Weathering Conditions and Behavior of Fission Products in Oklo Reactors

1997 ◽  
Vol 506 ◽  
Author(s):  
L. Pourcelot ◽  
F. Gauthier-Lafaye
Keyword(s):  
Fission Products ◽  
Fission Reactions ◽  
Clay Layer ◽  
Ore Deposit ◽  
Uranium Ore ◽  
Clay Matrix ◽  
High Concentrations ◽  
And Behavior ◽  
Fission Reactors

Two billion years ago, natural fission reactions occured in the uranium ore deposit of Oklo (Gabon), mainly due to the high concentrations of fissile 235U. At that time, high uranium contents (40-60 % U) allowed reaching criticality when oxidised uranium bearing fluids met reduced fluids accompanying the migration of hydrocarbons. Natural fission reactors consist of a core made of uraninite crystals embedded in a clay matrix (mainly chlorites). The thickness of the clay layer range between few centimetres to 2 meters. Fission products are mostly located in the uraninite grains but newly crystallised minerals such as phosphate minerals, clays and metallic aggregates retain some proportions of migrated fissiogenic elements [1].

Uraninites of the Oklo Reactors: O Isotopes and Mineralogical Data

1997 ◽  
Vol 506 ◽  
Author(s):  
L. Pourcelot ◽  
F. Gauthier-Lafaye
Keyword(s):  
Spent Nuclear Fuel ◽  
Fission Products ◽  
Ore Deposits ◽  
Unique Case ◽  
X Ray ◽  
Isotopic Analyses ◽  
O Isotopes ◽  
Clay Matrix ◽  
Oxygen Isotopic ◽  
Fission Reactors

Natural fission reactors located in the uranium ore deposits of Oklo-Okélobondo and Bangombé (Gabon) are a unique case of natural nuclear waste disposal. The Reactor Zones (RZ) (up to fifteen) cores are made of 60% uranium (UO2) embedded in a clay matrix [1]. The uraninites are depleted in 235U and contain fission products. Therefore, they are considered to be good analogues for spent nuclear fuel matrix [2]. The aim of this work is to study the conditions of preservation over a long periode of time of the uraninites which have been sumitted to interraction with fluid having different oxidizing potential. For this purposes mineralogical (X-ray powder diffraction), chemical (electron microprobe) and oxygen isotopic analyses were performed on uraninites from various RZs.

Radioactivity of spring and surface waters in the region of the uranium ore deposit at Žirovski vrh

1978 ◽  
Vol 44 (2) ◽  
pp. 307-315 ◽  
Author(s):  
I. Kobal ◽  
J. Kristan ◽  
M. Škofljanec ◽  
S. Jerančič ◽  
M. Ančik
Keyword(s):  
Surface Waters ◽  
Ore Deposit ◽  
Uranium Ore

scholarly journals A Review of In Situ Isotopic Studies of the Oklo and Bangombé Natural Fission Reactors Using Microbeam Analytical Techniques

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1060
Author(s):  
Hiroshi Hidaka
Keyword(s):  
Nuclear Reactions ◽  
Fission Products ◽  
Analytical Techniques ◽  
Laser Probe ◽  
The Past ◽  
Isotopic Analyses ◽  
Isotopic Studies ◽  
Reactor Materials ◽  
Fission Reactors

Isotopic analyses of elements in the natural reactor materials have often been performed to understand the distribution behaviors of the fission products and to evaluate the function of nuclear reactions since the first discovery of a natural reactor in 1972. Several types of unique microminerals, including significant amounts of fission products, have been found in and around the Oklo and the Bangombé natural reactors. In the past two decades, microbeam techniques using ion and laser probe facilities have been effectively applied for the in situ isotopic analyses of individual microminerals to investigate the migration behaviors of fissiogenic radioisotopes produced in the reactors. This paper presents a review of interpretations of the isotopic results of microminerals found in and around the natural reactors.

Mineralogical Study of Huashan Granite-Type Uranium Ore Deposit in Northeast of Guangxi

2012 ◽  
Vol 621 ◽  
pp. 17-22 ◽  
Author(s):  
Zhi Qiang Kang ◽  
Zuo Hai Feng ◽  
Yong Gao Huang ◽  
Hong Yi Chen ◽  
Wei Fu ◽  
...  
Keyword(s):  
Uranium Mineral ◽  
Ore Deposit ◽  
Granite Pluton ◽  
Uranium Ore ◽  
Mineralogical Characteristics ◽  
Granite Type ◽  
Mineralogical Study ◽  
Mineral Compositions ◽  
The Difference ◽  
Main Component

Huashan granite-type uranium ore deposit is originated within the Huashan granite pluton in northeast of Guangxi, the mineral (mineralization) occurrences already found include Changchong, Baishijiao and Caomiping. Previous studies are relatively weak, especially in mineralogical characteristics, in this paper, a detailed study of minerals has been carried out through EPMA and EDS, the results show that the uranium mineral compositions of the three mineral (mineralization) occurrences are significantly different, but all of them are of secondary uranium minerals, among them, the main component of Changchong mineral (mineralization) occurrence is (meta-) autunite, of Baijiaoshi mineral (mineralization) occurrence is kasolite, and of Caomiping mineral (mineralization) occurrence is torbernite and zeunerite, which reflect the difference of their minerals sources.

Ceramic Immobilization Options for Technetium

MRS Advances ◽  
2017 ◽  
Vol 2 (13) ◽  
pp. 753-758 ◽  
Author(s):  
Martin C. Stennett ◽  
Tae-Hyuk Lee ◽  
Daniel J. Bailey ◽  
Erik V. Johnstone ◽  
Jong Heo ◽  
...  
Keyword(s):  
Spent Nuclear Fuel ◽  
Thermo Gravimetric Analysis ◽  
Fission Products ◽  
High Mobility ◽  
Biologically Active ◽  
Purex Process ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Exchange Processes ◽  
High Concentrations

ABSTRACTLong half-life biologically active fission products, such as technetium-99, present particular problems for the disposal of spent nuclear fuel (SNF). Technetium is present in relatively high concentrations in fuel (approx. 1kg tonne-1 SNF) and has very high mobility in oxidizing environments. Technetium is therefore generally removed from SNF either by solvent extraction and reduction, during the PUREX process, or by sorption via ion exchange processes. Historically technetium has been disposed of via dilution and dispersion in the sea but stringent regulations now mean that the preferred long term option is immobilization in a highly stable and durable matrix. In this contribution we have looked at the synthesis of fluorite derivative crystalline host phases based on the zirconolite structure. Samples have been characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), thermo-gravimetric analysis (TG), and mass spectroscopy (MS). We have used Mo as an inactive surrogate for Tc.

Microorganisms Oxidize Iron (II) Ions in the Presence of High Concentrations of Sodium Chloride - Potentially Useful for Bioleaching

2017 ◽  
Vol 262 ◽  
pp. 364-367 ◽  
Author(s):  
Dieu Huynh ◽  
Stefan Kaschabek ◽  
Wolfgang Sand ◽  
Michael Schlömann
Keyword(s):  
Sodium Chloride ◽  
Ferrous Iron ◽  
High Salinity ◽  
Sea Water ◽  
Iron Oxidation ◽  
Ore Deposit ◽  
Enrichment Cultures ◽  
Spanish Coast ◽  
High Concentrations ◽  
Microbial Groups

Acidophilic leaching microorganisms have been reported to be in general intolerant to high salinity, namely high concentrations of chloride. At present this restriction hampers the use of sea water for bioleaching technology. Enrichment cultures obtained in this study from a former ore deposit near the Spanish coast oxidize ferrous iron in the presence of up to 50 gL-1 NaCl at pH 2.5 and 37°C. The presence of at least 5 gL-1 NaCl was shown to be an obligate requirement for iron oxidation. The major microbial groups comprise Alicyclobacillus and Arthrobacter. The findings may be of biotechnological relevance.

scholarly journals Uranium of dictyonema shale of Kajbolovo-Gostilitsky area of Baltic basin (Leningrad region)

2017 ◽  
pp. 25-30
Author(s):  
V. I. Vyalov ◽  
A. H. Bogomolov ◽  
V. A. Mihailov ◽  
E. V. Semenov
Keyword(s):  
Sedimentary Rock ◽  
Leningrad Region ◽  
Baltic Basin ◽  
Ore Genesis ◽  
Uranium Ore ◽  
Early Ordovician ◽  
Look Ahead ◽  
High Concentrations ◽  
Dictyonema Shale

The results of researches on uranium of Dictyonema shale of the Kajbolovo-Gostilitsky area of Baltic basin of shale and phosphorites (Leningrad region) are presented. Features uranium ore on the area and in sedimentary rock sequence of Pakerort horizon of early Ordovician Period are revealed. High concentrations of uranium in a layer of Dictyonema shale are determined, correlation of uranium with other elements are defined, probable conditions uranium ore genesis are described, look-ahead resources of uranium within the limits of the studied area are estimated.

239PU-238U DISEQUILIBRIUM STUDIES AT THE NOPAL I URANIUM ORE DEPOSIT, PEñA BLANCA, MEXICO

2016 ◽  
Author(s):  
Joanna S. Denton ◽  
◽  
Steven J. Goldstein ◽  
Andrew J. Nunn ◽  
Kimberly A. Hinrichs ◽  
...  
Keyword(s):  
Ore Deposit ◽  
Uranium Ore
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