JPS6261920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a closure device that can hermetically plug a main steam nozzle of a nuclear reactor pressure vessel and illuminate the inside of the reactor pressure vessel during periodic inspections.

Periodic inspections of boiling water reactors include, for example, fuel changes. This fuel exchange involves replacing the fuel assembly loaded in the reactor core within the reactor pressure vessel with a new one, and a fuel exchanger is used to replace this fuel assembly. This fuel exchange machine is placed on a work floor above the reactor pressure vessel, and when exchanging fuel, a worker operates the fuel exchange machine from the work floor to replace the fuel assembly. In addition, when performing such fuel exchange, the work floor is far above, and the reactor pressure vessel and the reactor well above the pressure vessel are filled with water for shielding. Therefore, the location of the reactor core is dark and difficult to see. For this reason, during fuel exchange, a lighting device is required to illuminate the inside of the reactor pressure vessel, that is, the reactor core. Conventionally, an underwater lighting device was installed by hanging from the fuel exchange machine, and this underwater lighting device illuminated the vicinity of the fuel assembly to be replaced. It is designed to provide localized illumination. However, in the case of such underwater lighting equipment that can be hung, there is a problem that the underwater lighting equipment shakes during work and cannot provide reliable illumination. Furthermore, since the hanging cable also sways as the underwater lighting equipment sways, the water surface of the reactor well also sways, resulting in poor visibility inside the reactor core.

By the way, during the above-mentioned periodic inspection, maintenance and inspection of the main steam system is performed in parallel with fuel exchange, and a blocking device is used for this maintenance and inspection of the main steam system. This blocking device is installed inside the reactor pressure vessel, and by inserting the blocking plug into the main steam nozzle, the main steam nozzle is hermetically sealed.This is used to conduct leakage tests of the main steam system, etc. It's becoming like that. As described above, during periodic inspections, there is installation work such as installing the above-mentioned underwater lighting equipment and the above-mentioned closure device inside the reactor pressure vessel, but these installation works have conventionally been performed separately. For this reason, since each installation work requires work time, the periodic inspection period becomes long and there is a problem that the amount of radiation exposure of the workers increases.

This invention was made based on the above circumstances, and its purpose is to stably illuminate the reactor pressure vessel during fuel exchange by providing the above-mentioned underwater lighting device. Another object of the present invention is to provide a closure device for a nuclear reactor main steam nozzle that can shorten periodic inspection time and reduce radiation exposure to workers.

That is, the present invention provides a blocking plug that is removably inserted into a main steam nozzle to seal the main steam nozzle in an air-water tight manner; The reactor pressure vessel is equipped with a ring-shaped support ring that is positioned along the surface of the reactor pressure vessel to prevent the plug from popping out into the reactor pressure vessel, and a plurality of underwater lighting devices are provided along the circumferential direction at the bottom of this support ring. This is a characteristic feature.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 10.

Figure 1 shows a boiling water nuclear reactor, where 1 is the reactor pressure vessel. This reactor pressure vessel 1 contains a reactor core 2, and a plurality (usually four) of main steam nozzles 3 are provided in the upper part of the reactor pressure vessel 1. These main steam nozzles 3 are connected to main steam pipes 4, respectively, and the boiling water reactor guides the steam generated in the reactor core 2 through these main steam pipes 4 to a power generation turbine. It is designed to be driven to generate electricity. In addition, the main steam pipe 4... is provided with a reactor containment vessel wall 5.
A pair of main steam isolation valves 6, 6 are provided on either side of the reactor pressure vessel 1, and a pressure relief valve 7 is provided which operates when the pressure inside the reactor pressure vessel 1 is abnormal.
8 is the working floor of the reactor building. In addition, the first
The figure shows a state in which the lid (not shown) inside the reactor pressure vessel 1 is removed during periodic inspection, and the inside of the reactor pressure vessel 1 and the reactor well 9 are filled with water for shielding.

In order to carry out maintenance and inspection of the main steam system during such periodic inspections, a blockage device 10 for the main steam nozzles 3 is inserted and installed in the reactor pressure vessel 1, and as described below. The configuration of the closure device 10 will be explained with reference to FIGS. 2 to 6. In the figure, 11 is a base. This base 11 consists of two beams 13, 13 connected at the center and both ends by connecting members 12, and both ends of these beams 13, 13 are arranged to face the main steam nozzles 3, respectively, when inserted. It is composed of In addition, the connecting members 12... have hanging ears 14 for hanging.
... are provided, and wire ropes are connected to these hanging ears 14, so that the entire closure device 10 can be suspended by an overhead crane of the reactor building. Closing plugs 15 are provided on both ends of the beams 13, 13, respectively. The closing plugs 15 are made up of a cylindrical body 16 having a smaller diameter than the inner diameter of the main steam nozzle 3, and rollers 17 are provided at the tips thereof. Furthermore, a hollow hydraulic seal 18 and a hollow pneumatic seal 19 are provided on the outer periphery of the intermediate portion of the cylindrical body 16, respectively, and an O-ring 20 is provided at the rear end. Also, 21...
is a collection of hoses that supply water and air to the hydraulic seal 18 and pneumatic seal 19.
And behind the blockage plug 15... is a trolley 22...
These carts 22... are capable of reciprocating in the longitudinal direction on the beams 13, 13 by means of hydraulic cylinders 23.... Also, 2
4... are wheels of the trolley 22.... As shown in FIG. 3, the carts 22 and the closing plugs 15 are hook-shaped connectors 25a that engage with each other,
25b, respectively, and the trolley 2
The reciprocating motion of the plugs 15 and 2 causes the plugs 15 to be pushed out and pulled back in the direction of insertion and removal from the main steam nozzles 3. Moreover, the connection between the carriages 22... and the blocking plug 15 is the connection between the carriages 22...
It can be released by moving the side upward. Moreover, the blocking plugs 15... are inserted into the insertion/extraction guide 26 on the beams 13, 13
...supported by... This insertion/extraction guide 2
6... are fixedly provided on the beams 13, 13, and their distal ends are removably inserted into the rear ends of the closing plugs 15....

A support ring 27 is provided on the side of the base 11. This support ring 2
7 is composed of a frame 28 that can be divided into four parts, and this frame 28 has a ring shape along the inner peripheral surface of the reactor pressure vessel 1. And frame 2
8 is connected to the beams 13, 13 via connecting rods 29, as shown in FIG. It can be inserted and removed. Therefore, the support ring 27 is supported on the base 11 in a detachable manner. In addition, 31a, 31b
is an engaging portion that determines the position between the support ring 27 and the base 11. And the above frame 2
Positioning guides 32, 32 are provided on the outer periphery of 8. These positioning guides 32, 32 are fitted and guided by guide rods 33, 33 on the inner surface of the reactor pressure vessel 1, and position the entire closure device 10 in the circumferential direction, that is, position the insertion/extraction direction of the closure plugs 15 with respect to the main steam nozzles 3. I'm starting to do that. Furthermore, upper supports 34 are provided on the outer periphery of the frame 28. These upper supports 34 project laterally from the upper part of the frame 28 and can engage with dryer support brackets 35 on the inner surface of the reactor pressure vessel 1. Further, when the upper supports 34 and the dryer supports 35 are engaged, the closing plugs 15 are positioned in the height direction with respect to the main steam nozzles 3. These dryer support brackets 35 are used to support a steam dryer (not shown) during operation of the nuclear reactor. Further, as shown in FIG. 4, the frame 28 is provided with lower supports 36 below the upper supports 34, respectively. These lower supports 36 are normally housed within the frame 28, and can be projected toward the dryer support brackets 35 by means of hydraulic cylinders 37. Further, when the lower supports 36 are made to protrude and the lower supports 36 are engaged with the dryer support brackets 35, the support ring 27 is positioned in the height direction relative to the main steam nozzle position. It is something that As shown in FIG. 1, pressing rods 38 are accommodated within the frame 28. These pressing rods 38 are connected to the closing plugs 15...
It is located below the frame 28 and can be protruded and retracted from the frame 28 toward the inner surface of the reactor pressure vessel 1 by means of hydraulic cylinders 39 .

The support ring 27 is provided with underwater lighting devices 40. These underwater lighting equipment 4
0... are arranged in the circumferential direction at the lower part of the frame 28..., and are adapted to irradiate light toward the center of the interior of the reactor pressure vessel 1, respectively.See FIGS. 5 and 6 for the configuration. and explain.
Arms 41, 41 are protruded downward from the lower part of the frame 28, and these arms 4
The lighting fixture main body 42 is attached between 1 and 41. The lighting main body 42 is constructed by accommodating, for example, a plurality of halogen light bulbs 44 in a lamp case 43 made of translucent and waterproof plastic, and 45 is a socket for the halogen light bulb 44;
6 is a reflective shade for the halogen light bulb 44. Also, 4
7 is a protective wire mesh provided on the outer surface of the lamp case 43. One end of a cabtire cable 48 for power supply is connected to the lighting fixture body 42 via a waterproof rubber sheath 49, and the other end of the cabtire cable 48 is connected to the work floor of the reactor building. It is led up to the surface 8 and connected to a power supply outlet. Note that 50 is a switch box. In this embodiment, the lighting main body 42 is supported between the arms 41, 41 via a pivot 51, and is rotatable about the pivot 51. A disc 52 for setting the illumination direction is fixed to one end of the pivot 51, and a plurality of engagement holes 53 are formed on the surface of the disc 52 at equal pitches on the circumference. . Further, a setting lever 54 is attached to the arm 41 on the side of the disc 52, and the setting lever 54 is provided with a projection (not shown) that can fit into the engagement hole 53. Therefore, by fitting the protrusion into any engagement hole 53, the rotation angle, that is, the illumination angle of the lighting device body 42 can be adjusted and fixed.

Next, the operation of the closure device 10 having the above configuration will be explained.

First, during regular inspection, the base 11 is placed on the work floor 8.
The entire device is assembled by attaching the blocking plugs 15 and the support ring 27 to the device, and the blocking device 10 is lifted by an overhead crane. Then, the closure device 10 is transferred to the upper part of the reactor pressure vessel 1 by this overhead crane, and the closure device 10 is gradually inserted into the reactor pressure vessel 1. Note that at this time, the positioning guides 32, 32 are connected to the guide rod 3.
3, 33, and the occlusion device 10 is inserted, and this occlusion device 10, that is, the occlusion plug 15
... is positioned in the circumferential direction. Furthermore, when the closure device 10 is submerged in water, the underwater lighting devices 40 are turned on to illuminate the inside of the reactor pressure vessel 1, and are also used as lighting for installing the closure device 10. Then, the closing device 10 is further suspended, the upper supports 34 of the support ring 28 are engaged with the dryer support brackets 35 as shown in FIG. 4, and the closing device 10 is supported by these dryer support brackets 35. do. At this time, the closing plugs 15 are opposed to the main steam nozzles 3, and the closing plugs 15 are positioned in the height direction. Then, by operating the hydraulic cylinders 23, the blockage plugs 15 are pushed out via the carts 22, and these blockage plugs 15 are connected to the respective main steam nozzles 3.
…Insert within. In addition, at this time, the blockage plug 1
5... slides on the beams 13, 13, and is guided by the insertion/extraction guides 26... to be inserted. After the closing plugs 15 are inserted, as shown in FIG. 7, water and air are supplied into the hydraulic seals 18 and pneumatic seals 19 to inflate them. let me,
As a result, the main steam nozzles 3 are air-tightly sealed. Then, the base 11 is lifted up and the support ring 28 is lifted up to a position slightly above the main steam nozzle position. At this time, each blockage plug 1
5 and the truck 22 are disengaged from each other as the base 11, that is, the truck 22 rises, and these connections are released. And after this,
After operating the hydraulic cylinders 37 and causing the lower supports 36 to protrude from the frame 28,
Gradually hang the base 11 side again. Then, the lower supports 36 are engaged with the dryer support brackets 35 as shown in FIG.
The support ring 27 is installed on this dryer support bracket 35. At this time, this support ring 27 is positioned at the main steam nozzle position. Further, the hydraulic cylinders 39 are operated to cause the pressing rods 38 to protrude from the frame 28, and these pressing rods 38 press and hold the closing plugs 15, respectively, as shown in FIG. After that, the hydraulic cylinders 30 are operated to pull out the connecting rods 29 from the frame 28 to release the connection between the support ring 28 and the base 11, and then the base 11 is lifted up and placed inside the reactor pressure vessel 1. remove from At this time, the closing plugs 15 of the closing device 10 and the support ring 27 remain in the reactor pressure vessel 1, as shown in FIG. In this way, the main steam nozzle 3...
After sealing, remove the main steam isolation valves 6, etc. in the main steam system and perform maintenance and inspection on them, and apply steam pressure inside the main steam pipes 4 to close the main steam pipes 4 and the main steam isolation valves 6. It is used to perform leakage tests such as... Note that even if steam pressure is applied inside the main steam pipe 4, the blocking plugs 15 are not connected to the support ring 2.
7, it is possible to reliably prevent the closing plugs 15 from popping out due to the steam pressure.

Furthermore, during such periodic inspections, fuel replacement work is performed in parallel with maintenance inspections of the main steam system. This fuel exchange involves replacing spent fuel assemblies in the core 2 with new ones using the fuel exchanger on the work floor 8. During this fuel exchange, the underwater lighting provided on the support ring 27 The devices 40 are turned on to illuminate the entire area inside the reactor pressure vessel 1.
As a result, visibility of the vicinity of the reactor core 2 from the work floor 8 is improved, and workability can be improved. Also, during such fuel exchange, a closure device 10 is installed inside the reactor pressure vessel 1 as shown in FIG.
Since only the support ring 27 remains, it does not interfere with the fuel exchange operation in any way.

In addition, since the underwater lighting fixtures 40 are attached to the support ring 27, the underwater lighting fixtures 40 do not shake like conventional hanging types during refueling, and the inside of the reactor pressure vessel 1 is can ensure stable lighting. Furthermore, the water surface of the reactor well 9 does not sway due to the shaking of the underwater lighting fixtures 40, or the shaking of the hanging wires, unlike in the case of conventional hanging types.
The visibility of the inside of the furnace from the work floor 8 can be further improved.

Furthermore, since the underwater lighting devices 40 can be installed in the reactor pressure vessel 1 at the same time as the closure device 10, that is, the support ring 27 is installed,
Compared to the conventional hanging type, underwater lighting equipment has 40...
The work time required for the installation itself can be omitted. As a result, the regular inspection period can be shortened, and the amount of radiation exposure of workers can be reduced.

Further, according to this embodiment, the underwater lighting device 40
Since the illumination angle can be varied, it is possible to intensively illuminate the areas where it is needed, and the illumination effect is high.

Note that the present invention is not limited to the above embodiment. For example, the mechanism for changing the illumination angle of the lighting fixture main body 42 may be as shown in FIGS. 11 and 12. That is, in this case, a worm wheel 60 is provided at one end of a pivot shaft 51 that supports the lighting device main body 42, and a worm gear 61 is meshed with the worm wheel 60. Further, an operating rod 62 passing through the support ring 27 is connected to the worm gear 61, and the upper end of the operating rod 62 has a shape capable of fitting a hexagonal wrench box or the like. Therefore, by fitting a long wrench onto the upper end of the operating rod 62 from above the work floor 8 and rotating the operating rod 62, the lighting main body 42 can be rotated via the worm gear 61 and the worm wheel 60. By moving it, the illumination angle of the lighting device main body 42 can be changed even during fuel exchange work.

As explained above, the present invention provides a blockage plug that is removably inserted into a main steam nozzle and seals the main steam nozzle in an air-watertight manner, and a blockage plug that is inserted into a reactor pressure vessel at the main steam nozzle position after insertion of the blockage plug. A ring-shaped support ring is positioned along the inner peripheral surface of the reactor pressure vessel to prevent the plug from popping out into the reactor pressure vessel, and a plurality of underwater lighting devices are provided below the support ring along the circumferential direction. It is characterized by: Therefore, since the above-mentioned underwater lighting equipment is attached to the support ring, there is no possibility that the underwater lighting equipment will shake during the fuel exchange operation, and the water surface will not shake due to the shaking of this underwater lighting equipment. Therefore, the inside of the reactor pressure vessel can be illuminated reliably and stably, and the visibility inside the reactor pressure vessel can be improved. In addition, since the work required to install the underwater lighting equipment itself can be omitted, periodic inspection periods can be shortened.
The effects are significant, such as reducing the radiation exposure of workers and improving the operating rate of the reactor.

[Brief explanation of the drawing]

1 to 10 show an embodiment of the present invention, in which FIG. 1 is a sectional view of a reactor pressure vessel, FIG. 2 is a partially sectional side view of a closure device, and FIG. 3 is a sectional view of a closure device. A plan view of the device, FIG. 4 is a cross-sectional view taken along the line in FIG. 3, FIG. 5 is a cross-sectional view taken along the line in FIG. 3, and FIG. 6 is a cross-sectional view taken along the line in FIG.
Fig. 7 is a view immediately after the blocking plug is inserted into the main steam nozzle, Fig. 8 is a sectional view of the support ring when the lower support is protruding, Fig. 9 is a view when the pressing rod is ejected, Fig. 10 The figure is a cross-sectional view of the reactor pressure vessel with the base removed when the plug is inserted. 11 and 12 show another embodiment of the present invention, FIG. 11 is a front view of the underwater lighting device, and FIG. 12 is a side view of the underwater lighting device seen from the direction XII in FIG. 11. 1... Reactor pressure vessel, 3... Main steam nozzle, 15
...Closure plug, 27... Support ring, 40... Underwater lighting device, 41... Arm.

Claims (1)

[Scope of Claims] 1. A blocking plug that is removably inserted into a main steam nozzle from the inside of the reactor pressure vessel to seal the main steam nozzle in an air-watertight manner, and after the blocking plug is inserted, the main steam nozzle a ring-shaped support ring that is positioned along the inner circumferential surface of the reactor pressure vessel at a position to prevent the plug from popping out into the reactor pressure vessel; A nuclear reactor main steam nozzle blocking device characterized by being provided with an underwater lighting device. 2. The nuclear reactor main steam nozzle closing device according to claim 1, wherein the underwater lighting device is rotatably attached to the lower part of the support ring.