JPS63246699A - Support structure of nuclear-reactor in-core structure - 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 [Objective of the Invention] (Industrial Field of Application) The present invention uses a liquid metal as a coolant, and a structure in which reactor internals are suspended and supported in the coolant in a reactor vessel. The present invention relates to a support structure for internal reactor structures in a nuclear reactor.

(Prior Art) Nuclear reactors, such as fast breeder reactors, generally use liquid metal, typified by liquid metal sodium, as a coolant, and are operated at higher temperatures than light water reactors. In such a fast breeder reactor, the reactor main vessel is used at the time of starting or stopping the reactor operation.

In order to prevent core equipment, piping, etc. from being damaged by thermal stress, a method is usually adopted to reduce the thickness of these structural members.

In addition, in order to make the overall structure of such a fast breeder reactor simple, a nuclear reactor that eliminates piping as much as possible, that is, a reactor that exchanges heat between the primary coolant and the secondary coolant. A so-called tank-type reactor structure is being considered, in which an intermediate heat exchanger and a coolant circulation pump are installed inside the main reactor vessel. The upper opening in the figure of the JM child reactor main vessel 1 is closed with a roof slab 2, and the reactor core 3, core upper mechanism 4, intermediate heat exchanger 5, coolant circulation pump 6, and coolant 7 are housed inside. The core 3 is housed at the lower end in the figure of a core support member 8 suspended from the roof slab 2, and the core upper mechanism 4 is rotatably mounted above the core support member 8. The reactor main vessel is supported by a rotary plug 9 provided therein.The reactor main vessel is suspended in the reactor chamber 11 via a ring garter lO, and the reactor main vessel
There is a safety vessel 1 on the outside of the reactor so as to cover this reactor main vessel 1.
2 is provided.

By adopting such a tank-type nuclear reactor structure, piping for the secondary heat exchange system and coolant circulation system can be eliminated.

(Problems to be Solved by the Invention) However, even in a nuclear reactor that employs such a tank-type reactor structure, the following problems are expected. That is, the core support member 8. The intermediate heat exchanger 5, circulation pump 6, etc. are formed with relatively thin walls in view of thermal stress, and are supported by the roof slab 2 to absorb the large amount of thermal expansion that occurs when the reactor is enlarged. It has a cantilever structure suspended within the main container 1. Therefore, when an external impact input or vibration input is applied, large vibrations are generated in them, and a portion may be damaged due to an increase in local stress due to the deformation, so some countermeasure is desired.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide no restraints to slow deformation such as thermal expansion, and to improve the structure of reactor internals during earthquakes. Horizontal shaking can be reliably suppressed,
An object of the present invention is to provide a support structure for internal structures of a nuclear reactor, which can improve the health of the entire reactor during an earthquake or the like.

[Structure of the invention]

(Means for Solving the Problems) The present invention uses liquid metal as a coolant, and the reactor internals such as the core intermediate heat exchanger or the circulation pump are suspended and supported in the coolant in the reactor vessel. In a nuclear reactor,
A cylindrical member provided to cover the side surface of the reactor internal structure through a fluid gap, a member that fixes this cylindrical member to the reactor vessel, and either the outer periphery of the reactor internal structure or the inner periphery of the cylindrical member. an annular member housed in a groove provided on one side;
It is characterized in that a protrusion is formed on either the annular member, the surface of the cylindrical member in contact with the annular member, or the surface of the furnace internal structure.

(Function) During an earthquake, if the reactor internals move relative to the reactor main vessel, there will be a gap between the cylindrical member fixed to the 1M sub-reactor main vessel and the reactor internals. Relative displacement occurs, creating a large pressure difference in the fluid gap, which acts as a low drag on the relative movement of the reactor internals.

Incidentally, the resistance force that an object receives from the surrounding fluid generally includes a force proportional to the acceleration of the object and a force proportional to the speed (or the square of the speed) of the object. The force proportional to acceleration becomes larger as the leakage of fluid in the vertical direction from the fluid gap becomes smaller, but the force proportional to velocity becomes extremely large when the leakage in the vertical direction becomes small to a certain extent, and then It has the property that when the leakage becomes smaller, the leakage becomes smaller.

In the present invention, the annular member prevents fluid leakage, but this can be prevented by providing a protrusion on either the annular member, the surface of the cylindrical member that is in contact with it, or the surface of the reactor internal structure. Since this prevents the parts from coming into close contact with each other, the resistance to vibration of the reactor internals can be controlled to the maximum. Therefore, according to the support structure for nuclear reactor internals according to the present invention, vibrations of the reactor internals can be efficiently suppressed without generating thermal stress.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. FIG. A cylindrical member 14 is fixed to the main vessel 1 by a support plate 15 via a fluid gap 13 filled with coolant around the core support member 8 . An L-shaped groove is cut in the inner periphery near the upper and lower ends of the cylindrical member, and a ring 16 having a rectangular cross section is accommodated in this groove.

FIG. 2 is an enlarged sectional view of the ring 16 and its vicinity. The above-mentioned ring has protrusions 17 of very small height arranged on the upper surface, lower surface, and inner circumferential surface of the ring. A container 18 is formed.

According to this support structure, leakage of fluid from the fluid gap can be controlled to an optimum amount, and vibration of the reactor internal structure can be suppressed to the maximum without generating thermal stress.

〔Effect of the invention〕

According to the support structure of the reactor internal structure of the present invention, the support effect can be greatly increased by dissipating fluid leakage from the fluid gap, and the thermal stress seen in mechanical support can be greatly increased. There has been no occurrence of

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a nuclear reactor that employs the support structure for reactor internals according to the present invention, Figure 2 is an enlarged cross-sectional +f+r diagram showing the ring and its vicinity in Figure 1, and Figure 3 is a conventional atomic reactor. FIG. 3 is a cross-sectional view of the furnace. 1... Reactor main vessel 12... Safety vessel 2.
...Roof slab 13...Fluid gap 3.
...Core 14...Cylindrical member 4...
Core upper mechanism 15...Support plate 5...Intermediate heat exchanger 16...Link 6...Circulation pump
17...Protrusion part 7...Cooling material
18...Minute flow passage 8...Core 9...Core support member 10...Ring gutter 11...Reactor room representative Patent attorney Noriyuki Chika, -

Claims (1)

[Claims] In a nuclear reactor in which a liquid metal is used as a coolant and reactor internals such as a core, an intermediate heat exchanger, and a circulation pump are suspended and supported in the coolant in the reactor vessel, the side surfaces of the reactor internals and A cylindrical member whose side surfaces are arranged to face each other across a fluid gap, a member for fixing the cylindrical member to the reactor vessel, and an annular member housed in a groove provided in one of the side surfaces. a member, on the other side;
A support structure for a nuclear reactor internal structure, characterized in that a protrusion that engages with the groove is formed.