JPH03282397A - Output adjusting device for nuclear reactor - Google Patents

Abstract

PURPOSE:To improve movement or transition control over a reflection body, and to stop the operation speedily in emergency and to improve the safety by composing the reflection body of a container wherein liquid reflecting neutrons is injected. CONSTITUTION:In the state of the operation state where the liquid level of the liquid 4 in the container 3 is at the lower end of fuel 2, the liquid 4 is supplied 14 to the hollow part 3a of the container 3 according to the combustion of the fuel 2 to control the maximum position in the reflection (output) area with the height of the liquid level. A driving motor 9 is driven to finely rotate a ball screw 7 engaging a ball screw nut 6 through a speed reducer 8, and the container (reflection body 5) is moved up and down finely to make a short- time fine adjustment for obtaining the best output. Then, if abnormality occurs during operation, a discharge valve 15 is opened automatically to discharge the liquid 3 speedily and the operation of the nuclear reactor can be stopped urgently, so high safety is secured.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is a method for controlling output by moving or displacing a reflector disposed around a reactor vessel in which fuel is stored. This invention relates to a power adjustment device for a nuclear reactor.

(Prior art) In small nuclear reactors such as those for research or military use, a reflector made of beryllium or the like that reflects neutrons is moved (or displaced) placed outside the reactor vessel that stores fuel to output power. is being controlled. There are two types of reflectors: one is a large number of thin cylindrical reflectors arranged around the furnace vessel, and the other is annular. In the former, the rotation angle of each cylindrical reflector is changed, and in the latter, the shape of the reflector is arranged around the furnace vessel. Controlled by changing the axial position. Due to the nature of this type of reactor being for research and military use, it is assumed that only a limited number of personnel will operate the reactor, so the drive mechanism for the reflector that controls the output has a relatively simple structure. For example, hydraulic drive or electric motor drive is used.

However, when this type of nuclear reactor is used for commercial purposes, much higher safety is required than for research or military use. In other words, in this type of nuclear reactor, the fuel is designed to have a lifespan of several years to a thousand years, and is burnt gently by controlling the movement (or displacement) of the reflector.If for some reason the reflector exceeds the allowable value, If the reflector moves (or is displaced) significantly, it may cause a nuclear reaction that exceeds the heat removal capacity of the reactor core, so any accident or failure, or malfunction or malfunction of the reflector may cause the reflector to move (or displace) beyond the allowable value. (displacement).

FIG. 3 is a schematic diagram showing a conventional nuclear reactor power adjustment device of the type that controls power by moving a reflector.

As shown in this figure, an annular reflector 102 made of beryllium alloy or the like that reflects neutrons and controls the output is arranged on the outside of a reactor vessel 100 containing fuel 101. On the outer peripheral surface of 102, there is a ball screw 1.
03 to move the reflector 102 in the vertical direction; and a linear bearing 1 that supports the reflector 102 in a movable manner by inserting a plurality of guide shafts 105 therethrough.
06 is installed. Reflector 102, ball screw 1
03, the guide shaft 105 is disposed within the reactor containment vessel 107.

Both ends of the ball screw 103 are rotatably supported by bearings 109a and 109b provided in the upper and lower parts of the reactor containment vessel 107, and a coupling 110 is installed at the top of the ball screw 103. The drive motor 111 and a speed reducer 112 that reduces the rotation speed of the drive motor 111 are connected through the drive motor 111 . In addition, the guide shaft 10
Both ends of the reactor containment vessel 107 are supported by fixing members 113a and 113b provided at the upper and lower parts of the reactor containment vessel 107, respectively.

A conventional nuclear reactor power adjustment device is configured as described above, and transmits the rotational driving force of the drive motor 111 to the ball screw 103 via the reducer 112 and the coupling 110 to rotate the ball screw 103. When the ball screw 103 rotates and the engaged pole screw nut 104 moves up and down, the reflector 102 is guided by the guide shaft 105 and moves up and down. By moving the reflector 102 in accordance with the combustion of the fuel 101 in this manner, it is possible to control the reflection of neutrons emitted by the nuclear fission reaction of the fuel 101, thereby controlling the output.

At this time, since the fuel 101 is burned from the bottom to the top, the reflector 102 is also controlled to move accordingly.

Further, in order to obtain the optimum output during operation, the reflector 102 is moved slightly up and down in a short period of time by the rotational drive of the drive motor 111 as described above.

In an emergency, the drive motor 111 is rotated in reverse at high speed to move the reflector 102 to the lower part of the reactor vessel 100 and stop the operation of the reactor.

(Problem to be Solved by the Invention) As described above, in the conventional nuclear reactor power adjustment device, the reflector 102 moves slowly in one direction (from bottom to top) as the fuel 101 burns, and the optimal power is obtained. The minute vertical movement in a short period of time for this purpose was performed by a movement mechanism based on the engagement of a ball screw 103 and a pole screw nut 104.

However, the two movements of the reflector 102 described above are speed,
Since the movement range is greatly different, the drive motor 11
If there is a mistake in the rotation control of the drive motor 111, the output may suddenly increase, and if the direction of rotation of the drive motor 111 is incorrect in an emergency, the output may suddenly increase as the reflector 102 moves upward. There was a risk of the water rising, which posed a safety problem.

Further, in the conventional moving mechanism based on the engagement of the ball screw 103 and the pole screw nut 104, it takes time to move the reflector 102 downward in an emergency, and the operation cannot be stopped quickly.

The present invention was made for the purpose of solving the above-mentioned problems, and it is an object of the present invention to provide a power adjustment device for a nuclear reactor that can effectively control the movement or displacement of a reflector and can quickly stop operation in an emergency. That is.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method in which a reflector that reflects neutrons toward the reactor vessel is arranged around a reactor vessel in which fuel is stored inside. In a nuclear reactor in which the output is controlled by moving or displacing the reflector, the reflector is constituted by a container in which a liquid that reflects neutrons is injected, and a supply means for supplying the liquid into the container. , a discharge means for discharging the liquid from inside the container.

The present invention also provides a nuclear reactor in which a reflector for reflecting neutrons toward the reactor vessel is disposed around a reactor vessel housing fuel therein, and the output is controlled by moving or displacing the reflector. a reflector constituted by a container in which a liquid is injected and a reflecting member that reflects neutrons is floated on the surface of the liquid; a supply means for supplying the liquid into the container; and a supply means for discharging the liquid from the inside of the container. It is characterized in that it is equipped with a discharge means.

(Function) According to the present invention, the maximum position of the reflection area (output area) can be regulated by the liquid supplied into the container or the reflection member on the liquid.

Further, by discharging the liquid in the container all at once using the discharging means, it is possible to make an emergency shutdown of the nuclear reactor.

(Example) Hereinafter, the present invention will be explained in detail based on the illustrated example.

FIG. 1 is a schematic diagram showing a nuclear reactor power adjustment device according to a first embodiment of the present invention. As shown in this figure, the outside of a reactor vessel 1 containing fuel 2 has an annular shape that does not reflect neutrons, forming a hollow part 3a into which a liquid (for example, water) 4 that reflects neutrons is injected. A reflector 5 constituted by a container 3 is arranged.

In the upper part 3b of the container 3, a pole screw nut 6 that engages with the ball screw/7 to move the container 3 in the vertical direction and a plurality of guide shafts 12 (one in the figure) are inserted to support the container 3 in a movable manner. A linear bearing 11 is attached. The ball screw 7 and the guide shaft 12 are each fixed member 10a.
, 10b is attached to the upper part of the reactor containment vessel 16 in which the reactor vessel 1 and the reflector 5 are arranged. A speed reducer 8 is connected thereto.

Further, in the upper part of the container 3, there is a liquid 4 in the hollow part 3a inside the container 3.
A supply pipe 14 for supplying liquid is disposed, and a discharge pipe 13 is disposed at the lower part of the container 3 and equipped with a discharge valve 15 that can quickly discharge the liquid 4 injected into the hollow part 3a of the container 3. . The liquid 4 supplied to the hollow part 3a in the container 3 through the supply pipe 14 is injected little by little with precision as the fuel 2 burns, and the maximum position of the reflection area (output area) is regulated by the height of the liquid level. do. Further, a discharge valve 15 provided in the discharge pipe 13 is configured to automatically open in an emergency to discharge the liquid 4.

Although not shown in the figure, there is an inlet pipe that allows liquid to be injected at any flow rate into the upper part of the container 3 so that after all the liquid 4 in the container 3 has been drained in an emergency, the operation can be resumed immediately upon recovery. is installed.

Next, the operation of the nuclear reactor power adjustment device according to the embodiment described above will be explained.

At the start of operation of a nuclear reactor, a liquid 4 is injected into a container 3.
The liquid level is located at the lower end of the fuel 2.

From this state, the supply pipe 1 is
4 into the hollow part 3a in the container 3, and the maximum position of the reflection area (output area) is regulated by the height of the liquid level.

In addition, fine adjustment in a short time to obtain the optimum output can be achieved by rotationally driving the drive motor 9 to minutely rotate the ball screw 7 that engages with the pole screw nut 6 via the reducer 8. ) by moving the guide shaft 12 up and down slightly.

If an abnormality occurs in the reactor or related systems during operation, the discharge valve 15 will automatically open and the liquid 3 in the container 3 will be immediately discharged, making it possible to emergency stop the operation of the reactor. , it is possible to make an emergency stop to the operation of the nuclear reactor, ensuring a high level of safety.

In addition, after all the liquid 4 in the container 3 has been discharged in an emergency, when restarting the operation, the liquid 4 is poured into the container 3 from an inlet pipe (not shown).
can be restarted immediately by injecting it at any flow rate.

FIG. 2 is a schematic diagram showing a nuclear reactor power adjustment device according to a second embodiment of the present invention.

In this embodiment, a reflecting member 20 made of beryllium alloy or the like that reflects neutrons is floated on the surface of the liquid 4 injected into the hollow part 3a of the container 3. in this case,
The liquid 4 does not need to reflect neutrons and may absorb them. The other configurations and operations are similar to those of the embodiment described above.

In this embodiment, as the liquid 4 injected into the container 3 increases due to the combustion of the fuel 2, the reflecting member 20 on the liquid surface also moves upward accordingly. The maximum position of the reflection area (output area) can be regulated in terms of height.

It should be noted that various methods can be considered for fine adjustment to obtain the optimum output, other than slightly moving the entire container 3 up and down using the drive motor 9 described above.

For example, the height of the liquid level may be slightly moved up and down by adjusting the injection amount or discharge amount of the liquid 4 instead of moving the entire container 3 up and down. At this time, the liquid 4 is injected and discharged through the supply pipe 14 and the discharge pipe 13 in consideration of the safety of the device.
It is desirable to have a separate system.

[Effects of the Invention] As described above in detail based on the embodiments, according to the present invention, output control is possible when an accident or failure occurs in the reactor or related systems during operation, or due to malfunction or erroneous operation. Even if an abnormality occurs in the reactor, the reactor can be brought to an emergency stop by quickly discharging the liquid in the container, so it is possible to provide a highly safe nuclear reactor power adjustment device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a power adjusting device for a nuclear reactor according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram showing a power regulating device for a nuclear reactor according to a second embodiment of the present invention. FIG. 3 is a schematic diagram showing a conventional nuclear reactor power adjustment device. 1... Furnace vessel 2... Fuel 3... Container 4... Liquid 5... Reflector 6... Pole screw nut 7... Ball screw 9... Drive motor 12... Guide Axis 1
3... Discharge pipe 14... Supply pipe 15... Discharge valve 16... Reactor containment vessel

Claims (2)

[Claims] (1) In a nuclear reactor, a reflector that reflects neutrons toward the reactor vessel is arranged around a reactor vessel that stores fuel inside, and the output is controlled by moving or displacing the reflector. A nuclear reactor comprising a reflector constituted by a container filled with a reflective liquid, a supply means for supplying the liquid into the container, and a discharge means for discharging the liquid from inside the container. output adjustment device. (2) In a nuclear reactor, a reflector that reflects neutrons toward the reactor vessel is arranged around a reactor vessel that stores fuel inside, and the output is controlled by moving or displacing the reflector. A reflector constituted by a container in which a reflecting member for reflecting neutrons is floated on the surface of the liquid that is injected, a supply means for supplying the liquid into the container, and a discharge means for discharging the liquid from the inside of the container. A nuclear reactor output adjustment device characterized by comprising: