Method of controlling uranium content in process media of nuclear power plants

FIELD: physics.

SUBSTANCE: invention relates to safe operation of nuclear power plants. Content of uranium in process media of nuclear power plants is controlled as follows: collecting a sample of the process medium, alkanising said sample to pH 9-11 by adding ammonia, filtering through a cellulose acetate membrane with freshly deposited manganese dioxide, dissolving the membrane with manganese dioxide in hydrochloric acid while boiling, reducing uranium with ascorbic acid and zinc metal to oxidation state IV, and then determining content of uranium in the solution using a photometric method using arsenazo III in a chloride medium.

EFFECT: simple and faster control, lowering the uranium detection limit 40-fold.

 

The invention relates to the field of analytical radiochemistry and ensure the safe operation of nuclear power plants (NPP).

Uranium, which is the basis of nuclear fuel, appears in technological environments NPU tightness teplovidelyaushaya elements (Fe). When loading of the reactor pressure vessels is considered acceptable having not more than 0.1% leakage of fuel rods [Nikiforov A.S., Kulichenko CENTURIES, Zhikharev M.I. Disposal of liquid radioactive waste. - M., 1985, p.6-7]. In the initial period of operation of the NPP (prior to the accumulation of fission products) this leakage causes the coolant only uranium. Therefore, control of the concentration of uranium in technological environments NPU provides security installations at all stages of their operation.

The most common method for determination of uranium in solution is its early separation from impurities by extraction, ion exchange or precipitation followed by measuring the concentration of uranium photometric method using a dye complexing agents (thiocyanate, dibenzoylmethane, arsenazo) [Marchenko Z.K. photometric determination of elements. - M., Mir, Moscow, 1971. S-426].

Thus, the known method of separating uranium by extraction him from nitric acid solutions of oxygen-containing solvent and, mainly ethers or esters and ketones with subsequent photometric its definition using thiocyanate [Marchenko Z.K. photometric determination of elements. - M., Mir, Moscow, 1971, s, 416-417].

The disadvantages of the extraction method are the use of harmful and flammable organic solvents, the duration of the extraction process, as well as the fact that the method using thiocyanate, lack sensitivity, are used primarily for the determination of uranium in ores and concentrates with a relatively high content.

Also known sorption method for isolating uranium on anion-exchange resins in the form of anionic complexes from solutions of nitric, hydrochloric or acetic acid in a mixture with organic solvents such as methanol, ethanol, acetone, ether, dioxane and other miscible with water solvents with subsequent elution of uranium and photometric its definition using dibenzoylmethane [Marchenko Z.K. photometric determination of elements. - M., Mir, Moscow, 1971, s, 418].

The main disadvantages of this method are the same as in the extraction and, despite the higher sensitivity dibenzoylmethane, it is used mainly in the analysis of uranium ores and minerals.

Hardware the most simple method of separating uranium from when the Yessei is sedimentation in alkaline medium using ammonium carbonate and svezheosazhdennoi manganese dioxide (Mno 2) [Marchenko Z.K. photometric determination of elements. -M., Mir, Moscow, 1971, s], and the most sensitive photometric measurement method using arsenazo I, in a weak alkaline medium or arsenazo III in a very acidic [Marchenko 3. K. photometric determination of elements. - M., Mir, Moscow, 1971, s-421], which allows to define and small concentrations of uranium in technological environments NPU. This method is in its essence and the achieved technical result closest to the proposed and selected as a prototype.

The disadvantage of this method is that the precipitation of the uranium separation requires two deposition (resultant deposition rates) and subsequent long-term evaporation of the filtrate to achieve the original sample volume, which excludes the speed control, which is especially important for technological environments NPU. In addition, the detection limit of uranium in solution in this case is ~ 50 µg/L.

The problem solved by this invention is to simplify and increase the efficiency of control, the lower detection limit uranium.

The technical result of the invention is to reduce the detection limit of uranium in technological environments NPU and increase the efficiency of the control.

The invention consists in that in the method of controlling the concentration of uranium in the breadboard is x environments, NPU, including sampling, separation of uranium by precipitation in an alkaline medium using ammonium compounds and svezheosazhdennoi manganese dioxide (Mno2), dissolving the precipitate in hot hydrochloric acid (Hcl) and determination of uranium in solution photometric method using arsenazo III in hydrochloric acid medium, according to the invention the alkaline environment of the sample is created by adding ammonia, and Mno2deposited on cellulose acetate membrane, through which is then filtered sample, then the membrane with Mno2soluble in model HC1 boiling, after cooling the solution, the uranium is recovered ascorbic acid and metallic zinc to the oxidation state IV, and then measuring the concentration of uranium in hydrochloric acid solution by the photometric method.

Compared with the known methods used for control of the concentration of uranium in technological environments NPU, the use according to the invention acutally-Loozen membranes, which first applied svezheosazhdennoi Mno2which then after filtering, the sample is dissolved together with the membrane in hydrochloric acid, provides an efficient preconcentration and subsequent reliable determination of uranium in cellulose acetate environment, which is not obvious from the prior art, as the method - prototype Mno2use the nose to separate uranium from impurities [Marchenko Z.K. Photometric determination of elements. - M., Mir, Moscow, 1971, s], and, therefore, the claimed method meets the criterion of inventive step.

The method is as follows.

A sample of the technological media NPU alkalinized by addition of ammonia to a pH of 9-11 and filtered through a cellulose acetate membrane with svezheosazhdennoi manganese dioxide (Mno2). MnO2applied to the membrane by immersing it in a 0.4 M solution of permanganate potassium (KMPO4within 10-20 seconds. After filtration of the sample membrane with Mno2dissolved in 4 M Hcl solution by boiling. The cooled solution in terms of 1 liter add ~5 g of ascorbic acid and 2 g of metallic zinc to recover uranium oxidation state IV. After soaking and mixing make a 0.05% solution of arsenazo III and measure the absorbance at 655 nm (red filter) relative to the blank sample, which uses the product of the dissolution of the cellulose acetate membrane with svezheosazhdennoi Mno2without uranium.

Since the detection limit of uranium in the solution subjected to photometric analysis of ~ 50 ág/l, the actual detection limit depends on the volume of sample filtered through cellulose acetate membrane with svezheosazhdennoi Mno2.

Examples of specific performance.

Example 1 (Prototype). The sample t is logical environments NPU volume of 25 ml with a uranium content of 50 µg/l was podslushivaet ammonium carbonate to a pH of 11, added KMPO4for translation of uranium in oxidation state VI, and then a small amount of alcohol for the recovery of excess KMPO4to Mno2and heated to precipitate as carbonates or hydroxides of most of the impurity of heavy metals. The ions of uranium formed soluble carbonate complexes. The reaction mixture was filtered and the precipitate washed with 1% soda solution. Then it was dissolved in hot 4 M Hcl and again precipitated with ammonium carbonate. The combined filtrates were acidified using Hcl and evaporated to the volume of the original sample. The duration of sample preparation was not less than 4 hours.

To one stripped off, the filtrate was added 0.05% solution of arsenazo III, was transferred to a volumetric flask of 50 cm3drove up to the mark with 4 M Hcl and measured the absorbance at 655 nm against blank experience. The measurement error was less than ±30% at a confidence level of 0.95.

Example 2 (the proposed method). Differs from example 1 in that a sample with a uranium content of 1 µg/l in a volume of 1 l was podslushivaet ammonia and then filtered through cellulose acetate membrane "Vladipor" with a pore size of 0.3-0.9 μm (diameter 35 mm) with svezheosazhdennoi Mno2under the pressure of 0.4 MPa. After filtration of the sample membrane was washed with distilled water. Then the membrane with Mno2was dissolved in 25 ml of 4 M solution of Hcl at boiling. Prod is littelest sample preparation by filtration through a membrane under pressure does not exceed 2 hours. The cooled solution was added ~150 mg of ascorbic acid and 2 g of metallic zinc to recover uranium oxidation state IV. After soaking and stirring was made a 0.05% solution of arsenazo III and measured the absorbance at 655 nm (red filter) relative to the blank sample, which used the product dissolving cellulose acetate membrane with svezheosazhdennoi Mno2without uranium. The measurement error was less than ±30% at a confidence level of 0.95.

The proposed method is compared with the prototype provides improved detection limit of uranium in solution in 40 times. The duration of the process of sample preparation is reduced in 2 times at a much lower intensity.

In the proposed method uses the same reagents produced on an industrial scale, as in the prototype. Thus, the proposed method is industrially applicable.

The method of controlling the concentration of uranium in the technological environments of nuclear power plants, including sampling technological environment, the separation of the uranium by precipitation in an alkaline medium using ammonium compounds and svezheosazhdennoi manganese dioxide, dissolving the precipitate in hot hydrochloric acid and the determination of uranium in solution photometric method using ARS is the naso III in hydrochloric acid medium, characterized in that the alkaline environment of the sample created by adding ammonia, manganese dioxide precipitated on cellulose acetate membrane, through which the filtered sample, then the membrane from the precipitated manganese dioxide is dissolved in hydrochloric acid at boiling and subsequent cooling of the solution, and the uranium before control of its content in the solution restore ascorbic acid and metallic zinc to the oxidation state IV.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: radionuclides and toxic metal ions are removed from water using sorbents in form of gaize crumbs with diameter of 20-50 mm.

EFFECT: invention enables to avoid intermediate operations and use of deactivating substances.

FIELD: power engineering.

SUBSTANCE: method to decontaminate liquid wastes containing one or several radioactive chemical elements to be removed, including the following stages: the stage of putting in contact the liquid wastes with the solid particles in the first reactor; the stage of suspension settling in the second reactor, as a result of which the solid phase is produced, and the liquid phase; the stage of separation of the specified solid phase and the specified liquid phase, a part of the specified solid phase produced after the stage of settling is repeatedly sent into the first reactor for realisation of the stage of putting in contact.

EFFECT: invention makes it possible to improve efficiency of decontamination.

6 cl, 1 dwg

FIELD: power engineering.

SUBSTANCE: invention relates to the technology of handling liquid radioactive wastes (LRW) of nuclear power plants (NPP) and may be used in process of recycling of floor drains and still bottoms of NPP LRW for removal of the radio nuclide 60Co with its concentration in the solid phase. The method to extract the radionuclide 60Co from liquid radioactive wastes of the NPP includes introduction of iron cations (III) and nickel cations (II) into the solution at the mole ratio of 1:1 and potassium ferrocyanide at the mole ratio with iron cations (III) from 2:1 to 4:1.

EFFECT: invention makes it possible to simpligy the process of extraction of radionuclide 60Co from NPP LRW, to reduce time of its performance.

FIELD: chemistry.

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

FIELD: chemistry.

SUBSTANCE: method of determining specific activity of radionuclides in low-activity and waste mineralised water involves filtration thereof through a sorbent layer containing a heavy metal ferrocyanide, a heavy metal sulphide and a strontium sorbent with extraction of radionuclides thereon and subsequent spectrometric analysis of said radionuclides. An anion-exchange resin is also added to the sorbent containing a heavy metal ferrocyanide and a heavy metal sulphide. The sulphate obtained after passing water through the three-component sorbent is further filtered through a strontium sorbent layer which is in form of a cation-exchange resin. Gamma-spectrometric determination of specific activity of radionuclides sorbed on the three-component sorbent is carried out. Determination of the specific activity of radionuclides sorbed on the cation-exchange resin is carried out via radiometric measurement of their total β-activity in an eluate.

EFFECT: high accuracy of determining specific activity of γ-emitting radionuclides and easy determination of specific activity of γ- and β-emitting radionuclides in low-activity and waste mineralised water.

2 cl

FIELD: power engineering.

SUBSTANCE: method to decontaminate spent ion-exchange resin, including changeover of radionuclides sorbed on the ion-exchange resin into a solution of acid sodium salts, treatment of a decontaminating solution from caesium radionuclides on a composite ferrocyanide sorbent and pH correction. Prior to treatment of the decontaminating solution from caesium radionuclides, the solution is treated from cobalt radionuclides by addition of alkali to the range of pH 2.5÷11.7 and co-deposition of cobalt radionuclides with oxides of ferrum (III), desorbed from the ion-exchange resin, with subsequent separation of residue. The treated decontaminating solution is returned into a reservoir of an initial solution. The pH value is corrected to 0.5-4.0 by addition of mineral acids, and the solution is used repeatedly for decontamination of fresh portion of the spent ion-exchange resin.

EFFECT: invention makes it possible to reduce volume of radioactive wastes subject to burial or controlled storage due to higher efficiency of decontamination of radionuclides and higher efficiency of decontaminating solution treatment by selective methods.

1 dwg

FIELD: power industry.

SUBSTANCE: treatment method of radioactive solutions containing plutonium and americium involves pH correction of base solutions, phase separation by filtration. In order to remove plutonium and americium from medium active waste, two-layer pH correction of the solution is used: the first one to pH=(3.5±0.5) at mixing (25±5) min till primary flocculi are formed; the second one to pH=(8.4±0.2) for deposition of plutonium and americium on deposits of hydroxides; thickened suspension is washed for three times with water at volume ratio of pulp:water of 1:3; decantats (filtrates) and intermediate waters are supply for treatment as per low active waste cleaning procedure; thickened suspension is heat treated at temperature of not more than 850°C so that calcification is obtained, which is supplied either to "temporary" storage for the purpose of removing valuable elements fro it in the future, or to solidification in the form of mineral-shaped matrixes (ferro-silicate, Sinroc-C, etc.), which are suitable for long-term disposal.

EFFECT: invention allows simplifying and cheapening the technological process of medium active waste processing and simplifying the treatment of water-tail solutions.

1 tbl

FIELD: power industry.

SUBSTANCE: processing method of liquid radioactive wastes of low level involves preparation of charge by adding the sorbent to liquid radioactive wastes, separation with further separation of wastes. Hydrophobic carbon sorbent is used as sorbent; at that, after addition of sorbent to wastes there crushed is solid phase of charge to degree of dispersion of 0.9-1.0 mcm, and then after powder drying the briquette is pressed and granulated to globules. At that, separation is performed with microplasma processing at constant mixing of globules in processing zone; then, the obtained gaseous products are subject to processing with "cold hydrogen oxidation" method, and solid precipitation of radioactive elements is compacted to briquettes.

EFFECT: invention allows more effective removal of active components from liquid wastes with simultaneous obtaining of water, electric power and encapsulated active residues.

5 cl, 3 ex

FIELD: power industry.

SUBSTANCE: method involves water filtration through loading of granulated ferrocyanide-containing sorbent; sorbent includes 0.2-2 wt % of hydrazine, 35-48 wt % of water and 20-35 wt % of nickel ferrocyanide; composition Me(I)4-2x[NixFe(CN)6], where Me(I) - Li+, Na+, K+, NH4+ or their mixture, x=1.2-1.8, the rest is zirconium hydroxide. Size of composite sorbent granules is 0.05-1.5 mm.

EFFECT: increasing cleaning coefficient and operational life of sorption loading.

FIELD: power industry.

SUBSTANCE: after equipment decontamination by acetic acid solutions containing oxygen, and stechiometric ortho-phosphoric and sulphuric acid or ortho-phosphoric excess is introduced into liquid radioactive waste (LRW) solution. After that resulting heterogenous product is subjected to thermal treatment under the temperature of 100-120°C. Acetic acid condensate is returned into decontamination process flow, and produced by heat treatment salt concentrates are embeded using traditional binding materials or phosphatic hardening materials as matrices.

EFFECT: process simplification of equipment deactivation and LRW decontamination, reducing consumption of chemical agents and radioactive wastes volume during deactivation, increasing the extent of salts introduction into suggested matrices, quality of hardened products and reliability of their long-term storage, improvement of ecological situation in the places of long-term storage of radioactive wastes.

4 cl

FIELD: recovery of liquid radioactive wastes.

SUBSTANCE: proposed method includes bringing liquid radioactive wastes in contact with matrix saturated with selective ion-exchange material (solid extracting agent). Glass-crystal material with open porous structure is used as matrix for the purpose. Matrix material is produced from hollow glass-crystal cene spheres formed from mineral particles of volatile ash produced as result of black coal combustion and saturated with selective ion-exchange material.

EFFECT: facilitated procedure of radionuclide extraction.

5 cl, 1 tbl, 5 ex

FIELD: recovery of liquid radioactive wastes.

SUBSTANCE: proposed method includes treatment of radioactive wastes by heavy-metal ferrocyanide and separation of sediment obtained. In the process liquid radioactive wastes are treated with heavy-metal ferrocyanide formed upon introduction of potassium ferrocyanide and bivalent nickel and/or copper and iron salts taken in amount abundant with respect to stoichiometric quantity. Clarified solution is treated with oxidant upon separation of sediment and filtered through catalytic material containing manganese dioxide. Then filtered-off solution is passed through highly acid cationite in Na-form and highly basic anionite in Cl-form.

EFFECT: enhanced decontamination quality.

5 cl, 1 tbl, 7 ex

FIELD: reactive sorbents.

SUBSTANCE: liquid is conditioned at pH 4-6 and then is brought into contact with chelating ion-exchange resin composed of grafted polyazocycloalkanes at temperature above or equal to 60°C.

EFFECT: enhanced metal removal efficiency.

35 ex, 9 dwg, 9 tbl, 5 ex

FIELD: processing of liquid radioactive wastes.

SUBSTANCE: the proposed method for cleaning of liquid radioactive wastes includes their processing with absorber-sorbent. Ash wastes are used as the absorber-sorbent. The ash wastes are introduced into liquid radioactive wastes in the stage of their neutralization at pH = 0.5-2 at the flow rate, ensuring the ratio of S : L = 1 : (15-50). Then the obtained suspension is separated into the liquid and solid phases.

EFFECT: increased degree of cleaning from radionuclides and enhanced separation rate of produced pulps.

4 cl, 1 tbl, 11 ex

FIELD: medicine.

SUBSTANCE: invention relates to application of pectin solution as detergent for skin and hair in radioactive and environmentally hazardous regions. Pectin containing in solution due to chelating action bonds to heavy metal ions to form stable compounds (micelles) having very large size and prevents transferring thereof trough transdermal barrier. Formed micells may be easily removed from human body.

EFFECT: new detergent for skin and hair useful in radioactive and environmentally hazardous regions.

2 ex, 5 tbl

FIELD: methods of the sorption decontamination of waters from the radioactive impurities.

SUBSTANCE: the invention is pertaining to the method of the sorption decontamination of waters from the radioactive impurities. The method of decontamination of the water from radiostrontium includes the treatment of the water with a sorbent based on the burned bauxite ore. At that the ore is burned together with calcium -magnesium lime - CaCO3·MgCO3 and sodium soda salt - Na2CO3 at the temperature of no less than 1200°C and flushed with the water to remove the solvable sodium compounds. It is preferable, that the mixture of the bauxite ore is subjected to burning with calcium-magnesium lime and sodium soda salt in the mass ratio of 1 : 0.55-0.60 : 0.055-0.060. The method ensures an increased effectiveness of removal of the radiostrontium at usage of the initial bauxite ore without lowering of effectiveness of the water decontamination from radiocesium, and also allows to reduce considerably the amount of the spent sorbents, which are subjected to disposal.

EFFECT: the invention ensures an increased effectiveness of removal of radiostrontium from the water at usage of the initial bauxite ore without lowering of effectiveness of the water decontamination from radiocesium, allows to reduce considerably the amount of the spent sorbents, which are subjected to disposal.

2 cl, 10 ex

FIELD: environment control including environment protection in atomic industry.

SUBSTANCE: proposed method for decontaminating radioactive aqueous solutions from radionuclides includes at least one contact of solution with complexing sorbent that has solid-medium immobilized active polymeric layer condensed with chelates. Medium is chosen from following group: activated cellulose; synthetic copolymers with divinyl benzene, activated chloromethyl or hydroxymethyl, or chlorosulfonic groups. Active sorbing layer has ethylenediamine or diethylene tridiamine, or tetraethylene pentaamine, or polyethylene polyamine with copolymers; chelates are chosen from group incorporating carboxyl-containing chelates, phosphonic-group chelates, and hydroxyl-containing chelates. Proposed method enables extraction of radionuclides both in ionic and colloidal condition from solutions doped with highly concentrated impurities; sorbent used for the purpose retains its sorbing properties upon repeated regenerations and is capable of decontaminating solutions both in dynamic and static modes with different pH of solutions being decontaminated.

EFFECT: enlarged functional capabilities.

11 cl, 3 tbl

FIELD: technology of handling of the liquid nuclear wastes of the nuclear fuel and power cycle; methods of reprocessing of the liquid nuclear wastes.

SUBSTANCE: the invention is pertaining to the procedure of the liquid nuclear wastes handling of the nuclear fuel and power cycle and may be used during reprocessing of the liquid nuclear wastes (LNW). The method includes the preliminary concentration, ozonization, microfiltration of the vat residue with fractionation of the permeate and the concentrate and the ion-selective purification of the permeate using the ion-selective a sorbent. At that the microfiltration is conducted at least in two stages: the permeate of each previous stage of the microfiltration is directed to the microfiltration as the source solution for the subsequent stage of the microfiltration, and at the final stage of the permeate from the microfiltration is sent to the utilization. The concentrate produced at each next stage of the microfiltration is mixed with the source solution of the previous stage of the microfiltration. The concentrate produced at the first stage of the microfiltration is directed to the conditioning and dumping. The ion-selective sorbent is added in the permeate of the previous stage of the microfiltration before the final stage of the microfiltration. The invention ensures: reduction of the volume of the liquid nuclear wastes due to the deep purification of the LNW with the high saline share from the radionuclides and extraction of the radionuclides in the compact form of the sparingly soluble compounds at the corresponding increase of the factor of purification of the salts extracted at the stage of the vat residue treatment; reduction and optimization of the consumption of the permeate and concentrate interacting with the source solution as well as produced at the further stages.

EFFECT: the invention ensures: reduction of the volume of the liquid nuclear wastes; the deep purification of the LNW with the high saline share from the radionuclides and extraction of the radionuclides in the compact form of the sparingly soluble compounds at the corresponding increase of the factor of purification of the salts extracted at the stage of the vat resudue treatment; reduction and optimization of the consumption of the permeate and concentrate interacting with the source solution ands produced at the further stages.

FIELD: nuclear-industry radiochemical enterprises for recovering and immobilizing gaseous radioactive wastes.

SUBSTANCE: sorbent used for entrapping radioactive iodine from gas-aerosol stream running from irradiated nuclear fuel cutting-and-dissolving unit has porous base impregnated with nitric acid silver salt (AgNO3); used as sorbent base is porous silicon carbide of 30 to 60% porosity.

EFFECT: enhanced corrosion and mechanical resistance of material in chemically active media.

1 cl, 2 dwg, 3 tbl

FIELD: environmental protection.

SUBSTANCE: invention relates to means and methods of integrated degassing, disinfection, and shielding of sites and zones, where presence of high-activity poisonous substances, poison-gases, chemical weapons, pathogenic microorganisms, their vital activity toxic products, insects (including carriers of human and animal diseases), radioactive substances are revealed or suspected, and also to means and methods to extinguish burning of inflammable liquids and to prevent in inflammation of spills of inflammable liquids. Multifunctional foam composition of invention includes, as active substance, 0.1-5% of didecyldimethylammonium halide clatrate with urea. Use of indicated clatrate provides simultaneous effect of foam compositions, wherein clatrate acts both as multifunctional active substance and as foaming agent. Invention can further be used to eliminate consequences of use of weapons of mass destruction and to eliminate consequences of man-made accidents and emergency situations.

EFFECT: expanded protection possibilities.

24 cl, 3 tbl, 6 ex

Up!