JPS60147687A - Nuclear reactor - 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 nuclear reactors, and in particular to improvements in control rods and their drive mechanisms. The rod drive mechanism was installed at the top or bottom of the support section continuous with the control rods, and the drive motor was installed outside the reactor pressure vessel. For this reason,
The control rod support section and drive mechanism section occupying inside the reactor pressure vessel are extremely long, and the drive mechanism motor section outside the reactor is also long, making it possible to downsize the reactor pressure vessel and reduce the overall size of the reactor. It was impossible to reduce the height. Particularly in a type of nuclear reactor in which a heat exchanger is installed within the reactor pressure vessel, there has been a major problem in utilizing the space above the reactor core.

[Purpose of the invention]

The present invention was made in view of the current situation, and it is possible to reduce the volume occupied by the control rod drive mechanism in the reactor pressure vessel as much as possible, simplify the structure and handling, and make it possible to It is an object of the present invention to provide a nuclear reactor whose entire reactor can be downsized and its height can be reduced to improve earthquake resistance, and whose building can be downsized to reduce construction and maintenance costs.

[Outline of the invention]

The present invention provides, as means for achieving the above object, a plurality of control rod guide tubes with a watertight structure arranged in a reactor core, and a storage box with a watertight structure connected to at least one of the upper and lower ends of the control rod guide tubes. A nuclear reactor is constructed of a control rod that is accommodated in the housing box in a bent state and is fed out into the control rod guide tube by a drive device.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Figure 7 shows a natural circulation cooling type reactor in which a heat exchanger is installed inside the reactor pressure vessel. In the figure, l is the reactor pressure vessel, and inside this reactor pressure vessel, A reactor core λ is installed below the center, a riser 3 for increasing the buoyancy of the coolant is installed above it, and a heat exchanger ψ is installed above it.

At the lower end of the core, a lower core/IJ hood is installed as shown in Figure 1, and inside the core,
A plurality of control rod guide tubes 6 having a flat plate-like watertight structure are inserted from below parallel to the in-core fuel channel, and each control rod guide tube 6 is fixed to the core lower grid j, respectively.

As shown in FIGS. 1 and 2, storage boxes 7 each having a honeycomb structure are connected to the lower ends of each of these control rod guide tubes. It is fixed to the grid mounting part.

As shown in FIG. 1, this storage box 7 also contains a drive motor that incorporates a reducer and a brake (none of which are shown), a drive mechanism section that will be described in detail later, and a control unit that can be accommodated in a bent state. The rods 10 are arranged respectively, and the storage box 7
The interior is filled with gas at atmospheric pressure or a constant pressure, making maintenance free for lubrication and corrosion of the drive mechanism.

Further, as shown in FIG. 1, the power and signal transmission lines for the drive motors housed in each storage box 7 are passed through a flexible electric conduit 12 that protects the reactor from high-pressure water. It has been pulled out of the pressure vessel. and said′
The connection part of the fJLal pipe with the storage box 7 and the penetration part of the reactor pressure vessel are sealed with a watertight seal 1 as shown in FIG.
Each of the three types has a water honey structure.

As shown in FIG. 2, the drive mechanism section includes drive gears /4' disposed at the top and bottom of a drive motor installed in the center of the storage box 7, and these drive gears /4'.
' is a bevel gear fixed to the output shaft of the drive motor.
It is connected to the drive motor via a bevel gear /A that is integrated with S and drive gear /4', and is driven to rotate in forward and reverse directions at a variable speed by a control signal sent to the drive motor through terminal /7. 0, and the control rod 10 is hooked to both drive gears /4' and is bent and accommodated in the storage box 7 in a wound state during rotation. When the control rod is rotated in the normal direction, it is fed out to the side of the control rod guide 6, and when the drive gear is reversed, it is accommodated in the storage box 7. As shown in the figure, a guide gear /g and a guide partition plate /9 are installed to maintain the attitude of the control rod 10 in a normal state at all times.

On the other hand, the control rod 10 includes a number of poison plates 20 housed in a metal sheath, as shown in FIGS. 3 and 4, for example.
, two chains 2/ that bendably connect these positions on both sides, and a large number of guide rollers arranged on the outside of each chain 2/ to reduce resistance when the control rod IO is operated.
22, the drive gear and the guide gear are adapted to mesh with both chains.

Next, the effect will be explained.

When a nuclear reaction occurs in the reactor core λ, the heat generated by the nuclear reaction heats the cooling chamber, the density decreases, and the buoyant force generated is expanded in the reactor core λ, and the flow of coolant generated by natural circulation forces −
heat is removed. The heated coolant is then heat exchanged in the heat exchanger φ. On the other hand, the output control of the reactor is carried out in a plurality of control rod guide tubes 6 arranged in the reactor core λ, which are housed in the accommodation box 7. This is done by inserting the control rod /θ and adjusting the amount of insertion.

In this case, first, the drive motor is started by remote control, and both seven drive gears are rotated in the direction in which the control rod 10 is fed out. Then, as shown in FIG. 2, the control rod 10, which is bent and accommodated between both drive gears in a half-rotation state, is gradually drawn out into the control rod guide tube 6. Conversely, when the control rod 10 inserted and housed in the control rod guide tube 6 is to be pulled out from the reactor core, the drive motor is reversed.

Therefore, the amount of insertion of the control rods 10 into the core λ changes,
This controls the power output of the reactor. At this time, the speed at which the control rods 10 are inserted into and withdrawn from the core is adjusted by sending a control signal to the drive motor via the terminal 7i and controlling its rotation speed. In addition, by increasing the rotational speed of the drive motor during a scram, the predetermined scram time can be increased.

In addition, the control rod 10 is held in a fixed position by a brake (not shown) built into the drive motor, and by a control rod guide tube 6.
, the guide partition plate/9 in the storage box 7, and the guide roller 2 of the control rod/θ.

In addition, since the brakes are applied during a power outage, the control rods 10 are held in the position immediately before the power outage, and therefore a scram does not occur. However, if an emergency shutdown is particularly necessary, a separate reactor shutdown system, such as a PORON What is necessary is to use a system etc.

On the other hand, the control W guide tube 6 and the storage box 7 are attached to and detached from the reactor core by lifting the core grid from which fuel has been removed upwards, and then remotely controlling the lower grid j. On this occasion,
Since these have a completely independent structure from the reactor core and fuel, it is extremely convenient and work is easy because the electric conduit/2 is flexible.

Therefore, by using the control rod 10 that can be bent and accommodated, the parts related to the control rod θ are small, the inside of the reactor pressure vessel is effectively utilized, and the reactor pressure vessel is made smaller. Becomes Noh.

In addition, since a through hole for the control rod 10 into the reactor pressure vessel is not required, manufacturing is easy and inexpensive, and safety can be improved.

In addition, the control rod drive mechanism is simple and inexpensive, and the operation is reliable and safe, and maintenance is extremely easy.

In addition, the height of the entire gonzi furnace can be reduced, which is advantageous from the standpoint of earthquake resistance and economy. Additionally, the building can be made smaller.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but the structure of the control rod 10 may be made into a rod shape with the epicenter being a rod shape, or the t source of the calming motor may be made into a battery and this may be incorporated into a seven-tata. Alternatively, it is also possible to arrange the driving part of the control rod 10 at the upper part of the reactor core, and furthermore, it is also possible to arrange the control rod 10 to be stored by bending it instead of winding it up.

Further, in the above embodiments, a natural circulation cooling type nuclear reactor was used as an example, but the present invention can be similarly applied to a forced circulation cooling type nuclear reactor.

〔Effect of the invention〕

As explained above, the present invention uses a bendable control rod, which is bent and accommodated in the storage box.
By reducing the volume occupied by the control rod drive mechanism in the reactor pressure vessel, the entire reactor can be downsized, the overall height can be reduced, and the building can be downsized. The fc structure and handling are simple, maintenance is easy, and safety can be improved.

In addition, since the inside of the reactor pressure vessel can be effectively used, it is effective for ships with small and medium-sized reactors in which a heat exchanger and a steam generator are arranged inside the pressure reactor.

[Brief explanation of drawings]

1M is a cross-sectional view of a natural circulation cooling reactor showing an embodiment of the present invention, FIG. 2 is a detailed view of the containment box, FIG. 3 is a detailed view of the control rod, and ≠ is FIG. FIG. c...Reactor pressure vessel, λ...core, ψ...heat exchanger, j...core lower grid, 6...control rod guide tube, 7...accommodation box, ri... Drive motor, 10...
Control rod, /l...Power transmission line, 7.2...Electric conduit, /l
I...Drive gear, /Za...Guide gear, /9...
Guide partition plate, 20... Poison plate, 2/... Teen, n... Guide roller. Applicant's agent Inomata Thin cylinder Figure 1 Figure 2 Figure 43 Figure 4

Claims (1)

[Scope of Claims] /) A plurality of watertight control rod guide tubes arranged in the reactor core, a watertight storage box connected to at least one of the upper and lower ends of the control rod guide tubes, and a watertight storage box connected to at least one end of the control rod guide tube; A nuclear reactor comprising: a control rod that is accommodated in a bent state in a box and is fed out into the control rod guide tube by a drive device. d) The nuclear reactor according to claim 1, characterized in that the power supply cable of the drive device is led out of the reactor pressure vessel through a tube that watertightly connects the storage box and the reactor pressure vessel.