Advanced Vitreous Wasteforms for Radioactive Salt Cake Waste Immobilisation

MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 121-129
Author(s):  
Vladimir A. Kashcheev ◽  
Nikolay D. Musatov ◽  
Michael I. Ojovan
Keyword(s):  
Radioactive Waste ◽  
Liquid Radioactive Waste ◽  
Synthesis And Characterization ◽  
Cold Crucible ◽  
Leaching Rate ◽  
Salt Cake ◽  
Solid Salt ◽  
Cement Compound

AbstractSalt cake radioactive waste is a remnant solid salt concentrate after deep evaporation of radioactive evaporator concentrate at WWER NPP’s. The traditional cementing of borate-containing liquid radioactive waste, to which the salt cake belongs, leads to a significant increase in the volume of the final product. This work describes borosilicate vitreous wasteforms developed to immobilize radioactive salt cake waste and comprises data on both glass synthesis and characterization. The composition of glass selected for the purpose of immobilisation of the salt cake radioactive waste allows to include up to 40 wt. % of the oxides contained in the salt cake and to reduce the volume of the final product by more than 2 times compared with the cement compound. The batches were melted in a cold crucible melter at 1200 °C. The normalized cesium leaching rate of the vitrified wasteform product was within range 3.0·10-5 – 3.7·10-6 g/(cm2·day).

scholarly journals Influence of Geopolymer Binder Components on Properties of Compounds during Cementation of Boron-Containing Liquid Radioactive Waste

2021 ◽  
Vol 21 (2) ◽  
pp. 71-77
Author(s):  
Yu. G. Fedorenko ◽  
◽  
Yu. A. Olkhovyk ◽  
A. N. Rozko ◽  
G. P. Pavlyshyn ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Liquid Glass ◽  
Potassium Hydroxide ◽  
Linear Equations ◽  
Liquid Radioactive Waste ◽  
Correlation Coefficients ◽  
Component Composition ◽  
Normative Values ◽  
Leaching Rate ◽  
Base Compound

The paper presents an analysis of the experimental results of the use of geopolymer binders for cementing boron-containing liquid radioactive waste (LRW). The dependence of the properties of compounds on the component composition of binders has been studied. The following components are considered: liquid glass with a silicon modulus of 2.9, a mixture of ash of Darnytsya TPP with slag of the Mariupol metallurgical plant in a ratio of 1: 1 and potassium hydroxide. To perform a factor analysis of the effect, the mass of these substances was taken as three factors in the analysis at two levels. For the manufacture of compounds imitation LRW was mixed with zeolite in a ratio of 10:1 at a temperature of about 60 оC. Subsequently, the above components were added to the mixture, the weight of which varied by ±17% relative to the weight of the base compound. To study the properties, samples of different sizes 5×5×5 cm, 1.5×1.5×1.5 cm and rectangular samples with an outer surface from 96 cm2 to 104 cm2 were made. Each property was studied in 8 samples. The obtained results allowed to construct linear equations that quantitatively link the corresponding characteristic of the compound with the composition of the binders. The correlation coefficients between the experimental and the data calculated by the equation are estimated. The average values of the correlation coefficients may indicate that not all factors were taken into account. The obtained regularities show that in the conditions of the experiment slag and ash increase, and liquid glass and potassium hydroxide reduce the rate of setting of the samples. The density of the samples is increased by ash and slag, while liquid glass and potassium hydroxide are reduced. The compressive strength of liquid glass and potassium hydroxide is reduced, while the mixture of ash and slag is increased. The leaching rate Сs of liquid glass and potassium hydroxide is increased, the mixture of ash and slag is reduced. At the same time, the leaching rate of Sr increases the ash/slag mixture, while liquid glass and potassium hydroxide decrease. The time during which the leaching of Cs reaches the normative values, slag and ash are reduced, and liquid glass and potassium hydroxide are lengthened. The obtained results can be taken into account when optimizing the composition of geopolymer binders for cementing LRW.

Cold Crucible Vitrification of NPP Operational Waste

2002 ◽  
Vol 757 ◽  
Author(s):  
Feodor A. Lifanov ◽  
Michael I. Ojovan ◽  
Sergey V. Stefanovsky ◽  
Rudolf Burcl
Keyword(s):  
Radioactive Waste ◽  
Nuclear Power ◽  
Power Plants ◽  
Glass Melting ◽  
Liquid Radioactive Waste ◽  
Specific Radioactivity ◽  
Melting Process ◽  
Specific Power ◽  
Cold Crucible ◽  
Minimal Impact

ABSTRACTOperational radioactive waste is generated during routine operation of nuclear power plants (NPP). This waste must be solidified in order to ensure safe conditions of storage and disposal. Vitrification of NPP operational waste is a relative new solidification option being developed for last years. The vitrification technology comprises a few stages, starting with evaporation of excess water from liquid radioactive waste, followed by batch preparation, glass melting, and ending with vitrified waste blocks and some relative small amounts of secondary waste. Application of induction high frequency cold crucible type melters facilitates the melting process and significantly reduces the generation of secondary waste. Two types of glasses were designed in order to vitrify operational waste depending on the reactor type at the NPP. For the NPP with RBMK-type reactors the glass 16.2Na2O 0.5K2O 15.5CaO 2.5 Al2O3 1.7Fe2O3 7.5B2O3 48.2SiO2 1.1 Na2SO4 1.2NaCl (5.7 others) was produced. For NPP with WWER reactors the glass 24.0Na2O 1.9K2O 6.2CaO 4.3Al2O3 1.8Fe2O3 9.0B2O3 46.8SiO2 0.8Na2SO4 0.9NaCl (4.3 others) was produced. The melting temperatures of both glass formulations were 1200–1250 C, specific power consumption was 5.2 ± 0.8 kW h/kg, 137Cs loss was within the range 3 - 4 %. The specific radioactivity of glass reached 7.0 MBq/kg. Glass blocks obtained were studied both in laboratory and field conditions. Long-term studies revealed that vitrified NPP operational waste has the minimal impact onto environment. Since the glass has excellent resistance to corrosion it gives the basic possibility of maximal simplification of engineered barrier systems in a disposal facility. The simplest disposal option for vitrified NPP waste is to locate the packages directly into earthen trenches provided the host rock has the necessary sorption and confinement properties.

scholarly journals WATER RESISTANCE OF SOLIDIFIED RADIOACTIVE WASTE

2020 ◽  
Vol 2 (61) ◽  
pp. 61-69
Author(s):  
V. Kovalchuk ◽  
◽  
I. Kozlov ◽  
O. Dorozh ◽  
N. Bogdanov ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Liquid Radioactive Waste ◽  
Aqueous Media ◽  
Matrix Material ◽  
Experimental Studies ◽  
Positive Temperature ◽  
Leaching Rate ◽  
The Matrix ◽  
Cement Matrices ◽  
The Absolute

The results of experimental studies of leaching characteristic of liquid radioactive waste of radionuclides from cement matrices for long-term storage are considered. It is shown that leach ability is a characteristic of the chemical resistance of matrices, indicating the ability of the matrix material to prevent the spread of radionuclides localized in them into the environment. It is noted that the rate of leaching of radionuclides from cement matrices changes with the time of their contact with aqueous media. Chronometric dependences of leaching rates are presented and analysed. It is shown that they consist of two sections of different duration. The initial section, lasting up to 250 hours, is distinguished by a higher steepness with a decrease in the absolute value of the speed to 2 orders of magnitude. The subsequent section, lasting up to 2500 hours or more, is characterized by an asymptotic decrease in speed to a constant minimum value. Approximating functions of the experimental chronometric dependences of radionuclide leaching were obtained in the form of power-logarithm expressions, valid in the intervals of the duration of the experiments, with a reliability of at least 0.9. It is shown that monovalent sodium and cesium ions are most intensively subject to leaching. The absolute values of the rates of leaching of monovalent nuclides are two to three orders of magnitude higher than those of divalent ones, all other things being equal. The content of the nuclide in the composition of the compound material has a significant effect on the leaching rate. An increase in matrix temperature promotes an increase in leaching rates, which is most likely due to a positive temperature coefficient of diffusion characteristics. Irradiation of the matrices decreases the leaching rate as a result of a decrease in the porosity of the matrix body and the formation of poorly soluble hydrates. The redox values of matrix-bound solutions have no significant effect on the leaching rate.

Application of the Dry Polyfunctional Additives at Radioactive Waste Cementation

2003 ◽  
Author(s):  
Andrey P. Varlakov ◽  
Konstantin M. Efimov ◽  
Valeri N. Tchernonojkine ◽  
Aleksandr S. Barinov ◽  
Olga A. Gorbunova
Keyword(s):  
Radioactive Waste ◽  
Liquid Radioactive Waste ◽  
Aggregation State ◽  
Technological Processes ◽  
Cement Compound ◽  
Liquid Condition ◽  
Solid Radioactive Waste ◽  
The Cost ◽  
Polyfunctional Additive

One of the known methods directed to improving of the technological cementation process, the increasing quality of a cement compound and degree of radioactive waste incorporating into a final product, is use of the various additives to a cement compound. At present there are technological processes where one or two additives in a dry loose or liquid condition in quantity of 1–10% are used. The application of these additives is directed, as a rule, to improving of one or two properties of a cement compound. The magnification of a quantity of the additives and use of them in a different aggregation state is connected with rise in the cost of the technological process. At Institute of Ecology and Technology Problems and Moscow SIA “Radon” the polyfunctional modifying additives representing dry mixtures of original macro- and microadditives to cement have been developed. The polyfunctional additive is introduced by traditional, reliable and inexpensive equipment directly into liquid radioactive waste and intermixed together with the rest of cement. The quantity of additive varies from 5 up to 20% of cement weight. The additives considerably improve all regulated properties of a cement compound (compressive strength, radionuclides leaching, frost resistance, biological resistance, etc.) and allow modifying the required properties (penetrating ability, viability, disintegration, terms of setting, viscosity etc.). Such additives are used both at cementation of solid radioactive waste and cementation of liquid radioactive waste having a complicated chemical composition, for example, containing simultaneously boric acid, sulphates and great quantity of organic compounds. It is important, that the components of the additives did not change the action in a mixture with other ones. In the report the compositions of the polyfunctional additives developed for various waste and technological processes, their properties and results of practical application are represented.

scholarly journals Perspective Schemes of Conditioning of Liquid Radioactive Waste of Ukrainian Nuclear Power Plants

2020 ◽  
Vol 18 ◽  
pp. 48-56
Author(s):  
Yu. A. Olkhovyk ◽  
Keyword(s):  
Radioactive Waste ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Liquid Radioactive Waste ◽  
Ventilation System ◽  
Salt Cake ◽  
Safe Level ◽  
Time Required ◽  
Storage Facilities

The existing world experience of practical use of sorption technology and technology of cementing liquid borne radioactive waste of nuclear power plants (NPP) with water-water energetic reactors (WWER) to obtain a product 1suitable for transfer to disposal facilities is considered. It has been concluded that salt cake accumulated in NPP storage facilities is a major problem that determines the further choice of the development and implementation of conditioning technologies. Currently, 18,000 salt cake containers stored at the Zaporizhzhia NPP and Khmelnitskiy NPP storage facilities have exceeded their design life. A possible solution is to change the classification of the salt cake and to classify it as solid radioactive waste. It is noted that the existing tax system for the generation of radioactive waste in Ukraine does not contribute to the choice of conditioning technologies aimed at minimizing the volume of the final product. The prospect of application of the technology of melting in the “cold crucible” for one-stage formation from a evaporator bottoms and salt cake borosilicate glass, guaranteed capable in the conditions of surface disposal to ensure the isolation of radionuclides during the time required for decay to a safe level of radioactivity. It is proposed to create a melting unit according to the modular scheme, when several parallel crucibles with capacity up to 20 kg/h with cheaper highfrequency generators with a capacity of 160 kW are connected to common ventilation system. The urgency of carrying out technical and economic analysis to determine the optimal 56 ISSN 2311-8253 Nuclear Power and the Environment № 3 (18) 2020 solutions for the introduction of effective and economically sound technologies for the processing of evaporator bottoms and salt cake at Ukrainian NPPs is emphasized.

Development of Technology for Cementation of Oil Containing LRW Using Porous Concrete

2007 ◽  
Author(s):  
S. A. Dmitriev ◽  
A. P. Varlakov ◽  
A. V. Germanov ◽  
O. A. Gorbunova ◽  
A. S. Barinov ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
New Technology ◽  
Liquid Radioactive Waste ◽  
Negative Influence ◽  
Cement Matrix ◽  
Porous Concrete ◽  
Cement Compound ◽  
Concrete Matrix

A new technology of oil containing liquid radioactive waste conditioning has been developed at SIA “Radon”. A porous concrete matrix is placed into special containers and impregnated with oil containing liquid radioactive waste. The waste is effectively fixed in the porous cement matrix. The final product has all the regulated properties. The content of oils in the cement compound can be up to 40% wt. The technology excludes negative influence of oils on hydration of cement which usually occurs at co-cementation of oils with salt liquid radioactive waste.

scholarly journals Inclusion of liquid radioactive waste into a cement compound with an additive of multilayer carbon nanotubes

2019 ◽  
Vol 227 ◽  
pp. 052030 ◽  
Author(s):  
Tatiana Kulagina ◽  
Vladimir Kulagin ◽  
Eleonora Nikiforova ◽  
Dmitriy Prikhodov ◽  
Alexander Shimanskiy ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Radioactive Waste ◽  
Liquid Radioactive Waste ◽  
Multilayer Carbon Nanotubes ◽  
Cement Compound

Application of Polyhexamethyleneguanidine Type Biocides at Cementing the Radioactive Waste

2001 ◽  
Author(s):  
Andrey P. Varlakov ◽  
Olga A. Gorbunova ◽  
Aleksandr S. Barinov ◽  
Vadim A. Iljin ◽  
Konstantin M. Efimov ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Compression Strength ◽  
Radiation Resistance ◽  
Water Resistance ◽  
Leaching Rate ◽  
Biocidal Activity ◽  
Wide Range ◽  
Cement Compound ◽  
Biological Corrosion

Abstract In order to prevent biological corrosion of cement compound containing radioactive waste, it is proposed to use biocidal additives of polyhexamethyleneguanidines (PHMG), which have a wide range of biocidal activity. It has been shown that inclusion of biocidal additives of polyhexamethyleneguanidines in quantities 0,25–2% wt. into the grout used for the solidification of radioactive waste (RW) or for recovering the integrity of old RW repositories provides the necessary bacteriostatic and biocidal protection of cement compound and improves all the regulated properties — compression strength, Cs-137 leaching rate, frost-resistance, radiation resistance and long term water resistance.

scholarly journals Liquid Radioactive Solidification Technologies

2019 ◽  
pp. 68-74 ◽  
Author(s):  
V. Svidersky ◽  
V. Glukhovsky ◽  
I. Glukhovsky ◽  
T. Dashkova
Keyword(s):  
Radioactive Waste ◽  
Nuclear Power ◽  
Power Plants ◽  
Liquid Radioactive Waste ◽  
Cement Stone ◽  
Leaching Rate ◽  
Additional Water ◽  
Volumetric Characteristics ◽  
Leaching Parameters ◽  
The Cost

This review provides a brief analysis of familiar and tested technologies of liquid radioactive waste solidification. The technologies of bituminization, vitrification and incorporation of radioactive waste into the polymer matrix are considered. The paper presents the efficiency indices of the conventional cementation technology and sets forth the results of calculating the cost of components for cementing liquid radioactive waste of various concentrations. Besides, there are results of calculating the volumetric characteristics of cement stone for water-cement relations used for cementing liquid radioactive waste. The review includes the results based on the development and implementation of solidification technologies for liquid radioactive waste using contact-hardening binders that form a durable waterproof stone at the time of pressing and do not require additional water for curing. Generated compounds for immobilization of liquid radioactive waste from nuclear power plants are tested to identify their strength characteristics, resistance to irradiation and leaching parameters. The paper covers the calculation of the cost of components for the solidification of liquid radioactive waste of various concentrations. The developed technology of liquid radioactive waste solidification allows obtaining compounds with strength up to 40 MPa. The volume of the final product is increased by 1.8 times, and the leaching rate is in the range of 1.10×10–4…9.5×10–5 kg/m2 per day.

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