Biogenic safety of clay barrier materials for radioactive waste repository database

2020 ◽  
Author(s):  
Alexey Safonov ◽  
Nadezhda Popova ◽  
Elena Spirina ◽  
Elena Abramova ◽  
Nadezhda Philippova ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Microbial Population ◽  
General Concept ◽  
Composition Analysis ◽  
Spent Fuel ◽  
Barrier Materials ◽  
High Efficient ◽  
High Sorption ◽  
Clay Barrier ◽  
Clay Materials

<p>Clay minerals are widely used as materials for construction of engineered barriers for nuclear waste and spent fuel repositories all over the world due to perfect isolation properties and high sorption capacity. Unwanted microbiological processes that occur in geological repository can cause deterioration of clay barrier materials, which may significantly affect long-term safety of the repository. It is important to note that such unwanted processes could be caused both by native microbial population and bacteria brought in from outside during the construction of the repository.</p><p>This paper aims to develop a general concept that could be used to prove the risk of unwanted microbial processes’ occurrence in clay materials.  </p><p>Some features of mineral composition of clay materials, including the content of iron, sulphur, phosphorus, organic and mineral carbon, provide the basis for the concept. The ratios of free mono- and di-valent cations present in the solution (Na-K-Ca-Mg) are also taken into account. Another approach presumes microflora composition analysis by means of high-efficient 16S rRNA sequencing method. In addition, the results of several tests dedicated to microbial communities’ stimulation are discussed. These include tests on hydrogen or organic substance addition as electron donors with subsequent standard tests on metabolic activity evaluation, MTT test and respiration assessment of microbial population, which is represented by both planktonic cells and cells incorporated into biofilms. The developed concept was used to assess clay materials found in Russian Federation that could potentially be used to construct engineered safety barriers. These data formed the basis for the formation of a database of microbial safety of engineering barrier materials for radioactive waste storage.</p>

Stability of clay buffer systems in the conditions of deep geological disposal of radioactive waste in the presence of microorganisms

2021 ◽  
Author(s):  
Elena Abramova ◽  
Alexey Safonov ◽  
Grigoriy Artemyev ◽  
Nadezhda Popova ◽  
Kirill Boldyrev
Keyword(s):  
Radioactive Waste ◽  
Diffusion Coefficients ◽  
Disposal Site ◽  
Rrna Gene ◽  
Mountain Range ◽  
Thermophilic Microorganisms ◽  
Safety Barriers ◽  
Bentonite Clays ◽  
Clay Barrier ◽  
Clay Materials

<p>Clay minerals are the main promising materials for engineering safety barriers in the disposal of radioactive waste in geological formations. Clays have high chemical stability, good sorption properties, and low diffusion coefficients. Bentonite clays combine the most optimal properties - high swelling pressure, low diffusion coefficients. At the moment, there is no unified international concept of the clay barrier density and its composition. Also, the parameters of the influence of biogenic processes on the properties of clay materials have not been correctly determined. It is planned to use of bentonite barrier between the metal container and the external environment in the design of the supercontainer for the new disposal of radioactive waste in the Nizhnekanskiy gneiss massif.</p><p>Within the studies of microbiological processes in the Yeniseisky disposal site, big attention will be paid to clay barriers as sources of biogenic elements in the system and microflora and organic and inorganic carbon.</p><p>Special attention will be paid to thermophilic microorganisms characterized by high growth rates and high levels of metabolic processes, which, along with the extreme impact of radioactive waste (temperature, gas release) on a site in the mountain range, can lead to the destruction of safety barriers.</p><p>Based on the data of phylogenetic analysis of the 16S rRNA gene sequences in clay materials, which are planned to be used as a barrier material, bacteria of the fermentative type of metabolism, capable of forming biogenic gases and organic acids, sulfate-reducing microflora, and a wide variety of microorganisms of the iron cycle were found. We investigating the processes under conditions corresponding to both the internal and external conditions of the clay barrier. As a result of our studies, in model experiments, the effect of microflora activation by radiolysis products, carbon steel corrosion products, hydrogen, and carbon dioxide was found. A thermophilic microbiota was found in samples with bentonite clays of the Khakass and Dinosaur deposits cultivated at temperatures of 50, 70, 90° C. High content of aluminum and silicon amorphous oxide phases was found in the liquid phase after cultivation, and an increase in bioleaching was observed with increasing temperature. Screening of biocidal additives was performed to suppress microbial activity, primarily sulfate reduction. The most effective, thermally stable biocide with prolonged action was polyhexamethylguanidine at a concentration of 0.5 wt. %.</p>

scholarly journals Performance of Clay Materials Constituting to Safety Barriers in Radiation Hazardous Facilities

2020 ◽  
Vol 13 (4) ◽  
pp. 42-57
Author(s):  
K. V. Martynov ◽  
◽  
E. V. Zakharova ◽  
A. N. Dorofeev ◽  
A. A. Zubkov ◽  
...  
Keyword(s):  
Functional Properties ◽  
Field Tests ◽  
Barrier Materials ◽  
Safety Barriers ◽  
Clay Barriers ◽  
Clay Barrier ◽  
Clay Materials

The paper elaborates on the characteristics of clays and clay materials governing functional properties (performance) of clay barriers. It considers methods applied to identify these characteristics with relevant examples being provided Criteria were proposed to select the required and sufficient numerical values of these characteristics (requirements) considered appropriate for the barrier materials. The paper discusses operating and envisaged test installations designed for mock-up and field tests of clay barrier materials.

scholarly journals Use of Clay Materials in the Construction of Protective Barriers at Radiation Hazardous Facilities

2020 ◽  
Vol 12 (3) ◽  
pp. 39-53
Author(s):  
K. V. Martynov ◽  
◽  
E. V. Zakharova ◽  
A. N. Dorofeev ◽  
A. A. Zubkov ◽  
...  
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Raw Materials ◽  
Mineral Raw Materials ◽  
Barrier Materials ◽  
Colloidal Properties ◽  
Clay Barriers ◽  
Clay Barrier ◽  
Clay Materials

The article discusses the types of mineral raw materials that can be used to manufacture clay barrier materials. The paper evaluates the characteristics of materials governing the performance of clay barriers: grain size, mineral and chemical composition, physical, mechanical (in dry state) and colloidal properties, stability in the environment. It considers the methods used to identify these characteristics and provides relevant examples.

Microbiological research program in deep HRW repository «Yeniseisky»: plans and first results

2021 ◽  
Author(s):  
Alexey Safonov ◽  
Elena Abramova ◽  
Nadezhda Popova ◽  
Grigory Artemiev ◽  
Kirill Boldyrev
Keyword(s):  
Activation Energy ◽  
Carbon Steel ◽  
Radioactive Waste ◽  
Steel Corrosion ◽  
Granite Gneiss ◽  
Water Radiolysis ◽  
Near Surface ◽  
Barrier Materials ◽  
High Level ◽  
Clay Materials

<p>The concept of engineered geologic disposal has been developed for the safe long-term management of long-lived high-level radioactive waste (HRW) by many countries. Russian Federation evaluates the “Yeniseiskiy” Nizhnekansky granite-gneiss crystalline formation, in Krasnoyarsk region. To this date microbiological studies became an integral part of safety assessment in Russia like other countries.</p><p>A multi-barrier concept was used to create super-container (SC). SC contains a primary vitrified radioactive waste package, placed in the carbon steel casing, bentonite and aluminate concrete layers placed between the casing and inner IC surface. All selected barrier materials are potential areas for biogenic processes.</p><p>The talk presented a plan of experimental research of biogenic processes and first step results. Microbiological studies at the first stage are carried out in laboratory conditions, at the second stage they will be carried out under the conditions of URL and include:</p><p>- changes of host rock sorption and diffusion properties due to biofilms formation,</p><p>- assessment of the possibility biocolloidal particles formation and determination clay and ferruginous colloids stability during biogenic processes;</p><p>To date, the study of the phylogenetic and functional diversity of the microflora of the granite-gneiss massif, near-surface waters, and clay materials that will be used in disposal has been carried out. It has been established that microorganisms, isolated from samples, collected nearby the zone of the future repository are capable of participating in a number of undesirable processes, including steel corrosion acceleration, the formation of biogenic gases, and changes in the properties of clay materials. Our studies also show that microbial communities of clays are activated by hydrogen, which is a product of steel corrosion and water radiolysis. At the first stage, we found an increase in the corrosion of carbon steel in the presence of microorganisms sampled from the study area.</p><p>An acceleration of the corrosion rate of carbon steel (from 1.3 to 1.9 μm/year) was observed with an increase in temperature from 20 to 50<sup>0</sup>С, the calculated value of the activation energy was 22 kJ/mol * K. Based on the data obtained, a kinetic model of carbon steel corrosion in the presence of microorganisms was created, including both the inclusion of the activation energy and the inhibition of corrosion by the formed corrosion products.</p><p> </p>

STATE-OF-ART IN THE DEVELOPMENT AND USE OF CLAY MATERIALS AS ENGINEERED SAFETY BARRIERS AT RADIOACTIVE WASTE CONSERVATION AND DISPOSAL FACILITIES IN RUSSIA

2019 ◽  
Vol 9 (4) ◽  
pp. 71-84
Author(s):  
O. A. Ilina ◽  
◽  
V. V. Krupskaya ◽  
S. E. Vinokurov ◽  
S. N. Kalmykov ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Barriers ◽  
Clay Materials ◽  
State Of Art

scholarly journals SiLiF Neutron Counters to Monitor Nuclear Materials in the MICADO Project

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2630
Author(s):  
Luigi Cosentino ◽  
Quentin Ducasse ◽  
Martina Giuffrida ◽  
Sergio Lo Meo ◽  
Fabio Longhitano ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Detector Response ◽  
Nuclear Materials ◽  
Spent Fuel ◽  
Neutron Detectors ◽  
Intermediate Level Radioactive Waste ◽  
Eu Project ◽  
Interim Storage ◽  
Waste Drums

In the framework of the MICADO (Measurement and Instrumentation for Cleaning And Decommissioning Operations) European Union (EU) project, aimed at the full digitization of low- and intermediate-level radioactive waste management, a set of 32 solid state thermal neutron detectors named SiLiF has been built and characterized. MICADO encompasses a complete active and passive characterization of the radwaste drums with neutrons and gamma rays, followed by a longer-term monitoring phase. The SiLiF detectors are suitable for the monitoring of nuclear materials and can be used around radioactive waste drums possibly containing small quantities of actinides, as well as around spent fuel casks in interim storage or during transportation. Suitable polyethylene moderators can be exploited to better shape the detector response to the expected neutron spectrum, according to Monte Carlo simulations that were performed. These detectors were extensively tested with an AmBe neutron source, and the results show a quite uniform and reproducible behavior.

Migration Rates of Brine Inclusions in Single Crystals of Nacl

1981 ◽  
Vol 6 ◽  
Author(s):  
I-Ming Chou
Keyword(s):  
Radioactive Waste ◽  
Temperature Gradients ◽  
Spent Fuel ◽  
Ion Diffusion ◽  
Cold Side ◽  
Migration Rates ◽  
Permanent Storage ◽  
Salt Brine ◽  
Salt Deposits ◽  
High Level

Rock-salt deposits have been considered as a possible medium for the permanent storage of high-level radioactive wastes and spent fuel. Brine inclusions present in natural salt can migrate toward the waste if the temperature and the temperature gradients in the vicinity of the radioactive waste are large enough. This migration is due to the dissolution of salt at the hot side of the salt-brine interface, ion diffusion through the brine droplet, and the precipitation of salt at the cold side of the salt brine interface.

Engineered Components for Spent Fuel Radioactive Waste Isolation Systems—are They Technically Justified?

1981 ◽  
Vol 11 ◽  
Author(s):  
H. C. Burkholder
Keyword(s):  
United States ◽  
Radioactive Waste ◽  
Release Rate ◽  
The United States ◽  
Radioactive Waste Disposal ◽  
Radionuclide Transport ◽  
Spent Fuel ◽  
Isolation System ◽  
Waste Forms ◽  
Isolation Systems

In response to draft radioactive waste disposal standards, R&D programs have been initiated in the United States which are aimed at developing and ultimately using radionuclide transport-delaying (e.g., long-lived waste containers) and radionuclide transport-controlling (e.g., very low release rate waste forms) engineered components as part of the isolation system. Before these programs proceed significantly, it seems prudent to evaluate the technical justification for development and use of sophisticated engineered components in radioactive waste isolation.

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