JP6767850B2 - Reactor water level detector and reactor - Google Patents

Description

The present invention relates to a reactor water level detecting device for detecting the water level of the coolant in the reactor, and a reactor equipped with this reactor water level detecting device.

For example, in a nuclear power plant, a pressurized water reactor uses light water as a reactor coolant and neutron moderator to make high-temperature high-pressure water that does not boil over the entire core, and sends this high-temperature high-pressure water to a steam generator to supply water. Steam is generated by exchanging heat with the reactor, and this steam can be sent to a turbo generator to generate electricity.

In this pressurized water reactor, a core is provided in the reactor vessel, and this core is composed of a large number of fuel assemblies, and by inserting control rod clusters into this fuel assembly, The output of the reactor can be controlled. The coolant (light water) is supplied into the reactor vessel from the inlet nozzle, then descends and reverses at the bottom, and is heated by cooling the fuel as it rises along the fuel assembly, and is heated from the outlet nozzle. It is discharged and sent to the steam generator. Further, the pressurized water reactor is provided with a water level detection device for detecting the water level of the coolant in the reactor vessel.

Examples of the water level detecting device for detecting the water level of the coolant in the reactor vessel include those described in the following patent documents. In the water level detector described in each patent document, the intermediate portion is supported by the upper core support plate, the lower portion is supported by the upper core plate, and the upper portion is supported by the reactor vessel lid.

Jikken 03-001768 Gazette Japanese Patent Application Laid-Open No. 08-220284

By the way, when the reactor is maintained, after removing the reactor vessel lid from the reactor vessel body, operations such as taking out the reactor internal structure and exchanging the fuel assembly are carried out. The water level detection device is generally configured by inserting a water level gauge into a storage member. One of the storage members is supported by a support member installed on the reactor internal structure side, and the other is fixed to the reactor vessel lid. Since the water level gauge measures the water level of the coolant inside the reactor vessel body, the total length of the water level gauge is generally longer than the total length of the reactor vessel lid. Therefore, in the maintenance of the reactor, if the reactor vessel lid is removed from the reactor vessel with the water level gauge inserted in the storage member, it will be inserted inside the storage member when the reactor vessel lid is moved or stored. Since there is a risk that the water level gauge will come into contact with the equipment and devices installed around the reactor vessel body, or the workers involved in maintenance, when maintaining the reactor, the water level gauge should be removed from the storage member. Work to pull out is required. After the maintenance is completed, it is necessary to reinsert the water level gauge into the storage member. The work of pulling out the water level gauge from the storage member or inserting the water level gauge into the storage member is a work that is always necessary for the maintenance of the reactor, the maintenance period of the reactor becomes long, and the exposure dose of the operator is increased. The issue is to increase.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a nuclear reactor water level detection device and a nuclear reactor for improving the workability of the maintenance work of the nuclear reactor.

The reactor water level detection device of the present invention for achieving the above object includes a water level gauge for detecting the water level of the coolant and a storage member for accommodating the water level gauge, and the lower part of the storage member is a reactor. It is characterized in that it is supported by a support member provided on the inner structure side, while the upper portion is detachably supported by the reactor vessel lid.

Therefore, while the lower part of the storage member is supported by the support member provided on the reactor internal structure side, the upper part is detachably supported by the reactor vessel lid, so that the reactor vessel main body is used during the maintenance of the reactor. When the reactor vessel lid is removed, the storage member containing the water level gauge is separated from the reactor vessel lid, so the work of pulling out the water level gauge from the storage member or inserting the water level gauge into the storage member is required. It becomes unnecessary. Therefore, the work time related to the maintenance of the nuclear reactor is shortened, the exposure dose of the worker is also reduced, and the workability of the maintenance work of the nuclear reactor can be improved.

In the reactor water level detection device of the present invention, the pedestal is fixed to the reactor vessel lid, and the upper end of the storage member penetrates the pedestal and is detachably locked by the locking member. It is a feature.

Therefore, the storage member can be attached to and detached from the base of the reactor vessel lid simply by operating the locking member, and the reactor vessel lid can be lifted by simply raising and lowering the reactor vessel lid with respect to the reactor vessel body. It can be separated from the storage member or the reactor vessel lid can be attached to the storage member.

In the reactor water level detection device of the present invention, the storage member is provided with a main body portion and an upper small diameter portion, and a stepped portion is provided between the main body portion and the upper small diameter portion. It is characterized in that a sealing member is interposed between the pipe base.

Therefore, if the sealing member is brought into close contact with the storage member and the pipe base by simply moving the stepped portion of the storage member and the pipe base in a direction approaching each other, and the storage member is locked by the locking member in this close contact state. Well, the sealability and the seal mountability can be improved.

In the reactor water level detection device of the present invention, a support member is fixed to the internal structure of the reactor, and the lower end of the storage member is movably supported by the support member along the longitudinal direction and is an urging member. It is characterized in that the seal member is urged and supported in the direction of being pressed.

Therefore, by moving the storage member upward with respect to the pipe base, the seal member can be brought into close contact with the storage member and the pipe base, and the storage member may be locked by the locking member in this close contact state. Further, when the locking member is removed to release the locked state of the storage member, the storage member is lowered by its own weight, but since the storage member is supported by the urging force of the urging member, it collides with the internal structure of the furnace. Can be prevented and damage to the storage member can be prevented.

The reactor water level detection device of the present invention is characterized in that the lower end portion of the storage member is supported apart from the internal structure by the urging force of the urging member.

Therefore, it is possible to secure the amount of movement of the storage member with respect to the tube base to improve the mountability of the seal member, and to alleviate the impact when the storage member is lowered by the urging member to prevent damage to the storage member. can do.

In the reactor water level detection device of the present invention, the support member has a tubular shape, the lower end of the storage member is arranged in the support member, and the storage member is located between the support member and the storage member. It is characterized in that a positioning member for positioning and holding is provided.

Therefore, since the storage member is supported by the support member via the positioning member, the storage member is stably supported at a predetermined position with respect to the internal structure of the reactor, and the reactor vessel lid can be easily attached. It can be attached to the reactor vessel body.

Further, the reactor of the present invention is characterized in that the reactor water level detecting device is provided.

Therefore, the water level in the reactor vessel can be detected with high accuracy, and the workability of the reactor maintenance work can be improved.

According to the reactor water level detector and the reactor of the present invention, the lower part of the storage member for accommodating the water level gauge is supported by the internal structure, and the upper part is detachably supported by the reactor vessel lid. It is possible to improve the workability of the maintenance work of the reactor.

FIG. 1 is a cross-sectional view showing the reactor water level detection device of the present embodiment. FIG. 2 is a vertical cross-sectional view showing a pressurized water reactor.

Hereinafter, preferred embodiments of the reactor water level detector and the reactor according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment, and when there are a plurality of embodiments, the present invention also includes a combination of the respective embodiments.

Although not shown, a nuclear power plant has a reactor and a steam generator arranged in a reactor containment vessel, and a steam turbine power generation facility. In the reactor of the present embodiment, light water is used as a reactor coolant and a neutron reducer to make high temperature and high pressure water that does not boil over the entire core, and this high temperature and high pressure water is sent to a steam generator to generate steam by heat exchange. This is a pressurized water reactor (PWR) that sends this steam to a turbine generator to generate power.

FIG. 2 is a vertical cross-sectional view showing a pressurized water reactor.

As shown in FIG. 2, in the pressurized water reactor 10, the reactor vessel 11 has a reactor vessel body 12 and a reactor vessel lid 13 mounted on the reactor vessel main body 12 so that an internal structure can be inserted into the reactor vessel 11. The reactor vessel lid 13 is openably and closably fixed to the reactor vessel body 12 by a plurality of stud bolts 14 and nuts 15.

The reactor vessel main body 12 has a cylindrical shape with an open upper portion and a hemispherical lower portion closed, and an inlet nozzle 16 for supplying light water as primary cooling water (coolant) to the upper portion, and light water. An outlet nozzle 17 is formed to discharge the water. The core tank 18 is arranged inside the reactor vessel main body 12, and the upper portion is supported by the inner wall surface of the reactor vessel main body 12. The upper core support plate 19 is arranged inside the reactor vessel main body 12, and the upper portion is supported by the upper portion of the core tank 18. The upper core plate 20 is suspended and supported by a plurality of core support rods 21 on the upper core support plate 19.

The lower core support plate 22 is supported downward in the core tank 18, and the outer peripheral portion of the lower core support plate 22 is positioned and supported on the inner wall surface of the reactor vessel main body 12 by the positioning member 23. The lower core plate 24 is supported at the lower part of the core tank 18. The core 25 is configured by arranging a large number of fuel assemblies 26, and a large number of control rods 27 are arranged inside, and the control rods 27 can be inserted into the fuel assembly 26. A large number of control rod cluster guide pipes 28 are fixed to the upper core support plate 19, and control rods 27 can be inserted therein. The reactor vessel lid 13 has a hemispherical shape, a control rod drive device 29 is arranged, a plurality of control rod cluster drive shafts 30 are inserted into the control rod cluster guide pipe 28, and the control rod 27 is connected to the lower end portion. ing. The control rod drive device 29 controls the reactor output by inserting and removing each control rod 27 from the core 25.

A water level detection device (reactor water level detection device) 40 for detecting the water level of light water (primary coolant) in the reactor container 11 is arranged in the reactor container 11. The water level detection device 40 penetrates the upper core support plate 19 as an internal structure and is supported by the upper core plate 20, and is detachable from the reactor vessel lid 13.

FIG. 1 is a cross-sectional view showing the reactor water level detection device of the present embodiment.

As shown in FIG. 1, the water level detection device 40 includes a water level gauge 41 that detects the water level of the primary coolant, and a storage pipe (storage member) 42 that stores the water level gauge 41.

The water level gauge 41 is generally referred to as, for example, a heated thermocouple type. Although not shown, the water level gauge 41 is composed of a plurality of thermocouples having different lengths, and the plurality of thermocouples measure the cooling water temperature at different heights in the primary cooling water stored in the reactor vessel 11. Can be measured. Then, when a sufficient amount of primary cooling water is filled in the reactor vessel 11, each thermocouple measures substantially the same cooling water temperature, there is substantially no temperature difference, and the water level gauge 41 is the reactor. It is determined that water is present in the container 11. On the other hand, when the primary cooling water in the reactor vessel 11 decreases, the temperature of the thermocouple exposed from the primary cooling water rises, so that each thermocouple measures a different cooling water temperature, a temperature difference occurs, and the water level gauge 41 Determines that the water in the reactor vessel 11 is decreasing. Although the heating type thermocouple method has been applied to the water level gauge 41, the description is not limited to this method.

The storage pipe 42 has a cylindrical shape having a predetermined length, and the water level gauge 41 is housed in a support hole formed along the longitudinal direction. Although FIG. 1 shows a storage pipe 42 in which only one water level gauge 41 (thermocouple) is stored, a plurality of water level gauges are actually stored. The main body 51 having a large diameter of the storage pipe 42 is composed of an upper small diameter portion 52 having a diameter smaller than that of the main body 51 and a lower small diameter portion 53 having a diameter smaller than that of the main body 51. An upper stepped portion 54 is formed between them, and a lower stepped portion 55 is formed between the main body portion 51 and the lower small diameter portion 53. The upper stepped portion 54 and the lower stepped portion 55 have a ring shape, but the shape is not limited to the ring shape.

A support pipe (support member) 61 is fixed to the upper surface of the upper core plate 20 as a support member on the furnace internal structure side. The support pipe 61 has a cylindrical shape having the same diameter along the axial direction, and the inner diameter is set to be larger than the outer diameter of the main body 51 of the storage pipe 42. On the other hand, in the reactor vessel lid 13, the tube base 62 penetrates and is fixed to the mounting hole 13a penetrating in the axial direction. The tube base 62 is formed in a cylindrical main body 62a, a ring-shaped flange portion 62b formed in the upper part of the main body 62a, a through hole 62c formed in the center of the flange portion 62b, and a lower portion of the main body 62a. It is composed of an enlarged diameter portion 62d forming an umbrella shape.

The lower part of the storage pipe 42 is supported by the support pipe 61 fixed to the upper core plate 20, while the upper part is detachably supported by the pipe base 62 fixed to the reactor vessel lid 13.

That is, the storage pipe 42 is positioned and held by the lower end of the main body 51 being arranged in the support pipe 61 and the leaf spring (positioning member) 63 interposed between the storage pipe 42 and the support pipe 61. Will be done. The leaf spring 63 has a cylindrical shape, an upper flange 63a is arranged at the upper end of the support pipe 61, and a plurality of support pieces 63b hanging from the flange 63a penetrate into the support pipe 61 and reach the outer peripheral surface of the storage pipe 42. Pressing. Therefore, the storage pipe 42 is pressed toward the center by each support piece 63b of the leaf spring 63, so that the storage pipe 42 is maintained in an upright state at the center position of the support pipe 61 with respect to the upper core plate 20 and in the axial direction. It is supported so as to be movable along (longitudinal direction).

Further, in the storage pipe 42, a compression coil spring (biasing member) 64 is interposed between the lower portion and the upper core plate 20. One end of the compression coil spring 64 presses against the upper surface of the upper core plate 20, and the other end presses against the lower stepped portion 55 of the storage pipe 42. Therefore, the storage pipe 42 is urged and supported upward in the vertical direction by the urging force of the compression coil spring 64.

On the other hand, the upper portion of the storage pipe 42 is arranged in the pipe base 62, and the upper small diameter portion 52 penetrates through the through hole 62c. Then, in the storage pipe 42, a ring-shaped seal member 65 is interposed between the upper stepped portion 54 and the flange portion 62b of the tube base 62, and the upper small diameter portion is in a state where the seal member 65 is crushed. 52 is detachably locked to the flange portion 62b of the tube base 62 by a clip (locking member) 66.

In the storage pipe 42, when the upper small diameter portion 52 is locked to the tube base 62, the lower small diameter portion 53 is separated from the upper core plate 20 and a gap is secured between the two. At this time, the storage pipe 42 is urged and supported in the direction in which the seal member 65 is pressed by the urging force of the compression coil spring 64.

Here, the operation of the reactor water level detection device of the present embodiment will be described.

When the water level detection device 40 is attached to the reactor vessel 11, with the reactor vessel lid 13 removed from the reactor vessel body 12, first, the leaf spring 63 and the leaf spring 63 and the support pipe 61 fixed to the upper core plate 20 are attached. The compression coil spring 64 is attached, and the storage pipe 42 in which the water level gauge 41 is housed is inserted into the support pipe 61. Here, the lower portion of the storage pipe 42 is elastically supported by the compression coil spring 64, and the outer peripheral surface is supported by the support pipe 61 by the leaf spring 63, so that the storage pipe 42 is positioned in the radial direction. Next, the seal member 65 is attached to the upper stepped portion 54 of the storage pipe 42, the reactor vessel lid 13 to which the pipe base 62 is fixed is lowered using a crane, and the upper small diameter portion 52 of the storage pipe 42 is used as the pipe base. It is passed through the through hole 62c of 62 and placed on the reactor vessel main body 12.

At this time, since the storage pipe 42 is in the lowering position where the compression coil spring 64 is compressed by its own weight, the storage pipe 42 is raised by using the upper small diameter portion 52 using a jig (not shown), so that the upper stepped portion The seal member 65 between the 54 and the flange portion 62b of the tube base 62 is crushed. Then, in the state where the seal member 65 is crushed at the raised position of the storage pipe 42, the storage pipe 42 is connected to the tube base 62 by locking the clip 66 to the upper small diameter portion 52. Then, the nut 15 (see FIG. 2) is fastened to fix the reactor vessel lid 13 to the reactor vessel main body 12.

On the other hand, when carrying out the maintenance work of the internal structure, first, the nut 15 (see FIG. 2) is loosened to release the fastening between the reactor vessel main body 12 and the reactor vessel lid 13, and the top of the storage pipe 42. The clip 66 locked to the small diameter portion 52 is removed, and the connection between the tube base 62 of the reactor vessel lid 13 and the storage tube 42 is released. At this time, the storage pipe 42 descends when the upper small diameter portion 52 is released from the tube base 62, but the lower portion is supported by the compression coil spring 64, so that the storage pipe 42 collides with the upper core plate 20. Be prevented.

Next, the reactor vessel lid 13 to which the tube base 62 is fixed is raised by using a crane, and the upper small diameter portion 52 of the storage pipe 42 is pulled out from the through hole 62c of the tube base 62. At this time, the lower portion of the storage pipe 42 is elastically supported by the compression coil spring 64, and the outer peripheral surface is supported by the support pipe 61 by the leaf spring 63, so that the storage pipe 42 is independently supported by the upper core plate 20. In this state, operations such as removal and replacement of the fuel assembly are carried out.

As described above, the reactor water level detection device of the present embodiment includes a water level gauge 41 for detecting the water level of the primary coolant and a storage pipe 42 for accommodating the water level gauge 41, and the lower portion of the storage pipe 42 is provided. While supported by the upper core plate (support member) 20, the upper portion is detachably supported by the reactor vessel lid 13.

Therefore, when the reactor vessel lid 13 is removed from the reactor vessel main body 12 during the maintenance of the reactor, the storage pipe 42 is separated from the reactor vessel lid 13 and is stably supported on the upper core plate 20 side. To. By separating the storage member 42 into which the water level gauge 41 is inserted from the reactor vessel lid, it is not necessary to pull out the water level gauge from the storage member or insert the water level gauge into the storage member. Therefore, the work time related to the maintenance of the nuclear reactor is shortened, the exposure dose of the worker is also reduced, and the workability of the maintenance work of the nuclear reactor can be improved.

In the reactor water level detection device of the present embodiment, the reactor base 62 is fixed to the reactor vessel lid 13, the upper end of the storage pipe 42 penetrates the reactor base 62, and is detachably locked by the clip 66. Therefore, the storage pipe 42 can be attached to and detached from the tube base 62 of the reactor vessel lid 13 simply by operating the clip 66, and the atom can be moved by simply raising and lowering the reactor vessel lid 13 with respect to the reactor vessel body 12. The reactor vessel lid 13 can be separated from the storage pipe 42, or the reactor vessel lid 13 can be attached to the storage pipe 42.

In the reactor water level detection device of the present embodiment, the main body 51 and the upper small diameter portion 52 are provided in the storage pipe 42, and the upper stepped portion 54 is provided between the main body 51 and the upper small diameter portion 52, and the upper stepped portion is provided. A seal member 65 is interposed between the 54 and the tube base 62. Therefore, the seal member 65 is brought into close contact with the storage pipe 42 and the pipe base 62 only by moving the upper stepped portion 54 of the storage pipe 42 and the pipe base 62 in the direction of approaching each other, and the storage pipe 66 in this close contact state. The sealability and the sealability can be improved by locking the 42.

In the reactor water level detection device of the present embodiment, the support pipe 61 is fixed to the upper core plate 20, the lower end of the storage pipe 42 is movably supported by the support pipe 61 along the longitudinal direction, and the compression coil spring 64 is used. The seal member 65 is urged and supported in the direction in which it is pressed. Therefore, by moving the storage pipe 42 upward with respect to the pipe base 62, the seal member 65 can be brought into close contact with the storage pipe 42 and the pipe base 62, and the storage pipe 42 is locked by the clip 66 in this close contact state. do it. Further, when the clip 66 is removed to release the locked state of the storage pipe 42, the storage pipe 42 is lowered by its own weight, but since the storage pipe 42 is supported by the urging force of the compression coil spring 64, the upper core plate 20 The collision with the storage pipe 42 can be prevented, and the storage pipe 42 can be prevented from being damaged.

In the reactor water level detection device of the present embodiment, the storage pipe 42 is supported by the urging force of the compression coil spring 64 with the lower end portion separated from the upper core plate 20. Therefore, the amount of movement of the storage pipe 42 with respect to the tube base 62 can be secured to improve the mountability of the seal member 65, and the impact of the storage pipe 42 when descending is alleviated by the compression coil spring 64 for storage. Damage to the pipe 42 can be prevented.

In the reactor water level detection device of the present embodiment, the support pipe 61 has a tubular shape, the lower end of the storage pipe 42 is arranged in the support pipe 61, and the storage pipe 42 is positioned between the support pipe 61 and the storage pipe 42. A leaf spring 63 for holding is provided. Therefore, since the storage pipe 42 is supported by the support pipe 61 via the leaf spring 63, the storage pipe 42 is stably supported at a predetermined position with respect to the upper core plate 20, and the reactor vessel The lid 13 can be easily attached to the reactor vessel body 12.

Further, in the reactor of the present embodiment, the reactor water level detection device 40 is provided in the reactor vessel 11. Therefore, the water level of the primary cooling water in the reactor vessel 11 can be detected with high accuracy, and the workability of the maintenance work of the reactor can be improved.

In the above-described embodiment, the compression coil spring 64 as the urging member is arranged below the storage pipe 42 as the storage member, but the position is not limited to this. For example, a flange portion or a stepped portion is provided in the middle portion of the storage member in the longitudinal direction, while a spring receiving portion is provided in the support member, and an urging member is interposed between the flange portion or the stepped portion and the spring receiving portion. You may. Further, the storage member may be divided into two, and the urging member may be interposed between the upper storage member and the lower storage member. Further, the urging member is not limited to the compression coil spring 64, and may be composed of a tension spring, a rubber member, a resin member, or the like.

Further, in the above-described embodiment, the water level detection device 40 is supported on the upper core plate 20 as a support member on the inner structure side, but the support on the other inner structure side such as the upper core support plate 19 is supported. It may be configured to support the member.

Further, although the reactor has been described as a pressurized water reactor in the above-described embodiment, it may be applied to a boiling water reactor (BWR: Boiling Water Reactor) or a fast breeder reactor (FBR: Fast Breeder Reactor). ..

10 Pressurized water reactor 11 Reactor vessel 12 Reactor vessel body 13 Reactor vessel lid 18 Core tank 19 Upper core support plate 20 Upper core plate (support member)
25 Core 26 Fuel assembly 27 Control rod 40 Water level detector 41 Water level gauge 42 Storage pipe (storage member)
51 Main body 52 Upper small diameter part 53 Lower small diameter part 54 Upper stepped part 55 Lower stepped part 61 Support pipe (support member)
62 Tube stand 63 Leaf spring (positioning member)
64 Compression coil spring (urging member)
65 Seal member 66 Clip (locking member)

Claims (6)

A water level gauge that detects the water level of the coolant,
A storage member for storing the water level gauge and
With
The lower portion of the storage member is supported by a support member provided on the furnace internal structure side, and the lower end portion is urged and supported upward in the vertical direction by a spring, so that the lower end portion is vertically oriented from the furnace internal structure. The upper part is detachably supported with respect to the reactor vessel lid, while being supported apart from each other.
A reactor water level detector characterized by this. The atom according to claim 1, wherein the pedestal is fixed to the reactor vessel lid, and the upper end of the storage member penetrates the pedestal and is detachably locked by the locking member. Reactor water level detector. The storage member is provided with a main body portion and an upper small diameter portion, a stepped portion is provided between the main body portion and the upper small diameter portion, and a seal member is provided between the stepped portion and the tubular base. The reactor water level detection device according to claim 2, wherein the reactor water level detection device is provided. The support member is fixed to the structure inside the furnace, and the lower end of the storage member is movably supported by the support member along the longitudinal direction, and the seal member is pressed by the spring. The reactor water level detection device according to claim 3, wherein the reactor water level detection device is urged and supported. The support member has a tubular shape, the lower end of the storage member is arranged in the support member, and a positioning member for positioning and holding the storage member is provided between the support member and the storage member. The reactor water level detecting apparatus according to claim 4 . A nuclear reactor according to any one of claims 1 to 5 , wherein the nuclear reactor water level detection device is provided.

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