JPS60214296A - Measuring device for fuel channel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel assembly whose shape etc. are measured in order to determine the health of the fuel channel of a fuel assembly of a boiling water reactor (hereinafter referred to as BWR). The present invention relates to a channel measuring device.

[Technical fungi of the invention] A conventional example will be explained below with reference to FIGS. 1 and 2.

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a BWR. Reference numeral 1 in the figure indicates a reactor pressure vessel, and this reactor pressure vessel 1
Inside there is a coolant 2, a plurality of fuel assemblies 3 and control rods 4.
A reactor core 5 consisting of the following is accommodated. The coolant 2 flows through the reactor core 5 from below to above, and at this time, it easily rises due to the nuclear reaction heat of the reactor core, resulting in a two-layer flow state of water and steam.

The coolant 3 in a two-layer flow state flows into the steam-water separator 7 via the shroud head 6 above the core 5 and is separated into water and steam. The separated steam flows into a steam dryer 8 provided above the steam separator 7 and is dried to become dry steam, which is then passed through a main steam pipe 9 (not shown) connected to the reactor pressure vessel 1. It is transferred to the turbine system and used for power generation.

In the figure, reference numeral 10 indicates a control rod drive mechanism for inserting or withdrawing the control rod 4 into or out of the reactor core 5, and reference numeral 11 indicates a diene 1 pump constituting a recirculation system. Further, reference numeral 12 indicates a water supply inlet nozzle, and reference numeral 13 indicates a recirculation water outlet nozzle.

The fuel assembly 3 has a configuration as shown in FIG. Reference numeral 21 in the figure indicates a fuel channel, and within this fuel channel 21, a plurality of fuel rods 22 containing pelletized nuclear fuel are arranged in a grid pattern (e.g., 8 rows x 8 rows). 22 is supported at its upper and lower ends by an upper tie plate 23 and a lower tie plate 24, respectively. In addition, a plurality of spacers 25 are provided at the intermediate position.
Supported by

The fuel channel 21 has the function of equalizing the flow of the cooling vJ2 in the core 5 and ensuring a space for inserting the control rods 3 or a space for inserting an instrumentation sensor (not shown) into the core 5. Such a fuel channel 21 is generally replaced with a new one at the time of fuel exchange, and the used fuel channel 21 is treated as radioactive waste, but it is being considered to reuse it in order to reduce radioactive waste. . At this time, it is necessary to thoroughly inspect the fuel channels 21 to confirm their soundness, and select only those fuel channels 21 that can withstand reuse.

The above inspection items are bending, swelling, and twisting.

However, there are the following restrictions when performing such an inspection. That is, the fuel channel 11 contains spent fuel therein, and because it is highly radioactive, it must be shielded within the fuel handling pool and must be operated remotely. In addition, high test accuracy is required, and in order to reduce radiation exposure to workers, it is desirable that the time required for the test be short.Furthermore, the test equipment used for the test should be small and lightweight, considering the test conditions. needs to be easy. Conventionally, based on such conditions, deformation has been detected by measuring distance in a non-contact manner using an ultrasonic sensor or an eddy current sensor.

[Problems with background technology] The above configuration had the following problems.

In other words, when using the sensor described above, in order to accurately measure the distance from the sensor to the object to be measured, the object to be measured must be a sufficiently wider plane than the sensor. Accurate measurements cannot be made if the measurement surface is tilted with respect to the central axis of the instrument. On the other hand, in the fuel channel 21, as shown in Fig. 2, the connection between the prismatic plate and the fitting member at the lower end is made by area fitting, and stress is constantly applied to that part. are doing.

Therefore, the lower end of the fuel channel 21 tends to expand outward after being used for a long time, and in this case, fluctuations occur in the flow state of the coolant 3, making it impossible to obtain the necessary cooling effect. I end up. Therefore, when performing shape measurement, it is necessary to reliably detect such shape changes. However, in such a situation, the non-contact type sensor described above has a problem in that it becomes unable to measure due to the large inclination and the edge.

[Object of the Invention] The present invention has been made based on the above points, and its purpose is to determine the health of a fuel channel by reliably measuring changes in shape such as swelling at the lower end of the fuel channel. The object of the present invention is to provide a fuel channel measuring device that is highly accurate and can improve not only the reliability of the device itself but also the safety of the plant.

[Summary of the invention]

That is, the fuel channel measuring device according to the present invention is a fuel channel measuring device for measuring the shape of a fuel channel of a boiling water reactor, and includes a measuring device frame and an insertion fixing device for inserting and fixing the fuel channel into the measuring device frame. a movable frame that is attached to the upper end of the measuring device frame and that moves to follow the horizontal deflection of the fuel channel when the fuel channel is inserted and fixed by the insertion and fixing mechanism; a contact distance sensor that is fixed to the circumferential side and measures the distance between the outer circumferential surface of the fuel channel and the inner circumferential surface of the movable frame;
When the fuel channels are inserted and fixed, they are distributed in the frame so that they are located on two virtual surfaces that oppose the two adjacent surfaces of the fuel channels, and the two adjacent surfaces of the fuel channels and the virtual surface A non-contact type distance sensor that measures the distance between The configuration includes an arithmetic processing mechanism that inputs and performs processing.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 3 to 5. It should be noted that the same parts as those in the prior art are indicated by the same reference numerals, and the explanation thereof will be omitted.

FIG. 3 is a perspective view of the fuel channel measuring device according to this embodiment. The symbol @51 in the figure indicates a measuring device frame, and this measuring device frame 51 is shaped like a box with a rectangular cross section by removing a pair of adjacent side plates, and is composed of side plates 51A and 51B. ing. The measuring device frame 51
A lower support fitting 52 for supporting the fuel assembly 3 from below is attached to the lower part of the fuel assembly 3. On the other hand, a movable frame 53 is attached to the upper end of the measuring device frame 51, and the fuel assembly 3 is mounted above the movable frame 53.
An upper guide mechanism 54 is attached which serves as a guide when inserted into the interior. The movable frame 53 is constructed as shown in FIG. In other words, the movable frame 53 is connected to four places by chains 55.
It is connected to the top and hangs down, allowing it to move forward, backward, left and right in the figure. Further, guide rollers 57 are attached to the inner circumferential sides of a pair of adjacent side plates 53A of the movable frame 53, respectively, via support members 58, and −δ is attached to the inner circumferential sides of the pair of opposing side plates 53B. A contact distance sensor 59 is attached to. This distance sensor 59 has a configuration in which a strain gauge (not shown) is attached to a plate spring 61 having a guide roller 60 at its lower end.And on both sides of the distance sensor 59, a pair of distance sensors having a similar configuration are arranged. Sensors 62 and 62 are attached.In other words, the fuel assembly 3 is suspended from above by a crane or the like (not shown), passed through the upper guide tjllN54, and placed in the measuring device frame 5.
Introduced within 1. At this time, the fuel channel 21 is lowered while pushing the distance sensors 59, 62 outwardly. As a result, the distances between the points of contact between the fuel channel 21 and the guide roller 57 and the points of contact between the fuel channel 21 and the distance sensors 59 and 62 are measured. ! Send the measurement results to the mechanism and perform processing (4
411 calculates the swelling etc. from these measurement results.

Further, the downward movement distance of the fuel assembly 4 can be calculated based on the signal from the crane. Note that the detection signals from each of the distance sensors 59, 62, and 62 mentioned above are XA,
Assuming XB and XC, the swelling of the fuel channel 21 on the contact surface is calculated by the following formula.

Swelling = (Xs +Xc) / 2-XA ・”-I
Furthermore, a plurality of non-contact type distance m sensors 63 are provided on the measuring device frame 51 at equal intervals in the vertical direction via mounting frames 64. This non-contact type distance sensor 63 is installed at a position corresponding to the measurement position shown in FIG. 5 (indicated by circles and squares in the figure). The bend is measured using the measurement signal from the distance sensor 63 corresponding to the measurement position indicated by the mark.
The configuration is such that the bulge and twist are measured using the measurement signal from the distance sensor 63 corresponding to the measurement position indicated by the mark.

Further, the positions measured by the contact-type distance sensors 59 and 62 coincide with the positions measured by the non-contact distance sensor 63. This is to compare the measurement results of the contact type distance sensor 59, 62 and the non-contact type distance sensor 63 after measurement to judge the validity thereof. That is, after the fuel assembly 3 is mounted and fixed in the measuring device frame 51, the distance between each distance sensor 63 and the fuel channel 21 is measured by the non-contact type distance sensor 63. Based on these measurement results, the arithmetic processing mechanism determines whether the fuel channel 21
Calculate the bending, bulging, and twisting of. Next, the results measured by these non-contact type distance sensors 63 and the results measured by the contact type distance sensors 59 and 62 are compared by the arithmetic processing mechanism to evaluate the validity of the measurement results.

Note that the reference numeral 65 in FIG. 3 indicates a guide. In addition, the side plate 5
A plurality of holes 66 are formed in 1A and 51B,
This is to make the device lighter.

The operation will be explained based on the above configuration. First, the fuel assembly pair 3 to be measured is suspended from above the measuring device by a crane, and then passed through the upper guide mechanism 54 to the measuring device frame 51.
Insert inside. The fuel channel 21 then pushes the contact distance sensor 59,62 outward. The arithmetic processing mechanism calculates the swelling of the fuel channel 21 based on the measurement signal at this time. Thereafter, path 11111 determination is performed sequentially at predetermined measurement positions. Further, the downward movement distance of the fuel channel 21 at that time is calculated based on the signal from the crane. Then, the arithmetic processing mechanism calculates the bulge at each of the above positions, as well as the bending and twisting. The fuel assembly 3 is completely inserted and fixed into the measuring device frame 51, and its upper and lower ends are supported by an upper guide mechanism 54 and a lower support fitting 52. After being inserted and fixed, the non-contact type distance sensor 63 measures the distance at the measurement position shown in FIG. Then, the arithmetic processing am calculates the bending of the fuel channel 51 based on the signal from the measurement position indicated by the mark in FIG. calculate. And a non-contact distance sensor 6
3 and the above-mentioned contact type distance sensor 5
The measurement results measured in accordance with 9.62 are compared by an arithmetic processing mechanism to determine their validity.

As described above, according to the measuring device according to the present embodiment, the swelling of the lower end of the fuel channel 21 can be prevented even when the lower end of the fuel channel 51 is in an expanded state.
1, the contact-type distance sensor 59.62 is always contacted, so that the contact-type distance sensor 59.62 can reliably measure the distance. Also, a contact type distance sensor 5
9.62 and the measurement result measured by the non-contact distance sensor 63 to confirm its validity, it is possible to check the swelling, bending and the like of the fuel channel 21 with high accuracy. It is possible to measure torsion, and it is possible to judge with high precision whether or not the fuel channel 21 can be reused, which not only improves the reliability of the measuring device itself but also greatly improves the safety of the reactor. can.

〔Effect of the invention〕

As detailed above, the fuel channel measuring device according to the present invention is a fuel channel measuring device for measuring the shape of a fuel channel of a boiling water reactor, which includes a measuring device frame body,
An insertion and fixing mechanism that inserts and fixes the fuel channel into the measuring device frame, and an insertion and fixing mechanism that is attached to the upper end of the measuring device frame to follow the lateral deflection of the fuel channel when inserting and fixing the fuel channel. a movable frame that is movable, a contact distance sensor that is fixed to the inner circumferential side of the movable frame and measures the distance between the outer circumferential surface of the fuel channel and the inner circumferential surface of the movable frame, and when the fuel channel is inserted and fixed; A non-contact device is distributed on the frame so as to be located on two virtual surfaces opposing the two adjacent surfaces of the fuel channel, and measures the distance between the two adjacent surfaces of the fuel channel and the virtual surface. a distance sensor, a distance measuring mechanism for measuring a distance traveled through a fuel channel, and a contact distance sensor.

This configuration includes a non-contact distance sensor and an arithmetic processing mechanism that inputs and processes measurement signals from a passing distance measuring mechanism.

Therefore, bending, swelling, twisting, etc. of the fuel channel can be measured reliably with high precision, and in particular, it is possible to reliably measure the swelling at the lower end of the fuel channel, which was previously difficult to measure. It is possible to judge with high precision whether a fuel channel can be reused or not, which is extremely effective in improving the safety of a nuclear reactor.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing a conventional example, in which Figure 1 is a longitudinal sectional view showing the schematic configuration of a boiling water reactor, Figure 2 is a perspective view of a fuel assembly, and Figures 3 to 5. The figure shows an embodiment of the present invention, and FIG. 3 is a perspective view of a fuel channel measuring device;
FIG. 4 is a perspective view of the movable frame, and FIG. 5 is a perspective view of the fuel assembly showing the measurement position of a non-contact distance sensor. Moving frame, 54... Upper guide mechanism, 59.6.2... Contact type distance sensor (first distance sensor), 63... Non-contact type distance sensor (second distance sensor). Applicant's agent Patent attorney Takehiko Suzue No. 1 Figure order] 23 2 24

Claims (1)

[Claims] In a fuel tunnel measuring device 4 for determining the shape of a fuel tunnel of a boiling water reactor, a measuring device frame;
An insertion and fixing mechanism for inserting and fixing the fuel channel into the measuring device frame, and an insertion and fixing mechanism attached to the upper end of the measuring device frame to follow the lateral vibration of the fuel channel when inserting and fixing the fuel channel. a movable frame that moves with the movable frame; a contact distance sensor that is fixed to the inner circumferential side of the movable frame and measures the distance between the outer circumferential surface of the fuel channel and the inner circumferential surface of the movable frame; Non-contact units are distributed in the frame so as to be located on two virtual surfaces opposite to the two adjacent surfaces of the channel, and are used to measure the distance between the two adjacent surfaces of the fourth channel and the virtual surface. a contact type distance sensor, a passage distance measuring mechanism for measuring the passage distance of the fuel tunnel, and the contact type distance sensor;
A fuel channel measuring device comprising a non-contact distance sensor and an arithmetic processing mechanism that inputs and processes a measurement signal from a passing distance measurement t1m.