JP6466778B2 - Radioactive material storage container - Google Patents

Description

  The present invention relates to a radioactive substance storage container in which a heat transfer member and a block-like neutron shield are provided in a space between an inner cylinder and an outer cylinder.

  For example, in the radioactive substance storage container of Patent Document 1, in order to remove the decay heat of the radioactive substance stored in the inner cylinder to the outside, a heat transfer member having an L-shaped cross section is formed in the space between the inner cylinder and the outer cylinder. (Thermal conductors) are arranged at predetermined intervals. A resin block-shaped neutron shield is provided between two adjacent heat transfer members. Thus, by making the neutron shield into a block shape, the neutron shield can be prepared prior to the assembly work of the radioactive substance storage container. This eliminates the need for on-site resin casting at the time of assembly, thereby improving the production efficiency of the radioactive substance storage container.

JP 9-49898 A

  By the way, in patent document 1, since the heat-transfer member is welded to the outer cylinder, a welding distortion generate | occur | produces in a heat-transfer member with the heat at the time of welding. As a result, if the heat transfer member is deformed and a gap is generated between the heat transfer member and the neutron shield, radiation streaming may occur. Therefore, a countermeasure for preventing a gap between the heat transfer member and the neutron shield due to welding strain has been demanded.

  In view of the above problems, an object of the present invention is to suppress the occurrence of a gap between the heat transfer member and the neutron shield during welding of the heat transfer member.

  In order to achieve the above object, the present invention provides an inner cylinder in which a radioactive substance is housed, an outer cylinder that is provided outside the inner cylinder with a space between the inner cylinder and the outer cylinder. A space includes a plurality of heat transfer members provided in the circumferential direction in contact with the inner cylinder and the outer cylinder, and a block-shaped neutron shield provided between the two adjacent heat transfer members. In the radioactive substance storage container, the heat transfer member extends in a circumferential direction from a connecting portion extending over the inner cylinder and the outer cylinder, and at least one end of the connecting portion on the inner cylinder side and the outer cylinder side. And a welded portion welded to the inner tube or the outer tube is formed at the tip of the projecting portion.

  In the present invention, the heat transfer member provided in the space between the inner cylinder and the outer cylinder includes a connecting portion extending over the inner cylinder and the outer tube, and a protrusion protruding in the circumferential direction from an end portion on at least one side of the connecting portion. Part. And since the front-end | tip part of a protrusion part is welded to an inner cylinder or an outer cylinder, a welding location can be kept away from a connection part, the influence of the heat | fever by welding hardly reaches a connection part, and a deformation | transformation of a connection part by welding distortion is carried out. Can be suppressed. For this reason, it can arrange | position in the state closely_contact | adhered to the connection part, and it becomes possible to suppress that a clearance gap arises between a heat-transfer member and a neutron shield at the time of welding of a heat-transfer member.

It is a longitudinal cross-sectional view of the radioactive substance storage container concerning this embodiment. It is sectional drawing in II-II of FIG. It is a partial perspective view of a heat-transfer member. It is a schematic diagram which shows the manufacturing process of a radioactive substance storage container. It is a schematic diagram which shows the detail of the manufacturing process of a division body unit.

  An embodiment of a radioactive substance storage container according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a radioactive substance storage container according to this embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG.

  The radioactive substance storage container 1 has a shape that extends in the axial direction as a whole, and includes a cylindrical container body 10 with a bottom, in which a radioactive substance (not shown) is stored, and a bolt or the like at an upper opening of the container body 10. And the lid portion 11 fixed by the At both ends in the axial direction of the container body 10, trunnions 12 for gripping a transfer crane or the like when the radioactive substance storage container 1 is moved are provided in the circumferential direction at a predetermined interval (for example, an interval of 90 degrees). ing.

  The container body 10 includes a bottomed cylindrical inner cylinder 13 having an internal space for storing a radioactive substance, and a cylindrical outer cylinder 14 provided on the outer side of the inner cylinder 13 with a space therebetween. In the space formed between the inner cylinder 13 and the outer cylinder 14, a plurality of heat transfer members 15 and a neutron shield 16 are disposed as shown in FIG. According to the radioactive substance storage container 1 having such a configuration, the decay heat of the stored radioactive substance is removed to the outside through the heat transfer member 15, and the radiation (mainly neutron) is removed from the neutron shield. 16 is shielded.

  Details of each part will be described. The inner cylinder 13 is formed in a bottomed cylindrical shape by welding a bottom plate 18 to a lower end portion of a cylindrical tubular member 17. In order to ensure the gamma ray shielding function and the structural strength, both the cylindrical member 17 and the bottom plate 18 are made of, for example, carbon steel. Below the bottom plate 18, a neutron shielding material 19 made of resin, rubber, or the like is provided in a state of being covered with a cover material 20. The outer cylinder 14 is a cylindrical thin plate member made of, for example, carbon steel or stainless steel, and covers the neutron shield 16. The lid portion 11 includes a primary lid 21 that closes the upper opening of the inner cylinder 13 and a secondary lid 22 that is provided above the primary lid 21. A neutron shielding material 23 and a cover material 24 that covers the neutron shielding material 23 are provided outside the secondary lid 22. The primary lid 21 is made of, for example, carbon steel or stainless steel, and the neutron shielding material 23 is mainly made of resin, rubber, or the like.

  As shown in FIG. 2, the heat transfer member 15 includes a connecting portion 15 a extending substantially along the radial direction over the inner cylinder 13 and the outer cylinder 14, and a circumferential direction (see FIG. 2) from the end of the connecting portion 15 a on the outer cylinder 14 side. 2 and a second projecting portion 15c projecting in the circumferential direction (right side in FIG. 2) from the end portion of the connecting portion 15a on the inner cylinder 13 side. It is Z-shaped. A plurality of such heat transfer members 15 are provided in an annular space between the inner cylinder 13 and the outer cylinder 14 in a state of being arranged in the circumferential direction.

  In the heat transfer member 15, the distal end portion of the projecting portion 15 b is welded to the inner peripheral surface of the outer cylinder 14 to be a welded portion 15 d, and the second projecting portion 15 c is in pressure contact with the outer peripheral surface of the inner cylinder 13 (tubular material 17). Is done. Thereby, the decay heat generated in the inner cylinder 13 is transmitted to the inner cylinder 13, the heat transfer member 15, and the outer cylinder 14 to be removed to the outside. The material constituting the heat transfer member 15 is suitably copper or copper alloy having high thermal conductivity, but iron, steel, aluminum, aluminum alloy, or the like can be used in addition to this.

  A block-shaped neutron shield 16 made of a material containing a large amount of hydrogen such as resin or rubber is disposed between two adjacent heat transfer members 15. In order to prevent radiation streaming, these two members are arranged in close contact as much as possible so that there is no gap between the side surface of the neutron shield 16 and the connecting portion 15a of the heat transfer member 15. In the present embodiment, the neutron shield 16 is constituted by one block. However, for convenience during assembly, the neutron shield 16 may be divided into a plurality of portions in the circumferential direction or the axial direction.

  FIG. 3 is a partial perspective view of the heat transfer member. As shown in FIG. 3, the protrusion 15b of the heat transfer member 15 is provided with a plurality of slits 15e formed from the distal end side to the proximal end side to the front of the connecting portion 15a at predetermined intervals in the axial direction. Yes. Moreover, although the protrusion part 15b is welded to the internal peripheral surface of the outer cylinder 14 as mentioned above, it is welded intermittently in an axial direction. As a result, as shown in FIG. 3, a plurality of welds 15d are formed at predetermined intervals in the axial direction.

  Next, the manufacturing method of the radioactive substance storage container 1 is demonstrated. FIG. 4 is a schematic diagram illustrating a manufacturing process of the radioactive substance storage container, and FIG. 5 is a schematic diagram illustrating details of a manufacturing process of the divided body unit.

  First, as shown in FIG. 4A, two outer cylinder divided bodies 14a each having a halved shape in which the outer cylinder 14 is divided into two in the circumferential direction are prepared. Such an outer cylinder divided body 14a is manufactured by bending a steel plate, for example. Subsequently, the heat transfer member 15 is fixed by welding to the outer cylinder divided body 14a, and the neutron shield 16 is provided between the two heat transfer members 15 adjacent to each other. As a result, as shown in FIG. 4B, a divided unit 25 in which the outer cylinder divided body 14a, the heat transfer member 15, and the neutron shield 16 are integrated is manufactured.

  Here, the details of the procedure for manufacturing the divided body unit 25 will be described with reference to FIG. First, the first heat transfer member 15 is attached to the outer cylinder divided body 14a by welding the tip 15d of the protrusion 15b of the first heat transfer member 15 to the inner peripheral surface of the outer cylinder divided body 14a. Fix (see FIG. 5A). Subsequently, the neutron shield 16 is arranged on the side where the protruding portion 15b of the heat transfer member 15 protrudes, and the second one on the opposite side of the first heat transfer member 15 with respect to the neutron shield 16. The heat transfer member 15 is disposed (see FIG. 5B).

  At this time, the neutron shield 16 is sandwiched between the first and second heat transfer members 15, and both side surfaces of the neutron shield 16 are connected to the connecting portions 15 a of the first and second heat transfer members 15. It arrange | positions so that each may closely_contact | adhere. Further, the second protrusions 15c of the two heat transfer members 15 adjacent to each other are substantially continuous in the circumferential direction so that the outer peripheral surface of the inner cylinder 13 is covered with almost no gap by the second protrusions 15c. Be placed. Such an arrangement can prevent radiation streaming.

  Thereafter, the tip 15d of the protrusion 15b of the second heat transfer member 15 is welded to the inner peripheral surface of the outer cylinder divided body 14a, so that the second heat transfer member 15 is attached to the outer cylinder divided body 14a. It fixes (refer FIG.5 (c)). As a result, the neutron shield 16 is assembled between the first and second heat transfer members 15. And as shown in FIG.5 (d), the division | segmentation body unit 25 is manufactured by repeating the above-mentioned process.

  Returning to FIG. 4, the description will be continued. When two divided body units 25 can be prepared, the inner cylinder 13 manufactured in a separate process is prepared (see FIG. 4C). Then, the two divided body units 25 are fitted on the outside of the inner cylinder 13 so that the second projecting portion 15 c of the heat transfer member 15 contacts the outer peripheral surface of the inner cylinder 13. In this state, the end faces in the circumferential direction of the two outer cylinder divided bodies 14 a are welded together, thereby connecting the two divided body units 25 to each other around the inner cylinder 13.

  As a result, as shown in FIG. 4D, the radioactive material in which a plurality of heat transfer members 15 and neutron shields 16 are alternately provided in the circumferential direction in the annular space between the inner cylinder 13 and the outer cylinder 14. The storage container 1 is completed. At this time, the second projecting portion 15c of the heat transfer member 15 can be reliably brought into pressure contact with the inner cylinder 13 by contraction during welding of the outer cylinder divided body 14a. In addition, the method of connecting the two division | segmentation body units 25 is not restricted to welding, Other methods, such as bolt fixation, may be used.

(effect)
In this embodiment, the heat transfer member 15 provided in the space between the inner cylinder 13 and the outer cylinder 14 includes a connecting portion 15a extending over the inner cylinder 13 and the outer cylinder 14, and an end on at least one side of the connecting portion 15a. And a protruding portion 15b protruding in the circumferential direction from the portion (in this embodiment, the end portion on the outer cylinder 14 side). And since the front-end | tip part of the protrusion part 15b is welded, the welding part 15d can be kept away from the connection part 15a, the influence of the heat by welding hardly reaches the connection part 15a, and suppresses a deformation | transformation of the connection part 15a by welding distortion. be able to. For this reason, the neutron shield 16 can be disposed in close contact with the connecting portion 15 a, and the occurrence of a gap between the heat transfer member 15 and the neutron shield 16 during welding of the heat transfer member 15 is suppressed. Is possible. As a result, it is possible to reliably prevent radiation streaming.

  In the present embodiment, the welded portion 15d is intermittently formed in the axial direction of the inner cylinder 13 or the outer cylinder 14. As described above, by performing the welding intermittently rather than continuously, the deformation of the heat transfer member 15 due to the welding distortion can be suppressed.

  Moreover, in this embodiment, the protrusion part 15b has the slit 15e formed toward the base end side from the front end side. By providing such a slit 15e, thermal expansion in the axial direction (longitudinal direction) of the heat transfer member 15 generated during welding is absorbed by the slit 15e, and deformation of the heat transfer member 15 can be suppressed.

  In the present embodiment, a protrusion 15 b is provided at the end of the heat transfer member 15 on the outer cylinder 14 side, and the tip of the protrusion 15 b is welded to the outer cylinder 14. Thus, by welding the heat transfer member 15 to the outer cylinder 14 instead of the inner cylinder 13, the production of the inner cylinder 13 proceeds in parallel during the operation of welding the heat transfer member 15 to the outer cylinder 14. Therefore, the production efficiency of the radioactive substance storage container 1 can be improved.

  Moreover, in this embodiment, the 2nd protrusion part 15c which protrudes in the circumferential direction is provided in the edge part by the side of the inner cylinder 13 of the heat-transfer member 15, and the 2nd protrusion part 15c contacts the inner cylinder 13. It is configured. By providing such a second protrusion 15c, it is possible to prevent the neutron shield 16 disposed between the two adjacent heat transfer members 15 from falling off radially inward, and the assembly work Becomes easy. Moreover, since the heat transfer member 15 and the outer peripheral surface of the inner cylinder 13 can be more reliably brought into contact with each other over a wide area, the heat removal performance can be improved.

  Moreover, in this embodiment, the 2nd protrusion part 15c protrudes in the opposite direction of the protrusion part 15b in the circumferential direction. For this reason, when welding the protrusion part 15b, the 2nd protrusion part 15c does not become a hindrance of welding work, and can perform a welding work smoothly.

  Further, if the neutron shield 16 is made of a rubber-based material, the neutron shield 16 is elastically deformed flexibly so that a gap is not easily formed between the heat transfer member 15 and the neutron shield 16. Streaming can be suppressed more effectively.

(Other embodiments)
The present invention is not limited to the above embodiment, and the elements of the above embodiment can be appropriately combined or variously modified without departing from the spirit of the present invention.

  For example, in the above embodiment, the protrusion 15b provided on the outer cylinder 14 side of the heat transfer member 15 is welded to the outer cylinder 14, but in addition to or instead of this, The second projecting portion 15 c provided on the cylinder 13 side may be welded to the inner cylinder 13. Further, the second projecting portion 15c may be closely attached to the inner cylinder 13 by fixing the second projecting portion 15c to the inner cylinder 13 with a bolt or the like.

  Moreover, in the said embodiment, the protrusion parts 15b and 15c which protrude in a mutually different direction from the both ends of the heat-transfer member 15 (provided that the cross-sectional shape is Z-shaped) are provided at both ends. The protruding portion may protrude in the same direction, and the cross-sectional shape may be a U shape. Moreover, it is not essential to provide the protrusions 15b and 15c at both ends of the heat transfer member 15, and the protrusion may be provided only on the side to be welded, and the cross-sectional shape may be L-shaped.

  Moreover, in the said embodiment, although welding of the heat-transfer member 15 was intermittently performed in the axial direction and the slit 15e was provided in the protrusion part 15b, the conditions which can suppress a deformation | transformation of the heat-transfer member 15 are provided. The welding may be performed continuously or the slit 15e may be omitted.

  Moreover, in the said embodiment, although the outer cylinder 14 shall be comprised by connecting the two outer cylinder division bodies 14a, the number of the outer cylinder division bodies 14a is not limited to two. Furthermore, the outer cylinder 14 may be manufactured from one cylindrical member instead of manufacturing the outer cylinder 14 from the plurality of outer cylinder divided bodies 14a.

  Moreover, in the said embodiment, although the inner cylinder 13 and the outer cylinder 14 were made into the cylindrical shape, these are good also as a polygonal cylinder shape.

DESCRIPTION OF SYMBOLS 1 Radioactive material storage container 13 Inner cylinder 14 Outer cylinder 15 Heat-transfer member 15a Connection part 15b Projection part 15c 2nd projection part 15d Welding part 15e Slit 16 Neutron shield

Claims (5)

An inner cylinder in which radioactive material is stored;
An outer cylinder provided on the outer side of the inner cylinder with a space therebetween;
A plurality of heat transfer members provided in the circumferential direction in a state in contact with the inner cylinder and the outer cylinder in a space between the inner cylinder and the outer cylinder;
A block-shaped neutron shield provided between two heat transfer members adjacent to each other;
In a radioactive substance storage container comprising:
The heat transfer member is
A connecting portion extending over the inner cylinder and the outer cylinder;
A protrusion protruding from an end portion of the front Symbol outer cylinder side of the connecting portion in the circumferential direction,
A second projecting portion projecting in a circumferential direction from an end portion of the connecting portion on the inner cylinder side;
Have
The tip portion of the protruding portion and welds are welded before Symbol outer cylinder is formed,
The second protrusion is in contact with the inner cylinder;
The second protrusions of the two heat transfer members adjacent to each other are arranged so as to be continuous in the circumferential direction.
A radioactive substance storage container.   The radioactive substance storage container according to claim 1, wherein the welded portion is formed intermittently in the axial direction of the inner cylinder or the outer cylinder.   The radioactive substance storage container according to claim 1, wherein the protrusion has a slit formed from the distal end side toward the proximal end side. The radioactive substance storage container according to any one of claims 1 to 3, wherein the second projecting portion projects in a direction opposite to the projecting portion in the circumferential direction. The radioactive substance storage container according to any one of claims 1 to 4 , wherein the neutron shield is made of a rubber-based material.

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