JP7234160B2 - Radiation detection device and its installation method - Google Patents

Description

An embodiment of the present invention relates to a radiation detection apparatus for detecting radiation in a nuclear reactor containment vessel and a method of installing the same.

In order to detect radiation in the reactor containment vessel, a radiation detector installed in the penetration part that penetrates the wall of the reactor containment vessel and a signal processing device installed outside the reactor containment vessel. is known. In this case, the radiation detector is inserted from the outside to the inside of the reactor containment vessel through the penetration portion of the reactor containment vessel.

JP 2011-80862 A

In recent years, there has been a demand for the provision of equipment necessary to cope with serious accidents caused by terrorism, such as intentional collisions of large aircraft with nuclear reactor buildings. In that case, a function to prevent damage to the containment vessel is required. Therefore, it is necessary to detect the radiation in the reactor containment vessel with a radiation detector and determine whether or not there is core damage in the reactor containment vessel.

Furthermore, when installing additional radiation detectors for the above serious accident, it is required to install multiple radiation detectors in one penetration without increasing the number of penetrations in the containment vessel. ing.

Radiation detectors need to be pulled out of the reactor containment vessel for maintenance and reinsertion during periodic inspections, etc., and it is required that multiple radiation detectors can be easily inserted and pulled out. Furthermore, it is necessary to ensure sufficient seismic resistance, assuming that an earthquake will occur while radiation detection is being performed by inserting a radiation detector.

The embodiments of the present invention have been conceived in view of this situation, and the object thereof is to enable highly reliable installation of a plurality of radiation detectors for detecting radiation in the reactor containment vessel. It is to make

In order to solve the above problems, a radiation detection apparatus according to an embodiment is a radiation detection apparatus that can be inserted into and pulled out of a penetration portion of the reactor containment vessel from the outside of the reactor containment vessel. first and second ionization chamber detectors inserted and arranged adjacent to each other in parallel within a reactor containment vessel; first and second cables extending through the penetration of the containment vessel, a holder that supports the first and second ionization chamber detectors and is movable in the penetration direction of the penetration of the reactor containment vessel; and an insulating member held by the holder and arranged between the first and second ionization chamber detectors to electrically insulate between the first and second ionization chamber detectors. , the insulating member is disposed between the first and second ionization chamber detectors so as to extend over the entire portion where the first and second ionization chamber detectors face each other; a metal plate disposed to span an entire portion between the first and second ion chamber detectors, wherein the insulating member extends across an entire portion between the first ion chamber detector and the metal plate; and a second isolation and insulation member extending over the entire portion between the second ionization chamber detector and the metal plate.

Further, a radiation detection device installation method according to an embodiment is a radiation detection device installation method for detecting radiation in a nuclear reactor containment vessel, comprising: a first ionization chamber detector to which a first cable is connected; A second ionization chamber detector to which a second cable is connected is arranged in parallel and detachably held by a holder in a state of being electrically insulated from each other by an insulating member, and the first and second ionization chamber detectors are arranged in parallel. an inserting step of inserting the box detector, the holder, and the insulating member into the reactor containment vessel from the outside of the penetration portion of the reactor containment vessel so as to be able to be pulled out; a connecting step of detachably connecting the first and second cables to the signal processing unit , wherein the insulating member is disposed between the first and second ionization chamber detectors; A second ion chamber detector is arranged to extend across the portion facing each other, and the holder is a metal plate arranged to extend across the portion between the first and second ion chamber detectors. wherein the insulating member comprises a first isolation insulating member extending over an entire portion between the first ion chamber detector and the metal plate; and a second isolation insulation member extending over the entire intermediate portion .

According to the embodiments of the present invention, a plurality of radiation detectors for detecting radiation within the reactor containment vessel can be installed with high reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation cross-sectional view schematically showing a state in which a radiation detection apparatus according to a first embodiment of the present invention is installed in a nuclear reactor containment vessel; FIG. 2 is an enlarged vertical cross-sectional view showing the vicinity of the detector and the reactor containment vessel penetration part in FIG. 1 ; FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. 2; FIG. 3 is an enlarged cross-sectional view of part IV in FIG. 2 ; FIG. 5 is an enlarged cross-sectional view showing a push-out mechanism and its vicinity of a radiation detection apparatus according to a second embodiment of the present invention; FIG. 11 is an enlarged cross-sectional view showing a push-out mechanism and its vicinity of a radiation detection apparatus according to a third embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and repeated explanations are omitted.

[First Embodiment]
FIG. 1 is an elevation cross-sectional view schematically showing a state in which a radiation detection apparatus according to a first embodiment of the present invention is installed in a nuclear reactor containment vessel. FIG. 2 is an enlarged vertical cross-sectional view showing the vicinity of the detector and the reactor containment vessel penetration part in FIG. 1 . 3 is an enlarged cross-sectional view taken along line III--III in FIG. 2, and FIG. 4 is an enlarged cross-sectional view of a portion IV in FIG.

The interior of the reactor containment vessel 10 is partitioned into a dry well 11 and a wet well 12 . A reactor pressure vessel 13 is installed in the dry well 11 . Contained within the wetwell 12 is a pressure suppression pool 14 .

The radiation detection apparatus 15 has first and second ionization chamber detectors (hereinafter also simply referred to as “detectors”) 161 and 162 and first and second signal processing units 171 and 172 . The first ionization chamber detector 161 and the first signal processing unit 171 are connected by two parallel first cables 181, and the second ionization chamber detector 162 and the second It is connected to the signal processing unit 172 by two second cables 182 parallel to each other.

The ionization chamber detectors 161 and 162 are arranged inside the reactor containment vessel 10 (inside the drywell 11 in the illustrated example), and the signal processing units 171 and 172 are arranged outside the reactor containment vessel 10 .

A penetrating portion 20 is provided so as to penetrate the wall of the containment vessel 10, and a cylindrical tubular member 30 whose axis is the penetrating direction (X direction) of the penetrating portion 20 is inserted and fixed into the penetrating portion 20. It is The tip of the tubular member 30 inside the reactor containment vessel 10 forms a closed end 31 , and the tip of the tubular member 30 outside the reactor containment vessel 10 forms an open end 32 . The tubular member 30 forms a pressure boundary together with the wall of the containment vessel 10 . An open end flange 33 is fixed to the open end 32 of the tubular member 30 .

The tubular member 30 forms a pressure boundary, but allows the radiation to be detected by the ionization chamber detectors 161 and 162 to pass therethrough. Therefore, although the inside of the tubular member 30 is outside the pressure boundary, the ionization chamber detectors 161 and 162 installed inside the tubular member 30 can detect the radiation inside the reactor containment vessel 10 .

In the following description, the expression that the ionization chamber detectors 161, 162 are placed or inserted into the reactor containment vessel 10 means that radiation within the reactor containment vessel 10 can be detected even outside the pressure boundary. Means to place or insert at a position. The expression "outside the containment vessel 10" does not mean "outside the pressure boundary", but means a position outside the wall of the containment vessel 10 and outside the cylindrical member 30.

The ionization chamber detectors 161 and 162 can be inserted into the cylindrical member 30 installed in one penetration 20 and can be pulled out to the outside of the containment vessel 10 . The cables 181 , 182 extend inside the cylindrical member 30 installed inside the penetrating portion 20 .

The signal processing units 171 and 172 include, for example, preamplifiers, logarithmic dose rate meters, displays, recorders, and the like. The first signal processing unit 171 is placed in a control room used during normal operation, and the second signal processing unit 172 is placed in a special facility for dealing with severe accidents, separate from the control room. good too. As another example, the first signal processing section 171 and the second signal processing section 172 can be arranged in the same control room for redundancy.

This radiation detector 15 can measure radioactive gas generated in the reactor containment vessel 10, for example, during a severe accident at a nuclear power plant.

Two ionization chamber detectors 161 , 162 are arranged side by side adjacent to each other near closed end 32 within tubular member 30 within reactor containment vessel 10 . The direction in which the two ionization chamber detectors 161 and 162 are arranged is the Y direction. The ionization chamber detectors 161 and 162 have substantially cylindrical external shapes and are arranged in parallel with each other with the axis of the tubular member 30 interposed therebetween so that their axes are parallel to the axis of the tubular member 30 (X direction). are arranged as follows.

A portion of each of the first and second cables 181 and 182 that is inside the tubular member 30 is composed of a Mineral Insulated (MI) coaxial cable (hereinafter referred to as an "MI cable"). The MI cable is excellent in radiation resistance, moisture resistance, and heat resistance, but has high rigidity and is difficult to bend and stretch.

Each of the four MI cable portions in the tubular member 30 among the cables 181 and 182 of the first and second systems is split longitudinally into two MI cable pieces 35a and 35b. , are detachably connected by first and second relays 361 and 362 . Two first cable pieces 35a and two second cable pieces 35b constituting two first cables 181 connected to the first ionization chamber detector 161 are connected to a first repeater 361. are connected longitudinally by Similarly, the two second cable pieces 35a and the two second cable pieces 35b constituting the two second cables 182 connected to the second ionization chamber detector 162 are connected to the second They are longitudinally connected by a repeater 362 .

The ionization chamber detectors 161, 162, the cable pieces 35a, 35b and the relays 361, 362 are held by the holder 40. FIG. A retaining flange 41 is attached to the outer end of retainer 40 . Retaining flange 41 is removably attached to open end flange 33 by a plurality of bolts 42 .

Attached to the retaining flange 41 are first and second external repeaters 801 , 802 .

A portion of the first cable 181 connected to the first signal processing portion 171 outside the penetration portion 20 and a second signal processing portion 172 outside the penetration portion 20 of the second cable 182 The part connected to the is not a MI cable, but a conventional soft cable.

The first external repeater 801 separates the two second cable pieces 35b of the first cable 181 and the two first soft cables 811 of the first cable 181. It is possible to connect Similarly, the second external repeater 802 includes two second cable piece 35b portions of the second cable 182 and two second soft cables 812 of the second cable 182. are separably connected.

The holder 40 supports the metal plate 45 by a flat metal plate 45 arranged to separate the first ionization chamber detector 161 and the second ionization chamber detector 162 and the holding flange 41 . and a support bar 70 . The metal plate 45 is arranged between the first ionization chamber detector 161 and the second ionization chamber detector 162 so as to extend over the entire area where they face each other. The support rod 70 extends in the X direction, and a first support rod piece 71a and a second support rod piece 71b are connected by a relay flange 73 so as to be separable in the axial direction. A first support bar piece 71 a is connected to the metal plate 45 and a second support bar piece 71 b is connected to the retaining flange 41 .

The retainer 40 further includes a first mounting bracket 461 for mounting the first ion chamber detector 161 to the metal plate 45 and a second mounting for mounting the second ion chamber detector 162 to the metal plate 45. and a fitting 462 . The first mounting bracket 461 and the second mounting bracket 462 are detachably attached to the metal plate 45 with a plurality of bolts 50 .

An insulating member is arranged to provide electrical isolation between the first ionization chamber detector 161 and the second ionization chamber detector 162 . The insulating members consist of a first separating insulating member 471 extending over the entire area between the first ionization chamber detector 161 and the metal plate 45 where they face each other, and a second ionization chamber detector 162 and the metal plate 45 . A second isolation insulating member 472 extending over the entire portion where they face each other, and a first mounting bracket insulating member 481 interposed between the first ionization chamber detector 161 and the first mounting bracket 461. , and a second fitting isolation member 482 interposed between the second ion chamber detector 162 and the second fitting 462 .

The holder 40 is further provided with a plurality of legs 52 for supporting the metal plate 45 against the inner wall of the tubular member 30 and protruding radially outward at intervals in the circumferential direction. A wheel 54 is attached to the tip of each leg 52 via a push-out mechanism 53 . The wheels 54 rotate in contact with the inner wall of the tubular member 30 when the retainer 40 is inserted into or withdrawn from the tubular member 30 (moving in the X direction) to facilitate insertion or withdrawal. arranged to be done.

The legs 52 are shown extending in the Y direction in FIGS. 2 and 4 and extending in a radial direction different from the Y direction in FIG. It suffices if they are provided at intervals from each other.

The push-out mechanism 53 includes a sliding member 56 and push-out bolts 57, as shown in FIG. The push bolt 57 is arranged so that its axial direction is in the X direction. The contact surface between the sliding member 56 and the tip of the leg 52 forms an inclined sliding surface 58 that is inclined with respect to the X direction. , and the sliding member 56 moves radially. Thereby, the positional relationship between the inner wall of the tubular member 30 and the wheel 54 can be adjusted on site. As a result, the ionization chamber detectors 161 and 162 can be smoothly inserted into or pulled out from the cylindrical member 30, and the ionization chamber detectors 161 and 162 can be reliably supported during an earthquake.

Furthermore, as shown in FIG. 4 , a recess 60 is formed at the tip of the sliding member 56 , and a plate-like elastic member 61 is fixed so as to straddle the recess 60 . The wheel 54 is attached to the center of the elastic member 61 in the X direction. With such a configuration, the elastic deformation of the elastic member 61 allows the wheels 54 to flexibly move in the Y direction. As a result, the ionization chamber detectors 161 and 162 can be smoothly inserted into or pulled out from the cylindrical member 30, and the ionization chamber detectors 161 and 162 can be reliably supported during an earthquake.

As described above, the legs 52, the sliding member 56, the wheels 54, and the like have been described as supporting the metal plate 45 against the inner wall of the cylindrical member 30. The structure for supporting the support rod 70 against the inner wall is also the same. It is the same.

Next, a procedure for installing the first and second ionization chamber detectors 161 and 162 of the radiation detection apparatus of this embodiment inside the reactor containment vessel 10 inside the tubular member 30 will be described. First, outside the containment vessel 10, the first and second ionization chamber detectors 161 and 162 are attached with the first cable piece 35a, which is part of the first and second cables, and separated. It is attached to the metal plate 45 together with the insulating members 471 and 472 and the like. The metal plate 45 is connected to the first support bar piece 71a.

Next, starting with the first and second ionization chamber detectors 161 and 162, the first and second ionization chamber detectors 161 and 162, the first support rod piece 71a, and the first cable piece 35a is inserted into the tubular member 30 from the open end 32 of the tubular member 30 .

When only part of the first cable piece 35a is inserted into the tubular member 30, the first and second repeaters 361 and 362 cause the first cable piece 35a and the second cable piece 35b to to connect. A relay flange 73 connects the first support rod piece 71a and the second support rod piece 71b. This connection work is performed outside the containment vessel 10 in the reactor building (not shown).

Next, the first and second ionization chamber detectors 161 and 162, the first cable piece 35a and the second cable piece 35b are further inserted into the cylindrical member 30. As shown in FIG.

Once the first and second ionization chamber detectors 161, 162 have reached the predetermined measurement position, the retaining flange 41 and the open end flange 33 are joined together by bolts 42. As shown in FIG.

After that, the second cable piece 35b and the first soft cable 811 that constitute the first cable 181 are joined via the first external repeater 801, and the first soft cable 811 and the first soft cable 811 are joined together. is connected to the signal processing unit 171 of . Similarly, the second cable piece 35b constituting the second cable 182 and the second soft cable 812 are joined via the second external repeater 802, and the second soft cable 812 and the second soft cable 812 are joined together. 2 signal processing unit 172 is connected.

The procedure for pulling out the first and second ionization chamber detectors 161 and 162 from the inside of the tubular member 30 to the outside of the reactor containment vessel 10 for maintenance is the reverse of the insertion procedure described above.

In this embodiment, while the first and second ionization chamber detectors 161 and 162 are being inserted into the tubular member 30, the first and second relays 361 and 362 connect the first cable piece 35a and the first cable piece 35a. It connects with the second cable piece 35b. Therefore, even if the space outside the reactor containment vessel 10 in the reactor building is narrow, and even if an MI cable that is difficult to bend and stretch is used, the first and second ionization chamber detectors 161 and 162 can be used. It can be installed at an installation location inside the tubular member 30 . They can also be pulled out for maintenance.

In addition, the operation of installing the first and second ionization chamber detectors 161 and 162 at the installation locations within the cylindrical member 30 and the operation of pulling them out can be performed smoothly by the wheels 54 and the push-out mechanism 53. , seismic resistance can be secured.

In addition, since an insulating member is arranged to electrically insulate between the first ionization chamber detector 161 and the second ionization chamber detector 162, even if an earthquake occurs, the first ionization There is no electrical contact between the box detector 161 and the second ionization chamber detector 162, and the functions of the first and second ionization chamber detectors 161, 162 are maintained.

[Second embodiment]
FIG. 5 is an enlarged cross-sectional view showing the push-out mechanism and its vicinity of the radiation detection apparatus according to the second embodiment of the present invention, and is a view corresponding to FIG. 4 in the first embodiment.

This embodiment is a modification of the first embodiment, and a strain sensor 85 is attached to a plate-like elastic member 61 . A signal cable 86 is connected to the strain sensor 85 and extends out of the containment vessel 10 through the open end 31 of the tubular member 30 (see FIG. 2). Other configurations are the same as those of the first embodiment.

According to this embodiment, the degree of deformation of the elastic member 61 can be measured by the output of the strain sensor 85, thereby. The strength of the force with which the wheels 54 push the inner wall of the tubular member 30 can be measured. Based on that information, the push bolts 57 can be adjusted to hold the ion chamber detectors 161, 162 with optimum force.

[Third Embodiment]
FIG. 6 is an enlarged cross-sectional view showing a push-out mechanism and its vicinity of a radiation detection apparatus according to a third embodiment of the present invention, and is a view corresponding to FIG. 5 in the second embodiment.

This embodiment is a modification of the second embodiment, and the sliding member 56a has a rod-shaped abutting portion 90 projecting in the X direction toward the inner surface of the closed end portion 31 of the tubular member 30. As shown in FIG. A spring 91 is arranged between the leg 52 and the sliding member 56a, and the sliding member 56a is biased by the spring 91 toward the inner surface of the closed end portion 31 of the tubular member 30. As shown in FIG. In this embodiment, push bolt 57 (see FIGS. 4 and 5) is not present. Other configurations are the same as those of the second embodiment.

In this embodiment, when the ionization chamber detectors 161 and 162 are installed in the cylindrical member 30, the holder 40 with the ionization chamber detectors 161 and 162 attached is pushed into the cylindrical member 30 (FIG. 2). etc.). The leg 52 is then pushed in the direction of arrow A in FIG. When the tip of the abutting portion 90 hits the inner surface of the closed end portion 31 of the tubular member 30, the abutting portion 90 is pushed in the direction of arrow B, the spring 91 is compressed, and the sliding member 56a moves relative to the leg 52. move in the direction of arrow B. At that time, since the sliding member 56a slides along the inclined sliding surface 58, the wheel 54 moves in the direction of the arrow C toward the inner surface of the cylindrical member 30. As shown in FIG. As a result, the wheels 54 are pressed toward the inner surface of the tubular member 30 , and the ionization chamber detectors 161 and 162 are reliably supported by the tubular member 30 .

[Other embodiments]
In the embodiment described above, two ionization chamber detectors 161 and 162 are arranged in one penetration portion 20 . As another example, a configuration in which three or more ionization chamber detectors are arranged in one penetration portion 20 may be employed. In that case, a metal plate, a separating insulating member, and the like may be arranged so as to separate three or more ionization chamber detectors from each other. Also, three or more cables are connected to the ionization chamber detector.

In the above description, it is assumed that the portions of the cables 181 and 182 of the first and second systems, which are located inside the cylindrical member 30, are composed of MI cables. As another example, it is conceivable that the cables 181 of the first system are all conventional soft cables, and the portion of the cables 182 of the second system inside the cylindrical member 30 is composed of an MI cable. In this case, the first ionization chamber detector and first signal processing section may be used for normal operation, and the second ionization chamber detector and second signal processing section may be used for severe accident.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Reactor containment vessel, 11... Dry well, 12... Wet well, 13... Reactor pressure vessel, 14... Pressure suppression pool, 15... Radiation detector, 20... Penetrating part, 30... Cylindrical member, 31... Closure End 32 Open end 33 Open end flange 35a, 35b Cable piece 40 Holder 41 Holding flange 42 Bolt 45 Metal plate 52 Leg 53 Extruding mechanism 54 Wheel 56, 56a Sliding member 57 Push bolt 58 Inclined sliding surface 60 Recess 61 Elastic member 70 Supporting rod 71a, 71b Supporting rod piece 73 Relay flange , 85... Strain sensor 86... Signal cable 56a... Sliding member 90... Abutment part 91... Spring 161, 162... Ionization chamber detector (detector) 171, 172... Signal processing unit 181, 182... Cable 461, 462... Mounting bracket 471, 472... Separating insulating member (insulating member) 481, 482... Mounting bracket insulating member (insulating member) 801, 802... External repeater 811, 812... Soft cable

Claims (9)

A radiation detection device that can be inserted and pulled out from the outside of a nuclear reactor containment vessel by arranging it in a penetration portion of the nuclear reactor containment vessel,
first and second ionization chamber detectors inserted and arranged adjacent to each other in parallel within the reactor containment vessel at the time of the insertion;
first and second cables that are connected to the first and second ionization chamber detectors, respectively, and extend into penetrations of the reactor containment vessel when inserted;
a holder that supports the first and second ionization chamber detectors and is movable in a penetrating direction of the penetrating portion of the reactor containment vessel;
an insulating member held by the holder and arranged between the first and second ionization chamber detectors to electrically insulate between the first and second ionization chamber detectors;
has
The insulating member is arranged between the first and second ionization chamber detectors so as to extend over the entire portion where the first and second ionization chamber detectors face each other,
the retainer includes a metal plate positioned to span the entire portion between the first and second ionization chamber detectors;
The insulating member includes a first isolation insulating member extending over the entire portion between the first ionization chamber detector and the metal plate, and a portion between the second ionization chamber detector and the metal plate. and a second isolating and insulating member extending over the entire area . The holder includes a metal first mounting bracket for mounting the first ionization chamber detector to the metal plate, and a metal mounting bracket for mounting the second ionization chamber detector to the metal plate. a second mounting bracket;
The insulating member comprises: a first mounting bracket insulating member disposed between the first ion chamber detector and the first mounting bracket; and a second fitting insulating member positioned between the fitting and the fitting. 3. The method of claim 1 or 2, wherein at least one of said first and second cables comprises an MI cable directly connected to at least one of said first and second ion chamber detectors. Radiation detector. A radiation detection device that can be inserted and pulled out from the outside of a nuclear reactor containment vessel by arranging it in a penetration portion of the nuclear reactor containment vessel,
first and second ionization chamber detectors inserted and arranged adjacent to each other in parallel within the reactor containment vessel at the time of the insertion;
first and second cables that are connected to the first and second ionization chamber detectors, respectively, and extend into penetrations of the reactor containment vessel when inserted;
a holder that supports the first and second ionization chamber detectors and is movable in a penetrating direction of the penetrating portion of the reactor containment vessel;
an insulating member held by the holder and arranged between the first and second ionization chamber detectors to electrically insulate between the first and second ionization chamber detectors;
has
a tubular member having a closed end located inside the reactor containment vessel and an open end located outside the reactor containment vessel, and forming a pressure boundary together with the reactor containment vessel; It penetrates the penetration part of the reactor containment vessel,
The first and second ionization chamber detectors are configured to be insertable and withdrawable from the tubular member in parallel from the open end ,
a wheel attached to the retainer and rotatable in contact with the inner surface of the tubular member when the retainer moves along the inner surface of the tubular member in the penetrating direction of the penetrating portion;
a push-out mechanism attached to the holder and capable of pushing the wheel toward the inner surface of the tubular member;
The radiation detection apparatus, wherein the push-out mechanism includes an elastic member that pushes the wheel toward the inner surface of the tubular member. 5. The radiation detector according to claim 4 , further comprising a strain sensor attached to said elastic member. The pushing mechanism is
a sliding member that protrudes toward the inner surface of the closed end portion and has an abutting portion whose tip can contact the inner surface of the closed end portion and that is slidable on an inclined sliding surface between the holder;
a spring mounted between the retainer and the sliding member for urging the sliding member such that the tip of the abutting portion is pressed against the inner surface of the closed end;
has
When the retainer is moved toward the inner surface of the closed end, the sliding member is pushed toward the closed end via the spring, and the tip of the abutting portion moves toward the closed end. The slide member is pressed against the inner surface of the tubular member and is pushed out toward the inner surface of the cylindrical member by sliding on the inclined sliding surface. The radiation detection apparatus according to claim 4 or 5 . The first cable is
a plurality of longitudinally separable and connectable cable pieces;
a repeater capable of longitudinally separating and connecting the plurality of cable pieces;
7. The radiation detecting apparatus according to any one of claims 1 to 6 , comprising: A method for installing a radiation detection device for detecting radiation in a nuclear reactor containment vessel,
A first ionization chamber detector to which a first cable is connected and a second ionization chamber detector to which a second cable is connected are held in parallel and electrically insulated from each other by an insulating member. The first and second ionization chamber detectors, the holder, and the insulating member are detachably held by a tool, and pulled out from the outside of the penetration portion of the reactor containment vessel to the inside of the reactor containment vessel. an inserting step of inserting the
a connection step of detachably connecting the first and second cables to a signal processing unit arranged outside the reactor containment vessel;
has
The insulating member is arranged between the first and second ionization chamber detectors so as to extend over the entire portion where the first and second ionization chamber detectors face each other,
the retainer includes a metal plate positioned to span the entire portion between the first and second ionization chamber detectors;
The insulating member includes a first isolation insulating member extending over the entire portion between the first ionization chamber detector and the metal plate, and a portion between the second ionization chamber detector and the metal plate. a second isolation insulation member extending therethrough;
A radiation detection device installation method characterized by: A method for installing a radiation detection device for detecting radiation in a nuclear reactor containment vessel,
A first ionization chamber detector to which a first cable is connected and a second ionization chamber detector to which a second cable is connected are held in parallel and electrically insulated from each other by an insulating member. The first and second ionization chamber detectors, the holder, and the insulating member are detachably held by a tool, and pulled out from the outside of the penetration portion of the reactor containment vessel to the inside of the reactor containment vessel. an inserting step of inserting the
a connection step of detachably connecting the first and second cables to a signal processing unit arranged outside the reactor containment vessel;
has
a tubular member having a closed end located inside the reactor containment vessel and an open end located outside the reactor containment vessel, and forming a pressure boundary together with the reactor containment vessel; It penetrates the penetration part of the reactor containment vessel,
The first and second ionization chamber detectors are configured to be insertable and withdrawable from the tubular member in parallel from the open end,
a wheel attached to the retainer and rotatable in contact with the inner surface of the tubular member when the retainer moves along the inner surface of the tubular member in the penetrating direction of the penetrating portion;
a push-out mechanism attached to the holder and capable of pushing the wheel toward the inner surface of the tubular member;
A method of installing a radiation detecting apparatus, wherein the pushing mechanism includes an elastic member that pushes the wheel toward the inner surface of the cylindrical member.

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