JPH0627246A - Degree of burn-up measuring apparatus - Google Patents

Abstract

PURPOSE:To provide a degree of burn-up measuring apparatus having simple structure which can measure radiation of an underwater object, in the vicinity thereof, without sacrifice of radiation shielding effect or without wetting a radiation detector while enhancing maintainability of radiation detector. CONSTITUTION:The degree of burn-up measuring apparatus comprises a rod-like flexible insertion pipe 1 having a closed end and a part fracturable upon insertion of a radiation detector, a radiation detector 2 to be inserted into the insertion pipe 1 from the open end thereof and detecting radiation of an object 0, and a drive means for moving the radiation detector 2 in the insertion pipe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burnup measuring apparatus for measuring the burnup of an object to be measured (spent fuel rods, etc.) immersed in water, for example, in a nuclear power plant by radiation. Combustion with a simple structure that can measure the radiation close to the object to be measured in water without reducing the radiation shielding effect to the outside and without wetting the radiation detector, and also improving the maintainability of the radiation detector It relates to a degree measuring device.

[0002]

2. Description of the Related Art Generally, for example, in a nuclear power plant, a burnup measuring apparatus has been used which measures the burnup of a spent fuel rod, which is an object to be measured and is immersed therein, by radiation. .

FIG. 7 is an external perspective view showing an example of the entire structure of a conventional burnup measuring device of this type. As shown in FIG. 7, this burnup measuring device includes three types of plural radiation detectors 12a, 12b, 12c, 1 on a large inspection table 10.
2d is placed and immersed in water together with the inspection table 10 at a water depth of 12
It is placed at a fixed position of m. Then, the spent fuel rod is inserted from the fuel rod loading port 11 on the upper portion into the central portion of the apparatus, and the radiation is measured.

By the way, in such a burnup measuring device, the radiation detectors 12a, 12b, 12c, 12d are always immersed in water, so that the device must be waterproof. In addition, since the device is complicated, there are many contaminated parts due to radioactive contaminants in the water, and decontamination is difficult. Further, the radiation detectors 12a, 12b, 12c, 1
When performing 2d maintenance and inspection, a large inspection table 10
Therefore, it is necessary to pull up the device from the water for each operation, which requires a great deal of labor and time.

[0005]

As described above, in the conventional burnup measuring apparatus, the apparatus is complicated, and the apparatus must be waterproof, and the radiation detector is difficult to maintain and inspect. There was a problem that was.

An object of the present invention is to have a simple structure and to measure the radiation in the vicinity of an object to be measured in water without reducing the radiation shielding effect to the outside and without wetting the radiation detector. An object of the present invention is to provide an extremely reliable burnup measuring device capable of improving the maintainability of

[0007]

In order to achieve the above object, in a burnup measuring apparatus for measuring the burnup of a measuring object immersed in water by radiation, first,
In the invention described in (1), a rod-shaped insertion tube made of a flexible material having a closed tip, at least a part of which is crushed when the radiation detector is inserted, and inserted into the insertion tube from the side opposite to the tip side to be movable. It is provided with a radiation detector which is provided and detects radiation from the object to be measured, and a drive means which moves the radiation detector inside the insertion tube.

According to the second aspect of the present invention, the insertion tube is made of an articulated material having a closed tip and is movable in water while being immersed in the water. A radiation detector that is movably provided by being inserted from the distal end side and that detects radiation from a measurement object, and a driving unit that moves the radiation detector inside the insertion tube are configured. Here, in particular, a protection cell for protecting the insertion tube from the influence of radiation is attached to the distal end portion of the insertion tube. Further, the protection cell is a bellows. Further, the insertion tube is made of rubber or metal having high radiation resistance.

[0009]

Therefore, in the burnup measuring device of the present invention,
By inserting the radiation detector inside the insertion tube, the radiation detector is not directly immersed in water and is not directly contaminated with radioactivity. Further, the insertion tube can be prevented from leaking radiation to the outside by crushing a part of the insertion tube or making it into a spiral shape. Further, the radiation detector can be easily taken out and replaced by freely moving inside the insertion tube, and maintenance and inspection of the radiation detector can be easily performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing a structural example of a burnup measuring apparatus according to the present invention. In FIG. 1, the burnup measuring device is a flexible material with a closed tip (for example,
A rod-shaped insertion tube 1 made of a material having high radiation resistance such as rubber or metal is used, and at least a part of the insertion tube is crushed when the radiation detector is inserted. A radiation detector 2 that is movably provided and detects radiation from a spent fuel rod 0 that is an object to be measured.
And a pair of streamlined hemispheres 3 attached so as to sandwich the radiation detector 2 from both sides, and one hemisphere 3 on the side opposite to the tip of the insertion tube 1, and the inside of the insertion tube 1 is exposed to the radiation detector 2 And a wire 4 which is a driving means for moving the hemisphere 3, and a signal line 5 which is attached to the radiation detector 2 along the wire 4 and which transmits a detection signal from the radiation detector 2 to the outside. . The insertion tube 1
Keeps it immersed in water and can move in water.

Next, when the burnup of the spent fuel rod 0 is measured by using the burnup measuring apparatus of this embodiment having the above-mentioned structure, the insertion pipe 1 is crushed by water pressure in water. It is inserted into the water in the shape, and is brought close to the spent fuel rod 0 immersed in the water. In addition, when it cannot be crushed only by the water pressure, the air in the insertion tube 1 can be deflated and crushed.

Next, from the insertion opening on the side opposite to the tip of the insertion tube 1,
When the radiation detector 2 and the hemisphere 3 are inserted by the wire 4, the hemisphere 3 pushes the flexible insertion tube 1 and expands the inside of the insertion tube 1. Then, when the radiation detector 2 moves toward the distal end side of the insertion tube 1, the insertion tube 1 near the insertion opening is crushed by water pressure, and the radiation detector 2 can be inserted into the insertion tube 1 while shielding the radiation. .

Thereafter, the radiation detector 2 detects the radiation of the spent fuel rod 0 in a state where the radiation detector 2 is positioned near the tip of the insertion tube 1, and the detection signal is detected by the signal line 5.
Is transmitted to the outside through.

The same applies to the case where the radiation detector 2 and the hemisphere 3 are taken out by the wire 4 after the burnup measurement of the spent fuel rod 0 is completed, and the radiation detector 2 is inserted while the radiation is shielded. You can take it out from 1.

Therefore, in such a burnup measuring device, the radiation detector 2 is inserted into the insertion tube 1 so that the radiation detector 2 is not directly immersed in water and the radiation detector 2 is made waterproof. You don't have to. Further, the radiation detector 2 is not directly contaminated by radioactivity, and decontamination can be performed only by the insertion tube 1 having a simple structure.

Further, at least a part of the insertion tube 1 is crushed when the radiation detector 2 is inserted so that the radiation does not leak to the outside from the insertion tube 1 and the radiation can be shielded from the outside. That is, the upper portion of the insertion tube 1 is prevented from being crushed and the radiation is prevented from leaking from the insertion tube 1 to the outside, which has a shielding effect.

Furthermore, since the streamlined hemisphere 3 is attached to the radiation detector 2, the radiation detector 2 can move smoothly in the insertion tube 1. As a result, the radiation detector 2 can be easily taken out, so that the radiation detector 2 itself can be easily maintained and inspected. As described above, in the burnup measuring apparatus of this embodiment, the following various effects can be obtained.

(A) Since the radiation detector 2 is inserted inside the insertion tube 1, the radiation detector 2 is not directly immersed in water, so that the radiation detector 2 does not have to be waterproof. Well, it becomes possible to simplify the device. (B) When the insertion tube 1 is partially crushed, the insertion tube 1
Radiation can be prevented from leaking from the outside, which has a shielding effect.

(C) Since the radiation detector 2 can be easily attached and detached, it is possible to easily perform maintenance and inspection of the radiation detector 2 itself as a single unit, and the radiation detector 2 can be freely replaced. Is possible. (D) Since the measurement unit can be brought close to the spent fuel rod 0 which is the measurement object, the detection sensitivity of the radiation detector 2 can be improved.

(E) Since the entire apparatus has an extremely compact, simple and simple structure as compared with a conventional large inspection table, the apparatus can be moved easily, and surface contamination due to radiation is small, and decontamination work is possible. Can be performed easily. The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below.

(A) FIG. 2 is a sectional view showing a structural example of a spiral burnup measuring apparatus according to another embodiment of the present invention. That is, as shown in FIG. 2, the insertion tube 1 itself made of a multi-joint type material having high radiation resistance (for example, rubber or metal of a material having high radiation resistance is used) is formed by bending it in a spiral shape, Even if the radiation detector 2 is inserted therein, leakage of radiation to the outside can be prevented.

(B) FIG. 3 is a sectional view showing a structural example of an air injection type burnup measuring apparatus according to another embodiment of the present invention. That is, as shown in FIG. 3, the air inlet 6 is attached to the inlet portion of the insertion tube 1.

In the burnup measuring apparatus, first, as shown in FIG. 3A, air is filled from the air inlet 6 to inflate the insertion tube 1 and the radiation detector 2 is inserted all the way. Next, the air is evacuated, the insertion tube 1 is crushed, and the same figure (b) is shown.
Like Further, by bending the tip of the air injection port 6 and attaching the shield 7 around it, it is possible to prevent radiation from leaking to the outside when the radiation detector 2 is inserted.

(C) FIG. 4 is a sectional view showing an example of the construction of a burnup measuring device having a detector moving pulley according to another embodiment of the present invention. That is, as shown in FIG. 4, in order to move the radiation detector 2 inside the tube, a pulley 8 is attached to the distal end of the insertion tube 1 and an operable position outside, and the radiation detector 2 is attached to the wire 4 and pulled. It is configured to be moved. In this case, the wire 4 is automatically driven by a motor or the like.

(D) FIG. 5 is a sectional view showing a structural example of a burnup measuring apparatus according to another embodiment of the present invention. That is, as shown in FIG. 5, a protective cell 9a is attached to the distal end portion of the insertion tube 1 to protect the insertion tube 1 from the influence of radioactivity.

(E) FIG. 6 is a sectional view showing a structural example of a burnup measuring apparatus according to another embodiment of the present invention. That is, as shown in FIG. 6, the protection cell 9a in FIG.
A bellows-type protection cell 9b is used, which is contracted until measurement, as shown in FIG. 7A, and during measurement, air is filled in to inflate the bellows as shown in FIG. The radiation detector 2 is brought close to the burned rod 0. This makes it possible to further reduce the influence of radioactivity during non-measurement.

[0028]

As described above, according to the present invention, there is provided a rod-shaped insertion tube which is made of a flexible material having a closed tip and at least a part of which is crushed when the radiation detector is inserted (or the tip is A rod-shaped insertion tube made of a closed flexible material, at least a part of which is crushed when the radiation detector is inserted, and) is inserted inside the insertion tube from the opposite tip side and is movably provided, Since the radiation detector for detecting the radiation of and the driving means for moving the radiation detector inside the insertion tube are provided, the radiation detector has a simple structure without reducing the radiation shielding effect to the outside. Highly reliable burnup measurement that allows you to measure radiation close to the object to be measured in water without having to wet it, and further improve the maintainability of the radiation detector. Location can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a burnup measuring device according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the burnup measuring apparatus according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the burnup measuring device according to the present invention.

FIG. 4 is a sectional view showing another embodiment of the burnup measuring device according to the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the burnup measuring device according to the present invention.

FIG. 6 is a sectional view showing another embodiment of the burnup measuring device according to the present invention.

FIG. 7 is an external perspective view showing an example of the overall configuration of a conventional burnup measuring device.

[Explanation of symbols]

1 ... Insertion tube, 2 ... Radiation detector, 3 ... Hemisphere, 4 ... Wire, 5 ... Signal line, 6 ... Air injection port, 7 ... Shield, 8 ... Pulley, 9a, 9b ... Protective cell.

Claims (5)

[Claims] 1. A burnup measuring device for measuring the burnup of an object to be measured immersed in water by means of radiation, which is made of a flexible material having a closed tip and at least a part of which is crushed when a radiation detector is inserted. A rod-shaped insertion tube, a radiation detector that is movably provided by being inserted into the inside of the insertion tube from the side opposite to the tip side, and detects radiation from the measurement object, and the inside of the insertion tube is the radiation detector. A burnup measuring device comprising: a drive unit that moves the burner. 2. A burnup measuring device for measuring the burnup of a measurement object immersed in water by radiation, comprising a multi-joint material with a closed tip, which is movable in water while immersed in water. A spiral insertion tube, a radiation detector that is movably provided by being inserted into the insertion tube from the side opposite to the tip side, and detects radiation from the measurement object, and the radiation detection inside the insertion tube. A burnup measuring device comprising: a drive unit for moving the vessel. 3. The burnup measuring device according to claim 1, wherein a protection cell that protects the insertion tube from the influence of radiation is attached to the distal end portion of the insertion tube. 4. The burnup measuring device according to claim 3, wherein the protection cell is a bellows. 5. The burnup measuring device according to claim 1, wherein the insertion tube is made of rubber or metal having high radiation resistance.