JPS5937763B2 - sodium fluoroscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sodium fluoroscopy system, and particularly to a type that uses a fuel exchanger hold-down arm to observe the top of a fuel assembly. This is a sodium fluoroscopy device that has a mechanism for performing a feeding operation.

The interior of fast breeder reactors, especially those that use liquid metal as a coolant, cannot be directly observed with the naked eye.

For this reason, in fast breeder reactors, a sodium fluoroscopy device is used in which a transducer that transmits and receives ultrasonic waves is moved above the fuel assembly, and the top of each fuel assembly is observed to check for abnormalities. By the way, this sodium fluoroscopy device is installed using the fuel exchanger hold-down arm on the same rotatable plug as the fuel exchanger, so the fluoroscopy device also rotates the rotatable plug and hold-down arm. After viewing the entire top of the fuel assembly to be gripped, the viewing device must be removed and the refueling device installed.

The time required to use this sodium fluoroscope directly affects the operating rate of the reactor. Therefore, in order to reduce the time required for the fluoroscope to observe the top of the fuel assembly as much as possible, a method has been adopted in which a transducer holder to which a plurality of transducers are attached is moved back and forth while the transducer holder is rotated. ing. Conventionally, the back-and-forth feeding mechanism of the transducer holder has been constructed using a ball screw provided through the rotary housing, a bevel gear attached to the tip of the ball screw, and a ball screw provided in the arm and attached to the end of the ball screw. The bevel gears are engaged with each other at a contact point between the rotary housing and the arm, and the transducer holder is fed by rotation of a ball screw within the rotary housing. In this case, the rotating shaft would pass through the primary boundary, making sealing very difficult. Furthermore, when the arm was folded, it was designed to bend at a universal joint provided on the ball screw within the arm, but this part had to be bent at a large angle of approximately 900 degrees, resulting in poor operability. Additionally, the ball screw, universal joint, and bevel gear mechanisms occupy most of the space within the arm and rotating housing, making placement of the transducer tilting mechanism and the transducer signal cable extremely difficult. was. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a sodium fluoroscopy device having good sealing properties of the operating shaft and folding properties of the arm, and having a transducer feeding mechanism that occupies a small space.

Hereinafter, the present invention will be explained in detail using the drawings of one embodiment.

FIG. 1 is an overall schematic view of the present sodium fluoroscope, and FIG. 2 is an enlarged view of the folding mechanism, the forward/backward feeding mechanism, and the tilt adjustment mechanism. FIG. 3 is an enlarged view of the guide roller section for longitudinal movement, and FIG. 4 is an enlarged view of the chain section for longitudinal movement. In Fig. 1, the sodium fluoroscopy device penetrates the rotating plug 3 of the reactor vessel 2 containing the sodium coolant 1, has a drive unit 5 at the top, and a rotating ujing that reaches close to the reactor core 6 in the sodium at the bottom. A scanning guide 8 is mounted on the tip of the rotary housing 7 in parallel with the upper surface of the core 6 .

In FIG. 2, one end of the scanning arm 11 is rotatably pin-coupled to the lower part of the rotary housing 12, and the other end is also pin-coupled to the folding arm 13.

The other end of the folding arm 13 is pin-coupled to a folding operation shaft 14 within the rotary housing 12. The transducer holder guide 15 is mounted within the scanning arm 11 via a rotary bearing 16 so as to be swingable.
Rotating housing 1 of transducer retainer guide 15
A swinging operation rod 17 is attached to the end on the second side.
A guide roller 19 for forward and backward feeding movement is attached to the upper surface of the transducer holder 18 via a bearing 24, so that the transducer holder 18 can reciprocate back and forth within the transducer holder guide 15. This guide roller 19 is placed on a rail groove for forward and backward feeding of the transducer holder guide 15. On the other hand, a coil spring 20 is provided between the transducer holder 18 and the transducer holder guide 15 for applying a force to constantly press the transducer holder 18 toward the arm distal end. A chain 21 for moving the transducer holder 18 back and forth is attached to the end of the transducer holder 18 on the rotating housing 12 side. This chain 21 is a sprocket 22
It changes direction through the rotary housing 12 and is connected to the drive unit 1. Note that one end of the chain 21 is connected to a drive source via a connecting rod 30. Also, connecting rod 3
0 is provided with a bellows 31 to form a boundary with the inside of the reactor vessel 2. The transducer 25 is attached to the lower surface of the transducer holder 18, and its signal cable 23 is installed along the upper surface of the transducer holder and changes direction at the root of the scanning arm 11.
It passes through the rotary housing 12 and is drawn out of the furnace. Next, the operation of the sodium fluoroscopy apparatus described above will be explained. In order to scan the upper surface of the reactor core, the scanning arm 11 is rotated (this is done by a drive system installed on the side of the hole into which this sodium fluoroscope is inserted), and the transducer holder 18 is reciprocated in the longitudinal direction of the scanning arm 11. However, in this device, the transducer retainer 18
This is done by pushing and pulling the chain 21 connected to the . To move the transducer holder 18 toward the rotating housing 12, the chain 21 can be pulled up. Conversely, the transducer holder 18 is connected to the scanning arm 11.
When moving the chain 21 toward the tip side, the chain 21 may be lowered and loosened. Since the transducer holder 18 is pushed by the coil spring 20 and is constantly trying to move toward the tip side of the scanning arm 11, if the chain 21 is loosened, it will automatically move toward the tip side. At this time, the transducer holder 18 is moved by the guide rollers 19 attached to the upper surface of the transducer holder 18 rolling on the longitudinal feed rail grooves of the transducer holder guide 15. The transducer signal cable 23 absorbs this amount of movement by its own flexibility. When folding the scanning arm 11 by pulling up the folding operation shaft 14, the chain 21 is lowered and the transducer holder 18 is moved toward the distal end of the scanning arm 11. When folding, the length of the chain 21 is required to be longer as the chain 21 wraps around the sprocket 22, but this length can be covered by the stroke of the coil spring 20, so the chain 21 can be easily folded without pushing or pulling. When operating the swing operation rod 17 to tilt the transducer retainer guide 15, the chain 21
Since this can be accommodated with flexibility in the direction of rotation, the inclination can be easily adjusted without operating the chain 21. On the other hand, since the movement direction of the chain 21 within the rotary housing 12 is vertical movement, the sealing mechanism of the bellows 31 can perform complete sealing. Although the coil spring 20 is used in the above description, a tension coil spring may be used, and it is also possible to use a plate spring or a disc spring in layers.

The chain 21 may also be made of wire rope, tape, or the like. As described above, according to the present invention, since the operating shaft moves in the vertical direction, a reliable sealing structure such as a bellows seal can be used, and the activated primary cover gas can be reliably isolated.

Furthermore, since the operating mechanism is a chain or the like, the arm can be easily bent during the folding operation, improving folding reliability. If the arm can no longer be folded inside the reactor, the entire oblong plug must be removed, which not only becomes an extremely difficult task but also significantly reduces the operating rate of the reactor plant. From this point of view, the arm feeding mechanism based on the present chain system is a highly reliable and advantageous mechanism. Furthermore,
Compared to mechanisms using ball screws and bevel gears, chain systems require fewer components, are smaller in size, and are highly flexible, allowing for greater freedom in arrangement. Easy to provide installation space for user signal cables. Therefore, the device itself can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of a sodium fluoroscope according to an embodiment of the present invention, FIG. 2 is a sectional view showing the folding mechanism and feeding mechanism of FIG. 1, and FIG. It is an enlarged view of a guide roller part, (a) is a front view, (b)
) is a side view, and FIG. 4 is an enlarged view of the longitudinal motion chain section. 11...Scanning guide, 12...Rotating housing, 15...Transducer retainer guide, 17...Obcillating operation rod, 18... ...
Transducer retainer, 21...Chain,
25...Transducer, 30...
Connecting rod, 31... Bellows.

Claims (1)

[Claims] 1. A rotating housing rotatably suspended from the lid of the sodium storage container, a scanning arm provided horizontally at the bottom of the rotating housing and supported with its end foldable, and a longitudinal axis attached to the scanning arm. a holder guide rotatably mounted around the holder; an oscillating operating rod attached to the holder guide for rotating the holder guide around the longitudinal axis of the scanning arm; The transducer holder is movable reciprocally along the length of the guide and is attached to the distal end side of the holder guide, and the transducer holder is installed in a rotary housing so as to be able to move up and down, and the inside of the sodium storage container is attached to the upper part. A connecting rod equipped with a sealing mechanism that seals the outside, connects the lower end of this connecting rod to a transducer holder, and converts the vertical movement of the connecting rod into horizontal movement of the transducer holder. A sodium fluoroscopy device comprising a flexible transmission member and a plurality of ultrasonic transducers attached along the longitudinal direction of a transducer holder.