JPH0374960B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a roof slab of a nuclear reactor structure, and relates to a through hole structure suitable for preventing thermal deformation of equipment due to convection of cover gas in the roof slab equipment through holes. be.

[Background of the invention]

Figure 1 shows the reactor structure.

A reactor core 2 is placed inside the reactor vessel 1 . Cold Na in the code pool 3 is sucked into the pump 5 suspended from the roof slab 4 and discharged into the high-pressure plenum 6 at the bottom of the core 2, then passes through the core 2, becomes high-temperature Na, enters the hot pool 7, and becomes intermediate heat. After passing through the exchanger 8 and exchanging heat with secondary Na, it returns to the cold pool 3 and goes around. A roof slab is installed above the reactor, and argon cover gas is filled between the roof slab and the sodium in the reactor vessel. An intermediate heat exchanger for exchanging heat between primary sodium and secondary sodium, a pump for circulating primary sodium, and the like are mounted on the roof slab. In order to mount these devices on the roof slab, through-holes are provided in the roof slab, but the thermal expansion of the installed devices such as intermediate heat exchangers, the manufacturing accuracy of the roof slab and the installed devices, the installation accuracy of the devices, etc. Taking this into consideration, a gap is required between the through hole in the roof slab and the mounted equipment. This gap is open to the cover gas at the bottom. The argon cover gas is at a high temperature because it is in direct contact with the sodium in the hot pool, which is at about 500°C. Here the outside of the roof slab is at room temperature;
In the through-hole gap, the upper side is low temperature and the lower side is high temperature, resulting in unstable flow. Convection can easily occur due to certain minute disturbances. The situation is as shown in Figure 2. The cover gas rises from one point, rises to the upper end, splits into two at the upper end, rotates 180 degrees, and descends.
When convection occurs, the temperature of the cover gas is higher in the rising part of the cover gas and lower in the falling part of the cover gas on the 180° opposite side. This temperature difference causes a temperature difference on the equipment side, and the difference in thermal expansion causes deformation of the equipment.

To prevent thermal deformation of equipment due to convection,
As shown in Fig. 4, there is a method of attaching a vertical rib 11 in the axial direction to the outer periphery of the penetrating device to prevent convection of the cover gas. During this process, it is impossible to eliminate the gap due to factors such as equipment manufacturing accuracy, installation accuracy, and adhesion of sodium vapor in the cover gas. I couldn't prevent it.

[Purpose of the invention]

An object of the present invention is to provide a through-hole structure that prevents thermal deformation of equipment due to natural convection of cover gas generated in an annular space between a roof slab through-hole and equipment.

[Summary of the invention]

The present invention provides, as a component, a device in which a portion below the device flange passes through a through hole in a roof slab of a tank-type FBR reactor whose upper portion is closed by a device flange, and which faces the through hole. A structure for preventing thermal deformation of a device, characterized in that vertical ribs are attached to the outer circumference of the device in a facing arrangement with the device sandwiched therebetween, and a heater is attached to the vertical rib along the vertical direction. Heat from the heater is applied to the cover gas existing in the gap between the equipment and the roof slab in the through hole, forcing an upward flow along the vertical ribs, and a downward flow at the center between the vertical ribs. Even if there is a gap around the outer periphery of the vertical rib, the forced convection state can be generated by the forcing force, and the temperature of the parts facing each other across the center of the device can be brought closer to each other, and the temperature state of the penetrating device can be maintained without deformation. It is something that is taken as a thing.

[Embodiment of the Invention] A heater is embedded in a conventional vertical rib as shown in FIGS. 5 to 7. During reactor operation, the heater is energized and heated to induce an upward flow of cover gas near the vertical ribs. The rising cover gas collides with the flange of the penetration device blocking the upper end of the roof slab penetration hole and moves along the flange surface. At this time, the outside of the roof slab is at room temperature and the cover gas is cooled through the flange of the penetration device. The cooled cover gas flow collides with the other cover gas flow that has moved in the same way, resulting in a downward flow. The flow of the cover gas at this time is as shown in FIG. Since the vertical ribs are installed facing each other with the equipment sandwiched in between them as shown in Figure 5, the temperature of the 180° facing can be made equal, thereby preventing thermal deformation of the penetrating equipment due to heat.

〔Effect of the invention〕

According to the present invention, the vertical ribs and the heater attached to the roof slab penetrating equipment can equalize the temperature of the equipment facing each other by 180 degrees, so that thermal deformation of the equipment can be prevented.

[Brief explanation of drawings]

Figure 1 is a diagram of the overall structure of a tank-type FBR nuclear reactor, Figure 2 is a diagram of equipment through-hole convection, Figure 3 is a plan view of a penetration part according to the prior art, Figure 4 is a vertical sectional view of a penetration part according to the prior art, FIG. 5 is a plan view of the penetrating portion of an embodiment of the present invention, FIG. 6 is an enlarged view of the vertical rib portion, and FIG. 7 is an enlarged view of the vertical rib portion.
The figure is also a vertical sectional view of the penetration part, and FIG. 8 is a developed view of the device penetration hole. 4...Roof slab, 5...Pump, 8...Intermediate heat exchanger, 11...Vertical rib, 12...Heater.

Claims (1)

[Claims] 1 Tank type where the upper part is closed by the equipment flange
In a device whose portion below the device flange passes through a through hole in a roof slab of an FBR reactor, vertical ribs are placed on the outer periphery of the device facing the through hole so as to face each other with the device in between. A structure for preventing thermal deformation of a device, characterized in that a heater is attached along the longitudinal direction of the vertical rib.