scholarly journals PHASE FORMATION PROCESSES IN STEEL – BENTONITE INTERFACE IN THE CONDITIONS OF RADIOACTIVE WASTE GEOLOGICAL REPOSITORY EVOLUTION

2019 ◽  
Vol 29 (1) ◽  
pp. 13-23
Author(s):  
B. Shabalin ◽  
◽  
O. Lavrynenko ◽  
S. Buhera ◽  
N. Mitsiuk
Keyword(s):  
Radioactive Waste ◽  
Phase Formation ◽  
Formation Processes ◽  
Geological Repository

Modeling of the Phase Formation Processes on the Steel Surface Contacting with Water Medium under Conditions of Deep Geological Repository

2021 ◽  
Vol 20 ◽  
pp. 60-72
Author(s):  
О. М. Lavrynenko ◽  
◽  
B. G. Shabalin ◽  
◽  
Keyword(s):  
Phase Composition ◽  
Phase Formation ◽  
Steel Surface ◽  
Spinel Ferrite ◽  
Corrosion Products ◽  
Chemical Mechanism ◽  
Formation Processes ◽  
Deep Geological Repository ◽  
Iron Oxyhydroxides ◽  
Geological Repository

The experimental modeling of the corrosive phase formation processes was performed under conditions approaching the initial and transitional stages of evolution of the deep geological repository (the hydrogen index of the medium lied in the range of 9–12 and a temperature was 50–70 °C). The specificity of the system of rotating disk electrode made it possible to determine the phase composition of corrosion products formed under oxidative conditions (the near surface layer, NSL) and, conditionally, reductive — on the steel surface (SL) covered by NSL, that significantly complicated the access of oxygen into the reaction area. It was determined that phase composition of the corrosion products at the pH0 values 9–11 was identical and it is regulated by the compensative action of cathodic half-reaction of oxygen reducing on the steel surface. Green Rust and magnetite or non-stoichiometric spinel ferrite characterized by coagulative type of the structure and spherical particle shape were determined as the main phases of SL. Iron oxyhydroxides — goethite and lepidocrocite were presented as the phases of NSL. Increase in the pH0 to 12 changes the chemical mechanism of the corrosion process and it leads to the formation of weak crystallized iron oxyhydroxide phases. It was proved the main phase formed under corrosion of steel at 50–70 °C was spinel ferrite. Its morphology is presented as the cubic shaped particles that evidences about condensingcrystallizing mechanism of their formation. Generally, the presence of Co2+ and Mn2+ cations does not influence on the phase formation process and the phase composition as well, whereas the iron oxyhydroxides with admixture of Mn2+ and Mn3+ oxygen compounds are dominant in the sediment compositions when they are formed in the presence of Mn7+.

scholarly journals Assessment of the climate changes evolution for the long-term safety of the radioactive waste repository in the Czech Republic

2019 ◽  
Vol 133 ◽  
pp. 02005
Author(s):  
Markéta Camfrlová
Keyword(s):  
Czech Republic ◽  
Radioactive Waste ◽  
Spent Nuclear Fuel ◽  
Global Climate ◽  
Deep Geological Repository ◽  
Climatic Effects ◽  
The Czech Republic ◽  
Area Of Interest ◽  
Geological Repository

Nuclear energy accounts for a significant part of the total energy production in the Czech Republic, which is currently facing a problem dealing with the high-level radioactive waste (HLW) and the spent nuclear fuel (SNF). Deep repository is the safest option for storage of HLW. Rock environment of the area must guarantee the stability of the deep geological repository for at least 100,000 years. The aim of the research is a long-term evaluation of the climatic changes of the hypothetical area of interest, which corresponds to the candidate sites for deep geological repository in the Czech Republic. The occurrences of endogenous and exogenous phenomena, which could affect site stability, were evaluated. Concerning exogenous processes, research focuses mainly on the assessment of climatic effects. The climate scenarios for the Central Europe were examined – global climate change, glaciation, and the depth of permafrost as well as CO2 increase.

Aspects of the phase-formation processes in highly dispersed BaTiO3-based materials

1991 ◽  
Vol 30 (12) ◽  
pp. 1005-1006
Author(s):  
V. I. Lapshin ◽  
E. L. Fokina ◽  
I. A. Kozlovskaya
Keyword(s):  
Phase Formation ◽  
Formation Processes ◽  
Highly Dispersed

Current Status of the Japanese Geological Repository Programme

2007 ◽  
Author(s):  
Kazumi Kitayama
Keyword(s):  
Decision Making ◽  
Project Management ◽  
Radioactive Waste ◽  
Waste Disposal ◽  
Safety Assessment ◽  
Current Status ◽  
Geological Disposal ◽  
Geological Repository ◽  
Deep Geological Disposal ◽  
Site Characterisation

The programme for disposal of radioactive waste in Japan is now moving ahead on a number of fronts. On the regulatory side, responsibility for TRU waste disposal has been assigned to NUMO and guidelines for the safety goals for disposal of LLW have been published. NUMO, as the implementer for the deep geological disposal programme, has been developing the special tools for project management that are needed as a result of the decision to adopt a volunteering approach to siting. NUMO is also building up the technical infrastructure for flexible tailoring of site characterisation, repository design and the associated safety assessment to the conditions found in any volunteer site. This work requires openness and transparency in decision-making but, as several sites may need to be investigated in parallel, particular emphasis is placed on operational practicality.

Development of Superfine Spherical Silica Grout as an Alternative Grouting Material for the Geological Disposal of Long-Lived Radioactive Waste

2010 ◽  
Author(s):  
Morimasa Naito ◽  
Hirokazu Kishi ◽  
Naomi Fukuoka ◽  
Tsutomu Yamada ◽  
Hideaki Ishida
Keyword(s):  
Radioactive Waste ◽  
Calcium Hydroxide ◽  
Cementitious Materials ◽  
Geological Disposal ◽  
Grouting Material ◽  
Spherical Silica ◽  
Geological Repository ◽  
Binder Ratio ◽  
Grouting Materials ◽  
Term Performance

As an alternative grouting material for the geological repository of long-lived radioactive waste, the “Superfine Spherical silica Grout” (SFSG) material is developed using a fine spherical silica and a fine calcium hydroxide. The developed SFSG material takes an advantage of its smaller particle size distribution (max. ∼1 micron or less) than those of the cementitious materials, and also provides a low alkaline environment so as to reduce unfavorable effects on the long-term performance of geological disposal system. The SFSG is a mixture of the “super fine silica powder”, the superfine calcium hydroxide and additives such as superplasticizer. Presently, the mixture being investigated for grouting materials is focused on water/binder ratio (W/B) of 1.2. Some preliminary laboratory experiments were carried out to characterize its fundamental properties from the viewpoint of practical use for geological disposal, which is required to be equivalent with the conventional cementitious materials in terms of penetrability, strength, pH performance and workability. From a series of experiments, it was concluded that SFSG is expected to become an alternative grouting material for a geological repository.

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