JPS6260001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluoroscopy device for inspecting abnormalities inside a fast breeder reactor, particularly in the vicinity of the upper part of the reactor core.

Generally, in a liquid metal cooled fast breeder reactor, it is not possible to directly inspect the inside of the reactor, so an inspection device that uses ultrasonic waves to see through the inside of the reactor is used. That is, in this type of device, for example, as shown in FIG. 1, an ultrasonic transducer b that transmits and receives ultrasonic waves in the horizontal direction is provided in the reactor vessel a, and a reactor core is placed opposite to the transducer b. An ultrasonic reflector f is placed on the opposite side of the extension of the gap e between c and the upper core mechanism d, and by receiving echo waves from this reflector f,
For example, it is possible to detect the lifting of fuel assemblies from the reactor core c, the presence of foreign objects in the upper part of the reactor core, or the presence or absence of detachment of control rods.
Further, as shown in FIG. 3, the transducer b is rotated so as to scan the ultrasonic waves in a predetermined angular range _θ1 in the horizontal direction, so as to cover a predetermined inspection area.

In this way, a fluoroscopic device that uses ultrasonic waves can perform its original function as a fluoroscopic device by accurately transmitting ultrasonic waves in the horizontal direction in a predetermined scanning range toward the reflector f. be. Therefore, it is very important to accurately set the reference position of transducer b. Conventionally, for example, in order to minimize the effects of thermal expansion acting on the fluoroscopy device, the fluoroscopy device is sufficiently preheated and then the transducer b is driven in elevation and horizontally. The reference point of the electrical instrumentation located at is set as the reference position. However, in this case, not only is there a disadvantage that preheating takes a long time, but it is also difficult to set the reference position accurately.For example, if the transducer is tilted upward or downward relative to the reference horizontal position, If ultrasound cannot be transmitted correctly in the horizontal direction,
In extreme cases, the ultrasonic waves may be reflected by the upper surface of the core c or the lower surface of the upper core mechanism d, and there is a possibility that an erroneous detection that there is an obstacle in the gap e may be made. Furthermore, as shown in Fig. 2, when the upper core mechanism d is tilted for some reason and the core components g such as fuel assemblies are floating up from the core c, the transducer b If there is a downward error in the transmission direction, the ultrasonic waves are transmitted and received through a small gap between the core component g and the core upper mechanism d, so it is conceivable that an abnormality cannot be detected. In this case, if the upper core mechanism d is rotated by mistake, the lower surface of the upper core mechanism d and the core components g may interfere, and the core and other structures may be damaged.

Further, as shown in FIG. 3, if the reference position o of the horizontal scanning range is shifted and scanning is performed within the range of _θ2 , there is a possibility that the shaded area p cannot be detected. Furthermore, in the conventional example described above, since the distance from transducer b to reflector f is long, it is difficult to adjust the ultrasonic output level of transducer b using reflector f. There were also problems such as difficulty in confirming the transmission of sound waves.

This invention has been made based on the above-mentioned circumstances, and its purpose is to enable the interior of a fast breeder reactor to accurately set the reference position of a transducer and to accurately detect obstacles, etc. in the upper part of the reactor core. An object of the present invention is to provide a fluoroscopy device.

The present invention will be explained below based on an embodiment shown in FIGS. 4 to 6. In the figure, reference numeral 1 denotes a reactor vessel of a liquid metal cooled fast breeder reactor, and within this reactor vessel 1, for example, liquid sodium 2 is accommodated as a liquid metal coolant. Reference numeral 3 denotes a core surrounded by a core barrel 3a, and a core upper mechanism 4 is provided above and facing the core 3. This core upper mechanism 4 is attached to a rotating shielding plug 5.

An internal see-through device 6 is provided in the reactor vessel 1 . Reference numeral 7 denotes the inspection head, and this inspection head 7 can be rotated in the horizontal direction by a drive section 8 attached to the rotary shielding plug 5, and can also be raised and lowered. . An ultrasonic transducer 9 is attached to this inspection head 7. This transducer 9 transmits ultrasonic waves toward a gap 10 between the reactor core 3 and the upper core mechanism 4, that is, in a direction across the reactor core 3, and receives the echo waves. Further, the transducer 9 is configured to be able to adjust the vertical elevation angle.

An ultrasonic reflector 11 is provided at a position facing the transducer 9. This ultrasonic reflector 11 is disposed on the opposite side of the reactor core as an extension of the above-mentioned gap 10, that is, with this gap 10 in between. A predetermined length is provided in the circumferential direction. In this embodiment, an ultrasonic reflector 11 is provided in the reactor inner cylinder 12.
is installed.

Also, the core side 3 on the side of the transducer 9
Reference reflectors 13a and 13b are attached to the upper part of b and the lower part of the side surface 4a of the core upper mechanism, respectively. The reference reflectors 13a and 13b are as shown in FIG. , and an escape reflection section 15 that reflects the ultrasonic waves in a direction other than the transducer 9. The specular reflection surface 14 is formed in a cross shape, including a horizontal reference surface 14a formed in the horizontal direction and a vertical reference surface 14b formed in the vertical direction. These reference reflectors 13a and 13b are fixed to each side of the core 3 and the upper core mechanism 4 so that each specular reflection surface 14 is at a predetermined position that should serve as a reference for the transducer 9. By raising and lowering the head 7, the transducer 9 can be opposed to it.

Next, the operation of the device of the above embodiment will be explained. First, the transducer 9 is inserted into the core upper mechanism 4.
The ultrasonic wave is emitted facing the reference reflector 13a attached to the reference reflector 13a. While the transducer 9 receives the echo waves reflected by the specular reflector 14, the drive section 8 rotates the transducer 9 in the horizontal direction and also performs elevation and elevation movements in the vertical direction. Then, when rotating in the horizontal direction, a signal level is obtained based on the vertical reference plane 14b, and when making an elevation movement, a signal level is obtained based on the horizontal reference plane 14a. Part 8
Comparison with the reference using electrical instrumentation and calibration of the reference position will be performed. Thereby, the reference position of the transducer 9 with respect to the core upper mechanism 4 is determined.
Next, the inspection head 7 is lowered, the transducer 9 is opposed to the reference reflector 13b attached to the side of the core, and the reference position relative to the core 3 is determined by following the same procedure as for the reference reflector 13a. Let's do it. Then, by combining the correction data at these two upper and lower locations, a reference position of the transducer 9 for transmitting ultrasonic signals horizontally and within a predetermined scanning range to the gap 10 in the upper part of the core is obtained.

After this reference positioning operation is completed, an operation for detecting obstacles, etc. in the gap 10 is started. That is, when an ultrasonic wave is emitted from the transducer 9 toward the gap 10, the ultrasonic wave is reflected by the reflector 11 and an echo wave is received by the transducer 9. The inspection head 7 is then rotated in the horizontal direction by a drive section 8 to scan the gap 10 within a predetermined angular range. For example, if fuel assemblies are floating from the reactor core 3, control rods have not been separated, or obstacles are floating, the ultrasonic waves will pass through these obstacles before reaching the reflector 11. reflected by etc. Therefore, by detecting this echo wave, it is possible to know the presence of an obstacle or the like.

In this way, according to the internal see-through device 6, the transducer 9 can be set at an accurate reference position using the reference reflectors 13a and 13b as described above, so that, for example, the ultrasonic wave is tilted in the vertical direction. It is possible to prevent the transmission from being transmitted, and to correctly transmit the transmission in the horizontal direction along the gap portion 10. Therefore, the ultrasonic waves will not be reflected on the upper surface of the reactor core 3 or the lower surface of the upper core mechanism 4 and cause false detection. In addition, since ultrasonic waves can be transmitted correctly in the horizontal direction, for example, as shown in Figure 2, when the upper core mechanism is tilted and the core components are floating from the reactor core, the transmitted ultrasonic waves This eliminates the possibility of accidentally passing through the gap and reaching the reflector, making it possible to reliably detect obstacles, etc. present in the gap. Furthermore, since the rotation reference position in the horizontal direction can be set accurately, there is no detectable area such as the shaded area p in FIG. 3, and a predetermined range can be reliably inspected.

Furthermore, since the reference reflectors 13a and 13b are installed close to the transducer 9,
Since there is little noise mixed in and the S/N ratio is good, an accurate reference position can be set, and the output of the transducer 9 can be easily adjusted using these reference reflectors 13a and 13b.

Note that FIGS. 7 and 8 show a modified example of the reference reflector, and the reference reflector 20 of this example
In this example, a groove-shaped escape reflection portion 22 is formed on a specular reflection surface 21 that reflects ultrasonic waves toward the transducer 9. The escape reflection section 22 has a cross shape including a horizontal reference section 22a formed in the horizontal direction and a vertical reference section 22b formed in the vertical direction. When the transducer 9 is rotated in the horizontal direction, a signal level is obtained based on the vertical reference part 22b, and when the transducer 9 is moved in elevation, a signal level is obtained based on the horizontal reference part 22a. It's summery. In short, the specific shape of the reference reflector is not limited to these embodiments and can be modified in various ways.

As explained above, in this invention, reference reflectors are attached to the eccentric side facing the transducer and the side of the core upper mechanism, respectively.
Since the reference positioning of the transducer can be set accurately using these reference reflectors, ultrasonic waves can be transmitted horizontally accurately into the gap between the reactor core and the upper core mechanism, and within a predetermined horizontal angle range. You can scan with . Therefore, without causing false positives,
It is extremely effective in improving the safety of nuclear reactors, as it can accurately detect whether core components such as fuel assemblies are floating, whether control rods are detached, and whether the upper core mechanism is tilted. In addition, even if the reference position shifts due to thermal expansion, etc., the reference position of the transducer can be easily calibrated using these reference reflectors, so it can be used without preheating, reducing the time required for inspection. can be shortened.

Moreover, it is possible to easily confirm the output of the transducer or calibrate the output level by using the reference reflector, which has great effects such as easy maintenance and inspection.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional examples, with Figure 1 being a vertical cross-sectional view of the reactor, Figure 2 being a vertical cross-sectional view showing the core upper mechanism in a tilted state, and Figure 3 showing the ultrasonic scanning range. 4 to 6 show an embodiment of the present invention, FIG. 4 is a longitudinal sectional view of the reactor, FIG. 5 is a perspective view of a reference reflector, and FIG. is a front view of the reference reflector, FIG. 7 is a perspective view showing a modified example of the reference reflector, and FIG. 8 is a front view of the reference reflector. DESCRIPTION OF SYMBOLS 1... Reactor vessel, 3... Reactor core, 3b... Core side, 4... Core upper mechanism, 4a... Core upper mechanism side, 6... Internal see-through device, 9... Ultrasonic transducer, 10 ...Gap portion, 11...Ultrasonic reflector, 13a, 13b...Reference reflector, 14...
... Regular reflection surface, 20 ... Reference reflector, 21 ... Regular reflection surface.

Claims (1)

[Scope of Claims] 1. An ultrasonic transducer that is movably and rotatably installed in the reactor vessel and transmits ultrasonic waves in a direction across the reactor core; an ultrasonic reflector disposed on an extension of the gap between the core upper mechanism; and a transducer provided facing the transducer on the side of the core on the transducer side and on the side of the core upper mechanism, respectively. What is claimed is: 1. A fast breeder reactor internal viewing device, comprising: a reference reflector having a specular reflection surface that reflects ultrasonic waves emitted from the transducer toward the transducer. 2 Claims characterized in that the specular reflection surface of the reference reflector has a cross shape, including a horizontal reference surface formed in the horizontal direction and a vertical reference surface formed in the vertical direction. 2. The internal see-through device for a fast breeder reactor according to item 1.