JP5208064B2 - Water jet peening method and apparatus - Google Patents

Description

  The present invention relates to a water jet peening method and an apparatus therefor, and more particularly, to a water jet peening method suitable for improving tensile residual stress of a structure in a nuclear reactor to compressive residual stress by water jet peening. And an apparatus for the same.

  When residual stress exists near the surface of the welded part and heat-affected zone of the components of the nuclear reactor, water jet peening (hereinafter referred to as WJP) is applied to the welded zone and the heat-affected zone. Thus, the tensile residual stress existing in the vicinity of the surface of the component member is improved to the compressive residual stress. WJP is performed by injecting a high-pressure water stream from a nozzle in water in a state in which a component for improving stress is immersed in water. A shock wave is generated by crushing bubbles contained in the jetted water flow. When this shock wave collides with the surface of the constituent member in water, the tensile residual stress near the surface of the constituent member is improved to the compressive residual stress. For this reason, generation | occurrence | production of the stress corrosion crack (SCC) in a structural member is suppressed. The stress improvement method by WJP is described in, for example, Japanese Patent No. 2841963, Japanese Patent No. 3530005, Japanese Patent Laid-Open No. 8-71919, and Japanese Patent Laid-Open No. 6-47668.

  In the construction of WJP on components, methods for confirming the state of construction of WJP are proposed in Japanese Patent Laid-Open Nos. 8-71919 and 6-47668.

  In JP-A-8-71919, WJP is applied to a conduit that is attached to the bottom of a reactor pressure vessel and passes through the bottom. This WJP is applied to the portion of the conduit inside the reactor pressure vessel. A high-pressure water flow is jetted from a nozzle existing in the water near the WJP construction target portion of the conduit, and a shock wave generated by collapsing bubbles contained in the water flow collides with the surface of the conduit in the reactor pressure vessel. Acoustics generated when an AE sensor (acoustic emission) attached to the outer surface of the conduit outside the reactor pressure vessel collides with a portion of the conduit inside the reactor pressure vessel during WJP construction. The signal is detected and an AE signal (sound power) is output. Based on the AE signal, it is confirmed whether or not the residual stress has been sufficiently improved for the conduit subjected to WJP. When the residual stress is not sufficiently improved, the injection condition (injection pressure) of the injected water flow is controlled and the nozzle position is adjusted.

  Japanese Patent Laid-Open No. 6-47668 describes that a piezoelectric ceramic (PZT) sensor is installed on a nozzle in the vicinity of an injection port of a nozzle that injects a high-pressure and high-speed water flow during WJP construction. When a high-pressure water flow is jetted from the nozzle, the PZT sensor detects an impact pulse (cavitation occurrence event) generated in the nozzle. The frequency distribution of the signal output from the PZT sensor based on the detected shock pulse is analyzed by a frequency analyzer. A determination device that inputs the analysis result of the frequency distribution outputs a control signal based on the dominant frequency obtained from the frequency distribution and the comparison result between the amplitude and these set values. The distance between the nozzle and the surface of the WJP work object is adjusted based on the dominant frequency, and the discharge pressure of the pump that supplies water to the nozzle is adjusted based on the amplitude of the dominant frequency.

Japanese Patent No. 2841963 Japanese Patent No. 3530005 JP-A-8-71919 Japanese Patent Laid-Open No. 6-47668

  In the WJP described in Japanese Patent Laid-Open No. 8-71919, an acoustic signal (elastic wave) generated when a shock wave collides with a portion in a reactor pressure vessel of a conduit at the time of WJP construction is generated. It is detected by an AE sensor attached to the outer surface of the conduit on the outside. However, this AE sensor is not only based on the elastic wave generated in the conduit by the shock wave generated by the collapse of bubbles contained in the water flow injected from the nozzle, but also by the impact force when the injected water flow directly collides with the conduit. Elastic waves generated in the conduit are also detected. By the way, the shock wave generated by the collapse of the bubbles greatly contributes to the improvement of the tensile residual stress existing near the surface of the conduit to the compressive residual stress. For this reason, the elastic wave generated by the impact force when the jetted water stream directly collides with the conduit reduces the reliability of the determination result of whether the improvement of the residual stress of the conduit by WJP is sufficient. In addition, when there are a plurality of conduits and WJP is applied to these conduits in order, it is necessary to change the conduit where the AE sensor is installed in accordance with the conduit where the WJP is applied. That is, it takes time and effort to remove the AE sensor from the conduit where the WJP construction has been completed, and then attach the AE sensor to the conduit where the WJP is constructed.

  In the WJP described in Japanese Patent Laid-Open No. 6-47668, since the PZT sensor is attached to the nozzle used for the construction of WJP, the above-mentioned problems caused by the WJP described in Japanese Patent Laid-Open No. 8-71919 are solved. The However, since the PZT sensor is attached to the nozzle, the WJP described in Japanese Patent Laid-Open No. 6-47668 has the following new problem. Since the PZT sensor is provided in the nozzle, this PZT sensor detects an impact pulse based on the flow vibration of high-pressure water containing bubbles passing through a narrow injection port. That is, in the WJP described in Japanese Patent Laid-Open No. 6-47668, the detected impact pulse is strongly influenced by the number of bubbles contained in the high-pressure water flow passing through the injection port.

  As will be described later, when a high-pressure water flow is jetted from the nozzle toward the surface of the WJP construction object, the high-pressure water flow containing a large number of bubbles passes through a narrow injection port formed in the nozzle. Even if it is not crushed, a large flow noise occurs. The PZT sensor provided in the nozzle also detects the flow noise. However, not all bubbles contained in the high-pressure water flow passing through the injection port are necessarily crushed after the water flow is injected from the nozzle. In Japanese Patent Laid-Open No. 6-47668, flow noise generated at a nozzle due to bubbles that do not collapse (bubbles that do not generate shock waves) is also detected. For this reason, even in Japanese Patent Laid-Open No. 6-47668, the effect of improving the residual stress in the WJP construction target cannot be confirmed with high accuracy.

  The objective of this invention is providing the water jet peening method and its apparatus which can confirm the improvement effect of the residual stress in a water jet peening execution target object more accurately.

  A feature of the present invention that achieves the above-described object is that a shock wave generated by collapsing bubbles contained in a water flow jetted into water from a nozzle is applied to a water jet peening object, and the shock wave generated in water is applied to the shock wave. The object is to obtain the frequency of occurrence of the detected shock wave detected by a shock wave detection device arranged in water.

  Shock waves generated during water jet peening construction are detected by a shock wave detector, and the frequency of shock wave generation is obtained. The effect of improving the residual stress can be confirmed with higher accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the improvement effect of the residual stress in a water jet peening construction target object can be confirmed more accurately.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the water jet peening apparatus used for the water jet peening method of Example 1, which is a preferred embodiment of the present invention. It is a flowchart which shows the control procedure at the time of using the water jet peening apparatus shown in FIG. It is explanatory drawing of the example of a display of the output signal of a pressure sensor, and the shock wave generation frequency in the state in which the improvement of the residual stress was performed favorably in Example 1. It is explanatory drawing of the example of a display of the output signal of a pressure sensor, and the shock wave generation frequency in the state in which improvement of a residual stress is insufficient in Example 1. FIG. It is explanatory drawing which shows typically the form of the bubble in the water flow injected from the nozzle. It is a block diagram of the water jet peening apparatus used for the water jet peening method of Example 2 which is another Example of this invention. It is a perspective view of the turntable vicinity of the water jet peening apparatus shown in FIG. It is an enlarged view of the moving apparatus with which the nozzle of the water jet peening apparatus shown in FIG. 6 is provided. It is a block diagram of the water jet peening apparatus used for the water jet peening method of Example 3 which is another Example of this invention. FIG. 10 is an enlarged view of the vicinity of the nozzle shown in FIG. 9. It is a flowchart which shows the control procedure in the water jet peening apparatus shown in FIG. It is explanatory drawing which shows an example of the output signal of two AE sensors in the water jet peening construction in Example 3. It is explanatory drawing of the example of a display of the output signal of a pressure sensor, and the shock wave generation frequency in the state in which the improvement of the residual stress was performed favorably in Example 3. It is explanatory drawing of the example of a display of the output signal of AE sensor and the shock wave generation frequency in the state in which improvement of residual stress is insufficient in Example 3.

  The residual stress of the component due to WJP is not improved by the impact force when the high-pressure water flow injected from the nozzle directly collides with the surface of the component, but is substantially included in the injected water flow. The shock wave generated by the collapse of the bubbles is improved by colliding with the constituent members.

  The improvement of the residual stress of the structural member due to the shock wave generated by the collapse of the bubbles contained in the high-pressure water flow ejected from the nozzle will be described in more detail. A high-pressure water stream ejected from a nozzle disposed in the water contains a large number of bubbles. The bubbles are not only contained in the high-pressure water stream ejected from the nozzle, but are also generated in the water stream ejected from the nozzle into the water. When a high-pressure water stream is ejected from nozzles placed in the water, a large number of vortices are generated by the shear force generated at the boundary between the static water around the nozzles and the water stream ejected from the nozzles. Local pressure fluctuations occur. At this time, bubbles are generated in a region where a negative pressure is locally generated.

  Bubbles contained in the high-pressure water flow at the time of injection from the nozzle and bubbles generated in the water flow after the injection grow under a negative pressure and contract under a positive pressure. When the positive pressure further increases, the generated bubbles are crushed. When a bubble collapses, a very large shock wave is emitted. This process of bubble generation, growth / shrinkage, and crushing is called cavitation. When cavitation occurs, a large shock wave is emitted, and the shock wave collides with the component member, whereby the tensile residual stress near the surface of the component member is improved to the compressive residual stress.

  FIG. 5 schematically shows a state from when bubbles are generated in the jetted water flow until they are crushed. High pressure water 31 is supplied from a pump (not shown) to the nozzle 6 disposed in the water 3. When the high-pressure water 31 is jetted into the water from the jet port 30 of the nozzle 6, a cavitation cloud 32 is generated in which a lot of minute bubbles are generated in the water to form a lump. When one or several bubbles are crushed in the generated plurality of cavitation clouds 32, a shock wave is emitted. Residual stress existing in the vicinity of the surface of the constituent member is improved by repeatedly applying shock waves generated by collapsing bubbles to the surface of the constituent member. When one or several bubbles are crushed and a shock wave is generated in the jetted water flow, a large number of bubbles existing around the bubble are swept away by the shock wave. For this reason, the vortex cavitation 33 in which the group of bubbles to be swept away is formed is formed. Furthermore, a spot 34 that looks as if the bubble has disappeared because the bubble has been swept away is observed. In FIG. 5, 35 is a rough bubble.

  It is a shock wave generated by collapsing bubbles that brings about the stress improving effect of the constituent members. The inventors have determined that the stress improvement effect is not due to the number of bubbles contained in the water stream ejected from the nozzle and the number of bubbles present in the water into which the water stream is ejected, but the number of collapsed bubbles (bubbles Has been found to be confirmed by the occurrence frequency of shock waves. The present invention has been made based on this finding.

  When the WJP construction conditions such as the pressure and flow rate of the water stream ejected from the nozzle and the distance between the nozzle and the surface of the WJP construction object (standoff) are maintained at the respective set values, the jetted water stream is The impact force when directly colliding with the surface of the component member becomes substantially constant. However, since the cavitation generation mechanism in the water flow injected from the nozzle is complicated, the shock wave does not always occur at the expected frequency. Therefore, by monitoring the frequency of occurrence of shock waves, the effect of improving the stress of the constituent members can be confirmed during WJP construction.

  Examples of the present invention will be described below.

  A water jet peening method according to embodiment 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS.

  Before describing the water jet peening method of this embodiment, a water jet peening apparatus (hereinafter referred to as a WJP apparatus) 1 used in this embodiment will be described with reference to FIG. The WJP device 1 includes a nozzle 6, a water supply device 7, a nozzle scanning device 10, a pressure sensor (shock wave detection device) 16, a signal processing device 39, and control devices 22 and 23. The signal processing device 39 includes a discrete 19 and a counter (shock wave counting device) 20. The control device (second control device) 22 is a control device that controls scanning of the nozzle scanning device 10, and the control device (first control device) 23 is a control device that controls the pump 5.

  The nozzle scanning device 10 includes a support column 11, moving devices 12, 14, and 38, a first arm 13, and a second arm 37. The support | pillar 11 is attached to the base 15, and is extended in the up-down direction. A moving device 12 that moves in the vertical direction is movably provided on the column 11. A first arm 13 extending in the X direction in the horizontal direction is installed on the moving device 12. A moving device 14 that moves in the X direction along the first arm 13 is movably installed on the first arm 13. A second arm 37 extending in the Y direction orthogonal to the X direction in the horizontal direction is attached to the moving device 14. A moving device 38 is movably installed on the second arm 37. A support member 36 extending in the vertical direction is attached to the moving device 38. The nozzle 6 is attached to the tip (lower end) of the support member 36. The base 15 is installed on the floor on which the water tank (container) 4 is installed.

  The water supply device 7 includes a high pressure pump 5, a water supply hose 8, and a high pressure hose 9. A water supply hose 8 is attached near the bottom of the water tank 4 and connected to the high-pressure pump 5. A high pressure hose 9 is connected to the high pressure pump 5 and the nozzle 6. The nozzle 6 side of the high-pressure hose 5 is attached to the support member 36.

  The pressure sensor 16 is installed on the support member 17 attached to the moving device 38. The pressure sensor 16 is connected to an amplifier 18 attached to the moving device 38. An amplifier 18 is connected to the disc 19 and the display device 21. A display device 21 is provided on the operation panel 26. A counter 20 is connected to the disc 19 and the display device 21. The control device 22 is connected to the moving devices 12, 14 and 38, and the operation panel 26 is connected to the control devices 22 and 23. A control device 23 is connected to the pump 5, and a pressure gauge 24 and a flow meter 25 attached to the high-pressure hose 9 are connected to the control device 23.

  The water jet peening method of this embodiment performed using the WJP apparatus 1 will be described. In the water jet peening method of the present embodiment, the operation or determination of each step shown in FIG. 2 is performed.

  The water 3 is filled in the water tank 4, and the constituent member 2 that is a WJP construction target object is installed in the water 3 in the water tank 4. This component 2 is a component installed in a plant, for example, a nuclear plant to be constructed. The component 2 may be a component removed from the nuclear plant that has experienced operation during the shutdown of the nuclear plant. In FIG. 1, the component member 2 is schematically shown in a simplified shape.

  The nozzle is moved to the WJP start position (step S1). The operator inputs the position information for starting WJP, that is, the position information of the injection port of the nozzle 6 to the operation panel 26. The position information of the nozzle 6 is indicated by coordinate values in the X direction, the Y direction, and the Z direction (up and down direction). The control device 22 inputs the position information, and drives the moving devices 12, 14, and 38 based on the input position information. The tip of the nozzle 6 is positioned at the coordinate value in the Z direction input by the movement of the moving device 12, the coordinate value in the X direction input by the movement of the moving device 14, and the coordinate value in the Y direction by the movement of the moving device 38. The The distance between the nozzle 6 and the component member 2, that is, the standoff is held at the set distance by the coordinate value in the Z direction. The pressure sensor 16 is disposed in the water 3 on the nozzle 6 side of the component member 2.

  After the nozzle 6 is set at the WJP start position, the high-pressure pump is activated (step S2). When the operator starts the high-pressure pump 5 from the operation panel 26, a pump activation signal is input from the operation panel 26 to the control device 23. At this time, the control device 23 activates the high-pressure pump 5. The high-pressure pump 5 is operated under the initial operating conditions. When the high-pressure pump 5 is activated, the water 3 in the water tank 4 is guided to the high-pressure pump 5 through the water supply hose 8. The control device 23 controls the pressure and flow rate of water discharged from the high-pressure pump 5 based on the measured values of the pressure gauge 24 and the flow meter 25. The water 3 is increased to the initial set pressure by the high pressure pump 5 and supplied to the nozzle 6 through the high pressure hose 9 at the initial flow rate. By supplying the high-pressure water from the high-pressure pump 5, a high-pressure water flow 27 containing bubbles is injected from the nozzle 6 into the water tank 4. The bubbles 28 in the jetted water stream 27 are crushed in water, and a shock wave 29 is generated. The shock wave 29 collides with the component member 2 and is detected by the pressure sensor 16. The shock wave detection signal 40 of the pressure sensor 16 that has detected the shock wave 29 is amplified by the amplifier 18 and then input to the display device 21 and displayed (see FIGS. 3 and 4). The display device 21 also displays information on the shock wave occurrence frequency 42 obtained by the process described later using the shock wave detection signal 40 output from the amplifier 18 (see FIGS. 3 and 4).

  It is determined whether the shock wave occurrence frequency is greater than a first set value of the shock wave occurrence frequency (step S3). The display device 21 displays a first set value 43 of the shock wave occurrence frequency indicated by a one-dot chain line. The operator can easily determine whether the shock wave occurrence frequency 42 is greater than the first set value 43 by looking at the image information displayed on the display device 21.

  If the shock wave frequency 42 is less than or equal to the first set value 43, the operating conditions of the high pressure pump are changed (step S4). The operator operates the operation panel 26 to change the set value of the operating condition of the high-pressure pump 5 (the discharge pressure of the high-pressure pump 5 (or the set value of the discharge flow rate)). That is, the set value of the discharge pressure (or discharge flow rate) is increased. The control device 23 controls the high pressure pump 5 based on the changed operating conditions of the high pressure pump 5. A water flow is injected from the high pressure pump 5 at an increased pressure or the like, and a shock wave frequency 42 is obtained as will be described later.

  When it is determined in step S3 that the shock wave generation frequency is greater than the first set value of the shock wave generation frequency, nozzle scanning is started (step S5). The nozzle 6 is scanned in the set direction. In this scanning, the operator inputs a nozzle scanning start position (hereinafter referred to as a scanning start position), a scanning direction (X direction or Y direction), and a nozzle scanning end position (hereinafter referred to as a scanning end position) to the operation panel 26. Done. The control device 22 inputs the scanning start signal and each information of the scanning direction and the scanning end position from the operation panel 26, and outputs the scanning start signal to the corresponding moving device (the moving device 14 or the moving device 38). When the scanning direction input by the operator to the operation panel 26 is the X direction, the moving device 14 moves along the first arm 13 and moves the nozzle 6 from the scanning start position to the scanning end position in the X direction.

  The scanning start signal output from the operation panel 26 is also input to the control device 23. The control device 23 drives the high-pressure pump 5 based on the scanning start signal. For this reason, while the moving device 14 moves and the nozzle 6 moves in the X direction, a high-pressure water stream is ejected from the nozzle 6. A shock wave 29 generated by collapsing bubbles in the jetted water flow is sequentially applied to the surface of the component member 2 in the scanning direction of the nozzle 6. Since the movement of the nozzle 6 is performed along the welded portion that exists in the component 2 and extends in the X direction and the heat-affected zone thereof, the action of the shock wave 29 causes the vicinity of the surface of the welded portion and the heat-affected zone. Existing tensile residual stress is improved to compressive residual stress.

  The pressure sensor 16 attached to the moving device 38 also moves in the X direction that is the moving direction of the moving device 14 together with the nozzle 6. While moving, the pressure sensor 16 detects the shock wave 29 and outputs a shock wave detection signal 40. The shock wave detection signal 40 is amplified by the amplifier 18 and then input to the disc 19. The disc 19 allows only a shock wave detection signal larger than the set value 41 (see FIGS. 3 and 4) of the shock wave detection signal 40 among the shock wave detection signals 40 to pass. The shock wave detection signal 40 output from the disc 19 is input to the counter 20 and counted by the counter 20. When the shock wave detection signal 40 larger than the set value 41 is input, the disc 19 automatically determines that the bubble 28 is crushed and the shock wave 29 is generated, and passes the shock wave detection signal 40. The count value at the counter 20 of the shock wave detection signal 40 output from the disc 19 is input to the display device 21. The count value per unit time counted by the counter 20 is the shock wave occurrence frequency 42 and is displayed on the display device 21 (see FIGS. 3 and 4).

  When the nozzle reaches the scanning end position, scanning of the nozzle is stopped (step S6). When the nozzle 6 reaches the scanning end position in the X direction described above, the control device 22 outputs a stop signal to the moving device 14. The moving device 14 is stopped by the output of the stop signal, and the scanning of the nozzle 6 in the X direction is completed. An encoder (not shown) for detecting the position of the nozzle 6 in the X direction is provided in the moving device 14, and the position signal of the nozzle 6 in the X direction output from this encoder is input to the control device 22. . When the position signal reaches the scanning end position in the X direction, the control device 22 stops the movement of the moving device 14 by the stop signal.

  It is determined whether the shock wave generation frequency is always greater than the first set value during nozzle scanning (step S7). The operator looks at the image information displayed on the display device 21 and determines whether the shock wave generation frequency 42 is always greater than the first set value 43 (two-dot chain line) during the scanning of the nozzle 6.

  An example of the shock wave detection signal 40 of the pressure sensor 16 and the shock wave generation frequency 42 displayed on the display device 21 when the WJP operation is performed on the surface of the component member 2 in step S5 and the WJP operation is stopped in step S6. Is shown in FIG. The shock wave detection signal 40 is a signal amplified by the amplifier 18. In the display example shown in FIG. 3, the high-pressure pump 5 is stopped between the time T0 and the time T1, and the starting operation of the high-pressure pump 5 is performed between the time T1 and the time T2. After confirming that the shock wave generation frequency 42 was sufficiently larger than the first set value 43, scanning of the nozzle 6 was started. The shock wave generation frequency 42 shown in FIG. 3 is always higher than the first set value 43 during the scanning of the nozzle 6. For this reason, the determination in step S7 is “Yes”, and the high-pressure pump 5 is stopped (step S10). Based on the pump stop command input from the operation panel 26 by the operator, the control device 23 stops the high-pressure pump 5. The construction of WJP along one welded portion formed on the component member 2 is completed.

  By performing the operation of the nozzle 6 in step S5 after the operations of steps S8 and S9, the amplified shock wave detection signal 40 of the pressure sensor 16 and the shock wave generation frequency 42 are displayed on the display device 21 as shown in FIG. Is displayed. In this display example, the momentum of cavitation weakens during the scanning of the nozzle 6, and the shock wave generation frequency 42 falls below the first set value 43 after time T3. In the state shown in FIG. 4, the determination in step S7 is “No”.

  Thereafter, the operating condition of the high pressure pump is changed (step S8). The operator operates the operation panel 26 to change the operating condition of the high-pressure pump 5 (the set value of the discharge pressure or the discharge flow rate of the high-pressure pump 5). Then, the nozzle scanning direction is changed to the reverse direction (step S9). The operator operates the operation panel 26 to set the scan end position in a certain direction (for example, the X direction) set in step S5 as the scan start position, and the scan start position set in step S5 as the scan end position. Set.

  Thereafter, the scan in step S5 is performed. Since the control device 22 inputs the position information set in step S9, the moving device 14 moves in the direction opposite to the previous time. The nozzle 6 injecting the high-pressure water stream is moved from the scanning start position set in step S9 to the scanning end position. When the nozzle 6 reaches the scanning end position, the scanning of the nozzle 6 is stopped (step S6). The determination in step S7 is performed.

  By performing scanning of the nozzle 6 in step S5 after the operations in steps S8 and S9, the amplified shock wave detection signal 40 and the shock wave generation frequency 42 of the pressure sensor 16 as shown in FIG. Is displayed. The shock wave generation frequency 42 shown in FIG. 3 is always higher than the first set value 43 during the scanning of the nozzle 6. Therefore, the determination in step S7 is “Yes”, and the operation of step S10 stops the high-pressure pump 5 as described above (step S10). The construction of WJP along one welded portion formed on the component member 2 is completed.

  When the shock wave occurrence frequency 42 is lower than the first set value 43, the shock wave occurrence frequency 42 is set to the first setting in the welded portion to be subjected to WJP except for a portion where the shock wave occurrence frequency 42 is higher than the first set value 43. What is necessary is just to construct WJP mainly with respect to the location which is less than the value 43. For this reason, in step S9, instead of the scan start position and the scan end position set in step S5, the scan start position and the scan end position are focused on points where the shock wave generation frequency 42 is lower than the first set value 43, respectively. It may be set anew and a WJP re-construction section may be set. At both ends of the WJP re-construction section, a portion where the shock wave generation frequency 42 slightly exceeds the first set value 43 is included. By re-constructing the WJP for the newly set re-construction section, the shock wave generation frequency 42 between them exceeds the first set value 43, and the time required for re-constructing the WJP can be shortened.

  In the component 2, when another welded part exists in the X direction and when a welded part also exists in the Y direction, scanning is sequentially started for each welded part and the heat affected part in step S5. Set the position and the scanning end position, and construct WJP sequentially. When the construction of WJP for all the welds and the like existing in the constituent member 2 is completed, the construction of WJP for the constituent member 2 is completed.

  In the present embodiment, a high pressure water flow is ejected from the nozzle 6 and a shock wave 29 generated by collapsing the bubbles 28 in the water flow is applied to the surface of the component member 2 while the WJP is applied to the component member 2. The sensor 16 detects the shock wave 29. The shock wave 29 is generated from the collapsed bubble 28 and is not generated from the bubble 28 that was not collapsed. Therefore, in the present embodiment, detecting the shock wave 29 with the pressure sensor 16 detects the bubble 28 that generated the shock wave 29, that is, the bubble 28 that contributed to the WJP construction. This embodiment does not detect the bubble 28 that has not been crushed. In this embodiment, the shock wave generation frequency 42 is obtained by counting the detection signal of the shock wave 29 output from the pressure sensor 16. In the present embodiment, the shock wave generation frequency 42 is obtained by detecting the shock wave 29 that is generated when the bubbles are crushed and contributes to the improvement of the residual stress. Therefore, based on the shock wave generation frequency 42, the residual stress of the WJP work object is determined. Can be confirmed with higher accuracy.

  In this embodiment, the pressure sensor 16 is attached not to the nozzle 6 but to the support member 36 provided in the moving device 38. For this reason, the detection of the impact pulse based on the flow vibration of the high-pressure water containing the bubbles passing through the injection port of the nozzle 6 by the pressure sensor 16 is remarkably suppressed. This also contributes to the improvement in the accuracy of confirmation of the effect of improving the residual stress in the WJP construction object.

  In particular, since the shock wave occurrence frequency is displayed on the display device 21, the operator can easily grasp the effect of improving the residual stress in the WJP construction object.

  In the present embodiment, the effect of improving the residual stress is confirmed based on the frequency of occurrence of the shock wave, so that a portion where the effect of improving the residual stress is insufficient in the WJP construction object can be confirmed with high accuracy. In addition, when there is a portion where the effect of improving the residual stress is insufficient, the WJP can be reconstructed in a shorter time using the WJP device 1 as a target.

  Since the present embodiment can accurately confirm the effect of improving the residual stress in the WJP work target based on the frequency of occurrence of shock waves, the margin for evaluation for confirming the effect of improving the residual stress can be reduced. . For this reason, the capacity | capacitance of the high pressure pump 5 which supplies high pressure water to the nozzle 6 can be made small by the part which can make the margin small.

  When the capacity of the high-pressure pump 5 is not reduced, the moving speed of the nozzle 6 can be increased as much as the margin can be reduced. For this reason, the construction time of WJP can be further shortened.

  A water jet peening method according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG. The water jet peening method according to the present embodiment is performed on, for example, an in-reactor structure installed in a reactor pressure vessel of a boiling water nuclear plant. This in-furnace structure is, for example, a core shroud.

  The structure near the nuclear reactor of the boiling water nuclear power plant will be described with reference to FIG. A nuclear reactor 50 of a boiling water nuclear power plant includes a reactor pressure vessel 51, a core shroud 52, a core support plate 54, an upper lattice plate 55, and a jet pump 56. The core shroud 52, the core support plate 54, the upper lattice plate 55, and the jet pump 56 are installed in the reactor pressure vessel 51. In the core shroud 52 surrounding the core, a core support plate 54 located at the lower end of the core is installed, and an upper lattice plate 55 located at the upper end of the core is installed. A plurality of jet pumps 56 are disposed in an annular downcomer 57 formed between the reactor pressure vessel 51 and the core shroud 52.

  The WJP apparatus 1A used in the water jet peening method of the present embodiment has a configuration in which the nozzle scanning apparatus 10 and the signal processing apparatus 39 are replaced with the nozzle scanning apparatus 10A and the signal processing apparatus 39A in the WJP apparatus 1 used in the first embodiment. Have. Other configurations of the WJP apparatus 1A are the same as those of the WJP apparatus 1.

  The nozzle scanning device 10A will be described. As shown in FIGS. 6, 7, and 8, the nozzle scanning device 10 </ b> A includes moving devices 58 </ b> A and 58 </ b> B, a post member 62, an elevating body 63, and a turntable 65. The turntable 65 is rotatably installed on an annular guide rail 66 installed on the upper surface of the upper flange 53 of the core shroud 52. Although not shown, the turntable 65 is provided with a plurality of wheels that contact the upper surface of the guide rail 66. A motor (not shown) that rotates at least one wheel (not shown) is provided on the turntable 65. Moving devices 58A and 58B are installed on the turntable 65.

  The moving devices 58A and 58B having the same configuration will be described by taking the moving device 58A as an example. As shown in FIG. 8, the moving device 58 </ b> A includes a device main body 59, two arms 60, and a ball screw 80. Two arms 60 pass through the casing of the apparatus main body 59 and are slidably attached to the casing. Both ends of the two arms 60 are connected by connecting members 61A and 61B. A ball screw 80 penetrating the casing of the apparatus main body 59 is rotatably attached to the connecting members 61A and 61B. Although not shown, a motor is installed in the casing of the apparatus main body 59, and a gear (not shown) attached to the rotation shaft of the motor meshes with a gear (not shown) that meshes with the ball screw 80. Yes. These gears are rotated by driving the motor, and the ball screw 80 moves in the radial direction of the reactor pressure vessel 51. A post member 62 extending in the axial direction of the reactor pressure vessel 51 is attached to the connecting member 61B. The elevating body 63 is attached to the post member 62 so that it can move along the post member 62. A motor 64 that moves the elevating body 63 up and down is provided at the upper end of the post member 62.

  The nozzle 6, the pressure sensor 16, and the monitoring camera 67 are installed on the lifting body 63.

  In the present embodiment, WJP is applied to the outer surface of the upper end portion of the core shroud 52. In this embodiment, the core shroud 52 is a WJP construction target object. After the operation of the boiling water nuclear power plant is stopped, the upper cover of the reactor pressure vessel 51 is removed, the steam dryer and the steam separator installed in the reactor pressure vessel 51 are removed, and the reactor pressure is removed. It is carried out of the container 51. These are carried out using an overhead crane (not shown) in the reactor building in which the reactor pressure vessel 51 is installed. When these removal and removal operations are performed, the water 3 is filled in the reactor well 68 positioned immediately above the reactor pressure vessel 51.

  The guide rail 66 is transferred to the upper flange 53 using the overhead crane and installed on the upper flange 53. The turntable 65 on which the moving devices 58 </ b> A and 58 </ b> B are installed is transported by the overhead crane and installed on the guide rail 66. A post member 62 to which a lifting body 63 having a nozzle 6, a pressure sensor 16, and a monitoring camera 67 is attached is installed in each of the moving devices 58 </ b> A and 58 </ b> B before the turntable 65 is transported. When the turntable 65 is installed on the guide rail 66, the post member 62 provided on each of the moving devices 58 </ b> A and 58 </ b> B is disposed in the downcomer 57.

  The high-pressure pump 5 and the operation panel 26 are placed on the operation floor 69 in the reactor building, and the signal processing device 39A, the control devices 22 and 23, and the display device 21 are provided on the operation panel 26. The signal processing device 39A includes an amplifier 18, a disc 19, and a counter 20. The operation floor 69 surrounds the reactor well 68. Two high-pressure hoses 9 connected to the high-pressure pump 5 are respectively attached to the moving devices 58A and 58B, and are separately connected to the nozzle 6 provided in the moving device 58A and the nozzle 6 provided in the moving device 58B. Yes. A signal line 70 connected to the pressure sensor 16 provided in the moving device 58A is connected to the amplifier 18. An amplifier 18 is connected to the disc 19 and the display device 21. The signal line 70 connected to the pressure sensor 16 provided in the moving device 58B is also connected to the display device 21 and the disc 19 of another signal processing device 39A via another amplifier 18. The counters 20 of the two signal processing devices 39A are connected to the display device 21. A control signal line 71 connected to the control device 22 is provided on the motor 64 provided in each of the moving devices 58A and 58B, the motor provided in the casing of the device main body 59, and the turntable 65. Are connected to motors that rotate the wheels. Each motor is provided with an encoder (not shown), and each encoder detects a moving distance of a member moved by the motor, that is, a position after the member moves.

  In the water jet peening method of the present embodiment, each operation or determination shown in FIG. In the core shroud 52, there are a plurality of welds extending in the axial direction in the circumferential direction of the core shroud 52, and there are a plurality of welds extending in the circumferential direction in the axial direction of the core shroud 52. In the present embodiment, WJP is applied along these welds.

  For example, it is assumed that WJP is applied along a certain welded portion extending in the circumferential direction of the core shroud 52. In step S1, each nozzle 6 provided in the moving devices 58A and 58B is moved to the WJP start position. The operator inputs positional information of the core shroud 52 in the circumferential direction, the axial direction, and the radial direction from the operation panel 26. The control device 22 drives three motors provided in the WJP device 1A based on the position information, and positions the nozzle 6 at a scanning start position designated so as to face the one welded portion. The ball screw 80 is rotated by driving a motor provided in each device main body 59 of each of the moving devices 58A and 58B, and each post member 62 moves in the radial direction of the core shroud 52. By this movement of the post member 62, the distance between the nozzle 6 and the outer surface which is the WJP construction surface of the core shroud 52, that is, the standoff is set to a set value. By driving the motor 64, the elevating body 63 moves along the post member 62 in the axial direction of the core shroud 52, and the nozzle 6 is positioned at a predetermined position in the axial direction of the core shroud 52.

  Thereafter, the operation of step S2 is executed. The high-pressure pump 5 is driven, and the pressurized high-pressure water is supplied through the high-pressure hose 9 to each nozzle 6 provided in the moving devices 58A and 58B. High-pressure water is injected from each nozzle 6 toward the outer surface of the core shroud 52 in the vicinity of the installed upper lattice plate 54 at an initial pressure and an initial flow rate. A shock wave generated by collapsing bubbles contained in the jetted water flow is detected by the pressure sensor 16. The shock wave occurrence frequency is obtained by the counter 20 based on the detection signal output from the pressure sensor 16 by the detection of the shock wave. Based on this shock wave occurrence frequency, the determination in step S3 is performed. If this determination is “No”, the operation condition of the high-pressure pump is changed in step S4, and the determination in step S3 is performed again. When the determination in step S4 is “Yes”, scanning of the nozzle 6 in step S5 is started. Each nozzle 6 provided in the moving devices 58A and 58B moves along a certain welded portion extending in the circumferential direction of the core shroud 52 while injecting a high-pressure water flow. This movement is performed by turning the turntable 65 along the guide rail 66. WJP for the welded portion and the heat affected zone is applied. In this embodiment, since the two nozzles 6 are positioned in the opposite directions of 180 °, when each nozzle 6 moves in the circumferential direction, for example, 190 °, the operation in step S6 is performed, and the scanning of the nozzles 6 is performed. Stopped.

  The determination in step S7 is made based on the shock wave occurrence frequency displayed on the display device 21. When this determination is “Yes”, the operation of the high-pressure pump 5 is stopped (step S10). Construction of WJP on one welded portion extending in the circumferential direction of the core shroud 52 is stopped. When the determination in step S10 is “No”, the operations in steps S8 and S9 are performed, and the WJP is re-constructed for the WJP re-construction section set in the corresponding welded portion. When the determination in step S10 after the re-working is “Yes”, the operation of the high-pressure pump 5 is stopped.

  The WJP is similarly applied to another welded portion formed in the core shroud 52 in the circumferential direction and a welded portion formed in the core shroud 52 in the axial direction.

  Also in this embodiment, each effect produced in the first embodiment can be obtained.

  A water jet peening method according to a third embodiment which is another embodiment of the present invention will be described with reference to FIGS.

  A WJP apparatus 1B used in this embodiment will be described with reference to FIG. The WJP apparatus 1B has a configuration in which the signal processing apparatus 39 is replaced with the signal processing apparatus 39B in the WJP apparatus 1A used in the second embodiment, and AE sensors (shock wave detection apparatuses) 72 and 72A are used instead of the pressure sensor 16. Other configurations of the WJP apparatus 1B are the same as those of the WJP apparatus 1A. The configuration of the WJP apparatus 1B will be described with respect to parts different from the WJP apparatus 1A.

The support member 36 </ b> A extends in the axial direction of the nozzle 6 installed on the elevating body 63 and is attached to the elevating body 63. Shock wave conversion plates 73 and 73A are installed on the support member 36A at different positions in the axial direction of the nozzle 6 (see FIG. 10). Shock wave conversion plate 73 is positioned on the distal end side of the nozzle 6 than the shock wave conversion plate 73A, the shock wave conversion plate 73A are separated by a distance L _AE from the shock wave conversion plate 73. The AE sensor 72 is installed on the shock wave conversion plate 73, and the AE sensor 72A is installed on the shock wave conversion plate 73A. The shock wave conversion plates 73 and 73A are located closer to the tip of the nozzle 6 than the installed AE sensors.

  The signal processing device 39B includes an analog / digital converter (A / D converter) 74, a detection time determination device 75, a time difference determination device (shock wave determination device) 76, a shock wave counting device 77, and a storage device 78 (see FIG. 9). ). The A / D converter 74 is connected to the detection time determination device 75, and the detection time determination device 75 is connected to the time difference determination device 76. A time difference determination device 76 is connected to the shock wave counting device 77. A storage device 78 is connected to the detection time determination device 75, the time difference determination device 76, the shock wave counting device 77, and the control devices 22 and 23. The signal processing device 39B is represented by a hard image in FIG. 9, but is programmed in a personal computer. The signal processing device 39B is attached to the operation panel 26 installed on the operation floor surrounding the reactor well. The high-pressure pump 5 is installed on the operation floor.

  The amplifiers 18 and 18A are attached to the lifting body 63. The amplifier 18 is connected to the AE sensor 72 and the A / D converter 74. The amplifier 18A is connected to the AE sensor 72A and the A / D converter 74. The amplifiers 18 and 18A are provided with a waterproof measure.

  The storage device 28 has a WJP scanning start position and a scanning end position for the welded portion formed on the WJP work object, a set value of the shock wave detection signal, a first set value 43 and a second set value 79 of the shock wave occurrence frequency (see FIG. 13), and information on the normal range (lower limit value and upper limit value) of the time difference in shock wave detection between the AE sensor 72 and the AE sensor 72A is stored. The second set value 79 is larger than the first set value 43.

  The water jet peening method of the present embodiment will be specifically described with reference to FIGS. The WJP execution object in the present embodiment is a core shroud 52. After the operation of the boiling water nuclear power plant is stopped, the nozzle scanning device 10A is placed on the upper flange 66 of the core shroud 52 in the reactor pressure vessel 51 filled with water 3 as described in the second embodiment. Installed. At this time, the respective post members 62 to which the elevating body 63 provided with the nozzles 6 of the moving devices 58A and 58B move are arranged between the reactor pressure vessel 51 and the core shroud 52.

  In this embodiment, steps S1, S3, S5, S6 and S11 to S14 are executed by the control device 22, and steps S2, S4, S14 and S10 are executed by the control device 23.

  Before the control in step S1 is performed, the operator sets the scan start position and the scan end position of the plurality of welds extending in the axial direction and the plurality of welds extending in the circumferential direction formed in the core shroud 52. Input to the operation panel 26 in advance. Each information of the input scanning start position and scanning end position is stored in the storage device 78 via the control device 22.

  For example, it is assumed that WJP is applied along a certain weld extending in the circumferential direction of the core shroud 52. In the present embodiment, similarly to the second embodiment formed in the core shroud 52, the control in step S1 is performed by the control device 22, and the control in step S2 is performed by the control device 23. In the control of step S <b> 1, the control device 22 inputs information on the scan start position related to one welded portion extending in the circumferential direction, which is stored in the storage device 78.

  After the control in steps S1 and S2 is finished, it is determined whether the shock wave generation frequency is greater than the first set value of the shock wave generation frequency (step S3). In this embodiment, the shock wave occurrence frequency is obtained by the shock wave counting device 77 as will be described later. The control device 22 determines whether the shock wave generation frequency input from the shock wave counting device 77 is greater than the second set value 79 (see FIG. 13) of the shock wave generation frequency input from the storage device 78. When the determination result is “No”, the control device 22 outputs an operation condition change signal to the control device 23. Thereafter, the operating conditions of the high pressure pump are changed (step S4). When the operation condition change signal is input, the control device 23 changes the operation condition of the high pressure pump 5 (the set value of the discharge pressure or the discharge flow rate of the high pressure pump 5). The control device 23 controls the high pressure pump 5 based on the changed operating condition. The high pressure pump 5 discharges water whose pressure has been increased. A water flow 27 is injected from the high pressure pump 5 at an increased pressure or the like, and a shock wave generation frequency 42 is obtained as will be described later.

  When the control device 22 determines “Yes” based on the shock wave occurrence frequency input in the determination of step S3, the control of step S5 is executed. When executing the control of step S <b> 5, the control device 22 inputs from the storage device 78 information on the scanning end position relating to one weld formed in the core shroud 52. The nozzle 6 has already been positioned at the scanning start position, and the control device 22 outputs a scanning start signal to a motor provided in the WJP device 1A that rotates the wheels of the turntable 65. The motor is driven to turn the turntable 65, and the nozzle 6 to which the high-pressure water stream 27 is sprayed moves to the scanning end position along the welded portion extending in the circumferential direction.

  The water stream 27 is jetted from the nozzle 6 toward the outer surface of the core shroud 52. A part of the plurality of bubbles 28 included in the jetted water flow is crushed and a shock wave 29 is generated. These shock waves 29 collide with the corresponding welded portion formed in the core shroud 52 and the heat affected zone. For this reason, the tensile residual stress existing in the vicinity of the welded portion and the surface of the heat affected zone is improved to the compressive residual stress. The AE sensors 72 and 72A moving in the circumferential direction together with the nozzle 6 detect the shock waves 29 propagating through the water 3 and output a plurality of shock wave detection signals. Specifically, the AE sensor 72 detects a sound wave generated in the shock wave conversion plate 73 due to the collision of the shock wave 29, and the AE sensor 72A detects a sound wave generated in the shock wave conversion plate 73A due to the collision of the shock wave 29. The shock wave detection signals output from the AE sensors 72 and 72A are amplified by the amplifiers 18 and 18A and input to the A / D converter 74. The A / D converter 74 converts each shock wave detection signal into a digital signal and outputs it to the display device 21 and the detection time determination device 75.

  When a shock wave generated by collapse of one bubble is received by the AE sensors 72 and 72A, a time difference occurs in the detection of the shock wave in these AE sensors. The reason for this will be described with reference to FIG. When the bubble 28a is crushed and a shock wave is generated, the propagation path of the shock wave to the AE sensor 72 is 84a, and the propagation path of the shock wave to the AE sensor 72A is indicated by 85a. Since the shock wave propagates through the water 3 at the speed of sound (≈1500 m / s), the difference in the detection time of the shock wave between the AE sensor 72 and the AE sensor 72A is the length of the propagation path 84a and the propagation path 85a. Occurs based on the difference.

Here, it is assumed that the range in which the bubbles are crushed is the range indicated by the alternate long and short dash line 83 (see FIG. 10). Since the AE sensor 72 and the AE sensor 72A are separated by a distance _{L AE,} at different positions within a range inside than one-dot chain line 83, a plurality of bubbles, e.g., bubbles 28a, 28b, 28c are crushed shock wave is generated respectively Even if it does, a difference arises in the detection time of each shock wave in AE sensor 72 and AE sensor 72A. The propagation paths of the shock waves generated by the collapse of the bubbles 28b and 28c to the AE sensor 72 are 84b and 84c, and the propagation paths of these shock waves to the AE sensor 72A are 85b and 85c. Since each shock wave propagates in water at the speed of sound, the difference between detection times thereof falls within a predetermined range. On the other hand, electromagnetic noise propagates at a speed close to the speed of light. For this reason, when the AE sensors 72 and 72A detect electromagnetic noise, these AE sensors simultaneously output an output signal for the detected electromagnetic noise. Therefore, when there is no difference between the detection times of the AE sensors 72 and 72A, it is determined that the output signal is due to electromagnetic noise. The difference between the detection time of the AE sensor 72,72A is, the shock wave is almost equal to the time required to propagate the distance L _AE between these AE sensor, a shock wave when it is within range of a preset normal time difference It is determined that it has been received.

  FIG. 12 shows an example of each shock wave detection signal output from the AE sensor 72 (first shock wave detection device) and the AE sensor 72A (second shock wave detection device) during WJP construction. In FIG. 12, the vertical axis represents the intensity of the shock wave detection signal, and the horizontal axis represents time. 12 expands the time on the horizontal axis as compared to FIGS. 13 and 14 described later. FIG. 12 shows a state in which each shock wave detection signal output from the A / D converter 74 to the display device 21 is displayed on the display device 21.

  The detection time determination device 75 selects a shock wave detection signal whose strength is greater than the set value 41 of the shock wave detection signal input from the storage device 78 among the shock wave detection signals input from the A / D converter 74. The detection time determination device 75 determines the detection time of the selected shock wave detection signal. In FIG. 12, the shock wave detection signals 81a to 81j are selected from the shock wave detection signals output from the AE sensor 72, and the shock wave detection signals 82a to 82j are output from the AE sensor 72A. Is selected from. Each selected shock wave detection signal is output from the detection time determination device 75 to the time difference determination device 76 together with the determined time information.

  The time difference determination device 76 calculates the difference between the detection time of the shock wave detection signal from the AE sensor 72 and the detection time of the shock wave detection signal from the AE sensor 72A, which has detected the shock wave generated when one bubble is crushed. The time difference determination device 76 determines whether the calculated time difference is within the normal range (lower limit value and upper limit value) of the time difference input from the storage device 78, and when the calculated time difference is within the normal range, the shock wave Is determined to have been detected. For example, in FIG. 12, since the shock wave detection signal 81a and the shock wave detection signal 82a, and the shock wave detection signal 81b and the shock wave detection signal 82b exist within the normal range of the time difference, it is determined that they are generated from the same shock wave. However, since the shock wave detection signal 81e and the shock wave detection signal 82e, and the shock wave detection signal 81g and the shock wave detection signal 82g are detected almost at the same time, it is determined not to have occurred due to the detection of the shock wave but to be noise. When the time difference determination device 76 determines that a shock wave has been detected, it outputs a shock wave determination signal.

  The shock wave counting device 77 counts the input shock wave determination signal. The count of the shock wave determination signal corresponds to the count of the shock wave. The count value of the shock wave determination signal per unit time is the shock wave generation frequency. The obtained shock wave occurrence frequency is stored in the storage device 78 and also input to the control device 22. The shock wave occurrence frequencies stored in the storage device 78 are sequentially displayed on the display device 21. The display device 21 includes a shock wave detection signal 40 from the AE sensor 72, a shock wave detection signal 40A from the AE sensor 72A, a shock wave detection signal setting value 41, a shock wave generation frequency 42, and a first set value 43 of the shock wave generation frequency. The second set value 79 is displayed (see FIGS. 13 and 14).

  It is determined whether the shock wave occurrence frequency is greater than the second set value of the shock wave occurrence frequency (step 11). The control device 22 determines whether the input shock wave occurrence frequency is greater than the second set value 79 input from the storage device 78. This determination is performed while the nozzle 6 moves from the scan start position toward the scan end position along one circumferential weld formed in the core shroud 52. When the determination in step S11 performed by the control device 22 is always “Yes”, the nozzle scanning ends when the nozzle reaches the scanning end position (step S6). When the control device 22 determines that the nozzle 6 has reached the scanning end position of one welded portion extending in the circumferential direction based on an output signal from an encoder provided in a motor that turns the turntable 65, the motor A drive stop signal is outputted to stop the turntable 65 from turning.

  The high pressure pump is stopped (step S10). The drive stop signal output from the control device 22 is input to the control device 23. The control device 23 stops the high-pressure pump 5 when the drive stop signal is input. Thereby, the WJP construction along one welded portion extending in the circumferential direction of the core shroud 52 is completed. By this WJP construction, the tensile residual stress existing in the vicinity of the surface of the welded part and its heat-affected zone is improved to a compressive residual stress. This can be confirmed by the fact that the shock wave occurrence frequency is larger than the second set value 79 which is larger than the first set value 43 in the entire circumferential length of the welded portion. If there is a location where the shock wave frequency is lower than the first set value 43, it means that the effect of improving the tensile residual stress is insufficient at that location.

  When the determination result of step S11 in the control device 22 is “No”, it is determined whether the shock wave occurrence frequency is smaller than the first set value of the shock wave occurrence frequency (step S12). The control device 22 determines whether the input shock wave occurrence frequency is smaller than the first set value 43 input from the storage device 78. When this determination is “No”, the operating condition of the high-pressure pump is changed (step S14). The control device 22 outputs an operation condition change signal for the high-pressure pump 5 to the control device 23 when the determination result of step S12 is “No”. When the operation condition change signal is input, the control device 23 changes the operation condition of the high-pressure pump 5 (the discharge pressure setting value or the discharge flow rate setting value of the high-pressure pump 5). That is, the control device 23 increases the set value of the discharge pressure (or the set value of the discharge flow rate) by the set predetermined width. The control device 23 controls the high pressure pump 5 based on the changed operating condition. By this control, the pressure of the water flow boosted by the high pressure pump 5 and injected from the nozzle 6 increases, and the effect of improving the tensile residual stress in the vicinity of the surface of the weld is increased by the shock wave (see FIG. 13). The change of the operating condition of the high-pressure pump 5 and the control of the high-pressure pump 5 based on the changed operating condition are performed while scanning the nozzle 6. A state in which the shock wave generation frequency is smaller than the second set value 79 and greater than the first set value 43 indicates that the cavitation momentum is weakening. However, as long as the shock wave generation frequency does not become smaller than the first set value, a predetermined improvement effect of the residual stress of the core shroud 52 is produced.

  When the determination in step S12 is “Yes”, the nozzle is moved to the scanning start position (step S13). When the determination in step S12 is “Yes”, the shock wave generation frequency is lower than the first set value 43 as shown in FIG. When the determination in step S12 is “Yes”, the control device 22 moves the nozzle 6 to the scanning start position. In this movement, the control device 22 sets the scanning start position for returning the nozzle 6 to a position at a time slightly before the position of the nozzle 6 when the shock wave generation frequency reaches the first set value 43. The movement of the nozzle 6 is performed when the control device 22 outputs a drive command to a drive device (for example, a motor) for turning the turntable 65 which is one of the moving devices of the nozzle scanning device 10A. Is returned to the set scan start position. The drive command output from the control device 22 is input to the control device 23. At this time, the control device 23 changes the operating condition of the high-pressure pump 5 as in step S14 described above, and controls the high-pressure pump 5 based on the changed operating condition.

  The control device 23 controls the high-pressure pump 5 based on the changed operating condition, and then outputs a nozzle scanning start signal to the control device 22. The control device 22 moves the corresponding moving device, for example, the turntable 65, of the nozzle scanning device 10A in response to the input of the nozzle scanning start signal. The nozzle 6 that is injecting a high-pressure water stream starts to move from the scanning start position, and the WJP operation on the welded portion of the core shroud 52 is resumed. When the control device 22 determines “Yes” in step S11, performs the control in step S6, and the control device 23 performs the control in step S10, the construction of WJP ends.

  In the present embodiment, each effect produced in the first embodiment can be obtained. Since the present embodiment has two AE sensors and obtains the difference in detection time of the shock wave detection signals output from these AE sensors, when performing WJP in a high noise environment, noise The effect of improving residual stress can be monitored without being affected.

  In this embodiment, when the determination in step S11 is “No”, that is, when the shock wave occurrence frequency is equal to or less than the second set value 79 that is larger than the first set value 43, the determination in step S12, that is, the shock wave occurrence frequency. Is determined to be smaller than the first set value 43, the probability that the shock wave occurrence frequency is smaller than the first set value 43 is reduced. For this reason, it is reduced that the improvement effect of the tensile residual stress of the core shroud (WJP execution object) 52 is insufficient.

  The control device 22 and the control device 23 may be integrated into a single control device.

  In the first and second embodiments, the determination in step S7 and the control in step S8 may be changed to the determinations in steps S11 and S12 and the control in step S14 performed in the present embodiment.

  The control by the control device 23 in step S14 may be changed to control of the scanning speed of the nozzle 6 by the control device 22. That is, the control device 22 controls the corresponding moving device of the nozzle scanning device that scans the nozzle 6 so as to reduce the scanning speed of the nozzle 6.

  Examples 1, 2 and 3 described above can be applied to the improvement of residual stress in components of a pressurized water nuclear plant. Furthermore, the above-described Examples 1, 2 and 3 are applied to the improvement of the stress of the steel rod immersed in the sea of the ship which is difficult to pull up from the sea to the land, and the dropping of the light spot attached to the steel plate. Can do. Further, the embodiment in which the signal processing device 39 is replaced with the signal processing device 39B in the first embodiment and the first embodiment may be applied to surface modification of automobile parts.

  The present invention can be applied to the improvement of the residual stress of the constituent members.

  DESCRIPTION OF SYMBOLS 1 ... Water jet peening apparatus, 4 ... Water tank, 5 ... High pressure pump, 6 ... Nozzle, 9 ... High pressure hose, 10, 10A ... Nozzle scanning device, 12, 14, 38, 58A, 58B ... Moving device, 13 ... 1st Arm, 16 ... Pressure sensor, 20 ... Counter, 22, 23 ... Control device, 28 ... Bubble, 29 ... Shock wave, 39, 39A, 39B ... Signal processing device, 51 ... Reactor pressure vessel, 52 ... Core shroud, 60 ... Arm, 62 ... post member, 63 ... elevating body, 65 ... turntable, 72, 72A ... AE sensor, 75 ... detection time determination unit, 76 ... time difference determination device, 77 ... shock wave counting device.

Claims (17)

  Injecting water supplied from a pump as water flow from the nozzle into the water in which the nozzle exists, moving the nozzle that is injecting the water flow along the water jet peening construction object existing in the water, A shock wave generated by collapsing bubbles contained in the water flow jetted into the water from the nozzle is applied to the water jet peening object, and the generated shock wave is detected by a shock wave detection device disposed in the water. A water jet peening method, wherein the frequency of occurrence of the detected shock wave is obtained.   When the frequency of occurrence falls below a first set value, either the pressure or flow rate of the water discharged from the pump and supplied to the nozzle is increased, and either the pressure or flow rate of the water is increased. 2. The water jet peening method according to claim 1, wherein the shock wave is applied to at least a portion of the water jet peening execution target object where the occurrence frequency is equal to or lower than a first set value.   When the occurrence frequency is equal to or lower than the first set value, the nozzle scanning speed is reduced, and after the nozzle scanning speed is lowered, at least the occurrence frequency of the water jet peening object is set to the first setting. The water jet peening method according to claim 1, wherein the shock wave is applied to a portion that is equal to or less than a value.   When the occurrence frequency is equal to or lower than a second set value that is greater than the first set value and the occurrence frequency is greater than the first set value, the nozzle that is injecting the water flow is discharged from the pump while scanning. And increasing the pressure and flow rate of the water supplied to the nozzle, and scanning the nozzle that is jetting the water flow in a state where either the pressure or flow rate of the water is increased. Item 8. The water jet peening method according to Item 1.   When the occurrence frequency is equal to or less than a second set value that is greater than the first set value and the occurrence frequency is greater than the first set value, scanning the nozzle while scanning the nozzle that is ejecting the water flow The water jet peening method according to claim 1, wherein the nozzle jetting the water flow is scanned in a state where the speed is decreased and the scanning speed is decreased.   The pressure and flow rate of the water discharged from the pump and supplied to the nozzle when the occurrence frequency is equal to or less than a second set value greater than the first set value and the occurrence frequency is equal to or less than the first set value. After increasing either of the pressure and flow rate of the water, at least the occurrence frequency of the water jet peening construction object, at a location where the occurrence frequency is less than or equal to the first set value, The water jet peening method according to claim 1, wherein the shock wave is applied.   When the occurrence frequency is equal to or less than a second set value greater than the first set value and the occurrence frequency is equal to or less than the first set value, the nozzle scanning speed is reduced, and the nozzle scanning speed is reduced. The water jet peening method according to claim 1, wherein the shock wave is applied to at least a portion of the water jet peening execution target object where the occurrence frequency is equal to or lower than a first set value.   At least two shock wave detection devices are disposed in the water at different positions from the surface of the water jet peening object, and each shock wave detection signal output by the shock wave detection is output to each shock wave detection signal. On the basis of the shock wave detection time difference between the respective shock wave detection devices, when the obtained time difference is within a set range, it is determined that the shock wave has been detected, the occurrence frequency, The water jet peening method according to claim 1, wherein the water jet peening method is obtained based on the determined shock wave.   The water jet peening method according to claim 1, wherein the water jet peening object is a constituent member in a nuclear reactor vessel.   The water jet peening method according to claim 1, wherein the occurrence frequency of the shock wave is displayed on a display device.   A nozzle for injecting water, a pump for supplying water to the nozzle, a nozzle scanning device to which the nozzle is attached and scans the nozzle, a shock wave detection device attached to the nozzle scanning device, and the shock wave detection device A water jet peening apparatus, comprising: a shock wave counting device that counts the shock waves detected by the step of calculating the shock wave generation frequency.   The water jet peening apparatus according to claim 11, further comprising a display device that displays information on the occurrence frequency.   A first controller that controls the pump to increase either the pressure or flow rate of the water that is discharged from the pump and supplied to the nozzle when the frequency of occurrence is equal to or less than a first set value; When either the water pressure or the flow rate is increased, the nozzle scanning device is controlled so that at least the occurrence frequency of the water jet peening object is the first set value or less, the nozzle The water jet peening apparatus according to claim 11, further comprising: a second control device that scans the water.   When the occurrence frequency is equal to or lower than the first set value, the nozzle scanning device is controlled to reduce the scanning speed of the nozzle, and when the scanning speed is reduced, the nozzle scanning device is controlled to The water jet peening apparatus according to claim 11, further comprising a control device that causes the nozzle to scan at least at a location where the occurrence frequency of the jet peening object is equal to or less than a first set value. When the occurrence frequency is less than or equal to a second set value greater than the first set value and the occurrence frequency is greater than the first set value, and when the occurrence frequency is less than or equal to the second set value, the occurrence frequency is A first controller that controls the pump to increase either the pressure or the flow rate of the water discharged from the pump and supplied to the nozzle when the first set value or less is reached;
When the occurrence frequency is less than or equal to the second set value and the occurrence frequency is greater than the first set value, the nozzle scanning device is controlled to scan the nozzle, and the occurrence frequency is less than or equal to the second set value. When the occurrence frequency becomes equal to or lower than the first set value, the nozzle scanning device is controlled, and at least the occurrence frequency of the water jet peening object is equal to or lower than the first set value. The water jet peening apparatus according to claim 11, further comprising a second control device that scans the nozzle.   When the occurrence frequency is equal to or lower than a second set value greater than the first set value and the occurrence frequency is greater than the first set value, the nozzle scanning device is controlled to scan the nozzles. The nozzle scanning speed is decreased, and when the frequency of occurrence is less than or equal to the second set value and the frequency of occurrence is less than or equal to the first set value, the nozzle scanning device is controlled to scan the nozzles. When the nozzle speed is decreased and the nozzle scanning speed decreases, the nozzle scanning device is controlled so that at least the occurrence frequency of the water jet peening object is the first set value or less, the nozzle The water jet peening apparatus according to claim 11, further comprising a control device that scans the water.   Based on at least two shock wave detection devices arranged at different positions in the axial direction of the nozzle, and each shock wave detection signal output by the shock wave detection device by the detection of the shock wave, each of the shock wave detection devices A shock wave determination device that obtains a difference in detection time of the shock wave between each other and determines that the shock wave is detected when the obtained time difference is within a set range; and the occurrence frequency is determined by the shock wave determination device. The water jet peening apparatus according to claim 11, further comprising the shock wave counting device that counts the determined shock waves.

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