JPS6125115B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear reactor in which the degree of freedom of horizontal movement for fuel exchange is three or more degrees of freedom, and particularly relates to a method of operating a fuel exchange machine in which the rotation angle of a rotating plug or arm is limited. be.

Nuclear reactors are equipped with fuel exchange systems for transferring fuel assemblies, etc. within the reactor, but there are various types, including the under-the-plug method, in which the fuel gripping mechanism is moved under the reactor vessel lid without removing the reactor vessel lid. A fuel exchange method has been proposed. Depending on the type of rotating plug installed on the reactor vessel lid and the degree of freedom of movement of the fuel gripping mechanism that moves under the rotating plug, there are three types: single-rotation plug fixed arm type, single-rotation plug variable arm type, and double-rotation plug vertically movable. There are various methods such as double rotating plug fixed arm method, triple rotating plug method, etc. Among these, the triple rotating plug method and the double rotating plug fixed arm method have three degrees of freedom for horizontal movement during fuel exchange, so the diameter of the reactor vessel can be reduced, and the diameter of the rotating plug can also be reduced. Therefore, it is considered a very promising method from the viewpoint of economical reasons and structural capabilities of the equipment. (The only difference between the two types is that the small rotating plug and the fixed arm are replaced with each other, and there is no essential difference. Therefore, only the triple rotating plug type will be explained below as an example. ) In the conventional triple rotating plug system, no special restrictions are placed on the rotation angle of the large rotating plug and medium rotating plug (in the double rotating plug fixed arm system, the large rotating plug and the small rotating plug) when exchanging fuel. Therefore, for example, if we take a nuclear reactor vessel with a fuel inlet/outlet chute as an example, the upper core mechanism moves within the area by the rotation of the large-rotation plug and the medium-rotation plug,
Since it is close to the fuel inlet/outlet chute, it is necessary to install the fuel inlet/outlet chute far from the center of the reactor vessel to avoid interference, which inevitably increases the diameter of the reactor vessel.

The object of the present invention has been made in view of the above points, and is to make it possible to significantly downsize the reactor vessel, the plug, the containment vessel housing it, and the building without changing the performance of the reactor. The objective is to learn how to operate a fuel exchanger.

The present invention will be described in detail below with reference to the drawings of one embodiment. As shown in FIGS. 1 and 7, the nuclear reactor includes a reactor vessel 15 and a vessel 1 containing a coolant.
The reactor is composed of a shield plug 16 that serves as a lid for the reactor 5, and a reactor core 17 in which a large number of fuels and the like are placed. The low-speed plug 16 includes a fixed plug 18 fixed to the container 14, a large-rotation plug 19 that rotates with respect to the fixed plug 18, and a medium-rotation plug 20 that is eccentrically attached to the large-rotation plug 19.
and a small-rotation plug 21 eccentrically attached to the medium-rotation plug 20. A fuel exchanger 22 is installed in this small rotation plug 21 at a position eccentric from the center of the small rotation plug 21, and during fuel exchange, a large rotation plug 19, a medium rotation plug 20,
By combining the rotation of the small rotation plug 21,
It is possible to grab fuel, etc. placed at any position in the reactor core 17 and fuel, etc. stored in the in-core temporary storage rack 23 provided in the periphery of the reactor core 17. A fuel inlet/outlet chute 24 is installed in the fixed plug 18, and the spent fuel etc. stored in the in-core temporary storage rack 23 provided in the periphery of the reactor core 17 can be taken out of the reactor or fresh fuel can be taken out from outside the reactor. This serves as a guide path for putting fuel, etc. into the rack 23. A core upper mechanism 25 that accommodates and supports a control rod drive mechanism and the like is installed eccentrically in the medium rotation plug 20, and is located at the center of the large rotation plug during normal operation. When replacing fuel, use the large rotation plug 19 and medium rotation plug 2.
0 rotation causes the core upper mechanism 25 to move within the region ○a in FIG. The fuel inlet/outlet chute 24 is connected to the reactor vessel 1 in order to avoid interference with the upper core mechanism 25.
5 is installed on the opposite side of the core upper mechanism 25 movement range with respect to the center.

Next, an example of the rotary plug operation for limiting the movement range of the upper core mechanism 25 within the reactor vessel 15 to the area ○A in FIG. 2 will be described. In Figure 3 O ₁
is centered on the large rotation plug, O ₂ is centered on the medium rotation plug,
O ₃ indicates the center of the small rotation plug, ε ₃ indicates the eccentricity between the center of the small rotation plug and the center of the fuel exchanger 22, and the area within the circle with radius ε ₁ +ε ₂ +ε ₃ indicates the range that the center of the fuel exchanger 22 should reach. In order for the center of the fuel exchanger 22 to reach the area A in FIG.
It is a circle with radius ε ₁ centered at O ₂ . In order for the center of the fuel exchanger 22 to reach the B area in FIG. 3, the center of the core upper mechanism 25 should be located in the _b1 area for the _B1 area as shown in FIG. (The same applies to the _B2 area if the top and bottom are reversed.) In other words, it is as shown in FIG. That is,
Position _F1 where the center of the fuel exchanger 22 is closest to _O2
When the rotation angle of the small-rotation plug is fixed and the medium-rotation plug 20 is rotated, the center of the fuel exchanger 22 becomes an arc.
Draw the trajectory F ₁ −F ₂ . Next, when the large rotation plug 19 is rotated by θ, the center of the fuel exchanger 22 is aligned with an arc F ₂ −
Since we draw F ₃ and reach the O ₁ −X ₁ axis, we can reach any point on this arc. At this time, large rotation plug 1
9 rotation, the center of the core upper mechanism 25 is arc U ₂
−U ₃ is drawn, but <F ₂ O ₁ U ₂ is always 90°, so
θ=90°−<X ₁ O ₁ U ₂ and <X ₁ O ₁ U ₃ =90°, so U ₃ is on the O ₁ −X ₄ axis. Therefore, the center of the upper core mechanism 25 is always in the fourth quadrant.

Next, in order for the fuel exchanger 22 to reach the C area in FIG. 3, the center of the core upper mechanism 25 needs to be in the _{C0 area relative to the C4 area} as shown in FIG. (The same applies to the _C2 area if it is turned upside down.) That is, as shown in FIG. 7. That is, when the rotation angle of the small rotation plug 21 is fixed at the position F ₄ where the center of the fuel exchanger 22 is farthest from O ₂ and the medium rotation plug 20 is rotated, the center of the fuel exchanger 22 will be located within the arc F ₄ −F ₅ . Draw a trajectory. Next, when the large rotating plug 19 is rotated, the center of the fuel exchanger 22 draws an arc _F5 - _F6 and reaches the _O1 - _X3 axis, so that it can reach any point on this arc. At this time, due to the rotation of the large rotating plug 19, the center of the core upper mechanism 25 draws an arc U ₂ - U ₃ , or <U ₂ O ₁ F ₇ is always 90 degrees, so <F ₇ O ₁ F ₅ =< U ₃ O ₁ X ₂ = θ
₁ −90゜−＜F ₅ O ₁ U ₃ . On the other hand, <F ₇ O ₁ F ₅ is
Since it is always positive from the geometrical relationship, <U ₃ O ₁ X ₂ is also positive, and the center of the core upper mechanism 25 is always in the 1st and 3rd quadrants.

According to the operating procedure of the rotating plug explained above,
It is possible to make the refueling machine 22 reach each region of A, B, and C in FIG. 3 while the movement range of the center of the core upper mechanism 25 is limited to the region ○A in FIG. 2. At this time, the center of the core upper mechanism is within a semicircle far from the fuel inlet/outlet chute, so there is no interference between the core upper mechanism and the fuel inlet/outlet chute.

In addition, in the explanation of the operation of the present invention, the method of operating the rotary plugs individually was explained, but at the same time,
A large rotation plug, a medium rotation plug, and a small rotation plug may be operated. For example, in FIG. 7, when the large rotary plug is rotated with the center of the upper core mechanism 25 aligned with O ₁ , the center of the fuel exchanger 22 draws an arc F ₄ -F ₈ . In other words, it is possible to move around the outermost circumference of the _C1 area.

As described above, the nuclear reactor of the present invention limits the range of movement of the upper core mechanism within the reactor vessel by limiting the rotation angle of the rotating plug or the arm, thereby limiting the range of movement of the upper core mechanism within the reactor vessel. Since interference with the reactor can be avoided, interfering in-core equipment can be installed near the center of the reactor vessel, and the diameter of the reactor vessel can be reduced. Therefore, the size of the plug, containment vessel, and building can be reduced, making it easier to manufacture and manufacture nuclear reactors.
Transportation and installation become easier, and operability is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a nuclear reactor for explaining the present invention, FIG. 2 is a cross-sectional view of FIG. 1, and FIGS.
The figure is an explanatory diagram showing the movable area of the fuel exchanger. 19... Large rotation plug, 20... Medium rotation plug, 21... Small rotation plug, 22... Fuel exchange machine, 25... Core upper mechanism.

Claims (1)

[Claims] 1. A reactor vessel, a reactor core housed in the reactor vessel, a shield plug serving as an upper cover of the reactor vessel, a core upper mechanism mounted on the shield plug, and The Shiyahei Plug consists of a fixed plug, and a large-rotation plug, a medium-rotation plug, and a small-rotation plug that are rotatably attached to the fixed plug. The upper core mechanism is installed in the upper part of the reactor core, the fuel exchanger is installed in a position eccentric from the center of the small rotating plug, and the fuel inlet/output chute is installed in the side of the core.
When reaching area A in the figure, the large rotation plug is fixed in a position where the center of the medium rotation plug is opposite to the center of the large rotation plug, and then the medium rotation plug and the small rotation plug are rotated. To reach area B in Figure 3, fix the small rotation plug in the position where the center of the fuel exchanger is closest to the center of the medium rotation plug, and then fix the medium rotation plug.
The large rotation plug is rotated by a predetermined angle within a range not exceeding 180°, and then the large rotation plug is rotated in the opposite direction to the rotation direction of the medium rotation plug by an angle not exceeding half of the rotation angle of the medium rotation plug. To reach area C, fix the small rotation plug at the position where the center of the fuel exchanger is farthest from the center of the medium rotation plug, then rotate the medium rotation plug by an angle not exceeding 180 degrees, and then fix the large rotation plug. A method of operating a fuel exchanger in which the fuel exchanger rotates in the same direction as the rotational direction of the medium-rotation plug within a range that does not exceed angle A. however B is the rotation angle ε of the medium rotation plug. ₁ is the eccentricity ε between the center of the large rotation plug and the center of the medium rotation plug. ₂ is the eccentricity ε between the center of the medium rotation plug and the center of the small rotation plug. ₃ is the center of the small rotation plug and the center of the fuel exchanger. is the amount of eccentricity.