JPH0797150B2 - Pressure plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention, when inspecting the inner surface of an in-core monitor housing that accommodates a neutron instrumentation tube (in-core monitor) in a boiling water reactor, The present invention relates to a pressure resistant plug that seals an arbitrary position above the inner surface of an in-core monitor housing to prevent leakage of reactor water and enables inspection of the inner surface of the in-core monitor housing.

(Prior Art) Generally, in a boiling water reactor, a rod-shaped neutron instrumentation tube, that is, an in-core monitor is placed between the fuel assemblies in order to keep the neutron flux in the reactor in an appropriate distribution state during operation. It is installed to monitor the distribution of neutron flux.

This in-core monitor uses the extension force of the spring installed at the upper end of the in-core monitor to engage the top part of the in-core monitor guide tube and the in-core monitor housing with the lower part of the in-core monitor engaging the intersection of the upper lattice plate in the furnace. Inserted in. The lower end of the incore monitor is supported by abutment formed on an incore monitor flange fixed to the lower end of the incore monitor housing via an O-ring. This seat is mirror-finished and is in close contact with the lower end of the in-core monitor to prevent leakage of reactor water.

(Problems to be Solved by the Invention) By the way, since oxides and the like adhere to the inner surface of the in-core monitor housing, periodic inspections are carried out for cleaning the adhered oxides and the like. When inspecting the inner surface of the incore monitor housing, it is necessary to temporarily shut off the inside of the reactor pressure vessel and the incore monitor guide tube to prevent the discharge of reactor water. In this case, conventionally, a seal member is attached to the upper part of the in-core monitor guide tube to prevent the reactor water from leaking.

However, it is difficult to completely seal the reactor water, and it is impossible to mount the seal member at an arbitrary position on the inner surface of the in-core monitor housing. Moreover, since pressure cannot be applied to the inside of the incore monitor housing, it has not been possible to confirm a leak from the wall surface of the incore monitor housing or the incore monitor flange at the lower end thereof. Furthermore, if the inspection work takes a long time, there is a risk that the worker will receive a large amount of radiation exposure.

The present invention has been made in consideration of the above circumstances, and when the inner surface of the in-core monitor housing is inspected, it can be freely attached to any position on the inner surface of the in-core monia housing and can completely seal the reactor water. It is also an object of the present invention to provide a pressure resistant plug capable of confirming a leak from the wall of the in-core monitor housing or the flange of the in-core monitor safely, reliably and easily, and preventing the radiation exposure of the worker. .

[Structure of Invention]

(Means for Solving the Problems) According to the present invention, a pressure-resistant seal that can be tightly sealed to the inner peripheral surface of an in-core monitor housing, and a coupling for guiding and mounting the pressure-resistant seal at an arbitrary position in the in-core monitor housing. A rod and a connecting mechanism for detachably connecting the pressure-resistant seal and the connecting rod are provided, and the pressure-resistant seal is equipped with a pressure-resistant packing around the rod shaft,
A collar is provided which deforms the pressure resistant packing by being rotated around the rod shaft so as to be brought into close contact with the inner peripheral surface of the in-core monitor housing. The connecting rod is airtight and slides on the sleeve fixed to the in-core monitor flange. The double shaft is movably held, and the inner shaft is hermetically and slidably held by the outer pipe. The upper end of the outer pipe is connected to the collar, while the upper end of the inner shaft is connected. Is connected to the rod shaft, and the sleeve is formed with a water pressure supply port capable of supplying pressurized water into the in-core monitor housing.

(Operation) Connect the pressure-resistant seal to the tip of the connecting rod via the connecting mechanism,
Secure the sleeve to the in-core monitor flange. Then, the double shaft is slid on the sleeve and is inserted upward in the in-core monitor housing. With the pressure-resistant seal reaching a predetermined position in the in-core monitor housing by the insertion, the inner shaft is fixed, while the outer tube is rotated, and the collar connected to the upper end of the outer tube is rotated. When the collar rotates, the pressure-proof packing deforms and comes into close contact with the inner peripheral surface of the in-core monitor housing, and the pressure-proof seal is attached. This pressure-resistant seal can completely prevent leakage of reactor water and can secure a complete seal even when pressure is applied to the in-core monitor housing.

After mounting the pressure-resistant seal, it is possible to confirm leakage from the in-core monitor housing wall or the in-core monitor flange by supplying pressurized water from the water pressure supply port formed in the sleeve. Further, the connecting rod can be removed by the connecting mechanism with the pressure-proof seal attached, and the inner surface of the in-core monitor housing can be inspected. Therefore, the inspection work of the in-core monitor housing can be efficiently performed, and the radiation exposure dose of the worker can be reduced.

(Example) An example of a pressure plug according to the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 6, a core shroud 12 provided integrally with a reactor pressure vessel 11 containing a core portion 10 and cooling water.
, A core support plate 13 is provided horizontally, and the core support plate 13
An in-core monitor housing 14 is fixed to the bottom portion 11a of the reactor pressure vessel 11 located below the base 11a through the base 11a. At the top of this incore monitor housing 14 is an incore monitor guide tube.
15 are integrally connected, and the upper end of the in-core monitor guide tube 15 penetrates the core support plate 13 to form an upper opening 15a.

An incore monitor 16 is removably inserted into the upper opening 15a of the incore monitor guide tube 15.
The upper part of is engaged with the lower side of the intersection of the upper grid plate 17. The lower end of the incore monitor 16 is located on the incore monitor housing 14
It is abutted and supported by a seat formed on an in-core monitor flange 18 fixed to the lower end of the via a seal portion 19. Reference numeral 20 indicates a fuel assembly loaded in the core 10.

By the way, the in-core monitor housing 14 and the in-core monitor flange 18 are regularly inspected to remove oxides and the like adhering to the surfaces thereof. The pressure resistant plug of this embodiment is used to completely seal the leak of the reactor water when the inner surface of the in-core monitor housing 14 and the in-core monitor flange 18 are inspected.

As shown in FIG. 1, FIG. 2, and FIG. 3, the pressure-proof plug is provided after removing the in-core monitor 16 housed in the in-core monitor housing 14 and then removing the in-core monitor flange 18.
It is inserted into the in-core monitor housing 14 from the lower end of the. The pressure-resistant plug 22 includes a pressure-resistant seal 23 that can be tightly sealed to the inner peripheral surface of the in-core monitor housing 14, and a connecting rod 24 that guides and attaches the pressure-resistant seal 23 to an arbitrary position in the in-core monitor housing 14. Be prepared.

The pressure-resistant seal 23, as shown in FIGS.
A rod shaft 26 extends in the central portion, and pressure-proof packing 27 is attached to the outer peripheral portion of the upper portion thereof. Around the pressure-resistant packing 27, the metal rings 28a,
28b is attached to prevent the packing (rubber) member of the pressure resistant packing 27 from expanding in the radial direction. The upper end of the pressure-resistant packing 27 is connected to the housing collar 30 via the O-ring 29.
Supported by. The lower end of the pressure-proof packing 27 is held by the collar 32 via the ring 31. The collar 32 is screwed onto the rod shaft 26, and is rotated around the rod shaft 26 to move in the axial direction of the rod shaft 26. Then, when the rod shaft 26 is fixed and the collar 32 is rotated and moved upward, the pressure-proof packing 27 is deformed into a bellows shape as shown in FIG. 5, and is closely attached to the inner peripheral surface of the in-core monitor housing 14. Then, the reactor water is completely sealed, and the pressure-resistant seal 23 itself is mounted in the in-core monitor housing 14. A groove 35 and a quadrangular prism portion 36 are formed at the lower end of the rod shaft 26 for connection with the connecting rod 24 by a ball lock mechanism 34 as a connecting mechanism for detachably connecting.

The connecting rod 24 is provided with a sleeve 38 that is screwed and fixed to the in-core monitor flange 18, and a double shaft 41 is airtightly and slidably attached to the sleeve 38 via an O-ring 40 in the vertical and circumferential directions. To be done. Double shaft 41 is outer tube 42
An inner shaft 44 is hermetically held inside via an O-ring 43 so as to be slidable in the vertical direction and the circumferential direction. The upper end of the inner shaft 44 is connected to the lower end of the rod shaft 26 via the ball lock mechanism 34, and the quadrangular prism 36
Are coupled in the rotational direction via. Further, the upper end portion of the outer tube 42 is fitted into the lower portion of the collar 32 and is joined in the rotation direction. Further, the sleeve 38 is provided with a water pressure supply port 45 for supplying pressurized water into the in-core monitor housing 14.

Next, the operation of the above embodiment will be described.

The pressure-proof plug 22 is used for sealing the reactor water to inspect the inner surface of the in-core monitor housing 14 after removing the in-core monitor 16 housed in the in-core monitor housing 14. Mounted inside the in-core monitor housing 14.

First, the sleeve 38 is screwed and fixed to the in-core monitor flange 18, and the double shaft 41 is slid with respect to the sleeve 38 and moved to the upper portion of the in-core monitor housing 14. Then, when the pressure-resistant seal 23 reaches a predetermined position in the in-core monitor housing 14, the inner shaft 44 is fixed, the outer tube 42 is rotated, and the collar 32 is raised to mount the pressure-resistant seal 23. This pressure-resistant seal 23
Thus, leakage of reactor water can be completely prevented.

After mounting the pressure-resistant seal 23, pressure water is supplied from the water pressure supply port 45, and a leak from the wall of the in-core monitor housing 14 or the in-core monitor flange 18 can be confirmed. In addition, after mounting the pressure-resistant seal 23, the ball lock mechanism 34
With this, the connection of the connecting rod 24 can be released, and the inner surface of the in-core monitor housing 14 can be inspected.

Thus, according to the above-mentioned embodiment, when inspecting the inner surface of the in-core monitor housing 14, it can be freely mounted at any position on the inner surface of the in-core monitor housing 14, and the reactor water can be completely sealed. Further, the leak from the wall surface of the in-core monitor housing 14 and the in-core monitor flange can be confirmed safely, reliably and easily, and the radiation dose of the worker can be reduced.

〔The invention's effect〕

The present invention relates to a pressure-resistant seal capable of closely contacting and sealing the inner peripheral surface of an in-core monitor housing, a connecting rod for guiding and mounting the pressure-resistant seal at an arbitrary position in the in-core monitor housing, and the pressure-resistant seal and the connecting rod. Since a connection mechanism for detachably connecting the incore monitor housing is provided, it can be freely attached to any position on the inner surface of the incore monitor housing when inspecting the inner surface of the incore monitor housing.
Reactor water can be completely sealed, and leaks from the in-core monitor housing wall and in-core monitor flange can be confirmed safely, reliably and easily, and the radiation exposure of workers can be reduced. You can

[Brief description of drawings]

1 is a block diagram showing an embodiment of a pressure-proof plug according to the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III in FIG. 4 (A),
(B) is a block diagram showing the pressure-resistant seal in the above embodiment,
FIG. 5 is a view showing a state in which the pressure-resistant seal is mounted in the in-core monitor housing in the above embodiment, and FIG. 6 is a sectional view showing a state in which the neutron instrumentation tube is installed in the reactor. 14 …… incore monitor housing, 15 …… incore monitor guide tube, 15a …… upper opening, 16 …… incore monitor, 18 …… incore monitor flange, 22 …… pressure plug, 23 …… pressure seal, 24 …… Connecting rod, 26 …… Rod shaft, 27 …… Pressure-proof packing, 32 …… Color, 34 …… Ball lock mechanism, 38 …… Sleeve, 41 …… Double shaft, 42 …… Outer pipe, 44 …… Inner shaft , 45 …… Water pressure supply port.

Claims (1)

[Claims] Claims: 1. A pressure-resistant seal capable of closely contacting and sealing the inner peripheral surface of an in-core monitor housing, a connecting rod for guiding and mounting the pressure-resistant seal at an arbitrary position in the in-core monitor housing, and the pressure-resistant seal and connection. The pressure-resistant seal is equipped with a pressure-resistant packing around the rod shaft, and the pressure-resistant seal is deformed by rotating around the rod shaft to deform the pressure-resistant packing inside the in-core monitor housing. The connecting rod is provided with a collar that closely adheres to the peripheral surface of the connecting rod, and the double shaft is hermetically and slidably held by the sleeve fixed to the in-core monitor flange. The outer tube is slidably held and the upper end of the outer tube is connected to the collar while the inner shank is The upper end of the: it is coupled to the rod shaft, the breakdown voltage plug, characterized in that the pressure supply port capable of supplying pressure water is formed in-core monitor housing in the sleeve.