JPS5819451A - Cold trap for liquid metal - Google Patents

Abstract

PURPOSE:To increase the amount of the impurities to be captured in settling chamber parts wherein the impurities in liquid metal for cooling of atomic reactors in a cold trap are deposited and are captured by providing heaters in said chamber parts. CONSTITUTION:Of the liquid Na cooled by the flow of a coolant such as gaseous N2 through an inlet 17 to an outlet 18, the impurities deposited in an annulus part 8 are deposited with the bottom part of a well part 1 and the settling chambers 2 provided in the part 1 as nuclei. The impurities of the liquid Na entering a capturing part 5 are increased by segregation to the amt. larger than the actual amt. of the impurities, thereby closing the drain nozzle 3 in the upper part of the chamber 2. The temp. of the nozzle 3 is measured with a thermometer 22 provided near the same, and voltage is applied to the heaters 9 provided in the chambers 2 according to the measured temp. The closing of the nozzle 3 is prevented and the amt. of the impurities to be captured is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold trap for liquid metal, and more particularly, to a cold trap for liquid metal.
The present invention relates to a cold trap for liquid metal suitable for use in effectively removing impurities contained in liquid metal.

The present invention relates to improvements in liquid cold traps for removing impurities in liquid metals. The prior art will be explained with reference to FIG.

Fast breeder reactors use cold traps as purification devices to remove impurities in the liquid metal used as reactor coolant. A cold trap cools liquid metal with another coolant to precipitate impurities in the liquid metal (for example, sodium oxide in liquid metal sodium), and removes this with a wire mesh or the like. This K usually has a cylindrical trapping part 5 formed with a wire mesh layer 4 in the center, a settling channel 1 having a settling channel (-2) in the lower part to precipitate impurities, and a nitrogen gas around the outer periphery. Cooling agent 6
There is a cylindrical cooling section 7 with a double wall into which impurities are introduced, and an anilus section 8 which introduces liquid metal from which impurities are to be removed and cools it from the outer periphery.

In conventional cold traps, precipitation of impurities is
The process is carried out in the anilus section 8, then in the reservoir section 1 having a settling channel (-2), and finally in the wire mesh 4.

Most of the impurities are precipitated using the settling channel No. 2 as a nucleus (sometimes referred to as a cold finger), and then the precipitation of impurities begins in the wire gauze section 4.

In this case, the precipitation of sodium impurities is temperature dependent, and therefore depends on the temperature at the location where the impurities are first precipitated. Therefore, the apparent impurities that precipitate in the settling chamber 2 include sodium that does not contain impurities due to the mass transfer (segregation) of impurities in IJium, which occurs simultaneously with the precipitation of impurities in sodium. It ends up. Therefore, the amount of IJium precipitated as an impurity in the second part of the settling chamber increases, resulting in a decrease in the ability to precipitate impurities in the second part of the settling chamber and blockage of the drain nozzle 6, making it impossible to drain.

An object of the present invention is to provide a heater 9 in the settling chamber 2 part for precipitating and capturing impurities contained in the liquid metal sodium in the cold trap, thereby increasing the amount of impurities captured in the settling chamber 2 part. The objective is to provide an increased cold trap.

This invention is patented in Japanese Patent No. 818861.
This is related to the section ``Setting out at the bottom'' written on page 1, lines 9 to 14 of page 4, and the state of precipitation of impurities at the bottom was investigated by disassembling the existing cold trap at the Kinki Oarai Engineering Center. This is because we have confirmed the necessity of providing a heater like the one according to the present invention. □ Hereinafter, one embodiment of the present invention will be explained with reference to FIG. In the drawings, reference numeral 10 denotes a liquid sodium inlet for introducing liquid sodium into the anilus portion 8. This anneal section 8 is bounded by upper and lower end plates 11.12 and a cylindrical wall 13.14. Further, on the inside of the cylindrical wall 14, there is provided a capturing part 5 having four layers of wire mesh and using the upper end plate 11 as a partition wall. At the bottom, there is an internal heater that disturbs the flow of impurities precipitated while descending through the anneal section 8 and the sodium flowing into the capture section 5 to generate vortices, etc., and causes the impurities in the sodium to precipitate and adhere. The settling chamber 2 has a settling chamber 9 inserted therein. At the upper end of the capture section 5, an outlet 16 for taking out purified liquid sodium is provided in the end plate 11. On the outer periphery of the anilus part 8,
A coolant passage section 19 for nitrogen gas or the like has an inlet 17 through which a coolant such as nitrogen gas to cool the liquid sodium in the anilus section 8 flows in, and an outlet 18 through which it flows out after cooling. Thus, it is formed.

Next, the operation of the cold trap of the present invention configured as described above will be explained. Cooling nitrogen gas flows into the coolant passage section 19 such as nitrogen gas from the inlet 17 and flows out from the outlet 18 . In the liquid sodium cooled by nitrogen gas, impurities precipitated in the anneal section 8 are removed from the bottom of the reservoir section 1 and a settling chamber 2 provided in the reservoir section 1.
is precipitated as a nucleus. Also, the liquid that has flowed into the capture section 5)
Impurities in the IJium are captured by the wire mesh 4. At this time, the impurities precipitated and captured in the settling chamber 2 increase due to segregation and become larger than the actual amount of impurities. A thermometer 22 is installed in the drain nozzle, and the temperature near the drain nozzle is measured by the thermometer 22. Depending on the measured temperature, a voltage is applied to the heating heater 8 installed in the reset channel (-2) to prevent the drain nozzle 3 from being blocked. In addition, by changing the applied voltage, it is possible to control the type of impurities that precipitate in the second part of the settling channel.As mentioned above, According to this embodiment, it is possible to prevent the drain nozzle 3 provided in the settling chicken par 2 part of the cold trap from clogging, and also to select the type of impurity to be precipitated.
This has the effect of increasing the amount of impurities captured in the second part of the settling chamber.

According to the present invention, since the temperature of the settling chamber 2 can be controlled, a temperature difference can be created between the settling chambers 2, and precipitated impurities can be captured.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a conventional cold trap for liquid metal, and FIG. 2 is a vertical cross-sectional view of a cold trap for liquid metal according to the present invention. 2...Settling chamber, 3...Drain nozzle, Figure 1

Claims (1)

[Claims] 1. A heater installed inside the settling chamber is controlled by a thermometer near the drain nozzle installed at the upper part of the settling chamber installed in the reservoir, and the water is captured by the settling chamber. This cold trap for liquid metal is characterized by its ability to efficiently melt impurities in the liquid metal and prevent clogging of the drain nozzle. 2. The method according to claim 1, characterized in that a heater for melting impurities in the adhered liquid metal can be inserted into the settling chamber installed in the reservoir part, using the settling chamber as a core. Cold trap for liquid metal. .