JP3266485B2 - Boiling water nuclear power plant, method of operating the same, and method of forming oxide film on wetted surface of its component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling water nuclear power plant and a method of operating the same, and also relates to a method of forming an oxide film on a wetted surface of a component in a boiling water nuclear power plant.

[0002]

2. Description of the Related Art A zirconium-based alloy is mainly used as a nuclear fuel element for a water-cooled nuclear power plant because of its small absorption cross section of fast neutrons and excellent corrosion resistance in high-temperature water. On the other hand, primary cooling system piping, pumps, and valve materials (hereinafter, referred to as piping materials) mainly use stainless steel,
Carbon steel and stellite are used.

[0003] An oxide film is formed and grows on the water-contact surface of these materials during the operation of the plant due to a corrosion reaction. Regarding the growth of the oxide film, it is necessary to control the growth from two viewpoints. One is to prevent corrosion damage,
Another is to suppress the incorporation of radioactive ions contained in the primary cooling water into the film. In the former, for example, the prevention of the leakage of nuclear fuel from the nuclear fuel element into the reactor water is the target, and in the latter, the radiation dose to workers during periodic inspections is reduced by lowering the surface dose rate of piping system materials That is the subject.

[0004] As the prior art for both, the improvement of the material, that is, the adjustment of the alloy composition and the improvement of the heat treatment conditions in the manufacturing process, have been advanced to prevent the corrosion damage of the former. The prefilming operation is effective for suppressing the surface dose rate of the piping system material.

[0005] First, a conventional technique for improving the corrosion resistance of a zirconium-based alloy which is a main material of a nuclear fuel element will be described. Zirconium alloys show better corrosion resistance than other metallic materials even in a radiation irradiation field and in a high-temperature high-pressure water or steam environment. However, fuel cladding tubes made of a zirconium alloy are used in the most severely corrosive environment among nuclear power plants, and various measures have been taken to improve the corrosion resistance of various materials.

[0006] The reason why the zirconium alloy exhibits higher corrosion resistance in a reactor water environment than other alloys is that an oxide film formed at an early stage of oxidation (corrosion) of the alloy acts as a protective layer against corrosion. Is raised. Zirconium alloy has no oxide film (accurately, zirconium alloy forms a film with a thickness of several nanometers only by exposure to air. The oxide film here refers to a film with a thickness of several tens of nanometers or more). The oxidation rate in high-temperature steam is extremely fast in the initial stage, but when an oxide film having a thickness of about 0.3 to 2 μm is formed, the oxidation rate becomes extremely small and further oxidation (corrosion) hardly proceeds. .

The oxide film at this stage is a dense black film. When corrosion progresses to a thickness of about 10 μm or more, or when spot-like local corrosion called nodular corrosion progresses, a white oxide film is formed. This white oxide film is porous and does not work as a protective layer.
In order to improve the corrosion resistance in the reactor water environment, the outer surface of the previous fuel cladding was treated with high-temperature steam at the stage of the manufacturing process, and a preliminary coating of about 0.3 to 0.8 μm was provided. . Therefore, a black oxide film stable against corrosion was formed on the outer surface of the fuel cladding tube before loading the fuel assembly into the nuclear reactor.

Further, regarding the oxide film on the outer surface in contact with the reactor water, a nuclear fuel cladding tube (see, for example, JP-A-61-196188) in which a 20-35 μm thick oxide film is formed on the outer surface in advance, or an oxide film is used. A nuclear fuel cladding tube formed by electrolysis (see, for example, JP-A-64-6891) has been proposed.

In recent fuel cladding, corrosion resistance has been remarkably improved by fine adjustment of alloy composition and improvement of heat treatment method in a manufacturing process. In order to prevent the oxidation of the soft pure zirconium layer lined on the inner surface as a liner layer to alleviate the action (PCI), a pre-oxidation step of the outer surface of the cladding tube in the manufacturing process is not performed.

Next, a description will be given of a conventional technique relating to a method of suppressing a surface dose rate of a piping material. In the primary cooling water of the reactor,
Due to the corrosion of the structural member, it contains ionic components such as Ni, Co, Fe, Cr, etc. and their oxide fine particles (referred to as cladding), though in very small amounts (ppt to ppb order). These corrosion products adhere to the surface of the fuel cladding tube in the nuclear reactor and undergo neutron irradiation. As a result, cobalt-60, cobalt-58, chromium-51, manganese-
A radionuclide such as 54 is produced.

[0011] These radionuclides are re-eluted into the reactor water and circulate through the primary cooling system as radioactive ions or radioactive cladding. Some of them are removed by the purification device of the reactor purification system, while the rest adhere to the surface of the piping system material while circulating through the primary reactor system. For this reason, the surface dose rate of the piping system member is increased, which is a cause of radiation exposure of workers when performing maintenance and inspection at the time of periodic inspection. The nature of the initial oxide film greatly affects the suppression of the surface dose rate, that is, the suppression of the amount of radioactive ions in the primary cooling water taken into the oxide film of the piping system.

For example, in the method described in Japanese Patent Application Laid-Open No. 62-95498, NaOH, LiOH, KOH or NH
3 When an oxide film is formed on the water-contact surface of the piping material while maintaining the pH at 8 to 9 by adding water, a stable oxide film with low porosity is formed. It has been shown that by performing this pre-filming treatment, it is possible to suppress the incorporation of radioactive ions from the primary cooling water into the oxide film thereafter.

[0013]

As described above, both the improvement of the corrosion resistance of nuclear fuel elements (mainly zirconium alloys) and the suppression of the surface dose rate of piping materials (mainly stainless steel, carbon steel and stellite) are: The properties of the oxide film in the initial stage have a significant effect. The above two objectives (improvement of corrosion resistance of nuclear fuel elements and suppression of surface dose rate of primary cooling system piping) can be achieved at the same time by adjusting water quality when starting up a new plant or when starting up a cycle after replacing pipes. desirable.

However, the conventional method described above, ie, pH = 8
The prefilming operation in an alkaline atmosphere of ~ 9 has an effect on suppressing the surface dose rate of the piping system material, but has no effect on improving the corrosion resistance of the nuclear fuel element. Rather,
For a zirconium alloy, an alkalinity-expressing substance (such as an alkali metal ion) may be taken into the initial oxide film, and the corrosion resistance may be reduced.

As one means for solving this problem, there is a method of applying an oxidation treatment in advance to the surface of the fuel cladding tube at the stage of the manufacturing process before the fuel is loaded into the nuclear reactor, thereby providing an oxide film. Has a soft pure zirconium layer as a liner layer on the inner surface to reduce the interaction (PCI) between fuel pellets and the cladding on the inner surface of the cladding tube, and oxidizes this liner layer. It is difficult to maintain the softness and to apply the oxide film only on the outer surface in the manufacturing process without performing the process.

The present invention has been made in view of the above, and it is an object of the present invention to easily improve the corrosion resistance of a nuclear fuel element and suppress the surface dose rate of a primary cooling system piping without using a special device. It is an object of the present invention to provide a boiling water nuclear power plant of this type, which can reduce the radiation exposure of workers during periodic inspections and the like, and a method for forming an oxide film on the water contact surface of its components. .

[0017]

That is, the present invention relates to a method for forming an oxide film on a water-contact surface of a primary component of a nuclear reactor of a boiling water nuclear power plant. When forming the reactor water, the reactor water was adjusted to have a pH converted to room temperature of less than 7.5 and a reactor water temperature of 25.
The temperature is maintained at 0 ° C. or higher for 20 to 50 hours, and then alkaline water is poured into the reactor water to adjust the pH at room temperature to 7.5 to 9.0, and the reactor water temperature is set to 250 ° C.
As described above, an oxide film is formed on the water-contacting surface of the constituent members of the primary reactor system by holding for 100 hours or more, thereby achieving the intended purpose.

Further, this method is performed during a reactor shutdown state in which a nuclear fission reaction does not occur or during an operation period from the reactor shutdown state to a state where the generator reaches a rated output operation state.

Further, in the method for operating a boiling water nuclear power plant equipped with a boiling water reactor, the reactor water is supplied during an operation period from a stop state of the reactor to a rated output operation state of the generator. The pH at room temperature is kept at a value lower than 7.5 and the reactor water temperature is kept at 250 ° C. or higher for 20 to 50 hours.
H is adjusted to a value of 7.5 to 9.0 and the temperature is maintained at 250 ° C. or higher for 100 hours or more, and the operation is performed while forming an oxide film on the wetted surface of the component member of the primary reactor. It is something to do.

That is, it becomes possible by performing a two-step prefilming operation. That is, during the operation period from the reactor shutdown state to the generator being in the rated output operation state, the reactor water is converted to a room temperature-converted pH of less than 7.5 and a reactor water temperature of 20 to 50 when the reactor water temperature is 250 ° C. or higher. Hold time,
Thereafter, alkaline water was poured into the furnace water to adjust the pH at room temperature to 7.5 to 9.0, and to adjust the temperature to 25%.
By maintaining the temperature at 0 ° C. or more for 100 hours or more (preferably 200 to 400 hours) and forming an oxide film on the water-contacting surface of the components of the primary system of the reactor, it is possible to simultaneously achieve the above two objects. Become.

Here, the reason why the pH is expressed as room temperature-converted pH is that the dissociation coefficient of water into H ions and OH ions depends on the temperature, and the pH value changes depending on the temperature even in water having the same alkalinity. For example, the neutral point at room temperature is pH = 7, but at a reactor water temperature of 288 ° C., the pH is 5.6.
Practically, even in reactor water, pH is measured by cooling the water temperature to almost room temperature by a sampling system, and therefore, control at room temperature-converted pH is more practical.

In addition, since it is particularly important to control the alkali metal ion concentration in the reactor water to improve the corrosion resistance of the nuclear fuel element, during the operation period from when the reactor is stopped to when the generator reaches the rated output operation state. the alkali metal ion concentration in the reactor water is not allowed to exceed ^{2.6 × 10 ~ 7 mol / l} , and the temperature is the reactor water above 250 ° C. 20 to 5
After holding for 0 hour, water containing alkali metal ions was injected into the reactor water so that the concentration of the alkali metal ions in the reactor water became 2.6 × 10 to ^{7 to} 8.7 × 10 to ⁶ mol / l. By keeping the reactor water at a temperature of 250 ° C. or higher for 100 hours or more and forming an oxide film on the surface of the reactor primary component that is in contact with water, the above two objects can be simultaneously achieved. Become.

The injection points of the alkaline water or the water containing alkali metal ions are provided in two parts, a reactor water supply system and a reactor purification system.
One possibility is considered, but during the start-up operation, the feedwater flow rate is small, so it is desirable to inject from the reactor purification system. Also,
It is particularly effective that the alkaline water to be injected contains at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide and aqueous ammonia. When the alkali metal ion-containing water is injected, it is particularly preferable to contain at least one of sodium ions, potassium ions, and lithium ions.

The method for injecting the alkaline water or the alkali metal ion-containing water includes a method of injecting a chemical from outside the system by using a pump, and a method of injecting the primary cooling water from a purifying apparatus using an ion exchange resin in a reactor purifying system. There is a method of mixing.
In other words, a part of the cationic resin to be filled in a part of the ion-exchange resin filtration device consisting of a plurality of towers is preliminarily made into an alkali metal type so that the tower through which water flows during reactor water purification or condensate purification can be used. By switching, the alkali metal ions leak from the cation resin by ion exchange with the cation ions in the water and are injected into the reactor water,
The reactor water pH or alkali metal ion concentration is controlled.

The two-step prefilming operation according to the present invention is based on the difference in oxidation rate between the nuclear fuel element (zirconium alloy) and the piping material (stainless steel, carbon steel, etc.). The inventors have found that the initial oxidation (corrosion) of these materials
After examining the speed in detail, it was found that zirconium alloy and piping materials have different initial film formation processes. That is, FIG. 2 shows a zirconium alloy (Sn; 1..
5 wt%, Fe: 0.17 wt%, Ni: 0.07 wt
%, Cr: 0.1 wt%, Zr: balance, Zircaloy 2
SUS 304) and the initial oxidation behavior of stainless steel (SUS304) were measured at a reactor water temperature of 28 for a typical boiling water reactor.
This is a comparative study based on experiments in 8 ° C. water.

It can be seen that the initial oxidation rate of the zirconium alloy in high-temperature water is much larger at the initial stage (within 50 hours) than that of stainless steel. The initial oxidation (corrosion) pattern of carbon steel also shows a shape almost similar to that of stainless steel. The present invention makes use of the fact that the initial film formation rate of this zirconium alloy is higher than that of piping materials, and that a highly corrosion-resistant film can be formed in a relatively short time.

During the operation period from when the reactor is stopped to when the generator reaches the rated output operation state, the reactor water is converted to room temperature p.
Is H is a small value or an alkali metal ion concentration than 7.5 not exceeding 2.6 × 10 ~ ⁷ mol / l and in a first step the reactor water temperature held 20-50 hours or more 250 ° C., the nuclear fuel elements To form a high corrosion resistant film with little incorporation of impurity ions on the surface in contact with water.

Then, as a second step, alkaline water is injected into the reactor water to adjust the pH at room temperature to a value of 7.5 to 9.0 or to adjust the alkali metal ion concentration to 2.
Water containing alkali metal ions is injected into the reactor water so as to have a concentration of 6 × 10 to ^{7 to} 8.7 × 10 to ⁶ mol / l, and the temperature is set to 250 ° C. or higher for 100 hours or more (200 to 400 hours is desirable). ) By holding, a dense oxide film is formed on the water-contacting surface of the piping system material, so that subsequent incorporation of radioactive ions into the piping system into the coating can be suppressed.

An oxide film of a zirconium alloy that is stable against corrosion is a film having a thickness of about 0.3 to 2 μm and exhibiting a black color. Corrosion increase of zirconium alloy is 15mg
/ Dm2 = 1 μm. In FIG. 2, the corrosion amount of the zirconium alloy is 0.3 μm (4.
It can be seen that it reaches about 5 hours at 288 ° C. (about 50 hours at 250 ° C.). During this time, the impurity ion concentration in the reactor water should be kept at a purity of several ppb or less, which is the level of ultrapure water, so that impurity ions (for example, Na ions) are not taken into the oxide film of the zirconium alloy.

At a room temperature-converted pH of 7.5 or an alkali metal ion concentration of 2.6 × 10 to ⁷ mol / l, when no other impurity anion coexists, about 6 p in the case of Na ion.
This corresponds to about 10 ppb for pb and K ions and about 2 ppb for Li ions. During the formation of the corrosion-resistant black coating on the nuclear fuel element, it is necessary to control the reactor water quality to at least these values.

On the other hand, in order to form an oxide film with a small amount of radioactive ions on the water-contacting surface of a piping material, for example, as described in JP-A-62-95498, p.
H = 8-9 (room temperature conversion) 200 ~ 4
It has been known that immersion for 00 hours forms a dense film with low porosity.

From FIG. 2, it can be seen that the formation rate of the oxide film of stainless steel (same tendency in the case of carbon steel or the like) is lower at the initial rise than that of the zirconium alloy, and is 20 to 50 corresponding to the pre-filming time of the first step. It can be seen that the amount of film formation is small with time. Then, the second step of the present invention, that is, the room temperature converted pH of the primary cooling water is 7.5 to 9.5.
A value of 0 or an alkali metal ion concentration of 2.6 × 10 to ⁷
~ 8.7 × 10 ~ ⁶ mol / l and the temperature is 250
Holding at 100 ° C. or more for 100 hours or more (preferably 200 to 400 hours) has an effect of forming a dense film on the piping system material.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a diagram showing a method of forming a film at the start of operation of the boiling water nuclear power plant. That is, it is a diagram showing a reactor water temperature, a reactor water pH-converted value at room temperature, and a change over time in the generator output.

During the start-up operation period from the reactor shutdown state to the generator being in the rated output operation state, the purifier of the reactor purification system is started to remove impurity ions in the reactor water and convert the reactor water to room temperature. Make the pH almost neutral. At this stage,
The pH slightly varies depending on the components and amounts of impurity ions remaining in the reactor water.

Nuclear heating is started and the reactor water temperature rises to 250 ° C.
Hold for 40 hours after reaching the above. At this stage, a corrosion-resistant black film is formed on the nuclear fuel element (mainly a zirconium alloy) as a pre-filming in the first step.

Next, alkaline water is injected into the furnace water to maintain the pH at room temperature as about 8.5 and keep it for about 300 hours. This stage is the second step of pre-filming, in which a dense oxide film is formed on the piping system material.

During this time, the output of the generator is gradually increased. However, until the generator reaches the rated output, the reactor may be shut down or the output may be reduced to carry out various startup test items. is there. Even in this case, the water quality condition of the first step is experienced for 20 to 50 hours by integration, and the water quality condition of the second step is maintained for 100 hours or more (about 200 to 400 hours) based on the reactor water temperature.

As a method of injecting alkaline water, there is a method of injecting an appropriate amount of a chemical into a reactor purification system while monitoring the pH using a high-pressure pump. As another method of injecting the alkaline water, a part of the cation resin to be charged into the tower A of the ion exchange resin filtration device including the two towers A and B of the reactor purification system is previously alkali metal type (Na or K type). ), And a general H-type is used as the cationic resin to be charged into the tower B. During the pre-filming in the first step, the reactor water is passed through the tower B to purify the water. Immediately before the start of prefilming, by switching the water flow from the tower B to the tower A, Na or K ions are leaked into the reactor water.

FIG. 2 shows a zirconium alloy (Sn: 1.5 wt%, Fe: 0.17 wt%, main material of the nuclear fuel element)
Ni: 0.07 wt%, Cr: 0.1 wt%, Zr: balance, referred to as Zircaloy 2) and stainless steel (SUS304), a typical material of the piping system, were tested for the formation (corrosion) of an oxide film. This is the result of an examination.

Temperature 288 ° C., dissolved oxygen concentration 200 ppb
Each test piece was immersed in an autoclave set as above, and the amount of corrosion was measured. The results of this experiment show that the initial oxidation rate of the zirconium alloy in high-temperature water is much larger at the initial stage (within 50 hours) than that of stainless steel. An oxide film of a zirconium alloy that is stable against corrosion is a film having a thickness of about 0.3 to 2 μm and exhibiting a black color.

The increase in corrosion of the zirconium alloy was 15 mg /
It can be converted to an oxide film thickness of dm2 = 1 μm. The amount of corrosion of the zirconium alloy is 0.3 μm (4.5 mg /
dm2) is reached at 288 ° C. for about 20 hours (25
It takes about 50 hours at 0 ° C.).

On the other hand, the rise of the corrosion rate of stainless steel in the initial stage is smaller than that of the zirconium alloy,
This indicates that a two-step prefilming operation can be performed during the plant startup period.

FIG. 3 shows an example of a primary cooling water system of a boiling water reactor according to the present invention. After the steam generated in the reactor 1 is operated by the turbine 2, the steam is cooled by the condenser 3 to be condensed. The condensate is condensed by the condensate pump 4, the condensate filter 5,
It is sent to the condensate desalter 6 and purified. At this time, in some plants, purification is performed only by the condensate desalter 6. The condensed water is further fed to a feed water heater 8 by a feed water pump 7 and supplied to the reactor 1 as feed water. Part of the reactor water is circulated by the reactor recirculation pump 9, and part of the reactor water is further purified by the reactor water purification device 11 by the reactor purification system pump 10.

An injection system 12 for injecting alkaline water into a plant having such a system is provided downstream of the reactor purification device 11. Further, a sampling system 13 provided upstream of the reactor purification device 11 measures the pH of the reactor water in terms of room temperature or the alkali metal ion concentration in the reactor water. The injection amount of alkaline water is controlled based on the water quality data. When the alkali leaks from the ion exchange resin of the reactor water purification device 11, the reactor purification device 11 also serves as the injection system 12 for injecting the alkaline water.

FIG. 4 shows a reactor cleaning system of a boiling water reactor according to one embodiment of the present invention. Part of the reactor water is introduced from the reactor 1 to the bottom drain and from the reactor recirculation system to the reactor purification system. The reactor water purification device 11 is composed of two towers A and B, and is a filter desalination device using powdered ion exchange resin as a filter aid.

Among them, a part of the cation resin to be charged into the tower A is preliminarily made into an alkali metal type (Na or K type). During pre-filming, the reactor water is passed through the switching tower 14 to the tower B for purification,
Immediately before the start of the pre-filming in the step, the flow of water from the tower B to the tower A is switched by the valve 14, thereby leaking Na or K ions into the reactor water.

When the second step is completed, the flow of water from the tower A to the tower B is switched again by the switching valve 14, and the pH of the reactor water is returned to near neutral. After this series of operations is completed, the ion exchange resin in the tower A is exchanged, and the cation resin in the column is converted into the H type.

FIG. 5 shows an outline of an operation flow at the time of starting the plant showing one embodiment of the present invention. From the reactor stopped state, the reactor recirculation pump is started first, and then the reactor purification system pump is started. If the improved boiling water reactor does not have a reactor recirculation system, an internal pump will be activated instead of the reactor recirculation pump.

Next, the degree of vacuum of the condenser is increased and deaeration operation is performed. After confirming that the room temperature pH of the reactor water is substantially neutral or the alkali metal ion concentration is several ppb or less, a part of the control rod is pulled out and nuclear heating is started. When the reactor water temperature reaches 250 ° C., the first step pre-filming is started. Reactor water temperature is rated temperature (generally 2
After reaching 88 ° C.), start the turbine. When the pre-filming of the first step reaches a predetermined time (20 to 50 hours), the injection of alkaline water is started, and the pre-filming of the second step is started.

During this time, the generator output is gradually increased.
The pre-filming of the second step is performed for 100 hours or more (2
After that, the injection of the alkaline water is stopped, the pH is returned to near neutrality, and the pre-filming in the second step is completed. When the generator reaches the rated output, the startup of the plant is completed.

In the above description, the pre-filming of the first step and the pre-filming of the second step are performed during the start-up operation period from the reactor shutdown state to the generator at the rated output operation state. Has been explained to
It is not always necessary to carry out the operation during the start-up operation period as described above, but it is a matter of course that a similar state may be formed in the reactor stopped state and an oxide film may be formed on the surface of the constituent member.

As described above, according to the method for forming the oxide film and the method for operating the reactor water, the reactor water is converted to a room temperature-converted pH of less than 7.5 and the reactor water is installed in a state where the reactor plant is installed. Reactor water temperature 20-50 when the temperature is 250 ° C
Then, alkaline water was injected into the reactor water to adjust the pH at room temperature to 7.5 to 9.0, and the temperature was maintained at 250 ° C. or higher for 100 hours or longer. At the same time as forming a corrosion-resistant oxide film on the water-contacting surface of the primary component, an oxide film with low uptake of radioactive ions can be formed on the water-contacting surface of the piping system material. This eliminates the need for special treatment for forming a preliminary film, thereby reducing the production cost, and suppressing radiation exposure of workers during periodic inspections of the plant.

[0053]

As described above, according to the present invention, it is possible to easily improve the corrosion resistance of the nuclear fuel element and to suppress the surface dose rate of the primary cooling system piping without using a special device. This type of boiling water nuclear power plant can reduce the radiation exposure of workers during inspections.

[Brief description of the drawings]

FIG. 1 is a diagram showing temporal changes in reactor water temperature, output, and pH of a boiling water reactor showing one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing oxide film growth of a zirconium alloy and stainless steel in high-temperature water.

FIG. 3 is a system diagram of primary cooling water of a boiling water reactor showing one embodiment of the present invention.

FIG. 4 is a system diagram of a reactor purification system of a boiling water reactor showing one embodiment of the present invention.

FIG. 5 is an operation flowchart of a start-up operation of the boiling water reactor showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Turbine, 3 ... Condenser, 4 ... Condenser pump, 5 ... Condenser filter, 6 ... Condensate desalinator, 7 ... Feedwater pump, 8 ... Feedwater heater, 9 ... Re Circulation pump, 10: Reactor purification system pump, 11: Reactor purification device, 12: Alkaline water injection system, 13: Reactor water sampling system, 14: Switching valve.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hidefumi Ibe 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Electric Power & Electric Equipment Development Division (58) Fields surveyed (Int. Cl. ⁷ , DB Name) G21D 1/00 G21D 3/08 G21C 19/30

Claims (11)

(57) [Claims] 1. A method for forming an oxide film on a water-contact surface of a primary component of a nuclear reactor of a boiling water nuclear power plant, wherein the oxide film is formed on a water-contact surface of the component.
The reactor water is maintained at a room temperature-converted pH of less than 7.5 and the reactor water temperature is maintained at 250 ° C. or higher for 20 to 50 hours. Thereafter, alkaline water is injected into the reactor water to adjust the room temperature-converted pH to 7.5. ９9.0, the reactor water temperature was kept at 250 ° C. or higher for 100 hours or more, and an oxide film was formed on the water contact surface of the primary reactor component. A method for forming an oxide film on a water contact surface of a reactor primary system component of a boiling water nuclear power plant. 2. A method for forming an oxide film on a water-contact surface of a primary component of a nuclear reactor of a boiling water nuclear power plant, wherein the oxide film is formed on a water-contact surface of the component.
During a reactor shutdown state in which no nuclear fission reaction occurs, the reactor water was adjusted to a room temperature equivalent pH of less than 7.5 and a reactor water temperature of 2
The temperature is maintained at 50 ° C. or higher for 20 to 50 hours, and then alkaline water is poured into the furnace water to adjust the pH at room temperature to 7.5 to 9.0.
And adjust the reactor water temperature to 250.
C. for more than 100 hours to form an oxide film on the wetted surface of the components of the reactor primary system, wherein the components of the reactor of the boiling water nuclear power plant are wetted with water. A method of forming an oxide film on the surface. 3. A method for forming an oxide film on a water contact surface of a primary component of a nuclear reactor of a boiling water nuclear power plant, wherein the oxide film is formed on a water contact surface of the component.
During the operation period from the reactor shutdown state to the generator being in the rated output operation state, the reactor water is brought into a state in which the room temperature-converted pH is a value smaller than 7.5 and the temperature is 250 ° C. or higher.
After maintaining for 0 to 50 hours, alkaline water is poured into the reactor water to adjust the pH at room temperature to 7.5 to 9.0, and the reactor water temperature is raised to 250 ° C or higher for 100 hours or longer. A method for forming an oxide film on a water-contact surface of a component of a boiling water nuclear power plant, wherein the oxide film is formed on a water-contact surface of a primary reactor component while being held. 4. A method for operating a boiling water nuclear power plant having a boiling water reactor, wherein the reactor water is operated during an operation period from a shutdown state of the reactor to a rated output operation state of the generator. When the pH at room temperature is less than 7.5 and the reactor water temperature is
Hold for 0 to 50 hours, then add alkaline water to the reactor water ,
Alternatively, inject water containing alkali metal ions and convert to room temperature p
H is adjusted to a value of 7.5 to 9.0, and the temperature is maintained at 250 ° C. or higher for 100 hours or more, and the operation is performed while forming an oxide film on the wetted surface of the constituent member of the reactor primary system. A method for operating a boiling water nuclear power plant, comprising: 5. A method for operating a boiling water nuclear power plant including a boiling water reactor, wherein the reactor water is provided during an operation period from a shutdown state of the reactor to a rated output operation state of the generator. alkali metal ion concentration should not exceed 2.6 × 10 ^-7 mol / l, and the temperature is the reactor water and held 20-50 hours or 250 ° C., then, an alkali metal ion concentration in the reactor water of There 2.6 × 10 ^-7 ~8.7 × such that 10 ^-6 mol / l alkaline water to the reactor water or an alkali metal ion
Injecting down-containing water, and the temperature is the reactor water and held for 100 hours or more than 250 ° C., and forming an oxide film on the water contact surface of the primary reactor system components boiling water How to operate a nuclear power plant. 6. Alkaline water injected into the reactor water,
The method for operating a boiling water nuclear power plant according to claim 4 or 5, wherein water containing alkali metal ions is injected from a part of the reactor purification system. 7. When the alkali metal is injected into the reactor water, a part of the cation resin to be filled in a part of a column of the ion exchange resin filtration device comprising a plurality of towers is made into an alkali metal in advance. At the time of water purification or condensate purification, by switching the tower through which water flows, ion exchange with cations in this water causes alkali metal ions to leak from the cation resin and is injected into the reactor water. 6. The method for operating a boiling water nuclear power plant according to claim 4, wherein the concentration of alkali metal ions is controlled. 8. A boiling water nuclear power plant having a boiling water reactor, wherein the reactor water is converted to room temperature during an operation period from a stop state of the reactor to a rated output operation state of the generator. When the pH is less than 7.5 and the temperature is at least
The temperature is kept at 0 ° C. for at least 100 hours and the furnace water is kept at a temperature of 250 ° C. or more and has a pH of 7.5 to 9.5.
Note to inject adjustable alkaline water to a value of 0
A boiling water nuclear power plant characterized in that the inlet device is installed in the reactor purification system . 9. A boiling water nuclear power plant equipped with a boiling water reactor, wherein the reactor water is converted to an alkali metal ion during an operation period from the reactor stop state to a rated output operation state of the generator. When the concentration is lower than 2.6 × 10 ⁻⁷ mol / l and the temperature is 25
The temperature is kept at 0 ° C. or more for 20 to 50 hours, and thereafter, at least 100 hours or more, the temperature of the furnace water is 250 ° C. or more, and the alkali metal ion concentration in the furnace water is 2.6 × 10 ⁻⁷ to 8.
A boiling water nuclear power plant, wherein an alkali metal ion-containing water injection device that can be adjusted to 7 × 10 ⁻⁶ mol / l is installed in a reactor purification system . 10. The reactor according to claim 1, wherein said injector is an element of said reactor cleaning system.
9. The boiling according to claim 8, which is installed downstream of the reactor purification device.
Water nuclear power plant. 11. A reactor purifying apparatus of the reactor purifying system.
Operates also as the injection device, the reactor purification device
Leaks alkali metal ions from the ion exchange resin
By injection of water containing alkali metal ions.
A boiling water nuclear power plant according to claim 9.