JP2011127925A - Welded structure of structural body in nuclear reactor, and method for welding the welded structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welded structure of a structural body in a nuclear reactor which can prevent the generation of a stress corrosion crack beforehand, and can perform integral installation welding stably and easily in a short time. <P>SOLUTION: The welded structure of the structural body in the nuclear reactor uses a constituent material of the structure body placed in a nuclear reactor pressure vessel 1 as a base metal 20, and welds the base material 20 to an object 34 to be welded. An overlay 31a formed of a weld metal is formed in the base metal 20, and the overlay 31a has at least a welding groove. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a welding structure for a reactor internal structure provided in a reactor pressure vessel of a boiling water reactor and a welding method thereof.

  In general, a boiling water reactor employs a system for forcibly recirculating reactor coolant as cooling water in order to increase the power density.

  In such a system, there are an external recirculation method and an internal recirculation method as a method for forcibly circulating the reactor coolant in the core portion in the reactor pressure vessel. Among these, the external recirculation system includes a plurality of jet pumps disposed in the reactor pressure vessel and a recirculation pump disposed outside the reactor pressure vessel, and the cooling water sent from the recirculation pump is supplied. The jet pump makes the jet flow, the surrounding reactor water is engulfed by this jet pump, the core plenum below the core is forced into the core, and the reactor coolant is forcibly recirculated in the reactor pressure vessel. I try to let them.

  11 to 18 show a conventional example of a jet pump of a boiling water reactor that employs a jet pump system based on this external recirculation system.

  FIG. 11 is a longitudinal sectional view showing a schematic configuration of a boiling water reactor.

  As shown in FIG. 11, a reactor coolant 2 and a core 3 are accommodated in the reactor pressure vessel 1, and the core 3 is composed of a plurality of fuel assemblies and control rods (not shown). Housed in shroud 10.

  The reactor coolant 2 flows upwardly from the core 3, and at that time, the temperature is raised by the nuclear reaction heat of the core 3 and a two-phase flow state of water and steam is obtained. The coolant 2 in the two-phase flow state flows into a steam / water separator 4 installed above the core 3 where it is separated into water and steam. Among these, the steam is introduced into a steam dryer 5 installed above the steam separator 4 and becomes dry steam.

  The dry steam is transferred to a steam turbine (not shown) via a main steam pipe 6 connected to the reactor pressure vessel 1 and is used for power generation. On the other hand, the separated water flows through the downcomer portion 7 between the core 3 and the reactor pressure vessel 1 and flows down below the core 3. A control rod guide tube 8 is installed below the core 3, and the control rod is inserted into and extracted from the core 3 through the control rod guide tube 8. A control rod drive mechanism 9 is installed below the control rod guide tube 8, and the control rod drive mechanism 9 controls insertion and withdrawal of the control rod into the core 3. A plurality of jet pumps 11 are installed in the downcomer portion 7 at equal intervals in the circumferential direction.

  On the other hand, a recirculation pump (not shown) is installed outside the reactor pressure vessel 1, and a recirculation system is formed by the recirculation pump, the jet pump 11, and a recirculation pipe disposed between them. It is configured. Then, driving water is supplied to the jet pump 11 by the recirculation pump, and the coolant 2 is forcibly circulated in the core by the action of the jet pump 11.

  FIG. 12 is an enlarged perspective view showing a main part of the jet pump 11 shown in FIG.

  As shown in FIG. 12, the jet pump 11 has a vertical riser pipe 12 in order to introduce the coolant supplied from the recirculation inlet nozzle 13 of the recirculation pump as an upward flow into the furnace. The riser pipe 12 is fixed to the furnace wall 1 a of the reactor pressure vessel 1 via a riser brace 20. A pair of elbows 15 are connected to the upper portion of the riser pipe 12 via a transition piece 14, and the coolant is divided into two hands by these elbows 15 and flows downward. An inlet throat 17 is connected to each of these elbows 15 via a mixing nozzle 16.

  Then, the coolant 2 is injected by the mixing nozzle 16, and at that time, the reactor water is entrained from the surroundings, and the injected coolant 2 and the entrained water are mixed in the inlet throat 17. Each inlet throat 17 is connected to a diffuser 18, and these diffuser 18 feeds a coolant below the core. These elbow 15, mixing nozzle 16, and inlet throat 17 are integrated and are called an inlet mixer 51.

  By the way, in said structure, fluid vibration generate | occur | produces with the flow at the time of the cooling sent from a recirculation pump. In order to cope with this fluid vibration, as described above, the lower end of the riser pipe 12 is welded to the recirculation inlet nozzle 13, and the upper end is fixed to the reactor pressure vessel 1 via the riser brace 20.

  The upper end of the inlet throat 17 is mechanically connected to the transition piece 14 via the mixing nozzle 16 and the elbow 15, and the lower end of the inlet throat 17 is inserted into the upper end of the diffuser 18. Thus, both the riser pipe 12 and the inlet mixer 51 are configured to sufficiently cope with fluid vibration.

  Next, the configuration above the mixing nozzle 16 will be described.

  As shown in FIGS. 12 and 13, a pair of gate-shaped posts 21 are erected on both sides of the transition piece 14 so as to face each other. Are formed respectively. Both ends of a jet pump beam 23 for pressing and supporting the elbow 15 from above are engaged with these groove portions 22. The end portion of the jet pump beam 23 has a rectangular cross section and is a beam whose cross-sectional area increases toward the central portion in the length direction, and a constituent member for pressing the elbow 15 is provided at the central portion. .

  Based on FIG. 13 and FIG. 14, the structure of the jet pump beam 23 and the fitting state to the post 21 will be described.

  As shown in FIGS. 13 and 14, a screw hole 23a is formed in the vertical direction in the center of the jet pump beam 23, and a head bolt 28 is screwed into the screw hole 23a. A hexagon head 28a is formed at the upper end of the head bolt 28, and a semi-round head 28b is formed at the lower end. On the other hand, the elbow 15 is formed with a pedestal portion 15a having a horizontal upper end surface, and a counterbore 15b is formed in the pedestal portion 15a. A semi-round head 28b of a head bolt 28 is fitted into the counterbore 15b via a spherical washer 15c.

  As shown in FIG. 12, the inlet mixer 51 (elbow 15, mixing nozzle 16, inlet throat 17) is not fixed to the reactor pressure vessel 1. The inflow water pressure of the driving water supplied via the air acts. In addition, a reaction force such as the ejection pressure of the driving water ejected from the mixing nozzle 16 into the diffuser 18 acts on the inlet mixer 51 upward. In order to counter this load, the head bolt 28 is screwed into the jet pump beam 23 as described above.

  As shown in FIG. 13, since the post 21 is fixed at a fixed position, when the head bolt 28 is screwed downward, the jet pump beam 23 is moved upward, and the jet pump beam Both ends of 23 are in contact with the upper wall surface of the groove 22. As a result, the jet pump beam 23 receives an upward load.

  On the contrary, a downward load is applied to the upper end portion of the elbow 15 via the head bolt 28, and the magnitude thereof is determined in relation to the upward load due to the reaction force of the driving water. A keeper 39 is detachably fitted to the hexagon head 28a of the head bolt 28. The keeper 39 is fixed on the plate 40 by spot welding. The plate 40 has a rectangular shape, and is fixed to the upper surface of the jet pump beam 23 by two bolts 40a as shown in FIG.

  A retainer 41 shown in FIG. 13 is provided below the head bolt 28 by a retainer mounting bolt 42 so that the inlet mixer 51, the head bolt 28, and the jet pump beam 23 can be handled as a unit when the inlet mixer 51 is removed. It is fixed to the elbow 15.

  FIG. 18 shows a main part of FIG. The inlet throat 17 is attached to a restraint bracket 25 fixed to the riser pipe 12. The inlet throat 17 is fixed by two pairs of adjusting screws 48 and wedges 47. The adjusting screw 48 is fixed to the restraint bracket 25 by rotation. The diffuser 18 is fixed to a shroud support plate 26 welded to the reactor pressure vessel 1. The wedge 47 is held by a rod 52.

  The jet pump 11 is used under severe conditions compared to other devices in order to circulate the coolant. Therefore, a large load acts on each member, and severe stress acts particularly on the riser brace 20 that supports the riser pipe 12 in the middle thereof. The riser brace 20 suppresses fluid vibration during operation of the reactor generated in the riser pipe 12 and heat between the reactor pressure vessel 1 made of carbon steel and the riser pipe 12 made of austenitic stainless steel. Absorbs differential expansion. Therefore, during the operation of the nuclear reactor, the reactor is in a deformed state while absorbing the above thermal expansion difference.

  As shown in FIG. 15, the riser brace 20 includes a support block 32 that is spanned and fixed to the free end side of a plate-like brace 31 that forms a pair of upper and lower sides. The plate-like brace 31 and the support block 32 are fixed in advance by V-shaped groove welding or the like and are integrally formed.

  When the riser brace 20 is attached to the reactor pressure vessel 1, the riser brace 20 is inserted so as to sandwich the riser pipe 12 of the jet pump between the left and right plate-like braces 31, and a circle formed at the center of the support block 32. The arcuate arcuate engagement portion 33 is engaged with the riser pipe 12 so as to surround it. In this state, the left and right braces 31 of the riser brace 20 are brought into contact with the mounting pads 34 of the reactor pressure vessel 1, and the individual braces 31 are welded and fixed to the mounting pads 34, respectively, while the support blocks 32 are arcuately engaged. The part 33 is fixed to the riser pipe 12 by welding.

  In this way, the riser brace 20 is fixed to the mounting pad 34 of the reactor pressure vessel 1, while the support block 32 of the riser brace 20 is fixed to the riser pipe 12, and the riser pipe 12 of the jet pump 11 is connected to the riser brace. 20 is stably fixed and held in the reactor pressure vessel 1.

  By the way, the riser pipe 12 of the jet pump 11 is thermally expanded by the temperature rise of the reactor coolant (reactor water) 2 accompanying the operation of the reactor. The expansion due to the thermal expansion of the riser pipe 12 is absorbed and escaped by the four left and right upper and lower plate-like braces 31 of the riser brace 20 being warped upward.

  As shown in FIG. 16, when four plate-like braces 31 in the riser brace 20 are fixed to the mounting pads 34 of the reactor pressure vessel 1 by welding, conventionally, they are generally welded by K-shaped groove welding. Yes. In this case, the K-shaped groove welding without the welded portion can maintain a stable strength against various loads. Since a large load acts on the riser brace 20 that is fixed to the mounting pad 34 of the reactor pressure vessel 1, each brace 31 has a sharp K-shaped weld groove and has a shape in which welding defects are unlikely to occur. Composed. Moreover, in order to avoid the stress concentration by shape discontinuity, it is necessary to finish a weld metal part after welding to the shape of the smooth curved surface part 35 with a grinder.

  Now, it is important to measure the flow rate of the jet pump during normal operation in order to control the output of the nuclear power plant. For this reason, as shown in FIGS. A measurement pipe 19 is provided to measure the static pressure difference between the upper and lower portions of the diffuser 18 during operation, and the jet pump flow rate is calculated from this measured value and the calibration value measured before using the plant. The measurement pipe 19 is welded and supported by a support 24 that is welded to the static pressure holes at the upper and lower portions of the diffuser 18 and fixed to the diffuser 18, and as shown in FIGS. 17A and 17B, It is arranged in a complicated state in the lower part of the pump 11, and is connected to the piping outside the furnace through the jet pump measurement nozzle 27.

  Two jet pump measurement nozzles 27 are provided at target positions of the reactor pressure vessel 1. The jet pump 11 having such a configuration is used under severe conditions as compared with other devices due to the cooling flow sent from the recirculation pump. For this reason, a large load acts on each member, and particularly, the measurement pipe 19 is affected by the fluid vibration of the diffuser 18 directly or via the support 24, and severe stress acts. Therefore, it is fully expected that a pipe break will occur. If this measuring pipe 19 breaks, it will interfere with the power control of the nuclear reactor and must be repaired.

  Here, as is clear from FIG. 17B, the measurement pipe 19 is disposed in the annular space 29 between the reactor pressure vessel 1 and the core shroud 10, and above the instrumentation pipe 19. The riser pipe 12 and the inlet throat 17 are arranged, and jet pump components such as the riser brace 20, the mixing nozzle 16 and the elbow 15 are arranged.

  As an improvement technique of such a jet pump, for example, there is a technique in which a connection portion with a mounting pad of a riser brace is locally thickened (see, for example, Patent Document 1).

JP 2007-85793 A

  By the way, in the jet pump 11 described above, if it is necessary to replace and install the jet pump 11 due to deterioration over time after the start of the reactor operation, the riser brace 20 and the mounting pad 34 of the reactor pressure vessel 1 are connected. Welding is required.

  Recent new findings have found that when the residual stress on the material surface is in tension, fine cracks in the surface of the material can lead to stress corrosion cracking, a characteristic of stainless steel. Therefore, it is necessary to improve the residual stress on the material surface from the tension side to the compression side by various methods.

  However, in order to improve the residual stress on the material surface to the compression side in the reactor pressure vessel 1 after welding, it is often difficult to access because the construction part is often a narrow part. In addition, there is a problem that the amount of exposure dose to workers increases due to work for a long time in a radiation environment.

  Further, during the operation, the side surface of the rod 52 comes into contact with the wedge 47 due to the vibration of the jet pump 11, and this wear progresses to lose the function of holding the wedge 47 of the rod 52. May be damaged.

  Furthermore, if the measurement pipe 19 breaks during operation, it will hinder the power control of the nuclear reactor, and the nuclear reactor operation is impossible without repairing this.

  If the jet pump 11 needs to be replaced or installed after the start of operation due to deterioration over time, the power consumption of the recirculation pump can be changed even if it is replaced with the same performance as the jet pump 11 before replacement. Since there is no change, economic efficiency does not change.

  The present invention has been made to solve the above-described problems, and prevents the occurrence of stress corrosion cracking in advance, and can weld a structure in a furnace that can perform a sound mounting weld stably and easily in a short time. It is an object to provide a structure and a welding method thereof.

  In order to achieve the above object, a welded structure of an in-core structure according to the present invention uses a constituent material of the in-core structure provided in a reactor pressure vessel as a base material, and welds the base material to a welding object. A welded structure of an in-furnace structure, wherein a build-up portion made of a weld metal is formed on the base material, and the build-up portion has at least a weld groove portion.

  In order to achieve the above object, a method for welding an in-core structure according to the present invention uses a constituent material of an in-core structure provided in a reactor pressure vessel as a base material, and welds the base material to a welding object. A method of welding a furnace internal structure, wherein a build-up portion forming step for forming a build-up portion made of weld metal on the base material, and the build-up portion is welded at least after the build-up portion forming step. And a welding step for welding the welding object to the welding object.

  According to the present invention, it is possible to prevent the occurrence of stress corrosion cracking resulting from the tensile residual stress state on the material surface after welding, and to perform sound and secure welding in a short time.

It is a top view which shows the riser brace welding structure in one Embodiment of this invention. It is an expanded sectional view which follows the II-II line before welding of FIG. It is an expanded sectional view which follows the II-II line after the welding of FIG. It is a front view which shows the wedge in one Embodiment of this invention. FIG. 5 is a side view of FIG. 4. FIG. 5 is a partial plan view of FIG. 4. It is a fragmentary sectional front view which shows the attachment structure of the piping for measurement in one Embodiment of this invention. It is a front view which shows the wedge in the modification of this invention. It is a side view of FIG. FIG. 9 is a partial plan view of FIG. 8. It is a longitudinal cross-sectional view which shows schematic structure of a boiling water reactor. It is a perspective view which expands and shows the principal part of the jet pump shown in FIG. It is a fragmentary sectional front view which expands and shows a part of jet pump shown in FIG. FIG. 14 is a plan view of FIG. 13. It is a perspective view which expands and shows the riser brace part of the jet pump shown in FIG. It is an expanded sectional view which shows the conventional riser brace welding part. (A), (b) is a block diagram which shows the conventional jet pump measurement piping. It is a top view which expands and shows a part of jet pump shown in FIG.

  Hereinafter, an embodiment of a welded structure of an in-furnace structure according to the present invention will be described with reference to the drawings. Since the overall configuration of the jet pump is substantially the same as that shown in FIG. 12, the same or corresponding parts will be described with the same reference numerals with reference to FIG.

  1 is a plan view showing a welded structure of the riser brace 20, and FIGS. 2 and 3 are enlarged sectional views taken along the line II-II before and after welding in FIG.

  As shown in FIG. 1, the riser brace 20 includes a support block 32 for holding the riser pipe 12 from the core side of the reactor pressure vessel 1 toward the reactor wall 1a, and the support block 32 is fixed to the riser pipe. 12 and a pair of braces 31 holding the furnace wall 1a from both sides in the circumferential direction of the furnace wall 1a.

  In the riser brace 20, the tip of each brace 31 is welded and fixed to a mounting pad 34 formed by overlay welding of the inner surface of the furnace wall 1a. Each brace 31 has a pair of flat arms arranged in parallel vertically in the same manner as the configuration of the conventional example shown in FIG. 15. In this embodiment, as shown in FIGS. In addition, the welding structure for the mounting pad 34 at the tip of the brace 31 is improved.

  In FIG. 2, the tip shape of the brace 31 is shown as an enlarged longitudinal sectional view. As shown in FIG. 2, a built-up portion 31 a having a shape in which the upper and lower surfaces rise is formed on the tip side of the brace 31. This built-up portion 31a is formed of a weld metal by welding from the front end side of the brace 31, and has a curved surface portion 35 whose front end rises smoothly. The curved surface portion 35 is, for example, a circular arc surface having a constant diameter, that is, a vertically (R) shape portion that is vertically symmetric. In addition, an inclined surface that is vertically symmetrical is formed on the front end side of the built-up portion 31a, whereby the built-up portion 31a has a radish shape as a whole. Further, a thin piece 31b is integrally formed at the top and bottom central portion of the tip of the inclined surface of the built-up portion 31a, and the tip of the thin portion 31b is in contact with the mounting pad 34.

  And as shown in FIG. 3, the front end side of the build-up part 31a and the attachment pad 34 are welded by arc welding (for example, TIG welding, MIG welding, MAG welding, etc.), and the weld metal 36 in this welded part is, for example, It has a wide shape that coincides with the extended line of the curved surface portion 35 of the built-up portion 31a.

  In the present embodiment, as shown in FIG. 3, a built-up portion 31a made of weld metal is formed on a brace 31 connected to the mounting pad 34, and the built-up portion 31a has at least a weld groove portion. The build-up portion 31 a is formed in a range wider than a range of 20 mm from a weld groove portion where residual stress in the compression direction is generated on the material surface of the mounting pad 34 by welding with the brace 31.

  In addition, before welding the front end side of the built-up portion 31a to the mounting pad 34, the tensile residual stress generated on the surface of the base material by welding is applied to the compression side in advance at the joint between the built-up portion 31a and the base material of the brace 31. Therefore, improvement work such as laser peening and laser desensitization treatment (LDT: Laser Desensitization Treatment) is performed in advance in a factory or the like.

  The weld metal used for the built-up portion 31a is, for example, an austenitic stainless steel (JIS SUS316L, SUS304L) whose brace 31 as a base material has excellent corrosion resistance in high-temperature water and is an object to be welded. When the material of the pad 34 is stainless steel for welding (JIS Y308), stainless steel for welding (JIS Y308L, Y316L) is used.

  In addition, the material of the reactor pressure vessel 1 that is the object to be welded is low alloy steel (JIS SFVQA), and the material of the furnace internal structure that is the base material is austenitic stainless steel SUS316L, SUS304L, or a heat-resistant and corrosion-resistant alloy. In the case of Inconel (registered trademark) (JIS NCF600), Inconel (registered trademark) 82, which is a heat-resistant and corrosion-resistant alloy, is used as the weld metal used for the built-up portion 31a.

  Therefore, austenitic stainless steel (JIS SUS316L, SUS304L) is mainly used as the material of the in-furnace structure, and the material of the weld metal used for the built-up portion 31a is appropriately selected based on the material of the welding object. The

  Here, as a constituent material of the in-furnace structure of the present embodiment, the riser brace 20 of the jet pump 11 has been described as an example, but not limited thereto, for example, other constituent materials that constitute the jet pump 11 Of course, it is possible to select a material to be welded from a certain riser pipe 12 or diffuser 18 as appropriate, and other furnace structures are also applicable.

  Moreover, in this embodiment, although the build-up part 31a was formed in the range wider than the range of 20 mm from the groove | channel of the brace 31, not only this but the part including a weld groove part is made of the weld metal 31a. What is necessary is just to form.

  As described above, according to this embodiment, the built-up portion 31a made of weld metal is formed on the brace 31 connected to the mounting pad 34, and the built-up portion 31a has at least a weld groove portion. 34, it is not necessary to carry out improvement work to make the tensile residual stress applied to both surfaces of the base material on the compression side when the brace 31 is attached to 34, and the riser brace 20 can be stably and easily placed in a radiation environment in a short time. It can be attached.

  Next, the attachment state of the inlet mixer 51 and the restraint bracket 25 is demonstrated based on FIGS. FIG. 4 is a front view showing a wedge in one embodiment of the present invention. FIG. 5 is a side view of FIG. 6 is a partial plan view of FIG.

  As shown in FIGS. 4 to 6, a support 45 and a bracket 50 are respectively fixed to the outer peripheral surface of the inlet throat 17 by welding, and a wedge 47 is disposed between the support 45 and the bracket 50. .

  A through hole is formed in the wedge 47 along the longitudinal (vertical) direction. Similarly, through holes having the same diameter are formed in the support 45 and the bracket 50. One rod 52 passes through these through holes. Both ends of the rod 52 are fixed by a support 49 and a bracket 50 using nuts 49, respectively. The wedge 47 is configured to be slidable in the vertical direction on the outer peripheral surface of the inlet throat 17 using the rod 52 as a guide.

  On the other hand, the restraint bracket 25 is attached to the side surface of the riser pipe 12 and has a contact surface with the wedge 47. The wedge 47 is formed in a wedge shape in the vertical direction, and is configured to contact the contact surface of the restraint bracket 25 at an arbitrary position. Thus, when the wedge 47 contacts the contact surface of the restraint bracket 25 at an arbitrary position, the horizontal displacement of the inlet throat 17 can be restrained.

  In addition, the wedges 47 are respectively formed with rounded portions 47a at the open ends of the upper and lower ends of the through hole along the vertical direction. Therefore, the wedge 47 is formed with the rounded portions 47a at the opening ends of the upper and lower ends of the through hole, so that the opening end of the through hole of the wedge 47 is brought into contact with the outer peripheral surface of the rod 52 and is vibrated. In this case, it is possible to prevent wear on the outer peripheral surface of the rod 52, and it is possible to reduce a decrease in the diameter of the rod 52 due to wear.

  Further, the wedge 47 is generally made of cast stainless steel (JIS SCS19A, SCS13) or austenitic stainless steel (JIS SUS316L, SUS304L). In the present embodiment, the material of the rod 52 is harder than the material of the wedge 47, for example, a heat-resistant stainless steel containing 20.5% or more of nickel-base alloy or chromium of JIS NCF750 is used. Therefore, by making the material of the rod 52 harder than the material of the wedge 47, it is possible to prevent wear of the outer peripheral surface of the rod 52 due to the hardness difference, and to reduce the decrease in the diameter of the rod 52.

  And in this embodiment, if the range which contacts the wedge 47 of the outer peripheral surface of the rod 52 or all the outer peripheral surfaces are coat | covered with the weld metal of hardness Rockwell hardness C30 or more, for example, according to the hardness difference of a raw material and a weld metal. It is possible to reduce the decrease in the diameter of the rod 52.

  Next, the mounting state of the measurement pipe 19 will be described with reference to FIG. FIG. 7 is a partial cross-sectional front view showing a measurement pipe mounting structure in one embodiment of the present invention.

  As shown in FIG. 7, the diffuser 18 has a collar 53, and a belt-like band 54 is covered on a part of the outer peripheral surface of the collar 53. The collar 53 and the band 54 are formed with detection holes 55 for detecting a differential pressure on the inner peripheral side of the diffuser 18.

  The measurement pipe 19 is connected to the collar 53 via a band 54. Specifically, the measurement pipe 19 has a bent portion 19a formed in the vicinity of the attachment end portion, and the attachment end portion is directly connected to the band 54 by welding. A connection guide 56 is provided at the upper end of the diffuser 18.

  As described above, according to the present embodiment, the bent portion 19a is formed in the measurement pipe 19, and the attachment end is directly connected to the band 54 by welding, so that the conventional pipe joint is omitted, and the pipe Since there is no welded part connecting the joint and the measurement pipe 19, it is possible to reduce the possibility that the measurement pipe 19 is broken, and it is possible to provide a highly reliable jet pump measurement pipe 19. .

  FIG. 8 is a front view showing a wedge in a modification of the present invention. FIG. 9 is a side view of FIG. FIG. 10 is a partial plan view of FIG. In addition, the same code | symbol is attached | subjected to the part same as embodiment shown in FIGS. 4-6, and only a different structure is demonstrated.

  As shown in FIGS. 8 to 10, in this modification, the width of the wedge 47 </ b> A is formed wider than the width of the contact surface of the restraint bracket 25. In this way, by increasing the width of the wedge 47A from the width of the contact surface of the restraint bracket 25, the frictional resistance against the displacement of the wedge 47A is increased. Thereby, it is possible to reduce the decrease in the diameter of the rod 52.

  Therefore, according to the present modification, the possibility that the rod 52 should be damaged can be reduced by increasing the width of the wedge 47A from the width of the contact surface of the restraint bracket 25. A high jet pump 11 can be provided.

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Reactor coolant, 3 ... Core, 4 ... Steam separator, 5 ... Steam dryer, 6 ... Main steam pipe, 7 ... Downcomer part, 8 ... Control rod guide pipe, 9 Control rod drive mechanism, 10 ... Core shroud, 11 ... Jet pump, 12 ... Riser pipe, 13 ... Recirculation inlet nozzle, 14 ... Transition piece, 15 ... Elbow, 16 ... Mixing nozzle, 17 ... Inlet throat, 18 ... Diffuser, 19 ... piping for measurement, 20 ... riser brace, 21 ... post, 22 ... groove, 23 ... jet pump beam, 24 ... support, 25 ... restorent bracket, 26 ... shroud support plate, 27 ... nozzle for jet pump measurement 28 ... Head bolt, 29 ... Annular space, 31 ... Brace, 31a ... Overlaying part, 32 ... Support block, 33 ... Arc-shaped engagement part, 34 ... Installation 35, curved surface shape part, 36 ... weld metal, 39 ... keeper, 40 ... plate, 41 ... retainer, 42 ... retainer mounting bolt, 45 ... support, 47 ... wedge, 49 ... nut, 50 ... bracket, 51 ... Inlet mixer, 52 ... Rod, 53 ... Color, 54 ... Band

Claims (5)

The construction material of the reactor internal structure provided in the reactor pressure vessel is a base material, and the welded structure of the reactor internal structure that welds this base material to the welding object,
A welded structure of an in-furnace structure, wherein a build-up portion made of weld metal is formed on the base material, and the build-up portion has at least a weld groove portion. The in-furnace structure is a jet pump for circulating circulating cooling water to the core, and the constituent material as the base material is a riser pipe, a riser brace or a diffuser,
The welded structure of an in-furnace structure according to claim 1. When the material of the base material is austenitic stainless steel and the material of the welding object is stainless steel for welding, the material of the overlay is stainless steel for welding,
The welded structure of an in-furnace structure according to claim 1 or 2. When the material of the base material is austenitic stainless steel or heat and corrosion resistant alloy, and the material of the welding object is low alloy steel, the material of the overlay is a heat and corrosion resistant alloy,
The welded structure of an in-furnace structure according to claim 1 or 2. A method for welding a reactor internal structure in which a constituent material of a reactor internal structure provided in a reactor pressure vessel is used as a base material, and the base material is welded to an object to be welded.
A build-up part forming step for forming a build-up part made of weld metal in the base material;
A welding step in which, after the build-up portion forming step, the build-up portion has at least a weld groove portion and is welded to the welding object;
A method for welding an in-furnace structure.

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