Method of selective extraction of radionuclides from radioactive nitric acid solutions (versions)

FIELD: chemistry.

SUBSTANCE: invention relates to radiochemical technology and can be used in production of "reactor" 99Mo as a generator of 99mTc of a biomedical purpose, as well as in an analysis of technological solutions for preliminary separation of Mo or Mo and Zr in extraction reprocessing of solutions of technology of spent nuclear fuel of nuclear power plants (NPP SNF). Described are versions of methods of selective extractive separation of a considerable part of molybdenum or together molybdenum and zirconium from radioactive solutions with obtaining an extract. A reprocessed radioactive solution is processed with an extractant, which represents poorly soluble in a water phase alcohol, in the presence of an extracted complexing agent. As the complexing agent, hydroxamic acids with a number of carbon atoms 6-12 can be used, which ensures sufficiently complete extraction of molybdenum and zirconium in an organic phase. Molybdenum or molybdenum and zirconium are separated from the extract in the compact form by sublimation or re-extraction.

EFFECT: obtaining the extract, purified from alpha- and gamma-radioactive admixtures more than by 100 times, and further separate extraction of radionuclides from the extract, combined in the final stage of the process with the extractant regeneration.

17 cl, 2 tbl, 12 ex

 

The invention relates to radiochemical technology and can be used in the production of "reactor"99Mo as generator99mTc biomedical purposes, or clearing the irradiated molybdenum in an alternative way, as well as the analysis of technological solutions for the initial allocation of Mo or Mo and Zr in extraction processing solutions technology of spent nuclear fuel in nuclear power plants (NPP SNF), as well as the chemical analysis of these and other complex high-level solutions.

In irradiated nuclear fuel, except subject to recovery of uranium and plutonium, also contains such fragmentation elements as molybdenum and zirconium. Their presence in the SNF solutions complicates the processing result of the tendency of these elements to sedimentation. The known method of removing molybdenum and zirconium from the high level of raffinate processing of spent nuclear fuel, which consists in heating of the high level of raffinate processing of spent nuclear fuel for complete precipitation of zirconium molybdate [RF Patent №1739784, Bul (1994)]. The disadvantage of this method is its inapplicability to extract trace elements due to their relatively high residual solubility.

In the allocation of molybdenum for medical purposes from irradiated uranium targets b is lsoe importance as the speed of the process, and the degree of purification from other radionuclides. The known method consisting in joint extraction of uranium, zirconium and molybdenum solution of di-ethylhexyloxyphenol acid in the diluent and the subsequent selective Stripping of molybdenum nitrate solution of hydrogen peroxide [Zykov BTW, Codina GE.. radiochemistry, 1999, Vol.41, No. 3, s-204].

The disadvantage of this method is the impossibility of obtaining zirconium product, purified from uranium.

Closest to the claimed solution is how to handle the highly refined from the regeneration fuel NPP (patent Ru 2080666, published. 27.05.97, Bul), lies in the selective extraction of zirconium and molybdenum from radioactive solutions by processing the original solution extractant - TBP in a non-polar diluent, with the introduction of complexing agents, in particular, aliphatic hydroxamic acids, and subsequent isolation of molybdenum, zirconium and complexing agents by treating the organic phase with a solution of an alkaline nature for the preparation of the extractant for re-use. This method is adopted for the prototype.

The main disadvantage of the prototype is the ability of the extractant to extract the uranium, plutonium, technetium from the source solution that makes the method inapplicable for most of the technological solutions due to the presence in them is azannyh elements.

The proposed method solves the problem of selective extraction extraction of a significant part of molybdenum or jointly molybdenum and zirconium from radioactive solutions with obtaining the extract, purified from alpha - and gamma-radioactive impurities more than 100 times, and the subsequent isolation of radionuclides from the extract, combined in the final stage of the process with regeneration of the extractant. As radioactive solutions can be used solutions of SNF processing, solutions of irradiated uranium targets, concentrates of molybdenum for medical purposes.

To achieve the technical result of processed radioactive solution containing 0.1 to 5 mol/l HNO3handle the extractant in the presence of extractable complexing agents, which provides a fairly complete extraction of molybdenum and zirconium in organic phase. As extractant can be used difficultly soluble in the aqueous phase liquid alcohols, and as complexing agents - aromatic hydroxamic acids or aliphatic hydroxamic acids with the number of carbon atoms of 6 to 12. Hydroxamic acids with the number of carbon atoms is less than 6 are water-soluble, and the use of hydroxamic acids with the number of carbon atoms of more than 12, at the stage alkaline treatment the extractant will form hard exfoliating emulsion. The raffinate, purified from zirconium and molybdenum, after oxidation treatment is fed to extraction extraction Chenoweth actinides, if the recovery provided for by the regulation of the production and extract produce molybdenum or molybdenum and zirconium in compact form by sublimation or reextracting. Increasing the temperature during extraction reduces the loss of molybdenum and zirconium with the raffinate. The upper temperature limit of extraction of 70°C is determined by thermal instability of hydroxamic acids at elevated temperature.

After processing of highly radioactive fluids in them until the complete chemical and radiation-chemical destruction remain reductants, a certain amount of dissolved hydroxamic acids and higher alcohols. For directions on extraction processing for accelerated decomposition of impurities introduced substances can be applied accelerated oxidation treatment, in particular heated to 60-80°C with the addition of Cr(VI).

If necessary, a deep cleaning of the extract in a continuous process it is washed 1-2 times (1-2 steps) 0.1 to 4.0 mol/l nitric acid, and the washing solution is added to the raffinate 1 stage process and treated with an extractant which is then used in the first stage. While cleaning pollution is increased by another 10 to 20 times.

Reextraction of radionuclides from the extract for the preparation of the extractant to reuse carried out with a solution of an alkaline nature, such as carbonate solution singly charged cation containing complexing additives, for example diethylenetriaminepentaacetic acid (DTPA), and the selection of radionuclides from the extract is carried out by sublimation of the solvent under reduced pressure, and the temperature of the extract above the boiling point of the extractant. When you separate how to obtain concentrates of Mo and Zr last extravert solution 5-6 mol/l HNO3or to 0.01 mol/l DTPA in 1-2 mol/l HNO3before conducting carbonate Stripping of molybdenum.

In continuous or ongoing process extractant periodically or continuously treated with a solution of 0.1-1 mol/l NaOH to remove the degradation products of the extractant.

In the case of presence in the processed solution a significant amount of oxidants or plutonium(IV), extracted hydroxamic acids, to achieve the technical result of the initial solution is pre-treated with a reducing agent or a reducing agent with extrahieren complexing agents, then adjusted the radioactive solution containing 0.1 to 5 mol/l HNO3handle the extractant in p is outstay extracted complexing agents, that provides a fairly complete extraction of zirconium and molybdenum in the organic phase. As extractant can be used difficultly soluble in the aqueous phase liquid alcohols, and as complexing agents - aromatic hydroxamic acids or aliphatic hydroxamic acids with the number of carbon atoms of 6 to 12. Hydroxamic acids with the number of carbon atoms is less than 6 are water-soluble, and the use of hydroxamic acids with the number of carbon atoms of more than 12, during the alkali treatment of the extractant will be generated hard exfoliating emulsion. The raffinate, purified from zirconium and molybdenum, after oxidation treatment is fed to extraction extraction Chenoweth actinides, if the recovery provided for by the regulation of the production and extract produce molybdenum or molybdenum and zirconium in compact form by sublimation or reextracting. Increasing the temperature during extraction reduces the loss of molybdenum and zirconium with the raffinate. The upper temperature limit of extraction of 70°C is determined by thermal instability of hydroxamic acids at elevated temperature.

When processing the original solution of the reducing agent are well-known ways, for example by treatment with hydrazinehydrate within 1-20 minutes or a mixture of the hydrazine and hydroxylamine [Melent'ev A.B., Maskin A.N., Tugarin O.V., Kolupaev D.N. and other radiochemistry - 2011. - T, No. 2. - P.150-154], restoring not only the plutonium, and technetium(AP). The use of ascorbic acid as a reducing agent causes the simultaneous suppression of the extraction of zirconium.

After processing of highly radioactive fluids in them until the complete chemical and radiation-chemical destruction remain reductants, a certain amount of dissolved hydroxamic acids and higher alcohols. For directions on extraction processing for accelerated decomposition of impurities introduced substances can be applied accelerated oxidation treatment, in particular heated to 60-70°C with the addition of Cr(VI).

If necessary, a deep cleaning of the extract in a continuous process it is washed 1-2 times (1-2 steps) 0.1 to 4.0 mol/l nitric acid, and the washing solution is added to the raffinate 1 stage process and treated with an extractant which is then used in the first stage. While cleaning up of pollution increases even 10-20 times.

Reextraction of radionuclides from the extract for the preparation of the extractant to reuse carried out with a solution of an alkaline nature, such as carbonate solution singly charged cation containing complexing additives, for example diethylenetriaminepentaacetic to the slot (DTPA), and the selection of radionuclides from the extract is carried out by sublimation of the solvent under reduced pressure, and the temperature of the extract above the boiling point of the extractant. When you separate how to obtain concentrates of Mo and Zr last extravert solution 5-6 mol/l HNO3or to 0.01 mol/l DTPA in 1-2 mol/l HNO3before conducting carbonate Stripping of molybdenum.

In continuous or ongoing process extractant periodically or continuously treated with a solution of 0.1-1 mol/l NaOH to remove the degradation products of the extractant.

Example 1.

Model solution the spent nuclear fuel of VVER containing 300 g/l of uranium, 2 mol/l HNO3indicator number241Am and154Eu, as well as molybdenum and zirconium in accordance with a burnup of 40 GW*d/t without pre-treatment with reducing agent and complexing agents have processed extractant - octanol containing 25 g/l benzylhydroxylamine acid for the selective extraction of zirconium and molybdenum. Molybdenum and zirconium extracted in extract more than 99%, with removal of uranium and gamma emitters more than 103. Remaining after selective extraction of zirconium and molybdenum raffinate, was warming at a temperature of 60-80°C, and then transferred to the extraction extraction Chenoweth actinides.

The extract containing the molybdenum and Irani, treated with a solution containing 1 mol/l of methylaminopropane (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo and Zr. The organic phase, not containing these radionuclides was returned for re-use.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH.

Example 2.

Model solution similar to Example 1, was treated with octanol containing 25 g/l benzylhydroxylamine acid for the selective extraction of zirconium and molybdenum at a temperature of 70°C. Remaining after selective extraction of zirconium and molybdenum RapNet, treated with a solution containing Cr(VI) concentration 1 g/l, after which he handed over to extraction extraction Chenoweth actinides.

Next, similarly to Example 1.

Example 3.

The extract containing molybdenum and zirconium, similar to Example 1, was placed in the flask rotary vacuum evaporator (RMA) and at a residual pressure of 25 mm Hg drove the extractant. Distilled the solvent did not contain Mo and Zr, and was returned for re-use.

Example 4.

For separate allocation of molybdenum and zirconium, the extract containing molybdenum and zirconium, similar to Example 1, was treated with a solution of nitric acid of a concentration of 5-6 mol/l is La selective extraction of Zr. After processing in the aqueous phase was discovered more than 99.9% of Zr.

Next, the extract containing only molybdenum, were treated with a solution containing 1 mol/l methylamine carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo. The organic phase, which does not contain the specified radionuclide, was returned for re-use.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH.

Example 5.

For separate allocation of molybdenum and zirconium, the extract containing molybdenum and zirconium, similar to Example 1, was treated with nitric acid solution of DTPA. After processing in the aqueous phase was discovered more than 99.9% of Zr.

Next, similarly to Example 4.

Example 6.

Concentrate fission molybdenum for medical purposes containing 2 mol/l HNO3, 120 mg/l of molybdenum and uranium, the concentration of which in the presence of molybdenum is 2 months (full collapse Mo), were sequentially treated with two portions of octanol-1, containing 15 g/l aprilhydraulic acid. More than 99% of the molybdenum is extracted in the first extract, the remaining amount in the second. In the raffinate after the establishment of the radiation balance within 3 days (99mTc-99TC) was discovered uranium in the amount of 7 ág/L. Molybde is less than 5 µg/L.

The extract was placed in a flask rotary vacuum evaporator (RMA) and at a residual pressure of 25 mm Hg drove the extractant. Distilled the solvent did not contain Mo and was returned for re-use.

Example 7.

The concentrate is similar to Example 6, were sequentially treated with two portions of octanol-2, containing 25 g/l aromatic benzylhydroxylamine acid (BGK). More than 99% of the molybdenum is extracted in the first extract, the remaining amount in the second. In the raffinate after the establishment of the radiation balance within 3 days (99mTc-99TC) was discovered uranium in the amount of 7 ug/l Molybdenum less than 5 µg/L.

The extract containing molybdenum, were treated with a solution containing 1 mol/l methylamine carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo. The organic phase, which does not contain the specified radionuclide, was returned for re-use.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH. The duration of the separation of phases in this operation amounted to 1 minute.

Example 8.

The concentrate is similar to Example 6, were sequentially treated with two portions of octanol-2, containing 25 g/l laurenheartssmiley acid (leaders of Leningrad city Committee). More than 99% of the molybdenum is extracted in the first the second extract, the amount remaining in the second. In the raffinate after the establishment of the radiation balance within 3 days (99mTc-99TC) was discovered uranium in the amount of 7 ug/l Molybdenum less than 5 µg/L.

The extract containing molybdenum, were treated with a solution containing 1 mol/l methylamine carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo. The organic phase, which does not contain the specified radionuclide, was returned for re-use.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH. The duration of the separation of phases in this operation amounted to 15 minutes.

Example 9.

The solution of the spent nuclear fuel of VVER - 1000 with a burnup of 60 GW·d/t HM containing 50 g/l U, and treated with a reducing agent is nitric acid solution hydrazinehydrate, obtaining in the final solution of 0.1 mol/l hydrazine nitrate and 2 mol/l HNO3. Then adjusted the original solution was treated with decanola containing 25 g/l benzylhydroxylamine acid for the selective extraction of zirconium and molybdenum. The extract obtained zirconium and molybdenum and the raffinate was analyzed on the content of the main components. The results are presented in table 1.

Table 1.
ProductThe concentration of the analyzed components
HNO3, mol/lU, g/lPu, mg/lMo, mg/lZr, mg/lΣα, Bq/lΣγ, Bq/l
Adjusted initial solution2of 37.8330140-2,8·10105.2 x 1011
Extract zirconium and molybdenum0,551751843,4·108
The raffinate237,3320 <5<152,8·10105·1011
ProductThe alpha range, % of ΣαGamma spectrum, Bq/l
239Pu240Pu241Am238Pu244Cm137Cs134Cs154Eu241Am144CE106EN
Adjusted initial solution3,728642.4 x 10111.6 x 10111,3·10102,1·1091,0·10111,7·109
Extract zirconium and molybdenum12,886,1 1,11,3·1078,4·1062,1·1086,7·1061,1·1091,4·108
The raffinate3,728642.4 x 10111.6 x 10111,3·10102,1·109to 9.9·10101.6 x 109

Based on the experimental data we can conclude that the molybdenum and zirconium is extracted from the original solution. Purification of alpha-emitters made 2 order, the main alpha contamination of the extract is due to plutonium. The removal of cesium exceeded 10,000, americium, europium and cerium cleaning was around 100.

Remaining after selective extraction of zirconium and molybdenum RapNet, warmed up at a temperature of 60-80°C, and then transferred to the extraction extraction Chenoweth actinides.

The extract containing molybdenum and zirconium, have been treated with a solution containing 1 mol/l to metill the n carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo and Zr. In the organic phase, these radionuclides were not detected. The extractant is aimed at reuse.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH. The duration of the separation of phases in this operation amounted to 1 minute.

Example 10.

Adjusted the original solution similar to Example 9, was treated with decanola containing 25 g/l benzylhydroxylamine acid for the selective extraction of zirconium and molybdenum at a temperature of 70°C. Remaining after selective extraction of zirconium and molybdenum RapNet, treated with a solution containing Cr(VI) concentration 1 g/l, after which he handed over to extraction extraction Chenoweth actinides.

For separate allocation of molybdenum and zirconium, the extract containing molybdenum and zirconium, similar to Example 9, is treated with a solution of nitric acid with a concentration of 5-6 mol/l for the selective extraction of Zr. After processing in the aqueous phase was discovered more than 99.9% of Zr.

Next, the extract containing only molybdenum, were treated with a solution containing 1 mol/l methylamine carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo. The organic phase, not when holding the specified radionuclide, was returned for re-use.

Example 11.

Adjusted the original solution similar to Example 9, was treated with decanola containing 25 g/l laurenheartssmiley acid for the selective extraction of zirconium and molybdenum at a temperature of 70°C. Remaining after selective extraction of zirconium and molybdenum RapNet, treated with a solution containing Cr(VI) concentration 1 g/l, after which he handed over to extraction extraction Chenoweth actinides.

The extract containing molybdenum and zirconium, have been treated with a solution containing 1 mol/l methylamine carbonate (IAC) in the presence of 20 g/l DTPA. After processing in the aqueous phase was discovered more than 99.9% of Mo and Zr. In the organic phase, these radionuclides were not detected. The extractant is aimed at reuse.

To remove any accumulated in the extractant carboxylic acid, spent washing the organic phase with a solution of 0.1-1 mol/l NaOH. The duration of the separation of phases in this operation amounted to 15 minute.

Example 12.

The solution of the spent nuclear fuel of VVER - 1000 burn-60 GW-d/t HM containing 50 g/l U, and treated with a reducing agent with complexing agents - nitrate solution hydrazinehydrate with ascorbic acid (AA), obtaining in the end a solution of 0.1 mol/l hydrazine nitrate, 2 g/l AK and 2 mol/l HNO3after which, with orrectional the original solution was treated with decanola, containing 13 g/l aprilhydraulic acid for the selective extraction of molybdenum. The extract obtained molybdenum and the raffinate was analyzed on the content of the main components. The results are presented in table 2.

Table 2.
ProductThe concentration of the analyzed components
HNO3, mol/lU, g/lPu, mg/lMo, mg/lZr, mg/lΣα, Bq/lΣγ, Bq/l
Adjusted initial solution2of 37.8330140*1842,8·10105.2 x 1011
Extract molybdenum0,5 <1175<153,4·108
The raffinate237,3330<51702,8·10105·1011
ProductThe alpha range, % of ΣαGamma spectrum, Bq/l
239Pu240Pu241Am238Pu244Cm137Cs134Cs154Eu241Am144CE106EN
Adjusted initial solution3,72864 2.4 x 10111.6 x 10111,3·10102,1·1091,0·10111,7·109
Extract molybdenum12,886,11,11,3·1078,4·1062,1·1086,7·1061,1·1091,4·108
The raffinate3,728642.4 x 10111.6 x 10111,3·10102,1·109to 9.9·10101,55·109

Based on the experimental data we can conclude that the molybdenum is extracted from the original solution. Purification of alpha-emitters made 2 order, the main alpha pollution is giving extract due to plutonium. The removal of cesium exceeded 10,000, americium, europium and cerium cleaning was around 100.

The extract was placed in a flask rotary vacuum evaporator (RMA) and at a residual pressure of 25 mm Hg drove the extractant. Distilled the solvent did not contain Mo and was returned for re-use.

1. Method for the selective extraction of radionuclides from radioactive nitrate solutions, including the processing of the original solution of the extractant in the presence of extractable complexing agents, in particular aliphatic hydroxamic acids, with subsequent excretion from the extract radionuclides, characterized in that the extraction of Mo or Mo together with Zr are using as extractant difficultly soluble in the aqueous phase of the liquid alcohol with the addition of complexing agents, in particular aromatic hydroxamic acids or aliphatic hydroxamic acids with the number of carbon atoms of 6 to 12, the extract is washed with a solution of nitric acid of a concentration of 0.1 to 4.0 mol/l and emit radionuclides together or separately from the extract of the sublimation of the extractant or reextracting.

2. The method according to claim 1, characterized in that the radioactive solutions are solutions of SNF processing, solutions of irradiated uranium targets, concentrates irradiated molybdenum biomedical destinations the deposits.

3. The method according to claim 1, characterized in that the extraction of radionuclides is carried out at a temperature of 70°C.

4. The method according to claim 1, characterized in that the selection of radionuclides from the extract is carried out by sublimation of the solvent under reduced pressure.

5. The method according to claim 1, characterized in that reextraction radionuclides carried out using solutions of carbonates singly charged cations in the presence of DTPA.

6. The method according to claim 1, characterized in that reextraction Zr to carbonate Stripping Mo spend 5-6 mol/l HNO3or nitric acid solution of DTPA.

7. The method according to claim 5, characterized in that the periodic removal of the extractant accumulated carboxylic acids is carried out by washing with a solution of 0.1-1 mol/l NaOH.

8. The method according to claim 1, characterized in that the processing of SNF solutions after extraction of Zr and Mo for subsequent extraction Chenoweth actinides carried out by heating at 60-80°C or by adding Cr(VI).

9. Method for the selective extraction of radionuclides from radioactive nitrate solutions, including processing the corrected solution of the extractant in the presence of extractable complexing agents, in particular aliphatic hydroxamic acids, with subsequent excretion from the extract radionuclides, characterized in that the starting solution is subjected to processing by reducing or vos is canoville with extrahieren complexing agents, after extraction of Mo or Mo together with Zr are using as extractant difficultly soluble in the aqueous phase of the liquid alcohol with the addition of complexing agents, in particular aromatic hydroxamic acids or aliphatic hydroxamic acids with the number of carbon atoms of 6 to 12, the extract is washed with a solution of nitric acid of a concentration of 0.1 to 4.0 mol/l and emit radionuclides together or separately from the extract of the sublimation of the extractant or reextracting.

10. The method according to claim 9, characterized in that the radioactive solutions are solutions of SNF processing, solutions of irradiated uranium targets, concentrates irradiated molybdenum biomedical application.

11. The method according to claim 9, characterized in that the reduction processing of the original solution to keep the plutonium extraction is carried out with the help of hydrazinehydrate or mixtures of the latter with nitrate or chloride, hydroxylamine, and to hold together plutonium and zirconium to hydrazinehydrate add ascorbic acid or DTPA.

12. The method according to claim 9, characterized in that the extraction of radionuclides is carried out at a temperature of 70°C.

13. The method according to claim 9, characterized in that the selection of radionuclides from the extract is carried out by sublimation of the solvent under reduced pressure.

14. The method according to claim 9, characterized t is m, that reextraction radionuclides carried out using solutions of carbonates singly charged cations in the presence of DTPA.

15. The method according to claim 9, characterized in that reextraction Zr to carbonate Stripping Mo spend 5-6 mol/l NGO3or nitric acid solution of DTPA.

16. The method according to 14, characterized in that the periodic removal of the extractant accumulated carboxylic acids is carried out by washing with a solution of 0.1-1 mol/l NaOH.

17. The method according to claim 9, characterized in that the processing of SNF solutions after extraction of Zr and Mo for subsequent extraction Chenoweth actinides carried out by heating at 60-80°C or by adding Cr(VI).



 

Same patents:

FIELD: chemistry.

SUBSTANCE: method involves converting wastes to a gel-like state and is characterised by that solutions of highly active wastes are mixed with zirconium and iron salts and glycerine to concentration of said salts of not less than 0.12, 0.6 and 0.25 M/l respectively, holding the obtained mixture for not less than 2.5 hours, followed by adding to the mixture a solution of mono-substituted potassium phosphate in phosphoric acid to molar ratio of components Zr:Fe:K:PO4=1:3:2:5-8, drying, calcining the obtained polymer gel of zirconyl phosphate at 70-90°C and 300-400°C, respectively, and melting the obtained granules at 980-1000°C.

EFFECT: converting wastes into compact material which is suitable for long-term and safe storage.

3 cl, 2 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to hydrometallurgy of uranium and can be used to recycle mother solutions formed when producing uranium tetrafluoride from nitrate solutions via extraction, re-extraction and heat treatment of uranium compounds obtained from re-extracts to obtain uranium dioxide and further treatment thereof with chloride and fluoride solutions. The method of recycling mother solutions from production of uranium tetrafluoride involves mixing said solutions at pH 4.0-5.2 by bubbling air until pH stabilises and treating with sodium hydroxide at pH 10.5-11.0, separating the uranium-containing residues from the solutions and return thereof to the step of leaching raw products, settling the waste solutions in a tailing pond and pumping the remaining part of the solutions into the ground.

EFFECT: low consumption of nitric acid, sodium hydroxide and lime, reduced discharge of liquid wastes in the tailing pond.

3 cl, 6 tbl

FIELD: process engineering.

SUBSTANCE: invention relates to processing of heterogeneous liquid radioactive wastes, particularly, to processing of used fine abrasive filter materials and can be used for processing of waste filter perlite powder of special water treatment systems. Proposed method consists in extraction of filter perlite powder pump from storage tank, removal of excess moisture, transfer by hydrotransport, cementation, and adding ion exchange resins in amount of 10÷75% of filter perlite powder volume at density of 1÷1.5 g/cm3 to said pulp before transfer from storage tank.

EFFECT: 80-100 times decreased wear of equipment and pipelines.

2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to processing liquid radioactive wastes formed when processing spent nuclear fuel. Described is a method of processing technetium solutions, which involves precipitation of technetium from nitrate solutions with concentration of nitric acid or the nitrate ion of not more than 3 mol/l, with concentrated aqueous solutions of o-phenanthroline or α-bipyridyl complexes of divalent transition metals, or mixed complexes of said organic compounds or mixed complexes containing o-phenanthroline or α-bipyridyl with dibasic amines. The obtained precipitates of organometallic pertechnetates are calcined in a hydrogen current at temperature of 600-1200°C with or without a low-melting metal or oxide thereof with melting point of 200-800°C to obtain stable matrices that are suitable for further storage and processing.

EFFECT: obtaining technetium in the final form which is suitable for further storage and processing.

5 cl, 2 tbl, 6 ex

FIELD: power industry.

SUBSTANCE: method provides for sedimentation of waste in an initial tank with draining of contaminants from surface to an oil product sump, pre-cleaning on mechanical bulk filters with modified nitrogen-containing coals and coarse and fine cleaning microfilters, softening and demineralisation on a reverse-osmosis filter with deposition of wastes in two intermediate tanks. Filtrate of reverse-osmosis filters is supplied for additional cleaning on ion-exchange filters, and concentrate is returned to the first intermediate tank before microfilters as an alkalising reagent prior to saturation as to salts with curing of formed radioactive concentrates by introduction to Portland cement. Coals saturated with oil products are replaced with new ones, and waste ones are burnt with oil products drained from the initial tank, including ash residue in Portland cement together with waste concentrates.

EFFECT: improving strength of cement stone by 1,5-2 times and reliable fixation of radionuclides in it.

1 dwg

FIELD: power industry.

SUBSTANCE: method for preparation of spent nuclear fuel reprocessing solutions containing complexing agents for extraction of multivalent actinides at suppression of action of complexing agents consists in introduction to a solution of nitric-acid solutions of transient metals that fix complexing impurities better than plutonium does. As complexing agents, the solution can contain ethanedioic acid, mellitic acid and other polybasic acids and oxygen acids, DTPA and EDTA. As added binding agents, there used are nitric-acid solutions of molybdenum and/or zirconium, including spent nuclear fuel solution based on uranium-molybdenum alloys introduced in equimolar amounts or amounts close to them as to metal: complexing agent ratio.

EFFECT: invention allows extracting multivalent actinides from spent nuclear fuel solutions containing complexing agents applying non-destructive methods and without strong change of reagent medium.

5 cl

FIELD: power engineering.

SUBSTANCE: calcination of a solution of radioactive wastes (RAW) is carried out in a microwave plasma reactor, then a homogeneous glass melt is produced in a frequency melter of direct induction heating. The method includes supply of the RAW solution into a zone of electrothermal processing, which comprises a zone of plasma microwave processing of the RAW solution in the water and vapour plasma and a zone of bath processing of the melt produced by direct induction heating of inorganic RAW ingredients, melting and electromagnetic mixing of inorganic RAW ingredients, continuous removal of the melt, cooling of the gas flow, cleaning of the gas flow from volatile products of RAW decomposition and from process dust. The device for realisation of the method comprises a plasma chamber, the upper part of which is made in the form of a truncated cone, equipped with an all-metal microwave plasmatron, which generates a flow of water and vapour plasma, a unit of RAW solution supply, a frequency melter of direct induction heating for melting and homogenisation of inorganic RAW ingredients, equipped with a pipeline for melt drainage, a collector - an accumulator of glass melt, a pipeline for gas flow transportation for cleaning.

EFFECT: solving the problem of complex environmentally and technical safe processing of RAW.

14 cl, 2 dwg

FIELD: power industry.

SUBSTANCE: invention refers to processing technology of high-salty liquid radioactive wastes of low and medium activity level, which contain up to 30% of organic substances by their being added to magnesite cement. Composite material has the following composition: loose dead-burned magnesite caustic powder - 27-28 wt %, hard salts - 5-6 wt %, calcium chloride (CaCl2) - 0.1-6 wt %, catalytic carbon-bearing additive - 0.1-0.2 wt %; potassium ferrocyanide solution - 0.05-0.1 wt %; and nickel nitrate solution - 0.05-0.1 wt %, and liquid radioactive wastes are the rest. The following sequence of ingredients is added to liquid radioactive wastes: hard salts, potassium ferrocyanide solution, nickel nitrate solution, calcium chloride, catalytic carbon-bearing additive, and loose dead-burned magnesite caustic powder. The invention allows obtaining compounds meeting the main requirements of their quality as per GOST R 51883-2002 (cesium leaching rate -137 ≤1-10-3, achieved - 2-10-5g/cm2·day, and compressive mechanical strength ≥5 MPa), with filling of dry radioactive layers of up to 37 wt %.

EFFECT: compliance with the main requirements.

2 cl

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

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: chemistry.

SUBSTANCE: invention relates to method of determining optimal parameters of dissolution of oxides of transition metals in solutions, which contain complexing agent, and can be applied in atomic energy. As parameters, applied are volume coefficients of distribution of radioactive isotopes of transition metals, which determine composition of oxides, between solutions, which contain complexing agent, and strong-base anionites in form of said complexing agent (complexits) and balanced values of solution pH. Radioactive isotopes of transition metals are introduced into fixed volumes of analysed solutions, after which, fixed volumes of complexits are introduced into solutions. Initial and final activity of solutions is measured. Also measured are balanced values of pH of solutions. Ranges, satisfying optimal parameters, which must be supported in contours of NEP directly in the process of dissolution of oxides in the process of washing and deactivation of NEP contours, are determined by the results of measurements.

EFFECT: increased reliability of determination of optimal parameters of dissolution of oxides of transition metals in complexing agent solutions and absence of necessity of carrying out complex analyses of metals to determine concentration of metal cations in solutions of complexons.

2 cl, 2 dwg, 1 tbl

FIELD: power engineering.

SUBSTANCE: machine for cutting of pipelines, preferably caissons from a storage tank, comprises a body and a rotor covering the cut pipe, with a metal cutting device fixed on it. The machine body is made in the form of a circular ball step-bearing, the fixed part of which is attached to the rotary board of the storage tank together with the drive for rotation of the movable part, coaxially and elastically fixed to the rotor flange. The rotor is made in the form of a cylindrical thin-walled hollow column that covers a caisson, with a rotary stem fixed on it, at the end of which a small-size driving cutting machine is attached with an abrasive disc.

EFFECT: creation of a reliable and comparatively cheap machine for cutting and trimming of pipelines, in particular, caissons in unavailable zones of radiation-hazardous facilities at the depth of at least 3 metres from the outer surface of the facility to provide for nuclear and radiation safety.

4 cl, 7 dwg

FIELD: power engineering.

SUBSTANCE: method includes construction of inspection wells in a reservoir bed, their equipment with facilities of water lift, facilities to measure level and pressure of subsurface water in them, to pump subsurface water from them, performance of physical and chemical tests of pumped subsurface waters. During pumping a volume of subsurface water is extracted from the well, and this volume is less than the one contained in its borehole, density of the extracted subsurface water is measured, afterwards it is supplied back into the well in the interval, from which it was pumped, measurement of subsurface water pressure is carried out along piezometric tubes lowered into a well filter and filled by water with available density, afterwards water density is determined in the reservoir bed.

EFFECT: improved validity of produced data and elimination of hydrodynamic mode disturbances in wells in process of monitoring.

1 cl, 1 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to separation of fluids by evaporation. Proposed method comprises evaporation of solvent from solution film formed on rotary drum inner surface. Solution is fed inside drum to allow displacement of solution toward unloading side. Solvent vapors are collected and condensed. Heat power consumed for solvent evaporation, drum rpm and level of solution inside the drum are selected provided concentrated product is discharged in the form of fluid. Flow rate of solution fed into drum is to be calculated by mathematical tools.

EFFECT: sufficient quality of concentrated product and solvent condensed vapors provided in continuous operation without drop in efficiency in wide range of concentrations of solutions.

11 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of recycling nuclear energy materials and specifically to methods of cleaning uranium hexafluoride from ruthenium fluorides, and can be used in returning uranium, extracted from spent nuclear fuel, into the fuel cycle of light water reactors. The method of cleaning uranium hexafluoride from ruthenium fluorides involves reaction of gaseous uranium hexafluoride with a sorbent, the sorbent used being porous granules of sintered metal powder of nickel or nickel which contains up to 10 wt % copper.

EFFECT: invention provides efficient cleaning of uranium hexafluoride from ruthenium fluorides at low temperatures, safety and simplification of the process, and also enables to reuse the sorbent after regeneration.

5 cl, 2 tbl, 5 ex

FIELD: mining.

SUBSTANCE: method of underground disposal of biohazardous waste water in geological formations with no distinct waterproof stratums above production level includes drilling of injection well and pumping of biohazardous waste water in production level. Injection well is drilled inclined directed, in the interval of production level bore of injection well is drilled parallel to bedding at a distance from bottom of production level equal to 0.1-0.2 of production level thickness, and observation well is drilled on water-bearing level located below level with groundwater used for drinking and technical needs.

EFFECT: preventing penetration of disposed biohazardous waste water in above located water-bearing levels.

4 cl, 1 dwg, 1 ex

FIELD: process engineering.

SUBSTANCE: proposed method comprises treatment of radioactive wastes solutions by alkaline metal hydroxides or carbonates to pH 1, extraction of tri-n butyl phosphate in inert diluter to convert rare-earth and transplutonium elements into extracts and their separation from cesium-strontium fraction, flushing of said extract by solution of aluminium nitrate and adding flushing solution to feed water. Hydrogen peroxide is added to radioactive wastes solution at neutralisation stage.

EFFECT: higher reliability of treatment.

1 tbl

FIELD: metallurgy.

SUBSTANCE: method consists in use for recovery of extragent of solutions of bicarbonates of univalent strong bases, and namely sodium bicarbonate, tetraethylamine or guanidine, or solutions of carbonates of univalent weak bases or mixture of carbonates and bicarbonates of univalent weak bases, such as hydrazine or methylamine, which are resistant to heating.

EFFECT: invention allows increasing the number of extragent operating cycles.

14 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to processing and decontaminating highly active pulp and can be used at radiochemical plants. The method of dissolving silicon-containing pulp involves dissolving silicic acid in an alkali solution, wherein a sodium alkali solution is added to the pulp with density not greater than the density of the pulp, and the obtained alkaline pulp is treated with nitric acid.

EFFECT: invention simplifies the process of dissolving silicon-containing pulp without heating and stirring, and enables to achieve a higher degree of dissolution of plutonium when treating silicon-containing pulp.

2 cl, 1 tbl, 5 ex

FIELD: transport.

SUBSTANCE: group of inventions relates to feeding solution into container accommodating hazardous wastes, in particular nuclear wastes. In the method, solution is fed into container immovably connected with the first and the second reservoirs. The first reservoir communicates with container via the first hole, the second reservoir - via the second one. In this process, solution flow is subjected to forced continuous circulation in circulation circuit. During this circulation, the second flow of solution is drawn which is less intensive than the first flow, and delivered to container. Solution appearance in the second reservoir is detected. When this appearance is detected solution bleeding from circulation circuit is terminated. Device for implementation of the method contains solution circulation circuit consisting of vessel for solution storage, pump for solution transfer connected with the vessel, source pipeline to transfer solution exiting the pump, return pipeline to transfer solution to the vessel, and discharge pipeline following the source pipeline. The device also contains the first and the second reservoirs immovably connected with container against holes made in its wall, and sensor detecting solution appearance in the second reservoir. In this structure, circulation circuit contains bleeding device connecting source, return and discharge pipelines, and cutoff of discharge pipeline from the circuit is performed by on-off valve installed at the inlet of discharge pipeline. Herewith, source and return pipelines provide continuous solution circulation, and bleeding device provides drawing part of solution flow circulating in the circuit and its delivery to discharge pipeline.

EFFECT: group of inventions provides better container filling when there is no reliable information on wastes volume in it, and better insulation.

18 cl, 4 dwg

FIELD: nuclear engineering.

SUBSTANCE: the proposed method of removal of irradiated material from nuclear reactor plate includes the irradiated material shielding with a shield material and their following removal of both materials. The shielding is fulfilled with a granulated material. Removal of irradiated and granulated materials is carried out by means of an auxiliary tube with a grate, confining the irradiated material and permeable for granulated material. The auxiliary tube is installed into the tube of a reactor fuel channel.

EFFECT: decreasing the idle time of reactor or/and production equipment.

1 cl, 1 dwg

Up!