JP2001108782A - Loading method and rotating device for control-rod assembly for nuclear reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the service life of a control-rod assembly for a nuclear reactor by retarding the progress of abrasion of control rods during the operation of the nuclear reactor. SOLUTION: The control-rod assembly 1 for a nuclear reactor comprises a bundled body made by bundling a plurality of long control rods 3 having a neutron-absorbing substance housed therein. The plurality of control rods 3 are disposed so as to display one-quarter rotational symmetry with an axis 9 passing through the center of a cross-section of the bundled body used as the axis 9 of rotation. The assembly 1 is loaded into a core of the nuclear reactor, and after the core is operated for a fixed period of time, the assembly is taken out of the core. The assembly is rotated one-quarter turn centering around the axis 9 of rotation, and then it is again loaded into the core in its one-quarter turn rotated state from the preceding position loaded in the core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of loading a control rod assembly for a nuclear reactor and a rotating device.
TECHNICAL FIELD The present invention relates to a method of loading a control rod assembly for a reactor and a rotating device in which measures are taken against wear during operation of the reactor.

[0002]

2. Description of the Related Art FIG. 4 is a front view showing a configuration example of a control rod assembly for a reactor used in a pressurized water reactor.

FIG. 5 is a front sectional view (a) showing a configuration example of a control rod, and a sectional view (b) along line AA.

FIG. 6 is a perspective view showing a configuration example of a fuel assembly used in a pressurized water reactor.

That is, a pressurized water reactor (hereinafter referred to as “PW
R) (hereinafter referred to as “RCC”) 1 includes a spider 2
A plurality of control rods 3 and a central axis 9 as a rotation axis.
It is configured by being arranged and suspended so as to have / 4 rotational symmetry. For this reason, even when the RCC 1 is rotated by １ ／ (90 ° rotation) about the center axis 9,
The cross-sectional shape is the same.

The control rod 3 has a stainless steel cladding tube 6 whose both ends are sealed with an upper end plug 7 and a lower end plug 8, and a neutron absorbing material 4 pressed by a spring 5 in the cladding tube 6. Is stored.

[0007] By inserting the control rod 3 of the RCC 1 into the control rod guide thimble 11 in the fuel assembly 10 loaded in the nuclear reactor, a negative reactivity is injected into the reactor core. The control rod guide thimble 11 is formed of a hollow tube into which the control rod 3 can be inserted.

On the other hand, the control rod guide thimble 11
The control rod 3 inserted in the control rod guide thimble 11
A positive reactivity is injected into the core by withdrawing it from the core. As described above, in the PWR, the reactivity of the core is controlled by inserting and extracting the RCC1.

The insertion or withdrawal of the RCC 1 is performed by driving a spider 2 by a control rod driving device described later.

[0010]

However, such a conventional RCC1 has the following problems.

FIG. 7 is a schematic diagram showing a state where the control rod is inserted from the control rod drive mechanism into the fuel assembly.

When the control rod 3 is inserted into the control rod guide thimble 11 in the fuel assembly 10 during the operation of the reactor, the control rod 3 vibrates, and comes into contact with the control rod guide thimble 11 at the tip end. Wear may occur.

The cause of this abrasion is RCC1
Rod guide tube (hereinafter referred to as "G / T") 1 serving as a guide for driving the
Coolant 19 flows laterally through gap 17 between upper core plate 5 and upper core plate (hereinafter referred to as “UCP”) 16, and control rod 3 vibrates due to the coolant 19 flowing in the lateral direction. It is conceivable that the vicinity of the tip of the control rod interferes with the inside of the control rod guide thimble 11 to cause friction.

In this case, the control rod 3 located on the side where there is no support pin 18 is compared with the control rod 3 located particularly near the mounting position of the two support pins 18 supporting the G / T 15 and the UCP 16. Wear tends to progress.

This is because the flow of the coolant 19 flowing in the gap 17 between the G / T 15 and the UCP 16 is obstructed by the support pins 18, so that the generation of friction on the side where the support pins 18 are present is small, while the support pins 18 are not provided. Coolant 19 on the side
This is due to the fact that friction is increased because the flow of air is not obstructed.

The control rod 3 located on the side without the support pin 18
It is considered that the abrasion progresses not only to the tip but also to the range of the lower end of the cladding tube 6, and finally, it becomes penetrating wear, which hinders the function as the control rod 3. It has to be replaced, and there is a problem that the life of the RCC1 is shortened.

The present invention has been made in view of such circumstances, and aims to reduce the progress of wear of control rods during operation of a nuclear reactor, thereby extending the life of a control rod assembly for a nuclear reactor. It is an object of the present invention to provide a method of loading a control rod assembly for a nuclear reactor and a rotating device capable of performing the method.

[0018]

Means for Solving the Problems In order to achieve the above object, the present invention takes the following measures.

That is, according to the first aspect of the present invention, an axial axis passing through the center of a binding direction cross section of a binding body formed by binding a plurality of elongated control rods containing a neutron absorbing substance is rotated. As an axis, a control rod assembly for a reactor, in which a plurality of control rods are arranged so as to be 1/4 rotationally symmetric, is loaded on the core of the reactor, and after operating the core for a predetermined period, the core is taken out of the core and rotated. By rotating the core by と し て of rotation about the axis, the core is loaded again with １ ／ of rotation from the state of being loaded on the core.

According to the second aspect of the present invention, an axis in the axial direction passing through the center of the section in the binding direction of the binding body formed by binding a plurality of long control rods containing the neutron absorbing substance is used as the rotation axis. Storage means for storing a control rod assembly for a reactor in which a plurality of control rods are arranged so as to be １ ／ rotationally symmetric, and a control rod assembly for a reactor taken out from a first predetermined storage location and stored To the storage means, housed in the storage means, taken out of the control rod assembly for the reactor housed in the storage means, transferred to a second predetermined storage place, and stored in the second predetermined storage place The take-out and transfer means for storing the control rod assembly for the reactor in the storage means and the take-out and transfer means after storing the control rod assembly for the reactor in the storage means are rotated 1/4 in a predetermined direction about the axis as a rotation axis. After removing the control rod assembly The feed means, as a rotation axis the axis, and a rotating means for quarter turn in the direction of the predetermined direction opposite.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

In the drawings used in the description of the following embodiments, the same parts as those in FIGS. 4 to 7 are denoted by the same reference numerals.

An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view showing an example of the entire configuration of a rotating device for realizing a method of loading a control rod assembly for a nuclear reactor according to an embodiment of the present invention.

That is, the rotating device of the control rod assembly for a nuclear reactor according to the embodiment of the present invention comprises the RCC removal and transfer device 2.
0, an RCC removal and transfer device rotating device 21, and an RCC storage container 22.

The RCC unloading and transferring device 20 lifts the RCC 1 taken out of the core and stored in a predetermined storage location, transfers the RCC 1 to the RCC storage container 22, and transfers the RCC 1 to the RCC storage container 22.
Is suspended in the RCC storage container 22 and stored.

When the RCC 1 is stored in the RCC storage container 22 in this manner, the RCC take-out and transfer device 20 uses the RCC take-out and transfer device rotating device 21 to be described later with the axis in the axial direction passing through the center of the horizontal section as the rotation axis. That is, it is configured to be rotated by 1/4 (90 °) along the direction shown in FIG. Then, after this, the RCC 1 stored in the RCC storage container 22 is lifted again.

In this state, the RCC removal and transfer device 20 is again rotated by the RCC removal and transfer device rotating device 21,
1/4 rotation (90 ° rotation) in the direction opposite to the previously rotated direction, that is, the direction shown in FIG. The RCC unloading transfer device 20 is located on the lower diagonal 2
A projection 30 is provided at a location, and by observing the projection, the rotation state and the rotation direction can be confirmed.

After that, the RCC take-out and transfer device 20
The CC 1 is suspended from the control rod guide thimble 11 of the predetermined fuel assembly 10 so that the control rod 3 is inserted.

Thus, the control rod guide thimble 11
The fuel assembly 10 having the control rod 3 inserted therein is loaded at a predetermined location in the core by a fuel exchange device (not shown).

The RCC take-out and transfer device rotating device 21 is provided with an RC
The C take-out and transfer device 20 is rotated by １ ／ (90 ° rotation) about an axial axis passing through the center of the horizontal section of the RCC take-out and transfer device 20 as a rotation axis. That is, the RCC storage container 22
RCC take-out and transfer device 20 after storing RCC1 in
1/4 turn (90 ° turn) along the direction shown in FIG. Thereafter, the RCC unloading and transferring apparatus 20 having lifted the control rod assembly 1 for the reactor from the RCC storage container 22 is rotated by 1/4 turn in the opposite direction, that is, the direction shown in FIG.
0 °).

The RCC storage container 22 is a long container for storing the RCC 1 and is applicable to an existing spent fuel rack of a PWR plant. Further, the RCC storage container 22 is provided with an RCC rotating jig 23 at the upper part.

The RCC rotating jig 23 is configured to be detachable from the upper part of the RCC storage container 22,
2 and four insertion guides 33 provided so as to surround four sides of the guide opening. The RCC 1 suspended from the RCC removal / transfer device 20 is guided to the guide port 32 by the insertion guide 33, and is appropriately inserted into the RCC storage container 22.

Next, a loading method using the rotating device for a control rod assembly for a nuclear reactor according to the embodiment of the present invention configured as described above will be described.

FIG. 2 is a schematic diagram showing a method of loading a control rod assembly for a nuclear reactor according to an embodiment of the present invention.

First, the RCC 1 is taken out of the reactor core by the existing reactor control rod assembly exchanger after the end of the operation cycle of the reactor, and stored in a predetermined storage location. Here, the RCC 1 taken out of the core is stored in the existing fuel rack 40.

As described above, the RCC 1 stored in the existing fuel rack 40 is lifted by the RCC unloading and transferring device 20 (Step 1) and transferred to the RCC storage container 22 (Step 2).

The RCC 1 is an RCC storage container 22.
Is suspended from above by the RCC removal and transfer device 20 and stored in the RCC storage container 22 (step 3).
At this time, the RCC 1 is guided along the guide port 32 by being hung along the insertion guide 33 provided on the RCC rotating jig 23, and is further smoothly inserted into the RCC storage container 22.

When the RCC 1 is stored in the RCC storage container 22 in this manner, the RCC removal and transfer device 20
The unloading / transporting device rotating device 21 makes a quarter turn (90 ° rotation) along the direction shown in FIG. 2 around the axis in the axial direction passing through the center of the horizontal section (step 4).
The rotation state and the rotation direction are determined by the RCC take-out and transfer device 2.
This is confirmed by observing the zero protrusion 30.

Next, the RCC 1 stored in the RCC storage container 22 is lifted from the RCC storage container 22 by the RCC take-out and transfer device 20 rotated by 1/4 in this way (step 5).

The RCC take-out and transfer device 20 is thus
With the CC1 lifted, the RCC take-out and transfer device rotating device 21 makes a 1/4 turn (90 ° rotation) in the opposite direction to that of step 4, that is, along the direction shown in FIG. 2 (step 6). ). As a result, the RCC take-out and transfer device 20 is returned to the normal state before being rotated in step 4, that is, the non-rotated state. on the other hand,
RCC1 suspended by the RCC removal and transfer device 20
Is held by the RCC take-out and transfer device 20 in a state of being rotated by 1/4 (90 °) along the direction from the state of being loaded on the core in the immediately preceding operation cycle. The rotation state and the rotation direction are also confirmed by observing the protrusion 30 of the RCC removal and transfer device 20.

When the 1/4 rotation along the direction of the RCC take-out and transfer device 20 in step 6 is completed,
The RCC 1 is transferred by the RCC unloading transfer device 20 to a fuel rack 40 in which a predetermined fuel assembly 10 is stored.
Then, the control rod 3 is suspended so as to be inserted (step 7). The RCC 1 has the control rods 3 arranged so as to be １ ／ rotationally symmetric about the axis in the axial direction passing through the center of the horizontal section, and the control rod guide thimble 11 is also arranged in the arrangement of the control rods 3. Since it is provided together, RC
C1 can be inserted into the control rod guide thimble 11 of the fuel assembly 10 even in the state of 1/4 rotation (90 ° rotation).

Thereafter, the fuel assembly 10 in which the control rod 3 has been inserted into the control rod guide thimble 11 is loaded at a predetermined location in the core by a refueling device (not shown), so that the RCC 1 operates immediately before operation. It is loaded in a state where it is rotated by １ ／ rotation (90 ° rotation) from the state of being loaded on the core in the cycle.

Thus, in the immediately preceding operation cycle, the control rod 3, which is located on the side where the support pin 18 is not present and whose abrasion at its tip is promoted, is located on the side where the support pin 18 is present. Moreover, the lateral flow of the coolant 19 is hindered. As a result, wear of the cladding tube 6 is suppressed.

FIG. 3 is a schematic diagram showing the progress of wear of the RCC realized by the method of loading the control rod assembly for a nuclear reactor according to the embodiment of the present invention, where the vertical axis represents the wear depth of the cladding tube. The horizontal axis indicates the stay time of the control rod in the reactor.

The curve A shown in FIG.
8 is a curve showing the progress of abrasion of the cladding tube 6 of the control rod 3 which is disposed on the side where no support member 8 is provided and is disposed on the side where the support pin 18 is provided halfway. On the other hand, a curve B is a curve indicating the amount of progress of wear of the cladding tube 6 of the control rod 3 which is first arranged on the side where the support pin 18 is present and is arranged on the side where the support pin 18 is not provided halfway.

The allowable wear amount F indicates the allowable limit of the wear amount of the cladding tube 6 of the control rod 3. Before the cladding tube 6 of any of the control rods 3 of the RCC 1 reaches the allowable wear amount F, ,
This RCC1 needs to be replaced.

If the operation of the reactor is continued without performing １ ／ rotation of the RCC1, if the reactor stay time D is located on the side where the support pins 18 are not provided as shown in the curve A, The wear progress amount of the cladding tube 6 of the control rod 3 reaches the allowable wear amount F.

However, during the reactor stay time C, 1/4 rotation of RCC1 is performed, and
1 is reloaded, as shown in curve A,
Since the control rod 3 located on the side having no support is located on the side having the support pin 18 after 1/4 rotation, the wear progress rate of the cladding tube 6 is reduced. As a result, RCC1
The time required for the wear amount of the cladding tube 6 of the control rod 3 in which the wear is most advanced to reach the allowable wear amount F is extended from the stay time D to the stay time E.

On the other hand, as shown by the curve B, the support pins 18
Since the control rod 3 located on the side with the support rod 18 is located on the side without the support pin 18 after 1/4 rotation, the rate of progress of wear is increased.

The storage means, take-out / transfer means, and rotation means referred to in the claims correspond to the RCC storage container 22, the RCC take-out / transport device 20, and the RCC take-out / transport device rotation device 21 in the embodiment of the present invention. Further, the first and second predetermined storage locations in the claims correspond to the fuel rack 40.

As described above, in the loading method to which the rotating device of the control rod assembly for a reactor according to the embodiment of the present invention is applied, the RCC 1 is taken out of the reactor core at an appropriate time, and By loading the core again after the rotation, the wear concentrated on the control rod 3 on the side where the support pin 18 is not provided during the operation of the reactor can be dispersed to other control rods 3.

That is, the RCC during operation of the reactor
Since the progress of the maximum wear of No. 1 is suppressed, it is possible to extend the life of RCC1.

The structure of RCC1 is originally 1/4
Since it is rotationally symmetric, it is possible to reload by rotating it by 1/4 turn without performing a hardware modification or the like.

The fuel assemblies 10 of the PWR are regularly arranged at equal intervals in the core, and the distribution of the fuel enrichment is uniform. Therefore, the nuclear characteristics are also 1/1 with the axis in the axial direction passing through the center of the cross section of the fuel assembly 10 as the rotation axis.
Since it is 4-rotationally symmetric, there is no nuclear influence even if RCC1 rotated 1/4 is used.

Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to such configurations. Within the scope of the technical idea described in the claims, those skilled in the art can come up with various modified examples and modified examples, and these modified examples and modified examples are also within the technical scope of the present invention. It is understood that it belongs to.

[0057]

As described above, according to the method and the apparatus for loading a control rod assembly for a nuclear reactor of the present invention, the RC
Remove C1 from the reactor core at an appropriate time, and
Since the core is loaded again after rotating,
The progress of wear of the control rods during operation of the reactor can be reduced. This makes it possible to extend the life of the control rod assembly for a nuclear reactor.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the entire configuration of a rotating device for realizing a method of loading a control rod assembly for a nuclear reactor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a method of loading a control rod assembly for a nuclear reactor according to the embodiment.

FIG. 3 is a schematic diagram showing the progress of wear of the RCC realized by the method for loading a control rod assembly for a nuclear reactor according to the embodiment.

FIG. 4 is a front view showing a configuration example of a control rod assembly for a reactor used in a pressurized water reactor.

5A is a front sectional view showing a configuration example of a control rod, and FIG. 5B is a sectional view taken along line AA.

FIG. 6 is a perspective view showing a configuration example of a fuel assembly used in a pressurized water reactor.

FIG. 7 is a schematic diagram showing a state where a control rod is inserted from a control rod drive mechanism into a fuel assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reactor control rod assembly (RCC), 2 ... Spider, 3 ... Control rod, 4 ... Neutron absorber, 5 ... Spring, 6 ... Cladding tube, 7 ... Upper end plug, 8 ... Lower end plug, 9 ... Center shaft, 10 ... Fuel assembly, 11 ... Control rod guide thimble, 14 ... Control rod drive unit, 15 ... Control rod guide tube, 16 ... Upper core plate (UCP), 17 ... Gap, 18 ... Support pin, 19 ... coolant, 20 ... RCC removal and transfer device, 21 ... RCC removal and transfer device rotating device, 22 ... RCC storage container, 23 ... RCC rotation jig, 30 ... projection, 32 ... guide port, 33 ... insertion guide, 40 ... fuel rack.

Claims (2)

[Claims] An axial axis passing through the center of a binding direction cross section of a binding body formed by binding a plurality of long control rods containing a neutron-absorbing substance is used as a rotation axis. A control rod assembly for a reactor, in which the plurality of control rods are arranged so as to be symmetrical, is loaded on a reactor core, and after operating the core for a predetermined period, the core is taken out of the core, and the rotation axis is centered. A method of loading a control rod assembly for a nuclear reactor, characterized in that the core is loaded again by rotating it by １ ／ rotation from the state loaded on the core by １ ／ rotation. 2. A quarter axis rotation about an axis in the axial direction passing through the center of a section in a binding direction of a binding body formed by binding a plurality of long control rods containing a neutron absorbing substance. Storage means for storing a control rod assembly for a reactor in which the plurality of control rods are arranged so as to be symmetrical; removing the control rod assembly for a reactor from a first predetermined storage location to the storage means Transported and stored in the storage means, the control rod assembly for the reactor stored in the storage means is taken out and transferred to a second predetermined storage place, and the second predetermined storage place The removal and transfer means for storing the control rod assembly for a nuclear reactor in the storage means, and the removal and transfer means after rotating the removal and transfer means 1/4 in a predetermined direction around the axis as a rotation axis, From the storage means to the control rod for the reactor A control rod assembly for a nuclear reactor, comprising: rotating means for rotating the unloading and transferring means after the union is taken out, by a quarter of rotation about the axis as a rotation axis in a direction opposite to the predetermined direction. Body rotation device.