JPS6110794A - Regulator for holding force of jet pump - 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 jet pump that adjusts the downward holding force of a cooling water circulation jet pump installed in the downcomer section of a boiling water reactor by remote control from above the reactor. The present invention relates to a holding force adjustment device.

[Technical background of the invention and its problems]

In a boiling water reactor, a jet pump for circulating cooling water is installed in the downcomer of the reactor pressure vessel. During regular inspections of nuclear reactors, feed rods and control rods are removed and inspected.
Jet pumps and other equipment inside the furnace are inspected using a television camera suspended from the operating floor above the furnace, without removing them. Jet pumps are exposed to relatively harsh operating environments among furnace equipment,
Ultrasonic flaw detection is also performed to confirm the integrity of the product.

In the unlikely event that a microscopic defect is discovered through this flaw detection and it is determined that it will impede reactor operation, replacement work will be carried out.

By the way, a jet pump has a vertical pump body equipped with a nozzle, and the upper end of the pump body is connected to the upper end of a vertical cooling water supply pipe fixed to the reactor pressure vessel via an inverted U-shaped elbow. It has a suspended and connected configuration. The cooling water rising along the inside of the cooling water supply pipe flows downward through the elbow and is blown out from the lower end of the pump body. As a result, several tons of upward fluid force is generated in the pump body and elbow.

Therefore, the upper part of the elbow is generally held down by a horizontal holding beam to prevent it from floating due to fluid force and to prevent damage to equipment due to fluid vibration, etc. However, when replacing this holding beam, it is difficult to remove and install it. There were problems that required skill or a lot of effort.

That is, the holding beam is usually supported at both ends by fitting into grooves of a pair of ears rising up from the upper end of the cooling water supply pipe. A push-down bolt is screwed into the approximately central portion of this holding beam from above, and the tip of the screw-inserted push-down bolt is pressed against the top of the pump with a tightening force of more than 10 tons. In other words, the holding beam is
When the top of the pump is pressed down and a large initial load is applied via the bolt, it is held down and held in a state where it flexes upward in a convex shape.

In this way, the holding beam holds down the top of the pump with a load of more than 10 tons, so even if it becomes necessary to replace it as a result of a flaw detection inspection, it can be replaced from the top of the furnace more than 10 meters away. It is extremely difficult to rotate the holding beam using a long wrench or the like to remove it from the fitting portion.

Therefore, the holding beam is first lifted with a force greater than the initial load applied by the push-down bolt, elastically curved upward, and the hold-down bolt is loosened to move it away from the elbow. It is common to remove the beam by rotating it. When installing, follow the steps in reverse. However, in the past, the equipment for performing this operation was individually configured and complicated, and when suspending multiple units from the downcomer, it was necessary to position each unit at a predetermined position to avoid interference with equipment above the downcomer. There are problems that are difficult and require skill. Further, since operations such as lifting and releasing the holding beam and rotating operations of the push-down bolt are performed independently using separate devices, operability is poor and work efficiency is also poor.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and aims at compactness by combining all the functions necessary for adjusting the holding force of a holding beam into a skewer configuration, and requires skill to operate. The purpose of the present invention is to provide a jet pump holding force adjustment device that can be easily and efficiently adjusted.

[Summary of the invention]

In order to achieve the above object, the present invention provides a plurality of jet pumps in the downcomer section of a nuclear reactor pressure vessel, and the tops of the jet pumps are pushed by a horizontal holding beam and a push-down bolt screwed into the beam from above. In a device that is held down and the push-down bolt is adjusted from above the furnace, there is a vertical O-rad that is suspended from the top of the furnace and has an engaging part for operating the push-down bolt at its lower end, and a vertical rod that is suspended from the top of the furnace. An elevating frame mounted on the outer circumferential side so as to be movable up and down relative to the vertical zero, a support leg that protrudes from the lower end of the elevating frame so as to be able to move forward and backward and comes into contact with the top of the jet pump, and a support leg that can be rotated by the elevating frame. The holding beam is configured to include an arm for elastic deformation of the holding beam, which is provided so as to be detachable from the lower side of the holding beam.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

First, the configuration of the jet pump and the holding beam will be explained with reference to FIGS. 2 to 5.

FIG. 2 schematically shows the internal structure of a boiling water reactor. A reactor core is housed in a reactor pressure vessel 1, surrounded by a shroud 2, and immersed in cooling water. A plurality of control rod drive mechanisms 3 are provided below the reactor core, penetrating the lower mirror portion of the reactor pressure vessel, and the control rod drive II structures 3 are used to move the control rods up and down within the reactor core. A plurality of jet pumps 4 are disposed in the annular gap between the reactor pressure vessel 1 and the shroud 2, that is, in the downcomer part, and the jet pumps 4 blow out cooling water below the reactor core and circulate the cooling water from below the core to above. That's what I do. Cooling water taken out from a recirculation nozzle 5 provided at the lower part of the reactor pressure vessel 1 is pumped to the jet pump 4 by a recirculation pump (not shown).

Additionally, a steam separator 6 is installed above the core, and a steam dryer 7 is installed above the steam separator 6. Steam from this steam dryer 7 is supplied to the outside from a main steam nozzle 8. Further, a water supply nozzle 9 is provided along the inner circumference of the reactor pressure vessel 1, and cooling water is supplied from this water supply nozzle 9. The supplied cooling water and the steam-separated cooling water are discharged to the lower part of the reactor core by the jet pump 4.

3 to 5 show the jet pump and its holding part.

The jet pump 4 has a riser pipe 1 as a cooling water supply pipe.
It is configured to be attached to the top of 2. The jet pump 4 has a bifurcated inverted U-shaped elbow 13, and a mixing nozzle 10 is attached to the end of the elbow 13. The nozzle opening of the mixing nozzle 10 is the inlet mixer 11
The inlet mixer 11a extends downward and is connected to a diffuser 11b. The cooling water supply pipe 12 is fixed to the reactor pressure vessel 1 via a bracket 14a, and the inlet mixer 11a is held and positioned by a bracket 14b fixed to the cooling water supply pipe 12. Therefore, when the cooling water that flows into the cooling water supply pipe 12 and rises changes its flow downward via the elbow 13 and is blown out from the mixing nozzle 10, the upward flow flows into the elbow 13 and the mixing nozzle 10 as the pump body. Since fluid force acts, the upper part of the elbow 13 is held down by a holding beam 15 attached to the cooling water supply pipe 12. In detail, the cooling water supply pipe 12 and the elbow 1
A pair of opposing ears 17 are erected on both sides of each elbow 13 from the connecting portion 16 with the elbow 3. A horizontal groove 18 is provided on the opposing surface of each ear portion 17, and both ends of the holding arm 15, which is made of a relatively thick leaf spring, are placed horizontally and above the elbow 13 in the matching groove 18. It is fitted and supported in a detachable manner. A push-down bolt 19 is screwed into the center of the holding beam 15 from above, and the lower end of this push-down bolt 19 is brought into pressure contact with the upper surface of the elbow 13.

As a result, an initial load due to the push-down force of the elbow 13 is applied to the holding beam 15 via the push-down bolt 19.
The jet pump 4 is held down. Note that hook protrusions 15a for hooking the holding force adjustment device are integrally provided on both sides of the holding beam 15 in a protruding manner.

Next, the holding force adjusting device will be explained with reference to FIGS. 1, 6, and 7.

A highly rigid pole 21 is suspended from a service platform 20 installed at the top of the reactor pressure vessel 1 to the downcomer section. This pole 21 has a structure in which a plurality of ball bodies are connected to each other in order to facilitate handling.

A vertical rod 23 for rotating the push-down bolt 19 is screwed to the lowermost end of the ball 21. This vertical rod 23 has a cylindrical shape, and the lower end side has a large diameter via a stepped portion. The lower end of this vertical rod 23 is formed with an engaging portion, for example, a hexagonal hole 24, which fits into the top of the push-down bolt 19.

Then, the operating handle 25 of the ball 21 placed on the furnace
The vertical rod 23 can be raised and lowered and rotated about its axis through the vertical rod 23.

A mechanism for applying or releasing an initial load to the holding beam 15 is provided on the outer periphery of the vertical rod 23. This mechanism consists of an elevating frame 26 in the shape of a vertically thin box that is fitted onto a vertical rod 23 so that it can be moved up and down and rotated relative to it, and support legs 27 that are attached to this elevating frame 26. It is composed of an arm 28 and an auxiliary arm 29.

That is, a piston 30 is fixed to the vertical rod 23, and the elevating frame 26 has a cylinder 31 fixed therein in sliding contact with the piston 30, and a housing 32 provided at the lower end of the vertical rod 23 is in sliding contact with the lower end of the vertical rod 23. It is attached to the vertical rod 23.

Water pressure introducing portions 33a are provided at the upper and lower portions of the cylinder 31.

33b is provided, and by applying water pressure to the upper and lower surfaces of the piston 30, the elevating frame 26 is moved up and down relative to the vertical rod 23. Water pressure introduction part 33
Pressurized water is supplied to a and 33b via a hose 35 hanging from an operation box 34 on the service platform 20, thereby positioning the elevating frame 26 up and down. A pair of insertion guides 26 are provided at the lower end of the elevating frame 26 so as to integrally project from the housing 32 for horizontally positioning the elevating frame 26 by slidingly contacting both sides of the holding beam 15. The mutually opposing portions of the lower end portions of each insertion guide 36 are formed into a tapered shape that gradually expands downward, so that positioning by fitting into the holding beam 15 can be easily performed.

Further, the support leg 27 and the arm 28 elastically deform, that is, curve, the holding beam 15 in a convex shape upward, and the push-down bolt 1
9 is provided to separate it from the elbow 13. That is, the pistons 38 are housed in a pair of vertically extending hydraulic cylinders 37 provided inside the housing 32, and the downward rods of the pistons 38 protrude downward from the lifting frame 26 to serve as the support legs 27. Each support 1I
The opposite lil corners of 127 are made wider than the width of the holding beam 15 so that each support leg 27 straddles the holding beam 15. Then, when pressurized water is introduced into the hydraulic cylinder 37 while the lifting frame 26 is lowered to the vicinity of the holding beam 15, the piston 38 is lowered and the support leg 27 is moved to the elbow 13.
The lift frame 26 is pushed down by pressing against the upper surface of the lift frame 26. Note that pressurized water to the hydraulic cylinder 37 is supplied via another hose hanging from the operation box 34 on the service platform 20, similar to the lifting cylinder 31 of the lifting frame 26 itself.

On the other hand, the arms 28 are hook-shaped, and are pivotally supported at intervals on a pair of horizontal bins 39 inserted into a housing 32 at the lower end of the elevating frame 26. A rotating link 40 is connected to each arm 28, and this link 40 is connected to a piston rod 42 of a hydraulic cylinder 41 provided at the lower end of the elevating frame 26. The spacing between the arms 28 corresponds to the hooking protrusions 15a on both sides of the holding beam 15,
The tip hook portion 28a of each arm 28 is the hook portion protrusion 15a.
It is designed to be locked to the lower part from the side.

Therefore, with the lifting frame 26 lowered to near the holding beam 15, each arm 28 is rotated, and with its distal end hook portion 28a hooked to the hook protrusion 15a of the holding beam 15, the support leg 27 is When pressed against the upper surface of the elbow 13, a large upward force is generated on the lifting frame 26 based on the elbow 13, and a lifting force is applied to the middle part of the holding beam 15 via the arm 28, thereby lifting the holding beam 15. The push-down bolt 19 is bent convexly into the elbow 13.
can be separated from the top surface of the

Further, a pair of auxiliary arms 29 are provided on the upper side of the elevating frame 26 on the left and right sides so as to be movable forward and backward. Each of the auxiliary arms 29 has one end pivotally connected to the bin 43, and the other end can be rotated to extend outward from one side of the elevating frame 26 at any time. The amount of advance is linked to the auxiliary arm 29 4
This is done by a piston rod 46 of a hydraulic cylinder 45 connected via 4. Note that the auxiliary arm 29 is always urged by a spring, for example, a tension fill spring 47, in the direction of retracting into one side of the elevating frame 26.

When the elevating frame 26 is suspended with one side facing the surface of the shroud 2, if the left and right auxiliary arms 29 are made to protrude, their tips will come into contact with the shroud 2. Therefore, by adjusting the amount of protrusion of each auxiliary arm 29, the angle at which one side of the elevating frame 26 faces the surface of the shroud 2, that is, the rotational position of the elevating frame 26 around its axis can be adjusted.
can be done. Thereby, the direction of the arm 28 at the lower end of the lifting frame 26 can be adjusted, and the hook portion 28 at the tip of the arm 28 can be adjusted in a direction in which the hook portion 28 is reliably engaged with the hooking protrusion 15a of the holding beam 15. In addition, arm 28
and a hydraulic cylinder 41.4 actuating the auxiliary arm 29.
5 also the operation box 3 on the service platform 20
4 via a hose to supply pressurized water.

Next, the effect of adjusting the holding force of the jet pump, especially the effect when replacing the holding beam 15, will be explained.

First, from above the service platform 20,
3 and the elevating frame 26 are suspended via the ball 21. In this case, the ball 21 may be extended downward by sequentially joining together a plurality of ball bodies. The hanging position is determined so that the axis of the vertical rod 23 coincides with the axis of the push-down bolt 19 of the holding beam 15 to be replaced.

Alignment is performed while visually checking with a television camera, etc. suspended in the furnace. At this time, in order to make it easier to see the lower end of the vertical Orad 23, the elevating frame 26
The vertical rod 2 is raised by introducing pressurized water to the 3a side.
It is desirable to leave the lower end of 3 exposed.

Then, the hexagonal hole 24 at the lower end of the suspended vertical rod 23 is fitted into the head of the push-down bolt 19 to prepare for screw-driving. - After confirming that the vertical rod 23 is fitted to the push-down bolt 19, pressurized water is introduced to the water pressure introduction part 33b side at the bottom of the cylinder 31 to pressurize the piston 30 from below, thereby lowering the elevating frame 26. . Lifting frame 2
6 is positioned at a predetermined position by contacting and guiding the tapered portion of the lower end of the insertion guide 36 protruding from the lower end with the outer side of the holding beam 15. Therefore, the arm 28 is rotated downward and the hook portion 28a is attached to the hook portion 15 of the holding beam 15.
Lock in a. In this case, in order to align the direction of the arm 28 with the locking direction to the hooking projection 15a, the auxiliary arm 29
operate. That is, by individually adjusting the amount by which the left and right auxiliary arms 29 extend from one side of the elevating frame 26,
Due to the contact of the auxiliary arm 29 with the shroud 2, the vertical rod 23 of the elevating frame 26 is rotated around the axis.
ll can be adjusted. For example, if one of the auxiliary arms 29 protrudes more than the other, the more protruded side becomes the rotation position away from the shroud 2.

Then, after making the necessary rotational position adjustment and locking the arm 28 to the hook protrusion 15a of the holding beam 15, pressurized water is introduced into the hydraulic cylinder 37 to cause the support leg 27 to protrude downward, and the elbow 13 It is pressed against the upper surface with a force greater than the initial load of the holding beam 15. As a result, the elevating frame 26
is raised, and the hooking protrusion 15a portion of the holding beam 15, that is, the central portion 15, is elastically curved upward in a convex shape through the hook portion 28a of the arm 28, and the lower end of the push-down bolt 19 is brought into contact with the upper surface of the elbow 13. distance from. Therefore, press down bolt 1
9 is released from the push-down load and can be easily rotated, so rotate the operation handle 25 at the upper end of the ball 21 on the service platform 20 to loosen the push-down bolt 19 and widen the gap with the elbow 13. .

After that, if the support leg 27 is raised via the hydraulic cylinder 37 and the holding beam 15 is returned to its flat shape, the holding beam 15 becomes loosely fitted in the groove 18 that supported it, and can be easily replaced. .

In addition, when applying an initial load to a replaced holding beam or adjusting the holding force of an existing holding beam,
Using the same procedure as above, curve the central part of the holding beam 15 upward in a convex shape, and in this state rotate the vertical rod 23 to tighten or loosen the push-down poles 1-19 to close the gap with the elbow 13. A predetermined holding force may be set by adjustment.

According to the above embodiment, the vertical rod 23 is suspended from the ball 21, and the lifting frame 2 is attached to the vertical rod 23.
6, a support leg 27 attached to the elevating frame 26, an arm 28, an auxiliary arm 29, and the like can lift and release the holding beam 15 and rotate the push-down bolt 19 using a single device. Unlike conventional methods that require multiple devices, this method does not become complicated.

In addition, since a single device has multiple functions as described above, interference with the equipment above the downcomer can be easily avoided when suspending it from the furnace, which does not require special skill. Even beginners can efficiently and reliably adjust the holding force. □ As in the embodiment described above, the elevating frame 26 is attached to the vertical rod 23 so as to be rotatable around its axis, and a pair of left and right auxiliary arms 29 that can move forward and backward are attached to the side surfaces of the elevating frame 26. If the rotational position can be adjusted by protruding and abutting this auxiliary arm 29 against the side wall of the shroud 2, the locking position of the hook portion 28 of the arm 28 for curving the holding beam 15 can be reliably set. The locking position can be determined extremely easily without causing problems such as twisting when the lifting frame 26 is suspended.

(Effects of the Invention) As described above, the present invention includes a vertical rod for rotating a push-down bolt for setting an initial load screwed into a holding beam, and a vertical rod that bends the holding beam in advance when rotating the push-down bolt. A lift frame with an arm and support legs for allowing rotation of the push-down bolt are integrated in a relatively movable state.

Therefore, devices that were previously individually configured and complicated are now compactly integrated and have multiple functions.
Manufacturing, handling, etc. can be simplified. In addition, when suspending a large number of in-furnace equipment to avoid interference, using multiple members previously required a high level of skill, but by integrating the equipment, interference can be easily avoided, making it easy even for beginners. It can be done reliably and efficiently. Therefore, the labor of the worker,
This greatly contributes to reducing radiation exposure, etc., and has great effects in terms of both workability and safety improvements.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic diagram of the entire device showing one embodiment of the present invention, FIG. 2 is a sectional view showing the overall configuration of a nuclear reactor having a jet pump to which the device of the present invention is applied, and FIG. 3 is a front view showing the overall structure of the jet pump, FIG. 4 is a cross-sectional view taken along the line ■-■ in FIG. 3 showing the structure of the holding part of the jet pump in detail, and FIG. FIG. 6 is a sectional view showing the configuration of the main parts of the holding force adjusting device, and FIG. 7 is a sectional view taken along the line -Vl in FIG. 6. 1...Reactor pressure vessel, 2...Shroud, 4...
・Jet pump, 15... Holding beam, 19...
Push-down bolt, 23... Vertical rod, 24... Hexagonal hole (engaging portion), 26... Lifting frame, 27... Support leg, 28... Arm, 29... Auxiliary arm. Applicant's agent Hisashi Hatano Figure 2 Figure 3

Claims (1)

[Claims] 1. A plurality of jet pumps are provided in the downcomer of the reactor pressure vessel, and the tops of the jet pumps are pushed by a horizontal holding beam and a push-down bolt screwed into the beam from above. In a device that is held down and the push-down bolt is adjusted from above the furnace, there is a vertical rod that is suspended from the top of the furnace and has an engagement portion formed at its lower end for operating the push-down bolt, and the outer periphery of this vertical rod. an elevating frame mounted on the side so as to be movable up and down relative to the vertical rod; a support leg that protrudes from the lower end of the elevating frame so that it can move forward and backward and comes into contact with the top of the jet pump; and a support leg that is rotatably mounted on the elevating frame. and an arm for elastic deformation of the holding beam which is removably locked to the lower side of the holding beam. 2. The elevating frame is attached to the vertical rod so as to be rotatable around its axis, and the elevating frame has a pair of auxiliary arms protruding from the side that can move forward and backward, and these auxiliary arms are attached to the side wall of the shroud. 2. The jet pump holding force adjustment device according to claim 1, wherein the rotational position can be adjusted by abutting the device.