KR100511560B1 - Multi-purpose Cf-252 Neutron Source Handling Device - Google Patents

Abstract

The present invention is divided into a moving shield and a fixed shield so that the moving shield moves along with the neutron source capsule when the Cf-252 neutron source moves so that the operator can perform neutron irradiation test or exponential test while minimizing the radiation exposure of the operator. Neutron source handling apparatus.

In the neutron source handling apparatus of the present invention, the mounting hole 11 is inserted in the center and a plurality of irradiating holes 13 penetrate through the fixed shield 3, the mounting hole 11 is detachably inserted. The movement shield 5 which is to hold the source capsule 7 in the inner shaft hole 15, the source capsule 7 coupled to one end of the moving bar 17 inserted into the shaft hole 15, and the moving bar. An insertion hole 19 into which the 17 is inserted is formed, and the shielding cover 9 fitted into the mounting hole 11 of the fixed shield 3 is characterized in that it is configured.

Therefore, according to the present invention, there is little exposure of the operator, very easy to handle, and it is possible to safely and usefully perform neutron irradiation experiments or exponential experiments.

Description

Multi-purpose Cf-252 Neutron Source Handling Device

The present invention relates to a neutron source handling apparatus, and more particularly, the shield is divided into a mobile shield and a fixed shield, so that the mobile shield moves with the neutron source capsule during movement of the Cf-252 neutron source while minimizing the radiation exposure of the operator. A multipurpose Cf-252 neutron source handling device that enables neutron irradiation tests and protects neutron sources from moisture contact or impact.

In general, radioisotopes are used for many studies and experiments in various fields, such as the medical field for diagnosis and treatment using radiopharmaceuticals, industrial fields such as non-destructive testing, and agricultural field. As the field of application expands, the demand for radioisotopes is increasing.

By the way, when treating or manufacturing such radioisotopes in the form of radioactive radiation sources in a reactor, or transporting the manufactured radioactive sources out of the reactor in a container or using them for neutron irradiation tests, until now, the operator has been able to use the radioisotopes without special devices. Using a shield, a tung, and a mirror to protect the whole body, the neutron source is injected and dismantled, and thus there is a problem that can be exposed by a considerable amount of radiation generated from the radiation source.

As a countermeasure against this, for example, a container such as a radioisotope container disclosed in Korean Patent Application No. 10-1997-0012671 has been used for transporting a spun capsule.

This container is for safely transporting the radiated capsule, and as shown by reference numeral 200 in Figure 1, the cask body (210) for opening the upper and receiving the capsule 202 therein and the It consists of a container cover (cask cover) 220 to cover the opening of the container body (210).

The capsule hole 213 is formed in the center of the container body 210 so that the capsule 202 is accommodated inward, and the process water flowing in when the capsule 202 is introduced at the lower end of the capsule hole 213. A drainage passage 214 capable of draining is installed to penetrate to the outside. In addition, the upper end of the container body 210 is provided with a locking device 215 to lock the container lid 220 by fastening. Meanwhile, the container body 210 and the container lid 220 inject molten lead into stainless steel housings 212 and 222 forming the outer side of the container body 210 and the shield lid 220. It consists of a structure to form.

The radioactive isotope transport container 200 for the conventional hydrotransmission irradiating facility configured as described above is introduced into the capsule discharge chamber 300 closed by the shielding wall 301 and loaded with the capsule 202, as shown in FIG. The process is as follows.

First, the transport container 200 is mounted on the container transport vehicle 320, the capsule discharge chamber through the shield door 302 in the state in which the locking device 215 of the container body 210 and the container lid 220 is released ( 300). As such, the container transport vehicle 320 for transporting the container 200 to the capsule discharge chamber 300 once stops at the lower portion of the container lid handling apparatus 330. At this time, the finger 331 of the container lid handling device 330 is moved to the lower through the drive motor 332 to grab the handle 223 of the container lid 220 and transferred to the upper again to the container lid 220 Separate from the body 210.

The container transport vehicle 320 again transports the container body 210 to the lower part of the capsule discharger 310 to aim the capsule hole 213 of the container body 210 at the discharge port of the capsule discharger 310, and the radiation source. The built-in radiated capsule 202 is discharged to the capsule ejector 310 through a transfer facility. The capsule 202 discharged from the capsule ejector 310 is introduced into the capsule hole 213 of the container body 210, and the container transport vehicle 320 is a container lid handling device 330 in which the container lid 220 is separated. Will move to the bottom of the At this time, while the finger 331 of the container lid handling device 330 is lowered to cover the container lid 220 to the container body 210 to seal. Again, the transfer device transfers the transport container 200 to the outside through the shield door 302, and the transport container 200 is fastened to the locking device 215 and then transferred to the hot cell, which is a subsequent treatment facility.

As such, when the container 200 is used, work can be performed more effectively while preventing radiation exposure than the method of simply using a shield, but as described above, the container 200 can be transported or The use and handling procedures such as loading were complicated and cumbersome.

The present invention has been proposed to solve the problems of the conventional radiation source handling method, in particular the exponent decay coefficient (exponenital decay constant) indicating the degree of neutron flux attenuation using a Cf-252 neutron source When conducting experiments, Cf-252 neutron source can be safely injected into control rod guide tube of spent fuel assembly, and after disassembly, it can be safely disassembled and stored safely. Also, Cf-252 neutron source can be easily used for irradiation test or radiation. The purpose is to make the handling of Cf-252 neutron sources safe and convenient.

In order to achieve the above object, the present invention provides a fixed shield body in which a mounting hole is inserted in the center and a plurality of irradiation holes are penetrated to the side, and is detachably inserted into the mounting hole, and a moving shield body and shaft hole for storing the source capsule in the inner shaft hole. Provided is a neutron source handling device is formed of a source cap capsule is attached to one end of the moving bar is inserted into, and the insertion hole is inserted into the moving bar is inserted into the mounting hole of the fixed shield.

Hereinafter, an embodiment of a neutron source handling apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

The neutron source handling apparatus of the present invention is a device for use in a test facility after conducting an experiment for inducing nuclear fission by neutrons using a Cf-252 neutron source or irradiating with a Cf-252 neutron source. As schematically shown as 1, it is largely composed of a fixed shield (3), a moving shield (5), a source capsule (7), and a shield cover (9).

Here, the fixed shield 3 is an outer shield that forms the outer body of the handling apparatus as shown in Figs. 3 and 4, and has a cylindrical shape having a diameter of 60 cm and a height of 50 cm as a whole. In addition, a mounting hole 11 into which the moving shield 5 is inserted is inserted in the center portion of the shaft, and a hexagonal bolt portion of the radiation source capsule 7 is provided in the central portion of the bottom surface of the mounting hole 11 as shown in FIG. 5. A hexagon bolt groove 33 into which the 73 is inserted is inserted, and a shielding material made of a paraffin material is filled in the stainless case 25. The use of paraffin as a shielding material is because the specific gravity is 0.93 g / cm 3, which is lighter than water, and the hydrogen atomic ratio is 0.675, which is higher than that of water. It is supposed to be protected by state. In addition, the fixed shield 3 may be installed on the mobile cart 27 as shown in Figure 4 so that the installation position can be changed.

In addition, a plurality of irradiation holes 13 penetrate the side surface of the lower end of the fixed shield 3 to be used as a passage for loading the irradiation sample during the irradiation experiment using the source handling apparatus 1 of the present invention. Therefore, in other words, when the neutron source is being used for the exponential experiment or stored after the experiment, the irradiation hole stopper 21 is inserted into the irradiation hole 13 to maintain the shielding performance.

The exponential experiment here refers to an exponential decay factor that represents the extent to which the neutron flux decays as the distance between the two neutron sources (Cf-252, etc.) and neutron detectors are installed in the nuclear material (uranium, etc.) system. As an experiment to measure exponenital decay constant, it was used to measure nuclear critial buckling in the early stages of reactor development (1960s). Currently, the neutron source and the detector are respectively inserted in two control rod guide tubes of the fuel assembly (the guide tubes are empty outside the reactor and there are dozens of tubes in the assembly), and either one is fixed to the center (the center of the assembly lengthwise). If one is moved in the upper and lower axial direction of the center, it is used to measure the flux of the neutron source and to determine the exponential decay coefficient of the spent fuel assembly from the slope which is attenuated. It is used to determine the neutron effective multiplication factor, which is a measure of nuclear criticality safety assessment of nuclear facilities.

As such, in order to maintain the shielding performance of the fixed shield 3, the stopper 21 is composed of a case 35, a shield 37 and a flange 39, as shown in FIG. The case 35 is formed in a cup shape to accommodate the shield 37 therein and is surrounded by 2 mm thick SUS. In addition, the shield 37 is made of paraffin of the same material as the fixed shield 3, the flange portion 39 is coupled to the outer periphery of the outer end of the case 35 to a thickness of 10mm relatively thick irradiation hole 13 It is to prevent the exposure caused by the neutron coming out of the gap between the hole 21 and the irradiation hole and a bolt for detachably fixing the stopper 21 is fastened to the outer periphery. On the other hand, the screw groove 41 is mounted on the inner end of the case 35 detachably mounted to the container (not shown) for charging the test sample. Accordingly, the stopper 21 coupled to the charging container may serve as an insert used to insert the irradiated sample to the center where the hexagonal bolt groove 33 of the fixed shield 3 is formed.

The movable shield 5 detachably installed in the mounting hole 11 of the fixed shield 3 is a portion that shields the radiation from the capsule 7 while moving together when the neutron source capsule 7 moves. And a cylindrical shape having a diameter of 20 cm and a height of 20 cm, as shown in FIG. 4, a polyethylene made of hydrogen and carbon is used as a shielding material. Similarly, polyethylene has a specific gravity of 0.92 g / cm 3, which is lighter than water, and has a hydrogen atom ratio of 0.667, which is the same as water, and is widely used as a neutron shield because it is solid at room temperature.

On the central axis of the moving shield 5 is formed through the shaft hole 15 through which the moving bar 17 and the source capsule 7 coupled to the bottom of the moving bar 17 are inserted, as shown in FIGS. 7A and 7B. , The shaft hole 15 is reduced in diameter upward from the locking step 43 of the upper middle portion. In addition, as shown in the figure, the upper and lower edge portions of the movable shield 5 are chamfered so that the longitudinal section thereof is hexagonal, thereby minimizing the overall weight, thereby preventing damage to the screw fastening portion coupled to the movable bar 17 and the like, while maximizing the shield radius. It can be secured. In addition, as shown in FIG. 7B, a plurality of fastening holes 23 are formed on the upper surface of the moving shield 5 so as to couple bolts (not shown) connected to auxiliary ropes (not shown).

The neutron radiation source capsule 7 mounted and stored at the bottom of the shaft hole 15 of the moving shield 5 is coupled to the bottom of the moving bar 17, as shown schematically in FIG. 3, and as shown in FIG. 8. As described above, it is made of a storage container 71 in which the neutron source 31 is stored, and a connection lid 72 connected to the storage container 71 to weld the contact portion. The upper portion of the connecting lid 72 of the neutron source capsule 7 has a screw thread to enable the coupling of the moving bar 17, and the lower surface of the storage container 71 as shown in FIG. Hexagon bolt portion (73) fitted into the hex bolt groove (33) of the projecting.

The moving bar 17 coupled to the connection cap 72 and connected to the source capsule 7 is connected to the threaded hole 75 of the connection cap 72 at the bottom by an elongated rod 45 as shown in FIG. 9. A screw portion 46 to be fastened is formed to protrude, and a screw hole 47 coupled to the handles 50 and 81 is recessed at an upper end thereof.

The shield cover 9 coupled to the inlet of the mounting hole 11 to seal the mounting hole 11 of the fixed shield 3 with the movable shield 5 inserted therein is fixed shield 3 Sealing and fastening with four fixing clamps 29 provided on the upper surface of the, for this purpose the outer periphery placed on the movable shield 5 is in the form of a relatively thin flange. In addition, an insertion hole 19 into which the moving bar 17 is inserted is formed in the center of the bottom surface, and a ring 10 for connecting the lifting rope (not shown) is attached to the center of the upper surface for opening and closing.

And, the handle 50, which is coupled to the moving bar 17 to carry the moving shield 5 in the state where the shield cover 9 is opened, is more than the moving bar 17 as shown in FIG. Consists of a bar-shaped connection bar 51 and an insertion bar 61. Here, the connection bar 51 has a hook 55 for carrying hook hook attached to the upper end and a screw hole 58 formed at the lower end thereof, and at least two flat gripping grooves on the outer circumferential surface adjacent to the hook 55 ( 57) is cut out to facilitate gripping by the spanner. In addition, the insertion bar 61 has a threaded portion 63 that is screwed to the threaded hole 58 of the connecting bar 51 at the upper end and a screwed portion screwed to the screw hole 47 at the lower bar 17. 65 is formed.

As another form of the handle 50, the handle shown by reference numeral 81 in FIG. 11 is attached to the hook hook for carrying hook hook at the top and screwed to the moving bar 17 screw hole 47 at the bottom The thread portion 85 is formed in a relatively short unimodal shape.

Now, the operation of the Cf-252 neutron source handling apparatus according to the embodiment of the present invention configured as described above is as follows.

The neutron source capsule 7 and the moving bar 17 do not need to be uncoupled except in special cases because the experiment, storage and irradiation experiments in a combined state. In the case of normal storage, as described above, the fixed shield is closed and the clamp is maintained. When conducting an exponential experiment, open the lid and combine the insertion bar (6 mm in diameter and 5 m in length) with the connecting bar (6 mm in diameter and 4.65 m in length, with a tap to hang the rope for the crane hook at the top). do. Then, they are fastened to the moving bar by fastening them with the crane. At this time, one person is holding the spanner in the groove 57 in the lower portion of the connecting bar, the other worker is fastening the screw by rotating the fixed shield (3), that is, the entire device placed on the cart 27.

After the coupling is completed, if you use the crane to lift the handle, the neutron source capsule exits the hexagonal groove and moves upward to reach the position where the diameter of the shaft hole is reduced to about 7 mm, and the neutron source has reached the center of the moving shield. When the upper portion of the neutron source capsule is caught on the locking jaw of the mobile shield. Accordingly, since the neutron source capsule and the moving shield are positioned at the center of the neutron source moving shield when moving in the air, the same shielding is achieved in all directions.

When the handle is pulled up by the crane, the mobile shield moves out of the fixed shield with the neutron source in the center and moves to the storage pool of the post-irradiation test facility containing the spent fuel assembly (the storage pool height is 12 m and the water height is 10 m). m, 4 m high spent fuel assembly spanning 4 m from the bottom in water). Subsequently, it moves to the location of spent fuel assembly and lowers the handle to approach the water level of the pool. Further down, the mobile shield floats on the water, and the neutron source capsule descends toward the control rod guide of the assembly (there is no problem because the water is still a good shield for neutrons, so it is still shielded out of the mobile shield). . Finally, the neutron source capsule (diameter 9.19 mm) is inserted into the control rod guide tube (guide tube diameter of ring 1 nuclear fuel: 12.827 mm, guide tube diameter of ring 2 nuclear fuel: 11.05 mm). It is not easy to insert because it is not very large compared to the diameter of the neutron war capsule, it is almost impossible to move the shield to the field of view if the water does not float. The moving shield is at the water level (10 m from the bottom), the top of the guide tube is 4 m from the bottom, and only 20 cm in diameter of the moving shield, so it almost obscures the subject's field of vision during injection. However, in case of a special case where the mobile shield should be pulled to the upper part, two threads are placed on the upper part of the mobile shield, and the two strapped screws can be combined to pull the mobile shield upward. .

Disassembly and storage after the experiment should be done in the reverse order. When irradiating with a neutron source, open the lid of the fixed shield and move the handle to the moving bar (17) to pull the neutron source capsule upwards so that the neutron source is at the middle height of the fixed shield, and then remove the stopper plug. . Subsequently, the sample is mounted on a suitably prepared sample handling device, and the sample handling device is fastened and screwed together at the irradiation stopper, and the combined material is inserted so that the sample is positioned on the hexagonal groove, and then the neutron source capsule is lowered. After approaching the sample, close the lid and perform the irradiation experiment. After the neutron irradiation is done, the work is reversed.

As a result of using this device in actual exponential experiment, there is little exposure of worker, it is very easy to handle, and it can be used safely and usefully in neutron investigation experiment.

In addition, as described above, since there is almost no exposure by the neutron source in the process of combining the components of the neutron source handle, the neutron source can be experimented by moving to the necessary position with time and can be safely stored.

1 is a cross-sectional view showing a conventional radioisotope container.

Figure 2 is a schematic diagram showing a state in which a conventional radioisotope container is introduced into the capsule discharge chamber to load the capsule.

Figure 3 is a schematic front cross-sectional view of the Cf-252 neutron source handling apparatus according to the present invention.

Figure 4 is a front sectional view of the Cf-252 neutron source handling apparatus according to the present invention.

5 is a detailed view of portion A of FIG. 4;

6 is a half cross-sectional view of the irradiation hole stopper shown in FIG. 4.

FIG. 7A is a half cross-sectional view of the moving shield shown in FIG. 4. FIG.

FIG. 7B is a plan view of the moving shield shown in FIG. 4. FIG.

8 is an exploded cross-sectional view of the radiation source capsule shown in FIG. 4.

9 is a plan view of the moving bar shown in FIG.

10 is an exploded view of a handle used for carrying a moving shield.

11 is an exploded view of a handle of yet another form used for carrying a moving shield.

Explanation of symbols on main parts of drawing

1: source handling device 3: fixed shield

5: moving shielding body 7: source capsule

9: shield cover 11: mounting holes

13: investigator 15: shaft

17: moving bar 19: insertion hole

21: investigator plug 31: neutron sailor

33: Hex Bolt Groove

Claims (7)

In the device for safely handling the source capsule (7) in which the radiation source is stored, A fixed shield (3) having a mounting hole (11) in the center portion and at least one irradiation hole (13) penetrating into the mounting hole (11); A movable shield 5 detachably inserted into the mounting hole 11 and configured to store the source capsule 7 in the inner shaft hole 15; A movement bar 17 having one end coupled to the source capsule 7 and inserted into the shaft hole 15 provided in the movement shield 5; And An insertion hole 19 into which the movable bar 17 is inserted is formed, and a shielding cover 9 fitted into the mounting hole 11 of the fixed shielding body 3; Neutron source handling device, characterized in that consisting of. The method of claim 1, A case 35 having a cup-shaped outer body, and having a screw groove 41 formed therein for detachably mounting the irradiation test sample charging container at an inner end thereof; A shielding body (37) filled in the case (35); And A flange portion 39 coupled to an outer end of the case 35 and detachably screwed to the irradiation hole 13 of the fixed shield 3; Neutron source handling device characterized in that it further comprises a stopper (21) consisting of. The method of claim 1, The moving shield 5 is a neutron source, characterized in that the shaft hole 15 is formed through the center portion, the shaft hole 15 is reduced in diameter upward from the locking jaw 43 of the upper middle portion. Handling device. The method of claim 1, The moving shield (5) is a neutron source handling device, characterized in that the upper and lower edges are chamfered. The method of claim 1, A screw hole 47 is formed at an upper end of the movable bar 17, and the movable bar 17 has a hook 55 for carrying hook hook attached thereto at an upper end thereof, and a threaded hole 58 formed at the lower end thereof. And a rod-shaped connection bar 51 in which the gripping groove 57 is cut and adjacent to the ring 55, and a screw portion 63 screwed to the screw hole 58 is formed at the upper end thereof. Neutron source handling device, characterized in that moved by the handle 50 made of a rod-shaped insertion bar 61 is formed with a threaded portion 65 is screwed to the screw hole 47 of the moving bar 17 . The method of claim 1, A screw hole 47 is formed at the upper end of the movable bar 17, and the movable bar 17 has a hook 83 for a hook hook attached to the upper end of the movable bar 17, and a lower portion of the movable bar 17 at the lower end of the movable bar 17. The neutron source handling apparatus, characterized in that moved by the rod-shaped handle (81) formed with a threaded portion (85) screwed to the thread hole (47). The method according to any one of claims 1 to 4, The fixed shield (3) and the moving shield (5) is a neutron source handling device, characterized in that the filling with a shielding material of polyethylene or paraffin material.