JPH022365B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electrically penetrating sleeve with excellent radiation shielding performance, which is used in a high-strength radial shielding wall.

Recently, in the design of nuclear power plants, safety-related equipment and systems have increased due to safety considerations, and the number of cables used has also increased significantly.
Along with this, the number of so-called electrical penetration sleeves that penetrate the radiation shielding wall has increased, and the number of penetration conductors in each sleeve has also increased significantly.

In cases where the area around the reactor may be exposed to an extremely strong radiation environment, such as liquid sodium-cooled fast breeder reactors, whose development has recently become important both domestically and internationally, sufficient consideration must be given to radiation shielding. . Therefore, when a large number of cables are passed through an electrical penetration sleeve for a radiation shielding wall, how to prevent leakage of radiation has become an extremely important issue.

Conventionally, in this type of electrical penetration sleeve, as shown in Fig. 1, a pressure-resistant sleeve body 1 is provided with a flange 2 at one end of a stainless steel pipe having a diameter of 300 to 400 mm and a length of 1500 to 3000 mm. It is welded or bolted to the shielding wall main body via the flange 2. That is, a plurality of insulated conductors 4 (6 in the figure is simplified) are passed through the sleeve main body 1, and the main body is filled with a shielding material 3 made of the same material as the shielding wall or concrete, mortar, lead, etc. to form a sleeve. In order to prevent gas from leaking along the insulated conductor, the inside or end of the sleeve is generally hermetically sealed by a hermetic seal.

However, with regard to radiation leakage, in such a structure, radiation, such as gamma rays, may leak while traveling straight along the interface between the conductor and the shielding material.
In order to prevent this, as shown in FIG. 2, the insulated conductor is bent at a desired portion to provide a stepped portion 5 to prevent the radiation from traveling straight.

Although this type of structure is sufficient to prevent radiation leakage in conventional water-cooled reactors or gas-cooled reactors, even stricter leakage prevention is required in molten metal cooled reactors as mentioned above. This is what is being done.

In the electrical penetrating sleeve as shown in Fig. 2, the positions of the outermost layers of the left and right insulated conductors are different around the stepped portion 5, and by providing the stepped portion 5, the diameter of the collective bundle of insulated conductors is increased. Therefore, the size and weight of the penetrating sleeve increase accordingly, which is disadvantageous in terms of installation to the shielding wall and economical efficiency. Moreover, in order to sufficiently prevent leakage of radiation, it is necessary to make the step large enough or to bend the insulated conductors in the circumferential direction when viewed from the center line of the sleeve, but since there are a large number of conductors, processing is not easy. Furthermore, this was also difficult for insulated conductors located close to the center line of the sleeve.

As a result of extensive research aimed at improving these shortcomings, the present invention has found a sleeve that can prevent radiation leakage through a relatively easy twisting process and without providing any step in the insulated conductor that passes through the sleeve body. It is something that That is, the present invention provides an electrical penetration sleeve in which a plurality of insulated conductors are passed through a radiation-shielding wall-penetrating sleeve main body, and a plurality of insulated conductors having a metal sheath or a plurality of insulated conductors inserted into a metal protective tube are inserted into the sleeve main body. The present invention is characterized in that a right-handed spiral and a left-handed spiral of a desired pitch are alternately formed at predetermined intervals along the longitudinal direction of the book, and twisted concentrically, and the outer periphery of the twisted spiral is filled with a shielding material. be.

Embodiments of the present invention will be described in detail based on the drawings.

As shown in FIG. 3, when the insulated conductors 4 inserted into the sleeve main body 1 are viewed from the flange of the sleeve (right side in the figure), each insulated conductor is at a position 6 in the longitudinal direction.
Twisting in opposite directions is applied alternately so that the right side is a right-handed spiral 7 and the left side is a left-handed spiral 8. A filling material 3, such as concrete, is inserted into the outer periphery and solidified to fill the outer periphery of the insulated conductor to prevent radiation from moving straight along the conductor.

Note that twisting concentrically means that
In the vicinity of the flanges at both ends of the sleeve, the insulated conductors are twisted so as to be arranged coaxially and on the same circumference. In other words, multiple insulated conductors to be twisted are concentrically twisted.

That is, to prevent leakage due to straight radiation, it is sufficient to twist the insulated conductor in one direction, but in the present invention, in addition to this, twisting the insulated conductor at predetermined intervals (for example, the third As shown in the figure, in the right twisting section at position 6, it is 1 pitch length, in other words, 360° rotation, and on the other hand, in the left twisting section at position 6, it is 1/2 pitch length, in other words, 180° rotation.)
A right-handed spiral and a left-handed spiral are given alternately.

Therefore, in the present invention, when providing a right-handed spiral and a left-handed spiral alternately, the interval (ie, pitch length x number of pitches) is not limited and may be arbitrary. For example, as described below, if expressed in terms of 1/4 length or rotation angle (or twisting angle), it is 90°, 1/3 pitch length (120°), 1/2 pitch length (180°), 1 Pitch length (360°)
Any desired spacing may be used, such as Furthermore, it is not necessary that the right-handed spirals and left-handed spirals have the same spacing; for example, as shown in Figure 3, the right-handed spirals have an interval of 1 pitch length, and the left-handed spirals have an interval of 1/2 pitch length. They can be provided at different intervals so that In addition, as shown in Fig. 3, it is not limited to the case where only one right-handed spiral portion and one left-handed spiral portion are provided, but a plurality of both spiral portions may be provided alternately such as two or three. It's okay.

FIG. 4 shows another example of the present invention, in which six insulated conductors a, b, and c are divided into three blocks and each block is twisted. In this case as well, the twisting positions are reversed on the left and right sides of position 6 within the sleeve body, as in FIG.
In this case as well, the outer periphery of the twisted insulated conductor is filled with shielding material 3 in the same manner as in FIG.

Furthermore, the insulated conductor used in the present invention is an insulated conductor having a metal sheath or an insulated conductor inserted into a metal protection tube, and examples of the former include insulated conductors as shown in FIGS. 5 and 6. . That is, FIG. 5 shows an insulated conductor for electric power or instrumentation, where 9 is a copper core wire, 10 is an inorganic insulator such as magnesium oxide powder, and 11 is a metal sheath such as stainless steel. Also, Figure 6 shows the insulated conductor for coaxial cable, and in the figure 9 and 1 are shown.
0 and 11 are the same as above, and 12 is an external conductor.

An example of the latter insulated conductor inserted into a metal protection tube is one in which an ordinary rubber/plastic insulated conductor is inserted into a metal protection tube such as a stainless steel tube.

The sleeve body used in the present invention is not particularly limited in its shape and dimensions, but usually consists of a flange and a pipe as shown in FIGS. 3 and 4, with one or both ends having an airtight seal structure. In order to prevent radiation leakage between the outer periphery of the pipe and the wall, a pipe with a difference in outer diameter at one or more places as shown in FIG. 2 may be used, but the penetrating sleeve of the present invention Since there is little radiation leakage along the insulated conductor as in the case shown in Figure 2, this outer diameter difference can be kept relatively small, and usually a sufficient effect can be achieved within 10 mm in the radial direction.

As the insulated conductor, rubber or plastic insulated conductors with excellent radiation resistance, or inorganic insulated conductors such as glass mica can be used, but particularly suitable for the purpose of the present invention is a conductor with a desired gap provided on the outside of the conductor core wire. A cable covered with a metal sheath and filled with an insulating inorganic material in the gap (abbreviated as MI cable)
It is. In other words, if you use an MI cable with a filling rate of inorganic powder close to 100%, this insulating layer itself will shield radiation, so there will be no problem even if it is linear, and the remaining MI
Since the leakage occurs through a small gap between the metal sheath of the cable and the shielding material, this has the advantage that radiation leakage can be easily prevented with very little twisting.

Therefore, when an MI cable is used in the sleeve having the structure of the present invention, there is no radiation leakage through the insulating layer, and it is only necessary to consider radiation leakage through a small gap between the metal sheath of the MI cable and the filled shielding material. , a small amount of twisting, ie long pitches, is sufficient for this.

However, even with a relatively slight twist, the stainless steel sheath
For MI cables, for example, inside the sleeve body
Not only is it extremely difficult to twist a large number of rigid cables over a length of 3000 mm, but the residual strain in the stainless steel may cause damage to the cables or electrical damage during the installation life of many months. The distortion of the sheath due to twisting must be kept as low as possible, as this may lead to a decline in physical performance.

However, according to the present invention, (1) it is possible to provide concentric twists that are easy to process by using a rotating jig, and (2) buckling and cracking can be avoided in an insulated conductor having a metal sheath or metal protection tube. It is possible to perform the twisting process evenly and alternating the twisting directions while maintaining a rotation angle that does not cause the twisting to occur, which makes the twisting process extremely easy and reduces the stress caused by twisting to the cable. It has the advantage that the strain on stainless steel is extremely small because it is easy to apply it uniformly. By twisting each block as shown in Figure 4, the strain on the stainless steel can be further reduced. Another advantage of the present invention is that it is possible to take advantage of the fact that MI cables are highly shaped by twisting, and if all the cables to be housed in the sleeve are to be twisted at the same time, the processing requires an extremely large amount of force. However, in the present invention, as described above, the right-handed spiral portion and the left-handed spiral portion are provided alternately, so each cable is twisted in a predetermined manner in advance, and thus shaped. Figure 3 shows the cable that was
It has the advantage that it can be easily assembled into the sleeve shown in FIG. 4, and that both the twisting process and the assembly are easy.

In addition, when using a rubber or plastic insulated conductor as an insulated conductor, insert it into a metal protection tube such as a stainless steel tube, and use the rubber or plastic insulated conductor inserted into the metal protection tube or the Each protective tube can be shaped in advance by twisting and then assembled into the sleeve. In this case as well, the radiation shielding performance can be improved by increasing the degree of twisting, and the same advantages as in the case of MI cables can be fully demonstrated.

Next, in the present invention, as an example of the manufacturing process of the sleeve, as an insulated conductor penetrating inside the sleeve body.
This section describes the case when using an MI cable.

That is, in FIG. 7, a fixed penetrating plate (cable position fixing plate) 13 having a through hole through which the cable 4 can pass is attached to the part where the bending starts near the right end flange 2 side (the end of the fixed section), and this is applied with an external force. Then, another penetration plate 14 for cable twisting is fixedly supported at that position by the sleeve.
Install. Further, a fixed penetrating plate (cable position fixing plate) 15 is attached to the part where the bend ends near the left end side of the sleeve (the starting end of the fixed section). In this state, by rotating the cable twisting penetration plate 14 in one direction (in the figure, at an angle of 180° to the right as indicated by the arrow), the cables can be twisted from the portions close to the left and right sides of the penetration plate 14. The twisting progresses smoothly, and the twisting directions are opposite on both the left and right sides of the penetrating plate 14. During this twisting, the twisting penetrating plate 14 and the fixed penetrating plate 15 are appropriately slid in the direction of the collar portion 2 along with the twisting.

According to this method, when using a cable with a metal sheath such as an MI cable, or when using a metal cable protection tube for a plastic sheath cable, it is easy to appropriately adjust the strain applied to the metal sheath or protection tube. Furthermore, it is extremely advantageous in terms of the processing equipment's ability (for example, rotation angle).

In addition, in FIG. 7, the case where there is one right-handed helical part and one left-handed helical part between all the sleeves has been explained, but as shown in FIG. In the case where there are a plurality of each alternately, the same process may be performed. Next, this case will be briefly explained.

That is, as in the case of Fig. 7, a fixed penetrating plate (cable position fixing plate) having a through hole through which the cable can pass is installed at the part where the bend begins near the right end flange side, and its position is fixed by external force. support,
Install another cable twisting pass-through plate approximately in the middle of the entire length of the sleeve. This twisting plate is adjusted to the desired angle by external force (360° to obtain the one in Figure 3).
Let it rotate. Next, this penetration plate is fixed and supported in that state by external force, and another penetration plate for twisting the cable is attached to the part where the bend ends at the left end of the cable, and it is rotated in the opposite direction in the same manner as above. . Therefore, the twist of the cable on the side facing the flange returns to almost its original state. In this case, the angle of twist can be increased by switching the direction of rotation even more.
You can freely reduce the angle from 360° to, for example, 180°, 120°, or 90°. This becomes extremely advantageous in terms of the ability of the device to rotate the penetrating plate.

On the other hand, if the twisting direction is twisted only in one direction without reversing the twisting direction at a predetermined point, the twisting angle needs to be large and the rotation angle must be set sufficiently as a device for rotating the penetrating plate. You need someone with the ability to draw. Moreover, stress tends to concentrate on a certain portion of the entire length of the cable, which is undesirable as it may cause buckling or cracking of the cable sheath.

In other words, when twisted to form a right-handed spiral and a left-handed spiral alternately, the insulation is more The local strain experienced by the weakest part of the conductor is significantly smaller. Therefore,
Buckling and cracking are prevented.

Each insulated conductor receives torsional strain due to twisting, but
Taking as an example the case where one pitch is twisted by winding in one direction, each insulated conductor will twist one rotation between each pitch.

However, since the "insulated conductor having a metal sheath or the insulated conductor inserted into a metal protection tube" used in the present invention has a metal sheath or metal protection tube, if it is twisted by twisting it, the mechanical Torsional stress concentrates on weak points, causing buckling or cracking.

However, when twisted in one direction, as shown in Figure 8, each insulated conductor undergoes one rotation of twist between each pitch, and this one rotation's worth of twisting stress is concentrated at the weakest point between each pitch. do.

That is, FIG. 8 shows a state in which one of the insulated conductors is focused and twisted uniformly. Figure 8 A is an insulated conductor 4
The figure shows a state in which the fibers are twisted by one pitch in a left-handed spiral on an imaginary coaxial cylinder 20. FIG. 8B shows how the sheath 11 of the insulated conductor 4 in FIG. 8A becomes twisted as it is twisted. In other words, from the left end a of the insulated conductor 4 in Figure 8A to the right end, the twist angle is position b at 90°, position c at 180°, position d at 270°, and position e at 360°.
A cross section of the sheath 11 at each position is shown in FIG. 8B. ● shown in each cross section of sheath 11
The mark and the x mark are virtual marks placed near the ● mark to clearly illustrate how the sheath 11 is twisted during one twist. The symbol T shown above indicates the top at position a at the left end, and the symbol B near the x mark indicates the bottom at position a. At position b, T and B are each rotated by 90 degrees, that is, 1/4 rotation. Similarly, at positions c, d, and e, T and B are respectively 180° (1/2 turn), 270° (3/4 turn), and 360° (1/2 turn).
rotation) is in a rotating state.

Therefore, when twisted in one direction, the insulated conductor undergoes one rotation of twist between each pitch, and this one rotation's worth of twisting stress is concentrated at the weakest point between each pitch, resulting in buckling or cracking. Occur. On the other hand, in the present invention, as shown in FIG. 9, since the spiral twist is right-handed and left-handed between the same pitches, a twist of half a rotation occurs between 1/2 pitches, but this 1/2 pitch Even if the torsional stress is concentrated at the weakest part between them, the stress is generated by twisting for 1/2 turn, and is equal to 1/2 of the torsional stress for one turn caused by the above-mentioned unidirectional winding. Become. That is, FIG. 9 shows a state in which one of the insulated conductors is focused on and twisted uniformly. Figure 9A shows the insulated conductor 4 as in the case of Figure 8.
The figure shows the twisted state on an imaginary coaxial cylinder 20, but the difference from FIG. The section from the /2 pitch position to the right end (1/2 pitch) is twisted in a right-handed spiral. Figure 9B shows the sheath 1 of the insulated conductor 4 in Figure 9A as in the case of Figure 8B.
1 shows how it becomes twisted as it is twisted. All numbers and symbols are the same as in FIG.

As is clear from FIG. 9, at positions a, b, and c, the cross sections of the sheath 11 are 0°, 90° (1/4 turn), respectively.
It is twisted by 180° (1/2 turn), but at positions d and e, it is shown to be twisted by 90° (1/4 turn) and 0° (0 turn), respectively.

Therefore, in this case, by alternating left-handed and right-handed spirals within one pitch, the insulated conductor is only twisted by 1/2 turn, so the torsional stress that the insulated conductor receives during actual twisting is 1 The stress is equivalent to 1/2 rotation, which is 1/2 the stress compared to unidirectional winding, and the occurrence of buckling and cracking is extremely prevented.

In other words, when twisting in one direction, if the torsional stress concentrates on the weakest part of the insulated conductor, then
Whereas the torsional stress for a rotation is concentrated, in the case of alternating left and right winding twisting (the present invention), only the torsional stress for 1/2 rotation is concentrated at the weakest part of the insulated conductor. The possibility of bending or cracking is significantly reduced.

Furthermore, since the present invention uses alternating right and left winding twisting, the degree of twisting (twisting angle) can be freely selected, thereby reducing the torsional stress that each insulated conductor receives between 1/2 pitches. Can be done. In other words, the twist angle given to the insulated conductor is 180 between 1/2 pitch.
Since it is possible to reduce the twist angle to less than a degree, the twist angle to which each insulated conductor is subjected can be reduced accordingly. the result,
Torsional stress can be reduced. Therefore, there is an advantage that the twisting angle can be adjusted in accordance with various conditions such as the degree of processing resistance of the insulated conductor, and appropriate processing can be performed.

In the above description of the manufacturing process, a plate having a hole through which the cable can pass is used as the penetration plate, but if this plate is to be removed after twisting, a lattice frame through which the cable can pass is used. After twisting, the frame body can be disassembled by removing the beams that make up the lattice. This has advantages such as ease of filling the shielding material into the sleeve body.

The above two examples show the manufacturing process of a sleeve that twists the cable that passes through the collar of the sleeve, but in this case, the insulated conductor is an MI cable, and the terminal is integrated with the cable as a pre-process of manufacturing the sleeve. Generally used when installing connectors. On the other hand, if there is no pre-processing for such a terminal, the cable (or protective tube)
All you have to do is give it a twist and attach it to the flange.
As an example, when the insulated conductor is divided into blocks and twisted as shown in FIG. MI cables and metal protection tubes can be pre-twisted and assembled into sleeves one by one), and can be attached to the right side of the flange, making it even more advantageous in terms of processing equipment capacity. This is preferable in terms of processing as it can avoid cable buckling and sheath cracking.

In the present invention, it is particularly desirable to use an MI cable as an insulated conductor, but the MI cable is made of powder such as magnesium oxide, aluminum oxide, or silica as an insulator, and a corrosion-resistant metal pipe such as stainless steel, copper, or Inconel is sheathed. It is preferable that As the conductor, copper alloy, constantan, alumel, chromel, etc. are selected depending on the purpose for power, control, measurement, etc.
The number of wire cores is not particularly limited, but as mentioned above, in the case of MI cables, it is relatively easy to solve the problem of radiation leakage from the insulated conductor itself, so a multi-core cable can be used. Another great advantage is that if the end of the MI cable is hermetically sealed, the cable itself can be used as a through conductor.
In other words, a general insulated conductor that does not have a metal pipe as a sheath cannot seal itself airtight, so after processing the terminal at the end of the sleeve etc., an airtight structure such as a hermetic seal is created using an insulating inorganic or organic material. Such troublesome measures have to be taken.

Even if you do not use an MI cable,
It goes without saying that the present invention is not limited to MI cables, as the purpose of the present invention can be achieved by selecting an insulated conductor with a relatively small amount of radiation leakage or by using other measures to prevent leakage of the insulated conductor itself. Nor.

In the present invention, the number of insulated conductors passing through the sleeve body is not particularly limited, but a large number of insulated conductors, at least six or more, usually ten or more, are made to pass through the sleeve body.

The twisting angle of the insulated conductor within the sleeve body of the present invention cannot be limited because it depends on the size of the conductor or the distance from the twisting center line, but it is usually right-handed. It is desirable that the rotation angle is 45° or more, preferably 90° or more for both left-handed rotations. Further, the number of locations where the twisting direction is reversed may be one or more for each insulated conductor, and is not particularly limited. Note that the twisting does not need to be performed over the entire length of the sleeve body, but may be at least 2/3 or more of the portion filled with the shielding material within the sleeve body.

In addition, the shielding material to be filled around the outer periphery of the insulated conductor only needs to have a high density and can be filled uniformly. It can also be effective. Alternatively, the insulated conductor may be brought into contact with the shielding material through another thin-walled material, such as through a metal tube. Note that the shielding material is not limited to a single type, and a mixture of two types may be used.

As described in detail above, the present invention has remarkable effects such as excellent shielding properties against high-intensity radiation, extremely high reliability, and advantages in manufacturing.

[Brief explanation of drawings]

1 and 2 show an example of a conventional electrical penetration sleeve, A is a side sectional view, B is a side view from the flange direction, and FIGS. 3 and 4 are electrical penetration sleeves of the present invention. This shows an example of a target penetrating sleeve, and A
is a side sectional view, B is a side view from the direction of the flange, FIGS. 5 and 6 are sectional views showing other examples of the through conductor in the present invention, and FIG. 7 explains the manufacturing process of the sleeve in the present invention. FIG. 8 is an explanatory diagram for explaining the state when one of the insulated conductors constituting the electrical penetration sleeve according to the prior art is twisted uniformly; The figure is an explanatory diagram for explaining a state when one of the insulated conductors constituting the electrically penetrating sleeve according to an embodiment of the present invention is twisted uniformly. DESCRIPTION OF SYMBOLS 1... Sleeve body, 2... Flam part, 3... Shielding material, 4... Insulated conductor, 5... Step part, 6... Center part, 7... Right-handed helical part, 8... Left-handed spiral part. Turning part, 9... Core wire, 10... Insulator, 11... Sheath, 12... Outer conductor, 13... Fixed penetrating plate, 1
4... Penetration plate for cable twisting, 15... Fixed penetration plate.

Claims (1)

[Scope of Claims] 1. An electrical penetration sleeve in which a plurality of insulated conductors are passed through the radiation shielding wall penetration sleeve body, an insulated conductor having a metal sheath or an insulated conductor inserted into a metal protection tube within the sleeve body. A plurality of the fibers are concentrically twisted by alternately forming right-handed spirals and left-handed spirals with a desired pitch at predetermined intervals along the longitudinal direction, and the outer periphery of the twisted spirals is filled with a shielding material. Electrical penetration sleeve for radiation shielding walls. 2. The radiation shielding according to claim 1, characterized in that an insulated conductor having a metal sheath covers the metal sheath with a gap provided on the outer periphery of the conductor core wire, and the gap is filled with inorganic powder. Electrical penetration sleeve for walls. 3. The electrically penetrating sleeve for a radiation shielding wall according to claim 1, wherein the insulated conductor inserted into the metal protection tube is a rubber/plastic insulated conductor inserted into the metal tube.