Method of processing oxalate mother waters and pulp wastes containing transuranium elements
FIELD: process engineering.
SUBSTANCE: invention relates to treatment of radioactive fluid and pulpy wastes formed in recovery of radiated nuclear fuel. Proposed method comprises destructing oxalate ions in mother waters by nitric acid in the presence of variable-valency metal ions. Processing of oxalate mother solution and pulpy wastes comprises mixing mother solution with solid phase of hydroxide pulp.
EFFECT: power savings, decreased amount of radioactive wastes.
3 cl, 3 tbl
The invention relates to the field of processing liquid and will be dissolved radioactive waste (radwaste)generated during the reprocessing of irradiated nuclear fuel (SNF), and can be used in radiochemical industry.
In many enterprises for the processing of irradiated nuclear fuel (SNF) accumulated hydroxide will be dissolved RAO, containing actinoid elements and ions of metals of variable valence. The tightening of the requirements for the storage of radioactive waste, necessitates the processing of such raw. To dissolve the hydroxide will be dissolved RAO typically use solutions of nitric acid, containing oxidants or reductants [Zakharova E.V., Ermolayev, V. M., Bondin, V.V. and others Studying the possibility of using solutions of different composition for decontamination production insoluble precipitation of radionuclides, primarily from plutonium. The report IPC RAS and MCC, 2003, inv. No. 13-16/1250 from 23.09.03]. After dilution of the pulp to extract from them actinoid elements are used, as a rule, the extraction method of processing.
At the same time on reprocessing of spent fuel one of the final stages of SNF processing is oxalate deposition of transuranium elements (TUE). Use this operation in the flow charts associated with certain difficulties, uslovlennyj inevitable obtaining relatively large amounts of oxalate mother solutions. These solutions are not drainage, so as to contain 100 mg/l TUE. The concentration of nitric acid oxalate in the mother solution is 160-200 g/l to Return uterine solutions in the extraction cycle does not allow the concentration to 10 g/l of oxalic acid, which significantly affects the extraction behavior of uranium, plutonium, and neptunium. In order oxalate uterine solutions containing TUE, process, you must destroy them in the oxalate ions.
There is a method of destruction of the oxalate ions when Parke mother solutions of nitric acid with a concentration of 12 mol/l [Jenkins J.L., Keen N.I., Wain A.G. Extractive and physical metallurgy of plutonium and it's alloys. New York: Intersci. Publ. 1960. R].
The disadvantages of this method are: low rate of oxidation of oxalic acid nitrate-ions and high energy costs.
There is a method of destruction of the oxalate ions by oxidation of their strong oxidizers [Plutonium. The Handbook, edited by Vic. - M.: Atomizdat, 1971, so S-409].
The disadvantages of this method are: high consumption of oxidants and weight increase of radioactively contaminated salts, resulting from the use of the method, requiring subsequent processing and immobilization.
A known method of disposal mother solutions by oxidation of oxalate ions and nitric acid in the presence of the cat is Isadora - ions of metals of variable valency, which is used as the ions of manganese. This mother liquor is introduced into contact with the silica gel containing manganese ions. The process is conducted by heating until complete evaporation of aqueous solutions of [the Patent of Russian Federation №2111562, CL G21F 9/04, G21F 9/16 from 20.05.1998]. This method is chosen as a prototype.
The disadvantages of this method are the high energy costs and the increase in the mass of radioactive waste through the use of additional reagent silica gel with salts of manganese, requiring subsequent processing and immobilization.
The aim of the proposed method is to reduce energy costs and reducing the mass of generated radioactive waste through the use of joint processing of Queen cells containing transuranium elements, and solid phase hydroxide slurry waste of radiochemical production.
This goal is achieved by the fact that instead used in the known method the radiation of pure silica gel, containing manganese, use the waste of radiochemical production - hydroxide radioactive slurry containing actinoid elements and ions of metals of variable valence, in the presence of which is the destruction of the oxalate ions. The concentration of nitric acid oxalate in the mother solution directed to account the aims with the solid phase of slurries, is 60-200 g/l
The use of this slurry allows you to destroy the oxalate ions in solution at room temperature and does not create an increase in the mass of generated radioactive waste by eliminating the use of additional radiation pure reagents.
The inventive method is tested in laboratory conditions. In the experiment used the production mother liquor generated during the reprocessing of irradiated nuclear fuel (see table 1, solution 1). In addition, treatments were carried out with solutions 2 and 3 (table 1), obtained by dilution of the original stock solution with distilled water in 2 and 3 times, respectively.
|The compositions of the solutions taken to process|
|The number of treatment and mortar||HNO3, g/l||H2C2O4, g/l||Ri, mg/l||U, g/l||NH4NO3, g/l|
The processing solutions of the proposed method was performed by solid phase hydroxide radioactive slurry, the composition of which is given in table 2.
|The composition of the hydroxide pulp|
|Component or indicator||Dimension||The magnitude component or indicator|
|The activity of β-emitting nuclides||CI/l||2,9|
|Water-insoluble solid phase||g/l||57,7|
In the experiment the proposed method used a portion hydroxide slurry with a volume of 4 ml Volume of solution before treatment was 50 ml. Pace is the atur solutions when processing samples of the solid phase was 20-22°C. The duration of contact of the solutions with samples of the solid phase under stirring was 4 o'clock the Remainder of nerastvorimaya solid phase of the pulp is connected to another portion of the slurry is directed to communicating with the new portion of oxalate stock solution. The examples were carried out in a measuring glass cylinders.
The results presented in table 3 show that during the processing of the original mother liquor or its diluted solution is the destruction of the oxalate ions. In the resulting decantate is a decrease in the total acidity of the solution due to the destruction of the oxalate ions and nitric acid in the course of redox reactions and partial neutralization of the acid metal hydroxides. The chemical composition of the obtained solutions are suitable for processing extraction methods.
1. A method of processing oxalate mother solutions radiochemical production containing transuranium elements, including the breakdown in the mother solution of the oxalate ions nitric acid in the presence of metal ions of variable valence, characterized in that the processing oxalate stock solution will be dissolved and waste carried out jointly by mixing the mother liquor from the solid phase hydroxide slurry.
. The method according to claim 1, characterized in that the concentration of nitric acid oxalate in the mother solution directed to the contact with the solid phase of slurries is 60-200 g/l
3. The method according to claim 1, characterized in that the balance nerastvorimaya solid phase of the pulp is connected to another portion of the slurry is directed to communicating with the new portion of oxalate stock solution.
FIELD: power industry.
SUBSTANCE: invention refers to processing technology of spent nuclear fuel of nuclear power plants (NPP SNF). Handling method of deposits based on molybdenum at processing of NPP SNF provides for liberation of molybdenum in the form of nonstoichiometric zirconium molybdate at heating of initial nitrogen acid solution, differs by the fact that the deposit which has been precipitated or settled at heating of temperature of 95-130°C of initial solution containing 100-900 g/l U and 1.0-3.5 mol/l HNO3, is separated from it and treated with solution of decomposable complexing agent, which is then adecomposed; after that, molybdenum is deposited for the second time at increased temperature and controlled acidity of solution by introducing salt-nonforming oxidation-reduction reagent, and mother solution is returned to the process. As complexing agents of molybdenum there used are ligands capable of self-decomposition without any residue nitrogen acid solutions, and namely hydric dioxide or carbonates of monovalent cations. As reducing agent there used is hydrazine nitrate or U (IV) in presence of hydrazine, and as oxidiser there used are nitrogen oxides or small quantities of Mn (VII) or Cr (VI).
EFFECT: invention allows avoiding losses of plutonium with deposits of zirconium molybdate.
7 cl, 4 ex
SUBSTANCE: method to detect a volume of radioactive soil consists in detection of borders of a contaminated area, building triangulation models of upper and lower surfaces limiting the sought-for volume, building a 3D model of a sought-for volume and calculating a volume. The upper limiting surface is a triangulation model of contaminated area surface relief made on the basis of a geodesic survey. The lower limiting surface is a triangulation model of conventional surface determined with soil contamination depth, such as soil thickness above solid geological rocks determined by means of a georadar survey or determined by means of dosimetric monitoring of wells drilled on the contaminated area.
EFFECT: invention makes it possible to increase accuracy of radioactive soil volume detection, which in its turn will reduce consumption of decontaminant substances, and will also make it possible to select optimum versions for soil excavation.
SUBSTANCE: method of reagent decontamination of sandy soils from caesium radionuclides involves treatment of soils with water solution containing decontaminating reagents which include sulphuric acid with concentration of 2-4 M at ratio of liquid and solid phases of 0.5/1-1/1 in autoclave at temperature of 100-140°C, with further separation of water solution with decontaminating reagents from cleaned soil; after that, caesium radionuclides are extracted from separated water solution with decontaminating reagents by supplying to the above solution of ferrocyanide of alkali metals or ammonium till the concentration is 6·10-4÷7·10-2 M with formation of deposit. Treatment of fine fractions is performed in autoclave at ratio of liquid and solid phases of 2/1-3/1. Some portion of reagent solution (1/2 at ratio of liquid and solid phases of 2/1 and 2/3 at ratio of liquid and solid phases of 3/1) is moved by means of decantation to precipitator in which caesium radionuclides extraction is performed. Reagent solution is supplied back to autoclave, mixed with the rest reagent solution and fine fractions, and that operation is performed for 2-3 times. Sulphuric acid is added to reagent solution till original concentrations, and stage of reagent treatment is repeated at the same parameters. Determination of specific caesium activity in fine fraction is performed; if contamination level corresponds to sanitary regulations, reagent treatment is stopped.
EFFECT: invention allows increasing soil decontamination coefficient for their cleaning till the level of sanitary regulations.
1 ex, 1 tbl
FIELD: power industry.
SUBSTANCE: chemical decontamination method of radioactive materials involves surface treatment of materials with water solution of chemical reagents. As water solution of chemical reagents there used is the solution containing sodium hydroxide, potassium hydroxide, calcium hypophosphite, pine rosin and water as its base and having the following component ratio (wt %): sodium hydroxide - 4.14-4.16, potassium hydroxide - 1.15-1.17, calcium hypophosphite - 0.16- 0.18, pine rosin- 0.87-0.89, water - up to 100.
EFFECT: invention allows developing easier, more effective and environmentally friendly method of chemical decontamination of radioactive contaminated materials using environmentally friendly composition of chemical reagents.
SUBSTANCE: invention relates to the field of environmental protection, namely, to devices for removal of radioactive contamination from metal surfaces. The plant comprises a cathode device in the form of a net arranged between a rubber sheet and a net from flexible corrosion-resistant non-conducting material. The surface of the rubber sheet covers the surface of the net from corrosion-resistant current-conducting material, and the net surface, and the net surface covers the net surface from corrosion-resistant current-conducting material; a nozzle for vacuumising of the cathode device, removal of sludge and electrolyte, the base of which is a flange of stainless steel attached mechanically, one nozzle for supply of electrolyte from a reservoir for electrolyte, the base of which is a flange of stainless steel attached mechanically, and the net of flexible corrosion-resistant non-conducting material, for instance, caprone, is attached to the wall of corrosion-resistant current-conducting material.
EFFECT: invention makes it possible to decontaminate bent surfaces.
FIELD: power engineering.
SUBSTANCE: method includes a counterflow treatment of a uranium-plutonium extract with an aqueous solution of a reducing agent that recovers plutonium to low-extractable state Pu (III), carried out in two subsequent stages. The first of them is carried out at the ratio of organic and water phase flows, O:W, from 25 to 50, and an aqueous plutonium containing solution produced as a result is taken out from the extraction cycle, and the second one is carried out at O:W from 7 to 15, in the solution produced accordingly the excessive reducing agent is destroyed, and Pu (III) is oxidizer to Pu (IV), afterwards the solution is returned to the extraction cycle into the area that precedes the first stage of separation.
EFFECT: higher content of plutonium in the flow taken from the extraction cycle to further recycling, and reduced content of plutonium in the uranium product.
5 cl, 4 tbl, 2 dwg
FIELD: power engineering.
SUBSTANCE: gel for surface cleaning contains a colloid solution of the following composition: inorganic modifier of viscosity in the amount of 5-25 wt % of the total mass of gel; surfactants in the amount of less than 0.1 wt %, preferably in the amount from 0.01 to less than 0.1 wt % of the total mass of the gel; inorganic acid or base with concentration of 0.5-7 mole per litre of gel; optionally an oxidant with standard redox potential E0 of more than 1.4 V in a strong-acid medium or a reduced form of this oxidant with concentration of 0.05 - 1 mole per litre of gel; water - balance; besides, the specified gel after complete drying within 2-72 hours at the temperature of 10-30°C and relative moisture of 20-70% is a solid dry residue. There is also a method to decontaminate surfaces and to apply gel.
EFFECT: group of inventions makes it possible to improve available gel for surface cleaning and methods of its application.
22 cl, 5 dwg, 6 ex, 1 tbl
SUBSTANCE: plant comprises a cathode device made from a corrosion-resistant current-conductive material, for instance, stainless steel, in the form of a rectangular tight hollow vessel, the base of which is a rectangular flange of stainless steel, at the outer side of which there is a rubber gasket tightly fixed, in the vessel there is at least one nozzle to supply electrolyte from a reservoir for electrolyte and a nozzle to vacuumise the cavity of the rectangular tight hollow vessel of the cathode device, to remove sludge and electrolyte; current conductors with negative and positive poles of a current source; a reservoir for electrolyte; a pump, which is vacuum; a collector for electrolyte, serving to accumulate and return electrolyte into the reservoir for electrolyte, which represents a tight reservoir from stainless steel, equipped with a ball valve in the lower part to drain sludge and a level meter; a spray trap made in the form of a tight reservoir from stainless steel, in the upper part of which there is a vacuum meter, besides, all elements of the plant are mounted on a movable platform.
EFFECT: higher safety of decontamination process for maintenance personnel and environment and increased efficiency of decontamination.
2 dwg, 1 tbl
SUBSTANCE: method of producing actinide nitrates involves treatment of actinides or compounds thereof with nitrogen tetraoxide in the presence of water. Nitrogen tetraoxide is fed into a reaction vessel in a mixture with air or oxygen and the process takes place at normal pressure and temperature from 25°C to 95°C.
EFFECT: invention provides easy conversion of actinide compounds into nitrates, which increases utilisation factor of nitrogen oxides, thereby reducing their emission into the atmosphere.
3 cl, 3 tbl, 3 ex
FIELD: power industry.
SUBSTANCE: fixation method of radioactive cesium isotopes at heat treatment of radioactive wastes (RW) involves preparation of the charge containing graphite, including 14C isotope, titanium dioxide, thermit mixture, as well as up to 25 wt % RW. Charge is mixed, loaded to tight reactor or container; above the main layer of charge there placed is additional layer of natural zirconium isotope with thickness of 1/6 thickness of the main charge layer or oxide of natural isotopes of silicon, titanium, aluminium and iron, with thickness of 1/5 to 1/3 of thickness of the main charge layer; and charge is heat treated.
EFFECT: possibility of performing high-temperature heat treatment of multi-component mixtures containing high-active RW including graphite-containing RW, with complete fixation of cesium evaporating during mixture heat treatment.
2 cl, 3 ex
FIELD: process engineering.
SUBSTANCE: installation for removal of liquid radioactive wastes (LRW) from temporary storage reservoirs comprises floating platform arranged there inside and composed of a tank equipped with system of ultrasound radiators connected with ultrasound oscillation generator and remote control system. Said ultrasound radiators are regularly arranged on floating platform walls and bottom to disperse and dissolve the sediments and to displace the platform in preset direction. Installation is equipped with LRW lifting and discharging system comprising pump and pipelined and remote control and observation system. Besides, said installation is integrated with LRS treatment unit.
EFFECT: higher efficiency and safety.
11 cl, 2 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to environmental protection against liquid radioactive wastes (LRW) that make byproducts of used nuclear fuel treatment or other industrial activities. Proposed method comprises converting LRW components into solid phase by processing them with silicon-bearing compounds of geothermal origin at 5-60°C. Dispersions of silicon dioxide spherulites are used as a hardener and produced by membrane concentration of natural geothermal solution, spherulite diameter making 4-150 nm at silicon dioxide concentration not lower than 105 g/kg, using microfibers from inorganic oxides, for example, basalt used in amounts of 0.5-5 wt % silicon dioxide dispersion weight.
EFFECT: higher safety.
4 dwg, 8 ex, 2 tbl
SUBSTANCE: disclosed is material which contains polyazacycloalkane which is grafted on polypropylene fibre, a method of producing said material and a method of removing metal cations from a liquid by bringing said liquid into contact with said material.
EFFECT: disclosed material combines excellent selectivity of binding heavy metals, lanthanides or actinides with excellent operational characteristics.
55 cl, 6 dwg, 9 tbl, 8 ex
SUBSTANCE: method of processing spent ion-exchange resins contaminated with radioactive elements involves wet grinding of resin grains to particle size 1-45 mcm, adding alkali to the obtained suspension to pH 10.5-11.0, liquid-phase oxidation of the suspension while feeding air into the oxidation zone under conditions of supercritical state of water at temperature 450-550°C and pressure 230-250 atm, removing gaseous oxidation products in form of CO2 and N2, separating the solid and liquid phases by filtering and subsequent deactivation of the liquid phase.
EFFECT: invention enables to reduce the volume of radioactive wastes for permanent storage, is characterised by absence of secondary gaseous wastes and does not require use of aggressive chemicals.
5 cl, 1 ex, 1 tbl
SUBSTANCE: method of processing a radioactive solution involves the following. First, an iron (III) compound in form of chloride or sulphate is added to the solution in amount of 0.04-0.05 mol/l to form an iron-containing precipitate. At the first step, a minimum amount of mineral acid - hydrochloric or sulphuric acid - is added, and at the second step 0.18-0.24 g-eq/l of the corresponding acid is added to the solution. The solution is held for not less than 120 hours at room temperature or not less than 18 hours at 70-95°C and sodium sulphide is added to the solution in a molar amount which is 1.5 times greater than the amount of the added iron (III) compound to form a basic collective precipitate of radionuclides of cobalt and caesium and a mother solution containing an organic complexing agent and a residual amount of radionuclides of cobalt and caesium. The mother solution is subjected to a post-treatment cycle by adding an iron (III) compound in amount of 0.02-0.04 mol/l with respect to iron (III) and mineral acid in an amount which is equivalent to content of sodium in the added sodium sulphide, holding the obtained mother solution and adding additional sodium sulphide in molar amount which is 1.5 times greater than the amount of the additionally added iron (III) to form an additional collective precipitate of the post-treated mother solution.
EFFECT: invention enables to increase processability of the method by replacing oxidation of the organic complexing agent with cationic substitution of the cobalt radionuclide therein, reduce the amount of reagents used while ensuring high degree of purification of solutions.
6 cl, 4 ex
FIELD: power industry.
SUBSTANCE: water treatment method of natural or artificial water reservoir from radioactive isotopes and harmful chemical substances involves the intake of source water, its pre-treatment and the main treatment by two-stage reverse osmosis so that filtrate is obtained, which is supplied to consumer as treated water and concentrate returned to water reservoir. Combined concentrate obtained at the stage of pre-treatment and the first stage of reverse osmosis is returned to water reservoir, and concentrate obtained at the second stage of reverse osmosis is supplied to the first stage of reverse osmosis.
EFFECT: invention allows improving the efficiency of treatment procedure and reducing the amount of secondary wastes.
6 cl, 1 dwg, 1 ex, 1 tbl
FIELD: water treatment.
SUBSTANCE: innovation relates to the chemical treatment of industrial and domestic wastewaters containing lubricating and cooling fluids, radioactive contaminating substances, washing solutions, ions of heavy metals; the method includes the decontamination and demulsification of wastewater by the mixture of ferrous chloride (FeCl3), calcium chloride (СаСl2) and permanganate of alkalic or the mixture of alkaline-earth metals at the mass ratio of (1/2):(0.15/0.2):(0.01/0.02) on conversion to arid salts and volume concentration of 1-3% of the initial solution, рН counts to 5-6.
EFFECT: innovation enhances the efficiency of wastewater purification.
1 cl, 5 tbl
FIELD: power industry.
SUBSTANCE: processing method of low-mineralised liquid radioactive wastes involves filtration through selective ferrocyanide absorbent, and then through ion exchange absorbents. Absorbent is obtained by sequential processing of organic carrier with solutions of potassium ferrocyanide and nickel salts with excess content of each reagent. As organic carrier for obtaining selective ferrocyanide absorbent there used is saw dust pre-dried at temperature of 105-110°C with sizes of 1-4 mm. At that, nickel-potassium ferrocyanide is synthesised immediately in structure of saw dust. Used radioactive ferrocyanide absorbent is burnt. Ash residue is added to cement compound as binding agent.
EFFECT: invention allows increasing by more than 10 times the capacities of selective ferrocyanide absorbent on the basis of pre-dried saw dust in comparison to application of nickel-potassium ferrocyanide to ion exchange resins; increasing operational life of sorption filters; cheapening of preparation technology of selective absorbent and reducing the volume of secondary disposed radioactive wastes.
SUBSTANCE: invention relates to the technology of decontaminating liquid radioactive wastes using a membrane-sorption method in field conditions. The method of decontaminating low-mineralised low-activity liquid radioactive wastes is realised through cleaning on mechanical and ultra-filters, desalination on reverse-osmosis filters and post-cleaning on ionite filters with post-evaporation of the formed radioactive concentrates until salt saturation at temperature lower than 100°C in a container and subsequent addition of the saturated salt concentrates to portland cement. Also, wastes are cleaned from radio nuclides on filters using selective sorbents with protection from ionising radiation. Post-evaporation of concentrates from reverse-osmosis filters is carried out at atmospheric pressure in a container. The condensate from the evaporation apparatus is returned to the ultra-filters. The concentrate from the ultra-filters is returned to the mechanical filters. Initial radioactive concentrates with beta-radiating nuclides specific activity greater than 0.1 MBq/kg and/or radioactive concentrates with specific activity greater than 0.1 MBq/kg before evaporation are directed to the selective sorbent filters.
EFFECT: more efficient removal of radionuclides even without using selective sorbent filters.
1 dwg, 4 ex
FIELD: power industry.
SUBSTANCE: thermochemical treatment of resins is performed in salt fusion diluted with sulphuric acid in three stages at temperatures of 100-150°C, 150-250°C and 250-350°C and at atmospheric pressure in the device, in conditions of free air access to reaction zone, at constant or periodic mixing of the product in the device, and final solidification of the obtained dry product is performed by means of binding agents of phosphate hardening (natural minerals or wastes of industrial enterprises, which contain metal oxides).
EFFECT: maximum possible decrease of volume and weight of solid radioactive wastes, simplifying the technology and reducing power consumption.
2 cl, 2 ex
FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.
SUBSTANCE: proposed method that can be used for deactivating and decontaminating industrial radioactive wastes incorporating Tb-232 and their daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Sl, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like includes dissolution of wastes, treatment of solutions or pulps with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9 - 10 in the amount of 120-150% of total content of metal oxyhydrates stoichiometrically required for precipitation, pulp is filtered, and barium chloride in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp, as well as pre-diluted sulfuric acid spent 5 - 20 times in chlorine compressors in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2 are introduced in filtrate. Alternately introduced in sulfate pulp formed in the process are lime milk to pH = 11 - 12, then acid chloride wash effluents from equipment and industrial flats at pulp-to-effluents ratio of 1 : (2 - 3) to pH = 6.5 - 8.5, and pulp obtained is filtered. Decontaminated solution is discharged to sewerage system and sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization process; then 35 - 45 mass percent of inert filler, 10 - 20 mass percent of magnesium oxide, and 15 -m 25 mass percent of magnesium chloride are introduced in pasty mixture formed in the process while continuously stirring ingredients. Compound obtained is subjected to heat treatment at temperature of 80 - 120 oC and compressed by applying pressure of 60 to 80 at.
EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.
7 c, 1 ex