JP2008051767A - Reflector control reactor and method for controlling its output - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflector control reactor which can prevent a reflector from breaking even if the reflector falls down due to a failure such as a pump trip and a method for controlling the output of the reactor. <P>SOLUTION: The reflector control reactor includes a core, a shield which is placed so that it can surround the core circumferentially and shields from neutrons emitted from the core, the reflector 9 to reflect neutrons between the core and the shield, a positioning mechanism 11 for fine-controlling the axial position of the reflector 9 to the core, and a reactor vessel including these. The reactor has a floating mechanism 18 placed below the reflector 9 to float it up with coolant 5 and a shock absorber 15 including a piston and a cylinder for relieving the impact on the reflector 9 when it drops by gravity in the pump trip. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reflector control reactor that ensures safety by dropping a reflector when the reactor is shut down, and an output control method thereof.

  A sodium-cooled small reactor that has high safety and can be operated without changing fuel for a long period (target 30 years) is a commercial nuclear reactor that adjusts fuel combustion by moving a reflector at a minute speed. This small sodium-cooled reactor uses a metal fuel core that is easy to ensure passive safety and moves the reflector at a very low speed to ensure high safety and a long core life. (See Patent Document 1).

  Generally, in a reflector-controlled nuclear reactor, the core power is controlled by using the neutron streaming effect by controlling the movement of the reflector in the vertical direction on the outer periphery of the core.

  This reflector drive control is controlled by electromagnetic repulsion drive when the reflector is slightly moved, and during large movements such as when the reflector is lowered when the reactor is stopped or when the reflector is raised when the reactor is started. The drive shaft is installed on the reflector and the drive is controlled by the motor. However, if the nuclear reactor is operated for a long period of time, the motor is likely to fail, and the reflector becomes uncontrollable when the motor fails.

  Therefore, since it is not necessary to use dynamic equipment to safely operate the reactor for a long period of time, the reflector is driven and controlled by fluid force, or the reflector is dropped by gravity when an abnormality such as a pump trip occurs. Reflector controlled reactors have been considered.

  That is, when the reactor is started, the reflector and the reflector levitation mechanism are lifted together with the buffer device due to the pressure difference generated in the buffer device as the coolant flow rate flowing into the reflector levitation mechanism increases. During the rated operation of the reactor, that is, when the rated coolant flow rate is flowing into the reflector levitation mechanism, the state where the reflector and the reflector levitation mechanism are raised is maintained.

When an abnormality such as a pump trip occurs, that is, when the coolant flow rate flowing into the reflector levitation mechanism decreases, the reflector and the reflector levitation mechanism drop by gravity.
JP-A-5-119175

  When the reflector falls by gravity with a decrease in the coolant flow rate, the reflector may collide with a stopper installed at the lower portion, and the reflector may be damaged.

  The present invention has been made in view of the above problems, and provides a reflector-controlled nuclear reactor and a power control method thereof that prevent damage to the reflector even when the reflector falls due to an abnormality such as a pump trip. Objective.

  In order to solve the above problems, a reflector-controlled nuclear reactor according to the present invention includes a core, a shield that surrounds the core in the circumferential direction, shields neutrons emitted from the core, and a core and a shield. In a reflector control reactor comprising a reflector for reflecting neutrons in between, a position adjusting mechanism for finely adjusting an axial position of the reflector with respect to the core, and a reactor vessel containing these, the reflector And a buffer mechanism including a piston and a cylinder for buffering the reflector when the reflector is dropped by gravity when the reflector pump is tripped. To do.

  According to the reflector control nuclear reactor and the power control method thereof according to the present invention, it is possible to prevent the reflector from being damaged even when the reflector is dropped due to an abnormality such as an electromagnetic pump trip.

  DESCRIPTION OF EMBODIMENTS Embodiments of a reflector control reactor and its power control method according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a configuration diagram of a first embodiment of a reflector controlled nuclear reactor according to the present invention, and FIG. 2 is a top view of a reflector of the reflector controlled nuclear reactor.

  As shown in FIG. 1, the reflector-controlled nuclear reactor 1 is provided with a fuel assembly storage area 3 in which a fuel assembly (not shown) is stored in the vicinity of the center in a cylindrical reactor vessel 2. . The fuel assembly storage area 3 is provided with a core 4.

  An upper plenum 6 and a lower plenum 7 to which the coolant sodium 5 convects are provided above and below the fuel assembly storage region 3, respectively.

  A barrel-shaped, sleeve-shaped, or cylindrical core barrel 8 is installed on the outer periphery of the fuel assembly storage region 3 so as to completely surround the fuel assembly storage region 3, and further, the reactor core 4 A cylindrical reflector 9 having the same length is provided to be slidable in the axial direction. The reflector controlled nuclear reactor 1 is configured to perform core power control by moving the reflector 9 up and down in the axial direction with respect to the core 4.

  As shown in FIG. 2, the reflector 9 is installed in a cylindrical shape by arranging and combining a plurality of reflector blocks 10, which are arc-shaped blocks in a plan view, as shown in FIG. 2. As shown in FIG. 3, the core 4 The neutron n leaking out from the core 4 is scattered and returned to the core 4 again.

  The core barrel 8 is provided with a position adjusting mechanism 11 for finely adjusting the vertical position of the reflector 9.

  The outside of the reflector 9 is covered with a cylindrical partition 12, and a shield 13 for absorbing neutrons n and γ rays generated in the core 4 is provided on the outer periphery of the partition 12.

  An electromagnetic pump 14 for circulating the coolant sodium 5 is provided above the shield 13.

  The coolant sodium 5 in the reactor vessel 2 is discharged downward by the electromagnetic pump 14, flows downward around the shield 13, and reaches the lower plenum 7.

  The coolant sodium 5, whose flow is reversed in the lower plenum 7, rises in the core flow path R <b> 1, which is the fuel assembly housing region 3 including the core 4, and flows to the upper plenum 6. At this time, a part of the coolant sodium 5 is partitioned by the partition wall 12 and the core barrel 8 and flows up to the cylindrical reflector channel R2 provided with the reflector 9, and flows to the upper plenum 6.

  When the coolant sodium 5 ascends the reflector flow path R2, the reflector 9 floats due to the fluid force of the coolant sodium 5. At this time, the floating and falling behavior of the reflector 9 is determined by the balance between the fluid force (drag) of the coolant sodium 5 and the buoyancy and gravity of the reflector 9.

  The reflector 9 moves up and down in a torus-like, annulus-like, and cylindrical reflector raising / lowering region A surrounded by the core barrel 8 and the partition wall 12. The up-and-down movement of the reflector 9 is mainly a coolant. It is controlled by the fluid force of the sodium 5 and is adjusted by the position adjusting mechanism 11 in the case of a minute movement.

  As shown in FIG. 4, the reflector 9 rises and rises as the discharge pressure of the electromagnetic pump 14 increases. When the reflector 9 is in an axial position around the core 4, even if neutrons n are emitted by the nuclear reaction of the core 4, they are reflected by the reflector 9 and return to the core 4, and surely in the core 4. Since the nuclear reaction is continued and the nuclear reaction is continued, the reactor power increases.

  Further, when the coolant flow rate is lost such as a trip of the electromagnetic pump 14, the pump discharge pressure decreases as shown in FIG. Since the gravity of the reflector 9 is superior to the fluid force of the coolant sodium 5, the reflector 9 falls, and the neutron n emitted from the core 4 is absorbed by the shield 13 without being reflected by the reflector 9 again. Therefore, passive furnace power shutdown is achieved.

  The coolant sodium 5 that has reached a high temperature in the upper plenum 6 is guided to a heat exchanger (not shown), and returns to the suction side of the electromagnetic pump 14 again after heat removal.

  As described above, the reflector 9 raised by the fluid force of the coolant sodium 5 falls by gravity when the coolant flow rate is lost. However, the reflector 9 may be damaged by the impact of the drop. In the reflector controlled nuclear reactor 1, a reflector lower shock absorber 15 that absorbs impact force is provided in the reflector 9.

  FIG. 6 is an enlarged configuration diagram of the reflector channel R2.

  In the reflector flow path R <b> 2, the reflector 9 is provided in the reflector lifting / lowering region A surrounded by the core barrel 8, the partition wall 12, and the sector wall 16. The upper part of the reflector 9 is provided with a cavity 17 filled with gas and a position adjusting mechanism 11 for finely adjusting the vertical position of the reflector 9, and a box for floating the reflector 9 below the reflector 9 A reflector levitation mechanism 18 is provided. Further, the cavity 17 and the reflector 9, and the reflector 9 and the reflector floating mechanism 18 are each connected by a universal joint 19.

  Further, as shown in FIGS. 6 and 7, the reflector floating mechanism 18 has a plurality of reflector lower shock absorbers 15 therein.

  FIG. 8 and FIG. 9 are enlarged configuration diagrams showing the operating state of the reflector lower shock absorber 15.

  The reflector lower shock absorber 15 includes a cylindrical upper cylinder 20 and an upper piston 21 as shown in FIGS. 8 and 9. The upper cylinder 20 has an upper lid 22 in the upper portion and a lower lid 23 in the lower portion, and the upper piston 21 is accommodated in the upper cylinder 20 so as to be slidable in the axial direction.

  An upper orifice 24 and a lower orifice 25 through which the coolant sodium 5 enters and exits are provided on the upper and lower sides of the side surface of the upper cylinder 20, respectively.

  An upper piston 21 is accommodated in the upper cylinder 20 so as to be slidable in the axial direction with a predetermined stroke. The upper piston 21 is provided with a piston rod 26 that extends through the lower lid 23 of the upper cylinder 20, and a landing foot 28 is provided at the lower end of the piston rod 26.

  A lower stopper 27 for receiving the landing foot 28 is fixed to the core barrel 8 below the upper cylinder 20. The landing foot 28 of the piston rod 26 contacts and cushions the lower stopper 27 when the reflector 9 is dropped, so that the foot of the reflector 9 is buffered.

  FIG. 8 shows the state of the upper cylinder 20 and the upper piston 21 when the reflector 9 floats. FIG. 9 shows the state of the upper cylinder 20 and the upper piston 21 when the reflector 9 falls. .

  When the reflector 9 rises, as shown in FIG. 8, the upper cylinder 20 rises integrally with the reflector 9, and the upper piston 21 is pushed down by gravity and contacts the lower lid 23 of the upper cylinder 20. The upper part of the upper piston 21 in the upper cylinder 20 is filled with the coolant sodium 5.

  On the other hand, when the reflector 9 falls, the upper cylinder 20 falls in a state where the reflector 9 is in contact with the lower cover 23 of the upper cylinder 20, and the landing foot 28 of the piston rod 26 contacts the lower stopper 27. Then, the upper piston 21 is lifted with respect to the upper cylinder 20 while being buffered by the fluid force of the coolant sodium 5.

  That is, the coolant sodium 5 flows into the upper cylinder 20 from the lower orifice 25 and the coolant sodium 5 in the upper cylinder 20 is discharged from the upper orifice 24, so that the upper cylinder 20 receives a buffering action and gradually. Fall into.

  The upper piston 21 finally comes into contact with the upper lid 22 of the upper cylinder 20 as shown in FIG.

  At this time, depending on the diameters of the upper orifice 24 and the lower orifice 25 and the gap between the upper cylinder 20 and the upper piston 21, the landing piston 28 of the piston rod 26 lands on the lower stopper 27 and then the upper piston 21 moves upward. The time until complete landing in the cylinder 20 is determined.

  FIG. 10 shows the impact load characteristics when the reflector 9 is dropped in the reflector-controlled nuclear reactor 1. The impact load when the reflector lower shock absorber 15 is not provided is F1, and the impact load when the reflector lower shock absorber 15 is provided is F2.

  The drop impact load F2 when the reflector lower shock absorber 15 is provided is dispersed twice in F2a and F2b with a time difference. This is because the impact load when the reflector 9 falls is dispersed into the load at which the landing foot 28 lands on the lower stopper 27 and the impact load at which the upper piston 21 and the upper cover 22 of the upper cylinder 20 collide.

  In addition, it was found that the impact load of both of them becomes “F2a + F2b <F1” due to the fluid force of the coolant sodium 5, and the impact load is mitigated by providing the reflector lower shock absorber 15.

  In the first embodiment, two reflector lower shock absorbers 15 are installed inside the reflector levitation mechanism 18 for each reflector block 10, but the present invention is not limited to this, and the reflector lower shock absorber 15 is 1 It may be a body or a plurality of bodies, and may be installed directly under the reflector 9 instead of inside the reflector floating mechanism 18.

[Second Embodiment]
Next, a second embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  In the reflector controlled reactor of the second embodiment, as shown in FIG. 11, the upper orifice 24 and the lower orifice of the side surface of the upper cylinder 20 of the reflector lower shock absorber 15 of the reflector controlled reactor 1 of the first embodiment. 25, a plurality of intermediate orifices 29 are provided.

  By installing the reflector lower shock absorber 15A below the reflector 9, the upper piston 21 passes through the intermediate orifice 29 when the reflector 9 is dropped, so that the impact force is absorbed stepwise due to the difference in flow resistance. Can be prevented.

  The diameter of the intermediate orifice 29 may be reduced (or increased) from the lower side to the upper side, or may be equal, and is appropriately set.

  In addition, as shown in FIG. 12, a plurality of rows of upper orifices 24, lower orifices 25, and intermediate orifices 29 on the side surface of the upper cylinder 20 may be provided. The flow resistance can be adjusted by adjusting the diameter Φ and the number N of the orifices by the combination of the diameter Φ and the number N of the orifices of the plurality of orifices.

[Third Embodiment]
Next, a third embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  In the reflector controlled nuclear reactor of the third embodiment, as shown in FIG. 13, the upper piston 21 of the reflector lower shock absorber 15 of the reflector controlled nuclear reactor 1 of the first embodiment is devised. This reflector lower shock absorber 15B is provided with a plurality of chevron labyrinths 30 that are chevron-shaped ridges along the circumferential direction on the side surface of the upper piston 21 to provide a flow resistance of coolant sodium flowing around the upper piston 21. It is.

  By installing the reflector lower shock absorber 15B below the reflector 9, the impact force is absorbed by the flow resistance when the reflector 9 falls or when the upper piston 21 moves in the upper cylinder 20, so that Damage to the body 9 is prevented.

  As shown in FIG. 14, the chevron labyrinth 30 may be formed by providing a plurality of arc-shaped gasket-like resistors 31 on the upper piston 21 of the reflector lower shock absorber 15B. At this time, the chevron labyrinth 30 is formed by digging a groove in the side surface of the upper piston 21 and inserting a gasket-like resistor 31 into the groove.

  As shown in FIG. 15, the gasket-shaped resistor 31 is formed in an arc shape having a notch 32 at one location. The gasket-like resistor 31 is installed on the upper piston 21 so that the positions of the notches 32 do not overlap in the axial direction. However, the position and number of the notches 32 are not limited to this, and may be arbitrarily set.

[Fourth Embodiment]
Next, a fourth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-3rd Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 16, the reflector controlled nuclear reactor of the fourth embodiment has a lower lid 23 of the upper cylinder 20 of the reflector lower shock absorber 15 when the reflector 9 of the reflector controlled nuclear reactor 1 of the first embodiment falls. A coil spring 33 is provided on the piston rod 26 of the upper piston 21 so as to buffer the collision between the grounding foot 28 and the landing foot 28.

  By installing the reflector lower shock absorber 15C below the reflector 9, when the reflector 9 falls, the impact force is absorbed by the flow resistance of the upper piston 21 and the upper cylinder 20, and the reflector is applied by the coil spring 33. Since the impact force at the time of landing 9 is reduced, the reflector 9 is prevented from being damaged.

  Further, as shown in FIG. 17, the upper portion of the upper piston 21 and the upper lid 22 of the upper cylinder 20 are buffered so as to buffer the collision between the upper lid 22 and the upper piston 21 in the upper cylinder 20 of the reflector lower shock absorber 15C. A coil spring 33 may be provided between them.

[Fifth Embodiment]
Next, a fifth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-4th Embodiment, and the overlapping description is abbreviate | omitted.

  18 and 19 are enlarged configuration diagrams of the reflector lower shock absorbers 15D and 15E according to the fifth embodiment. The reflector controlled nuclear reactor of the fifth embodiment includes a plurality of reflector lower shock absorbers 15D and 15E having different lengths of the piston rods 26A and 26B of the upper piston 21 in the reflector controlled reactor 1 of the first embodiment. It is a combination.

  For example, the reflector lower shock absorber 15D in FIG. 18 (the length L1 of the piston rod 26A) and the reflector lower shock absorber 15E in FIG. 19 (the length L2 of the piston rod 26B) are used in combination.

  By installing the reflector lower shock absorbers 15D and 15E below the reflector 9, the reflector 9 lands while relaxing by the flow resistance of the upper piston 21 and the upper cylinder 20 when the reflector 9 is dropped. Since the landing times of the shock absorbers 15D and 15E are different and the impact force is dispersed, the reflector 9 is prevented from being damaged.

  FIG. 20 is a diagram illustrating impact characteristics when the reflector 9 is dropped in the reflector controlled nuclear reactor according to the fifth embodiment. The landing time of the reflector lower shock absorber 15D (the length L1 of the piston rod 26A) is t1, and the landing time of the reflector lower shock absorber 15E (the length L2 of the piston rod 26B) is t2.

  Reflector lower shock absorbers 15D and 15E having different lengths of the piston rods 26A and 26B of the upper piston 21 are combined and installed in the lower part of the reflector 9, so that when the reflector 9 falls, the upper piston 21 and the upper cylinder 20 In addition to landing while mitigating due to the flow resistance, the landing time is different from t1 and t2, so the impact force is distributed in three stages, F3a, F3b and F3c. Therefore, when the impact force of the reflector controlled reactor of the fifth embodiment is compared with the impact force F1 when the reflector lower shock absorbers 15D and 15E are not provided, the inequality of F3a + F3b + F3c <F1 holds, and the piston of the upper piston 21 By varying the lengths of the rods 26A and 26B, the impact force is reduced, and damage to the reflector 9 is prevented.

  In FIG. 21, two reflector lower shock absorbers 15D (the length L1 of the piston rod 26A) and two reflector lower shock absorbers 15E (the length L2 of the piston rod 26B) are installed in the reflector floating mechanism 18. An example of use is shown.

  The reflector 9 and the reflector levitation mechanism 18 are connected by a universal joint 19, and a gas vent hole 34 penetrating the inside and outside of the reflector levitation mechanism 18 is provided in the upper part of the reflector levitation mechanism 18.

  When the reflector 9 is landed, the two reflector lower shock absorbers 15D of the length L1 piston rod 26A land, and then two reflector lower shock absorbers 15E of the length L2 piston rod 26B with a time difference. The impact force is dispersed by landing.

  In addition, as 5th Embodiment, although the example which installed 2 each reflector lower buffer apparatus 15D and 15E from which the length of piston rod 26 differs was shown, it is not limited to this, The piston rod 26A of the upper piston 21, The type of the length of 26B and the number of bodies to be installed may be arbitrarily set.

[Sixth Embodiment]
Next, a sixth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-5th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 22, the reflector controlled nuclear reactor of the sixth embodiment includes the upper piston 21 </ b> F of the reflector lower shock absorber 15 of the reflector controlled nuclear reactor 1 of the first embodiment and three disks 35. It is configured by laminating while providing a gap.

  By installing the reflector lower shock absorber 15F below the reflector 9, the coolant sodium 5 flows into the flow resistance of the upper piston 21F and the upper cylinder 20 and the gap between the disks 35 when the reflector 9 is dropped. Since the impact force at the time of landing is dispersed while relaxing by the generated flow resistance, the reflector 9 is prevented from being damaged.

  In addition, in 6th Embodiment, although the upper piston 21F is comprised from the three discs 35, it is not limited to this, You may set the number of the discs 35 arbitrarily.

[Seventh Embodiment]
Next, a seventh embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-6th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 23, the reflector controlled nuclear reactor according to the seventh embodiment includes the upper cylinder 20 and the upper piston 21 of the reflector lower shock absorber 15 of the reflector controlled nuclear reactor 1 according to the first embodiment. A rectangular parallelepiped inner cylinder 36 that surrounds the upper piston 21 in the upper cylinder 20 is provided to form a reflector lower shock absorber 15G. The inside of the inner cylinder 36 is filled with, for example, the coolant sodium 5.

  By installing the reflector lower shock absorber 15G at the lower part of the reflector 9, when the reflector 9 falls, it lands while being relaxed by the flow resistance of the upper piston 21 and the upper cylinder 20, but there is an impact force due to the inner cylinder 36. However, since the number is dispersed as much as the relaxation of the inner cylinder 36, the reflector 9 is prevented from being damaged.

  Further, as shown in FIG. 24, the upper piston 21 may be surrounded by the inner cylinder 36 and a through hole 37 penetrating in the axial direction may be provided in the upper piston 21. In this case, the coolant sodium filled in the inner cylinder 36 flows through the through hole 37.

[Eighth Embodiment]
Next, an eighth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-7th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 25, the reflector controlled nuclear reactor according to the eighth embodiment is formed such that the upper piston 21 of the reflector controlled nuclear reactor 1 according to the first embodiment is not cylindrical but formed in a bag shape opened at the top. It is.

  By installing the reflector lower shock absorber 15H below the reflector 9, when the reflector 9 falls, it is landed while relaxing by the flow resistance of the bag-like upper piston 21A and the upper cylinder 20, but the bag-like upper part Since the piston 21 has a large internal volume and the impact force is dispersed, the reflector 9 is prevented from being damaged.

  As shown in FIG. 26, a resistor 38 may be mounted on the outer side surface of the bag-shaped upper piston 21A. When the reflector 9 is dropped, a flow resistance is generated by the resistor 38, and the breakage of the reflector 9 is further prevented.

[Ninth Embodiment]
Next, a ninth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-8th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 27, the reflector controlled nuclear reactor according to the ninth embodiment is provided with a through hole 39 in the axial direction in the upper piston 21 of the reflector controlled nuclear reactor 1 according to the first embodiment. A rotating lid 40 for opening and closing the through hole 39 is provided.

  The rotary lid 40 is configured such that a flat plate that closes the through hole 39 is rotatably installed on a hinge joint 41 that is fixed to the center of the upper surface of the upper piston 21.

  By installing the reflector lower shock absorber 15J at the lower part of the reflector 9, when the reflector 9 falls, the reflector 9 is landed while being relaxed by the flow resistance of the upper piston 21 and the upper cylinder 20. When the body 9 is dropped, the rotary lid 40 is closed, and the impact force is dispersed as much as the relaxation of the upper piston 21, so that the reflector 9 is prevented from being damaged.

  When the reflector 9 and the upper cylinder 20 float together, the rotary lid 40 is opened and the upper piston 21 falls smoothly in the upper cylinder 20 as shown in FIG.

  Further, as shown in FIG. 29, a slide lid 42 may be used instead of the rotary lid 40. That is, the slide lid 42 includes a disc 43 that opens and closes the through hole 39 and a slide shaft 44 that is fixed perpendicularly to the center of the disc 43, and the piston rod 26C of the upper piston 21 is hollow. The slide lid 42 is installed on the upper piston 21 so that the through-hole 39 is opened and closed by sliding the slide shaft 44 of the slide lid 42 within the piston rod 26 </ b> C of the upper piston 21.

  By installing the reflector lower shock absorber 15J below the reflector 9, the reflector 9 lands while being relaxed by the flow resistance of the upper piston 21 and the upper cylinder 20 when the reflector 9 is dropped. By sliding in the piston rod 26C, the slide lid 42 closes when the reflector 9 is dropped, and the impact force is dispersed as much as the relaxation of the upper piston 21, so that the reflector 9 is prevented from being damaged.

  Further, when the reflector 9 and the upper cylinder 20 float together, the slide lid 42 is opened and the upper piston 21 falls smoothly in the upper cylinder 20 as shown in FIG.

[Tenth embodiment]
Next, 10th Embodiment of the reflector control nuclear reactor which concerns on this invention is described based on FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-9th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 31 and 32, the reflector controlled nuclear reactor according to the tenth embodiment is formed such that the upper cylinder 20 is formed in a conical shape in the reflector controlled nuclear reactor 1 according to the first embodiment, and the upper piston 21 is disposed at the upper part. It is formed in a conical shape that is substantially similar to the shape of the upper portion of the cylinder 20.

  By installing the reflector lower shock absorber 15K below the reflector 9, when the reflector 9 falls, the upper cylinder 20A is placed on the ground while being relaxed by the flow resistance of the upper cylinder 20A and the upper piston 21B. Since it has a conical shape, the gap flow path becomes small just before landing, the fall speed is reduced, and the reflector 9 is prevented from being damaged.

  Further, as shown in FIGS. 33 and 34, the upper piston 21C may be formed so as to have a conical shape as a whole by laminating a plurality of discs 45 with gaps therebetween.

[Eleventh embodiment]
Next, an eleventh embodiment of a reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-10th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 35 and 36, the reflector controlled nuclear reactor according to the eleventh embodiment has a lower reflector 15 in the reflector controlled reactor 1 according to the first embodiment. A lower cylinder 46 and a lower piston 47 are provided.

  That is, the upper piston 21 and the lower piston 47 are provided at both ends of the piston rod 26. The upper piston 21 and the lower piston 47 slide freely in the upper cylinder 20 and the lower cylinder 46, respectively, and when the reflector 9 is landed, FIG. As shown, the upper cylinder 20 and the lower cylinder 46 are in contact with each other.

  By installing the reflector lower shock absorber 15L below the reflector 9, the reflector 9 falls while being relaxed by the flow resistance of the upper cylinder 20 and the upper piston 21 when the reflector 9 is dropped, but the upper cylinder 20 and the upper piston 21 are dropped. Since the lower cylinder 46 and the lower piston 47 exist, the impact is dispersed in four stages before landing, and the reflector 9 is prevented from being damaged.

  37 and 38, the piston rod 26D may be provided with a communication hole 48 along the axial direction so that the coolant sodium 5 flows inside the piston rod 26D. The reflector 9 is smoothly dropped by the communication hole 48.

[Twelfth embodiment]
Next, a twelfth embodiment of the reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-11th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 39 to 42, in the reflector controlled reactor of the twelfth embodiment, an inert gas 49 such as argon gas is enclosed in the upper cylinder 20 of the reflector controlled reactor 1 of the first embodiment. It is a thing.

  39 and 40 are views showing a reflector lower shock absorber 15M in which an inert gas 49 of about 60% of the volume in the upper cylinder 20 is sealed, and FIGS. 41 and 42 are inside the upper cylinder 20. FIG. It is a figure which shows the reflector lower buffer 15M filled with the inert gas 49. FIG.

  39 and 40, only the lower orifice is provided as an orifice in the upper cylinder 20 of the reflector lower shock absorber 15M, and the coolant sodium 5 flows into about 40% of the lower portion in the upper cylinder 20.

  By installing the reflector lower shock absorber 15M below the reflector 9, the reflector 9 falls while being relaxed by the flow resistance of the upper cylinder 20 and the upper piston 21 when the reflector 9 is dropped, but contains an inert gas 49. Therefore, the impact due to the compression of the gas is dispersed before landing, and the reflector 9 is prevented from being damaged.

  As shown in FIGS. 43 and 44, the upper cylinder 20 may be filled with an inert gas 49, and the gasket-like resistor 31 used in the third embodiment may be attached to the upper piston 21. The gasket-like resistor 31 generates a flow resistance to buffer the impact when the reflector 9 is dropped.

[Thirteenth embodiment]
Next, a thirteenth embodiment of a reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-12th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 45, the reflector controlled nuclear reactor according to the thirteenth embodiment is the reflector upper portion that buffers the impact applied to the reflector 9 when the reflector 9 falls in the reflector controlled nuclear reactor 1 according to the first embodiment. The shock absorber 50 is installed on top of the reflector 9.

  The reflector upper shock absorber 50 is provided with a suction plate 52 at the upper end of a drive shaft 51 that drives the reflector 9, and the upper piston 21 is housed on both sides of the suction plate 52 via a horizontal balance bar 53. The upper cylinder 20 is suspended. The position adjustment mechanism 11 is installed so as to be located above the liquid level S of the coolant sodium 5, and the reflector upper shock absorber 50 is installed below the position adjustment mechanism 11 and above the reflector 9.

  A landing foot 28 is provided at the lowermost portion of the piston rod 26 of the upper piston 21, and a landing base 54 for landing the landing foot 28 is installed above the liquid level S of the coolant 5. The landing base 54 is installed at a position where the landing foot 28 of the reflector upper shock absorber 50 should land when the reflector 9 falls.

  By installing the reflector upper shock absorber 50 on the drive shaft 51 of the reflector 9, the attracting plate 52 is separated from the position adjusting mechanism 11 and the reflector 9 falls when scramming the electromagnetic pump 14 or the like. After landing on the landing base 54, the landing foot 28 of the reflector lower shock absorber 15M falls while being relaxed by the gas or hydraulic flow resistance of the upper cylinder 20 and the upper piston 21. At this time, the reflector lower shock absorber 15 is further installed to disperse the impact and prevent the reflector 9 from being damaged.

  As the reflector upper shock absorber 50, a coil spring 55 may be used instead of the upper piston 21 and the upper cylinder 20, as shown in FIG. That is, the reflector upper shock absorber 50 constituted by the coil spring 55 may be provided on both sides of the balance bar 53.

  By installing the reflector upper shock absorber 50 on the drive shaft 51 of the reflector 9, the attracting plate 52 is disconnected from the position adjusting mechanism 11 and the reflector 9 falls when the electromagnetic pump 14 is scrammed, and the reflector 9 falls. The impact is dispersed by the coil spring 55 of the upper shock absorber 50, and the reflector 9 is prevented from being damaged.

  Furthermore, as shown in FIG. 47, the reflector upper shock absorber 50 may be configured by installing one coil spring 55 on the drive shaft 51 below the suction plate 52 of the drive shaft 51. At this time, the coil spring 55 of the reflector upper shock absorber 50 is installed so as to be coaxial with the drive shaft 51.

[Fourteenth embodiment]
Next, a fourteenth embodiment of a reflector controlled nuclear reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-13th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 48, the reflector controlled nuclear reactor according to the fourteenth embodiment is used when the reflector 9 and the drive shaft 51 collide with the position adjusting mechanism 11 due to fluid levitation when the reactor is started or when the reactor is restarted. In order to alleviate the impact force, a reflector floating time buffer device 56 composed of the upper piston 21 and the upper cylinder 20 is provided below the position adjusting mechanism 11.

  A landing foot 28 is provided at the lowermost portion of the piston rod 26 of the upper piston 21, and a suction plate 52 for landing the landing foot 28 is placed on the uppermost portion of the drive shaft 51 of the reflector 9. It is installed so as to be above the liquid level S. At this time, when the reflector 9 and the drive shaft 51 are floated by a fluid force, the suction plate 52 is installed so as to collide with the shock absorber 56 when the reflector floats.

  When the drive shaft 51 of the reflector 9 moves upward and is attracted by the floating fluid force at the time of activation, it floats and adsorbs while being relaxed by the gas or hydraulic flow resistance in the upper cylinder 20. The impact is dispersed, and the suction plate 52 and the position adjusting mechanism 11 above the drive shaft 51 are prevented from being damaged.

  49 shows the operation behavior of the reflector floating buffer device 56 when the reflector 9 floats, and FIG. 50 shows the behavior of the reflector float buffer device 56 when the reflector 9 is attracted.

  When the reflector 9 floats, the upper piston 21 is positioned in the lower part in the upper cylinder 20 integrated with the position adjusting mechanism 11. On the other hand, at the time of attracting the reflector 9, the attracting plate 52 of the drive shaft 51 is pushed upward by the fluid force floating of the reflector 9, and the upper piston 21 moves in the upper cylinder 20 and reaches the upper end of the upper cylinder 20.

  Since the shock absorber 56 at the time of reflection of the reflector is installed in the position adjustment mechanism 11, the impact is dispersed when the drive shaft 51 collides with the position adjustment mechanism 11 when the fluid force floats. Is prevented from being damaged.

  After the landing foot 28 and the suction plate 52 are attracted, the upper cylinder 20 and the upper piston 21 are configured to maintain the state at the time of adsorption with an electromagnet. Further, in a fluid force loss event such as when the electromagnetic pump 14 is tripped, the landing foot 28 is cut off by the suction plate 52 and the reflector 9 falls.

  Further, as shown in FIGS. 51 and 52, a gasket-like resistor 31 may be attached to the upper piston 21 shown in FIGS. 49 and 50.

[Fifteenth embodiment]
Next, a fifteenth embodiment of a reflector controlled reactor according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-14th Embodiment, and the overlapping description is abbreviate | omitted.

  The reflector controlled nuclear reactor according to the fifteenth embodiment is for mitigating the upper collision load when the reflector 9 and the drive shaft 51 collide with the position adjusting mechanism 11 due to fluid levitation when the reflector 9 is started or restarted. In addition, a control system for reducing the coolant flow rate is provided to reduce the impact load by reducing the fluid force levitation force between the time when the reflector 9 starts to float and then collides with the position adjusting mechanism 11. Is.

  FIG. 53 is a diagram showing an upper collision load characteristic of the reflector 9 in the reflector controlled nuclear reactor according to the fifteenth embodiment. FIG. 54 is a diagram showing an upper collision load characteristic when the reflector 9 collides with the position adjusting mechanism 11 when the flow rate is not decreased when the reflector 9 is floated by the fluid force.

  The upper collision load characteristic of the reflector 9 of the reflector controlled nuclear reactor according to the fifteenth embodiment will be described with reference to FIGS. 53 and 54.

  As shown in FIG. 54, when the coolant flow rate increases and reaches the reflector floating flow rate QU0, the reflector 9 begins to float. When the coolant flow rate is kept above a certain level, the reflector 9 continues to float by the fluid force, and collides with the position adjusting mechanism 11. The upper collision load FU1 at this time shows a spike-like peak.

  In the reflector controlled reactor 1Q, as shown in FIG. 53, when the reflector 9 starts to rise, the coolant flow rate is reduced by 5 to 10% and maintained at the reduced control flow rate QU1. At this time, the reflector 9 continues to float by the inertia force and collides with the position adjusting mechanism 11.

This collision load greatly depends on the flow rate, and becomes the upper collision load FU2 at the decrease control flow rate QU1.
When comparing FU1 and FU2, [Equation 1]
FU1> FU2
It can be seen that the upper collision load is relaxed.

  According to the fifteenth embodiment, by reducing the coolant flow rate when the reflector 9 floats, the collision between the position adjustment mechanism 11 and the suction plate 52 of the drive shaft 51 can be mitigated and damage can be prevented.

[Sixteenth Embodiment]
Next, a sixteenth embodiment of a reflector controlled reactor according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment-15th Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 55, the reflector controlled nuclear reactor according to the sixteenth embodiment is used to balance the reflector 9 in the reflector controlled nuclear reactor 1 according to the first embodiment instead of floating and dropping the reflector 9 by fluid force. The reflector upper shock absorber 50A using the counterweight 57 which is a weight of the above is provided.

  That is, the reflector upper shock absorber 50A includes a connecting shaft 58 that connects the reflector 9 and the position adjusting mechanism 11, and the counterweight 57 and the position adjusting mechanism 11 are connected by the connecting wire 60 via the pulley 59. The counterweight 57 plays an auxiliary role of the position adjustment mechanism 11 that adjusts the vertical position of the reflector 9. The reflector controlled nuclear reactor according to the sixteenth embodiment is suitable when the fluid power of the coolant sodium 5 is small.

  In the sixteenth embodiment, in order to drop the reflector 9 in the event of an abnormality, the reflector 9 and the counterweight 57 are separated by the abnormality separation device 61, and the neutron n released from the core 4 by dropping the reflector 9 by gravity is removed. By making the shield 13 absorb, the passive furnace output is stopped.

  Furthermore, the present invention is not limited to the embodiments described above, and can be implemented in various modifications without departing from the spirit of the present invention by combining the examples of the present invention. .

The block diagram of 1st Embodiment of the reflector control reactor which concerns on this invention. The top view of the reflector of the reflector control nuclear reactor of 1st Embodiment. The principle figure of the neutron control of the reflector control nuclear reactor of 1st Embodiment. The reflector sectional view at the time of reflector floating of the reflector control nuclear reactor of a 1st embodiment. The reflector sectional view at the time of reflector fall of the reflector control nuclear reactor of a 1st embodiment. The expanded block diagram which shows the reflector flow path of the reflector control nuclear reactor of 1st Embodiment. The bottom view of the reflector floating mechanism of the reflector control nuclear reactor of 1st Embodiment. The enlarged block diagram which shows the reflector floating time of the reflector lower shock absorber of the reflector control nuclear reactor of 1st Embodiment. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of the reflector control reactor of 1st Embodiment. The graph which shows the reflector lower part buffer load in the reflector control nuclear reactor of 1st Embodiment. The expanded block diagram which shows the reflector lower shock absorber of 2nd Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 2nd Embodiment. The expanded block diagram which shows the reflector lower shock absorber of 3rd Embodiment of the reflector control nuclear reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 3rd Embodiment. The expanded block diagram which shows the gasket-like resistor of the reflector control nuclear reactor of 3rd Embodiment. The expanded block diagram which shows the reflector lower shock absorber of 4th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 4th Embodiment. The expanded block diagram which shows the time of reflector landing of the reflector lower shock absorber of 5th Embodiment of the reflector control reactor which concerns on this invention. The expansion block diagram which shows the time of reflector landing of the reflector lower shock absorber of the reflector control reactor of 5th Embodiment. The graph which shows the reflector lower part buffer load in the reflector control nuclear reactor of 5th Embodiment. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 5th Embodiment. The expanded block diagram which shows the reflector lower buffer apparatus of 6th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of 7th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 7th Embodiment. The expanded block diagram which shows the reflector lower shock absorber of 8th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector lower shock absorber of the reflector control nuclear reactor of 8th Embodiment. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of 9th Embodiment of the reflector control reactor which concerns on this invention. The expansion block diagram which shows the time of reflector floating of the reflector lower buffer of the reflector control reactor of 9th Embodiment. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of the reflector control reactor of 9th Embodiment. The expansion block diagram which shows the time of reflector floating of the reflector lower buffer of the reflector control reactor of 9th Embodiment. The expansion block diagram which shows the reflector floating time of the reflector lower buffer apparatus of 10th Embodiment of the reflector control reactor which concerns on this invention. The expansion block diagram which shows the time of reflector landing of the reflector lower shock absorber of the reflector control reactor of 10th Embodiment. The expansion block diagram which shows the reflector floating time of the reflector lower buffer of the reflector control nuclear reactor of 10th Embodiment. The expansion block diagram which shows the time of reflector landing of the reflector lower shock absorber of the reflector control reactor of 10th Embodiment. The reflector lower buffer of 11th Embodiment of the reflector control nuclear reactor which concerns on this invention is also an enlarged block diagram which shows the time of reflector floating. The reflector lower part buffer of the reflector control reactor of 11th Embodiment is also an enlarged block diagram which shows the time of reflector landing. The reflector lower part buffer apparatus of the reflector control reactor of 11th Embodiment is also an enlarged block diagram which shows the reflector floating time. The reflector lower part buffer of the reflector control reactor of 11th Embodiment is also an enlarged block diagram which shows the time of reflector landing. The expansion block diagram which shows the reflector floating time of the reflector lower buffer apparatus of 12th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of the reflector control reactor of 12th Embodiment. The expanded block diagram which shows the time of reflector floating of the reflector lower buffer of the reflector control reactor of 12th Embodiment. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of the reflector control reactor of 12th Embodiment. The expanded block diagram which shows the time of reflector floating of the reflector lower buffer of the reflector control reactor of 12th Embodiment. The expanded block diagram which shows the time of the reflector fall of the reflector lower shock absorber of the reflector control reactor of 12th Embodiment. The expanded block diagram which shows the reflector upper shock absorber of 13th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector upper shock absorber of the reflector control nuclear reactor of 13th Embodiment. The expanded block diagram which shows the reflector upper shock absorber of the reflector control nuclear reactor of 13th Embodiment. The expanded block diagram which shows the reflector upper shock absorber of 14th Embodiment of the reflector control reactor which concerns on this invention. The expanded block diagram which shows the reflector floating time of the reflector upper buffer of the reflector control reactor of 14th Embodiment. The expanded block diagram which shows the time of reflector adsorption | suction of the reflector upper shock absorber of the reflector control reactor of 14th Embodiment. The expanded block diagram which shows the reflector floating time of the reflector upper buffer of the reflector control reactor of 14th Embodiment. The expanded block diagram which shows the time of reflector adsorption | suction of the reflector upper shock absorber of the reflector control reactor of 14th Embodiment. The graph which shows the reflector upper buffer load in 15th Embodiment of the reflector control reactor which concerns on this invention. The graph for comparing with FIG. The expanded block diagram which shows the reflector upper shock absorber of 16th Embodiment of the reflector control reactor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reflector control reactor 2 Reactor vessel 3 Fuel assembly storage area 4 Core 5 Coolant sodium 6 Upper plenum 7 Lower plenum 8 Core barrel 9 Reflector 10 Reflector block 11 Position adjustment mechanism 12 Bulkhead 13 Shield 14 Electromagnetic pump 15 , 15A to M Reflector lower shock absorber 16 Sector wall 17 Cavity 18 Reflector levitation mechanism 19 Universal joint 20, 20A Upper cylinder 21, 21A to C, 21F Upper piston 22 Upper lid 23 Lower lid 24 Upper orifice 25 Lower orifice 26, 26A ˜D Piston rod 27 Lower stopper 28 Landing foot 29 Intermediate orifice 30 Angle labyrinth 31 Gasket-like resistor 32 Notch 33 Coil spring 34 Gas vent 35 Disc 36 Inner cylinder 37 Through hole 38 Resistor 39 Through hole 40 Rotating lid 41 Hinge joint 42 Slide lid 43 Disc 4 4 Slide shaft 45 Disc 46 Lower cylinder 47 Lower piston 48 Communication hole 49 Inert gas 50, 50A Reflector upper shock absorber 51 Drive shaft 52 Adsorption plate 53 Balance rod 54 Landing base 55 Coil spring 56 Reflector floating shock absorber 57 Counterweight 58 connecting shaft 59 pulley 60 connecting wire 61 disconnecting device A in case of abnormality reflector lifting region R1 core channel R2 reflector channel S coolant level n neutron

Claims (17)

A reactor core, a shield that surrounds the reactor core and shields neutrons emitted from the reactor core, a reflector that reflects neutrons between the reactor core and the shield, and an axis of the reflector relative to the reactor core In a reflector-controlled nuclear reactor equipped with a position adjustment mechanism that finely adjusts the directional position and a reactor vessel containing these,
A levitation mechanism provided below the reflector and levitating the reflector with a coolant;
A shock absorber including a piston and a cylinder for buffering the reflector when it falls by gravity during the reflector pump trip;
A reflector-controlled nuclear reactor comprising:   The reflector controlled nuclear reactor according to claim 1, wherein the cylinder is provided with a plurality of orifices separated from each other in the axial direction.   The reflector controlled nuclear reactor according to claim 1, wherein a plurality of chevron labyrinths are provided on an outer peripheral side surface of the piston of the shock absorber.   The reflector controlled nuclear reactor according to claim 1, wherein a coil spring is provided on a piston rod of a piston of the shock absorber, and a collision between the piston and the cylinder bottom surface in the cylinder is buffered.   2. The reflector controlled nuclear reactor according to claim 1, wherein the shock absorber includes a plurality of pairs of pistons and cylinders, and the piston rods of the pistons have different lengths.   2. The reflector-controlled nuclear reactor according to claim 1, wherein the piston of the shock absorber is formed in a cylindrical shape as a whole by laminating a plurality of discs with a gap therebetween.   The reflector controlled nuclear reactor according to claim 1, wherein the piston of the shock absorber is housed in an internal cylinder, and the internal cylinder is further housed in the cylinder.   The reflector controlled nuclear reactor according to claim 1, wherein a piston of the shock absorber is formed in a bag shape opened at an upper portion.   The reflector controlled nuclear reactor according to claim 1, wherein a through-hole penetrating in the axial direction is provided in the piston of the shock absorber, and a lid for opening and closing the through-hole is provided.   The reflector controlled nuclear reactor according to claim 1, wherein the piston and the cylinder of the shock absorber are formed in a conical shape, and the piston is fitted into an upper portion of the cylinder.   The reflector controlled nuclear reactor according to claim 1, wherein a lower piston is provided below a piston rod of a piston of the shock absorber, and the lower piston is contained in a lower cylinder.   The reflector controlled nuclear reactor according to claim 1, wherein an inert gas is filled in a cylinder of the shock absorber. A core, a shield that is installed so as to surround the core in the circumferential direction and shields neutrons emitted from the core, a reflector that reflects neutrons emitted from the core between the core and the shield, and the reflector In a reflector-controlled nuclear reactor equipped with a position adjustment mechanism for finely adjusting the axial position of the core of the reactor and a reactor vessel containing these,
The reflector is floated by the fluid force of the coolant, and a suction plate detachably attached to the position adjusting mechanism is provided at the upper end of the drive shaft to which the reflector is fixed. This suction plate collides with the position adjustment mechanism when it floats by the fluid force of
A reflector-controlled nuclear reactor comprising a shock absorber for buffering an impact force at the time of a collision between the suction plate and the position adjusting mechanism.   The reflector controlled nuclear reactor according to claim 13, wherein the shock absorber includes a piston and a cylinder.   The reflector-controlled nuclear reactor according to claim 13, wherein the flow rate of the coolant is reduced until the reflector and the drive shaft rise and the suction plate and the drive device collide. A core, a shield that is installed so as to surround the core in the circumferential direction and shields neutrons emitted from the core, a reflector that reflects neutrons emitted from the core between the core and the shield, and the reflector In a reflector-controlled nuclear reactor equipped with a position adjustment mechanism for finely adjusting the axial position of the core of the reactor and a reactor vessel containing these,
A counterweight that is connected to the reflector by a connecting wire via a connecting shaft and a pulley, and adjusts the vertical position of the reflector during reactor operation,
An abnormal-time disconnecting device that separates the reflector from the counterweight and drops it when a nuclear reactor malfunctions;
A reflector-controlled nuclear reactor comprising a shock absorber that cushions the impact of the reflector when the reflector falls. A core, a shield that shields neutrons emitted from the core installed to surround the core in the circumferential direction, a reflector that reflects neutrons between the core and the shield, and an axial direction of the reflector with respect to the core In the output control method of the reflector-controlled nuclear reactor provided with a position adjustment mechanism for finely adjusting the position and a reactor vessel containing these,
A reflector levitation step of levitating the reflector with a coolant using a levitation mechanism;
A reflector buffering step of buffering the reflector using a shock absorber including a piston and a cylinder when the reflector is dropped by gravity during a pump trip;
A power control method for a reflector-controlled nuclear reactor, comprising:

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