A low-cost method for preparing nuclear-grade polyacrylic acid and its scale inhibition application.

Abstract

This application discloses a low-cost method for preparing nuclear-grade polyacrylic acid and its scale-inhibiting application, belonging to the fields of nuclear power plant material preparation technology and water treatment technology. The method for preparing the low-cost nuclear-grade polyacrylic acid includes: polymerizing a mixture of acrylic acid monomer, a non-sulfur water-soluble initiator, a chain transfer agent, and a solvent to obtain the low-cost nuclear-grade polyacrylic acid. The nuclear-grade polyacrylic acid obtained by this invention contains inorganic anions Cl... ‑ SO4 2‑ F ‑ The concentrations of all substances were below 1 ppm, and the concentrations of inorganic metal cations sodium, lead, and copper were below 1 ppm, 0.2 ppm, and 0.2 ppm, respectively, meeting the requirements of nuclear power plants for scale inhibitor impurity ions and other performance indicators.

Description

Technical Field

[0001] This application relates to a low-cost method for preparing nuclear-grade polyacrylic acid and its scale-inhibiting application, belonging to the fields of nuclear power plant material preparation technology and water treatment technology. Background Technology

[0002] Pressurized water reactor nuclear power plants operate under high temperature and pressure, resulting in a large amount of corrosion products generated annually due to pipeline corrosion. These corrosion products are mainly composed of oxides formed from metal corrosion and oxidation. After entering the steam generator, these products deposit in the crevices and on the surface of heat transfer tubes, leading to serious consequences such as thermal-hydraulic instability, heat loss, heat transfer tube corrosion, and reduced power output. Therefore, controlling the deposition of corrosion products is crucial to ensuring the performance and integrity of the steam generator, effectively improving the safe operation and economic efficiency of the nuclear power plant. To mitigate scaling within the steam generator, nuclear power plants employ various strategies, such as:

[0003] (1) Stainless steel is used in pipelines instead of easily corroded carbon steel materials to reduce corrosion product sources.

[0004] (2) Optimize the water chemistry control of the secondary loop system, such as increasing the pH value of the feed water to ≥9.5 and reducing the corrosion rate of materials.

[0005] (3) During shutdown, use a high-pressure water gun to flush the sludge on the top of the tube sheet, which can wash away some loose scale and sediment.

[0006] While these methods are effective, they are either not thorough enough or costly. The simple, convenient, and economical removal of corrosion oxides from water has always been a goal of nuclear power plants. Adding water-soluble dispersants to the feedwater system of nuclear power plants can effectively disperse corrosion oxide particles, keeping them suspended in the water before they are discharged into the wastewater system. Polymer dispersants have been widely used in thermal power plants to mitigate sludge scaling in steam generators with great success. These polymer dispersants include polyacrylic acid (PAA), polymethacrylic acid (PMAA), and polymaleic acid (PMA). For example, US Patent 3890228 proposes using polyacrylic acid or polymethacrylic acid together with polyphosphonic acid to treat water in steam generators, effectively preventing the precipitation of carbonates, phosphates, sulfates, etc., on the surface. Wu Bing et al. studied the static scale inhibition of polyacrylic acid-polymaleic acid copolymers, achieving a scale inhibition rate of 96% (Wu Bing et al., Environmental Engineering, 2003, 21(5): 13-14). However, these polymer dispersants used in thermal power plants are usually obtained by initiating the polymerization reaction of monomers using inorganic water-soluble initiators such as sodium persulfate or ammonium persulfate. For example, polyacrylic acid can be easily generated by initiating acrylic acid monomers with a molecular weight between 2000-6000 using ammonium persulfate at a certain temperature (Liang Ping, Gansu Science and Technology, Vol.21(2), 126(2015); Li Pengfei et al., China Water Treatment Technology Symposium, 2016, Nanjing). This polyacrylic acid is commonly used as a scale inhibitor for industrial circulating cooling water, and has a good dispersing and scale inhibition effect on calcium carbonate and calcium phosphate in boilers or thermal power plant steam generators, with a scale inhibition rate of over 55%.

[0007] Scale inhibitors produced using inorganic water-soluble initiators can achieve a certain scale inhibition effect; however, they also present other problems. For example, polyacrylic acid scale inhibitors produced using persulfate as an initiator often have excessive levels of impurities such as sulfur, sodium, and chloride ions. Nuclear power plant structural materials, especially stainless steel and nickel-based alloys, are highly sensitive to these inorganic impurities, which can lead to various forms of corrosion in equipment and pipelines under nuclear power plant operating conditions, seriously threatening the safe operation of the nuclear power plant. If nuclear power plants use polyacrylic acid as a scale inhibitor / dispersant, the aforementioned problems associated with the use of persulfate must be addressed. Summary of the Invention

[0008] According to one aspect of this application, a low-cost method for preparing nuclear-grade polyacrylic acid is provided, which uses a non-sulfur, water-soluble initiator to initiate the process, and with the participation of a chain transfer agent, under conditions where the solvent is ultrapure water, so that the inorganic anion Cl in the obtained nuclear-grade polyacrylic acid is reduced. - SO4 2- F -The concentrations of all components are below 1 ppm, and the concentrations of inorganic metal cations sodium, lead, and copper are below 1 ppm, 0.2 ppm, and 0.2 ppm, respectively. This meets the requirements of nuclear power plants for scale inhibitor impurity ions and other performance indicators. It solves the problem of excessive sulfur, sodium, and chlorine impurity ions in polyacrylic acid produced using persulfate as an initiator in existing technologies, which leads to various types of corrosion in equipment and pipelines and seriously threatens the safe operation of nuclear power plants.

[0009] The method for preparing the low-cost nuclear-grade polyacrylic acid includes: under the protection of an inactive gas, carrying out a polymerization reaction of a mixture of acrylic monomer, non-sulfur water-soluble initiator, chain transfer agent and solvent at a certain temperature to obtain the low-cost nuclear-grade polyacrylic acid;

[0010] The low-cost nuclear-grade polyacrylic acid contains inorganic anions Cl. - SO4 2- F - The concentrations of all inorganic metal cations, sodium, lead, and copper, were all below 1 ppm, 0.2 ppm, and 0.2 ppm, respectively.

[0011] Preferably, the low-cost nuclear-grade polyacrylic acid contains inorganic anions Cl... - SO4 2- F - The concentrations are below 0.5 ppm, 0.3 ppm, and 0.2 ppm, respectively; more preferably, the low-cost nuclear-grade polyacrylic acid contains inorganic anions Cl... - SO4 2- F - The concentrations were 0.429 ppm, 0.286 ppm, and 0.156 ppm, respectively.

[0012] Preferably, the concentrations of inorganic metal cations sodium, lead, and copper in the low-cost nuclear-grade polyacrylic acid are less than 0.4 ppm, 0.1 ppm, and 0.01 ppm, respectively; more preferably, the concentrations of inorganic metal cations sodium, lead, and copper in the low-cost nuclear-grade polyacrylic acid are 0.318 ppm, 0.089 ppm, and 0.008 ppm, respectively.

[0013] In this invention, the concentrations of inorganic anions and inorganic cations are determined using ICP-OES.

[0014] Optionally, the low-cost nuclear-grade polyacrylic acid has a thermal decomposition half-life of 1-4 hours at 280°C; more preferably, the low-cost nuclear-grade polyacrylic acid has a thermal decomposition half-life of 1.5-3.5 hours at 280°C.

[0015] Optionally, the thermal decomposition half-life of the low-cost nuclear-grade polyacrylic acid at 280°C is independently selected from any value of 1.5 hours, 2 hours, 3 hours, 3.5 hours, 4 hours, and any range of both.

[0016] Preferably, the low-cost nuclear-grade polyacrylic acid has a weight-average molecular weight of 50,000-250,000 and a molecular weight distribution of 1-2.5. More preferably, the low-cost nuclear-grade polyacrylic acid has a weight-average molecular weight of 100,000-150,000 and a molecular weight distribution of 1.2-2. When its weight-average molecular weight is 100,000-150,000, it can ensure that it exerts its maximum scale inhibition effect in the steam generator of a pressurized water reactor nuclear power plant.

[0017] Optionally, the weight-average molecular weight of the low-cost nuclear-grade polyacrylic acid is independently selected from any value or a range between 50,000, 80,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 170,000, 200,000, 220,000, and 250,000.

[0018] Specifically, the low-cost nuclear-grade polyacrylic acid resistor has a molecular weight distribution of 1.8 and 1.9.

[0019] In this invention, the weight-average molecular weight and molecular weight distribution are determined using gel permeation chromatography.

[0020] Preferably, the solvent is ultrapure water; more preferably, the resistivity of ultrapure water is ≥18.2 MΩ·cm.

[0021] Optionally, the non-sulfur water-soluble initiator is a water-soluble peroxide compound and / or a water-soluble azo compound.

[0022] Preferably, the water-soluble peroxide compound is one or more selected from peracetic acid, acetyl peroxide, hydrogen peroxide, tert-butyl hydrogen peroxide, 2-isopropionyl peroxide, tert-butyl peracetate, methyl ethyl ketone peroxide, and dialkyl peroxide compounds.

[0023] Preferably, the water-soluble azo compound is one or more of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis[2-(2-imidazolin-2-yl)propane], azobisisobutylamidine, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropamidinium] tetrahydrate, 4,4'-azobis(4-cyanopentanoic acid), and dicyandiamide.

[0024] Optionally, the polymerization reaction temperature is 50-110℃.

[0025] Preferably, the polymerization reaction temperature is 60-90℃.

[0026] Optionally, the temperature of the polymerization reaction is independently selected from any value or a range between 50°C, 60°C, 70°C, 75°C, 80°C, 90°C, 100°C, and 110°C.

[0027] Optionally, the polymerization reaction time is 1-10 hours; more preferably, the polymerization reaction time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or any combination thereof.

[0028] Optionally, the chain transfer agent is one or more of alcohols, aldehydes, and ketones.

[0029] Preferably, the alcohol compound is selected from one or more of the following: propanol, isopropanol, butanol, sec-butanol, tert-butanol, isobutanol, 2-ethylbutanol, 2-methylbutanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, pentanol, tert-pentanol, 3-pentanol, 2-methylpentanol, 4-methyl-2-pentanol, 3-ethyl-3-pentanol, 4-methyl-1-pentanol, hexanol, cyclohexanol, 2-methyl-3-hexanol, 2-ethylhexanol, and 2,5-dimethyl-2,5-hexanediol.

[0030] Preferably, the aldehyde compound is selected from one or more of propionaldehyde, n-butyraldehyde, and isobutyraldehyde.

[0031] Preferably, the ketone compound is selected from one or more of acetone, butanone, and methyl isobutyl ketone.

[0032] Optionally, the weight ratio of the acrylic monomer, the non-sulfur water-soluble initiator, and the chain transfer agent is 10:(0.05-2):(0.5-20); preferably, the weight ratio of the acrylic monomer, the non-sulfur water-soluble initiator, and the chain transfer agent is 10:(0.05-1):(1-15). The acrylic monomer is polymerized in ultrapure water as the solvent. By controlling the content of the chain transfer agent, the molecular weight and molecular weight distribution of the polymerized polyacrylic acid are controlled within an optimal range, thereby achieving a better scale inhibition effect.

[0033] Optionally, the weight ratio of the acrylic monomer, the non-sulfur water-soluble initiator, and the chain transfer agent is independently selected from any one of 10:0.05:1, 10:0.1:3, 10:0.2:1, 10:0.2:3, 10:0.2:5, 10:0.4:3, 10:0.4:7, 10:0.6:3, 10:0.6:9, 10:0.8:11, 10:1:15, and the range of both.

[0034] Optionally, the weight ratio of the solvent to the acrylic monomer is 100:(5-35).

[0035] Optionally, the weight ratio of the solvent to the acrylic monomer is independently selected from any one of 100:5, 100:10, 100:15, 100:20, 100:25, 100:30, 100:35, and any two of them.

[0036] Another aspect of the present invention provides the application of the aforementioned low-cost nuclear-grade polyacrylic acid as a scale inhibitor in the secondary loop cooling water system of nuclear power plants, industrial circulating cooling water, and boiler water.

[0037] The beneficial effects that this application can produce include:

[0038] 1) The present invention provides a low-cost method for preparing nuclear-grade polyacrylic acid, which uses a non-sulfur water-soluble initiator to produce the nuclear-grade polyacrylic acid, meets the requirements of nuclear power plants for impurity ions in scale inhibitors, and the other properties of the produced scale inhibitor meet the requirements of nuclear power plants. It is very suitable for use under the operating conditions of steam generators in pressurized water reactor nuclear power plants, and the cost is low and the process is simple.

[0039] 2) The nuclear-grade polyacrylic acid prepared by this invention has good dispersion and scale inhibition effects on oxides such as ferric hydroxide, which are the main corrosion products in the secondary loop of nuclear power plants. Attached Figure Description

[0040] Figure 1 The dispersion effect of polyacrylic acid on iron hydroxyoxide prepared in Example 2 of this application is shown. Detailed Implementation

[0041] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0042] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0043] Example 1

[0044] This embodiment provides a low-cost method for preparing nuclear-grade polyacrylic acid, specifically comprising the following steps:

[0045] 100g of ultrapure water was added to a 200mL three-necked flask. The mixture was evacuated and then filled with argon gas three times. Under the protection of inert argon gas, 0.2g of water-soluble tert-butyl hydroperoxide initiator, 10g of acrylic acid monomer and 1g of tert-butanol were added in sequence. The mixture was reacted at 70℃ for 2h to obtain a polyacrylic acid solution, which can be used as a scale inhibitor in the secondary cooling water system of nuclear power plants, industrial circulating cooling water and boiler water.

[0046] Among them, the resistivity of ultrapure water is ≥18.2MΩ·cm.

[0047] The molecular weight of the polyacrylic acid scale inhibitor was determined by gel permeation chromatography. The weight-average molecular weight was 141,000 and the molecular weight distribution index was 1.9.

[0048] FT-IR analysis of solid samples revealed that the infrared spectra matched the standard spectra.

[0049] Example 2

[0050] This embodiment provides a low-cost method for preparing nuclear-grade polyacrylic acid, specifically comprising the following steps:

[0051] 100g of ultrapure water was added to a 200mL three-necked flask. The mixture was evacuated and then filled with nitrogen three times. Under the protection of inert nitrogen gas, 0.4g of water-soluble tert-butyl peracetate initiator, 10g of acrylic acid monomer and 3g of pentanol were added in sequence. The mixture was reacted at 75℃ for 3h to obtain a polyacrylic acid solution, which can be used as a scale inhibitor in the secondary cooling water system of nuclear power plants, industrial circulating cooling water and boiler water.

[0052] The molecular weight of the polyacrylic acid scale inhibitor was determined by gel permeation chromatography. The weight-average molecular weight was 117,000, and the molecular weight distribution was 1.8.

[0053] The interaction between the polyacrylic acid produced in this invention and iron hydroxide, a corrosion product generated in nuclear power plants, at different concentrations was investigated using spectrophotometry. The results are shown in Figure 1. Figure 1 These transmittance data show that, without PAA, the transmittance of the FeOOH suspension increases rapidly with time, reaching 60% at 4 hours. This indicates that the FeOOH suspension is extremely unstable and prone to rapid sedimentation, hence the rapid increase in transmittance. Under the influence of 10 ppm and 1000 ppm PAA, the transmittance of the FeOOH suspension remained essentially unchanged within 10 hours, indicating that the FeOOH suspension is very stable under PAA concentrations greater than or equal to 10 ppm. Under 10 ppm PAA, the transmittance of the suspension begins to increase slowly after 10 hours, reaching a maximum of 3%, while under 1000 ppm PAA, the transmittance is almost zero within 12 hours. Therefore, the FeOOH suspension under 1000 ppm PAA is more stable.

[0054] Example 3

[0055] This embodiment provides a low-cost method for preparing nuclear-grade polyacrylic acid, specifically comprising the following steps:

[0056] 100g of ultrapure water was added to a 200mL three-necked flask. The mixture was evacuated and then filled with nitrogen three times. Under the protection of inert nitrogen gas, 0.6g of water-soluble azobisisobutylamidine initiator, 10g of acrylic acid monomer and 5g of isobutyraldehyde were added in sequence. The mixture was reacted at 80℃ for 4h to obtain a polyacrylic acid solution, which can be used as a scale inhibitor in the secondary loop cooling water system of nuclear power plants, industrial circulating cooling water and boiler water.

[0057] The molecular weight of polyacrylic acid was determined by gel permeation chromatography. The weight-average molecular weight was 125,000, and the molecular weight distribution was 1.8.

[0058] The content of inorganic anions and cations in polyacrylic acid was determined using ICP-OES, with the main anion being Cl-. - SO4 2- F - The concentrations were 0.429 ppm, 0.286 ppm, and 0.156 ppm, respectively; the concentrations of the main cations sodium, lead, and copper were 0.318 ppm, 0.089 ppm, and 0.008 ppm, respectively. These anion and cation concentrations are very low, meeting the requirements for use in nuclear power plants.

[0059] Example 4

[0060] This embodiment provides a method for preparing polyacrylic acid. The specific implementation method is the same as that in Embodiment 1, except that the water-soluble tert-butyl hydroperoxide initiator is replaced with acetyl peroxide, while other conditions remain unchanged.

[0061] The molecular weight of polyacrylic acid was determined by gel permeation chromatography, with a weight-average molecular weight of 135,000 and a molecular weight distribution index of 1.8.

[0062] The content of inorganic anions and cations in polyacrylic acid was determined using ICP-OES, with the main anion being Cl-. - SO4 2- F - The concentrations were 0.339 ppm, 0.278 ppm, and 0.127 ppm, respectively; the concentrations of the main cations sodium, lead, and copper were 0.138 ppm, 0.012 ppm, and 0.006 ppm, respectively.

[0063] The interaction between the polyacrylic acid produced in Example 4 and iron hydroxide, a corrosion product from a nuclear power plant, at 1000 ppm was investigated using spectrophotometry. The results showed that under the action of 1000 ppm PAA, the transmittance of the FeOOH suspension increased very slowly within 12 hours, only increasing to 6% at 12 hours.

[0064] Example 5

[0065] This embodiment provides a method for preparing polyacrylic acid. The specific implementation method is the same as that in Embodiment 2, except that the content of pentanol is increased to 15g, while other conditions remain unchanged.

[0066] The molecular weight of polyacrylic acid was determined by gel permeation chromatography, with a weight-average molecular weight of 102,000 and a molecular weight distribution index of 1.9.

[0067] The content of inorganic anions and cations in polyacrylic acid was determined using ICP-OES, with the main anion being Cl-. - SO4 2- F - The concentrations were 0.401 ppm, 0.183 ppm, and 0.177 ppm, respectively; the concentrations of the main cations sodium, lead, and copper were 0.275 ppm, 0.09 ppm, and 0.006 ppm, respectively.

[0068] The interaction between the polyacrylic acid produced in Example 5 and iron hydroxide, a corrosion product from a nuclear power plant, at 1000 ppm was investigated using spectrophotometry. The results showed that under the action of 1000 ppm PAA, the transmittance of the FeOOH suspension increased very slowly within 12 hours, only increasing to 2% at 12 hours.

[0069] Example 6

[0070] This embodiment provides a method for preparing polyacrylic acid. The specific implementation method is the same as that in Embodiment 3, except that the content of isobutyraldehyde is reduced to 1g, while other conditions remain unchanged.

[0071] The molecular weight of polyacrylic acid was determined by gel permeation chromatography, with a weight-average molecular weight of 145,000 and a molecular weight distribution index of 1.7.

[0072] The content of inorganic anions and cations in polyacrylic acid was determined using ICP-OES, with the main anion being Cl-. - SO4 2- F - The concentrations were 0.391 ppm, 0.313 ppm, and 0.105 ppm, respectively; the concentrations of the main cations sodium, lead, and copper were 0.117 ppm, 0.07 ppm, and 0.004 ppm, respectively.

[0073] The interaction between the polyacrylic acid produced in Example 6 and iron hydroxide, a corrosion product from a nuclear power plant, at 1000 ppm was investigated using spectrophotometry. The results showed that under the action of 1000 ppm PAA, the transmittance of the FeOOH suspension increased very slowly within 12 hours, only increasing to 5% at 12 hours.

[0074] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A low-cost method for preparing nuclear-grade polyacrylic acid, characterized in that, Under the protection of an inactive gas, a mixture of acrylic monomer, non-sulfur water-soluble initiator, chain transfer agent, and solvent is polymerized to obtain the low-cost nuclear-grade polyacrylic acid. The solvent is ultrapure water; The non-sulfur water-soluble initiator is a water-soluble peroxide compound and / or a water-soluble azo compound; The low-cost nuclear-grade polyacrylic acid contains inorganic anions Cl. - SO4 2- F - The concentrations of all inorganic metal cations, sodium, lead, and copper, were below 1 ppm, 0.2 ppm, and 0.2 ppm, respectively. The weight ratio of the solvent to the acrylic monomer is 100:(10-35). The weight ratio of the acrylic monomer, the non-sulfur water-soluble initiator, and the chain transfer agent is 10:(0.05-2):(0.5-20).

2. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The resistivity of the ultrapure water 18.2 MΩ·cm.

3. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 60-100℃ for a reaction time of 1-8 h.

4. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The low-cost nuclear-grade polyacrylic acid has a thermal decomposition half-life of 1-4 hours at 280°C.

5. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The low-cost nuclear-grade polyacrylic acid has a thermal decomposition half-life of 1.5-3.5 hours at 280°C.

6. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The low-cost nuclear-grade polyacrylic acid has a weight-average molecular weight of 50,000-200,000 and a molecular weight distribution of 1-2.

5.

7. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 6, characterized in that, The low-cost nuclear-grade polyacrylic acid has a weight-average molecular weight of 100,000-150,000 and a molecular weight distribution of 1.2-2.

8. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The water-soluble peroxide compound is one or more of peracetic acid, hydrogen peroxide, and tert-butyl hydroperoxide; The water-soluble azo compound is one or more of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis[2-(2-imidazolin-2-yl)propane], azobisisobutylamidine, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropamidinium] tetrahydrate, and 4,4'-azobis(4-cyanopentanoic acid).

9. The method for preparing low-cost nuclear-grade polyacrylic acid according to claim 1, characterized in that, The chain transfer agent is one or more of alcohols, aldehydes, and ketones; The alcohol compounds are selected from one or more of the following: propanol, isopropanol, butanol, sec-butanol, tert-butanol, isobutanol, 2-ethylbutanol, 2-methylbutanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, pentanol, tert-pentanol, 3-pentanol, 2-methylpentanol, 4-methyl-2-pentanol, 3-ethyl-3-pentanol, 4-methyl-1-pentanol, hexanol, cyclohexanol, 2-methyl-3-hexanol, 2-ethylhexanol, and 2,5-dimethyl-2,5-hexanediol. The aldehyde compound is selected from one or more of propionaldehyde, n-butyraldehyde, and isobutyraldehyde; The ketone compounds are selected from one or more of acetone, butanone, and methyl isobutyl ketone.

10. The application of a low-cost nuclear-grade polyacrylic acid preparation method according to any one of claims 1-9 as a scale inhibitor in secondary loop cooling water systems of nuclear power plants, industrial circulating cooling water, and boiler water.

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