers of limited thickness on top of the kaolin close to aquiferous horizons and the clay-lignite seams. After a general survey of the site a new set of drillings has been sunk in 2002 in order to investigate the hydraulic, geological and chemical conditions of the area, including detailed investigations of kaolin and granite.Based on actual results new conceptual models for geological evolution and uranium transport pathways at Ruprechtov site have been developed. There is now strong evidence that U-migration at the site is mainly determined by three different processes: a) diffusion through kaolin, b) advection via fault zones across the kaolin and c) advection through aquiferous layers at the interface kaolin/Tertiary. Uranium source is the so-called Erzgebirgs-(Krusné hory) granite, underlying the Tertiary and kaolin and outcropping at the margins of the Tertiary basin.

Aqueous system-level processes and prokaryote assemblages in the ferruginous and sulfate-rich bottom waters of a post-mining lake

“…This is consistent with ongoing meteoric water-rock interactions and rather limited evaporation effects (cf. Noseck et al, 2004;Pačes and Šmejkal, 2004;Dupalová et al, 2012). By applying the expression first proposed by Taylor et al (1984) to relate the δ 18 O values of dissolved SO 4 2and those of ambient waters, we deduced that the oxygen isotope effect ( 18 ε SO4-amb.…”

Confocal μ-XRF, μ-XAFS, and μ-XRD Studies of Sediment from a Nuclear Waste Disposal Natural Analogue Site and Fractured Granite Following a Radiotracer Migration Experiment

“…Both bulk samples and sediment thin sections collected from the Ruprechtov site [1] are investigated. Autoradiographic measurements of the samples allow identification and quantification of U hot spots (Noseck et al, 2004). Areas around spots in two different samples containing ~150 and up to 350 μg 238 U/g material are investigated.…”

27 Radiochemistry and radiopharmaceuticals

“…Thus the solution behaviour of uranyl cation colloids under alpha particle bombardment has been studied, 262 as has the effect of alpha radiolysis under reducing conditions 263 on both uranium and other spent fuel elements; 264 such conditions are anticipated inside steel storage drums. 265 The mobility of elements such as uranium in clay 266,267 and salt 268 as well as the movement of radionuclides of various types in fractured rocks 269 have all been the subjects of recent research.…”