JP2983265B2 - Fuel channel corrosion measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial Application Field) The present invention relates to a fuel channel corrosion measuring device for remotely measuring a surface corrosion amount of a fuel channel in a fuel pool of a nuclear power plant. About.

(Prior art) Conventionally, as a device for measuring the amount of corrosion of the surface of a fuel channel, a device in which a contact type oxide film thickness measuring sensor such as an eddy current sensor is attached to the tip of a long pole has been put into practical use. Have been. Then, when measuring the amount of corrosion of the fuel channel using this measuring device, after placing the fuel channel on the channel attaching / detaching machine in the fuel pool, the long pole is brought close to the fuel channel, and the wire or air pressure is used. A method of pressing a contact-type oxide film thickness measuring sensor attached to the tip of a long pole against a fuel channel is adopted.

By the way, in this device, in order to measure the fuel channel upright similarly to the storage state in the fuel pool,
The sensor is mounted horizontally on the lower end of a vertically suspended elongate pole, and the upper end of the elongate pole is rotatably supported so that it can be pressed or separated from the fuel channel.

(Problems to be Solved by the Invention) In the conventional fuel channel corrosion measuring device, only the fuel channel surface corresponding to the lower end position of the long pole can be measured.
It is necessary to move the channel detacher up and down and rotate the channel detacher so that the surface to be measured faces the sensor side, which increases the working time per fuel channel and increases the radiation exposure of the measurer. There's a problem.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a fuel channel corrosion measuring device that can efficiently measure in a short time.

[Configuration of the invention]

(Means for Solving the Problem) A corrosion measurement device for a fuel channel according to the present invention is erected in a fuel pool in order to solve the above-mentioned problem,
A cylindrical device frame provided so that a fuel channel can be inserted from an upper position to an arbitrary position, and a positioning mechanism provided on the device frame for sandwiching a diagonal diagonal portion from both sides and positioning the fuel channel around an axis. And provided on the device frame, close to the positioned fuel channel and in close contact with the surface, the amount of surface corrosion of the fuel channel,
A sensor that can be measured, wherein the positioning mechanism includes a corner guide roller located on one side of a diagonal diagonal portion of the fuel channel, and a corner guide roller located on the other side of the diagonal diagonal portion. And a V-shaped arm which is remotely operated so as to be able to move forward and backward.

(Operation) In the fuel channel corrosion measuring device according to the present invention, the fuel channel is inserted from above into a cylindrical device frame erected in the fuel pool, and the amount of insertion is adjusted to measure the axial direction. Point positioning is performed.

On the other hand, the diagonal corners of the fuel channel inserted into the device frame are clamped from both sides by the positioning mechanism, and positioning around the axis is performed. After positioning, the sensor approaches the fuel channel and comes to the surface. Adhere,
The amount of surface corrosion of the fuel channel is measured. Since this sensor can measure the amount of corrosion of the surface of the fuel channel, there is no need to move the fuel channel in the circumferential direction, and as a result, the amount of corrosion at all measurement points can be measured simply by moving the fuel channel up and down. Measurement can be performed, and efficient measurement can be performed in a short time.

Hereinafter, an embodiment of a fuel channel corrosion measuring apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a fuel channel corrosion measuring device according to the present invention. As shown in FIG. 2, the corrosion measuring device 1 is a control device which is already provided at the bottom of a fuel pool 2. It is inserted into the rod / damaged fuel storage rack 3 and is shared with it.

As shown in FIGS. 1 to 3, the corrosion measuring device 1 includes a rectangular cylindrical device frame 6 into which a fuel channel 4 can be inserted from above using a fuel exchanger 5. The upper end of the device frame 6 A roller guide 7 that guides each outer surface of the fuel channel 4 is rotatably attached to the portion, and a hanging rope 9 is attached via a hanging bracket 8.

Further, as shown in FIGS. 1, 3 and 4, for example, two corner guide rollers 11 located at one of the diagonal corners of the fuel channel 4 And a positioning mechanism 10 having a V-shaped tip 12 located on the other side. The arm
Numeral 12 has a V-shaped guide surface at the tip which can be engaged with the corner of the fuel channel 4. The arm 12 is moved forward and backward by the driving of the air cylinder 13, and is moved forward and backward toward the corner guide roller 11 by remote control. Then, each of these positioning mechanisms 10
Holds the diagonal diagonal of the fuel channel 4 from both sides,
The fuel channel 4 is positioned around the axis.

As shown in FIGS. 1, 3, and 5, four sets of sensor mechanisms 14 for detecting the corrosion thickness of the four side surfaces of the fuel channel 4 are provided at intermediate positions in the vertical direction of the two positioning mechanisms 10, respectively. Are provided at 90 ° intervals in the circumferential direction so that the amount of surface corrosion of the fuel channel 4 can be simultaneously measured over the entire circumferential direction.

As shown in FIGS. 5 and 6, each sensor mechanism 14 includes an air cylinder 15 fixed to the device frame 6, a sensor mounting block 16 fixed to the tip of a rod 15a of the air cylinder 15, and a sensor holder. A contact type sensor 18 fixed to 17 is provided, and a spring 19 for connecting the sensor holder 17 and the sensor mounting block 16 and urging the contact type sensor 18 toward the distal end side is provided. By the urging force of the spring 19, the sensor 19 passes through the mounting hole 20 provided in the sensor mounting block 16 and protrudes toward the distal end. As a result, as shown in FIG.
Even if the surface of the sensor is not parallel to the sensor mounting block 16, the posture of the contact type sensor 18 is corrected against the urging force of the spring 19 so that the tip can always be in close contact with the surface of the fuel channel 4. Has become.

An air hose 21 drawn from each air cylinder 13 and 15 and a sensor cable 22 drawn from each contact type sensor 18
Is connected to a controller 23 on the operating floor, as shown in FIG. 2, which controls the height of the fuel channel 4 from the refueling machine 5 which axially positions the corrosion measurement point. The sensor signal and the measurement output signal from each contact sensor 18 are input, and the relationship between the measurement position and the corrosion amount is arranged and output.

In FIGS. 1 and 3, reference numeral 24 is provided at the lower end of the apparatus frame 6 to fit the hole in the bottom of the fuel rod / broken fuel storage rack 3 to make the corrosion measuring apparatus 1 self-standing. It is a support base.

 Next, the operation of the present embodiment will be described.

The oxide film formed on the surface of the fuel channel 4 is zirconium oxide (ZrO2), the thickness of which grows at a maximum of 20 μm / year, and comes off when it reaches 100 to 180 μm. The corrosion measuring device 1 according to the present embodiment measures the thickness of the zirconium oxide.

In this measurement, first, the fuel channel 4 is lifted by the fuel exchanger 5 and inserted into the apparatus frame 6 of the corrosion measuring apparatus 1. The measurement points of the amount of corrosion are set at about 10 points in the axial direction of the fuel channel 4.
By raising and lowering the fuel channel 4 at
The elevating position is measured by the pull-out length of the rope suspending the fuel channel 4.

In this way, the fuel channel 4 is connected to the device frame 6
, The fuel channel 4 is guided by the roller guides 7 from four directions, smoothly inserted into the apparatus frame 6, and is prevented from contacting the inner surface of the apparatus frame 6.

Once the fuel channel 4 has been inserted to the proper position,
The air cylinder 13 extends to move the arm 12 closer to the corner guide roller 11. Then, the diagonal corners of the fuel channel 4 are sandwiched from both sides by the corner guide roller 11 and the arm 12, and the positioning of the fuel channel 4 around the axis is performed by the positioning mechanism 10. Normally, this position is such that the four sides of the fuel channel 4 have four sets of sensor mechanisms 14.
It is a position facing in parallel with.

After the fuel channel 4 is positioned, the air cylinder 15 is extended, and each contact type sensor 18 approaches the fuel channel 4 and comes into close contact with its surface. At this time, as shown in FIG. 6, even if the contact type sensor 18 and the surface of the fuel channel 4 are not parallel, the contact type
The deviation is automatically corrected against the urging force, so that the contact type sensor 18 can always be brought into close contact with the surface of the fuel channel 4.

The output value of the contact-type sensor 18 becomes a constant value when it comes into close contact with the surface of the fuel channel 4, and if this value does not change for a predetermined time, it is taken into the controller 23 as a measured value.

The controller 23 performs signal conversion and arithmetic processing based on the measured value and the signal of the elevation position from the refueling machine 5 to arrange the relationship between the measurement position and the amount of corrosion and store it in the storage circuit.

Since the four sides of the fuel channel 4 are simultaneously measured by the four sets of sensor mechanisms 14, the measurement of all the measurement points can be performed only by raising and lowering the fuel channel 4 by the fuel exchanger 5.

In the above-described embodiment, the case where four sets of sensor mechanisms 14 are driven by four different air cylinders 15 has been described. However, four sets of sensor mechanisms 14 are driven by one air cylinder 15. You may.

Also, four sets of sensor mechanisms 14 are not provided, for example, two sets are provided at 180-degree intervals. In the first measurement, measurement is performed on two sides of the fuel channel 4, and then the sensor mechanism 14 is turned around the 90-degree fuel channel. Alternatively, the measurement may be performed on the remaining two sides.

〔The invention's effect〕

As described above, in the fuel channel corrosion measuring device according to the present invention, the fuel channel inserted into the device frame is provided with the corner guide roller on one side of the diagonal corner and the tip V on the other side. With a positioning mechanism equipped with a shaped arm, the fuel channel is pinched from both sides of the diagonal diagonal, and the fuel channel is rotated around the axis with a small number of positioning guide parts using the corner on one side of the fuel channel as the positioning reference. Positioning can be performed stably and accurately without rotation, and the measurement of all measurement points can be performed simply by raising and lowering the fuel channel without rotating it around the axis. The measurement can be performed efficiently in a short time, and the radiation exposure dose of the measurer can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an apparatus for measuring corrosion of a fuel channel according to an embodiment of the present invention, FIG. 2 is an explanatory view showing an installation state of the apparatus in a fuel pool, and FIG. FIG. 1 is a diagram corresponding to FIG. 1 showing a state of being inserted into the corrosion measuring device, FIG. 4 is an explanatory diagram showing a positioning state of a fuel channel by a positioning mechanism, FIG.
FIG. 6 is a detailed sectional view of the main part. DESCRIPTION OF SYMBOLS 1 ... Corrosion measuring device, 2 ... Fuel pool, 4 ... Fuel channel, 5 ... Refueling machine, 6 ... Device frame, 10
…… Positioning mechanism, 11… Corner guide roller, 12 ……
Arm, 13,15 …… Air cylinder, 14 …… Sensor mechanism, 1
6 ... Sensor mounting block, 17 ... Sensor holder, 18 ...
... contact type sensor, 19 ... spring, 23 ... controller.

Claims (1)

(57) [Claims] 1. A tubular device frame provided upright in a fuel pool and capable of inserting a fuel channel from above to an arbitrary position, and a diagonal diagonal portion provided on the device frame is sandwiched from both sides. A positioning mechanism for positioning the fuel channel around the axis, and a sensor provided on the device frame, which is close to the positioned fuel channel and is in close contact with the surface, and is capable of measuring the amount of surface corrosion of the fuel channel. The positioning mechanism has a corner guide roller located on one side of a diagonal diagonal portion of the fuel channel, and is located on the other side of the diagonal diagonal portion, and can advance and retreat toward the corner guide roller. An apparatus for measuring corrosion of a fuel channel, comprising: a remotely operated V-shaped tip.