JP2000162376A - Replacing method for reactor internal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve work efficiency by separately performing cutting and replacing of a guide rod, supply water sparger, shroud support, etc., having peculiar structures into an in-air state and an underwater state. SOLUTION: In a replacing method for in-core structure for replacing reactor internal structure consisting of a reactor pressure vessel 1, a guide bracket 19 attached to the reactor pressure vessel inner wall and a guide bracket 18 welded to the guide bracket, a supply water sparger 15 attached by penetrating the reactor pressure vessel and core spray piping 14, a shroud support 2 attached in cone shape to the reactor pressure vessel inner wall and a flow baffle 5 formed in one body with the shroud support, a part of the guide rod underwater state is cut and removed and then the remaining guide rods are cut and removed from the guide bracket in-air state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for replacing a reactor internal structure, and more particularly to a method for replacing a reactor internal structure including a guide rod, a water supply sparger, a core spray pipe and a shroud support in a reactor pressure vessel. The present invention relates to a method of replacing a furnace internal structure to be replaced with a newly manufactured furnace internal structure or the like.

[0002]

2. Description of the Related Art Structures in a nuclear reactor may deteriorate over time when operated for a long period of time, and cracks may occur. In order to prevent such an event, it is desirable to replace the deteriorated furnace internals.

[0003] Conventionally, regarding the method of replacing the furnace internals,
JP-A-8-86896 and JP-A-10-132
As disclosed in Japanese Patent No. 985, after the inside of a furnace is chemically cleaned, a shroud, an upper grid plate, a core support plate, a jet pump, and the like are cut and removed, and then a replacement method for attaching a new furnace internal structure is performed. It has been known.

[0004]

The conventional replacement method described above is a method for replacing a reactor internal structure in a nuclear reactor having a general structure, and includes a guide bracket attached to an inner wall of a reactor pressure vessel and the guide. A feed rod sparger and core spray pipe having a structure such as a guide rod welded to a bracket, a fit, and the like, and a unique structure having a conical shroud support attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support It is not a technology related to a structural reactor.

[0005] That is, the above-mentioned prior art discloses a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe having a unique structure, and a cone formed on the inner wall of the reactor pressure vessel. No consideration is given to a method of replacing a reactor internal structure having a unique structure having a shroud support attached to a shape and a flow baffle formed integrally with the shroud support.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in view of the above circumstances, and has been made in view of the above circumstances. Provide a way.

[0007]

The present invention employs the following means in order to solve the above-mentioned problems.

A reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a feedwater sparger and a core spray pipe attached through the reactor pressure vessel; In a method for replacing a reactor internal structure comprising a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support, the method for replacing a reactor internal structure includes the steps of: After a part of the rod is cut and removed, the remaining guide rod is cut and removed from the guide bracket in the air state.

In the method for replacing a reactor internal structure for replacing the nuclear reactor internal structure, the step of cutting and removing the guide rod from the guide bracket, which is performed in the air, comprises suspending the guide rod from above the reactor pressure vessel. It is performed in a shielded body.

Also, a reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel A method for replacing a reactor internal structure comprising a shroud support conically mounted on the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support, wherein the water supply sparger Further, after cutting and removing a part of the core spray pipe, the remaining part is removed in the air state.

In the method for replacing a reactor internal structure for replacing a reactor internal structure, the step of cutting and removing a part of the water supply sparger and the core spray pipe is performed in the air.

In the method for replacing a reactor internal structure for replacing a nuclear reactor internal structure, the step of cutting and removing a part of the water supply sparger and the core spray pipe is performed in water.

In the method for replacing an internal structure of the reactor for replacing the internal structure of the reactor, the step of removing the water supply sparger and the core spray pipe, which is performed in the aerial state, comprises suspending the reactor pressure vessel from above. It is performed in a shielded body.

A reactor pressure vessel, a guide bracket mounted on the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe mounted through the reactor pressure vessel. Wherein the shroud support is replaced with a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support. Is characterized in that cutting is performed so as to avoid an intermediate weld formed in an intermediate portion of the shroud support, and the intermediate weld is removed together with the flow baffle.

Also, a reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel Wherein the shroud support is replaced with a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support. Cuts off the intermediate weld formed in the intermediate part of the shroud support, removes the intermediate weld together with the flow baffle, and then forms a new thick shroud support integrally formed with the flow baffle with the shroud. Attach the support to the pressure vessel side by welding. The features.

In the method for replacing a reactor internal structure for replacing a nuclear reactor internal structure, the remaining portion of the shroud support on the pressure vessel side and the welding side end of the new shroud support are grooved. And

[0017]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing an example of a procedure of a method of replacing a reactor internal according to the present embodiment, and FIG. 2 is a cross-sectional view of a reactor pressure vessel and a reactor internal to which the present invention is applied. .

In FIG. 2, reference numeral 1 denotes a reactor pressure vessel, 2 denotes a conical shroud support mounted on the inner surface of the reactor pressure vessel 1 by welding, and 3 denotes an annular shroud support ring mounted on the shroud support 2 by welding. Reference numeral 4 denotes a cylindrical shroud attached to the shroud support ring 3 by welding, and reference numeral 5 denotes a shroud support 2.
This is a flow baffle attached by welding.

6 is a core support plate for supporting the fuel, 7 is an upper lattice plate for supporting the upper part of the fuel, 8 is a fuel support, 9 is a control rod, 10 is a control rod guide tube, 11 is an in-core guide tube,
Reference numeral 12 denotes a differential pressure detection / boric acid water injection pipe, and these structures are installed in the shroud 4. 13 is a fuel, 14 is a core spray pipe, 15 is a water supply sparger, 16 is a shroud head / water separator, 17 is a steam dryer, and 18 is a guide when inserting the furnace internals into the pressure vessel. Guide rods, which are located above the core shroud 4.

Reference numeral 19 denotes a guide rod bracket for attaching the guide rod to the inner wall of the pressure vessel. Reference numeral 20 denotes a reactor pressure vessel upper cover (see FIG. 4, FIG. 2 shows a state where the guide rod is removed).
1 is a control rod drive mechanism, 22 is a control rod drive mechanism housing, 23 is an in-core housing, 24 is a dry tube / LPRM detector, 25 is an in-core stabilizer, 2
6 is a core spray thermal sleeve, 27 is a water supply sparger thermal sleeve, 28 is a core spray nozzle safe end, 29 is a water supply nozzle, and 30 is a water supply nozzle safe end.

Next, a procedure of a method of replacing the internal structure of the nuclear reactor having the above configuration will be described below.

(1) First, the procedure shown in step 1 of FIG. 1 will be described with reference to FIG. FIG. 3 is a diagram illustrating removal of the furnace internals. In the following drawings, the same portions are denoted by the same reference numerals, and description thereof will be omitted.

In step 1, the reactor well is filled with water, and a steam dryer 17, a shroud head / water separator 16, a fuel 13, a fuel The support bracket 8, the control rod 9, the control rod guide tube 10 and the like are removed and stored in a temporary facility installed at a predetermined place such as a fuel pool.

(2) Next, the procedure shown in step 2 of FIG. 1 will be described with reference to FIG. FIG. 4 is a view for explaining chemical cleaning in the furnace. In step 2, reference numeral 30 denotes a chemical cleaning device for mixing the chemical agent into the reactor water with the pressure vessel upper lid 20 attached, and circulates the reactor water mixed with the chemical agent into the furnace by a recirculation pump (not shown). This removes the inside of the furnace.

(3) Next, the procedure shown in step 3 of FIG. 1 will be described with reference to FIGS. FIG. 5 is a view for explaining the cutting of the guide rod, and FIG. 6 is a view for explaining the details of the cutting of the guide rod. In FIG. 6, reference numeral 31 denotes a welded portion between the guide rod 18 and the guide rod bracket 19, and 32 denotes a guide rod. A body cutting position 33 is a guide rod mounting welding portion cutting position. Guide rod 18
Since it is difficult to cut the welded portion 31 between the mounting bracket 31 and the guide bracket 19 by underwater remote control, in step 3, first, a diver approaches underwater remote control or underwater to cut the guide rod body. Cut at location 32. The worker cuts the attachment weld 31 by approaching it in the air in a later step described later. By cutting in two stages in this way, it is possible to improve the work efficiency, shorten the process, and reduce the cost as compared with the one-stage operation by underwater remote operation or underwater diver.

(4) Next, the procedure shown in step 4 of FIG. 1 will be described with reference to FIGS. FIG. 7 is a view for explaining the cutting of the upper grid plate and the vertical pipe portion of the core spray pipe, FIG. 8 is a view for explaining the cutting of the upper part of the shroud, and FIG.
FIG. 10 is a diagram illustrating removal of a core support plate, FIG. 10 is a diagram illustrating cutting of an in-core guide tube, a stabilizer, and the like, and FIG. 11 is a diagram illustrating cutting of a lower portion of a shroud.

In FIG. 7, reference numeral 34 denotes a connection between the water supply sparger and the thermal sleeve, and reference numeral 14a denotes a core spray pipe 14;
The vertical pipe section 14b is a vertical pipe section cutting position of the core spray pipe.

In step 4, before removing the water supply sparger 15 and the core spray pipe 14, the upper grid plate 7,
This is a step of removing the shroud 4, the core support plate 6, the in-core guide tube 11, and the differential pressure detection / boric acid water injection pipe 12.

The reactor to which the present invention is applied has a long operating year, and the water supply sparger 15 and the core spray pipe 14 are activated because their mounting positions are closer to the core region than other reactors. High radiation dose.

When removing the water supply sparger 15 and the core spray pipe 14 having a high radiation dose as described above, the reactor is usually operated in a state where the activated shroud 4, the upper lattice plate 7, the core support plate 6, etc. are installed. The water level is lowered to the core area, and then a shield is installed on the upper part of the shroud to reduce the atmospheric dose equivalent rate in the furnace, and the water supply sparger 15 and the core spray pipe 14 are cut and removed in the air, or underwater remote control. A method of cutting and removing by operation is adopted. However, the former method has a problem that the construction period is long, and the latter method has a problem in terms of the construction period and cost.

In view of the above, the present invention provides a water supply sparger and a part of the core spray pipe, that is, the shroud 4.
After cutting the fixed part, shroud 4
Then, the core support structure is cut and removed, and then the water supply sparger and the rest of the core spray piping are removed in the air.

In the step of cutting and removing a part of the water supply sparger and the core spray pipe, a shield is hung from the upper part of the pressure vessel while the reactor water level is in the upper part of the core area, and cut and removed in the air. Alternatively, a shield may be provided on the upper part of the shroud so that the diver can approach and cut off the underwater.

That is, in this step, first,
As shown in FIG. 7, the upper lattice plate 7 is detached by cutting its fastening portion. Next, the portion fixed to the shroud 4 of the vertical pipe portion 14a of the core spray pipe 14 is cut at the cutting position 1.
Cut and remove at 4b. By this step, a clearance between the water supply sparger 15 and the core spray pipe 14 necessary for removing the upper part of the shroud 4 can be secured.

Next, as shown in FIG.
At the center and remove the top.

Next, as shown in FIG.
And the core support plate 6 is removed.

Next, as shown in FIGS. 10 and 11, the in-core guide tube 11, the in-core stabilizer 25,
The differential pressure detection / boric acid water injection pipe 12 and the lower part of the shroud 4 are cut and removed.

(5) Next, the procedure shown in step 5 of FIG. 1 will be described with reference to FIGS. FIG. 12 is a diagram illustrating removal and cutting of a core spray pipe, a water supply sparger and a guide rod, FIG. 13 is a diagram illustrating cutting of a guide rod, FIG. 14 is a diagram illustrating removal of a water supply sparger, and FIG. 15 is a water supply sparger It is a figure explaining the connection part after removal.

In FIG. 12, 35 is an upper core shield suspended from the upper part of the pressure vessel, and 36 is a temporarily closed lid. FIG.
In the drawing, reference numeral 37 denotes a pull-out jack.

In step 5, the reactor water level is lowered to the upper part of the core region, the core shield 35 is suspended from the upper part of the pressure vessel 1, and the guide rod 18 is suspended in the air as shown in FIG.
At the cutting position 33, the welding portion 31 between the guide bracket 19 and the mounting weld 31 is cut and removed.

Further, as shown in FIGS. 14 and 15, cutting of the fastening portion of the water supply sparger 15 and pulling out of the thermal sleeve 27 are performed.

As shown in FIG. 14, the water sparger 15
Are connected to the water supply sparger thermal sleeve 27 by an interference fit method. In this structure, the water supply sparger 15 can be pulled out by the pull-out jack 37.

As shown in FIG. 15, after the water supply sparger 15 has been pulled out, the connection portion is checked for soundness and reused.
Or replace with a new one.

As for the core spray pipe 14,
First, cut the pipe outside the furnace.
6 and the welded portion of the core spray nozzle safe end 28 are cut off, and then the core spray pipe 14 is pulled out. At this time, a temporary closing lid 36 for the reactor water seal is welded to the external pipe.

When a part of the water supply sparger and the core spray pipe is taken out by a diver in close proximity, structural members such as the upper lattice plate 7, shroud 4, core support plate 6, incore guide tube 11, incore stabilizer 25, etc. When there is a shield, a shield is installed above the shroud.

(6) Next, the procedure shown in step 6 of FIG. 1 will be described with reference to FIG. FIG. 16 is a diagram for explaining the installation of the furnace wall shield.

In the drawing, reference numeral 38 denotes a furnace wall shield which is divided and arranged inside the furnace wall, 39 denotes a furnace wall shield support which supports the furnace wall shield 38, 40 denotes a furnace bottom scaffold, and 40a denotes a furnace bottom scaffold 40. This is a support for supporting the flow baffle 5 which is arranged at the bottom.

In step 6, the reactor water level is raised to below the flange of the reactor pressure vessel 1, and the reactor water is drained while cleaning the inside of the reactor. Thereafter, the reactor water level is raised to below the flange of the reactor pressure vessel 1, and a divided furnace shield 38 is installed inside the inner wall of the pressure vessel 1.

Next, the furnace water level was lowered to the bottom of the pressure vessel 1, and the inside of the furnace was in an air state, and a furnace bottom scaffold 40 was installed.
Make it accessible to workers.

Next, a support 40a for supporting the flow baffle 5 is installed.

(7) Next, the procedure shown in step 7 of FIG. 1 will be described with reference to FIGS. 17 and 18. FIG. 17 is a diagram illustrating a cutting position and a groove processing position of the shroud support, and FIG. 18 is a diagram illustrating a groove processing of the shroud support.

In these figures, 41 is a shroud support intermediate weld, 42 is a shroud support intermediate weld cutting position, 43 is a shroud support groove working position,
44 is a shroud support beveling device. In addition,
Shroud support 2 can be used when it is necessary to clarify the distinction between existing and new shroud supports.
a, New shroud support is indicated by 2b.

In step 7, the intermediate welded portion 42 of the existing shroud support 2a is cut in the air by a method such as plasma cutting, and the shroud support is removed integrally with the flow baffle except for a part on the pressure vessel side.

Next, a beveling process for attaching and welding a new shroud support to the remaining end of the existing shroud support 2a on the pressure vessel side is performed.

The existing shroud support 2a is welded at the intermediate weld, and there is a heat affected zone due to the intermediate welding near the intermediate weld, and it is necessary to remove this heat affected zone.

For this reason, upon plasma cutting of the intermediate weld, the end of the intermediate weld 37 is detected by an ultrasonic flaw detection method or a corrosion method, and further, taking into account the range affected by heat, A shroud support cutting position 42, a cutting range thereof, and a shroud support groove processing position 43 are set, and lines indicating these positions are marked.

In the case of the first groove forming for mounting and welding with the new shroud support 2b, first, the height of the processing position is determined based on the upper end surface of the control rod drive mechanism housing 22 located at the center of the reactor pressure vessel 1. , And the groove processing is performed by the shroud support groove processing device 44. The processing position by the processing device 44 can be measured by the processing device.

The groove position data obtained in this way is used as groove processing data for the new shroud support, and the groove surface of the new shroud support 2b is left on the pressure vessel side of the existing shroud support 2a. It can match the groove surface formed at the end.

(8) Next, the procedure shown in step 8 of FIG. 1 will be described with reference to FIGS. 19 illustrates the installation of the new shroud support and the flow baffle, FIG. 20 illustrates the structure of the new shroud support, FIG. 21 illustrates the inner welding of the new shroud support, and FIG. 22 illustrates the new shroud support. It is a figure explaining outside welding.

In FIG. 21, reference numeral 45 denotes a shroud support inner welding device for welding the inside of the shroud support,
In FIG. 22, reference numeral 46 denotes a shroud support outside welding device for welding the outside of the shroud support. Also,
Reference numeral 2b denotes the new shroud support described above, and its plate thickness is formed larger than the plate thickness of the existing shroud support 2a.

In step 8, the groove of the new shroud support integrally formed with the flow baffle is welded to the groove of the existing shroud support 2a.

Next, the work of improving the residual stress by welding is performed on the welded portion and the heat affected portion of the existing shroud support 2a and the new shroud support 2b.

FIG. 20 is a diagram showing the structure of the new shroud support. In the drawing, the thickness of the new shroud support 2b is made larger than the thickness of the existing shroud support 2a in order to facilitate alignment of the groove surface of the existing shroud support 2a with the groove surface of the new shroud support 2b. ing.

By increasing the plate thickness of the new shroud support 2b, even if the groove processing surface of the existing shroud after the groove processing is not a perfect circle and the shroud support 2a is radially misaligned, The misalignment can be absorbed by the thickness of the new shroud support 2b.

The processing dimensions of the groove portion of the new shroud support 2b can be pre-processed at the factory in accordance with the amount of misalignment of the groove size measurement result of the existing shroud support 2a. After the processing, a new shroud support 2b
Is integrated with the new shroud support ring 3 and the flow baffle 5 and aligned and attached to the existing shroud support 2b. By this method, even if the existing shroud support is misaligned, the groove of the new shroud support 2b can be reliably aligned with the groove surface of the existing shroud support 2a. In addition, since it is integrated with the new shroud support ring 3 and the flow baffle 5 and aligned and attached to the existing shroud support 2b, the construction period can be shortened as compared with split installation.

FIG. 21 is a view showing a state where the groove of the new shroud support 2b is aligned with the groove of the existing shroud support 2a and the welding surface is welded by the inner welding device 45 for the shroud support.

FIG. 22 is a view showing a state in which the groove of the new shroud support 2b is aligned with the groove of the existing shroud support 2a, and the welding surface is welded by the outer welding device 46 for the shroud support.

(9) Next, the procedure shown in step 9 of FIG. 1 will be described with reference to FIG. FIG. 23 is a diagram illustrating the groove processing of the new shroud support ring.

After the new shroud support 2b is attached to the existing shroud support 2a and welded, the upper surface of the shroud support ring 3 is grooved in order to mount the new shroud 4, and the dimensions after the processing are measured.

At the time of beveling of the upper surface of the shroud support ring 3, the control rod drive mechanism housing 22 located at the center of the reactor pressure vessel 1 is determined on the basis of the height of the processing position, similarly to the beveling of the existing shroud support 2 a. Is processed by the shroud support beveling machine 44, and dimension measurement after the processing is performed.

(10) Next, the procedure shown in step 10 of FIG. 1 will be described with reference to FIG. FIG. 24 is a diagram illustrating installation of a new shroud.

In the drawing, reference numeral 47 denotes a phytoup device for supporting a new shroud 4 so as to be adjustable in position; 48, a lower template; 49, an upper template; 50, a misalignment between the new shroud and a predetermined control rod drive mechanism housing 22; Core measuring device for measuring, 51 is a new shroud 4
An outer shroud welding device for welding the shroud support ring 3 to the shroud support ring 52 is a furnace elevating device.

In step 10, the new shroud 4 is placed on the fit-up device 47 and loaded onto the shroud support ring 3.
The center of the shroud 4 is seated on the shroud support ring 3 by welding the shroud 4 to the inner periphery and the outer periphery of the shroud 4 by adjusting the center of the shroud 4 with the predetermined control rod drive mechanism housing 22 by the core measuring device 50 and the core measuring device 50.

(11) Next, the procedure shown in step 11 of FIG. 1 will be described with reference to FIG. FIG. 25 is a diagram illustrating installation of a new in-core guide tube, a stabilizer, and the like.

In the figure, reference numeral 53 denotes water extending under the upper flange of the new shroud 4 in the annulus between the reactor pressure vessel 1 and the new shroud 4, and the water is supplied to the atmosphere dose equivalent rate in the reactor. To reduce.

In step 11, after the in-core housing 23 is beveled in the above water-filled state,
Weld a new incore guide tube. Next, the in-core stabilizer 25 is attached and welded.

Further, the differential pressure detection / boric acid water injection pipe 12 is similarly attached and welded.

(12) Next, the procedure shown in step 12 of FIG. 1 will be described with reference to FIG. FIG. 26 is a diagram illustrating installation of a new core support plate.

In step 12, the core support plate 6 is loaded into the furnace with the annulus filled with water in the same manner as in the previous step, and the core is adjusted with a predetermined control rod drive housing 22, and the fixing bolts are fixed. Tighten and perform installation.

After the installation of the core support plate 6, the inside of the body of the new shroud 4 is filled with water to a position below the lower flange thereof in order to reduce the atmospheric dose equivalent rate in the furnace.

(13) Next, the procedure shown in step 13 of FIG. 1 will be described with reference to FIG. FIG. 27 is a diagram illustrating the installation of a new upper lattice plate.

In step 13, the upper lattice plate 7 is carried into the furnace, the core is adjusted with the fuel rod hole of the predetermined core support plate 6, and the fixing bolts are tightened for installation.

After the upper lattice plate 7 is installed, water is filled under the upper flange of the new shroud 4 in order to reduce the atmospheric dose equivalent rate in the furnace.

(14) Next, the procedure shown in step 14 of FIG. 1 will be described with reference to FIG. FIG. 28 is a diagram for explaining the installation of a new core spray tube and a guide rod.

In the figure, reference numeral 54 denotes an upper shield provided on the new shroud 4.

In step 28, the core upper shield 5
2 is placed on top of the new shroud 4. Next, the core spray pipe 14 is carried in, adjusted in position, and welded to the core spray nozzle safe end 28, the vertical pipe part 14a of the core spray pipe 14 on the new shroud 4 side, and installed.

Further, the outer pipe of the furnace is installed by welding to the core spray nozzle safe end 28.

Further, with the upper core shield 54 suspended from the upper flange of the reactor pressure vessel 1, the position of the new guide rod 18 is adjusted on the groove processing surface of the guide rod bracket 19, and the installation is performed by welding. .

(15) Next, the procedure shown in step 15 of FIG. 1 will be described with reference to FIG. FIG. 29 is a diagram illustrating installation of a water supply sparger.

In step 15, the water supply sparger 1
5 is carried in, the position is adjusted, the water supply sparger thermal sleeve is loosened to widen the diameter, and the water supply sparger 15 is inserted and installed.

(16) Next, the procedure shown in step 16 of FIG. 1 will be described with reference to FIG. FIG. 30 is a diagram illustrating the final appearance inspection and performance inspection of the replacement device.

In step 16, after the replacement of the shroud 4 and other furnace internals is completed, a final appearance inspection and performance inspection of the replacement equipment are performed.

(17) Next, the procedure shown in step 17 of FIG. 1 will be described with reference to FIG. FIG. 31 is a diagram for explaining the installation confirmation of the furnace internals.

Step 17 is a final restoration step, in which the control rod guide tube 10, the fuel support 8, the control rod 9, the control rod drive mechanism 21, the dry tube
The installation of the LPRM detector 24, the loading of the fuel 13, the installation of the shroud head, the steam separator 16, and the steam dryer 17 are performed, and the installation in the furnace is checked.

[0095]

As described above, according to the present invention, the cutting and replacement of the guide rod, the water supply sparger, the shroud support and the flow baffle having the unique structure are performed separately in the operations in the aerial state and the underwater state. ,
The replacement work can be simplified, the work efficiency can be improved, the process can be shortened, and the cost can be reduced. Further, the replacement work can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a procedure of a method of replacing a furnace internal structure according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a reactor pressure vessel and reactor internals.

FIG. 3 is a view showing a procedure shown in step 1 and is a view for explaining removal of a furnace internal structure.

FIG. 4 is a view showing a procedure shown in step 2 and is a view for explaining chemical cleaning in a furnace.

FIG. 5 is a view showing a procedure shown in step 3, and is a view for explaining cutting of a guide rod.

FIG. 6 is a view showing a procedure shown in step 3 and is a view for explaining details of cutting of a guide rod.

FIG. 7 is a view showing a procedure shown in step 4, and is a view for explaining cutting of a vertical pipe portion of an upper lattice plate and a core spray pipe.

FIG. 8 is a view showing a procedure shown in Step 4, and is a view for explaining cutting of an upper portion of the shroud.

FIG. 9 is a view showing a procedure shown in step 4 and is a view for explaining removal of a core support plate.

FIG. 10 is a view showing a procedure shown in step 4, and is a view for explaining cutting of an in-core guide tube, a stabilizer, and the like.

FIG. 11 is a view showing a procedure shown in step 4 and is a view for explaining cutting of a lower part of the shroud.

FIG. 12 is a view showing a procedure shown in Step 5, and is a view for explaining removal and cutting of a core spray pipe, a water supply sparger, and a guide rod.

FIG. 13 is a view showing a procedure shown in step 5 and is a view for explaining cutting of a guide rod.

FIG. 14 is a view showing a procedure shown in Step 5, and is a view for explaining removal of a water supply sparger.

FIG. 15 is a view showing a procedure shown in Step 5, and is a view for explaining a connection portion after removing a water supply sparger.

FIG. 16 is a view showing a procedure shown in Step 6, and is a view for explaining how to attach a furnace wall shield.

FIG. 17 is a view showing a procedure shown in step 7, and is a view for explaining a cutting position and a groove processing position of the shroud support.

FIG. 18 is a view showing a procedure shown in step 7, and is a view for explaining a groove processing of a shroud support.

FIG. 19 is a view showing a procedure shown in Step 8, and is a view for explaining installation of a new shroud support and a flow baffle.

FIG. 20 is a view showing a procedure shown in step 8 and is a view for explaining a structure of a new shroud support.

FIG. 21 is a view showing a procedure shown in step 8 and is a view for explaining inside welding of a new shroud support.

FIG. 22 is a view showing a procedure shown in step 8 and is a view for explaining outer welding of a new shroud support.

FIG. 23 is a view showing a procedure shown in step 9 and is a view for explaining a groove processing of a new shroud support.

FIG. 24 is a diagram showing a procedure shown in Step 10, and is a diagram for explaining installation of a new shroud.

FIG. 25 is a view showing a procedure shown in step 11, and is a view for explaining installation of a new in-core guide tube, a stabilizer, and the like.

FIG. 26 is a view showing a procedure shown in Step 12, and is a view for explaining installation of a new core support plate.

FIG. 27 is a view showing a procedure shown in step 13 and is a view for explaining installation of a new upper lattice plate.

FIG. 28 is a view showing a procedure shown in step 14, and is a view for explaining installation of a new core spray pipe and a guide rod.

FIG. 29 is a diagram showing a procedure shown in step 15 and is a diagram for explaining installation of a water supply sparger.

FIG. 30 is a view showing a procedure shown in step 16, and is a view for explaining final appearance inspection and performance inspection of the replacement device.

FIG. 31 is a view showing a procedure shown in step 17 and is a view for explaining a confirmation of installation of a furnace internal structure.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reactor pressure vessel 2 shroud support 3 shroud support ring 4 shroud 5 flow baffle 6 core support plate 7 upper lattice plate 8 fuel support fitting 9 control rod 10 control rod guide pipe 11 incore guide pipe 12 differential pressure detection / boric acid water injection pipe DESCRIPTION OF SYMBOLS 13 Fuel 14 Core spray pipe 14a Vertical pipe section of core spray pipe 14b Cutting position of vertical pipe section of core spray pipe 15 Water supply sparger 16 Shroud head / water separator 17 Steam dryer 18 Guide rod 19 Guide rod bracket 20 Pressure vessel top lid 21 Dying rod drive mechanism 22 Control rod drive mechanism housing 23 In-core housing 24 Dry tube / LPRM detector 25 In-core stabilizer 26 Core spray thermal sleeve 27 Water supply spray thermal sleeve 28 Core spray Spill-safe end 29 Water supply nozzle 30 Chemical cleaning device 31 Mounting welding part 32 Guide rod body cutting position 33 Guide rod mounting welding part cutting position 34 Connection part between water supply sparger and thermal sleeve 35 Core upper shield 36 Temporary closing lid 37 For pull-out Jack 38 Furnace wall shield 39 Furnace wall shield support 40 Furnace bottom scaffold 41 Shroud support intermediate weld 42 Shroud support intermediate weld cutting position 43 Shroud support groove processing position 44 Shroud support groove processing device 45 Shroud support inner welding device 46 Shroud support outer welding device 47 Fit-up device 48 Lower template 49 Upper template 50 Core measuring device 51 Shroud outer welding device 52 Furnace elevating device 53 Water for shielding 54 Upper shield

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 000005441 Babcock Hitachi, Ltd. 2-4-1, Hamamatsucho, Minato-ku, Tokyo (72) Inventor Toshikazu Kikuchi 3-2-2, Sachimachi, Hitachi-shi, Ibaraki Hitachi Inside Nuclear Engineering Co., Ltd. (72) Inventor Tsukasa Ikegami 3-1-1, Sachimachi, Hitachi City, Ibaraki Prefecture Within Hitachi Works, Ltd.Hitachi Plant (72) Inventor Harumasa Fukumitsu Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi 1-1, Hitachi, Ltd., Hitachi Plant (72) Inventor Fumio Kikuchi 3-1-1, Sakaimachi, Hitachi, Ibaraki Prefecture, Hitachi, Ltd. Hitachi Plant, Hitachi, Ltd. (72) Inventor Fumio Manabe, Kure, Hiroshima Prefecture 3-36, Ichitakara-cho Babkotsuk Hitachi Kure Factory (72) Inventor Junichi Kawabata 3-1-1 Sakaicho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. In the standing plant (72) inventor samurai Akira Hitachi City, Ibaraki Prefecture Saiwaicho Third Street No. 2 No. 2 stock company Hitachi engineering in the service

Claims (9)

[Claims] 1. A reactor pressure vessel, a guide bracket attached to an inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel. A method for replacing a reactor internal structure comprising: a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support; After cutting and removing a part of the guide rod,
A method for replacing a reactor internal structure, comprising cutting and removing a remaining guide rod from a guide bracket in an air state. 2. The atom according to claim 1, wherein the step of cutting and removing the guide rod from the guide bracket, which is performed in the air state, is performed in a shield suspended from the upper part of the reactor pressure vessel. How to replace the furnace internals. 3. A reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel. A method of replacing a reactor internal structure comprising: a shroud support conically mounted on the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support; And a method for replacing a reactor internal structure, comprising cutting off a part of a core spray pipe and removing the remaining part in the air. 4. The method according to claim 3, wherein the step of cutting and removing a part of the water supply sparger and the core spray pipe is performed in the air. 5. The method according to claim 3, wherein the step of cutting and removing a part of the water supply sparger and the core spray pipe is performed in water. 6. The shield according to claim 3, wherein the step of removing the water supply sparger and the core spray pipe, which is performed in the air state, is performed by a shield suspended from an upper part of the reactor pressure vessel. A method for replacing a reactor internal structure, wherein 7. A reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel. A method for replacing a reactor internal structure comprising a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support, wherein the shroud support comprises: A method for replacing a reactor internal structure, comprising cutting off the intermediate weld formed in the intermediate portion of the shroud support, and removing the intermediate weld together with the flow baffle. 8. A reactor pressure vessel, a guide bracket attached to the inner wall of the reactor pressure vessel, a guide rod welded to the guide bracket, a water supply sparger and a core spray pipe attached through the reactor pressure vessel. A method for replacing a reactor internal structure comprising a shroud support conically attached to the inner wall of the reactor pressure vessel and a flow baffle formed integrally with the shroud support, wherein the shroud support comprises: Cuts off the intermediate weld formed in the intermediate part of the shroud support, removes the intermediate weld together with the flow baffle, and then forms a new thick shroud support integrally formed with the flow baffle with the shroud To be attached to the rest of the support on the pressure vessel side by welding METHOD replacement reactor internal structure characterized. 9. The reactor according to claim 8, wherein the remaining portion of the shroud support on the pressure vessel side and the welding-side end portion of the new shroud support are grooved so that the groove surfaces are aligned. How to replace internal structures.