Treatment method and purification device for primary cooling water in pressurized water nuclear power plant

Abstract

To provide a primary cooling water treatment method which reduces fluorine concentration in primary cooling water containing high concentration of boron in a pressurized water nuclear power plant.SOLUTION: A method of treating primary cooling water in a pressurized water nuclear power plant is provided, the method comprising supplying primary cooling water containing boric acid in primary water purification equipment of the pressurized water nuclear power plant to a purification device comprising a fluorine absorbent to absorb and remove fluoride ions in the primary cooling water so as to produce treated water with reduced fluorine concentration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating primary cooling water of a pressurized water nuclear power plant by removing fluorine from the primary cooling water, and a purification apparatus used therefor. [Background technology]

[0002] A pressurized water nuclear power plant (PWR) is a power generation plant in which primary coolant water is heated in a nuclear reactor and supplied to a steam generator, and secondary coolant water is heated in the steam generator to convert it into steam and supply it to a turbine. It has a primary system line that includes the nuclear reactor and a secondary system line that generates electricity by driving a turbine using steam generated in the steam generator.

[0003] Boric acid, which has a high neutron absorption capacity, is added as a chemical shim to the primary coolant of a PWR in order to control the reactivity of the reactor and ensure stable plant operation. Lithium hydroxide is also added as a pH adjuster to adjust the pH lowered by the boric acid to an appropriate pH and prevent corrosion (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Atomic Energy Society of Japan Japanese Journal, Vol.11, No.1, p.77~90 (2012) Summary of the Invention [Problem to be solved by the invention]

[0005] In the primary cooling system of a PWR, a primary water purification system is installed to purify the primary cooling water for the purpose of maintaining the integrity of the constituent materials and fuel and reducing radiation exposure. The primary water purification system uses a purification device (desalting device) filled with cation exchange resin and anion exchange resin. On the other hand, the primary coolant system of a PWR is required to properly manage the concentrations of boric acid and lithium hydroxide in the primary coolant, which contains boric acid, lithium hydroxide, etc., and trace amounts of impurities such as fluoride ions. Ion exchange resins are used to purify these impurities, but the selectivity of the anion exchange resins used for fluoride ions is significantly lower than that for other anionic impurities such as chloride ions, making removal difficult. In order to maintain the set control value concentration (fluorine concentration of 0.15 ppm or less), the ion exchange resins must be replaced frequently, which is a factor in increasing the amount of radioactive waste.

[0006] Furthermore, there have been no cases where a fluoride ion adsorbent has been used to remove trace amounts of fluoride ions in the presence of high concentrations of boric acid.

[0007] Under these circumstances, an object of the present invention is to provide a method for treating primary coolant and a purification apparatus capable of removing trace amounts of fluoride ions from primary coolant containing a high concentration of boron in a pressurized water nuclear power plant. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the following invention meets the above object, thereby completing the present invention.

[0009] That is, the present invention relates to the following inventions. <1> A method for treating primary cooling water of a pressurized water nuclear power plant, comprising: supplying primary cooling water containing boric acid in a primary water purification facility of the pressurized water nuclear power plant to a purification device including a fluorine adsorbent, and adsorbing and removing fluoride ions in the primary cooling water to produce treated water having a reduced fluorine concentration. <2> The fluorine concentration of the treated water discharged from the purification device is 0.15 ppm or less. <1> The method for treating primary cooling water according to claim 1. <3> The boric acid concentration of the primary cooling water to be treated is 50 ppm or more in boron equivalent concentration. <1> or <2> The method for treating primary cooling water according to claim 1. <4> The fluorine adsorbent is the following adsorbent (A) and / or adsorbent (B): <1> from <3> The method for treating primary cooling water according to any one of the above. Adsorbent (A): Adsorbent containing a hydrated rare earth element hydroxide and a binder resin Adsorbent (B): an adsorbent made of a chelating resin or a cation exchange resin to which polyvalent cationic metal ions are immobilized <5> The hydrous rare earth hydroxide in the adsorbent (A) is cerium(IV) hydroxide n-hydrate (Ce(OH)4 nH2O). <4> The method for treating primary cooling water according to claim 1. <6> In the adsorbent (B), the metal element constituting the polyvalent cationic metal ion is one or more selected from zirconium, aluminum, and calcium. <4> The method for treating primary cooling water according to claim 1. <7> The lithium concentration in the primary cooling water to be treated is between 0.2 ppm and 2.2 ppm. <1> from <6> The method for treating primary cooling water according to any one of the above. <8> The purification device is installed in at least one of the chemical volume control system, the boric acid recovery system, and the spent fuel pit water purification and cooling system in the primary water purification facility. <1> from <7> The method for treating primary cooling water according to any one of the above. <9> The purification device is an existing purification device using an ion exchange resin in the primary water purification facility, The fluorine adsorbent is mixed with the ion exchange resin of the existing purification device, or is layered on top of the resin layer or on the bottom of the resin layer. <8> The method for treating primary cooling water according to claim 1.

[0010] <1a> A purification device for primary cooling water containing boric acid in primary water purification equipment of a pressurized water nuclear power plant, the purification device for primary cooling water including a fluorine adsorbent that adsorbs fluoride ions in the primary cooling water. <2a> The primary cooling water purification device according to <1a>, which is installed in at least one of a chemical volume control system, a boric acid recovery system, and a spent fuel pit water purification and cooling system in the primary water purification facility. <3a> The primary cooling water purification device according to <1a> or <2a>, wherein the purification device is an existing purification device using an ion exchange resin in the primary water purification facility, and the fluorine adsorbent is mixed with the ion exchange resin of the existing purification device, or is layered on top of or under the resin layer. <4a> The method for treating primary cooling water according to any one of <1a> to <3a>, wherein the fluorine adsorbent is the following adsorbent (A) and / or adsorbent (B): Adsorbent (A): Adsorbent containing a hydrated rare earth element hydroxide and a binder resin Adsorbent (B): an adsorbent made of a chelating resin or a cation exchange resin to which polyvalent cationic metal ions are immobilized [Effects of the Invention]

[0011] According to the present invention, in a purification system for primary cooling water of a pressurized water nuclear power plant, it is possible to maintain the fluorine concentration below the control value for a long period of time without frequently replacing the ion exchange resin. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a purification line for primary cooling water of a pressurized water nuclear power plant. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below using examples, etc., but the present invention is not limited to the examples below and can be practiced with any modifications within the scope of the gist of the present invention. In this specification, the symbol "to" is used as an expression including the numerical values ​​or physical quantities before and after it. In addition, in this specification, the expression "A and / or B" includes "A only," "B only," and "both A and B."

[0014] In this specification, "ppm" means "ppm by mass" and is synonymous with "mg / L."

[0015] The present invention relates to a method for treating primary coolant of a pressurized water nuclear power plant (hereinafter referred to as "the method for treating primary coolant of the present invention" or "the treatment method of the present invention"), in which primary coolant containing boric acid in a primary water purification facility of the pressurized water nuclear power plant is supplied to a purification device including a fluorine adsorbent, and fluoride ions in the primary coolant are adsorbed and removed to produce treated water with a reduced fluorine concentration.

[0016] In this specification, pressurized water nuclear power plants are sometimes abbreviated as "PWR." Note that in the primary system of a PWR, the boric acid concentration is generally expressed in boron (B) equivalent, and the lithium hydroxide concentration is generally expressed in lithium (Li) equivalent. Therefore, hereinafter, the boric acid concentration in boron equivalent and the lithium hydroxide concentration in lithium equivalent will be simply expressed as the boron concentration and the lithium concentration, respectively. The concentration of fluoride ions to be removed is expressed as fluorine (F) concentration.

[0017] In this specification, the term "fluorine adsorbent" refers to a material that adsorbs fluoride ions (F - ) and does not include fluorine compounds that do not dissociate into complex ions or free fluoride ions as adsorbents.

[0018] The treatment method of the present invention can adsorb and remove fluoride ions by using a fluorine adsorbent, and can continuously produce treated water with a control value concentration (fluorine concentration of 0.15 ppm or less). According to the present invention, in a purification device for primary coolant of a PWR, it is possible to maintain the fluorine concentration below the control value for a long period of time without frequently replacing the ion exchange resin.

[0019] The method for treating primary cooling water of the present invention may be carried out by installing a new dedicated purification device, or by mixing the ion exchange resin with the ion exchange resin of an existing purification device that uses ion exchange resin, or by stacking the ion exchange resin above or below the ion exchange resin.

[0020] <Primary cooling water> The primary coolant to be treated contains boric acid to control the reactivity of the reactor. The boric acid concentration of the primary coolant to be treated is not particularly limited, but is typically 50 ppm or more, 100 ppm or more, 200 ppm or more, or 300 ppm or more. The boric acid concentration is 5000 ppm or less, 3000 ppm or less, 1000 ppm or less, or 500 ppm or less.

[0021] The primary cooling water to be treated also contains a pH adjuster, such as lithium hydroxide, to adjust the pH lowered by boric acid to an appropriate level and prevent corrosion. The lithium concentration in the primary cooling water to be treated is controlled to a value between 0.2 ppm and 2.2 ppm.

[0022] Furthermore, the primary cooling water to be treated contains impurity fluorine, which originates from additives (boric acid and lithium hydroxide) used in the primary cooling water, in the form of fluoride ions. There are no particular restrictions on the fluorine concentration of the primary cooling water to be treated, but it is typically 10 ppm or less.

[0023] The concentration of each component contained in the primary cooling water to be treated can be measured, for example, by an ion chromatograph or an inductively coupled plasma mass spectrometer (ICP-MS).

[0024] <Fluorine adsorbent> The fluorine adsorbent used in the method for treating primary cooling water of the present invention is preferably the following adsorbent (A) and / or adsorbent (B).

[0025] Adsorbent (A): Adsorbent containing a hydrated rare earth element hydroxide and a binder resin Adsorbent (B): an adsorbent made of a chelating resin or a cation exchange resin to which polyvalent cationic metal ions are immobilized

[0026] The adsorbent (A) and the adsorbent (B) each have a specific adsorption capacity for fluoride ions, and are capable of selectively adsorbing and removing fluoride ions in primary cooling water containing high concentrations of boron and lithium.

[0027] The adsorbent (A) and the adsorbent (B) will be described below.

[0028] <Adsorbent (A)> The adsorbent (A) is an adsorbent containing a hydrated rare earth element hydroxide and a binder resin. The adsorbent (A) is typically an aggregate of particulate hydrous rare earth element hydroxides bonded together with a binder resin.

[0029] Examples of rare earth elements constituting the hydrated rare earth element hydroxide include hydroxides of rare earth elements such as scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), etc. These hydrated rare earth element hydroxides may be of one type or a mixture of two or more types.

[0030] Among the hydrous rare earth element hydroxides, cerium(IV) hydroxide n-hydrate (Ce(OH)4 nH2O) is preferred from the viewpoints of its fluoride ion adsorption ability and availability.

[0031] The particle size (secondary particle size) of the hydrous rare earth element hydroxide is not particularly limited, but for example, the average particle size is 0.2 μm or more and 25 μm or less. If the particle size of the hydrous rare earth element hydroxide is too small, it may be wrapped in the binder resin and may not contact the primary cooling water to be treated sufficiently, while if it is too large, it may not be able to be mixed uniformly with the binder resin.

[0032] The hydrous rare earth element hydroxide preferably has a water content of 1 to 30 parts by weight per 100 parts by weight of the dried product. This water content maintains the fluidity of the hydrous rare earth element hydroxide, allowing it to be mixed appropriately with the binder resin, and the secondary agglomerates of hydrous rare earth element hydroxide particles can be maintained at an appropriate particle size. Therefore, the voids formed between the secondary particles of the hydrous rare earth element hydroxide allow for adequate contact with the water to be treated, preventing the hydroxide from returning to its oxide form and allowing the hydroxide to exert its adsorption effect.

[0033] The binder resin may be any stable resin that can bond particles of the hydrated rare earth element hydroxide to form an aggregate and that does not dissolve in water under the treatment conditions of the primary cooling water. Examples of the binder resin include fluorine-based resins such as polyvinylidene fluoride resins and polytetrafluoroethylene resins, polyvinyl resins, and natural polymers such as alginates, and derivatives thereof. Among these, ethylene-vinyl alcohol copolymer resins, which are polyvinyl resins, are preferred because they can easily contain a high concentration of hydrated rare earth element hydroxide. There are no particular restrictions on the molecular weight of the binder resin, but for example, the number average molecular weight is 500 or more.

[0034] In the adsorbent (A), the content of the hydrated rare earth element hydroxide is not limited as long as it has the desired fluorine adsorption ability, but is, for example, 10 parts by weight or more, preferably 400 parts by weight or more, per 100 parts by weight of the binder resin.

[0035] There are no restrictions on the shape of the adsorbent (A), but since it is used by filling it into a purification device, a spherical shape is particularly preferred, and it is preferable that the adsorbent be a porous molded body or a molded body having a mesh structure that allows the water to be treated (primary cooling water) to pass through the inside of the adsorbent.

[0036] When the adsorbent (A) is uniformly spherical, the average particle size is, for example, 0.2 mm or more and 5.0 mm or less, and preferably 0.5 mm or more and 2.0 mm or less.

[0037] Commercially available products may be used as the adsorbent (A). A suitable commercial product is READ-F(HG), a product name manufactured by Nihon Kaisui Co., Ltd., which uses cerium (IV) hydroxide n-hydrate as the hydrated rare earth element hydroxide and ethylene-vinyl alcohol copolymer resin as the binder resin.

[0038] <Adsorbent (B)> The adsorbent (B) is an adsorbent made of a chelating resin or a cation exchange resin to which polyvalent cationic metal ions are immobilized. Polyvalent cationic metal ions have the ability to adsorb fluorine by forming stable complexes with fluorine in water, and so chelating resins or cation exchange resins to which these ions are immobilized function as fluorine adsorbents.

[0039] In the adsorbent (B), the polyvalent cationic metal ion can be a polyvalent cationic metal ion that forms a stable complex with fluorine. Metal elements constituting the polyvalent cationic metal ion include zirconium, aluminum, calcium, iron, cerium, lanthanum, titanium, etc., and these may be used alone or in combination of two or more. The metal element is preferably one or more selected from zirconium, aluminum, and calcium, and more preferably zirconium or aluminum.

[0040] In the adsorbent (B), the chelating resin is a resin in which a chelating functional group is bonded to a base polymer. The "chelating functional group" in a chelating resin refers to a ligand having multiple coordination sites and is a functional group capable of forming a chelate with a polyvalent cationic metal ion. There are no limitations on the type of the chelating functional group as long as it can immobilize a polyvalent cationic metal ion. Examples of the chelating functional group include a polyamine group, a bispicolylamine group, an isothionium group, a dithiocarbamic acid group, an iminodiacetic acid group, a glucamine group, a bispicolylamine group, an aminomethylphosphonic acid group, and an aminophosphate group.

[0041] In the adsorbent (B), the cation exchange resin is a resin in which cation exchange groups are bound to a base polymer. The type of cation exchange group is not limited as long as it can immobilize polyvalent cationic metal ions, and includes, for example, functional groups such as sulfonic acid groups, carboxylic acid groups, phosphonic acid groups, phosphinic acid groups, phenoxide groups, and arsenous acid groups. Depending on the type of functional group, cation exchange resins are classified as strong acid cation exchange resins and weak acid cation exchange resins. When the adsorbent (B) is a cation exchange resin, it may be either a strongly acidic cation exchange resin or a weakly acidic cation exchange resin, but a strongly acidic cation exchange resin is preferably used.

[0042] As the base polymer in the chelating resin and cation exchange resin, any polymer can be used as long as it does not impair the object of the present invention, and examples thereof include styrene-based crosslinked copolymers and (meth)acrylic crosslinked copolymers. In the present invention, "(meth)acrylic" refers to a combination of "acrylic" and "methacrylic".

[0043] In the present invention, the term "styrene-based cross-linked copolymer" refers to a cross-linked copolymer obtained by copolymerizing a monovinyl aromatic monomer with a cross-linkable aromatic monomer, and the term "(meth)acrylic cross-linked copolymer" refers to a cross-linked copolymer obtained by copolymerizing a (meth)acrylic monomer with a cross-linkable (meth)acrylic monomer.

[0044] Examples of the monovinyl aromatic monomer include alkyl-substituted styrenes such as styrene, methylstyrene, and ethylstyrene, and halogen-substituted styrenes such as bromostyrene. These may be used alone or in combination of two or more. Among these, styrene or a monomer mainly composed of styrene is preferred as the monovinyl aromatic monomer.

[0045] Examples of crosslinkable aromatic monomers include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis(vinylphenyl)methane, bis(vinylphenyl)ethane, bis(vinylphenyl)propane, and bis(vinylphenyl)butane. These may be used alone or in combination of two or more. Among these, divinylbenzene is preferred as the crosslinkable aromatic monomer. Industrially produced divinylbenzene usually contains a large amount of ethylvinylbenzene (ethylstyrene) as a by-product, and such divinylbenzene can also be used in the present invention.

[0046] Examples of (meth)acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-(meth)acrylate, iso-butyl (meth)acrylate, t-butyl (meth)acrylate, n-butyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0047] Examples of crosslinkable (meth)acrylic monomers include polymethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0048] Commercially available products may be used as the adsorbent (B). Examples of commercially available products using zirconium include fluorine adsorption resins manufactured by Muromachi Chemical Co., Ltd., trade names of which are Muromac XSS-530B, Muromc XSS-5630, Muromac XMS-5630, and Muromac XMS-5631. Examples of commercially available products using aluminum include fluorine adsorption resins manufactured by Muromachi Chemical Co., Ltd., trade names of which are Muromac XMS-520B-Al.

[0049] The adsorbent (B) may be either a gel type or a porous type. In the present invention, resins generally called "high-porous type" are also included in the meaning of "porous type."

[0050] There are no restrictions on the shape of the adsorbent (B), but since it is used by filling it into a purification device, a spherical shape is particularly preferred, and it is preferable that the adsorbent be a porous molded body or a molded body having a mesh structure that allows the water to be treated (primary cooling water) to pass through the inside of the adsorbent.

[0051] The primary cooling water purification apparatus of the present invention is a purification apparatus that executes the primary cooling water treatment method of the present invention. That is, the primary cooling water purification device of the present invention is a purification device for primary cooling water containing boric acid in a primary water purification facility of a pressurized water nuclear power plant, and is a purification device including a fluorine adsorbent that adsorbs fluoride ions in the primary cooling water.

[0052] The primary cooling water purification device of the present invention is usually incorporated into the primary water purification facility of an existing pressurized water nuclear power plant.

[0053] An embodiment of a primary water purification system for a pressurized water nuclear power plant equipped with a primary coolant purification device of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiment, and can be implemented with any modifications within the scope of the present invention. The dimensions, materials, and other specific numerical values ​​shown in the embodiment are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted where appropriate.

[0054] In this specification, the term "line" is a general term for a line such as a flow path, a passage, or a conduit through which a fluid can flow.

[0055] In the following description, explanations that overlap with those of the method for treating primary cooling water of the present invention (primary cooling water, fluorine adsorbent, etc.) may be omitted.

[0056] FIG. 1 is a schematic diagram showing a purification line for primary cooling water in a primary cooling system facility of a pressurized water nuclear power plant according to an embodiment of the present invention. The primary cooling system equipment 1 of the pressurized water nuclear power plant is equipment used to circulate the primary cooling water that cools the nuclear reactor 2 and to purify the primary cooling water.

[0057] The primary cooling water that has cooled the reactor 2 is at high temperature and high pressure (for example, a temperature of 280°C or higher and a pressure of 15 MPa or higher). The primary cooling water that has cooled the reactor 2 is circulated through a primary cooling water circulation line 3 by a pump P1, and generates steam of the secondary cooling water that is used for power generation by heat exchange with secondary cooling water supplied via a secondary cooling water line 5 in a steam generator 4.

[0058] A portion of the primary cooling water passes through the primary cooling water extraction line 6, is cooled in the heat exchanger 12, and then is extracted outside the reactor containment vessel and supplied to the chemical volume control system, which is a system that chemically purifies the primary cooling water and maintains its volume constant. The primary cooling water taken out of the reactor containment vessel is supplied to a purification device 13 or a purification device 13a via a chemical volume control line 11, and then, if necessary, to a lithium removal device 14, where impurity ions and radioactive nuclides contained in the primary cooling water are removed.

[0059] The purification device 13 is a mixed-bed demineralization device (demineralization tower) and has the same configuration as a mixed-bed demineralization device used in a chemical volumetric control system through which primary cooling water of a conventionally known pressurized water nuclear power plant flows, except that it includes the above-mentioned fluorine adsorbent of the present invention. That is, the purifier 13 is a purifier in which a fluorine adsorbent is added to an existing mixed-bed demineralization apparatus packed with a mixture of a strongly acidic cation exchange resin and a strongly basic anion exchange resin. In this embodiment, the above-mentioned fluorine adsorbent of the present invention is mixed with ion exchange resins (strongly acidic cation exchange resin and strongly basic anion exchange resin) and used in the purification apparatus 13, which is an existing mixed-bed demineralization apparatus. However, the fluorine adsorbent may be disposed so as to be layered on the upper or lower part of the resin layer.

[0060] The purifier 13a is a demineralizer (demineralization tower) filled with a mixture of a strongly acidic cation exchange resin, a strongly basic anion exchange resin, and the fluorine adsorbent of the present invention, similar to the purifier 13. In this embodiment, the purifier 13a is designed to contain a higher proportion of the fluorine adsorbent of the present invention than the purifier 13.

[0061] In this embodiment, the fluorine concentration (inlet concentration and outlet concentration, respectively) in the primary cooling water before and after it is supplied to the purification device 13 or the purification device 13a is continuously monitored (not shown), and the purification device 13 or the purification device 13a is selected so that the outlet concentration of the purified primary cooling water (treated water) is equal to or less than the control value of 0.15 ppm fluorine concentration. That is, when the fluorine concentration of the primary cooling water to be treated is low, it is treated by the purifier 13, and when the fluorine concentration is high, it is treated by the purifier 13a, which has better fluorine removal performance.

[0062] The amount of the fluorine adsorbent to be filled in the purifier 13 and the purifier 13a is appropriately selected in proportion to the existing ion exchange resin, taking into consideration the primary cooling water to be treated (concentrations of contained components, treatment amount, etc.) so that the fluorine concentration falls within the control value.

[0063] In this embodiment, the purifier 13 or the purifier 13a is designed to have different fluorine removal performances, but it may be designed to have the same fluorine removal performance. In this embodiment, the purifier 13 and the purifier 13a are arranged in parallel, but they may be arranged in series. In this case, either the purifier 13 or the purifier 13a may be filled with only the fluorine adsorbent of the present invention.

[0064] The above-described adsorbent (A) and / or adsorbent (B) is used as the fluorine adsorbent mixed and packed in the purification device 13 or 13a of this embodiment. As described above, the adsorbent (A) and the adsorbent (B) each have a specific adsorption power for fluoride ions and can selectively adsorb and remove fluoride ions in primary cooling water containing high concentrations of boron and lithium.

[0065] The primary cooling water purified by the purification device 13 or the purification device 13a (and the lithium removal device 14, if necessary) is supplied to the volume control tank 15, and then returned to the primary cooling water circulation line 3 via the heat exchanger 12 by the pump P2.

[0066] In a boric acid recovery system for controlling the boric acid concentration in the primary cooling water, a portion of the primary cooling water is intermittently supplied to a hold-up tank 22 via a boric acid recovery line 21 before being supplied to a volume control tank 15. The primary cooling water in the hold-up tank 22 is purified by a purifier 23 or a purifier 23 a, concentrated by a boric acid concentrator 24 , and then supplied to a boric acid tank 25 .

[0067] The purifier 23 has the same configuration as a mixed-bed demineralizer used in a boric acid recovery system through which primary cooling water of a conventional pressurized water nuclear power plant flows. That is, the purifier 23 is an existing mixed-bed demineralizer packed with a mixture of a strong acid cation exchange resin and a strong basic anion exchange resin. In this embodiment, a purifier 23a is disposed in parallel with the purifier 23, and the purifier 23a is a single-bed purifier using only a fluorine adsorbent.

[0068] The amount of the fluorine adsorbent packed in the purification device 23a is appropriately selected in consideration of the primary cooling water to be treated (concentration of contained components, treatment amount, etc.).

[0069] In this embodiment, an existing mixed-bed demineralization apparatus that does not contain a fluorine adsorbent is used as the purifier 23, and a single-bed purifier that uses only a fluorine adsorbent is used as the purifier 23a. In other words, the purifiers 23 and 23a are designed to have different fluorine removal performances, but they may also be designed to have the same fluorine removal performance.

[0070] The primary cooling water purified by the purification device 23 or 23a is concentrated by the boric acid concentration device 24 and stored as a concentrated boric acid solution in the boric acid tank 25. The concentration of the stored concentrated boric acid solution is adjusted with pure water from the pure water tank 34, and the solution is supplied to the primary cooling water circulation line 3 via the boric acid / pure water supply line 26 and the heat exchanger 12 by the pump P2.

[0071] The steam generated in the boric acid concentrator 24 during boric acid concentration is condensed in the heat exchanger 32, then passes through the condensate line 31 and is purified in the mixed-bed demineralizer 33, and is then supplied to the pure water tank 34 and stored therein. When the concentration of boric acid in the primary cooling water is high, the pure water in the pure water tank 34 is used as dilution water, and is supplied to the primary cooling water circulation line 3 via the boric acid / pure water supply line 26 and the heat exchanger 12 by the pump P2.

[0072] The purifier 33 has the same configuration as a mixed-bed demineralizer used in the condensate line of a conventionally known pressurized water nuclear power plant. That is, the purifier 33 is an existing mixed-bed demineralizer packed with a mixture of a strong acid cation exchange resin and a strong basic anion exchange resin.

[0073] In this embodiment, the purifying device 33 does not include a fluorine adsorbent, but the purifying device 33 may include a fluorine adsorbent.

[0074] Although the embodiments of the present invention have been described above with reference to the drawings, the embodiments disclosed herein are illustrative in all respects and are not limiting. In particular, in the embodiments disclosed herein, matters not expressly disclosed, such as operating conditions, operating conditions, various parameters, dimensions, weights, volumes of components, etc., do not deviate from the scope of ordinary practice by a person skilled in the art, and values ​​that can be easily assumed by a person skilled in the art are used.

[0075] In this embodiment, the purification device 13 and the purification device 13a are arranged in parallel, the purification device 23 and the purification device 23a are arranged in parallel, and the purification device 33 is arranged singly, but as long as the object of the present invention can be achieved, the present invention is not limited to these arrangements, and only one purification device may be arranged, or two or more purification devices may be arranged in series or in parallel (or a combination of series and parallel).

[0076] Furthermore, in this embodiment, the fluorine adsorbent according to the present invention is used together with an ion exchange resin in an existing purification facility. However, instead of using an existing purification facility, a dedicated purification device using the fluorine adsorbent according to the present invention may be newly installed. [Example]

[0077] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0078] The reagents and analytical equipment used are as follows. (reagent) Boric acid (Kanto Chemical Co., Ltd., special grade, product number: 04232-00) Sodium fluoride (Fujifilm Wako Pure Chemical Industries, Ltd., Reagent Grade, Part Number: 196-01975) Lithium hydroxide monohydrate (Kanto Chemical Co., Ltd., special grade, product number: 24129-00) (Analyzer) B, Li analysis: ICP emission spectrometer (Thermo Fisher Scientific iCAP7400) F analysis: Ion chromatography system (Thermo Fisher Scientific ICS-1500)

[0079] <1. Preparation of simulated primary cooling water> The primary coolant water was prepared in accordance with the PWR Primary Water Chemistry Control Standard (Handbook of Nuclear Reactor Water Chemistry). The reagents used were boric acid, lithium hydroxide, and sodium fluoride. The quality of the prepared simulated water is shown in Table 1.

[0080] [Table 1]

[0081] <2. Fluorine adsorbent> The following adsorbents were used as adsorbents 1 to 3. (Adsorbent 1) Resin carrying cerium hydroxide particles (READ-F(HG) manufactured by Nihonkaisui Co., Ltd.) Base resin: ethylene-vinyl alcohol copolymer Effective metal compound: cerium hydroxide (particulate) ·Average particle size: 0.6~0.8mm (Adsorbent 2) Zirconium-loaded resin (Muromachi Chemical Co., Ltd., Muromac XSS-5630) Base resin: styrene-divinylbenzene copolymer Effective metal: Zirconium ·Particle size: 0.40~0.90mm (Adsorbent 3) Zirconium-loaded resin (Muromachi Chemical Co., Ltd., Muromac Muromac XSS-530B) Base resin: styrene-divinylbenzene copolymer Effective metal: Zirconium ·Particle size: 0.315~1.25mm

[0082] <3. Evaluation> Adsorbents 1 to 3 were packed into columns (Muromachi Chemical's Muromak Mini Column L), Simulated water flow rate SV10h -1 The simulated water was passed through at a rate of 10 times the amount of resin per hour. After passing 30BV and 50BV of simulated water through the resin, the simulated water (treated water) was sampled and the amount of F contained in the treated water was evaluated by ion chromatography. The analytical results of the treated water are summarized in Table 2.

[0083] [Table 2]

[0084] As shown in Table 2, the F concentration in the treated water was less than 0.05 ppm for both 30BV and 50BV. That is, it was confirmed that by passing simulated primary cooling water through a column packed with adsorbents 1 to 3, fluoride ions can be removed so that the F concentration is significantly below the control value (0.15 ppm or less), satisfying the F concentration of less than 0.05 ppm, even when the B concentration and Li concentration are high (within the control value range in Table 1). [Industrial Applicability]

[0085] This is industrially promising because it makes it possible to satisfy the fluorine concentration control value set in the primary system of a pressurized water nuclear power plant. [Explanation of symbols]

[0086] 1 Primary cooling system equipment 2 nuclear reactor 3 Primary cooling water circulation line 4. Steam generator 5 Secondary cooling water line 6 Primary cooling water extraction line 11 Chemical volume control line 12 Heat exchanger 13,13a Purification equipment 14 Lithium removal device 15 Volume control tank 21 Boric Acid Recovery Line 22 Hold-up tank 23,23a Purification equipment 24 Boric Acid Concentrator 25 Boric Acid Tank 26 Boric acid / pure water injection line 31 Condensate line 32 Heat exchanger 33 Purification equipment 34 Pure water tank P1, P2 pumps

Claims

1. 1. A method for treating primary cooling water of a pressurized water reactor nuclear power plant, comprising: supplying primary cooling water containing boric acid in a primary water purification facility of the pressurized water reactor nuclear power plant to a purification device including a fluorine adsorbent, and adsorbing and removing fluoride ions in the primary cooling water to produce treated water having a reduced fluorine concentration.

2. 2. The method for treating primary cooling water according to claim 1, wherein the fluorine concentration of the treated water discharged from the purification device is 0.15 ppm or less.

3. 2. The method for treating primary cooling water according to claim 1, wherein the concentration of boric acid in the primary cooling water to be treated is 50 ppm or more in terms of boron.

4. 2. The method for treating primary cooling water according to claim 1, wherein the fluorine adsorbent is the following adsorbent (A) and / or adsorbent (B): Adsorbent (A): Adsorbent containing a hydrated rare earth element hydroxide and a binder resin Adsorbent (B): an adsorbent made of a chelating resin or a cation exchange resin to which polyvalent cationic metal ions are immobilized

5. The hydrous rare earth element hydroxide in the adsorbent (A) is cerium (IV) hydroxide n-hydrate (Ce(OH) 4 ・nH 2 5. The method for treating primary cooling water according to claim 4, wherein the primary cooling water is oxidized.

6. 5. The method for treating primary cooling water according to claim 4, wherein the metal element constituting the polyvalent cationic metal ions in the adsorbent (B) is at least one selected from the group consisting of zirconium, aluminum and calcium.

7. 2. The method for treating primary cooling water according to claim 1, wherein the lithium concentration of the primary cooling water to be treated is 0.2 ppm or more and 2.2 ppm or less.

8. 2. The method for treating primary cooling water according to claim 1, wherein the purification device is installed in at least one of a chemical volume control system, a boric acid recovery system, and a spent fuel pit water purification and cooling system in the primary water purification facility.

9. The purification device is an existing purification device using an ion exchange resin in the primary water purification facility, 9. The method for treating primary cooling water according to claim 8, wherein the fluorine adsorbent is mixed with an ion exchange resin of the existing purification device, or is layered on top of or below a resin layer.

10. A purification device for primary cooling water containing boric acid in a primary water purification facility of a pressurized water nuclear power plant, the purification device including a fluorine adsorbent that adsorbs fluoride ions in the primary cooling water.

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