JPH038717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a handling mechanism for installing, replacing, and holding a nuclear instrumentation detector outside a nuclear reactor.

In order to measure the neutron flux distribution in a nuclear reactor from outside the reactor, it is necessary to install nuclear instrumentation detectors outside the reactor around the reactor vessel.

In this case, the handling mechanism for installing, replacing, and holding the detector at the measurement position has conventionally been the first one.
There is one shown in the figure. That is, as shown in FIG. 1, the conventional detector handling mechanism provides a detector exchange hole 2 in a living body shield 1. The detector exchange hole 2 vertically penetrates the interior of the biological shield 1, and its upper end communicates with an exchange hole entrance 4 that opens into the reactor cavity 3, and its lower end reaches the measurement space 5.

The detector 6 is inserted from the exchange hole entrance 4, suspended by a hanging rope 7, and descends inside the detector exchange hole 2 to reach the measurement space 5. After that, the detector 6 is inserted into the protection tube 8 in the measurement space 5. After that, the protective tube 8
is pushed by the pressing mechanism 9 and moves in parallel to the reactor vessel 11
is positioned at a measurement position close to the reactor core 12 and facing the reactor core 12. In this way, the neutron flux from the reactor core 12 is measured. When the detector 6 is to be taken out, the above procedure is reversed.

However, in the conventional detector handling mechanism configured in this manner, the detector installation and replacement operations must be performed within the reactor cavity 3 where the air dose rate is high, resulting in a high radiation exposure for the workers. Furthermore, since water is collected in the reactor cavity during fuel exchange, there is a drawback that the fuel exchange work and the detector installation/replacement work cannot be performed in parallel. Furthermore, since the detectors are hung and housed in the protection tube 8, it takes a lot of time to align them so that the front faces of the detectors face toward the reactor, which causes work delays. Furthermore, since the detector 6, protection tube 8, etc. are embedded in the biological shielding wall, there remains the problem that repair thereof is extremely difficult.

This invention was made in view of the above-mentioned circumstances, and it is possible to install and replace the detector in a place with a low radiation dose, thereby reducing the radiation exposure of workers. In addition, fuel exchange work and detector installation/replacement work can be performed in parallel, and the detectors can be easily aligned in the direction of the reactor, reducing work time and reducing maintenance costs. The purpose is to provide a mechanism for easily handling nuclear instrumentation detectors outside reactors.

Corresponding to this purpose, the handling mechanism of the nuclear instrumentation detector outside the reactor of the present invention is such that the handling mechanism connects the biological shield around the reactor with an exchange hole inlet/outlet located at a high position on the outer surface of the biological shield to a low point on the inner surface of the biological shield. a guide device disposed in the detector exchange hole to guide movement of the detector; and an upper end opening that is rotatably displaceable at the measurement position. a protection tube capable of receiving the detector;
The present invention is characterized by comprising a positioning device that performs positioning by rotationally displacing the protection tube, and an unlockable locking device that locks the protection tube at a measurement position.

Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment.

In FIGS. 2, 3, and 4, 20 is a detector handling mechanism for installing, replacing, and holding the detector. The detector handling mechanism 20 is provided with a detector exchange hole 23 formed through a biological shield 22 disposed around the reactor vessel 21 .

The upper end of the detector exchange hole 23 communicates with an exchange hole entrance/exit 24 formed on the outer surface of the biological shield 22, and the lower end of the detector exchange hole 23 is an opening on the inner surface of the biological shield 22 toward the reactor vessel 21. It communicates with a measurement space 25 located at a low position and formed to This measurement space 25 prepares a place for installing a detector 26 at a measurement position when measuring from outside the reactor. Exchange hole entrance 24
The open end of is opened and closed by a concrete plug 27. The inner surface of the detector exchange hole 23 is lined with a detector guide tube 28, and the measurement space 25 is a chamber hollowed out of the biological shield 22, and the biological shield wall in this part faces toward the reactor vessel 21. Although the end is open, it communicates with the detector guide tube 28 and is similarly lined to form a box 31. The lower end of the measurement space 25 can be opened and closed by a door 33. A guide rail 34 is disposed inside the detector guide tube 28 along the longitudinal direction.

A detector protection cylinder 35 is located within the measurement space 25 . The detector protection cylinder 35 is a cylindrical body with an open upper end and has a size that allows the detector 26 to be housed therein. The detector protection tube 35 is connected to the shaft 3 near the lower end.
6, it is rotatably displaceable, and is rotatably displaced to the vertical position to be located at the measurement position, and tilted to assume a posture capable of receiving the detector 26. A guide rail 37 (omitted in FIGS. 2 and 3) is provided inside the detector protection tube 35 along the longitudinal direction. Further, a window 38 is formed in the side wall of the detector protection cylinder 35 facing the reactor vessel 21 . Furthermore, the detector protection tube 35
A bracket 41 is attached to the outside of the side wall opposite the window. The detector 26 is connected to the cable 30
The detector can be suspended by itself and slide down inside the detector guide tube 28 due to its own weight.

A first lock piece 43 is provided on one side of the detector 26.
is attached, and a spacer 44 is attached to the opposite side. When the spacer 44 moves within the detector guide tube 28, it engages with the guide rail 34 to align the orientation of the detector 26,
Moreover, when it is housed in the detector protection tube 35, it engages with the guide rail 37 to align its directions.
The first lock piece 43 locks the window 3 of the detector protection tube 35 when the protection tube 35 is displaced to the vertical measurement position.
8, and the detector 26 is positioned at the measurement position.

The rotational displacement of the detector protection cylinder 35 about the shaft 36 is performed by a push rod 46. The push rod 46 passes through the biological shield 22, and its tip is connected to the bracket 41 via a pin 48 that is engaged with an elongated hole 47. The other end 51 of the push rod 46 extends outside the biological shield 22 and is provided with a mechanism (not shown) for pressing the push rod with a constant force.

Detector handling mechanism 20 configured in this way
The procedures for installing, replacing, and maintaining the detector using the detector are as follows.

To install the detector 26, after removing the concrete plug 27 which also serves as a shield from the outside of the biological shield 22, the detector 26 is guided to the detector protection tube 35 via the detector guide tube 28. When the detector 26 slides down inside the detector guide tube 28, the guide rail 34 and the spacer 44 engage, and the detector 2
Align the directions of 6. After the detector 26 descends through the detector guide tube 28, it is housed in the detector protection tube 35. When the detector 26 is housed in the detector protection tube 35, the guide rail 37 and the spacer 44 engage to align the orientation of the detector 26. After the detector 26 is housed in the detector protection tube 35, by pushing the push rod 46 from outside the living body shield 22, the detector protection tube 35 is rotationally displaced about the shaft 36, and the third
The first locking piece 43 and the second locking piece 45 are displaced to the vertical measurement position shown by the chain line in the figure.
and are engaged through window 38 to position detector 26 in the measurement position. The detector is fixed using the push rod 4.
6 is provided with a mechanism that presses the biological shield 22 with a constant force from outside, and is fixed by this mechanism. In this state, radiation measurements outside the reactor are performed. When replacing the detector 26, the installation process described above is reversed.

For maintenance of the detector protection tube 35, etc., please refer to the box 31.
This is done by opening the door 33.

In this type of handling mechanism for external nuclear instrumentation detectors, the detector 26 can be installed and replaced from outside the biological shielding wall without using the cavity, reducing radiation exposure of workers. In addition, the installation/replacement of this detector and the fuel exchange using the cavity can be done in parallel, which shortens the reactor work and shortens the reactor shutdown period. time can be increased. In addition, since the direction of the detector 26 can be automatically aligned using the guide rails 34 and 37 and the spacer 44, it can be set accurately without the need for any operation to set the front toward the reactor. can do. Moreover, the box body 3
When the bottom of 1 can be opened and closed, the detector protection tube 3
5. Maintenance of other equipment is easy, and countermeasures in case of failure are extremely easy.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing the handling mechanism of a conventional nuclear instrumentation detector outside the reactor, and Fig. 2 is a configuration diagram showing the handling mechanism of the nuclear instrumentation detector outside the reactor according to an embodiment of the present invention. An explanatory drawing, FIG. 3 is an enlarged configuration explanatory diagram showing a handling mechanism of a nuclear instrumentation detector outside a reactor according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram of a nuclear reactor according to an embodiment of the present invention. FIG. 2 is a cross-sectional configuration explanatory diagram showing a handling mechanism of the extra-core instrumentation detector. 20...detector handling mechanism, 21...reactor vessel, 23...biological shield, 24...detector exchange hole,
26...detector, 28...detector guide tube, 33...
... Door, 34 ... Guide rail, 35 ... Detector protection tube, 36 ... Shaft, 37 ... Guide rail, 38 ...
Window, 43...first lock piece, 43...spacer, 45...second lock piece, 46...push bar.

Claims (1)

[Scope of Claims] 1. Forming a detector exchange hole in the biological shield around the reactor, which reaches from an exchange hole entrance/exit located at a high position on the outer surface of the biological shield to a measurement position located at a low position on the inner surface of the biological shield, a guide device disposed in the detector exchange hole to guide the movement of the detector; a protective tube that is at the measurement position and has an opening at an upper end that can be rotated and is capable of receiving the detector; A handling mechanism for a nuclear instrumentation detector outside a nuclear reactor, characterized by comprising a positioning device that performs positioning through rotational displacement, and an unlockable locking device that locks the protection tube at a measurement position. 2. The locking device has a window formed through the side wall of the protective cylinder, a first locking piece is attached to the detector, and a second locking piece is attached to the fixed position of the measuring position. Claim 1, wherein the first locking piece and the second locking piece are configured to engage and lock through the window. Handling mechanism of the described nuclear instrumentation detector outside the reactor. 3. The positioning device is constituted by a push rod that passes through the living body shield, is connected to the protection tube at one end, and extends outside the living body shield at the other end. 1st term or 2nd term
Handling mechanism of the nuclear instrumentation detector outside the reactor described in Section 2.