JPS6162811A - Remote measuring apparatus - Google Patents

Abstract

PURPOSE:To accurately measure the height difference between a core support plate and a CRT part, by providing a water seal pipe covering a stub tube so as to pierce an upper lattice plate and the core support plate in the vessel of an atomic reactor and performing measurement by using the same pipe. CONSTITUTION:A water seal pipe 22 for discharging the water of an atomic reactor is provided on a CRD (control rod drive mechanism) housing 18 and contacted with the lower mirror inner wall surface of a pressure container 10 in a water-tight state while the upper part pierces a core support plate 13 and the lattice opening of an upper lattice plate 14 to extend upwardly. A transfer sensor 24 is attached to the outer side surface of the water seal pipe 22. The sensor 24 has a probe 25 downwardly protruding in a freely advancing and retracting state and measures the distance X from the reference point 0 of the pipe 22 to the upper surface of the core support plate. A laser measuring apparatus 20 is provided to the upper part of the pipe 22 and measures the distance Y from a laser oscillator 28 to the top part of the CRD housing 18. A counter 26 accurately calculates the height difference A between the top part of the housing 18 and the upper surface of the support plate 13 from the above mentioned measured values X, Y.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a remote measuring device that measures the height difference h1 between the top of a control rod drive mechanism housing and the first plane of a core support plate.
In particular, when replacing the stub tube in the lower head of the reactor pressure vessel, a new multi-tiered control system was installed to remotely measure the difference between the upper surface of the core support plate and the lower part of the housing. Related.

[Technical costs of inventions and their problems]

In the lower mirror of the reactor pressure vessel 1 of the boiling water reactor 11i1,
As shown in FIGS. 3 and 1, the control rod drive mechanism housing (hereinafter referred to as C and RD housing) 2 is
A single supporting stubbed cove 3 is attached by welding 1. If cracks or stress corrosion cracks (4) occur due to poor welding at or near the welding part of this stub unit 3, reactor water will leak to the outside from this crack, preventing the reactor from shutting down. There is a possibility v1 that the need will arise.

If stress corrosion cracking or the like occurs in the stub tube 3, one possible solution is to remove the existing stub tube 3 and install a new stub tube 3. In this case, not only the stubbed cove 3 but also the CRD housing 2 will be replaced with a new one at the same time.

At that time, the height position of the CRD housing 2 and the core support plate 5
The height position is an important dimension for forming the reactor core 6. In particular, a control rod guide tube 7 is installed between the CRr) housing 2 and the core support plate 5 to house and cover the core control control rods, and this guide tube must be within a predetermined size limit due to installation accuracy. If l-J cannot be installed on the
After housing 2 and 1, core support J! The height difference from the I plate 5F product can be measured with very high accuracy.

Therefore, when CRD housing 2 is replaced,
It is necessary to measure and cover the height X between the top of the replaced new (CRD housing 2 and the -1-plane of the core support plate 5. However, the replacement of the CRr) housing 2, The reason for this is that the inside of the reactor pressure vessel 1 is filled with reactor water, and due to the environmental problems of the radiation limbs 1rIl'' and r1', 11
It was impossible for a contractor to enter the reactor and directly measure it, and it was difficult to accurately measure the difference between the top surface of the IC 1 part of the CRI housing and the core support. .

. [Objective of the Invention] Considering the above-mentioned circumstances, the present invention is to remotely and accurately measure the difference in height between the top of the CRI' housing and the top surface of the core support plate. This significantly reduces radiation exposure for production personnel! The purpose is to provide a remote measuring device.

[Summary of the Invention] In order to achieve the above-mentioned object, a remote measuring device according to the present invention includes a control rod drive mechanism housing installed in the lower mirror of a reactor pressure vessel via a stub tube.
A water seal pipe for removing reactor water is installed in the reactor pressure vessel so as to pass through the upper grid plate and the core support plate and cover the stubbed cove, and this water seal pipe is connected to the core support plate. It is characterized by being equipped with a non-contact type distance measuring device for measuring the height difference between the upper surface and the top of the control rod drive mechanism housing.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the telemetry device according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a reactor pressure vessel of a boiling water reactor, and a shroud 12 forming a reactor core 11 is accommodated within this pressure vessel 10.

A core support plate 13 that supports the reactor core 11 and an upper lattice plate 14 that support part of the reactor core are housed in the lower part of the shikoroud 12. The core support plate 13 has control rod guide tubes 15 inserted through it.
A number of ξ1 through holes are drilled 5, and a stubde cove 17 is welded 1+7n9 to the lower head plate of the reactor pressure vessel 10 corresponding to each hole, and the lower head plate extends through the stubde cove 17 by r''. A portion of the control rod drive (of the housing 18) is fixed by welding.

Thus, the control rod guide tube 15 is supported by riding on the top of the CRD housing 18, and the LIJ is mounted on the core support plate 1.
It is supported in the 11 through holes of 3, and the core fuel Fl
(/I f4 fuel assembly) One is removed. A control rod (41 in the figure) is housed in the control rod guide tube 15 so that it can be taken in and out. J: The sea urchin is turning. In this way, the height position of the core support plate 13
The height position of the housing 18 is an important dimension that forms and covers the reactor core 11, and the difference in height is remotely measured by a laser measuring device 20 as a non-contact type distance measuring device.

By the way, the stub that supports the CRC housing]-11
7 is welded to the lower end of the reactor pressure vessel 10, but if cracks occur at or near the welded part of the stub tube 17 due to poor welding or stress corrosion, the reactor Since reactor water may leak, the existing CRD housing 18 and stub tube 17 are removed, replaced with new stub tubes 17 and CRD housing 18, and covered.

Through this replacement work, a new stub tube 17 and CR
When the D housing 18 is attached, the difference in height between the top of the CRD housing and the upper surface of the core support plate 13 is an important dimension in forming the core, and is measured by the laser measuring device 20.

When performing this measurement, the CRD to be measured is
The reactor core 1119, control rods, and control rod guide tubes 15 on the upper part of the housing 18 are removed, and a new one is installed.A water seal pipe 22 is installed in the upper part of the CRD housing 18 to remove reactor water. will be erected. The lower end of the water seal pipe 22 is in watertight contact with the inner wall surface of the lower mirror of the reactor pressure vessel 10, and the upper part of the water seal pipe 22 is in contact with the Lq through hole of the core support plate 13). extending towards the top;
+Xi = t'''''' splat] - M 231 and terminates. Plans 1 to 23 are attached to one part of the flange part of the reactor pressure vessel 10, and then eight parts to cover [1]. J was handed over on the 11th.

A transfer lens 24 is provided on one outer peripheral surface of the water seal pipe 22.
is taken (=I lj. This transfer lane i+ 24 is installed at a distance of a little 10/i from the earth surface of the core support plate 13, and allows the contact 25 protruding downward to move forward and backward.

At this time, a base 111 point 0 is determined for the water seal pipe 22, and the distance from this IJ quasi-point O to the point at which the transfer is completed is predetermined. The pipe 22 is erected in the reactor pressure vessel 10, and the contact 25 is in contact with the -1- surface of the core support plate 13.
:S, the contact 25 is retracted in the electromagnetic coil of the transfer lens 1J'24, and then 313B! The force is applied to the cylinder 26 at the 1st position.
JtX can be measured.

On the other hand, a fouling plate 27 is detachably attached to the head of the newly removed CRD housing 18 as shown in FIG. will be installed. A laser measurement device 20 is composed of the laser oscillator 28, the reflection plate 27, and the photodetector 29. The coherent laser beam oscillated from the laser oscillator 28 passes through the water seal pipe 22, is reflected by the reflector 27 on the top of the CRr housing, returns to the laser oscillator 28, and is sent to the photodetector. 29. This detection is carried out by detecting the time delay between the oscillating laser beam and the anti-aluminum laser beam, and the detection signal is transmitted, for example, to channels, changeover switches, etc. 1-
It is sent to the counter 26 through the line 30, where it is sent to the counter 26.
and the distance from the laser oscillator 28 to the anti-0.1 plate 27 is 1
111 Y is measured.

Therefore, the distance Y measured by the laser measuring device 20
is calculated using the pre-measured distances 111 Let it go. The measured height difference is shown in the diagram.
It may be displayed continuously on a display device such as a display panel.

This indicator is connected to counter 26.

<rO, in the description of the embodiments of the present invention, the distance N1
We have explained an example using a laser measuring device that uses a laser beam as the measuring device, but what about an ultrasonic device that uses ultrasound instead of this laser measuring device?゛? Even if a non-contact type distance measuring device such as a wave measuring device is used, it is not possible.

[Efficacy of invention Song Dynasty]

As described above, the remote 'JI'I fixed installation according to the present invention
j is a water seal pipe for removing reactor water IJI installed in the reactor pressure vessel so as to cover the stub tube with the upper lattice plate and core support plate vl, and this water seal pipe Since a distance H1 measuring device was installed to measure the height difference between the upper surface of the core support plate and the control rod drive mechanism housing 10, this distance H1 measuring device was used to measure the height difference between the upper surface of the core support plate and the control rod drive mechanism housing 10. The distance to the mechanism housing ((i) can be measured remotely and continuously. Therefore, even if the control rod drive mechanism housing is in the process of being welded and the height changes from moment to moment, continuous measurement is possible. is possible.

Roughly, distance #1 between the core support plate-1 surface and the top of the control rod drive mechanism housing is determined using a non-contact type distance measuring device.
Since measurement can be performed remotely without direct contact with the object to be measured, exposure to radiation during measurement work can be significantly reduced. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the internal state of a boiling water reactor incorporating a remote measuring device according to the present invention, and FIG. 2 is a diagram showing a water seal pipe to which a laser oscillator and a transfer sensor are attached. FIG. 3 is a cross-sectional view showing the internal state of a boiling water reactor, and FIG. 4 is a diagram showing an assumed cracked state of a stub tube provided in the lower mirror of the reactor pressure vessel. 10...Reactor pressure vessel, 11...Reactor core, 12...
・Shikoroud, 13... Core support plate, 1/l... Upper grid plate, 15... Control rod guide tube, 17... Stub tube, 18... Control rod drive +ff +1"r housing, 20...Ray measurement device, 22...Water seal pipe, 2A...Transfer Pn1, 26...Counter, 27...1 foul, 28...1 nozzle Oscillator, 29... photodetector.

Claims (1)

[Claims] 1. A control rod drive mechanism housing is provided on the lower mirror of the reactor pressure vessel via a stub tube, and a water seal pipe for discharging reactor water into the reactor pressure vessel, A non-contact type distance is installed to penetrate the upper grid plate and core support plate and cover the stub tube, and this water seal pipe measures the height difference between the top surface of the core support plate and the top of the control rod drive mechanism housing. A remote measuring device comprising a measuring device. 2. The distance measuring device is a laser measuring device, and this laser measuring device includes a laser oscillator installed at the top of the water seal pipe and a control rod drive mechanism housing top that reflects the oscillated laser light from the laser oscillator. The distance from the laser oscillator to the reflector is determined from the time delay of the reflected laser light detected by the photodetector. A telemetry device according to claim 1 that performs measurement. 3. A transfer sensor is provided on the outer periphery of the water seal pipe, and this transfer sensor has a contact that can move forward and backward in contact with the upper surface of the core support plate when the water seal pipe is erected. The telemetry device according to claim 1, wherein the distance to the tip of the contact of the sensor is predetermined.