JPS59102190A - Control rod drive mechanism - 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 boiling water nuclear reactor, and particularly to a control rod drive mechanism for controlling the drive of control rods.

[Technical backbone of the invention]

', pJ 4 A conventional example will be explained with reference to FIG. 1 m and V. In the figure, 1 indicates the reactor pressure vessel. The reactor pressure vessel 1 accommodates a reactor core.

The reactor core Z is composed of a plurality of fuel assemblies (not shown) and a plurality of control rods 4 inserted in a grid pattern between the fuel assemblies. The cooling water 5 in the reactor pressure vessel 1 flows through the reactor core from below to above, and the heated cooling water 5 rises in temperature at that time and enters a two-phase flow state of water and steam into a steam-water separator (not shown). into which air and water are separated. The separated steam then flows into a steam dryer (not shown) installed above the steam separator and becomes dry steam via the main steam pipe 6 connected to the multi-reactor pressure vessel 1). The configuration is such that the gas is sent to a turbine system (not shown). Said reactor core! Control rod 4 below
A plurality of control rod guide tubes 7 are arranged corresponding to the positions of the control rod guide tubes 7. Below the control rod guide tubes 7, a control rod drive mechanism housing (hereinafter referred to as CHD housing) 8 is located at the bottom of the reactor pressure vessel 1. It is arranged to penetrate through the IA. A control rod drive mechanism main body (hereinafter referred to as CHD main body) 9 is inserted into the control rod drive mechanism housing 8 from below, and is located at the lower end. The shaft is flange-jointed by the root 1.

The CRD main body 9 and the control rod 4 are connected via a drive rod 10.
This configuration controls the insertion into or withdrawal from the reactor core 2. In other words, the control rod 4 is connected to the CRD main body 9.
The structure is such that the nuclear reaction in the reactor core is suppressed by inserting it into the reactor core 2, and the nuclear reaction is promoted by withdrawing it.

According to the above configuration, as shown in FIG.
If the CHD main body 9 is damaged, there is a risk that the CHD main body 9 may fall downward. In addition, as shown in Figure 3, if any cross section of the CRD housing 8 outside the reactor pressure vessel 1 is damaged, or if the weld between the CBD housing 8 and the reactor pressure vessel 1 is damaged, , the CRD housing 8 and even the control rods 4"! may fall. As a result, the cooling water 5 in the reactor pressure vessel 1 leaks out, making it impossible to control the nuclear reaction in the reactor core. Therefore, conventionally, as shown in Fig. 4, the JCRD main body 9 and CHD housing 8 are supported by rods 12, grids 13, grid retainers 14, etc. below the reactor pressure vessel 1 to prevent vibrations or damage caused by earthquakes, etc. It has a structure that prevents it from falling.

[Problems with background technology]

According to the above configuration, the rod 12. The support mechanism consisting of the grid 13, grid holder 14, etc. is complicated and must be disassembled during periodic inspections, for example.

When assembling, it takes a long time, which is not desirable in terms of reducing radiation exposure to workers.

[Purpose of the invention]

The purpose of the present invention is to support the CRD main body and the CHD housing with a simple structure to reliably prevent accidents such as dropping children, thereby shortening the work time during periodic inspections, etc., and reducing the radiation exposure of workers. The object of the present invention is to provide a control rod drive mechanism capable of

[Summary of the invention]

The control rod drive mechanism according to the present invention includes a control rod drive mechanism housing fixed to a reactor pressure vessel, and the control rods are inserted from below into the inner circumferential side of the drive mechanism housing and the control rod portion 1i is inserted into the control rod portion 1i at the lower end. A control rod drive mechanism main body that is closely joined together, a female fitting portion formed on an upper inner circumferential surface of the control rod drive mechanism housing, and a female fitting portion formed on an upper outer circumferential surface of the control rod drive mechanism main body. This configuration includes a fitting portion and a female fitting portion that constitutes a bayonet mechanism.

In other words, whereas conventionally the control rod drive mechanism housing and the control rod drive mechanism main body were supported below the reactor pressure vessel, a female fitting part is formed on the inner peripheral surface of the upper part of the control rod drive mechanism housing to support the control rod drive mechanism housing and the control rod drive mechanism body below the reactor pressure vessel. A female fitting part is provided on the upper outer circumferential surface of the rod drive mechanism main body, and the rod drive mechanism is supported by a bayonet mechanism formed by the female fitting part and the female fitting part.

Therefore, the space below the reactor pressure vessel is simplified, and a support function can be obtained with a simple configuration, so the time required for periodic inspections, for example, can be greatly shortened, and workers' exposure reduction parts can be damaged. Since it is possible to reliably prevent the control rods from falling due to damage occurring in the lower portion of the reactor pressure vessel of the control rod drive mechanism housing, safety and soundness can be greatly improved.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 5 and 6. In the figure, reference numeral 101 indicates the bottom of the reactor pressure vessel 101. The CHD housing 10 passes through this bottom portion 101k.
2 is provided and welded at the upper end of the penetration. A control rod guide tube 103 is disposed above the CRD housing 102 with its lower end fitted into the upper end of the CRD housing 102, and a CRD main body 104 is inserted into the CHD housing 102 from below. It has been inserted. And the lower end 7 runno 104 of this CRD main body 104
The lower end flange 102 of the CHD haunong 102 mentioned above
A and lr! It is connected to a bolt 106 via a packing 105. A drive rod 107 is connected to the upper end of the CRD main body 104, and the control rod 10B is inserted into or withdrawn from the reactor core via the drive rod 107. A female fitting portion 109 is formed on the upper inner peripheral surface of the CRD housing 102, and
A female fitting part 110, which forms a bayonet mechanism with the female fitting part 109, is formed on the upper outer peripheral surface of the D main body 104. That is, as shown in Figure 6 (4), first CR
Insert the D main body 104 into the CRD housing 102.

Then, as shown in FIG. 6(B), the CRD main body 104 is rotated and the protrusion 111 of the female fitting part 110 is inserted into the female fitting part 1.
09 to form a connected state as shown in FIG. 6(C). Now, 10,000-CRD housing 102
and the CRD main body 104 are connected? Even if the bolt 11 is damaged or the lower part of the reactor pressure vessel 101 of the CHD housing 102 ruptures, the
This configuration can prevent the RD main body 104 and control rod 108 from falling. And CRD No ~ Uzing 10
An annular ring 113 formed in a skirt shape is provided above the penetrating portion of the bottom portion 101A of No. 2. In other words, even if the welded part connecting the 100-CRD housing 102 and the bottom 101 is damaged, the annular ring 113 contacts the bottom 101k, so that the υCRD and the housing 1 are
This is a configuration that can prevent 02 from falling.

According to the above configuration, it is possible to eliminate the support mechanism consisting of a companion rod, a grid, a grid holder, etc. that conventionally supports the CHD housing 102 and the CRD main body 104 below the reactor pressure vessel 101. This simplifies the space required for regular inspection work, for example, and improves work efficiency, shortens work time, and reduces radiation exposure for workers. Even if, for example, the bolt 106 is damaged or the CRD housing 102 located below the reactor pressure vessel 101 is broken, the bayonet mechanism formed by the female fitting part 109 and the female fitting part 110 will continue to connect. Because it is CRD
It is possible to reliably prevent the main body 104 and the control rod 10B from falling. Furthermore, if the welded part between the CHD housing 102 and the reactor pressure vessel 101 is damaged, the annular ring 113 will come into contact with the bottom 101k of the reactor pressure vessel 101, thereby damaging not only the CRD housing 102 but also the CHD main body 104 and the control rod 108. This can significantly improve safety and soundness with a simple configuration.

Next, another embodiment will be described with reference to FIGS. 7 and 8. In this embodiment, a CHD main body 10 is added to the configuration of the previous embodiment.
4 and the control rod guide tube 103 and the adjacent C
This is a configuration in which a rotation prevention mechanism is provided between the HD housings 102. That is, an upper female fitting part 114 is formed by extending the female fitting part 110 of the CRD main body 104 upward. An upper female fitting part 115 is formed on the outer periphery of the lower end of the control rod guide tube 103, and forms a bayonet mechanism with the upper female fitting part 114. The connection between the upper female fitting part 114 and the upper female fitting part 115 is configured to prevent the control rod guide tube 103, the reactor core, etc. from floating even when an upward load is applied, for example. At this time, the axial gap violet between the upper female fitting part 114 and the upper female fitting part β 115 corresponds to the amount of vertical movement of the control rod guide tube 103 and the reactor core. This is to ensure that the integrity of the equipment and structures inside the reactor is maintained by making it as small as possible. The rotation prevention iFA structure is
It is composed of a fitting protrusion 116 protruding from the cylindrical portion of one lower end flange 102A of the adjacent CHD housing 102, and a fitting recess 117 formed on the other cylindrical portion and fitting into the fitting protrusion 116. ing. And this fitting convex part 1
16 and the fitting recess 117, the rotation of the CHD housing 1020 is prevented, for example, the CRD housing 1
This configuration prevents the bayonet mechanism between the CRD housing 102 and the CRD main body 104 from coming off even if the welded portion between the CRD housing 102 and the bottom 101A of the reactor pressure vessel 101 is damaged. At this time, the CRD main body 104 is
When inserted into the RD housing 102, its position is determined by a positioning pin (not shown), so that it does not rotate.

According to the above configuration, not only can the same effects as those of the above embodiments be achieved, but also the floating of the control rod guide tube 103, the reactor core, etc. can be prevented, and the integrity of the reactor equipment, structures, etc. can be maintained. can be maintained reliably. Furthermore, due to the fitting between the fitting protrusion 116 and the fitting recess 117, the J C
Since rotation of the RD housing 102 can be prevented, for example, if the bolt 106 is damaged and the CRD housing 102 and the bottom part 101! ', even if the welded part between the CRD body 1θ4 and the C'RD housing 102 is damaged, the connection by the bayonet mechanism between the CRD body 1θ4 and the C'RD housing 102 will be reliably maintained, and the CRD body 104 and control rod 108 will not fall, making it safe. It can greatly improve your sexuality.

Note that the same parts as those in the above embodiment are denoted by the same reference numerals.
Descriptions of the same constituent parts have been omitted.

〔Effect of the invention〕

The control rod drive mechanism according to the present invention includes a control rod drive mechanism housing fixed to a reactor pressure vessel, a control rod drive mechanism main body joined to the control rod drive mechanism body, and a female part formed on the upper inner circumferential surface of the control rod drive mechanism housing. The control rod drive mechanism has a configuration including a female fitting part and a female fitting part formed on the upper outer circumferential surface of the control rod drive mechanism main body and forming a bayonet mechanism with the female fitting part.

In other words, whereas conventionally the control rod drive mechanism housing and the control rod drive mechanism main body were supported below the reactor pressure vessel, a female fitting part is formed on the inner peripheral surface of the upper part of the control rod drive mechanism housing to support the control rod drive mechanism housing and the control rod drive mechanism body below the reactor pressure vessel. A female fitting part is provided on the upper outer peripheral surface of the rod drive mechanism main body, and the rod drive mechanism is supported by a bayonet mechanism formed by the female fitting part and the female fitting part.

Therefore, the space below the reactor pressure vessel is simplified, and a support function can be obtained with a simple configuration, which can greatly reduce the time required for periodic inspections, and damage the radiation exposure reduction part of workers. Since it is possible to reliably prevent damage to the lower part of the reactor pressure vessel of the control rod drive mechanism or the control rod from falling, safety and soundness can be greatly improved.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams showing conventional examples, Figure 1 is a sectional view showing an outline of a boiling water reactor, Figures 2 and 3 are sectional views showing an example of a fall accident, and Figure 4 Figure (4)P (B) is a perspective view showing the support mechanism such as the control rod drive mechanism main body and the control rod drive mechanism housing. (C) is a plan view for explaining the action of the bayonet mechanism. 7 and 8 are views showing another embodiment, in which FIG. 7 is a cross-sectional view of the vicinity of the control rod drive mechanism, and FIG. 8 is a cross-sectional view taken along the line -■ in FIG. 7. DESCRIPTION OF SYMBOLS 101... Reactor pressure vessel, 102... CRD housing, 104... CRp main body, 109... Female fitting part, 110... Female fitting part. Applicant's agent Patent attorney Takehiko Suzue 535- Figure 2 Figure 3 11 11 Figure 4 Figure 5 Figure 6 (A) (B) (C) Figure 7 Figure 8

Claims (1)

[Scope of claims] A control rod drive comprising: a mating portion; and a female fitting portion formed on the upper outer circumferential surface of the control rod drive mechanism body and forming an ion-to-mechanism. Mechanism. (2) The female fitting part is a part that protrudes from the upper inner circumferential surface of the control rod drive mechanism housing and the inner circumferential surface of the housing.
The female fitting part is composed of a pair of protrusions that protrude from the upper outer circumferential surface of the control rod drive mechanism main body and a pair of protrusions that protrude from this outer circumference. A control rod drive mechanism according to claim 1.