JPS6219599B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a main circulation pump for a tank-type fast breeder reactor.

A primary main circulation pump used in a conventional tank-type fast breeder reactor will be explained with reference to FIG. A reactor core 2 is arranged in a tank 1, and a plurality of circulation pumps 3 are arranged around this reactor core 2. The circulation pump 3 is filled with a low temperature sodium liquid 4 at about 400°C. Its outer periphery is in contact with a high-temperature sodium liquid 6 at about 550° C. via a partition wall 5 . The partition wall 5 and the pump casing 7 are filled with the sodium liquid 4, and the upper part of the pump casing 7 is sealed with a radiation shield 8. A rotating shaft 10 having an impeller 9 attached to its lower end is supported by a ball bearing 11 and a hydrostatic bearing 13 inside an impeller casing 12. The upper part of the rotating shaft 10 passes through the radiation shield 8 and reaches outside the pump casing 7, and is connected to a drive motor (not shown). Low temperature sodium solution 4
An inert gas space 14 is formed in the pump casing 7 on the upper side. Inert gas is introduced from the inert gas filling port 15 as indicated by an arrow 16 in the figure. Further, the low temperature sodium liquid 4 flows from the overflow hole 17 of the pump casing 7 to the partition wall 5.
and the gap between the pump casing 7 and the pump casing 7.

In the above configuration, the sodium liquid that has flowed in from the inlet at the lower end of the partition 5 is guided from the inlet of the impeller casing 12 and is pressurized by the impeller 9, and most of it is discharged from the outlet at the lower end of the partition 5 to the core 2 side. be done. A part of the sodium liquid discharged from the impeller 9 is supplied to the static pressure bearing 13.
After lubricating the rotating shaft 10 and the bearing 13, a part of the
leaks into the pump casing 7 through the gap between the The sodium solution leaked into the pump casing 7 flows out from an overflow hole 17 provided in the pump casing 7 into the slit between the pump casing 7 and the partition wall 5. The liquid sodium solution that has flowed into this narrow gap flows down and is returned to the lower end inlet of the partition wall 5.

However, in the above configuration, the temperature of the partition wall 5 on the side of the core 2 is high due to radiant heat, and conversely, the temperature of the partition wall 5 on the side opposite to the core 2 is low. Therefore, the temperature distribution on the outer periphery of the pump casing 7 becomes uneven, and the casing 7 supporting the rotating shaft 10 is deformed, which has an adverse effect on the pump function.

This invention takes into consideration the above-mentioned disadvantages of the main circulation pump for fast breeder reactors, and aims to provide a highly reliable liquid metal pump that eliminates the non-uniformity of the temperature in the circumferential direction of the casing that supports the rotating shaft. do.

The present invention is characterized by: a pump casing installed in a partition wall provided on the outer periphery of the core in a tank having a reactor core; an impeller casing having a liquid metal inlet and discharge part connected to a lower part of the pump casing; A liquid metal pump consisting of a rotating shaft that extends through the casing to the impeller casing and is supported by a bearing, and an impeller that is attached to the lower end of the rotating shaft within the impeller casing. This is due to the placement of a heat shield plate along the casing.

Hereinafter, a preferred embodiment of a circulation pump of the present invention applied to a tank-type fast breeder reactor will be described with reference to FIGS. 2 and 3.

Components that are the same as those in FIG. 1 are designated by the same reference numerals.
In FIG. 2, a heat shield plate 18 is disposed between the partition wall 5 and the pump casing 7, covering the pump casing 7 and running along the casing 7.
A plurality of convection prevention plates 19 are arranged on the outer periphery of the pump casing 7 between the heat shield plate 18 and the convection prevention plates 19 to prevent natural convection of the cover gas. The pump casing 7 has an overflow hole 20 for leaking sodium liquid around the lower end and a cover gas flow hole 2 around the upper end.
1 is drilled. Further, the heat shield plate 18 is also provided with cover gas flow holes 22 .

The rotating shaft 10 is inserted into a pump casing 7 provided within the partition wall 5, and an impeller 9 is provided at its lower end. The upper part of the rotating shaft 10 passes through the radiation shield 8 and is connected to a drive motor (not shown) outside the pump casing 7.

When the drive motor is driven, the impeller 9 attached to the rotating shaft 10 rotates, and sodium liquid flows into the lower end of the partition wall 5 and is pressurized by the impeller 9.
Most of it is sent to the reactor through the discharge port at the lower end of the partition wall 5. On the other hand, the sodium liquid that has lubricated the hydrostatic bearing 13 flows out from the overflow hole 20 of the pump casing 7 between the pump casing 7 and the heat shield plate 18 .

This prevents the pump casing 7 from receiving radiant heat from the high-temperature core 2 side, and
The effect of natural convection of the cover gas in the tank 1 is also eliminated.

A double cylindrical portion filled with cover gas is formed between the heat shield plate 18 and the pump casing 7.
(See Figure 3) The cover gas at the lower end H of the double cylinder is in contact with the high-temperature sodium solution, and the upper end L is the low-temperature cover gas, so the cover gas heated by the high-temperature sodium solution becomes an upward flow. Natural convection may occur, which rises as indicated by arrow U in the figure and becomes a downward flow on the opposite side of this upward flow, descending as indicated by arrow D in the figure. However, the occurrence of this natural convection is prevented by the presence of the convection prevention plate 19.

The cover gas is introduced through the filling hole 15 as indicated by an arrow 16 in the figure, and flows out into the tank 1 through the flow holes 21 and 22.

This improves temperature non-uniformity in the circumferential direction of the pump casing 7.

As explained above, according to the present invention, since the pump casing is covered and a heat shield plate is arranged along the casing, thermal deformation of the casing that supports the rotating shaft can be eliminated, and highly reliable circulation can be achieved. You can get a pump.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional circulation pump for a tank-type fast breeder reactor, Fig. 2 is a longitudinal sectional view of a circulation pump for a tank-type fast breeder reactor of the present invention, and Fig. 3 is a longitudinal sectional view of a circulation pump for a tank-type fast breeder reactor of the present invention. FIG. 2 is a schematic diagram showing the occurrence of 2... Core, 5... Partition wall, 7... Pump casing, 18... Heat shield plate, 19... Convection prevention plate.

Claims (1)

[Scope of Claims] 1. A pump casing installed within a partition wall provided on the outer peripheral side of the reactor core in a tank having the reactor core;
an impeller casing having a liquid metal inlet and a discharge part connected to the lower part of the pump casing; a rotating shaft extending through the inside of the pump casing to the impeller casing and supported by a bearing; 1. A circulation pump for a tank-type fast breeder reactor, characterized in that the pump casing is covered with a heat shielding plate arranged along the casing in a liquid metal pump comprising an impeller attached thereto. 2. The circulation pump for a tank-type fast breeder reactor according to claim 1, wherein the heat shield plate is located between the partition wall and the pump casing. 3. The circulation pump for a tank-type fast breeder reactor according to claim 2, characterized in that a convection prevention plate for preventing natural convection is attached to the outer periphery of the pump casing.