JP5523883B2 - Installation method of core spray system piping - Google Patents

Description

  The present invention relates to a method for attaching a core spray system pipe for attaching a core spray system pipe as a core cooling system device to a reactor pressure vessel of a boiling water nuclear power plant.

  With reference to FIG. 13 to FIG. 15, the configuration and function of conventional core spray system piping installed in the reactor pressure vessel will be described. FIG. 13 is a perspective view showing the overall configuration of the core spray system piping, and FIG. 14 is an enlarged cross-sectional view of the main part of the core spray system piping shown in FIG. FIG. 15 is an enlarged side view showing a part of the furnace wall shown in FIG. 14 as a cross section.

  As shown in FIGS. 13 and 14, a water supply nozzle 101 is provided on the furnace wall 102 of the reactor pressure vessel 100. A nozzle safe end 103 (hereinafter referred to as “safe end”) made of a hollow tube is provided in the water supply nozzle 101, and a thermal sleeve 104 is provided in the safe end 103.

  A junction box 105 is provided at the tip of the thermal sleeve 104 that protrudes into the furnace. The junction box 105 is divided into two in the horizontal direction inside the furnace, and is arranged in an arc along the inner surface of the furnace wall. The rising pipes 110 and 110 extend vertically downward, and their lower end portions penetrate from the outer peripheral surface side to the inner peripheral surface side of the core shroud 106 and are connected to the core spray system pipes 107 and 107.

  That is, an annular core spray system pipe 107 is welded to the junction box 105 via two semi-annular pipe portions 108 and 108 at the insertion end of the thermal sleeve 104 in the furnace, and the semi-annular pipe Rise pipes 110 are attached to both ends where the portion 108 is not welded via 90 ° elbows 109.

  Since the cover plate 111 is attached to the inside of the furnace of the junction box 105, the thermal sleeve 104 is welded to the safe end 103 before the core spray system pipe 107 is carried into the furnace. With this configuration, it was possible to weld the junction box 105 and the thermal sleeve 104 from the cover plate 111 after being carried into the furnace.

  However, since the welding between the junction box 105 and the semi-circular pipe portion 108 is discontinuous, there have been cases where cracks and the like occur overseas. Therefore, for example, as shown in FIG. 15, the replacement core spray system pipe 107 (107b) uses a reducing tee 112, which is a T-shaped pipe joint member, instead of the junction box 105. Butt circumferential welding with 108 is possible.

  Further, the application of the reducing tee 112 can also reduce the welding of the cover plate 111 of the junk box 105.

  On the other hand, since the reducing tee 112 does not function as the cover plate 111 of the junction box 105, the core spray system pipe 107 is loaded into the furnace with the thermal sleeve 104 welded to the safe end 103. It is impossible to weld the duty tee 112 and the thermal sleeve 104.

  When installing the core spray system pipe 107 of a plant of 500,000 KW, 800,000 KW or the like in the furnace, it is inserted into the nozzle 113 (113a, 113b) with the thermal sleeve 104 attached to the reducing tee 112, Welding with the safe end 103 is performed.

  In the above method, since the N5 nozzle 113a and the N16 nozzle 113b of the reactor pressure vessel (RPV) 100 are mounted 180 ° symmetrically with respect to the core position in plan view, the procedure can be set without interfering with each other. is there.

  On the other hand, as shown in FIG. 15, the N5 nozzle 113a and the N16 nozzle 113b of the 1.1 million KW plant are not mounted 180 ° symmetrically with respect to the core position, and are arranged close to each other on the side shifted laterally from the core. Is provided.

  For this reason, when installing a pair of core spray system pipes 107 a and 107 b in the furnace, the installation is carried out first, and the thermal sleeve 104 is assembled to the reducing tee 112.

  In this case, the riser pipe 110 that is long above and below the core spray system pipe 107b that is loaded and attached later interferes with the core spray system pipe 107a that has been loaded earlier, and cannot be installed in the furnace.

  Further, in the method in which the thermal sleeve 104 and the safe end 103 are welded in advance and the core spray system piping 107 is carried in, and then the reducing tee 112 and the thermal sleeve 104 are welded from the inside of the nozzle 113, the welded portion is an atom. Since it is on the center side of the furnace pressure vessel 100, it becomes difficult.

JP 2000-214290 A

  As described above, when a reducing pressure tee structure is adopted for a reactor pressure vessel in which nozzles such as a 1.1 million KW plant are not attached 180 ° symmetrically, it becomes difficult to attach a core spray system pipe. .

  The reason for this is that when the thermal sleeve attached to the reducing tee is inserted into the nozzle, the core spray system pipes interfere with each other in the furnace, and further, the problem for improving the welding performance is also taken up.

  The present invention has been made in view of such circumstances, and the reducing tee is applied by replacing the core spray system piping in which aging or cracking occurs without interfering with the core spray system piping. Provided is a method for mounting a core spray system pipe that enables the core spray system pipe to be used again.

  In the present invention, the thermal sleeve is attached to the reducing tee within a length range in which the core spray system pipe can be inserted, so that the welding position of the short pipe and the thermal sleeve is arranged closer to the outside of the nozzle, thereby facilitating welding. A method for mounting the core spray system piping that can be performed in a convenient manner is provided.

  Furthermore, it is possible to adopt reducing tees, and from the discontinuous welded structure between the junction box and the annular pipe, the reducing tee and the annular pipe are made into a butt welded structure, so that the reliability of the equipment can be improved. Provided is a method of mounting a core spray system pipe that can improve the performance.

  In addition, the present invention provides a method for mounting a core spray system pipe that eliminates the junction box, reduces the number of weld lines compared to the junction box structure, and can reduce the damage potential.

The present invention has been made in view of the above circumstances, and is a method of attaching a core spray system pipe for attaching a core spray system pipe as a core cooling system device to a reactor pressure vessel of a boiling water nuclear power plant, The core cooling water injection nozzle provided in the core spray system piping is set so as to exclude the position 180 ° symmetrical with respect to the center of the core in plan view, and a part of the thermal sleeve divided by the T-shaped pipe joint and the circle A core spray system pipe with a riser pipe attached to only the end of the ring pipe and the short ring pipe through the 90 ° elbow is installed in the furnace, and the riser pipe attached to the long ring pipe is installed in the furnace. A method for mounting a core spray system pipe is provided.

  According to the present invention, even in a plant where the nozzle is not in a 180 ° symmetrical position, such as a plant of 1.1 million KW class, the core spray system piping adopting the reducing tee structure is installed by replacement work or construction work. It becomes possible.

  Then, the core spray system piping that has deteriorated or cracked may be replaced without interfering with the core spray system piping that may interfere with each other. Is possible.

  Also, by attaching the thermal sleeve to the reducing tee within the length range in which the core spray system piping can be inserted, the welding position between the short pipe and the thermal sleeve is closer to the outside of the nozzle, making welding easier. .

  Furthermore, it becomes possible to adopt reducing tees, so that the discontinuous welded structure between the junction box and the annular pipe is changed to a butt welded structure between the reducing tee and the annular pipe. You will be able to improve.

  Further, since the weld line can be reduced by one place as compared with the junction box structure, the damage potential can be reduced.

Explanatory drawing which shows the attachment method of the core spray type | system | group piping by 1st Embodiment of this invention. The cross-sectional view which shows the basic structure of the nozzle safe end applied in the said embodiment. The cross-sectional view which shows the structure of the nozzle safe end applied in the said embodiment. The top view which shows the basic composition of the annular pipe applied in the said embodiment. The top view which shows the state which attached the riser pipe | tube to the annular pipe shown in FIG. The top view which shows the temporary placement state of the core spray type | system | group piping applied in the said embodiment. The top view which shows the state at the time of welding of the core spray type | system | group piping shown in FIG. The cross-sectional view which shows the attachment structure of the thermal sleeve in the said embodiment. The top view which shows the attachment method of the core spray type | system | group piping by 2nd Embodiment of this invention. The top view which shows the attachment method of the core spray type | system | group piping by 3rd Embodiment of this invention. The top view which shows the attachment method of the core spray type | system | group piping by 4th Embodiment of this invention. Explanatory drawing which shows the attachment method of the core spray type | system | group piping by 5th Embodiment of this invention. The perspective view explaining the installation method of the core spray system piping by a prior art example. The longitudinal cross-sectional view explaining the installation method of the core spray type | system | group piping by a prior art example. The top view explaining the installation method of the core spray type | system | group piping by a prior art example.

  Hereinafter, an embodiment of a method for attaching a core spray pipe according to the present invention will be described with reference to FIGS.

[First Embodiment (FIGS. 1 to 8)]
FIG. 1 is a plan view showing the configuration of a replacement core spray system pipe that is applied to the core spray system pipe mounting method according to the first embodiment of the present invention.

  As shown in FIG. 1, the replacement core spray system piping 1 according to the present embodiment includes a hollow first annular pipe 2 (2a) having a substantially semicircular arc shape, and about 1/3 of the annular pipe 2a. The second annular pipe 2 (2b) having a length is connected by a reducing tee 3, and as a whole, the structure is almost a semicircular arc. With this configuration, the connecting portion between the annular pipes 2a and 2b and the thermal sleeve 4 is connected by the reducing tee 3 unlike the case where the existing junction box is applied.

  And in this embodiment, by using the core spray system piping 1 to which the reducing tee 3 is applied, unlike the existing core spray system piping, the annular pipe 2 (2a, 2b) of the core spray system piping 1 is used. The reducing tee 3 and the thermal sleeve 4 are attached to the furnace.

  As in the 1.1 million KW plant, in the reactor pressure vessel in which the nozzle of the reactor pressure vessel (see FIG. 15 “113 (113a, 113b)”) is not mounted at a 180 ° symmetrical position, the core spray system piping 1 As described above, when the thermal sleeve 4 is inserted into the nozzle 12, the core spray system piping to be carried in later may interfere with the previously carried in (see FIG. 15).

  On the other hand, in this embodiment, when there is a situation where the core spray system pipes 1 interfere with each other, the replacement core spray system pipe 1 is assembled by the following procedure.

  FIG. 2 is a cross-sectional view showing the basic structure of the safe end 13 applied in the present embodiment. As shown in FIG. 2, in this embodiment, first, the safe end 13 is attached to the existing nozzle 12 of the reactor pressure vessel by welding (welded portion (A)). In the welded portion between the safe end 13 and the nozzle 12, backside finishing is performed. Thus, considering that the back of the welded portion can be finished, the tip of the safe end 13 is limited to a length that does not block the welded portion.

  FIG. 3 is a cross-sectional view showing the internal structure of the safe end 13.

  As shown in FIG. 3, in this embodiment, a short pipe (thermal sleeve “I”) 14 is attached to the inner peripheral side of the safe end 13 by welding (welded portion (B)). By this short tube 14, the safe end 13 functions as a thermal sleeve at the distal end portion thereof. Regarding the axial length setting of the short pipe 14, the core spray system pipe 1 with the thermal sleeve 4 attached to the reducing tee 3 is carried into the furnace, and the other core spray system pipe carried in first and Avoid interference.

  Also, a core spray system piping dimension measuring jig (not shown) is carried into the furnace, the length dimension of the thermal sleeve 4 taking into account the distance to the short pipe 14 (I) after welding, the gap between the annular pipe 2 and the RPV 11 Perform in-furnace measurement.

  FIG. 4 is a plan view showing a basic configuration of an annular pipe applied in the present embodiment. As shown in FIG. 4, the thermal sleeve 4 is welded to the reducing tee 3 after the length of the thermal sleeve 4 is processed based on the measurement result. In this case, the length of the thermal sleeve 4 is limited to a length that can be inserted into the nozzle 12 in the furnace. In addition, the bending of the annular pipe 2 is corrected.

  FIG. 5 is a plan view showing a state where the riser pipe 5 is attached to the annular pipe 2 shown in FIG. 4, and FIG. 6 is a plan view showing a temporarily placed state of the core spray system pipe 1 applied in the present embodiment. It is. FIG. 7 is a plan view showing a state during welding of the core spray system pipe 1 shown in FIG.

  As shown in FIGS. 5, 6 and 7, the riser pipe 5 is welded through the 90 ° elbow 6 only on the short annular pipe 2 (2 b) side. In order to secure a space in the furnace where the core spray piping does not interfere with each other, the rising pipe 5 and the 90 ° elbow 6 on the long annular pipe 2 (2a) side are not assembled until they are carried into the furnace.

  The welded parts of the thermal sleeve 4, the annular pipe 2, the reducing tee 3 and the riser pipe 5 are class 2 piping ("safety related to water-cooled reactor facilities for testing and research") The pressure test and ultrasonic inspection (UT) or radiation transmission inspection (RT), which are the test requirements of the “Design Review Guidelines” and “Review Guidelines on the Classification of Importance of Safety Functions for Light Water Reactor Facilities for Power Generation”, are carried out.

  When the above procedure is completed, the annular pipe 2 (2a, 2b) as the core spray system piping is transferred to the site. The replacement core spray system piping is installed on site according to the following procedure.

  First, as shown in FIG. 6, the two furnace ring pipes 2 (2a, 2b) are carried into the furnace, and the thermal sleeve 4 is inserted into the nozzle 12 and temporarily placed therein.

  Next, as shown in FIG. 7 and FIG. 8, the riser pipe 5 and the 90 ° elbow 6 on the side of the two long annular pipes 2a are welded in the furnace in a temporarily placed state.

  Thereafter, the core spray system piping is replaced with a class 2 piping pressure test, and the annular pipe 2 and the 90 ° elbow 6 and the rising pipe 5 and the 90 ° elbow 6 are subjected to PPT and post-welding UT.

  Then, the thermal sleeve 4 inserted into the nozzle 12 and the short pipe (thermal sleeve I) 14 attached to the safe end 13 are welded from the outside of the opening portion of the nozzle 12.

  Thereafter, PPT of the thermal sleeve 4 and the short pipe (thermal sleeve I) 14 and post-welding UT are performed.

  Further, the inlet pipe on the core shroud side and the riser pipe 5 are welded via a sleeve. Thereafter, PPT of the inlet pipe and the rising pipe 5 and UT after welding are performed.

  According to this embodiment, even in a plant where the nozzle 12 is not in a 180 ° symmetrical position, such as a 1.1 million plant, the core spray system piping adopting the reducing tee 3 is attached by replacement work or construction work. Is possible.

  Then, the core spray system pipe 1 to which the reducing tee 3 is applied can be used again by exchanging the core spray system pipe 1 in which the aging or cracking phenomenon has occurred without interfering with each other.

  Further, by attaching the thermal sleeve 4 to the reducing tee 3 within a length range in which the core spray system pipe 1 can be inserted, the welding position of the short tube 14 and the thermal sleeve 4 is arranged closer to the outside of the nozzle 12. Therefore, welding becomes easy.

  In addition, since the reducing tee 3 can be adopted, the butt welding of the reducing tee 3 and the annular pipe 2 can be changed from the conventional discontinuous welding structure between the junction box and the annular pipe 2. It becomes a welded structure, and the reliability of equipment can be improved.

  Furthermore, since the weld line can be reduced by one place as compared with the junction box structure, the damage potential can be reduced.

Second Embodiment (FIG. 9)
FIG. 9 is a plan view showing a method of attaching the core spray system piping according to the second embodiment of the present invention. In the second embodiment, the following steps are changed from the first embodiment described above.

  That is, in the first embodiment described above, in order to prevent the core spray system pipes 1 from interfering with each other, the rising pipe 5 and the 90 ° elbow 6 of one or both of the core spray system pipes are assembled and welded in the furnace. It was decided.

  On the other hand, in this embodiment, assembly welding of the riser pipe 5 and the 90 ° elbow 6 is performed in advance in a factory, and then carried into the furnace. Then, the test of the welded part of the annular pipe 2 and the 90 ° elbow 6 and the rising pipe 5 and the 90 ° elbow 6 is performed in the furnace. This test method is UT or RT and pressure resistance test.

  Further, in order to prevent the core spray system pipe 1 to be carried in later from interfering with the pipe 2a carried in first, the core spray system pipe 2b to be carried in later can elastically deform the annular pipes 2 at both ends by the wires 21 or the like. It is carried into the furnace while being narrowed down to the inside of the furnace within a certain range, and inserted into the nozzle 12.

  In this case, the length of the thermal sleeve 4 attached to the reducing tee 3 is limited to a length that allows the thermal sleeve 4 to be inserted into the nozzle 12 in the above state. When the thermal sleeve 4 can be engaged with the safe end 13, the short pipe 14 is not necessary.

  In this embodiment as well, as in the first embodiment, it becomes possible to replace the core spray system pipe adopting the structure of reducing tee 3 by replacement work or construction work, and aging and cracking occur. The core spray system piping of the reducing tee 3 can be used again by replacing the core spray system piping that may interfere with each other without interfering with each other.

  Further, by attaching the thermal sleeve 4 to the reducing tee 3 within a length range in which the core spray system piping can be inserted, the welding position of the short pipe 14 and the thermal sleeve 4 becomes closer from the outside of the nozzle 12, so that welding is performed. Since the reducing tee 3 can be adopted, the reducing tee 3 and the annular pipe 2 can be butt welded from the discontinuous welded structure of the junction box and the annular pipe 2. It becomes a welded structure, and the reliability of equipment can be improved. Moreover, the welding line can be reduced by one place compared to the junction box structure, and the damage potential can be reduced.

[Third Embodiment] (FIG. 10)
FIG. 10 is a plan view for explaining a method of attaching the core spray system pipe according to the third embodiment of the present invention.

  In the first embodiment described above, the rising pipe 5 and the 90 ° elbow 6 of one or both of the core spray system pipes 1 are assembled and welded in the furnace so that the core spray system pipes do not interfere with each other.

  On the other hand, in this embodiment, the riser pipe 5 and the 90 ° elbow 6 are assembled and welded at the factory, transferred to the site after inspection, and carried into the furnace.

  Further, the long annular pipe 2 (2a) is not attached to the reducing tee 3 at the factory, and the thermal sleeve 4 attached to the reducing tee 3 is inserted into the nozzle 12.

  After being inserted into the nozzle 12, the long annular pipe 2 that is not attached is assembled and welded in the furnace. The test method of the welded part of the annular pipe 2 and the 90 ° elbow 6 and the rising pipe 5 and the 90 ° elbow 6 carries out PPT and post-weld UT as an alternative to the pressure test of class 2 piping.

  Since the thermal sleeve 4 can have a length up to the safe end 13, the thermal sleeve 4 and the safe end 13 can be directly welded, and the short tube 14 is not necessary.

  Also in this embodiment, the same operation and effect as in the above embodiment can be obtained.

[Fourth Embodiment] (FIG. 11)
FIG. 11 is a plan view for explaining a method of attaching the core spray system pipe according to the fourth embodiment of the present invention.

  In the present embodiment, the following steps are changed from the first embodiment. That is, in the first embodiment, the rising pipe 5 and the 90 ° elbow 6 of one or both of the core spray system pipes are assembled and welded in the furnace so that the core spray system pipe (ring pipe 2) does not interfere with each other. It was adopted.

  On the other hand, in this embodiment, the riser 5 and the 90 ° elbow 6 are welded at the factory, and after inspection of the class 2 piping, the weld is transferred to the site and carried into the furnace. In addition, the assembly of the annular pipe 2 and the reducing tee 3 is not performed at the factory, and only the annular pipe 2 is installed in the furnace.

  Note that the thermal sleeve 4 attached to the reducing tee 3 has a length to be engaged with the safe end 13. This is possible because the reducing tee 3 and the annular pipe 2 are not assembled in advance, and the core spray system piping does not interfere with each other.

  After inserting the thermal sleeve 4 into the nozzle 12, the reducing tee 3 and the annular pipe 2 are assembled and welded. The testing method for the welded part of the reducing tee 3 and the annular pipe 2 is PPT and post-weld UT as an alternative to the pressure test of class 2 piping.

  Since the thermal sleeve 4 can have a length up to the safe end 13, the thermal sleeve 4 and the safe end 13 can be directly welded, and the short tube 14 is not necessary.

  Also in the above method, the same operation and effect as the above embodiment can be obtained. Moreover, since the short pipe 14 becomes unnecessary, the number of welding lines is reduced as compared with the first embodiment, and the construction period can be shortened.

[Fifth Embodiment (FIG. 12)]
FIG. 12 is a plan view for explaining a method of attaching the core spray system pipe according to the fifth embodiment of the present invention.

  In the present embodiment, the following steps are changed from the first embodiment. That is, in the first embodiment, in order to prevent the core spray system pipes 1 and 1 from interfering with each other, the rising pipe 5 and the 90 ° elbow 6 of one or both of the core spray system pipes 1 and 1 are assembled and welded at the factory. It was decided to.

  On the other hand, in this embodiment, assembly welding of the riser pipe 5 and the 90 ° elbow 6 is performed at the factory, and after inspection of class 2 piping, it is transferred to the site and carried into the furnace. The annular pipe 2 is attached to the reducing tee 3 at the factory.

  Further, the thermal sleeve 4 attached to the reducing tee 3 is not assembled outside the furnace, and the core spray system pipe 1 is attached. The thermal sleeve 4 is attached in advance to the safe end 13 side.

  According to the present embodiment, since the welding position between the thermal sleeve 4 and the reducing tee 3 is on the back side when viewed from the nozzle 12, there is a possibility that the difficulty of welding may be increased, but as in the previous embodiment. As for the length of the thermal sleeve 4, since the length of the connection between the safe end 13 and the reducing tee 3 is taken into consideration, there is an advantage that the short pipe 14 is not necessary.

1 Core spray system piping 2 (2a, 2b) Ring pipe 3 Reducing tee 4 Thermal sleeve 5 Rising pipe 6 90 ° elbow 11 RPV
12 Nozzle 13 Safe end 14 Short tube 21 Wire 100 Reactor pressure vessel 101 Water supply nozzle 102 Furnace wall 103 Nozzle safe end 104 Thermal sleeve 105 Junction box 106 Core shroud 107 Core spray system piping 108 Semi-annular pipe portion 109 90 ° elbow 110 Rising pipe 111 Cover plate 112 Reducing tee 113 Nozzle 113a N5 nozzle 113b N16 nozzle

Claims (5)

In a method for mounting a core spray system pipe in which a pair of semicircular arc core spray system pipes are installed in a reactor pressure vessel of a boiling water nuclear power plant, a core cooling water injection nozzle provided in the core spray system pipe is a core Set to an arrangement excluding the 180 ° symmetrical position in plan view with respect to the center, 90 ° only at the part of the thermal sleeve divided by the T-shaped pipe joint and the end of the annular pipe and the annular pipe on the short side Installation method of core spray system piping characterized in that a core spray system pipe with a riser pipe attached via an elbow is carried into the furnace and installed, and a riser pipe attached to the long annular ring is installed in the furnace. . 2. The method of attaching a core spray system pipe according to claim 1, wherein an existing nozzle of the boiling water reactor is set so that a joint portion with a safe-end thermal sleeve is located outside a welded portion between the nozzle and the safe end. The method for attaching a core spray system pipe according to claim 2 , wherein a short pipe is attached to the safe end as a part of the divided thermal sleeve before the core spray system pipe is carried into the furnace. The method for attaching core spray system piping according to claim 1, wherein the riser pipe is welded via a 90 ° elbow only on the short annular pipe side outside the furnace. The method for mounting core spray system piping according to claim 1, wherein the two rising pipes on the side of the long annular pipe and the 90 ° elbow are welded in the furnace.

Images