JPS60219540A - Corroded part measuring apparatus of radioactive member - Google Patents

Abstract

PURPOSE:To rapidly measure a corrosion state with high accuracy, by moving a corrosion sensor with respect to the core constitutional member, especially, a fuel channel of a nuclear reactor and allowing said sensor to accurately oppose to the measuring surface of the channel. CONSTITUTION:A fuel channel 10 made of a zirconium alloy is suspended in the pool water 2 of a nuclear reactor and the measuring head 8 supported by a support rod 7 is moved along the outer wall of the fuel channel 10. The measuring head 8 is constituted by supporting a corrosion sensor 14 by a spring box 18, a rigid cable 17 and a convolute support 21 and attaching a disc 16 to the leading end of said sensor 14. When the measuring head 8 is impinged to the fuel channel 10, the sensor 14 is contacted with the channel 10 so as to be accurately opposed thereto even if said channel 10 is inclined. Further, as the corrosion sensor 14, an eddy current type one is used. Therefore, because the measuring head moves to the wall surface of the fuel channel and is accurately opposed to the measuring surface thereof, corrosion can be measured with high accuracy.

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a corrosion measuring device for M-prone members, and in particular, to improvement of a corrosion measuring device for radioactive members that measures corrosion of nuclear reactor core components, etc. l'ru. [Technical Background of the Invention and its Problems] In general, some of the core components of a nuclear reactor include fuel channels, etc. made of a zirconium base metal. It is known that it contains four meals. Corrosion phenomena of these core components can be a factor that has a small effect on the integrity of a nuclear reactor.Next, the case of a fuel channel of a boiling water reactor will be explained. The fuel channel is made of Zircaloy-4 and is formed into a rectangular tube shape, and accommodates a large number of fuel rods to form a mantle member of the fuel assembly, giving rigidity to the fuel rods, and forming a flow path for coolant. It is composed of If severe corrosion occurs in such a fuel channel, the thickness of the fuel channel decreases, resulting in a decrease in strength, which may impair the safety of the nuclear reactor. Furthermore, when the thickness of the oxide film due to corrosion grows beyond a certain value, this oxide film peels off from the surface of the fuel channel to the lower part of the reactor, causing an increase in the radiation dose in the lower part of the reactor. Therefore, fuel channel corrosion is
Corrosion is one of the factors that determines the lifespan of fuel channels, and understanding the progress of corrosion is an extremely important task when determining the usable period of fuel. Therefore, relatively simple devices have been developed that measure corrosion while the object to be measured, such as a fuel channel, is placed horizontally. , a relatively large device that scans a corrosion sensor along the measurement surface of the object to be measured has been used. However, since a fuel assembly containing a large number of fuel rods in a fuel channel cannot be placed horizontally, corrosion measurement of such a fuel assembly is There was a problem in that the method could not be applied to other reactor core components, and corrosion measurements of other core components could not be carried out quickly and in large quantities. In addition, the latter requires a large installation space for installing a large device, and when it is installed around a fuel storage pool, this affects the arrangement of equipment within the storage pool. Furthermore, since the apparatus is contaminated by radioactive objects during measurement, there is a problem in that a large amount of money is unavoidably spent on maintenance of the apparatus. [Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and provides a radioactive member that has a simple configuration, excellent operability, and can quickly measure the ffl eating state of a subject at a high vJ degree. The purpose is to provide a corrosion measuring device. [Summary of the Invention] In order to achieve the above-mentioned object, a radioactive member corrosion measuring apparatus according to the present invention is configured as follows. a corrosion detection section including a corrosion sensor that detects the corrosion state of the object to be measured; a display section that displays the detection output from the corrosion detection section by an appropriate means; and a support part that can be moved appropriately along the measurement surface of the object to be measured, and the corrosion detection section is configured such that the corrosion sensor always directly faces the measurement surface of the object to be measured. There is. Embodiments of the Invention] Hereinafter, an embodiment of the FI blastable member corrosion measuring apparatus according to the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a front view showing the overall configuration of the corrosion measuring device for radioactive members according to the present invention, and the mark in the figure is ? 31 is a fuel storage pool in which fuel assemblies are stored in pool water 2; A channel handling boom 5 is erected on the concrete side wall 4 of the fuel storage pool 1 as an incidental equipment of the fuel storage pool 1 so as to slightly overhang the pool opening. A hoisting device 6 is installed at the end of the overhang j, and a hook tied to the hoisting rope is suspended. A locking part (not shown) installed at the upper end of the head support rod 7 is hooked onto this hook.

[The head support rod 7 is lifted into the pool water 2 of the fuel storage pool 1 by the hoisting operation of the hoisting device 6.
can be lifted. This measurement support rod 7
A measuring head 8 is attached to the lower end of the fuel storage pool 1.
The measurement head 8 is attached to the outer wall of the fuel channel 10, which is held upright in the pool water 2, by a channel attachment/detachment device 9 attached thereto, so that the measurement head 8 can be moved in the vertical direction. That is, the measuring head 8 can be moved upward via the head support rod 7 by the hoisting operation of the hoisting device 6 . The measurement head 8 incorporates a sensor assembly 11 that mainly detects the corrosion state of radioactive members such as the fuel channel 10, and this sensor assembly 11 is electrically connected to a corrosion indicator 12 via a cable to be described later. . This corrosion indicator 12 displays the detection output output from the measuring head 8 by appropriate means, and is arranged on the floor or the like on the upper surface of the side wall of the fuel storage pool 1, as shown in FIG. FIG. 2 is an enlarged perspective view of section A in FIG. 1, and shows the measuring head 8.
is shown being pressed against the outer wall surface of the fuel channel 10. The measuring head 8 is connected to the head support rod 7.
The center of gravity of the measuring head 8 is fixed so as to be eccentric from the center of gravity of the lifting part of the head support rod 7, and the self-Φ of the measuring head 8 produces a certain pressing force on the fuel channel 10.
The measuring head 8 is pressed. and,
The measuring head 8 has a movable guide 1 whose flat surface is formed into a mouth shape.
3, a head support rod 7 is fixed upright and covering the upper surface of the mouth-shaped web, and the opposite sides of the mouth-shape extend to the left and right side walls of the fuel channel 10, respectively. It is designed to slide on both the left and right walls. As shown in FIG. 2, a plurality of sensor assemblies 11, for example three sensor assemblies 11, are arranged in parallel to each other on the inner surface of the mouth-shaped web of the moving guide 13, and these sensor assemblies 1
The tip surfaces of the fuel channels 10 are brought into surface contact with the corrosion measurement surface of the fuel channel 10 at the required contact pressure. The sensor assembly 11 is constructed as shown in FIG.
One end of the corrosion sensor 14 is inserted into a cylindrical cover 15. The front and rear ends of this cover 15 have a front end insertion hole 15a and a rear end insertion hole 15b that are bored coaxially with the axis, and the insertion end of the corrosion sensor 14 is provided in the front end insertion hole 15a. The parts are loosely fitted. An outer flange 14a projecting outward is provided around the outer periphery of the insertion end of the corrosion sensor 14,
The front end insertion hole 15a of the cover 15 is inserted into the outer flange 14a.
It is now blocked from the inside. On the other hand, the front end of the corrosion sensor 14 extends outward from the cover 15, and a fixed disk 16 made of a non-conductor is fixed thereto to insulate the front end of the corrosion sensor 14. The front end of the corrosion sensor 14 is slightly recessed a3 from the front end surface of the fixed disk 16, and the child retracted portions are formed at four parts of the front end of the fixed disk 16. The fixed disk 16 is formed to have a diameter sufficient to close the front end insertion hole 15a of the cover 15, and an outer flange of a required width is integrally provided around the outer periphery of the front end, so that the front end surface of the fixed disk 16 is sufficiently wide. Ensures a contact area of A recess for accommodating the outer flange of the fixed disk 16 is formed at the front end of the cover 15, so that when the corrosion sensor 14 is retracted inward from the cover 15,
The front end of the fixed disk 16 and the front end of the cover 15 are formed so as to be substantially coplanar. The corrosion sensor 14 is a sensor that detects the corrosion state of a radioactive member, and the fuel channel 1 made of zirconium alloy
An eddy current sensor is suitable for measuring zero corrosion. In other words, when a zirconium alloy corrodes, zirconium oxide is produced, but since this zirconium oxide is a non-conductor, the thickness of the oxide film can be detected by contacting it with an eddy current sensor and energizing the sensor. . The cable 17 electrically connected to the corrosion sensor 14 has appropriate rigidity, and one end thereof is inserted into the rear end insertion hole 15b of the cover 15.
It coaxially passes through the spring box 18 through the spring box 18 and extends to the outside thereof, and is electrically connected to the AM display 12 of the upper part, and receives the detection output output from the corrosion hinge 14 by appropriate means. It's turning into a sea urchin. The spring box 18 accommodates therein a coil spring 19 coaxially attached to the outer circumference of the rigid cable 17, and presses the stopper 20 fixed to the cable 17 forward so that the cable 17 and the cable Corrosion sensor 14 connected to 17 is always facing forward. Further, the front end portion of the cable 17 is coaxially and elastically supported within the cover 15 by a spiral-shaped spiral formed by a spring member. That is, the spiral centers of the spiral V bows 1 to 21 are fixed to the outer periphery of the front end of the cable 17, and the outer diameter ends of the spirals are embedded and fixed in an annular groove recessed in the inner peripheral wall of the cover 15. . However...
] Thus, the front end of the cable 17 is always held at the center of the axis of the cover 15. Furthermore, since the cable 17 is also elastically supported by the coil spring 19, even if the corrosion support 14 connected to the cable 17 retreats backward in the axial direction, its spring horn will return it to its original position. It is possible to return. In measurement using this scale, the thickness of the oxide film on the object to be measured is generally a microscopic unit of several tens of microns, and extremely high measurement accuracy is required of the corrosion sensor. for that,
During measurement, it is necessary for the corrosion sensor to always face the object to be measured and face it, and if the corrosion sensor is brought into surface contact with the object at an angle, a measurement error will occur. However, in the corrosion measuring device according to the embodiment of the present invention, as shown in FIG. 4, the corrosion sensor 14 always faces the measurement surface of the fuel channel 10 which is the object to be measured, so High measurement accuracy can be obtained. That is, as shown in FIG.
On the other hand, when the measuring surface is inclined, the front end surface of the fixed disk 16 is always maintained in a close surface contact with the inclined measurement surface from the perpendicular direction with the required contact pressure. , cable 17, spiral → no boat 21, and coil spring 19 are elastically deformed to absorb the strain caused by these inclinations. As a result, the fixed disk 16 is always in surface contact with the measurement surface of the fuel channel 10, so that the front end surface of the corrosion sensor 14 fixed to the fixed disk 16 can always face the measurement surface. can. As a result, high measurement accuracy can always be obtained. Also,
The contact pressure between the front end surface of the fixed disk 16 and the measurement surface such as the fuel channel 10 is also one of the factors that affects measurement accuracy. The cable 17 and the coil spring 19 that elastically supports the cable 17 are independent of pressure.
, is determined by the pressure nozzle j that presses the front end surface of the fixed disk 16 against the measurement surface by the elastic force of the spiral support 21, so that stable measurement values can always be obtained. Incidentally, in the above embodiment, an example was described in which the front end surface of the corrosion sensor 14 was slightly set back from the front end surface of the fixed disk 16.
It may be so-called flush. [Effects of the Invention] As explained above, the radioactive member corrosion measuring device according to the present invention has a fixed disk that is always in close surface contact with the measurement surface of the object to be measured, such as a radioactive member, with a required contact pressure. A corrosion sensor was fixed to detect the corrosion state of the object to be measured. Therefore, according to the present invention, the front end surface, which is the detection surface of the corrosion sensor, always faces the measurement surface of the object to be measured, so that even if the object to be measured is tilted, the detection surface of the corrosion sensor is It always faces the measurement surface of the object to be measured, allowing extremely accurate corrosion measurement results to be obtained. Regarding measurement accuracy, extremely high reliability is obtained regardless of the installation accuracy of the object to be measured, and an accuracy of ±3μ has been confirmed in measurement results in actual nuclear reactors. Further, according to the embodiments of the present invention, the structure is simple, the operation is easy, and the operability is excellent, and the device can be constructed to be lightweight and small. Furthermore, when measuring corrosion of the fuel channel, existing equipment such as a fuel loading/unloading machine can be utilized to a large extent. As a result, corrosion of a large number of radioactive members can be quickly measured.

[Brief explanation of the drawing]

1 to 4 respectively show the configuration of an embodiment of the radioactive member corrosion measuring device according to the present invention, and FIG. Figure 2 is a partially enlarged perspective view showing the Δ section of Figure 1, Figure 3 is a vertical sectional view of the sensor assembly, and Figure 4 shows the corrosion sensor directly facing the measurement surface of the inclined object. There is a vertical sectional view C of the assembly without showing the state. 1...Fuel storage pool, 2...Pool water, 4...
Pool side wall, 5...Channel handling boom, 6...
・Volume" device, 7... Head support rod, 8... Measuring head, 9... Channel attachment/detachment machine, 10... Fuel tunnel, 11... Sensor assembly, 12... Corrosion indicator, 13...Movement guide, 14...Corrosion sensor→ノ, 15...) J bar, 16...Fixed disk, 17
... Cable, 18 ... Spring box, 19
...Coil spring, 20...Stopper, 21.
...Vortex support. Applicant's agent Hisashi Hatano

Claims (1)

[Scope of Claims] 1. A corrosion detection section including a corrosion sensor that detects the corrosion state of the object to be measured, a display section that displays the detection output from the corrosion detection section by appropriate means, and a support for the corrosion detection section. and a support part for appropriately moving the corrosion detection section along the measurement surface of the object to be measured, and the corrosion detection section is arranged so that the corrosion sensor always faces the measurement surface of the object to be measured. A corrosion measuring device for a radioactive member, characterized by comprising: 2. The rg4 food sensor is elastically supported in the axial and radial directions, and a fixed disk is fixed coaxially to the outer periphery of the front end, and the contact surface of the fixed disk is attached to the measurement surface of the object to be measured. 11. The apparatus for measuring corrosion of a 11i radioactive member according to claim 1, wherein the fixing disk is formed so as to be able to make surface contact, and the contact surface of the fixed disk is formed to be parallel to the detection surface of the corrosion sensor. 3. The support part is connected to the hoisting device via the hoisting rope,
The radioactive member corrosion measuring device according to claim 1, which is configured to be lifted upward by a hoisting operation of the hoisting device.