Processing Of Liquid Radioactive Waste Research Articles

Application of methods for the chemical and radiometric monitoring of liquid radioactive waste processing

ABSTRACT The processing and control of liquid radioactive waste (LRW) in nuclear power plants (NPP) are critical aspects of nuclear energy management. This study details the principles of the methods and the measuring instruments used for control, and highlights the features and advantages of chemical and radiometric control in radioactive waste processing. The purpose is to systematize and analyze the results and methods used for chemical and radiometric monitoring, treatment technologies, and adherence to regulatory standards. The paper presents findings from an operating NPP with water–water energy reactor power units, showcasing the novelty of systematizing monitoring methods at each stage of LRW processing and ensuring compliance with regulatory standards. Moreover, the chemical and radiometric indicators in the LRW were analysed, which provides insight into the dynamics of waste processing and classification. In addition, the application of Pearson correlation analysis allowed us to identify the relationships between chemical and radiometric indicators in the LRW, which provides valuable information for waste management practices. The selection of appropriate chemical and radiometric methods is crucial given the complexity of LRW characteristics, making this study relevant for enhancing LRW monitoring and management practices.

Removal of Cs-137 Radionuclide by Resorcinol-Formaldehyde Ion-Exchange Resins from Solutions Simulating Real Liquid Radioactive Waste.

The efficiency of the removal of Cs-137 radionuclides with porous and non-porous resorcinol-formaldehyde resins from alkaline solutions simulating the composition of real liquid radioactive waste (LRW) streams has been evaluated. Resins were synthesized through the polycondensation of resorcinol and formaldehyde in an alkaline medium at a molar ratio of 1.8/2.2 and a temperature of 210 °C. The Cs-137 distribution coefficients on RFRs in alkaline solutions simulating LRW were above 103 mL/g under static sorption conditions. In a model solution with pH 11, the full dynamic sorption capacity of non-porous RFR was 0.178 mmol/g. The values of the full dynamic sorption capacities of porous RFRs were 0.274 and 1.035 mmol/g for resins obtained with calcium carbonate and toluene as templates, respectively. When the sizes of RFR beads increased two-fold, the volume until 5% cesium breakthrough decreased by 20-40%. The most pronounced beneficial effect of the RFR's porosity was observed at flow rates from 25 to 50 BV/h. It was shown that the negative effect of metal cations on Cs-137 uptake increases in the following order: Na+ < Mg2+ < Ca2+ < K+. The number of bed volumes of LRW-simulating solution decontaminated with RFRs until 5% cesium breakthrough was above 450; that is higher than the value of known commercially available analogs. The latter shows that the developed RFRs are promising for application in technological schemes of alkaline LRW processing.

Анализ современных методов переработки кубовых остатков атомных электрических станций

To date, more than 600 thousand m3 of liquid radioactive waste has been accumulated at Russian nuclear power plants (NPPs). In addition to radioactive components, they contain a large amount of mineral salts, organic matter, oil products, and suspensions. The problem of overfilling the storage facilities for liquid waste at some NPPs is critical and has to be solved urgently. The article presents modern methods for processing vat residues and the existing prerequisites for modernizing ion-selective purification plants, which are based on the results of research works carried out by various teams. A technological analysis of the methods for evaporation and ion-selective purification of vat residues with identified shortcomings of individual stages of the technologies is carried out. Decontamination of secondary products of liquid radioactive waste processing implies the possibility of subsequently separating valuable components for reusing them. Their decontamination is necessary, since these wastes are essentially high-salt solutions with a specific activity of 106-107 Bq/l contaminated with fission products, radionuclides of corrosion origin, and various substances used to decontaminate the equipment and maintain the water chemistry. It is proposed to apply the electrodialysis method for separating a multicomponent solution of the decontaminated NPP vat residue and to use the obtained products at the plant. Owing to the partial extraction of valuable components from decontaminated vat residues, it becomes possible to reduce the amount of waste and return the separated substances into the main process cycle, thereby reducing the expenditures for initial reagents. To implement the developed technology for component-wise separation of the initial solution, a laboratory electrodialysis facility was manufactured. The project implementation feature was that in dealing with boric acid salts, it is necessary to take into account the danger of their precipitation at certain pH values. It was found that to minimize the escape of boric components, the process should be conducted at low pH values, i.e., the solution should be acidified with the nitric acid obtained in the process. The obtained study results can be used to modernize the cementation plants.

Научные и проектные аспекты остекловывания жидких радиоактивных отходов АЭС с ВВЭР-1200

The article presents a comparison of technologies for liquid radioactive waste bottom sediment processing from NPPs with WWER-1200 reactor units. Vitrifi cation and cementing methods were compared based on the state of art in the development of the Unifi ed State System for Radioactive Waste Management, as well as engineering and design study of various processing methods. The research demonstrates that industrial use of the vitrifi cation method can be seen as a promising one when it comes to the processing of liquid radioactive waste from NPPs and radiochemical plants.

Використання технологій опріснення морської води для попереднього упарювання рідких радіоактивних відходів

Processing of liquid radioactive waste (LRW) includes evaporation followed by vitrification. Reducing the energy consumption of evaporation of LRW is an urgent task. In the article, an attention is paid to the fact that similar technical and economic problems are solved with the desalination of seawater. It is proposed to use well-developed seawater desalination technologies for preliminary evaporation of LRW. For a detailed analysis, desalination technology with mechanical vapor compression (MVC) was selected. This technology is energy-saving because it implements the heat pump principle. MVC technology is highly efficient, simple, and does not lead to the generation of secondary radioactive waste. A mathematical model of a single-stage desalination plant with MVC has been developed, taking into account that the thermodynamic cycle of this process is open. Since there are no data on the physical properties of LRW in the literature, the properties of sea water were used. The design and operational parameters were optimized in order to reduce the cost of 1 m3 of evaporated water. It has been established that the main design parameters affecting the cost of evaporated water are the degree of vapor compression in the compressor and the heat exchange surface area of the evaporatorcondenser. The influence of these parameters on capital and operating costs is shown. The optimal combinations of these parameters are determined. To ensure the optimal operating mode of the installation, it is necessary to maintain the optimum salt content of boiling brine, which is determined by the rate of consumption of the source water. The optimal values of these parameters are calculated in a wide range of salt content of the source water. It is shown that, at low salinity of the initial LRW, evaporation is advisable to be carried out in a multi-stage installation. As a result of the calculations, it was found that the specific cost of evaporation of liquid radioactive waste with an initial salt concentration of 10% to a salt content of 20% using the desalination technology with mechanical vapor compression is 0.843 USD/m3.

Дослідження процесів озонолізу органічних компонентів модельних розчинів рідких радіоактивних відходів реакторів ВВЕР

The article highlights the problem of reprocessing of liquid radioactive waste (LRW) from the Ukrainian nuclear power plants with VVER reactors. The main method of these LRW treatment is distillation (evaporation) and ion exchange sorption. The final products of LRW processing by distillation are distillation residues, spent sorbents and sludges, and salt melt with significant radioactivity accumulated in large volumes, which do not meet the long-term storage and disposal criteria. So, it is necessary to develop a new, more efficient LRW treatment scheme that can solve the problems of large volumes of LRW and transfer waste to a state suitable for long-term storage and disposal. One of the important and challenging problems of LRW treatment is the presence of organic components (ethylenediaminetetraacetic acid (EDTA), oxalic acid, synthetic surfactants (SPAR) in the waste, since these substances complicate removal of radionuclides from the LRW. The results of investigation of ozonolysis conditions of LRW organic components are presented on the example of a model solution with imitated solutions of disodium salt of ethylenediaminetetraacetic acid and ethane diacid. It was established, that ozonation of organic components of LRW results in decreasing of pH value, which causes reduction of their destruction efficiency. Control of the pH values at the initial level (11−12 units) by permanent alkalifying can increase the ozonolysis efficiency of LRW organic components in 30%. EDTA is better destructed by ozone than ethane diacid. Destruction of LRW organic components progresses in two stages: the first is fast and second is low. The maximum of EDTA destruction degree, in the experimental conditions, was 86%; destruction degree of ethane diacid — 51%; maximum of LRW model solution organic components (EDTA, ethane diacid, synthetic surface-active reagent) destruction degree was 67%. Due to co-precipitation and adsorption during the solution ozonizing, decrease in Mn concentration in LRW model solution reaches 94.3%, 137Cs activity decreases by 26%, and 90Sr — 15.7%, concentration of Co decreases only by 6%.

Kola Peninsula in solving problems of national arctic materials science

The Kola Peninsula is one of the most developed Arctic regions in Russia and in the world. Its share in the Russian production of apatite, nepheline, loparite and baddeleyite concentrates is 100%. The region produces up to 45% of nickel, and 13% of copper, and the majority of rare-earth metals, niobium, and titanium compounds from the regional minerals. The ores mined from the existing deposits can be used for production of up to 30 various concentrates. The materials produced from the regional minerals include metal nickel, cobalt, copper, titanium, niobium, rare-earth metals, steel; sealants, components of electrode coatings and welding fluxes, sorbents for disposal of radioactive waste and wastewater containing heavy non-ferrous metals and other contaminants, high-porous heat insulation and fire-resistant materials for arctic application, cement, concretes with improved resistance to frost and sea water. In satisfying demand for new materials, the first and foremost objective is to establish a pilot engineering base for adaptation of process flowsheets, and collection of data for design and construction of new operations. Successive implementation of this objective requires concentrated efforts of scientists and engineers focused on implementation of the Kola Chemical and Technological Cluster Project, which enables to improve significantly the economy of minerals use by means of products of their deep processing. At the first stage of the Cluster operation, a process of new titanium sorbents production will be established to solve environmental issues — treatment of non-ferrous metals industry wastewater from heavy metals, and processing of liquid radioactive waste accumulated in the Arctic zone of Russian Federation.

Indonesia’s Local Material Effect in Clay-Based Ceramic Filter Fabrication as an Alternative for Liquid Radioactive Waste Processing Material

One of the procedures to handle liquid radioactive waste is by filtration process. To do this process, suitable filter should be used because of radioactive nature of the waste. Ceramic filter is one of the suitable filters that could be used for this purpose. This paper will discuss about producing ceramic filter from local clay and test its performance. Performance of the filter is given by its flux, compressive strength, Decontamination Factor (DF) and adsorption efficiency. The results show that there are almost no effects of casting pressure on both flux and compressive strength of ceramic filter, but zeolite addition produces different effect. The higher concentration of zeolite will decrease the filter flux and increase filter compressive strength. The optimal composition from this research is 70% w/o clay-25% w/o zeolite-5% w/o charcoal. It has adsorption efficiency (60.36) and Decontamination Factor (2.52). Besides, Sr concentration after filtration is still higher than environmental standard for Sr-90 and more studies are still needed.

Современные окислительные и фотоокислительные методы разрушения комплексонов в жидких радиоактивных отходах

State-of-the-art analysis for oxidizing technologies related to destruction of complexons and metalloorganic complexes in
 liquid radioactive waste has been carried out. Ways already put into practice, as well as the experimental ones have been
 considered. Oxidation by potassium permanganate and hydrogen peroxide and also ozonization and photo oxidation have
 been considered in detail. It has been shown that oxidation by potassium permanganate with subsequent filtration leads to
 decrease of isotopes activity, but hereby a considerable volume of manganese dioxide is formed. The ozonization application
 allows reduce considerably the liquid radioactive waste (LRW) volume, but along with this ozone is the extremely toxic and
 explosive substance demanding a special equipment for its production. Efficiency of oxidation by hydrogen peroxide and photo
 oxidation without catalysts is low. The special attention has been paid to combined oxidizing methods (AOP) based on use of
 ultra-violet (UV) radiation together with ozone and/or hydrogen peroxide. Such methods allow apply the strongest oxidizer –
 hydroxyl radical – for LRW processing. Efficiency of AOP-methods and their technological capabilities are substantially defined
 by characteristics of used UV radiation sources. A detailed analysis for a wide range of UV radiation possible sources (low
 and average pressure mercury lamps, amalgamate lamps, excimer lamps, light-emitting diodes and pulse xenon lamps) has
 been carried out, their comparative assessment has been executed. Great potential opportunities for the pulse xenon lamps
 providing a continuous range of radiation in UV area and high intensity for a stream of high-vigorous photons have been noted.

Concept of autonomous processing of liquid radioactive waste from ship nuclear power installations

The concept of autonomous processing of liquid radioactive waste from ship nuclear power installations is substantiated, and its implementation in the form of a module membrane sorption installation consisting of micro- and ultrafiltration, reverse-osmosis, and ion-exchange modules is suggested. Data on treatment of liquid radioactive waste of complex physicochemical composition using this installation are reported.

Mobile modular installation for processing liquid low- and average-radioactive waste

The mobile modular installation for processing of liquid radioactive waste of complex physic-chemical composition is developed in co-operation of the All-Russian Research Institute of Chemical Technology and a number of research and production organisation. The complex treatment of the solutions is done in a membrane adsorption technology followed by the cementation of formed sediments and slimes. The distinctive feature of the proposed LRW processing scheme is the ability to nearly completely extract the most dangerous radionuclides Cs- 137, Co-60 and Sr-90 on the selective inorganic Co-, Ni-,Cu-containing adsorbents at the stage of the initial solution pre-cleaning. The developed scheme on ensures a possibility of reusing purified water according to standard OST V95.823-89 and the minimum quantity of SRW ensuing at the LRW processing.

Ion-Exchange Property and Thermal Stability of Hydrous Metal Oxide Ion Exchangers

Ion-exchange property and thermal stability were studied on four synthetic hydrous metal oxides from the viewpoint of applicability for the processing of liquid radioactive waste. Hydrous titanium (IV) oxide and hydrous niobium (V) oxide, consisting of metal ions having larger ionic potential, possessed large cation-exchange capacities, and showed high affinity for both the transition metal ions and the representative element ions. Hydrous tin (IV) oxide and hydrous zirconium (IV) oxide, consisting of metal ions having smaller ionic potential, were amphoteric ion exchangers possessing large anion-exchange capacities, and showed much higher affinity for the transition metal ions than for the representative element ions. The selectivity series are understood in terms of the formation of a bond partially covalent in character for the transition metals, and the purely electrostatic interaction between anionic exchange sites and unhydrated or hydrated cations for the representative elements. An examination of the effects of heat treatment in air on the ion-exchange properties indicated that the hydrous niobium (V) oxide was the most stable among the four hydrous metal oxides. Even this material, however, was not stable enough to be used under hydrothermal conditions.

Ion-exchange property and thermal stability of hydrous metal oxide ion exchangers.

Ion-exchange property and thermal stability were studied on four synthetic hydrous metal oxides from the viewpoint of applicability for the processing of liquid radioactive waste. Hydrous titanium (IV) oxide and hydrous niobium (V) oxide, consisting of metal ions having larger ionic potential, possessed large cation-exchange capacities, and showed high affinity for both the transition metal ions and the representative element ions. Hydrous tin (IV) oxide and hydrous zirconium (IV) oxide, consisting of metal ions having smaller ionic potential, were amphoteric ion exchangers possessing large anion-exchange capacities, and showed much higher affinity for the transition metal ions than for the representative element ions. The selectivity series are understood in terms of the formation of a bond partially covalent in character for the transition metals, and the purely electrostatic interaction between anionic exchange sites and unhydrated or hydrated cations for the representative elements. An examination of ...