JP2011089942A - Method for controlling water quality in boiling water reactor plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the water quality in a boiling water reactor plant, which is capable of suppressing deposition of nonradioactive materials on the outer surface of a fuel rod without requiring isotope separation. <P>SOLUTION: In the boiling water reactor plant 1, feedwater piping 11 is provided with a hollow fiber filter 8A suppressing the iron oxide concentration included in the feedwater to a level of ≤1×10<SP>-9</SP>mol/kg. A molybdenum acid ion-containing solution injection device 18 having a molybdenum acid ion-containing solution tank 19 in which a molybdenum acid solution is charged is connected to the feedwater piping 11. The molybdenum acid solution is injected into the feedwater, and supplied into a reactor pressure vessel 3 so that a molar concentration ratio of the molybdenum acid ions to cobalt ions in the reactor water in the reactor pressure vessel 3 satisfies 0<Mo/Co<1,200. A tungsten acid solution may be supplied to the reactor pressure vessel 3 so that a molar concentration ratio of the tungstate ions to cobalt ions in the reactor water satisfies 0<W/Co<70. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water quality control method for a boiling water nuclear power plant, and more particularly to a water quality control method for a boiling water nuclear power plant suitable for controlling the water quality of a boiling water nuclear reactor.

  In boiling water reactors, reducing the radiation exposure of workers during periodic inspections is an important issue from the viewpoint of plant health. The radiation source of the radiation exposure of the workers at the time of the regular inspection is mainly radioactive cobalt (for example, cobalt 60) that has adhered to and accumulated on the inner surfaces of the recirculation system piping and the reactor water purification system piping. Cobalt 60 is a plurality of fuels in which non-radioactive cobalt (for example, cobalt 59) contained in the reactor water in the reactor pressure vessel of the boiling water reactor is loaded in the core disposed in the reactor pressure vessel. It is generated by irradiating the attached non-radioactive cobalt with neutrons generated by the fission of nuclear fuel material in the fuel rod attached to the outer surface of multiple fuel rods included in the assembly, that is, the outer surface of the cladding tube. The Therefore, if the adhesion of the cobalt 59 to the outer surface of the cladding tube is suppressed, the production of the cobalt 60 can be suppressed, and the radiation source of the radiation exposure of the worker during the periodic inspection can be reduced.

  Japanese Patent Application Laid-Open Nos. 5-264786 and 6-130191 describe a technique for suppressing the adhesion of cobalt 59 to the outer surface of the cladding tube of the fuel rod. In Japanese Patent Application Laid-Open No. 5-264786, the concentration of iron contained in the feed water supplied into the reactor pressure vessel is suppressed to 0.05 ppb or less to suppress the adhesion of cobalt 59 to the outer surface of the cladding tube. . Furthermore, nitrogen gas, dinitrogen monoxide gas, or carbon dioxide gas is injected into the reactor water to control the pH of the reactor water to be weakly acidic, thereby promoting dissolution of the cobalt oxide 59 adhering to the outer surface of the cladding tube.

  In JP-A-6-130191, the concentration of iron contained in feed water is suppressed to 0.05 ppb or less, and copper, tin, bismuth, cadmium, germanium, selenium, which are metals having a solubility greater than nickel oxide and smaller than sodium oxide. Any of mercury, arsenic, gallium, chromium, manganese, zinc, antimony, vanadium and tellurium is injected into the reactor water in the reactor pressure vessel. By injecting this substance, dissolution of cobalt oxide 59 adhering to the outer surface of the cladding tube is promoted.

Japanese Laid-Open Patent Publication No. 7-84090 proposes a method for suppressing the incorporation of radioactive ions into a corrosion film in accordance with the corrosion of the surface of a nuclear plant component that comes into contact with the reactor water. In this method, the isotopes of the elements used for injection into the reactor pressure vessel are adjusted (excluding ⁹⁸ Mo for molybdenum and ¹⁸⁴ W and ¹⁸⁶ W for tungsten), which are the reactor pressures. Metal ions that do not generate secondary radioactivity when injected into the container are implanted. As the metal ions, molybdenum or tungsten metal acid ions, that is, molybdate ions or tungstate ions are used.

  H. Tsuge et al., “Prevention of Intergranular and Transgranular Stress Corrosion Cracking of type 304 Stainless Steel in High Temperature Water Environments”, 1988 JAIF International Conference on Water Chemistry in Nuclear Power Plants, 19-22 Apr., 1988, Tokyo, Japan, Vol.2, p.728 (1988) describes that injection of molybdic acid or tungstic acid suppresses stress corrosion cracking of plant components.

Japanese Patent Laid-Open No. 5-264786 JP-A-6-130191 Japanese Patent Laid-Open No. 7-84090

H. Tsuge et al., “Prevention of Intergranular and Transgranular Stress Corrosion Cracking of type 304 Stainless Steel in High Temperature Water Environments”, 1988 JAIF International Conference on Water Chemistry in Nuclear Power Plants, 19-22 Apr., 1988, Tokyo, Japan, Vol.2, p.728 (1988)

  As described in JP-A-5-264786 and JP-A-6-130191, the concentration of iron contained in the feed water supplied to the reactor pressure vessel is suppressed to 0.05 ppb or less, thereby providing a coating. The amount of non-radioactive cobalt adhering to the outer surface of the tube can be reduced, and the amount of radioactive cobalt produced is reduced. For this reason, the surface dose rate of the recirculation system piping and the reactor water purification system piping is reduced, and the exposure amount of workers during the periodic inspection is reduced.

However, it is desired to further reduce the exposure of workers. For this reason, the technology described in JP-A-5-264786 and JP-A-6-130191 described in JP-A-7-84090 is a technique for suppressing the concentration of iron contained in water supply to 0.05 ppb or less. By combining the injection of molybdate ions not containing ⁹⁸ Mo (or tungstate ions not containing ¹⁸⁴ W and ¹⁸⁶ W), the surface dose rate of the piping of the nuclear power plant can be reduced. The application of the technique for reducing the surface dose rate of piping described in Japanese Patent Application Laid-Open No. 7-84090 is an isotope element that generates secondary radioactivity from natural molybdenum or tungsten ( ⁹⁸ Mo, or ¹⁸⁴ W and ¹⁸⁶ W) must be removed. In the techniques described in Japanese Patent Laid-Open Nos. 5-264786 and 6-130191, it is necessary to separate molybdenum or tungsten isotopes.

  An object of the present invention is to provide a water quality control method for a boiling water nuclear plant that does not require isotope separation and can suppress adhesion of non-radioactive materials to the outer surface of a fuel rod.

The feature of the present invention that achieves the above-described object is that a boiling water nuclear plant provided with equipment for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less. In the water quality control method, the ratio of reactor water molybdate ion molar concentration MoC to reactor water cobalt ion molar concentration CoC in the reactor pressure vessel is such that the MoC / CoC satisfies 0 <MoC / CoC <1200. The purpose is to implant molybdate ions.

  Since molybdate ions are injected into the reactor water so that the ratio MoC / CoC satisfies 0 <MoC / CoC <1200, adhesion of non-radioactive cobalt to the outer surface of the cladding of the fuel rod in the core is suppressed, and the core The production amount of radioactive cobalt is reduced. Thereby, a worker's radiation exposure can be suppressed. Further, even if the molybdate ions to be implanted contain isotopes of molybdenum that generate secondary radioactivity, adhesion of non-radioactive cobalt to the outer surface of the cladding tube is suppressed. This eliminates the need for molybdenum isotope separation.

In a water quality control method for a boiling water nuclear power plant equipped with a facility for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less, By injecting tungstate ions into the reactor water so that the ratio WC / CoC of the tungstate ion molar concentration WC of the reactor water to the cobalt ion molar concentration CoC of the reactor water satisfies 0 <WC / CoC <70. Can achieve the goal.

  Since tungstate ions are injected into the reactor water so that the ratio WC / CoC satisfies 0 <WC / CoC <70, adhesion of non-radioactive cobalt to the outer surface of the cladding of the fuel rod in the core is suppressed, and the core The production amount of radioactive cobalt is reduced. Thereby, a worker's radiation exposure can be suppressed. Moreover, even if the tungstate ion to be injected contains an isotope that generates secondary radioactivity of tungsten, adhesion of non-radioactive cobalt to the outer surface of the cladding tube is suppressed. For this reason, it is not necessary to perform tungsten isotope separation.

In a water quality control method for a boiling water nuclear power plant equipped with a facility for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less, It is also possible to inject molybdate ions into the reactor water and adjust the concentration of molybdate ions contained in the reactor water within the range of 1 × 10 ⁻⁸ mol / kg to 1 × 10 ⁻⁶ mol / kg. Can achieve the goal.

By injecting molybdate ions into the reactor water, the concentration of molybdate ions contained in the reactor water is adjusted within the range of 1 × 10 ⁻⁸ mol / kg or more and 1 × 10 ⁻⁶ mol / kg or less. The production amount of is reduced. Thereby, radiation exposure of workers can be suppressed, and it is not necessary to perform isotope separation of molybdenum.

In the water quality control method for a boiling water nuclear power plant having a suppressing equipment iron oxide concentration in the feed water supplied to the reactor pressure vessel below 1 × 10 -9 ^{mol /} kg, the reactor pressure vessel By injecting tungstate ions into the reactor water and adjusting the tungstate ion concentration contained in the reactor water within the range of 1 × 10 ⁻⁸ mol / kg to 1 × 10 ⁻⁷ mol / kg, Can achieve the goal.

Since the tungstate ion concentration in the reactor water is adjusted within the range of 1 × 10 ⁻⁸ mol / kg to 1 × 10 ⁻⁷ mol / kg by injecting the tungstate ions into the reactor water, radioactive cobalt The production amount of is reduced. Thereby, radiation exposure of workers can be suppressed, and it is not necessary to perform tungsten isotope separation.

  According to the present invention, it is not necessary to perform isotope separation, and adhesion of non-radioactive substances to the outer surface of the fuel rod can be suppressed. For this reason, since the production amount of a radionuclide can be reduced, the radiation exposure of an operator can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the boiling water nuclear plant to which the water quality control method of the boiling water nuclear plant of Example 1 which is one suitable Example of this invention is applied. It is explanatory drawing which shows the experimental result which confirmed the adhesion amount of the cobalt ion to the surface of a zirconium alloy. It is a characteristic view which shows the relationship between the molar ratio of the molybdate ion with respect to a cobalt ion, a cobalt deposition rate, and a molybdate ion deposition rate. It is a characteristic view which shows the relationship between the molar ratio of molybdate ion (or tungstate ion) to cobalt ion and the exposure dose rate relative value. It is a characteristic view which shows the relationship between a molybdate ion concentration and a cobalt adhesion rate. It is a block diagram of the other Example of the molybdate ion containing solution injection apparatus shown in FIG. It is a block diagram of the boiling water nuclear plant to which the water quality control method of the boiling water nuclear plant of Example 2 which is another Example of this invention is applied. It is a block diagram of the boiling water nuclear plant to which the water quality control method of the boiling water nuclear plant of Example 3 which is another Example of this invention is applied. It is a block diagram of the boiling water nuclear plant to which the water quality control method of the boiling water nuclear plant of Example 4 which is another Example of this invention is applied. It is a block diagram of the boiling water nuclear plant to which the water quality control method of the boiling water nuclear plant of Example 5 which is another Example of this invention is applied.

  The inventors have studied a method that can suppress the adhesion of non-radioactive material to the outer surface of the fuel rod without the need to perform isotope separation of the material injected into the reactor pressure vessel.

First, the substances injected into the reactor pressure vessel were examined. The inventors conducted an experiment for confirming how the amount of cobalt ions adhering to the surface of the zirconium alloy is affected by the substance to be injected. The contents of this experiment will be described below. The heater pin coated with the zirconium alloy was immersed in high-temperature and high-pressure water at 286 ° C. and 7 MPa, the heater pin was heated, and high-temperature and high-pressure water was boiled on the liquid contact surface of the heater pin. The experiment was conducted in four cases: cobalt ions, molybdate ions, tungstate ions, and borate ions, each added to high-temperature high-pressure water alone, and cases where no substances other than cobalt ions were added to high-temperature high-pressure water. Went about. The high-temperature high-pressure water has an iron oxide concentration of 0 in order to simulate reactor water to which feed water having an iron oxide concentration of 1 × 10 ⁻⁹ mol / kg or less is supplied.

  FIG. 2 shows the results of these experiments. According to these experimental results, in high-temperature and high-pressure water to which molybdate or tungstate ions were added, the amount of cobalt adhered to the zirconium alloy surface covering the heater pin was reduced to 1/7 compared to the case where only cobalt ions were added. It turns out that it falls. In high-temperature and high-pressure water to which borate ions were added, the amount of cobalt adhering to the surface of the zirconium alloy became comparable to that in the case of using high-temperature and high-pressure water to which only cobalt ions were added. Based on the experimental results described above, the inventors injected a molybdate ion or a tungstate ion into the reactor water, thereby coating the fuel rod contained in the fuel assembly loaded in the core with a zirconium alloy. It was newly found that the amount of non-radioactive cobalt adhering to the outer surface of the tube can be suppressed. Molybdate and tungstate ions are also reported in H. Tsuge et al., “Prevention of Intergranular and Transgranular Stress Corrosion Cracking of type 304 Stainless Steel in High Temperature Water Environments”, 1988 JAIF International Conference on Water Chemistry in Nuclear Power Plants, 19 -22 Apr., 1988, Tokyo, Japan, Vol.2, p.728 (1988), suppresses stress corrosion cracking of components. Therefore, stress corrosion cracking of plant components can be suppressed by injecting molybdate or tungstate ions into the reactor water.

  Next, the inventors examined the respective concentrations of molybdate and tungstate ions injected into the reactor water. The contents of the experiment conducted by the inventors using molybdic acid will be described. FIG. 3 shows experimental results showing changes in the deposition rate of cobalt and the deposition rate of molybdate ions on a zirconium alloy with respect to the ratio of the molar concentration of molybdate ions to the molar concentration of cobalt ions in water. This experimental result could be obtained by the following experiment. The heater pin coated with the zirconium alloy was immersed in high-temperature and high-pressure water at 286 ° C. and 7 MPa, the heater pin was heated, and high-temperature and high-pressure water was boiled on the liquid contact surface of the heater pin. This high-temperature and high-pressure water contains dissolved cobalt ions and molybdate ions. In this experiment, the ratio of the molar concentration of molybdate ions to the molar concentration of cobalt ions in high-temperature and high-pressure water was changed to determine the respective deposition rates of cobalt and molybdate ions on the surface of the zirconium alloy covering the heater pin. confirmed. The experimental results are shown in FIG.

  In FIG. 3, black circles indicate the cobalt deposition rate, and white circles indicate the molybdenum deposition rate. FIG. 3 shows that the deposition rate of cobalt on the surface of the zirconium alloy decreases when the ratio MoC / CoC of the molar concentration MoC of molybdate ions to the molar concentration CoC of cobalt ions in water is greater than zero. . This is because the adhesion of cobalt is suppressed by the addition of molybdate ions. In particular, when the ratio MoC / CoC of the molar concentration of molybdate ions to the molar concentration of cobalt ions is 1 or more, the deposition rate of cobalt on the surface of the zirconium alloy is significantly reduced. Also, the molybdate ion deposition rate on the surface of the zirconium alloy increases as the ratio MoC / CoC of the molar concentration of molybdate ions to the molar concentration of cobalt ions in water becomes larger than 0, and the ratio MoC / When the CoC is larger than 30, it significantly increases.

  Further, the inventors adhere to the outer surface of the zirconium alloy cladding tube of the fuel rod included in the fuel assembly loaded in the core based on the cobalt deposition rate and the molybdate deposition rate shown in FIG. The relative effects of the radioactivity generated from each of the cobalt and molybdate ions on the exposure dose rate were evaluated. The evaluation results are shown in FIG. In this evaluation, the amount of radioactive material generated is determined based on the activation cross sections of each element (cobalt and molybdenum), and the radiation dose is relatively evaluated based on the energy of gamma rays emitted from the generated radioactive material. Went by. The ratio of the molar concentration of molybdate ions to the concentration of cobalt ions The relative value of the exposure dose rate in the region where the MoC / CoC is large, the cobalt deposition rate is constant, and the deposition rate of molybdate ions is the latest two-point data. Assuming that it is proportional to

  The reason why the cobalt deposition rate becomes constant is as follows. If it is considered that the reaction between cobalt ions and molybdate ions affects the deposition rate, when molybdate ions having a predetermined concentration or more are present, excess molybdate ions do not contribute to the reaction. For this reason, the cobalt deposition rate becomes constant when the molybdate ion concentration is a predetermined amount or more. The experimental results also showed that the cobalt deposition rate tends to be constant in the region where the molybdate ion concentration is high.

  The reason why the molybdate ion deposition rate is proportional to the most recent two-point data is as follows. As the concentration of molybdate ions increases, the concentration of cobalt ions decreases relatively, making it less susceptible to cobalt ions. Therefore, it is considered that the molybdenum deposition rate increases as the molybdate ion concentration increases. The experimental results also showed a tendency for the molybdenum deposition rate to increase with increasing molybdate ion concentration. Therefore, it was determined that the deposition rate of molybdate ions is linearly proportional to the molybdenum concentration.

  For the tungstate ion, it was assumed that the same molar amount of tungsten as the molybdate ion was deposited on the outer surface of the cladding tube. This is because the attachment of molybdate ions and tungstate ions on the surface of the zirconium alloy is caused by a chemical reaction, and the amount of each attachment depends on the number of moles. Molybdenum and tungsten are included in the same group in the periodic table and have similar chemical properties. Therefore, molybdic acid and tungstic acid have similar chemical properties. Since adhesion to the cladding tube made of a zirconium alloy is caused by a chemical reaction (morphological change from ion to oxide), molybdate ions adhere to the cladding tube in the same manner as molybdate ions. For this reason, the deposition rate of tungstate ions on the cladding tube is substantially the same as the deposition rate of molybdate ions on the cladding tube.

In a boiling water nuclear power plant equipped with a facility that suppresses the concentration of iron oxide contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, the addition of molybdate ions suppresses the cobalt deposition rate, while cobalt ions The ratio of the molar concentration of molybdate to the molar concentration of molybdate increases with the increase in MoC / CoC, so that the relative value of the exposure dose rate is calculated as follows. The ratio of the molar concentration of molybdate ions to the concentration, MoC / CoC, changes so as to protrude downward. The relative value of the exposure dose rate is the same as when the molybdate ions are not implanted when the ratio MoC / CoC of the molar concentration MoC of molybdate ions to the molar concentration CoC of cobalt ions is 1200. Therefore, in a boiling water nuclear power plant equipped with a facility that suppresses the concentration of iron oxides contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, the molybdate ions added to the reactor water are secondary molybdenum ions. Molybdate ions containing isotopes that do not generate specific radioactivity (eg, ⁹² Mo, ⁹⁴ Mo, etc.) and molybdenum containing isotopes that generate secondary radioactivity (eg, ⁹⁸ Mo, etc.) Even in the case where acid ions are included, the ratio of the molar concentration of molybdate ions to the molar concentration of cobalt ions in the reactor water is such that the MoC / CoC satisfies 0 <MoC / CoC <1200. The inventors have newly found that the addition of acid ions can reduce the exposure of workers during periodic inspections of nuclear power plants. Preferably, the ratio of the molar concentration of molybdate ions to the molar concentration of cobalt ions is such that the MoC / CoC satisfies the following condition: 1 ≦ MoC / CoC ≦ 600. Can be further reduced.

As equipment for suppressing the concentration of iron oxide contained in the water supply to 1 × 10 ⁻⁹ mol / kg or less, there are a hollow filter and an electrodialyzer.

Even when tungstate ions are added to the above high-temperature and high-pressure water instead of molybdate ions, the cobalt deposition rate is suppressed by the addition of tungstate ions. That is, in a boiling water nuclear power plant equipped with a facility that suppresses the concentration of iron oxide contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, the molar concentration WC of tungstate ions relative to the molar concentration CoC of cobalt ions Since the attachment rate of tungstate ions increases as the ratio WC / CoC increases, as shown in FIG. 4, the relative value of the exposure dose rate is the ratio of the molar concentration of tungstate ions to the molar concentration of cobalt ions WC / It changes so as to be convex downward with respect to CoC. The relative value of the exposure dose rate is equivalent to the case where the tungstate ion is not implanted when the ratio WC / CoC of the molar concentration of tungstate ion to the molar concentration of cobalt ion is 70. Therefore, in a boiling water nuclear power plant equipped with a facility that suppresses the concentration of iron oxide contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, the tungstate ion added to the reactor water is secondary tungsten. Tungsten ion containing an isotope that does not generate a specific radioactivity (for example, ¹⁸⁰ W, ¹⁸² W, etc.) and an isotope that generates a secondary radioactivity of tungsten (for example, ¹⁸⁴ W, ¹⁸⁶ W, etc.) The ratio of the molar concentration of tungstate ions to the molar concentration of cobalt ions in the reactor water is such that WC / CoC satisfies 0 <WC / CoC <70. By adding tungstate ions to water, it was found that the exposure of workers during periodic inspections of nuclear power plants can be reduced. Shah et al. Newly found. Preferably, the exposure of workers by adding tungstate ions to the reactor water so that the ratio WC / CoC of the molar concentration of tungstate ions to the molar concentration of cobalt ions satisfies 1 ≦ WC / CoC ≦ 50. Can be further reduced.

Based on the experimental results shown in FIG. 3, the inventors of the present invention in a boiling water nuclear power plant equipped with facilities for suppressing the concentration of iron oxide contained in feed water to 1 × 10 ⁻⁹ mol / kg or less. The effect of the molar concentration of molybdate ions on the deposition rate was evaluated. The result is shown in FIG. From FIG. 5, in a boiling water nuclear power plant equipped with equipment for suppressing the concentration of iron oxide contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, molybdate ions added to the reactor water are Molybdate ions containing isotopes that do not generate secondary radioactivity (eg, ⁹² Mo, ⁹⁴ Mo, etc.), and molybdenum isotopes (eg, ⁹⁸ Mo, etc.) that generate secondary radioactivity Even in the case of containing molybdate ions, a solution containing molybdate ions is injected into the reactor water, and the molar concentration of molybdate ions contained in the reactor water is 1 × 10 ⁻⁸ mol / kg or more 1 by adjusting the × 10 -6 ^{mol /} kg within the following ranges, cobalt deposition rate to the cladding outer surface of the fuel rods to be smaller than without the addition of molybdate ions, Inventor et al newly found.

In a boiling water nuclear power plant equipped with a facility that suppresses the concentration of iron oxides contained in feed water to 1 × 10 ⁻⁹ mol / kg or less, the tungstate ion added to the reactor water is tungsten secondary. Includes tungstate ions containing isotopes that do not generate radioactivity (eg, ¹⁸⁰ W, ¹⁸² W, etc.) and isotopes that produce secondary radioactivity of tungsten (eg, ¹⁸⁴ W, ¹⁸⁶ W, etc.) Even when tungstate ions are contained, a solution containing tungstate ions is injected into the reactor water, and the molar concentration of tungstate ions contained in the reactor water is 1 × 10 ⁻⁸ mol / kg or more and 1 × 10 6. by adjusting within a range of less than ^{-7 mol} / kg, cobalt deposition rate to the cladding outer surface of the fuel rods than without addition of molybdate ions To be a fence, we have newly found.

  In the injection of molybdate ions or tungstate ions into the reactor water, it is desirable to further inject hydrogen into the reactor water. By injecting hydrogen, the concentration of oxygen and hydrogen peroxide in the reactor water is reduced, so that corrosion of components in contact with the reactor water of a boiling water nuclear power plant can be suppressed, and non-radioactive cobalt (for example, cobalt 59) can be reduced.

  Further, in addition to molybdate ions or tungstate ions, it is desirable to inject zinc ions into the reactor water. By injecting zinc ions, it is possible to suppress corrosion of components that come into contact with the reactor water of the boiling water nuclear power plant, and to reduce the supply of non-radioactive cobalt (for example, cobalt 59). For the implantation of zinc ions, for example, it is desirable to use a solution containing zinc ions separately from either molybdate ions or tungstate ions.

Molybdate or tungstate ions are injected into the reactor water with equipment that suppresses the iron oxide concentration in the feed water to 1 × 10 ⁻⁹ mol / kg or less and a solution containing molybdate or tungstate ions. It is necessary to carry out in a boiling water nuclear power plant equipped with the equipment to do.

  Embodiments of the present invention will be described below in consideration of the knowledge newly found by the inventors.

  A water quality control method for a boiling water nuclear power plant, which is a preferred embodiment of the present invention, will be described with reference to FIG. First, a boiling water nuclear plant to which this embodiment is applied will be described with reference to FIG. A boiling water nuclear power plant 1 includes a reactor 2, a main steam pipe 5, a turbine 6, a condenser 7, a hollow filter 8A, a feed water pipe 11, a reactor purification system 13, and a molybdate ion-containing solution injector (molybdic acid). An ion implantation device) 18 is provided.

  The nuclear reactor 2 includes a nuclear reactor pressure vessel 3 and a core 4. A core 4 loaded with a plurality of fuel assemblies (not shown) is disposed in the reactor pressure vessel 3. Each fuel assembly has a plurality of fuel rods. The fuel rod contains a nuclear fuel material, which is filled with the nuclear fuel material and sealed, and has a cladding tube made of a zirconium alloy.

  A main steam pipe 5 connected to the reactor pressure vessel 3 is connected to a turbine 6. A water supply pipe 11 is connected to the condenser 7 and the reactor pressure vessel 3. A hollow filter 8 </ b> A, a desalter 8 </ b> B, a feed water pump 9, and a feed water heater 10 are installed in the feed water pipe 11. The extraction pipe 12 connected to the main steam pipe 5 is connected to the feed water heater 10. The hollow filter 8A is disposed upstream of the desalter 8B. An electrodialyzer may be used instead of the hollow filter 8A.

  The reactor purification system 13 includes a purification system pipe 14, a purification system pump 15, and a desalter (purification device) 17. The purification system pipe 14 has one end connected to the reactor pressure vessel 3 and the other end connected to the water supply pipe 11. A purification system pump 15, a heat exchanger 16, and a desalter 17 are provided in the purification system pipe 14.

  The molybdate ion-containing solution injection device 18 includes a molybdate ion-containing solution tank 19, a pump 20, and an injection pipe 21. An injection pipe 21 provided with a pump 20 and an on-off valve 22 is connected to a molybdate ion-containing solution tank 19 and a water supply pipe 11 filled with a molybdate ion-containing solution. An injection pipe 21 is connected to the water supply pipe 11 between the desalter 8 </ b> B and the water supply pump 9. The hydrogen injection device 23 is connected to the water supply pipe 11 between the connection point of the injection pipe 21 and the water supply pipe 11 and the demineralizer 8B by the injection pipe 24 provided with the on-off valve 25.

  The sampling pipe 26 is connected to the water supply pipe 11 between the connection point between the injection pipe 24 and the water supply pipe 11 and the demineralizer 8B. A sampling pipe 27 is connected to the purification system pipe 14 between the heat exchanger 16 and the desalter 17 upstream of the desalter 17.

  During operation of the boiling water nuclear power plant 1, an internal pump (not shown) provided at the bottom of the reactor pressure vessel 3 (or a recirculation pump for the recirculation system provided in the reactor pressure vessel) is driven. Then, the cooling water (reactor water) in the reactor pressure vessel 3 is supplied to the reactor core 4. While the reactor water rises in the fuel assembly in the core 4, it is heated by the heat generated by the nuclear fission of the nuclear fuel material in the fuel rods, and a part of the reactor water becomes steam. A steam separator (not shown) and a steam dryer (not shown) are installed in the reactor pressure vessel 3 above the core 4. A gas-liquid two-phase flow including steam and reactor water is guided from the core 4 to the steam-water separator, and the steam is separated from the reactor water in the steam-water separator. The steam separated by the steam separator is guided to a steam dryer to further remove moisture.

The steam from which the moisture has been removed is discharged from the reactor pressure vessel 3 to the main steam pipe 5 and guided to the turbine 6. The turbine 6 is rotated by steam, and a generator (not shown) connected to the turbine 6 is also rotated. Electricity is generated by the rotation of the generator. The steam exhausted from the turbine 6 to the condenser 7 is condensed in the condenser 7 to become water. This water is supplied to the reactor pressure vessel 3 through the water supply pipe 11 as water supply. While the feed water flows through the feed water pipe 11, the feed water is purified by the hollow filter 8 </ b> A, pressurized by the feed water pump 20, and heated by the feed water heater 10. The hollow filter 8A removes solid content such as iron oxide contained in the water supply. Since iron oxide is removed by Nakazorako filter 8A, it is possible to suppress the iron oxide concentration in the feed water supplied to the reactor pressure vessel 3 below 1 × 10 -9 ^{mol /} kg. The desalinator 8B is filled with an ion exchange resin, and seawater components (sodium ions and chlorides) contained in the water supply when seawater used for condensing steam in the condenser 7 leaks into the condenser 7. Ions, etc.) are removed. For this reason, seawater components can be prevented from flowing into the reactor pressure vessel 3 through the water supply pipe 11.

  The reactor water in the reactor pressure vessel 3 flows into the purification system pipe 14, is pressurized by the purification system pump 15, is cooled by the heat exchanger 16, and is purified by the desalter 17. The purified reactor water is heated by the heat exchanger 16 and then returned to the reactor pressure vessel 3 through the purification system pipe 14 and the feed water pipe 11.

  A part of the reactor water flowing in the purification system pipe 14 is sampled by the sampling pipe 27, and the sampled reactor water is analyzed by chromatography or the like. Thereby, each density | concentration of substances, such as cobalt ion and molybdate ion contained in this reactor water, is measured. A part of the feed water flowing in the feed water pipe 11 is sampled by the sampling pipe 26, and the sampled feed water is analyzed by chromatography or the like. Thereby, the density | concentration, such as an iron oxide contained in this water supply, is measured. A flow meter 29 provided in the purification system pipe 14 measures the flow rate of the reactor water flowing through the purification system pipe 14.

During operation of the boiling water nuclear power plant 1, the molybdate ion-containing solution is injected into the water supply pipe 11 from the molybdate ion-containing solution injection device 18. In this example, a molybdate (H ₂ MoO ₄ ) solution is used as the molybdate ion-containing solution. The molybdate solution used in this example includes, for example, 0.1 mol / kg of molybdate ions. The molybdic acid solution is a secondary emission of molybdenum, such as ⁹² Mo, ⁹⁴ Mo, ⁹⁵ Mo and ⁹⁶ Mo, which are isotopes of molybdenum that do not generate secondary radioactivity, and molybdenum. Each of the molybdate ions of ⁹⁸ Mo, which is an isotope that generates a function, is included. Sodium molybdate (Na ₂ MoO ₄ ) solution, potassium molybdate (K ₂ MoO ₄ ) solution, and lithium molybdate (Li ₂ MoO ₄ ) that are molybdate ions-containing solutions other than molybdate (H ₂ MoO ₄ ) solutions Any of the solutions may be used. These molybdate ions-containing solutions also contain molybdate ions of molybdenum that does not generate secondary radioactivity and molybdenum that generates secondary radioactivity.

The injection of the molybdate solution by the molybdate ion-containing solution injector 18 will be described in detail. The measured concentrations of cobalt ions and molybdate ions are input to the controller 28 from an input device (not shown) by an operator. The control device 28 also inputs the flow rate of the reactor water flowing through the purification system pipe 14 measured by the flow meter 29. The control device 28 determines the measured flow rate F _RWCU (t / h) of the reactor water flowing in the purification system pipe 14 and the set concentration C _{RW, Mo} ^set (mol / kg) of molybdate ions contained in the reactor water. Substituting into the equation (1), the injection flow rate F _tank ^Mo (t / h) of the molybdate ion-containing solution (for example, molybdate solution) is obtained.

However, C _{RW, Mo} ^meas is the measured concentration of molybdate ions (mol / kg) in the reactor water, and C _tank ^Mo is included in the molybdate ion-containing solution filled in the molybdate ion-containing solution storage tank 18. The molybdate ion concentration (mol / kg) and f _Mo are factors.

In calculating the injection flow rate F _tank ^Mo (t / h) of the molybdate ion-containing solution based on the equation (1), the factor f _Mo is initially assumed to be 1. Molybdate ion concentration C _tank ^Mo (mol / kg) contained in molybdate (H ₂ MoO ₄ ) solution filled in molybdate ion-containing solution storage tank 19 and set concentration C _RW of molybdate ions in the reactor water _{, Mo} ^set (mol / kg) is also input to the controller 28 by the operator. The set concentration C _{RW, Mo} ^set of molybdate ions is set by the operator so as to be included in the above-described range of 1 × 10 ⁻⁸ mol / kg to 1 × 10 ⁻⁶ mol / kg. For example, 3 × 10 ⁻⁷ mol / kg is set in the control device 28 as the set concentration C _{RW, Mo} ^{set of} molybdate ions. 0.1 mol / kg which is the concentration C _tank ^Mo of molybdate ions is input to the controller 28. The flow rate F _{RWCU of the} reactor water flowing through the purification system pipe 14 measured by the flow meter 29, for example, 128 t / h is input to the control device 28.

The control device 28 has a factor f _Mo of 1, a molybdate ion set concentration C _{RW, Mo} ^set of 3 × 10 ⁻⁷ mol / kg, and a reactor water flow rate F _RWCU of 128 t / h, and by substituting 0.1 mol / kg is the concentration C _tank ^Mo molybdate ions, to calculate the infusion rate F _tank ^Mo molybdate solution. The determined flow rate F _tank ^Mo of the molybdic acid solution is 3.84 × 10 ⁻⁴ t / h.

The control device 28 opens the on-off valve 22 to drive the pump 20, and the molybdic acid solution injection flow rate F _tank ^Mo (t / h) calculated by the equation (1), that is, 3.84 × 10 ⁻⁴ t / h. The rotational speed of the pump 20 is controlled so as to be h. The molybdate solution in the molybdate ion-containing solution storage tank 19 is supplied into the water supply pipe 11 at 3.84 × 10 ⁻⁴ t / h. In this way, molybdate ions are injected into the feed water, guided into the reactor pressure vessel 3 together with the feed water, and injected into the reactor water in the reactor pressure vessel 3. The measured cobalt ions are monitored by analyzing the reactor water sampled by the sampling pipe 27.

The control device 28 determines whether the molybdate ion concentration measured by analyzing the reactor water sampled by the sampling pipe 27 after the injection of the molybdate solution is the set concentration C _{RW, Mo} ^set of molybdate ions. . If the molybdate ion concentration is the set concentration C _{RW, Mo} ^set of molybdate ions, the controller 28 continues to inject the molybdate solution at 3.84 × 10 ⁻⁴ t / h.

If the controller 28 determines that the measured molybdate ion concentration C _{RW, Mo} ^meas (mol / kg) is not the set molybdate ion concentration C _{RW, Mo} ^set , this measurement is performed. The factor f _Mo is calculated by substituting the molybdate ion concentration C _{RW, Mo} ^meas and the molybdate ion set concentration C _{RW, Mo} ^set into the equation (2). It is assumed that the molybdate ion concentration C _{RW, Mo} ^meas measured by analysis of the reactor water sampled by the sampling pipe 27 is, for example, 2.5 × 10 ⁻⁷ mol / kg. The molybdate ion concentration C _{RW, Mo} ^meas is not ^set to 3 × 10 ⁻⁷ mol / kg which is the set concentration C _{RW, Mo} ^set , and is input to the controller 28. The control device 28 substitutes these values into the equation (2), and calculates 1.2 as the factor f _Mo.

The control device 28 assigns the calculated factor f _Mo of 1.2 to the equation (1), and the molybdic acid solution injection flow rate F _tank ^Mo (t / h) is 4.61 × 10 ⁻⁴ t / h. h is newly calculated. The control device 28 controls the rotational speed of the pump 20 based on the newly obtained molybdic acid solution injection flow rate F _tank ^Mo (t / h). As a result, the molybdic acid solution is supplied from the molybdate ion-containing solution storage tank 19 to the water supply pipe 11 at the newly obtained 4.61 × 10 ⁻⁴ t / h. That is, a necessary amount of molybdate ions is injected into the water supply pipe 11. By controlling the injection of the molybdate solution by the controller 28, the concentration of molybdate ions contained in the reactor water is adjusted to the set concentration C _{RW, Mo} ^{set of} molybdate ions, that is, 3 × 10 ⁻⁷ mol / kg.

  During the operation of the boiling water nuclear power plant 1, the on-off valve 25 is opened, and hydrogen is injected from the hydrogen injector 23 into the feed water pipe 11 through the injection pipe 24. This hydrogen is also supplied into the reactor pressure vessel 3 together with the feed water and injected into the reactor water. Hydrogen reacts with oxygen contained in the reactor water to become water. For this reason, the oxygen concentration and hydrogen peroxide concentration contained in the reactor water are reduced.

In this embodiment, the concentration of molybdate ions contained in the reactor water in the reactor pressure vessel 3 is 3 × 10 ⁻⁷ mol / kg, and each fuel rod of each fuel assembly loaded in the reactor core Adhesion of non-radioactive cobalt (for example, cobalt 59) to the outer surface of the zirconium alloy cladding tube is suppressed, and the amount of radioactive cobalt produced is reduced. For this reason, the cobalt radioactivity density | concentration in a reactor water falls to 1/3 of the past by application of the molybdate ion implantation of a present Example. The surface dose rate of the reactor pressure vessel 3 and the piping through which the reactor water in the reactor pressure vessel 3 such as the purification system piping 14 flows is reduced, and the exposure of workers in the periodic inspection of the boiling water nuclear power plant 1 can be reduced. . By the way, when the operation of applying the molybdate ion implantation of this embodiment is started in a state where the pipe dose rate is 0 in the newly installed boiling water nuclear power plant and the existing boiling water nuclear power plant that has been chemically decontaminated. The exposure dose rate after the end of the first operation cycle (for example, 10000 hours) is 1/3 ((pipe dose rate when this embodiment is applied) = (piping when this embodiment is not applied) (Dose rate) x (1/3)). In addition, after the equilibration cycle of the boiling water nuclear power plant 1, for example, after the boiling water nuclear power plant 1 has experienced about five operation cycles, the boiling water nuclear power plant 1 is subjected to the molybdate ion implantation of this embodiment. When applied, the pipe dose rate at the end of the first operation cycle after application of the present embodiment is 4/5 ((pipe dose rate when this embodiment is applied) = (when this embodiment is not applied). Pipe dose rate)) × (4/5)), and after 10 operating cycles, the pipe dose rate is 1/2 ((pipe dose rate when this embodiment is applied) = (this embodiment is not applied) In case of pipe dose rate) x (1/2)).

In this embodiment, the molybdate ions injected into the reactor water are the isotopes of molybdenum, isotopes that do not generate secondary radioactivity, such as ⁹² Mo, ⁹⁴ Mo, ⁹⁵ Mo and ⁹⁶ Mo, and molybdenum. It contains each molybdate ion of ⁹⁸ Mo which is an isotope that generates the next radioactivity. For this reason, in this embodiment, there is no need to remove the isotope of molybdenum that generates secondary radioactivity by performing molybdenum isotope separation as in JP-A-7-84090. Even when molybdate ions including molybdenum (for example, ⁹⁸ Mo) generating secondary radioactivity exist as molybdate ions to be injected, the concentration of molybdate ions contained in the reactor water is 3 × 10 ^−7. Since it is mol / kg, the exposure of workers can be reduced.

  In JP-A-5-264786, nitrogen gas, dinitrogen monoxide gas or carbon dioxide gas is injected into the reactor water in order to make the pH of the reactor water weakly acidic. Nitric acid and carbon dioxide, which can arise from nitrous oxide gas, can increase the susceptibility to stress corrosion cracking of reactor internals in the reactor pressure vessel. On the other hand, since a molybdate ion which suppresses the stress corrosion cracking of the component member is injected into the reactor water in the present embodiment, the stress corrosion cracking of the component member contacting the reactor water can be suppressed.

  In Japanese Patent Laid-Open No. 6-130191, copper is injected to promote dissolution of cobalt oxide 59 attached to the outer surface of the cladding tube. This copper can promote corrosion of the cladding. In this embodiment, molybdate ions are implanted, so that problems caused by the implantation of copper can be solved.

  Instead of connecting the injection pipe 21 of the molybdate ion-containing solution injection apparatus 18 to the water supply pipe 11, the injection pipe 21 may be connected to the purification system pipe 14 downstream of the desalter 17. Accordingly, molybdate ions can be injected into the reactor pressure vessel 3 through the purification system pipe 14 even during a period in which feed water cannot be supplied to the reactor pressure vessel 3 through the feed water pipe 11. The period in which feed water is not supplied to the reactor pressure vessel 3 is a period from the start of the reactor to immediately before the start of water supply to the reactor in the process of increasing the reactor power. By injecting molybdate ions into the purification system pipe 14, the cobalt radioactivity concentration in the reactor water can be reduced from the time when the boiling water nuclear power plant is started. Connecting the molybdate ion-containing solution injection device 18 to the purification system pipe 14 instead of the water supply pipe 11 may be applied to Examples 3 and 5 described later.

  In the present embodiment, the injection flow rate of the molybdate ion-containing solution is controlled by controlling the rotational speed of the pump 20, but the on-off valve 22 is replaced with a flow rate adjustment valve, and this flow rate adjustment is performed by the controller 28. You may carry out by adjusting the opening degree of a valve.

In this embodiment, the flow rate of the molybdate ion-containing solution is controlled using the control device 28, but the control may be performed manually. That is, the operator inputs necessary information to the personal computer, and the injection flow rate F _tank ^Mo (t / h) of the molybdate ion-containing solution (for example, molybdate solution) according to the equation (1) is calculated by the personal computer. Based on the determined injection flow rate F _tank ^Mo (t / h), the operator adjusts the rotational speed of the pump 20.

Instead of the molybdate (H ₂ MoO ₄ ) solution, any of a sodium molybdate (Na ₂ MoO ₄ ) solution, a potassium molybdate (K ₂ MoO ₄ ) solution and a lithium molybdate (Li ₂ MoO ₄ ) solution, or When a molybdate (H ₂ MoO ₄ ) solution containing a cation impurity is injected into the water supply pipe 11, the molybdate ion-containing solution injector 18 is replaced with the molybdate ion-containing solution injector 18A shown in FIG. You may change. The molybdate ion-containing solution injector 18A has a configuration in which a cation exchange resin tower 30 is added to the molybdate ion-containing solution injector 18. The other configuration of the molybdate ion-containing solution injection device 18A is the same as that of the molybdate ion-containing solution injection device 18. The cation exchange resin tower 30 is provided in the injection pipe 21 between the pump 20 and the on-off valve 22. The injection pipe 21 is connected to the water supply pipe 11 as shown in FIG. The cation exchange resin tower 30 may be applied to Examples 3 and 5 described later.

The solution containing molybdate ions and cation impurities in the molybdate ion-containing solution storage tank 19 is guided to the cation exchange resin tower 30 by driving the pump 20. Thereby, cations such as cation impurities contained in the solution containing molybdate ions are removed by the cation exchange resin tower 30, and the molybdate ions can be injected into the feed water. Injecting cations such as cation impurities into the water supply can be prevented. Na ⁺ ions are present when a sodium molybdate solution is used, K ⁺ ions are present when a potassium molybdate solution is used, and Li ⁺ ions are present when a lithium molybdate solution is used. . The cation exchange resin tower 30 removes Na ⁺ ions, K ⁺ ions, and Li ⁺ ions.

  By installing the cation exchange resin tower 30, the influence of cations such as cation impurities into the reactor pressure vessel 3 (activation of cations, influence on stress corrosion cracking, oxidation of the fuel rod cladding tube) (Acceleration and increase in load of the reactor purification system 13 demineralizer 17 due to an increase in impurities in the reactor water) can be eliminated, and the cobalt radioactivity concentration in the reactor water can be reduced.

  A cation exchange membrane may be installed in place of the cation exchange resin tower 30.

  A water quality control method for a boiling water nuclear power plant according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG. The boiling water nuclear power plant 1A to which the present embodiment is applied is different from the boiling water nuclear power plant 1 to which the first embodiment is applied in that the molybdate ion-containing solution injector 18 is replaced with the tungstate ion-containing solution injector (tungstate ion implanter). The control device 28 is replaced with a control device 28A. The other configuration of the boiling water nuclear plant 1A is the same as that of the boiling water nuclear plant 1.

The tungstate ion-containing solution injection device 31 has a configuration in which the molybdate ion-containing solution tank 19 is replaced with a tungstate ion-containing solution tank 32 in the molybdate ion-containing solution injection device 18. Other configurations of the tungstate ion-containing solution injection device 31 are the same as those of the molybdate ion-containing solution injection device 18. The tungstate ion-containing solution tank 32 is filled with a tungstate ion-containing solution. The tungstate ion-containing solution is a tungstate ion that contains an isotope that does not generate secondary radioactivity of tungsten (for example, ¹⁸⁰ W, ¹⁸² W, etc.) It contains tungstate ions including isotopes that generate secondary radioactivity (eg, ¹⁸⁴ W, ¹⁸⁶ W, etc.). Examples of the tungstate ion-containing solution include a tungstic acid (H ₂ WO ₄ ) solution, a sodium tungstate (Na ₂ WO ₄ ) solution, a lithium tungstate (Li ₂ WO ₄ ) solution, and a potassium tungstate (K ₂ WO ₄ ) solution. Either of these is used.

  During the operation of the boiling water nuclear power plant 1A, a part of the reactor water flowing in the purification system pipe 14 is sampled by the sampling pipe 27, and the sampled reactor water is analyzed by chromatography or the like. Thereby, each density | concentration of substances, such as cobalt ion and tungstate ion contained in this reactor water, is measured.

During operation of the boiling water nuclear power plant 1 </ b> A, a tungstate ion-containing solution is injected into the feed water pipe 11 from the tungstate ion-containing solution tank 32 of the tungstate ion-containing solution injection device 31. In this embodiment, a tungstic acid (H ₂ WO ₄ ) solution is used as the tungstate ion-containing solution.

The injection of the tungstic acid solution by the tungstate ion-containing solution injection device 31 will be described in detail. The measured concentrations of cobalt ions and tungstate ions are input from an input device (not shown) to the control device 28A by an operator. The control device 28A inputs the flow rate of the reactor water flowing through the purification system pipe 14 measured by the flow meter 29. The control device 28A determines the measured flow rate F _RWCU (t / h) of the reactor water flowing through the purification system pipe 14 and the set concentration C _{RW, W} ^set (mol / kg) of tungstate ions contained in the reactor water. Substituting into the equation (3), the injection flow rate F _tank ^W (t / h) of the tungstate ion-containing solution is obtained.

Where C _{RW, W} ^meas is the measured concentration (mol / kg) of tungstate ion in the reactor water, and C _tank ^W is the tungstate ion contained in the tungstate ion-containing solution filled in the tungstate ion-containing solution storage tank. The concentration (mol / kg) and f _W are factors.

When calculating the injection flow rate F _tank ^W (t / h) of the tungstate ion-containing solution based on the equation (3), a factor f _W assumed to be 1 at first is used. The concentration C _tank ^W (mol / kg) of the tungstate ion contained in the tungstate solution filled in the tungstate ion-containing solution storage tank 31, for example, 0.03 mol / kg and the set concentration of molybdate ions in the reactor water. C _{RW, W} ^set (mol / kg), for example, 1 × 10 ⁻⁷ mol / kg is also input to the control device 28A by the operator. The set concentration C _{RW, W} ^set of tungstate ions, 1 × 10 ⁻⁷ mol / kg, is included in the above-described range of 1 × 10 ⁻⁷ mol / kg to 1 × 10 ⁻⁶ mol / kg. . The flow rate F _{RWCU of the} reactor water flowing through the purification system pipe 14 measured by the flow meter 29 is, for example, 128 t / h and is input to the control device 28A.

The control device 28A opens the on-off valve 22 to drive the pump 20, and substitutes the above numerical values into the equation (3) to calculate the injection flow rate F _tank ^W of the tungstate ion-containing solution, that is, the tungstate solution. . The calculated flow rate F _tank ^W of the tungstic acid solution is 3.84 × 10 ⁻⁴ t / h. The control device 28A controls the rotational speed of the pump 20 so that the calculated tungstic acid solution injection flow rate F _tank ^W (t / h) is obtained. The tungstic acid solution in the tungstate ion-containing solution storage tank 32 is supplied into the water supply pipe 11 at 4.27 × 10 ⁻⁴ t / h. In this way, tungstate ions are injected into the feed water, guided into the reactor pressure vessel 3 together with the feed water, and injected into the reactor water in the reactor pressure vessel 3. The measured cobalt ions are monitored by analyzing the reactor water sampled by the sampling pipe 27. The control device 28A determines whether or not the tungstate ion concentration measured by analyzing the reactor water sampled by the sampling pipe 27 after the injection of the tungstate solution is the set concentration C _{RW, W} ^set of tungstate ions. . If the tungstate ion concentration is the set concentration C _{RW, W} ^set of the tungstate ion, the control device 28A continues to inject the tungstate solution at 4.27 × 10 ⁻⁴ t / h.

If the controller 28A determines that the measured tungstate ion concentration is not the set concentration _CRW, ^Wset of the tungstate ion, the measured tungstate ion concentration and the tungstate ion The factor f _W is calculated by substituting the set density C _{RW, W} ^set of In this example, the measured concentration _{CRW, W} ^meas of tungstate ions in the reactor water after the tungstic acid solution is injected is 0.8 × 10 ⁻⁷ mol / kg. Therefore, it is determined that the measured density C _{RW, W} ^meas is not the set density C _{RW, W} ^set .

The controller 28A substitutes 1 × 10 ⁻⁷ mol / kg and 0.8 × 10 ⁻⁷ mol / kg into the equation (4) to calculate the factor f _W. By substituting the calculated factor f _W of 1.25 into the equation (3), the injection flow rate F _tank ^W (t / h) of the tungstic acid solution is newly calculated. The newly obtained injection flow rate F _tank ^W is 5.33 × 10 ⁻⁴ t / h. The control device 28A controls the rotational speed of the pump 20 based on the newly obtained injection flow rate F _tank ^W (t / h) of the tungstic acid solution. As a result, the tungstic acid solution is supplied from the tungstate ion-containing solution storage tank 32 to the water supply pipe 11 at 5.33 × 10 ⁻⁴ t / h. That is, a necessary amount of tungstate ion is injected into the water supply pipe 11. The concentration of tungstate ions contained in the reactor water is adjusted to the set concentration C _{RW, W} ^set (for example, 1 × 10 ⁻⁷ mol / kg) of tungstate ions by controlling the injection of the tungstate solution by the control device 28A. .

In the present embodiment, the concentration of tungstate ions contained in the reactor water in the reactor pressure vessel 3 is 1 × 10 ⁻⁷ mol / kg, and as in the first embodiment, the outer surface of the cladding tube made of zirconium alloy is applied. Adhesion of non-radioactive cobalt (for example, cobalt 59) is suppressed, and the production amount of radioactive cobalt in the core is reduced. For this reason, the cobalt radioactivity density | concentration in a reactor water falls to 1/3 of the past by application of the tungstate ion implantation of a present Example. The surface dose rate of the reactor pressure vessel 3 and the piping through which the reactor water in the reactor pressure vessel 3 such as the purification system piping 14 flows is reduced, and the exposure of workers in the periodic inspection of the boiling water nuclear power plant 1 can be reduced. . By the way, when the operation of applying the molybdate ion implantation of this embodiment is started in a state where the pipe dose rate is 0 in the newly installed boiling water nuclear power plant and the existing boiling water nuclear power plant that has been chemically decontaminated. The exposure dose rate after the end of the first operation cycle (for example, 10000 hours) decreases to 1/2 ((piping dose rate when this embodiment is applied) = (when this embodiment is not applied) (Dose rate for piping) x (1/2)). After the equilibrium cycle of the boiling water atomic weight plant 1A, for example, after the boiling water atomic weight plant 1A has experienced about five operating cycles, the molybdate ion implantation of this embodiment is applied to the boiling water nuclear power plant. In this case, the pipe dose rate is reduced to 4/5 at the end of the first operation cycle after the application of this embodiment ((pipe dose rate when this embodiment is applied) = (this embodiment is not applied). (Pipe dose rate in case) x (4/5)) After 10 operation cycles, the pipe dose rate drops to 3/5 ((pipe dose rate when this embodiment is applied) = (this embodiment is applied) (Pipe dose rate when not) x (3/5)).

In this embodiment, the tungstate ions injected into the reactor water have the secondary radioactivity of tungsten, such as ¹⁸⁰ W and ¹⁸² W, which are isotopes that do not generate secondary radioactivity. Each tungstate ion such as ¹⁸⁴ W, ¹⁸⁶ W and the like, which are generated isotopes, is included. For this reason, in this embodiment, there is no need to perform tungsten isotope separation and remove tungsten isotopes that generate secondary radioactivity as in JP-A-7-84090. Even if tungstate ions containing tungsten (for example, ¹⁸⁴ W, ¹⁸⁶ W, etc.) that generate secondary radioactivity exist as tungstate ions to be implanted, the concentration of tungstate ions contained in the reactor water is 1 Since it is × 10 ⁻⁷ mol / kg, the exposure of workers can be reduced.

  Since a tungstate ion which suppresses the stress corrosion crack of a structural member is inject | poured into a reactor water, a present Example can suppress the stress corrosion crack of the structural member which contacts this reactor water.

  Also in this embodiment, since hydrogen is injected from the hydrogen injection device 23 into the water supply pipe 11, the oxygen concentration and the hydrogen peroxide concentration contained in the reactor water can be reduced.

  Instead of connecting the injection pipe 21 of the tungstate ion-containing solution injection device 31 to the water supply pipe 11, it connects to the purification system pipe 14 downstream of the desalter 17 and injects tungstate ions into the purification system pipe 14. Also good. Connecting the tungstate ion-containing solution injection device 31 to the purification system pipe 14 instead of connecting to the water supply pipe 11 is the case of injecting tungstate ions described in Example 4 and Example 5 described later. You may apply to.

  In this embodiment, the injection flow rate of the tungstate ion-containing solution is controlled by controlling the rotational speed of the pump 20, but the control device 28A replaces the on-off valve 22 with a flow rate control valve, and this flow rate control is performed. You may carry out by adjusting the opening degree of a valve.

In this embodiment, the control of the injection flow rate of the tungstate ion-containing solution is performed using the control device 28A, but the control may be performed manually. That is, the operator inputs necessary information to the personal computer, and the injection flow rate F _tank ^W (t / h) of the tungstate ion-containing solution according to the equation (3) is calculated by the personal computer. Based on the determined injection flow rate F _tank ^W (t / h), the operator adjusts the rotational speed of the pump 20.

  A water quality control method for a boiling water nuclear power plant according to embodiment 3, which is another embodiment of the present invention, will be described with reference to FIG. A boiling water nuclear plant 1B to which the present embodiment is applied has a configuration in which the control device 28 is replaced with a control device 28B in the boiling water nuclear plant 1 to which the first embodiment is applied. The other configuration of the boiling water nuclear plant 1B is the same as that of the boiling water nuclear plant 1.

  The water quality control method of the boiling water nuclear power plant according to the present embodiment is such that the ratio MoC / CoC of the molar concentration MoC of molybdate ions to the molar concentration CoC of cobalt ions in the reactor water satisfies 0 <MoC / CoC <1200. Molybdate ions are added to the reactor water. In the present embodiment, the molar concentration ratio MoC / CoC existing within the range of 0 <MoC / CoC <1200 is set in the control device 28B as the set value of the molar concentration ratio MoC / CoC. The operator inputs, for example, 30 as the set value of the molar concentration ratio MoC / CoC to the control device 28B using the input device. This set value is registered in the memory of the control device 28B. The set value 30 of the molar concentration ratio MoC / CoC is the molar concentration ratio MoC / CoC at which the effect of reducing the exposure dose by molybdate ion implantation is maximized.

  After the boiling water nuclear power plant 1B is operated and feed water is supplied to the reactor pressure vessel 3 through the feed water pipe 11, a molybdate ion-containing solution, for example, a molybdate solution is supplied from the molybdate ion-containing solution injector 18 to the feed water pipe. 11 is injected. The molybdic acid solution in the present embodiment is injected into the reactor water in the reactor pressure vessel 3 as follows.

The molar concentration of cobalt ions in the reactor water measured by analysis of the reactor water sampled by the sampling pipe 27 is input to the control device 28B. The controller 28B integrates the set value of the molar concentration ratio MoC / CoC and the measured molar concentration of cobalt ions, and calculates the molar concentration of molybdate ions. Molarity MoC of the calculated molybdate ions, set of molybdate ions contained in the reactor water concentration C _RW, a _Mo ^{The set.} The controller 28B uses the set concentration C _{RW, Mo} ^set of the molybdate ions to inject the molybdate ions into the water supply, that is, the molybdate solution calculated by the equation (1), as in the first embodiment. The molybdic acid solution is injected into the feed water based on the injection flow rate F _tank ^Mo (t / h).

It is assumed that the cobalt ion concentration contained in the reactor water measured by the analysis of the reactor water sampled by the sampling pipe 27 is 1 × 10 ⁻⁸ mol / kg, for example. Based on the measured value of the cobalt ion concentration and the set value 30 of the molar concentration ratio MoC / CoC, the control device 28B calculates the concentration of molybdate ions contained in the reactor water, and this concentration is 3.0. × 10 ⁻⁷ mol / kg is obtained. For this reason, 3.0 × 10 ⁻⁷ mol / kg is registered in the control device 28B as the set concentration C _{RW, Mo} ^set of molybdate ions.

First, the control device 28B sets the factor f _Mo to 1, the measured molybdate ion concentration C _tank ^Mo (for example, 0.1 mol / kg), and the measured flow rate of the reactor water flowing in the purification system pipe 14. F _RWCU (for example, 128 t / h), the set concentration of molybdate ions C _{RW, Mo} ^set (for example, 3.0 × 10 ⁻⁷ mol / kg) is substituted into the formula (1), and the molybdate solution is the infusion rate F _tank ^Mo calculating a 3.84 × ¹⁰ -4 t / h. The control device 28B adjusts the rotational speed of the pump 20 so that the flow rate of the molybdate solution injected from the molybdate ion-containing solution storage tank 19 into the water supply pipe 11 becomes 3.84 × 10 ⁻⁴ t / h. However, since the molybdate ion concentration in the reactor water does not become 3.0 × 10 ⁻⁷ mol / kg even by the injection of the molybdic acid solution, the control device 28B renews the factor f _Mo based on the equation (2). To obtain 1.2 as a factor f _Mo. The control device 28B substitutes 1.2 and the above-described numerical values into the equation (1), recalculates the injection flow rate F _tank ^Mo of the molybdic acid solution, and newly obtains 4.61 × 10 ⁻⁴ t / h. . The control device 28B controls the injection flow rate of the molybdate solution into the water supply by the molybdate ion-containing solution injection device 18 based on 4.61 × 10 ⁻⁴ t / h. As a result, a predetermined amount of molybdate ions are injected into the reactor water in the reactor pressure vessel 3.

In the present embodiment, the set value (for example, 30) of the molar concentration ratio MoC / CoC registered in the control device 28B is not changed, but the cobalt ion concentration contained in the reactor water is the molybdate ion concentration in the reactor water. Varies with injection. For this reason, the molybdate ion concentration in the reactor water determined based on the measured cobalt ion concentration changes, and the set concentrations C _{RW, Mo} ^{set of the} molybdate ions set in the control device 28B also change. However, the control device 28B calculates the injection flow rate F _tank ^Mo of the molybdic acid solution from the equation (1) using the updated updated molybdate ion set concentration C _{RW, Mo} ^set .

In the present embodiment, each effect produced in the first embodiment can be obtained. This embodiment set concentration C _RW molybdate ion, which has been calculated based on the cobalt ion concentration in the reactor _water, using a _Mo ^{The set} to calculate the infusion rate F _tank ^Mo molybdate solution, replacement and the water quality of the reactor internal material When the concentration of cobalt ions in the reactor water changes with the change, the molybdate ion implantation concentration can be optimized.

  The control executed by the control device 28B may be performed manually.

  A water quality control method for a boiling water nuclear power plant according to embodiment 4, which is another embodiment of the present invention, will be described with reference to FIG. A boiling water nuclear power plant 1C to which the present embodiment is applied has a configuration in which the control device 28A is replaced with a control device 28C in the boiling water nuclear power plant 1A to which the second embodiment is applied. The other configuration of the boiling water nuclear plant 1C is the same as that of the boiling water nuclear plant 1A.

  The water quality control method for the boiling water nuclear power plant according to the present embodiment is such that the ratio WC / CoC of the molar concentration WC of tungstate ions to the molar concentration CoC of cobalt ions in the reactor water satisfies 0 <WC / CoC <70. The tungstate ion is added to the reactor water. In the present embodiment, the molar concentration ratio WC / CoC existing within the range of 0 <WC / CoC <70 is set in the control device 28C as the set value of the molar concentration ratio WC / CoC. The operator inputs, for example, 30 as the set value of the molar concentration ratio WC / CoC to the control device 28C using the input device. This set value is registered in the memory of the control device 28C. The set value 30 of the molar concentration ratio WC / CoC is the molar concentration ratio WC / CoC that maximizes the dose reduction effect by tungstate ion implantation.

  After the boiling water nuclear power plant 1C is operated and feed water is supplied to the reactor pressure vessel 3 through the feed water pipe 11, a tungstate ion-containing solution, for example, a tungstate solution is supplied from the tungstate ion-containing solution injector 31 to the feed water pipe. 11 is injected. Injection of the tungstic acid solution in the present embodiment into the reactor water in the reactor pressure vessel 3 is performed as follows.

The measured molar concentration of cobalt ions in the reactor water is input to the controller 28C. The controller 28C integrates the set value of the molar concentration ratio WC / CoC and the measured molar concentration of cobalt ions, and calculates the molar concentration of tungstate ions. Molar concentration of the calculated tungstate ions, set of tungstate ions contained in the reactor water concentration C _RW, a _W ^{The set.} The control device 28C uses the set concentration _{CRW, W} ^set of the tungstate ion to inject the tungstate ion into the water supply, that is, the tungstate solution calculated by the equation (3), as in the second embodiment. The tungstic acid solution is injected into the feed water based on the injection flow rate F _tank ^W (t / h).

It is assumed that the cobalt ion concentration contained in the reactor water measured by the analysis of the reactor water sampled by the sampling pipe 27 is, for example, 1 × 10 ⁻⁹ mol / kg. Based on the measured value of the cobalt ion concentration and 30 which is the set value of the molar concentration ratio WC / CoC, the control device 28C calculates the concentration of tungstate ion contained in the reactor water, and this concentration is 3.0. × 10 ⁻⁸ mol / kg is obtained. Therefore, 3.0 × 10 ⁻⁸ mol / kg is registered in the control device 28C as the set concentration C _{RW, W} ^set of tungstate ions.

First, the controller 28C sets the factor f _W to 1, the measured tungstate ion concentration C _tank ^W (for example, 0.01 mol / kg), and the measured flow rate of the reactor water flowing in the purification system pipe 14 F _RWCU (for example, 128 t / h), the set tungstate ion set concentration C _{RW, W} ^set (for example, 3.0 × 10 ⁻⁸ mol / kg) is substituted into the formula (3), and the tungstic acid solution An injection flow rate F _tank ^W of 3.84 × 10 ⁻⁴ t / h is calculated. The control device 28C adjusts the rotational speed of the pump 20 so that the injection flow rate of the tungstic acid solution from the tungstate ion-containing solution storage tank 32 to the water supply pipe 11 becomes 3.84 × 10 ⁻⁴ t / h. However, since the tungstate ion concentration in the reactor water does not become 3.0 × 10 ⁻⁷ mol / kg even by the injection of the tungstic acid solution, the control device 28C newly sets the factor f _W based on the equation (4). To obtain 1.2 as a factor f _Mo. The control device 28C substitutes 1.2 and the above-described numerical values into the equation (3), recalculates the injection flow rate F _tank ^W of the tungstic acid solution, and newly obtains 4.61 × 10 ⁻⁴ t / h. . The control device 28C controls the injection flow rate of the tungstic acid solution into the water supply by the tungstate ion-containing solution injection device 31 based on 4.61 × 10 ⁻⁴ t / h. As a result, a predetermined amount of tungstate ion is injected into the reactor water in the reactor pressure vessel 3.

In the present embodiment, the set value (for example, 30) of the molar concentration ratio WC / CoC registered in the control device 28C is not changed, but the cobalt ion concentration contained in the reactor water is the tungstate ion concentration in the reactor water. Varies with injection. For this reason, the tungstate ion concentration in the reactor water obtained based on the measured cobalt ion concentration changes, and the set concentration _{CRW, W} ^{set of} tungstate ions set in the control device 28C also changes. However, the control device 28C calculates the injection flow rate F _tank ^W of the tungstic acid solution according to the equation (3) using the updated updated tungstate ion concentration C _{RW, W} ^set .

In the present embodiment, each effect produced in the second embodiment can be obtained. The present embodiment for calculating the injection flow rate F _tank ^W of the tungstic acid solution using the set concentration _{CRW, W} ^set of the tungstate ion obtained based on the cobalt ion concentration of the reactor water is the replacement of the structural material in the reactor and the water quality. When the concentration of cobalt ions in the reactor water changes with the change, the tungstate ion implantation concentration can be optimized.

  The control executed by the control device 28C may be performed manually.

  A water quality control method for a boiling water nuclear power plant according to embodiment 5, which is another embodiment of the present invention, will be described with reference to FIG. In the boiling water nuclear power plant 1D to which the present embodiment is applied, the control device 28 is replaced with the control device 28D in the boiling water nuclear power plant 1 to which the first embodiment is applied, and a zinc ion-containing solution injection device 33 is further added. The configuration is as follows. The other configuration of the boiling water nuclear plant 1D is the same as that of the boiling water nuclear plant 1.

  The difference between the boiling water nuclear plant 1D and the boiling water nuclear plant 1 will be described. The zinc ion-containing solution injection device 33 includes a zinc ion-containing solution tank 34, a pump 35, and an injection pipe 36. An injection pipe 36 provided with a pump 35 and an on-off valve 37 is connected to a zinc ion-containing solution tank 34 and a water supply pipe 11 filled with a zinc ion-containing solution. The injection pipe 36 is connected to the water supply pipe 11 between the connection point of the injection pipe 21 and the water supply pipe 11 and the hollow filter 8A.

  The control device 28D controls the rotational speed of the pump 20 of the molybdate ion-containing solution injection device 18 to adjust the injection amount of the molybdate ion-containing solution into the water supply pipe 11, and the pump of the zinc ion-containing solution injection device 33. By controlling the rotational speed of 35, the injection amount of the zinc ion-containing solution into the water supply pipe 11 is adjusted.

  In the water quality control method for a boiling water nuclear plant according to the present embodiment, during operation of the boiling water nuclear plant 1D in which feed water is supplied to the reactor pressure vessel 3, the molybdate ion-containing solution and the zinc ion-containing solution are: It is injected into the feed water and supplied into the reactor pressure vessel 3. The cobalt ion concentration, molybdate ion concentration, and zinc ion concentration measured in the reactor water sampled by the sampling pipe 27 are input from the input device to the control device 28D by the operator. In this embodiment, the measured cobalt ion concentration is used for monitoring.

  A molybdate ion-containing solution, for example, a molybdate solution, is controlled by the control device 28D and supplied from the molybdate ion-containing solution tank 19 of the molybdate ion-containing solution injection device 18 in the same manner as the control device 28 of the first embodiment. 11 is injected. A control device 28D that performs control to inject the molybdic acid solution into the water supply pipe 11 functions in the same manner as the control device 28 used in the first embodiment.

The injection of the zinc ion-containing solution not performed in Example 1 will be described in detail. The control device 28D is included in the measured flow rate F _RWCU (t / h) of the reactor water flowing in the purification system pipe 14, the measured zinc ion concentration C _{RW, Zn} ^meas (mol / kg) in the reactor water, and the reactor water. setting of zinc ion concentration ^{_{C RW, Zn set (mol /}} kg), and the concentration of zinc ion containing solution is filled into the storage tank 34 zinc ion containing zinc contained in the solution ion C _tank ^W a (mol / kg) ( 5) Substituting it into the equation, find the injection flow rate F _tank ^Zn (t / h) of the zinc ion-containing solution.

However, _fZn is a factor.

Nominal concentration C _RW in the reactor water zinc _{ion, Zn} ^{The set} is preferably set to the range of 1 × ¹⁰ -8 mol / kg of 2 × ¹⁰ -7 mol / kg. Nominal concentration C _RW of zinc ions in this _{embodiment, Zn} ^{The set} is set to 8 × ¹⁰ -8 mol / kg in the control device 28D.

In this embodiment, the control device 28D determines the flow rate F _{RWCU of the} reactor water flowing in the purification system pipe 14, which is substituted into the equation (1) to calculate the injection flow rate F _tank ^Mo (t / h) of the molybdic acid solution. 128 t / h, zinc ion set concentration C _{RW, Zn} ^set is 8 × 10 ⁻⁸ mol / kg, and zinc contained in the zinc ion-containing solution filled in the zinc ion-containing solution storage tank 34 An ion concentration C _tank ^Zn , for example, 2.7 × 10 ⁻² mol / kg is substituted into the equation (5) to determine the injection flow rate F _tank ^Zn (t / h) of the zinc ion-containing solution. At this time, 1 is used as the factor f _Zn . The calculated injection flow rate F _tank ^Zn of the zinc ion-containing solution is 3.79 × 10 ⁻⁴ t / h.

The control device 28D controls the rotational speed of the pump 35 so that the calculated injection flow rate F _tank ^Zn of the zinc ion-containing solution becomes 3.79 × 10 ⁻⁴ t / h. The zinc ion-containing solution in the zinc ion-containing solution tank 34 is supplied into the water supply pipe 11 at 3.79 × 10 ⁻⁴ t / h. In this way, zinc ions are injected into the feed water, guided into the reactor pressure vessel 3 together with the feed water, and injected into the reactor water in the reactor pressure vessel 3.

3. Zinc ions in the reactor water measured by analysis of the reactor water sampled by the sampling pipe 27 after the 3.79 × 10 ⁻⁴ t / h zinc ion-containing solution was supplied into the reactor pressure vessel 3 It is assumed that the concentration C _{RW, Zn} ^meas is, for example, 6.67 × 10 ⁻⁸ mol / kg. This zinc ion concentration C _{RW, Zn} ^meas is smaller than the set concentration C _{RW, Zn} ^set of zinc ions. The control device 28D supplies a set concentration of zinc ions C _{RW, Zn} ^set of 8 × 10 ⁻⁸ mol / kg and a measured concentration of zinc ions C _{RW, Zn} ^meas of 6.67 × 10 ⁻⁸ mol / kg. Substituting into the equation (6), the factor f _Zn is calculated. The factor f _Zn obtained from the equation (6) is 1.2.

The control device 28D calculates the injection flow rate F _tank ^Zn (t / h) of the zinc ion-containing solution by setting the factor f _Zn in the equation (5) to 1.2. The injection amount F _tank ^Zn becomes 4.55 × 10 ⁻⁴ t / h, and the rotational speed of the pump 35 is controlled by the control device 28D so that the zinc ion-containing solution in the zinc ion-containing solution tank 34 is 4.55 × 10 6. ^-4 t / h is supplied into the water supply pipe 11. Therefore, the concentration of zinc ions contained in the reactor water in the reactor pressure vessel 3 is adjusted to 8 × 10 ⁻⁸ mol / kg.

  In the present embodiment, each effect produced in the first embodiment can be obtained. Furthermore, since this embodiment injects zinc ions into the reactor water, it is possible to suppress corrosion of the components that come into contact with the reactor water in the boiling water nuclear power plant, and supply of non-radioactive cobalt (for example, cobalt 59). Can be reduced. For this reason, adhesion of a non-radioactive substance to the outer surface of the fuel rod can be further suppressed than in the first embodiment.

  You may install the zinc ion containing solution injection apparatus 33 used by a present Example in the boiling water nuclear power plant 1B to which Example 3 is applied. Thus, in the water quality control method for the boiling water nuclear power plant according to the third embodiment, zinc ions can be injected into the reactor water in the reactor pressure vessel 3 together with the injection of molybdate ions. Furthermore, you may install the zinc ion containing solution injection apparatus 33 in the boiling water nuclear power plant 1A to which Example 2 is applied, and the boiling water nuclear power plant 1C to which Example 4 is applied. In the water quality control method of the boiling water nuclear plant of the second embodiment and the water quality control method of the boiling water nuclear power plant of the fourth embodiment, zinc ions are introduced into the reactor water in the reactor pressure vessel 3 along with the injection of tungstate ions. Can be injected.

  The present invention can be applied to a boiling water nuclear power plant.

  1, 1A, 1B, 1C, 1D ... Boiling water nuclear power plant, 2 ... Reactor, 3 ... Reactor pressure vessel, 4 ... Reactor core, 8A ... Hollow core filter, 11 ... Feed water piping, 13 ... Reactor purification system, DESCRIPTION OF SYMBOLS 14 ... Purification system piping, 17 ... Demineralizer, 18 ... Molybdate ion containing solution injection apparatus, 19 ... Molybdate ion containing solution tank, 12, 35 ... Pump, 21, 36 ... Injection piping, 23 ... Hydrogen injection apparatus, 26, 27 ... sampling piping, 28, 28A, 28B, 28C, 28D ... control device, 30 ... cation exchange resin tower, 31 ... tungstate ion-containing solution injection device, 32 ... tungstate ion-containing solution tank, 33 ... zinc Ion-containing solution injection device, 34... Zinc ion-containing solution tank.

Claims (19)

In a water quality control method for a boiling water nuclear plant equipped with equipment for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less,
The ratio of the molybdate ion molar concentration MoC of the reactor water to the cobalt ion molar concentration CoC of the reactor water in the reactor pressure vessel so that the MoC / CoC satisfies 0 <MoC / CoC <1200. A water quality control method for a boiling water nuclear plant characterized by implanting ions.   The water quality control method for a boiling water nuclear plant according to claim 1, wherein molybdate ions are injected into the reactor water so that the ratio MoC / CoC satisfies 1≤MoC / CoC≤600.   Based on the measured cobalt ion concentration of the reactor water and the ratio MoC / CoC specified in the range of 0 <MoC / CoC <1200, the set concentration of the molybdate ion molar concentration is determined. The water quality control method for a boiling water nuclear plant according to claim 1, wherein the amount of molybdate ions injected into the reactor water is controlled based on the determined concentration.   The cobalt ion concentration of the reactor water is measured, and the set concentration of the molybdate ion molar concentration is determined based on the measured cobalt ion concentration and the ratio MoC / CoC specified in the range of 1 ≦ MoC / CoC ≦ 600. The water quality control method for a boiling water nuclear power plant according to claim 2, wherein the amount of molybdate ions injected into the reactor water is controlled based on the determined concentration.   A plurality of the molybdate ions include a first molybdate ion containing an isotope that does not generate secondary radioactivity of molybdenum, and a second molybdenum containing an isotope that generates secondary radioactivity of molybdenum. The water quality control method for a boiling water nuclear power plant according to any one of claims 1 to 4, comprising acid ions. In a water quality control method for a boiling water nuclear plant equipped with equipment for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less,
Tungstic acid in the reactor water so that a ratio WC / CoC of the tungstate ion molar concentration WC of the reactor water to the cobalt ion molar concentration CoC of the reactor water in the reactor pressure vessel satisfies 0 <WC / CoC <70. A water quality control method for a boiling water nuclear plant characterized by implanting ions.   A tungstate ion is injected into the reactor water so that a ratio WC / CoC of a tungsten ion molar concentration WC of the reactor water to a cobalt ion molar concentration CoC of the reactor water satisfies 1 ≦ WC / CoC ≦ 50. 7. A water quality control method for a boiling water nuclear plant according to 6.   The cobalt ion concentration of the reactor water is measured, and the set concentration of the tungstate ion molar concentration is determined based on the measured cobalt ion concentration and the ratio WC / CoC specified in the range of 0 <WC / CoC <70. The water quality control method for a boiling water nuclear power plant according to claim 6, wherein the amount of tungstate ions injected into the reactor water is controlled based on the determined concentration.   The cobalt ion concentration of the reactor water was measured, and the set concentration of the tungstate ion molar concentration was determined based on the measured cobalt ion concentration and the ratio WC / CoC specified in the range of 1 ≦ WC / CoC ≦ 50. The water quality control method for a boiling water nuclear power plant according to claim 7, wherein the amount of tungstate ions injected into the reactor water is controlled based on the determined concentration.   A plurality of the tungstate ions include a first tungstate ion containing an isotope that does not generate secondary radioactivity of tungsten, and a second tungsten containing an isotope that generates secondary radioactivity of tungsten. The water quality control method for a boiling water nuclear power plant according to any one of claims 6 to 9, comprising acid ions. In a water quality control method for a boiling water nuclear plant equipped with equipment for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less,
Molybdate ions are injected into the reactor water in the reactor pressure vessel, and the concentration of molybdate ions contained in the reactor water is within the range of 1 × 10 ⁻⁸ mol / kg or more and 1 × 10 ⁻⁶ mol / kg or less. A water quality control method for a boiling water nuclear power plant characterized by adjusting to a water temperature.   The molybdate ion concentration in the reactor water is measured, and the molybdate ion implantation is performed by controlling the amount of molybdate ion implantation into the reactor water based on the measured molybdate ion concentration. The water quality control method for a boiling water nuclear plant according to claim 11.   A plurality of the molybdate ions include a first molybdate ion containing an isotope that does not generate secondary radioactivity of molybdenum, and a second molybdenum containing an isotope that generates secondary radioactivity of molybdenum. The water quality control method for a boiling water nuclear plant according to claim 11 or 12, which contains acid ions. In a water quality control method for a boiling water nuclear plant equipped with equipment for suppressing the iron oxide concentration contained in the feed water supplied to the reactor pressure vessel to 1 × 10 ⁻⁹ mol / kg or less,
Tungstate ions are injected into the reactor water in the reactor pressure vessel, and the tungstate ion concentration contained in the reactor water is in the range of 1 × 10 ⁻⁸ mol / kg or more and 1 × 10 ⁻⁷ mol / kg or less. A water quality control method for a boiling water nuclear power plant characterized by adjusting to a water temperature.   The tungstate ion concentration of the reactor water is measured, and the tungstate ion implantation is performed by controlling the implantation amount of the tungstate ion into the reactor water based on the measured tungstate ion concentration. The water quality control method for a boiling water nuclear power plant according to claim 14.   A plurality of the tungstate ions include a first tungstate ion containing an isotope that does not generate secondary radioactivity of tungsten, and a second tungsten containing an isotope that generates secondary radioactivity of tungsten. The water quality control method for a boiling water nuclear power plant according to claim 14 or 15, comprising acid ions.   The water quality control method for a boiling water nuclear plant according to any one of claims 1 to 16, wherein zinc ions are injected into the reactor water.   18. The water quality control method for a boiling water nuclear plant according to claim 17, wherein the zinc ion concentration of the reactor water is measured, and the injection amount of the zinc ions into the reactor water is controlled based on the measured zinc ion concentration. .   The water quality control method for a boiling water nuclear plant according to any one of claims 1 to 17, wherein hydrogen is injected into the reactor water.

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