JP2946394B2 - Reactor power control mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor power control mechanism, and more particularly to a so-called satellite atom which is promising as an energy supply source for extraterrestrial or deep-sea stations such as lunar bases and artificial satellites. The present invention relates to a power control mechanism for a small special nuclear reactor such as a nuclear reactor.

[0002]

2. Description of the Related Art A liquid metal-cooled fast reactor is promising for a small special nuclear reactor as an energy supply source for a lunar base or a deep-sea station from the viewpoint of long fuel life and easy compactness. Have been. Conventionally, as a power control mechanism of such a small liquid metal-cooled fast reactor,
As described below, a method of controlling the reactivity of a core by displacing a control plate having a neutron absorbing ability with respect to the core in a solid reflector region surrounding the outer periphery of the core is known.

FIG. 2 is a schematic cross-sectional view of a small special nuclear reactor for a lunar surface that has already been proposed. The core configuration of this nuclear reactor is such that an outer core 2 surrounds an inner core 1, and the outer core 2 surrounds the inner core 1. 6 and one safety rod 3 are provided at the center of the core, and a coolant 4 made of liquid lithium is circulated around the outer periphery of the outer core 2. A furnace output is surrounded by a solid reflector region 8 made of beryllium, and a plurality of cylindrical control drums 5 arranged in the circumferential direction to surround the outer periphery of the core in the reflector region 8 to rotate around the axis. It is a control method.

Each of the control drums 5 is made of beryllium, and a neutron absorber 7 made of B ₄ C having a thickness t is attached to a part of the angular range of the outer peripheral surface to form a neutron absorber 6. By adjusting the rotation amount of the drum 5, the position (direction and distance) of the neutron absorber 6 with respect to the core in the reflector region 8 on the outer periphery of the core is changed to control the reactivity of the core.

[0005]

However, in the conventional output control mechanism as shown in FIG. 2, when power is not supplied to the motor responsible for rotating the control drum 5 due to, for example, loss of power, the control drum 5 operates. However, even if the furnace power increases for some reason, there is a problem that operations such as reactivity suppression and furnace shutdown cannot be performed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize a compact reactor required for a small special nuclear reactor and to provide a passive safety by a fail-safe function to a position control mechanism of a control board in the event of a power loss accident. It is to provide a furnace power control mechanism.

[0007]

According to the first aspect of the present invention,
A reactor power control mechanism that controls the reactivity of the core by displacing a control plate with neutron absorption capability with respect to the core in the liquid reflector area surrounding the outer periphery of the core, and moves toward and away from the core A rotary link mechanism that supports the control plate as much as possible and is constantly biased in a direction to bring the control plate closer to the core; and a control plate that is positioned at a predetermined distance from the core against the bias. The above-described subject is provided by providing a drive mechanism for adjusting, and a release mechanism for selectively releasing the control plate from the driving force of the drive mechanism and entrusting the approach movement toward the reactor core by the urging of the rotary link mechanism. Is solved.

According to a second aspect of the present invention, in the reactor power control mechanism, the release mechanism includes an electromagnetic lock device, and the electromagnetic lock device maintains the connection between the control plate and the drive mechanism in an energized state and in an unexcited state. Disengaging the connection between the control plate and the drive mechanism, and reducing the reactivity of the core to a predetermined furnace stop level when the disengaged control plate comes closest to the core by the bias of the rotating link mechanism. It is characterized by the following.

[0009]

The operation of the present invention will be described with reference to FIG. 1 corresponding to the embodiment. A liquid reflector region (14) made of water or liquid beryllium is provided around the outer periphery of a core (10). In the liquid reflector region (14), instead of the control drum (5) in the conventional example of FIG. 2, a plurality of control plates (1) made of a material having a neutron absorbing ability such as B ₄ C are provided.
3) is arranged so as to surround the core, and furthermore, these control plates (13) are supported by a rotary link mechanism (11) so as to be displaceable to a position approaching / separating from the core (10).

Each control plate (13) is provided with a rotating link mechanism (1).
1), the rotary link mechanism (11) is constantly urged in a direction to bring the control plate (13) closer to the core (10). Have been. For example, when this reactor is used in a gravitational field, the biasing of the rotary link mechanism can be achieved by the control plate and the gravity caused by its own load, which is selected depending on the relationship between the direction of gravity and the arrangement posture of the reactor. it can. On the other hand, when the nuclear reactor is used in a zero-gravity field or a low-gravity field, the rotary link mechanism (11) incorporates a spring mechanism that constantly urges the link toward the core.

The output control when the power for the drive system of the control mechanism is secured is determined in advance by the drive mechanism (15) from the core (10) against the bias of the control plate (13). This is performed by adjusting the position to the distance t.
In this case, at the position where the control plate (13) is displaced, the thickness of the reflector (14) around the core is adjusted simultaneously with the position of the control plate (13), which also contributes to the power control effect. Become.

The release mechanism (16) releases the control plate (13) from the driving force of the driving mechanism (15) by a selective operation performed when necessary, for example, when the power is lost. As a result, the control plate (13) is rotated by the rotating link mechanism (1).
It is entrusted to the approach movement in the core direction by the bias of 1).
The release mechanism (16) can be constituted by an electromagnetic lock device, and the electromagnetic lock device is energized and the control plate (1) is activated.
3) Maintaining the connection between the drive mechanism (15) and disengaging the connection between the control plate (13) and the drive mechanism (15) in a non-excited state, and the disengaged control plate (13) serves as a rotating link mechanism. Due to the bias of (11), the reactivity of the core is reduced to a predetermined reactor shutdown level when the core comes closest to the core (10).

Therefore, according to the reactor power control mechanism of the present invention, instead of disposing the rotary type cylindrical control drum in the solid reflector area, the control plate supported by the rotary link mechanism is used. By arranging it in the liquid reflector area, it is possible to achieve a compact structure around the reactor core, and to provide passive safety with a fail-safe function to the position control mechanism of the control board when power is lost or a trouble occurs. The output can be automatically controlled to the furnace stop side.

[0014]

FIG. 1 is a schematic longitudinal sectional view (upper view) and a schematic transverse sectional view (lower view) showing a configuration of a core portion of a small special nuclear reactor having an output control mechanism according to an embodiment of the present invention. , Core 1
Numeral 0 surrounds the core frame 17 by a liquid reflector 14 such as water or liquid beryllium filled in a container 18. B ₄ is contained in the liquid reflector 14 around the core frame 17.
Eleven control plates 13 made of a neutron absorbing material such as C are arranged so as to surround the core frame 17.
The arm is pivotally supported by a container 18 by each arm 12 of a movable link mechanism 11 at the upper and lower ends thereof so that the arm can be displaced to a position approaching / separating from the core 10.

Rotating link mechanism 1 supporting each control plate 13
1 is constantly urged in a direction in which the control plate 13 approaches the core 10. In the illustrated example, since the reactor used in the gravitational field is assumed, the urging of the rotating link mechanism 11 is achieved by the control plate 13 and gravity by its own load. In the case of a nuclear reactor used in a zero-gravity field or a low-gravity field, a spring mechanism (not shown) that always urges the link 12 toward the reactor core is incorporated in a pivot portion of each arm 12 of the rotary link mechanism 11.

Each control plate 13 is connected to an output shaft of a drive mechanism 15 via an electromagnetic lock device 16 at a slide connection portion at an upper end portion. The control plate 13 is driven by a driving mechanism 15 that drives the control plate 13 so as to be pulled up against the bias.
This is performed by adjusting the position from 0 to a predetermined distance t. In this case, at the position where the control plate 13 is displaced, the thickness of the reflector 14 around the core is adjusted simultaneously with the position of the control plate 13, which also contributes to the output control. In FIG. 1, reference numeral 13a denotes a control plate at a position close to the core 10, and reference numeral 13b denotes a control plate at a position away from the core.

The electromagnetic lock device 16 constitutes a release mechanism. The electromagnetic lock device 16 is in an excited state in a normal state and maintains the connection between the control plate 13 and the output shaft of the drive mechanism 15. At the time of occurrence, the control plate 13 is de-energized, thereby disconnecting the control plate 13 from the output shaft of the drive mechanism 15 and freeing the control plate 13. Thereby, the control plate 13 is entrusted to the approach movement in the core direction by the bias of the rotation link mechanism 11. The control plate 13 disconnected from the output shaft of the drive mechanism 15 when the electromagnetic lock device 16 is de-energized automatically approaches the position where it comes into contact with the core frame 17 by the biasing (own weight) of the rotary link mechanism 11. And
As a result, the power of the core is reduced to a predetermined furnace shutdown level.

In the present embodiment, when the distance t between the control plate 13 and the core frame 17 is adjusted, the reflector 14 between the control plate 13 and the furnace frame 17 can be adjusted in addition to the power adjustment effect of the control plate 13 itself. Is also adjusted at the same time, and when the control plate 13 approaches the core frame 17, the thickness of the reflector 14 between them decreases, and the effect of suppressing the furnace power by these two actions is reduced. growing. It is preferable to provide an opening in the reflection plate 13 in order to reduce the fluid resistance generated when the control plate 13 moves in the liquid reflector 14.

[0019]

As described above, in the reactor power control mechanism of the present invention, the rotary cylindrical control drum is supported by the rotary link mechanism instead of being arranged in the solid reflector area. By placing the control plate in the liquid reflector area,
Since the core upper structure for inserting the control drum is not required, the structure around the core can be made more compact,
The output distortion is less than that of the rotary control drum system, and when the power is lost or a trouble occurs, the position control mechanism of the control plate can be given passive safety by the fail-safe function, and it automatically goes to the furnace stop side. This has the effect that the output can be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view (upper view) and a schematic transverse sectional view (lower view) showing a configuration of a core portion of a small special nuclear reactor having an output control mechanism according to one embodiment of the present invention.

FIG. 2 is a schematic cross section showing a core configuration of a conventional small special nuclear reactor.

[Explanation of symbols]

 10: Reactor core 11: Rotating link mechanism 12: Link mechanism arm 13: Control plate 14: Liquid reflector 15: Drive mechanism: 16: Electromagnetic lock device (release mechanism) 17: Core frame 18: Container

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI G21C 9/02 G21C 9/02 Z (56) References JP-A-4-320993 (JP, A) JP-A-60-111988 ( JP, A) Jikai Sho 60-80393 (JP, U) Hideshi Yasuda et al. “Special issue: Forecasting“ nuclear energy ”in the 21st century. 38, No. 1, pp. 53-59 (1992) Takakazu Takizuka et al. "Recent Space Reactor Power Generation Systems" Journal of the Atomic Energy Society of Japan, 36, 2, 116-123 (1991) Shunsuke Kondo "Current Status of Space Reactor Development" Journal of the Atomic Energy Society of Japan, Vol. 28, No. 7, pp. 587-593 (1986) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 7/08 GDF G21C 1/00 G21C 1/02 G21C 7/28 G21C 9/02 JICST file (JO S)

Claims (2)

(57) [Claims] 1. A reactor power control mechanism for controlling the reactivity of a core by displacing a control plate having a neutron absorption capability with respect to the core in a liquid reflector region surrounding the outer periphery of the core. A rotating link mechanism that supports the control plate so as to be able to approach and separate from the core and is constantly urged in a direction to bring the control plate closer to the reactor core; And a release mechanism for selectively releasing the control plate from the driving force of the driving mechanism and entrusting the approach movement in the core direction by the urging of the rotary link mechanism. Reactor power control mechanism characterized in that: 2. The release mechanism includes an electromagnetic lock device, which maintains the connection between the control plate and the drive mechanism in an excited state and disengages the connection between the control plate and the drive mechanism in a non-excited state. 2. The reactor power according to claim 1, wherein the reactivity of the core is reduced to a predetermined reactor shutdown level when the controlled plate approaches the core by the bias of the rotary link mechanism. Control mechanism.