Method for measuring potassium ions in boron-containing water of nuclear power station

Abstract

The invention belongs to the field of water chemical analysis, and particularly relates to a method for measuring potassium ions in boron-containing water of a nuclear power plant, which comprises the following steps: step 1, calibrating a potassium ion selective electrode by using a potassium ion standard solution to obtain a potassium ion concentration-electromotive force signal standard curve; step 2, using hydrogen peroxide to adjust the boron-containing water sample to be detected to be neutral through oxidation reduction; step 3, adjusting the boron-containing water sample of the to-be-detected sample to be neutral by using hydrochloric acid to obtain a treated boron-containing water sample of the to-be-detected sample; and step 4, inserting the calibrated potassium ion selective electrode into the treated boron-containing water sample of the sample to be detected, and calculating the potassium ion concentration of the sample to be detected through the electromotive force signal according to the standard curve. According to the method, human intervention and medicament use are effectively reduced, radioactive gas release is reduced, and the potassium ion concentration in the dosing system can be rapidly and accurately analyzed.

Description

Technical Field

[0001] The invention belongs to the field of water chemical analysis, and in particular relates to a method for measuring potassium ions in boron-containing water in a nuclear power plant. Background Art

[0002] As an important moderator, boric acid is widely used in the primary circuit of nuclear power plants, including primary circuit coolant, emergency spray system, safety injection system, etc. In order to neutralize boric acid and provide an alkaline environment for the safety system, some units add potassium hydroxide to the main circuit, as well as to the emergency spray system and safety injection system to ensure unit safety and emergency preparedness.

[0003] Therefore, accurately measuring the potassium ion concentration in boron-containing water in nuclear power plants is of great significance to improving the overall safety of pressurized water reactor nuclear power plants.

[0004] At present, the acid-base titration method is used for emergency spraying systems, which has the disadvantages of many sample preparation steps, long analysis time, many types of reagents, and many manual access. At the same time, this method is also interfered by boric acid, resulting in data deviation.

[0005] For the primary coolant and safety injection system, the atomic absorption flame method is usually used. This method requires flammable gas as a combustion agent, the equipment is expensive, and the atomization process produces radioactive gas.

[0006] In summary, the traditional titration and atomic absorption flame method for measuring the potassium ion content in boron-containing water in nuclear power plants has hidden dangers in terms of safety, quality, environmental protection, economy, and radiation protection. It is necessary to find a method for measuring the potassium ion content in boron-containing water in nuclear power plants with less manual operation, fast, stable, and cost-effectiveness. Summary of the invention

[0007] The object of the present invention is to provide a method for measuring potassium ions in boron-containing water in a nuclear power plant, which effectively reduces human intervention and the use of reagents, reduces the release of radioactive gases, and can quickly and accurately analyze the potassium ion concentration in the dosing system.

[0008] The technical solution to achieve the purpose of the present invention is:

[0009] A method for measuring potassium ions in boron-containing water in a nuclear power plant, the method comprising:

[0010] Step 1, calibrating a potassium ion selective electrode using a potassium ion standard solution to obtain a potassium ion concentration-electromotive force signal standard curve;

[0011] Step 2: Using hydrogen peroxide, adjust the boron-containing water sample to be tested to redox neutrality;

[0012] Step 3, using hydrochloric acid to adjust the boron-containing water sample to be tested to neutral acidity and base, to obtain a treated boron-containing water sample to be tested;

[0013] Step 4: insert the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, and calculate the potassium ion concentration of the sample to be tested through the electromotive force signal according to the standard curve.

[0014] The step 1 specifically comprises: using a potassium ion standard solution, inserting a potassium ion selective electrode into the potassium ion standard solution, connecting the potassium ion selective electrode and an ion meter, measuring the electromotive force signal of the potassium ion standard solution, taking the electromotive force as the ordinate and the potassium ion concentration as the abscissa, and obtaining a potassium ion concentration-electromotive force signal standard curve.

[0015] The concentration of the potassium ion standard solution in step 1 is 1×10 -4 mol / L、1×10 -2 mol / L, 1mol / L, and is acid-base neutral and redox neutral.

[0016] The step 2 specifically includes: recording the initial volume of the boron-containing water sample to be tested, measuring the redox potential value of the boron-containing water sample to be tested, adding hydrogen peroxide dropwise until redox neutrality is reached, and then stopping adding hydrogen peroxide dropwise.

[0017] The step 3 specifically comprises: measuring the pH value of the boron-containing water sample to be tested, adding hydrochloric acid until the acid-base neutrality is reached, stopping the addition of hydrochloric acid, and recording the volume of the boron-containing water sample to be tested after treatment.

[0018] The step 4 specifically comprises: inserting the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, connecting the potassium ion selective electrode and the ion meter, measuring the electromotive force signal of the treated boron-containing water sample to be tested, reading the potassium ion concentration corresponding to the electromotive force signal value according to the standard curve, and calculating the potassium ion concentration in the boron-containing water sample to be tested according to the read potassium ion concentration.

[0019] The calculation formula for the potassium ion concentration in the boron-containing water of the sample to be tested in step 4 is:

[0020]

[0021] In the formula,

[0022] C: potassium ion concentration in boron-containing water, g / L;

[0023] C0: potassium ion concentration reading obtained according to the standard curve, mol / L;

[0024] V0: initial volume of sample, mL;

[0025] V1: volume of sample after treatment, mL;

[0026] 39: Molar mass of potassium, g / mol.

[0027] The potassium ion selective electrode comprises: an electrode cap, a cable, a filling hole, an electrode shell, a reference cell, an electrode interior, and a sensitive component; the electrode cap is connected to the electrode shell through a cable, the electrode shell is provided with a reference cell, an electrode internal structure, and a sensitive component, the reference cell is arranged at the periphery of the electrode internal structure, the sensitive component is connected to the bottom of the electrode internal structure, the electrode shell is provided with a filling hole, and the filling hole is communicated with the reference cell.

[0028] The beneficial technical effects of the present invention are:

[0029] 1. The present invention provides a method for measuring potassium ions in boron-containing water in a nuclear power plant. The method no longer uses an indicator, no longer performs acid-base neutralization calculations, no longer performs acid calibration, and no longer atomizes radioactive gases. The average time for analyzing a sample is reduced from 30 minutes to 5 minutes, thereby reducing the human error link, improving accuracy, and improving the level of radiation protection.

[0030] 2. The present invention provides a method for measuring potassium ions in boron-containing water in a nuclear power plant. The method uses a potassium ion selective electrode, and the sample preparation is fast and simple. No toxic or harmful reagents are used during sample preparation, no radioactive gas is generated, and the waste liquid is easy to handle.

[0031] 3. The potassium ion selective electrode used in the method for measuring potassium ions in boron-containing water in a nuclear power plant provided by the present invention has the advantages of fast analysis speed, high analysis accuracy and wide analysis range.

[0032] 4. The measuring device (i.e., potassium ion selective electrode, ion meter) used in the method for measuring potassium ions in boron-containing water in a nuclear power plant provided by the present invention can be used as an online meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a method for measuring potassium ions in boron-containing water in a nuclear power plant provided by the present invention;

[0034] Figure 2 The present invention provides a schematic diagram of the structure of a potassium ion selective electrode used in a method for measuring potassium ions in boron-containing water in a nuclear power plant.

[0035] In the figure:

[0036] 1- ion meter; 2- potassium ion selective electrode; 3- standard solution or sample to be tested;

[0037] 21 - electrode cap; 22 - cable; 23 - filling hole; 24 - electrode housing; 25 - reference cell; 26 - electrode interior; 27 - sensitive component. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0039] This method provides a method for measuring potassium ions in boron-containing water in a nuclear power plant, which specifically includes the following steps:

[0040] Step 1: Use a potassium ion selective electrode as a measurement method, use standard solutions with different potassium ion concentrations to calibrate the electrode, use the electromotive force signal as the ordinate and the concentration as the abscissa to obtain a standard curve with different potassium ion concentration ranges.

[0041] Prepare potassium ion concentration of 1×10 -4 mol / L(3.9mg / L), 1×10 -2 mol / L (390mg / L), 1mol / L (39g / L) standard solution, and check whether it is acid-base neutral and redox neutral;

[0042] Select the range to be used according to Table 1, use the potassium ion standard solution of corresponding concentration, insert the potassium ion selective electrode 2 into the standard solution 3, and connect the potassium ion selective electrode 2 and the ion meter 1, as shown in Figure 1 As shown, the electromotive force signal of the potassium ion standard solution is measured by an ion meter, and a standard curve is drawn on the coordinate paper with the electromotive force as the ordinate and the potassium ion concentration as the abscissa, and with (0,0) and the measured value of the standard solution as two points.

[0043] Table 1 Concentration range corresponding to different potassium ion concentration curves

[0044]

[0045] Step 2: For water samples containing hydrazine, use hydrogen peroxide to adjust the boron-containing water sample to redox neutral.

[0046] The initial volume of the boron-containing water sample to be tested is recorded as V0, the redox potential value of the boron-containing water sample to be tested is measured, 5% concentration hydrogen peroxide is added, and the redox potential of the water sample is monitored until the redox potential value reaches 0mV and reaches redox neutrality, then the addition of hydrogen peroxide is stopped.

[0047] Step 3: Use hydrochloric acid to adjust the boron-containing water sample to be tested to neutral acidity and base to obtain a treated boron-containing water sample to be tested.

[0048] Measure the pH value of the boron-containing water sample of the test sample after adjustment with hydrogen peroxide in step 2, add 1 mol / L hydrochloric acid, and keep monitoring the pH of the water sample until the pH value reaches acid-base neutrality at 7, then stop adding hydrochloric acid to obtain the treated boron-containing water sample of the test sample. At this time, record the volume of the boron-containing water sample of the test sample after treatment as V1.

[0049] Step 4: insert the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, and calculate the potassium ion concentration in the boron-containing water sample to be tested through the electromotive force signal according to the standard curve.

[0050] Estimate the concentration range of the samples to be tested and select the appropriate curve range.

[0051] Insert the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, connect the potassium ion selective electrode 2 and the ion meter 1, measure the electromotive force signal of the treated boron-containing water sample to be tested, and read the potassium ion concentration C0 (mol / L) corresponding to the electromotive force signal value on the coordinate paper.

[0052] According to formula (1), the potassium ion concentration in the boron-containing water of the sample to be tested is calculated.

[0053]

[0054] In the formula,

[0055] C: potassium ion concentration in boron-containing water, g / L;

[0056] C0: potassium ion concentration reading obtained according to the standard curve, mol / L;

[0057] V0: initial volume of sample, mL;

[0058] V1: volume of sample after treatment, mL;

[0059] 39: Molar mass of potassium, g / mol.

[0060] The potassium ion selective electrode used in the measurement method of the present invention is as follows Figure 2 As shown, it includes: an electrode cap 21, a cable 22, a filling hole 23, an electrode shell 24, a reference cell 25, an electrode interior 26, and a sensitive component 27.

[0061] The electrode cap 21 is connected to the electrode shell 24 through a cable 22. A reference cell 25, an electrode internal structure 26, and a sensitive component 27 are provided in the electrode shell 24. The reference cell 25 is arranged on the periphery of the electrode internal structure 26. The sensitive component 27 is connected to the bottom of the electrode internal structure 26. A filling hole 23 is provided on the electrode shell 24, and the filling hole 23 is connected to the reference cell 25.

[0062] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A method for measuring potassium ions in boron-containing water in a nuclear power plant, characterized in that: The method comprises: Step 1, calibrating a potassium ion selective electrode using a potassium ion standard solution to obtain a potassium ion concentration-electromotive force signal standard curve; Step 2: Using hydrogen peroxide, adjust the boron-containing water sample to be tested to redox neutrality; Step 3, using hydrochloric acid to adjust the boron-containing water sample to be tested to neutral acidity and base, to obtain a treated boron-containing water sample to be tested; Step 4: insert the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, and calculate the potassium ion concentration of the sample to be tested through the electromotive force signal according to the standard curve.

2. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 1, characterized in that: The step 1 specifically comprises: using a potassium ion standard solution, inserting a potassium ion selective electrode (2) into the potassium ion standard solution (3), connecting the potassium ion selective electrode (2) and the ion meter (1), measuring the electromotive force signal of the potassium ion standard solution, taking the electromotive force as the ordinate and the potassium ion concentration as the abscissa, and obtaining a potassium ion concentration-electromotive force signal standard curve.

3. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 1, characterized in that: The concentration of the potassium ion standard solution in step 1 is 1×10 -4 mol / L、1×10 -2 mol / L, 1mol / L, and is acid-base neutral and redox neutral.

4. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 2, characterized in that: The step 2 specifically includes: recording the initial volume of the boron-containing water sample to be tested, measuring the redox potential value of the boron-containing water sample to be tested, adding hydrogen peroxide dropwise until redox neutrality is reached, and then stopping adding hydrogen peroxide dropwise.

5. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 4, characterized in that: The step 3 specifically comprises: measuring the pH value of the boron-containing water sample to be tested, adding hydrochloric acid until the acid-base neutrality is reached, stopping the addition of hydrochloric acid, and recording the volume of the boron-containing water sample to be tested after treatment.

6. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 5, characterized in that: The step 4 specifically comprises: inserting the calibrated potassium ion selective electrode into the treated boron-containing water sample to be tested, connecting the potassium ion selective electrode (2) and the ion meter (1), measuring the electromotive force signal of the treated boron-containing water sample to be tested, reading the potassium ion concentration corresponding to the electromotive force signal value according to the standard curve, and calculating the potassium ion concentration in the boron-containing water sample to be tested according to the read potassium ion concentration.

7. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 6, characterized in that: The calculation formula for the potassium ion concentration in the boron-containing water of the sample to be tested in step 4 is: In the formula, C: potassium ion concentration in boron-containing water, g / L; C0: potassium ion concentration reading obtained according to the standard curve, mol / L; V0: initial volume of sample, mL; V1: volume of sample after treatment, mL; 39: Molar mass of potassium, g / mol.

8. The method for measuring potassium ions in boron-containing water in a nuclear power plant according to claim 1, characterized in that: The potassium ion selective electrode comprises: an electrode cap (21), a cable (22), a filling hole (23), an electrode shell (24), a reference cell (25), an electrode interior (26), and a sensitive component (27); the electrode cap (21) is connected to the electrode shell (24) through the cable (22); the electrode shell (24) is provided with a reference cell (25), an electrode interior structure (26), and a sensitive component (27); the reference cell (25) is arranged on the periphery of the electrode interior structure (26); the sensitive component (27) is connected to the bottom of the electrode interior structure (26); the electrode shell (24) is provided with a filling hole (23); and the filling hole (23) is communicated with the reference cell (25).

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