JPS58195187A - Control rod drive mechanism - 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 control rod drive mechanism that increases the insertion speed of control rods into a reactor core during scram.

[Technical background of the invention]

Figure 31 shows a liquid metal cooled fast breeder reactor, in which the upper end opening of the reactor vessel 1 has a fixed plug 2 having a circular hole at an eccentric position, and a fixed plug 2 that rotates to close the circular hole. (Ha)Tan that can be attached freely! It is shielded by a shielding body consisting of a lug 3. A reactor core 5 is configured inside the reactor vessel 1 and supported by an in-reactor support part 4, and
A liquid metal (usually liquid sodium) i is contained as a coolant. Then, the liquid metal 6 flows into the high-pressure plenum 8 below the reactor support section 4 through the primary cold radar piping 7, and the reactor core configuration I! It flows upward through the reactor core 5, flows out from the primary system E connected to the peripheral wall of the reactor vessel 10, flows out from the Toleda piping III, and flows through the intermediate heat exchanger ( (not shown) and then back to the primary system cold leg piping 1 and high pressure plenum 8.
returned inside. In front, outside 1111 of the reactor vessel 1, a protective container 1i is provided to prevent the liquid metal 6 from flowing out.

On the other hand, spinning spinning! The core upper mechanism 12 is on the bottom side of the lug go.
Attach 111 so that it is located above the core 50) and rotate! A drive device 13 is attached to the top side of the rudder S. A plurality of control rod drive mechanisms 14 are provided inside the upper core mechanism 12. These control rod drive mechanisms 14 control the reactivity of the reactor core i by inserting and withdrawing the control rods 15 into and out of the reactor core 5 from above.

As shown in FIG. 2, lower guide tubes 1d for guiding the control rods 15 are provided in the reactor core 5, corresponding to each control rod 15.

FIG. 2 shows the control rod drive mechanism 14, in which 1
1 is one of a plurality of casings attached to the core upper mechanism 12. Also, said rotation! On the top side of the rudder 3 is a drive motor 8 that is the drive source of the control rod drive mechanism 14.
is housed therein, and an extension pipe 20 is connected to the basket 18 via a connecting mechanism 19. The configuration of the connection mechanism 19 is as follows. That is, 21 in the figure is an I-le screw that is rotationally driven by the motor 8.':1: This? -Gerna and G 22 are screwed together with the screw 21, and -
The lunnut 11 is configured to move up and down as the lunnut 21 rotates. Furthermore, a cylindrical electromagnet holder 24 is suspended from the lower surface of the nut xxo via a load cell 23, and is configured to monitor the insertion state of the control rod 15 based on the load detected by the load cell 23. . An electromagnet 25 is attached to the upper end of the electromagnet holder 24], and an actuator 26 that attracts or expands and detaches from the electromagnet 25 (see FIG. 3) is disposed below the electromagnet 25. A plurality of engagement claws 21 are pivotally supported on the lower surface of the actuator 26, and a plurality of links 28 are pivotally supported on the inner peripheral surface of the electromagnet holder 24, and these engagement claws 27 and links 28 connect their rotating ends. It constitutes a link mechanism. The engaging claws 21 have an engaging stepped portion 29 on the inner edge as shown in FIG. When the actuator 2# is closed and removed from the electromagnet 25, it opens as shown in FIG.

A plurality of drive section separation claws 30 are pivotally supported at the lower end of the electromagnet holder 24, and these separation claws 30 are held in a closed state by being surrounded by a cylindrical claw holder JJK. Note that the pawl holder 11 is pushed upward (downward) by an operation tube (not shown) to open the separation pawl 30.

The extension tube 20 is composed of an inner extension tube 32 and an outer extension tube 33 attached to its outer periphery, and these extend from the casing 17 to an upper guide tube 34 attached to the upper core mechanism 12. There are a lot of people inside.

The internal extension pipe 32 has a large diameter JJA pipe at the upper end, and
The large diameter portion 32m is introduced downward into the electromagnet holder 24, is gripped by the plurality of engaging claws 21, and is suspended within the upper guide tube 14.

At the front, below the large diameter part 32, there is a flange-like strike 9 part 321, the lower half of which is formed narrowly, and the lowermost end has a medium or large diameter finger ring.

It has a de Jl.

The front external extension pipe 33 also has a large diameter part J at the upper end. has A,
This large-diameter S33 entry tube is held by the drive section separation claw JO. And the strut and ivy portion 32 of the internal extension tube 12
By bringing Bt into contact with this large diameter portion 33k (from above), p
1. The amount of fall of the internal extension tube 32 is regulated.

'*There is a 7-lunge-shaped stop 9 part JIB at the lower position of the 9th large diameter part jjA, and this strike 9 part 33B is brought into contact with the contact part JI6 at the lower end of the casing 1r upwardly. ) The amount of downward movement is regulated.

Furthermore, the external extension pipe 33 has a plurality of holes and a tiffin t at the lower end.
rsv. These fins fJ1 have engaging portions that protrude outward and have an elastic restoring force inward, but normally the inward restoring is prohibited by the finger holes and do 35. ing.

On the other hand, the control@16 has a handling head 38 at the upper end.
’ has. To this J1 ring, the door 3a has a concave shape with an open upper end, and a retaining edge JJI&
It has the following characteristics. Then, the retaining edge ssA is engaged with the off finger 37, and it is suspended in the upper guide pipe 34, and the lower end is passed through the lower guide pipe 1# to allow a person to enter the reactor core 5. There is.

An acceleration tube 39 is attached to the outside of the external extension tube SSO. This acceleration tube 39 has its lower end connected to the upper end of the control rod 15, that is, the handling.

The upper end has a large diameter portion 39k, and this large diameter portion 39k is extended into the inner part of the upper guide tube 34 and is brought into contact with the round annular strut, 1 part 40. (especially) K is set so that the amount of fall is regulated.

Further, an acceleration spring 42 such as a compression coil spring is inserted in a stored (compressed) state between the upper end of the acceleration tube 39 and a spring receiver 41 provided inside the upper guide tube 34. ing.

Next, the operation of the nine-control m drive mechanism 14 constructed as described above will be explained.

First, the output control of the core 5 during normal operation is performed by the motor 8. That is, when the motor 18 is driven to rotate the 1:□, '≠ screw 21, the male nut 22 moves up or down depending on the direction of rotation of the screw 21. Therefore, one stone 25, t actuator 26, extension fzo and control ring 15 are also
22. As a result, the number of control rods 1j inserted into the core 5 changes, and the core jO reactivity is controlled.

9. For example, when an emergency stop occurs in the event of an earthquake,
The supply of current to the PT magnet 25 is cut off by the scram signal,
Lower acti and eta Jgt. As a result, the engaging claw 21 is opened as shown in FIG. 3, and is removed from the large diameter portion 32, so that the internal extension tube 32 falls. At this time, the internal extension tube 3
As the nine-finger rod 35 provided at the lower end of the control rod 2 is lowered from the position shown in FIG. 4 to the position shown in FIG. . Further, since the acceleration tube 3g is always urged downward by the acceleration spring 42, the urging force of the spring 42 is obtained to accelerate the falling speed of the control rod 1j.

As a result, the control rods IJ are urgently inserted into the reactor core 5.

[Problems with background technology]

The acceleration spring 42 for accelerating the falling speed of the control rod 15 is kept energized for a long period of time during normal operation of the reactor.
Moreover, it is maintained within a high temperature range (for example, 500° C.). Therefore, the acceleration spring 42 may experience so-called relaxation, in which the stress decreases over time. If relaxation occurs, the pressing force of the acceleration spring 42 against the acceleration tube 39 during scram operation becomes weaker, so the scram operation time becomes longer, resulting in an unfavorable outcome from the standpoint of reactor safety. is expected.

On the other hand, it is not preferable to weaken the rigidity of the spring simply to prevent relaxation or to reduce the size of the elastic displacement tube during energy storage, as this will weaken the pressing force against the acceleration tube 39.

[Purpose of the invention]

The present invention was made based on these circumstances, and
The purpose is to provide a control rod drive mechanism that can prevent relaxation of the acceleration spring, shorten the scram operation time, and improve reactor safety.

[Summary of the invention]

The control rod drive mechanism according to the present invention is characterized in that a plurality of acceleration springs are inserted in a well-energized state between spring receivers provided in each of the upper guide tube and the acceleration tube.

If multiple acceleration springs are used to apply biasing force to the acceleration tube in this way, it is possible to weaken the image quality of each acceleration spring (9) and reduce the amount of elastic displacement that occurs when accumulating energy. υ, this can prevent acceleration spring leakage. Moreover, by using a plurality of acceleration springs, the biasing force against the control rods can be increased, the scram operation time can be shortened, and the safety of the reactor can be improved.

[Embodiments of the Invention] □, 1': First, a first embodiment shown in FIGS. 6 to 1O- will be described.

FIG. 6 shows a liquid metal cooled fast breeder reactor, in which the upper end opening of the reactor vessel 101 has a fixed plug 102 having a circular hole at an eccentric position, and a fixed plug 102 that closes the circular hole. Rotatably attached nine-turn plug 10
3) is shielded. Inside the reactor vessel 101, a reactor core 105 is supported by an in-reactor support part ion, and a liquid metal (usually liquid sodium) 106 as a coolant is accommodated. ° Then, the liquid metal 106 is transferred to the primary cold leg piping 10.
7, flows into the high-pressure plenum 108 below the reactor support 104, flows upward through the core component lower part 109, through the core 105, and is connected to the peripheral wall of the reactor vessel 101. System hot leg piping 110 leaked out,
An intermediate heat exchanger (
(not shown), and is returned to the high-pressure plenum 108 from the primary cold reder piping 107. Nine, there is a structure on the outside of the reactor vessel 1010 to prevent the liquid metal 106 from flowing out.
A first protective container 11 is provided.

On the other hand, a core upper mechanism 112 is attached to the upper surface of the rotary plug 103 so that it is located above the core 105, and a drive device 313 is attached to the upper surface of the rotary plug 103. A plurality of control rod drive mechanisms 114 are provided inside the upper core mechanism 112. These control rod drive mechanisms 114 control the reactivity of the reactor core 10B by upwardly inserting and withdrawing the control rods 115 into the reactor core 105. Note that the reactor core 105 includes a lower guide tube 115 that guides the control rods 115 as shown in FIG.
A corresponding one is provided for each control rod 115.

FIG. 7 shows the control rod drive mechanism 114, and numeral 117 in the figure is one of a plurality of casings attached to the core upper mechanism 112.

Also, l! The itI rotation pre-rotation plug 203 accommodates a drive motor 118 which is a drive source for the control rod drive mechanism 114, and an extension tube XXO is connected to this motor 118 via a connection mechanism 1119. The connection mechanism 119
The structure is as follows. That is, in the figure, 121 is a male screw rotated by a motor 118, and an I-luna and a male screw 12 are screwed together. −
The fi&-lu nut 122 is configured to move up and down as the screw 121 rotates. In addition, the above
A cylindrical electromagnet holder 124 is suspended from the lower surface of the control rod 116 via a load cell 123, and is configured to monitor the insertion state of the control rod 116 based on the load detected by the load cell 123. An electromagnet 115 is attached to the upper end of the electromagnet holder 124, and an actuator 126 that attracts or detaches from the electromagnet 125 (see FIG. 8) is disposed below the electromagnet 115. Further, on the lower surface of the actuator 126, an engaging claw 127 and an electromagnet holder 124 are provided.
A plurality of links 1z8 are respectively pivoted on the 0-circumferential surface, and these engaging claws 127 and links 128 connect their rotating ends to form a link mechanism. In addition, the engaging claw 127
As shown in FIG. 8, the engaging step portion 129 is shouldered on the inner edge, and when the actuator 126 is attracted to the electromagnet 125, the plurality of locking pawls 127 are closed as shown in FIG. When 126 separates from electromagnet 125, it opens as shown in FIG.

A plurality of drive part separation claws 130 are pivotally supported at the lower end of the electromagnet holder 124, and these separation claws 130 are surrounded by a cylindrical mold presser 131 and held in a closed state. It should be noted that the mold presser 131 is pushed downwardly by an operation tube (not shown) to open the separation claw 130.

The extension pipe 120 is composed of an inner extension pipe isz and an outer extension pipe 133 attached to the outer periphery of the inner extension pipe isz.
It is housed inside the upper guide tube J34 attached to □:.

...-Go.

The upper guide f134 is arranged above the reactor core 105 with its axis oriented in the vertical direction. The internal extension tube 132 has a large-diameter portion 132 at its upper end, and the large-diameter portion 132A is introduced downward into the electromagnet holder 124 and is held by the plurality of retaining portions 121 to guide the upper portion. It is suspended within tube 134. t, the above large diameter W, zs
There is a flange-shaped stop at the lower position of xh.
f: 4, the lower half is formed thin, and the lower end has a finger rod 135 with a slightly larger diameter.

Further, the external extension tube 133 also has a large diameter portion 133A at the upper end, and when the large diameter portion 133 is removed, the drive section separation claw 13
It is held at 0. Then, move the f section 132B of the internal extension pipe 132 above this large diameter section 7.9JAK)
By bringing them into contact with each other, the amount of fall of the internal extension tube 132 is restricted. In addition, at the lower position of the large diameter portion 133A, there is a flange 1-shaped strut, a base portion xs:tBf4,
By bringing this strike 9 part 133B into upward contact with the phantom portion 136 at the lower end of the casing 117, the downward movements m and t are restricted. moreover,
The external extension pipe 133 has a plurality of pipes and fins 1137 at the lower end.
There is a disaster. These bags and typhin eisr have retaining portions protruding outward 9 and have an elastic restoring force inward, but normally the finger rods 135 prevent inward restoring. ing.

- 10,000, to the upper end of the control rod 115, to the handling
It has 38. For this handling, the door 138 has a concave shape with an open upper end, and a retaining edge 138 is formed on the inner periphery of the open end.
A. The retaining edge 138k is engaged with the tefinger 137, suspended within the upper guide tube 134, and the lower end is inserted into the core 105 through the lower guide v116.

Further, an acceleration tube 139 is attached to the outside of the external extension tube 133. This acceleration tube 139 has a lower end connected to the control rod 115.
The upper end, i.e., is brought into contact with the handling head 13JF, and has a large diameter portion 139A on the outer periphery near the upper end,
By bringing this large diameter portion 139A into contact with the annular stop/arm portion 140 provided inside the upper guide tube 134,
Uploading is now regulated.

The acceleration tube 1314 has a first spring receiving portion 14 at its upper end, and a second spring receiving portion 142 at the upper surface of the large diameter portion 139A. Further, on the inner surface of the upper guide tube 134, a nozzle of the first spring receiving portion 14 of the acceleration tube 139 is located in the upper direction #.
It has a spring receiving part 143 with stripes 1, and the acceleration tube 13
A second spring receiving portion 144 is provided at approximately the same height as the first spring receiving portion 141 of No. 9.

In the figure, 141i and 146 are respectively 1st. This is the second acceleration spring. All of these are configured as compression coil springs having a conical shape. and a first acceleration spring 145
is compressed in the axial direction by bringing the large diameter end into downward contact with the #il spring receiving part 143, and bringing the small diameter end into contact with the first spring receiving part 141 of the acceleration tube 1390. It is maintained in the same condition. '*For the second acceleration, the large diameter end of the spring 146 is brought into contact with the second V spring receiver 144 from below, and the small diameter end is brought into contact with the second spring receiver for acceleration '1jzs9. Part 14. ?
t and is held in a compressed state in the axial direction.

Next, the operation of the control rod drive mechanism 1140 configured as described above will be explained.

During normal operation, the output of the core 105 is controlled by the motor 18. That is, when the motor 18 is driven to rotate the I-rule screw 121, ? -Luna,)
111 rises or falls depending on the direction of rotation of the goal screw 121.

Therefore, the electromagnet 125, the actuator 126, the extension tube 126, and the control rod JJJ also move up or down together with the Lunar 122. As a result, the amount of insertion of the control rods 115 into the reactor core 105 changes, and the reactivity of the reactor core 105 is controlled.

1゜In addition, when making an emergency stop (for example, in the event of an earthquake), a scram signal is sent to the multi-electromagnet 125.
□...:.

The current supply is cut off, and the actuator 126 is lowered. As a result, the engaging claw 127 opens as shown in FIG. 8, and the large diameter @ J J! &, so the internal extension tube 132 falls. At this time, the finger ring 135 provided at the lower end of the internal extension tube 132 is lowered from the position shown in FIG. 9 to the position shown in FIG.
When the control rod J J J is handled, it comes off from the handle 138 and the control rod 115 falls. Furthermore, since the acceleration tube 139 is always urged downward by the acceleration springs xis and 14tiK, the falling speed of the control rod i1M is accelerated by the urging force of these springs 145 and 146. Control rod 1 at this time
The initial acceleration force F of 15 is given by the following equation.

''' /s+/m -ktJt+km Js Here, fl and fmB are the first and second acceleration springs 141, respectively.
, 1411 compressive stress in scram straight bend, klsk
l is the first . Spring constant of acceleration springs 145, 146 of 2nd), J! t・:h 1' is the previous, □11・2nd degree acceleration is 7"・146
is the amount of axial compression.

Thus, the control rods 115 are inserted into the reactor core 105 in an emergency.

Next, when it is necessary to perform maintenance on the mechanism accommodated in the casing 117, the mold presser 131 is raised using an operation tube (not shown). This is K)
The separation claw 130 is released from the restraint by the mold presser 131, opens outward, and is removed from the large diameter portion 133 of the external extension tube 1310. Cut off the supply of current to the electromagnet 125,
When the actuator ixn is lowered, the engaging claw 121 comes off from the large diameter portion 132A of the extension tube 1320 as shown in FIG.
It can be separated and transported to a designated maintenance facility.

The effects of the above embodiment are as follows.

Since the acceleration tube 139 is biased by the two acceleration springs 145 and 146, the initial acceleration force F of the control @ 115 during scram operation is kl 't+ic*
It is given by a. Therefore, in order to obtain the same initial acceleration force F as when using one acceleration spring, it is possible to reduce both the spring constant klskl and the axial compression amount δ1, J of each acceleration spring 145°146. ,
As a result, each acceleration spring has 146.146 degrees of force,
This can improve the safety of nuclear reactors by keeping the gases in a separated state. In addition, as a means for changing the breakage constant, it is sufficient to change the length, the diameter of the spring cable of 4 m, the effective number of turns, the effective diameter, etc. Furthermore, it is possible to increase the initial acceleration force F in a state where relaxation is difficult to occur, and by increasing the initial acceleration force F, the control rod 115
(insertion speed is fast), and the scram operation time can be shortened.

In addition, in the above embodiment, two acceleration springs 145° and 146 are used, but three or more may be used. Here, the initial acceleration force F of wI011 salary 115 is
Generally, it is given by the following formula.

, J,, -,1h, ai 1=1 +=1 Also, by using a conical compression coil spring as the pressure spring as in the above example, the axial dimension can be reduced. There are advantages.

Next, the second and third embodiments of the present invention shown in Fig. 11 and Fig. 12 will be explained.

In both of these, a cylindrical compression coil spring is used as the first.
In this example, it is used as the second pressure spring 147, 14B,
The same parts as in the first embodiment are given the same reference numerals. In addition, in the embodiment shown in Figure 12, the pressure pipe is the upper pressure pipe 1.
49 and the lower pressurizing pipe 150 are connected to each other to facilitate the manufacture of the pressurizing pipe.

And the second above. According to the third embodiment, the same effects as in the first embodiment can be obtained.

〔Effect of the invention〕

As detailed above, the control rod drive mechanism according to the present invention includes:
It is characterized by a plurality of accelerating springs being inserted in a energized state between spring receivers provided in each of the upper guide tube and the accelerating tube, including:

Therefore, the spring surface force of each pressure spring can be reduced without weakening the bias against the control rod. Therefore, pressurization is easy.

This makes it possible to prevent the occurrence of accidents and shorten the scram operation time, thereby increasing the safety of the nuclear reactor.

[Brief explanation of drawings]

Figures 111 to 5 explain the background technology. Figure 1 is a longitudinal cross-sectional view of a fast breeder reactor, and Figure 2 is a control rod drive IIh.
A vertical sectional view of the mechanism, FIG. 3 is an enlarged vertical sectional view of a part of the mechanism, FIGS. 114 and 5 are vertical sectional views showing the scram operation of the mechanism, and FIGS. The first aspect of the present invention
Fig. 6 is a longitudinal sectional view of a fast breeder reactor, Fig. 7 is a longitudinal sectional view of the control rod drive mechanism, and Fig. 8 is an enlarged longitudinal sectional view of a part of the mechanism. The top view, FIGS. 9 and 10 are vertical sectional views showing the scram operation of the same mechanism, and FIGS. 11 and 112 are respectively the second. There is a partial sectional view of the control rod drive mechanism showing the 39th embodiment. 〃 105...Reactor core, 111...Control rod, 118...
Drive "[,,,9 Drive motor (drive source), X; tO... Extension tube, 132.
...Internal extension pipe, 133...External extension pipe, 134...
・Top Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 Figure 9 Figure 10 Figure 11 Figure 72

Claims (4)

[Claims] (1) An upper guide tube that has a spring receiver inside and is placed above the core with its axis facing vertically, and a control rod that is placed inside this upper guide tube O and supports the control rods by suspending it at its lower end. an extension tube that disconnects the control rod in response to a scram signal; a drive source that inserts and withdraws the control rod from the core through the extension tube; an acceleration tube that is attached to the outer periphery of the extension tube in contact with the upper end of the rod and falls together with the control rod when the control rod is separated from the extension tube; a spring receiving portion of the acceleration tube; and a plurality of acceleration springs which are inserted in a stored state between the control rod and the spring receiver and which accelerate the falling speed of the acceleration tube when the control rod is separated from the extension tube. Tosui control rod drive mechanism. (2) The control rod drive mechanism according to claim (1), wherein the plurality of acceleration springs are compression coil springs. (3) The control rod drive mechanism according to claim (2), wherein the compression coil spring has a conical shape. (4) The control rod drive mechanism according to claim 1, wherein the acceleration tube and the upper guide tube are each provided with the same number of spring receivers as the acceleration springs.