JPH01197700A - Photographic cassette loading/unloading device - Google Patents

Abstract

PURPOSE:To simultaneously execute putting in and out of a cassette for photographing and shielding of a photographing chamber by providing an auxiliary shielding body which shields the radiations leaking from a photographing chamber and 1st and 2nd moving means which move a plug shielding body. CONSTITUTION:Transfer foil is first inserted into a cassette for loading of the transfer foil. An upper shutter 65 is then opened upon confirmation that the plug shielding body 50 exists in a standby position. The cassette for loading is then lowered and the transfer foil is dropped in a cassette 58 for photographing. An upper shutter 64 is closed and the shielding body 50 is moved from the standby position to a photographing position. The cassette 58 is brought near to a sample capsule by a pantagraph 56 while the positional relation is checked by the television monitor equipment in the 1st photographing chamber 12. The sample capsule is photographed by projecting the neutrons of a nuclear reactor thereto. The cassette 58 is thereafter returned to the initial position. The shielding body 50 is fitted into the recess of the auxiliary cassette 42 to shut off the photographing chamber 12 from the outside. Since the putting in and out of the cassette 58 and the shielding of the photographing chamber 12 are simultaneously executed by the shielding body 50 in such a manner, the danger of exposure is entirely eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a neutron radiography equipment that uses neutron irradiation to image radioactive materials such as spent nuclear fuel, and uses a transfer foil that is activated by neutron irradiation for imaging. This invention relates to a photographing cassette loading/unloading device which is stored in a photographic cassette and which is taken in and out of a photographing room.

[Conventional technology] During the development stage of a new type of nuclear fuel, nuclear fuel is used experimentally in a research reactor at a level exceeding its rating, and the deterioration of the fuel is reported to be 7! ! (cracks, etc.) must be investigated using radiographic imaging.

By the way, when photographing spent fuel, ordinary film cannot be used because the subject itself is a powerful radiation source. For this reason, so-called neutron radiography technology is used to photograph highly radioactive substances. In the neutron radiography technique, a subject is irradiated with neutrons, and the neutrons that have passed through the subject are received by a dysprosium (Dy) transfer foil and a transmitted image is transferred. The transfer foil that has been irradiated with neutrons is temporarily activated, so a film is brought into close contact with the activated transfer foil, and the transmitted image of the subject is transferred to the film. That is, as shown in the formula below, +65D
β generated when y (half-life is approximately 2.33 hours) decays
Expose the film with a line.

+64Dy (stable) + n-169Dy (radioactive nucleus) +65Dy-* 16'HO (holmium) + β-ray In conventional neutron radiography technology, the Dy transfer foil is stored in a photographic cassette, and the cassette is placed inside the subject (inside the cask). The device is immersed in a reactor pool together with the stored spent fuel (spent fuel), removes water between the reactor and the subject, and irradiates the subject with neutrons emitted from the reactor. Thereafter, the activated transfer foil is taken out of the cassette, a film is brought into close contact with the transfer foil, and the image of the β rays emitted from the transfer foil is transferred onto the film.

According to another conventional technique, spent fuel is stored in a dedicated cask having a special window, a cassette containing transfer foil is inserted through the window of the cask, and a photograph is taken inside the cask.

[Problem to be solved by the inventionffi] However, when taking pictures inside a nuclear reactor pool, the shooting location is narrow, so the operability is not good, it takes a long time to take pictures, and it is difficult to take pictures reliably. It is extremely difficult. Also, when shooting using a special cask,
The problem was that there was an increased risk of exposure to radiation during filming.

The present invention has been made in view of the above circumstances, and is an imaging cassette for neutron radiography equipment that can safely, reliably, and quickly photograph objects containing radioactive materials, and has excellent operability. The purpose is to provide access and exit devices.

[Means for Solving the Problems] A photographing cassette loading/unloading device according to the present invention stores a transfer foil that becomes radioactive when irradiated with neutrons in a photographing cassette, and uses a shielding member to photograph a subject. A photography cassette loading/unloading device for loading and unloading a photography cassette into and out of a photography room surrounded by A plug shield is provided to cover the opening and block radiation leaking from the imaging room when the transfer foil is installed in the imaging cassette; It has an auxiliary shield for shielding radiation leaking from the imaging room when going out into the room, and a first moving means for moving the plug shield between the opening and the imaging room, and the plug shield is The camera is characterized by comprising a second moving means for holding the photographing cassette and bringing it close to the subject. In this case, the first moving means is provided with a pair of rail members for guiding the plug shield and inside the photographing room along the rail members, and moves the plug shield from the opening to the photographing room. It is preferable to have a ball screw member and a flexible cable that bends through the auxiliary shield and is connected to the ball screw member, and the second moving means includes a pantograph,
A gear shaft connected to each end of the pantograph and provided so as to pass through the plug shield, and a gear meshed with the gear shaft are provided, and the gear shaft is provided with a gear shaft that is connected to each end of the pantograph and is provided to pass through the plug shield. It is preferred to have a supplementary gearbox, an elongated gear meshed with one of the gears in the gearbox, and a flexible cable bent through the auxiliary shield and connected to the elongated gear.

[Function] In the photographing cassette loading/unloading device according to the present invention, when a subject is placed at a predetermined position in the photographing room, the transfer foil is stored in the photographing cassette while the opening is closed with a plug shield. When the transfer foil is stored in the photographing cassette, the opening is closed by the auxiliary shielding body, and the first moving means moves the plug shielding body to the photographing room so that the cassette is behind the subject in the neutron irradiation direction. . Next, the photographing cassette is brought close to the subject by the second moving means, neutrons are irradiated to the subject, and after photographing, the photographing cassette is removed from the subject and returned to the opening together with the plug shield,
While blocking the opening with a plug shield, the transfer foil in the photographic cassette is dropped into the transfer cassette and collected, the transfer foil is brought into close contact with the film in the transfer cassette, and the image of the subject is transferred onto the film.

[Embodiments] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view from above of an imaging cassette loading/unloading device according to an embodiment of the present invention, and FIG. 2 is a sectional schematic diagram of a neutron radiography facility equipped with the imaging cassette loading/unloading device viewed from the side. 3 is a schematic cross-sectional view of the neutron radiography equipment viewed from above, and FIG. 4 is a schematic cross-sectional view of the neutron radiography equipment viewed from the neutron irradiation direction. A neutron radiography facility 10 is installed on the side of a research nuclear reactor (not shown), and neutrons are irradiated toward the facility 10 when the beam shutter of the reactor is opened. The radiography equipment 10 is entirely covered with a lead block of a predetermined thickness, a boron-containing polyethylene plate and a polyethylene plate are pasted at appropriate places inside the block, and the neutron entrance is provided with a bismuth shutter 24 that can be opened and closed. A beam catcher 16 is provided at the rear of the neutron beam path. Inside the equipment 10, a partition wall 1
3 into two rooms, a first and second photography room 12.14. A passage 15 is formed approximately in the center of the partition wall 13, and when the shutter 26 is raised and lowered by the lifting device 25, the passage 15 opens and closes. That is, when the first photography room 12 is used, the shutter 26
On the other hand, when the second imaging room 14 is used, the shutter 26 is in an open state, and the neutron beam is introduced into the second imaging room 14 through the passage 15. ing. A hatch 18.20 is provided on the ceiling of the first and second photography rooms 12.14, respectively, and objects are loaded into the respective photography rooms via the hatches 18.20. Further, a manhole 22 is provided on the side wall of the second photography room 14, and a manhole 22 is provided on the side wall of the second photography room 14.
Workers can enter and exit the facility. A passage 19 for loading a sample (object) is formed in the ceiling hatch 18, and a spent fuel rod (sample capsule) as an object is loaded onto a sample holder 30 below the first photography room 12 through the passage 19. It is set to be placed on. The holder 30 is mounted on a table, and is moved up and down and rotated by two electric motors 28 and 31. Also, holder 3
0 has a chuck for gripping the sample and is connected to a high-pressure air supply source. This allows the sample placed on the holder 30 to be gripped. A pair of upper and lower rails 70 and 71 of the cassette loading/unloading device 40 are connected to the first photographing room 1.
It penetrates one side wall of 2 and is provided from side wall to side wall. Note that, as shown in FIG. 4, a collimator 33 is provided in the path of the neutron beam (not shown in FIGS. 2 and 3).

As shown in FIG. 1, the transfer foil loading portion (the portion protruding from the side wall of IIFL 0) of the cassette loading/unloading device 40 is surrounded by an auxiliary shield 42 made of lead. The body 42 is provided with a maintenance shield door 44, which is opened and closed by a handle 46.
Flexible cables 43 and 45 respectively connected to handles 48 and 52 are connected to the auxiliary shield 42 so as to be bent.
penetrates through. A flexible cable 43 of the handle 48 is connected to a screw 49 for moving the plug shield, while a flexible cable 45 of the handle 52 is connected to an elongated gear shaft 54 for cassette delivery.

As shown in FIG. 5, an upper shutter 64 and a lower shutter 65 are provided at the upper and lower parts of the auxiliary shield 42, respectively, and each shutter 64, 65 is attached to a handle 66.
．． 67, respectively. The plug shield 50 is slidably mounted along rails 70.71 from side wall to side wall of the first photography room 12. This plug shield 50 has a gearbox 7 in its front part.
2, and a cassette 58 for storing transfer foil is provided at the rear thereof. The plug shield 50 is a vertically elongated rectangular body having three steps, and when in the standby position, the step fits into a recess 62 surrounded by the auxiliary shield 42, so that the photography room is not exposed to the outside. It is now blocked. Auxiliary shield 4
A cassette mounting stand 67 for loading transfer foil is provided on the upper part of the transfer foil 2, and communicates with the recess 62 via an upper shutter 66. That is, when the plug shield 50 is in the standby position (inside the recess 62), the upper shutter 66 is opened and the mounting base 67 is opened.
When the handle 68 is turned, a transfer foil loading cassette (not shown) in the mounting base 67 is lowered, and this
The transfer foil is connected to the No. 0 cassette 58 so that the transfer foil falls from the loading cassette into the photographing cassette 58. On the other hand, spur gears 74 and 76 are housed in the gear box 72 of the plug shield 50, and the gears 74 are meshed with both the elongated gear shaft 54 and the gear 76, respectively, and when the gear shaft 54 rotates, A gear 76 is configured to rotate via a gear 74. A pair of bevel gears 81.82 are provided on the gear shaft 78 of the gear 76 so that the gear surfaces thereof are oriented in the same direction, and these bevel gears 81.8
2 is a screw shaft 86.2 that is orthogonal to the gear shaft 78.
88 bevel gears 83 and 84, respectively.

The gear shaft 78 passes through a portion of the plug shield 50, and the gear box 72 compensates for the shielding deficiency due to this penetration. A pair of screw shafts 86.
Nuts 87° and 89 are screwed into each of 88,
When the shafts 86 and 88 rotate, the nuts 87 and 89 move up and down. Further, a ball screw nut 73 is attached to the lower part of the plug shield 50, and this ball screw nut 73 is screwed onto the ball screw 49 so that the entire plug shield 50 is transported. .

As shown in FIGS. 7 and 1, the plug shield 50 has a plate member 51 for supporting a pantograph, and screw shafts 86 and 88 are respectively fixed to the lower part of this plate member 51. The lower proximal end portions of a pair of pantographs 56 are rotatably provided at each of 87 and 89 via a horizontal shaft 57. In addition, each pantograph 5
6 is attached to the upper part of the plate member 51 via a horizontal shaft 57. The pair of arms of the pantograph 56 intersect approximately in the middle of their lengths, and the upper proximal end is connected to the lower free end and the lower proximal end is connected to the upper free end through a central horizontal axis 57. They are set to be replaced. A cassette 58 is attached to the free end of the pantograph 56, and the lower free end is connected to move up and down a slide shaft 90 via a nut 91 and a horizontal shaft 57, respectively.
The link is configured such that the pair of nuts 91 on the free end side move up and down in response to the vertical movement of the nuts 87, 89 on the base end side. That is, when the cassette 58 is in the standby position, the nut 87.8 on the pantograph base end side
9 are located below the shafts 86, 88, nuts 87.
As 89 moves upward, cassette 58 moves forward to approach sample capsule 60 (containing spent fuel). In this case, the transfer foil 59 to be housed in the cassette 58 is a dysprosium foil having a thickness of approximately 0.1111%, a width of approximately 115 ml1s, and a length of approximately 4321 mm. The approximate size of the first photography room 12 is that its depth (length in the neutron irradiation direction) is 170 On+m and its width is 12 On+m.
60Ill1m, its height is 2200mm. Incidentally, in the shielding wall surrounding the first photographing room, the thickness of the ship wall is about 270 mm, and the thickness of the boron-containing polyethylene plate is about 200 mm.

Next, the operation of the embodiment will be explained.

Make sure the reactor beam shutter is closed. A shutter 26 in the equipment 10 is closed to prevent neutrons, gamma rays, etc. from leaking from the first imaging room 12 to the second imaging room 14. The sample capsule 60 containing the spent fuel is
When it is loaded into the first photographing room 12 through the passage 19 of the ceiling hatch 18 and gripped by the chuck of the sample holder 30,
The holder 30 is raised to the neutron beam irradiation height. The transfer foil 59 is loaded into the transfer foil loading cassette of the mounting table 67. After confirming that the plug shield 5o is in the standby position (the position of the recess 62), turn the handle 66 to open the upper shutter 64, then turn the handle 68 to lower the transfer foil loading cassette, and then Photography cassette 58
Connect to.

The lower lid of the loading cassette is opened and the transfer foil is dropped from the loading cassette into the photographing cassette 58. 1nd dollar 68
After turning the loading cassette in the opposite direction to raise the loading cassette, the upper shutter 66 is closed. Next, turn the handle 48 to move the plug shield 50 from the standby position to the photographing position, and align the center of the cassette 58 with the center of the neutron beam irradiation area (the alignment of the cassette center and the beam center axis is (This is done using a stopper (not shown) on the body movement rail). A television monitor g1 (not shown) in the first photographing room 12 turns the handle 52 to extend the pantograph 56 while checking the positional relationship between the cassette 58 and the sample capsule 60, and moves the cassette 58 into the sample capsule 60. bring them closer. When the cassette 58 is sent to the photographing position, the beam shutter of the nuclear reactor is opened to irradiate the sample capsule with neutrons for a predetermined period of time, and the sample is photographed.

When the beam shutter of the reactor is closed and the photographing is finished, the pantograph 56 is retracted by turning the handle 52 in the opposite direction.
Return the cassette 58 to its initial position.

Next, turn the handle 48 in the opposite direction to remove the plug shield 5.
0 is fitted into the recess 62 of the auxiliary shield 42 to isolate the photographing room 12 from the outside. A film is attached to the top lid of a vacuum cassette of a transfer foil recovery device (not shown) (which is entirely covered with a shield), and the thus prepared transfer foil recovery device is installed below the auxiliary shield 42. Next, the handle 69
Turn the handle 66 to open the lower shutter 65, turn the handle 66 to open the upper shutter 64, and turn the handle 68 to load the loading cassette (not shown) into the photographing cassette 5.
Connect to 8. Pull the transfer foil removal lever (not shown),
Drop the transfer foil inside the photography cassette onto the collection device,
The transfer foil is guided by a number of rollers and guided into a vacuum cassette. When the transfer foil is dropped, the loading cassette is raised,
The upper shutter 64 and lower shutter 65 are closed. On the other hand, when the transfer foil guided by multiple rollers arrives above the vacuum cassette and stops in a horizontal position, the guide rollers are opened left and right and the transfer foil is dropped onto the vacuum cassette. The vacuum cassette is installed with its lid open, so
When the vacuum cassette is moved forward with the stand, the lid comes off the stopper, the vacuum cassette is closed, and the transfer foil is stored in the vacuum cassette. Next, the shield door with a glass window of the transfer foil storage shield is opened, the vacuum cassette is taken out, and the cassette is connected to a vacuum pump. By reducing the pressure inside the vacuum cassette, the film and the activated transfer foil are brought closer to each other, and a transmitted image of the subject (image formed by the intensity of β-ray radiation) is created.
Transfer to film.

According to the above embodiment, since a ball screw is employed as the movement mechanism for the plug shield, the plug shield can be moved accurately while withstanding a high load.

Further, according to the above embodiment, the flexible cable is curved and passed through the auxiliary shielding body, and the shielding loss caused by the gear shaft penetrating the plug shielding body is compensated for by the gearbox, so that the shielding performance can be improved. can. Moreover, the handle is easy to operate and has good operability.

[Effects of the Invention] According to the present invention, the plug shielding body allows the imaging cassette to be taken in and out and the imaging room to be shielded at the same time.

Therefore, in the neutron radiography equipment, the risk of exposure to radiation can be almost completely eliminated, and the object can be photographed safely, reliably, and quickly, and photographed more efficiently than before.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view from above of an imaging cassette loading/unloading device according to an embodiment of the present invention, and FIG. 2 is a sectional schematic diagram of a neutron radiography facility equipped with the imaging cassette loading/unloading device viewed from the side. Figure 3 is a schematic cross-sectional view of the neutron radiography equipment viewed from above, Figure 4 is a schematic cross-sectional view of the neutron radiography equipment viewed from the neutron irradiation direction, and Figure 5
The figure is an enlarged sectional view of the imaging cassette loading/unloading device viewed from the neutron irradiation direction, Figure 6 is a perspective view schematically showing the drive section of the photography cassette loading/unloading device, and Figure 7 is the cassette of the photography cassette loading/unloading device. It is a side view showing a sending mechanism. 10; Neutron radiography equipment, 12, 14; Photography room, 18, 20; Hutch, 24, 26. Shutter, 30;
Sample holder, 33; Collimator, 40; Cassette loading/unloading device, 42; Auxiliary shield, 46.48.52, 66.68
, 69; handle, 49; ball screw, 5
0; Plug shield, 54; Long gear shaft, 56; Pantograph, 58; Photographic case/steer, 59; Transfer foil,
60; sample capsule, 70, 71; rail, 72; gear box, 73; ball screw nut, 74.76; spur gear, 78; through gear shaft, 81.82.8B, 84
．． Bevel gear, 86.88; screw, 87.89; nut. Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) For photography, in which a transfer foil that becomes radioactive when irradiated with neutrons is stored in a photography cassette, and is taken in and out of a photography room surrounded by a shield through an opening in order to photograph a subject. The cassette loading/unloading device is provided with a mechanism for holding the photographing cassette and is movable from the opening of the shield to the photographing room, and when the transfer foil is installed in the photographing cassette. A plug shield that blocks the opening and blocks radiation leaking from the imaging room, and an auxiliary plug that is installed to cover the opening and shields radiation leaking from the imaging room when the plug shield is out in the imaging room. a shield, and a first moving means for moving the plug shield between the opening and the photographing room, the plug shield comprising:
A photographing cassette loading/unloading device comprising a second moving means for holding the photographing cassette and bringing it close to a subject. (2) The first moving means includes a pair of rail members for guiding the plug shield, and a ball that is provided in the photography room along the rail members and moves the plug shield from the opening to the photography room. 2. The imaging cassette inlet/outer device according to claim 1, further comprising a screw member and a flexible cable that bends through the auxiliary shield and is connected to the ball screw member. (3) The second moving means includes a pantograph, a gear shaft connected to each end of the pantograph and provided so as to pass through the plug shield, and a gear meshed with the gear shaft. , a gearbox that compensates for the lack of shielding of the plug shield penetration part by the gear shaft; a long gear meshed with one of the gears in the gearbox;
2. The photographing cassette inlet/output device according to claim 1, further comprising a flexible cable that bends and passes through the auxiliary shield and is connected to a long gear.