JP2863482B2 - Capsule for radiation irradiation test - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation irradiation test capsule for accommodating a sample for performing a radiation irradiation test of neutrons, gamma rays, etc., and more particularly to a radiation capable of irradiating a sample under desired conditions. The present invention relates to an irradiation test capsule.

[0002]

2. Description of the Related Art In order to inspect the influence of radiation deterioration of materials mounted on a nuclear reactor or the like due to radiation, a radiation irradiation test such as neutron radiation or γ-ray is performed. In such a radiation irradiation test, a sample is mounted on a place such as a nuclear reactor where radiation is generated, the sample is irradiated with radiation during operation of the reactor, and then the sample is taken out of the reactor and inspected for radiation deterioration. And other tests. In such a radiation irradiation test, a sample is stored in a cylindrical container called a capsule and mounted on a nuclear reactor or the like.

[0003]

The degradation of radioactive irradiation of a material mainly depends on the irradiation temperature and the radiation dose to the material. It is also known that the degree of irradiation deterioration of a material is different when the radiation flux is different even when the radiation irradiation amount is the same. Therefore, in order to accurately analyze the radiation deterioration of the sample due to radiation irradiation, it is necessary to set the irradiation conditions such as the irradiation temperature and the amount of irradiation radiation at the time of irradiation of the sample to the desired conditions before conducting the irradiation test. It is.

[0004] However, when the reactor is operated, the output of the reactor gradually rises from the start of the operation, reaches a rated state in which a constant output is maintained after a certain period of time, and thereafter the output gradually decreases when the operation is stopped. And after a certain period of time, the output becomes zero. In a radiation irradiation test using a conventional capsule, since the radiation generated from the radiation source is directly irradiated to the sample, the sample is affected by transient radiation effects other than the desired irradiation conditions at the time of starting and stopping the reactor, For example, it receives its thermal and radiation history. For this reason, a radiation irradiation test cannot be performed under desired irradiation conditions, and it is not possible to efficiently analyze irradiation deterioration or the like of a material using irradiation temperature and irradiation radiation amount as parameters based on the test results. there were.

In the present invention, in view of such a problem of the conventional capsule for radiation irradiation test, the sample is not given a thermal or radiation history at the time of starting or shutting down the reactor, and the sample is irradiated under a desired irradiation condition. To be able to perform radiation tests on
An object of the present invention is to enable efficient analysis of irradiation deterioration and the like of a material using irradiation temperature and irradiation radiation amount as parameters.

[0006]

According to the present invention, in a radiation irradiation test capsule, a fixed cylindrical shield 9a and a rotary shield 9b, each of which has a partially cylindrical shape, are provided around a sample holder 8 for storing a sample. By rotating the rotary shield 9b, the radiation source side is opened and closed in a shutter shape. Thus, the radiation applied to the sample from the radiation source side can be interrupted as needed, and the radiation can be applied in a desired irradiation pattern.

That is, the radiation irradiation test capsule according to the present invention comprises a sample holder 8 for holding a sample 5 and a partial cylinder fixedly arranged around the sample holder 8 and having a side surface opened by a partial angle. A fixed shield 9a for shielding radiation having a shape, and a partial cylindrical body which is rotatably disposed around the holder 8 concentrically with the fixed shield 9a and has an angle wider than the opening angle of the fixed shield 9a. It is characterized in that it has a rotating shield 9b for shielding radiation and a rotating mechanism for rotating the rotating shield 9b around its central axis.

In this irradiation capsule, the open side surface of the fixed shield 9a is opened and closed by rotating the rotary shield 9b. That is, when the rotary shield 9b is on the open side of the fixed shield 9a, the side is closed, and the sample holder 8 inside them is shielded from the outside. On the other hand, if the rotating shield 9b is displaced from the open side of the fixed shield 9a, the side is opened and the use holder 8 inside them is exposed to the outside. The rotation of the rotation shield 9b causes the sample 5 to rotate.
Can be irradiated or the irradiation can be blocked. Therefore, when this radiation irradiation capsule is mounted inside a nuclear reactor or the like, and the open side surface of the fixed shield 9a faces the radiation source, the rotation of the rotary shield 9b causes
The sample inside the sample holder 8 can be irradiated with radiation or blocked. This radiation pattern
It can be changed arbitrarily by the rotation of the rotary shield 9b.

The radiation irradiation capsule includes an outer cylinder 3 that covers the sample holder 8, the fixed shield 9a and the rotary shield 9b, and the rotary shield 9b is rotatable around the central axis of the outer cylinder 3. Supported. Furthermore, the outer cylinder 3
A centering member 1 for positioning the center of the sample holder 8 at a predetermined position is provided at a tip end of the reactor, whereby the sample holder 8 can be mounted at a predetermined position inside the nuclear reactor.

[0010]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings. The outer cylinder 3 made of a stainless steel pipe or the like and the protective tube 17 are connected in an airtight manner in the longitudinal direction via the upper end plug 4 made of stainless steel or the like so that the central axes coincide. A protective tube 18 made of a stainless steel tube or the like having a larger diameter than the protective tube 17 is air-tightly connected to the upper end of the protective tube 17 in the longitudinal direction so that the central axes thereof coincide with each other. A protective tube 19 made of a thin and long stainless steel tube or the like is hermetically connected in the longitudinal direction so that the central axes coincide.

A lower end of the outer cylinder 3 is sealed with a lower end plug 2 made of stainless steel or the like, and a heat insulating plate 6 is attached to an upper surface of the lower end plug 2. Further, a sample holder supporting member 23 is attached to the upper surface of the heat insulating plate 6. On the other hand,
A centering member 1 is attached below the lower end plug 2. A support pin (not shown) protruding from the bottom surface of the nuclear reactor or the like is fitted on the front end surface of the centering member 1,
A concave portion for supporting the lower end of the outer cylinder 3 at a predetermined position is formed, and the central axis of the concave portion coincides with the central axis of the outer cylinder 3.

As shown in FIG. 2, a sample holder 8 is attached to the center of the outer cylinder 3, and a sample 5 to be subjected to a radiation irradiation test is loaded inside the sample holder 8. The sample holder 8 is mounted at the center of the outer cylinder 3 by removing the lower end plug 2 from the lower end of the outer cylinder 3, and upper and lower ends thereof are supported by a joint 21 and a sample holder support member 23 described later. It is fixed on the central axis of the cylinder 3. A fixed shield 9a and a rotary shield 9b are mounted in the outer cylinder 3 so as to surround the sample holder 8, and each of the shields 9a and 9b is made of a material for shielding radiation, for example, hafmium (Hf). ).

The fixed shield 9a has a partial cylindrical shape having an angle of 180 ° or more, and is fixed inside thereof so as to coincide with the center axis of the outer cylinder 3. Fixed shield 9 shown
a has an angle of about 200 °, and the side of the other about 160 ° is open. The rotary shield 9b has a partial cylindrical shape whose outer diameter is smaller than the inner diameter of the fixed shield 9a and has an angle of 180 ° or more.
It is arranged inside so as to coincide with the central axis of a.
The lower end of the rotating shield 9b is rotatably supported on the lower inner peripheral wall of the outer cylinder 3 via the bearing 7, and the upper end of the rotating shield 9b is connected to a rotating mechanism via a joint 21. I have.

A heater 11 is mounted in a space between the inner surface of the outer cylinder 3 and the shields 9a and 9b. The heater 11 can heat the sample 5 in the sample holder 8 to a required temperature. it can. The rotation mechanism includes a motor 16 such as a stepping motor and the rotation introducing machine 14. The motor 16 is housed in a protective tube 18, and its shaft 20 is connected to the rotation introducing machine 14. This rotation introducing machine 14 penetrates the center of the upper end plug 4 and
It is supported by the same end plug 4. The shaft 24 of the rotation introducing machine 14 is connected to the joint 21, and the joint 21 is rotatably supported on the upper end of the outer cylinder 3 by the bearing 12. Therefore, the rotation shield 9b is rotated around the central axis of the outer cylinder 3 by driving the motor 16.

As shown in FIG. 3, pipes 15, 15,... Penetrate through a portion of the upper end plug 4 around the rotation introducing machine 14, and a part of these pipes 15, 15,. The other part is for ventilation between the 17 side and the outer cylinder 3 side, and the other part is for drawing out wiring and the like between the protective tube 17 side and the outer cylinder 3 side.
When the capsule is mounted on the reactor, the uppermost protective tube 19 is drawn out of the reactor, and the protective tube 19,
Air is supplied into the outer cylinder 3 through the protective tubes 17 and 18 and the tubes 15, 15.

Such a capsule for radiation irradiation test is mounted inside a nuclear reactor or the like with the outer cylinder 3 and the protection tubes 17 and 18 arranged vertically, and the centering member 1 at the tip of the outer cylinder 3 is attached to the bottom of the reactor. To support a lower end side of the outer cylinder 3 at a predetermined position in the reactor. Further, the protection tube 19 is held vertically in a state where the protection tube 19 is pulled out from the reactor. At this time, as shown by the arrow on the right side of FIG. 2, the open side of the fixed shield 9a faces the radiation source, for example, the reactor core.

When the nuclear reactor is started in this state, the rotary shield 9b is first stopped at the position shown in FIG. 2, and the entire sample holder 8 is closed by the shields 9a and 9b.
Thereafter, when the operation of the reactor reaches the rated state, the motor 16 is driven to rotate the rotary shield 9b in the direction indicated by the arrow 180 ° (or the opposite direction), and the shield 9 is rotated.
Open the radiation source side of a and 9b. Thereafter, the rotary shield 9b is again rotated by 180 °, and the entire sample holder 8 is closed by the shields 9a and 9b as shown in FIG. In this manner, the sample holder 8 side is intermittently exposed to the radiation source side, and the sample 5 therein is intermittently irradiated with radiation.

FIG. 4 shows the output of the reactor and the sample 5 at this time.
7 is an example of a graph showing a relationship between radiation irradiation illuminance and irradiation irradiance. In the operation of a general reactor, the output of the reactor gradually increases from the start of the operation, reaches a rated state after a certain time, and the output becomes constant. Thereafter, when the operation is stopped, the output gradually decreases, and after a certain period of time, the output becomes zero. In this case, when a capsule having no shields 9a and 9b is used, the sample 5 in the sample holder 8 is constantly irradiated with the radiation of the reactor. It will also be affected by transient radiation. For this reason, it is not possible to efficiently analyze the irradiation deterioration and the like of the material using the irradiation temperature, the irradiation radiation amount, and the like as parameters from the test results.

On the other hand, as described above, after the operation of the reactor has reached the rated state, the shields 9a, 9a are rotated by the rotary shield 9b.
When b is opened and the sample 5 inside the sample holder 8 is exposed to radiation, the sample 5 inside the sample holder 8 can be irradiated only during the rated operation of the reactor, as shown in FIG. That is, the sample 5 can be irradiated with radiation only under certain irradiation conditions. Also, its irradiation pattern
The rotation of the rotary shield 9b by the motor 16 can be arbitrarily set, for example, as shown in FIG. FIG. 5 shows a modification of the shields 9a and 9b, in which the fixed shield 9a is formed over an angle of about 225 ° and the rotary shield 9b is formed over an angle of about 155 °. In this example, the fixed shield 9a
As a result, the directivity of the sample 5 with respect to the radiation increases.

[0020]

As described above, in the irradiation test capsule according to the present invention, the sample can be irradiated only under desired conditions without being affected by the transient radiation at the time of starting and stopping the reactor. At the same time, it is possible to arbitrarily set a radiation irradiation pattern on the sample. This makes it possible to perform a radiation irradiation test on the sample in various patterns under the desired irradiation conditions according to the purpose of the test, and to efficiently analyze the irradiation deterioration and the like of the material using the irradiation temperature and irradiation dose as parameters. You will be able to do well.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an example of a radiation irradiation test capsule according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an example of a graph showing the relationship between the output of a nuclear reactor and the irradiance of radiation applied to a sample.

FIG. 5 is a cross-sectional plan view showing another example of the radiation irradiation test capsule according to the present invention, which is cut at the same position as in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Centering member 3 Outer cylinder 5 Sample 7 Bearing 8 Sample holder 9a Fixed shield 9b Rotary shield

Continued on the front page (72) Inventor Hiroshi Kawamura 3607 Niibori, Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki Prefecture (72) Inventor Masaru Nakamichi 3607 Niibori, Narita-cho, Oarai-cho, Higashiibaraki-gun, Ibaraki Address Oarai Research Institute, Japan Atomic Energy Research Institute (56) References JP-B-45-15600 (JP, B1) JP-B-44-12638 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB Name) G21C 23/00 G21K 5/08

Claims (3)

(57) [Claims] 1. A sample to be tested by irradiation with radiation (5)
A sample holder (8) holding a sample (5) and a portion fixedly arranged around the sample holder (8) and having a side surface opened by a part of an angle in a radiation irradiation test capsule containing A fixed shield (9a) for shielding cylindrical radiation, and an open angle of the fixed shield (9a), which is rotatably disposed around the holder (8) concentrically with the fixed shield (9a). A radiation irradiation test comprising: a rotary shield (9b) for shielding a partial cylindrical radiation having a wider angle; and a rotating mechanism for rotating the rotary shield (9b) around its central axis. For capsule. 2. A sample holder (8), a fixed shield (9)
a) and an outer cylinder (3) covering the rotating shield (9b),
2. The radiation irradiation test capsule according to claim 1, wherein the rotary shield (9b) is supported so as to be rotatable around the central axis of the outer cylinder (3). 3. A centering member (1) for positioning a center of a sample holder (8) at a predetermined position is provided at a distal end portion of an outer cylinder (3).
The capsule for radiation irradiation test according to 4.