JPH04297898A - Recovering device for control element for high-temperature gas-cooled reactor - Google Patents

Abstract

PURPOSE:To prevent that a filter is clogged by abrasion powder of a control element and deteriorates in suction of a gas and consequently it becomes impossible to recover the control element, and thereby to improve the efficiency and safety of a recovery operation. CONSTITUTION:A hole part 26a communicating with a suction port 27a of a blower 27 is provided in a ceiling part of a hopper 26, a filter 30 being made coaxial with the hole part 26a and rotatable is fitted on the lower side of the ceiling part of the hopper 26, and a moving blade 34 is fitted on the inside of this filter 30 so that it is integrated therewith. Besides, a brush 31 coming into slidable contact with the outer periphery of the filter 30 is fitted to the hopper 26.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control element recovery device for a high-temperature gas furnace, and more particularly to a structure for preventing clogging of a filter attached to the inlet of a blower.

0003

2. Description of the Related Art Generally, nuclear reactions in nuclear reactors are controlled by inserting and removing control rods into and from the reactor core using a control rod drive device, and when the reactor is shut down, the control rods are fully inserted. This reactor shutdown function is extremely important, and must operate reliably even in the event of a reactor abnormality, so in normal nuclear reactors, in addition to the main reactor shutdown system using the control rod drive device, a separate system is required. A nuclear reactor shutdown system is also installed in the system.
Heavy and triple safety measures are in place.

FIG. 5 is a schematic cross-sectional view showing the general structure of a conventional high-temperature gas furnace. In the figure, a reactor core 2 is housed in a reactor vessel 1, graphite blocks acting as a moderator are stacked inside the reactor core 2, and fuel rods 3 are loaded in these graphite blocks. Furthermore, a gas having a large specific heat, such as helium gas, is circulated as a coolant within the reactor vessel 1. This helium gas is supplied to the reactor vessel 1 from an inlet pipe 4 communicating with the bottom of the reactor vessel 1.
It flows into the reactor core 2 and is heated to a high temperature.
It is discharged through an outlet pipe 5 which is arranged concentrically inside the inlet pipe 4 and communicates with the bottom of the reactor core 2 . The high-temperature helium gas from the outlet pipe 5 exchanges heat with an external coolant in the heat exchanger 6, and then is returned to the reactor vessel 1 by the circulation device 7. The external coolant that has undergone heat transfer in the heat exchanger 6 is sent to a required location by a circulation system (not shown) and is used for power generation or process heat.

In the figure, reference numeral 8 indicates a control rod drive device, and the control rod drive device 8 includes a wire rope 10 for suspending the control rod 9, a drum 11 for winding in and letting out the wire rope 10, The control rod 9 is inserted into and removed from the core 2 by forward and reverse rotation of the drum 11 by the motor 12, and the output of the core 2 is controlled. In addition, a backup reactor shutdown device 13 is installed in case the control rod drive device 8 becomes inoperable. This back-up reactor shutdown device 13 includes a hopper 15 that accommodates a control element 14 containing a neutron absorbing material and has a rupture disk 16 on the bottom surface that breaks at a predetermined pressure, and a hopper 15 (not shown) in which it is necessary to shut down the reactor in the event of an abnormality. The hopper 15 is provided with a valve 17 that is opened in response to an emergency signal issued by a sensor and sends hot gas from a hot gas source 18 into the hopper 15 . Note that a control element insertion hole 19 is installed in the core 2 at a position directly below the hopper 15, and when the rupture disk 16 is destroyed by introducing high pressure gas, the control element 14 in the hopper 15 is inserted into the control element insertion hole 19. It was dropped into the reactor and stopped the nuclear reaction in the reactor core. Here, the control element 14 is made of a neutron absorber such as boron carbide (B4C) molded into a cylindrical or spherical shape.

[0006] In the figure, reference numeral 20 indicates a plurality of stand pipes, which protrude from the upper surface of the reactor vessel 1. The control rod drive device 8 and the backup reactor shutdown device 13 are installed within this standpipe 20. Although the control rod drive device 8 and the backup reactor shutdown device 13 are actually installed at a plurality of locations, only one is shown in FIG. 5 for simplicity of illustration.

[0007] However, when the back-up reactor shutdown device 13 is activated in the high-temperature gas reactor with the above configuration, the control element 14 is dropped and accommodated in the control element insertion hole 19, so that the reactor is not activated. It is necessary to collect this in order to restart. The collection operation will be explained with reference to FIG. Note that the same parts as in FIG. 5 are given the same reference numerals. That is, FIG. 6 is a schematic cross-sectional view for explaining the configuration and operation of the conventional control element recovery device 21. As shown in FIG. In the same figure, a control element recovery device 21 is attached to a standpipe 20 of a reactor vessel 1, and sucks helium gas in the reactor core 2 by reducing the pressure with a blower or the like, and carries the flow of helium gas into a control element insertion hole 19. a recovery section 22 that sucks and recovers the control element 14; a recovery tube 24 that hangs down from the lower end of the recovery section 22 and is equipped with a suction nozzle 23 at the lower end; and a recovery tube 24 that is installed above the recovery section 22 and drives the recovery tube 24 in the vertical direction. The winding machine 25 is equipped with a hoisting machine 25. However, the hoisting machine 25 may not be included in the element recovery device 21 and a separate hoisting machine for a handling machine (not shown) may be used.

The collection section 22 is configured as shown in FIG. 7, for example. That is, a hopper 26 that sucks and collects the control element 14 in the control element insertion hole 19 through a recovery pipe 24 and a blower 27 that is installed so as to suck gas in the hopper 26 and discharge it outside the hopper 26. , a filter 28 attached to the inlet of the blower 27 and provided to prevent the control element 14 and the abrasion powder of the control element 14 from flowing into the blower 27, and the hoisting machine 25.
A guide tube 29 that guides the vertical movement of the hopper 26 by
It consists of The collection pipe 24 has an upper end connected to a hopper 26.
It is inserted into the inside of the hopper 26 and led out from the lower part of the hopper 26 and extends into the control element insertion hole 19.

When the pressure inside the hopper 26 becomes lower than the furnace internal pressure by driving the blower 27, the gas inside the control element insertion hole 19 is sucked through the suction nozzle 23, passes through the recovery pipe 24, and enters the hopper 26. Inflow. This gas flow causes the control element 1 in the control element insertion hole 19 to
4 is sucked up, discharged from the upper end of the recovery pipe 24, and stored in the hopper 26. At this time, the wear powder of the control element 14 is accommodated in the hopper 26 together with the control element 14, or is captured in the filter 28. Therefore, clean gas is drawn into the blower 27 and discharged out of the hopper 26. As the recovery of the control elements 14 progresses, the amount of the control elements 14 in the control element insertion hole 19 decreases, and the distance between the suction nozzle 23 and the upper surface of the control element stack increases, resulting in poor suction. 25 is activated to lower the recovery pipe 24 together with the hopper 26 as the deposited layer decreases, thereby efficiently recovering all the control elements 14 in the control element insertion hole 19.

0010

[Problems to be Solved by the Invention] As explained above, the abrasion powder of the control element 14 generated during collection is removed by the filter 28.
captured by. Therefore, as the collection time increases, the filter 28 becomes clogged. As this clogging progresses, gas suction becomes poor and the control element 14
recovery becomes impossible. In such a situation, the recovery operation may be interrupted, the recovery operation may be interrupted, the element recovery device 21 must be taken out of the furnace, and then the filter 28 must be cleaned to regenerate it or the filter 28 must be replaced. Efficiency may be significantly reduced and work may become dangerous.

[0011] The present invention was made to solve the above problems, and it is possible to automatically and safely prevent clogging of the filter while the collection operation is still in progress, thereby improving the efficiency and safety of the collection operation. It is an object of the present invention to provide a control element recovery device for a high-temperature gas reactor that can be improved. [Structure of the invention]

0012

[Means for Solving the Problems] The present invention provides a hopper for accommodating control elements hoisted and recovered by a hoist, a blower for making the inside of this hopper a low pressure, and a filter attached to an inlet of this blower. In a high-temperature gas reactor control element recovery device equipped with a recovery pipe that is led downward from the inside of the hopper and sucks up the control elements in the control element insertion hole of the reactor core into the hopper, the filter causes the inside of the hopper to reach a low pressure state. It is equipped with a clogging prevention mechanism that operates when the

[0013]

[Operation] By creating a low pressure inside the hopper with a blower, the control element in the control element insertion hole in the core is sucked up into the hopper through the recovery pipe, and at the same time, the clogging prevention mechanism operates to open the blower inlet. This prevents the filter attached to the part from clogging and allows the collection work to be carried out smoothly and reliably.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially sectional view showing an enlarged main part of an embodiment of the present invention. Note that the same parts as in the conventional example shown in FIGS. 5 to 7 are given the same reference numerals, and redundant explanation will be omitted. In FIG. 1, 26 is a hopper, and this hopper 2
6 is provided with a hole 26a which is coaxial with the inlet portion 27a of the blower 27 and has approximately the same diameter as the inlet portion 27a of the blower 27, and a filter 30 which is rotatable coaxially with the hole 26a.
Then, a brush 31 is attached so as to be in sliding contact with the outer periphery of this filter 30. The filter 30 is composed of a filter body 32 and a rotating support 33 that is integrally fixed to the upper surface of the filter body 32 by adhesive or other means. Here, the filter main body 32 is formed of a filtering material and is integrally composed of a cylindrical part whose inner diameter is approximately the same as the inner diameter of the hole 26a, and a bottom part that closes the lower opening surface of this cylindrical part. The rotating support body 33 is formed into an annular shape, and has an inner diameter that is approximately the same as the inner diameter of the filter body 32 and an outer diameter that is slightly larger than the outer diameter of the filter body 32 . Further, a disk-shaped support member 32a is integrally provided at the bottom center of the filter body 32, and this support member 32a
A rotating blade 34 is integrally provided via the rotary blade 34. Here, the rotary blade 34 is arranged coaxially with the hole 26a, has a lower end attached to the support member 32a, and has an upper end attached to the hole 26a.
It is composed of a shaft 34a extending up to a point a, and a blade 34b fixed to the upper end of the shaft 34a. On the other hand, a bearing support stand 35 is fixed to the inside upper part of the hopper 26 with bolts 36, and supports a ball bearing 37 between it and the rotary support body 33 of the filter 30, so that the filter 30 is rotatably supported in the hopper 26. ing. Note that the brush 31 is also attached to this bearing support base 3.
It is attached to 5.

Next, the operation of the embodiment configured as above will be explained. When blower 27 is started, hopper 2
6 passes through the filter 30 and is sucked into the blower 27. At this time, the rotating blade 3 is
4 receives rotational force. Therefore, the filter 30 to which the rotary vanes 34 are attached is rotatably supported by the hopper 26 and therefore rotates. In other words, by operating the blower 27 and continuing to suck gas, the filter 30
rotates continuously. On the other hand, since the brush 31 is attached so as to be in contact with the surface of the filter 30, when the filter 30 rotates, the abrasion powder of the control element 14 adhering to the surface of the filter 30 is brushed off by the brush 31. Therefore, a function is provided that can automatically prevent the filter 30 from clogging during the collection operation.

As described above, according to the present embodiment, the filter can be prevented from clogging even during the recovery operation, and maintenance and maintenance of the recovery device can be performed safely and efficiently.

[0017] The present invention is based on the above-mentioned embodiments (hereinafter referred to as
The present invention is not limited to the first embodiment, and various modifications can be made. FIG. 2 is a partially enlarged sectional view showing a main part of another embodiment of the present invention, and FIG. 3 is a sectional view taken along the line A--A in FIG. 2. In FIGS. 2 and 3, 26 is a hopper, and a hole 26a is provided in the ceiling of the hopper 26, which is coaxial with the inlet 27a of the blower 27 and has a diameter that is approximately the same as the inner diameter of the inlet 27a. A bellows 40 that is coaxial with the hole 26a, a filter 41 that is coaxial with the lower part of the bellows 40, and brushes that are equally distributed at four locations along the outer circumferential direction of the filter 41 and come into sliding contact with the outer circumference. Install 42. The bellows 40 is composed of a bellows main body 43 and flanges 43 and 44 that are fixed to the upper and lower ends of the bellows main body 41 and have the same inner diameter as the inner diameter of the hole 26a.
3 is fixed to the lower surface of the ceiling of the hopper 26 via bolts 45. The filter 41 also includes a filter body 47 and a flange 48 that is integrally fixed to the upper surface of the filter body 47 by adhesive or other appropriate means, and has the inner and outer diameters of the flange 44 of the bellows 40 that are the same diameter. It is configured. Here, the filter main body 47 is formed of a filtering material and is integrally composed of a cylindrical part whose inner diameter is approximately the same as the inner diameter of the hole 26a, and a bottom part that closes the lower opening surface of this cylindrical part. has been done. The bellows 40 and filter 41 configured as described above are kept airtight through the packing 49 inserted into the groove of the flange 48 and are tightened with the bolts 50. Furthermore, the brush 42 has a shaft body 51
and a brush body 52 fixed to this shaft body 51. Here, the shaft body 51 supports the weight of the filter 41 and functions as a guide rod for the bellows 40 and the filter 41, and has a large diameter part 51a in the middle, and the part above the large diameter part 51a is the flange 44. By passing through the hole 48, the expansion and contraction of the bellows 40 and the accompanying vertical movement of the filter 41 are guided, and the lower surface of the flange 48 comes into contact with the upper surface of the large diameter portion 51a, thereby supporting the weight of the filter 41. Note that a threaded portion is provided at the upper end of the shaft body 51, and the shaft body 51 is fixed by screwing into the flange 43.

Next, the operation of another embodiment configured as described above (hereinafter referred to as the second embodiment) will be explained. The blower 27 is started to reduce the pressure inside the hopper 26, and the control element 14 inside the control element insertion hole 19 is sucked up into the hopper 2.
Contained within 6. Control element 1 generated during this recovery work
Since the abrasion powder No. 4 adheres to the filter 41 and is captured, clean gas flows into the blower 27 and is discharged. Here, if the amount of attached wear powder increases and clogging occurs, the pressure loss of the filter 41 increases, and the filter 41 becomes clogged.
The pressure difference between the inside and outside of 1 increases. Naturally, the pressure on the outside increases, so the bellows 40 contracts and the filter 41 is lifted upward. At this time, the brush 42
Since the filter 41 is in contact with the filter 41, abrasion powder adhering to the surface of the filter 41 is brushed off. If the abrasion powder is not completely removed in one operation, stopping the blower 27 equalizes the pressure inside and outside the filter 41, so the bellows 40 stretches and returns to its original position, and the filter 41 also lowers. Restart the blower 27, and if the filter 41 is still clogged, replace the filter 41 as described above.
is lifted upwards. By moving the filter 41 up and down by starting and stopping the blower 27, abrasion powder can be more effectively removed. On the other hand, since the filter 41 is attached to the expandable bellows 40 in a suspended state, a large diameter portion 51a is provided on the shaft body 51 of the brush 42 as a stopper to prevent the bellows 41 from being fully extended under normal conditions. ing. In other words, the above configuration is
Similar to the first embodiment described above, the automatic clogging prevention function of the filter 41 is provided. Therefore, according to the second embodiment, clogging of the filter can be prevented by simple operations such as starting and stopping the blower while in the recovery operation state, and maintenance and maintenance of the recovery device can be performed safely and efficiently.

Further, as a monitoring device for ensuring that the action of the second embodiment described above is carried out, a filter 4 is used.
It is also possible to install a pressure gauge that measures the pressure difference between the inside and outside of the filter 1, or a linear displacement gauge such as a potentiometer that monitors the amount of movement of the filter 41 as shown in FIG. 4 (third embodiment). Of course, the above-mentioned pressure gauge and linear displacement gauge 5
A combination of 3 may be used. That is, the pressure difference between the inside and outside of the filter 41 is measured using a pressure gauge (not shown), and the pressure difference between the inside and outside of the filter 41 is measured.
The occurrence of clogging in step 1 can be confirmed, and the linear displacement meter 53 can directly monitor the movement of the filter 41 up due to the clogging of the filter 41 and the downward movement of the filter 41 due to clogging improvement, so it has the effect of an automatic clogging prevention function. , can contribute to determining whether to start or stop the blower 27 to prevent filter clogging. In the second embodiment, the brush is fixed and the filter moves up and down, but a bellows is attached to the bottom surface of the filter, and a shaft body functioning as a guide rod is fixed to the free end of the bellows. By attaching the brush body to the shaft so as to be in sliding contact with the filter surface, it is also possible to have a configuration in which the filter is fixed and the brush moves up and down, and the same effects as in the second embodiment can be obtained. Further, in the first embodiment, the filter is rotated and the brush is fixed, but instead, the filter can be fixed and the brush rotated, and the same effects as in the first embodiment can be obtained.

[0020]

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent clogging of the filter and regenerate it while the control element is still in the recovery operation state, so maintenance and maintenance of the recovery device can be carried out safely and efficiently. At the same time, it is possible to provide a control element recovery device for a high-temperature gas reactor that allows recovery work to be performed smoothly and reliably, restarts the reactor smoothly, and greatly improves the operating rate and reliability of operation management.

[Brief explanation of drawings]

FIG. 1 is a partially sectional view showing an enlarged main part of an embodiment of the present invention.

FIG. 2 is a partial sectional view showing an enlarged main part of another embodiment of the present invention.

FIG. 3 is a sectional view taken along line A-A in FIG. 2;

FIG. 4 is a partial sectional view showing an enlarged main part of still another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view schematically showing the configuration of a conventional high-temperature gas furnace.

FIG. 6 is an explanatory diagram showing a state in which control elements filled in the reactor core are recovered in the conventional high-temperature gas reactor shown in FIG. 5;

FIG. 7 is a longitudinal sectional view showing the configuration of the conventional control element recovery device for a high temperature gas reactor shown in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Reactor vessel, 2...Reactor core, 14...Control element, 19...Control element insertion hole, 20...Stand pipe, 24...Recovery pipe,
25... Winding machine, 26... Hopper, 27... Blower, 30
, 41... Filter, 31, 42... Brush, 34... Rotating vane, 40... Bellows, 51... Shaft body.

Claims (1)

[Claims] Claim 1: A hopper for storing control elements hoisted and recovered by a hoist, a blower for making the inside of this hopper low pressure, a filter attached to an inlet of this blower, and a filter for lowering the pressure from the inside of the hopper. In a control element recovery device for a high temperature gas reactor, which is equipped with a recovery pipe that sucks up the control element in the control element insertion hole of the reactor core into the hopper, when the inside of the hopper is brought into a low pressure state by the filter. A control element recovery device for a high-temperature gas furnace, characterized in that it is equipped with a clogging prevention mechanism that operates.