JPS5946592A - Thermal shielding device of reactor container - 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 heat insulating device capable of alleviating thermal deformation and thermal stress of a nuclear reactor vessel, and is particularly applicable to a reactor vessel of a liquid metal cooled fast breeder reactor. The present invention relates to a heat insulating device suitable for.

[Technical background of the invention]

Conventionally, liquid metal cooled fast breeder reactor (hereinafter referred to as fast reactor)
The area near the liquid level of the reactor vessel has a surface structure as shown in Figure 1, for example, and a seven-lung structure lid, that is, a shielding plug, is provided at the top of the reactor vessel to shield radiation and heat. stone.

Generally, the temperature of the liquid metal (liquid sodium) contained in the reactor vessel l of a fast reactor is about 4tOθ! fO'C
Since the temperature of the upper surface of the shielding plug is around room temperature, a temperature difference of approximately WOO to ZOO'a occurs between the free liquid surface 3 of the liquid metal and the upper surface of the shielding plug. Therefore, it is necessary to keep the temperature gradient of the furnace vessel wall between the shielding hole and the upper part of the furnace vessel at a gentle and low temperature to prevent thermal deformation due to thermal creep occurring in the furnace vessel wall.

Therefore, conventionally, as shown in FIG. 1, a part of the liquid flowing from the inlet pipe of the reactor vessel through the reactor core 5 to the outlet pipe 6 is transferred between the reactor vessel and a cylindrical liner 7 provided inside the reactor vessel. A method is adopted in which the temperature of the inner wall of the furnace vessel is maintained at a relatively low temperature.

[Problems with background technology]

However, in this method, the high-temperature liquid on the core j side heats the liquid passing through the annular channel l via the linac, so the temperature difference between the two becomes smaller as it moves upwards in the reactor vessel, and a high relaxation effect cannot be expected. I can't come.

Also, in the reactor vessel/improvement section, the reactor core! The high-temperature liquid metal heated by the linac and the low-temperature liquid metal that cooled the furnace vessel/inner wall mix and come into contact with each other, causing thermal fatigue, and large temperature differences between the inside and outside of the linac, resulting in large thermal stress. There is also the problem that thermal deformation is likely to occur due to thermal deformation, and there is also the problem that during thermal transients such as pump trips, rapid temperature changes are transmitted to the furnace vessel, making it easy to receive thermal stress similar to thermal shock.

[Purpose of the invention]

The present invention was made in view of the current situation, and is an atom that can reliably and effectively alleviate thermal stress and thermal deformation of the container by keeping the inner wall temperature of the container low and making the temperature gradient near the liquid surface gentle. The purpose of the present invention is to provide a heat insulating device for a furnace vessel.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a plate-shaped insulating box in which a plurality of thin box-shaped insulating elements are housed and filled with gas on the outer peripheral surface of the liner at required intervals in the circumferential direction and the vertical direction. A large number of heat insulating elements are arranged, the inside of the heat insulating element is reinforced with a reinforcing member, and gas is sealed.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in Figs. 1 to 7. In Fig. 1, lI is a reactor vessel of a fast reactor, and this (3) A shielding plug/2 is airtightly installed via an O-ring 13. Also, the furnace vessel
A support structure /4 (not shown) that supports and mounts the reactor core is disposed at a lower position within the reactor vessel /l, and is directly connected to the reactor vessel /l. As shown in the figure, a cylindrical liner IS having a communication hole /A for liquid metal (liquid sodium) is installed at the lower end, and this liner /j is connected to the cover gas above the free liquid level /7 of the liquid metal. It extends to space/g.

As shown in Fig. 2, on the outer circumferential surface of this liner/S, there is a thin box-shaped heat insulating structure/? is 0.3 of the length of one side
A large number of stud units 6 are installed in the circumferential direction and the vertical direction while maintaining a gap J of about 1 to 1 inch. The said heat insulating structure /9 has a donut corner with the central part left as shown in FIG. It has a plate-shaped sealed box structure, and inside the box, a plurality of thin box-shaped heat insulating elements are housed inside and an inert gas is sealed. In addition, in the center of the heat insulating structure /9, two connecting plates with holes in the center are fixed by welding, etc., and the liner /r position corresponding to the connecting plate 2'l is fixed. As shown in FIG. 3, a stud roller is protruded through the hole and has a male thread at its tip. And the heat insulating structure /9 is liner /! as shown in Fig. 3. r
The connector plate is screwed onto the male screw 17 with a spacer λg interposed between the connecting plate and the connecting plate. is fixed to the liner 15 at one point. In this case, hole! 5 and by making the stud rollers non-circular, etc., to create a heat-insulating structure/? It is preferable to take into consideration the possibility that the stud will rotate against the stud roller. Further, it is preferable that the stud 2A and the nut 29 be fixed by welding or the like after tightening.

The heat insulating element a is a heat insulating structure/a as shown in FIG.
Similar to D, it has a sealed box structure, and an inert gas 3θ is sealed inside. Also, inside the heat insulating element 22, there is a concave-convex plate with many protrusions as shown in FIG. 7(a). 3
/a or as shown in (1) of the same figure, a reinforcing member 3/ consisting of a surface wave plate J/b etc. is installed inside.

This reinforcing member 3/ is fixed to the surface of the heat insulating element n with the largest area by spot welding or the like. In addition, remaining parts 3/
is not limited to the uneven plate 3/a, corrugated plate, or 7/b, but may also be a honeycomb structure, a grid-shaped lattice body, or the like.

Next, the operation of this embodiment will be explained.

The liquid metal with a free liquid level /7 in the furnace vessel 11 is kept at a high temperature, usually between 50 and szo'O.

However, since the inside of the furnace vessel 7 is lined with a heat insulating structure /9 attached to the liner /S, the wall of the furnace vessel is protected by the heat insulating structure /1, and is kept at a lower temperature. Ru. As a result, it is possible to reduce the thermal stress and thermal deformation occurring between the room-temperature upper surface of the shielding plug 12 and the vicinity of the free liquid level /7. Furthermore, it is possible to protect against sudden temperature changes during temperature rise, stoppage, pump trip, etc., and effectively prevent the occurrence of sudden thermal stress.

In addition, the heat insulating structure /9 has a sufficient heat insulating effect due to the heat insulating effect due to the inert gas 23 with low thermal conductivity inserted into the inside and the radiant heat blocking effect of the multilayer heat insulating element 2.2. Moreover, it is highly reliable.

That is, since the heat insulating element 2 includes the reinforcing member 3/ fixed therein by spot welding or the like, it hardly deforms even if a pressure change occurs outside.

Therefore, even if a crack occurs in the heat insulating structure /q and liquid metal infiltrates, there is almost no possibility that a crack will occur in the heat insulating element 22, thereby effectively preventing the deterioration of the heat insulating performance.

Here, if the probability of damage to the heat insulating structure is P and the probability of damage to the internal heat insulating element is Pl, the probability pb that the heat insulation performance will deteriorate is as follows.

The value is extremely small, resulting in a highly reliable heat insulating structure.

Is it a trench or an insulated structure? Is the stud roller part - the liner at the tube place/! r, and a certain gap m is formed between the adjacent heat insulating structure /9. Therefore, thermal expansion of the heat insulating structure /q becomes free, and there is no risk of undue thermal stress occurring. FIG. 5 shows another embodiment of the present invention.
and insulation structures/? It has a multilayer structure in the radial direction7).

That is, a large number of heat insulating structures /9 are fixedly installed on the outer circumferential surface of the plurality of liners /j- arranged concentrically with constant gaps in the circumferential direction and the vertical direction. and
In addition, the positions of the gaps 20 in each liner/j are provided evenly in the circumferential direction and in the vertical direction.

However, with this configuration, the occurrence of local hot spots can be prevented, and the temperature non-uniformity between the heat insulating structure /9 part and the gap J part can be reduced more effectively. [Effects of the Invention] As explained above, the present invention requires a plate-shaped insulating box in which a plurality of thin box-shaped insulating elements are housed and filled with gas on the outer circumference side of the liner in the circumferential direction and the vertical direction. A large number of them are arranged at intervals, and gas is also sealed inside the insulating elements, so the radiant heat shield keeps the inner wall temperature of the container low and reduces the temperature gradient near the liquid surface, thereby reducing thermal stress and heat in the container. Deformation can be reliably and effectively alleviated.

(g) Furthermore, since the inside of the heat insulating element is reinforced with a reinforcing member, even if a crack occurs in the heat insulating box and liquid infiltrates, there is extremely little risk of damage to the heat insulating element. Therefore, deterioration in heat insulation performance can be prevented and reliability can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional example, Fig. 2 is a sectional view showing an embodiment of the present invention, Fig. 3 is an enlarged sectional view of the main part of Fig. 2, and Fig. 7 (,) (b) is FIG. 5 is a perspective view showing typical examples of reinforcing members installed in a heat insulating element, and FIG. 5 is a schematic view showing another embodiment of the present invention. 1/... Furnace vessel, 15... Liner, /7... Free liquid level, /9... Insulating structure 1. w...gap, here...
...Insulating element, ,Z3,30...Inert gas, 2
6... Stud, 3/... Reinforcement member, 3/a...
Uneven board, 31b... corrugated board. Applicant's representative Inomata Kiyosu 2nd time Leopard 3rd time

Claims (1)

[Claims] / In a nuclear reactor vessel filled with a liquid having a free liquid level, a cylindrical liner is disposed on the inner peripheral surface side,
A large number of plate-shaped insulating boxes each containing a plurality of layers of thin box-shaped insulating elements and filled with gas are arranged at required intervals in the circumferential direction and in the vertical direction on the outer peripheral surface of the inner, and the inside of the insulating elements is A thermal insulation device for a nuclear reactor vessel characterized by being reinforced with a reinforcing member and filled with gas. The heat insulating device for a nuclear reactor vessel according to claim 1, characterized in that the heat insulating box is fixed to the liner at one point in the center thereof. 3. A plurality of liners are arranged concentrically, and a heat insulating box is arranged on the outer peripheral surface of each liner. 3. A heat insulating device for a nuclear reactor vessel according to claim 1 or 2, characterized in that the gap positions between adjacent heat insulating boxes in each liner trap are anisotropic with respect to each other.