JPH068897B2 - Shape inspection method for fuel channel box - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for inspecting a fuel channel used in a nuclear power plant, and more particularly to a method for inspecting an irradiated fuel channel in a nuclear power plant. It is a thing.

[Background of the Invention]

The fuel channel is a fuel assembly 1 shown in FIG.
Which is one of the components, and houses the fuel body 2 inside. The fuel channel 3 is irradiated with neutrons for a long time during use in the core and is operated in a state where the pressure difference inside and outside the fuel channel is large, so that deformation such as creep occurs during use.

FIG. 7 shows the positional relationship between the fuel channel 3 and the control rod 5. Since the upper lattice 6 which defines these positions is formed by a pitch having no margin so that the fuel can be densely arranged, when the deformation of the fuel channel box 3 becomes large, it interferes with the control rod 5 and the control is performed. The rod cannot be inserted or pulled out. Therefore, the fuel channel 3 must be used within a deformation range where it does not interfere with the control rod 5, and the measurement of the shape and size of the fuel channel 3 is important in evaluating the life of the fuel channel 3. It is an inspection item.

Eighth conventional fuel channel shape inspection system
Shown in the figure. In this conventional shape dimension inspection device 7,
After inserting the fuel channel box 3 into the shape inspection device 7, the fuel channel box 3 is clamped and held by the clamp mechanism 8. After that, the shape dimension detection unit 9 is caused to travel along the guide rail 12 in the axial direction, and the cross-sectional shape dimension and the longitudinal shape dimension of the fuel channel box 3 are measured. However, in this method, in order to meet the present needs for shape inspection of the fuel channel 3,
There are the following problems.

(1) The inspection time becomes long because it is necessary to move the shape dimension detection unit 9 in the axial direction. At present, the fuel channel 3 is considered to be reused for the purpose of long-term use and reduction of waste. In this case, it is necessary to measure the deformation amount of the fuel channel box 3 before reuse and determine whether or not it can be reused. In order to put into practical use the total reuse of the fuel channels 3, it is desired to shorten the reuse inspection time as much as possible.

(2) In order to measure the shape dimension in the longitudinal direction with high accuracy, the shape dimension detecting section 9 must be run straight along the guide rail 12. Deviations in straightness during running directly lead to measurement errors in the longitudinal geometry. In order to maintain the accurate traveling of the shape dimension detection unit 9, a large traveling mechanism is likely to be formed, and the shape dimension inspection device is likely to be upsized.

(3) The shape inspection device 7 is used by being attached to the wall of the spent fuel storage pool. However, when the measurement is performed with the fuel channel box 3 attached to the fuel body 2, the range in which the fuel body 2 can be handled is limited. For safety of radiation exposure of work, the depth of the frame 13 of the apparatus is increased because the area is limited to a depth deeper than a certain depth, and it is difficult to make the apparatus compact.

(4) The place where the shape and dimension inspection device 7 can be attached is limited to the wall surface provided with the mounting and fixing metal fittings of the spent fuel storage pool, and at present, there are various types on the wall of the spent fuel storage pool of the existing nuclear power plant. Since the service equipment is attached, it may be necessary to remove any of the service equipment when attaching the shape dimension inspection device 7.

[Object of the Invention]

An object of the present invention is to shorten the shape inspection time of the fuel channel, especially the shape inspection time of the reused fuel channel, to effectively utilize the spent fuel storage pool, and to remove other service equipment. It is an object of the present invention to provide a method for inspecting the shape and dimension of a fuel channel that does not need to be processed.

[Outline of Invention]

The present invention relates to a control rod arranged in a spent fuel storage pool with a shape measuring device including a combination of a cross-sectional shape measuring portion provided at a frame inlet and a longitudinal shape measuring portion provided in a frame axial direction.・ Propose a method to inspect the shape and size of the reused fuel channel box by installing it on the damaged fuel storage rack.

In the present invention, since the measurement detection unit is not run, the measurement of the shape dimension is completed in a short time. Moreover, since it is installed in the storage rack and used, it is not necessary to remove other service equipment. Further, the shape measuring device can be easily removed and used for measurement in other pools.

Example of Invention

 An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows the entire shape and dimension inspection device for the fuel channel 3. This apparatus is composed of a frame 15, a guide roller mechanism 16, a cross-sectional shape dimension detecting section 17, a longitudinal direction shape dimension detecting section 18, and a seating detecting section 19.

As shown in FIG. 2, the dimension inspection device 21 is used in a state in which it is inserted in the control rod / damaged fuel storage rack 22. When this control rod / damaged fuel storage rack 22 is used, it is not necessary to install a mechanism for installing the long and slender device of 4 m or more in the spent fuel storage pool so that it does not tip over. Don't worry.

Next, the guide roller mechanism 16 is shown in FIG. Four guide rollers 23 are attached to the guide roller mechanism 16 so that the four surfaces of the fuel channel box 3 can be guided, and each guide roller 23 is pressed against the fuel channel box 3 by a spring 24. . The guide roller mechanism 16 is a fuel channel box 3.
In addition to the function of a guide when the fuel is carried into the shape dimension inspection device 21, the fuel channel 3 has a function of holding the fuel channel 3 in a twisted state during measurement. When the fuel channel 3 is measured in a twisted state, the error in the cross-sectional shape dimension inspection, especially the outer width measurement becomes large, and the measurement accuracy is significantly reduced. In particular, when an ultrasonic sensor is used as the measuring terminal, if this twist is large, the ultrasonic wave emitted from the ultrasonic sensor will be reflected by tilting on the surface of the fuel channel box, and the ultrasonic sensor will be reflected. The waves cannot be received and the measurement itself becomes difficult.
For this reason, the guide roller mechanism 16 corrects the orientation of the fuel channel 3 so that the vertical direction of the measurement surface of the fuel channel and the direction of the measurement terminal coincide with each other to prevent the measurement accuracy from deteriorating.

FIG. 4 shows the cross-sectional shape dimension detection unit 17 provided at the entrance of the shape dimension inspection device 21. An ultrasonic sensor is used as the measurement terminal 25. Three measuring terminals 25 are arranged on each surface, and twelve measuring terminals are arranged on all four surfaces. The cross section straightness of the fuel channel 3 can be measured by the three measuring terminals 25 on each surface. In addition, by the two measuring terminals 25 facing each other,
The outer width dimension of the fuel channel 3 is obtained from the relationship between the distance between the two measuring terminals and the distance measured by the measuring terminals from the surface of the fuel channel 3 to the surface of the fuel channel 3.

On the other hand, as shown in FIG. 1, the longitudinal shape dimension detecting unit 18 is configured by arranging several measuring terminals 26 in the axial direction. Further, in FIG. 5 showing the cross section of the longitudinal shape dimension inspection unit 18, the measuring terminals 26 are provided on four surfaces, and the four terminals can be measured simultaneously. By means of several measuring terminals 26 arranged in this axial direction, the fuel channel 3
The longitudinal bending of the is measured. The measuring terminal 26 in the axial direction does not necessarily have to be accurately arranged straight. That is, since the measuring terminal 26 is fixed to the frame 15, a calibrating body whose axial shape and dimension are known is used to measure this calibrating body to obtain the displacement of the measuring terminal 26 from the straightness. By correcting the deviation in the measured data, the bending of the fuel channel 3 in the longitudinal direction can be accurately measured.

As shown in FIG. 1, the seating detection unit 19 is provided at the lower end of the shape inspection device 21, and detects that the fuel channel box 3 is seated in the shape inspection device using the limit switch 27. It is said.

Next, a method of inspecting the fuel channel 3 according to the present invention using the shape / dimension inspection device 21 will be described.

First, the fuel channel 3 to be inspected is inserted into the shape inspection device 21 by the fuel gripping device of the refueling truck. After the insertion, the seating detection unit 19 confirms that the fuel channel box 3 is seated in the device in a normal state. Therefore, by the longitudinal shape dimension detection unit 18,
The bending of the fuel channel 3 in the longitudinal direction is measured. After the bending measurement is completed, the fuel channel 3 is raised by the fuel gripping device at a constant speed, for example, 4 m / min. At the time of this rise, the cross-section straightness and the outer width at each position in the longitudinal direction of the fuel channel box 3 are measured by the cross-section shape dimension detection unit 17. As for the longitudinal position to be measured, the time required for any measurement position to pass is determined in advance from the relationship between the rising time and the elapsed time from the time when the seating detection unit 19 detects the start of rising of the fuel channel box 3, and this fixed time elapses. Sometimes it can be specified by taking a measurement. In the case of the ultrasonic sensor, since the measurement can be performed in about 1 ms, the measurement accuracy does not decrease even if the measurement is performed in the ascending state without stopping the fuel channel 3. Due to this rise, after the fuel channel 3 is taken out from the shape inspection device 21, the fuel channel 3 is moved to the designated storage location as it is, and the shape inspection is completed.

Since the inspection device is installed in the rack close to this storage location, the distance and time for moving the fuel channel box is also a feature of the present invention.

〔The invention's effect〕

According to the present invention, the shape and dimension inspection of the fuel channel box is performed only in the time of inserting into and removing from the shape and dimension inspection device, so that the shape and dimension inspection time is shortened. In addition, by inserting the shape inspection device into the control rod / damaged fuel storage rack and using it, the shape inspection device can be made compact, and the control rod / damaged fuel storage can be used as an inspection place in the spent fuel storage pool. You can effectively use the rack. Therefore, when installing the shape dimension inspection device, it is not necessary to remove other service equipment.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall structure of a fuel channel box shape inspection apparatus used in the shape inspection method of the present invention,
FIG. 2 is a view showing a state in which the apparatus is attached to a control rod / damaged fuel storage rack, FIG. 3 is a structural view of a guide roller mechanism, FIG. 4 is a structural view of a sectional shape dimension detecting portion, and 5 Fig. 6 is a structural diagram of the longitudinal shape dimension detector, Fig. 6 is a structural diagram of the fuel assembly, Fig. 7 is a layout diagram of the fuel channels and control rods in the core, and Fig. 8 is a conventional fuel channel dimension. It is a structural diagram of an inspection device. DESCRIPTION OF SYMBOLS 1 ... Fuel assembly, 2 ... Fuel assembly, 3 ... Fuel channel box, 5 ... Control rod, 6 ... Upper lattice, 7 ... Fuel channel box shape inspection device, 8 ... Clamp mechanism, 9 ... Shape detection unit, 10 ... Seating part, 11 ... Dimension detection part elevation drive part, 12 ... Guide rail, 13 ... Frame, 14 ... Spent fuel storage pool wall, 15 ... Frame, 16 ... Guide roller mechanism, 17 ... Cross-section shape size detection part, 18 ... longitudinal shape dimension detecting section, 19 seating detecting section, 20 apparatus mounting mechanism, 21 fuel column shape measuring apparatus, 22 control rod / damaged fuel storage rack, 23 guide roller, 24 spring, 25 , 26 ... Measuring terminals.

Claims (2)

[Claims] 1. A frame, a guide mechanism arranged on the upper part of the frame for guiding the carry-in of the fuel assembly, and a cross-section shape dimension detecting section arranged near the guide mechanism for measuring the cross-sectional shape of the fuel assembly. A shape measuring device including a plurality of longitudinal shape detecting portions arranged in the longitudinal direction of the frame is installed on a fuel storage rack to inspect the shape of a fuel channel box which is a constituent member of the fuel assembly. In the method of inspecting the shape and dimension of a fuel channel box, a seating detector is arranged at the bottom of the frame, and the plurality of longitudinal shapes are arranged in a state where the seating detector confirms normal seating of the fuel channel box. The dimension detection unit measures the shape dimension in the longitudinal direction of the fuel channel box, and takes out the fuel assembly from the measuring device. At the time of measuring the shape and size of the fuel channel box by the cross-sectional shape and size detecting unit, the start of the withdrawal is detected by the detachment of the fuel assembly from the seating detection mechanism, and the elapsed time after the withdrawal and the withdrawal speed A method for inspecting the shape and size of a fuel channel box, characterized in that the measurement position in the longitudinal direction is determined from the relationship of. 2. The method for inspecting the shape of a fuel channel box according to claim 1, wherein the guide mechanism presses a guide roller against the fuel channel box by an elastic member, and the guide channel is perpendicular to the fuel channel box. A method for inspecting the shape and dimension of a fuel channel box, which is characterized in that the direction of the measuring terminal of the shape and dimension detecting unit is made to match.