Method for measuring corrosion product thermodynamic parameters under zinc injection

Abstract

A method for measuring the thermodynamic parameters of corrosion products under zinc injection conditions is disclosed. This method involves detecting the characteristic peak positions of the corrosion products using Raman spectroscopy, comparing them with a standard Raman spectroscopy database to obtain the chemical structure of the corrosion products, and calibrating the peak intensities of standard samples. The concentration of the corrosion products is then obtained based on the relationship between the peak intensities and concentrations of the standard samples. AC conductivity is used to detect the conductivity of the coolant containing the corrosion products, and combined with the concentration information provided by Raman spectroscopy, the ionization constant of the corrosion products is obtained. This invention enables in-situ measurement of the thermodynamic parameters of corrosion products under zinc injection water chemistry conditions, including the chemical structure, concentration, and equilibrium constant of the corrosion products. It solves the problem of missing thermodynamic parameters of corrosion products under current zinc injection water chemistry conditions, laying the foundation for accurately predicting the deposition patterns of corrosion products under these conditions and for model development.

Description

Technical Field

[0001] This invention relates to a technology in the field of reactor control, specifically a method for measuring the thermodynamic parameters of corrosion products under zinc injection. Background Technology

[0002] Due to limitations in current experimental techniques, the thermodynamic parameters of corrosion products under zinc injection hydride chemical conditions are currently calculated theoretically using the Helgeson-Kirkham-Flowers (HKF) model and the Pitzer formula. However, the HKF model lacks the standard partial molar Gibbs free energy parameters of Fe, Ni, and Zn components under the primary loop operating conditions of a pressurized water reactor. This results in the inability to accurately calculate the Gibbs free energy changes and equilibrium constants of various chemical reactions involved in the primary loop corrosion products, and also lacks the ability to analyze structural and concentration equilibrium, conductivity, and in-situ adaptability to high temperature and high pressure. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a method for measuring the thermodynamic parameters of corrosion products under zinc injection conditions. This method enables in-situ measurement of the thermodynamic parameters of corrosion products under zinc injection water chemistry conditions, including the chemical structure, concentration, and equilibrium constant of the corrosion products. It solves the problem of missing thermodynamic parameters of corrosion products under current zinc injection water chemistry conditions, laying the foundation for accurately predicting the deposition patterns of corrosion products under zinc injection water chemistry conditions and developing models.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a method for measuring the thermodynamic parameters of corrosion products under zinc injection. After detecting the characteristic peak positions of the corrosion products by Raman spectroscopy, the chemical structure of the corrosion products is obtained by comparing with a standard Raman spectroscopy database to calibrate the peak intensity of the standard sample. Then, the concentration of the corrosion products is obtained based on the relationship between the peak intensity and concentration of the standard sample. The conductivity of the coolant containing the corrosion products is detected by AC conductivity. Combined with the concentration information provided by Raman spectroscopy, the ionization constant of the corrosion products is obtained.

[0006] This invention relates to a system for measuring the thermodynamic parameters of corrosion products to implement the above-mentioned method, comprising: a Raman detection unit, a concentration analysis unit, a conductivity measurement unit, and an ionization constant calculation unit. Specifically: the Raman detection unit extracts the characteristic peak positions of the corrosion products based on the Raman spectral information of the coolant sample to be tested, and performs spectral identification processing by comparing with a standard Raman spectral database to obtain the chemical structure information of the corrosion products; the concentration analysis unit performs concentration inversion processing based on the characteristic peak intensity information provided by the Raman detection unit, combined with a pre-calibrated standard sample concentration-peak intensity relationship curve, to obtain the quantitative concentration of the target corrosion product; the conductivity measurement unit performs conductivity response analysis processing based on the AC conductivity signal of the coolant containing the corrosion products to obtain the total conductivity of the coolant system; and the ionization constant calculation unit performs thermodynamic inversion processing based on the corrosion product concentration information provided by the concentration analysis unit and the total conductivity data provided by the conductivity measurement unit, establishes an ion dissociation equilibrium model, and obtains the ionization constant of the target corrosion product.

[0007] Technical effect

[0008] This invention combines Raman spectroscopy with AC conductivity to detect the thermodynamic parameters of corrosion products in the coolant under zinc injection conditions in pressurized water reactors (PWRs). By combining standard sample calibration curves, a quantitative relationship is established between Raman characteristic peaks and corrosion product concentrations, solving the problem of inaccurate identification of corrosion product concentrations. Through the linkage analysis of conductivity and Raman concentration, the ionization constants of corrosion products are deduced, forming key thermodynamic data for the primary loop water chemistry of PWRs. Compared with existing technologies, this invention can identify the types of corrosion products in the coolant, measure their concentrations, and assess their ionization behavior, providing comprehensive information and improving measurement efficiency and accuracy. It can be used for online or in-situ detection, avoiding errors caused by coolant cooling and transfer in PWRs. It is more suitable for practical applications under high temperature and high pressure conditions. Furthermore, the detection system has a simple structure, rapid measurement, and can dynamically assess changes in corrosion product behavior, which helps in formulating PWR primary loop water chemistry control strategies. Attached Figure Description

[0009] Figure 1 This is a schematic diagram / flowchart of the invention.

[0010] Figure 2 The Raman characteristic peak positions and intensities of zinc-free corrosion products;

[0011] Figure 3 Raman spectral data showing the positions and intensities of the corrosion products from zinc injection. Detailed Implementation

[0012] like Figure 1 As shown in this embodiment, a method for measuring the thermodynamic parameters of corrosion products under zinc injection is provided, specifically including:

[0013] Step 1: After measuring the characteristic peak positions and peak intensities of corrosion products using Raman spectroscopy, the changes in the type and concentration of corrosion products under zinc injection chemistry are determined by comparing the relationship between the peak intensities and concentrations of calibrated standard samples.

[0014] The Raman spectroscopy measurement refers to the following: when a laser irradiates a molecule / ion, inelastic scattering occurs. The change in the frequency of the scattered light reflects the Raman activity of a specific chemical bond or molecular structure. After the Raman scattered light is filtered to remove stray light, it is received by a CCD (charge-coupled device) detector, which converts the optical signal into an electrical signal. After signal amplification and analog-to-digital conversion (A / D) processing, the signal enters the spectral processing module, and the final output is the characteristic peak position and intensity of the Raman spectrum.

[0015] like Figure 2 and 3 As shown, the horizontal axis represents wavelength, corresponding to the characteristic peak position of the corrosion products, and the vertical axis represents the characteristic peak intensity of the corrosion products. This was obtained by comparing with a standard Raman spectroscopy database. Figure 2 and Figure 3 The chemical structures of corrosion products corresponding to the characteristic Raman peaks were compared and determined to identify the changes in the chemical structures of corrosion products under zinc injection chemistry.

[0016] Step 2: Measure the AC conductivity of the corrosion products using a conductivity probe, specifically including:

[0017] 2.1 AC conductivity measurement is based on the principle that ionization reactions alter the number of migratable ions and conductivity in a solution system. Under zinc-injection water chemistry conditions, the hydrolysis and ionization of corrosion products cause changes in the number of migratable ions in the solution, which are characterized by changes in the real and imaginary parts of the resistivity of the zinc-injection corrosion product solution. Specifically: Where: the real resistance of the solution , Alternating current angular frequency, The resistance of the solution and All of these are fitting parameters.

[0018] 2.2 Obtaining the conductivity of a solution from its resistance. ,in: The conductivity is that of the standard solution. When calculating the conductivity of the solution containing the chemical corrosion products of zinc injection water, the effect of water ionization in the solution is further considered, specifically: According to the theoretical conductivity equation, the equivalent conductivity of the solution is... Where: equivalent concentration C is the molar concentration, and Z is the ionic charge.

[0019] 2.3 Ionization reaction of corrosion products A - +B + AB, its ionization equilibrium constant According to the law of conservation of mass, , Where: C= The initial concentration of corrosion products. This represents the solubility fraction. The ionization equilibrium constant can be further expressed as... ,in: The average activity coefficient of the ion pair. is the average activity coefficient of the corrosion products.

[0020] 2.4 The equivalent conductivity of the solution is expressed using the solubility fraction. Wherein: the total conductivity of free ion i (determined by the chemical structure of corrosion products) , , The ionic equivalent conductivity of the solution at infinite dilution. and These are considered in relation to the electrophoretic correction of free ions and the relaxation effect of free ions, respectively.

[0021] 2.5 The dissolved fraction obtained according to the above steps can be displayed. Based on the chemical structure and concentration of the corrosion products obtained from Raman spectroscopy and the conductivity of the corrosion product solution obtained from AC conductivity, the average activity coefficient of the chemical structure corrosion product ion pairs and the average activity coefficient of the corrosion products are calculated by iteratively executing steps 2.3-2.5, and finally the ionization equilibrium constant K is obtained.

[0022] Through specific practical experiments, Raman spectroscopy measurements were performed on corrosion products in pressurized water reactor coolant under both zinc-free and zinc-filled conditions. AC conductivity was recorded simultaneously during the experiments to aid in determining the ionization behavior of the corrosion products, as detailed below:

[0023] like Figure 2 The image shows the Raman spectrum measured in a coolant system without added zinc ions. The main characteristic peak of the corrosion products is low in intensity and broad in shape, indicating that in a zinc-free environment, the corrosion products coexist with multiple unstable coordination structures, and the proportion of free ions in the system is relatively high. AC conductivity measurements show that conductivity at this stage exhibits a non-linear response with increasing concentration, indicating that the corrosion products have not formed stable complex structures.

[0024] like Figure 3 The image shown is a Raman spectrum measured after injecting a certain concentration of zinc ions into the system. Compared to... Figure 2Several characteristic peaks (such as ~750 cm⁻¹ and ~860 cm⁻¹) were significantly enhanced, and the spectral shape was clearer and sharper, indicating that the introduction of zinc ions promoted the formation of more stable coordination complexes of corrosion products. Simultaneous measurement of AC conductivity showed a decrease in the overall ion mobility and a reduction in the concentration of free ions, verifying the regulatory role of zinc in the complexation-precipitation equilibrium of corrosion products.

[0025] Compared with existing technologies, this method can obtain the changes in the chemical structure and concentration of corrosion products under zinc injection water chemical conditions, as well as the ionization equilibrium constant of corrosion products.

[0026] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A method for measuring the thermodynamic parameters of corrosion products under zinc injection, characterized in that, After detecting the characteristic peak positions of the corrosion products by Raman spectroscopy, the chemical structure of the corrosion products is obtained by comparing with the standard Raman spectroscopy database to calibrate the peak intensity of the standard sample. Then, the concentration of the corrosion products is obtained according to the relationship between the peak intensity and concentration of the standard sample. The conductivity of the coolant containing the corrosion products is detected by AC conductivity. Combined with the concentration information provided by Raman spectroscopy, the ionization constant of the corrosion products is obtained. The conductivity is measured in the following ways: 1) AC conductivity measurement is based on the fact that ionization reactions alter the number of migratable ions and conductivity in a solution system. Under zinc injection hydration conditions, the hydrolysis and ionization of corrosion products cause changes in the number of migratable ions in the solution, which is characterized by changes in the real and imaginary parts of the resistivity of the zinc injection corrosion product solution. Specifically: Where: the real resistance of the solution , Alternating current angular frequency, The resistance of the solution and All are fitted parameters; 2) Obtain the conductivity of the solution based on its resistance. ,in: The conductivity is that of the standard solution. When calculating the conductivity of the solution containing the chemical corrosion products of zinc injection water, the effect of water ionization in the solution is further considered, specifically: According to the theoretical conductivity equation, the equivalent conductivity of the solution is... Where: equivalent concentration C is the molar concentration, and Z is the ionic charge; 3) Regarding the ionization reaction of corrosion products A - +B + AB, its ionization equilibrium constant According to the law of conservation of mass, , Where: C= The initial concentration of corrosion products. The dissolution fraction; the ionization equilibrium constant can be further expressed as ,in: The average activity coefficient of the ion pair. The average activity coefficient of the corrosion products; 4) The equivalent conductivity of the solution is expressed using the solubility fraction. Among them: the total conductivity of free ion i determined by the chemical structure of the corrosion products. , , The ionic equivalent conductivity of the solution at infinite dilution. and These are considered in relation to the electrophoretic correction of free ions and the relaxation effect of free ions, respectively. 5) The dissolved fraction is displayed according to the above steps. Based on the chemical structure and concentration of the corrosion products obtained from Raman spectroscopy and the conductivity of the corrosion product solution obtained from AC conductivity, the average activity coefficient of the chemical structure corrosion product ion pairs and the average activity coefficient of the corrosion products are calculated by iteratively executing steps 3)-5), and finally the ionization equilibrium constant K is obtained.

2. The method for measuring the thermodynamic parameters of corrosion products under zinc injection according to claim 1, characterized in that, The characteristic peak positions of the corrosion products are detected in the following way: When irradiated by laser, molecules / ions undergo inelastic scattering. The change in the frequency of the scattered light reflects the Raman activity of specific chemical bonds. After the Raman scattered light is filtered to remove stray light, it is passed through a charge-coupled device detector, a signal amplification and analog-to-digital conversion module, and a spectral processing model to complete photoelectric signal conversion, signal amplification and analog-to-digital conversion, and spectral analysis, and finally outputs the characteristic peak positions and intensities of the Raman spectrum.

3. A system for measuring the thermodynamic parameters of corrosion products in the method of claim 1 or 2, comprising: The system comprises a Raman detection unit, a concentration analysis unit, a conductivity measurement unit, and an ionization constant calculation unit. Specifically: the Raman detection unit extracts the characteristic peak positions of corrosion products based on the Raman spectrum information of the coolant sample, and performs spectral identification processing by comparing it with a standard Raman spectral database to obtain the chemical structure information of the corrosion products; the concentration analysis unit performs concentration inversion processing based on the characteristic peak intensity information provided by the Raman detection unit, combined with a pre-calibrated standard sample concentration-peak intensity relationship curve, to obtain the quantitative concentration of the target corrosion product; the conductivity measurement unit performs conductivity response analysis processing based on the AC conductivity signal of the coolant containing corrosion products to obtain the total conductivity of the coolant system; and the ionization constant calculation unit performs thermodynamic inversion processing based on the corrosion product concentration information provided by the concentration analysis unit and the total conductivity data provided by the conductivity measurement unit, establishes an ion dissociation equilibrium model, and obtains the ionization constant of the target corrosion product.

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