JPS61178691A - Liquid metal cooling type reactor - 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 reactor upper structure of a liquid metal cooled nuclear reactor that closes the upper opening of a special C double reactor vessel. [Technical background of the invention and its problems] In a liquid metal cooled nuclear reactor, the liquid metal must not come into contact with air, so the upper opening of the reactor vessel is closed with a flexible plug and the liquid metal level is is covered with inert gas.Therefore, a shield plug (:) is required to have heat and radiation shielding functions, coolant cover gas boundary functions, and retaining functions for equipment mounted on the tower. Among the functions, the heat shield function is a function that reduces the amount of heat radiated from the reactor and keeps the upper surface of the heat shield plug at a low temperature. Plug interior C: Various types of heat insulating materials can be installed to forcefully cool the inside of the plug, or a medium heat shielding plate of C1 to 2 below the plug can be suspended from the plug. structure was adopted.

However, since the cover gas is suspended from the heat shield plate from the heat shield plate, the cover gas is suspended between the fixed plug and the rotating plug, between the 9-rotation plugs, or between the flexible plug and the reactor vessel. It was necessary to create a split structure for the medium heat shield plate. When the cover gas heat shield plates are divided, a gap 6 exists between the cover gas heat shield plates.

However, above such a gap (Y is between the stationary plug and the rotating plug, 9 between the rotating plugs, and between the flexible plug and the reactor vessel, there are two annular gaps. As shown in Figure 4, schematic diagram C: Natural convection consisting of upward flow and downward flow occurs, resulting in uneven temperature distribution in the circumferential direction of the furnace vessel. A large temperature difference occurs in the circumferential direction, causing natural convection in the circumferential direction, which adds thermal stress to the furnace vessel and the heat plug, causing their deformation.
Nuclear products in the cover gas rise through the annular gap due to natural convection, causing problems such as the formation of areas with locally high radiation dose rates in the upper part of the plug. Moreover, since the gap between the heat shield plates in the cover gas is located directly below the annular gap, the natural convection in the circumferential direction does not occur only in the annular gap, but from the coolant liquid level to the annular gap. Therefore, there is a possibility that the run-up section of circumferential natural convection will be promoted. There is a possibility that it will be encouraged.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to reduce the initial distance of natural convection that occurs in the cover gas space! It is possible to provide a liquid metal cooled nuclear reactor that is shortened and the heat shielding function of the cooling plug is improved by reducing the occurrence of large circumferential temperature differences.

[Summary of the Invention] In order to achieve the above objects, the present invention includes a reactor vessel, a shield plug that closes an opening of the reactor vessel, and a lower part of the shield plug. Hanging tool 6 thrown on the plug; Therefore, the annular gap that exists between the cover gas heat shield plate supported and fixed and the shield plug and the reactor vessel; Below the annular gap and between the heat shield plates in the cover gas or between the heat shield plates in the cover gas and the reactor vessel C: A liquid metal cooled atom comprising a partition plate that covers the existing gap. It is related to furnaces.

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

FIG. 1 shows a schematic sectional view of an embodiment of the present invention. As shown in FIG. , this shielding plug 2 is composed of a fixed plug 3 and a rotating plug 4 which is disposed in a spaced relation to the fixed plug 3C and supports the upper core mechanism 5. C so that the coolant 6 has a predetermined depth and forms a free liquid level.
:The space above the free liquid level is filled with an inert gas such as argon gas. Therefore, the upper plenum space of the reactor vessel 1 is filled with a gas (hereinafter referred to as cover gas) 7 which is mainly composed of active gas and contains liquid metal coolant mist, steam, and these radioactive substances. In addition, a large number of thin plates 8 of the thin plug 2ri are laminated, and a heat shield layer 9 is set between them (2) to fill the cover gas and maintain a certain distance to prevent convection; A radiation shield 11 that is split into two parts in the upper part C, and a ninth cooling layer 11 that forcibly introduces an external cooling gas (to maintain a low temperature of 0°C to approximately 70°C) on the upper surface of the shield plug. It consists of an upper plate 12 having rigidity to reduce the amount of deflection due to the total load of the Yahei plug main body and the installed equipment, and a Yahei shell 13 arranged around it. Then, the arrangement relationship σ diagram of the heat shielding layer 9, the radiation shielding body 1O, and the cooling layer 11 (: There is no need to limit the arrangement only to the one shown.Furthermore, between the fixed plug 3 and the rotating plug 4! - is formed with an annular gap 14, and the upper part of this annular gap 14, the upper surface C of the seal plug;
is installed. In addition, fixed plug 3 and rotating plug 4
A heat shielding plate 16 in the cover gas is supported from the bottom surface of each plug by a hanging tool such as a hanging rod or a hanging pipe. The lower surface of the cover gas has a C2 structure so as to cover the entire surface C.By the way, the heat shielding plate 16 in the cover gas is divided below the annular gap 14, and the gap 17 created here is cut out. A C-shaped partition plate structure 18 is adopted.

Next, the details of the partition structure 18 will be explained with reference to FIG.

As is clear from Fig. 2, the C1 partition plate isa, 18b
are welded (not shown) to cover gas heat shield plates 16m-1 and 16b-1 on the fixed plug 3 side, respectively, but the axial directions of the partition plates 18a and 18b are shifted from each other. Then, bellows 191.19b are attached to the tips of the partition plates 18a and 18b (each of the two halves are o -1
9a.

The upper end of 19b is configured to be in contact with the heat shield plate 161-2.16b-2C in the cover gas on the side of the rotating plug 4, so that
8b and cover gas medium heat shield plate 16Jl-2, 16b
C: Closing the gaps 20a and 20b created by -2. The natural length of the bellows 198.19b is the same as the heat shielding plates 16m-2, 16b-2 and the partition plate 18 in the cover gas even when the rotating plug 4 is jacked up.
&, 18b gap 20m.

Use one that has a length such that 20b is covered.

Furthermore, since the inner diameters of the partition plates 18a and 18b are made larger as they move upward, the rotary plug 4''4r has a structure that allows it to be carried into the fixed plug 3 from above.

In addition, in FIG. 1, the gap between the reactor vessel 1 and the heat shielding plate 16 in the cover gas is covered by a partition plate structure 18 in which a partition plate 17 is welded to the inner wall of the reactor vessel 1. The only difference is that the other structure is the same as the partition plate structure as shown in Fig. 2.Furthermore, C: If the heat shielding plate 16 in the cover gas is divided at a place other than the above and there is a gap, then Station - A partition plate structure similar to that shown in Figure 2 shall be installed.

In the above embodiment, the partition plates 18a and 18b, the heat shield plates 16m-1 and 16b-1 in the cover gas, and the partition plate 18a.

18b and the reactor vessel 1 are attached and fixed by welding (y), but the welding is not limited to this type of welding.
For example, it can be fixed by bolting or by bolting.

FIG. 3 shows only the structure of the partition plate according to another embodiment of the present invention.
(not shown), and the other end of the partition plate 18C and the cover gas heat shielding plate 16C-2 on the rotary plug side are arranged with a gap 20C formed above and below, but even with such a structure, The upward flow and downward flow of the cover gas (the pressure drop between the two increases, and so on.

Since it also has the function of covering the gap between the heat shield plates in the cover gas provided in the reactor vessel, the same effect as in the above embodiment can be obtained. Since the cover gas space is completely divided at the level of the heat shield plate, the run-up section of natural convection in the circumferential direction and axial direction of the cover gas is shortened, and heat transfer accompanying natural convection can be reduced. As a result, the thermal shielding function is improved, the temperature difference in the circumferential direction of the reactor vessel and the shield plug is reduced, and the thermal stress and thermal deformation caused by these seas are significantly reduced (
: Relaxed. (9) Since the rise of nuclear products in the cover gas into the annular gap due to natural convection is reduced, the radiation shielding function of the shielding plug is improved. Now 1;,
Since the gap between the heat shield plate and the cover gas is closed,
Radiant heat from the coolant liquid upwards is suppressed, improving the heat shielding function of the coolant plug, and preventing the rise of coolant metal mist and vapor.
This has the effect of preventing objects, such as bolts, from falling from the reactor upper structure (inside the reactor).

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of one embodiment of the present invention, FIG. 2 is a detailed sectional view of the partition plate structure of FIG. 1, and FIG. 3 is a detailed diagram of the partition plate structure of another embodiment of the present invention. Fig. 4 is a diagram for explaining the natural convection in the circumferential direction in the annular gap that exists between the reactor vessel and the sealing plug. 1... Reactor vessel 3... Fixed plug 4...
Rotating plug 5... Core upper mechanism 6... Liquid metal coolant 9... Thermal shield layer lO... Radiation shield body l]... Cooling layer 13... Shield body
14... Annular gap 16... Cover gas heat shield plate 18... Partition plate structure Agent Patent attorney Yoshiaki Inomata (and 1 other person) No. 1
figure

Claims (4)

[Claims] (1) A reactor vessel, a shield plug that closes the opening of the reactor vessel, and a suspension plug that is supported and fixed below the shield plug by a hanging device provided on the shield plug. An annular gap existing between a heat shield plate in the cover gas and between the heat shield plugs or between the heat shield plug and the reactor vessel, and a heat shield in the cover gas below the annular gap. A liquid metal cooled nuclear reactor comprising a partition plate that covers a gap that exists between the cover gas or between the cover gas and the reactor vessel. (2) The liquid metal cooled nuclear reactor according to claim 1, wherein at least one heat shielding plate is provided in the cover gas. (3) The liquid metal cooled nuclear reactor according to claim 1, wherein the mounting positions of the partition plates are staggered. (4) The liquid metal cooled nuclear reactor according to claim 1, wherein one end of the partition plate is fixed to the cover gas heating plate, and the other end is attached to a retractable plate such as a bellows.