JPS6322242B2 - - Google Patents

Description

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

In general, in sodium-cooled fast breeder reactors and the like, 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. In other words, this type of device is equipped with an ultrasonic transmitter/receiver that transmits and receives ultrasonic waves in the horizontal direction within the reactor vessel, and an ultrasonic transmitter/receiver that transmits and receives ultrasonic waves in the horizontal direction. It is equipped with an ultrasonic reflector. Then, by transmitting this ultrasonic wave into the gap between the reactor core and the upper core mechanism and receiving the echo,
It is designed to detect phenomena such as the lifting of fuel assemblies from the core and the presence of foreign objects in the upper part of the core.

By the way, since the above ultrasonic transmitter/receiver emits ultrasonic waves at a wide range of angles in the horizontal direction, it is necessary to arrange reflectors over a fairly wide range in the circumferential direction of the reactor vessel. A rigid structure was adopted in which a long, integral reflector along the mounting wall inside the container was fixed with mounting seats at multiple locations spaced apart in the circumferential direction. Therefore, in this case, the mounting wall inside the reactor vessel and the reflector are firmly constrained to each other via the mounting seat, so that external loads due to earthquakes, for example,
When the mounting wall is deformed due to thermal transient loads that occur during transient operation of the nuclear reactor, a very large load is applied to the reflector through the mounting seat, which poses a major problem in maintaining the structural integrity of the reflector. If the reflector were to be damaged, it would no longer be able to function as an ultrasonic fluoroscopy device, making it impossible to detect floating fuel assemblies or obstacles in the upper part of the reactor core. .

This invention was made based on the above circumstances, and its purpose is to prevent excessive loads from being applied to the reflector even if the mounting wall to which the reflector is attached is deformed due to external loads such as earthquakes or thermal transient loads. An object of the present invention is to provide an internal see-through device for a fast breeder reactor that can prevent damage to the reflector and prevent damage to the reflector.

That is, in this invention, the ultrasonic reflector is divided into a plurality of parts in the circumferential direction of the reactor vessel, and each divided part is independently fixed to the mounting wall.

The present invention will be described below with reference to an embodiment shown in the drawings. In the figure, reference numeral 1 denotes a reactor vessel of a fast breeder reactor, and a liquid metal coolant such as liquid sodium 2 is housed within this reactor vessel 1. Further, 3 is a reactor core, and a core upper mechanism 4 is provided above and facing the reactor 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 its inspection head, and this inspection head 7 is adapted to be rotated in the horizontal direction by a drive mechanism 8 attached to the rotary shielding plug 5. An ultrasonic transmitter/receiver 9 is attached to this inspection head 7. This ultrasonic transmitter/receiver 9 transmits ultrasonic waves in the horizontal direction toward the gap 10 between the reactor core 3 and the upper core mechanism 4 and receives the echo waves.

An ultrasonic reflector 11 is provided at a position facing the ultrasonic transmitter/receiver 9. This ultrasonic reflector 11 is arranged along the circumferential direction of the reactor vessel 1, and in this embodiment is attached to the reactor inner cylinder 1a. The reflector 11 is provided with a plurality of reflective surface rows 15 in the circumferential direction of the reactor vessel 1, and is divided into a plurality of, for example, five divided bodies 11a, 11.
It is divided into 11b, 11c, 11d, and 11e.
Each of the divided bodies 11a to 11e is fastened with bolts or other fasteners 14 to the mounting wall 13 of the reactor inner cylinder 1a by means of one mounting seat 12 so that each of the divided bodies 11a to 11e is fixed only at the center of the divided body. It is fixed using Therefore, each of the divided bodies 11a to 11e is in a state of being fixed independently from each other without being restrained by each other.

In the internal fluoroscopy device 6 configured as described above, ultrasonic waves are transmitted from the ultrasonic transmitter/receiver 9, and the ultrasonic waves are transmitted to the gap 10 between the reactor core 3 and the upper core mechanism 4.
The echo wave is reflected by the reflector 11 and received by the ultrasonic transmitter/receiver 9. Then, the inspection head 7 is rotated by the drive mechanism 8, and the inspection head 7 is rotated by the drive mechanism 8 to
scan in the horizontal direction. For example, core 3
If the fuel assembly is floating or there are obstacles floating, the ultrasonic waves will be reflected by these obstacles before reaching the reflector 11. Therefore, by detecting this echo wave, it is possible to know the presence of an obstacle or the like.

However, according to the internal see-through device, the reflector 1
1 is divided into a plurality of parts in the circumferential direction, and each divided body 11
a, 11b, 11c, 11d, and 11e are each fixed by one mounting seat 12, so even if the mounting wall 13 is deformed as shown in FIG. 4 due to an earthquake or thermal transient load, for example, Each divided body 1
Since 1a, 11b, 11c, 11d, and 11e are not constrained to each other, excessive loads can be prevented from being applied to each other, and the reflector 11 can be prevented from being damaged.

Therefore, the reflector 11 can function properly even when inspecting a nuclear reactor abnormality after a large-scale earthquake or a large thermal transient, and is extremely effective in ensuring the safety of the reactor.

It goes without saying that the number of divisions of the reflector is not limited to the embodiment.

As explained above, the present invention includes an ultrasonic transmitter/receiver disposed within a reactor vessel, and a gap on the inner circumferential side of the reactor vessel at a position facing the ultrasonic transmitter/receiver. an ultrasonic reflector consisting of a plurality of divided bodies disposed along the circumferential direction of an inner cylinder arranged along the circumferential direction and provided with a plurality of reflective surface rows and divided in the circumferential direction; Since the reflector and the mounting wall are not constrained to each other, even if the mounting wall is deformed, However, each divided body can absorb this deformation, and can prevent an excessive load from being applied to the reflector. Therefore, the structural integrity of the reflector is not impaired even when subjected to seismic loads or severe thermal loads, and it is possible to maintain its normal function as a reflector. It can detect the presence or absence of rod separation and the presence of other obstacles, which is highly effective in ensuring the safety of nuclear reactors.

Furthermore, since the ultrasonic reflector of the present invention is attached to the inner cylinder located on the inner peripheral side of the reactor vessel,
The integrity of the reactor vessel will not be compromised due to welding distortion, etc. In addition, since each divided body is attached to the inner cylinder via a mounting seat attached to the circumferential center, it is possible to secure a coolant flow path between the inner cylinder and the divided body. It is possible to prevent the occurrence of uneven temperature distribution and thereby damage to the structural integrity.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional view of a fast breeder reactor, Fig. 2 is a cross-sectional view, and Fig. 3 is a cross-sectional view showing a part of the reactor vessel and ultrasonic reflector. FIG. 4 is a cross-sectional view showing a state in which the mounting wall of the reflector is deformed. DESCRIPTION OF SYMBOLS 1... Reactor vessel, 6... Internal see-through device, 9... Ultrasonic transmitter/receiver, 11... Ultrasonic reflector, 11a-1
1e...Divided body, 13...Mounting wall.

Claims (1)

[Claims] 1. An ultrasonic transmitter/receiver disposed within the reactor vessel, and an inner cylinder located at a position facing the ultrasonic transmitter/receiver with a gap on the inner circumferential side of the reactor vessel. an ultrasonic reflector consisting of a plurality of divided bodies disposed along the direction and provided with a plurality of reflective surface rows and divided in the circumferential direction; An internal viewing device for a fast breeder reactor, characterized by comprising a mounting seat fixed to an inner cylinder.