KR100941734B1 - Radiation shielding body - Google Patents

Abstract

The present invention provides a radiation shield that can simply install a radiation shield inside the steam generator to reduce the radiation dose rate to minimize the exposure of radiation to the operator, the radiation shield according to the invention, the center of the bottom surface For shielding the radiation during the internal operation of the steam generator of the nuclear power plant having a central axis in the close contact band and one end which is located on the outer peripheral surface of the central axis of the steam generator is connected to the upper portion of the close contact band, the other end is the steam A plurality of upper support rods in contact with the inner circumferential surface of the generator; And one end is connected to the lower portion of the close band, the other end includes a lower support bar in contact with the bottom surface of the steam generator, the lower support bar is prevented from moving toward the bottom surface, The upper support bar is characterized in that the contact band is prevented from being separated from the outer peripheral surface of the central axis.

Steam Generator, Adhesive Band, Upper Support Rod, Lower Support Rod

Description

Radiation shielding body {RADIATION SHIELDING BODY}

The present invention relates to a radiation shield, and more particularly, to a radiation shield that can minimize the radiation exposure to the operator by reducing the radiation dose rate during maintenance and repair operations of the steam generator in the steam generator.

As shown in FIG. 1, the nuclear reactor 10 includes a coolant pump 11, a reactor vessel 12, a pressurizer 13, and a steam generator 14 to serve as a heat exchanger. Water, which is a coolant, is heated by heat generated by nuclear fission of uranium, which is nuclear fuel, while passing through the reactor vessel 12, and water passing through the reactor vessel 12 enters the steam generator 14 through the pressurizer 13. The coolant entering the steam generator 14 passes the inside of the U-tube (Tube) of the steam generator to transfer heat to the water outside the tube to generate steam, whereby the coolant having a lower temperature is supplied to the coolant pump (11). It is sent back to the inlet of the reactor vessel 12 again. During this cycle, the coolant will contain uranium, so that the facilities inside the reactor, ie coolant pump 11, reactor vessel 12, pressurizer 13, steam generator 14, Is contaminated. In particular, since the steam generator 14 is a device for generating steam by transferring heat generated from the control rods of the reactor vessel to the water outside the U-tube by the coolant, the high radiation dose rate is high around the steam generator. Indicates.

In general, a nuclear power plant periodically stops a nuclear power plant in order to ensure stability, and then inspects and repairs equipment and facilities, and also checks steam generators that are located at the primary and secondary sides of the nuclear power plant. .

The steam generator is equipped with a manway, which is a passage through which workers can enter and exit for internal inspection and repair work (installation and removal of steam generator nozzle dams, vortex flaw test and clogging, etc.), The operator checks the equipment as the worker walks in and out through the manway.

However, the interior of the steam generator is not wide enough for the operator to work smoothly, and moreover, there is a problem that the worker is exposed by the mobile radioactive contaminants of the steam generator and a large amount of radiation.

In addition, it is possible to impose a psychological burden on the worker by finishing the work within a short time in the steam generator, which is a high dose area and a high pollution area, and thus there is a problem in that a more complete inspection and repair work cannot be performed.

An object of the present invention is to reduce the radiation dose rate inside the steam generator when the operator enters into the steam generator to check and repair the equipment inside the steam generator, such as the drainage nozzle of the steam generator and the measurement nozzle It is to provide a radiation shield that can minimize the exposure of radiation.

In addition, an object of the present invention is to shield the radiation present inside the steam generator, it is possible to prevent the body contamination of the worker working inside the steam generator, and to increase the working time to prevent the error in operation in advance It is to provide a radiation shield.

According to the present invention, the radiation shield is for shielding the radiation during the internal operation of the steam generator of the nuclear power plant having a central axis in the center of the bottom surface, the close contact band and one end located on the outer peripheral surface of the central axis of the steam generator is in close contact with the It is connected to the upper portion of the band, the other end is a plurality of upper support rods in contact with the inner circumferential surface of the steam generator; And one end is connected to the lower portion of the close band, the other end includes a lower support bar in contact with the bottom surface of the steam generator, the lower support bar is prevented from moving toward the bottom surface, The upper support bar is characterized in that the contact band is prevented from being separated from the outer peripheral surface of the central axis.

Preferably, the upper support rod and / or the lower support rod is hinged to the tight band.

The upper support rod includes a variable length means located between one end and the other end of the upper support rod, the length variable means by applying a force in the direction of the central axis to the close band by increasing the length of the upper support rod It is characterized in that the separation of the close contact band.

The variable length means is a buckle body, it is preferable that the length of the upper support bar is adjusted by the rotation of the buckle body.

The radiation shielding body further comprises a solder plate positioned on top of the upper support rods so as to be supported by the upper support rods.

 The soldering plate is characterized in that it comprises a pedestal to the upper support rod is fitted to the lower surface of the soldering plate.

Preferably, the radiation shield is coupled to the hook rod positioned to protrude from the close band, the rod support positioned to span the adjacent upper support rods, the upper support rod, the hook rod, and the rod support, It characterized in that it further comprises a shielding membrane for shielding the radiation to the bottom surface of the steam generator from a fixed position fixed to the hook hook and the shielding membrane hanger formed to protrude.

The contact band is composed of a plurality of members, the plurality of members are hinged to each other, surround the outer peripheral surface of the central axis of the steam generator, the upper support rod is a connecting rod fixed to the upper outer peripheral surface of the contact band, and the A buckle body is screwed to one side of the connecting rod, and the main rod is screwed to the other side of the buckle body, and the shielding bar hanger is connected to the upper portion of the body and the body is bent in the center portion to span the upper support bar; It is preferably made of an annular handle and a hook ring extending integrally outwardly from one end of the body to be bent to catch the shielding film.

According to the present invention, the radiation shielding shields the space where the worker works inside the steam generator, thereby minimizing the radiation exposure to the worker.

In addition, to reduce the exposure of the radiation to the worker to prevent the worker's body contamination.

In addition, by minimizing the radiation exposure to the operator, the average working time increases than before, and provides a psychological stability to the operator to perform a smooth operation to perform a more complete inspection than before, thereby improving the maintenance quality.

Hereinafter, a radiation shield according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The radiation shield is installed inside the steam generator 100.

2 is a cross-sectional view of a steam generator provided with a radiation shield. 3 is a longitudinal sectional view of a steam generator provided with a radiation shield according to line A-A of FIG.

The central shaft 110 extends from the bottom surface 112 of the steam generator 100 and is located at the center of the steam generator 100. As described above, as the coolant containing uranium passes through the central axis 110 of the steam generator 100, radiation contamination is particularly severe around the central axis 110 even inside the steam generator 100, which is a high dose region. . Therefore, the adhesion band 120 is in close contact with the outer circumferential surface 111 of the central axis 110 to reduce the radiation dose exposed from the central axis 110.

The adhesive band 120 is formed of a plurality of plate members (not shown), and the plurality of plate members are hinged to each other. The hinged plate members are folded to allow hinge movement to each other. Unfolding the close band 120 made of a plurality of plate-shaped members connected to each other, the close band 120 is a band shape having a predetermined length and width. In addition, each of the plate-like members constituting the close band 120 is formed to have an internal angle of 90 ° or more so as not to slide to the left / right in the state installed on the central axis 110 of the steam generator.

The enlarged part of FIG. 2 shows the packing material 124 attached to the close band 120. The packing material 124 is attached between the outer circumferential surface 111 of the central axis 110 and the inner circumferential surface 121 of the contact band 120. The packing member 124 is a member that prevents damage to the outer circumferential surface 111 of the central axis 110 of the steam generator 100 and improves the adhesion to the central axis 110 of the adhesion band 120. In the embodiment of the present invention, the packing material 124 uses a rubber material, but is not limited thereto.

Hanger rod 122 is provided on the outer peripheral surface 123 of the contact band 120. The hanger rod 122 is a member for hanging the shield curtain rack 160 (refer FIG. 11). In the exemplary embodiment of the present invention, the shape of the hook rod 122 is disclosed as a recessed shape, but the shape of the hook rod 122 is not limited to the exemplary embodiment of the present invention as long as the shielding rod may be hooked.

When the adhesive band 120 is in close contact with the outer circumferential surface 111 of the central shaft 110, the lower support rod 140 is attached to the outer circumferential surface 111 of the central shaft 110 and the bottom surface 112 of the steam generator 100. Contact. Thereafter, the upper support rod 130 is installed between the outer circumferential surface 111 of the central shaft 110 and the inner circumferential surface 101 of the steam generator.

2 and 3, one end 137 of the upper support rod 130 is in contact with the outer circumferential surface 123 of the upper portion of the contact band 120, the other end 139 of the upper support rod 130 The inner peripheral surface 101 of the steam generator 100 is in contact. Here, one end 137 of the upper support bar 130 and the outer peripheral surface 123 of the upper portion of the contact band 120 is hinged. Also, As will be described later, the upper support rod 130 has a variable length means, fine length can be adjusted, the upper support rod 130 is installed to support the inner peripheral surface 101 of the steam generator using this. As shown in FIG. 2, each of the plurality of upper support rods 130 is radially installed based on the central axis 110 and spaced apart at regular intervals so that the outer circumferential surface 123 and the steam generator 100 are spaced apart from each other. It is provided between the inner circumferential surface 101 of (). This allows the load applied to the upper support rod by the solder plate and the load of the upper support rod itself to be evenly distributed when the solder plate 150 (see FIG. 8) is placed on the top of the upper support rod 130. In addition, the upper support rod 130 serves as a main frame for shielding the upper portion of the steam generator with a large amount of radiation by supporting the lead plate (150, see Figure 8) for shielding radiation.

The lower support bar 140 is a structure for supporting the upper support bar 130 to assist. One end 141 of the lower support rod 140 is hinged to the outer circumferential surface 123 of the lower portion of the contact band 120, the other end 142 of the lower support rod 140 is the bottom surface of the steam generator (100) 112). Here, the lower support rod 140 is located below the upper support rod 130. That is, one end 141 of the lower support rod 140 hinged to the outer circumferential surface 123 of the close contact band 120 is one end of the upper support rod 130 hinged to the outer circumferential surface 123 of the close contact band 120. Located at the bottom of the 137 to support the upper support bar 130 to support the close band 120. In the embodiment of the present invention, the upper support rod 130 and the lower support rod 140 is made of a strong aluminum material and easy to move, but is not limited thereto.

Table 1 below is a level evaluation of the radiation dose rate according to the installation position of the radiation shield in the workplace in the steam generator (100). Referring to Table 1, the radiation dose rate inside the steam generator before shielding is 70mSv / hr in the upper part, 50mSv / hr in the middle, and 30mSv / hr in the lower part, where the highest radiation dose rate is in the upper part of the steam generator and in the steam generator. It can be seen that the radiation dose per hour (mSv / hr) decreases from the top to the bottom of. Moreover, the radiation dose per hour (mSv / hr) is the same in the upper, middle, and lower portions of the steam generator after the shielding. Therefore, since it is most efficient to install the radiation shield on top of the steam generator, in the embodiment of the present invention, the radiation shield is installed on top of the steam generator.

[Table 1] Evaluation of radiation dose rate level before and after shielding in steam generator

 Measuring position Radiation dose rate (mSv / hr) Before shielding After shielding Reduction ratio Top 70 17 76% middle 50 17 66% bottom 30 17 44% Average 50 17 66%

4 shows a preferred embodiment of the variable length means located between one end 137 and the other end 139 of the upper support rod.

The length of the upper support bar 130 is adjustable, the connecting rod 132 hinged to the outer peripheral surface 123 of the contact band 120, the buckle body 134 is screwed to one side of the connecting rod 132, buckle body 134 It consists of a known supporting rod 136 is screwed to the other side of the). The upper support bar 130 configured as described above is variable in length by the rotation of the buckle body in a turnbuckle manner. The buckle body 134 is provided with a screw shape on both sides is a structure capable of adjusting the distance when supporting the structure.

Therefore, after contacting one end 137 of the upper support bar 130 hinged to the outer peripheral surface 123 (see Fig. 2) of the contact band 120 in contact with the central axis 110, the buckle body 134 Rotating the other end 139 of the supporting rod 136 to the inner peripheral surface 101 of the steam generator (see Fig. 2) of the upper support rod 130 of the central shaft 110 to which the close band 120 is attached It is positioned between the outer circumferential surface 111 and the inner circumferential surface 101 of the steam generator 100. In an embodiment of the present invention, the variable length means is described with the buckle body 134 as an example, but is not limited thereto.

FIG. 5 is a cross-sectional view of a steam generator provided with a radiation shield according to line B-B of FIG. 3. 6 is a cross-sectional view taken along line C-C of FIG. 5, and FIG. 7 is an enlarged view of portion D of FIG. 5.

As shown in FIG. 5, rod support 135 is positioned to span the top of adjacent upper support rods 130. The rod support 135 may be installed at least one upper portion of the upper support rod (130). One or more rod supports 135 are arranged to be spaced apart from each other at regular intervals. This assists the upper support rod 130 to structurally and stably install a soldering plate 150 (see FIG. 8) for shielding radiation descending from the top of the steam generator 100 to the lowering of the soldering plate 150 (FIG. 8). Support).

As shown in FIG. 6, the rod support 135 has a groove 135a formed to be seated on the upper support rod 130. The groove 135a formed in the rod support 135 is seated on the upper support rod 130 to fix the rod support 135 to the upper support rod 130.

 As shown in FIG. 7, an elastic material 138 is attached to the other end 139 of the upper support rod 130. The elastic member 138 is also attached to the other end 142 of the lower support bar (see FIG. 3). The elastic member 138 prevents the inner circumferential surface 101 of the steam generator 100 from being damaged by the other end 139 of the upper support rod 130, and the other end 139 of the upper support rod 130. It is a member that prevents slipping on the inner circumferential surface 101 of the main body of the steam generator 100. Therefore, in the embodiment of the present invention, the material of the elastic material is made of polyurethane in order to prevent damage and slipping of the contacting object, but is not limited thereto.

8 is a cross-sectional view of a radiation shield provided with a lead plate.

As illustrated in FIG. 8, the solder plate 150 is positioned above the upper support bar 130 to shield radiation descending from the top to the bottom of the steam generator 100. The lead plate 150 is a lead plate containing a material that shields radiation. In general, compared to the shielding film used for shielding radiation, the lead plate can be installed stably while maintaining horizontality. Therefore, in the upper part of the steam generator, which is a high radiation dose region among the steam generator 100, a lead plate is used to increase the shielding effect of radiation. However, the lead plate 150 is formed not too thick to facilitate movement and installation.

One or more upper support rods 130 are radially widened from each other toward the inner circumferential surface 101 of the steam generator 100 from the outer circumferential surface 111 of the central shaft 110, so that the upper support rods 130 are positioned at the upper portion of the upper support rod 130. The soldering plate 150 may have a rectangular plate shape as shown in FIG. 9, but is preferably made in an arc shape.

10 is a cross-sectional view of a solder plate provided with a pedestal on the solder plate bottom surface. As shown in FIG. 10, the bottom surface of the solder plate 150 is provided with a pedestal 152 that prevents the detachment of the solder plate 150 from the upper support rod 130 (see FIG. 8).

11 is a cross-sectional view of the shield film hanger.

11 is a structure for fastening the shielding film rack 160, the shielding film rack 160 is a hook rod 122 (see Fig. 2) of the close band, the upper support rod 130 and the rod support (135, 5) The body 162 which is bent to cover the center portion, the ring-shaped handle 164 connected to the upper portion of the body 162, and integrally formed to be bent outwardly extending to one end of the body 162. Then it is integrally formed with a hook 166 for hanging the shielding film. In the exemplary embodiment of the present invention, the shape of the shielding film rack 160 is limited as described above. However, the shielding film rack 160 is not limited to the shape of the shielding film rack because it is a structure for binding the shielding film.

The shielding film is a structure composed of fibers containing a shielding material, and generally, lead blanket is used as the shielding film. The lead blanket is flexible like a tent, so it is easy to shield the space. Therefore, the shielding film (not shown) is caught on the hook 166 of the shielding film hanger 160 to shield everywhere except the upper portion shielded by the solder plate 150. That is, the shielding film connected to the shielding film rack 160 provided in the hook rod 122 (refer to FIG. 2) provided in the close band 120 (see FIG. 2) shields the periphery of the central axis 110 and the upper support bar 130. The shielding film connected to the shielding film rack 160 provided in the shields the left / right space of the workplace, and the shielding film connected to the shielding film rack 160 provided in the rod support 135 shields the direction facing the central axis 110. do. In this case, the shielding film connected to the shielding film rack 160 provided in the rod support 135 is formed longer than the shielding film connected to the shielding film rack 160 provided in the hook rod 122 (see FIG. 2) and the upper support bar 130. This is to shield the bottom of the steam generator. Here, the shielding film rack 160 is manufactured in a small size of 7 ~ 10cm in order to minimize the radiation dose flowing into the gap generated when the shielding film is connected to the shielding film rack 160. In addition, the hook 166 is hooked through a hole (not shown) formed in the upper portion of the shielding film.

On the other hand, in the present invention, as shown in Figure 3, the nozzle cover body on the upper portion of the nozzle dam 170 to prevent foreign substances generated during the installation and removal operation of the radiation shielding body into the nozzle dam 170 inside the steam generator It is provided.

The shielding effect by the radiation shielding body installed as above will be described with reference to Tables 2 and 3 below. Table 2 shows the estimates of worker exposure before steam generator shielding and Table 3 shows the estimates of worker exposure after steam generator shielding.

Referring to Tables 2 and 3, the total exposure to workers was 4.9 mSv before the radiation shield was installed in the same workplace (inside the S / GC / L steam generator), and 5.8 mSv after the radiation shield was installed. The exposure to the worker for 1 minute was 0.49 mSv / min before shielding, while the shielding exposure to 0.23 mSv / min after shielding was reduced to 1/2. In addition, the working time per worker is 0.17 (man-hr) before installing the radiation shield, whereas after the radiation shield is installed, the working time per worker is 0.42 (man-hr). It can be seen that the work time per person is increased by about 2.5 times.

[Table 2] Evaluation of Exposures of Workers Before Steam Generator Shielding

Work contents Work place Input Total work time man-hr Total exposure (mSv) 1 minute exposure (mSv / min) S / G 02 Drain nozzle UT S / G C / L Steam Generator Inside  2 people  10 minutes  0.17  4.9  0.49

[Table 3] Evaluation of the exposure of workers after the steam generator shielding

Work contents Work place Input Total work time man-hr Total exposure (mSv) 1 minute exposure (mSv / min) S / G 02 Drainage Nozzle Processing S / G C / L Steam Generator Inside  4 people  25 minutes  0.42  5.8  0.23

The illustrative embodiments described above are intended to be illustrative within all aspects of the invention rather than limiting. Accordingly, the present invention is capable of many modifications and detailed implementations that can be obtained from those skilled in the art from the description contained herein. All such modifications and variations are considered to be within the scope and spirit of the invention as defined by the following claims.

1 is a system diagram of a nuclear power plant.

2 is a cross-sectional view of a steam generator provided with a radiation shield.

3 is a longitudinal sectional view of a steam generator provided with a radiation shield according to line A-A of FIG.

4 is a cross-sectional view of the upper support bar.

FIG. 5 is a cross-sectional view of a steam generator provided with a radiation shield according to line B-B of FIG. 3.

6 is a cross-sectional view taken along the line C-C of FIG.

FIG. 7 is an enlarged view of portion D of FIG. 5.

8 is a cross-sectional view of a radiation shield provided with a lead plate.

9 is a perspective view of a soldering plate located on top of an upper support rod.

10 is a cross-sectional view of a soldering plate provided with a pedestal on the bottom of the soldering plate.

11 is a cross-sectional view of the blocking bar hanger.

<Explanation of symbols for the main parts of the drawings>

100: steam generator 110: central axis

120: close band 122: hanger rod

124: packing material 130: upper support bar

135: bag support 138: elastic material

140: lower support bar 150: lead plate

152: base 160: shielding rack hanger

Claims (8)

In the radiation shielding body which is installed inside the steam generator for the shielding of the radiation during the operation of the steam generator of the nuclear power plant having a central axis in the center of the bottom surface, An adhesion band positioned on an outer circumferential surface of the central axis of the steam generator; One end is connected to the upper portion of the contact band, the other end is a plurality of upper support rods in contact with the inner circumferential surface of the steam generator; And One end is connected to the lower portion of the close band, the other end includes a lower support bar in contact with the bottom surface of the steam generator, And the adhesion band is prevented from moving toward the bottom surface by the lower support rod, and the adhesion band is prevented from being separated from the outer circumferential surface of the central axis by the upper support rod. The method of claim 1, The upper support rod, the lower support rod, or the upper support rod and the lower support rod is a radiation shield, characterized in that hinged to the close band. The method of claim 1, The upper support rod includes a variable length means located between one end and the other end of the upper support rod, And the length varying means increases the length of the upper support bar, thereby applying a force in the direction of the center axis to the close band to prevent separation of the close band. The method of claim 3, wherein The variable length means is a buckle body, Radiation shielding body characterized in that the length of the upper support bar is adjusted by the rotation of the buckle body. The method of claim 1, wherein the radiation shield is And a soldering plate positioned above the upper supporting rods to be supported by the upper supporting rods. The method of claim 5, wherein The soldering plate is a radiation shield, characterized in that it comprises a pedestal to the upper support rod is fitted to the lower surface of the soldering plate. The method of claim 1, wherein the radiation shield is A hook rod positioned to protrude from the contact band; A rod support positioned to span an upper portion of the adjacent support rods; A shielding film hook coupled to the upper support rod, the hook rod, and the rod support, the hook hook protruding from the hook support; And And a shielding film for shielding radiation from a fixed position fixed to the catching ring of the shielding film hanger to the bottom surface of the steam generator. The method of claim 7, wherein The contact band is composed of a plurality of members, the plurality of members are hinged to each other, surrounds the outer peripheral surface of the central axis of the steam generator, The upper support rod includes a connecting rod fixed to the upper outer circumferential surface of the contact band, a buckle body screwed to one side of the connecting rod, and a known supporting rod screwed to the other side of the buckle body, The shielding film hanger is formed integrally to be bent to extend outwardly from one end of the body, and the body is bent in the center portion is bent over the upper support rod, the ring-shaped handle connected to the upper portion of the body and the shielding film is caught Radiation shield, characterized in that made of a hook to make.

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