JPS5970994A - Supporting device for control rod drive housing - 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 C. The present invention relates to a control rod drive mechanism bar in a boiling water nuclear reactor.
This invention relates to a device for supporting a song in a nuclear reactor pressure vessel.

[Technical background of the invention]

With reference to FIGS. 1 to 6, the conventional control rod drive mechanism (
Hereinafter, it will be referred to as CHD. ) Describe the housing support device.

Reference numeral 2 in FIG. 1 is a reactor pressure vessel, and this reactor pressure vessel 2 houses a reactor core 4 therein. In addition, the reactor pressure vessel 2 is filled with reactor water 6 as a coolant.
It is configured to cool the reactor core 4.

A plurality of CHDs penetrate through the lower blunt part of the reactor pressure vessel 20.
(not shown) is provided. This CHD is housed in a cylindrical CRD housing 8 that penetrates the lower part of the reactor pressure vessel 20, and is driven by water pressure and positioned upward. The control rods 1o... are configured to be inserted into and removed from the reactor core 2.

A control rod guide tube 12 (
Hereinafter referred to as CRGT. ) is connected, this CR
GTJ? penetrates the core support plate 14 and is connected to the lower part of the core 4. In the figure, reference numeral 16 denotes an upper lattice plate, and this upper lattice plate 16 supports the fully inserted control rod 10 in the horizontal direction.

The reactor pressure vessel 2 is placed on a cylindrical base (・i;′, Js) called a pedestal, and this base hole L
1B surrounds the CRD housing 8.

Still provided within the foundation 18 is a conventional CRD housing support device 20 . This support device 20 is a beam 2
2. Rod 24. Support block 26. It consists of a support par 289 and a disc spring 30, and is configured to support the CRD housing 8 from below.

As shown in FIGS. 2 and 3, the CHD housing 8 is connected to the reactor pressure vessel 2 via a stub tube 32 protruding from the inner surface of the lower mirror portion of the reactor pressure vessel 2 to maintain watertightness. ing.

The lower end opening of the CRD housing 8 is sealed with a flange 34. Further, a thermal sleeve 34 is housed within the CRD housing 8, and the CRD 36 is housed inside the thermal sleeve 34. CR
The upper end of the D housing 8 is connected to the CRGT 12.

As shown in FIG. 3, a control rod 10 is housed inside the CRGT 72, and this control rod 10 is connected to the CRD 36. CRGT7. ? is the core support plate 14
It is connected to the reactor core 4 by passing through it.

The control rod 10 has a cruciform cross-sectional shape and is configured to absorb thermal neutrons and suppress the reactivity of the reactor core 4. Four fuel II assemblies 42 are arranged around the control rod 10 via fuel support fittings 40. In this fuel assembly 42 and control rod 10, the unit cell is
has been completed.

This unit grid is supported by the upper grid plate 16.

Note that the core support plate 14 and the upper grid plate 16 are supported by a core searoud 44 surrounding the core 4 .

With reference to FIG. 4, the CRD housing 8 and the CRGT
The connection mechanism with 12 will now be explained. 21'! 46 in 4 figures
1 are engagement protrusions projecting inward from the upper end of the thermal sleeve 34, and several protrusions 46 are provided at equal intervals on the inner peripheral surface of the thermal sleeve 34.

On the other hand, CRGT1. ? The lower end portion is shaped to be inserted into the inner surface of the thermal sleeve 34, and an L-shaped retaining groove into which the engaging protrusion 46 engages is formed in this lower end portion. This engagement property and the engagement protrusion 46 are engaged in the vertical direction and then rotated and fixed in the circumferential direction, which is a so-called bayonet mechanism.
l'j are formed from the first to the first.

Further, a key 48 is fitted into the outer periphery of the lower end of the thermal sleeve 34, and fixes the thermal sleeve 34 and the CRD housing 8.

Therefore, said CRGTI, ? is thermal sleeve 3
4 to engage the bayonet)
The thermal sleeve 34 cannot be removed unless the key 48 is removed, and the thermal sleeve 34 cannot be rotated unless the key 48 is removed.

By the way, in the unlikely event that the melted part of the stub tube 32 breaks 4.
If it is zero, there is a risk that the CRD housing 8 will fall down and the reactor water 6 will flow out. The CRD housing support device 20 is configured to support the CRD housing 8 from below.

A conventional CHD housing support device 20 will be described below with reference to FIGS. 5 and 6. Reference numeral 22 in FIG. 5 is a beam, and this beam 22 is installed within the foundation 18 through a gap between the CRD housings 80, in which a plurality of beams are provided. A plurality of rods 2 pass through the beam 22.
4 is installed vertically, and a disc spring 30 is attached to the upper end of the rod 24.
is attached so as to force the rod 24 upward. The rod 24 still extends below the CRD housing 8, and a support block 26 is gripped at the lower end of the rod 24. Is this support block 26 +at? , l are arranged parallel to the beam 22.

Further, a support par 28 is installed on the upper surface of the support block 26. As shown in FIG. 6, this support par 28 is configured to support the CRD housing 8 from below with the aid of a flange 34.

[Problems with background technology]

The conventional CRD housing support device 20 has the following problems.

First, when inspecting and repairing the CRD, it was necessary to remove the support device 20. However, the inside of the foundation 18 where the support device 20 is installed has a high radiation level, and if a worker enters the foundation 18 and performs the above-mentioned removal work, there is a problem that the amount of radiation exposure of the worker increases.

If the CRD machine 41k is changed to electric type etc., CHD
There was also a risk that the shapes of the housing 8 and the flange 34 would change, making it impossible to install the support device 20 as described above.

[Purpose of the invention]

The purpose of the present invention is to reduce the radiation exposure of workers by eliminating the need for workers to enter the rusted area and perform removal work, and to reduce the radiation exposure of workers. To provide a CRD housing support device that can be installed even if the shape is changed.

[Summary of the invention]

The CRD housing support insert 1 according to the present invention includes an engaging body provided on the outer peripheral surface of the CRGT that passes through the core support plate,
This engaging body is engaged with the core support plate to support the CRD housing.

[Actual example of invention]

A first embodiment of the present invention will be described with reference to FIGS. 7 and 8. In addition, the same reference numerals are used in the figures to avoid duplication of explanatory text.

12th out of 71!2j is CRGT, and this CRGT
l2 penetrates the core support plate 14 and connects the upper part to the core support plate 14.
It protrudes upward. CRGTJ,? An engaging body 102 is provided to protrude from the upper outer circumferential surface of. As shown in FIG. 8, the engaging bodies 102 are formed at four equal intervals on the outer periphery of the CR (112), and are configured to engage with the upper surface of the core support plate 14.

The operation of the apparatus configured as above will be explained.

In the unlikely event that the welded portion of the stub tube 32 is damaged, the CRD housing 8 will tend to fall off downward. Therefore, since the CRD) h Ujifugu 8 is connected to the CRGT I 2, the engagement body 102 of the CRGT I 2 engages with the core support plate 14, thereby supporting the CRD housing 8 and preventing it from falling downward. .

The advantages of the apparatus according to the first embodiment of the present invention will be explained.

First, a worker like the conventional one supports the support device t20f: the foundation 18.
It is possible to reduce the amount of radiation exposure of workers without having to go into the interior and remove it. It's a moat, the removal work of CRGT 12 is as mentioned above, CRD housing 8 and CRGT
J.? CRGTJ2 can be removed by lifting it from above the reactor core.

Next, since it is not dependent on the shape of the CRD housing 8, it can be easily installed even in electric type CHDs.

A second embodiment of the present invention will be described with reference to FIG. This second embodiment is CRGTl,? A protruding body 104 protrudes from the outer periphery of the protruding body 104 and a loose 11 fixed to the lower surface side of the protruding body 104.
The seven bodies 106 form a holding body 108.

In addition to the advantages obtained in the first embodiment, the second embodiment can buffer the impact force generated between the protrusion 104 and the core support plate 14.

Note that the present invention is not limited to the above two embodiments. Other embodiments will be described below with reference to FIGS. 10 to 14.

A third practical example of the present invention will be described with reference to FIG. In this third embodiment, an engaging body 110 in the form of a projecting peripheral wall is formed on the outer periphery of the CRD housing 8, and the engaging body 110 is attached to the core support plate 14.
It is designed to engage.

In the third embodiment described above, the strength of the holding body 110 can be improved and the reliability can be further improved.

A 21;4 e17 embodiment of the present invention will be explained with reference to FIG. In this fourth embodiment, an engaging body 114 is formed by a protrusion 104 protruding from the outer periphery of the CRGTJ 2 and a spacer 112 welded to the protrusion.

In this fourth embodiment, the spacer 112 can compensate for the dimensional error in the vertical direction that occurs between the projecting body 104 and the core support plate 14.

A fifth embodiment of the present invention will be described with reference to FIG. In this fifth embodiment, a spacer 116 is passed through the projecting body 104.

A sixth embodiment of the present invention will be described with reference to FIG. In this sixth embodiment, an engaging body is constructed by a protruding body 104, a spacer 118 loosely inserted into the protruding body 104, and a buffer body 120 interposed between the spacer 118 and the protruding body 104.
22.

Furthermore, the present invention is not limited to the connection mechanism as shown in FIG. 4, and as shown in FIG.
It can also be applied to those fixed with 24. In this case, the above-mentioned bayonet ramming mechanism may be released by rotating CRGTJ2.

〔Effect of the invention〕

As described in detail below, according to the present invention, the worker's radiation &
lThe amount of applied Wd can be reduced, and even if the shape of the CRD housing is changed, it can be easily installed in one piece.
An RD housing support device can be provided, the effect of which is canine.

[Brief explanation of the drawing]

Figures 1 to 6 are diagrams showing conventional examples,
Figure 1 is a longitudinal if'j-r view of the reactor pressure vessel, Figure 2 is a longitudinal sectional view of the CRD housing 8, and Figure 31 is a CRGT.
Vertical sectional view of J2, Figure 4 shows CHD housing 8 and CRG
A vertical sectional view showing the connection ta'M with T12, FIG.
An old perspective view of the HD housing support device 20, FIG. 6 is a CRD
911i view of the lower end of the housing support device 2θ, a)
Figures 7 to 8 are diagrams showing the first embodiment of the present invention. Figure 7 is a longitudinal cross-sectional view of the CRGT 72, and Figure 8 is a cross-sectional view of the CRGT 72.
FIG. 9 is a plan view of C, which shows the second embodiment of the present invention.
FIG. 10 is a vertical cross-sectional view of RG'l12 and shows CRGT7. ? The plan view of FIG. 11 shows the fourth embodiment of the present invention. FIG. 12 is a vertical cross-sectional view of CRGTJ2 showing the fifth embodiment of the present invention,
FIG. 13 is a vertical cross-sectional view of the CRGTJ2, not showing the sixth embodiment of the present invention, and FIG. 14 is a vertical cross-sectional view of a connecting mechanism showing a modification of the connecting mechanism shown in FIG. 4. 8... Control rod y (moving mechanism), Uzing (CRD),
12... Control rod guide tube (CRGT),
102°108.110,114,122. ... Engaging body, 104... Projection body, 106, 120... Buffer body, 112, 116.11 g... Spacer. Applicant's agent Patent attorney Takehiko Suzue 45 Figure 6 Figure 7 Figure 8 02 02 Figure 9 Figure 10 Figure 11 Figure 12 Figure 116 116 Figure 13 -454-

Claims (2)

[Claims] (1) A control rod drive mechanism housing that extends through the lower head of the reactor pressure vessel of a boiling water reactor, and a control rod that is connected to the upper end of this housing and extends through the core support plate. A control rod drive mechanism housing support device comprising: a guide tube; and an engaging body protruding from the outer circumference of the control rod guide tube and engaging with the core support plate. (2) The engaging body comprises a protruding body protruding from the outer circumference of the control rod guide tube, and a weighting body attached to the protruding body. The control rod drive mechanism housing support device described in item 1).