Method and device for rapidly measuring high-concentration 226Ra based on 222Rn generation rate

Abstract

The invention provides a method and a device for rapidly measuring 226Ra activity concentration, and belongs to the technical field of radionuclide detection. The invention provides the concept of radon generation rate in the 226Ra-containing solution, in the 226Ra-222Rn non-equilibrium state, according to the decay law of 226Ra, a theoretical model for measuring radon precipitation of the 226Ra solution in the 226Ra and 222Rn non-decay equilibrium state by a radon measuring instrument is established, and the concentration of 226Ra in the 226Ra-containing solution is obtained through theoretical calculation after the concentration of 222Rn precipitated from the 226Ra-containing solution is measured. Therefore, the activity concentration of the 226Ra in the solution containing the 226Ra can be quickly measured and calculated without waiting for a relatively long balance time (6-7 radon half-life periods) of the 226Ra and the 222Rn.

Description

Technical Field

[0001] The present invention belongs to the technical field of radionuclide detection, and particularly relates to a method and device for rapidly measuring 226 the activity concentration of Background Art

[0002] 226 225 Ac (actinium), 223 213 Bi (bismuth) and other raw materials of α-radionuclides. Therefore, it is necessary to carry out research on the extraction and large-scale production of high-purity 226 226 226 238 U (uranium), 235 U and other daughters with relatively long half-lives. Therefore, a method for rapidly and accurately measuring the 226 226 concentration of

[0003] Existing 226 226 226 222 Rn (radon) decay-generated 222 Rn cumulative amount, which requires the sample to be sealed for several days to accumulate enough 222 Rn, has the disadvantage of long waiting time and does not meet the requirement of rapid on-site measurement of 226 Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method and device for rapidly measuring 226 the activity concentration of 226 226 in a

[0005] solution containing

[0006] The present invention provides a method for rapidly measuring 226 ​​​​​​​​​​​Method for Ra activity concentration, characterized by comprising the following steps:

[0007] Under the condition of vacuum pumping, measure the 226 initial concentration C 222 of Rn in the Ra solution Rn0 , after an accumulation time t1, measure the 226 precipitated 222 Rn concentration C Rn1 in the Ra solution, and obtain the 226 activity concentration A Ra of Ra according to Equation a;

[0008]

[0009] In Equation a: C Rn0 is the initial concentration of Rn in the 226 Ra solution, in Bq / m 222 ; 3 ;

[0010] C Rn1 is the precipitated 222 Rn concentration after the accumulation time t1, in Bq / m 3 ;

[0011] V is the total volume of the space through which Rn flows 222 under the condition of vacuum pumping, in m 3 ;

[0012] λ Rn is the 222 decay constant of Rn, in s -1 ;

[0013] t is 1, in s;

[0014] t1 is the accumulation time, in s;

[0015] A Ra is the 226 activity concentration of Ra, in Bq.

[0016] Preferably, before measuring the initial concentration C Rn0 , it further includes discharging the already generated 226 Rn in the Ra solution, and the discharging time of the 222 Rn is 3 - 10 min. 222 ;

[0017] Preferably, the accumulation time t1 ≥ 10 min.

[0018] Preferably, the total volume is 1 × 10 -3 m 3 .

[0019] The present invention provides a device for rapidly measuring the 226 activity concentration of Ra, comprising a diffuser 1, a flowmeter 3, a radon detector 5 and a vacuum pump 6;

[0020] The vacuum pump 6 is communicated with the outlet of the diffuser 1, and the radon detector 5 is communicated with the outlet of the vacuum pump 6; the flowmeter 3 is communicated with the inlet of the diffuser 1.

[0021] Preferably, the measuring range of the radon detector is 2 - 2000000 Bq / m 3 .

[0022] Preferably, the radon detector comprises a continuous radon detector.

[0023] Preferably, the flowmeter comprises a glass rotameter.

[0024] Preferably, the device further comprises a hydrophobic membrane 4 disposed on the pipeline between the flowmeter 3 and the diffuser 1.

[0025] Preferably, the hydrophobic membrane comprises a polytetrafluoroethylene membrane.

[0026] The present invention provides a method for rapidly measuring the 226 activity concentration of Ra, comprising the following steps: under the condition of vacuum pumping, measuring the 226 initial concentration C 222 of Rn in the Ra solution, after an accumulation time t1, measuring the Rn0 Rn concentration C 226 precipitated from the Ra solution, and obtaining the 222 activity concentration A Rn1 of Ra according to formula a; 226 ; Ra ;

[0027]

[0028] In formula a: C Rn0 is the initial concentration of Rn in the Ra solution, Bq / m 226 ; C 222 is the Rn concentration precipitated after the accumulation time t1, Bq / m 3 ; V is the total volume of the space through which Rn flows under the condition of vacuum pumping, m Rn1 ; λ 222 is the decay constant of Rn, s 3 ; t is 1, s; t1 is the accumulation time, s; A 222 is 3 ; λ Rn is 222 ; t is 1, s; t1 is the accumulation time, s; A -1 ; t is 1, s; t1 is the accumulation time, s; A Ra is226 The activity concentration of Ra, Bq. The present invention indirectly measures 226 the concentration of radon ( 222 Rn) precipitated from the Ra solution, and thus obtains the 226 activity concentration of Ra in the Ra solution, 226 avoiding the methods of directly measuring the activity concentration of Ra, such as liquid scintillation counting method, α energy spectrum method, ICP-MS, etc. The methods in the prior art require a complex experimental process of chemical separation and purification of samples in the early stage of measurement, have a long sample processing time, and are carried out in a professional radiochemistry laboratory, which is not suitable for the on-site environmental measurement experiment of uranium ore; the γ energy spectrum method can directly measure 226 the activity concentration of Ra without chemical treatment of the sample. However, the γ rays released by the decay of 226 U in uranium ore at 185.72 keV (branch ratio 57.5%) interfere with the characteristic γ rays of 235 Ra decay at 186.21 keV (3.59%), and the measurement instrument of the γ spectrometer has high requirements for operating conditions, requiring a specific temperature, humidity and low background experimental environment, which is not suitable for measuring the 226 activity concentration of Ra in the on-site environment of large-scale extraction of 226 Ra. 226 the activity concentration of Ra.

[0029] The present invention proposes the concept of "radon production rate" in the 226 Ra solution, that is, the activity of radon produced per unit time (1 s). In the 226 Ra- 222 Rn non-equilibrium state, according to 226 the decay law of Ra, a theoretical model for radon precipitation from the 226 Ra and 222 Rn non-decay equilibrium state in the 226 Ra solution is established. By measuring the concentration of 226 Rn precipitated from the 222 Ra solution, the concentration of 226 Ra in the 226 Ra solution is theoretically calculated. In this way, it is not necessary to wait for 226 Ra and 222 Rn to reach equilibrium for a long time (6-7 half-lives of radon), and the activity concentration of 226 Ra in the 226 Ra solution can be quickly measured and calculated.

[0030] The method provided by the present invention can quickly, accurately and simply measure the 226 activity concentration of 226 Ra in the 226The activity concentration of Ra has been solved 226 On-site production of Ra products 226 The need for rapid measurement of Ra

[0031] The present invention provides a method for rapidly measuring 226 an apparatus for the activity concentration of Ra, comprising a diffuser 1, a flow meter 3, a radon detector 5 and a vacuum pump 6; the vacuum pump 6 is communicated with the outlet of the diffuser 1, the radon detector 5 is communicated with the outlet of the vacuum pump 6; the flow meter 3 is communicated with the inlet of the diffuser 1. The present invention uses a radon detector (such as an ALPHAGUARD DF2000 continuous radon detector) to replace the scintillation chamber method to measure the 226 radon concentration in Ra solution. The scintillation chamber radon concentration detector consists of a scintillation bottle and a scaler, which are large in volume and mass, and require stable alternating current, and need to be evacuated by a vacuum pump before measurement, which is not suitable for on-site use. The ALPHAGUARD DF2000 continuous radon detector is small in volume and light in weight, and the built-in battery can work automatically for 10 days (diffusion type), which is suitable for on-site radon concentration measurement. And the ALPHAGUARD DF2000 continuous radon detector measures the radon concentration based on the ionization chamber method, has high sensitivity and stability, does not need to dry the gas entering the instrument during measurement, the measurement process is convenient, the measurement result of the standard radium solution is reliable, and the rapid measurement of the radon concentration precipitated from the on-site Ra 226 solution is efficiently realized, meeting the requirements of rapid measurement of the radon concentration in the on-site Ra 226 solution 226 in Ra solution

[0032] Furthermore, the present invention adds a hydrophobic membrane to the upper part of the diffuser, which can prevent the splash and backflow of radon in the Ra solution when using a pump to drain it and the Ra solution during pump-suction radon measurement 226 and the hydrophobicity of the hydrophobic membrane can prevent the splashed solution from penetrating the membrane, causing solution loss and contamination of the instrument 226 BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in 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, other drawings can be obtained based on these drawings without creative efforts

[0034] Figure 1 Schematic diagram of an apparatus for rapidly measuring the 226 activity concentration of Ra according to an embodiment of the present invention, where 1 - diffuser, 3 - flow meter, 4 - hydrophobic membrane, 5 - radon detector, 6 - vacuum pump​ Detailed implementation mode

[0035] The present invention provides a method for quickly measuring 226 the activity concentration of Ra, comprising the following steps:

[0036] Under the condition of vacuum pumping, measure the 226 initial concentration C of 222 Rn in the Ra solution Rn0 . After an accumulation time t1, measure the 226 Rn precipitated in the Ra solution 222 concentration C Rn1 . Obtain the 226 activity concentration A of Ra according to formula a Ra ;

[0037]

[0038] In formula a: C Rn0 is the 226 initial concentration of Rn in the Ra solution, Bq / m 222 ; 3 ;

[0039] C Rn1 is the concentration of Rn precipitated after the accumulation time t1 222 , Bq / m 3 ;

[0040] V is the total volume of the space through which Rn flows under the condition of vacuum pumping 222 , m 3 ;

[0041] λ Rn is 222 the decay constant of Rn, s -1 ;

[0042] t is 1, s;

[0043] t1 is the accumulation time, s;

[0044] A Ra is 226 the activity concentration of Ra, Bq.

[0045] In the present invention, before measuring the initial concentration C Rn0 , it is also preferably included to discharge the 226 already generated 222 Rn in the Ra solution. The 222The discharge time of Rn is preferably 3 to 10 minutes. In the embodiments of the present invention, it can specifically be 3 minutes, 5 minutes, 8 minutes, or 10 minutes. In the present invention, the accumulation time t1 is preferably ≥10 minutes. In the present invention, the 222 space through which Rn flows preferably includes a diffuser, a radon detector chamber, a vacuum pump, and the connecting pipelines between the diffuser, the vacuum pump, and the radon detector. In the present invention, the total volume (V) is 1×10 -3 m 3 ³.

[0046] In the present invention, the flow rate of vacuum pumping is preferably (0.5 - 3)×10 -3 m 3 ³ / min, ensuring that radon can be effectively carried out without causing backflow and splashing of the solution. In the embodiments of the present invention, it can specifically be 0.5×10 -3 m 3 ³ / min, 1×10 -3 m 3 ³ / min, 1.5×10 -3 m 3 ³ / min, 2×10 -3 m 3 ³ / min, 2.5×10 -3 m 3 ³ / min, or 3×10 -3 m 3 ³ / min. The present invention preferably sets the measurement period to 10 minutes, that is, a measurement is carried out every 10 minutes. In the present invention, the measurement period is the same as the accumulation time t1.

[0047] The present invention preferably uses a vacuum pump for vacuum pumping and makes 222 Rn diffuse (by introducing gas into the 226 Ra solution using a vacuum pump, and making the 226 Rn in the 222 Ra solution diffuse out through bubbling) into the measurement chamber of the radon detector for 222 the determination of Rn concentration.

[0048] The present invention indirectly measures the 226 radon ([[]] 222 Rn) concentration precipitated from the 226 Ra solution to obtain the 226 activity concentration of 226Method for Ra activity concentration. The methods in the prior art require a complex experimental process of chemical separation and purification of samples in the early stage of measurement, with a long sample processing time, and are carried out in a professional radiochemistry laboratory, which is not suitable for on-site environmental measurement experiments of uranium ore; the gamma spectrometry method can directly measure 226 Ra activity concentration without chemical treatment of the sample, but there is 235 Interference of the 185.72 keV (branch ratio 57.5%) gamma ray released by the decay of 226 U on the characteristic gamma ray of 186.21 keV (3.59%) generated by the decay of 226 Ra, and the measurement instrument of the gamma spectrometer has high usage conditions and requires a specific temperature, humidity and low background experimental environment, which is not suitable for large-scale extraction of 226 Ra activity concentration in the on-site environment of the

[0049] The present invention proposes the concept of "radon production rate" in a solution containing 226 Ra, that is, the activity of radon generated per unit time (1 s). In the 226 Ra- 222 Rn non-equilibrium state, according to the 226 Decay law of 226 Ra, establish a theoretical model for radon precipitation in a solution containing 222 Ra and 226 Rn in the non-decay equilibrium state. By measuring the concentration of 226 Rn precipitated from the solution containing 222 Ra, the concentration of 226 Ra in the solution containing 226 Ra can be theoretically calculated. In this way, it is not necessary to wait for 226 Ra and 222 Rn to reach equilibrium for a long time (6-7 half-lives of radon), and the activity concentration of 226 Ra in the solution containing 226 Ra can be quickly measured and calculated.

[0050] The method provided by the present invention can quickly, accurately and simply measure the activity concentration of 226 Ra in the solution containing 226 Ra at the on-site of uranium ore / uranium tailings extraction 226 Ra products, and has solved the 226 On-site production of 226 Quick measurement requirement of

[0051] The present invention provides a method for quickly determining using the method described in the above scheme 226A device for measuring the activity concentration of Ra, comprising a diffuser 1, a flow meter 3, a radon detector 5 and a vacuum pump 6; the vacuum pump 6 is communicated with the outlet of the diffuser 1, and the radon detector 5 is communicated with the outlet of the vacuum pump 6; the flow meter 3 is communicated with the inlet of the diffuser 1.

[0052] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products.

[0053] As Figure 1 shown, the device provided by the present invention further comprises a hydrophobic membrane 4 disposed on the pipeline between the flow meter 3 and the diffuser 1. In the present invention, the hydrophobic membrane preferably comprises a polytetrafluoroethylene membrane. By adding a hydrophobic membrane to the upper part of the diffuser in the present invention, it is possible to prevent the splashing and back-suction of radon in the Ra solution when using a pump to drain it and during pump-suction radon measurement, and the hydrophobicity of the hydrophobic membrane can prevent the splashed solution from soaking through the membrane, causing solution loss and contamination of the instrument. 226 radon in the Ra solution, and the splashing and back-suction of the Ra solution during pump-suction radon measurement 226 Moreover, the hydrophobicity of the hydrophobic membrane can prevent the splashed solution from soaking through the membrane, resulting in solution loss and contamination of the instrument.

[0054] In the present invention, the range of the radon detector is preferably 2 - 2000000 Bq / m 3 ; the radon detector preferably comprises a continuous radon detector; the model of the continuous radon detector is preferably ALPHAGUARD DF2000. In the present invention, a radon detector (such as the ALPHAGUARD DF2000 continuous radon detector) is used to replace the scintillation chamber method to measure the radon concentration in the Ra solution. The radon concentration detector of the scintillation chamber consists of two parts, a scintillation bottle and a scaler, which are large in volume and mass, and require a stable alternating current, and need to be evacuated by a vacuum pump before measurement. It is not suitable for on-site use. The ALPHAGUARD DF2000 continuous radon detector is small in volume and light in weight, and the built-in battery can work automatically for 10 days (diffusion type), which is suitable for on-site radon concentration measurement. And the ALPHAGUARD DF2000 continuous radon detector measures the radon concentration based on the ionization chamber method, with high sensitivity and stability. During measurement, it is not necessary to dry the gas entering the instrument, the measurement process is convenient, the measurement result of the standard radium solution is reliable, and it efficiently realizes the rapid measurement of the radon concentration precipitated from the Ra solution on site, meeting the requirement of rapid measurement of the radon concentration in the Ra solution on site in uranium mines. 226 radon in the Ra solution. The radon concentration detector of the scintillation chamber consists of a scintillation bottle and a scaler, which are large in volume and mass, and require a stable alternating current, and need to be evacuated by a vacuum pump before measurement. It is not suitable for on-site use. The ALPHAGUARD DF2000 continuous radon detector is small in volume and light in weight, and the built-in battery can work automatically for 10 days (diffusion type), which is suitable for on-site radon concentration measurement. And the ALPHAGUARD DF2000 continuous radon detector measures the radon concentration based on the ionization chamber method, with high sensitivity and stability. During measurement, it is not necessary to dry the gas entering the instrument, the measurement process is convenient, the measurement result of the standard radium solution is reliable, and it efficiently realizes the rapid measurement of the radon concentration precipitated from the Ra solution on site, meeting the requirement of rapid measurement of the radon concentration in the Ra solution on site in uranium mines. 226 radon in the Ra solution, meeting the requirement of rapid measurement of the radon concentration in the Ra solution on site in uranium mines. 226 radon in the Ra solution on site, meeting the requirement of rapid measurement of the radon concentration in the Ra solution on site in uranium mines. 226 radon concentration in the Ra solution.

[0055] In the present invention, the flow meter preferably comprises a glass rotameter; the flow meter is preferably used to measure the flow rate of the vacuum pump.

[0056] The present invention provides a method for rapidly measuring the 226 activity concentration of Ra by using the device described in the above solution, comprising the following steps:

[0057] Introduce the solution containing 226 Ra into diffuser 1, and use vacuum pump 6 to discharge the 226 Rn that has been generated in the solution containing 222 Ra; under the condition of vacuum pumping by vacuum pump 6, use radon detector 5 to measure the 226 initial concentration C of 222 Rn in the solution containing Rn0 Ra. After the accumulation time t1, use radon detector 5 to measure the 226 Rn concentration C 222 precipitated from the solution containing Rn1 Ra, and obtain the 226 activity concentration A of Ra Ra according to Equation a;

[0058]

[0059] In Equation a: C Rn0 is the initial concentration of 226 Rn in the solution containing 222 Ra, Bq / m 3 ;

[0060] C Rn1 is the concentration of 222 Rn precipitated after the accumulation time t1, Bq / m 3 ;

[0061] V is the total volume of the space through which 222 Rn flows under the condition of vacuum pumping, m 3 ;

[0062] λ Rn is 222 the decay constant of -1 Rn, s

[0063] t is 1, s;

[0064] t1 is the accumulation time, s;

[0065] A Ra is 226 the activity concentration of

[0066] In the present invention, it is preferred to use flowmeter 3 to measure the flow rate of vacuum pump 6. In the present invention, the volume of the solution containing 226 Ra preferably does not exceed 2 / 3 of the diffuser capacity.

[0067] In the present invention, when discharging the 226 Rn that has been generated in the solution containing 222 Ra, it is preferred to connect the vacuum pump 6 to a container filled with the solution containing226 The diffuser 1 of Ra solution 2 is connected to the hydrophobic membrane 4 and the flowmeter 3, and there is no need to connect the radon detector 5. Preferably, the present invention connects the diffuser 1 in the form of an open-loop connection, and contains 226 in the Ra solution that has been generated 222 Rn is discharged and then measured.

[0068] In the present invention, when measuring the initial concentration C Rn0 and the 222 Rn concentration C Rn1 precipitated after the accumulation time t1, it is preferably measured by a radon detector in the form of an open-loop connection, that is, the exhaust port of the radon detector is directly discharged into the ambient atmosphere to form an open-loop measurement.

[0069] In the present invention, the derivation process of the formula a is as follows: the measurement period is set to 10 min;

[0070] Based on 226 Ra and 222 Rn decay law, establish 226 Ra and 222 Rn non-decay equilibrium state (the present invention is a rapid measurement. If it waits for more than 20 days for decay equilibrium, it is not a rapid measurement) 226 The theoretical model of radon precipitation in Ra solution, through rapid measurement 226 The radon concentration generated by Ra per second is deduced and calculated to obtain the 226 activity concentration of Ra in the Ra solution 226 The calculation derivation process is as follows:

[0071] 226 The half-life of Ra is 1602 years, 222 The half-life of Rn is 3.82 days, 226 The 222 cumulative amount of Rn generated by Ra decay has the following relationship:

[0072]

[0073] In formula 1: A Ra is 226 the activity concentration of Ra, Bq;

[0074] A Rn is 222 the cumulative amount of Rn, Bq;

[0075] λ Rn is 222 the decay constant of Rn, s -1 ; λ Rn = 2.1×10 -6 s -1 ;

[0076] t is 1 s (representing 226 the decay time of Ra, 1 s).

[0077] Under the condition of vacuum pumping 222 the total volume of the space through which Rn flows, and the radon concentration is measured to calculate 226 the radon activity generated by the decay of Ra solution within 1 s, and then the 226 Ra activity is calculated. The formula is as follows:

[0078] A Rn = C Rn × V Formula 2;

[0079] The radon activity generated by decay within 1 s is the radon production rate. Substitute C Rn0 , C Rn1 into Formula 2:

[0080]

[0081] In Formula 3: A Rn,1 is the 222 Rn activity generated by decay per second, Bq / s;

[0082] C Rn0 is the initial concentration of 226 Rn in the Ra solution contained in the diffuser, Bq / m 222 ; 3 ;

[0083] C Rn1 is the concentration of 222 Rn precipitated after the accumulation time t1 (10 min), Bq / m 3 ;

[0084] V is the total volume of the space through which 222 Rn flows under the condition of vacuum pumping, m 3 ;

[0085] t1 is the accumulation time, s; t1 = 10 min = 600 s.

[0086] Then, according to the relationship between A Rn and A Rn1 , see Formula 4:

[0087] A Rn = A Rn,1 * t Formula 4;

[0088] Substitute Formula 4 into Formula 1 to get:

[0089]

[0090] In Formula a: C Rn0 is the 226In the Ra solution 222 Initial concentration of Rn, Bq / m 3 ;

[0091] C Rn1 is the Rn concentration precipitated after the accumulation time t1 (10 min), 222 Bq / m 3 ;

[0092] V is the total volume of the space through which Rn flows under the condition of vacuum pumping, 222 m 3 ;

[0093] λ Rn is 222 the decay constant of Rn, s -1 ;

[0094] t is 1, s;

[0095] t1 is the accumulation time, s; t1 = 10 min = 600 s;

[0096] A Ra is 226 the activity concentration of Ra, Bq.

[0097] To further illustrate the present invention, a device and method for rapidly measuring the activity concentration of Ra provided by the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention. 226

[0098] Example 1

[0099] The source of the Ra solution containing 226 is a standard Ra solution with an activity concentration of 26.3 Bq. The concentration of Rn generated by Ra is rapidly measured using a continuous radon monitor, and the activity concentration of Ra in the Ra solution containing is indirectly measured and calculated. 226 226 generated by Ra 222 Rn concentration, and the activity concentration of Ra in the Ra solution containing is indirectly measured and calculated. 226 In the Ra solution 226 Ra

[0100] Drain the Rn that has been generated in the Ra solution containing 226 : 30 mL of the Ra solution containing 222 is filled into the diffuser 1 (the volume of the Ra solution containing does not exceed 2 / 3 of the diffuser capacity). Connect the vacuum pump 6 to the diffuser 1 containing the Ra solution 2, the hydrophobic membrane 4, and the flow meter 3. Do not connect the continuous radon monitor 5; use the vacuum pump 6 with a flow rate of 1 L / min to connect the diffuser 1 containing the Ra solution containing 226 in an open-loop connection form 226 The Rn that has been generated in the Ra solution 226 Ra 226 in the Ra solution​​222 Measure after the Rn is discharged for 5 minutes. The flow rate of the vacuum pump is measured by the glass rotameter 3.

[0101] Measure the 226 Initial 222 Rn concentration C in the Rn0 Ra solution: Connect the ALPHAGUARD DF2000 continuous radon detector 5 to the diffuser 1 filled with 226 Ra solution 2, the hydrophobic membrane 4 (which can prevent the splash and backflow of the 226 Ra solution caused by the operation of the air extraction pump in the radon detector) and the flowmeter 3. The flow rate of the vacuum pump (1 L / min) is measured by the glass rotameter 3. Measure the 226 Rn precipitated from the 222 Ra solution in the form of an open-loop connection using a continuous radon detector, and measure the initial 222 Rn background concentration C (i.e., the Rn0 Rn background concentration in the diffuser 1) 3 .

[0102] Set the measurement period to 10 minutes (representing a measurement every 10 minutes, i.e., the accumulation time t1) during the measurement. Measure the 226 Rn concentration generated by the 222 Ra solution. In the pulse ionization chamber method, it is possible to effectively achieve rapid and efficient measurement of the 226 Rn concentration generated by the decay of the 222 Ra solution. Directly discharge the exhaust port of the continuous radon detector into the ambient atmosphere to form an open-loop measurement.

[0103] Based on 226 Ra and 222 Rn decay laws, establish a theoretical model for radon precipitation from the 226 Ra solution in the non-decay equilibrium state of 222 Ra and 226 Rn using a continuous radon detector. Derive and calculate the 226 Ra activity concentration in the 226 Ra solution by rapidly measuring the 226 Rn concentration generated per second by

[0104] 226 The half-life of 222 Ra is 1602 years, and the half-life of 226 Rn is 3.82 days. The cumulative amount of 222 Rn generated by the decay of

[0105]

[0106] In formula 1: A Ra for 226 Activity concentration of Ra, Bq;

[0107] A Rn for 222 Cumulative amount of Rn, Bq;

[0108] λ Rn for 222 Decay constant of Rn, s -1 ; Rn =2.1×10 -6 s -1 ;

[0109] t is 1s (represents 226 The decay time of Ra is 1s).

[0110] According to the total volume V = 1 × 10 -3 m 3 , the measured radon concentration is calculated 226 The radon activity produced by the decay of Ra solution within 1s is then calculated. 226 Ra activity, the formula is as follows:

[0111] A Rn =C Rn ×V Formula 2;

[0112] The radon activity produced by decay within 1s is the radon production rate. Rn0 , C Rn1 Substitute into formula 2:

[0113]

[0114] In formula 3: A Rn,1 The decay rate per second 222 Rn activity, Bq / s;

[0115] C Rn0 For diffuser 226 Ra solution 222 Initial concentration of Rn, Bq / m 3 ;

[0116] C Rn1 is the precipitation after accumulation time t1 (10min) 222 Rn concentration, Bq / m 3 ;

[0117] V is the condition of vacuum pumping 222 The total volume of space through which Rn flows, 1×10 -3 m 3 ;

[0118] t1 is the accumulation time, in s; t1 = 10 min = 600 s.

[0119] Then, according to the relationship between A Rn and A Rn,1 , see Equation 4:

[0120] A Rn = A Rn,1 *t Equation 4;

[0121] Substitute Equation 4 into Equation 1, and we get:

[0122]

[0123] Substitute the accumulation time t1 = 600 s and t = 1 s into Equation a, and we get:

[0124] (1.26E-3 represents 1.26 * 10 -3 );

[0125] In Equation 6: C Rn0 is the initial concentration of Rn in the Ra solution contained in the diffuser, in Bq / m 226 ; 222 Rn in the 3 ;

[0126] C Rn1 is the concentration of Rn precipitated after the accumulation time t1 (10 min = 600 s), in Bq / m 222 ; 3 ;

[0127] V is the total volume of the space through which Rn flows under the condition of vacuum pumping (i.e., the total volume of the diffuser, the radon detector chamber, the vacuum pump, and the connecting pipelines between the diffuser, the vacuum pump, and the radon detector), 1 × 10 222 m -3 ; 3 ;

[0128] A Ra is 226 the activity concentration of Ra, in Bq.

[0129] Among them, the measured C Rn1＝ is 54.12 Bq / m 3 . Then, according to Equation 6, after calculating the accumulation time of 10 min, the activity concentration of Ra in the Ra solution containing 226 is 24.8 Bq. Compared with the standard 226 Ra solution activity concentration of 26.3 Bq, the relative deviation is 5.7%, which further shows that the method of the present invention is accurate. 226

[0130] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for rapid determination of 226 the activity concentration of Ra, characterized in that It includes the following steps: Under the condition of vacuum pumping, measure the 226 initial concentration C of 222 Rn in the Rn0 Ra solution. After the accumulation time t1, measure the 226 concentration C of 222 Rn precipitated in the Rn1 Ra solution. Obtain the 226 activity concentration A of Ra Ra according to Equation a; In formula a: C Rn0 is the 226 initial concentration of Rn in the Ra solution 222 , Bq / m 3 ; C Rn1 Rn concentration precipitated after the accumulation time t1, Bq / m 222 3 ;​ Under the condition of vacuum pumping 222 Total volume of the space through which Rn flows, m 3 ; λ Rn is 222 the decay constant of Rn, s -1 ; t is 1, s; t1 is the accumulation time, s; A Ra is 226 the activity concentration of Ra, Bq.

2. The method according to claim 1, wherein Measure the initial concentration C Rn0 Before that, it also includes discharging the 226 Rn that has been generated in the Ra solution, and the 222 discharging time of the Rn is 3 - 10 min. 222 ​ 3. The method according to claim 1 or 2, characterized in that, The accumulation time t1 ≥ 10 min.

4. The method according to claim 1, wherein The total volume is 1×10 -3 m 3 .

5. An apparatus for rapidly measuring the 226 activity concentration of Ra by using the method according to any one of claims 1 to 4, characterized in that It includes a diffuser (1), a flowmeter (3), a radon detector (5) and a vacuum pump (6); The vacuum pump (6) is communicated with the outlet of the diffuser (1), and the radon detector (5) is communicated with the outlet of the vacuum pump (6); the flowmeter (3) is communicated with the inlet of the diffuser (1).

6. The device according to claim 5, characterized in that, The measuring range of the radon detector is 2 - 2000000 Bq / m 3 .

7. The device according to claim 5 or 6, characterized in that, The radon detector includes a continuous radon detector.

8. The device according to claim 5, characterized in that, The flowmeter includes a glass rotor flowmeter.

9. The device according to claim 5, 6 or 8, characterized in that The device further includes a hydrophobic membrane (4) disposed on the pipeline between the flowmeter (3) and the diffuser (1).

10. The device according to claim 5, characterized in that, The hydrophobic membrane includes a polytetrafluoroethylene membrane.

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