The Boom Clay geochemistry: Natural evidence

2006 ◽  
Vol 932 ◽  
Author(s):  
M. De Craen
Keyword(s):  
Pore Water ◽  
Point Of View ◽  
Water Sampling ◽  
Spent Fuel ◽  
Geochemical Composition ◽  
Boom Clay ◽  
Water Composition ◽  
Geological Processes ◽  
Long Time ◽  
High Level

ABSTRACTIn Belgium, the Boom Clay is studied as the reference formation for geological disposal of high-level radioactive waste and spent fuel. As the Boom Clay is considered as the main barrier for radionuclide migration/retention, a thorough characterisation of the clay and its pore water was done. This facilitates better understanding of the long-term geological processes and the distribution of the trace elements and radionuclides.From a mineralogical/geochemical point of view, the Boom Clay is considered as a rather homogeneous sediment, vertically as well as laterally. It is composed of detrital minerals, organic matter and fossils. Minerals are mainly clay minerals, quartz and feldspars. Minor amounts of pyrite and carbonates are also present. Small variations in mineralogical/geochemical composition are related to granulometrical variations. The radiochemical study indicates that the Boom Clay is in a state of secular radioactive equilibrium, meaning that the Boom Clay has not been disturbed for a very long time.Pore water sampling is done in situ from various piezometers, or by the squeezing or leaching of clay cores in the laboratory. These three pore water sampling techniques have been compared and evaluated. Boom Clay pore water is a NaHCO3 solution of 15 mM, containing 115 mg·1−1 of dissolved natural organic carbon. Some slight variations in pore water composition have been observed and can be explained by principles of chemical equilibrium.

Effect of Thiosulfate on the SCC Behavior of Carbon Steel Welds Exposed to Concrete Pore Water Under Anoxic Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (19) ◽  
pp. 1019-1029 ◽  
Author(s):  
B. Kursten ◽  
S. Caes ◽  
R. Gaggiano
Keyword(s):  
Carbon Steel ◽  
Strain Rate ◽  
Pore Water ◽  
Water Solution ◽  
Weld Zone ◽  
Constant Strain Rate ◽  
Open Circuit ◽  
Spent Fuel ◽  
Anoxic Conditions ◽  
High Level

ABSTRACTThe Supercontainer (SC) is the reference concept for the post-conditioning of vitrified high-level nuclear waste and spent fuel in Belgium. It comprises a prefabricated concrete buffer that completely surrounds a carbon steel overpack. Welding is being considered as a final closure technique of the carbon steel overpack in order to ensure its water tightness. Welding is known to induce residual stresses near the weld zone, which may lead to an increased susceptibility to stress corrosion cracking (SCC). In this study, slow strain rate tests were conducted to study the SCC behavior of plain and welded P355 QL2 grade carbon steel exposed to an artificial concrete pore water solution that is representative of the SC concrete buffer environment. The tests were performed at 140°C, a constant strain rate of 5 × 10-7s-1and at open circuit potential under anoxic conditions. The effect of thiosulfate on the SCC behavior was investigated up to levels of 600 mg/L S2O32-.

A Review of Corrosion Considerations of Container Materials Relevant to Underground Disposal of High-Level Radioactive Waste in Belgium

2006 ◽  
Vol 932 ◽  
Author(s):  
Bruno Kursten ◽  
Frank Druyts
Keyword(s):  
Radioactive Waste ◽  
Large Scale ◽  
General Corrosion ◽  
Spent Fuel ◽  
High Level Radioactive Waste ◽  
Boom Clay ◽  
Nuclear Site ◽  
In Situ Experiments ◽  
Underground Disposal ◽  
High Level

ABSTRACTThe underground formation that is currently being considered in Belgium for the permanent disposal of high-level radioactive waste and spent fuel is a 30-million-year-old argillaceous sediment (Boom Clay layer). This layer is located in the northeast of Belgium and extending under the Mol-Dessel nuclear site at a depth between 180 and 280 meter.Within the concept for geological disposal (multibarrier system), the metallic container is the primary engineered barrier. Its main goal is to contain the radioactive waste and to prevent the groundwater from coming into contact with the wasteform by acting as a tight barrier. The corrosion resistance of container materials is an important aspect in ensuring the tightness of the metallic container and therefore plays an important role in the safe disposal of HLW. The metallic container has to provide a high integrity, i.e. no through-the-wall corrosion should occur, at least for the duration of the thermal phase (500 years for vitrified HLW and 2000 years for spent fuel).An extensive corrosion evaluation programme, sponsored by the national authorities and the European Commission, was started in Belgium in the mid 1980's. The main objective was to evaluate the long-term corrosion performance of a broad range of candidate container materials. In addition, the influence of several parameters, such as temperature, oxygen content, groundwater composition (chloride, sulphate and thiosulphate), γ-radiation, … were investigated. The experimental approach consisted of in situ experiments (performed in the underground research facility, HADES), electrochemical experiments, immersion experiments and large scale demonstration tests (OPHELIE, PRACLAY). Degradation modes considered included general corrosion, localised corrosion (pitting) and stress corrosion cracking.This paper gives an overview of the more relevant experimental results, gathered over the past 25 years, of the Belgian programme in the field of container corrosion.

scholarly journals Системные и ситуационные детерминанты вовлеченности морского судового экипажа в трудовую деятельность

2020 ◽  
Author(s):  
A.S. Zaladina ◽  
I.K. Kuzmichev ◽  
R.Y. Vakulenko ◽  
V.N. Kostrov
Keyword(s):  
Working Conditions ◽  
Emotional State ◽  
Point Of View ◽  
Work Activity ◽  
Level Of Involvement ◽  
Psychological Point ◽  
Long Time ◽  
The Many ◽  
High Level ◽  
Stimulus Environment

В статье определены факторы, оказывающие существенное влияние на эффективность деятельности моряков, пребывающих на судне на протяжении длительного времени Рассмотрены условия труда моряков на судне, требующие волевых усилий, психологической готовности к ситуативному физическому, интеллектуальному и эмоциональному напряжению, сопровождающемуся периодами монотонии. Цель исследования заключалась в проверке гипотезы о том, что члены экипажа, отличающиеся высоким уровнем включенности в свою трудовую деятельность и ситуацию на судне в целом, менее подвержены влиянию обеднённой стимульной среды, провоцирующей развитие деривационных процессов.In this article the organizational and psychological factors that have a significant impact on the effectiveness of the work of seafarers staying on the ship for a long time are identifies. The conditions in which crew members live and work are examined from a psychological point of view. Among the many factors that can destructively affect for the psycho-emotional state, sensory, cognitive, emotional and social types of deprivation are considered in detail. The working conditions of seafarers on the ship, requiring volitional efforts, psychological readiness for situational physical, intellectual and emotional stress, accompanied by periods of monotony, are considered. The purpose of the study is to test the hypothesis that crewmembers who are distinguished by a high level of involvement in their work activity and the situation on the ship as a whole are less susceptible to the effect of a depleted stimulus environment that provokes the development of diversion processes.

Safety Assessment of Geological Disposal of High-Level Radioactive Waste in Boom Clay: Relation With the Radionuclide Inventory

2009 ◽  
Author(s):  
Pierre Van Iseghem ◽  
Jan Marivoet
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
High Level Waste ◽  
Spent Fuel ◽  
Geological Disposal ◽  
High Level Radioactive Waste ◽  
Boom Clay ◽  
High Level ◽  
Clay Formation ◽  
Parameter Values

This paper discusses the impact of the parameter values used for the transport of radionuclides from high-level radioactive waste to the far-field on the long-term safety of a proposed geological disposal in the Boom Clay formation in Belgium. The methodology of the Safety Assessment is explained, and the results of the Safety Assessment for vitrified high-level waste and spent fuel are presented. The radionuclides having the strongest impact on the dose-to-man for both HLW glass and spent fuel are 79Se, 129I, 126Sn, 36Cl, and 99Tc. Some of them are volatile during the vitrification process, other radionuclides are activation products, and for many of them there is no accurate information on their inventory in the waste form. The hypotheses in the selection of the main parameter values are further discussed, together with the status of the R&D on one of the main dose contributing radionuclides (79Se).

The Issue of Underground Depositing of High Radioactive Waste

2016 ◽  
Vol 722 ◽  
pp. 59-65
Author(s):  
Markéta Kočová ◽  
Zdeňka Říhová ◽  
Jan Zatloukal
Keyword(s):  
Radioactive Waste ◽  
Nuclear Power ◽  
Power Plants ◽  
High Level Waste ◽  
Spent Fuel ◽  
High Level Radioactive Waste ◽  
Medium Level ◽  
Long Time ◽  
High Level ◽  
Fuel Elements

Nowadays manipulation and depositing of high-level radioactive waste has become the most important issue, which needs to be solved. High-level radioactive waste consists mainly of spent fuel elements from nuclear power plants, which cannot be deposited for long time in surface repositories in the same way as it is possible in case of low and medium level radioactive waste. The most effective and safe solution in longer time horizon seems to be deep geological repository of high level waste. In this process of deposition, large amount of specific conditions needs to be taken into account while designing the whole underground complex, because the materials and structures must fulfil all necessary requirements. Then adequate safety will be ensured.

Coupling Time-Dependent Sorption Values of Degrading Concrete With a Radionuclide Migration Model

2009 ◽  
Author(s):  
Janez Perko ◽  
Dirk Mallants ◽  
Diederik Jacques ◽  
Lian Wang
Keyword(s):  
Pore Water ◽  
Safety Assessment ◽  
Time Dependency ◽  
Radionuclide Migration ◽  
Near Surface ◽  
Water Composition ◽  
Disposal Facility ◽  
Long Time ◽  
Concrete Degradation ◽  
Engineered Barriers

Safety assessment of radioactive waste disposal facilities is usually carried out by means of simplified models. Abstraction of the numerical model from the real physical environment is done in several steps. One of the most challenging issues in safety assessment concerns the long time scales involved and the evolution of engineered barriers over thousands of years. For some processes occurring in specific engineered barriers the uncertainties related to long time scales are addressed by implementing conservative assumptions in the radionuclide migration models. Other processes such as chemical concrete degradation, however, can be estimated for long time periods by the use of coupled geochemical transport models. For many near-surface disposal facilities, concrete is a very important engineered barrier because it is used in the construction of disposal modules or vaults, in production of high-integrity monoliths and their backfilling and for waste conditioning. Knowledge on the durability of such concrete components and its relation to radionuclide sorption is important for a defensible safety assessment. Chemical degradation typically occurs as the result of decalcification, dissolution and leaching of cement components and carbonation. These reactions induce a gradual change in the solid phase composition and the concrete pore-water composition, from “fresh” concrete porewater with a pH above 13 to a pH lower than 10 for “evolved” porewater associated with fully degraded concrete. The focus of this work is to analyse the behaviour of the disposal facility in terms of radionuclides sorption values depending on the geochemical evolution of engineered barriers. The time-dependency of the concrete mineralogy and porewater is coupled with sorption values that are characteristic for the four concrete degradation states: (i) State I with a pH larger than 12.5, controlled by the dissolution of alkali-oxides, (ii) State II with a pH at 12.5 controlled by the dissolution of portlandite, (iii) State III with a pH between 12.5 and 10 when all portlandite is dissolved and the pore water composition is determined by different cement phases including calcium-silicate hydrates (C-S-H phases), and (iv) State IV with a pH lower than 10 with calcite and aggregate minerals present. Above mentioned pH values are valid for a system with a temperature of 25°C. Sorption values are obtained from a literature review. The time-dependency of the sorption values Rd is implemented in a one-dimensional radionuclide migration model used for release calculations from the planned near-surface disposal facility at Dessel, Belgium. Calculated releases will be discussed for radionuclides typical of low- and intermediate level short-lived (LILW-SL) waste.

scholarly journals First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

2016 ◽  
Vol 95 (3) ◽  
pp. 315-335 ◽  
Author(s):  
Thilo Behrends ◽  
Iris van der Veen ◽  
Alwina Hoving ◽  
Jasper Griffioen
Keyword(s):  
The Netherlands ◽  
Pore Water ◽  
Solid Phase ◽  
Clay Material ◽  
Pore Waters ◽  
Calcium Carbonates ◽  
Boom Clay ◽  
Water Composition ◽  
Dilution Experiments ◽  
Chloride Concentrations

AbstractThe Rupel Clay member in the Netherlands largely corresponds to the Boom Formation in Belgium, and this marine, clay-rich deposit is a potential candidate to host radioactive waste disposal facilities. Prediction of the speciation of radionuclides in Rupel Clay pore water and their retardation by interactions with Rupel Clay components requires knowledge about the composition of Rupel Clay pore water, the inventory of reactive solids and understanding of interactions between Rupel Clay and pore water. Here, we studied Rupel Clay material which was obtained from cores collected in the province of Zeeland, the Netherlands, and from drilling cuttings retrieved from a drilling in the province of Limburg, the Netherlands. Pore water was obtained by mechanical squeezing of Rupel Clay material from Zeeland. Additionally, anaerobic dilution experiments were performed in which the clay material was suspended with demineralised water or a 0.1M NaHCO3solution. Solid-phase characterisation included determination of carbon, nitrogen and sulphur contents, measurement of cation exchange capacity (CEC) and sequential extraction of iron phases.In contrast to the pore water in Belgian Boom Clay, pore water collected from the location in Zeeland has a higher salinity, with chloride concentrations corresponding to 70–96% of those in seawater. The high chloride concentrations most likely result from the intrusion of ions from saline waters above the Rupel Clay in Zeeland. Cation exchange during salinisation might account for the observed deficit of marine cations (Na, K, Mg) and excess of Ca concentrations, in comparison with seawater. The measured CEC values at both locations in the Netherlands vary between 7 and 35 meq(100g)−1and are, for most samples, in the range reported for Boom Clay in Belgium (7–30meq(100g)−1).Pore water and solid-phase composition indicate that Rupel Clay from Zeeland has been affected by oxidation of pyrite or other Fe(II)-containing solids. When coupled to the dissolution of calcium carbonates, oxidation of pyrite can account for the elevated sulphate and calcium concentrations measured in some of the pore waters. The relatively low concentrations of pyrite, organic carbon and calcite in the Rupel Clay in Zeeland, in comparison to Limburg, might be an indicator for an oxidation event. Higher contents of dithionite-extractable Fe in Rupel Clay in Zeeland (0.7–2.6mg Fe / g clay) than in Limburg (0.4–0.5mg Fe / g clay) might also be a consequence of the oxidation of Fe(II) minerals. Oxidation in the past could have accompanied partial erosion of Rupel Clay in Zeeland before deposition of the Breda Formation. However, indications are given that oxidation occurred in some of the pore waters after sampling and that partial oxidation of the cores during storage cannot be excluded. Results from dilution experiments substantiate the influence of equilibration with calcium carbonates on pore water composition. Furthermore, removal of dissolved sulphate upon interaction with Rupel Clay has been observed in some dilution experiments, possibly involving microbial sulphate reduction.

Testing Safety and Performance Indicators in an Assessment of the Long-Term Performance of the Geological Disposal of Spent Fuel in Boom Clay

2003 ◽  
Author(s):  
Xavier Sillen ◽  
Jan Marivoet ◽  
Wim Cool ◽  
Peter de Preter
Keyword(s):  
Dose Rate ◽  
Performance Indicators ◽  
Spent Fuel ◽  
Geological Disposal ◽  
Boom Clay ◽  
And Performance ◽  
The Individual ◽  
High Level ◽  
Clay Formation

The classical numerical output, or indicator, from assessments of the long-term safety of geological disposal systems for high-level radioactive waste is the individual effective dose rate. This indicator is an estimate of the possible individual health detriment and it is commonly compared to regulatory limits for assessing the safety of other nuclear activities as well, such as medical and industrial activities. As a safety indicator, the individual dose rate provides an estimate of the overall safety of the disposal system. However, because of the time frames involved in safety assessments of geological disposal systems, the need arises of complementary safety indicators that could be less affected by uncertainties like those associated with future human behaviour or the effects of climate change on the biosphere and the aquifers. Such alternative safety indicators can be, for example, radionuclide concentrations in the groundwater or fluxes to the biosphere due to a repository. Safety indicators only tell how globally safe a disposal system is. For confidence building, performance indicators can be used in addition to tell how the system works. In particular, performance indicators such as fluxes, activities or activity concentrations of selected radionuclides can show how the different components of the system fulfil their safety functions and contribute to the overall safety. The SPIN project of the European Commission assessed the usefulness of seven safety indicators and fourteen performance indicators by testing them in four actual assessments of disposal systems in granite formations. In this paper, indicators calculated from an assessment of the disposal of spent fuel in the poorly indurated Boom Clay formation are presented. Conclusions from the SPIN project that hold for repositories in clays are highlighted, as well as results that illustrate differences between the granite and clay disposal options. Finally, various performance and safety indicators are combined into a logical sequence to comprehensively present, and explain, the results of a safety assessment.

Performance Assessment of Geological Disposal of High-level Radioactive Waste in a Plastic Clay formation

2002 ◽  
Vol 713 ◽  
Author(s):  
Jan Marivoet ◽  
Xavier Sillen ◽  
Dirk Mallants ◽  
Peter De Preter
Keyword(s):  
Performance Assessment ◽  
Performance Assessments ◽  
High Level Waste ◽  
Spent Fuel ◽  
Scenario Development ◽  
Boom Clay ◽  
Site Characterisation ◽  
High Level ◽  
Clay Formation ◽  
The Impact

ABSTRACTIn Belgium the possibilities to dispose of high-level waste in the plastic Boom Clay formation has been studied since 1975. Consequently many results of the site characterisation programme are already available. Various performance assessments have been carried out dealing with the disposal of high-level waste arising from reprocessing and with direct disposal of spent fuel. The performance assessment consists of two main steps: scenario development and consequence analyses. The scenario analysis is based on a catalogue of features, events and processes (FEPs) having the potential to influence the behaviour of the repository system. Two main groups of scenarios are distinguished. The normal evolution scenario, including a number of variants, treats the FEPs that are fairly sure to take place. Altered evolution scenarios focus on FEPs having a probability of occurrence lower than one but that might influence the performance of the repository system. For the impact analyses, a robust concept approach was introduced, which focused the analyses on a limited number of well-characterised barriers and processes. The impact analyses are complemented with sensitivity and uncertainty analyses based on deterministic and probabilistic approaches.

To the memory of the geobotanist. Leonid E. Rodin (to the 100th anniversary of his birthday)

2007 ◽  
pp. 106-107
Author(s):  
B. K. Gannibal
Keyword(s):  
End Of Life ◽  
100Th Anniversary ◽  
State University ◽  
Botanical Institute ◽  
Komarov Botanical Institute ◽  
The Future ◽  
Long Time ◽  
High Level

Leonid Efimovich Rodin (1907-1990) was a graduate of Leningrad state University. To him, the future is known geobotanica, happened to a course in Botanical geography is still at the N. A. Bush. His teachers were also A. P. Shennikov and A. A. Korchagin, who subsequently headed related Department of geobotany and Botanical geography of Leningrad state University. This was the first school scientist. And since the beginning of the 30s of XX century and until the end of life L. E. was an employee of the Department of geobotany of the Komarov Botanical Institute (RAS), where long time worked together with E. M. Lavrenko, V. B. Sochava, B. A. Tikhomirov, V. D. Alexandrova and many other high-level professionals, first continuing to learn and gain experience, then defining the direction of development of geobotany in the Institute and the country as a whole.

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