JPH0784090A - Method and device for injecting metal ion into reactor primary coolant - Google Patents

Abstract

PURPOSE:To suppress the rise of space dose rate and reduce the exposure of workers by controlling the isotope rate of used element and injecting metal ions not generating secondary radiation due to activation. CONSTITUTION:As for metal ions not generating secondary radiation due to activation, Mg, Cr and the like are used. Owing to the coexistence of these ions, radioactive ion adhesion to the structure in contact with coolant is suppressed. In the device generating this metal ions, carbondioxide gas, for example, is dissolved from a carbondioxide saturation tank 1 and a solution with carbondioxides ions in dissociation state is sent to an electrolysis tank 3 to cause electrode reaction. For the positive electrode 16 and the negative electrode 17, metal plates with controlled isotope ratios are used. A direct current source 19 impresses voltage to the electrode plates 16 and 17 through lead cables 18. By this, metal ion species concentration becomes arbitrarily and exactly controllable by controlling the current value and flow-in of unnecessary ion species can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for injecting metal ions into a reactor primary coolant in a nuclear power plant.

[0002]

2. Description of the Related Art In a boiling water reactor (BWR),
Particulate metal oxides (generally called clad) and ionic impurities brought in from the water supply system are fixed on the surface of the fuel cladding tube by the boiling concentration phenomenon. Further, in a pressurized water nuclear reactor (PWR), since the boiling phenomenon does not exist on the fuel surface, the adhesion phenomenon is observed although the clad adhesion amount is smaller than that of the BWR.

At the surface of the fuel, they are exposed to neutrons and activated to become radioactive corrosion products. The whole amount of generated radioactivity is not fixed on the fuel surface as it is, but part of it is exfoliated in the form of particles or eluted in the form of ions, increasing the radioactivity concentration in the primary coolant. .

Further, as a process of generating radioactivity, a process of peeling or eluting from the internal structural material and similarly being fixed on the fuel surface to be activated, or the core structural material being directly activated at that site, The process of eluting as is also considered.

Radioactivity generated through various processes is
Using the primary coolant as a medium, it reaches the entire primary system of the plant and pollutes each system. Further, the liquid contact portion of the primary coolant is almost a metallic material, and contamination is nothing but a phenomenon that radioactivity is incorporated into this metallic material.

[0006] The incorporation of particulate radioactivity is mainly a process of physical adsorption on the surface of a metal material or adhesion by gravity settling, while ionic radioactivity is the surface of a metal material when it corrodes. It is co-deposited as an oxide in the formed corrosion film or is incorporated by an isotope exchange reaction. For example, ⁶⁰ Co ²⁺ is considered to be incorporated into the film by the following two equations with the corrosion of steel materials.

[0007]

[Equation 1] In this way, the metal material in contact with the primary coolant takes up radioactivity, and its amount balances with the amount that increases over time due to the growth of the corrosion film and the rate that the amount of radioactivity taken in by radioactive decay decreases. It will continue to increase until you do. When radioactivity is accumulated on the surface of pipes and equipment, the air dose rate increases and the exposure dose of workers working in the vicinity increases, which in turn increases the total exposure dose during the periodic inspection period of the plant (total manrem). Push up.

As a result, an increase in the number of workers causes an increase in the cost of the regular inspection and an extension of the period of the regular inspection.
Therefore, for example, the radioactive ion attachment suppression method described in Japanese Examined Patent Publication No. 3-14155 (hereinafter referred to as the “Gazette”), the method of suppressing the accumulation of radioactivity, the method of removing the accumulated radioactivity (decontamination), etc. Is enthusiastically proposed.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
"In a method for suppressing the attachment of radioactive ions to a structural material that is in contact with a coolant containing radioactive ions, during operation of a nuclear power plant, the amount of metal ions in the coolant is measured, and based on this measurement value, Mg, Cr, V, Ti, C so that the amount of metal ions in the coolant becomes a predetermined value.
A method for suppressing the deposition of radioactive ions, characterized in that metal ions of at least one substance selected from the group consisting of u, Ni, Zn and Cd are injected into the coolant. Therefore, the present inventors conducted a similar test in accordance with the description of this publication to confirm the effectiveness and elucidate the mechanism thereof. As a result, the present publication discloses that, in the process in which ionic radioactivity is taken into the corrosion film accompanying the corrosion of the wetted part of the structural material, the uptake rate of these radioactive ions is different from that of the coexisting metal ion species. It is clarified that it is governed by a competitive reaction and uses this principle.

That is, the uptake of ions into the corrosion film is controlled by the concentration ratio of radioactive ions and other coexisting ionic species in the solution to a large or small extent, and the result is that the coexisting ionic species concentration is high. It was found that the uptake of radioactive ions into the corrosion film was suppressed.

Further, in the above publication, "Mg, Cr, V,
Although metal ion implantation of Ti, Cu, Ni, Zn and Cd can be expected to suppress the uptake of ionic radioactivity, a nuclear reaction occurs incidentally, and activation of each implanted metal causes ²⁷ Mg, ⁵¹ Cr, ⁵⁵ Cr, ⁵² V, ⁵¹ Ti, ⁶⁴
Cu, ⁶⁶ Cu, ⁶⁵ Ni, ⁵⁸ Co, ⁶⁹ Zn, ¹⁰⁷ Cd,
^It produces secondary radioactivity such as ¹¹¹ Cd.

The half-life of these is shorter than that of ⁶⁰ Co, and the radioactivity decreases in a short time even if they adhere to the pipe, so the amount of radioactivity decreases after waiting for a predetermined time after the operation is stopped. There is no problem if you wait for. Is concluded.

However, as a result of detailed verification in the isotope handbook and the like, the present inventors have found that adjusting the isotope ratio may cause no secondary radioactivity at all.

In order to suppress the increase of the air dose rate due to the deposition of radioactive corrosion products on the surface of the primary system piping and the equipment surface by comprehensively examining the transfer behavior of radioactivity, (1) Does not generate corrosion products (2) Keeps radioactivity in the generation site and does not transfer it to reactor water (3)
It does not increase the concentration by removing the radioactivity transferred to the reactor water,
(4) Do not let radioactivity adhere to the pipe surface or equipment, (5)
It was found that measures such as removing the attached radioactivity can be considered.

The present invention relates to a technique for preventing the radioactivity of the item (4) from adhering to the surface of a pipe or equipment, and by this technique, the increase of the air dose rate is suppressed, and the atomic dose that contributes to the reduction of the exposure of workers is reduced. An object of the present invention is to provide a method and an apparatus for injecting metal ions into a furnace primary coolant.

Further, in order to solve the problems in the prior art that the secondary radioactivity is generated and the injection method is defective, the ionic radioactivity corrodes the wetted part of the structural material. As a result, the rate of uptake of these radioactive ions is controlled by the competitive reaction with the coexisting metal ion species in the process of being incorporated into the corrosion film, and metal ion species are actively added. In this technology, the isotope ratio of the metal ion species to be injected is adjusted, and even if they are brought into the reactor, the highest injection effect can be obtained without generating secondary radioactivity due to the radiation ratio. An object of the present invention is to provide a method and an apparatus for injecting metal ions into the reactor during primary cooling.

[0017]

According to the present invention, in order to reduce the amount of radioactivity that is taken in during the process in which radioactive ions are taken into the corroded film of corroded parts of the structural material as they corrode. In the method of injecting metal ions into the reactor primary coolant to inject metal ions into the reactor primary coolant in the plant, adjusting the isotope ratio of the elements used for the injection, they are in the reactor It is characterized by injecting metal ions that do not generate secondary radioactivity by activation even when brought in.

Further, according to the present invention, the main steam system for guiding the steam generated in the reactor to the turbine and the steam working in the turbine as condensate, and the condensate system for guiding the condensate to the reactor and the reactor Adjust the isotope ratio of the elements used for injection into a nuclear power plant that has at least a water supply system and a reactor purification system that purifies impurities in the primary coolant, and bring them into the reactor. However, it is characterized in that a metal ion device capable of injecting metal ions which does not generate secondary radioactivity by activation is attached.

[0019]

[Function] For example, the corrosion products adhering to the surface of the fuel cladding are converted to radioactive corrosion products by neutron irradiation, and then re-released into the reactor water by melting or peeling, which causes corrosion of the wetted parts of the structural materials. The metal ion species are positively injected by utilizing the fact that the rate of uptake of these radioactive ions is governed by the competing reaction with the coexisting metal ion species in the process of being incorporated into the corrosion film.

According to the present invention, the isotope ratio of the metal ion species to be implanted is adjusted so that secondary radioactivity is not generated even when brought into the reactor, and the ion implantation is most effectively performed. .

Mg will be described as an example in which no secondary radioactivity is generated when the isotope ratio is adjusted. In the natural world, there are three types of Mg, ²⁴ Mg, ²⁵ Mg, and ²⁶ Mg in abundance ratios of 78.99, 10.00, and 11.01%, respectively. ²⁶ Mg generates a ^{26 Mg (n · γ) 27} Mg 27 Mg absorbs the neutrons by the reaction equation of.

At this time, the isotope ratio is adjusted so that ²⁶ Mg is excluded and one of ²⁴ Mg and ²⁵ Mg, or Mg composed of two components.
By using, it is possible to suppress the attachment of ionic radioactivity without any secondary radioactivity generated by injecting these.

Thus, in the present invention, adjusting the isotope ratio means the above operation. If the above isotope ratio is adjusted, not only Mg but also Cr, V, Ti, Ni,
It is applicable to Zn and Cd metal ions. Next, a method for adjusting the isotope ratio of the above metal ion will be described.

Cr: ⁵² C excluding ⁵⁰ Cr (4.35%)
The isotope ratio is adjusted to one of r, ⁵³ Cr, ⁵⁴ Cr or a multi-component body composed of them.

V: ⁵¹ V (99.75%) is excluded, and the isotope ratio is adjusted to ⁵⁰ V only. Ti: ⁵⁰ Ti (5.2%) is excluded, ⁴⁶ Ti, ⁴⁷ Ti, ⁴⁸
The isotope ratio is adjusted to one of Ti and ⁴⁹ Ti or a multi-component body composed of them.

Ni: ⁵⁸ Ni (68.3%), ⁶² Ni (3.59)
%), ⁶⁴ Ni (0.91%) are excluded, and 1 of ⁶⁰ Ni and ⁶¹ Ni
Adjust the isotope ratio to the species or two components.

Zn: ⁶⁴ Zn (48.6%), ⁶⁸ Zn (18.8
%), ⁷⁰ Zn (0.6%) is excluded, and 1 of ⁶⁶ Zn and ⁶⁷ Zn is excluded.
Adjust the isotope ratio to the species or two components.

Cd: ¹¹⁴ Cd (28.7%) is excluded, ¹⁰⁶
Cd, ¹⁰⁸ Cd, ¹¹⁰ Cd, ¹¹¹ Cd, ¹¹² Cd, ¹¹³
The isotope ratio is adjusted to one of Cd and ¹¹⁶ Cd or a multi-component body composed of them.

As described above, in the case of metal species in which the incorporation of ionic radioactivity is suppressed by the addition of metal ions, adjustment of the isotope ratio eliminates the generation of secondary radioactivity associated with the injection, and the metal ions The injection can be performed more effectively. Further, it is of course possible to adjust the isotope ratio not only for the above-mentioned metal species but also for the metal species for which similar effects can be expected.

Note that Cu is not applicable. In addition, molybdenum and tungsten can be applied as the metal having the effect of suppressing the uptake of ionic radioactivity. That is, molybdenum and tungsten are present in the BWR primary coolant in the form of metal ions or metal acid ions, but are applicable to the present invention.

Mo: Excludes ⁹⁸ Mo (24.1%), ⁹² M
o, ⁹⁴ Mo, ⁹⁵ Mo. ^The isotope ratio is adjusted to one of ⁹⁶ Mo, ⁹⁷ Mo, ¹⁰⁰ Mo or a multi-component body composed of them.

W: ¹⁸⁴ W (30.3%) and ¹⁸⁶ W (28.6%)
Is excluded, and the isotope ratio is adjusted to one of ¹⁸⁰ W, ¹⁸² W, and ¹⁸³ W or a multi-component body composed of them.

Ta is unadjustable (secondary radioactivity cannot be suppressed), and Nb is unadjustable (secondary radioactivity is not generated).

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first method and apparatus for injecting metal ions into a primary reactor coolant with reference to FIGS. 1 and 2.
An example will be described. FIG. 1 illustrates the method and apparatus of the first embodiment in a unified manner, and shows a metal ion implanting apparatus for generating a target metal ion having an adjusted isotope ratio.

In FIG. 1, reference numeral 1 is a carbon dioxide gas saturation tank in which an electrolytic solution is used as an electrolyte, which is connected to an electrolytic tank 3 via a first communication pipe 2 and is connected to the electrolytic tank 3 via a second communication pipe 4. The carbon dioxide gas removal tank 5 is connected. A bubbling line 7 having a discharge nozzle 8 is inserted in the carbon dioxide gas saturation tank 1, and the bubbling line 7 is connected to a carbon dioxide gas cylinder 9.

The carbon dioxide gas saturation tank 1 has an exhaust pipe from the upper end.
Seal pot 11 is connected via 10, and the water supply pipe is on the lower side
A flow control valve 13 is connected via 12 and a pure water supply line 15 for supplying pure water to the carbon dioxide saturated tank 1 is connected to the flow control valve 13. An anode 16 and a cathode 17 are provided in the electrolytic cell 3, and the anode 16 and the cathode 17 are connected via a lead wire 18 to a DC power source 19 respectively.
Connected to.

A jet nozzle 20 is provided in the carbon dioxide removing tank 5.
Is provided with a degassing gas bubbling line 21, which is connected to a degassing gas cylinder 23. An exhaust pipe 22 and a discharge pipe 24 are connected to the upper end of the carbon dioxide removal tank 5,
The exhaust pipe 22 is connected to an exhaust line 26 via a pump 27, and the discharge pipe 24 is connected to a seal pot 25.

By the way, from the pure water supply line 15 to the flow control valve 13
Is adjusted to continuously supply a constant amount of pure water to the carbon dioxide gas saturation tank 1. Carbon dioxide gas is supplied to the carbon dioxide gas saturation tank 1 from a carbon dioxide gas cylinder 9 through a bubbling line 7. As a result, carbon dioxide gas is dissolved in the solution in the metal ion saturation tank 1 to cause the following dissociation reaction and become an electrolyte to facilitate the electrode reaction.

[0039]

[Equation 2] Excess carbon dioxide gas is passed through the exhaust pipe 10 to the seal pot.
It is released from the system from 11.

Next, a solution in which carbon dioxide gas is dissolved and carbonate ions are in a dissociated state is sent to the electrolytic cell 3 to cause an electrode reaction. A metal plate having an adjusted isotope ratio is used for the anode 16 and the cathode 17. In the figure, the anode 16 and the cathode 17 are composed of two electrodes, but a plurality of electrodes are set to increase the generation amount, or electrodes made of different metal species are set to blend different ionic species. It can also be generated in the state.

The DC power supply 19 applies a DC voltage to the electrodes 16 and 17 through the lead wire 18. If the polarity of the DC voltage is switched at regular intervals to equalize the thinning of the plates of the electrodes 16 and 17, the material can be effectively used.

The electrolytic solution in which the metal ions are dissolved is then sent to the carbon dioxide gas removal tank 5 in order to remove the dissolved carbonate ions. In the carbon dioxide gas removing tongue 5, the degassing gas is sent from the degassing gas cylinder 23 through the bubbling line 21. Then, the dissolved carbonate ions are recovered in a gas state by the reverse reaction of the dissociation reaction. The recovered carbon dioxide gas and excess degassed gas flow through the discharge pipe 24 and are removed outside the system by the seal pot 25.

By the way, the above-mentioned publication describes a method of implanting metal ions, in which the tank is filled with metal ions and then, if necessary, pumping Cr. It is described therein that the tank is filled with Cr ions.

However, it is impossible to fill the chromium metal in an ionic state and at a high concentration to cope with the injection on a plant scale unless the pH of the solution in which Cr is dissolved is extremely acidic. When this method is adopted, it is obvious that the acidic solution is introduced into the plant along with the injection of the ionic species.

Although the ionic species introduced unnecessarily differs depending on what kind of acidic solution is used, Cl ⁻ , SO ₄
^2-, NO ₃ ^-, or the like is generally used. These anionic species threaten the integrity of structural materials and cause SCC (stress corrosion cracking).
It is known to be an accelerating factor of. in any case,
It goes without saying that implantation of metal ions other than the target metal ions should be prevented.

In the present invention, since the metal ion species to be injected are injected while being manufactured, the concentration in the tank is low, and the carbonate ions in the electrolytic solution are removed by degassing, so that unnecessary introduction of ion species is not required. It is suppressed and only the target metal ions are implanted.

Similarly, Mg, V, Ti, Ni, Z
With respect to n and Cd as well, there is a concern that incidental injection of anion species will occur in the method of storing in the tank.

Due to the degassing of carbon dioxide gas, some of the dissolved metal ions are precipitated in the solution as hydroxides of fine particles. However, when these fine particles are brought into high temperature water, they become ionic state again. This is because the solubilities of these metals are sufficiently high compared to the desired concentration (eg 10 ppb), which results in the initial introduction of unwanted ionic species into the reactor. It is possible to achieve the purpose of. The solution containing the target metal ion species is injected at the target point using the pump 27.

In the metal ion implanter shown in FIG. 1, the target metal ion species whose isotope ratio is adjusted is
A metal plate consisting of the element alone, or a plurality of metal plates containing a part thereof is used to generate a DC voltage, and by using this for injection, the metal ion species concentration can be arbitrarily and by adjusting the current value, It is possible to accurately control even a delicate value and prevent the inflow of unnecessary metal ion species.

Furthermore, the ion species to be implanted can be changed by exchanging the electrode plates, or the ion species can be easily blended by using a plurality of metal plates for the electrode plates. Of course, by increasing the number of electrode plates, injection from a laboratory scale to an actual plant scale is possible.

FIG. 2 shows an embodiment in which the metal ion implanter shown in FIG. 1 is applied to a boiling water nuclear power plant. In FIG. 2, a reactor core 30 is installed in a reactor pressure vessel 29, and steam is generated by a nuclear reaction. The generated steam is sent to the turbine 32 through the main steam line 31 for work. The steam that has worked returns to the water by the condenser 33. This water is sent to the condensate purification system 35 by the pump 34,
Remove impurities. After that, it is preheated by the feed water heater 36 and returns to the reactor.

On the other hand, the water in the nuclear reactor is forcibly circulated by the recirculation line 37 and the recirculation pump 38. The reactor water is taken out from a part of the recirculation line 37 by the reactor cleaning system pump 39 and sent to the reactor cleaning system.

Here, the reactor water is cooled through the regenerative heat exchanger 40 and the non-regenerative heat exchanger 41, and purified by the purification system 42. The reactor water from which impurities have been removed by the purification system is again preheated by the regenerative heat exchanger 40, and then returns from the water supply line 28 into the reactor pressure vessel 29.

In the boiling water nuclear power plant having the above flow, the metal ion monitor device 45 is attached to the reactor recirculation line 37. For the metal ion monitor device 45, an in-line ion chromatography device or the like may be optimal.

According to this apparatus, the metal ion concentration in the reactor water can be measured at regular intervals. Depending on the output of the metal ion monitoring device 45, opening and closing the valve 43,
The amount of metal ions generated by the metal ion implanter 44 can be controlled. With these systems, the metal ion concentration in the reactor water can be maintained at a predetermined value.

In the present embodiment, the metal ion implanting device 44 is installed at the outlet of the reactor water purifying system 42, but it is of course not limited to this position, and a portion in which high-temperature water of the same temperature as the reactor water temperature flows It can also be installed in a recirculation line, water supply line, etc.

FIG. 3 is for explaining the second embodiment of the present invention. In order to generate a target metal ion having an adjusted isotope ratio, a target element is brought into a metal state,
1 schematically shows an apparatus for implanting metal ions, which is installed in a high-temperature system to allow high-temperature water to pass therethrough and to obtain a predetermined concentration by a corrosion release reaction. In this figure, a method of filling a cylindrical column with fine metal particles and performing a test is described.

In FIG. 3, reference numerals 47, 48 and 49 denote valves. High temperature water is introduced from the upstream side of the valve 47 and passes through the column 46 filled with the metal particles 51. As a result, a corrosion release reaction occurs on the metal surface, and metal ions are released into high temperature water.

The metal particles 51 are sized to have a distribution of 0.1 to 1 mm to increase the specific surface area and
The packing density within 46 is improved. The metal particles 51 are held in a high temperature system by the screen 50. Then, the high-temperature water containing the target metal ions passes through the valve 48 and returns to the high-temperature system again.

The column 46 is provided with the bypass line 14, and high temperature water can be bypassed via the bypass valve 49. Further, the valves 48, 49 have a flow rate adjusting function and constantly adjust the opening degree while monitoring the metal ion concentration of the plant.

That is, when the metal ion concentration is lower than the predetermined value, the bypass valve 49 is throttled to increase the flow rate of the column 46. On the other hand, when it is higher than the predetermined value, the flow rate passing through the column 46 is narrowed down to increase the metal ion generation amount.

Instead of the fine metal particles 51 in the column 46 of FIG. 3, finely divided oxides may be filled and placed in a high temperature system to pass high temperature water to generate predetermined metal ions. . When an oxide is used, if it is fired at a temperature not lower than half of the melting temperature of the oxide and placed in a sintered state, the sintered state is maintained even when high-temperature water is passed through. Will not flow into the high temperature system by mistake, which makes it easy to maintain the high temperature system.

Furthermore, in the case of using fine metal particles or an oxide to generate a desired metal ion with an adjusted isotope ratio, the apparatus configuration is simple, and before the test, in the metal or the oxide. By reducing the amount of impurities contained therein, unnecessary ionic species that are incidentally brought in can be easily prevented.

FIG. 4 shows that, in order to generate a target metal ion with an adjusted isotope ratio, the target metal is processed into fine particles or an oxide state, and the metal is placed in a high temperature system and placed in high temperature water. An example is shown in which a method of passing water to obtain a predetermined concentration by a corrosion release reaction is applied to a boiling water nuclear power plant. In this embodiment, the adjustment of the flow rate flowing through the column does not depend on the flow rate control valve as shown in FIG.
This is done by adjusting the flow rate of the high pressure pump.

First, since the reference numerals 29 to 42 are the same as the components already described in FIG. 2, the description thereof will be omitted. Here, while monitoring the metal ion concentration in the reactor water with the metal ion monitoring device 45, in order to generate the metal ion with the target isotope ratio adjusted, the target metal is finely divided or oxidized. The column packed with material is shown at 52. This column 52 is connected to the recirculation line 37 by opening the valves 53 and 54. Reference numeral 55 denotes a high-pressure pump, which compensates for the pressure loss generated in the column 52 and regulates the flow rate flowing into the column 52. With such a device configuration, the flow rate of the gas flowing through the column 52 is adjusted by the output of the metal ion monitor to achieve a predetermined metal ion concentration in the reactor water.

In this embodiment, the apparatus for implanting metal ions is installed upstream of the recirculation pump 38 in the reactor recirculation line 37, but of course the present invention is not limited to this position, and is approximately the same as the reactor water temperature. It can be installed in the area where high temperature water is flowing (downstream side of the recirculation pump, water supply line, reactor water purification system outlet, etc.).

FIG. 5 is for explaining the third embodiment of the present invention. In order to generate a target metal ion, the target element is not an oxide but a hydride or hydroxide, Further, schematically shown is a metal ion injecting device, which is characterized in that it is in a compound state containing one or both of hydrogen and oxygen like a metal salt and is injected in a slurry state or a solution state to obtain a predetermined concentration. ing.

First, pure water is continuously supplied to the first tank 57 from the pure water supply line 56. A second tank in which an upper part of the first tank 57 is filled with a compound containing one or both of hydrogen and oxygen, such as a hydride or a hydroxide, and a metal salt in a fine powder state.
58 are installed.

The fine powder in the second tank 58 is continuously or intermittently supplied to the first tank 57. A forced agitator 59 such as an impeller is attached to the first tank 57 to prevent the fine powder from settling. The slurry-like suspension or solution is injected at a predetermined point by the high-pressure pump 60. These injected slurries are metal ionized by contact with high temperature water.

FIG. 6 shows that, in order to generate a metal ion having a desired isotope ratio adjusted, a target element other than an oxide, a hydride or a hydroxide, and a metal salt such as a metal acid salt are used. An example is shown in which a method of injecting in a slurry state or a solution state to obtain a predetermined concentration in a compound state containing one or both of oxygen and oxygen is applied to a boiling water nuclear power plant. In addition, reference numerals 29 to 42 represent FIG.
Since the components are the same as those already described in, the description thereof will be omitted.

In this embodiment, a metal ion monitor device is used.
While monitoring the metal ion concentration in the reactor water at 45, the suspension of the first tank 57, in which the particulate compound whose target isotope ratio is adjusted is suspended in the slurry, is supplied to the plant by the high-pressure pump 60. Injecting into line 28. In this system, the flow rate of the high pressure pump 60 is adjusted by the output of the metal ion monitoring device to achieve a predetermined metal concentration in the reactor water.

In the present embodiment, the metal ion implanting device is installed in the water supply line 28, but of course it is not limited to this position, and a portion (recirculation line) in which high-temperature water having the same temperature as the reactor water temperature is flowing. , Reactor water purification system outlet). In addition, the flow rate is large in each part of the plant,
There is no problem not only in the high temperature system but also in the low temperature system where the sedimentation in the line is negligible.

Furthermore, the present invention can also adopt the following embodiments.

(1) The polarity of the DC voltage applied to the electrode plate is switched at regular intervals to equalize the thinning of the electrode plate.

(2) When a DC voltage is applied to generate metal ions, carbon dioxide gas is previously dissolved in the electrolytic solution, and the solution is used as an electrolyte so that the electrode reaction can be easily performed.

(3) When a DC voltage is applied to generate metal ions, carbon dioxide gas is dissolved in the electrolytic solution in advance, and the solution is used as an electrolyte to facilitate the electrode reaction, and then the carbon dioxide gas is removed. It was removed from the solution by air gas to suppress the introduction of carbonate ions into the plant.

(4) The metal used is made into fine particles and sized so that the diameter thereof has a distribution of 0.1 to 1 mm in order to increase the specific surface area and the packing density.

(5) The oxide used is made into fine particles, and
Bake at a temperature that is at least half the melting temperature of the oxide, and supply in the sintered state.

The above embodiments of the present invention describe the boiling water nuclear power plant of the type in which the reactor water is forcedly circulated by the jet pump, but the reactor type is not limited to this. Includes a natural circulation type boiling water nuclear power plant that does not have a jet pump, an ABWR that does not have an external recirculation line and forcibly circulates reactor water by an internal pump, and a pressurized water nuclear power plant (PWR). It is also applicable to all light water reactors and heavy water reactors.

[0080]

EFFECTS OF THE INVENTION According to the present invention, in the process in which ionic radioactivity is incorporated into the corroded film of the structural material in association with the corrosion of the liquid contact portion, the incorporation rates of these radioactive ions coexist. Utilizing the fact that it is dominated by the competitive reaction with the metal ion species, in the technology of actively adding the metal ion species, the isotope ratio of the metal ion species to be injected is adjusted so that only specific isotope metal ion species To inject
It is possible to prevent the generation of secondary radioactivity and most effectively inject the metal ion species.

The target metal ion species is a metal plate consisting of a single metal element or a metal plate containing a part of the metal ion, and a DC voltage is applied to the target metal ion to adjust the target isotope ratio. Since this is generated and used for implantation, the ion species concentration can be controlled arbitrarily and accurately to a delicate value, and unnecessary implantation of metal ion species can be prevented.

When metal fine particles or oxides are used, the structure of the device is simple, and the amount of impurities contained in the metal or oxides before the test is reduced to bring them incidentally. Unwanted ionic species can be easily prevented.

Furthermore, if the target element is other than oxide,
One of hydrogen and oxygen, such as hydride or hydroxide or metal acid salt, or a compound state containing both,
When injecting in a slurry state or a solution state to obtain a predetermined concentration, not only the equipment configuration is simple, but also if it is a high flow rate part where sedimentation can be ignored, not only the high temperature system of the plant but also the low temperature system Can also be installed.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of a metal ion implantation apparatus according to the present invention.

FIG. 2 is a system diagram in which the metal ion implanter in FIG. 1 is applied to a BWR power plant.

FIG. 3 is a system diagram showing a second embodiment of the apparatus for implanting metal ions according to the present invention.

4 is a system diagram in which the metal ion implanter in FIG. 3 is applied to a BWR power plant.

FIG. 5 is a system diagram of a third embodiment of a metal ion implanter according to the present invention.

FIG. 6 is a system diagram in which the metal ion implanter in FIG. 5 is applied to a BWR power plant.

[Explanation of symbols]

1 ... Carbon dioxide saturation tank, 2 ... First communication pipe, 3 ... Electrolysis tank,
4 ... Second communication pipe, 5 ... Carbon dioxide removal tank, 7 ... Carbon dioxide bubbling line, 8 ... Discharge nozzle, 9 ... Carbon dioxide cylinder, 10 ... Gas pipe, 11 ... Seal pot, 12 ... Water supply pipe, 13 ... Flow rate Control valve, 14 ... Bypass line, 15 ... Pure water supply line, 16 ... Anode, 17 ... Cathode, 18 ... Lead wire, 19 ... DC power supply, 20 ... Jet nozzle, 21 ... Degassing gas bubbling line, 22 ... Exhaust pipe , 23 ... Degassing gas cylinder, 24 ... Discharge pipe, 25
... Seal pot, 26 ... Exhaust line, 27 ... Pump, 28 ... Water supply line, 29 ... Reactor pressure vessel, 30 ... Core, 31 ... Main steam line, 32 ... Turbine, 33 ... Condenser, 34 ... Pump, 35 …
Condensate purification system, 36 ... Feed water heater, 37 ... Recirculation line, 38 ...
Recirculation pump, 39 ... Pump, 40 ... Regenerative heat exchanger, 41 ... Non-regenerative heat exchanger, 42 ... Reactor water purification system, 43 ... Valve, 44 ... Ion implantation device, 45 ... Metal ion monitor device, 46 ... Filling Column, 47, 48, 49 ... Valve, 50 ... Screen, 51 ... Metal fine particles or metal oxide, 52 ... Packed column, 53, 54 ...
Valves, 55 ... High pressure pumps, 56 ... Pure water supply line, 57 ... First tank, 58 ... Second tank, 59 ... Stirring mechanism, 60 ... High pressure pump.

Claims (7)

[Claims] 1. A primary coolant for a nuclear reactor in a nuclear power plant in order to reduce the amount of radioactivity taken in during the process in which radioactive ions are taken into the corroded film of the structural material due to corrosion of the wetted part of the structural material. In a method of injecting metal ions into a reactor primary coolant in which metal ions are injected into the reactor, the isotope ratio of the element used to inject the metal ions is adjusted, and secondary radioactivity is generated by activation. A method of implanting metal ions into a primary reactor coolant, characterized by implanting metal ions that are not generated. 2. The metal ions which do not generate secondary radioactivity by the activation are Mg, Cr, V, T.
The injection of metal ions into the reactor primary coolant according to claim 1, which is a metal ion of at least one substance selected from the group consisting of i, Ni, Zn, Cd, Mo and W. Method. 3. A main steam system for guiding steam generated in a nuclear reactor to a turbine, and steam working in the turbine as condensate,
A reactor condensate system that guides this condensate to the reactor and a reactor water supply system, and a nuclear reactor purification system that purifies impurities in the primary coolant, at least Into the primary reactor coolant, which is equipped with a metal ion implanter that can adjust the isotope ratio and inject metal ions that do not generate secondary radioactivity by activation. Metal ion implanter. 4. The metal ion implanting apparatus uses a plurality of metal plates made of a target element or a metal plate containing a part thereof in order to generate a target metal ion, and applies a DC voltage thereto. The apparatus for injecting metal ions into the primary reactor coolant as claimed in claim 3, further comprising an electrolytic cell for making it. 5. The apparatus for implanting metal ions, in order to generate a target metal ion, sets a target element in a metal state, installs it in a high temperature system, passes hot water through it, and causes a corrosion release reaction. 4. An apparatus for injecting metal ions into a primary reactor coolant according to claim 3, further comprising an apparatus for obtaining a predetermined concentration according to. 6. The metal ion implanting apparatus, in order to generate a target metal ion, sets a target element in an oxide state, installs it in a high temperature system, and allows high temperature water to pass therethrough,
The apparatus for injecting metal ions into a primary reactor coolant according to claim 3, further comprising an apparatus for obtaining a predetermined concentration by a corrosion release reaction. 7. The device for implanting metal ions comprises, in order to generate a target metal ion, a target element other than an oxide, a hydride or a hydroxide, and a hydrogen salt such as a metal salt. 4. A device for obtaining a predetermined concentration by injecting oxygen in a compound state containing one or both of oxygen and injecting it in a slurry state or a solution state.
Apparatus for injecting metal ions into the reactor primary coolant described.