KR20090022812A - Outlet pipe line of sodium fast reactor steam generator to prevent the crystallization of sodium hydroxides therein - Google Patents

Abstract

An outlet pipe system of steam generator of fast reactor is provided to prevent crystallization of sodium hydroxide in whole part of a transfer pipe by installing a plurality of ultrasonic generating units on a path of the transfer pipe. An outlet pipe system(100) of a steam generator of a fast reactor comprises a transfer pipe(120) and an ultrasonic generating unit(130). The transfer pipe is connected to one side of a steam generator(110), and provides a flow path of a molten metal and a metal compound in leakage state due to a tube damage of the steam generator. The molten metal is refrigerant. The metal compound is formed by reaction between water and the molten metal. Temperature of the transfer pipe is lower than temperature of the metal compound. The ultrasonic generating unit is mounted on a surface of the transfer pipe, and prevents crystallization of the metal compound inside the transfer pipe by generating the ultrasonic.

Description

Outlet pipe line of sodium fast reactor steam generator to prevent the crystallization of sodium hydroxides therein}

The present invention relates to an exhaust piping system of the steam generator, and more particularly, to the exhaust piping system of the steam generator to prevent the sodium compound crystallized in the inner surface of the pipe due to the temperature difference to maintain a smooth flow.

High-speed reactors (fast growth reactors or liquid metal furnaces) are currently being actively developed as nuclear reactors that can significantly increase the utilization efficiency of uranium resources because they can generate (proliferate) more fuel than consumed during power generation.

Numerous reactors that enable proliferation are currently being studied, but liquid uranium and plutonium mixed oxides are used as nuclear fuel, liquid metal sodium is used as the coolant, and moderators are used as liquid metals using nuclear fission of plutonium by fast neutrons. It aims at practical use as a plant for power generation.

The high speed furnace has the advantage of operating the cooling system at high temperature and low pressure by using liquid sodium as the coolant.However, if water (steam) leaks into the sodium due to heat pipe damage in the high speed steam generator, sodium is chemically active. It forms a sodium compound through a chemical reaction with water, which causes the problem of preventing the flow of molten sodium mixed with the sodium compound when the sodium compound is discharged from the steam generator through the discharge system.

In order to solve this problem, a pipe is formed from a steam generator in which the sodium compound is accumulated and discharged into a separate storage tank. However, due to the temperature difference between the steam generator and the storage tank and the pipe, the sodium compound crystallizes on the inner surface of the pipe to block the pipe.

An object of the present invention for solving the above problems is to prevent the sodium compound formed by the reaction of the molten sodium flowing in the pipe and the water is crystallized in the inner surface of the pipe to prevent the steam generator discharge pipe to maintain the flow characteristics of the pipe To provide a system.

Another object of the present invention is to provide a discharge piping system of the steam generator that can save time and cost without the need to process a separate pipe inside.

According to a preferred embodiment of the present invention for achieving the above objects, the discharge piping of the steam generator mixed with sodium hydroxide of the present invention comprises a transfer pipe and an ultrasonic wave generating unit.

The transfer pipe may provide a path through which the molten metal in the high-speed steam generator and the metal compound formed by reacting the molten metal with water flow.

The molten metal here is a molten sodium (Na), lithium (Li), potassium (K) or a mixed metal, or, for example, sodium in these metals is produced by the reaction of sodium hydroxide and sodium oxide or sodium with water It means a molten metal in which the mixed metal compound is mixed, and the metal compound means sodium hydroxide and sodium oxide when the molten metal is sodium.

And, the ultrasonic wave generating unit is provided on the surface of the conveying pipe, it is possible to prevent the crystallization of the metal compound on the inner surface of the conveying pipe by generating an ultrasonic wave to the conveying pipe.

In the transfer pipe, a mixture formed by mixing the metal compound and the molten metal may be transferred.

On the other hand, the exhaust pipe of the steam generator further comprises a steam generator for storing the molten metal and water, the transfer pipe may be coupled to the steam generator. In particular, the transfer pipe is preferably welded to the steam generator to ensure watertightness.

The water may be supplied to the heat exchanger tube of the steam generator and the like type heat exchanger through the water supply tube.

In the present invention, the ultrasonic wave generating unit may be formed in plural, and the interval between the ultrasonic generating units adjacent to each other may be 1/2 or less of the mixture flow rate transferred through the transfer pipe.

The ultrasonic generating unit may be attached to the surface of the conveying pipe, it is preferable to be welded to the conveying pipe to increase the ultrasonic delivery rate. The ultrasonic wave in the present invention may be pulsed while being in the form of a sine wave or a square wave in the range of 15 kHz to 30 kHz without one phase.

And, the frequency of the ultrasonic wave can be more effectively prevent the crystallization of the metal compound by the same as the resonance frequency of the transfer pipe.

Meanwhile, the molten metal may be sodium in a molten state, and thus the metal compound may be any one of sodium hydroxide and sodium oxide, and like lithium (Na), elements such as lithium (Li) and potassium (K) may be used. In the case of the metal of the Group 1 element in the periodic table, the metal may react with water to be any one of a metal hydroxide and a metal oxide.

As described above, according to the present invention, the metal compound formed by the reaction of the molten metal and water is prevented from crystallizing on the inner surface of the conveying pipe due to the temperature difference when the molten metal is introduced into the conveying pipe having a relatively low temperature to improve the flow characteristics of the conveying pipe It has the effect of maintaining good.

In addition, there is an effect of preventing the crystallization of the sodium compound in all parts of the conveying pipe by mounting the ultrasonic generating unit so as to be close to the steam generator, and by installing a plurality of ultrasonic generating units on the path of the conveying pipe.

In addition, when water leaks into sodium due to a leak accident in the heat exchanger tube of the high-speed steam generator, ultrasonic waves may be applied to the sodium compound formed by the reaction of sodium and water to prevent crystallization on the inner surface of the transfer pipe. It is possible to prevent the sodium compound from agglomeration in the steam generator, thereby creating a safe working environment.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. In this embodiment, but may be applied to sodium as the molten metal, but is not limited to this, it is a matter of course that can be used a variety of active metal materials having excellent heat capacity and smooth flow characteristics in the liquid state.

First, referring to Figure 1, the overall configuration of the exhaust piping system of the steam generator of the present invention will be described. Here, FIG. 1 is a block diagram for demonstrating the discharge piping system of the steam generator of this invention. And since Figure 1 shows the phenomenon occurring in the discharge piping of the steam generator provided in the actual high speed furnace, the present invention can be applied to other reactors or various plant apparatuses other than the high speed furnace by adjusting the ultrasonic intensity and number.

The exhaust piping system 100 of the steam generator of the present invention includes a steam generator 110, a transfer pipe 120, an ultrasonic generator unit 130, a gas supply unit 140 and a storage tank 150.

Here, the discharge piping system of the steam generator refers to a piping system in which the ultrasonic generator unit 130 including the steam generator 110 is mounted, and the molten metal and the melt from the steam generator 110 to the storage tank 150. Refers to an apparatus applied to transfer a metal compound formed by reacting metal and water.

The steam generator 110 provides a space for receiving the molten metal 10 and water, the water is transferred to the molten metal 10 in the form of steam, and then discharged to the outside.

In the space of the steam generator 110, the molten metal 10 reacts with the water to form a metal compound formed in a lump form. When the molten metal 10 is sodium, the metal compound is sodium oxide or sodium hydroxide produced by chemical reaction of the sodium and water.

In addition, the water supply pipe 160 for supplying the water is connected to one side of the steam generator 110. One end of the water supply pipe 160 may be formed as a nozzle to inject the water into the internal space of the steam generator 110.

The transfer pipe 120 is connected to one side of the steam generator 110 to transfer the metal compound and the molten metal 10 generated as a result of chemical reaction between the molten metal 10 and the water. That is, the transfer pipe 120 is mixed with the molten metal 10 in a state in which crystals of the metal compound are dispersed and then transferred.

The inner surface of the transfer pipe 120 is lower in temperature than the steam generator 110. As a result, the metal compound is partially crystallized in contact with the inner surface of the transfer pipe 120 while flowing inside the transfer pipe 120.

On the other hand, in this embodiment, the transfer pipe 120 is preferably welded to the steam generator 110 to ensure water tightness.

The ultrasonic wave generating unit 130 is mounted on the transfer pipe 120, and specifically, is mounted on the outer wall surface of the transfer pipe 120. On the other hand, the ultrasonic wave generating unit 130 is preferably welded to the conveying pipe so that the ultrasonic wave propagates well to the conveying pipe 120. The ultrasonic wave generating unit 130 generates ultrasonic waves to prevent the metal compound introduced into the transfer pipe 120 from crystallizing on the inner surface of the transfer pipe 120 due to a temperature difference.

Specifically, the means for preventing the crystals on the inner surface of the transfer pipe 120 is to prevent the crystallization is made by the adhesion of the crystals generated on the inner surface by the ultrasonic waves, the crystals attached to the inner surface is ultrasonic energy and It is to prevent crystallization by fragmenting or disturbing crystal growth by frequency characteristics, thereby preventing the crystallization from growing or solidifying.

The ultrasonic wave generating unit 130 may be disposed in plural along the transfer pipe 120, and the interval of each of the transfer pipes is the molten metal 10 and the metal compound flowing in the transfer pipe 120. It is preferable that the flow rate is set to 1/2 or less.

In addition, the ultrasonic wave generating unit 130 may be located close to the storage tank 150 to prevent the crystallization from occurring on the inner surface of the transfer pipe 120 from the point of entry into the transfer pipe 120. .

The gas supply unit 140 may supply argon (Ar) gas to the steam generator 110. Here, the argon gas may prevent the molten metal 10 from being changed into a metal oxide on the inner side surface of the steam generator 110 to prevent sticking. The gas supply unit 140 may be connected to the storage tank 150 to supply the argon gas.

On the other hand, the ultrasonic wave generation unit 130 may be driven when the concentration of the molten metal measured in the steam generator 110 is higher than a predetermined concentration.

Referring to Figures 2 and 3, the crystallization state of the metal compound according to before and after the driving of the ultrasonic generating unit is as follows. Here, FIG. 2 is an enlarged view of part I of FIG. 1 and is an operation diagram for explaining a state before driving of the ultrasonic generating unit, and FIG. 3 is an operation diagram for explaining a state after driving of the ultrasonic generating unit. .

As shown in the drawing, the amorphous metal compound 30 is mixed and flows in the molten metal flowing in the transfer pipe 120. The metal compound 30 is discharged through the outlet 114 of the steam generator 110 having a high temperature, and has a higher temperature than the transfer pipe 120.

Due to this temperature difference, the metal compound 30 loses heat while being in contact with the inner surface of the conveying pipe 120 while the conveying pipe 120 flows, and as a result, in the inner surface of the conveying pipe 120. Crystallization produces crystal 40 of metal compound.

The metal compound 30 is formed of amorphous crystals of a relatively small size in the steam generator 110, but the amorphous crystals grow and grow in size as the temperature is introduced into the transfer pipe 120 having a low temperature, and the transfer pipe ( 120) It grows into larger crystals more easily due to heterogeneous surface effects on the inner surface.

The crystal 40 of the metal compound may gradually block the passage of the transfer pipe 120 after a predetermined time as the crystal size increases. However, by driving the ultrasonic wave generating unit 130 mounted perpendicularly to the surface of the transfer pipe 120, the ultrasonic wave is transferred to the transfer pipe 120 to determine the metal compound on the inner surface of the transfer pipe 120. ) Can be prevented from being generated.

The ultrasonic generating unit 130 connects between the ultrasonic generating unit 132 for generating the ultrasonic wave and the ultrasonic generating unit 132 and the transfer pipe 120 to transmit the ultrasonic wave to the transfer pipe. 134. Here, the ultrasonic transmitting unit 134 is preferably formed using a metal material having excellent acoustic characteristics, and is preferably formed of a material having strong heat resistance because it is coupled to the outside of the transfer pipe 120 having a relatively high temperature. .

The ultrasonic generating unit 130 may be configured in plural numbers and may be mounted at uniform intervals along the path of the transfer pipe 120. At this time, the interval between the neighboring ultrasonic wave generating unit 130 has a constant correlation with the flow rate of the fluid, such as the molten metal and metal compound 30 flowing through the transfer pipe 120. This relationship can be expressed as an equation (1).

 Here, D [m] is the distance between neighboring ultrasonic wave generating units, and V [㎧] is the speed of the fluid flowing through the conveying pipe. That is, the spacing (D) between the ultrasonic wave generating unit 130 is less than 1/2 of the flow rate (V) of the fluid, such as the molten metal and the metal compound 30 flowing through the transfer pipe 120 It is desirable to be.

In this way, when the ultrasonic wave is applied to the flow rate of the molten metal and the metal compound 30 flowing through the transfer pipe 120, the ultrasonic wave is added to the period peak of the fluid flow rate to the molten metal and the metal compound 30 The phenomenon of growing into crystals on the inner surface of the transfer pipe 120 can be effectively prevented.

On the other hand, the plurality of ultrasonic generating unit 130 is preferably mounted in a zigzag form in a direction facing each other along the path of the transfer pipe 120.

The frequency of the ultrasonic wave generated through the ultrasonic wave generating unit 130 may have the same value as the resonance frequency of the transfer pipe 120, and the ultrasonic wave may be generated in the form of a surface wave.

In addition, the ultrasonic energy intensity generated through the ultrasonic wave generating unit 130 is such that the amorphous crystal of the metal compound is large enough to prevent adhesion and growth of the inner surface of the transfer pipe 120. The appropriate energy intensity of the ultrasonic wave can be determined through Equation 2 below.

 Here, W [watts] is the energy intensity of the ultrasonic waves, G is the energy intensity of the ultrasonic waves per 1 kg. For example, if the weight of the fluid flowing over an interval of 1m between the ultrasonic generating units is 2 kg, G is 2, and if the weight of the fluid flowing over the 1m interval is 4 kg, G is 4 do. Here, the fluid refers to a molten metal containing a metal compound.

As such, when the distance between the ultrasonic generating units 130 adjacent to each other is determined, the energy intensity of the ultrasonic waves may also be determined. However, since the amount of fluid flowing through the transfer pipe 120 is also changed, the ultrasonic wave may be supplied at an energy intensity greater than that of the energy calculated by Equation 2.

FIG. 4 is a cross-sectional view illustrating the ultrasonic wave generation unit connected along the tangent of the transfer pipe surface as a modification of FIG. 2.

As shown in the drawing, the transport pipe 120 for transporting molten metal containing a metal compound is equipped with an ultrasonic wave issue unit 130 to prevent the metal compound from crystallizing on the inner surface of the transport pipe 120. do.

In this modified example, one side of the ultrasonic wave generating unit 130 is positioned on the tangent of the surface of the transfer pipe 120. The ultrasonic wave generated through the ultrasonic wave generating unit 130 is thus evenly transmitted to the entire surface of the transfer pipe 120 and more effective in preventing crystallization than when mounted vertically on the surface of the transfer pipe 120. to be.

FIG. 5 is a cross-sectional view of another ultrasonic generator of FIG. 2, illustrating an ultrasonic wave generating unit mounted inclined to a conveying pipe.

As shown in the drawing, a plurality of ultrasonic wave generating units 130 are mounted on the surface of the conveying pipe 120 for conveying the molten metal mixed with the metal compound, and each of the ultrasonic wave generating units 130 has a constant slope α. It is mounted inclined by).

The ultrasonic wave generation unit 130 prevents the metal compound contained in the molten metal from sticking to the inner surface of the transfer pipe 120 to crystallize. As in the present modified example, the ultrasonic wave generating unit 130 may be inclined to the surface of the transfer pipe 120 to transmit ultrasonic waves in a wider range along the transfer pipe 120. That is, when the ultrasonic wave generating unit 130 is mounted perpendicularly to the surface of the transfer pipe 120, ultrasonic waves are transmitted only to a narrow area in contact with the ultrasonic wave generating unit 130. It is also transmitted in the longitudinal direction along the surface and the inside of the conveying pipe 120 may be affected by the ultrasonic waves over a wider area.

The ultrasonic wave generation unit 130 of the present modified example may be mounted in a state of about 20 to 40 degrees with respect to the surface of the transfer pipe 120, and most preferably, the transfer unit is mounted at an inclination of about 30 degrees. It is more effective to prevent crystallization from occurring on the inner surface of the pipe 120.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram for demonstrating the discharge piping system of the steam generator of this invention.

FIG. 2 is an enlarged view of part I of FIG. 1 and is an operation diagram illustrating a state before driving the ultrasonic wave generating unit.

3 is an enlarged view of part I of FIG. 1 and is an operation diagram illustrating a state after driving of the ultrasonic wave generating unit.

FIG. 4 is a cross-sectional view illustrating the ultrasonic wave generation unit connected along the tangent of the transfer pipe surface as a modification of FIG. 2.

FIG. 5 is a cross-sectional view illustrating another example of the ultrasonic generator tilted and mounted as another modified example of FIG. 2.

<Explanation of symbols for the main parts of the drawings>

100: exhaust piping 110: steam generator

120: transfer piping 130: ultrasonic generation unit

132: ultrasonic generator 134: ultrasonic transmitter

140: gas supply unit 150: storage tank

160: water supply pipe

Claims (19)

In the discharge piping of the steam generator receives the heat generated from the reactor core to generate steam, Is connected to one side of the steam generator, when the accident of leaking water due to the heat pipe damage of the steam generator, the molten metal and the molten metal and the water is a refrigerant agent that receives the heat of the reactor core inside the steam generator reacts A transfer pipe providing a path through which the formed metal compound flows, and maintained at a lower temperature than the metal compound; And An ultrasonic wave generation unit provided on a surface of the transfer pipe and generating ultrasonic waves in the transfer pipe to prevent crystallization of the metal compound on the inner surface of the transfer pipe; Discharge piping system of the steam generator comprising a. The method of claim 1, And the transfer pipe is mixed with the molten metal in a dispersed state of the crystals of the metal compound to be transferred. The method of claim 1, The transfer pipe is the discharge piping system of the steam generator, characterized in that welded to the steam generator. The method of claim 1, And the ultrasonic wave generating unit is attached to the outer wall surface of the transfer pipe. The method of claim 4, wherein The ultrasonic generating unit is the discharge piping system of the steam generator, characterized in that welded to the conveying pipe. The method of claim 4, wherein Discharge piping system of the steam generator, characterized in that consisting of a plurality of ultrasonic generating units. The method of claim 6, The interval between the ultrasonic wave generating unit is the discharge piping system of the steam generator, characterized in that less than 1/2 of the flow rate of the metal compound and the molten metal flowing through the conveying pipe. The method of claim 1, And the ultrasonic wave generating unit is mounted perpendicular to the surface of the transfer pipe. The method of claim 1, The ultrasonic generator unit is discharge piping system of the steam generator, characterized in that attached to the surface of the conveying pipe inclined. The method of claim 9, And an inclination angle of the ultrasonic wave generating unit is 20 to 40 degrees. The method of claim 1, One side of the ultrasonic wave generating unit is the discharge piping system of the steam generator, characterized in that located on the tangential of the outer wall surface of the transfer pipe. The method of claim 1, The molten metal is the discharge piping system of the steam generator, characterized in that any one of the metal of the Group 1 element including sodium, lithium, potassium in the periodic table of the elements. The method of claim 12, Wherein said metal oxide is any one of a metal hydroxide and a metal oxide. The method of claim 1, And the ultrasonic wave generating unit is located close to the steam generator. The method of claim 1, The ultrasonic wave generating unit An ultrasonic generator for generating the ultrasonic waves; And An ultrasonic transmitter for connecting the ultrasonic wave generator and the transfer pipe to transfer the ultrasonic wave to the transfer pipe; Discharge piping system of the steam generator comprising a. The method of claim 1, And the frequency of the ultrasonic waves is the same as the resonance frequency of the transfer pipe. The method of claim 1, The frequency of the ultrasonic wave is one of the sinusoidal wave and square wave form of one phase without the range of 15kHz to 30kHz in the range of the same or similar to the resonant frequency of the transfer pipe. The method of claim 1, And a storage tank connected to the transfer pipe and separately storing the metal compound and the molten metal. The method of claim 1, And said reactor is a high speed reactor.

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