JPH07280979A - Control rod supporting structure in nuclear reactor for ship - Google Patents

Abstract

PURPOSE:To prevent a control rod from being removed from a fuel assemble to bring about a critcal state in the reactor core even it a significant vibratiorn takes place when a control rod driver is dismantled and the control rod is separated from a control rod drive shaft at the time of maintenance or inspection of a nuclear reactor for ship. CONSTITUTION:An unlock button 7 is disposed at the lower end of a gripper operating shaft 3, an anti-removal gripper 6 is built in a control rod cluster spider body 5, and a supporting rod 13 having an enlarged part 13a at the upper end thereof is installed on a fuel assembly 8 disposed under the spider body 5 thus constituting the control rod supporting structure. A control rod 11 can be separated from a control rod drive shaft 11 while simultaneously coupling it with the fuel assembly 8 by simply shifting the gripper operating shaft 3 upward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for supporting a control rod of a marine nuclear reactor. In maintenance and inspection of a marine nuclear reactor, a control rod drive device is disassembled to separate the control rod drive shaft from the control rod. Even if a large vibration occurs between them and the ship reactor is turned upside down, it is possible to prevent the control rod from being withdrawn from the fuel assembly and the core from entering a critical state.

[0002]

2. Description of the Related Art As a marine nuclear reactor which is a main engine of a nuclear power ship, application of a pressurized water type light water reactor is considered to be promising from the viewpoint of both the actual use at a power plant and the control of the output of the reactor.

FIG. 5 shows a structure around a control rod of a power generation reactor using a pressurized water reactor, FIG. 5 (a) is a top view of a fuel assembly 25, and FIG. FIG. 3 is a side view of a fuel assembly 25 showing a control rod cluster spider body 23 and a control rod 26 extracted.

In FIGS. 5 (a) and 5 (b), a large number of control rod driving devices (not shown) are installed on a reactor vessel lid (not shown), and lower parts of these control rod driving devices are installed. A tubular control rod drive shaft 20 is connected to each.

A control rod cluster spider body 23 is connected to the lower portion of each control rod drive shaft 20,
One control rod cluster spider body 23 is the support member 2
Twelve control rods 26 are supported via 8 and end plugs 29. Since the control rod drive shaft 20 is moved up and down according to the operating conditions of the reactor, the 12 control rods 26 supported by each control rod cluster spider body 23 are also moved up and down to control the reactivity of the reactor. The black circles in FIG. 5A indicate fuel rods.

FIG. 6 is an explanatory view showing in detail the control rod support structure of a nuclear reactor for power generation using a pressurized water type light water reactor.

As shown in the figure, in the conventional control rod support structure, the control rod drive shaft 20 which is moved up and down according to the operating condition of the reactor is connected to the upper end portion 22a, and gradually contracts toward the lower end portion. Diameter outward and flange 22 on the lower end
b has a hollow cylindrical shape having b, and the diameter of the outward flange 22b at the time of connecting the control rod drive shaft 20 and the control rod 26 at the time of operating a nuclear reactor, etc. The gripper 2 in which the shaft 21 descends and is fixed to the lower end of the gripper operating shaft 21 and a lock button 24 having a shape that tapers down toward the bottom is inserted and enlarged.
2, and the gripper 22 is inserted from the upper opening 23a,
It has an enlarged diameter portion 23b into which the outward flange 22b whose diameter has been enlarged by inserting the lock button 24 is fitted and has an inner surface shape into which the gripper 22 is fitted, with a support member 28 and an end plug 29 provided on the outer surface. Hollow cylindrical control rod cluster spider body 23 supporting the control rod 26
And a shock absorbing spring 27 that is fixed to the bottom of the control rod cluster spider body 23 and is a shock absorber that absorbs the collision of the control rod cluster spider body 23 that drops toward the fuel assembly 25 during an emergency stop of the reactor. Composed of and. Reference numeral 30 in the drawing denotes a control rod guide thimble for guiding the control rod 26.

When the reactor is in operation, the gripper 22
After being inserted into the control rod cluster spider body 23, the gripper operating shaft 21 is lowered with respect to the gripper 22 and the lock button 24 is inserted into the lower end of the gripper 22 so that the gripper operating shaft 21 is divided into a plurality of parts in the circumferential direction and is elastic. Outer flange 2 that can be expanded and contracted by having
2b is pushed out and fitted into the expanded diameter portion 23b provided in the groove shape on the inner surface of the control rod cluster spider body 23, so that the control rod cluster spider body 23
The control rod drive shaft 20 and the control rod 26 are connected.

On the other hand, in maintenance and inspection of the nuclear reactor, fuel exchange, etc., first, the control rod drive device (not shown) located above the control rod drive shaft 20 is disconnected, and then the control rod drive shaft 20 and the control rod are removed. Separate from 26. Control rod drive shaft 2
0 and the control rod 26 are separated by raising the gripper operating shaft 21 and pulling it out from the gripper 22, and then pressing the lock button 2
When 4 moves upward from the inside of the lower end of the gripper 22, the outward flange 22b, which has a spring action and can be freely reduced in diameter, is reduced in diameter so that the enlarged diameter portion 23b of the control rod cluster spider body 23.
It is carried out by disengaging from the control rod cluster spider body 23 and gathering on the center side.

In order to quickly shut down the reactor, the control rod drive shaft 20 is disconnected at the upper part, and the control rod drive shaft 20, gripper operating shaft 21, gripper 22, control rod cluster spider body 23, lock button 24 and By dropping the shock absorbing spring 27 in the coupled state, the control rod 2
6 is inserted into the fuel assembly 25. At this time, the shock absorbing spring 27 installed at the bottom of the control rod cluster spider body 23 alleviates the collision of the control rod cluster spider body 23 with the fuel assembly 25.

[0011]

As described above, in the conventional pressurized water type light water reactor, when the control rod drive shaft and the control rod are separated during the internal inspection or the like, the control rod remains inserted in the fuel assembly. It was held in a state.

However, since there is no means for fixing and restraining the control rods, when the pressurized water type light water reactor is applied to a marine reactor, the control rod drive shaft and the control rods are separated and the fuel assembly is removed from the reactor. If the reactor is turned upside down due to a tsunami, etc. that abruptly moves up and down or overturns before taking out, the control rods may come out of the fuel assembly and the reactor core may enter a critical state. There is.

In particular, nuclear ships to be constructed in the future are required to comply with the International Maritime Organization (IMO) nuclear ship safety standards. However, these nuclear ship safety standards require the use of marine reactors from the viewpoint of improving safety. Maintenance and refueling are also positioned as a part of the normal operation state of nuclear ships, and maintenance is required because it is required to prevent the core from going into a critical state during such maintenance and refueling. We have urgently established a technology that can prevent the reactor core from going into a critical state even if the reactor is turned upside down due to a ship accident or the like when the control rod drive shaft is disconnected from the control rod during fuel refueling, etc. Need to be kept.

The present invention has been made in view of the above problems of the prior art, and the hull is large while the control rod drive shaft and the control rod are separated during maintenance and inspection of a marine nuclear reactor. An object of the present invention is to provide a control rod support structure for a marine reactor, which can prevent the control rod from being withdrawn from the fuel assembly and being brought into a critical state even when it is vertically moved or overturned.

[0015]

In order to solve the above-mentioned problems, the inventor of the present invention controls the gripper operating shaft for separating the control rod drive shaft and the control rod, which has been conventionally performed, by controlling the gripper operating shaft. It was thought that it would be good if the rods could be fixed to the fuel assembly at the same time, and the present invention was completed by earnestly studying such a control rod support structure for a marine nuclear reactor.

A control rod support structure for a marine nuclear reactor according to the present invention comprises a lower portion of a control rod drive shaft connected to an upper control rod drive device and a control rod supported below the control rod drive shaft. Is provided between the upper part of the fuel assembly and the upper part of the fuel assembly located below the connection release mechanism B. Below the connection release mechanism B and above the impact absorption mechanism A, the release connection between the control rod and the impact absorption mechanism A is interlocked with the connection release between the control rod and the connection release mechanism B. When the control rod is disconnected from the control rod drive shaft, the shock absorbing mechanism A
A release coupling mechanism C that can be fixed to the above is provided (hereinafter, also referred to as "invention structure 1").

More specifically, in the control rod support structure for a marine nuclear reactor according to the present invention, a control rod drive shaft that is moved up and down in accordance with the operating condition of the reactor is connected to the upper end portion, and goes toward the lower end portion. It has a hollow columnar shape that gradually decreases in diameter and has a lower end portion that is divided into a plurality of pieces in the circumferential direction and that has an outward flange that is elastic in the radial direction and that can be freely reduced in diameter and expanded. The diameter of the outward flange is such that a gripper operating shaft that is vertically inserted inside is lowered, and a lock button that is fixed to the gripper operating shaft and that is tapered downward is inserted into the inside. And a gripper that is enlarged due to the gripper operating shaft being raised so that the lock button is not inserted inside, and the gripper is inserted through an upper opening, and the lock button is inserted. A hollow columnar shape having an enlarged diameter portion to which the outward flange of the gripper having a larger diameter is fitted and having an inner surface shape to be fitted with the gripper, and supporting the control rod via a supporting member provided on the outer surface Control rod cluster spider body, and a shock absorber that is installed in the fuel assembly below the control rod cluster spider body and receives the control rod cluster spider body that falls during an emergency shutdown of the reactor. A control rod support structure for a marine nuclear reactor, further comprising: (i) the gripper operating shaft extending downward through the lock button and tapering downward at a lower end thereof. A lock release button with a shape that reduces the diameter is fixed, (i
i) The shock absorber is fixed to the fuel assembly below the control rod cluster spider body, extends to the inside of the control rod cluster spider body, and has an enlarged diameter portion at or near the upper end portion. A support rod, and (iii) an inner surface of the control rod cluster spider body, the lower end of which is a circle between the enlarged diameter portion of the control rod cluster spider body and the enlarged diameter portion of the support rod. The support bar is divided into a plurality of parts in the circumferential direction and has elasticity and can be freely contracted and expanded, and the gripper operating shaft is lowered and the lock release button is inserted to expand the lower end portion of the support bar. Not gripping the expanded diameter part of the support rod, and the lock release button is not inserted due to the gripper operating shaft being raised so that the lower end of the gripping part contracts and the expanded diameter part of the support rod is gripped. What Tsu path is characterized in that it is arranged (hereinafter, also referred to as "the present invention Structure 2".).

That is, the impact absorbing mechanism A in the present invention structure 1 is constituted by the impact absorbing body in the present invention structure 2, and the connection releasing mechanism B in the present invention structure 1 is the gripper and control rod cluster spider in the present invention structure 2. In the present invention structure 2, the release coupling mechanism in the present invention structure 1 is composed of the pull-out preventing gripper, the control rod cluster spider body, and the unlock button.

[0019]

In the structure 1 of the present invention, the shock absorbing mechanism for absorbing the shock of the control rod that falls at the time of emergency stop is fixed to the upper portion of the fuel assembly, and the control rod drive shaft and control located above the fuel assembly. A connection release mechanism is provided between the control rod and the shock absorption mechanism, below the connection release mechanism and above the impact absorption mechanism in conjunction with the connection release between the control rod and the connection release mechanism. A release coupling mechanism is provided that can secure the control rod that is coupled and disconnected from the control rod drive shaft to the shock absorbing mechanism.

Therefore, when the control rod drive shaft and the control rod are connected as in the normal operation of the reactor, the control rod and the shock absorbing mechanism are opened without being connected, while the maintenance and inspection of the reactor and the fuel are not performed. When disconnecting the control rod drive shaft and the control rod for replacement or the like, the control rod and the shock absorbing mechanism are connected. Therefore, even if the control rod and the control rod drive shaft are disconnected during maintenance and inspection of the nuclear reactor, fuel exchange, etc., the control rod is connected to the fuel assembly via the shock absorbing mechanism.

In the structure 2 of the present invention, the gripper is fixed to the gripper operating shaft by inserting the gripper into the control rod cluster spider body and fitting the gripper at a predetermined position and then inserting the gripper operating shaft downward with respect to the gripper. The lock button pushes the outward flange at the lower end of the gripper and expands it to fit the enlarged outward flange into the groove-shaped enlarged portion provided inside the control rod cluster spider body. A lock release button fixed to the lower end pushes the lower end of the pull-out prevention gripper installed inside the control rod cluster spider body to expand it, and the upper end of the support rod fixed to the fuel assembly below the control rod cluster spider body. It becomes impossible to grip the enlarged diameter part of the part with the pull-out prevention gripper.

On the other hand, when the gripper operating shaft is moved upward with respect to the gripper in order to pull out the gripper from the control rod cluster spider body, the lock button also rises and the diameter-reducing outward flange is reduced in diameter and outward. As the flange is disengaged from the expanded diameter portion of the control rod cluster spider body, the lock release button also rises and the lower end of the pull-out prevention gripper is reduced in diameter to grip the expanded diameter portion of the support rod.

Therefore, in order to connect the control rod drive shaft and the control rod, the gripper is inserted into a predetermined position of the control rod cluster spider body, and then the gripper operating shaft is inserted below the gripper. The gripper and control rod cluster spider body are connected by the outward flange at the lower end of the control rod cluster spider body and the control rod cluster spider body is expanded by expanding the lower end of the pullout prevention gripper. Is no longer connected to the support rod.

Next, when disconnecting the control rod drive unit from the control rod for maintenance and inspection of the nuclear reactor, the gripper operation shaft is pulled out upward with respect to the gripper, and the lower end portion of the gripper is pulled out. The outer flange and the expanded part of the control rod cluster spider body are disengaged to separate the gripper from the control rod cluster spider body, and the lower end of the pullout prevention gripper is reduced in diameter to reduce the control rod cluster spider. The body and the support rod are connected.

Therefore, when the control rod drive unit and the control rod are separated from each other, the gripper operating shaft is pulled out to separate the gripper from the control rod cluster spider body, and the control rod cluster spider body and the control unit. Connections with the rods are made simultaneously so that the control rod drive and control rods are disconnected and the control rods and fuel assemblies are connected at the same time.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a control rod support structure for a marine nuclear reactor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view showing a control rod support structure of a marine nuclear reactor using a pressurized water type light water reactor to which the present invention is applied, with a part thereof omitted, and FIG. FIG. 2B is a perspective view of the pullout prevention gripper 6.

In the present embodiment, a large number of control rod drive devices (not shown) are installed on the reactor vessel lid (not shown), and tubular control rod drive shafts 1 are connected to these control rod drive devices, respectively. It Control rod cluster spider bodies 5 are respectively connected to the lower portions of the control rod drive shafts 1. Although not shown in FIG. It supports the control rod 11 of the book. Further, in FIG. 1, since each control rod drive shaft 1 is moved up and down according to the operating condition of the reactor, 12 control rods 11 supported by each control rod cluster spider body 5 are also moved up and down. Is controlled.

To the lower end of the control rod drive shaft 1 is connected a gripper 2 which is an example of a component of a mechanism for releasing the connection between the control rod drive shaft 1 and the control rod 11. The gripper 2 is shown in FIG.
As shown in (a), the inner diameter and the outer shape are gradually reduced toward the lower end, and the lower end is divided into a plurality of slits 2b provided in the circumferential direction and is divided. Each of the divided portions 2c is a hollow columnar member having a spring action of deforming in the radial direction due to its elasticity and having an outwardly facing flange 2a capable of contracting and expanding in diameter as a whole.

Inside the gripper 2, there is provided a lock release button 7 having a shape in which the diameter is tapered downward at the lower end,
A gripper operating shaft 3 is fixedly installed above the lock button 4 having a shape that is tapered by a certain distance and is tapered downward. The gripper operating shaft 3 is extended to the upper side, and is configured so that it can be raised and lowered from the outside.

The diameter of the outward flange 2a of the gripper 2 is
When the gripper operating shaft 3 that is vertically inserted inside the gripper 2 descends, the lock button 4 fixed to the gripper operating shaft 3 is inserted inside and enlarged, and the gripper operating shaft 3 rises. As a result, the lock button 4 is not inserted inside, and the lock button 4 is contracted by its own spring action.

The gripper 2 is provided inside the control rod cluster spider body 5 so as to be freely fitted therein. This control rod cluster spider body 5 has a groove shape in which the gripper 2 is inserted from the upper end opening 5a of the control rod cluster spider body 5 and the outward flange 2a of the gripper 2 whose diameter is expanded by inserting the lock button 4 is fitted. Is a hollow columnar member having an inner surface shape that fits with the gripper 2 while having the expanded diameter portion 5b. Below the enlarged diameter portion 5b, there is provided an enlarged diameter portion 5d for holding and housing a pull-out prevention gripper 6 which will be described later. In this embodiment, the connection releasing mechanism is composed of the gripper 2, the control rod cluster spider body 5, and the lock button 4.

Below the control rod cluster spider body 5, there is installed a shock absorber 10 for receiving the control rod cluster spider body 5 that falls when the reactor is urgently stopped. The shock absorber 10 includes a spring 10b provided on the upper surface of the fuel assembly 8 and a disc 1 supported by the spring 10b.
0a, and the disk 10a is arranged so as to be able to support the lower surface of the flange 5c provided inside the control rod classiter spider body 5, the control rod supporting structure for a marine nuclear reactor according to the present invention. Then, as another element, below the control rod cluster spider body 5, it is fixed to the fuel assembly 8 by the fixing pin 9 and is extended to the inside of the control rod cluster spider body 5, and the diameter is expanded at the upper end. A support rod 13 having a portion 13a is provided. The expanded diameter portion 13a is gripped by the pull-out prevention gripper 6 by reducing the diameter of the lower end portion of the pull-out prevention gripper 6 which will be described later, and the lower end portion 6a which is the grip portion of the pull-out prevention gripper 6 expands in diameter. As a result, the pull-out prevention gripper 6 is not gripped by the gripper 6 and is appropriately determined according to the shape of the inner surface of the grip portion 6a of the pull-out prevention gripper. As described above, in this embodiment, the shock absorbing mechanism includes the shock absorbing body 1 including the support rod 13, the disc 10a, the spring 10b, and the pin 9.
It is composed of 0.

On the inner surface of the control rod cluster spider body 5, the expanded diameter portion 5b of the control rod cluster spider body 5
2B, the lower end portion 6a is circumferentially divided into a plurality of portions by a plurality of slits 6b, and the divided portion 6c is divided into a plurality of portions. Since each of them has elasticity, it is deformed in the radial direction and a hollow cylindrical pull-out prevention gripper 6 that can be reduced in diameter and expanded in diameter is installed. The pull-out preventing gripper 6 is installed inside the control rod cluster spider body 5 by pushing it from the upper end opening 5a and fitting it into the lower portion of the expanded diameter portion 5b.

The pull-out prevention gripper 6 can hold the expanded diameter portion 13a of the support rod 13 because the lock release button 7 is inserted inside and the lower end portion 6a is expanded when the gripper operating shaft 3 is lowered. When the gripper operating shaft 3 is lifted, the lock release button 7 is not inserted and the lower end portion of the gripper operating shaft 3 is reduced in diameter by its own elastic action, so that the enlarged diameter portion 13a of the support rod 13 is grasped. .
In this embodiment, the release coupling mechanism is the pull-out prevention gripper 6
And a control rod cluster spider body 5 and an unlock button 7.

A support member 14 is connected to the outer surface of the control rod cluster spider body 5, and the control is guided by the control rod guide thimble 12 via the support member 14 and an end plug 15 connected to the support member 14. The rod 11 is supported.

The operation of an embodiment of the control rod support structure for a marine nuclear reactor according to the present invention constructed as above will be described with reference to FIGS. 1 to 4. 3 and 4 show the fuel rod assembly when the control rod 11 and the control rod drive shaft 1 are connected in the embodiment of the control rod support structure for a marine nuclear reactor according to the present invention shown in FIG. 8 and the control rod 11 are respectively connected, and the reference numerals in FIGS. 3 and 4 are the same as those in FIG.

When operating the reactor, in FIG.
The gripper 2 is inserted into the control rod cluster spider body 5, the control rod cluster spider body 5 and the gripper 2 are fitted together, and then the gripper operating shaft 3 is inserted into the gripper 2 to lock the lock button 4 of the gripper 2. By inserting the outward flange 2a into the enlarged diameter portion 5b of the control rod cluster spider body 5 by inserting it into the lower end, the control rod drive shaft 1
And the control rod 11 are connected. At this time, interlocking with the insertion of the lock button 4 into the lower end of the gripper 2, by inserting the lock release button 7 into the pull-out prevention gripper 6, the expanded portion 13a of the support rod 13 is elastically exerted by itself. Lower end 6 of the pull-out prevention gripper 6 that holds the
The diameter a is expanded and the support rod 13 and the control rod 11 are separated.

FIG. 3 (a) shows a certain timing when the reactor is in operation, in which the control rod drive shaft 1 is lifted upward by a control rod drive device (not shown), and the control rod 11 is slightly pulled from the fuel assembly 8. Shows the removed state. That is, the control rod drive shaft 1 is connected to the gripper 2, the gripper 2 is fitted to the control rod cluster spider body 5, and the control rod 11 is connected to the control rod cluster spider body 5 via the support member 14 and the end plug 15. Control rod drive shaft 1 and control rod 1
1 is connected.

FIG. 3B is a sectional view of the gripper 2 taken along the line AA in FIG. 3A, and FIG.
3B is a cross-sectional view taken along line BB in FIG. In this state, as shown in FIG. 3 (b), the lower portion of the gripper 2 is expanded in diameter, the outward flange 2a is fitted into the expanded diameter portion 5b on the inner surface of the control rod cluster spider body 5, and at the same time as shown in FIG. ), The lower portion of the pull-out preventing gripper 6 is also expanded in diameter so that the lower end portion 6a does not grip the expanded diameter portion 13a of the support rod 13.

In order to quickly shut down the nuclear reactor,
In the state shown in (a), the control rod drive shaft 1 is separated at the upper part, and the control rod drive shaft 1, gripper 2, gripper operating shaft 3, control rod cluster spider body 5, support member 14,
The end plug 15 and the control rod 15 are dropped downward as they are, but a flange 5c inside the control rod cluster spider body 5 is provided on the upper end of the shock absorber 10 by a spring 10b. It is received by 10a and the shock caused by falling is absorbed.

Next, when the reactor is stopped, the control rod drive shaft 1 descends by the control rod drive device (not shown) and stops at the position shown in FIG. In this state, in order to separate the control rod drive shaft 1 and the control rod 11, the gripper operating shaft 3 is attached to the gripper 2
Pull upwards against. Then, as the lock release button 7 moves upward, the lower end portion 6a of the pull-out prevention gripper 6 is reduced in diameter by its own elastic action and the support rod 13 is pressed.
Of the control rod cluster spider body 5 by reducing the diameter by the elastic action of the outward flange 2a of the gripper 2 by gripping the enlarged diameter portion 13a of the control button 4 and moving the lock button 4 upward. Get out of.

FIG. 4A shows the situation when the control rod drive shaft 1 is further pulled up thereafter. That is,
The gripper 2 is separated from the control rod cluster spider body 5, the control rod cluster spider body 5 holds the support rod 13 by the pull-out prevention gripper 6, and the support rod 13 is supported by the fuel assembly 8 and the control rod cluster spider body. 5 is a control rod 1 via a support member 14 and an end plug 15.
The control rods 11 are connected to the fuel assembly 8 to support 1.

FIG. 4B shows a CC cross section of the gripper 2 in FIG. 4A, and FIG. 4C shows a DD cross section of the pullout prevention gripper 6 in FIG. 4A. .
In this state, the lower portion of the gripper 2 is reduced in diameter as shown in FIG. 4 (b) to engage with the upper surface of the lock release button 7, and the lower portion of the pull-out prevention gripper 6 is also contracted as shown in FIG. 4 (c). The diameter of the lower end 6a is increased so that the expanded diameter portion 13 of the support rod 13
You will be able to grab a.

As described above, in the control rod supporting structure for a marine nuclear reactor according to the present invention, the control rod drive shaft 1 and the control rod 11 are separated by one operation of pulling up the gripper operating shaft 2 and It has become possible to connect the control rod 11 and the fuel assembly 8 at the same time. Therefore, even when the control rod drive device is disassembled during maintenance / inspection of the marine reactor, the control rod 11 is not left in a state of being separated from other members, and a large vibration occurs in the hull. It has become possible to prevent the control rod from being pulled out of the fuel assembly and the core from entering a critical state even when the ship reactor is turned upside down.

[0046]

[Modification] In this embodiment, the gripper 2 and the like are used as the connection and release mechanism, and the extraction gripper 6 and the like are used as the release and connection mechanism, and these are interlocked by the lock button 4 and the lock release button 7 fixed to the gripper operating shaft 3. However, the control rod support structure for a marine nuclear reactor according to the present invention is not limited to this mode. Control of a marine reactor equipped with a coupling / releasing mechanism for coupling / releasing a control rod and a control rod drive shaft, and a release coupling mechanism for coupling / releasing the control rod and an impact absorbing mechanism fixed to a fuel assembly Rod support structures are equally included in the present invention.

[0047]

According to the structure 1 of the present invention, the shock absorbing mechanism for absorbing the shock of the control rod which falls at the time of emergency stop is fixed to the upper portion of the fuel assembly, and the control rod drive shaft located above the fuel assembly. A connection release mechanism is provided between the control rod and the control rod, and below the connection release mechanism and above the impact absorption mechanism, the control rod and the impact absorption mechanism are interlocked with the connection release between the control rod and the connection release mechanism. The control rod drive shaft is disconnected from the control rod drive shaft, and the control rod drive shaft is disconnected from the control rod, and the control rod drive shaft is disconnected from the control rod drive shaft. You can connect at the same time.

In the structure 2 of the present invention, the lock release button is installed at the lower end of the gripper operating shaft, the pull-out preventing gripper is built in the control rod cluster spider body, and further the fuel assembly located below the control rod cluster spider body is installed. Since the support rod having the enlarged diameter portion is installed at the upper end, the control rod drive shaft and the control rod are separated by one operation of moving the gripper operation shaft upward,
Also, the control rod and the fuel assembly can be connected at the same time.

Therefore, according to the structure 1 of the present invention or the structure 2 of the present invention, even when the control rod drive device is disassembled in the maintenance and inspection of the marine nuclear reactor, the control rod is separated from other members. It is possible to prevent the control rod from being withdrawn from the fuel assembly and the core from entering a critical state even if large vibrations occur in the hull.
Therefore, it was possible to secure the application of IMO to the safety standard for nuclear ships.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a control rod support structure for a marine nuclear reactor according to the present invention.

2A is a perspective view of the gripper, and FIG.
(B) is a perspective view of a pull-out prevention gripper.

FIG. 3 (a) is a vertical cross-sectional view showing the connection of the control rod drive shaft and the control rod to one embodiment of the control rod support structure for a marine nuclear reactor according to the present invention, and FIG. ) Is Figure 3
FIG. 3A is a sectional view taken along line AA in FIG.
It is a BB sectional view in (a).

FIG. 4 (a) is a vertical cross-sectional view showing the connection between the support rod and the control rod in one embodiment of the control rod support structure for a marine nuclear reactor according to the present invention, and FIG. It is CC sectional drawing in FIG.4 (a), and FIG.4 (c) is DD sectional drawing in FIG.4 (a).

FIG. 5 shows a structure around a control rod of a conventional power generation reactor using a pressurized water reactor, FIG. 5 (a) is a top view of a fuel assembly, and FIG. 5 (b) is a control rod. It is a side view of the fuel assembly which shows the cluster spider body and the control rod in an extracted manner.

FIG. 6 is a vertical cross-sectional view showing in detail a control rod support structure of a conventional nuclear reactor for power generation using a pressurized water reactor.

[Explanation of symbols]

 A shock absorbing mechanism B coupling release mechanism C release coupling mechanism 1 control rod drive shaft 2 gripper 2a outward flange 2b slit 2c split portion 3 gripper operating shaft 4 lock button 5 control rod cluster spider body 5a upper end opening 5b, 5d diameter expansion Part 5c Flange 6 Pull-out prevention gripper 6a Lower end (grasping part) 6b Slit 6c Divided part 7 Lock release button 8 Fuel assembly 9 Fixing pin 10 Impact absorber 10a Disc 10b Spring 11 Control rod 12 Control rod guide thimble 13 Support Rod 13a Expanded part 14 Support member 15 End plug

Claims (2)

[Claims] 1. A connection release mechanism is provided between a lower portion of a control rod drive shaft connected to an upper control rod drive device and an upper portion of a control rod supported below the control rod drive shaft. A shock absorbing mechanism for absorbing a shock of a control rod that falls during an emergency stop is provided above the fuel assembly located below the connection releasing mechanism, and further below the connection releasing mechanism and above the impact absorbing mechanism. In addition, the control rod disconnected from the control rod drive shaft is connected to the shock absorbing mechanism by releasing and connecting the control rod and the shock absorbing mechanism in conjunction with the connection release of the control rod and the connection releasing mechanism. A control rod support structure for a marine nuclear reactor, comprising a release coupling mechanism that can be fixed. 2. A control rod drive shaft, which is moved up and down according to the operating conditions of a nuclear reactor, is connected to an upper end portion, gradually decreases in diameter toward the lower end portion, and is divided into a plurality of circumferential portions in the lower end portion. In addition, it has a hollow cylindrical shape having an outward flange that is elastic in the radial direction and that can be reduced in diameter and expanded in diameter, and the diameter of the outward flange is a gripper operation that is vertically inserted inside. The lock button, which is fixed to the gripper operation shaft and is tapered downwardly, is expanded by inserting the lock button into the inside of the gripper operation shaft, and the gripper operation shaft is moved upward to increase the lock button. A gripper that is reduced by not inserting it inside, and a diameter expansion part into which the outward flange of the gripper that has been diameter-increased by the insertion of the lock button is inserted. And a hollow cylindrical control rod cluster spider body that has an inner surface shape that fits with the gripper and supports the control rod via a support member provided on the outer surface, and a fuel below the control rod cluster spider body. A control rod support structure for a marine nuclear reactor, comprising: a shock absorber installed in an assembly and configured to receive the control rod cluster spider body falling during an emergency shutdown of the reactor, further comprising (i) The gripper operating shaft extends downward through the lock button, and a lock release button having a shape tapering downward is fixedly provided at a lower end portion thereof, (ii) The shock absorber is fixed to the fuel assembly below the control rod cluster spider body and extends to the inside of the control rod cluster spider body. A support rod having an enlarged diameter portion at or near the upper end, and (iii) an inner surface of the control rod cluster spider body, wherein the enlarged diameter portion of the control rod cluster spider body and the expanded diameter of the support rod The lower end is divided into a plurality of parts in the circumferential direction and has elasticity so that the diameter can be reduced and expanded, and the gripper operating shaft is lowered to insert the lock release button. As a result, the lower end portion expands in diameter and does not grip the enlarged diameter portion of the support rod, and the gripper operating shaft rises to prevent the lock release button from being inserted so that the lower end portion decreases in diameter and the support rod diameter increases. A control rod support structure for a marine nuclear reactor, wherein a pullout prevention gripper for gripping a portion is arranged.