GB2583276A

GB2583276A - Method and system for concentrating and solidifying nuclides in radioactive liquid waste

Info

Publication number: GB2583276A
Application number: GB2009626.9A
Authority: GB
Inventors: Zhao Xuan; Li Fuzhi; Wei Jiying; Zhang Meng
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2018-01-03
Filing date: 2018-11-07
Publication date: 2020-10-21
Anticipated expiration: 2038-11-07
Also published as: CN109994238B; WO2019134436A1; CN109994238A; GB202009626D0; GB2583276B

Abstract

The present invention relates to a method and system for concentrating and solidifying nuclides in radioactive liquid waste. The method for concentrating and solidifying nuclides in radioactive liquid waste of the present invention comprises the following steps: step 1) pretreatment: the radioactive liquid waste is subjected to extraction using a first selective extraction agent; step 2) concentration: the extracted radioactive liquid waste is subjected to reverse osmosis concentration; step 3) extraction: the enriched radioactive nuclides in the concentrated solution are extracted into a solid phase using an organic ion exchange resin and/or a second selective extraction agent; and step 4) solidification of nuclides: the nuclide-enriched organic ion exchange resin and/or second selective extraction agent obtained in step 3) and the first selective extraction agent obtained in step 1) are then allowed to form a solidified body. By means of the method and system of the present invention, the radioactive nuclides in the radioactive liquid waste can be effectively extracted and concentrated and stored safely, and at the same time, the minimization of the storage volume of the radioactive waste is achieved.

Description

METHOD AND SYSTEM FOR CONCENTRATING AND SOLIDIFYING RADIONUCLIDES IN RADIOACTIVE WASTE LIQUID

CROSS-REFERENCE TO RELATED APPLICATIONS

100011 This application claims the priority of Chinese patent application No. 201810006458.6 filed on January 3, 2018, the entire content of which is hereby incorporated by reference.

TECHNICAL FIELD

100021 The invention refers to method and system for concentrating and solidifying radionuclides in radioactive waste liquid.

BACKGROUND

100031 Nuclear power, as an important clean energy source, is gradually becoming an important part of the world's energy supply. After the Fukushima nuclear accident in Japan, nuclear safety has become a major concern in the development of nuclear energy. In the daily operation and accident conditions of nuclear power plants, a large number of radioactive waste liquids are usually generated.

100041 There are two main sources of radionuclides (also referred to as radioactive nuclides) contained in radioactive waste liquids. The first source is from the products of fission and the second source is from the products of activation and corrosion. The second source is mainly related to activation, corrosion, precipitation and release behaviors of the metal materials. Radionuclides from the second source include nuclides such as Ag, Co, Cr, Mn, Fe and the like. In the event of fuel leakage, long-lived fission products with beta radioactivity, such as 134CS/37CS, 90Sr and the like, appear in the radioactive waste liquid. Radionuclides with a long half-life need to be separated from the waste liquid, isolated from the environment, and stored for a long time, until they decay to a harmless level.

[0005] Due to high cost of long-term geological storage and disposal of radionuclides, the capacity of temporary depository or disposal site is limited. Generally, radioactive waste liquids need to be concentrated and reduced in volume to minimize volume as long as possible for long-term storage. At present, in nuclear power plants, methods for concentrating nuclides in radioactive waste liquids mainly comprise evaporation concentration and ion exchange. No matter which treatment method is applied, the radionuclide is essentially concentrated in a liquid medium or a solid medium, which is finally solidified and subjected to long-term geological storage. Evaporative concentration is the redistribution of radionuclides between the distillation residue and the condensed liquid to obtain a distillation residue containing most of radionuclides and a condensed liquid with a low amount of radionuclides. Ion exchange is the process in which radionuclides are accommodated in ion exchange materials.

100061 Evaporation concentration and ion exchange have a wide range of applications in the treatment of radioactive waste liquids, with their own advantages and disadvantages.

The evaporation process has the advantages including mature technology, strong decontamination ability, and the minimized production of the radioactive waste; and the disadvantages including high energy consumption, large/complicated equipment, high investment, poor operating conditions, and serious problems such as corrosion and scaling.

In contrast, the ion exchange process has the advantages including low energy consumption, simple equipment, and convenient operation; and the disadvantage including the production of a large number of radioactive waste ion exchange resins, which are difficult to be handled and disposed.

100071 In the design of three generations of nuclear power plants, the evaporation process has been gradually quitting, and the ion exchange process has become the main process. However, during the concentration of the radionuclides, the existing ion exchange process in nuclear power plants must ensure that the discharged liquids meet environmental discharge requirements. This would impose a very high requirement on the decontamination coefficient of resins, and thus the adsorption capacity of the resins cannot be fully utilized, resulting in a large number of radioactive waste resins and putting more pressure on long-term storage in the later stage.

100081 Treatment of radioactive waste liquid itself has many difficulties, mainly in the following aspects: [0009] 1) Radioactive waste liquid from nuclear power plant contains hundreds of nuclides, including Na-24, Cr-51, Mn-54, Fe-55, Fe-59, Co-58, Co-60, Zn-65, Sr-89, Sr- 91, Zr-95, Nb-95, Mo-99, Tc-99m, Ru-103, Ru-106m, Ag-110m, Te-129m, Te-129, Te131m, Te-131, Te-132, Cs-134, Cs-137, Ba-140, La-140, Ce-141, Ce-143, Ce-144, W-187, Np-239 and the like. The properties of each of nuclides (such as concentration and enrichment properties, speciation, ion concentration, valence, corrosivity, and the like) are very complicated and may vary under different operating conditions (such as pH, ionic strength, temperature, and the like), which make more difficult in concentration and enrichment of nuclides.

100101 2) The mass concentrations of radionuclides are extremely low, generally not higher than 10-3 gg/L, while the concentrations of co-existing non-radioactive ions such as K, Na, Ca, and Mg are relatively high, generally in the order of milligrams per liter, even up to the order of grams per liter. The presence of these non-radioactive ions severely affects the concentration and solidification of the nuclides in radioactive waste liquid.

100111 3) The amount (especially the volume) of radioactive waste needs to be reduced as much as possible, so that the nuclides in radioactive waste liquid are concentrated at a higher recovery ratio.

100121 4) The production of secondary radioactive waste liquid should be avoided.

100131 5) It is necessary to comprehensively consider factors, such as operability and maintainability of equipments under radioactive conditions, power consumption, species of nuclides, and concentrations, at the same time.

100141 6) In the case where the process is simplified as much as possible, it is difficult to coordinate the various treatments with each other, and efficiently concentrate the nuclides in radioactive waste liquid.

100151 At present, the above problems cannot be properly solved by using the existing method or system for concentrating and solidifying radionuclides in radioactive waste liquids in the art.

SUMMARY

10016:I The present invention refers to method and system for concentrating and solidifying radionuclides in radioactive waste liquid.

100171 An aspect of the invention is to provide a method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the following steps: 100181 1) pretreatment: extracting the radioactive waste liquid with a first selective extracting agent, thereby obtaining an extracted radioactive waste liquid; [00191 2) concentration: subjecting the extracted radioactive waste liquid to reverse osmosis concentration, thereby obtaining a retentate and a permeate; 100201 3) extraction: extracting the radionuclides enriched in the retentate (or the concentrate) into a solid phase with a first ion exchange resin and/or a second selective extracting agent; 100211 4) solidifying nuclides: rendering the nuclides-rich organic ion exchange resin and/or second selective extracting agent obtained from step 3) and first selective extracting agent obtained from step 1) to form a solidified body.

100221 Another aspect of the invention provides a system for concentrating and solidifying radionuclides in radioactive waste liquid, comprising: 100231 a) a pretreatment unit, comprising a first selective extracting agent; 100241 b) a concentration unit, comprising a concentrating tank equipped with a reverse osmosis device, so that the retentate from the reverse osmosis device is recycled back to the concentrating tank, and the water outlet of the pretreatment unit is connected to the inlet of the reverse osmosis device; [00251 c) an extraction unit, comprising an organic ion exchange bed and/or second selective extracting agent, wherein the water inlet of the extraction unit is connected to the concentrating tank so that the liquid in the concentrating tank enters the extraction unit, the water outlet of the extraction unit is connected to the concentrating tank so that the liquid passing though the extraction unit is recycled back to the concentrating tank; 100261 d) a unit for solidifying nuclides, where nuclides-rich selective extracting agent and/or nuclides-rich organic ion exchange resin form a solidified body.

100271 In the method and system according to the invention, the first selective extracting agent for pretreatment and the second selective extracting agent for extraction may be the same or different. The selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides, or each independently comprise molecular sieve or zeolite or zeolum.

100281 The inventors have surprisingly found that by the method and system according to the present invention, radionuclides in radioactive waste liquids can be efficiently concentrated and extracted for safe storage while minimizing radioactive waste.

The method and system according to the invention not only fully utilize the adsorption capacity of resin to minimize the production of radioactive waste resin, but also ensure that the discharged liquid meets environmental discharge requirements. The method and system according to the invention exhibit the advantages of low energy consumption, simplified equipment, convenient operation, and small volume of radioactive waste after concentration and solidification.

100291 As compared with the existing concentration methods and systems, the invention provides novel method and system for concentrating nuclides in radioactive waste liquids for storage, having at least the following inventive aspects: 100301 I) Reasonable and optimized combination of processes. In the art, radioactive waste liquids have extreme distinctiveness. Some technical processes show very different behaviors in view of the treatment of a non-radioactive liquid and the treatment of a radioactive liquid. In absence of actual operation and testing of radioactive experiments, the designed combination of processes often differs greatly from under the actual conditions. Moreover, there is a wide gap between a laboratory scale and a real industrial scale, which are incomparable. In the method and system of the present invention, the steps or units can be coordinated with each other in an effective way to form an integrated method and system. The results show that the invention refers to a demonstration project. This demonstration project is currently the only demonstration project that is completed by using real radioactive liquids in the nuclear power plant in China. Under the radioactive conditions, the inventors repeatedly combined, tested, adjusted, and verified individual units in the demonstration engineering prototype, and finally obtained the most effective method and system in an organically integrated whole, in which the mutual cooperation between the units is optimal to achieve the functions that cannot be achieved by merely a simple combination of individual units.

100311 2) There are hundreds of species of nuclides in radioactive waste liquid from nuclear power plant. Through the research on the concentration and enrichment properties of single-component nuclide and multi-component nuclides in individual units, including the laboratory simulation of concentration and solidification of nuclides in radioactive waste liquid and the verification on radioactive liquid in demonstration project of a real nuclear power plant, the inventors have found for the first time that among the hundreds of species of nuclides, several species of nuclides, especially Cs, could not be effectively concentrated by reverse osmosis; however, the aim of enrichment can be achieved upon adding selective extracting agent. It has also been found that two special nuclides, Ag and Co, cannot be effectively concentrated by ion exchange resin; however, the aim of enrichment for both nuclides can be achieved after oxidation, treatment with a selective extracting agent and an ion exchange resin. The concentration of some nuclides such as Sr by the ion exchange resin would suffer from the competition of divalent cations present in the solution, thereby shortening the service life of resin, but addition of a selective extracting agent can facilitate the overall volume reduction of radioactive waste. In view of the concentration properties of various nuclides, the inventors design the method and system for concentrating and solidifying, to well achieve the efficient concentration and solidification of various nuclides.

[0032] 3) Since the evaporation is not necessary in the method of the invention to achieve concentration in radioactive waste liquid, the method and system are highly simplified and represents obvious advantages in size, operability, maintainability, power consumption, and the like of equipments, as compared with other methods/systems [0033] 4) Through the reasonable setting of the process in which ion exchange resin functions to concentrate and contain radionuclides, so there is no particularly high requirement for the decontamination coefficient of resin itself In this way, the adsorption capacity of the resin can be fully utilized, and the production of radioactive resin can be greatly reduced.

[0034] 5) The method and system according to the invention provide a recovery ratio of 95% or higher of nuclides in the radioactive waste liquid while ensuring that the discharged liquid meets environmental discharge requirements.

[0035] 6) The method and system according to the invention have not been reported in China or other countries. The specific combination employed in the invention provides a groundbreaking design concept for the recovery of nuclides in the radioactive liquids.

DETAILED DESCRIPTION

[0036] The method and system for concentrating and solidifying radionuclides in radioactive waste liquid according to the invention are further described below.

[0037] One aspect of the invention provides a method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the steps: I) pretreatment: extracting the radioactive waste liquid with a first selective extracting agent, thereby obtaining an extracted radioactive waste liquid; 2) concentration: subjecting the extracted radioactive waste liquid to reverse osmosis concentration, thereby obtaining a retentate and a permeate; 3) extraction: extracting the radionuclides from the concentrate with an organic ion exchange resin and/or a second selective extracting agent; 4) solidifying nuclides: rendering the nuclides-rich organic ion exchange resin and/or second selective extracting agent obtained from step 3) and the first selective extracting agent obtained from step 1) to form a solidified body.

100381 In the method of the invention, the selective extracting agent in step 1) is mainly useful for extracting those nuclides in radioactive waste liquid which may have difficulty in being rejected by membrane, especially nuclide Cs in radioactive waste liquid which may have difficulty in being rejected by membrane. The inventors found for the first time that among the hundreds of species of nuclides, several species of nuclides, especially Cs, could not be effectively concentrated by reverse osmosis, also referred to as "nuclides having difficulty in being rejected by membrane". According to the invention, some nuclides having difficulty in being rejected by membrane, such as Cs, could be effectively enriched by treating with selective extracting agent prior to reverse osmosis treatment. The selective extracting agent in step 3) could be useful for extracting the -nuclides having difficulty in being rejected by membrane" and nuclides which tend to compete with divalent cations, thereby facilitating the miniaturization of the total radioactive waste.

100391 In some preferred embodiments, in step 3), before extraction of nuclides, the concentrate is treated to remove organic materials in liquid. Preferably, activated carbon is used. The inventors have surprisingly found that by removing organic materials from concentrate, the enrichment of organic materials in concentrate is avoided, thereby further improving stability of the system.

[0040] In a preferred embodiment, the pretreatment further comprises oxidizing the nuclides in the radioactive waste liquid to convert them into ionic form, preferably with ultraviolet light, ozone, hydrogen peroxide, and/or sodium hypochlorite, prior to the extracting in step 1).

100411 The liquid may be filtered during all of the stages of the process of the invention (e.g., prior to extracting or oxidizing of step 1)). Preferably, filtration is carried out with flocculation, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device, or any combination thereof, to remove fine suspended solids and colloidal materials.

100421 During the oxidation, photocatalytic oxidation is preferably employed with ultraviolet light. As an oxidant, I-1202, ozone and/or sodium hypochlorite may be used.

Preferably, H202 is used. In some embodiments, the oxidant dosage is controlled in a range of between 2 and 30 mg/L, preferably between 3 and 25 mg/L, more preferably between 5 and 20 mg/L, for example 10 mg/L or 15 mg/L.

10043_1 As used herein, the term "selective extracting agent" is a class of materials that are capable of selectively extracting and enriching nuclides.

[0044] In some embodiments of the invention, selective extracting agent comprises an inorganic oxide carrier and an active component for extracting the nuclides. Preferably, the inorganic oxide carrier comprises silica, manganese dioxide, aluminum oxide, titanium oxide, zirconium oxide, or any combination thereof Preferably, the active component for extracting the nuclides comprises ferrocyanides, antimonates, titanates, tin oxide, tungstates or any combination thereof Most preferably, selective extracting agent comprises silica, aluminum oxide, ferrocyanides and antimonates.

100451 In other embodiments, selective extracting agent comprises molecular sieve. As a selective extracting agent, cerium zirconium solid solution, natural or synthetic clinoptilolite, NaY molecular sieve, 13X molecular sieve, ZSM-5 molecular sieve, SAPO- 34 molecular sieve, R molecular sieve, chitosan adsorbent, montmorillonite, hydrated manganese oxide, titanium silicalite molecular sieve, metal stibiate, hydrated tin oxide or sodium titanate or any combination thereof may also be used.

100461 The inventors have also found that when the components for constituting a selective extracting agent comprise silica, aluminum oxide, titanium oxide, ferrocyanides and antimonates, the recovery ratio of nuclides in the radioactive waste liquid can be further improved.

[0047] In this disclosure, reverse osmosis concentration is carried out in a concentrating tank. In a preferred embodiment, reverse osmosis concentration may also be carried out in multi-stage liquid tank comprising a concentrating tank and a medium concentrating tank. In a concentrating tank, liquid may be subjected to one or more stages of reverse osmosis concentration, such as two stages or three stages of reverse osmosis concentration. In multi-stage reverse osmosis concentration, the permeate from each stage of reverse osmosis sequentially enters the next stage of reverse osmosis, the retentate in each stage of reverse osmosis is recycled back to the concentrating tank, and the final permeate leaves the concentrating tank. In some embodiments, the ratio of dilute water and concentrated water produced in each stage of reverse osmosis is independently controlled, preferably between 11 and 8:1, for example 3:1 or 5:1. The dilute water produced in the first stage of reverse osmosis has a conductivity of lower than or equal to 50 pS/cm, for example 40µS/cm, 35 pS/cm, 30 µS/cm, and 25 pS/cm. The produced dilute water after two or more stages of reverse osmosis has a conductivity of lower than or equal to 25 µS/cm, for example 20 µS/cm, 15 pS/cm, 11 pS/cm, and 10 pS/cm. During reverse osmosis concentration, the final permeate has a microorganism parameter of total bacterial count of lower than 200 CFU/mL, preferably lower than 100 CFU/mL.

[0048] In some embodiments, the liquid produced during reverse osmosis concentration (i.e., the final permeate) is subjected to deionization. The concentrated water after the liquid purification is recycled back to the concentration step. In some preferred embodiments, the method of the invention further comprises step 5) of liquid purification: subjecting the permeate obtained from step 2) to deionization, and recycling the radionuclides-rich concentrated water obtained from the liquid purification back to step 2). Preferably, continuous electrodeionization purification is carried out. In a preferred embodiment, in continuous electrodeionization, the anode is made of a pure titanium plate electrode and the cathode is made of a stainless steel plate. In the continuous electrodeionization unit, a volume ratio of the dilute water to the concentrated water is in a range of from 0.5:1 to 10:1, preferably from 1:1 to 5:1, such as 3:1. The dilute water after the deionization purification meets environmental discharge.

[0049] In this disclosure, the concentrate from reverse osmosis concentration is extracted with an organic ion exchange resin and/or a selective extracting agent.

Preferably, before the extracting step, the concentrate is treated with activated carbon to remove organic materials in the concentrate, and avoid the enrichment of organic materials in the concentrate, and thus further improve the stability of the system. Ion exchange resin bed and optional selective extracting agent may be used at one stage, two or more stages.

When two or more stages of ion exchange resin beds and optional selective extracting agents are used, the retentate sequentially passes through the stages of ion exchange resin bed and the stages of selective extracting agent. In the ion exchange bed, mixed cation and/or anion ion exchange resins could be employed. Preferably, cation exchange resin is used in hydrogen form, and anion exchange resin is used in hydroxylic form. Based on the present disclosure, a person skilled in the art would be able to reasonably determine the particular ion exchange resin.

[0050] In some embodiments, the concentrate of reverse osmosis concentration is pumped into an organic ion exchange bed and a selective extracting agent bed. When a selective extracting agent is used in an extracting step, the selective extracting agent(s) as described above may be used. The first selective extracting agent for pretreatment and the second selective extracting agent for extraction may be the same or different. The selective extracting agents for extraction in stages may be the same or different. After the extracting step, the final effluent has a pH value of between 6 and 8, and is recycled back to the concentrating tank.

[0051] The flow rate of the liquid in the pretreatment is not critical. It can be determined according to actual needs and may be any value. In some exemplary embodiments of the invention, the liquid in the pretreatment has a flow rate in a range of from 0.05 m3/h to 10 m3/h, for example from 0.1 m3/h to 5 m3/h, for example, 0.2 m3/h and 1 m3/h.

[0052] In some preferred embodiments, nuclides-rich selective extracting agent and/or nuclides-rich ion exchange resin are stirred with cement, or are dehydrated and dried, in order to form a solidified body.

[0053] In a particularly preferred embodiment, the invention provides a method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the steps: [0054] 1) pretreatment: catalytically oxidizing the radioactive waste liquid with IMO) under ultraviolet light, followed by extracting it with a first selective extracting agent; [0055] 2) concentration: carrying out at least two stages of reverse osmosis concentrations in a concentrating tank, thereby obtaining a retentate and a permeate in each stage, wherein the permeate from each stage of reverse osmosis sequentially enters the next stage, and the retentate from each stage of reverse osmosis is recycled back to the concentrating tank; [0056] 3) extraction: extracting the retentate in the concentrating tank obtained from step 2) with two or more stages of the organic ion exchange resins and/or the second selective extracting agents, wherein the retentate sequentially passes through the stages of ion exchange resins and/or the second selective extracting agent, and the final effluent is recycled back to the concentrating tank; 100571 4) solidifying nuclides: rendering the first selective extracting agent obtained from step I) and/or the second selective extracting agent and/or the organic ion exchange resin obtained from step 3) to form a solidified body; 100581 wherein the selective extracting agents comprise an inorganic oxide carrier and an active component for extracting nuclides, the inorganic oxide carrier comprises silica, aluminum oxide, titanium oxide or any combination thereof, and the active component for extracting nuclides comprises ferrocyanides and/or antimonates.

100591 In an even more preferred embodiment, the invention provides a method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising step 3) extraction: extracting organic materials in the concentrate with activated carbon, followed by extracting the liquid in using two or more stages of organic ion exchange resins and/or second selective extracting agents, wherein the retentate sequentially passes through the stages of ion exchange resins and/or second selective extracting agents, and the final effluent is recycled back to the concentrating tank.

100601 Another aspect of the invention provides a method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the steps: 100611 I) pretreatment: introducing the waste liquid into an oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device, followed by adding 11,02; the effluent from the oxidizing device passes through a selective extracting agent comprising: i) silica, aluminum oxide, titanium oxide, zirconium oxide and any combination thereof; and, ii) ferrocyanides, antimonates, titanates, tin oxide, tungstates and any combination thereof; introducing the effluent after the treatment with selective extracting agent into a concentrating tank for step 2); 100621 2) concentration: subjecting to multi-stage reverse osmosis concentration in the concentrating tank, thereby obtaining a retentate and a permeate in each stage, wherein the permeate from each stage of reverse osmosis sequentially enters the next stage, and the retentate from each stage of reverse osmosis is recycled back to the concentrating tank; 100631 3) extraction: treating the liquid in the concentrating tank obtained from step 2) with an activated carbon to remove organic materials in the liquid, followed by pumping the treated liquid into a organic ion exchange bed comprising two or more stages of ion exchange resins, wherein the retentate sequentially passes through the stages of ion exchange resins, and the final effluent is recycled back to the concentrating tank; 100641 4) solidifying nuclides: rendering the selective extracting agent obtained from step 1) and/or the ion exchange resin obtained from step 3) to form a solidified body.

100651 In some preferred embodiments, when the conductivity of the effluent in the extracting/extraction step is greater than or equal to that of the concentrate in the concentrating/concentration step, or the conductivity of the final permeate in step 2) is higher than 50 RS/cm, the ion exchange resin (nuclides-rich ion exchange resin) and/or selective extracting agent in the first stage of bed in extracting step is subjected to step 4) of solidifying nuclides. Optionally, fresh ion exchange resin and/or fresh selective extracting agent are loaded as last stage of ion exchange resin and/or selective extracting agent, and other stages of ion exchange resins and/or selective extracting agents are moved forward sequentially.

100661 In some preferred embodiments, the ratio of the liquid discharged from step 5) to the liquid entering step 3) is controlled, preferably in a range of from 1 to 10:1, more preferably in a range of from 3 to 10:1, for example 3:1, 5:1 or 8:1. Controlling such ratio of the liquids may further achieve higher recovery ratio of nuclides, obtain a smaller volume of the solidified nuclides after the concentration, and further improve the concentration efficiency of the method and system of the present invention, meanwhile ensuring that the effluent after purification meets the environmental discharge requirements.

100671 In a particularly preferred embodiment, the invention provides a novel process for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the specific steps: 100681 1) pretreatment: first introducing the radioactive waste liquid into raw liquid tank, followed by removing fine suspended substances with flocculation, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device and the like, then introducing into an oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device, adding F1202 in a controlled dosage. The effluent flows through a selective extracting agent at a certain flow rate, then enters a concentrating tank for step 2). The selective extracting agent comprises: i) silica, aluminum oxide, titanium oxide, zirconium oxide and any combination thereof; and ii) ferrocyanides, antimonates, titanates, tin oxide, tungstates and any combination thereof 100691 2) concentration: a concentrating tank is equipped with high and low working liquid level switches and comprises multiple stages of reverse osmosis concentrations.

Permeate from each stage of reverse osmosis sequentially enters the next stage and finally enters step 5). Retentate from each stage of reverse osmosis is recycled back to the concentrating tank.

100701 3) extraction: pumping the liquid in the concentrating tank obtained from step 2) into organic ion exchange bed comprising mixed cation and/or anion ion exchange resins.

Cation exchange resin is used in hydrogen form, and anion exchange resin is used in hydroxylic form. The ion exchange resin bed comprises two or more stages of resins. The retentate sequentially passes through the stages of ion exchange resin bed. The final effluent has a pH value of between 6 and 8, and is recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed is not lower than that of the liquid in the concentrating tank, or the conductivity of the final permeate in step 2) is higher than 50 p.S/cm, the (nuclides-rich) ion exchange resin in the first stage of bed is fed into step 4) through a feed pump. Fresh resin is loaded as last stage, and other stages are moved forward sequentially.

100711 4) solidifying nuclides: feeding the selective extracting agent obtained from step 1) and the ion exchange resins obtained from step 3) into a standard barrel with a predetermined amount of cement via a feed pump, followed by stirring with the cement to form a solidified body, or by dehydrating, drying, and sending the mixture to a standard barrel for storage to form a solidified body.

100721 5) liquid purification: the permeate of reverse osmosis obtained from step 2) enters continuous electrodeionization. The residual radionuclides are enriched in the concentrated water of continuous electrodeionization, recycled back to the concentrating tank in step 2). The remaining liquid meets environmental discharge requirements. The ratio of the liquid discharged from step 5) to the liquid entering step 3) in concentrating tank is controlled in a range of from 1 to 10:1.

100731 In an even more preferred embodiment, the invention provides a novel process for concentrating and solidifying radionuclides in radioactive waste liquid, comprising step 3) extraction: pumping the liquid in the concentrating tank obtained from step 2) into an activated carbon bed, followed by pumping into an organic ion exchange bed.

100741 Another aspect of the invention provides a system for concentrating and solidifying radionuclides in radioactive waste liquid, comprising: 10075_1 a) a pretreatment unit, comprising a first selective extracting agent; 100761 b) a concentration unit, comprising a concentrating tank equipped with a reverse osmosis device, so that the retentate from the reverse osmosis device is recycled back to the concentrating tank, and the water outlet of the pretreatment unit is connected to the inlet of the reverse osmosis device; [00771 c) an extraction unit, comprising an organic ion exchange bed and/or second selective extracting agent, wherein the water inlet of the extraction unit is connected to the concentrating tank so that the liquid in the concentrating tank enters the extraction unit, the water outlet of the extraction unit is connected to the concentrating tank so that the liquid passing though the extraction unit is recycled back to the concentrating tank; 100781 d) a unit for solidifying nuclides, where the nuclides-rich selective extracting agent and/or nuclides-rich organic ion exchange resin form a solidified body.

100791 In some preferred embodiments, in the pretreatment unit, the system further comprises an oxidizing device at the upstream of the first selective extracting agent in the pretreatment unit. The oxidizing device is preferably equipped with ultraviolet light source or ozone oxidizing device. Preferably, the oxidizing device is equipped with a dosing device and an on-line pH controlling and measuring device.

100801 In some preferred embodiments, the system for concentrating and solidifying radionuclides in radioactive waste liquid in the invention comprises: 100811 a) a pretreatment unit, comprising a raw liquid tank and an oxidizing device.

The pretreatment unit may further comprise a selective extracting agent at water outlet; 100821 b) a concentration unit, comprising a concentrating tank equipped with at least two stages of reverse osmosis devices. The water outlet of the pretreatment unit is connected to the concentrating tank, and each stage of reverse osmosis device is connected to the concentrating tank so that the retentate from each stage of reverse osmosis device is recycled back to the concentrating tank; [00831 c) an extraction unit, comprising organic ion exchange bed loaded with mixed cation and/or anion ion exchange resin. The water inlet of the extraction unit is connected to the concentrating tank so that the liquid in the concentration unit enters the extraction unit, and the water outlet of the extraction unit is connected to the concentrating tank so that the liquid passing though the extraction unit is recycled back to the concentrating tank; 100841 d) a unit for solidifying nuclides, where nuclides-rich selective extracting agent and/or nuclides-rich ion exchange resin form a solidified body.

10085] In some preferred embodiments, a filtration device may be comprised in any unit. Preferably, the pretreatment unit further comprises a filtration device. More preferably, the filtration device is placed at the upstream of the oxidizing device or selective extracting agent. In some embodiments, the filtration device comprises flocculation device, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device or any combination thereof The filtration is carried out with flocculation, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device or any combination thereof, in order to remove fine suspended substances and colloidal materials.

100861 In the system of the invention, a high working liquid level switch, a low working liquid level switch or their combination are equipped in the concentrated tank.

100871 In some preferred embodiments, in the system for concentrating and solidifying radionuclides in radioactive waste liquid of the invention, an extraction unit comprises an activated carbon bed before the organic ion exchange bed and/or second selective extracting agent. As discussed above, organic materials in concentrate are removed in the extraction unit, preferably by using activated carbon, to avoid enrichment of organic materials in concentrate, and thus further improving the stability of the system 100881 In a preferred embodiment, the system of the invention further comprises e) a liquid purification unit. Liquid purification unit may comprise a deionization unit or consist of deionization units. The water inlet in liquid purification unit is connected to the concentration unit, so that the permeate after reverse osmosis device enters the liquid purification unit, and a concentrated water outlet of the liquid purification unit is connected to the concentration unit so that the concentrated water obtained from the deionization unit is recycled back to the concentrating tank.

100891 In a preferred embodiment, the deionization unit is a continuous electrodeionization unit. Preferably, in the continuous electrodeionization unit, the anode is made of a pure titanium plate electrode and the cathode is made of a stainless steel plate.

[0090] The inventors have surprisingly found that, the method and system according to the invention could achieve an optimal concentration effect and a highly simplified process. The recovery ratio of nuclides in the radioactive waste liquid is up to 95% or even 99.9%. All units build the most efficient integration system. In the method and system according to the invention, there is no specific requirement for the decontamination coefficient of resins, so that the adsorption capacity of resins can be fully utilized, and the production of the radioactive resin could be greatly reduced. The method and system according to the present invention could achieve the recovery of nuclides in radioactive waste liquids at very high recovery ratio, meanwhile ensuring that the discharged liquids meet environmental discharge requirements.

[0091] To further illustrate certain aspects of the invention, the disclosure also specifically provides some non-limiting embodiments as follows: [0092] Embodiment 1. A method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the steps: [0093] 1) pretreatment: extracting the radioactive waste liquid with a first selective extracting agent, thereby obtaining an extracted radioactive waste liquid; 100941 2) concentration: subjecting the extracted radioactive waste liquid to reverse osmosis concentration, thereby obtaining a retentate and a permeate; [0095] 3) extraction: extracting the radionuclides from the concentrate with an organic ion exchange resin and/or a second selective extracting agent; and [0096] 4) solidifying nuclides: rendering the nuclides-rich organic ion exchange resin and/or second selective extracting agent obtained from step 3) and first selective extracting agent obtained from step 1) to form a solidified body.

[0097] Embodiment 2. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 1, characterized in that, the pretreatment further comprises oxidizing the nuclides in the radioactive waste liquid to convert them into ionic form, preferably with ultraviolet light, ozone, hydrogen peroxide, and/or sodium hypochlorite, prior to the extracting in step 1).

[0098] Embodiment 3. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 1, characterized in that, the method further comprises removing organic materials in the liquid, preferably with an activated carbon, prior to the extraction in step 3).

[0099] Embodiment 4. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 1, characterized in that, the method further comprises step 5) of liquid purification: subjecting the permeate obtained from step 2) to deionization, preferably continuous electrodeionization, and recycling the radionuclides-rich concentrated water obtained from the liquid purification back to step 2).

[00100] Embodiment 5. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 1 to 4, characterized in that, the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides.

1001011 Embodiment 6. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 5, characterized in that, the inorganic oxide carrier comprises silica, manganese dioxide, aluminum oxide, titanium oxide, zirconium oxide or any combination thereof, and the active component for extracting the nuclides comprises ferrocyanides, antimonates, titanates, tin oxide, tungstates or any combination thereof [00102] Embodiment 7. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding embodiments, characterized in that, the organic ion exchange resin comprises a cation exchange resin in hydrogen form and an anion exchange resin in hydroxylic form.

1001031 Embodiment 8. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 1 to 4, characterized in that, the selective extracting agents each independently comprise molecular sieves, preferably NaY molecular sieve, 13X molecular sieve, ZSM-5 molecular sieve, SAPO-34 molecular sieve, p molecular sieve or any combination thereof 1001041 Embodiment 9. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding embodiments, comprising the steps: 1001051 1) pretreatment: catalytically oxidizing the radioactive waste liquid with H202 under ultraviolet light, followed by extracting it with the first selective extracting agent; 1001061 2) concentration: carrying out at least two stages of reverse osmosis concentrations in a concentrating tank, wherein the permeate from each stage of reverse osmosis sequentially enters the next stage, and the retentate from each stage of reverse osmosis is recycled back to the concentrating tank; 1001071 3) extraction: extracting the retentate in the concentrating tank obtained from step 2) with two or more stages of the organic ion exchange resins and/or the second selective extracting agents, wherein the retentate sequentially passes through the stages of ion exchange resins and/or the second selective extracting agent, and the final effluent is recycled back to the concentrating tank; 1001081 4) solidifying nuclides: rendering the first selective extracting agent obtained from step 1) and/or the second selective extracting agent and/or the organic ion exchange resin obtained from step 3) to form a solidified body; 1001091 wherein the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides, the inorganic oxide carrier comprises silica, aluminum oxide, titanium oxide or any combination thereof, and the active component for extracting the nuclides comprises ferrocyanides and/or antimonates.

1001101 Embodiment 10. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding embodiments, characterized in that, when the conductivity of the effluent in step 3) is greater than or equal to that of the final concentrate in step 2), or the conductivity of the final permeate in step 2) is higher than 50 pS/cm, 1001111 subjecting the first stage ion exchange resin and/or selective extracting agent obtained from step 3) to step 4) of solidifying nuclides, and 1001121 optionally, loading a fresh ion exchange resin and/or a fresh selective extracting agent as last stage ion exchange resin and/or selective extracting agent, and moving forward other stages of ion exchange resins and/or selective extracting agents successively.

1001131 Embodiment 11. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding embodiments, characterized in that, comprising treating the waste liquid with flocculation, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration or any combination thereof, prior to the pretreatment in step 1).

1001141 Embodiment 12. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 4 to 11, characterized in that, the volume ratio of dilute water discharged in step 5) to the liquid entering step 3) is controlled in the range of 1 to 10:1, preferably in the range of 3 to 10:1.

1001151 Embodiment 13. A system for concentrating and solidifying radionuclides in radioactive waste liquid, comprising: 1001161 a) a pretreatment unit, comprising a first selective extracting agent; 1001171 b) a concentration unit, comprising a concentrating tank equipped with a reverse osmosis device, so that the retentate from the reverse osmosis device is recycled back to the concentrating tank, and the water outlet of the pretreatment unit is connected to the inlet of the reverse osmosis device; 1001181 c) an extraction unit, comprising an organic ion exchange bed and/or second selective extracting agent, wherein the water inlet of the extraction unit is connected to the concentrating tank so that the liquid in the concentrating tank enters the extraction unit, and the water outlet of the extraction unit is connected to the concentrating tank so that the liquid passing though the extraction unit is recycled back to the concentrating tank; 1001191 d) a unit for solidifying nuclides, where nuclides-rich selective extracting agent and/or nuclides-rich organic ion exchange resin form a solidified body.

1001201 Embodiment 14 The system for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 13, further comprising an oxidizing device, preferably equipped with ultraviolet light source or ozone device, at the upstream of the first selective extracting agent in the pretreatment unit.

1001211 Embodiment 15. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 13, wherein the extraction unit comprises an activated carbon bed before the organic ion exchange bed and/or the second selective extracting agent.

1001221 Embodiment 16. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 13, further comprising e) a liquid purification unit equipped with a deionization unit, wherein the water inlet in the liquid purification unit is connected to the concentration unit, so that the permeate obtained from the reverse osmosis device enters the liquid purification unit, and a concentrated water outlet in the liquid purification unit is connected to the concentration unit so that the concentrated water obtained from the deionization unit is recycled back to the concentrating tank.

1001231 Embodiment 17. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 13 to 16, characterized in that, the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides.

1001241 Embodiment 18. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to embodiment 17, characterized in that, the inorganic oxide carriers each independently comprise silica, manganese dioxide, aluminum oxide, titanium oxide, zirconium oxide or any combination thereof, and the active component for extracting the nuclides comprises ferrocyanides, antimonates, titanates, tin oxide, tungstates or any combination thereof [001251 Embodiment 19. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 13 to 16, characterized in that, the organic ion exchange resin comprises a cation exchange resin in hydrogen form and an anion exchange resin in hydroxylic form.

1001261 Embodiment 20. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 13 to 16, characterized in that, the selective extracting agents each independently comprise molecular sieve, preferably comprises NaY molecular sieve, 13X molecular sieve, ZSM-5 molecular sieve, SAPO-34 molecular sieve, P molecular sieve or any combination thereof 1001271 Embodiment 21. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 13 to 16, wherein the pretreatment unit further comprises a filtration device, including flocculation device, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device or any combination thereof 1001281 Embodiment 22. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of embodiments 13 to 16, wherein the concentration unit comprises a concentrating tank equipped with at least two stages of reverse osmosis devices, and the retentate outlet in each stage of the reverse osmosis devices is connected to the concentrating tank so that the retentate in each stage of the reverse osmosis devices is recycled back to the concentrating tank.

1001291 The present invention is exemplarily illustrated by the following embodiments.

1001301 Examples 1001311 Example 1: 1001321 Radioactive waste liquid was introducing into a raw liquid tank, with the flow rate controlled at 1m3/h. After removal of fine suspended substances in the liquid with self-cleaning filter and ultrafiltration, the liquid entered catalytically oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device under ultraviolet light. I-1202 was added in a controlled dosage (5 mg/L). The effluent passed through a selective extracting agent at certain flow rate. The selective extracting agent comprised: silica, titanium oxide, ferrocyanides and antimonates. The effluent entered the concentrating tank.

1001331 High and low working liquid level switches were equipped in the concentrating tank. Two stages of reverse osmosis concentration were configured in the concentrating tank. The permeate from each stage of reverse osmosis sequentially entered the next stage and finally entered the continuous electrodeionization unit. The retentate from each stage of reverse osmosis was recycled back to the concentrating tank. When the system was turned on, the membrane module was automatically flushed, and the normal working procedure began. When the system was stopped, the system was on-line flushed with non-radioactive water or the dilute water produced by the system. The radioactive waste liquid first passed through a precision filter, and the effluent entered the first stage of reverse osmosis. The ratio of the dilute water to the concentrated water produced by the first stage of reverse osmosis was controlled at 51. The dilute water had a conductivity of 400/cm, and entered the second stage of reverse osmosis. The concentrated water entered ion exchange resin. The ratio of the dilute water to the concentrated water produced by the second stage of reverse osmosis was controlled at 5:1. The concentrated water in the second stage of reverse osmosis was recycled back to the concentrating tank. The effluent dilute water had a conductivity of 110/cm, and a total bacterial count of <100 CFU/mL, and entered a continuous electrodeionization unit. In the continuous electrodeionization unit, the anode was made of a pure titanium plate electrode, and the cathode was made of a stainless steel plate. The volume ratio of the dilute to the concentrated water in the continuous electrodeionization unit was 5:1. The final dilute water met environmental discharge requirements. The concentrated water was recycled back to the concentrating tank via a booster pump.

1001341 The liquid in a medium concentrating tank was first pumped into an activated carbon bed, and then an ion exchange resin bed, with the flow rate controlled at 100L/h.

The ion exchange resin bed had two stages, with 10 L resin in each stage. The first stage was filled with cation exchange resin, and the second stage was filled with mixed cation and anion ion exchange resins. Cation exchange resin was used in hydrogen form, and anion exchange resin was used in hydroxylic form. The liquid sequentially passed through the stages of ion exchange resin bed. The final effluent had a pH value of between 6 and 8, and was recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed was not lower than that in the concentrating tank, the ion exchange resin in the first stage of bed was fed into a standard barrel with a predetermined amount of cement through a feed pump, and was solidified after being stirred with the cement, or was dehydrated, dried, and sent to a standard barrel for storage..

1001351 With this process, the recovery ratio of nuclides (except tritium) in the radioactive waste liquid was up to 99% or higher, all of which were stored in the selective extracting agent and the ion exchange material.

1001361 Example 2:

1001371 Radioactive waste liquid was introducing into a raw liquid tank, with the flow rate controlled at 1m3/h. After removal of fine suspended substances in the liquid with self-cleaning filter and ultrafiltration, the liquid entered catalytically oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device under ultraviolet light. EEG) was added in a controlled dosage (10mg/L). The effluent passed through a selective extracting agent at certain flow rate. The selective extracting agent comprised: aluminum oxide, titanium oxide, ferrocyanides and antimonates. The effluent entered the concentrating tank.

1001381 High and low working liquid level switches were equipped in the concentrating tank. There stages of reverse osmosis concentration were configured in the concentrating tank. The permeate from each stage of reverse osmosis sequentially entered the next stage and finally entered the continuous electrodeionization unit. The retentate from each stage of reverse osmosis was recycled back to the concentrating tank. When the system was turned on, the membrane module was automatically flushed, and the normal working procedure began. When the system was stopped, the system was on-line flushed with nonradioactive water or the dilute water produced by the system. The radioactive waste liquid first passed through a precision filter, and the effluent entered the first stage of reverse osmosis. The ratio of the dilute to the concentrated water produced by the first stage of reverse osmosis was controlled at 5:1. The dilute water had a conductivity of 40µS/cm, and entered the second stage of reverse osmosis and the third stage of reverse osmosis. The concentrated water entered ion exchange resin. The ratio of the dilute water to the concentrated water produced by the reverse osmosis was controlled at 5:1. The concentrated water in the reverse osmosis was recycled back to the concentrating tank.

The effluent dilute water had a conductivity of lORS/cm, and a total bacterial count of <100 CFU/mL, and entered continuous electrodeionization unit. In the continuous electrodeionization unit, the anode was made of a pure titanium plate electrode, and the cathode was made of a stainless steel plate. The volume ratio of the dilute water to the concentrated water in the continuous electrodeionization unit was 3:1. The final dilute water met environmental discharge requirements. The concentrated water was recycled back to the concentrating tank via a booster pump.

1001391 The liquid in a medium concentrating tank was pumped into an activated carbon bed. The effluent was pumped into adsorption bed, with the flow rate controlled at 100L/h. The bed was filled with selective extracting agent comprising: aluminum oxide, titanium oxide, ferrocyanides and antimonates, in total 10L. The effluent was pumped into organic ion exchange bed, with the flow rate controlled at 100L/h. The bed was filled with mixed cation and anion ion exchange resins, in total 20L. Cation exchange resin was used in hydrogen form, and anion exchange resin was used in hydroxylic form. The ion exchange resin bed had two stages. The liquid sequentially passed through the stages of ion exchange resin bed. The final effluent had a pH value of between 6 and 8, and was recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed was not lower than that in the concentrating tank, the ion exchange resin in the first stage of bed was fed into a standard barrel with a predetermined amount of cement through a feed pump, and was solidified after being stirred with the cement, or was dehydrated, dried, and sent to a standard barrel for storage. A resin bed filled with fresh resin was loaded as the last stage, and other stages were moved forward sequentially.

1001401 With this process, the recovery ratio of nuclides (except tritium) in the radioactive waste liquid was up to 99.9% or higher, all of which were stored in the selective extracting agent and the ion exchange material.

1001411 Example 3:

1001421 Radioactive waste liquid was introducing into a raw liquid tank, with the flow rate controlled at 0.2m3/h. After removal of fine suspended substances in the liquid with self-cleaning filter and ultrafiltration, the liquid entered catalytically oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device under ultraviolet light. 11202 was added in a controlled dosage (10mg/L). The effluent passed through a selective extracting agent at certain flow rate. The selective extracting agent comprised: silica, aluminum oxide, titanium oxide, ferrocyanides, tin oxide and antimonates. The effluent entered the concentrating tank.

1001431 High and low working liquid level switches were equipped in the concentrating tank. Two stages of reverse osmosis concentration were configured in the concentrating tank. The permeate from each stage of reverse osmosis sequentially entered the next stage and finally entered the continuous electrodeionization unit. the retentate from each stage of reverse osmosis was recycled back to the concentrating tank. When the system was turned on, the membrane module was automatically flushed, and the normal working procedure began. When the system was stopped, the system was on-line flushed with non-radioactive water or the dilute water produced by the system. The radioactive waste liquid first passed through a precision filter, and the effluent entered the first stage of reverse osmosis. The ratio of the dilute water to the concentrated water produced by the first stage of reverse osmosis was controlled at 1:1. The dilute water had a conductivity of 50µS/cm, and entered the second stage of reverse osmosis. The concentrated water entered ion exchange resin. The ratio of the dilute water to the concentrated water produced by the second stage of reverse osmosis was controlled at 1:1. The concentrated water in the second stage of reverse osmosis was recycled back to the concentrating tank. The effluent dilute water had a conductivity of 20µS/cm, and a total bacterial count of <100 CFU/mL, and entered continuous electrodeionization unit. In the continuous electrodeionization unit, the anode was made of a pure titanium plate electrode, and the cathode was made of a stainless steel plate. The volume ratio of the dilute water to the concentrated water in the continuous electrodeionization unit was 1:1. The final dilute water met environmental discharge requirements. The concentrated water was recycled back to the concentrating tank via a booster pump.

1001441 The liquid in a medium concentrating tank was pumped into an activated carbon bed, then pumped into adsorption bed filled with selective extracting agent comprising: silica, aluminum oxide, titanium oxide, ferrocyanides, tin oxide and antimonates. The effluent was pumped into organic ion exchange bed, with the flow rate controlled at 50L/h. The bed was filled with mixed cation and anion ion exchange resins, in total 10L. Cation exchange resin was used in hydrogen form, and anion exchange resin was used in hydroxylic form. The ion exchange resin bed had two stages. The liquid sequentially passed through the stages of ion exchange resin bed. The final effluent had a pH value of between 6 and 8, and was recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed was not lower than that in the concentrating tank, the ion exchange resin in the first stage of bed was fed into a standard barrel with a predetermined amount of cement through a feed pump, and was solidified after being stirred with the cement, or was dehydrated, dried, and sent to a standard barrel for storage. A resin bed filled with fresh resin was loaded as the last stage, and other stages were moved forward sequentially.

1001451 With this process, the recovery ratio of nuclides (except tritium) in the radioactive waste liquid was up to 99.9% or higher, all of which were stored in the selective extracting agent and the ion exchange material.

1001461 Example 4:

1001471 Radioactive waste liquid was introducing into a raw liquid tank, with the flow rate controlled at 0.2m3/h. After removal of fine suspended substances in the liquid with self-cleaning filter and ultrafiltration, the liquid passed through a selective extracting agent at certain flow rate. The selective extracting agent comprised: aluminum oxide, zirconium oxide, ferrocyanides, tin oxide and tungstates. The effluent entered the concentrating tank. 1001481 High and low working liquid level switches were equipped in the concentrating tank. Two stages of reverse osmosis concentration were configured in the concentrating tank. The permeate from each stage of reverse osmosis sequentially entered the next stage and finally entered the continuous electrodeionization unit. The retentate from each stage of reverse osmosis was recycled back to the concentrating tank. When the system was turned on, the membrane module was automatically flushed, and the normal working procedure began. When the system was stopped, the system was on-line flushed with nonradioactive water or the dilute water produced by the system. The radioactive waste liquid first passed through a precision filter, and the effluent entered the first stage of reverse osmosis. The ratio of the dilute water to the concentrated water produced by the first stage of reverse osmosis was controlled at 3:1. The dilute water had a conductivity of 350/cm, and entered the second stage of reverse osmosis. The concentrated water entered ion exchange resin. The ratio of the dilute water to the concentrated water produced by the second stage of reverse osmosis was controlled at 5:1. The concentrated water in the second stage of reverse osmosis was recycled back to the concentrating tank. The effluent dilute water had a conductivity of lORS/cm, and a total bacterial count of <100 CFU/mL, and entered continuous electrodeionization unit. In the continuous electrodeionization unit, the anode was made of a pure titanium plate electrode, and the cathode was made of a stainless steel plate. The volume ratio of the dilute water to the concentrated water in the continuous electrodeionization unit was 5.1. The final dilute water met environmental discharge requirements. The concentrated water was recycled back to the concentrating tank via a booster pump.

1001491 The liquid in a medium concentrating tank was pumped into an activated carbon bed, and then pumped into adsorption bed filled with selective extracting agent comprising: aluminum oxide, zirconium oxide, ferrocyanides, tin oxide and tungstates. The effluent was pumped into organic ion exchange bed, with the flow rate controlled at 200L/h. The bed was filled with mixed cation and anion ion exchange resins, in total 10L. Cation exchange resin was used in hydrogen form, and anion exchange resin was used in hydroxylic form. The ion exchange resin bed had two stages. The liquid sequentially passed through the stages of ion exchange resin bed. The final effluent had a pH value of between 6 and 8, and was recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed was not lower than that in the concentrating tank, the ion exchange resin in the first stage of bed was fed into a standard barrel with a predetermined amount of cement through a feed pump, and was solidified after being stirred with the cement, or was dehydrated, dried, and sent to a standard barrel for storage.

A resin bed filled with fresh resin was loaded as the last stage, and other stages were moved forward sequentially.

1001501 With this process, the recovery ratio of nuclides (except tritium) in the radioactive waste liquid was up to 95% or higher, all of which were stored in the selective extracting agent and the ion exchange material.

1001511 Example 5:

1001521 Radioactive waste liquid was introducing into a raw liquid tank, with the flow rate controlled at 1m3/h. After removal of fine suspended substances in the liquid with self-cleaning filter and ultrafiltration, the liquid entered catalytically oxidizing device equipped with a dosing device and an on-line pH controlling and measuring device under ultraviolet light. H202 was added in a controlled dosage (5 mg/L). The effluent passed through a selective extracting agent at certain flow rate. The selective extracting agent comprised: silica, zirconium oxide, ferrocyanides and tin oxide. The effluent entered the concentrating tank.

1001531 High and low working liquid level switches were equipped in the concentrating tank. two stages of reverse osmosis concentration were configured in the concentrating tank. The permeate from each stage of reverse osmosis sequentially entered the next stage and finally entered the continuous electrodeionization unit. The retentate from each stage of reverse osmosis was recycled back to the concentrating tank. When the system was turned on, the membrane module was automatically flushed, and the normal working procedure began. When the system was stopped, the system was on-line flushed with nonradioactive water or the dilute water produced by the system. The radioactive waste liquid first passed through a precision filter, and the effluent entered the first stage of reverse osmosis. The ratio of the dilute water to the concentrated water produced by the first stage of reverse osmosis was controlled at 5:1. The dilute water had a conductivity of 40µS/cm, and entered the second stage of reverse osmosis. The concentrated water entered ion exchange resin. The ratio of the dilute water to the concentrated water produced by the second stage of reverse osmosis was controlled at 5:1. The concentrated water in the second stage of reverse osmosis was recycled back to the concentrating tank. The effluent dilute water had a conductivity of 11µS/cm, and a total bacetrial count of <100 CFU/mL, and entered continuous electrodeionization unit. In the continuous electrodeionization unit, the anode was made of a pure titanium plate electrode, and the cathode was made of a stainless steel plate. The volume ratio of the dilute water to the concentrated water in the continuous electrodeionization unit was 5.1. The final dilute water met environmental discharge requirements. The concentrated water was recycled back to the concentrating tank via a booster pump.

1001541 The liquid in a medium concentrating tank was pumped into an adsorption bed filled with selective extracting agent comprising: silica, zirconium oxide, ferrocyanides and tin oxide. Then the liquid was pumped into organic ion exchange bed, with the flow rate controlled at 100L/h. The organic ion exchange bed was filled with mixed cation and anion ion exchange resins, in total 5L. Cation exchange resin was used in hydrogen form, and anion exchange resin was used in hydroxylic form. The ion exchange resin bed had two stages. The liquid sequentially passed through the stages of ion exchange resin bed. The final effluent had a pH value of between 6 and 8, and was recycled back to the concentrating tank. When the conductivity of the effluent in the ion exchange bed was not lower than that in the concentrating tank, the ion exchange resin in the first stage of bed was fed into a standard barrel with a predetermined amount of cement through a feed pump, and was solidified after being stirred with the cement, or was dehydrated, dried, and sent to a standard barrel for storage. A resin bed filled with fresh resin was loaded as the last stage, and other stages were moved forward sequentially.

1001551 With this process, the recovery ratio of nuclides (except tritium) in the radioactive waste liquid was up to 95% or higher, all of which were stored in the selective extracting agent and the ion exchange material.

1001561 While various aspects of the invention have been described hereinbefore with reference to the particular exemplary embodiments, it will be understood by those skilled in the art that the present invention is not limited to the specific examples described hereinbefore. Various equivalents to the specific technical means, raw materials, devices, steps and the like may be substituted without departing from the scope of the invention. All of these equivalents and the combination thereof are intended to fall within the scope of the invention.

Claims

CLAIMS1. A method for concentrating and solidifying radionuclides in radioactive waste liquid, comprising the steps: I) pretreatment: extracting the radioactive waste liquid with a first selective extracting agent, thereby obtaining an extracted radioactive waste liquid; 2) concentration: subjecting the extracted radioactive waste liquid to reverse osmosis concentration, thereby obtaining a retentate and a permeate; 3) extraction: extracting the radionuclides from the concentrate with an organic ion exchange resin and/or a second selective extracting agent; and 4) solidifying nuclides: rendering the nuclides-rich organic ion exchange resin and/or second selective extracting agent obtained from step 3) and first selective extracting agent obtained from step 1) to form a solidified body.The method for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 1, characterized in that, the pretreatment further comprises oxidizing nuclides in the radioactive waste liquid to convert them into ionic form, preferably with ultraviolet light, ozone, hydrogen peroxide, and/or sodium hypochlorite, prior to the extracting in step 1).The method for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 1, characterized in that, the method further comprises removing organic materials in the liquid, preferably with an activated carbon, prior to the extraction in step 3).The method for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 1, characterized in that, the method further comprises step 5) of liquid purification: subjecting the permeate obtained from step 2) to deionization, preferably continuous electrodeionization, and recycling the radionuclides-rich concentrated water obtained from the liquid purification back to step 2).The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 1 to 4, characterized in that, the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides.The method for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 5, characterized in that, the inorganic oxide carrier 2. 4. 6.comprises silica, manganese dioxide, aluminum oxide, titanium oxide, zirconium oxide or any combination thereof; and the active component for extracting the nuclides comprises ferrocyanides, antimonates, titanates, tin oxide, tungstates or any combination thereof 7 The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding claims, characterized in that, the organic ion exchange resin comprises a cation exchange resin in hydrogen form and an anion exchange resin in hydroxylic form.8. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 1 to 4, characterized in that, the selective extracting agents each independently comprise molecular sieves, preferably NaY molecular sieve, 13X molecular sieve, ZSM-5 molecular sieve, SAPO-34 molecular sieve, (3 molecular sieve or any combination thereof 9. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding claims, comprising the steps: 1) pretreatment: catalytically oxidizing the radioactive waste liquid with H202 under ultraviolet light, followed by extracting it with the first selective extracting agent; 2) concentration: carrying out at least two stages of reverse osmosis concentrations in a concentrating tank, wherein the permeate from each stage of reverse osmosis sequentially enters the next stage, and the retentate from each stage of reverse osmosis is recycled back to the concentrating tank; 3) extraction: extracting the retentate in the concentrating tank obtained from step 2) with two or more stages of the organic ion exchange resins and/or the second selective extracting agents, wherein the retentate sequentially passes through the stages of ion exchange resins and/or the second selective extracting agent, and the final effluent is recycled back to the concentrating tank; 4) solidifying nuclides: rendering the first selective extracting agent obtained from step 1) and/or the second selective extracting agent and/or the organic ion exchange resin obtained from step 3) to form a solidified body; wherein the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides, the inorganic oxide carrier comprises silica, aluminum oxide, titanium oxide or any combination thereof, and the active component for extracting the nuclides comprises ferrocyanides and/or antimonates.The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding claims, characterized in that, when the conductivity of the effluent in step 3) is greater than or equal to that of the concentrate in step 2), or the conductivity of the final permeate in step 2) is higher than 50 pS/cm, subjecting the first stage ion exchange resin and/or selective extracting agent obtained from step 3) to step 4) of solidifying nuclides, and optionally, loading a fresh ion exchange resin and/or a fresh selective extracting agent as last stage ion exchange resin and/or selective extracting agent, and moving forward other stages of ion exchange resins and/or selective extracting agents successively.11 The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of the preceding claims, characterized in that, comprising treating the waste liquid with flocculation, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration or any combination thereof, prior to the pretreatment in step 1).12. The method for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 4 to 11, characterized in that, the volume ratio of dilute water discharged in step 5) to the liquid entering step 3) is controlled in the range of 1 to 10:1, preferably in the range of 3 to 10:1.13. A system for concentrating and solidifying radionuclides in radioactive waste liquid, comprising.a) a pretreatment unit, comprising a first selective extracting agent; b) a concentration unit, comprising a concentrating tank equipped with a reverse osmosis device, so that the retentate from the reverse osmosis device is recycled back to the concentrating tank, and the water outlet of the pretreatment unit is connected to the inlet of the reverse osmosis device; c) an extraction unit, comprising an organic ion exchange bed and/or second selective extracting agent, wherein the water inlet of the extraction unit is connected to the concentrating tank so that the liquid in the concentrating tank enters the extraction unit, and the water outlet of the extraction unit is connected to the concentrating tank so that the liquid passing though the extraction unit is recycled back to the concentrating tank; d) a unit for solidifying nuclides, where nuclides-rich selective extracting agent and/or nuclides-rich organic ion exchange resin form a solidified body.14. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 13, further comprising an oxidizing device, preferably equipped with ultraviolet light source or ozone device, at the upstream of the first selective extracting agent in the pretreatment unit.15. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 13, wherein the extraction unit comprises an activated carbon bed before the organic ion exchange bed and/or the second selective extracting agent.16. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 13, further comprising e) a liquid purification unit equipped with a deionization unit, wherein the water inlet in the liquid purification unit is connected to the concentration unit, so that the permeate obtained from the reverse osmosis device enters the liquid purification unit, and a concentrated water outlet in the liquid purification unit is connected to the concentration unit so that the concentrated water obtained from the deionization unit is recycled back to the concentrating tank.17. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 13 to 16, characterized in that, the selective extracting agents each independently comprise an inorganic oxide carrier and an active component for extracting the nuclides.18. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to claim 17, characterized in that, the inorganic oxide carriers each independently comprise silica, manganese dioxide, aluminum oxide, titanium oxide, zirconium oxide or any combination thereof, and the active component for extracting the nuclides comprises ferrocyanides, antimonates, titanates, tin oxide, tungstates or any combination thereof 19. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 13 to 16, characterized in that, the organic ion exchange resin comprises a cation exchange resin in hydrogen form and an anion exchange resin in hydroxylic form.20. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 13 to 16, characterized in that, the selective extracting agents each independently comprise molecular sieve, preferably comprises NaY molecular sieve, 13X molecular sieve, ZSM-5 molecular sieve, SAPO-34 molecular sieve, P molecular sieve or any combination thereof 21. The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 13 to 16, wherein the pretreatment unit further comprises a filtration device, including flocculation device, activated carbon, precision filter, cartridge filter, self-cleaning filter, ultrafiltration device or any combination thereof 22 The system for concentrating and solidifying radionuclides in radioactive waste liquid according to any one of claims 13 to 16, wherein the concentration unit comprises a concentrating tank equipped with at least two stages of reverse osmosis devices, and the retentate outlet in each stage of the reverse osmosis devices is connected to the concentrating tank so that the retentate in each stage of the reverse osmosis devices is recycled back to the concentrating tank.