JPS593397A - Cleaning device for incore monitor housing and guide tube - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cleaning device for cleaning the interior of an in-core monitor housing and guide tube.

[Technical background of the invention]

In general, a boiling water reactor (hereinafter referred to as BWR) has a large number of control rod drive mechanism housings (hereinafter referred to as CHD housing) 2 that penetrate through the bottom wall 1a of a reactor pressure vessel 1, as shown in FIG. are installed, these CRDs
A control rod guide tube 3 is connected to the housing 2 . The control rod is driven up and down in the control rod guide tube 3 by a control rod drive mechanism (hereinafter referred to as CHD) installed in the CHD housing 2. Still a reactor pressure vessel! A cylindrical shroud 4 is housed therein, and an upper grid plate 5 is provided at the upper end of the shroud 4, and a core support plate 6 is provided at the lower end. A fuel assembly (not shown) is loaded between the upper grid plate 5 and the core support plate 6.

In addition, an in-reactor neutron flux monitor (hereinafter referred to as an in-core monitor) 7 is provided in order to grasp the neutron flux distribution state within the reactor during reactor operation. This in-core monitor 7 is inserted into the reactor core through an in-core monitor housing (hereinafter simply referred to as in-core housing) 8 and an in-core monitor guide tube (hereinafter simply referred to as in-core guide tube) 9, as shown in FIG. The head 7a of the in-core monitor 70 is fitted into the locking recess 10 of the upper lattice plate 5 to stand upright. The head 71L is configured to be able to project upwardly into the main body 7b, and is heated by the spring 1 in the projecting direction. The lower stepped portion 7b of the in-core monitor 7 is connected to the in-core housing 8.
It comes in contact with the inner seat portion 12a of the in-core flange 12 to form a self-shield to prevent the outflow of reactor water.

The in-core monitor 7 having the above configuration is replaced with a new in-core monitor 7, for example, at the time of periodic inspection.

At this time, before installing the new in-core monitor 7, the inside of the in-core housing 8 and the in-core guide tube 9 are cleaned. This is because there is a possibility that the inside of the in-core housing 8 and the in-core guide tube 9 are contaminated with slurry-like crud such as radioactive fine dust containing oxidized metals and scale, especially the seat portion 12a of the in-core flanz 12. If cracks and dots adhere to the inner portion of the monitor 7, there is a risk that the seat with the lower stepped portion 7b of the in-core monitor 7 may be incomplete and a seat leak may occur. Therefore, before installing a new in-core monitor 7 during periodic inspection, the inside of the in-core housing 8 and the in-core guide tube 9 are cleaned to remove the crud. As a cleaning method, for example, attach a drainage device (not shown) from below the Incoano 1 Uging IIIK.
Reactor water is allowed to flow down into the in-core guide pipe 9 and the in-core housing 8 by opening the on-off valve of the drainage device.

The structure is such that the crud inside the in-core guide pipe 9 and the in-core nozzle puffer 8 is removed by the flowing down of this reactor water.

Also, when fixing the in-core flange 12 to the in-core housing 8, the bolts 13 are carefully tightened. aK Prevent scratches from occurring.

[Problems with background technology]

With the above configuration, it may not be possible to reliably remove the cladding, and if the cladding remains on the seat portion 12a of the in-core flange 12, the bolts 13 must be tightened carefully, prolonging the work and requiring more labor. Considering the radiation exposure, etc., it is necessary to definitely remove rad.

[Purpose of the invention]

An object of the present invention is to be able to reliably remove crud in the in-core guide pipe and the in-core guide pipe, thereby shortening the work time required for removing the crud and further reducing the work time required for replacing the in-core monitor. An object of the present invention is to provide a cleaning device for an in-core monitor housing and a guide tube that can reduce radiation exposure for personnel.

[Summary of the invention]

The in-core monitor housing and guide tube cleaning device according to the present invention cleans the in-core from above the reactor core.

A knob-shaped main body installed so as to be able to enter and exit the monitor guide pipe and in-core monitor housing sink, a wash water supply mechanism connected to the upper part of the main body and supplying washing water into the main body, and a wash water supply mechanism provided at the bottom end of the main body. a cleaning nozzle provided on the main body, a positioning member provided on the main body to position the main body through engagement with the core structure, and a cleaning water containing removed crud provided on the in-core monitor housing detachably from below. The structure is equipped with a drainage device for draining water.

That is, for example, at the time of periodic inspection, before installing a new Incore monitor, the main body is placed into the Incore monitor guide pipe and the Incore monitor housing, and washing water is supplied to the main body from the washing water supply mechanism and then the Incore monitor is supplied through the washing nozzle to the main body. Clean the inside of the monitor guide tube and in-core monitor housing.

Therefore, the cladding inside the in-core monitor guide pipe and the in-core monitor housing can be reliably removed, and in particular, the cladding on the seat part of the in-core 7 lange can be reliably removed, so the tightening of the in-core flange, which was done carefully in the past, can now be done easily. The time required can be shortened, and the time required for removing dirt and dust can also be shortened, reducing radiation exposure of workers and improving safety.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 3 to 6. 3 to 6 are diagrams showing the configuration of the cleaning device. In the figure, 21 indicates the main body of the cleaning device. This main body 21
The incore monitor 7 and the hill have the same shape, and the gripping tool 2
2 is suspended from above the core and inserted into the in-core guide tube 9 and the in-core housing 8. A wash water supply mechanism 23 is connected to the upper part of the main body 21, which includes a hook, a pipe joint 24, a water hose 25, a submersible YJP pump (not shown), and the like. A cleaning nozzle 26 is installed at the lower end of the main body 21 on the in-core flange 1.
A plurality of them are formed in the circumferential direction so as to face the second seat portion 12h. Further, an insertion guide 27 is provided to protrude below the main body 21. This insertion guide 27 connects the main body 2 to the in-core guide tube 9 and the in-core housing 8.
The upper part of this insertion guide 27 protrudes into the main body 21 and adjusts the washing water jet from the washing nozzle 26 appropriately. That is, the main body 21 of the gripper 22 is suspended and inserted into the inner core guide tube 9 and the inner core housing 8.

At that time, the quick pipe fitting 24 and water hose 25
In this configuration, cleaning water is supplied into the main body 21 from a submersible pump connected through a submersible pump, and is injected from a cleaning nozzle 26 to clean the inside of the in-core guide pipe 9 and the in-core housing 8 to remove crud. Further, the main body 21 is provided with a positioning member 2 pa 8, and when the main body 21 is inserted into the in-core guide tube 9 and the in-core housing 8, this positioning member comes into contact with the upper surface of the core support plate 6, thereby positioning the main body 21. This is the configuration that determines the At this time, the cleaning nozzle 26 of the main body 2 is configured to face the seat portion 12m of the in-core flange 12. In addition, 29 in the figure shows the joint fittings,
29B indicates a guide. This is the ID 29B and the main body 2
1 and the in-core housing 8.

The first gripper 22 is constructed as shown in FIG.

In the figure, numeral 30 denotes a latch portion which is made by dividing a long cylinder into several pieces, each of which has a spring characteristic, and grips the head portion 7m of the in-core monitor 7. A guard sleeve 3 is provided on the outer periphery of the latch portion 30 to allow the latch portion 30 to open. The latch portion 30 and the guard sleeve 31 are connected by the connecting portion 32 and the hoist mechanism (
(not shown).

Next, the drainage device 34 will be explained with reference to FIG.

In the figure, 35 indicates a drain pipe connected to the in-core 7 flange 12. This drain pipe 35 is connected via a connector 36 and a quick pipe fitting 37? - Le pulp 38 is connected.

A transparent hose 40 is connected to this ball pulp 38 via a hose fitting 39.
0 is piped to Radpit 41.

In other words, the above? -Open Leparve 38 and in-core guide tube 9
The cleaning water containing the crud removed in the in-core housing 8 is drained to the Radvit 41.

At this time, the structure is such that the removed cladding can be confirmed by visually observing the transparent boss 40.

The operation of the in-core monitor housing and guide tube cleaning device configured as above will be explained. For example, the in-core monitor 7 is replaced during periodic inspection. At that time, first, the drain pipe 35 is connected to the in-core 7 run (12) and the drain device 34 is installed. At this time, the pole valve 38 is closed.

Next, the existing in-core monitor 7 is pulled out using a puller (not shown). Then, the main body 21 of the cleaning device is inserted into the suspended Incore guide tube 9 and the Incore pipe 8 using the hoist mechanism via the gripping tool 22. At that time, from the submersible pump to the water hose 25 and the pipe joint 2
Cleaning water is supplied into the main body 21 through the cleaning nozzle 2.
6 to remove the cladding inside the in-core guide pipe 9 and the in-core housing 8. Then, open the front Me pole valve 38 and pour the cleaning water containing Claratra into the Rad Pit 4.
Drain to 1. At this time, the removed crud can be confirmed by visually observing the transparent hose 40, and it can be seen that the crud has been reliably removed by cleaning. When the main body 21 is further inserted, the positioning member 28 comes into contact with the core support plate 6, and the insertion of the main body 21 is stopped. At this time, the cleaning nozzle 26 is placed at a position opposite to the seat portion 12hK of the in-core 7 flange 12, so that the seat portion 12h can be cleaned and dirt and grime can be reliably removed.

When the transparent hose 40 is visually observed and it is determined that the crud removal has been completed, the cleaning is stopped and the goal valve 38 is closed. Then, the main body 21 is pulled up and a new in-core monitor 7 is installed.

In other words, when replacing the in-core monitor during periodic inspection, the drain device 2' is connected to the lower part of the in-core housing 8, and the main body 2I is inserted from above the core into the in-core guide pipe 9 and the in-core housing 8, and at that time, cleaning water is supplied from the submersible pump. is supplied and injected from the cleaning nozzle 26 to clean the in-core guide pipe 9 and the in-core housing 8 and remove the crud.

Therefore, the crud can be removed more reliably than in the conventional cleaning method, such as by letting reactor water flow down. When the cleaning nozzle 26
The cladding of the seat portion 12a can be reliably removed by placing it at a position facing the seat portion 12a of the Fi-in core flange 12. This eliminates the trouble of having to carefully tighten the delts 13 when connecting the in-core flange 12 to the in-core housing 8, and the working time is also shortened. In addition, the time required for work similar to cleaning work is also shortened, and the exposure of workers to radiation can also be reduced.

Note that the same items are indicated by the same reference numerals.

〔Effect of the invention〕

The in-core monitor housing and guide tube cleaning device according to the present invention includes a pipe-shaped main body that is provided so as to be able to enter and exit the in-core monitor guide pipe and the in-core monitor housing from above the reactor core, and a cleaning device that is connected to the upper part of the main body and has a cleaning water inside the main body. a cleaning nozzle provided at the lower end of the upper main body; a positioning member provided in the main body for positioning the main body in connection with the core structure; and the in-core monitor housing. The structure includes a drainage device that is detachably installed from below and drains the cleaning water containing the removed crud.

That is, for example, during periodic inspections, before installing a fragile Incore monitor, the main body is placed into the Incore monitor guide pipe and the Incore monitor housing, and washing water is supplied to the main body from the washing water supply mechanism through the washing nozzle. Clean the inside of the Incore monitor guide tube and Incore 7 lunge housing.

Therefore, the crud inside the in-core monitor guide pipe and the in-core monitor housing can be reliably removed, and especially the crud on the seat part of the in-core flange can be reliably removed, so the tightening of the in-core flange, which has been done carefully in the past, can be done. The benefits include being able to shorten the time required for the work, reduce the time required for the crud removal work, reduce radiation exposure for workers, and even improve safety.

[Brief explanation of drawings]

Figures 1 and 2 refer to the explanation of the conventional example.
The figure shows a part of the configuration of the reactor, Figure 2 shows how the in-core monitor is installed, Figures 3 to 6 show a simple embodiment of the present invention, and Figure 3 shows the main body and FIG. 4 and FIG. 5 are partially enlarged views of FIG. 3, and FIG. 6 is a diagram showing the configuration of a drainage device. 7... In-core monitor, 8... In-core monitor housing, 9... In-core monitor guide pipe, 2... Main body, 11... Washing water supply mechanism, 26... Washing nozzle, 28... - Positioning member, 34... drainage device. Respondent's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Procedure amendment RSS 5%, "'s2". 2 Director General Kazuo Wakasugi Indication of patent application No. Sho G7-112979 Law Name Incore Monitor...Relationship with the case of person who corrects cleaning equipment for cleaning and guide pipes Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. Agent address: No. 17 Mori Building, 26t5, Toranomon 1-chome, Minato-ku, Tokyo Subject: Akasu, tl, l Kosho Completely corrected detailed statement of contents (no changes to the contents) 497-

Claims (2)

[Claims] (1) A pipe-shaped main body that is pressurized to be able to enter and exit the in-core monitor guide pipe and the in-core monitor housing from above the reactor core, a wash water supply mechanism that is connected to the upper part of this main body and supplies wash water into the main body, and the above-mentioned a cleaning nozzle provided at the lower end of the main body; a positioning member provided on the main body for positioning the main body by fitting with a core structure;
A cleaning device for an in-core monitor housing and a guide pipe, characterized in that the in-core monitor housing is provided with a drainage device that is removably attached to the in-core monitor housing from below and drains cleaning water containing removed crud. (2) The cleaning nozzle is provided so as to face the seat portion of the in-core monitor housing and the in-core monitor with the main body positioned on the positioning part side. 2. The in-core monitor housing and guide tube cleaning device according to item 1.