JP2016075651A - Reactor pressure vessel and repair method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor pressure vessel capable of preventing a reactor core internal structure, which is disposed in the reactor pressure vessel, from getting damaged due to vibrations caused from a fluid and capable of reducing stress generated on the reactor core internal structure.SOLUTION: The reactor pressure vessel includes: a reactor pressure vessel body; plural in-furnace nuclear instrumentation guide tubes 28 which are vertically disposed on the furnace bottom 25 in the lower part of the core 13 in the reactor pressure vessel body; plural in-furnace nuclear instrumentation housings 29 each of which is coaxially connected to the lower part of the in-furnace nuclear instrumentation guide tubes 28 via a connection block 32 and a step part 33; and a connection beam 31 for coupling the neighboring in-furnace nuclear instrumentation housings 29 at the step part 33.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a reactor pressure vessel of a boiling water reactor and a method for repairing the reactor pressure vessel.

  In a boiling water reactor, a coolant (cooling water) is boiled in a reactor core in a reactor pressure vessel to form steam, which is sent to a turbine for power generation. The steam exiting the turbine is cooled and returned to water, and returned again as a coolant into the reactor pressure vessel. The coolant returned to the reactor pressure vessel is guided to the core through the bottom of the core below the core by a recirculation pump and a jet pump or an internal pump.

  At the bottom of the furnace, there are guide tubes and housings for storing control rods and in-core nuclear instrumentation (ie, control rod guide tubes, control rod drive mechanism housings, in-core nuclear instrumentation guide tubes, in-core nuclear instrument housings, etc.). Furnace in-furnace structures) are provided to stand. These guide tubes and housings are known to vibrate upon receiving fluid force from a coolant guided from the bottom of the furnace to the core.

  Patent Documents 1 and 2 disclose a structure that reduces the vibration of the reactor internal structure by reducing the turbulence of the flow of the coolant introduced to the reactor bottom by the internal pump.

JP 2004-233258 A JP-A-3-48797

  In the reactor pressure vessel of a boiling water reactor, even if the reactor internal structure vibrates due to the fluid force of the coolant introduced to the bottom of the reactor, the reactor internal structure may be damaged. Designed not to be. However, if the reactor power is increased or the equipment structure is installed to increase safety after the start of operation of the boiling water reactor, the flow conditions of the coolant at the bottom of the reactor will change. Further, there is a possibility that a change may occur in the vibration caused by the fluid force of the reactor internal structure provided in the reactor pressure vessel.

  The object of the embodiment of the present invention is made in consideration of the above-described circumstances, and reduces vibrations caused by fluid of the reactor internal structure provided in the reactor pressure vessel to prevent damage, or An object of the present invention is to provide a reactor pressure vessel and a method for reinforcing the same that can reduce the stress generated in the reactor internal structure.

  A reactor pressure vessel according to an embodiment of the present invention includes a reactor pressure vessel main body, a plurality of in-core nuclear instrumentation guide tubes respectively erected at a bottom of the reactor pressure vessel main body below the core, and the in-core A plurality of in-core nuclear instrumentation housings connected coaxially via connection portions and stepped portions below each of the instrumentation guide tubes, and connecting beams for connecting the adjacent in-core nuclear instrumentation housings at the stepped portions. It is characterized by comprising.

  Further, a method for refurbishing a reactor pressure vessel according to an embodiment of the present invention includes a plurality of in-core nuclear instrumentation guide tubes erected on the bottom of the reactor pressure vessel main body below the core, and the in-core nuclear instrumentation guide. A plurality of in-core nuclear instrumentation housings connected coaxially via a connecting portion and a stepped portion below each of the tubes; and in the vicinity of the in-core nuclear instrumentation housing and the in-core nuclear instrumentation guide tube at the bottom of the reactor In a method for repairing a reactor pressure vessel, comprising: a plurality of control rod guide tubes installed upright; and a control rod drive mechanism housing connected coaxially below each of the control rod guide tubes. The control rod guide tube connected to one of the drive mechanism housings is removed together with an internal control rod, and then the control rod guide tube and the control rod drive mechanism housing from which the control rods have been removed are removed. The connecting beam installation device is carried in through the opening of the core support plate that supports the core, and then the connecting beam installation device is operated by the control rod drive in which the control rod guide tube and the control rod are removed. The in-core nuclear instrumentation housing is connected to the stepped portion of the in-core nuclear instrumentation housing near the mechanism housing by fastening the connection beam carried through the opening of the core support plate. It is.

  Furthermore, a method for refurbishing a reactor pressure vessel according to an embodiment of the present invention includes a plurality of in-core nuclear instrumentation guide tubes respectively erected on the bottom of a reactor pressure vessel main body below the core, and the in-core nuclear instrumentation guide. A plurality of in-core nuclear instrumentation housings connected coaxially via connection portions and stepped portions below each of the tubes, and in the vicinity of the in-core nuclear instrumentation housing and the in-core nuclear instrumentation guide tube at the bottom of the reactor In a method for repairing a reactor pressure vessel, comprising: a plurality of control rod guide tubes installed upright; and a control rod drive mechanism housing connected coaxially below each of the control rod guide tubes. The control rod guide tube connected to one of the drive mechanism housings is removed together with an internal control rod, and then the control rod guide tube and the control rod drive mechanism housing from which the control rods have been removed The in-core nucleometer in the vicinity of the control rod drive mechanism housing from which the control beam guide tube and the control rod are removed is moved in the coolant by moving the floating beam connecting beam installation device. A connecting beam carried in through an opening of a core support plate that supports the core is fastened to the stepped portion of the mounting housing to connect the in-core nuclear instrumentation housing.

  According to the embodiment described above, the vibration caused by the fluid of the reactor internal structure provided in the reactor pressure vessel can be reduced.

The block diagram which shows the reactor pressure vessel which concerns on one Embodiment of this invention. The partial expanded side view which expands and shows a part of reactor bottom part in the boiling water reactor of FIG. Sectional drawing which follows the III-III line | wire of FIG. Sectional drawing which follows the IV-IV line | wire of FIG. 2 shows the relationship between the in-core nuclear instrumentation housing and the connecting beam in FIG. 2, (A) shows the state before installing the connecting beam, (B) shows the state after installing the connecting beam, and (C) shows the state of the connecting beam. Explanatory drawing which shows a fastening part in a cross-sectional state, respectively. FIGS. 2, 4, and 5 show an embodiment of the connecting beam, where (A) is a plan view and (B) is an exploded perspective view showing a fastening portion in an exploded state. FIG. The top view which shows the other form of the connection beam of FIG.2, FIG4 and FIG.5. The joint state of the fastener which comprises the fastening part of the connection beam shown in FIG.6 and FIG.7 is shown, (A) is a partial top view in the case of bolt joining, (B) is the case of welding joining. FIG. 6 and FIG. 7 are cases where the fasteners constituting the fastening portion of the connecting beam are joined using a shape memory alloy, (A) and (B) are before joining, and (C) is after joining. FIG. FIG. 2, FIG. 4 and FIG. 5 show the repair procedure of the reactor pressure vessel using the connecting beam, (A) is an explanatory diagram showing the installation status of the connecting beam installation device, and (B) is an illustration of the connecting beam by the connecting beam installation device. The XB arrow directional view of FIG. 10 (A) which shows an installation condition. Explanatory drawing which shows the case where the repair procedure of the reactor pressure vessel by the connection beam of FIG.2, FIG4 and FIG.5 is performed using the connection beam installation apparatus of another form.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing a reactor pressure vessel of a boiling water reactor according to an embodiment of the present invention. The reactor pressure vessel 11 houses a reactor core 13 in a reactor pressure vessel body 12, and a large number of fuel assemblies (not shown) constituting the reactor core 13 are surrounded by a shroud 14, and a reactor core support plate 15 and Supported by the upper grid plate 16. The upper part of the shroud 14 is closed by a shroud head 17, and a steam / water separator 19 is installed in the shroud head 17 via a stand pipe 18. A steam dryer 20 is disposed above the steam / water separator 19 in the reactor pressure vessel main body 12.

  The steam generated in the reactor core 13 is separated from the water by the steam separator 19, dried by the steam dryer 20, reaches the upper dome 21, passes through the main steam system from the main steam nozzle 22, and the turbine system (both (Not shown). The steam that has worked in the turbine system becomes condensate and is supplied as coolant (cooling water) 24 into the reactor pressure vessel main body 12 through the water supply nozzle 23. The coolant 24 is guided to the core 13 through a reactor bottom 25 below the core 13 in the reactor pressure vessel body 12 by a recirculation pump and a jet pump or an internal pump.

  As shown in FIGS. 1 to 4, the reactor bottom portion 25 of the reactor pressure vessel main body 12 has a plurality of control rod guide tubes 26 and control rod drive mechanisms which are reactor internal structures of the reactor pressure vessel 11. A housing 27 is provided upright and connected in a coaxial state with the control rod guide tube 26 facing upward. Further, a plurality of in-core nuclear instrumentation guide tubes 28 and an in-core nuclear instrumentation housing 29 which are the reactor internal structures of the reactor pressure vessel 11 are disposed at the bottom 25 of the reactor pressure vessel 11 with the in-core nuclear instrumentation guide tube 28 facing upward. Are connected in a coaxial state and are provided upright. The in-core nuclear instrumentation guide tube 28 and the in-core nuclear instrumentation housing 29 are disposed in the vicinity of the control rod guide tube 26 and the control rod drive mechanism housing 27.

  Here, a control rod (not shown) is accommodated in the control rod guide tube 26, and a control rod drive mechanism (not shown) is accommodated in the control rod drive mechanism housing 27. Further, in-core nuclear instrumentation guide tube 28 and in-core nuclear instrumentation housing 29 accommodate an in-core nuclear instrumentation device (not shown). Among these, the adjacent in-core nuclear instrumentation guide tubes 28 are supported by a stabilizer 30 arranged in the horizontal direction so that the posture is stabilized.

  By the way, the control rod guide tube 26 and the control rod drive mechanism housing 27 as well as the in-core nuclear instrumentation guide tube 28 and the in-core nuclear instrumentation housing 29 are subjected to fluid force by the coolant 24 flowing through the bottom 25. In a boiling water reactor equipped with a reactor pressure vessel 11, the flow of the coolant 24 flowing through the reactor bottom 25 by installing an equipment structure for increasing output or improving safety after the start of operation. Conditions may change. In the present embodiment, in particular, the in-core nuclear instrumentation guide tube 28 and the in-core nuclear instrumentation housing 29 are arranged such that the adjacent in-core nuclear instrumentation housing 29 is suppressed so that vibration is also suppressed by a change in the flow condition of the coolant 24. It connects using the connection beam 31 arrange | positioned under the stabilizer 30. FIG.

  That is, as shown in FIGS. 5 to 7, the connecting beam 31 includes a beam portion 31 </ b> A and fastening portions 31 </ b> B provided at both ends of the beam portion 31 </ b> A. The in-core nuclear instrumentation housing 29 is formed to have a larger diameter than the in-core nuclear instrumentation guide tube 28, and thus includes a stepped portion 33 in the vicinity of the connection portion 32 with the in-core nuclear instrumentation guide tube 28. The connecting beam 31 connects the adjacent in-core nuclear instrument housings 29 to each other by fastening the fastening portions 31B to the step portions 33 of the adjacent in-core in-core instrument housings 29.

  Here, as shown in FIGS. 6 and 7, the fastening portion 31 </ b> B of the connecting beam 31 includes a first fastener 34 and a second fastener 35, and the first fasteners 34 are joined and combined. Or the first fastener 34 and the second fastener 35 are joined and combined. The first fastener 34 is integrally formed with the beam portion 31 and is provided so as to be able to contact an angular range of 90 degrees around the step portion 33 of the in-core nuclear instrumentation housing 29. Further, the second fastener 35 is formed separately from the beam portion 31 </ b> A and is provided so as to be able to come into contact with an angular range of 90 degrees around the stepped portion 33 of the in-core nuclear instrument housing 29.

  Therefore, as shown in FIGS. 4 and 7, in the connecting beam 31, the four first fasteners 34 are joined around the entire circumference of the stepped portion 33 of the in-core nuclear instrument housing 29 to form a fastening portion 31 </ b> B. Thus, the in-core nuclear instrument housing 29 is connected to the other four adjacent in-core nuclear instrument housings 29.

  In addition, the coupling beam 31 is configured such that a total of four first fasteners 34 and second fasteners 35 are joined around the entire circumference of the stepped portion 33 of the in-core nuclear instrumentation housing 29 to form a fastening portion 31B. This in-core nuclear instrumentation housing 29 is connected to a maximum of three other in-core nuclear instrumentation housings 29 adjacent to each other. For example, in the connecting beam 31, one first fastener 34 and three second fasteners 35 are joined on the entire circumference of the step portion 33 of the in-core nuclear instrument housing 29 to form a fastening portion 31 </ b> B. Thus, the in-core nuclear instrument housing 29 is connected to another adjacent in-core nuclear instrument housing 29.

  As for the fastening part 31B of the connection beam 31, the 1st fasteners 34 or the 1st fastener 34 and the 2nd fastener 35 are joined using the volt | bolt 36 and the nut 37 which are shown to FIG. 8 (A). Consists of. Further, the fastening portion 31B of the connecting beam 31 is joined by welding forming the welded portion 38 shown in FIG. 8B, or the first fasteners 34 or the first fastener 34 and the second fastener 35 are joined together. It is composed by.

  Further, the fastening portion 31B of the connecting beam 31 includes a fitting projection 39 made of a shape memory alloy, as shown in FIG. 9, in which the first fasteners 34 or the first fasteners 34 and the second fasteners 35 are arranged. Is fitted into the fitting recess 40 and joined. As shown in FIGS. 9A and 9B, the fitting convex portion 39 is detachably inserted into the fitting concave portion 40 when the room temperature is applied (when the connecting beam 31 is installed). At the operating temperature (about 200 ° C.) of the boiling water reactor equipped with the reactor pressure vessel 11, it expands as shown in FIG. 9C and is firmly fitted into the fitting recess 40, and cannot be removed. .

  An installation method (procedure) for installing the connecting beam 31 as described above in the in-core nuclear instrumentation housing 29 will be described with reference to FIG.

  First, as shown in FIG. 10A, the control rod guide tube 26 connected to the control rod drive mechanism housing 27 in the vicinity of the in-core nuclear instrumentation housing 29 to be connected by the connecting beam 31 is accommodated inside. Remove with control rod made.

  Next, the control beam guide tube 26 and the control rod drive mechanism housing 27 from which the control rod has been removed are installed on the connection beam installation device 41 that can be remotely operated. In other words, the connecting beam installation device 41 includes, for example, a control rod drive mechanism housing in which the control rod guide tube 26 and the control rod are removed through the opening 42 formed in the core support plate 15 by removing the control rod guide tube 26. 27 is carried in from above, and is installed on the upper part of the control rod drive mechanism housing 27.

  Thereafter, as shown in FIG. 10B, the connection beam installation device 41 uses the arm 44 to hold the connection No. 31 carried in the suspended state through the opening 42 of the core support plate 15 by the connection beam conveying device 43. Then, the gripped connecting beam 31 is fastened to the stepped portion 33 of the in-core nuclear instrumentation housing 29 to be connected, so that the in-core nuclear instrumentation housing 29 to be connected is connected to each other by the connecting beam 31.

  Moreover, the other aspect of the installation method (procedure) which installs the connection beam 31 in the adjacent in-core nuclear instrumentation housing 29 is demonstrated using FIG.

  Also in this case, first, the control rod guide tube 26 connected to the control rod drive mechanism housing 27 in the vicinity of the in-core nuclear instrument housing 29 to be connected by the connecting beam 31 is removed together with the control rod accommodated therein. .

  Next, in the coolant 24 above the control rod guide tube 26 and the control rod drive mechanism housing 27 from which the control rod has been removed, the remotely floating submerged connecting beam installation device 45 is operated and its screw 46 is operated. Thus, for example, the opening 42 of the core support plate 15 is passed through and moved.

  Thereafter, the connecting beam installation device 45 uses the arm 44 to grip the connecting beam 31 carried in a suspended state through the opening 42 of the core support plate 15 by the connecting beam transport device 43 (see FIG. 10B). By fastening the gripped connecting beam 31 to the stepped portion 33 of the in-core nuclear instrument housing 29 to be connected, the in-core reactor instrumentation housing 29 to be connected is connected to each other by the connecting beam 31.

With the configuration as described above, according to the present embodiment, the following effects (1) and (2) are obtained.
(1) As shown in FIGS. 2 and 4, even when the flow condition of the coolant 24 flowing through the bottom 25 of the reactor pressure vessel 11 below the core 13 changes, the adjacent in-core nuclear instrument housing 29 is connected. Since they are connected by the beam 31, vibration due to the flow of the coolant 24 in the in-core nuclear instrument housing 29 and the in-core nuclear instrument guide tube 28 can be reduced. As a result, the in-core nuclear instrument housing 29 and the in-core nuclear instrumentation are reduced. Breakage of the guide tube 28 can be reliably prevented.

  (2) Since the connecting beam 31 is fastened to the stepped portion 33 in the vicinity of the connecting portion 32 of the adjacent in-core nuclear instrumentation housing 29 with the in-core nuclear instrumentation guide tube 28, the stepped portion 33 is fastened to the connecting beam 31. Stress concentration is suppressed by being reinforced by the portion 31B. As a result, the stress generated in the in-core nuclear instrument housing 29 can be reduced.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. It is included in the scope and gist of the invention, and is included in the invention described in the claims and the equivalent scope thereof.

11 Reactor pressure vessel 12 Reactor pressure vessel body 13 Core 15 Core support plate 24 Coolant 25 Reactor bottom 26 Control rod guide tube (reactor internal structure)
27 Control rod drive mechanism housing (reactor internal structure)
28 In-core nuclear instrumentation guide tube (reactor internal structure)
29 In-core nuclear instrumentation housing (reactor internal structure)
31 connection beam 31A beam part 31B fastening part 32 connection part 33 step part 34 first fastener 35 second fastener 36 bolt 38 welding part 39 fitting convex part 41, 45 connection beam installation device 42 opening

Claims (6)

A reactor pressure vessel body;
A plurality of in-core nuclear instrumentation guide tubes erected at the bottom of the reactor below the core in the reactor pressure vessel body;
A plurality of in-core nuclear instrument housings connected coaxially via a connecting portion and a stepped portion under each of the in-core nuclear instrumentation guide tubes;
A reactor pressure vessel comprising a connecting beam for connecting adjacent nuclear reactor instrumentation housings at the stepped portion. The connecting beam is configured to include a beam portion and fastening portions provided at both ends of the beam portion,
The fastening portion is in contact with a 90-degree angle range around the in-core nuclear instrumentation housing and is integrally formed with both ends of the beam portion, and a 90-degree angle range around the in-core nuclear instrumentation housing. 2. The reactor pressure according to claim 1, further comprising a second fastener in contact with each other, wherein the first fasteners are combined with each other or the first fastener and the second fastener are combined. container. In the connecting beam, four first fasteners are joined around the entire circumference of the in-core nuclear instrumentation housing to form a fastening portion, so that the in-core nuclear instrumentation housing is adjacent to four other in-core cores. The in-core nuclear instrumentation is configured by connecting to the instrument housing or by connecting a total of four first and second fasteners on the entire circumference of the in-core nuclear instrument housing to form a fastening portion. The reactor pressure vessel according to claim 2, wherein the reactor is configured to connect the housing with a maximum of three other in-core nuclear instrument housings. The fastening portion of the connecting beam is fastened between the first fasteners or between the first fastener and the second fastener using bolts, by welding, or at the operating temperature of the boiling water reactor. The reactor pressure vessel according to claim 2, wherein the reactor pressure vessel is configured to be joined by fitting using a shape memory alloy in a state. A plurality of in-core nuclear instrumentation guide tubes standing on the bottom of the reactor pressure vessel body below the core, respectively, and coaxially connected to each of the in-core nuclear instrumentation guide tubes via a connecting portion and a step portion A plurality of in-core nuclear instrumentation housings, a plurality of control rod guide tubes standing up in the vicinity of the in-core nuclear instrumentation housing and the in-core nuclear instrumentation guide tube at the bottom of the reactor, and the control rod guide tube A control rod drive mechanism housing connected coaxially below each of the reactor pressure vessels,
First, remove the control rod guide tube connected to any of the control rod drive mechanism housing together with the internal control rod,
Next, a connecting beam installation device is installed at the upper part of the control rod drive mechanism housing from which the control rod guide tube and the control rod have been removed, carried through an opening of a core support plate that supports the core, and installed.
Thereafter, the connecting beam installation device passes the opening of the core support plate into the stepped portion of the in-core nuclear instrumentation housing near the control rod drive mechanism housing from which the control rod guide tube and the control rod have been removed. A method of repairing a reactor pressure vessel, comprising: fastening the connected beam that is carried in and connecting the in-core nuclear instrumentation housing. A plurality of in-core nuclear instrumentation guide tubes standing on the bottom of the reactor pressure vessel main body, respectively, and coaxially connected to the lower part of the in-core nuclear instrumentation guide tube via connecting portions and step portions. A plurality of in-core nuclear instrumentation housings, a plurality of control rod guide tubes standing up in the vicinity of the in-core nuclear instrumentation housing and the in-core nuclear instrumentation guide tube at the bottom of the reactor, and the control rod guide tube A control rod drive mechanism housing connected coaxially below each of the reactor pressure vessels,
First, remove the control rod guide tube connected to any of the control rod drive mechanism housing together with the internal control rod,
Next, the floating rod connecting beam installation device is moved into the coolant above the control rod drive mechanism housing from which the control rod guide tube and the control rod have been removed,
Thereafter, the connecting beam installation device supports the core at the stepped portion of the in-core nuclear instrument housing near the control rod drive mechanism housing from which the control rod guide tube and the control rod have been removed. A method of repairing a reactor pressure vessel, comprising: fastening a connecting beam carried in through an opening of the core and connecting the in-core nuclear instrument housing.

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