JPH04131798A - Capsule transporting device - Google Patents

Abstract

PURPOSE:To take out a capsule certainly from an irradiation cylinder without generating vibration on the capsule by putting a capsule passage in communication with small paths through parallel slits, wherein the range of controllable rate of flow is set wide for the time of individual taking-out. CONSTITUTION:The gap between an outer cylinder 12 and inner cylinder 14 is divided by partitions 17 into small paths 6a, 6b, 6c. These small paths are in communication with a capsule passage 7 through No.1, No.2, and No.3 parallel slits 21. Among them 21, the No.1 and No.2 parallel slits are so formed in the inner cylinder 14 that the bottoms of slits are in line with the bottom of a capsule 2 in its stop position. Locating the capsule 2 in this position precludes it from vibrating even though impact is applied given by the spout water from the slits 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capsule transportation device for transporting a sample capsule to a radiation irradiation position and taking it out in an irradiation facility for activation analysis using a research nuclear reactor.

[Prior Art] In the field of nuclear energy, studies are being conducted to examine changes in chemical and physical properties of various samples by irradiating them with neutrons, and to produce radioisotopes. In such activation analysis technology, in order to avoid worker exposure to radiation,
The analysis area and neutron irradiation area are set apart from each other,
Samples will be transported in capsules between both areas. In the neutron irradiation area, the irradiation cylinder or nuclear reactor is loaded, and the sample capsule is transported to this via a transport path. This irradiation cylinder is fixed at a predetermined position within the nuclear reactor, and has the role of allowing a plurality of capsules to temporarily stay there and receiving neutron irradiation. After opening and closing the shielding shutter to irradiate the sample with a predetermined amount of neutrons, a predetermined flow rate of fluid is supplied into the irradiation tube, the capsule is taken out from the irradiation tube, and the capsule is transported to the analysis area via the transportation path where it is analyzed. do.

The irradiation tube consists of a double tube consisting of an outer tube and an inner tube.
The seat at the bottom of the inner cylinder is made porous to allow the inner cylinder and outer cylinder to communicate with each other. That is, when fluid is supplied to the inner tube from the side of the capsule loading port, a downward flow toward the receiving seat is generated, and the capsule arrives in the irradiation tube. On the other hand, when fluid is supplied to the outer cylinder, the fluid is ejected from the hole in the seat, creating an upward flow within the inner cylinder, and the capsule escapes from the irradiation cylinder.

Such an irradiation tube cannot be raised or lowered within the reactor, and the capsule is irradiated only at the bottom seat. For this reason, the sample is irradiated at a position where the neutron flux density is maximum in the axial neutron flux distribution, and when low-intensity irradiation is required, there is a problem that the radiation dose rate of the sample becomes excessive.

[Problems to be Solved by the Invention] Therefore, in order to vary the irradiation intensity, a plurality of capsules were stacked in series in an irradiation cylinder in multiple stages, and the neutron irradiation intensity was improved so that the higher the capsule is located, the lower the neutron irradiation intensity.

That is, a hole is made at a suitable position in the middle of the inner cylinder of the irradiation tube, and fluid is injected into the inner cylinder through the hole in the middle, so that the capsules stacked in multiple stages in series can be taken out individually from the irradiation tube.

However, in the above-mentioned irradiation tube, when capsules are taken out individually, the range of flow rate distribution between upward flow and downward flow is narrow, and it is very difficult to control this. It is preferable that the controllable flow rate range during individual extraction be as wide as possible.

If the flow rate distribution becomes unbalanced, the capsule below the hole may also be taken out, which is an inconvenience.

Furthermore, when taking out individual capsules, the capsules above and below the hole vibrate violently, giving impact to the capsules or the inner cylinder, shortening the life of the inner cylinder.

This invention was made in view of the above circumstances, and has a wide range of controllable flow rate during individual extraction.
It is an object of the present invention to provide a capsule transportation device that can reliably take out a capsule from an irradiation tube without causing vibration to the capsule.

[Means for Solving the Problems] A capsule transportation device according to the present invention includes an outer cylinder, an inner cylinder inserted into the outer cylinder and forming a passage for the capsule, and a space between the inner cylinder and the outer cylinder. It has a partition for partitioning the formed gap into a plurality of small passages, and a fluid supply means for supplying fluid to each of these small passages, and a parallel slit hole communicating with the capsule passage and each of the small passages. The capsule is formed in the inner cylinder, and each of these parallel slit holes is located near the bottom of the capsule at the capsule stop position.

The length of the parallel slit hole is preferably 1/2 or less of the capsule length, and when transporting a lightweight capsule weighing 500 grams or less, it should be about 215 times the capsule length. desirable.

Further, the width of the parallel slit hole is preferably at least 1/2 or less of the capsule diameter, and most preferably about 1/4. In this case, increasing the width of the slit hole to slow down the flow rate is advantageous for vibration suppression, but there is a certain limit to increasing the width because the capsule tends to get caught in the slit hole.

In addition, the relative positions of the parallel slit hole and the stop capsule are preferably such that the lower end of the parallel slit hole does not protrude below the lower end of the stop capsule, and the lower end of the stop capsule is aligned with the lower end of the parallel slit hole. It is most desirable to form parallel slit holes.

Furthermore, if the distance between the holes is made small and the holes are placed too close to each other, the parts sandwiched between the holes may lack strength and be easily damaged, and an accident may occur where the capsule gets stuck in the damaged and enlarged hole. , it is necessary to separate the two with an appropriate distance. On the other hand, if the distance between the holes is increased and the holes are separated too far from each other, the momentum of the upward flow will be weakened and the capsule will not be able to rise quickly. Therefore,
The distance between the parallel slit holes is preferably determined in consideration of the balance with the capsule diameter, and is most preferably set to the same dimension as the width of the hole.

[Function] In the capsule transport device according to the present invention, the capsule passage and the small passage are communicated with each other by the parallel slit holes, so when fluid is supplied to the small passage, the fluid flows into the capsule passage through the parallel slit hole. flows in, this is split up and down, and the capsule rises with the upward flow. In this case, since the parallel slit holes are arranged near the lower end of the stop capsule, the upward flow reliably lifts the upper capsule, and the downward flow flows so as to press the lower capsule toward the catch.

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

The irradiation tube 11 of the capsule transportation device 1F10 is installed almost vertically in the research nuclear reactor 50, so that the sample capsules 2 in the irradiation tube 11 are irradiated with neutrons generated in the reactor core. The irradiation tube 11 is installed at a position where the lowest part thereof is closest to the reactor core, and the irradiation amount is maximum at the lowest part and gradually decreases as it moves upward.

A capsule passage 7 communicates with the upper part of the irradiation tube 11. The capsule passage 7 communicates with a loading/unloading port of a capsule loading/unloading device 70 and further communicates with a fluid supply source 80 via a pump 60 and a flow path 47 . The fluid supply source 80 stores water as a carrier fluid. In addition, the pump 60
is a switching pump that can switch between the suction side and the discharge side to reverse flow.

Four channels 9a, 9b, 9c, 9 are provided at the bottom of the irradiation tube 11.
d are connected to each other. Each channel 9a9b, 9c, 9
d communicate with the pump 60 via valves 61 and 6263.64, respectively, and further with the fluid supply source 8 via the flow path 46.
Connected to 0.

Note that the flow path 9d and the flow path 47 communicate with each other through a bypass flow path 42. A valve 65 is provided in this bypass passage 42.
Or is provided.

As shown in FIGS. 1 and 3, a branching member 8 is attached to the upper part of the irradiation tube 11, and a flow path 9a.

9b and 9c each communicate with the outer cylinder 12, while the capsule passage 7 communicates with the inner cylinder 14. The inner cylinder 14 is supported by the outer cylinder 12 by a support member 16 so that the gap between the inner cylinder 14 and the outer cylinder 12 is uniform.

The inner cylinder 14 is made of stainless steel, has a length of 1 m or more, and has an inner diameter slightly larger than the diameter of the capsule 2. Incidentally, the inner diameter of the inner cylinder 14 is 36.5 to 3
7 mm, while the diameter of capsule 2 is 3211 mm.
Ill. In addition, capsule 2 has a length of 150 f.
The empty weight of f1lls is 180 grams, and the weight when loaded with a sample is approximately 500 grams.

The catch seat 18 is fitted into the lower end of the inner cylinder 14, and the capsule 2
collides with the catch seat 18 and stops. As shown in FIG. 7, a large number of holes 18a are formed in the seat 18, and the carrier fluid can flow through the inside and outside of the inner part 14 through the holes 18a.

As shown in FIGS. 4 to 6, the outer cylinder 12 and the inner cylinder 14
The gap between the small passage 6a,
It is divided into three equal parts 6b and 6c. As shown in FIG. 4, the small passage 6a is formed in the middle of the inner cylinder 14.
It communicates with the capsule passage 7 through a parallel slit hole 21 . As shown in FIG. 5, the small passage 6b is connected to the inner cylinder 14.
It communicates with the capsule passage 7 through a second parallel slit hole 21 formed in the middle of the capsule. As shown in Figure 6,
The small passage 6c communicates with the capsule passage 7 through a third parallel slit hole 21 formed in the middle of the inner cylinder 14.

As shown in FIG. 8, the first and second parallel slit holes 21 are formed in the inner tube 14 so that the lower ends of the parallel slit holes 21 are aligned with the lower end of the capsule 2 at the capsule stop position. When the capsule 2 is placed in such a position, the capsule 2 will not vibrate even if it receives the impact of water jetted from the parallel slit hole 21. Note that the third parallel slit hole 21 is formed in the middle of the inner cylinder 14 near the catch seat 18. Incidentally, each parallel slit hole 21 has a length of 6
0111111, the width is 81, and the mutual distance between the holes is 8 mm. In this case, if the width of the slit hole 21 becomes too narrow, vibrations will occur in the capsule even at a low flow rate. on the other hand,
If the width of the slit hole 21 is too wide, the head of the capsule 2 will easily get caught in the slit hole 21. Therefore, the optimum width of the parallel slit hole 21 varies depending on the size and weight of the capsule 2, but it is usually desirable to set it to about 1/4 of the diameter of the capsule 2.

Next, individual extraction of capsules will be explained with reference to FIGS. 9 to 12.

Three capsules 2 are loaded one after another into the capsule passage 7 from the loading port of the device 70, water is supplied from the device 70 side toward the irradiation tube 11 side, and the capsules 2 are transported to the irradiation tube 11. As shown in FIG. 9, three capsules 2 are stacked in series, and the shielding shutter is opened to irradiate them with neutrons for a predetermined period of time.

After the irradiation is completed, the pump 60 is switched between the suction side and the discharge side to supply water to the first channel 9a. At this time, the flow rate is set to 2 per hour.
．． It is controlled within the range of 3 to s, 'ym'. Water flows into the capsule passage 7 from the parallel slit hole 21 of the small passage 6a.

This slit hole 21 is located at the boundary between the top capsule 2 and the middle capsule 2, and the water flowing through the hole 21 is divided into upper and lower parts and flows there. The upward flow passes through the side of the topmost capsule 2 and passes through the passage 7 at the top of the inner cylinder 14.
, and is carried out to the outside of the irradiation tube 11.

As shown in FIG. 10, the rising branch flow creates a pressure difference in which the pressure on the upper side is lower than the pressure on the lower side, and this pressure difference causes the topmost capsule 2 to rise.

On the other hand, when the downward flow passes by the middle and lower capsules 2, it removes heat from each capsule 2 that has generated heat due to neutron irradiation, and passes through the gap between the seats 18 of the inner cylinder 14 to the second capsule 2. and flows into the third small passages 6b, 6c, and returns to the water supply source 80 through the flow passages 9b, 9c.

When taking out the middle capsule 2, water is supplied to the second flow path 9b. At this time, the flow rate is controlled within the range of 2.4 to 9.8 m'/hour. The water flows through the parallel slit hole 21 of the small passage 6b.
It flows into the capsule passage 7 via. This hole 21 is located at the boundary between the middle capsule 2 and the bottom capsule 2, and the water flowing in from the hole 21 is divided into upper and lower parts and flows there.

The upward flow passes through the side of the middle capsule 2, passes through the guide tube at the top of the inner cylinder, and is carried out to the outside of the irradiation tube 11.

As shown in FIG. 11, the middle capsule 2 rises along with the rising branch flow and is taken out from the irradiation tube 11. On the other hand, the downward flow cools the lower capsule 2 and flows through the gap between the seat 18 of the inner cylinder 14 and the first and third small passages 6a, 6c.
and returns to the water supply source 80 through channels 9a and 9c.

Note that even when the two capsules 2 in the uppermost and middle stages are taken out at the same time, the same flow rate control range as above can be achieved.

When taking out the lowest capsule 2, use the third flow path 9C.
Water is sent to At this time, the flow rate is 2.4 to 9.6 m'/hour.
control within the range of Water flows into the capsule passage 7 through the parallel slit hole 21 of the small passage 6c. This hole 21 is located near the lower end of the lowermost capsule 2, and the water flowing through the hole 21 is divided into upper and lower portions and flows there. The upward flow passes through the side of the lower capsule 2, passes through the capsule passage 7, and is carried out to the outside of the irradiation tube 11.

As shown in FIG. 12, the lowermost capsule 2 rises due to the rising branch flow and is taken out from the irradiation tube 11. In addition,
By appropriately adjusting the flow rate, it is also possible to take out three capsules 2 at the top, middle, and bottom tier at the same time.

As a comparative example, instead of the parallel slit hole 21, two types of single holes (width 24I x length 25IIms width 2
4m1IX length 30mIg) under the same conditions. As a result, there is no vibration and
1 out of 3 capsules without getting caught
The flow rate control range in which each individual sample can be taken out is 3.5% per hour.
7-5.1 m' and 3.6-5.8 m3 per hour. This is a very narrow range compared to the case of the above embodiment, and it has been found that this is not practical.

[Effects of the Invention] According to the capsule transportation device of the present invention, one or two capsules can be easily taken out individually from a plurality of capsules without finely adjusting the flow rate. In other words, the range of controllable flow rate during individual extraction is wide (
, the capsule can be reliably taken out from the irradiation tube without causing any vibration to the capsule.

Moreover, by employing parallel ribbed holes, the capsule transportation device of the present invention can expand the usable range of flow rate distribution when individual capsules are taken out compared to the conventional method. Furthermore, since the opening area is reduced, the strength of the inner cylinder is improved, resulting in a longer life.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an irradiation tube used in a capsule transportation device according to an embodiment of the present invention, FIG. 2 is an overall schematic diagram of the capsule transportation device, and FIG. 3 is a plan view showing the irradiation tube viewed from above. 4 to 7 are cross-sectional views of various parts of the irradiation tube, and FIG. 8 is a partially enlarged view of the inner tube to explain the relative positional relationship between the parallel slit hole and the stop capsule. 9 is a schematic cross-sectional view showing the irradiation tube, and FIGS. 10 to 12 are schematic cross-sectional views showing a part of the irradiation tube. 2...Capsule, 6a, 6b, 6c...Small passage, 7
... Capsule passage, 10 ... Capsule transport device, 1
1... Irradiation tube, 12... Outer tube, 14... Inner tube, 17
... Partition, 18... Seat, 21... Parallel slit hole, 50... Nuclear reactor, 60... Pump, 70...
Capsule loading and unloading device, 80... water supply source

Claims (1)

[Claims] an outer cylinder, an inner cylinder that is inserted into the outer cylinder and forms a passage for the capsule, a partition that partitions a gap formed between the inner cylinder and the outer cylinder into a plurality of small passages, and each of these small passages. a fluid supply means for supplying fluid to each of the inner cylinders, parallel slit holes communicating with the capsule passage and each of the small passages are formed in the inner cylinder, and each of the parallel slit holes is connected to a lower part of the capsule at the capsule stop position. A capsule transport device characterized by being located nearby.