Joint monitoring method for strontium-90, strontium-89, nickel-63 and iron-55 in liquid effluent

Abstract

The invention provides a combined monitoring method for Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent, and particularly relates to the technical field of radioactive substance detection. The method comprises the following steps: carrying out sample pretreatment by adopting a resin column array; the liquid effluent is pretreated, and strontium ions, iron ions and nickel ions in the liquid effluent are enriched in a first cation resin column; leaching the first cationic resin column with a nitric acid solution, and collecting the leacheate in a temporary storage tank after the leacheate sequentially passes through an anion resin column, a strontium resin column and a DGA resin column; then sequentially desorbing the TRU resin columns to obtain an Fe-55 desorption solution; the strontium resin column and the DGA resin column are desorbed, and Sr-89 desorption liquid and Sr-90 desorption liquid are obtained respectively; desorbing the nickel resin column to obtain a Ni-63 desorption solution; and the activity of Fe-55, the activity of Sr-89, the activity of Sr-90 and the activity of Ni-63 are measured. According to the invention, combined measurement of multiple nuclides of a single sample can be realized, the multi-nuclide monitoring efficiency is improved, and the monitoring cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radioactive substance detection, and particularly relates to a combined monitoring method for strontium-90 (Sr-90), strontium-89 (Sr-89), nickel-63 (Ni-63) and iron-55 (Fe-55) in liquid effluent. BACKGROUND

[0002] The operation of nuclear facilities such as nuclear power plants is accompanied by the emission of radioactive substances, which enter the environment through liquid effluent and air-borne effluent emissions, and cause radiation effects on the public. Therefore, monitoring and evaluating the radioactive emissions in the effluent of nuclear power plants and other nuclear facilities is the main work of radioactive waste management and environmental protection.

[0003] According to the current regulatory standard requirements, the operating unit of a nuclear power plant needs to monitor Fe-55, Ni-63, Sr-90 and other nuclides in the liquid effluent on a quarterly mixed sample basis, and the detection limit needs to meet the following standards: Fe-55: ≤1 Bq / L; Ni-63: ≤1 Bq / L; Sr-90: ≤0.1 Bq / L. At present, nuclear power plants generally use offline laboratory analysis methods, which have the following problems: (1) low efficiency: the traditional radiochemical separation process is complex, and it takes more than 3 days to analyze a single sample, which is difficult to meet the demand for high-frequency monitoring. (2) Strong dependence on manual operation: sample pretreatment requires manual adjustment of pH, multiple filtration, drying and other operations, which poses a risk of radioactive exposure. (3) Equipment is scattered: the existing technology needs to process each nuclide separately, resulting in redundant laboratory equipment, large space occupation, and often requiring several days to obtain results. The complex analysis process often affects the implementation of emissions, and has potential adverse effects on the production and operation of nuclear power plants.

[0004] Therefore, it is necessary to develop a multi-nuclide combined monitoring method to replace the lengthy and complex sampling and laboratory manual analysis, and to implement fast and efficient automatic monitoring, which has become a problem that must be solved in the current nuclear power industry. SUMMARY

[0005] The present application provides a combined monitoring method for Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent to solve the technical problems of low detection efficiency, high manpower and material resource costs in the prior art.

[0006] The combined monitoring method for Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by the present application comprises the following steps: resin column pretreatment: pretreating a resin column array, wherein the resin column array comprises a first cation resin column, an anion resin column, a second cation resin column, a TRU resin column, a strontium resin column, a DGA resin column and a nickel resin column;

[0007] Sample pretreatment: Strontium carrier, yttrium carrier, iron carrier and nickel carrier are added to the liquid effluent, and the pH is adjusted to 1-2 to obtain a mixed solution;

[0008] Metal ion enrichment: The mixed solution is passed through the first cation resin column, and strontium ions, iron ions and nickel ions are enriched on the first cation resin column;

[0009] Iron ion elution and adsorption: The first cation resin column is eluted with nitric acid solution, and the eluate is collected in a temporary storage tank after passing through the anion resin column, strontium resin column and DGA resin column in turn to obtain a first eluate;

[0010] Iron ion separation: The anion resin column is eluted with hydrochloric acid solution, and the eluate is transferred to the second cation resin column. Then the second cation resin column is eluted with nitric acid solution, and the eluate is transferred to the TRU resin column. Finally, the TRU resin column is desorbed with phosphoric acid solution to obtain Fe-55 desorption solution;

[0011] Strontium isotope separation: The strontium resin column is desorbed with nitric acid solution, and the DGA resin column is desorbed with hydrochloric acid solution to obtain Sr-89 desorption solution and Sr-90 desorption solution, respectively;

[0012] Nickel ion separation: The first eluate is passed through the nickel resin column, and the nickel resin column is desorbed with hydrochloric acid solution to obtain Ni-63 desorption solution;

[0013] Activity detection: The activities of Fe-55, Sr-89, Sr-90 and Ni-63 in the Fe-55 desorption solution, Sr-89 desorption solution, Sr-90 desorption solution and Ni-63 desorption solution are measured.

[0014] In an embodiment of the present application, the step of resin column pretreatment comprises:

[0015] The first cation resin column and the second cation resin column are activated with 0.05-0.1M nitric acid solution at a flow rate of 5-10mL / min;

[0016] The nickel resin column is activated with 2-4M ammonium citrate solution at a flow rate of 5-10mL / min;

[0017] The anion resin column, TRU resin column, strontium resin column and DGA resin column are activated with 6-8M nitric acid solution at a flow rate of 5-10mL / min, respectively.

[0018] In an embodiment of the present application, in the step of metal ion enrichment, the mixed solution passes through the first cation resin column at a flow rate of 3-6mL / min.

[0019] In one embodiment of the present invention, in the step of iron ion rinsing and adsorption, a 6-8 mol / L nitric acid solution is used to rinse the first cation exchange resin column at a flow rate of 4-6 mL / min. The rinsing solution adsorbs iron ions through the anion exchange resin column and adsorbs strontium ions and yttrium ions through the strontium resin column and the DGA resin column.

[0020] In one embodiment of the present invention, the iron ion separation step includes: first washing the anion exchange resin column with a 4-6 mol / L hydrochloric acid solution at a flow rate of 4-6 mL / min; then rinsing the anion exchange resin column with a 0.05-0.1 mol / L hydrochloric acid solution at a flow rate of 4-6 mL / min, transferring the eluted iron ions to the second cation exchange resin column; then rinsing the cation exchange resin column with a 6-8 mol / L nitric acid solution at a flow rate of 4-6 mL / min, transferring the eluted iron ions to the TRU resin column; and finally desorbing the TRU resin column with a 0.5-1 mol / L phosphoric acid solution at a flow rate of 1-3 mL / min to obtain Fe-55 desorption solution.

[0021] In one embodiment of the present invention, in the step of strontium isotope separation, the strontium resin column is desorbed using a 0.05-0.1 mol / L nitric acid solution at a flow rate of 1-3 mL / min, and the DGA resin column is desorbed using a 0.05-0.1 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min, to obtain Sr-89 desorbent and Sr-90 desorbent.

[0022] In one embodiment of the present invention, the nickel ion separation step includes adjusting the pH of the first eluent to 8-9 and passing it through the nickel resin column at a flow rate of 4-6 mL / min; then desorbing the nickel resin column with a 2.5-3.5 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min to obtain Ni-63 desorbent.

[0023] In one embodiment of the present invention, in the activity detection step, Fe-55 and Ni-63 are measured using liquid scintillation counting, and the activities of Sr-89 and Sr-90 are calculated using the Cherenkov effect combined with decay correction formula.

[0024] The activity concentrations of Fe-55, Sr-89, and Ni-63 were calculated using formula (1):

[0025]

[0026] In formula (1):

[0027] A represents the radioactivity concentration of Fe-55, Sr-89, or Ni-63 in the liquid effluent, expressed in Bq / L.

[0028] N represents the net count of the liquid scintillation counter;

[0029] T represents the measurement time, in s;

[0030] Y represents the chemical recovery rate of Fe-55 or Sr-89 or Ni-63;

[0031] E represents the measurement efficiency of Fe-55 or Sr-89 or Ni-63;

[0032] V represents the sample volume of Fe-55 or Sr-89 or Ni-63, in L;

[0033] The activity concentration of Sr-90 is calculated by formula (2):

[0034]

[0035] In the formula:

[0036] A Sr-90 represents the radioactivity concentration of Sr-90 in the liquid effluent, in Bq / L;

[0037] N represents the net count of the liquid scintillation counter;

[0038] T represents the measurement time, in s;

[0039] Y Y90 represents the chemical recovery rate of Y-90;

[0040] E Y90 represents the measurement efficiency of Y-90;

[0041] V represents the sample volume of Sr-90, in L;

[0042] D represents the decay coefficient, e- 0.396t′ / T wherein t' is the time interval of strontium-yttrium separation to the measurement intermediate moment, in min; T is the half-life of Y-90, taken as 3845 min, and e is the natural logarithm.

[0043] In an embodiment of the present application, the Fe-55 desorption solution, the Sr-89 desorption solution, the Sr-90 desorption solution and the Ni-63 desorption solution can also be used to measure the recovery rate and the repetition rate;

[0044] The calculation formula of the recovery rate is shown in formula (3):

[0045]

[0046] In formula (3), Y represents the recovery rate; Q is the mass of the tracer in the sample after purification, in mg; Q0 is the mass of the tracer added to the sample, in mg, and the tracer is a strontium carrier, a yttrium carrier, an iron carrier or a nickel carrier added to the sample.

[0047] The calculation formula of the repetition rate is shown in formula (4):

[0048]

[0049] In formula (4), RSD represents the repetition rate, S represents the standard deviation, and n represents the total number of samples or the number of measurements; x i represents the measured value of the corresponding component in the material, i is 1-n, represents the average value of n times of measurement of the corresponding component in the material.

[0050] In an embodiment of the present application, the combined monitoring method further comprises: regenerating the resin column array, and the regeneration step comprises:

[0051] The first cation resin column and the second cation resin column are flushed with 0.05-0.1 mol / L nitric acid;

[0052] The anion resin column, the TRU resin column, the strontium resin column and the DGA resin column are flushed with 6-8 mol / L nitric acid, respectively.

[0053] The nickel resin column is flushed with 1-3 mol / L ammonium citrate solution.

[0054] The present application has the following beneficial effects: the combined monitoring method of Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by the present application combines multiple resin columns, realizes the separation of four nuclides through pre-enrichment of cation resin columns and step-by-step adsorption of specific resins (TRU, DGA, strontium resin column, nickel resin column, etc.), and further reduces the detection limit of Fe-55 to 0.71 Bq / L and the detection limit of Sr-90 to 0.08 Bq / L by combining gradient elution (iron→strontium→yttrium→nickel) and decay correction algorithm.

[0055] The present application realizes the online monitoring of four types of beta nuclides in liquid effluent of a nuclear power plant for the first time, solves the problems of low efficiency and insufficient detection limit of the traditional method, and provides technical support for the real-time supervision of radioactive emissions of a nuclear power plant. BRIEF DESCRIPTION OF DRAWINGS

[0056] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application. It is apparent that the drawing in the following description is only some embodiments of the application, and other drawings can be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings.

[0057] In the drawings:

[0058] Figure 1 The flow chart of the method for jointly monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by an embodiment of the application;

[0059] Figure 2 The connection schematic diagram of the resin column array used in the method for jointly monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by an embodiment of the application;

[0060] Figure 3 The connection schematic diagram of the components of the monitoring system used in the method for jointly monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by an embodiment of the application;

[0061] Figure 4 The cooperation connection schematic diagram of the resin column array, the control valve and the injection pump provided by an embodiment of the application.

[0062] The reference signs are as follows:

[0063] 110, resin column array; 111, first cation resin column; 112, anion resin column; 113, second cation resin column; 114, TRU resin column; 115, strontium resin column; 116, DGA resin column; 117, nickel resin column; 118, temporary storage tank; 119, waste liquid collection barrel; 121, iron separation liquid collection bottle; 122, strontium separation liquid collection bottle; 123, yttrium separation liquid collection bottle; 124, nickel separation liquid collection bottle; 210, control valve; 211, multi-channel switching valve; 212, double-flow switching valve; 213, three-way valve; 220, feedback module; 221, pressure sensor; 222, thermometer; 223, pH meter; 230, liquid storage bottle; 240, injection pump; 310, beta detector. DETAILED DESCRIPTION

[0064] The present application is described in greater detail by the following specific examples, and other advantages and benefits of the present application will become apparent to those of ordinary skill in the art upon implementation and practice. The present application can be carried out by different embodiments and be applied in various ways. All such modifications and variations that come within the scope of the present application are intended to be included herein as set forth herein and herein claimed. The disclosures of these patents and publications in their entireties are hereby incorporated by reference.

[0065] It is to be understood that the drawings are to be used only for illustrating the specific embodiments of the present application and not for explaining the spirit or scope of the present application. The drawings show only the components related to the present application and not the actual number, shape and size of the components. The actual components can be modified in shape, number and size, and the layout of the components can be more complex.

[0066] In the following description, numerous specific details are discussed in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to one of ordinary skill in the art that the embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the embodiments of the present application.

[0067] The present application provides a method for monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent. The method realizes online monitoring of Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent by using multi-stage resin column, automatic chemical separation technology and β online monitoring technology.

[0068] Referring to Figure 1 The method for monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by the present application comprises the following steps:

[0069] S1, resin column pretreatment: pretreating a resin column array, wherein the resin column array comprises a first cation resin column, an anion resin column, a second cation resin column, a TRU resin column, a strontium resin column, a DGA resin column and a nickel resin column;

[0070] S2, sample pretreatment: adding a strontium carrier, a yttrium carrier, an iron carrier and a nickel carrier to the liquid effluent, and adjusting the pH to 1-2 to obtain a mixed solution;

[0071] S3, metal ion enrichment: passing the mixed solution through the first cation resin column, and enriching strontium ions, iron ions and nickel ions on the first cation resin column;

[0072] S4, iron ion elution and adsorption: nitric acid solution is used to elute the first cation resin column, the eluate is collected in a temporary storage tank after passing through the anion resin column, the strontium resin column and the DGA resin column in sequence, and a first eluate is obtained;

[0073] S5, iron ion separation: hydrochloric acid solution is used to elute the anion resin column, the eluate is transferred to the second cation resin column, then nitric acid solution is used to elute the second cation resin column, the eluate is transferred to the TRU resin column, and phosphoric acid solution is used to desorb the TRU resin column, and a Fe-55 desorption solution is obtained;

[0074] S6, strontium isotope separation: nitric acid solution is used to desorb the strontium resin column, and hydrochloric acid solution is used to desorb the DGA resin column, and a Sr-89 desorption solution and a Sr-90 desorption solution are obtained respectively;

[0075] S7, nickel ion separation: the first eluate flows through the nickel resin column, and hydrochloric acid solution is used to desorb the nickel resin column, and a Ni-63 desorption solution is obtained;

[0076] S8, activity detection: the activities of Fe-55, Sr-89, Sr-90 and Ni-63 in the Fe-55 desorption solution, the Sr-89 desorption solution, the Sr-90 desorption solution and the Ni-63 desorption solution are measured.

[0077] Please refer to Figure 2 and Figure 3 , specifically, the resin column array 110 in step S1 includes a first cation resin column 111, an anion resin column 112, a second cation resin column 113, a TRU resin column 114, a strontium resin column 115, a DGA resin column 116 and a nickel resin column 117. Among them, the first cation resin column 111 contains a large number of anion groups, such as sulfonic acid groups (-SO3 - ), carboxyl groups (-COO - ) and the like, and the radionuclides in the liquid effluent exist in the form of positively charged cations, so the first cation resin column 111 can preliminarily enrich Fe 3+ , Ni 2+ , Sr 2+ and other metal ions; the anion resin column 112 contains quaternary ammonium groups, in strong acid, Fe 3+ is adsorbed by the quaternary ammonium groups in the form of FeCl4 - complex, the TRU resin column 114 contains CMPO extractant, which can selectively bind Fe 3+ ; the nickel resin column 117 contains dimethylglyoxime, which can form a chelate with Ni 2+ ; since Sr-90 will continuously decay to produce Y-90, the DGA resin column can adsorb Sr 2+ and Y 3+The Sr resin column 115 and the DGA resin column 116 can separate Sr isotopes (Sr-89 and Sr-90) in cooperation. The resin columns described above can be purchased through general commercial means.

[0078] The resin column array 110 is connected as follows: the first cation resin column 111 is connected to a sample tank (not shown in the figure) storing liquid effluent and a waste liquid collection tank 119 through pipelines. The anion resin column 112 is arranged downstream of the first cation resin column 111 and is connected thereto. The TRU resin column 114, the Sr resin column 115, the DGA resin column 116, and the Ni resin column 117 are arranged in parallel downstream of the anion resin column 112. The second cation resin column 113 is arranged on a communication branch between the TRU resin column 114 and the anion resin column 112. The Sr resin column 115 and the DGA resin column 116 are connected through a pipeline. The DGA resin column 116 is provided with a temporary storage tank 118 on a liquid discharge pipeline thereof. The temporary storage tank 118 is connected to the Ni resin column 117 through a pipeline. The waste liquid collection tank 119 is connected to each of the resin columns. In order to facilitate the collection of desorption liquid, the TRU resin column 114, the Sr resin column 115, the DGA resin column 116, and the Ni resin column 117 are respectively connected to an iron separation liquid collection bottle 121, a Sr separation liquid collection bottle 122, a Y separation liquid collection bottle 123, and a Ni separation liquid collection bottle 124 through pipelines.

[0079] The pretreatment step in step S1 includes:

[0080] The cation resin column is activated. A 0.05-0.1 mol / L nitric acid solution is used to flush the first cation resin column 111 and the second cation resin column 113 at a flow rate of 5-10 mL / min to remove impurities and activate exchange sites. Specifically, the concentration of the nitric acid solution can be 0.05 mol / L, 0.08 mol / L, or 0.1 mol / L, etc., and the flow rate can be 6 mL / min, 7 mL / min, or 8 mL / min, etc. The flushing time is not specifically limited and can be set according to actual needs, for example, 15 min, 20 min, 30 min, etc.

[0081] The anion resin column is activated. A 6-8 mol / L nitric acid solution is used to flush the anion resin column at a flow rate of 5-10 mL / min to ensure that the anion resin column has a high adsorption capacity for Fe 3+ Specifically, the concentration of the nitric acid solution can be 6 mol / L, 7 mol / L, or 8 mol / L, etc., and the flow rate can be 5 mL / min, 8 mL / min, or 10 mL / min, etc. The flushing time is not specifically limited and can be set according to actual needs, for example, 15 min, 20 min, 30 min, etc.

[0082] The nickel resin column is activated, and 2-4 mol / L ammonium citrate solution is used to activate and flush the nickel resin column at a flow rate of 5-10 mL / min, so as to improve the binding efficiency of butanedione oxime and Ni 2+ in the nickel resin column. Specifically, the concentration of the ammonium citrate solution can be 2 mol / L, 3 mol / L or 4 mol / L, etc., the flow rate can be 5 mL / min, 8 mL / min or 10 mL / min, etc., and the flushing time is not specifically limited and can be set according to actual needs, for example, flushing for 15 min, 20 min, 30 min, etc.

[0083] The TRU resin column, the strontium resin column and the DGA resin column are activated by using 6-8 M nitric acid solution to flush the TRU resin column, the strontium resin column and the DGA resin column at a flow rate of 5-10 mL / min. The TRU resin column contains CMPO / TBP extractant, and the activation by nitric acid can enhance the selectivity of Fe 3+ . The activation of the strontium resin column and the DGA resin column by nitric acid can optimize the adsorption of Sr 2+ . Specifically, the concentration of the nitric acid solution can be 6 mol / L, 7 mol / L or 8 mol / L, etc., the flow rate can be 5 mL / min, 8 mL / min or 10 mL / min, etc., and the flushing time is not specifically limited and can be set according to actual needs, for example, flushing for 15 min, 20 min, 30 min, etc.

[0084] The pretreatment liquid used in the pretreatment step S1 can be communicated with each resin column through a pipeline and switched into the corresponding resin column through a syringe pump and a control valve.

[0085] Please refer to Figure 3 , the pretreatment liquid is configured in a liquid storage bottle 230, and different kinds and different concentrations of pretreatment liquids are separately stored in different liquid storage bottles 230. The liquid storage bottles 230 are only exemplarily shown in the figure and do not represent the actual number of liquid storage bottles 230. The number of liquid storage bottles 230 can be set according to actual needs. The outlet of each liquid storage bottle 230 is provided with a syringe pump 240. The plurality of syringe pumps 240 can be controlled by a control system (not shown in the figure) to deliver the solutions in the plurality of liquid storage bottles 230 into the corresponding resin column according to the instructions, so as to complete the separation and purification of each nuclide in the liquid effluent in cooperation with the resin column array 110. In an embodiment, the syringe pump 240 is a vertical syringe pump, and the parameters of the syringe pump 240 are as follows: flow rate 0.1-10 mL / min, back pressure 0.28 MPa, and PTFE piston.

[0086] Please refer to Figure 3 and Figure 4The control valves 210 are arranged on each pipeline between the resin column array 110 and the liquid storage bottle 230, and can realize several flow path combinations. In an embodiment, the control valves 210 include a plurality of multi-channel switching valves 211, a plurality of double-flow switching valves 212, and a plurality of three-way valves 213. The plurality of multi-channel switching valves 211 are respectively connected to each resin column of the resin column array 110 and the injection pump 240 through a pipeline, and the number of the multi-channel switching valves 211 is consistent with the number of the injection pump 240. The plurality of double-flow switching valves 212 are respectively connected to each resin column and the multi-channel switching valve 211, and the number of the double-flow switching valves 212 is consistent with the number of the resin column. The three-way valves 213 are arranged on the connecting pipelines between the resin column and the separated liquid collection bottle. Specifically, the plurality of three-way valves 213 are respectively arranged on the effluent pipelines of the TRU resin column 114, the strontium resin column 115, the DGA resin column 116, and the nickel resin column 117. One end of the three-way valve 213 is connected to the resin column, the other end is connected to the separated liquid collection bottle corresponding to the resin column, and the other end is connected to the waste liquid collection barrel 119. Since the pretreated liquid, the desorption liquid and the like have strong acidity, the above pipelines are made of polytetrafluoroethylene material which is resistant to acid corrosion. The multi-channel switching valve 211 is made of PCTFE material, has a pressure resistance of 1.6 MPa, and a response time of less than 0.5 s. The double-flow switching valve 212 has a flow control accuracy of ±0.1 mL and an acid resistance level of IP67.

[0087] Further, a feedback module 220 is arranged on the connecting pipeline to monitor the changes of pressure, temperature and pH value in the pipeline in real time, and feed back to the control system 400. In an embodiment, the feedback module includes fourteen pressure sensors 221, eight thermometers 222 and nine pH meters 223. The fourteen pressure sensors 221 are respectively arranged at the inlet section and the outlet end of the seven resin columns of the cascade separation module 100, to monitor the changes of pressure in the pipeline in real time, and feed back the data to the control system to adjust the flow rate. The pressure sensor 221 has a range of 0-1.6 MPa and an accuracy of ±0.5% FS. One pH meter 223 is arranged in the sample barrel, one pH meter 223 is arranged in the temporary storage tank 118 before the liquid inlet of the nickel resin column 117, and the remaining seven pH meters 223 are respectively arranged at the liquid inlet of the seven resin columns of the cascade separation module 100. One thermometer 222 is arranged in the temporary storage tank 118 before the liquid inlet of the nickel resin column 117, and seven thermometers 222 are respectively arranged at the liquid outlet of the seven resin columns. The thermometer 222 has a range of 0-50℃ and an accuracy of ±0.5℃, and is used to monitor the working temperature of the resin column. The pressure sensor 221, the thermometer 222 and the pH meter can feed back the real-time pressure, temperature and pH data to the control system, so that the control system can monitor the running state in real time and can feed back in time when an abnormality occurs.

[0088] Please refer to Figure 1, step S2, i.e. pretreatment of the sample, strontium carrier, yttrium carrier, iron carrier and nickel carrier are added to the liquid effluent, wherein the strontium carrier can be strontium nitrate, the yttrium carrier can be yttrium nitrate, the iron carrier can be ferric nitrate, and the nickel carrier can be nickel nitrate, and in other embodiments, the carrier can also be other compounds containing corresponding ions. In step S2, the pretreatment adjusts the pH of the liquid effluent to 1-2, for example, it can be 1.0, 1.5, 2.0, etc., but it is not limited to the listed values, and other values not listed in this range are also applicable. Further, the amount of strontium carrier, yttrium carrier, iron carrier and nickel carrier added in the mixed solution is determined by the sampling amount of the liquid effluent, for example, the amount of each carrier added per 1 L of liquid effluent is 2-10 mg, and further, it can be 2 mg / L, 5 mg / L, 8 mg / L or 10 mg / L, etc., but it is not limited to the listed values, and other values not listed in this range are also applicable. The mixed solution obtained in this step is collected in a sample tank.

[0089] Step S3, i.e. the mixed solution obtained in step S2 is passed through the pretreated first cation resin column 111 at a flow rate of 3-6 mL / min, so that Fe 3+ , Ni 2+ , Sr 2+ in the mixed solution are enriched on the first cation resin column 111. The flow rate of the mixed solution can be controlled by the injection pump 240 and the control valve 210, for example, it can be 3 mL / min, 4 mL / min, 5 mL / min or 6 mL / min, etc.

[0090] Steps S4-S7 are specific nuclide separation, as follows:

[0091] Iron ion elution and adsorption step, first elute the first cation resin column 111 with 6-8 mol / L nitric acid solution at a flow rate of 4-6 mL / min, and the effluent passes through the anion resin column 112 to adsorb Fe 3+ as FeCl4 - complex anion on the quaternary ammonium group of the resin on the anion resin column 112; then, the effluent successively flows through the strontium resin column 115 and the DGA resin column 116 to adsorb Sr 2+ and Y 3+ , and the effluent is collected in a temporary storage tank 118, and then the pH is adjusted to 8-9 to obtain a first eluate. In this step, the concentration of the nitric acid solution can be 6 mol / L, 7 mol / L or 8 mol / L, etc., and the flow rate can be 3 mL / min, 4 mL / min, 5 mL / min or 6 mL / min, etc., and the flow rate can be adjusted by the injection pump 240 and the control valve 210. The pH of the first eluate can be adjusted by ammonia.

[0092] Fe-55 separation (washing and elution)

[0093] Washing: First, 4-6 mol / L hydrochloric acid solution is used to wash the anion resin column 112 at a flow rate of 4-6 mL / min to remove Co 2+ , Zn 2+ and other interfering ions. In this step, the concentration of hydrochloric acid can be 4 mol / L, 5 mol / L or 6 mol / L, etc., and the flow rate of hydrochloric acid can be 4 mL / min, 5 mL / min or 6 mL / min, etc., which can be adjusted by the injection pump 240 and the control valve 210.

[0094] Elution: Then, 0.05-0.1 mol / L hydrochloric acid solution is used to elute the anion resin column 112 at a flow rate of 4-6 mL / min to elute Fe 3+ to the second cation resin column 113; then, 6-8 mol / L nitric acid solution is used to elute the second cation resin column 113 at a flow rate of 4-6 mL / min to elute Fe 3+ to the TRU resin column 114. In this step, the concentration of hydrochloric acid can be 0.05 mol / L, 0.08 mol / L or 0.1 mol / L, etc., and the concentration of nitric acid solution can be 6 mol / L, 7 mol / L or 8 mol / L, etc., and the flow rate of hydrochloric acid and nitric acid can be 4-6 mL / min, specifically 4 mL / min, 5 mL / min or 6 mL / min, etc., which can be adjusted by the injection pump 240 and the control valve 210.

[0095] Desorption: Then, 0.5-1 mol / L phosphoric acid solution is used to desorb the TRU resin column 114 at a flow rate of 1-3 mL / min to break the coordination of the TRU resin, and Fe-55 desorption solution is obtained. In this step, the concentration of phosphoric acid solution can be 0.5 mol / L, 0.8 mol / L or 1 mol / L, etc., and the flow rate of phosphoric acid solution can be 1 mL / min, 2 mL / min or 3 mL / min, etc. The obtained Fe-55 desorption solution is collected in the iron separation solution collection bottle 121 for subsequent measurement.

[0096] Sr separation flow

[0097] Sr-89 separation: 0.05-0.1 mol / L nitric acid solution is used to desorb the strontium resin column 115 at a flow rate of 1-3 mL / min to obtain Sr-89 desorption solution. In this step, the concentration of nitric acid solution can be 0.05 mol / L, 0.08 mol / L or 0.1 mol / L, etc., and the flow rate of nitric acid solution can be 1 mL / min, 2 mL / min or 3 mL / min, etc. The obtained Sr-89 desorption solution is collected in the strontium separation solution collection bottle 122 for subsequent measurement.

[0098] Sr-90 separation:

[0099] The DGA resin column 116 is eluted with 0.05-0.1 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min to obtain Sr-90 eluate. In this step, the concentration of the hydrochloric acid solution can be 0.05 mol / L, 0.08 mol / L or 0.1 mol / L, etc., and the flow rate of the hydrochloric acid solution can be 1 mL / min, 2 mL / min or 3 mL / min, etc. The obtained Sr-90 eluate is collected in the yttrium separation liquid collection bottle 123 for subsequent measurement.

[0100] Ni-63 separation flow

[0101] Adsorption: The pH of the first eluate collected in the temporary storage tank 118 is adjusted to 8-9, and then passed through the nickel resin column 117 in an ammonium citrate buffer solution. The butanedione oxime on the nickel resin column 117 selectively adsorbs Ni 2+ forms a red chelate, thereby selectively adsorbing Ni 2+ onto the nickel resin column 117.

[0102] Desorption: The nickel resin column 117 is eluted with 2.5-3.5 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min. The hydrochloric acid destroys the chelate structure, thereby releasing Ni 2+ eluate. The concentration of the hydrochloric acid solution can be 2.5 mol / L, 3 mol / L or 3.5 mol / L, etc., and the flow rate of the hydrochloric acid solution can be 1 mL / min, 2 mL / min or 3 mL / min, etc. The obtained Ni-63 eluate is collected in the nickel separation liquid collection bottle 124 for subsequent measurement.

[0103] Step S8, i.e., activity detection: The present application adopts a four-way beta detector 310 array containing dual-mode detection, which is used to detect the radioactivity of Fe-55, Ni-63, Sr-89 and Sr-90. Specifically, the dual-mode detection includes a liquid flash detection unit and a Cerenkov detection unit. The liquid flash detection unit is composed of a plastic scintillator and a photomultiplier tube, which is used to detect the low-energy beta rays of Fe-55 and Ni-63. The Cerenkov detection unit is composed of a quartz window and a photomultiplier tube array, which is used to detect the high-energy beta rays of Sr-89 and Sr-90. Further, the plastic scintillator adopts plastic scintillation microspheres (20 microns) with polyethylene as the substrate, and is coated with 1 wt% fluorescent enhancer PPO and 0.2 wt% wavelength shifter (POPOP); the photomultiplier tube adopts Hamamatsu R6231-100 with a gain of 10 6, dark current <1 nA; sample cell is made of quartz glass, volume 10 mL, acid resistance level IP68. That is, two of the four beta detectors 310 use liquid scintillation detection mode (beta particle counting mode) to measure Fe-55 and Ni-63, and two use Cerenkov detection mode to measure Sr-89 and Sr-90.

[0104] The detection process of step S8 is as follows

[0105] Fe-55 and Ni-63 detection:

[0106] Liquid scintillation measurement: The Fe-55 eluate and the Ni-63 eluate are mixed with scintillation liquid (Ultima Gold AB) at a volume ratio of 2:18-8:12, and measured for 300 minutes using low-energy beta mode (threshold value 50-200 keV). Exemplarily, the volume ratio of the Fe-55 eluate, the Ni-63 eluate and the scintillation liquid can be 2:18, 5:15 or 8:12, etc.

[0107] Efficiency calibration: Efficiency calibration is performed using standard sources of Fe-59 and Ni-63 (efficiency > 80%).

[0108] Sr isotope detection:

[0109] Cerenkov measurement: High-energy beta mode (threshold value > 500 keV) is used for measurement, and decay correction formula is used to calculate the activity.

[0110] The calculation formula is as follows:

[0111] The activity concentration of Fe-55, Sr-89 and Ni-63 is calculated using formula (1):

[0112]

[0113] In formula (1), A represents the radioactivity concentration of Fe-55 or Sr-89 or Ni-63 in the liquid effluent, in units of Bq / L; N represents the net count of the liquid scintillation counter; T represents the measurement time, in units of s; Y represents the chemical recovery rate of Fe-55 or Sr-89 or Ni-63; E represents the measurement efficiency of Fe-55 or Sr-89 or Ni-63; and V represents the sample volume of Fe-55 or Sr-89 or Ni-63, in units of L.

[0114] The activity concentration of Sr-90 is calculated using formula (2):

[0115]

[0116] In formula (2), A Sr-90Y represents the radioactivity concentration of Sr-90 in the liquid effluent, in Bq / L; N represents the net count of the liquid scintillation counter; T represents the measurement time, in s; Y Y90 Y represents the chemical recovery of Y-90; E Y90 Y represents the measurement efficiency of Y-90; V represents the sample volume of Sr-90, in L; D represents the decay coefficient, e -0.396t′ / T where t' is the time interval of strontium-yttrium separation to the measurement intermediate time, in min; T is the half-life of Y-90, taken as 3845 min, and e is the natural logarithm.

[0117] The present application can also calculate the recovery rate and repeatability of each nuclide by liquid-liquid separation, as follows:

[0118] The recovery rate calculation formula is shown in formula (3):

[0119] The mass of iron, nickel and yttrium in the purified sample is measured by ultraviolet spectrophotometry, ICP-AES or X-ray fluorescence spectrometry, and the recovery rate Y is calculated by formula (3):

[0120]

[0121] In formula (3), Y represents the recovery rate; Q is the mass of the tracer in the purified sample, in mg; Q0 is the mass of the tracer added to the sample, in mg, and the tracer is a strontium carrier, a yttrium carrier, an iron carrier or a nickel carrier added to the sample.

[0122] The repeatability calculation formula is shown in formula (4):

[0123] The content of the purified nuclide is measured by plasma emission spectrometry, and the recovery rate RSD is calculated by formula (4), and the repeatability RSD should be no more than 20%.

[0124]

[0125] In formula (4), RSD represents the repeatability, S represents the standard deviation, and n represents the total number of samples or the number of measurements, and the value of n is not less than 20-30; x i Yi represents the measurement value of the corresponding component in the material, and the value of i is 1-n, Yi represents the average value of n times of measurements of the corresponding component in the material.

[0126] The combined monitoring method of the present application also includes resin column regeneration, and the process of resin column regeneration is as follows:

[0127] The first cation resin column 111 and the second cation resin column 113 are washed with 0.05-0.1 mol / L nitric acid solution, and the flow rate is, for example, 4 mL / min;

[0128] The anion resin column 112, the TRU resin column 114, the strontium resin column 115 and the DGA resin column 116 are flushed with 6-8 mol / L nitric acid solution, for example, at a flow rate of 4 mL / min;

[0129] The nickel resin column 117 is flushed with 1-3 mol / L ammonium citrate solution, for example, at a flow rate of 4 mL / min.

[0130] The above process can be controlled by a control system. In an embodiment, the control system comprises a PLC controller, which is electrically connected to the multi-channel switching valve 211, the double-flow switching valve 212 and the injection pump 240. The PLC controller controls the operation of the multi-channel switching valve 211, the double-flow switching valve 212 and the injection pump 240 through the built-in program, can automatically plan the separation path according to the measurement requirements, and dynamically adjust the flow rate according to the feedback real-time parameters, forming a closed-loop process of separation-detection-optimization. The built-in program of the control system can use conventional programs in the art, which will not be described in detail here.

[0131] The detection process of the present application is described in detail below through a specific embodiment to verify the separation and detection capability of the present application for Fe-55, Ni-63, Sr-89 and Sr-90 in the liquid effluent of the nuclear power plant, and to evaluate the chemical recovery rate, repeatability and detection limit.

[0132] (1) Resin column and reagent model

[0133]

[0134]

[0135] (2) Equipment model

[0136]

[0137] (3) The monitoring process is as follows:

[0138] Resin column pretreatment:

[0139] First, the injection pump 240 is used to inject the pretreatment liquid in the liquid storage bottle 230 into each resin column to pretreat the resin column to achieve the required pH value. For example, the first cation resin column 111 and the second cation resin column 113 are flushed with 0.1 mol / L HNO3 solution at a flow rate of 4 mL / min for 20 min to activate the sulfonic acid group; the anion resin column 112, the TRU resin column 114, the strontium resin column 115 and the DGA resin column 116 are flushed with 8 mol / L HNO3 at a flow rate of 4 mL / min for 15 min; and the nickel resin column 117 is flushed with 1 mol / L ammonium citrate solution at a flow rate of 4 mL / min for 15 min.

[0140] Sample loading:

[0141] Take 1 L simulated liquid effluent (containing Fe-55 10 Bq / L, Ni-63 20 Bq / L, Sr-89 1 Bq / L, Sr-90 0.5 Bq / L), add Fe, Ni, Sr, Y carriers (ferric nitrate 10 mg / L, nickel nitrate 5 mg / L, strontium nitrate 2 mg / L, yttrium nitrate 2 mg / L), adjust pH to 2.0 ± 0.1 with 0.1 mol / L HNO3 or ammonia water (pH meter real-time monitoring).

[0142] Metal ion enrichment:

[0143] Pass the liquid effluent through the first cation resin column 111 at a flow rate of 4 mL / min, Fe 3+ , Ni 2+ , Sr 2+ in the liquid effluent are adsorbed, and the effluent is recovered into the waste liquid collection bucket 119.

[0144] Nuclide-specific separation process:

[0145] Fe-55 separation:

[0146] (1) Elute the first cation resin column 111 with 8 mol / L HNO3 solution (flow rate 4 ml / min, amount 20 mL), Fe 3 + in the form of FeCl4 - enters the anion resin column 112 and is adsorbed. The eluate passes through the strontium resin column and the DGA resin column in sequence and is collected, and the pH is adjusted to 8-9 with ammonia water;

[0147] (2) Washing: Wash the anion resin column 112 with 4 mol / L HCl (flow rate 4 mL / min, amount 20 mL) to remove Co 2 + , Zn 2+ and other interfering ions;

[0148] (3) Elution: Elute Fe 3+ to the second cation resin column 113 with 0.1 mol / L HCl (4 mL / min, amount 50 mL), and then transfer to the TRU resin column 114 with 8 M HNO3 (4 mL / min, amount 20 mL);

[0149] (4) Elute Fe 3+ in the TRU resin column 114 to the iron separation liquid collection bottle 121 with 1 mol / L HPO4 (2 mL / min, amount 10 mL).

[0150] Sr isotope separation:

[0151] (1) Elute Sr-89 in the Sr resin column 115 to the Sr separation liquid collection bottle 122 with 0.1 mol / L HNO3 solution (2 mL / min, 10 mL used).

[0152] (2) Elute Sr-90 (Y-90) in the DGA resin column 116 to the Y separation liquid collection bottle 123 with 0.1 mol / L HC1 solution (2 mL / min, 10 mL used).

[0153] Ni-63 separation:

[0154] (1) Adjust the first elution liquid in the iron separation step to pH 8-9 with ammonia water, and elute the nickel resin column 117 with the elution liquid, Ni 2 + entering the nickel resin column and chelating with dimethylglyoxime;

[0155] (2) Elute Ni 2 + in the nickel resin column 117 to the nickel separation liquid collection bottle 124 with 3 mol / L HC1 (4 mL / min, 50 mL).

[0156] When performing the above process, the multi-channel switching valve 211, the double-flow switching valve 212, and the three-way valve 213 are freely combined under the control of the PLC controller to complete the whole process of pretreatment-sample loading-elution-desorption. At the same time, the data of the pressure sensor 221 is fed back to the PLC controller in real time, and the PLC controller dynamically adjusts the flow rate of the syringe pump 240 according to the change of the pipeline pressure value.

[0157] After the desorption of each resin column is completed, the separation liquid containing the nuclides is collected in the iron separation liquid collection bottle 121, the strontium separation liquid collection bottle 122, the yttrium separation liquid collection bottle 123, and the nickel separation liquid collection bottle 124.

[0158] Then, each separation liquid is detected, as follows:

[0159] (1) Fe-55 and Ni-63 detection (liquid scintillation method):

[0160] The Fe-55 desorption liquid is mixed with the scintillation liquid (Ultima Gold AB) at a volume ratio of 1:2, and measured in low-energy beta mode (50-200 keV) for 300 minutes.

[0161] The Ni-63 desorption liquid is mixed with the scintillation liquid (Ultima Gold AB) at a volume ratio of 1:2, and measured in low-energy beta mode (50-200 keV) for 300 minutes.

[0162] (2) Sr isotope detection (Cerenkov method):

[0163] Sr-89: High-energy beta mode (>500 keV) measurement for 300 minutes.

[0164] Sr-90: High-energy beta mode (>500 keV) measurement for 300 minutes, calculated by decay correction formula.

[0165] The experimental results are shown in Tables 1 to 3.

[0166] Table 1: Chemical recovery rate

[0167] Nuclide Amount added (Bq) Measured amount (Bq) Recovery rate (%) Fe-55 10.0 7.8±0.6 78.0±6.0 Ni-63 20.0 16.4±1.2 82.0±6.0 Sr-89 1.0 0.85±0.07 85.0±7.0 Sr-90 0.5 0.43±0.04 86.0±8.0

[0168] Table 2: Reproducibility (RSD, n = 10)

[0169]

[0170]

[0171] Table 3: Detection limit (3σ, 300 minutes of measurement)

[0172] Nuclide Detection limit (Bq / L) Requirement of GSNF

[2020] No. 44 (Bq / L) Fe-55 0.71 ≤1 Ni-63 0.16 ≤1 Sr-89 0.12 / Sr-90 0.08 ≤0.1

[0173] This embodiment verifies the monitoring capability of the application for Fe-55, Ni-63, Sr-89, and Sr-90 in liquid effluent:

[0174] The chemical recovery rate meets the standards: Fe-55 (78.0 ± 6.0%), Ni-63 (82.0 ± 6.0%), Sr-89 (85.0 ± 7.0%), and Sr-90 (86.0 ± 8.0%), all of which are higher than the design requirement of 70%.

[0175] The reproducibility is excellent: RSD ≤ 7.2%, meeting the specification requirement of ≤ 20%.

[0176] The detection limit is significantly optimized: Fe-55 (0.71 Bq / L), Ni-63 (0.16 Bq / L), Sr-89 (0.12 Bq / L), and Sr-90 (0.08 Bq / L), which is better than the national standard

[2020] No. 44.

[0177] Full-process automation: from 3L sample loading to detection result output, the time consumption is ≤ 24 hours, which is 3 times more efficient than the traditional method.

[0178] In summary, the application constructs a seven-column synergistic resin column array to realize the simultaneous processing of Fe-55, Ni-63, Sr-89 / 90; adopts nitric acid-hydrochloric acid-nitric acid stepwise desorption to reduce cross contamination; and eliminates the interference of Y-90 on Sr-89 measurement through decay correction algorithm.

[0179] The method for monitoring Sr-90, Sr-89, Ni-63 and Fe-55 in liquid effluent provided by the application realizes the separation of the four nuclides by using multi-stage resin columns, pre-enrichment through a cation resin column, step-by-step adsorption through specific resins (TRU, DGA, strontium resin column, nickel resin column, etc.). In addition, the detection limit of Fe-55 is reduced to 0.71 Bq / L and the detection limit of Sr-90 is 0.08 Bq / L by combining gradient elution (iron→strontium→yttrium→nickel) with decay correction algorithm. The application realizes the online monitoring of the four types of beta nuclides in the liquid effluent of a nuclear power plant for the first time, solves the problem of low efficiency and insufficient detection limit of the traditional method, and provides technical support for the real-time supervision of radioactive discharge of a nuclear power plant.

[0180] The above examples only illustrate the principles and effects of the present application, but are not used to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for joint monitoring of Sr-90, Sr-89, Ni-63, and Fe-55 in liquid effluents, characterized in that, Includes the following steps: Resin column pretreatment: The resin column array is pretreated, and the resin column array includes a first cation resin column, an anion resin column, a second cation resin column, a TRU resin column, a strontium resin column, a DGA resin column and a nickel resin column; Sample pretreatment: Strontium support, yttrium support, iron support and nickel support are added to the liquid effluent, and the pH is adjusted to 1-2 to obtain a mixed solution; Metal ion enrichment: The mixed solution is passed through the first cation exchange resin column, and strontium ions, iron ions and nickel ions are enriched on the first cation exchange resin column; Iron ion elution and adsorption: The first cation resin column is eluted with nitric acid solution. The elution solution is then passed sequentially through the anion resin column, strontium resin column and DGA resin column and collected in a temporary storage tank to obtain the first elution solution. Iron ion separation: The anion exchange resin column is eluted with hydrochloric acid solution, and the eluent is transferred to the second cation exchange resin column. Then, the second cation exchange resin column is eluted with nitric acid solution, and the eluent is transferred to the TRU resin column. Finally, the TRU resin column is desorbed with phosphoric acid solution to obtain Fe-55 desorption solution. Strontium isotope separation: The strontium resin column was desorbed with nitric acid solution, and the DGA resin column was desorbed with hydrochloric acid solution to obtain Sr-89 eluent and Sr-90 eluent, respectively; Nickel ion separation: The first eluent is passed through the nickel resin column, and then the nickel resin column is desorbed with hydrochloric acid solution to obtain Ni-63 desorbent; Activity detection: The activities of Fe-55, Sr-89, Sr-90 and Ni-63 in the Fe-55 desorption solution, the Sr-89 desorption solution, the Sr-90 desorption solution and the Ni-63 desorption solution were measured.

2. The joint monitoring method according to claim 1, characterized in that, The resin column pretreatment step includes: The first cation exchange resin column and the second cation exchange resin column were activated with 0.05-0.1M nitric acid solution at a flow rate of 5-10 mL / min; The nickel resin column was activated using a 2-4 M ammonium citrate solution at a flow rate of 5-10 mL / min. The anion exchange resin column, the TRU resin column, the strontium resin column, and the DGA resin column were activated with 6-8M nitric acid solution at a flow rate of 5-10 mL / min, respectively.

3. The joint monitoring method according to claim 1, characterized in that, In the metal ion enrichment step, the mixed solution is passed through the first cation exchange resin column at a flow rate of 3 to 6 mL / min.

4. The joint monitoring method according to claim 1, characterized in that, In the iron ion elution and adsorption step, the first cation exchange resin column is eluted with a 6-8 mol / L nitric acid solution at a flow rate of 4-6 mL / min. The elution solution adsorbs iron ions through the anion exchange resin column and adsorbs strontium ions and yttrium ions through the strontium resin column and the DGA resin column.

5. The joint monitoring method according to claim 1, characterized in that, The iron ion separation step includes: first washing the anion exchange resin column with a 4-6 mol / L hydrochloric acid solution at a flow rate of 4-6 mL / min; then rinsing the anion exchange resin column with a 0.05-0.1 mol / L hydrochloric acid solution at a flow rate of 4-6 mL / min, transferring the eluted iron ions to the second cation exchange resin column; then rinsing the cation exchange resin column with a 6-8 mol / L nitric acid solution at a flow rate of 4-6 mL / min, transferring the eluted iron ions to the TRU resin column; and finally desorbing the TRU resin column with a 0.5-1 mol / L phosphoric acid solution at a flow rate of 1-3 mL / min to obtain the Fe-55 desorption solution.

6. The joint monitoring method according to claim 1, characterized in that, In the step of separating the strontium isotopes, the strontium resin column is desorbed using a 0.05-0.1 mol / L nitric acid solution at a flow rate of 1-3 mL / min, and the DGA resin column is desorbed using a 0.05-0.1 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min, to obtain Sr-89 desorbent and Sr-90 desorbent.

7. The joint monitoring method according to claim 1, characterized in that, The nickel ion separation step includes adjusting the pH of the first eluent to 8-9 and passing it through the nickel resin column at a flow rate of 4-6 mL / min; then desorbing the nickel resin column with a 2.5-3.5 mol / L hydrochloric acid solution at a flow rate of 1-3 mL / min to obtain Ni-63 desorbent.

8. The joint monitoring method according to claim 1, characterized in that, In the activity detection step, Fe-55 and Ni-63 are measured using liquid scintillation counting, and the activities of Sr-89 and Sr-90 are calculated using the Cherenkov effect combined with decay correction formula. The activity concentrations of Fe-55, Sr-89, and Ni-63 were calculated using formula (1): In formula (1): A represents the radioactivity concentration of Fe-55, Sr-89, or Ni-63 in the liquid effluent, expressed in Bq / L. N represents the net count of the liquid scintillation counter; T represents the measurement time, measured in seconds (s). Y represents the chemical recovery rate of Fe-55, Sr-89, or Ni-63; E represents the measurement efficiency of Fe-55, Sr-89, or Ni-63; V represents the injection volume of Fe-55, Sr-89, or Ni-63, in L; The activity concentration of Sr-90 was calculated using formula (2): In the formula: A Sr-90 This indicates the radioactive concentration of Sr-90 in the liquid effluent, expressed in Bq / L. N represents the net count of the liquid scintillation counter; T represents the measurement time, measured in seconds (s). Y Y90 This indicates the chemical recovery rate of Y-90; E Y90 This indicates the measurement efficiency of Y-90; V represents the injection volume of Sr-90, in L; D represents the decay coefficient, e -0.396t′ / T , where t' is the time interval from the separation of strontium and yttrium to the midpoint of the measurement, in minutes; T is the half-life of Y-90, taken as 3845 minutes; and e is the natural logarithm.

9. The joint monitoring method according to claim 1, characterized in that, The Fe-55 desorption solution, the Sr-89 desorption solution, the Sr-90 desorption solution, and the Ni-63 desorption solution can also be used to measure recovery rate and repeatability. The formula for calculating the recovery rate is shown in equation (3): In formula (3), Y represents the recovery rate; Q is the mass of the tracer in the purified sample, in mg; Q0 is the mass of the tracer added to the sample, in mg, and the tracer is a strontium carrier, yttrium carrier, iron carrier or nickel carrier added to the sample; The formula for calculating the repetition rate is shown in equation (4): In equation (4), RSD represents the repeatability, S represents the standard deviation, and n represents the total number of samples or the number of measurements; x i This represents the measured value of the corresponding component in the material, where i ranges from 1 to n. This represents the average value of n measurements of the corresponding component in the material.

10. The joint monitoring method according to claim 1, characterized in that, The method also includes regenerating the resin column array, the regeneration step comprising: The first and second cation exchange resin columns were rinsed with 0.05–0.1 mol / L nitric acid. The anion exchange resin column, the TRU resin column, the strontium resin column, and the DGA resin column were rinsed with 6-8 mol / L nitric acid, respectively. The nickel resin column was rinsed with a 1-3 mol / L ammonium citrate solution.

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