JP4492728B2 - Shielding structure - Google Patents

Description

  The present invention relates to a shielding structure used when inspecting and repairing equipment such as a pipe installed near a storage tank for storing radioactive waste.

  A storage tank for storing low-level radioactive waste is installed in the facility of the nuclear power plant. This storage tank is installed in a room composed of thick concrete walls having a thick floor and ceiling and surrounding side walls, and leakage of radiation to the outside is prevented. In addition, when radioactive waste is sent from the outside and stored in a storage tank, the room containing the storage tank has facilities such as piping and valves for supplying radioactive waste to the storage tank. It is laid. Usually, these facilities such as piping and valves are laid along the indoor side wall at a predetermined height from the floor surface due to the relationship with the storage tank.

Equipment such as piping and valves are regularly inspected and repaired or replaced as necessary. Since this inspection / repair is performed by the staff members entering the room, the radiation shielding effect between the inspected equipment and the staff members is excellent prior to the inspection / repair in order to minimize the exposure amount of the staff members. A shielding plate made of a lead plate is installed. This shielding plate is also provided in the storage tank. In the conventional installation of the shielding plate of the storage tank part, the support structure is welded to the upper part of the storage tank, and the shield support plate is supported by the welded support structure, or the support structure is assembled around the storage tank, The shield plate is supported by the assembled support structure.
JP-A 61-187699

  However, the conventional installation of the shielding plate of the storage tank portion requires welding work or requires assembly work of the support structure around the storage tank. There is a problem of increasing the number, and there is a long-awaited realization of a shielding structure that can further reduce the work time.

  This invention is made | formed in view of the situation mentioned above, and it aims at providing the shielding structure which can assemble the support structure for supporting a shielding board efficiently in a short time.

  In order to achieve the above object, according to the present invention, as a first solution, a central member placed at the center of the upper surface of a storage tank for storing radioactive waste, and a peripheral portion of the storage tank radially from the central member A plurality of foundation members that are mounted on the upper surface of the storage tank with a predetermined distance from each other, and are provided at locations located at the peripheral edge of the storage tank of each foundation member, and project upward A plurality of second mountings each having an opening to be inserted into each of the first mounting rods and the adjacent first mounting rods at both ends, and projecting upward at a predetermined distance from each other at the intermediate portion A support member that connects a plurality of connecting members having a bar, a plurality of standing bars inserted into each first mounting bar, and an intermediate part of each foundation member and an intermediate part of each vertical bar And spanned between the upper parts of adjacent standing bars Several horizontal bars, a plurality of first shielding plates for shielding radiation provided so that the upper end side is locked to the horizontal bar and the lower end side reaches the upper surface position of the storage tank, and the opening is made into the first mounting rod or A plurality of second shielding plates for shielding radiation provided to be inserted into the second mounting rod so that the upper end side is supported and the lower end side hangs down a predetermined length along the side surface of the storage tank; Adopt means.

  As a second solving means, a means is adopted in which, in the first means, the first shielding plate is attached to the horizontal bar using a hook.

  As a third solving means, a means is adopted in which, in the first or second means, the first shielding plate is configured to be foldable.

  As a fourth solving means, in the first or second means, a means is adopted in which the second shielding plate is configured to be foldable.

According to the present invention, the support structure that supports the first shielding plate and the second shielding plate is mounted on the central portion of the upper surface of the storage tank, and the first attachment connected to the central member. A plurality of base members having a bar, a plurality of connecting members having a second mounting bar connected between adjacent base members, and a plurality of standing members inserted into the first mounting bar and the second mounting bar Because it is composed of a standing bar, a support member that connects the foundation member and the standing bar, and a plurality of horizontal bars that are spanned and fixed between adjacent standing bars, it stores radioactive waste. It can be assembled in a very short time on the upper surface of the storage tank. Therefore, the exposure amount of the worker can be reduced.
In addition, when the hook is provided on the first shielding plate, the first shielding plate can be easily attached to the horizontal bar, and the first shielding plate and the second shielding plate can be folded. Sometimes it is easy to carry in and store.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view of a shielding structure according to the present embodiment, and FIG. 2 is a side view. The shielding structure is for shielding radiation of a storage tank that stores low-level radioactive waste in a nuclear power plant.

  In each of these figures, reference numerals T1 and T2 denote steel storage tanks for storing low-level radioactive wastes, and in a tank chamber R constructed hermetically by a thick concrete wall C exceeding 1 m. They are arranged in parallel at a predetermined interval. Reference numeral E denotes an entrance / exit, which is used for entrance / exit of a person such as an attendant or a worker in / from the tank chamber R and taking in / out each member to be described later, and is formed in an opening having a minimum size. Yes. In the tank chamber R, the entrance E is blocked by concrete having the same height as the storage tanks T1 and T2. Therefore, radiation does not leak out of the tank chamber R. In addition, E shown with the dashed-two dotted line in FIG. 2 has shown that the entrance / exit is provided in the wall C before this figure.

  The storage tanks T1 and T2 are used as storage tanks for storing wastes of powder ion exchange resin used for purifying water in nuclear power plants. These storage tanks T1 and T2 are configured so that the used powder ion exchange resin can be received in the form of a slurry containing water via a pipe (not shown).

Therefore, in these storage tanks T1 and T2, the powder ion exchange resin is deposited in the lower portion, and a water layer is formed thereon. For this reason, the radiation emitted from the storage tanks T1 and T2 has a property of decreasing with respect to the upper side of the storage tanks T1 and T2 because the formed water layer attenuates the radiation (such as “shielding”). Yes.
In addition, although not shown in the figure, facilities such as pipes and valves to be inspected and repaired are arranged in the vicinity of the upper surface of the storage tanks T1 and T2 on the side wall in the tank chamber R.

  Reference numerals B and B are scaffold members provided on the upper portions of the storage tanks T1 and T2, and F is a frame body provided in the tank chamber R. These are used for assembly and removal of the shielding structure, Used when checking and repairing equipment such as pipes. Since these members are not directly related to the shielding structure, further explanation is omitted.

  Reference symbol a is an upper shielding portion provided above the upper surfaces of the storage tanks T1 and T2, and reference symbol b is a lower shielding portion provided below the upper surfaces of the storage tanks T1 and T2. Since the upper shielding part a and the lower shielding part b provided in the storage tanks T1 and T2 have the same configuration, the following description will be made using the upper shielding part a and the lower shielding part b provided in the storage tank T1.

  FIG. 3 is an enlarged cross-sectional view taken along line AA of FIG. 4A is a perspective view of the first shielding plate, FIG. 4B is a perspective view of the second shielding plate, and FIG. 5 is an enlarged left side view of FIG. With reference to these drawings, the above-described upper shielding part a and lower shielding part b will be described.

  The central member 1 is made of a flat plate made of steel formed in a donut shape, and is placed at the center of the upper surface of the storage tank T1. A plurality of base members 2 that extend radially from the periphery of the central member 1 to the peripheral edge of the storage tank T1 and that are placed on the upper surface of the storage tank T1 at a predetermined equal interval from each other are provided. Yes. The base member 2 is made of a long steel plate. The base member 2 is bent downward at a right angle at the peripheral edge of the storage tank T1, and is bent upward at a right angle on the central member 1 side. Yes.

  The end of each base member 2 on the side of the central member 1 and the central member 1 are connected via a distance adjusting mechanism 2a including a screw rod and a hand-turnable nut that is screwed to the screw rod. Yes. Therefore, the base member 2 can be fixed without adjusting the base member 2 on the upper surface of the storage tank T1 by adjusting the distance adjusting mechanism 2a.

  The first mounting bar 3 is made of a steel bar, and is slightly inward from the upper part of the portion of the base member 2 that contacts the peripheral edge of the storage tank T1, that is, the portion bent downward at a right angle of the base member 2. A predetermined length is provided on the upper part of the inserted portion so as to protrude upward. The connection between the first mounting rod 3 and the base member 2 is fixed in advance by welding.

  The connecting member 4 is made of a long steel plate having openings on both end sides to be inserted into the adjacent first mounting rods 3, 3, and protrudes upward at predetermined intermediate intervals from each other in the middle part. The second mounting rod 5 made of a plurality of (three in the illustrated example) steel rods is provided. The connection between the connecting member 4 and the second mounting rod 5 is fixed in advance by welding.

  The standing bar 6 is made of a steel pipe material having an inner diameter that can be easily inserted into and removed from the first mounting bar 3 provided on the base member 2 and has a predetermined length. This length is determined by the shielding height of the upper shielding part a.

  The support member 7 is provided so as to connect a substantially middle part of the base member 2 and a substantially middle part of the standing bar 6, and is provided so that the standing bar 6 can be stably fixed in a substantially vertical shape. ing. The support member 7 is made of a pipe material having a predetermined length made of steel, and female threads are provided on the inner diameters at both ends thereof. In addition, a substantially intermediate portion of the base member 2 is provided with a connecting portion 6 a provided with a bar screw that can be screwed into a female screw provided on the support member 7. A connecting portion 2b having a bar screw that can be screwed into a female screw provided on the support member 7 is provided. Therefore, the standing bar 6 can be easily erected vertically by adjusting the connecting portions 6a and 2b.

  The horizontal bar 8 is made of a steel pipe material, and is constructed so as to be bridged between the upper portions of the adjacent standing bars 6 and 6 and fixed by the U-shaped metal fitting 9. Accordingly, the standing bars 6, 6... Are fixed to each other by the horizontal bar 8, and the standing condition of the entire standing bars 6, 6,.

  The first shielding plate a1 hits a member constituting the upper shielding portion a, and has a vertically long rectangular shape as shown in FIG. 4A. And it has the hook 10 on both sides of the upper part, respectively, These hooks 10 and 10 are comprised so that it can latch to the horizontal bar 8. FIG. The vertical length of the first shielding plate a1 is determined to be the shielding height of the upper shielding portion a, and the horizontal length is plural (four in the illustrated example). The first shielding plate a1 is determined so that it can be laid between the adjacent standing rods 6 and 6 without interruption. In addition, the first shielding plate a1 has a plurality of substantially square lead plate materials (three in the illustrated example) arranged in a vertical direction in the campus bag, and can be bent between the respective plate materials for easy storage and transportation. It is devised to become. The first shielding plate a1 can be composed of a single lead plate material between the adjacent standing rods 6 and 6, but a plurality of lead plate materials as described above from the viewpoint of storage and transportation. It is preferable to comprise.

  The 2nd shielding board b1 hits the member which comprises the lower shielding part b, and as shown in (b) of FIG. 4, is exhibiting the oblong rectangle of the vertically long predetermined thickness. The upper central portion has an opening 11 of a predetermined size, and the opening 11 can be inserted into the first mounting rod 3 or the second mounting rod 5 and locked. ing.

  The vertical length of the second shielding plate b1 is determined to be the shielding height of the lower shielding portion b, and the horizontal length is plural (four in the illustrated example). The second shield plate b1 is determined so that it can be laid between the adjacent standing bars 6 and 6 without interruption. The second shielding plate b1 is formed by inserting a plurality of substantially square lead plate materials (four in the illustrated example) in the campus bag in a vertical direction in the campus bag so that it can be bent between the respective plate materials. Further, the sheet material is devised so that it can be easily stored and transported so as to be along the wall surface of the storage tank T1. The second shielding plate b1 can be composed of a single lead plate material having an L-shaped upper portion between the adjacent standing rods 6 and 6, but as described above from the viewpoint of storage and transportation. It is preferable to form a plurality of lead plate materials.

In the shielding structure having the above configuration, first, the central member 1 is placed at the center of the upper surface of the storage tank T1. A plurality of base members 2 having the first mounting rods 3 are connected to the central member 1 radially at equal intervals through a distance adjusting mechanism 2a. Thereafter, the substantially intermediate portion of the base member 2 and the substantially intermediate portion of the upright bar 6 are connected by the support member 7, and the upright bar 6 is adjusted to be substantially vertical.
In addition, as for this foundation member 2, the location where the scaffold member B is installed and the location where the manhole is installed and the foundation member 2 cannot be placed are omitted. However, the standing bar 6 at this omitted location is supported by the horizontal bar 8 fixed to the adjacent standing bar 6, so there is no problem.

Further, the connecting member 4 having the second mounting rod 5 is connected between the adjacent base members 2 and 2. The opening 11 of the second shielding plate b1 is inserted into each of the first mounting rod 3 and the second mounting rod 5 to complete the lower shielding portion b. Thereafter, each first mounting rod 3 is erected by inserting a standing rod 6. After the upright bar 6 is erected, the horizontal bar 8 is fixed between the adjacent upright bars 6 by using a U-shaped metal fitting 9. The first shielding plate a1 is engaged with the fixed horizontal bar 8 to complete the upper shielding part a.
In addition, the shield structure assembled in this way is disassembled in a procedure reverse to the assembly order after inspection and repair work, and is carried out of the tank chamber R.

Here, in the above example, the radioactive waste stored in the storage tank T1 is a slurry-like powder ion exchange resin, a water layer is formed in the upper layer in the storage tank T1, and the water layer attenuates radiation. Therefore, it is not necessary to lay a shielding material on the upper surface of the storage tank T1, but a shielding material is also laid on the upper surface of the storage tank by the dose equivalent on the upper surface of the storage tank.
Although the description has focused on the shielding structure assembled to the storage tank T1, the shielding structure of the storage tank T2 is also assembled in the same manner as the storage tank T1.

  According to such a shielding structure, it is possible to efficiently assemble the support structure that supports the first shielding plate a1 and the second shielding plate b1 on the upper surfaces of the storage tanks T1 and T2, and efficiently. Since it can be decomposed in a short time, the exposure dose of the worker can be reduced.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) Each base member 2 is fixed by using a central member 1 made of a doughnut-shaped plate material. However, each base member 2 may be fixed by using a suction cup, or each base member 2 may be a magnet. You may fix using. Therefore, the central member of the present invention includes various fixing means such as a suction cup and a magnet for fixing the base member to the upper surface of the storage tank.
(2) Although the said embodiment is related with the shielding structure which shields the radiation of the storage tank which stores a low level radioactive waste in a nuclear power plant, this invention is the radiation of objects other than such a storage tank. It can also be applied to shielding.

It is a top view of the storage tank to which the shielding structure concerning one embodiment of the present invention is applied. It is a side view of the storage tank to which the shielding structure concerning one embodiment of the present invention is applied. It is an AA line expanded sectional view in FIG. It is the perspective view (a) of the 1st shielding board in one Embodiment of this invention, and the perspective view (b) of a 2nd shielding board. FIG. 4 is an explanatory diagram of a pair of support bar portions corresponding to the left enlarged side view of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Center member, 2 ... Base member, 3 ... 1st attachment rod, 4 ... Connection material, 5 ... 2nd attachment rod, 6 ... Standing rod, 7 ... Support member, 8 ... Horizontal bar, 9 ... U-shaped metal fitting 10 ... hook, 11 ... open hole,
a ... upper shielding part, a1 ... first shielding plate, b ... lower shielding part, b1 ... second shielding plate, T1, T2 ... storage tank, R ... tank chamber, C ... wall, E ... doorway

Claims (4)

A central member placed on the central portion of the upper surface of the storage tank for storing radioactive waste;
A plurality of foundation members that extend radially from the central member to the peripheral edge of the storage tank, and are placed on the upper surface of the storage tank at a predetermined interval from each other;
A first mounting rod provided at a location located at the peripheral edge of the storage tank of each foundation member, and protruding upward;
A plurality of connecting members each having an opening to be inserted into each of the adjacent first mounting rods at both ends, and having a plurality of second mounting rods protruding upward at a predetermined distance from each other in the middle portion When,
A plurality of standing bars inserted into the first mounting bars and standing;
A support member that connects the intermediate portion of each of the foundation members and the intermediate portion of each of the standing rods;
A plurality of horizontal bars that are bridged and fixed between the upper portions of the adjacent standing bars;
A plurality of first shielding plates for shielding radiation provided so that the upper end side is locked to the horizontal bar and the lower end side reaches the upper surface position of the storage tank;
An opening is inserted into the first mounting rod or the second mounting rod, the upper end side is supported, and the lower end side is provided with a plurality of first shields for shielding radiation that hangs down a predetermined length along the side surface of the storage tank. A shielding structure comprising: a second shielding plate.   The shielding structure according to claim 1, wherein the first shielding plate is attached to the horizontal bar using a hook.   The shielding structure according to claim 1, wherein the first shielding plate is configured to be foldable.   The shielding structure according to claim 1, wherein the second shielding plate is configured to be foldable.

Images