JPS6015916B2 - Fast breeder reactor cooling and purification system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a primary cooling system or a heat exchanger for transferring thermal energy generated in the reactor core to a heat exchanger using liquid sodium as a coolant in a fast breeder reactor. Regarding the secondary cooling system, which uses liquid sodium as a coolant to transmit the thermal energy to the evaporator, more specifically, it describes a device that purifies liquid sodium by removing impurities from the liquid sodium. This relates to the cooling and purification system of fast breeder reactors.

In these cooling systems, impurities in liquid sodium (
For example, Fe, etc.) have a large amount of radioactivity, so it is important to remove as much of the impurities as possible to reduce the radiation dose.

The present invention has been made in view of the above points, and is equipped with an impurity removal device that can remove impurities from the liquid sodium and can efficiently remove the impurities, and furthermore, it is possible to regenerate the impurity removal device. The object of the present invention is to provide a cooling purification system for a fast breeder reactor that can maintain high efficiency in purifying the liquid sodium.

The drawings showing the embodiments of the present application will be described below. In FIG. 1, which is a system diagram of a fast breeder reactor, 1 indicates a nuclear reactor, the core of which is configured to be cooled with liquid sodium. This atomic system 1 constitutes the heat generating part of the primary sodium cooling system described below. In the primary sodium cooling system connected to the reactor 1, 2 is a heat exchanger, which serves as a heat receiving part in the primary sodium cooling system. A first pipe line 3 is a pipe line for sending liquid sodium heated to a high temperature in the nuclear reactor 1 to the heat exchanger 2.

A second pipe line 4 is a pipe line for sending the liquid sodium that has become low temperature in the heat exchanger 2 to the reactor 1, and there is a primary system pump 5 for transferring the liquid sodium and a liquid sodium pipe line on the way. A valve 6 is provided to adjust the flow rate.

Reference numeral 7 denotes an impurity removal device, the inlet 8 and outlet 9 of which are connected to the second conduit 4 via connecting pipes 10 and 11, respectively, as shown.

(Other than shown, the inlet 8 and outlet 9 are connected to the first pipe 3, respectively.
Note that 12 is a valve for adjusting the flow rate. Next, in the secondary sodium cooling system connected to the heat exchanger 2, 15 is an evaporator, which serves as a heat receiving part in the secondary sodium cooling system.

16 is the first pipe line, 17 is the second pipe line, 18 is the secondary pump, 19 is the valve, 20 is the impurity removal device, 21 and 22 are the inlet and outlet thereof, 23 and 24 are the second pipe line 17 ( or a connecting pipe connected to the first pipe line 16), and 25 indicates a valve, respectively.

It should be noted that since these are functionally the same or equivalent in structure to those of the primary sodium cooling system, repeated detailed explanations will be omitted. In this secondary sodium cooling system, the heat exchanger 2 serves as a heat generating section. Next, in the water system connected to the evaporator 15, 26 is a turbine, 27 is a steam distribution line, 28 is a steam and water circulation line, and 29 is a water supply pump.

Next, in FIG. 2 showing the impurity removal device 7, 31 is a case, which is formed in a hollow cylindrical shape, and has an internal space 35.
The system is designed to allow liquid sodium to flow through it.

In this case 31, numeral 32 is a cleaning liquid discharge port, which is a port for discharging waste fluid that has been used to clean the filter element, which will be described later. It's connected. Next, in the internal space 35 of the case 31, 36 is a suitable pipe, and the internal space end 35a
and Exit 9 are connected by a lotus. Reference numeral 37 denotes a filter element, which is formed into an annular and net-like shape that fits between the side wall 31a of the case 31 and the lotus tube 36, and a large number of filter elements are arranged in the direction of the bag line of the case 31 (see Fig. 2). (in the vertical direction).

Furthermore, this filter element 37 is formed using ferritic stainless steel as an example of a magnetic material. Note that the filter element 37 is not limited to the silk-like material as described above, but may also be made of cotton-like material. Reference numeral 38 denotes cooling fins as an example of a cooling means. A large number of cooling fins formed in the shape of long plates in the axial direction of the case 31 are fixed to the outer circumferential surface of the side wall 31a, and cooling air (for example, approx. 200
The liquid sodium inside the case 31 is cooled by ventilation or natural ventilation with a fan (external air of 0).

Note that this cooling means may have any configuration capable of cooling the liquid sodium in the case 31, such as a configuration in which cooling pipes are disposed between a large number of filter elements 37 inside the case 31. Reference numeral 40 denotes an electromagnet exemplified as a magnetic field generating device, which is capable of applying a magnetic field parallel to the marquee direction of the case 31 to a location where a large number of filter elements 37 are placed.

Note that the direction of the magnetic field may be perpendicular to (for example, orthogonal to) the axial direction of the case 31. 41 and 42 are connecting pipes 1, respectively.
The operation switching valves installed at 0 and 11 are shown.

Next, the cleaning system will be explained.

First, in the cleaning fluid pumping device 44, reference numeral 45 denotes a cleaning gas tank, in which gas (nitrogen, argon, etc.) as an example of cleaning fluid is sealed at high pressure. 4
Reference numeral 6 denotes an electric heater exemplified as a heating means attached to the tank 45, and is used to heat the cleaning gas.

Reference numeral 47 denotes a tank for cleaning liquid sodium, in which liquid sodium as an example of cleaning fluid is stored.

Reference numeral 48 denotes an electric heater exemplified as a heating means attached to the tank 47, and is used to heat liquid sodium for cleaning.

In addition to the electric heater, an oil or gas burner, or the temperature of the liquid sodium used for cooling may be used as the heating means. When using liquid sodium used for cooling, pipe coils for heating are arranged in the tanks 45 and 47, and the pipe line 3 is connected to the pipe coils.
Alternatively, part of the liquid sodium flowing through 4 may be allowed to flow. Reference numeral 49 indicates a gas pressure supply pipe, 50 indicates a pressure supply pipe for cleaning fluid, and 51, 52, and 53 indicate operation switching valves, respectively.

Next, 54 is a cleaning simulated liquid tank connected to the discharge pipe 33;
5 is a gas discharge pipe connected to the upper part of the tank 54, and 56 is a valve. It should be noted that since the impurity removing device 2 has the same structure as the impurity removing device 7, redundant explanation will be omitted.

Next, the operation of the above-mentioned Yokozumi will be explained.

In Fig. 1, first in the Yamaji sodium cooling system, liquid sodium, which is used for cooling the reactor 1 and has received thermal energy from the reactor 1 and has reached a high temperature (for example, 530 pm), flows through the pipe 3. It enters the heat exchanger 2 through the heat exchanger 2. In the heat exchanger 2, heat exchange is performed between liquid sodium flowing in from the pipe 3 and flowing out into the pipe 4, and liquid sodium flowing in from the pipe 17 and flowing out into the pipe 16. The liquid sodium flowing from the self-conduit 3 becomes low temperature (for example, 400 qo) and flows out to the conduit 4. The liquid sodium flowing into the pipe 4 passes through the valve 6 or the impurity removal device 7 depending on the opening degree of the valves 6 and 12, and then passes through the pump 5 and returns to the reactor 1. Return to reactor 1 for cooling. A similar operation is then performed in the secondary sodium cooling system.

That is, the liquid sodium that has received thermal energy in the heat exchanger 2 and has become high temperature (for example, 500 qo) enters the evaporator 15 through the pipe line 16. In the evaporator 15,
Thermal energy of the liquid sodium is used to evaporate or raise the temperature of water or steam at a low temperature (for example, 25 qo) flowing in from the pipe 28, and the liquid sodium becomes low temperature (for example, 300 qo) and passes through the pipe 7 and the valve. 19 or is returned to the heat exchanger 2 via the impurity removal device 20 and the pump 18. Next, in the water system, the steam that has reached a high temperature (for example, 480 qo) in the evaporator 15 passes through the pipe 27 and rotates the turbine 26, where it is heated to a low temperature (for example, 480 qo).
The water or steam that has become 0qo) is returned to the evaporator 15 via a pipe 28 and a pump 29.

Note that the ratio of the opening degrees of the valve 6 and valve 12 (valve 19
(The ratio of the function of valve 25 is also the same) is used when a large amount of impurities are contained in the liquid sodium in the cooling system and it is necessary to remove them rapidly, or when there are not so many impurities and it is necessary to remove them regularly. It is set appropriately depending on the time and situation, such as when it is only necessary to remove it little by little.

That is, for example, the entire amount of liquid sodium circulating through the cooling system may be passed through the impurity removal device, or only a portion thereof may be passed through the impurity removal device. Next, in FIG. 2, during the above-described treatment, the liquid sodium flowing from the pipe line 4 through the connecting pipe 10, the valve 41, and the inlet 8 into the internal space 35 of the case 31 flows between the meshes of the numerous filter elements 37. through the flow to the end 35a (flow velocity is, for example, 50 m/
time), is passed through the lotus tube 36 and sent out from the outlet 9 to the conduit 4 via the connecting tube 11 and valve 45.

In the above case, liquid sodium flows into the inlet 8 and ends at the end 3.
In the process of moving to 5a, it is cooled by the cooling means.

This cooling is performed to a temperature (for example, 120 oo to 150 oo) that does not solidify the liquid sodium. By cooling the liquid sodium in this way, impurities (02, Fe, Cd, P) dissolved in the liquid sodium are removed.
b, Sn, Se, Te, Sb, Bi, Ag, Ca, Mg
etc.) will precipitate as particles due to decreased solubility.
The precipitated particles are mechanically fixed and captured by the filter element 37. Furthermore, since the filter element 37 is magnetized, magnetic particles also magnetically affect the filter element 3.
7 and is captured. In this way, liquid sodium is purified by removing impurities. As mentioned above, while the cooled liquid sodium reaches the outlet 9 via the lotus tube 36, it exchanges heat with the liquid sodium that has flowed in from the inlet 8, and is warmed as well as the liquid that has flowed in. Cool the sodium. Therefore, improvement in thermal efficiency can be expected. In addition, in the above case, opening and closing of each valve, heater,
The coil of the electromagnet is energized as shown in "Processing" in Table 1 below. In the fast breeder reactor, first and second pipes are connected between the heat generating part and the heat receiving part, and liquid sodium as a coolant is transferred between the heat generating part, the first pipe, the heat receiving part, and the second pipe. If the sodium is circulated in this order from the heat generating section to the heat generating section, there is an advantage that when the fast breeder reactor is in operation, the liquid sodium can be circulated and reused to send thermal energy from the heat generating section to the heat receiving section.

Moreover, an impurity removal device was connected to the second pipe line, which cooled the liquid sodium, precipitated impurities dissolved in the liquid sodium as particles, and captured the precipitated impurity particles with a filter element. In some cases, during operation of the fast breeder reactor, the circulating liquid sodium can be purified, and the thermal energy transfer efficiency decreases due to a decrease in the purity of the liquid sodium, or the impurities are present in the heat generating part of the fast breeder reactor or This has the effect of preventing damage to heat receiving parts (furnace D, heat exchanger, evaporator, etc.) due to adhesion thereto.

Furthermore, even if an impurity removal device is attached to the pipe through which liquid sodium flows, the liquid sodium in the pipe is cooled to precipitate impurities, and the precipitated impurities are removed. If the impurity removal device is installed in the second pipeline through which the cooled liquid sodium flows after releasing thermal energy in the heat receiving section, the impurity removal device will install the liquid sodium in order to precipitate the impurities. When cooling, the liquid sodium can be cooled to a temperature at which impurities can be precipitated with a small amount of cooling energy, resulting in an energy-saving effect. In addition, when performing the above operation on the low-temperature liquid sodium in the second pipe line, the above-mentioned cooling in the impurity removal device may cause adverse effects on the cooling system, such as the heat of the cooling system. There is also an energy saving effect as energy losses can be kept to a minimum. Next, in the apparatus shown in FIG. 2, if a large amount of impurity particles precipitated by performing the purification process of the liquid sodium as described above adheres to the filter element 37, the particles are washed and regenerated.

This operation can be carried out in various ways as shown in "1" to "6" in Table 1. Table 1 For example, when only the gas in the tank 45 is used as the cleaning fluid, each operation is performed as indicated by ○× in "1" of Table 1.

Then, the gas in the tank 45 rapidly flows into the internal space 35 of the case 31 through the pressure feed pipe 50 and the inlet 8, blowing away impurity particles adhering to the filter element 37. The blown particles enter the tank 54 from the discharge port 32 through the discharge pipe 33 together with the gas. In the tank 54, the particles accumulate at the bottom of the tank 54, and the gas is exhausted from the exhaust pipe 55. In addition, when using only the liquid sodium in the tank 47 as the cleaning fluid, the first
Perform the operations as shown in "2" in the table.

Then, the gas in the tank 45 flows into the tank 47 via the pressure feed pipe 49, so the liquid sodium in the tank 47 passes through the pressure feed pipe 50 and the inlet 8, enters the internal space 35, and enters there at high speed (processing). The flow rate may be several times the flow rate during treatment, but if heating is also used, the flow rate may be approximately the same as the flow rate during treatment.) As the liquid sodium flows in this manner, impurity particles adhering to the filter element 37 are washed away by the liquid sodium and enter the tank 54 together with the liquid sodium. Furthermore, both the above gas and liquid sodium are used as the cleaning fluid, and the two are heated.
If so, perform the operations as shown in "6" in Table 1.

In this case, the above gas and liquid sodium are used in case 31.
A bubbling effect occurs in the process of flowing through the internal space 35 of
The effect of removing impurity particles from the filter element 37 is extremely high. In addition, since a high temperature fluid is used as described above (temperature that is high enough to dissolve impurity particles attached to the filter element, for example, 15,000 or higher), the impurity particles attached to the filter element begin to dissolve. Removal by fluid flow as described above (filter element 37
(separation from) is carried out more effectively. The cleaning gas and the cleaning liquid sodium may be pumped using, for example, pumps, instead of using pressurized gas as described above.

As described above, in the present invention, since an impurity removal device designed to remove impurities in liquid sodium is connected to the pipe, when the fast breeder reactor is operated, the circulating liquid sodium is The above thermal energy transfer efficiency decreases due to a decrease in the purity of liquid sodium, or the above impurities adhere to the heat generating part or heat receiving part (core, heat exchanger, evaporator, etc.) of a fast breeder reactor. It has the effect of preventing damage to the

When removing impurities using the filter element provided in the above impurity removal device, the filter element is magnetized by the magnetic field from the magnetic field generator, so it removes fine precipitates that cannot be removed by ordinary mechanical filters. can also be removed from the liquid sodium by adsorption by the magnetic force of the magnetic filter element, which has the effect of greatly increasing the degree of purification. Furthermore, the fact that impurities can be removed using magnetic force as described above has the advantage that it is possible to use a filter element with a coarse mesh.

Such a coarse filter element is easy to operate to clean impurities adsorbed therein. Furthermore, in the present invention, a cleaning fluid pumping device capable of pumping a cleaning fluid into the deposition section and the removal section of the device is connected to the inlet of the impurity removal device, and Since the outlet side of the device is provided with a discharge port for the above fluid,
When the efficiency of purifying the liquid sodium decreases due to a large amount of impurity particles trapped in the filter element of the removal section due to the operation, the impurity particles are washed away by flowing the cleaning fluid to the precipitation section and the removal section. This has the effect of making it possible to efficiently purify the liquid sodium by the impurity removing device again.

Moreover, in the case of the above-mentioned cleaning, since the cleaning liquid and the cleaning gas can be pumped into the case of the removal device, the bubbling effect between the liquid and the gas causes the cleaning to be carried out within the case. Impurities attached to the filter element can be removed from the filter element by an extremely large mechanical removal force, resulting in an extremely high cleaning effect.

Furthermore, since both the cleaning liquid and the cleaning gas can be heated to zero, when the filter element is cleaned by bubbling action as described above, an even higher cleaning effect can be achieved.

That is, first, the hot cleaning liquid comes into contact with the impurities adhering to the filter element, so that the heat contained in the cleaning liquid heats and dissolves the impurities, and then,
The cleaning liquid, which has become lukewarm due to the energy used to melt it, is separated from the dissolved and undissolved impurities by the bubbling action of the high-temperature gas, and during this time, the high-temperature gas also removes the dissolved impurities. By contacting the impurity, the impurity is continuously heated and its dissolution is captured, and the next flowing high temperature cleaning liquid is brought into contact with the impurity again to continue heating and dissolving the impurity. It is possible to repeat the action of causing
It has the effect of making the cleaning effect extremely high.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a system diagram of a fast breeder reactor, and FIG. 2 is a schematic vertical cross-sectional view of an impurity removal device equipped with a cleaning system. 1... Nuclear reactor, 2... Heat exchanger, 15
...Evaporator, 3,16...First pipe line, 4,1
7... Second pipe line, 7, 20... Impurity removal device, 44... Cleaning fluid pumping device. Figure 1

Claims (1)

[Claims] 1. Between the heat generating section and the heat receiving section in a fast breeder reactor, there is a first pipe line that sends the liquid sodium heated up in the heat generating section to the heat receiving section, and a first pipe line that sends the liquid sodium that has become low temperature in the heat receiving section to the heat generating section. The liquid sodium is circulated in the order of the heat generating part, the first pipe, the heat receiving part, the second pipe, and the heat generating part, and in the process of the circulation. In the cooling and purification system of a fast breeder reactor, which sends thermal energy from the heat generating part to the heat receiving part,
The inlet and outlet of an impurity removing device designed to remove impurities in liquid sodium are connected to the liquid sodium transferred through the pipe line to the impurity removing device, and the liquid sodium leaving the impurity removing device to be transferred to the impurity removing device. The impurity removal device is connected to each of the pipelines so as to be able to be returned to the pipeline, and the impurity removal device includes a hollow case that allows liquid sodium to flow from an inlet to an outlet, and a hollow case that cools the liquid sodium that flows inside the case. a cooling means configured to precipitate impurities dissolved in the liquid sodium as particles; and a filter made of a magnetic material disposed within the case and configured to capture impurity particles precipitated in the liquid sodium. and a magnetic field generator configured to magnetize the filter element, further comprising a tank configured to pump a cleaning liquid into the case at the inlet of the case of the impurity removal device, and a case. The tank is connected to a tank capable of pumping the cleaning gas inward, and each tank is provided with a heating means for heating the cleaning liquid and the cleaning gas, respectively, and on the other hand,
An outlet for discharging the cleaning liquid and cleaning gas is provided at the outlet of the impurity removal device, and the cleaning liquid and cleaning gas are pumped from the cleaning liquid tank and the cleaning gas tank into the case of the impurity removal device. Cooling and purification of a fast breeder reactor, characterized in that a cleaning liquid and a cleaning gas are distributed in the case in a mixed state, and the distributed cleaning liquid and cleaning gas are discharged from the discharge port. system.