WO2015146485A1

WO2015146485A1 - Water jet peening system and water jet peening method

Info

Publication number: WO2015146485A1
Application number: PCT/JP2015/055890
Authority: WO
Inventors: 平井　滋登; 田中　豊; 貴治前口; 展之堀
Original assignee: 三菱重工業株式会社
Priority date: 2014-03-28
Filing date: 2015-02-27
Publication date: 2015-10-01
Also published as: JP2015188992A

Abstract

This water jet peening system (1) is equipped with: a supply device (3) that has a treatment device (2) for reducing the amount of gas dissolved in water and supplies the treated water generated by the treatment device; and a nozzle (5) that has a jetting port that is disposed in a water-filled space and ejects the treated water supplied from the supply device.

Description

Water jet peening apparatus and water jet peening method

The present invention relates to a water jet peening apparatus and a water jet peening method.

If tensile residual stress is present at the welds of the structure, a water jet peening apparatus as disclosed in US Pat.

Japanese Patent Application Publication No. 08-336755

A water jet peening apparatus injects water (high pressure water) from the injection port of the nozzle arrange | positioned in water. The impact force generated when the bubbles contained in the jetted water collapse hits the construction object, thereby reducing the tensile residual stress of the construction object. It is desirable to increase the pressure of the impact pressure so that the tensile residual stress of the construction object is sufficiently reduced.

The aspect of this invention aims at providing the water jet peening apparatus and the water jet peening method which can reduce the tensile residual stress of construction object.

According to a first aspect of the present invention, there is provided a treatment device for reducing the amount of gas dissolved in water, and a supply device for supplying treated water generated by the treatment device, and a treatment device disposed in a space filled with water, And a nozzle having an injection port for injecting the treated water supplied from the supply device.

According to a second aspect of the present invention, there is provided a process of reducing the amount of gas dissolved in water, and supplying the treated water generated in the process to a nozzle disposed in a space filled with water. Water jet peening method including jetting the treated water from the jet port in a state where the jet port of the nozzle and the construction target are opposed in the space.

According to the aspect of the present invention, the tensile residual stress of a construction subject can be reduced.

FIG. 1 is a schematic configuration diagram of an example of a nuclear power plant according to the first embodiment. FIG. 2 is a longitudinal sectional view showing an example of the nuclear reactor vessel according to the first embodiment. FIG. 3 is a cross-sectional view showing an example of the instrumentation nozzle of the nuclear reactor vessel according to the first embodiment. FIG. 4 is a view showing an example of the water jet peening apparatus according to the first embodiment. FIG. 5 is a front view showing an example of the water jet peening apparatus according to the first embodiment. FIG. 6 is a view showing the relationship between the bubble diameter and the vapor pressure in the bubble. FIG. 7 is a view schematically showing an example of the cavitation generator according to the first embodiment. FIG. 8 is a view schematically showing an example of the cavitation generator according to the first embodiment. FIG. 9 is a view schematically showing an example of the cavitation generator according to the first embodiment. FIG. 10 is a view schematically showing an example of the cavitation generator according to the first embodiment. FIG. 11 is a view schematically showing an example of the separation device according to the first embodiment. FIG. 12 is a view showing an example of a water jet peening apparatus according to a second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate. In addition, some components may not be used. In addition, constituent elements in the following embodiments include those that can be easily replaced by persons skilled in the art or those that are substantially the same.

First Embodiment
The first embodiment will be described. FIG. 1 is a schematic configuration view showing an example of a nuclear power plant NP according to the present embodiment. As shown in FIG. 1, the nuclear power plant NP has a reactor system CS1 and a turbine system CS2. In the present embodiment, the nuclear power plant NP includes a pressurized water reactor (PWR: Pressurized Water Reactor), and circulates the high temperature and high pressure primary cooling water (hot water) generated in the reactor system CS1 and the turbine system CS2. A steam generator 103 is provided which performs heat exchange with secondary cooling water to generate secondary cooling water vapor.

The reactor system CS1 includes a reactor vessel 101, a pressurizer 102, and a primary cooling water pump 104. Each of the reactor vessel 101, the pressurizer 102, the steam generator 103, and the primary cooling water pump 104 is stored in the reactor containment vessel 100. The reactor vessel 101 accommodates the core 129 and the fuel assembly 120. The high-temperature and high-pressure primary cooling water (hot water) heated by the reactor vessel 101 and pressurized by the pressurizer 102 is supplied to the steam generator 103. The low temperature primary cooling water heat-exchanged by the steam generator 103 is supplied to the reactor vessel 101.

The turbine system CS2 includes a steam turbine 107 including a high pressure turbine 108 and a low pressure turbine 109, a generator 110 driven by the steam turbine 107 to generate electric power, a moisture separation heater 111, and steam generated by the steam turbine 107. A condenser 112 for cooling and liquefying, a feed water pump 116, a condensate pump 113, a low pressure feed water heater 114, a deaerator 115, and a high pressure feed water heater 117 are provided. The steam turbine 107 operates with the steam supplied from the steam generator 103. The condenser 112 cools the steam back to water using, for example, seawater. The feed water pump 116 operates so that the secondary cooling water from the condenser 112 is supplied to the steam generator 103.

FIG. 2 is a longitudinal sectional view showing the vicinity of the nuclear reactor vessel 101 according to the present embodiment. As shown in FIG. 2, the nuclear reactor vessel 101 has a vessel body 101 a and a vessel lid 101 b. A core 129 is disposed inside the reactor vessel 101. A plurality of fuel assemblies 120 and a plurality of control rods 130 are disposed in the core 129. The control rod drive device 133 controls the output of the nuclear reactor vessel 101 by moving the control rod cluster drive shaft 135 in the vertical direction.

The nuclear reactor vessel 101 has a plurality of instrumentation nozzles 136 arranged to penetrate the lower mirror 101 e of the vessel body 101 a. The upper end portion of the instrumentation nozzle 136 is disposed inside the reactor vessel 101, and the lower end portion of the instrumentation nozzle 136 is disposed outside the reactor vessel 101. An in-core instrumentation guide tube 137 is connected to the upper end of the instrumentation nozzle 136. The conduit tube 138 is connected to the lower end of the instrumentation nozzle 136.

The thimble tube 141 is disposed so as to be insertable to the fuel assembly 120 via the conduit tube 138, the instrumentation nozzle 136, and the in-core instrumentation guide tube 137. The thimble tube 141 has a neutron flux detector capable of measuring the neutron flux.

The control rod drive device 133 can pull out the control rod 130 from the fuel assembly 120 or insert the control rod 130 into the fuel assembly 120 by moving the control rod cluster drive shaft 135. The control rod 130 is pulled out of the fuel assembly 120, and the heat energy generated by nuclear fission in the core 129 heats the primary cooling water of the reactor vessel 101, and the heated primary cooling water is a steam generator. It is supplied to 103. Further, by adjusting the insertion amount of the control rod 130 into the fuel assembly 120, the number of neutrons generated in the core 129 is adjusted. Also, the reactor is shut down by inserting all the control rods 130 into the fuel assembly 120.

FIG. 3 is a cross-sectional view showing an example of the instrumentation nozzle 136 according to the present embodiment. As shown in FIG. 3, the instrumentation nozzle 136 includes an in-core instrumentation cylinder 145 and is disposed in a hole 146 formed in the lower mirror 101 e of the container body 101 a. The instrumentation nozzle 136 is fixed to the inner surface of the lower mirror 101 e by welding. A welding portion (groove welding portion) 147 is provided between the instrumentation nozzle 136 and the lower mirror 101 e.

In the present embodiment, the container main body 101a includes a low alloy steel as a base material and a stainless steel overlay welded on the inner surface of the low alloy steel. The in-core instrumentation cylinder 145 is made of a nickel base alloy. With the in-core instrument cylinder 145 disposed in the hole 146, the vessel body 101a and the in-core instrument cylinder 145 are welded by a material made of a nickel-based alloy. Thereby, a welded portion 147 is generated.

The tensile stress may remain in the instrumentation nozzle 136 (in-core instrumentation cylinder 145), the groove weld portion 147, and the container main body 101a (lower mirror 101e) disposed around the welding by welding, As a result, stress corrosion cracking may occur.

In the present embodiment, the surface (inner surface) of the instrumentation nozzle 136 (in-core instrumentation cylinder 145), the groove weld portion 147, and the lower mirror 101e are constructed by water jet peening. To reduce the tensile residual stress of the construction object, and to suppress the occurrence of stress corrosion cracking.

Water jet peening is a construction method in which water (high pressure water) is jetted from a jet nozzle of a nozzle disposed in water in a state where a construction target for improving stress is immersed in water. An impact pressure is generated by the collapse of air bubbles contained in the water injected from the nozzle. When the impact pressure hits the object to be installed in water, the tensile residual stress in the vicinity of the surface of the object to be applied is relaxed.

That is, when high pressure water containing bubbles is jetted from a nozzle placed in water, a shear force is generated by the shear force generated at the boundary between the stationary water present around the nozzle and the high pressure water jetted from the nozzle, A local pressure drop occurs in the vicinity of the vortex. At this time, bubbles are generated in a region locally lower than the water vapor pressure. Bubbles contained in high pressure water at the time of injection from the nozzle and bubbles generated in the water flow after injection grow under low pressure and contract under pressure recovery. When the pressure is further restored, the bubbles collapse. An impact pressure is generated when the bubble collapses. The process of such bubble generation, growth, contraction and collapse is called cavitation.

An impact pressure is generated by the cavitation, and the impact pressure strikes the object to be construction, whereby at least a part of the object to be construction is plastically deformed. Thereby, the tensile residual stress in the vicinity of the surface of the construction object is relaxed. For example, when tensile stress remains in the vicinity of the surface of the construction object, it is converted into compressive stress by impact pressure being applied to the construction object.

Next, an example of the water jet peening apparatus 1 according to the present embodiment will be described. FIG. 4: is a figure which shows typically an example of the water jet peening apparatus 1 which concerns on this embodiment. FIG. 5 is an enlarged view of a part of FIG. 4.

As shown in FIGS. 4 and 5, the water jet peening apparatus 1 has a processing device 2 for reducing the amount of gas dissolved in water (cooling water) Lr, and supplies the treated water Ls generated by the processing device 2 And an injection nozzle 5 disposed in a space WH filled with the water Lr and having an injection port 4 for injecting the treated water Ls supplied from the supply device 3. The water jet peening apparatus 1 is controlled by a controller 50.

In the present embodiment, in a state where at least a part of the water jet peening apparatus 1 is attached to the instrumentation nozzle 136 (in-core instrumentation cylinder 145), the construction object (surface and bottom of in-core instrumentation cylinder 145) The construction for relieving the tensile residual stress of the surface of the mirror 101e etc. is performed.

As shown in FIG. 4, the nuclear power plant NP has a working floor FR of the reactor building and a space WH provided below the working floor FR and filled with water Lr. The injection nozzle 5 and the reactor vessel 101 are disposed in the space WH.

As shown in FIGS. 4 and 5, the water jet peening apparatus 1 has a construction apparatus 6 disposed in the space WH. The construction apparatus 6 has a main body 61, a connection member 62, and an injection nozzle 5 having an injection port 4 for injecting the treated water Ls.

The connecting member 62 is disposed at the lower part of the main body 61 and protrudes downward from the main body 61. The connection member 62 is connected to the instrumentation nozzle 136 (in-core instrumentation cylinder 145). Thereby, the main body 61 is fixed to the instrumentation nozzle 136.

The injection nozzle 5 is disposed in the space WH, and injects the treated water (high pressure water) LS from the injection port 4 in the water Lr. The injection operation of the injection nozzle 5 is controlled by the control device 50. The injection | spray nozzle 5 is provided in the main body 61 so that the surface of a construction target object may be opposed. In the present embodiment, the surface of the installation target includes at least one of the outer surface of the instrumentation nozzle 136 (in-core instrumentation cylinder 145), the inner surface of the lower mirror 101e, and the surface of the grooved weld portion 147. The treated water Ls is injected from the injection port 4 in a state where the injection port 4 of the injection nozzle 5 disposed in the space WH is opposed to the construction target.

As shown in FIG. 4, at least a part of the supply device 3 is disposed outside the space WH. In the present embodiment, at least a part of the supply device 3 is disposed on the work floor FR. The supply device 3 is generated by the water supply tank 9 in which the water Lr sent from the space WH is stored, the processing device 2 for reducing the amount of gas dissolved in the water Lr sent from the water supply tank 9, and the processing device 2 The high pressure pump 14 for supplying the treated water Ls to the injection nozzle 5 is provided. The high pressure pump 14 is controlled by the controller 50.

Further, the supply device 3 includes a pipe 8 connecting the space WH and the water supply tank 9, and a pump 7 disposed in the pipe 8. The pump 7 is controlled by the controller 50. By the operation of the pump 7, the water Lr in the space WH is supplied to the water supply tank 9 through the pipe 8. The water supply tank 9 stores the water Lr sent from the space WH. The pipe 8 may be provided with a valve mechanism capable of opening and closing the flow path of the pipe 8.

The supply device 3 further includes a pipe 10 connecting the water supply tank 9 and the processing device 2, a flow meter 11 disposed in the pipe 10, and a pump 12 disposed in the pipe 10. The pump 12 is controlled by the controller 50. The flow meter 11 detects the flow rate of the water Lr per unit time in the pipe 10. The detection result of the flow meter 11 is output to the control device 50. By the operation of the pump 12, the water Lr of the water supply tank 9 is supplied to the processing device 2 through the pipe 10. The controller 50 may control the pump 12 based on the detection result of the flow meter 11. The processing device 2 reduces the amount of gas dissolved in the water Lr supplied from the water supply tank 9.

The processing device 2 includes a degassing device capable of reducing the amount of gas dissolved in the water Lr. In the present embodiment, the processing device 2 generates a cavitation in the water Lr to reduce the amount of gas dissolved in the water Lr, and a gas component from the primary treated water Lt generated by the cavitation generator 21. And a separation device 22 that separates to generate treated water Ls.

The supply device 3 further includes a pipe 13 connecting the processing device 2 and the high pressure pump 14, a pipe 16 connecting the high pressure pump 14 and the injection nozzle 5, and a pressure gauge 15 disposed in the pipe 16. There is. The pressure gauge 15 detects the pressure of the treated water Ls in the pipe 13. The detection result of the pressure gauge 15 is output to the control device 50. By the operation of the high pressure pump 14, the treated water Ls generated by the processing device 2 is supplied to the injection nozzle 5 via the pipe 16. The controller 50 may control the high pressure pump 14 based on the detection result of the pressure gauge 15. The injection nozzle 5 injects the treated water Ls from the injection port 4 in a state of being disposed in the space WH (in water).

In order to sufficiently reduce the tensile residual stress of the construction object, it is desirable that the pressure of the impact pressure striking the construction object be high. The amount of gas dissolved in water per unit volume correlates with the impact pressure. As the amount of gas dissolved in water is smaller, higher impact pressure can be obtained. In the present embodiment, the amount of gas dissolved in the water Lr is reduced so as to obtain a high impact pressure.

FIG. 6 is a view showing the relationship between the size of the diameter of a bubble (bubble diameter) present in water and the pressure inside the bubble (the vapor pressure in the bubble). In the graph shown in FIG. 6, the horizontal axis indicates the bubble diameter. The vertical axis shows the vapor pressure in the bubble.

In FIG. 6, line A1 shows the relationship between the bubble diameter and the vapor pressure in the bubble in a virtual state in which no dissolved gas exists in water. Line A2 shows the relationship between the bubble diameter and the vapor pressure in the bubble when the amount of gas dissolved in water per unit volume is small. Line A3 shows the relationship between the bubble diameter and the vapor pressure in the bubble in a state where the amount of gas dissolved in water per unit volume is large.

As mentioned above, cavitation refers to the process of bubble formation, growth, contraction and collapse. When the air bubble shrinks and the air bubble diameter reaches a certain size, the air bubble collapses. Impact pressure is generated at the collapse of the bubble. It is known that the pressure of impact pressure generated in the collapse of the bubble changes depending on the vapor pressure in the bubble at the time of the collapse. The higher the vapor pressure in the bubbles, the higher the impact pressure.

The vapor pressure in the bubble is determined by the balance with the surface tension of the bubble. When the bubble diameter is small, the vapor pressure in the bubble is high. Therefore, in the bubble contraction process in which the bubble diameter gradually decreases, the vapor pressure in the bubble gradually increases.

In the virtual state in which no dissolved gas exists in water, as shown by line A1 in FIG. 6, the vapor pressure in the bubbles gradually increases in the contraction process in which the bubble diameter gradually decreases.

When dissolved gas is present in water, as shown by line A2 and line A3 in FIG. 6, the vapor pressure in the bubbles gradually increases in the contraction process in which the bubble diameter gradually decreases. In the presence of dissolved gas in water, the vapor pressure in the bubbles reaches a peak value at a bubble size and does not increase beyond the peak value.

As shown in FIG. 6, the vapor pressure in bubbles changes in accordance with the amount of gas dissolved in water. When the amount of gas dissolved in water is small, the vapor pressure in the bubbles is high. Therefore, when the amount of gas dissolved in water is small, the impact pressure is high.

Thus, in order to obtain high impact pressure, it is desirable that the amount of gas dissolved in water be small. In order to obtain a high impact pressure, in the present embodiment, the water jet peening apparatus 1 reduces the amount of gas dissolved in the water injected from the injection port 4 of the injection nozzle 5. In the present embodiment, the processing device 2 for reducing the amount of gas dissolved in the water Lr is provided in the supply device 3, and the water (processed water) Ls in which the amount of dissolved gas is reduced is supplied to the injection nozzle 5.

The processing device 2 includes a degassing device capable of reducing the amount of gas dissolved in the water Lr. In the present embodiment, the degassing system of the degassing apparatus is a degassing system using cavitation. The processing device 2 includes a cavitation generator 21. When cavitation occurs in water, the dissolved gas of water forms bubbles with water vapor. Most of the dissolved gas is generally air (nitrogen gas and oxygen gas). Nitrogen gas and oxygen gas dissolve in water to almost saturated amount depending on their partial pressure. When the bubble collapses, the water vapor contained in the bubble is liquefied immediately, but it takes time for the dissolved gas in the bubble to be redissolved in water. That is, in the bubble collapse process, although the water vapor part disappears immediately, the dissolved gas part does not disappear immediately but remains in water. The water jet peening apparatus 1 generates cavitation in the water Lr in the processing apparatus 2 to generate bubbles containing dissolved gas, and generates water (primary treated water) Lt containing the bubbles, and then the primary treated water By removing air bubbles from Lt, the amount of dissolved gas is reduced to generate treated water Ls.

FIG. 7 is a view schematically showing an example of the cavitation generator 21 according to the present embodiment. As shown in FIG. 7, the cavitation generator 21 includes a pipe 24 having a contraction portion 23. The water Lr pressurized by the pump 12 flows through the pipe 24. The flow path of the pipe 24 includes the contraction portion 23. The dimension (cross-sectional area) of the flow path of the contraction portion 23 is smaller than the dimension of the flow path of the pipe 24 on the upstream side of the contraction portion 23 and the dimension of the flow path of the pipe 24 on the downstream side. In the present embodiment, the flow reducing portion 23 is formed by the orifice plate 25A.

The flow velocity of the water Lr supplied from the pump 12 to the flow path of the pipe 24 is high in the contraction portion 23, and the pressure of the water Lr is low in the contraction portion 23. When the pressure of the water Lr is reduced to the saturated vapor pressure by the contraction portion 23, bubbles are generated in the water Lr. Water (primary treated water) Lt containing air bubbles generated in the contraction portion 23 flows downstream from the contraction portion 23. After growth and contraction, some of the bubbles generated in the contraction portion 23 disintegrate immediately downstream of the contraction portion 23. Thus, cavitation including the process of bubble generation, growth, contraction, and collapse is generated by the cavitation generator 21 including the pipe 24 having the contraction portion 23.

Each of FIG. 8, FIG. 9, and FIG. 10 is a schematic view showing an example of the cavitation generator 21. As shown in FIG. As shown in FIG. 8, the flow reducing portion 23 may be formed by the nozzle 25 </ b> B. As shown in FIG. 9, the contraction portion 23 may be formed by the throat 25 </ b> C. As shown in FIG. 10, the flow reducing portion 23 may be formed by the valve 25D. The valve 25D can adjust the dimensions (cross-sectional area, opening degree) of the flow passage of the contraction portion 23.

As described above, although some of the bubbles immediately collapse downstream of the constriction portion 23, some of the bubbles mainly composed of the dissolved gas do not disappear immediately, but remain in the primary treated water Lt. Primary treated water Lt containing air bubbles generated by the cavitation generator 21 is supplied to the separator 22.

FIG. 11 is a view schematically showing an example of the separation device 22 according to the present embodiment. The separation device 22 includes an intermediate tank 26 that stores primary treated water Lt supplied from the cavitation generator 21. When the primary treated water Lt containing air bubbles is supplied to the intermediate tank 26, the air bubbles (gas phase) move near the surface (upper surface) of the primary treated water Lt of the intermediate tank 26 by gravity (difference in specific gravity). Water (liquid phase) moves below the gas phase. Thus, the separation device 22 including the intermediate tank 26 moves the gas phase to the upper part of the internal space of the intermediate tank 26 and transfers the liquid phase to the lower part of the internal space of the intermediate tank 26 to obtain primary treated water. The gas component is separated from Lt, and the primary treated water Lt is divided into a gas phase and a liquid phase. The primary treated water Lt from which the gas component is separated becomes treated water Ls in which the dissolved gas is reduced.

The inlet 13 </ b> R of the pipe 13 connected to the high pressure pump 14 is disposed at the lower part of the internal space of the intermediate tank 26. When the high pressure pump 14 is operated in a state where the inlet 13R of the pipe 13 is disposed at the lower part of the internal space of the intermediate tank 26, the water (treated water) Ls existing in the lower part of the internal space of the intermediate tank 26 is the pipe 13 , And is supplied to the injection nozzle 5 through the pipe 16. Since the gas phase is present in the upper part of the internal space of the intermediate tank 26, it is suppressed from flowing into the pipe 13 through the inlet 13R.

The separation device 22 may have a rotatable propeller 27 disposed in the intermediate tank 26. The gas phase and the liquid phase may be centrifuged by rotating the propeller 27 in a state where the intermediate tank 26 is filled with the primary treated water Lt.

Next, an example of a water jet peening method using the water jet peening apparatus 1 according to the present embodiment will be described.

The construction apparatus 6 including the injection nozzle 5 and the reactor vessel 101 are disposed in the space WH filled with the water Lr. By the operation of the pump 7, the water Lr in the space WH where the construction device 6 and the reactor vessel 101 are disposed is supplied to the water supply tank 9.

The water supply tank 9 stores water Lr from the space WH. When the water Lr is stored in the water supply tank 9, the gas phase moves to the upper part of the water supply tank 9 and the liquid phase moves to the lower part of the water supply tank 9 by gravity action (difference in specific gravity). That is, when the water Lr supplied from the space WH contains a gas component, the water Lr is separated in the gas-liquid separation in the water supply tank 9.

The water Lr of the water supply tank 9 is supplied to the processing device 2 by the operation of the pump 12. Of the gas phase and liquid phase separated in the water supply tank 9, only the liquid phase is supplied to the pump 12 and the supply of the gas phase to the pump 12 is suppressed. Thereby, the malfunction of the pump 12 is suppressed. The water Lr boosted by the pump 12 is supplied to the processing device 2.

The processing device 2 processes the water Lr sent from the space WH. The processing device 2 performs processing to reduce the amount of gas dissolved in the water Lr. The water Lr pressurized by the pump 12 is supplied to the cavitation generator 21 of the processing device 2. The cavitation generator 21 reduces the pressure of the water Lr in the contraction portion 23 to generate cavitation in the water Lr. The occurrence of cavitation generates bubbles containing dissolved gas dissolved in the water Lr. A part of generated bubbles collapses, and a part of bubbles mainly composed of dissolved gas remains. The water Lr containing the remaining air bubbles is sent to the separation device 22 as primary treated water Lt.

The separation device 22 separates the gas component from the primary treated water Lt containing bubbles (gas component) generated by the occurrence of cavitation to generate treated water Ls. As described above, in the present embodiment, the separation device 22 performs gas-liquid separation of the primary treated water Lt containing air bubbles, using gravity action (difference in specific gravity). The amount of gas dissolved in the treated water Ls from which the gas component has been separated is sufficiently small.

The treated water Ls generated by the treatment device 2 is supplied to the injection nozzle 5 disposed in the space WH filled with the water Lr by the operation of the high pressure pump 14. The treated water Ls is injected from the injection port 4 in a mode in which the injection port 4 of the injection nozzle 5 and the construction target are opposed in the space WH.

As described above, the amount of gas dissolved in water correlates with the pressure of impact pressure generated based on the water. The treatment object can be constructed with a high impact pressure by injecting the treated water Ls in which the amount of gas dissolved in the water is sufficiently reduced from the injection port 4 of the injection nozzle 5 facing the object to be constructed . Thereby, the tensile residual stress of a construction subject is reduced.

As described above, according to the present embodiment, focusing on the correlation between the amount of gas dissolved in water and the impact pressure generated when the water is injected from the injection port 4 of the injection nozzle 5, Since the amount of dissolved gas of the water (processed water) Ls to be injected from the injection port 4 of the injection nozzle 5 is reduced, the construction object can be constructed with a high impact pressure. Therefore, the tensile residual stress of the object to be installed can be further reduced, and further converted to compressive residual stress.

In the present embodiment, as a method of reducing the amount of dissolved gas, cavitation is generated in the water Lr by the cavitation generator 21 of the processing device 2, the dissolved gas is bubbled by the cavitation, and the generated bubbles are separated by the separator 22. As a result, the treated water Ls in which the amount of dissolved gas is reduced is generated. Thereby, treated water Ls can be generated at a high processing speed with a simple structure. In the present embodiment, the water Lr in the space WH in which the reactor vessel 101 is disposed is used. The treated water Ls can be generated from the water Lr with a simple structure only by devising the shape of the pipe 24 and providing the contraction portion 23.

Further, in the present embodiment, the water Lr in the space WH is subjected to the dissolved gas amount reduction process and used for water jet peening. That is, the water jet peening process is performed by circulating the water Lr. Thereby, the increase in the water Lr which contacts the reactor vessel 101 is suppressed.

Second Embodiment
The second embodiment will be described. In the following description, the component parts identical or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 12 is a view showing an example of a water jet peening apparatus 1B according to the present embodiment. The water jet peening apparatus 1B has a processing apparatus 2B that reduces the amount of gas dissolved in the water Lr. The processing device 2B includes a degassing device. In the present embodiment, the processing device 2B does not generate primary treated water (Lt).

The degassing system of the processing apparatus (degassing apparatus) 2B may be selected from at least one of a heating boiling degassing system and a vacuum reduced pressure degassing system. Also, as the degassing method, a membrane degassing method using a hollow fiber membrane degassing module may be selected.

The heating and boiling degassing method is a method of reducing the amount of gas dissolved in water by heating and boiling water and reducing the solubility of the gas. In general, the solubility of the gas decreases with increasing temperature. By heating the water Lr, the amount of gas dissolved in the water Lr can be reduced.

The vacuum reduced pressure degassing method is a method of reducing the amount of gas dissolved in water by reducing the pressure of water in vacuum and making the partial pressure of the gas in contact with the water substantially zero. In general, the solubility of a gas is proportional to the partial pressure of the gas in contact with water, and as the partial pressure decreases, the solubility also decreases. By depressurizing the water Lr in a vacuum, the amount of gas dissolved in the water Lr can be reduced.

The membrane degassing method uses a thin film (hollow fiber membrane) in which water permeation is suppressed and gas permeation is permitted, one space of the thin film is filled with a liquid in which gas is dissolved, and the other space of the thin film is depressurized By moving the gas only to the other space.

As the degassing method, at least one of an ultrasonic degassing method and a centrifugal degassing method may be selected.

In the first and second embodiments described above, the object to be subjected to water jet peening is the instrumentation nozzle 136 (in-core instrumentation cylinder 145), the groove weld portion 147, and the lower mirror 101e. I decided to be at least one. The installation object of the water jet peening may be the inlet-side nozzle of the reactor vessel 101 as described with reference to FIGS. 1 and 2 or the outlet-side nozzle of the reactor vessel 101.

Further, the object to be installed is not limited to the members of the reactor vessel 101. For example, piping connecting the pressurizer 102 and the steam generator 103, the pressurizer 102, the steam generator 103 and the primary cooling water pump 104 It may be connected piping and at least a part of the steam generator 103.

Further, the object to be installed is not limited to the structure of the reactor system CS1, but may be the structure of the turbine system CS2. For example, the construction target is a pipe connecting the steam generator 103 and the steam turbine 107, the steam turbine 107, the moisture separation heater 111, the condenser 112, and the condenser 112 and the steam generator 103. It may be at least a part of the piping.

In each of the above-described embodiments, the nuclear power plant NP includes the pressurized water reactor. Nuclear power plant NP may include a boiling water reactor (BWR: Boiling Water Reactor).

The object to be subjected to water jet peening is not limited to the structure of the nuclear power plant NP. Structures of various plants such as a thermal power plant and a geothermal power plant may be objects of water jet peening.

DESCRIPTION OF SYMBOLS 1 water jet peening apparatus 2 processing apparatus 3 supply apparatus 4 injection port 5 injection nozzle 6 construction apparatus 7 pump 8 piping 9 water supply tank 10 piping 11 flow meter 12 pump 13 piping 13 R inlet 14 high pressure pump 15 pressure gauge 16 piping 21 cavitation generation Device 22 Separator 23 Condensing part 24 Piping 25A Orifice plate 25B Nozzle 25C Throat 25D Valve 26 Intermediate tank 27 Propeller 61 Body 62 Connecting member 100 Reactor containment vessel 101 Reactor vessel 101a Vessel body 101b Vessel lid 101e Lower mirror 102 Pressurizer 103 steam generator 104 primary cooling water pump 107 steam turbine 108 high pressure turbine 109 low pressure turbine 110 generator 111 moisture separation heater 112 condenser 113 condensate pump 114 low pressure feed heater 115 deaerator 116 feed pump 117 high pressure feed water heater 120 fuel assembly 129 core 130 control rod 133 control rod drive 135 control rod cluster drive shaft 136 instrumentation nozzle 137 in-core instrumentation guide tube 138 conduit tube 141 thimble tube 145 in-core instrumentation tube 146 Hole 147 Welded section CS1 Reactor system CS2 Turbine system FR Working floor Lr Water Ls Treated water Lt Primary treated water NP Nuclear power plant WH Space

Claims

A supply device that has a treatment device that reduces the amount of gas dissolved in water, and that supplies treated water generated by the treatment device;
A nozzle disposed in a space filled with water and having an injection port for injecting the treated water supplied from the supply device;
A water jet peening device comprising:
The water jet peening apparatus according to claim 1, wherein the processing apparatus includes a cavitation generator that generates cavitation in the water to reduce the amount of gas.
The water jet peening apparatus according to claim 2, wherein the cavitation generator includes a pipe having a contraction portion.
The water jet peening apparatus according to claim 2 or 3, wherein the treatment device includes a separation device that separates a gas component from the primary treatment water generated by the cavitation generator to generate the treatment water.
The water jet peening apparatus according to any one of claims 1 to 4, wherein the processing apparatus processes water sent from the space.
Performing treatment to reduce the amount of gas dissolved in water;
Supplying the treated water generated by the treatment to a nozzle disposed in a space filled with water;
Injecting the treated water from the injection port in a state where the injection port of the nozzle and the construction target are opposed in the space;
Water jet peening method including.
The water jet peening method according to claim 6, wherein the treatment includes generating cavitation in the water.
The water jet peening method according to claim 7, wherein the treatment includes separating a gas component from primary treatment water generated by the generation of the cavitation to generate the treatment water.
The water jet peening method according to any one of claims 6 to 8, wherein the water in the space is treated.