UA82581C2 - Method for deactivation of liquid radioactive wastes (variants) - Google Patents

Abstract

Method for deactivation of liquid radioactive wastes includes two main stages, in particular:(a) sorption of ions of radioactive cesium with Cs-selective sorbent at temperature not higher that point of water boiling during time enough for decrease of concentration of radionuclides of cesium to level lower that LPC.(b) separation of ions of radioactive cobalt and other metals as dispersion deposit of insoluble in water carbonates and / or hydrated oxides of metals of type МеОnНО.Deposit is formed by inclusion to PPV of source of carbonate-ions with simultaneous thermal (at temperature lower than boiling point of water), mechanical and electromagnetic treatment of alkaline mix in through induction heater, in body of which there is installed at least one short-circuit electro-conductive heating element that can vibrate mechanically in varying electromagnetic field.In different variants of implementation of the invention those stages can be performed in different order.For selective extraction of cesium it is desirable to use sorbent on basis of sodium-cobalt gexacyanoferate KCo[Fe(CN)], that is fixed on granulated silica-gel as carrier.

Description

Description of the invention

The invention relates to the processes of deactivation of liquid media containing radioactive isotopes of metals and 2 to the composition of the sorbent for the selective extraction of cesium.

Such processes and sorbents can be used: - for the extraction of long-lived radioactive isotopes of cesium, cobalt, strontium, etc. from liquid radioactive waste (hereinafter RWW), which usually arise as by-products of the cooling systems of power (and, to a lesser extent, experimental) nuclear reactors , 70 - for the conversion of extracted isotopes and other non-combustible toxic impurities into compact solid radioactive waste (hereafter TRW), suitable for reliable burial, and - for the extraction of boric acid from acidic RWW for the purpose of its reuse.

Typical RRV of experimental nuclear reactors with water cooling of the core usually contain water with impurities of radioactive products of nuclear fuel decomposition and corrosion of metal parts of the cooling system 72.

Typical RRV of nuclear power plants (hereinafter NPP) are aqueous solutions of boric acid with impurities of the specified radioactive isotopes and some other substances such as sodium and potassium chlorides and iron sulfates and/or nitrates

ICadiospetivigu ip MysiIeag Romeg Keasiogg (1996) trans//mlum par. edyshoreprook/M100156/piti).

With regard to nuclear power plant waste, it is customary to distinguish: - "source (especially acidic) waste water", which is periodically taken directly from the cooling system of the active zone of an arbitrary nuclear reactor, and - "melt", that is, conditionally solid radioactive waste in the form of a mixture of crystalline boric acid (НзВОз- pNoO), concentrated impurities of radioactive isotopes and ballast substances.

In the United States, RRV weekends are used, as a rule, for wetting cement and making concrete blocks, which are hidden together with the radioactive isotopes included in the concrete. Go)

However, even concrete is not an absolutely reliable container for TRVs, which are obtained as indicated above. Therefore, the territories allocated for their burial must be under protection and systematic control of the radiation situation.

The float is obtained by evaporating the excess of unbound water from the original RRV.

This process is used at nuclear power plants built according to Soviet designs. For example, the brine of nuclear power plants equipped with Soviet reactors of the VVER-1000 type, according to the data of the Atomproekt Institute (Russia), has the following average composition (taking into account the main ingredients): borates 400-60Okg/m Z (25-3795 wt.) Ha ions Mach, Kk 300-400kg/m Z (19-2596 wt.)

Zo! (ge) MOH ions - 280-34Okg/m З (17-2196 wt.) ionnzo42 - 50-7Bkg/m З (3.5-595 wt.)

Ions SI- 2B-ZOkg/m З (1.6-296 wt.) water of crystallization 155-BABkg/m З (10-3496 wt.) « - s Usually, such melt contains radionuclides of 13"Sv in a concentration of the order of 10 "Bk /kg, Sv - of the order of 10 "Bq/kg" with and Oso - of the order of 107 and more Bq/kg and analytically significant impurities of non-radioactive ions He, He", Mp", Ma?", "Sag" mi25, Sug" in /or some other metals.

The finished float is stored in corrosion-resistant metal containers, which in principle are suitable for transportation on railways or roads in compliance with radiation safety rules. However, at many NPPs, excessive liquid reserves have become a source of threat to personnel and the environment. Therefore, it is desirable: - firstly, to exclude the accumulation of fresh water by cleaning the original RRV from radioactive 1 impurities to a level below the MPC, returning boric acid to the cooling systems of nuclear reactors and burying CO 20 only compact TRVs and ballast impurities, and - secondly, dissolve the previously accumulated float in water, and then clean and deactivate the regenerated RRV in this way.

According to tradition, sorbents are used for cleaning the original and regenerated solid waste, which, after the sorption capacity is exhausted, are usually thermally treated (in particular, incinerated and remelted in solid waste) and buried. o The most notable successes in this direction have been achieved in the development of ion-exchange sorbents based on such complex coordination compounds as: potassium-nickel co-hexacyanoferrate, obtained by (as a rule, multiple) impregnation of silica gel with solutions of Mi(MO»z)» and KABe(SM)5 (Mitiga ei ai. Zeyesime getoma! sevzisht iliyot Pidniu sopsepigabgei zoaiit 60 pisha pecsiga! zoishiopv roiazzisht pisKe! Pehasuapogegtae(II)-Ioadei vziysa deiv// Zoimepi Ehigasiop apa

Iop Ekhspapde. My. 17; Ivvce 2; RVO, Magsi 1999); - hexacyanoferrates of transition metals or pentavalent antimony hydroxide on granular polymer, in particular, phenolformaldehyde, carriers (U. Magriy, A. Viemis7, V. Vapyo Sotrozye iop ekspapdegv:

Rgozresiime pisieag arriisayopv// doigpa! Kadioapa|uiisa! apa Mysieag Spetivig. My. 183, Mo. 1, pp. 27-32). However, ion-exchange sorbents of this type make it possible to isolate only radioactive isotopes of cesium from aqueous solutions.

Therefore, more complex processes and means are required for the deactivation of nuclear power plants, in which, as a rule, isotopes "Sv and 137С8 of the alkali metal cesium and 99Со together with ions of other metals are present together.

For example, the known concentration of B0Co and 73485 using cetylpyridinium chloride, separation of the concentrate by flotation and sorption of the specified ions with hexacyanoferrate (II) of cobalt (I) (M. Ai2, 5.0. Vepeig

Ketoma! 99Sbo apa "St.

Spitiwig 1995, My. 191, Mo. 1, pp. 53-66).

Unfortunately, the content of radionuclides of cesium and cobalt, even in the recovered from the floating PRW, is so small that their 70 simultaneous separation by flotation and subsequent sorption is convenient only in laboratory conditions, while their separate extraction is desirable in industry.

Naturally, this requires specific means.

Thus, there is a known method of liquid radioactive waste deactivation, which is closest to the method proposed below (ZgaroYisv 520Ke, Subgdu Raigau, I az2i6 M/eizeg OemeIortepi zeiIesiime sobraii apa saezitst hetomai! iot 72 emarogaig sopsepiga (ez RMUB. Rakz I Kadiospitisa Asia, Moi. 91 , 2003 Moe3, pp. 229-232). This method involves: - evaporation of water from low-concentration RRV to obtain concentrated solutions suitable for long-term storage (in which the concentration of such radionuclides as Sv, 197Sv and oso is significantly increased), - extraction of radioactive cesium from the specified concentrated solution using an SS-selective sorbent based on such an ion-exchange material as potassium-nickel hexacyanoferrate (II), - extraction of radioactive cobalt from the specified concentrated solution with activated carbon, - processing of spent sorbents into compact TRVs for burial.

The technological line for the implementation of the described method includes: - at least one source of initial RRV (which usually serves as a buffer collector for the liquid that is taken from the cooling system of the active zone of a nuclear reactor), c 29 - at least one source of concentrated RRV (which can be served either directly by the evaporation apparatus, (3 is connected to the indicated collector of source RRV, or a tank for storing previously concentrated RRV, at the outlet of which an apparatus with a stirrer for dissolving the melt is installed), - at least one adsorber filled with C3-selective sorbent (which, in particular, is connected to the source of concentrated RRV) , -- - at least one device for the isolation of radioactive cobalt and other metal ions (namely, an adsorber filled with activated carbon), which is connected to an adsorber filled with a Cvz-selective sorbent, - means of pumping initial and concentrated RRV and liquid intermediate and by-products of their cleaning and yuyu - means of processing spent sorbents into compact ones TRV for burial. high school

However, this process and the known means for its implementation are extremely uneconomical due to heat consumption

From the evaporation of water during the preparation of the outgoing RRV for decontamination. Not only that, the described process does not provide efficient cleaning of even concentrated RRVs obtained by dissolution of melt, because the sorption capacity of potassium-nickel hexacyanoferrate depends on the presence in the liquid medium of such metal ions as Ee 7,

BeZya, Mp2", Ma", Sa?", So", Mi2", Suy?", and activated carbon is in principle not selective as a sorbent. Attempts to weaken the negative influence of these ions on the sorption of cesium ions by introducing complexing agents such as citrate ions, oxalate ions, and EDTA into the RRV significantly complicate the process. And, finally, the known process does not involve the release of boric acid as a valuable by-product. :z" The invention is based on the task of changing the means, conditions and order of isolation of long-lived radioactive isotopes from low-concentration aqueous solutions to create such a method and such a sorbent that would ensure effective deactivation of both the original RRV and acidic RRV obtained by dissolving the melt. This problem in the first version is solved by the fact that the method of decontamination of RRV involves: - selection of a portion of the initial RRV for deactivation, io) - introduction of a source of carbonate ions into the selected portion of the initial RRV until an alkaline reaction is reached, simultaneous thermal, mechanical and electromagnetic treatment of the mixture in induction heater, in the body of which at least one short-circuited electrically conductive heating element is installed, capable of mechanically (se) vibrating in an alternating electromagnetic field, also - the separation of cobalt radionuclide and other metal impurities in the form of a dispersed precipitate of water-insoluble carbonates and/or hydrated metal oxides of the MeuOu pNos type, which fell out as a result of the specified processing, - introduction of the mother liquor remaining after the separation of the specified sediment into contact with the S-selective sorbent for a time sufficient to reduce the concentration of cesium radionuclides to a level below the MPC, - processing of the spent sorbent and the specified above MechOu pH2oO sediment in compact TRVs for p further (F. burial. The combination of such processes as the formation of a dispersed deposit of radioactive cobalt and other metals in an induction heater at a temperature below the boiling point of water during the treatment of arbitrary RRV and boron sorption of radioactive isotopes of the alkali metal cesium allows, as will be shown later in the examples: - first , to reliably reduce the content of radionuclides in RRV to levels below the MPC and, secondly, to practically exclude the overgrowth of the internal surfaces of the devices with radioactive sediments.

The task is also solved by the fact that the second variant of the method of decontamination of nuclear reactors involves: - selection of a portion of acidic source nuclear reactors containing boric acid, corrosion products of the B5 cooling system of a power nuclear reactor and at least such radionuclides as "Z/Sv, 134Sv and б0Со, - introduction of a selected portion of RRV into contact with a Сv-selective sorbent at a temperature of no more than б02С for a time sufficient to reduce the concentration of cesium radionuclides to a level below the MPC, - introduction of a source of carbonate ions into practically cleaned of radionuclides. 7378 and 1348 liquid radioactive waste to achieving an alkaline reaction, - simultaneous thermal, mechanical and electromagnetic treatment of the mixture in an induction heater, in the body of which at least one short-circuited conductive heating element is installed, capable of mechanically vibrating in an alternating electromagnetic field, separating cobalt radionuclide and other metal impurities in the form of a dispersed precipitate of water-insoluble carbonates and/or hydrated of metal oxides of the type

MechOu pn2o, which fell out as a result of the indicated treatment, - partial evaporation of the practically deactivated mother liquor to obtain a concentrated solution of boric acid with impurities of mineral salts, - cooling of the indicated solution until the precipitate of boric acid precipitates, - separation of the practically deactivated precipitate of boric acid for further utilization, - evaporation of the mother liquor under vacuum to obtain an almost deactivated dry mixture of salts and - processing of the spent sorbent and the above-mentioned sediment of MechOu pNoO in compact TRVs for further burial.

This makes it possible to significantly reduce energy costs for the decontamination of RRV and to obtain practically deactivated boric acid as a valuable by-product.

The task is also solved by the fact that the third variant of the method of decontamination of RRV provides for: - selection of a portion of melt, - regeneration of liquid radioactive waste by dissolving the selected portion of melt in acidified water in circulation mode through a flow induction heater that maintains a temperature below the boiling point of water, - cooling of the obtained solution until the precipitation of boric acid, which is practically purified from radionuclide 9Co and contains an admixture of radionuclides 737Sv and 134Sv, with. - separation of the boric acid precipitate, its washing from the specified impurities in a closed loop with ge) deposition of radionuclides 137Cv and 1345 on a Cvz-selective sorbent and drying of the washed precipitate to a constant mass, - introduction of a source of carbonate ions into the supernatant liquid remaining after the separation of the precipitate boric acid, until the alkaline reaction is reached, - simultaneous thermal, mechanical and electromagnetic treatment of the mixture in induction heating, in the case (87 of which at least one short-circuited electrically conductive heating element capable of mechanically vibrating in an alternating electromagnetic field is installed, - separation of cobalt radionuclide and other metal impurity in the form of a dispersed precipitate of carbonates and/or hydrated metal oxides insoluble in hot water of the MeuOu pH.O type, which fell out as a result of the specified treatment, c - at least a two-fold dilution of the mother liquor remaining after the separation of the specified precipitate, - introduction of the obtained diluted solution into contact with St. selective so rbent at a temperature lower than the boiling point of water for a time sufficient to reduce the number of cesium radionuclides to a level below the maximum permissible concentration, - evaporation of a solution purified from cesium radionuclides under vacuum to obtain an almost "deactivated dry mixture of salts and Z c 70 - processing of the spent sorbent and the above-mentioned MechOu pNoO sediment into compact solid radioactive waste for further burial. :z» This allows for efficient processing of floating reserves into compact solid waste suitable for reliable burial, and purified water to be returned to the technological cycle. 415 The first additional difference for this version of the method is that the water obtained by evaporation of the deactivated salt solution is used to dissolve the following portions of the melt, or to dilute the filtrate. This reduces the need for fresh water during mass decontamination of RRV. io) The next additional difference is that the solution purified from cesium radionuclides, before evaporation under vacuum, is heated for at least two hours at a temperature below the boiling point of water in an induction heater, in the body of which at least one short-circuited (se) conductive heating element is installed an element capable of mechanically vibrating in an alternating electromagnetic field. This also makes it possible to transform the remains of iron, aluminum and other metal ions, which are corrosion products of the cooling systems of power nuclear reactors, into a water-insoluble form.

An additional difference for each of the described variants of the RRV deactivation process is that the source of carbonate ions is selected from the group consisting of sodium bicarbonate, sodium carbonate, lithium bicarbonate, lithium carbonate and potassium carbonate. This allows you to use various available tools

HF) saturation of RRV with carbonate ions. And, finally, the problem is solved by the fact that the sorbent for selective extraction of cesium serves as an ion-exchange material based on potassium-cobalt hexacyanoferrate KoCo|Be(СМ)5|, which is fixed on a carrier in the form of boron granulated silica gel.

Such a sorbent has a high sorption capacity, which practically does not depend on the presence of cobalt ions and other metals in the PRV.

An additional difference is that the indicated ion-exchange material and the indicated carrier are taken in the following ratio (in 9% by mass): for potassium-cobalt hexacyanoferrate 20-40 granular silica gel 60-80

It is convenient to obtain this sorbent by the method described below.

It is clear to a specialist that when choosing specific embodiments of the invention, arbitrary combinations of the specified 9 additional differences with the main inventive concept are possible and that the preferred examples of its embodiment described below do not limit the scope of rights in any way.

Next, the essence of the invention is explained by a detailed description of: - the method of manufacturing and the composition of the C3-selective sorbent (hereinafter FC-M) - the general method of decontamination of RRV with a brief description of the equipment and examples of implementation of the method of RRV deactivation, which differ in origin and chemical composition.

Production of ion-exchange C3-selective sorbent FC-M.

To manufacture the sorbent in laboratory conditions, the following reagents were used: a) reagents such as: 75 - coarsely granulated silica gel - cobalt hexahydrate CoSi»bNo0 with a density of 1.92 g/cm" yellow blood salt K DEe(SM)v| with a density of 1, 85g/cm C - C9o aqueous solution of ammonia MH" and - O.1M solution of nitric acid NMO"; and b) dishes such as "VOMEH" glasses with a capacity of 5.00 ml and 0.2 l.

In a glass with a capacity of 5.0 liters, silica gel granules were introduced to a level of about 2.5 liters, they were poured with 395% ammonia solution to a level that exceeded the level of the solid phase by about 1 cm, and the mixture was kept covered for one hour. Then the ammonia solution was drained, and the granules were washed with distilled water until the smell of ammonia disappeared. 38Og of cobalt chloride was added to the wet granules with intensive mixing. After its uniform distribution over the entire volume, the mixture was kept for 24 hours, washed from the remaining unreacted cobalt chloride, and 370 g of yellow blood salt was added in small portions with intensive stirring. The mixture was kept for 24 hours, washed from the remaining unreacted yellow blood salt, the granules were poured with a 0.1M solution of nitric acid, kept for 30 minutes and washed with distilled water. - z The product was dried on filter paper at room temperature in air.

Separate laboratory batches of FC-M sorbent obtained in this way corresponded to the data given in Table 1. (ge)

Table 1 o

Admissible composition of the ion-exchange С-selective sorbent FC-М сч with со

Regardless of the specific composition of individual batches, the FC-M sorbent, intended for the selective extraction of "c 40 |ons of Sv" from diluted solutions, has the following parameters: - n size of the granules of the main fraction 0.1-0.5,» mmoperating range pH 1- 12 admissible admixture of background ions up to 200 g/l (total of Masi'Kkeyi) maximum permissible operating temperature 15026 so with Sorbent FC-M it is recommended to store it in a sealed container (for example, in polyethylene bags) at a temperature of 18-2596. 1 For experiments on weekend cleaning and regenerated PPV from the ions of radioactive Ce isotopes, sorbents from 20 different batches were mixed and a product with an averaged theoretical exchange capacity of not less than 1.7 g-equiv/g (by K ions) was obtained. In general, the method of PPV deactivation involves two main stages of radionuclide release, namely: (a) sorption of cesium ions by a Cvz-selective sorbent at a temperature not higher than the boiling point of water for a time sufficient to reduce the concentration of cesium radionuclides to level below the MPC and 59 (b) release of ions of radioactive cobalt and other metals in the form of a dispersed precipitate insoluble in

HF) in water of carbonates and/or hydrated metal oxides of the MechOu pH2oO type, which are formed: - by introducing a source of carbonate ions into the RRV and bottom - by simultaneous thermal, mechanical (at a temperature below the boiling point of water) and electromagnetic processing of the alkaline mixture in an induction heater in the body of which is equipped with at least one short-circuited electrically conductive heating element capable of mechanically vibrating in an alternating electromagnetic field.

In various embodiments of the invention, these stages can be performed in a direct (that is, as indicated above) or in reverse order.

It is natural that each portion of spent sorbent should be removed from the process and processed (usually by heating to a temperature not lower than 20022) into compact solid radioactive waste even before the sorption capacity is exhausted.

The above-mentioned precipitate of carbonates and/or hydrated metal oxides is treated similarly after its separation from the mother liquor.

For the extraction of cesium radioisotopes in all variants of the invention, it is preferable to use the above-described FC-M sorbent.

The source of carbonate ions is usually selected from the group consisting of sodium bicarbonate, sodium carbonate, lithium bicarbonate, lithium carbonate, and potassium carbonate. Among them, sodium carbonate (from the point of view of availability on the market) and lithium carbonate (from the point of view of reducing obstacles to the sorption of cesium radionuclides) are more desirable. 70 For heating RRV and other liquid media at any stages of the process, flow induction heaters should be used mainly according to the previous invention, which is known from the International publication

MO 2006/006946 A1 dated January 19, 2006 of the international application PCT/OA2004/000068 and from the patent of Ukraine Mo75778.

Each such heater has at least one short-circuited conductive heating element capable of mechanically vibrating in an alternating electromagnetic field.

Accordingly, with simultaneous thermal, mechanical and electromagnetic treatment of suspensions inside any such induction heater, it is practically impossible to overgrow its surfaces with salt deposits.

High-speed centrifuges available on the market can be used to separate dispersed sediment of the MexOu'pNoO type, and preferably - filters with periodic reset of the sediment (for example, under the influence of ultrasound).

For receiving, accumulating and burying RW, it is advisable to use vaporizer containers, which are made of alternating layers of stainless steel and depleted uranium, and are able to maintain mechanical strength and shape when the outer shell is repeatedly heated to a temperature of more than 25096.

Each such container is designed for the accumulation and burial of 20 kg of solid waste. 1. An example of decontamination of an experimental nuclear reactor.

To clean up liquid radioactive waste of the VVR-M experimental nuclear reactor (Institute of Nuclear Research, Ukraine), an experimental installation was assembled, which included: - a 180-liter waste collector; i9) - a flow induction heater, in the case of which at least one short-circuited electrically conductive heating element is installed, capable of mechanically vibrating in an alternating electromagnetic field; - high-speed centrifuge at 17 OObob/min.; h-: - storage tank with a capacity of ZOOl; - two sorption columns with a capacity of Ol each, filled with FC-M sorbent; so - an intermediate collector of purified water with a capacity of 7Ol. i am

The initial RRV had a pH of less than 5, contained (in individual portions) 30-4Omg/l of iron ions and 30-4Omg/l of aluminum ions and, according to gamma spectroscopic analysis, were contaminated (on average) with radionuclides of Co in a cm concentration of 2, 03-107g/l (8.5.10ZBq/l) and 137Sv in a concentration of 5.59-10Ug/l (1.8-109Bq/l). with

After each successive filling of the RRV collection to the level of 150 l, sodium hydrogen carbonate or sodium carbonate was introduced into it with stirring until the pH was greater than 8 (but not more than 11).

The resulting mixture was pumped in the circulation mode with a flow rate of approximately 2 l/min through an induction heater at a temperature in the range from 46 to 6092C until the appearance of finely dispersed flakes of carbonates and hydrated oxides of boron, iron and aluminum. These flakes arose as a result of simultaneous thermal, mechanical, and electromagnetic treatment of the mixture and were not deposited on the inner surfaces of the induction heater.

From" Next, the suspension was fed into a centrifuge, in which the solid phase containing the concentrated radionuclide os, iron and aluminum was separated. The accumulated radioactive sediment was removed and, after vacuum drying, sent for burial. so that the Warm mother liquor was poured into the indicated storage tank with a capacity of ZbOl and from there it was gradually pumped through the indicated sorption columns filled with FC-M sorbent for absorption of the radionuclide 137Sv. to Purified water was poured into the indicated intermediate collector with a capacity of 7Ol, from where samples were taken for determination of sl residual content of radionuclides by gamma spectroscopy. With positive results, the water was poured into the 50 sewer without dilution, since the residual activity was no more than 2.39 Bq/l, and "Z'Sv" was no more than 4.67 Bq/l. shkch The described method was used for cleaning from Co and 1050 liters of PPE 2. Examples of decontamination of PPE containing boric acid.

Example 2.1. Deactivation of the initial nuclear power plants containing radionuclides and boric acid in an amount of at least 5B g/l.

For deactivation, 1.75mM of the acidic initial RRV of the NPP was taken, which had a pH of about 5 and contained 27g/l of boric acid, 42.3g/l of sodium ions, 10.1g/l of potassium ions, and 0Og/l of chlorine ions. , 17.50g/l of sulfate ions, 34.8g/l of nitrate ions and 1.1g/l of carbonate ions. According to gamma spectrometric analysis, such radionuclides were present in the solution as 737Sv at the level of 1.2:109Bq/l, 734Sv - 2.02.10"Bq/l and Co - 4.56-.109Bq/l. Because deactivation was carried out in the equipment listed below.

At the first stage, a portion of RRV was selected within 9 hours. once passed with a consumption of about 2O0l/min. through six sorption columns heated to a temperature of no more than 609C, containing a total of 9bkg

St-selective sorbent FC-M. At the exit from the columns, partially deactivated RRV contained 4.OBq/l of 137Sv8, less than 0.6bBq/l. 134Sv and 4.2.106Bq/l of CO. Taking into account the sorption capacity of the FC-M sorbent, it was established that the indicated 9bkg are sufficient for the deactivation of 3000m of RRV.

The solution practically purified from cesium radionuclides, in which boric acid and the above-mentioned cations and anions remained, was pumped into a mixing tank with a capacity of 2.B5m3.

Into this mixing tank with intensive stirring for 12 minutes. bkg of soda ash (Ma»SoOz) were introduced.

The alkaline solution, which had a pH of 59, was pumped through a flow-through induction heater equipped with short-circuited conductive heating elements capable of mechanically vibrating in an alternating electromagnetic field for 5 Ohv. in the circulation mode with a consumption of approximately 15 l/min. at a temperature not higher than 602C. Thus, all components of the solution underwent compatible thermal, mechanical and electromagnetic treatment in an alternating electromagnetic field. Treatment of the solution was stopped after it became turbid due to the formation of 70 finely dispersed particles of water-insoluble carbonates and/or hydrated oxides of the MechOupNiO type, mainly of such metals as iron and cobalt.

The resulting suspension was passed through a filter with an average hole size of no more than microns. As the sediment accumulated, it was periodically dumped into an intermediate receiver, and the filtrate was poured into a collection tank with a capacity of BM3.

In total, we received about 33.1 liters of sediment in the form of an ointment-like suspension, which contained 17.9 g of hydrated iron oxide and 8.90-1077 g of carbonate bSo. This suspension was transferred to a container-evaporator for accumulation and further burial of TRV. In particular, 19.98 g of TRV were obtained from the indicated volume of suspension.

The water vapor was condensed and poured into the mixer tank mentioned above.

The practically deactivated filtrate containing background amounts of radionuclides (namely: 4.3Bq/l 137Sv, about 9.5Bq/l 13485 and about 2.4Bq/l 90Co) was dumped into a 2mU evaporator tank connected to a water ring vacuum pump with a productivity of 35 m3/h, acidified to pH 5 and evaporated under vacuum at a residual pressure of no higher than 4 ΩmHg. (5 Zmbar) to obtain 350 l of a solution with a concentration of boric acid of 150 g/l.

This solution was fed into a crystallizer with a capacity of 2.5 mU, where, after cooling to a temperature of 10 °C, most of the boric acid (Zbkg based on dry matter) precipitated, which was almost completely purified from radionuclides 99Co and 1348 and contained about 65Bq/ kg 73'Sv, which is significantly lower than the MPC. This sediment was dried and transferred to the warehouse.

The mother liquor was evaporated under vacuum and a dry mixture of salts was obtained in the amount of 185.45 kg, which was transferred to storage. This portion of the mixture contained 9.OOkg of boric acid, 63.5Okg of sodium ions, 15.0Okg of potassium ions, 1.35kg of chlorine ions, 43.75kg of sulfate ions, 52.20kg of nitrate ions, 1.65kg of carbonate ions and impurities "Z "Sv, З4Svib0Со at the level (/Ж7 less than the MPC, which are established by the "Radiation Safety Norms of Ukraine" for each of these radionuclides. со

The water obtained during the experiment in the amount of about 1.5 m7 was poured into the general factory sewer.

Example 2.2. Deactivation of Zbokg water obtained by evaporation of chemically unbound water from the original RRV

Zaporizhzhia NPP (Ukraine). with

This portion of the float contained 111.6 bkg of boric acid (H zVO»z), 80.28 kg of sodium ions, 19.8 kg of potassium ions, 0.009 kg

From iron ions, 1.8 kg of chlorine ions, 34.2 kg of sulfate ions, 64.0 kg of nitrate ions and water of crystallization - up to Zbokg. co

According to gamma spectrometric analysis, such radionuclides were present in the water as C7C3 at the level of 5.18.109Bq (1.439 10"Bq/kg), Sv - 8.6810 "Bq (2.41.109UBq/kg) and Co - 1 ,9610 "Bq (5.44 107 Bq/kg).

The following equipment was used for decontamination. "

The indicated ZbOkg swim for 50 minutes. was dissolved in 700 l of 0.01956 aqueous solution of nitric acid in the -o s circulation mode with a flow rate of 15 l/min through a flow induction heater, which maintained a temperature of about 902 with a power consumption of no more than 20 kW. The resulting solution had a pH of no more than 5 and contained 159.00 g/l boric acid, 114.7 g/l sodium ions, 28.30 g/l potassium ions, 2.57 g/l chlorine ions, 48.85 g/l sulfate - ions and 94.42 g/l of nitrate ions.

This solution was poured into an intermediate heat-insulated tank with a capacity of 2 m3, where the temperature was maintained at no lower than 60 °C, and then pumped into a crystallizer with a capacity of 2.5 m"U, where, after cooling to a temperature of 102 °C, most of the boric acid (8 bkg) fell into a precipitate, which was practically free from the radionuclide Co, but contained a noticeable admixture of "Z"Cv and "Cv, o". Next, the wet precipitate of boric acid was transferred to a device for washing, and the acidic supernatant liquid, which at CO 50 had a pH of about 5 and contained ions of Ma, K" , SI", 80.2, MOz and radionuclides "Sv, 13'Sv and b0Sbo, were pumped into the gas tank-mixer.

In the device, which consisted of two flow vessels with a capacity of ZOOl and 100 l, respectively, five heated sorption columns filled with FC-M sorbent, each with a capacity of 1bl and a pump, boric acid was washed with 5B of 13 liters of technical water.

This water is in the circulation mode with a consumption of approximately 5bl/min. passed three times through the indicated columns at

HF) at a temperature of about 602C. t The washed boric acid was removed and dried to a constant mass in the amount of 85 kg. According to radiological research, this by-product was chemically pure and contained 7Z/Sv ions in a concentration of 60-7OBk/kg, while 60 impurities of radionuclides 134Sv and 9Co were practically absent. Therefore, boric acid regenerated in this way can be admitted for free sale on the chemical market.

The washing water can be used many times until it is saturated with such an amount of potassium ions that it can interfere with the effective sorption of radionuclides 148 and 137С5, and then it is poured into the mixer tank mentioned above and combined with the supernatant liquid from the boric acid crystallizer. 65 About two kilograms of caustic soda Ma»CO»z were introduced into the supernatant liquid in the mixing tank with stirring for 15 minutes and the pH was brought to 9. The resulting alkaline solution was treated for 5 hours. in the circulation mode with a consumption of approximately 15 l/min. in induction heating at a temperature not higher than 602 to a slight cloudiness. This testified to precipitation of water-insoluble carbonates and/or hydrated oxides of the MechOuu pH2oO type, mainly of such metals as iron and cobalt.

The resulting suspension was passed through a filter with an average pore size of no more than microns. As the sediments accumulated, they were periodically dumped into an intermediate receiver, and the filtrate was poured into a collector with a capacity of BM3.

In total, about 3 ml of sediment was obtained in the form of a suspension, which contained 18 g of hydrated iron oxide and 8.92:107 g of CO carbonate. This suspension was transferred to a container-evaporator for accumulation and further burial of TRV. In particular, 20.00 g of TRV was obtained from the indicated volume of suspension. Water vapor was condensed 70 and merged into the collection mentioned above.

The liquid in the collection was diluted 2.5 times with technical water and a solution was obtained that had a pH of less than 9 and contained 14.6 g/l. NzVO»z, 47.1g/l of sodium ions, 11.Zg/l of potassium ions, 1.0Zg/l of chlorine ions, 19.5g/l. sulfate ions, 37.8 g/l of nitrate ions and 1.6 g/l of carbonate ions with an admixture of radionuclides 137Sv and 134Sv,

Diluted solution within 9 hours. once passed with a consumption of about 2O0l/min. through six heated 19 to a temperature of no more than 602C columns, containing a total of 9bkg of SS-selective sorbent FC-M. At the exit, the solution contained "Z/Sv - 8.37Bq/l and So - 8.38Bq/l, and "Sv was not determined. Taking into account the sorption capacity of the FC-M sorbent, it was established that the indicated 9 bkg are sufficient for the deactivation of 50 tons of float.

A practically deactivated solution with a volume of about 1.75 m3 was heated for 2 hours and 25 minutes to a temperature of no higher than 7022 in recirculation mode through an induction heater, and then discharged into an evaporator tank with a capacity of 2 m3, connected to a water ring vacuum pump with a capacity of 35 m3/h. and the water was finally evaporated at a residual pressure of no higher than 4 OmmHg. (5Zmbar), releasing the main part of water vapor into the condenser through the salt separator.

The water obtained in the amount of 1.52 m? can be used to dissolve the following portions of the melt, or to dilute the filtrate. The water obtained in the course of the experiment was poured into the general plant sewer.

The dry mixture of salts in the amount of 225 kg was transferred to storage. This portion of the mixture contained 25.00 kg of boric acid, 80.28 kg of sodium ions, 19.8 kg of potassium ions, 1.8 kg of chlorine ions, 34.20 kg of sulfate ions, 4 kg of nitrate ions, 1.32 kg of carbonate ions and an admixture " Z/Sv, 134Sbv and b0bo at a level less than the MPC for each of these radionuclides.

According to the Radiation Safety Standards of Ukraine (NRBU-97), the permissible total activity of water for cobalt and cesium, which can be discharged into the drainage system, should not exceed 87 Bq/l.

The activity of solid materials of the 1st class should not be more than 37OBk/kg. Such materials can be used for all types of construction work without restrictions.

The activity of materials of the 2nd class must be at least 37 OBq/kg, but not more than or equal to 740 OBq/kg. Such cm materials can be used: (se) a) for industrial construction; b) for road construction.

The activity of materials of the 3rd class may exceed 740 OBq/kg, but must not be more than or equal to 1350 Bq/kg. Such materials are used: a) outside settlements: for the construction of underground structures covered with a layer of earth more than 0.5 m thick, where long-term stay of people (less than half of the working day) is excluded; h b) outside the population centers: for the construction of roads, for the construction of dams, for the construction of other objects with a short stay of people. (COLLECTION of important official materials on sanitary and anti-epidemic issues. Official publication in nine volumes. Volume 7, Part 1 - Kyiv: Ministry of Health of Ukraine, 1998, p. 153-271). (ee) As can be seen from the examples given, any products of decontamination of arbitrary RRV by the proposed method t have radioactivity lower than the lowest limit established by NRBU. i-th

Claims (1)

The formula of the invention of - 1. The method of liquid radioactive waste (LRW) deactivation, which includes: selection of a portion of the initial RRV for deactivation, introduction of a source of carbonate ions into the selected portion of the initial RRV until an alkaline reaction is reached, simultaneous thermal, mechanical and electromagnetic treatment of the mixture in an induction heater, in the body of which is equipped with at least one short-circuited electrically conductive heating element capable of mechanically (F, vibrating in an alternating electromagnetic field, Go) separation of cobalt radionuclide and other metal impurities in the form of a dispersed precipitate of water-insoluble carbonates and/or hydrated metal oxides of the MechOu pH2oO type that fell as a result of the specified processing, because the introduction of the mother liquor remaining after the separation of the specified sediment into contact with the Сv-selective sorbent for a time sufficient to reduce the concentration of cesium radionuclides to a level below the maximum permissible concentration (MPC), processing of the spent sorbent and the above-mentioned sediment MechOupNoO in compact vol verdi radioactive waste (TRW) for further burial. bo 2. The method of liquid radioactive waste deactivation, which includes: selection of a portion of the acidic source RRV of a nuclear power plant (NPP) containing boric acid, corrosion products of the cooling system of a power nuclear reactor and at least such radionuclides as 1378, 13478 and bos, introduction of the selected portion of RRV into contact with the SS-selective sorbent at a temperature of no more 60 2С for a time sufficient to reduce the concentration of cesium radionuclides to a level below the MPC, introduction of a source of carbonate ions into liquid radioactive waste practically purified from radionuclides Z/Sv and 134C8 until an alkaline reaction is reached, simultaneous thermal, mechanical and electromagnetic treatment of the mixture in an induction heated, in the housing of which at least one short-circuited conductive heating element capable of mechanically vibrating in an alternating electromagnetic field is installed in the housing 70, separation of cobalt radionuclide and other metal impurities in the form of a dispersed precipitate of water-insoluble carbonates and/or hydrated metal oxides of the MechOu pH2oO type, which fell into as a result of the specified processing partial evaporation of the practically deactivated mother liquor to obtain a concentrated solution of boric acid with impurities of mineral salts, cooling of the specified solution until the precipitation of boric acid precipitates, separation of the practically deactivated boric acid precipitate for further utilization, evaporation of the mother liquor under vacuum to obtain a practically deactivated dry mixture of salts and processing of the spent sorbent and the above-mentioned MechOu pNoO sediment into compact TRVs for further burial. 3. The method of liquid radioactive waste deactivation, which includes: selection of a portion of liquid radioactive waste, regeneration of liquid radioactive waste by dissolving the selected portion of liquid radioactive waste in acidified water in the circulation mode through a flow induction heater that maintains the temperature below the boiling point of water, with 29 cooling of the resulting solution until precipitation boric acid precipitate, which is practically purified from He) radionuclide Co and contains an admixture of radionuclides "Z/Sv and Sv, separation of the boric acid precipitate, its washing from the indicated impurities in a closed circuit with precipitation of radionuclides 737Sv and 134С5 on a Sv-selective sorbent and drying of the washed sediment to a constant mass, "- from the introduction of a source of carbonate ions into the supernatant liquid, which remained after the separation of the boric acid sediment, until the alkaline reaction is reached, from the simultaneous thermal, mechanical and electromagnetic treatment of the mixture in an induction heater, in the body of which at least one short-circuited conductive heating element, capable of mechanically vibrating in an alternating electromagnetic field, with the separation of cobalt radionuclide and other metal impurities in the form of a dispersed precipitate of water-insoluble carbonates and/or hydrated metal oxides of the MechOu pNos type that fell out as a result of the specified treatment, at least a two-fold dilution of the remaining mother solution after separation of the specified sediment, the introduction of the obtained diluted solution into contact with a C-selective sorbent at a temperature below the boiling point of water for a time sufficient to reduce the number of cesium radionuclides to a level below the maximum permissible concentration, - with evaporation of the solution purified from cesium radionuclides under vacuum to obtaining a practically deactivated dry mixture of salts and processing of the spent sorbent and the above-mentioned sediment of MechOupNoO into compact solid radioactive waste for further burial. 4. The method according to claim 3, in which the water obtained by evaporation of the deactivated salt solution is used (se) to dissolve the following portions of the melt or to dilute the filtrate. 5. The method according to claim 3, in which the solution purified from cesium radionuclides, before evaporation under vacuum, is heated for at least two hours at a temperature below the boiling point of water in an induction heater, in the body of which at least one short-circuited electrically conductive heating element capable of mechanically vibrating is installed in an alternating electromagnetic field. with b. The method according to claim 1 or according to claim 2 or according to point 3, in which the source of carbonate ions is selected from the group consisting of sodium bicarbonate, sodium carbonate, lithium bicarbonate, lithium carbonate and potassium carbonate. Official Bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2008, M 8, 25.04.2008. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. io) because b5