JP3131166B2 - Beryllium reflector bending measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a bend of a beryllium reflector using a fuel element insertion hole for inserting a fuel element of a nuclear reactor.

[0002]

2. Description of the Related Art Heretofore, a beryllium reflector provided in a nuclear reactor has a gradually increasing bend as its use period becomes longer. For this reason, the bend of the beryllium reflector was measured by a dial gauge when replacing the fuel element.

Further, as described in Japanese Utility Model Application No. 60-76747 (Japanese Utility Model Application Laid-Open No. 61-190899), a distortion measuring device for a fuel channel equipped with a plurality of ultrasonic distance sensors is also known. . This strain measuring device includes a sensor holding frame having a length substantially equal to the length of the fuel channel in the reactor,
And a plurality of ultrasonic sensors arranged on the peripheral wall of the sensor holding frame. According to this strain measuring device, referring to the drawing, the fuel channel 7 is connected to the sensor holding frame 4.
At this time, the upper guide 5 serves as a guide means so that the outer surface of the sensor holding frame 4 does not come into contact with the inner surface of the fuel channel 7, so that each sensor and the opposing surface of the fuel channel 7 Is measuring the distance.

[0004]

However, according to the conventional beryllium reflector bending measuring device, the bending environment of the beryllium reflector is measured in a measuring environment such as a water depth of 6 m, a temperature of 35 ° C., and still water. Needed. Further, according to the conventional strain measuring device, the outer surface of the sensor holding frame and the inner surface of the fuel channel are prevented from coming into contact with each other, but the interval is not controlled to be constant, which may cause an error in the measured bending value. Is concerned.

The present invention has been made in view of the above-mentioned problems of the related art, and is a beryllium that can measure the bend of a beryllium reflector provided in a nuclear reactor efficiently without contact by a relatively easy operation. An object of the present invention is to provide a method for measuring the bending of a reflector.

[0006]

Means for Solving the Problems A method for measuring the bend of a beryllium reflector according to the present invention for achieving the above object, comprises:
An elongate support that can be inserted into a fuel element insertion hole provided in a core of a nuclear reactor and can be inserted into the fuel element insertion hole, and a plurality of distance sensors disposed in a longitudinal direction of the support. Using a bend measuring means having a tapered shape at the end of the support for insertion into the fuel element insertion hole. Along the longitudinal direction, inserted into the fuel element insertion hole, the taper portion formed on the support of the bending measuring means,
It is mounted on a tapered receiving portion formed at the bottom of the fuel element insertion hole, and the distance to the beryllium reflector is measured by the plurality of distance sensors.

[0007]

According to the bending measurement method of the present invention, a simple operation of inserting a support into a fuel element insertion hole at the time of replacement of a fuel element allows a plurality of distance sensors to measure the length of the beryllium reflector in the longitudinal direction. The amount of bending can be measured easily and with good workability.

An embodiment of the present invention is shown in FIGS. Ultrasonic sensors 3, 4, 5, 6, 7 and 8, 9, 10, as five distance sensors at equal intervals in the longitudinal direction of each of two orthogonal side surfaces 2 a, 2 b of the support 2 of the bending measuring device 1. 1
1 and 12 are provided. 2 orthogonal sides 2a, 2b
The reason why the ultrasonic sensor is provided is that two perpendicular sides of a beryllium reflector described later can be measured at a time. The tip of the support 2 is the tip 2 of the opposing surfaces 2d and 2c.
0 and 21 are formed in a tapered shape.
1 is fixed by a shaft 22. The tip portions 20 and 21 are formed in a tapered shape so that they can be easily guided to the fuel element insertion holes in the core. Ultrasonic measurement sensor 3,
4, 5, 6, 7, 8, 9, 10, 11, and 12, electrical wiring is drawn out from each of the wirings.
And is connected to a detector 24 as shown in FIG.

The end of the support 2 on the side of insertion into the fuel element insertion hole has a tapered step 26, and a small-diameter portion 25 having a smaller diameter from the step 26 toward the end. Is provided.

A core structure for housing a fuel element and a beryllium reflector is configured as shown in FIGS. 5 and 6, for example. The beryllium reflector, as shown in FIG.
The A-type beryllium reflector 31, the B-type beryllium reflector 32, and the C-type beryllium reflector 33 are assembled in four sets each, and the outer wall is formed in an arc shape. As shown in FIG. 6, a number of fuel element insertion holes 40 are provided. A tapered receiving portion 45 is formed at the bottom of the fuel element insertion hole 40 so that the tapered step 26 formed at the insertion side end of the support 2 can be placed thereon. The bending measurement device 1 is inserted into the outermost fuel element insertion hole 40 among these fuel element insertion holes 40 to perform measurement.

For example, when measuring the A-type beryllium reflector 31, as shown in FIG. 4, the bend measuring device 1 is inserted into the fuel element insertion hole 40a adjacent to the beryllium reflector 31 along the longitudinal direction thereof. FIG. 7 shows a state in which the bending measuring instrument 1 is inserted. Since the bending measuring device 1 is configured as described above, as apparent from FIG.
The tapered step 45 of the support 2 is
6 can always be placed at a predetermined position, so that a plurality of ultrasonic measurement sensors 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
And the distance between the beryllium reflector and the beryllium reflector 31 can be easily measured, and the measurement of the bending in the longitudinal direction of many beryllium reflectors can be efficiently performed.

As shown in FIG. 2, for example, an ultrasonic sensor 7 (represented by 7) has an ultrasonic sensor main body 42 fixed to a guide cylinder 41 fixed to the support 2 with a screw portion 42 a. ing. A delay member 4 is provided at the tip of the ultrasonic sensor 42.
3 are provided. The distance from the ultrasonic sensor body 42 to the measurement surface 31a of the beryllium reflector 31 via the delay member 43 is measured by ultrasonic echo. For example, as shown in FIG. 3, the ultrasonic echo includes a reflected wave S in which an oscillation echo transmitted from the sensor main body 42 is reflected on the delay member 43,
The distance between the distal end surface 43a of the delay member 43 and the measurement surface 31a is measured based on the delay time T with respect to the reflected wave B reflected on the measurement surface 31a of the beryllium reflector. The space between the delay member 43 and the beryllium reflector 31 is filled with light water. Then, assuming that the sound speed value of light water is V, the distance D is represented by D = １ ／ TV since the distance D is reciprocating.

In this way, each of the ultrasonic sensors 3, 4,
The distance D measured by 5, 6, 7, 8, 9, 10, 11, 12 is measured by the detector 24. Hole 40a for inserting fuel element
B-type beryllium reflector 32
The two beryllium reflectors 31 and 32 can be simultaneously measured in the longitudinal direction by inserting the A-type beryllium reflector 31 so that the side surface 2a faces the A-type beryllium reflector 31. According to this embodiment, there is an effect that the bending of the beryllium reflector, which is difficult to measure in the water of the nuclear reactor, can be measured by a simple operation of inserting it into the fuel element insertion hole.

The reason for using an ultrasonic sensor is that measurement in water is relatively easy and is advantageous in terms of heat resistance, size, and measurement accuracy. Sensors such as laser sensors, eddy current sensors, and contact electric micrometers are conceivable as changeable sensors other than ultrasonic sensors, but these sensors are difficult to measure in water and are relatively small in size. There are drawbacks such as large size and low measurement accuracy. On the other hand, the ultrasonic sensor is advantageous in terms of water resistance, heat resistance, sensor size, and measurement accuracy. In the present invention, it goes without saying that other types of sensors may be used instead of the ultrasonic sensors.

[0015]

As described above, according to the beryllium reflector bending measurement method of the present invention, a simple operation of inserting a support into a fuel element insertion hole provided in a core of a nuclear reactor, There is an effect that the bend in the longitudinal direction of the beryllium reflector can be measured efficiently with high accuracy and simple operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a bending measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the principle of measurement according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a reflection echo of the bending measurement device.

FIG. 4 is a schematic diagram showing a state at the time of measurement of the bending measuring instrument according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing an example of a configuration of a beryllium reflector provided in a reactor core of a nuclear reactor.

FIG. 6 is a schematic configuration diagram showing a fuel element insertion hole of a beryllium reflector of a nuclear reactor.

FIG. 7 is a schematic diagram showing a state in which a bending measuring instrument is inserted into a fuel element insertion hole.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bending measuring device (bending measuring device), 2 ... Support, 2a,
2b: Side surface, 3, 4, 5, 6, 7, 8, 9, 10, 12
... Ultrasonic sensor (distance sensor).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G21C 17/003 G01B 17/00 G01B 21/20 G21C 19/02

Claims (1)

(57) [Claims] An elongated support that can be inserted into a fuel element insertion hole provided in a reactor core of a nuclear reactor and can be inserted into the fuel element insertion hole, and is disposed in a longitudinal direction of the support. A plurality of distance sensors, and a bend measuring unit having a tapered shape at the end of the support inserted into the fuel element insertion hole. The bend measuring unit is provided in a reactor core. The tapered portion formed in the support for the bending measuring means is inserted into the fuel element insertion hole along the longitudinal direction of the beryllium reflector, and the tapered receiver formed at the bottom of the fuel element insertion hole. A method for measuring the bend of a beryllium reflector, wherein the bend is placed on a part and the distance to the beryllium reflector is measured by the plurality of distance sensors.