JPS6358294A - Incore inspection device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a boiling water nuclear reactor (hereinafter referred to as BWR),
The present invention relates to an in-reactor inspection device for inspecting in-reactor substructures such as baffle plates or shroud supports in a nuclear reactor pressure vessel during use.

(Prior Art) In general, nuclear power plants, such as B'vVR plants, are required to periodically stop operation and perform maintenance inspections (hereinafter referred to as in-service inspections).

During this in-service inspection, the upper cover of the reactor containment vessel is removed to perform fuel inspection, fuel replacement, and visual inspection of the integrally welded core support structure and internal attachment structures to the reactor vessel. It is. This inspection during use is performed by remote control from above while the reactor pressure vessel and upper well are filled with pool water.

The above configuration has the following problems. In other words, among the integrally welded core support structures and internal attachment structures to the reactor pressure vessel, baffle plates, shroud support legs, and differential pressure detection/creeping water injection pipes will be inspected during the above period of use. It had become impossible to apply.

This is a pendant swelling submersible TV used for remote visual testing.
This is due to the inability of the camera to approach these structures.

(Problems to be Solved by the Invention) As described above, in the past, the problem was that the baffle plate, shroud support leg, and differential pressure detection/creeping water injection pipe could not be inspected during the period of use. However, the present invention was made based on this point, and its purpose is to inspect baffle plates, shroud support legs, and differential pressure detection/creeping water supply pipes during use. The object of the present invention is to provide an in-furnace inspection device that can perform the following.

[Structure of the Invention] (Means for Solving the Problems) That is, the in-reactor inspection device according to the present invention is suspended from above a reactor pressure vessel, and its upper and lower ends are suspended by a core support plate and a control rod drive mechanism housing. a multi-joint arm mechanism accommodated in the case so as to be freely protrusive and retractable; a multi-joint arm drive structure housed in the case and driving the multi-joint arm mechanism; and the multi-joint arm an optical head attached to the tip of the b1 structure, a decontamination head attached to the tip of the multi-joint arm mechanism, and a decontamination mechanism arranged outside the case and driving the decontamination head. It is characterized by leakage.

(Function) In other words, the case is suspended in a predetermined place from which the fuel assembly, fuel support fittings, 11 control rods, and control rod guide tubes have been removed, and this is placed between the core support plate and the control rod drive hoe structure housing. to be installed. Next, the multi-joint arm drive mechanism drives the multi-joint arm mechanism to bring the optical head and the decontamination head close to a predetermined inspection target location. Next, the decontamination head is driven by the decontamination mechanism to decontaminate the area to be inspected, and the area to be inspected is inspected via the optical head.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a diagram showing a state in which the in-core inspection apparatus according to this embodiment is suspended from above within a reactor pressure vessel 1.

A reactor well 2 is formed above the reactor pressure vessel 1 . Further, a reactor core 3 is installed within the reactor pressure vessel 1 in a state housed within a shroud 4 . core 3
is composed of a plurality of fuel assemblies 5 and control rods (not shown). Further, the core 3 is supported at its upper and lower ends by an upper grid plate 6 and a core support plate 7. A plurality of fuel support fittings 8 are attached to the core support plate 7, and the fuel assembly 5 is supported by the fuel support fittings 8.

A plurality of stub tubes 9 are welded and fixed to the lower end plate 1a of the reactor pressure vessel 1. This stub tube 9
A control rod drive unit housing 10 and a control rod guide tube 11 are disposed above the control rod drive unit. Further, a differential pressure detection/water distribution water injection pipe 12 is disposed through the lower mirror 4N1a. The lower end of the shroud 4 is fixed to the reactor pressure vessel 1 via a plurality of shroud support legs 13 and a baffle plate 14.

The control IfI guide tube 11 connects the core support plate 7 and the control rod drive! Its upper and lower ends are supported by a JJv1 structure housing 10. That is, on the upper surface of the core support space 7, as shown in FIG.
A recess 16 is formed at the upper end of the control mechanism housing 10 to seat the lower end of the 1.11 steel rod guide tube 11.

Reference numeral 17 in FIG. 1 is an operating floor, and a workbench 18 is movably installed on this operating floor 17. A furnace inspection device 2, which will be described later, is suspended from this workbench 18 via a wire 19.

Note that the reference symbol @20a in the figure is a cable winding reel for winding up the cable 19a, and the reference symbol 20b is a power supply device.

Next, the configuration of the furnace inspection device 2 will be explained. Second
The figure shows the configuration of the in-furnace inspection Vt station, in which reference numeral 22 indicates an upper case, and reference symbol @23 indicates a lower case. Both the upper case 22 and the lower case 23 have a cylindrical shape, and are installed so as to be rotatable with respect to each other. The wire A719 is connected to the upper end of the upper case 22, and an upper end support portion 25 is provided protruding from the upper pH side. This upper end support portion 25 engages with the control rod guide tube fixing pin 15.

The lower case 23 is formed with a window 27 through which the separate multi-jointed arm 26 can enter and exit. Further, a lower end support portion 28 is rotatably installed at the center of the lower end. This lower end support portion 28 is seated in the recess 16 . Further, the multi-joint arm structure 26 is connected to the multi-joint arm drive mechanism 31 housed in the lower case 23 via two parallel bins 29 and 30.
is connected to. The above-mentioned multi-joint arm structure 26 is an ITI
It is composed of an arm 32, a second arm 33, and a third arm 34, and an optical head 35 consisting of a micro TV camera and a decontamination head 37 are attached to the tip of the third arm 34. This decontamination head 37 is the fifth
It is configured as shown in the figure. Reference numeral 38 in the figure represents an outer case, and a fixed brush 39 is attached to the lower end of this outer case 38. The fixed brush 39 is used to place the decontamination head 37 against the curved lower head plate 1a of the reactor pressure vessel 1 without any gap and seal it.

Further, an impeller 40 is disposed within the outer case 38, and a rotating brush 41 is attached to the lower end of the impeller 40. Further, a suction hose 42 and a discharge hose 43 are connected to the outer case 38.

Further, as shown in FIG. 1, a decontamination device 51 is installed at the bottom of the reactor well 2. This decontamination device 51 has a configuration as shown in FIG.

Reference numeral 52 in the figure is a base, and a pump 53 and a filter 54 are installed on this base 52.

The pump 53 is connected to the suction hose 42 and the discharge hose 43. Further, a hose 57 is branched from this discharge hose 56 and connected to the filter 54 . In the figure, reference numerals 58 and 59 are on-off valves. Driving water is supplied to the impeller 40 of the decontamination head 37 through the discharge hose 4, thereby rotating the rotating brush 41.

The operation will be explained based on the above configuration.

(1) First, as a preparation step for arranging the in-core inspection device 21, the fuel assembly 5, fuel support fittings 8, control rods not disclosed, and control rod guide tubes 11 at the relevant positions are removed.

-Secondly, the furnace inspection device 21 is suspended from the workbench 18 via the wire 19. Then, the lower support portion 28 is seated in the recess 16 of the control shaft drive rock structure housing 11 through the insertion holes formed in the upper grid plate 6 and the core support plate 7. At the same time, the upper support portion 25 is engaged with the control rod guide tube fixing pin 15 of the core support plate 6. As a result, the upper case 22 of the furnace inspection device 21 is installed in a state where its rotation is restricted, and the lower case 23 is installed in a state where its rotation is allowed.

■Next, the multi-joint arm drive mechanism 31 is driven to move the multi-joint arm i+M26 housed in the lower case 23 to the window 2.
7 to the outside of the lower case 23 and move it downward. As a result, the optical head 35 as shown in FIG.
Then, the decontamination head 37 is brought close to the lower end welded portion (indicated by symbol a in the figure) of the shroud support leg 13.

(2) Next, the decontamination device 51 is driven to supply driving water to the impeller 40 in the outer case 38 of the decontamination head 37 via the discharge hose 43. This causes the rotating brush 41 to rotate via the impeller 40.

Due to the action of the rotating brush 41, the clarad deposited on the welded portion a of the shroud support leg 13 is removed, resulting in a clean state. The removed crud is suctioned through suction hose 42.

Also, part of the water discharged from the pump 53 is discharged from the discharge hose 4.
3 to the decontamination head 27, and the rest is supplied to the decontamination head 27 via piping 57.
is supplied to a filter 54, where cladding and the like are removed. In this state, a remote visual test is performed via the optical head 35.

(2) Inspect the desired locations (baffle plate 14, differential pressure detection/creeping water-resistant water injection pipe 12, etc.) using the same action.

According to this embodiment, the following effects can be achieved.

■Firstly, shroud support leg 13 and baffle plate 1, which were conventionally considered impossible to inspect during use.
4, and the differential pressure detection/acid aqueous water pipe 12 can be inspected during the period of use.

■Also, since the remote visual test is performed with the inspection target area decontaminated by the decontamination device 51 and the decontamination head 37 attached to the tip of the multi-jointed arm Isosugi 26, highly accurate inspections can be carried out. Zuko can do it.

■Also, when the furnace inspection device 21 is installed, the lower case 2
3 is in a rotatable state and uses a multi-joint arm mechanism 26, making it possible to inspect a wide range.

■Also, the fixed brush 39 connects the decontamination head 37 and the lower mirror plate 1a.
Since the space between the cladding and the cladding can be effectively sealed, the cleaning effect can be enhanced and the scattering of the cladding can be prevented.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and for example, a jet nozzle may be installed in the decontamination head 37 instead of the rotating brush 41. A similar effect can be achieved with a configuration in which the cladding is removed by spraying jet water through this jet nozzle. In this case, as a method of supporting the reaction force of the jet water, it is also possible to use a support structure from the control guide pipe 11 or the like.

Also, in the decontamination mechanism 51, the filter 54 is connected to the discharge hose 4.
3 may be inserted.

[Effects of the Invention] As detailed above, according to the furnace inspection device according to the present invention, it is possible to inspect shroud support legs, baffle plates, differential pressure detection, and crawling acid water pipes during use, which was previously considered impossible. This is extremely effective in maintaining the integrity of structures and improving plant safety.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing one embodiment of the present invention.
The figure is a sectional view showing the in-core inspection device inserted into the reactor pressure vessel, Figure 2 is a front view of the in-core inspection device, and Figure 3 is a front view of the in-core inspection device.
The figure is a sectional view showing the state of inspection by the in-furnace inspection device, FIG. 4 is a front view of the decontamination device, and FIG. 5 is a sectional view of the decontamination head. 1... Reactor pressure vessel, 7... Core support plate, 10.
... Control shaft drive structure housing, 21 ... Furnace inspection device. 22... Upper case, 23... Lower case, 26.
...Multi-joint arm mechanism, 31...Multi-joint arm drive!
3I stripes, 35... optical head, 37... decontamination head, 51... decontamination mechanism. Applicant's agent Patent attorney Takehiko Suzue 1st Prisoner Figure 252 3rd Prisoner 4th Prisoner 2: Figure X5

Claims (3)

[Claims] (1) A case that is suspended from above the reactor pressure vessel and whose upper and lower ends are supported by the core support plate and the control rod drive mechanism housing, and a multi-joint arm mechanism that is housed in this case so that it can move in and out. a multi-joint arm drive mechanism housed in the case and driving the multi-joint arm mechanism; an optical head attached to the distal end of the multi-joint arm mechanism; and an optical head attached to the distal end of the multi-joint arm mechanism. An in-furnace inspection device comprising: a decontamination head; and a decontamination mechanism disposed outside the case and driving the decontamination head. (2) The case consists of an upper case and a lower case, the multi-joint arm mechanism and the multi-joint arm drive mechanism are housed in the lower case, and the lower case is rotatably supported by the control rod drive mechanism housing. An in-furnace inspection device according to claim 1, characterized in that: (3) The decontamination head has a rotary brush equipped with an impeller, and the decontamination mechanism rotates the rotary brush by supplying driving water to the impeller. The in-furnace inspection device according to item 1.