A method for monitoring the activity concentrations of 55 Fe and 59 Fe in the liquid effluents of nuclear power plants

Abstract

The present invention relates to a method for monitoring the activity concentrations of 55 Fe and 59 Fe in the liquid effluent of a nuclear power plant, comprising the following steps: flowing a solution to be measured through a pretreated hydrogen-type cation resin to adsorb metal ions in the solution to be measured, desorbing the metal ions from the hydrogen-type cation resin to form a metal solution, flowing the metal solution through a pretreated iron resin column to adsorb iron in the metal solution, desorbing iron from the iron resin column to form an iron solution, sending the iron solution to an electro-precipitation cell for electrolytic precipitation, and respectively measuring and calculating the activity concentrations of 55 Fe and 59 Fe based on the difference in the detection efficiencies of 55 Fe and 59 Fe by a first proportional counter and a second proportional counter on both sides of the electro-precipitation cell. The monitoring method of the present invention respectively measures and calculates the activity concentrations of 55 Fe and 59 Fe based on the difference in the detection efficiencies of 55 Fe and 59 Fe by a first proportional counter and a second proportional counter on both sides of the electro-precipitation cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental detection, and particularly relates to a method for monitoring the activity concentration of 55 Fe and 59 Fe in the liquid effluent of a nuclear power plant. Background Technique

[0002] 55 Fe is a pure low-energy β-radioactive nuclide with a half-life of 2.73 a, and its decay mode is orbital electron capture (EC) decay. Along with the EC decay, a series of X-rays with extremely low energies are emitted. The X-ray with the highest energy among them is the K α1 with an energy of 5.89875 keV and the K α2 ray with an energy of 5.88765 keV. The energies of these two X-rays are very close. Averaged at 5.9 keV, the X-ray branching ratio is about 25%.

[0003] 59 Fe is a low-energy β-radioactive nuclide with a half-life of 44.49 d and a maximum energy of 149.21 keV. During decay, γ-rays are released simultaneously. Among them, the γ-rays with relatively large branching ratios are the K α1 with an energy of 1099.251 keV and the K α2 ray with an energy of 1291.596 keV, and the branching ratios are 56.5% and 43.3% respectively.

[0004] The 55 Fe and 59 Fe generated in the reactor are mainly produced through neutron activation reactions 54 Fe(n,γ) 55 Fe, 56 Fe(n,2n) 55 Fe and 58 Fe(n,γ) 59 Fe. The target nuclides of the neutron activation reaction 54 Fe, 56 Fe and 58 Fe are all stable isotopes of Fe, and their sources are various metal materials widely used in the reactor. Due to corrosion, a large amount of 55 Fe and 59 Fe will be released into the primary coolant, enter the waste treatment system through the drainage and leakage of the coolant, and enter the solid waste and liquid effluent. After being discharged into the environment through the effluent, 55 Fe may cause certain radiation effects on the public through various channels.

[0005] Currently, in water 59The Fe activity concentration is generally directly measured by a high-purity germanium γ spectrometer. The main disadvantage is the high detection limit, which is not conducive to the emission statistics of radioactive liquid effluents. In China, 55 There is no standard method for monitoring the Fe activity concentration in water. Internationally, the liquid scintillation measurement method is generally adopted, which has a cumbersome operation process and a long cycle. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for monitoring the 55 Fe and 59 activity concentrations of Fe in the liquid effluents of nuclear power plants to overcome the deficiencies of the prior art.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for monitoring the 55 Fe and 59 activity concentrations of Fe in the liquid effluents of nuclear power plants, comprising the following steps: flowing the solution to be measured through a pretreated hydrogen-type cation resin to adsorb metal ions in the solution to be measured, desorbing the metal ions from the hydrogen-type cation resin to form a metal solution, flowing the metal solution through a pretreated iron resin column to adsorb iron in the metal solution, desorbing iron from the iron resin column to form an iron solution, sending the iron solution to an electro-precipitation cell for electrolytic precipitation, and respectively measuring and calculating the 55 Fe and 59 activity concentrations of Fe by the difference in the detection efficiencies of Fe. In some embodiments of the present invention, the electrolyte is a mixed solution of ammonium carbonate and ammonium dihydrogen phosphate. 55 Fe and 59 55

[0009] According to some preferred embodiments of the present invention, the 55 Fe and 59 activity concentrations of Fe are calculated respectively according to the following formulas: Where A1 is the 55 activity concentration of Fe; A2 is the 59 activity concentration of Fe; ε1 is the detection efficiency of the first proportional counter for 55 Fe; ε2 is the detection efficiency of the first proportional counter for 59 Fe; ε3 is the detection efficiency of the second proportional counter for 59 Fe; B1 is the background counting rate of the first proportional counter; B2 is the background counting rate of the second proportional counter; n1 is the measurement counting rate of the first proportional counter; n2 is the measurement counting rate of the second proportional counter; Y is the iron chemical recovery rate; V1 is the volume of the water sample.

[0010] According to some preferred embodiments of the present invention, for55 Fe and 59 the activity concentration of Fe are measured after calculating the chemical recovery rate of iron by using 90 Sr / 90 Y radioactive source; the chemical recovery rate of iron is calculated according to the following formula: where Y is the chemical recovery rate of iron; S is the effective electrodeposition area of iron; c0 is the concentration of iron carrier; V2 is the volume of iron carrier added; μ2 is 90 Sr / 90 the mass attenuation coefficient of Y on the metal sheet; B1 is the background counting rate of the first proportional counter; B2 is the background counting rate of the second proportional counter; N1 is the counting rate of the first proportional counter before electrodeposition; N2 is the counting rate of the first proportional counter after electrodeposition.

[0011] According to some preferred embodiments of the present invention, the pretreatment of the hydrogen-type cation resin is to inject a HNO3 solution with a concentration of 0.1 M into the hydrogen-type cation resin; the desorption of metal ions from the hydrogen-type cation resin is to inject a HNO3 solution with a concentration of 8 M into the hydrogen-type cation resin.

[0012] According to some preferred embodiments of the present invention, the pretreatment of the iron resin column is to inject a HNO3 solution with a concentration of 8 M into the iron resin column; the desorption of iron from the iron resin column is to inject a HNO3 solution with a concentration of 0.01 M into the hydrogen-type cation resin.

[0013] According to some preferred embodiments of the present invention, a first metal sheet and a first proportional counter are arranged above the electro-deposition cell, a second metal sheet and a second proportional counter are arranged below the electro-deposition cell, and the positive and negative electrodes of a direct current are respectively connected to the first metal sheet and the second metal sheet. In the embodiments of the present invention, the metal sheet is a platinum sheet, and a direct current power supply is loaded at both ends of the first platinum sheet and the second platinum sheet to realize the electro-deposition of iron on the surface of the first platinum sheet.

[0014] According to some preferred embodiments of the present invention, a first lead chamber and a second lead chamber are respectively arranged on the upper and lower sides of the electro-deposition cell, the first proportional counter is located in the first lead chamber, the second proportional counter, the stainless steel source conduit, 90 Sr / 90 Y source are located in the second lead chamber, and the 90 Sr / 90 Y source is located in the stainless steel source conduit.

[0015] According to some preferred embodiments of the present invention, the stainless steel conduit includes a vertical portion and an inclined portion, and the inclined portion is located at the bottom end of the vertical portion.

[0016] According to some preferred implementation aspects of the present invention, the solution to be measured is formed by uniformly mixing a water sample and a siderophore. The calculation formula for the injection speed of the siderophore is as follows: ν2 = V2 × ν1 / V1, where: V1 is the volume of the water sample; ν1 is the injection speed of the water sample (the speed of the constant flow pump); V1 is the volume of the added siderophore; ν2 is the set injection speed of the siderophore (the set speed of the adjustable injection pump).

[0017] According to some preferred implementation aspects of the present invention, the iron resin column is a granular resin attached with tributyl phosphate, which can quantitatively adsorb iron under high-concentration nitric acid conditions and rarely adsorb iron under low-concentration acid conditions.

[0018] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art: In the liquid effluent of the nuclear power plant of the present invention 55 Fe and 59 The monitoring method for the activity concentration of Fe, by setting two kinds of resins, first adsorb the metals in the solution to be measured and then desorb to obtain a metal solution, then select to adsorb the iron in the metal solution and desorb to obtain an iron solution, and then deposit the iron by electro-precipitation, and pass the first proportional counter and the second proportional counter on both sides of the electro-precipitation tank to 55 Fe and 59 The difference in the detection efficiency of Fe, respectively measure and calculate the 55 Fe and 59 Activity concentration of Fe. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the overall structure of the monitoring device in the preferred embodiment of the present invention;

[0021] Figure 2 It is a flowchart of the monitoring method in the preferred embodiment of the present invention;

[0022] In the attached drawings: 1. Sampling unit; 11. Water sample storage tank; 12. Constant flow pump; 13. First liquid mass flowmeter; 14. Siderophore storage tank; 15. Adjustable sampling pump; 16. Second liquid mass flowmeter; 2. Enrichment unit; 21. First three-way switching valve; 221. First four-way switching valve; 231. Hydrogen-type cation resin column; 241. First quantitative injection pump; 25. Third quantitative injection pump; 222. Third four-way switching valve; 232. Hydrogen-type cation resin column; 242. Second quantitative injection pump; 3. Separation unit; 311. Second three-way switching valve; 321. Second four-way switching valve; 331. Fe resin column; 341. Third three-way switching valve; 35. Fourth three-way switching valve; 361. First waste liquid bucket; 37. Fourth quantitative injection pump; 312. Fifth three-way switching valve; 322. Third four-way switching valve; 332. Fe resin column; 342. Sixth three-way switching valve; 362. Second waste liquid bucket; 4. Electro-deposition unit and measurement unit; 41. Seventh three-way switching valve; 42. Glass electro-deposition cell; 43. Shut-off valve; 44. Third waste liquid bucket; 45. Fifth quantitative injection pump; 46. First platinum plate; 47. Second platinum plate; 51. First proportional counter; 52. Second proportional counter; 53. First lead chamber; 54. Second lead chamber; 55. Stainless steel source conduit; 56. 90 Sr / 90 Y source. Detailed implementation manners

[0023] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1 In water 55 Fe and 59 Continuous monitoring device for

[0025] As Figure 1-2 shown, the continuous monitoring device for 55 Fe and 59 Fe in water in this embodiment includes a liquid pipeline and a sampling unit 1 sequentially arranged on the liquid pipeline for quantitatively collecting water samples and forming a solution to be measured, an enrichment unit 2 for enriching metal ions in the solution to be measured and then desorbing them to obtain a metal solution, a separation unit 3 for selectively adsorbing iron from the metal solution (iron-containing solution) and then desorbing it to obtain an iron solution, an electro-deposition unit 4 for electro-depositing the iron solution onto the first platinum plate 46, and 55 Fe and 59Measurement unit 4 for continuously measuring the Fe activity concentration.

[0026] The sampling unit includes a water sample injection component and an iron carrier injection component. The water sample injection component successively includes a water sample storage tank, a constant flow pump, and a first liquid mass flowmeter. The iron carrier injection component successively includes an iron carrier storage tank, an injection pump, and a second liquid mass flowmeter. The ends of the water sample injection component and the iron carrier injection component are connected to mix the water sample and the iron carrier to form a solution to be measured. One end of the constant flow pump is connected to the water sample storage tank, and one end of the adjustable injection pump is connected to the iron carrier storage tank (iron carrier storage tank).

[0027] The sampling unit uses the cooperation of the constant flow pump and the first liquid mass flowmeter. According to the monitoring requirements, the sampling volume can be adjusted within the range of 0.2L to 10L, and the iron carrier content in the sample does not change significantly. The Fe carrier concentration is fixed. According to the set sampling volume, the injection speed of the Fe carrier is calculated, and the adjustable injection pump is feedback-controlled to achieve uniform mixing of the water sample and the carrier. The calculation formula is as follows: ν2 = V2×ν1 / V1, where: V1 is the water sample volume; ν1 is the constant flow pump speed; V1 is the volume of the added carrier; ν2 is the set speed of the adjustable injection pump.

[0028] Specifically, according to the measurement requirements, the sampling volume is set on the first liquid mass flowmeter 13 and fed back to the adjustable injection pump 15, and then the injection speed of the Fe carrier is determined. The water sample in the water sample storage tank 11 enters the enrichment unit through the constant flow pump 12 at a speed of 6 mL / min and stops when the volume reaches the set value of the first liquid mass flowmeter 13.

[0029] The enrichment unit includes a first metering injection pump 241, a hydrogen-type cation resin 231, a third metering injection pump 25, a second metering injection pump 242, a hydrogen-type cation resin column 232, and supporting valve joints. The first metering injection pump is used to inject a first activation liquid into the hydrogen-type oxygen ion resin to pre-treat the hydrogen-type cation resin. The hydrogen-type cation resin is used to adsorb metal ions in the solution to be measured after pre-treatment. The third metering injection pump is used to inject a first desorption liquid into the hydrogen-type oxygen ion resin to desorb the metal ions from the hydrogen-type cation resin to form a metal solution.

[0030] Specifically, the first metering injection pump 241 aspirates 10 mL of 0.1 M HNO3 solution, enters the hydrogen-type cation resin column 231 through the first four-way switching valve 221, pre-treats the hydrogen-type cation resin, and the effluent is discharged to the first waste liquid bucket 361 through the second three-way switching valve 311; the solution to be measured successively enters the hydrogen-type cation resin column through the first three-way switching valve 21 and the first four-way switching valve 221. The metal ions in the solution to be measured are enriched on the surface of the pre-treated hydrogen-type cation resin, and the effluent is discharged to the first waste liquid bucket 361 through the second three-way switching valve 311.

[0031] The third metering injection pump 25 aspirates 50 mL of 8 M HNO3 solution and enters the hydrogen-type cation resin column through the first four-way switching valve 221 to desorb the metal ions adsorbed on the surface of the hydrogen-type cation resin, obtaining a desorbed solution (metal solution).

[0032] The separation unit includes a fourth metering injection pump 37, an iron resin column 331, a first waste liquid barrel 361, an Fe resin column 332, a second waste liquid barrel 362, and supporting valve interfaces. The iron resin column is connected to the hydrogen-type cation resin, the third metering injection pump, and the fourth metering injection pump. The third metering injection pump is used to inject a second activation liquid into the iron resin column for pretreatment of the iron resin column. The iron resin column is used to adsorb iron in the metal solution after pretreatment. The fourth metering injection pump is used to inject a second desorption liquid into the iron resin column to desorb iron from the iron resin column to form an iron solution.

[0033] Specifically, the third metering injection pump 25 aspirates 10 mL of 8 M HNO3 solution and enters the Fe resin column 331 through the second four-way switching valve 321 to pretreat the Fe resin. The effluent is discharged to the first waste liquid barrel 361 through the third three-way switching valve 341. The desorbed solution (metal solution) enters the Fe resin column 331 through the second three-way switching valve 311 and the second four-way switching valve 321 in sequence. The iron in the desorbed solution (metal solution) is adsorbed onto the surface of the Fe resin, and the effluent is discharged to the first waste liquid barrel 361 through the third three-way switching valve 341.

[0034] The fourth metering injection pump 37 aspirates 5 mL of 0.01 M HNO3 solution and enters the Fe resin column 331 through the second four-way switching valve 321 to desorb the iron adsorbed on the surface of the Fe resin, obtaining a desorbed solution (iron solution) containing iron ions.

[0035] Both the enrichment unit and the separation unit in this embodiment are designed with one in use and one standby (or one in use and one regenerated). When the first enrichment and separation structure is working, the second enrichment and separation structure performs resin regeneration, stops after completion, and is in standby, and vice versa.

[0036] The electroplating unit mainly includes a glass electroplating cell 42, a stop valve 43, a third waste liquid barrel 44, a fifth metering injection pump 45, a first platinum sheet 46, and a second platinum sheet 47. The first metal sheet and the second metal sheet are respectively located on the upper and lower sides of the electroplating cell. The desorbed solution containing iron ions enters the glass electroplating cell 42 through the third three-way switching valve 341, the fourth three-way switching valve 35, and the seventh three-way switching valve 41 in sequence; the fifth metering injection pump 45 aspirates 5 mL of electrolyte solution (a mixed solution of ammonium carbonate and ammonium dihydrogen phosphate) and enters the glass electroplating cell 42 through the seventh three-way switching valve 41; the positive pole of the direct current is connected to the first platinum sheet 46, and the negative pole of the direct current is connected to the second platinum sheet 47. Using about 70 mA / cm 2Electrodeposit iron at a current density. After the electrolysis is completed, the waste liquid is discharged into the third waste liquid bucket 44 through the stop valve 43.

[0037] The measuring unit includes a first proportional counter 51, a second proportional counter 52, a first lead chamber 53, a second lead chamber 54, a stainless steel source conduit 55, 90 Sr / 90 Y source 56. The first lead chamber and the second lead chamber are respectively located on the upper and lower sides of the electrodeposition cell; the first lead chamber is located above the first metal sheet, the second lead chamber is located below the second metal sheet, the first proportional counter is located in the first lead chamber, and the second proportional counter, the stainless steel source conduit, 90 Sr / 90 Y source is located in the second lead chamber, 90 Sr / 90 Y source is located inside the stainless steel source conduit. The stainless steel conduit includes a vertical portion and an inclined portion, and the inclined portion is located at the bottom end of the vertical portion.

[0038] The first proportional counter 51 records the counting rate B1 before electrodeposition, 90 Sr / 90 when the Y source 56 is at the bottom end of the stainless steel source conduit 55; 90 Sr / 90 when the Y source 56 is at the top end of the stainless steel source conduit 55, record the measurement counting rate N1 of the first proportional counter 51; after the electrodeposition is completed, 90 Sr / 90 when the Y source 56 is at the top end of the stainless steel source conduit 55, record the measurement counting rate N2 of the first proportional counter 51, and calculate the chemical recovery rate of iron; 90 Sr / 90 when the Y source 56 is at the bottom end of the stainless steel source conduit 55, the first proportional counter 51 and the second proportional counter 52 respectively measure the 55 Fe and 59 content of Fe on the surface of the first platinum sheet 46; both the first lead chamber 53 and the second lead chamber 54 are used to shield external radiation interference and reduce the measurement background.

[0039] Example 2 Monitoring method for 55 Fe and 59 activity concentration of Fe in water

[0040] As Figure 1-2 shown, this example provides a method for monitoring 55 Fe and 59 Fe in water based on the monitoring device in Example 1. Combining the content in Example 1, the monitoring method includes the following steps:

[0041] Flow the solution to be measured through a pretreated hydrogen-form cation resin to adsorb metal ions in the solution to be measured, desorb the metal ions from the hydrogen-form cation resin to form a metal solution, flow the metal solution through a pretreated iron resin column to adsorb iron in the metal solution, desorb the iron from the resin column to form an iron solution, and send the iron solution to an electro-precipitation cell for electrolytic precipitation. Use the first proportional counter and the second proportional counter on both sides of the electro-precipitation cell to 55 Fe and 59 the difference in the detection efficiency of Fe, and measure and calculate the 55 Fe and 59 activity concentrations of Fe respectively.

[0042] Specifically, the monitoring method includes the following steps:

[0043] 1) Sampling

[0044] According to the measurement requirements, set the sampling volume on the first liquid mass flowmeter 13 and feedback it to the adjustable sampling pump 15, and then determine the sampling speed of the Fe carrier to achieve uniform mixing of the water sample and the carrier. The water sample in the water sample storage tank 11 enters the enrichment unit through the constant flow pump 12 at a speed of 6 mL / min and stops when the volume reaches the set value of the first liquid mass flowmeter 13 to form the solution to be measured.

[0045] 2) Pretreat the hydrogen-form cation resin

[0046] The first quantitative injection pump 241 aspirates 10 mL of 0.1 M HNO3 solution, enters the hydrogen-form cation resin column 231 through the first four-way switching valve 221, pretreats the hydrogen-form cation resin, and the effluent is discharged to the first waste liquid bucket 361 through the second three-way switching valve 311.

[0047] 3) Adsorb metal ions in the solution to be measured

[0048] Flow the solution to be measured formed in step 1) into the hydrogen-form cation resin column through the first three-way switching valve 21 and the first four-way switching valve 221 in sequence. The metal ions in the solution to be measured are enriched on the surface of the pretreated hydrogen-form cation resin, and the effluent is discharged to the first waste liquid bucket 361 through the second three-way switching valve 311.

[0049] 4) Desorb the metal ions adsorbed on the surface of the hydrogen-form cation resin

[0050] The third quantitative injection pump 25 aspirates 50 mL of 8 M HNO3 solution, enters the hydrogen-form cation resin column through the first four-way switching valve 221, and desorbs the metal ions adsorbed on the surface of the hydrogen-form cation resin to obtain a desorbed solution (metal solution).

[0051] 5) Pretreat the iron (Fe) resin

[0052] The third metering injection pump 25 aspirates 10 mL of 8 M HNO3 solution, enters the Fe resin column 331 through the second four-way switching valve 321 to pre-treat the Fe resin, and the effluent is discharged to the first waste liquid bucket 361 through the third three-way switching valve 341.

[0053] 6) Adsorb iron in the metal solution

[0054] The desorbing solution (metal solution) obtained in step 4) enters the Fe resin column 331 successively through the second three-way switching valve 311 and the second four-way switching valve 321. The iron in the desorbing solution (metal solution) is adsorbed onto the surface of the Fe resin, and the effluent is discharged to the first waste liquid bucket 361 through the third three-way switching valve 341.

[0055] 7) Desorb the iron adsorbed on the surface of the iron (Fe) resin

[0056] The fourth metering injection pump 37 aspirates 5 mL of 0.01 M HNO3 solution, enters the Fe resin column 331 through the second four-way switching valve 321 to desorb the iron adsorbed on the surface of the Fe resin, and a desorbing solution (iron solution) containing iron ions is obtained.

[0057] 8) Electrolysis

[0058] The desorbing solution containing iron ions enters the glass electrodeposition cell 42 successively through the third three-way switching valve 341, the fourth three-way switching valve 35 and the seventh three-way switching valve 41; the fifth metering injection pump 45 aspirates 5 mL of electrolyte solution (a mixed solution of ammonium carbonate and ammonium dihydrogen phosphate), enters the glass electrodeposition cell 42 through the seventh three-way switching valve 41; the positive pole of the direct current is connected to the first platinum sheet 46, the negative pole of the direct current is connected to the second platinum sheet 47, and iron is electrodeposited using a current density of about 70 mA / cm 2 After the electrolysis is completed, the waste liquid is discharged to the third waste liquid bucket 44 through the stop valve 43.

[0059] 9) Measurement and calculation

[0060] The first proportional counter 51 records the counting rate B1 before the electrodeposition and 90 Sr / 90 when the Sr / 90 Sr / 90 Y source 56 is at the bottom end of the stainless steel source conduit 55; 90 Sr / 90 when the Sr / 90 Sr / 90 Y source 56 is at the top end of the stainless steel source conduit 55, the first proportional counter 51 measures the counting rate N1; after the electrodeposition is completed, 90 Sr / 90 when the Sr / Y source 56 is at the top end of the stainless steel source conduit 55, the first proportional counter 51 measures the counting rate N2, and the chemical recovery rate of iron is calculated; 90 Sr / 90 when the Sr / Y source 56 is at the bottom end of the stainless steel source conduit 55, the first proportional counter 51 and the second proportional counter 52 respectively measure the55 Fe and 59 the content of Fe.

[0061] During the entire on-line continuous measurement process, the program records the reading V1 of the first liquid mass flowmeter 13; the reading V2 of the second liquid mass flowmeter 16; the reading N1 of the first proportional counter before electroplating; the reading N2 of the first proportional counter after electroplating; the background B1 of the first proportional counter; the background B2 of the second proportional counter; the reading n1 of the first proportional counter during the measurement of 55 Fe and 59 Fe; the reading n2 of the second proportional counter during the measurement of 55 Fe and 59 Fe, and calculates the chemical recovery rate of iron through formula (1), and calculates the activity concentrations of 55 Fe and 59 Fe in water through formula (2) and formula (3) respectively.

[0062]

[0063] In the formula:

[0064] Y: Chemical recovery rate of iron, %;

[0065] S: Effective electroplating area of iron, cm 2 ;

[0066] c0: Concentration of iron carrier, mg / mL;

[0067] V2: Volume of iron carrier added, mL;

[0068] μ2: 90 Sr / 90 Mass attenuation coefficient of Y on the platinum sheet, cm -1 ;

[0069] B1: Background counting rate of the first proportional counter, CPM;

[0070] N1: Counting rate of the first proportional counter before electroplating, CPM;

[0071] N2: Counting rate of the first proportional counter after electroplating, CPM.

[0072]

[0073] In the formula:

[0074] A1: 55 Activity concentration of Fe, Bq / L;

[0075] ε1: 55 Detection efficiency of the first proportional counter for

[0076] ε2: The first proportional counter pair 59 Detection efficiency of Fe, %;

[0077] ε3: The second proportional counter pair 59 Detection efficiency of Fe, %;

[0078] n1: Measurement counting rate of the first proportional counter, CPM;

[0079] B1: Background counting rate of the first proportional counter, CPM;

[0080] n2: Measurement counting rate of the second proportional counter, CPM;

[0081] B2: Background counting rate of the second proportional counter, CPM;

[0082] Y: Chemical recovery rate of iron, %;

[0083] V1: Volume of water sample, L.

[0084]

[0085] Where:

[0086] A2: 59 Activity concentration of Fe, Bq / L;

[0087] n2: Measurement counting rate of the second proportional counter, CPM;

[0088] B2: Background counting rate of the second proportional counter, CPM;

[0089] ε3: The second proportional counter pair 59 Detection efficiency of Fe, %;

[0090] Y: Chemical recovery rate of iron, %;

[0091] V1: Volume of water sample, L.

[0092] In the water of the present invention 55 Fe and 59 The continuous monitoring device for Fe, which enriches metal ions in the water sample through a hydrogen-type cation resin, desorbs the metal ions on the hydrogen-type cation resin with an 8M HNO3 solution, separates and purifies the desorbing solution through an Fe resin to obtain an iron solution, electroplates the iron ions in the solution onto a platinum sheet through 90 Sr / 90 Y and a proportional counter combination to calculate the chemical recovery rate of iron, measures β rays through a pair of proportional counters, and calculates the 55 Fe and 59 Activity concentration of Fe, with a recovery rate of about 90%, 55 Fe and59 The detection limits of Fe are as low as 0.16 Bq and 0.02 Bq respectively. The structure design of the invention monitoring device is reasonable, the detection accuracy is high, and through the cooperation and control of the system program, one-key operation can be realized, unattended, stable and reliable, and it is applicable to continuous monitoring of 55 55Fe and 59Fe in water.

[0093] The above embodiments are only for explaining the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for monitoring the activity concentrations of 55 Fe and 59 Fe in the liquid effluent of a nuclear power plant, characterized in that It includes the following steps: Flow the solution to be measured through a pretreated hydrogen-form cation resin to adsorb metal ions in the solution to be measured, desorb the metal ions from the hydrogen-form cation resin to form a metal solution, flow the metal solution through a pretreated iron resin column to adsorb iron in the metal solution, desorb the iron from the iron resin column to form an iron solution, send the iron solution to an electro-precipitation cell for electrolytic precipitation, and use the first proportional counter and the second proportional counter on both sides of the electro-precipitation cell to 55 Fe and 59 the difference in the detection efficiency of 55 Fe and 59 Fe, and measure and calculate the activity concentrations of The 55 activity concentrations of 59 Fe and 55 Fe are calculated according to the following formulas respectively: where A1 is the 59 activity concentration of 55 Fe; A2 is the 59 activity concentration of 59 Fe; ε1 is the detection efficiency of the first proportional counter for 55 Fe; ε2 is the detection efficiency of the first proportional counter for 59 Fe; ε3 is the detection efficiency of the second proportional counter for 59 Fe; B1 is the background counting rate of the first proportional counter; B2 is the background counting rate of the second proportional counter; n1 is the measured counting rate of the first proportional counter; n2 is the measured counting rate of the second proportional counter; Y is the iron chemical recovery rate; V1 is the volume of the water sample.

2. The monitoring method according to claim 1, wherein: For 55 Fe and 59 Before measuring the activity concentration of Fe, first measure and calculate the chemical recovery rate of iron through 90 Sr / 90 Y radioactive source; the iron chemical recovery rate is calculated according to the following formula: where Y is the iron chemical recovery rate; S is the effective electrodeposition area of iron; c0 is the iron carrier concentration; V2 is the volume of the added iron carrier; μ2 is 90 Sr / 90 the mass attenuation coefficient of Y on the metal sheet; B1 is the background counting rate of the first proportional counter; B2 is the background counting rate of the second proportional counter; N1 is the counting rate of the first proportional counter before electrodeposition; N2 is the counting rate of the first proportional counter after electrodeposition.

3. The monitoring method according to claim 1, characterized in that: The pretreatment of the hydrogen-type cation resin is to inject a HNO3 solution with a concentration of 0.1 M into the hydrogen-type cation resin; the desorption of the metal ions from the hydrogen-type cation resin is to inject a HNO3 solution with a concentration of 8 M into the hydrogen-type cation resin.

4. The monitoring method according to claim 1, wherein: The pretreatment of the iron resin column is to inject a HNO3 solution with a concentration of 8 M into the iron resin column; the desorption of the iron from the iron resin column is to inject a HNO3 solution with a concentration of 0.01 M into the hydrogen-type cation resin.

5. The monitoring method according to claim 1, characterized in that: A first metal sheet and a first proportional counter are arranged above the electro-precipitation tank, and a second metal sheet and a second proportional counter are arranged below the electro-precipitation tank. The positive and negative electrodes of a direct current are respectively connected to the first metal sheet and the second metal sheet.

6. The monitoring method according to claim 5, wherein: A first lead chamber and a second lead chamber are respectively arranged on the upper and lower sides of the electro-sedimentation tank. The first proportional counter is located in the first lead chamber. The second proportional counter, the stainless steel source conduit, 90 Sr / 90 Y source is located in the second lead chamber. The 90 Sr / 90 Y source is located inside the stainless steel source conduit.

7. The monitoring method according to claim 6, wherein: The stainless steel conduit includes a vertical portion and an inclined portion, and the inclined portion is located at the bottom end of the vertical portion.

8. The monitoring method according to claim 1, wherein: The test solution is formed by uniformly mixing a water sample and an iron carrier. The calculation formula for the injection speed of the iron carrier is as follows: ν2 = V2 × ν1 / V1, where: V1 is the volume of the water sample; ν1 is the injection speed of the water sample; V1 is the volume of the added iron carrier; ν2 is the injection speed of the iron carrier set.

9. The monitoring method according to claim 1, characterized in that: The iron resin column is a granular resin attached with tributyl phosphate.

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