Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F46356088%3A_____%2F09%3A%230001158" target="_blank" >RIV/46356088:_____/09:#0001158 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1115/ICEM2009-16340" target="_blank" >http://dx.doi.org/10.1115/ICEM2009-16340</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1115/ICEM2009-16340" target="_blank" >10.1115/ICEM2009-16340</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

Popis výsledku v původním jazyce

Groundwater data from the natural analogue site Ruprechtov have been evaluated with special emphasis on the uranium behaviour in the so-called uranium-rich clay/lignite horizon. In this horizon in-situ Eh-values in the range of -160 to -280 mV seem to bedetermined by the SO(4)(2-)/HS(-) couple. Under these conditions U(IV) is expected to be the preferential redox state in solution. However, on-site measurements in groundwater from the clay/lignite horizon show only a fraction of about 20 % occurring inthe reduced state U(IV). Thermodynamic calculations reveal that the high CO(2) partial pressure in the clay/lignite horizon can stabilise hexavalent uranium, which explains the occurrence of U(VI). The calculations also indicate that the low uranium concentrations in the range between 0.2 and 2.1 mu g/l are controlled by amorphous UO(2) and/or the U(IV) phosphate mineral ningyoite. This confirms the findings from previous work that the uranium (IV) mineral phases are long-term stable un

Název v anglickém jazyce

Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

Popis výsledku anglicky

Groundwater data from the natural analogue site Ruprechtov have been evaluated with special emphasis on the uranium behaviour in the so-called uranium-rich clay/lignite horizon. In this horizon in-situ Eh-values in the range of -160 to -280 mV seem to bedetermined by the SO(4)(2-)/HS(-) couple. Under these conditions U(IV) is expected to be the preferential redox state in solution. However, on-site measurements in groundwater from the clay/lignite horizon show only a fraction of about 20 % occurring inthe reduced state U(IV). Thermodynamic calculations reveal that the high CO(2) partial pressure in the clay/lignite horizon can stabilise hexavalent uranium, which explains the occurrence of U(VI). The calculations also indicate that the low uranium concentrations in the range between 0.2 and 2.1 mu g/l are controlled by amorphous UO(2) and/or the U(IV) phosphate mineral ningyoite. This confirms the findings from previous work that the uranium (IV) mineral phases are long-term stable un

Druh

D - Stať ve sborníku

CEP obor

DL - Jaderné odpady, radioaktivní znečištění a kontrola

OECD FORD obor

—

Projekt

<a href="/cs/project/1H-PK%2F25" target="_blank" >1H-PK/25: Výzkum bariér úložišť radioaktivních odpadů.</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2009

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management, Volume 2

ISBN

978-0-7918-4408-3

ISSN

—

e-ISSN

—

Počet stran výsledku

6

Strana od-do

839-844

Název nakladatele

ASME

Místo vydání

New York

Místo konání akce

Liverpool, UK

Datum konání akce

1. 1. 2009

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000291330400103