JPS6225963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention emits ultrasonic waves from a transducer in an opaque liquid, and uses reflected waves from obstacles or the inner wall surface of a reactor vessel facing the obstacles to generate ultrasonic waves.
The present invention relates to an ultrasonic fluoroscopy device that detects obstacles.

An example of application to a sodium-cooled fast reactor will be described below. In sodium-cooled fast reactors, before fuel exchange, the control rods installed at the top of the reactor pressure inside the reactor core are separated, and a plug integrated with the core upper mechanism is rotated to perform fuel exchange. By the way, if the control rods are not disconnected reliably during fuel exchange, or if the core components are floating and interfering with the upper reactor mechanism, rotating the plug can cause fatal damage to the core. There is a risk of giving. Therefore, a transducer and a reflector are installed at a position where the gap between the core components and the upper reactor mechanism can be seen, and monitoring is performed using ultrasonic waves emitted from the transducer. To make this monitoring more complete, an elevation movement that directs the transducer in a direction parallel to the lower surface of the upper core mechanism;
It is necessary to perform a horizontal movement to cover the entire top of the core component and a vertical movement to cover the entire gap between the top of the core component and the lower surface of the core upper mechanism. This device also requires high reliability, ease of handling, and ease of transducer replacement.

2. Description of the Related Art Conventionally, there has been an ultrasonic fluoroscopy device that satisfies the above-mentioned requirements and includes a transducer drive device and a reflector, and an example thereof will be explained with reference to the drawings.

FIG. 1 is a sectional view of a conventional nuclear reactor. A drive unit 1 for driving a transducer is provided on the shield plug 16, and is used to drive the core components 12 and upper reactor mechanism 15 in the reactor vessel 14 during normal operation.
A transducer 3 is provided so as to be located in the gap, and the transducer 3 is connected to the drive unit 1 by a holding tube 2 provided through a stiff plug 16. . These drive section 1, holding tube 2, and transducer 3 constitute a transducer drive device. A reflector 11 is fixed within the inner cylinder 13 at a position facing the transducer 3.

According to the above method, the distance between the transducer 3 and the reflector 11 is large, and the amount of signal obtained as a reflected wave is small. In addition, it is necessary to install a special reflector inside the reactor vessel, and this reflector has a special surface shape to prevent loss of function due to thermal deformation that may occur during the reactor life. is scarce. Further, it is expected that it will be even more difficult to maintain a reflector that has lost its function.
One possible solution to the above problem is to install the transducer drive mechanism at the center of the plane of the reactor vessel and use the inner wall of the vessel as a reflective surface, but this is not possible for every case. This is because the core upper mechanism is installed in the center of the reactor vessel, and control rod drive mechanisms are installed in groups inside the core upper mechanism. For example, consider a fast breeder reactor with control rods installed in the center of the reactor vessel. It is possible to remove the control rod drive mechanism when refueling the reactor. However, the insertion hole of the control rod drive mechanism is too small to install the conventional transducer drive device.
Another way to solve this problem is to use a vertical immersion tube, but the attenuation of the signal amount affects reliability when the signal reaches the transducer in the upper part of the core through the immersion tube.

The present invention has been made in view of the above points,
The details of the present invention will be explained below with reference to the illustrated embodiments.

FIG. 2 shows, as an example, the method of the present invention in contrast to the conventional method shown in FIG. , core component 12
The top part 12a of the figure is shown in a cylindrical shape.

FIG. 3 is a cross-sectional view showing the internal mechanism of the transducer drive device shown in FIG. 2, and the same parts will be described with the same reference numerals.

The drive unit 1 provided in the upper core mechanism 15 of the rotating plug 18 penetrates the rotating plug 18,
A guide tube 7 is installed vertically below the coolant liquid level 17, and a transducer 3 is installed at the end of the guide tube 7.
It is connected to a holding tube 2 having a. A sliding portion 9 is provided in the gap between the holding tube 2 and the guide tube 7 for guiding during driving. Further, the transducer 3 is fixedly attached to the inner surface of the holding tube 2 by a support 20, and the transducer 3 and the holding tube 2
is immersed in coolant. At the top of the drive unit 1, there is an eye bolt 31 for handling and for vertical movement of the drive unit.
is provided, and a hanging tool 30 with a built-in ball bearing is attached to the lower part of the hanging tool 3.
0 suspends the drive unit 1. eye bolt 31
is the drive section 35 installed above the core upper mechanism 15.
Upper drive motor 38, wire rope winding drum 3
7. It is connected to a guide pulley 36 via a wire rope 32, and constitutes a transducer vertical movement mechanism. Further, the drive section 1 has a gear 29 on its upper part, and a drive motor 3 installed in the drive section 35.
4 via a gear 33 to constitute a transducer horizontal rotation mechanism. The drive unit 1 is supported by a sealing mechanism 25 on the upper surface of the rotating plug 18, and seals the cover gas 19 inside the furnace. Next, the internal mechanisms of the holding tube 2 and the drive section 1 will be explained. The transducer 3 is connected to an operating rod 22, and the operating rod 22 is connected to a ball screw 2 in the drive unit 1.
4. Drive motor 28 via gears 26a and 26b
, and constitutes a transducer depression/elevation angle movement mechanism. In addition, a bellows 6 is installed in the through hole of the operating rod 22 to separate the drive unit 1 from the cover gas in the furnace.
is provided. The gear 26b in the drive unit 1 is connected to the position detector 27 via the other gear 26c.

Next, we will discuss its effect. Before refueling, the transducer drive device is inserted and installed along the guide tube 7 that has been installed in advance. First, in order to make the transducer 3 parallel to the lower surface of the reactor upper mechanism 15, an elevation angle movement C is performed from the drive unit 1 via the ball screw 24 to fix it in an appropriate position, and then the entire top of the core component 12 is scanned. horizontal movement A, upper reactor mechanism 15 and core components 1
Up and down movement B to cover all the gaps with 2
The holding tube 2 and the entire drive unit 1 are moved up and down, and the waves reflected from the inner wall surface of the reactor vessel 14, the floating core components, and the control rods that have not been detached confirm the detachment of the control rods and confirm the detachment of the core components 12. Detects the presence or absence of floating. At this time, only the elevation angle movement C is operated by using the simple link mechanisms 39 and 40 in the sodium, and converting the operating rod 22 into vertical movement by rotating the ball screw 24 from the drive motor 28 on the rotating plug 18. let The transducer drive mechanism within the holding tube 2 is therefore immersed in sodium. However, since the mechanism is simple, it is extremely reliable. Furthermore, due to the simplicity of the transducer drive mechanism within the holding tube 2, the thickness of the holding tube 2 can be reduced, and the transducer is also integrated into the core component 12.
and the vertical movement B due to the narrow gap of the upper core mechanism 15.
By performing the elevation angle movement C, it is possible to install the reactor vessel in the center of the horizontal plane in the upper core mechanism. Therefore, a reflector is unnecessary, the distance between the transducer and the reflecting surface is shortened, and a sodium fluoroscopy device with high detection sensitivity can be obtained. The horizontal rotational movement A of the transducer is caused by the drive motor 34 through the gears 33 and 29 to the drive section 1 and the holding tube 2.
Rotate the whole body 360°A. At this time, the horizontal rotational movement A is performed independently of the vertical movement mechanism by a ball bearing provided in the hanging tool 30. The vertical movement B can be performed by winding up and lowering the wire rope 32 on the drum 37 using a drive motor. At this time, the drive motor 34 and the gear 33 move up and down B together with the drive section 1, and can slide relative to the drive section 35 by key coupling. Furthermore, the ultrasonic transducer drive mechanism can raise the operating rod 22 beyond the upward movement of the elevation angle to direct the transducer 3 downward. At this time, the operating rod 22 is bent at the link portion 41, so that the bending of the operating rod 22 itself is absorbed. By directing the transducer 3 downward, when the holding tube 2 and the driving section 1 are inserted into the reactor as a single piece as described above, the transducer 3 is activated to remove the components from the top of the core component 12. The transducer 3 itself captures the ultrasonic reflected waves and transmits them to the core components 12.
It can act as a guide to avoid collisions with others. In addition, the horizontal rotation movement A, vertical movement B, and elevation angle movement C of the transducer described above can be used to confirm the separation of control rods and the core components 1 during fuel exchange.
When the detection of the presence or absence of floating in step 2 is completed and it is OK to rotate the rotary plug 18, the transducer 3 is directed downward again, and at the same time as the fuel is replaced, ultrasonic signals from the top of the core components are obtained. It is also possible to map the top of the core. At this time, if the horizontal rotation movement A is performed, the mapping time can be shortened.
After using the fluoroscope, the drive unit 1 and the holding tube 2 are removed from the drive unit 35, pulled out as a unit, cleaned with sodium, and maintained. Because of the simple sodium contact mechanism, cleaning is excellent, and the transducer 3 It has a structure that allows for easy replacement, and has excellent maintainability.

As described above, by using the ultrasonic fluoroscope of the present invention, it is possible to confirm the separation of control rods and detect the presence or absence of levitation of core components during refueling of sodium-cooled fast reactors, and The safety of furnace operation is improved. In addition, since only the elevation angle drive mechanism of the transducer drive device is exposed in the sodium using a simple mechanism, the drive mechanism suspended in the reactor can be compact and small in diameter. It is installed at the center of the plane of the reactor vessel, providing good performance and extremely high accuracy and reliability. In addition, it is easy to clean sodium, etc., and maintainability is very good. Furthermore,
The power from the drive unit 1 is transmitted by a ball screw 24, and the entire device is lightweight, and the drive unit 1 and holding tube 2 have a structure that allows them to be handled as one unit, making it easy to handle and improving the operating rate of the reactor. do. Furthermore, the transducer 3 can be easily replaced. In addition, since the ultrasonic fluoroscope of the present invention uses the reactor vessel as it is as a reflector for ultrasonic waves, there is no need to install a special reflector, and the reactor vessel is sufficiently strong and does not easily undergo thermal deformation. Therefore, there is no need to worry about loss of functionality during the life of the reactor, making it even more reliable. Furthermore, since the transducer is installed in the center of the reactor vessel, the travel distance of the ultrasonic waves is also much shorter than in conventional systems. Therefore, a reliable signal can be obtained.In addition, since a cylindrical surface is also provided on the top of the core component, a signal can be obtained directly from the target object, and it has two detection functions, which improves safety. further improves. Furthermore, the ultrasonic transducer drive mechanism enables vertical viewing with the same transducer by pulling up the operating rod 22, as shown in the above-mentioned operation, making it an extremely convenient ultrasonic fluoroscopy device. I can say that.

The example of application to a sodium-cooled fast reactor has been described above, and the ultrasonic fluoroscope according to the present invention is useful for detecting obstacles in opaque liquid for the safety function of plants or equipment. It goes without saying that it can be applied to other countries with the same effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a nuclear reactor showing a state in which a conventional ultrasonic fluoroscopy device is installed, and FIG. 2 is a longitudinal cross-sectional view of a nuclear reactor showing a state in which an ultrasonic fluoroscopy device according to an embodiment of the present invention is installed. FIG. 3 is a longitudinal sectional view showing the drive section and holding tube section of FIG. 2. DESCRIPTION OF SYMBOLS 1... Drive part, 2... Holding tube, 3... Transducer, 14... Reactor vessel, 15... Core upper mechanism, 2
8, 34, 38... Drive motor.

Claims (1)

[Claims] 1. A drive part installed in the core upper mechanism provided at the center of the outside of the reactor vessel, and a transducer connected to the drive part and penetrating through the core upper mechanism, with a transducer at the lower end and a transducer inside. a holding tube housing and holding a drive mechanism; a driving means for driving the holding tube; a drive motor housed in the holding tube; an operating rod driven vertically by the driving motor; and a link mechanism that converts the ultrasonic oscillation surface of the transducer downward and sideways as the transducer moves up and down, the inner wall of the reactor vessel having a vertical cylindrical surface facing the transducer reflects ultrasonic waves. An ultrasonic fluoroscopy device characterized by being used as a surface.