JP3153833B2 - Guide device for neutron flux detector in reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a neutron flux detector in a reactor for guiding a neutron flux detector in a reactor through a cylinder into a fuel assembly in a nuclear instrumentation facility of a nuclear reactor such as a pressurized water reactor. The present invention relates to a guide device.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional nuclear instrumentation facility and a nuclear instrumentation guide structure. The nuclear instrumentation equipment shown in FIG. 5 is a system in which the nuclear instrumentation detector 5 is inserted from the lower part of the core through the instrumentation nozzle 14 as a lower penetration part of the reactor vessel A, and the detector 5 and the in-core instrumentation thimble 7 It is a structure of guiding by a cylindrical body having the same inner diameter with a minute gap between them. For this reason, the in-core instrumentation thimble 7 serving as a guide path for the detector 5 needs a large bending radius as shown in FIG. 5, and has a bent portion outside the reactor vessel.

[0003] The in-furnace instrumentation thimble 7 needs to be pulled out of the fuel assembly at the time of refueling, and the swage lock seal provided on the seal table 28 is opened and pulled out. An isolation valve 29 is provided above the seal table 28. The detector 5 is connected to a coaxial cable for extracting a signal. Insertion or extraction of the detector into or from the furnace is performed by a driving device 13, and the insertion position of the detector is selected by a detector path selector 23, Perform at 24.

[0004]

In the conventional nuclear instrumentation equipment of a nuclear reactor, a large bending radius is required for detecting and inserting into and extracting from the inside of a cylinder having the same inside diameter having a minute gap around the detector 5, A bent portion is provided outside the reactor vessel A, and the detector is inserted through an instrumentation nozzle 14 below the reactor vessel A installed below the core.

Therefore, if the instrumentation nozzle 14 and the in-core instrumentation outlet pipe (conduit tube) are provided below the reactor vessel A, a large space is required below the reactor vessel A due to the arrangement. In addition, there is a possibility that coolant may leak from the lower part of the core due to poor construction or aging.

On the other hand, in order to solve these problems, it is conceivable to adopt a system in which the instrumentation nozzle 14 at the lower part of the reactor vessel A is abolished and the detector 5 for nuclear instrumentation is inserted from above the core. However, there is a control rod drive device on the upper part of the reactor vessel A, and it is difficult to apply the conventional method to the upper part of the reactor vessel A.

[0007] Under such circumstances, the present invention is provided with a guide support structure for a detector capable of inserting a detector for nuclear instrumentation from above the reactor core, and a guide support structure for the detector at the time of refueling. It is an object of the present invention to obtain a guide device for a neutron flux detector in a furnace that can improve handling efficiency.

[0008]

According to the present invention, there is provided a guide device for a neutron flux detector in a reactor, wherein a lower cylinder for guiding the neutron flux detector in the reactor is inserted into a fuel assembly in a reactor. A pipe, an upper core support plate for supporting an upper core support column for supporting the guide tube, an instrumentation nozzle installed on a batch lifting plate in the reactor, and penetrating a reactor vessel lid; An upper cylindrical body installed in a furnace instrumentation support column in a mounting nozzle, and an upper cylindrical body between the upper cylindrical body and the lower cylindrical body
And the middle cylinder with a larger diameter than the lower cylinder is connected
And a support member for guiding and supporting the intermediate body at a small curvature .

Further, another guiding device for a neutron flux detector in a reactor according to the present invention is such that the holding of the batch lifting plate by the reactor vessel lid can be released by opening the lid, and the batch lifting plate is connected to each of the cylinders. It can be lifted with the body.

[0010]

According to the present invention, the lower, upper and intermediate cylinders are disposed in the reactor vessel and partially connected to penetrate the reactor vessel lid, and the intermediate cylinder has a curvature. By providing a small bent portion, the guide of the neutron flux detector in the furnace is facilitated, and a compact arrangement as the in-core instrumentation equipment is enabled, so that the equipment cost can be reduced.

[0011] Further, since each cylindrical body is configured to be supported by an instrumentation nozzle, a support member, and the like on the lifting plate, the batch lifting plate is opened by opening the reactor vessel lid, and then using an elevator. By lifting, the neutron flux detector in the furnace together with each cylinder can be lifted at a time, thereby facilitating and speeding up refueling.

[0012]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a reactor structure employing a structure for guiding and supporting a neutron flux detector in a reactor of the present invention, and FIG. 2 is a schematic view showing a guide structure of the neutron flux detector in the reactor. First, the cylindrical bodies 1a to 1c for guiding the in-core neutron flux detector 5 , the in-core instrumentation support columns 3 and the support plate 4 for supporting the same are provided in the in-core neutron flux detector installed in the reactor vessel 15. It is supported on the upper surface of the batch lifting plate 43 of the support structure.

The upper portion of the cylindrical body 1a passes through the inside of the in-core instrumentation support column 3 for supporting the cylindrical body 1a, penetrates a cono seal 10 at the upper end of the support column 3, and as shown in FIG. Guided to the top. The penetrating portion of the lid 16 of the reactor vessel 15 uses a nozzle 8 of the same type as the in-core instrumentation nozzle conventionally used in a pressurized water light water reactor.

Further, the cylindrical body 1b has a bent portion in a horizontal and vertical plane for guiding from the nozzle section to the in-core nuclear instrumentation position. The lower portion of the cylindrical body 1c includes a guide tube 6 installed inside the upper core support column 18 and a thimble 7 for instrumentation of the fuel assembly 20 in the furnace.
To form a guide path for guiding the in-core neutron flux detector 5A into the core.

Further, details of the cylinders 1a to 1c having the straight portion and the bent portion for guiding the in-core neutron flux detector 5 and the structure for supporting the same are as shown in FIG.
a has a minute gap between the movable in-core neutron flux detector 5 like the in-core instrument thimble conventionally used in pressurized water light water reactors, and the instrumentation nozzle shown in FIG. 8, the diameter of the through hole of the cono seal 10 is reduced.

In FIG. 1, the small-diameter cylindrical body 1a passes through the inside of the in-core instrumentation support column 3 for supporting the cylindrical body 1a, passes through the cono-seal 10, and is guided to the upper part of the reactor. At 11, the leakage of the coolant is shut off. The penetrating portion of the reactor vessel lid 16 uses the instrumentation nozzle 8 conventionally used in a pressurized water reactor. The instrumentation nozzle 8 can be disassembled by opening and closing the Merman clamp 9, and is opened before lifting the reactor vessel lid 16 at the time of refueling.

As shown in FIG. 2, the cylinder 1b is a cylinder having two or more bent portions and straight portions, and has a diameter larger than that of the cylinder 1a. The cylindrical body 1b is supported by an integrated structure composed of a support column 4 for supporting the same and the in-furnace instrumentation support column 3. The cylinder 1b at the intermediate portion is constituted by a cylinder having an inner diameter larger than that of the upper cylinder 1a, and a joint between the small and large diameter cylinders has a joint 2 joined by welding or the like. And can be manufactured separately.

A feature of the present invention is to provide a guide path for the cylindrical body 1b having a larger inner diameter of the bent portion, so that the bending radius of the guide tube can be reduced in a narrow area such as the top plenum of the reactor vessel 16. Is small enough to guide the movable neutron flux detector 5 in the reactor.

As shown in FIG. 2, the cylindrical body 1c is formed of a small-diameter cylindrical body like the upper cylindrical body 1a, and the lower end has a square shape so that the cylindrical body 1a can be inserted smoothly. A structure in which shell-shaped end plugs from which are dropped are joined. During operation of the reactor, the cylinder 1c is inserted into the in-core instrumentation guide tube 6 as a guide tube for the upper core support column 18 and the instrumentation thimble 7 of the fuel assembly 20, and the neutron flux detector 5 is inserted into the core. Configure the path to be inserted into

The conventional fuel assembly has a structure which can be inserted into the instrumentation thimble 7 through the lower nozzle 27 of the fuel assembly 20 corresponding to the lower insertion type in-core instrumentation. Then, in order to enable the upper instrumentation type in-furnace instrumentation, a through hole is formed in the upper nozzle 26 so that the cylindrical body 1 c can be inserted from above the instrumentation thimble 7.

On the other hand, at the time of refueling, before the upper core structure is suspended from the reactor vessel 15, the cylindrical member inserted into the instrumentation thimble of the fuel assembly 20 below the upper core plate 19. Until the lower end of 1c is located above the upper core plate 19, it is lifted by the upper core structure lifting device shown in FIG. 4, so that the cylindrical body 1c does not come into contact with other members at the time of lifting and is damaged. Handle it.

FIG. 4 shows an example of the arrangement of the instrumentation equipment in the furnace of the upper insertion type. In this example, on the upper surface of a missile shield 22 installed above a lifting integrated structure 21 attached to a reactor vessel lid 16, detector path selectors 23 and 24 are arranged, and a driving device 25 is connected to a reactor cavity. By installing the inside of the furnace, the arrangement can be more compact than the conventional in-core instrumentation equipment shown in FIG.

Embodiment 2 FIG. It is necessary to install a plurality of the nuclear instrumentation detector guide structures of the present invention in the reactor vessel 15,
Performing the lifting work individually increases the refueling work time. In order to shorten the working time, all the core instrumentation detector guide structures 1 in the furnace are lifted at one time by a single lifting work.

The batch lifting structure shown in FIG. 4 has a structure in which an elevator 41 is attached to a conventional upper core structure lifting device 40 and is lifted at once by a batch lifting plate 43 installed on a flange portion of the reactor vessel. The fitting portion between the in-core core instrumentation support column lower fixed portion 12 and the collective lifting plate 43 has a structure in which the in-core core instrumentation support column 3 is fitted in a plane so as not to rotate in a horizontal plane and a vertical plane.

The cylindrical bodies 1a to 1 of the core instrumentation detector guide structure in the furnace
c is handled so as not to be damaged by contact with other members when lifted inside the upper core structure. The upper core structure lifting device shown in FIG. 4 has a structure having a stopper 42 for fixing the elevator 41 at the top dead center position.

The core instrumentation support column 3 and the batch lifting plate 43
Is lifted using a crane of a nuclear reactor. In order to provide a structure that can be lifted without using a polar crane at the time of the periodic inspection, it is possible to install an automatic lifting device in the upper core structure lifting device 40 and add a lifting function.

[0027]

As described above, according to the present invention, the guide tube in which the lower cylinder for guiding the in-reactor neutron flux detector is inserted into the fuel assembly in the reactor, and the guide tube are supported. An upper core support plate that supports the upper core support column, an instrumentation nozzle that is established on the batch lifting plate in the reactor, and penetrates the reactor vessel lid, and an in-core instrumentation in the instrumentation nozzle. An upper cylinder installed in the support column, and a middle cylinder having a larger diameter than the upper cylinder and the lower cylinder between the upper cylinder and the lower cylinder. body are connected, the cylindrical body of the intermediate portion and then, is guide supporting at small curvature by a support member, a movable incore neutron flux detector proven in existing reactors, the conventional guide structure This structure can be guided with a smaller bend radius, and if this structure is applied, the reactor penetration in a narrow area like the reactor top plenum can be achieved. The detector can be guided from the position to the instrumentation position, and the detector for in-core nuclear instrumentation can be inserted from the upper part of the reactor core. Since there is no need for a space below the reactor vessel, there is an effect that compact arrangement is possible.

Further, the basic shape of the reactor building is such that the lower part of the reactor vessel is dug deep, but it can be made a flat shape which does not require the space under the reactor vessel, and the amount of excavation can be reduced. It is also advantageous for foundation work.
Further, there is an effect that it is possible to eliminate the possibility of coolant leakage from below the core.

Further, according to the present invention, the holding of the batch lifting plate by the reactor vessel lid can be released by opening the lid, and the batch lifting plate can be lifted together with the respective cylinders. And speeding up can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of a guide device for a neutron flux detector in a reactor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a nuclear reactor having a guide device in FIG.

FIG. 3 is a layout view showing the in-furnace instrumentation device in FIG. 1;

FIG. 4 is a schematic configuration diagram showing a lifting function of the in-furnace instrumentation device in FIG.

FIG. 5 is a configuration diagram showing a conventional in-core nuclear instrumentation facility.

[Explanation of symbols]

1a, 1b, 1c Cylindrical body 4 Support plate (support member) 5 In- core neutron flux detector 6 Guide cylinder 8 Instrumentation nozzle 16 Reactor vessel lid 17 Upper core support plate 18 Upper core support column 20 Fuel assembly 43 Batch Lifting plate

Claims (1)

(57) [Claims] 1. A guide tube through which a lower cylinder for guiding a neutron flux detector in a reactor is inserted into a fuel assembly in a nuclear reactor,
An upper core support plate that supports an upper core support column that supports the guide tube, and is established on a batch lifting plate in the reactor,
An instrumentation nozzle that penetrates the reactor vessel lid, an upper cylinder installed in an in-core instrumentation support column in the instrumentation nozzle, and an upper cylinder and the lower cylinder. Between the upper cylinder and the lower
A connecting member connected to an intermediate cylindrical body having a diameter larger than that of the cylindrical body and guiding and supporting the intermediate cylindrical body at a small curvature;
Guiding device in the furnace neutron flux detector, characterized by that.