KR20180082990A - Apparatus for preventing radiation exposure of an inspection apparatus of a calandria - Google Patents

Abstract

The present invention relates to an apparatus for preventing radiation exposure of a calandria internal structure inspection tool, capable of performing a visual inspection by inputting a measurement device for inspecting an internal structure through an observation hole prepared in a calandria container. An apparatus for preventing radiation exposure of a system for inspecting a calandria internal structure by inputting the calandria internal structure into an observation hole (VP) provided in a calandria container (10) and vertically lifting the same comprises: a chamber (500) provided on the upper part of the calandria container (10) in which the observation hole (VP) is located, and provided in a transfer section of a rod unit (200) in which the measurement instrument (100) is fixed to the lower end; and a vacuum source (610) connected to the chamber (500) to generate negative pressure.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus for preventing radiation exposure of an internal structural inspection apparatus,

The present invention relates to an apparatus for preventing radiation coating of a calandria internal structure inspection apparatus capable of performing a visual inspection by inserting an instrument for inspecting an internal structure through an observer on a calandria vessel.

Generally, the pressurized heavy water reactor is a reactor using heavy water as a coolant and a moderator, and the CANDU model developed in Canada is representative. In Korea, Wolsong 1,2,3,4 employs pressurized heavy water reactor.

The pressurized heavy water reactor uses unconcentrated natural uranium (about 0.7% of U-235) unlike the light water reactors (pressurized light water reactor and boiling light water reactor) that use 2-5% low enriched uranium and is used as coolant and moderator Heavy water does not absorb much neutrons as compared to normal water, so there is little neutron loss and uses natural uranium as fuel.

Meanwhile, the light-water reactor exchanges the fuel after stopping the reactor, while the pressurized heavy-water reactor uses 380 fuel pipes of horizontal cylindrical shape to replace the fuel during operation.

Specifically, a cylindrical reactor called Calandria is installed horizontally in the water reactor during pressurization. In the calandria, 380 pressure tubes having a diameter of about 10 cm are also horizontally penetrated, Nuclear fuel is supplied in a pressure vessel in the form of a bundle (fuel bundle), and one pressure tube is usually supplied with 12 fuel assemblies.

As the use period of the heavy water reactor becomes longer, the necessity of directly inspecting the state of the internal structure of the reactor is increased, and it is required to develop a device capable of directly inspecting the interior of the reactor.

In addition, it is possible to inspect the calandria tube and the pressure tube when it is removed to replace the calandria tube and the pressure tube. However, the calandria tube and the pressure tube replacement are usually carried out after 20 years of operation, To confirm the integrity of the internal structure without removing the drainage pipe and the pressure pipe, visual inspection is carried out through an observer above the calandria container. Therefore, it is required to develop a visual inspection device for inspecting internal structures of a calandria container having a high-level radiation environment and a complicated structure without existing equipment developed.

1 is a schematic view showing a reactor structure of a general pressurized heavy water reactor.

1, a general pressurized water reactor is provided with a calandria tube (CT) 20 horizontally in a cylindrical calandria vessel 10, and a pressure tube is installed inside the calandria tube 20 And fuel is loaded in the inside of the fuel cell.

In addition, in addition to the calandria tube 20, many tubes are installed in the calandria vessel 10 in a horizontal or vertical direction, and in particular, a safety system liquid injection nozzle (LIN) And is installed at a right angle to the pipe (20).

As the operation history of the power plant is increased, the calandria tube 20 installed horizontally as described above is subject to sagging due to growth and creep in the material due to stress, irradiation, etc. , Where the calandria tube 20 may contact the reactor shut-off tube to affect the safe operation of the power plant. Thus, there is a need to identify the proper spacing between the calandria tube and other tubes (especially the injection tube) in the reactor during the life of the reactor.

Conventionally, there has been proposed a method for directly or indirectly measuring the distance between a calandria tube and a reactor stopper material injection tube, for example, a method using a reactor stop material injection tube, a horizontal placement between the calandria tubes A method using a horizontal flux detector, a method using a vertical flux detector, a method using a viewing port (VP), and the like.

The observer (VP) is located in two vertical positions in the upper part of the calandria and is used for internal observation, and the start-up unit including the neutron source is inserted during the initial operation of the reactor It is a hole, and there is no use after that. Therefore, the method through the observer (VP) is advantageous in the convenience of measurement work, economical efficiency, and other reliability since it is possible to perform direct measurement while minimizing preliminary preparation work such as field design change or replacement of neutron detector.

However, when inserting a measuring instrument through an observer (VP) and inspecting it, it is difficult to stably insert the measuring instrument because the depth is more than 10 meters. In addition, an unstable situation occurs in the inspection process, It is impossible to recover it if it remains inside the dria and it can seriously affect the operation of the reactor.

Therefore, it is very important to minimize the risk of such accidents by inspecting the internal structure through the VP, thereby preventing safety accidents and performing stable inspection.

Japanese Patent Application Laid-Open No. 10-2014-0042009 (public date: April 4, 2014)

The present invention relates to a calandria inner structure inspection apparatus for inspecting an inner structure of a pressurized heavy water reactor through an instrumentation unit using an observer (VP) above the calandria vessel, (Hereinafter, also abbreviated as "radiation covering device").

In order to accomplish the above object, according to the present invention, there is provided an apparatus for preventing radiation exposure of a system for vertically elevating and inspecting a calandria internal structure inspection instrument into an observation hole provided in a calandria vessel, A chamber provided at an upper portion of the calandria vessel in which the observation hole is located, the chamber being provided in a transfer section of the rod section where the measuring instrument is fixed at the lower end, And a vacuum source for generating a negative pressure inside the chamber.

Preferably, the chamber comprises: a first chamber for blocking the flow of radioactive water; And a second chamber defined by the first chamber and operated by a negative pressure by the vacuum source.

More preferably, the first chamber includes an inverted cone-shaped blocking block surrounding the outer circumferential surface of the rod portion.

The apparatus for preventing radiation exposure of the present invention includes a chamber which is located at an upper portion of a calandria container in which an observer is located and which is provided in a conveying section of the rod portion and a vacuum source which is connected to the chamber to generate a negative pressure, It is possible to prevent the worker from being exposed to the high-level radiation by preventing the worker from escaping from the inside of the calandria vessel to the outside of the radioactive heavy water during the ascending and descending,

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a structure of a calandria reactor in a general pressurized heavy water reactor,
FIG. 2 is an overall configuration diagram of a calandria internal structure inspection apparatus equipped with a radiation exposure prevention apparatus according to the present invention,
FIG. 3 is an enlarged schematic view of a main portion of a radiation exposure prevention apparatus according to the present invention. FIG.

The specific structure or functional description presented in the embodiment of the present invention is merely illustrative for the purpose of illustrating an embodiment according to the concept of the present invention, and embodiments according to the concept of the present invention can be implemented in various forms. And should not be construed as limited to the embodiments described herein, but should be understood to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Meanwhile, in the present invention, the terms first and / or second etc. may be used to describe various components, but the components are not limited to the terms. The terms may be referred to as a second element only for the purpose of distinguishing one element from another, for example, to the extent that it does not depart from the scope of the invention in accordance with the concept of the present invention, Similarly, the second component may also be referred to as the first component.

Whenever an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but it should be understood that other elements may be present in between something to do. On the other hand, when it is mentioned that an element is "directly connected" or "directly contacted" to another element, it should be understood that there are no other elements in between. Other expressions for describing the relationship between components, such as "between" and "between" or "adjacent to" and "directly adjacent to" should also be interpreted.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It will be further understood that the terms " comprises ", or "having ", and the like in the specification are intended to specify the presence of stated features, integers, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

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

2 is an overall configuration diagram of a calandria internal structure inspection apparatus equipped with a radiation exposure prevention apparatus according to the present invention.

2, the calandria internal structure inspection equipment includes a measuring instrument 100, a rod portion 200 to which the measuring instrument 100 is fixed at the lower end, A chamber 500 provided in the transfer section of the rod section 200 provided on the upper part of the calandria vessel 10 in which the observation port VP is located, And a vacuum source for generating a negative pressure.

The measuring instrument 100 may include a camera for visually inspecting the internal structure, a laser distance measuring unit for calculating the distance of the object to be irradiated, a lighting device, and the like. The measuring means may include a lead shield A lead glass or the like, and the signal can be transmitted by the shielded cable 110 for the noise influence of the transmission signal due to radiation or the like.

The rod unit 200 may be a rigid body that can move up and down by supporting the measuring instrument 100 provided at the lower end of the rod unit 200. The rod unit 200 can be vertically operated .

On the other hand, the rod unit 200 may be a pipe having a hollow receiving hole, and a cable 110 for receiving an electric signal of the measuring device in the measuring device 100 or an electric power for driving the electric device may be accommodated therein . Such a cable 110 may be drawn along the rod part 200 and connected to a controller including a monitor.

Meanwhile, the rod unit 200 may be composed of a plurality of unit rods that can be assembled and connected to each other in multiple stages by a fastening member. Preferably, a stopper 210 protrudes horizontally from the upper end of the rod portion 200.

The stopper 210 is provided to prevent the rod 200 from dropping freely due to an unfavorable situation and causing the rod 200 to fall down inside the calanderia vessel 10, The stopper 210 can prevent falling of the rod unit 200 by preventing the stopper 210 from falling when the rod unit 200 is free to fall. In this embodiment, the chamber 500 is formed with a hole through which the rod portion 200 passes, and this hole is smaller than the size of the stopper 210, and thus the chamber 500 can function as a fall preventing means.

The vertical driving unit 300 includes at least two clamps 310 and 320 for fixing the rod unit 200 and a first driving unit for vertically moving the clamps 310 and 320.

The clamps 310 and 320 in this embodiment include a first clamp 310 and a second clamp 320 provided at the lower end of the first clamp 310. The first clamp 310 and the second clamp 320 (320) is fixed to the clamp transfer block (330), and the clamp transfer block (330) is moved up and down by the first drive part. The first clamp 310 and the second clamp 320 may be clamps having the same structure capable of detachable attachment or may be a well-known clamp having a mutual structure.

The first driving part includes a body part 341, a screw 342 which is installed vertically to the body part 341 and is rotatable so that the clamp transfer block 330 is vertically moved up and down along the rotation direction, And a driving motor 343 for rotating or rotating the screw 342. The driving motor 343 may further include a bearing 344 for supporting rotational movement of the screw 342. [

The vertical driving unit 400 may further include a second driving unit 412 for rotationally driving the wheel for winding or unwinding the wire 411. The second driving unit 412 may further include: And can be provided by a known electric motor capable of forward rotation or reverse rotation. One or a plurality of pulleys 413 may be provided to guide the wire 311 in the winding direction.

The chamber 500 is provided at an upper portion of the calandria vessel 10 where the observation point VP is located and is formed by a vacuum source to effectively remove the radioactive material that can be emitted to the outside through the observation hole VP can do.

The chamber 500 may be directly seated on the upper portion of the calandria vessel 10 or may be provided at a suitable position within the transfer section of the rod portion 200 above the calandria vessel 10. In this embodiment, the chamber 500 is positioned above the plate 345 on which the first driving unit and other structures are installed.

The vacuum source may generate a negative pressure inside the chamber 500 and may be provided by a well-known vacuum pump 610. Preferably, the discharge end of the vacuum pump 610 is provided with a pump for purifying the exhaust gas A purification processing unit 620 may be provided.

The purification treatment unit 620 removes the radioactive material contained in the exhaust gas and discharges the purified gas to the atmosphere.

FIG. 3 is an enlarged schematic view of a main part of a radiation exposure prevention apparatus according to the present invention.

3, the exposure control apparatus may include two first chambers 520 and a second chamber 530 partitioned by a separation plate 510, and the first chamber 520 may include an observer VP of the second chamber 530. The second chamber 530 generates a negative pressure by a vacuum source connected to the vacuum port 531 to prevent the radioactive material from being directly discharged to the outside.

The first chamber 520 may be provided with an inverted cone-shaped blocking block 521 surrounding the outer circumferential surface of the rod portion 200. The blocking block 521 may be formed on the outer circumferential surface of the rod portion 200 A certain amount of friction is generated to remove radioactive heavy water adhering to the surface of the rod unit 200 when the rod unit 200 is lifted. The removed heavy water is then returned to the calandria vessel through the observer VP.

The blocking block 521 generates a frictional force with the outer circumferential surface of the rod portion 200 within a range that does not hinder the vertical movement of the rod portion 200. If necessary, The rubbing protrusions 521a may be provided to friction with the roller 200 so that heavy water can be removed from the surface of the rod portion 200 without causing a large load when the rod portion 200 is lifted or lowered.

In the present embodiment, the plate 345 is formed at a lower portion of the chamber 500 with a predetermined inclined surface 345a toward the observer VP so that a part of the heavy water removed by the blocking block 521 is adhered to the plate 345 prevent.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be apparent to those of ordinary skill in the art.

100: Measuring instrument 200:
300, 400: vertical driving means 500: chamber
510: separator plate 520: first chamber
530: Second chamber 610: Vacuum pump
620:

Claims (3)

An apparatus for preventing radiation exposure of a system for vertically elevating and inspecting a calandria internal structure inspection device by inserting it into an observer provided in a calandria vessel,
A chamber provided at an upper portion of the calandria vessel in which the observation hole is located, the chamber being provided in a transfer section of a rod unit to which a meter is fixed at a lower end,
And a vacuum source for generating a negative pressure inside the chamber. The apparatus of claim 1,
A first chamber for blocking outflow of heavy water;
And a second chamber partitioned by the first chamber and operated by a negative pressure by the vacuum source. The apparatus according to claim 2, wherein the first chamber includes an inverted cone-shaped blocking block surrounding the outer circumferential surface of the rod portion.

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