JPS6148875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary core cooling device for a liquid metal cooled fast breeder reactor.

In general, fast breeder reactors use a liquid metal such as liquid sodium as the primary coolant flowing through the reactor core, and this primary coolant is heat exchanged with a secondary coolant such as liquid sodium in an intermediate heat exchanger. This secondary coolant is configured to exchange heat with water in a steam generator to generate steam. by the way,
Since decay heat is generated in the core of a nuclear reactor after it is shut down, an auxiliary core cooling device is provided to remove this heat during shutdown. This auxiliary core cooling system has conventionally been constructed as shown in FIG. 1, for example. That is, numeral 1 in the figure is a reactor vessel, the upper end of which is closed with a shielding plug 2. A reactor core 3 is housed within this reactor vessel 1 . A primary coolant 4 such as liquid sodium is distributed within the reactor vessel 1, and 5 is a hot leg pipe for the primary coolant 4;
6 is cold leg piping. In order to remove the decay heat of the core 3 during shutdown, an auxiliary core cooling device 7 is provided. 8 is the cooler, which is provided outside the reactor vessel 1.
Further, 9 is a heat exchanger, which is immersed in the primary coolant 4 inside the reactor vessel 1. The heat exchanger 9 and the cooler 8 are communicated through circulation pipes 10, 10, and a circulation pump 11 is provided in the middle of the circulation pipes 10, 10. A heat medium such as a primary coolant 4 is provided in the circulation pipes 10, 10.
Contains the same liquid sodium. This heat medium is circulated by the circulation pump 11, and the heat medium that has exchanged heat with the primary coolant 4 in the heat exchanger 9 is sent to the cooler 8, where it is cooled by air sent by the blower 12. The decay heat is returned to the heat exchanger 8, thereby removing the decay heat of the core 3. Further, FIG. 2 shows another type of auxiliary core cooling system 7', in which the circulation pipes 10', 10 are branched and connected to the hot leg pipe 13 and cold leg pipe 14 of the secondary coolant circulation system, The configuration is such that high-temperature secondary coolant is taken out from the hot leg piping 13 and cooled by a cooler 8, and the cooled secondary coolant is returned to the cold leg piping 14. The parts in FIG. 2 that correspond to those in FIG.
is a secondary pump, 19 is a water supply pipe, and 20 is a steam pipe. By the way, the above-mentioned auxiliary core cooling devices 7, 7'
In order to increase reliability, the reactor is configured so that even if the circulation pump 11 is stopped, the heat medium can be circulated only by natural convection to remove heat from the core. For this reason, even during operation of the nuclear reactor, the heat medium circulates by natural convection, resulting in a problem that the thermal efficiency of the reactor decreases. For this reason, in the conventional system, when the auxiliary core cooling devices 7, 7' are not operated, the cooler 8 is heated to prevent natural convection from occurring in order to prevent temperature differences. However, in this case, a large amount of electric power is consumed to heat the cooler 8, resulting in a problem that the efficiency of the reactor eventually decreases. In addition, circulation pipes 10, 10, 10',
10', and if the auxiliary core cooling system is not used, it is possible to close this isolation valve and stop the circulation of the heat medium. If liquid sodium similar to the above is used, this heating medium will solidify in the cooler 8, so the cooler 8 will end up being
There was a problem that required heating.

The present invention was made based on the above circumstances, and its purpose is to improve the thermal efficiency of the nuclear reactor by stopping the circulation of the heat medium during operation of the nuclear reactor, and to eliminate the need for heating the cooler, etc. The goal is to obtain an auxiliary core cooling system that does not require

The present invention will be described below with reference to embodiments shown in the drawings. 3 and 4 show a first embodiment of the invention. In the figure, 101 is a nuclear reactor vessel, and the upper end of this reactor vessel 101 is closed by a shielding plug 102. A reactor core 103 is housed within this reactor vessel 101 . In this reactor vessel 101, the reactor core 103 is
A primary coolant 104, such as liquid sodium, is configured to flow through it. This nuclear reactor is provided with an auxiliary core cooling device 106, the configuration of which will be described below. In the figure, 107 is a heat exchanger, which is housed in the reactor vessel 101 and immersed in the primary coolant 104. Further, a cooler 108 is provided outside the reactor vessel 101. The cooler 108 and the heat exchanger 107 are communicated through circulation pipes 109, 109, which pass through the shielding plug 102 in an airtight manner. Further, a circulation pump 110 is provided in the middle of the circulation pipe 109. And this circulation pipe 109,
109, a heat medium 111 is sealed in the cooler 108 and the heat exchanger 107, and this heat medium 1
11 uses liquid sodium similar to the above-mentioned primary coolant 104. Moreover, 112 is a blower and is configured to send the cooling air. The heat medium 111 is circulated between the heat exchanger 101 and the cooler 108 by the circulation pump 110, and the heat exchanger 107 circulates the heat medium 111 to the primary coolant 104.
It is configured to exchange heat with the cooling air in the cooler 108, cool it, and return to the heat exchanger 107, and is configured to remove decay heat generated in the reactor core 103 when the reactor is shut down. There is. Also,
113 is a heat medium storage tank, which has an internal volume larger than the internal volume of the cooler 108,
Its upper end opening is closed by a lid 114. The heat medium storage tank 113 communicates with the circulation pipe 109 via a communication pipe 115.
Further, an exhaust tank 1 is provided above the cooler 108.
16 are in communication with each other, and the upper end opening is connected to the lid body 117.
is blocked by. A gas supply/discharge mechanism 118 is connected to the heat medium storage tank 113 and the exhaust tank 116. This gas supply/exhaust mechanism 118 supplies gas such as argon into the heat medium storage tank 113 and the exhaust tank 116, or exhausts the gas inside these, and is used during operation of the reactor, that is, as an auxiliary core cooling system. If 106 is not used, exhaust tank 116
The heat medium storage tank 11
Exhaust the gas in the cooler 108 by gravity.
The heat medium storage tank 1 is removed by removing the heat medium 111 in the heat medium storage tank 1.
When the reactor is shut down, that is, when the auxiliary core cooling device 106 is used, gas is supplied to the heat medium storage tank 113 and the gas in the exhaust tank 116 is exhausted to cool the heat medium storage tank. The pressure on the 113 side is high and the pressure on the exhaust tank 116 is low, and this pressure difference causes the heat medium storage tank 113 to
It is configured to push out the heat medium 111 inside and fill it into the cooler 108. Note that the surplus heat medium 111 in this case is configured to accumulate in the exhaust tank 116. Further, the outer circumferential surfaces of the heat medium storage tank 113 and the circulation pipes 109, 109 are covered with a heat insulating material 119 to prevent heat from dissipating from these surfaces and to keep the heat medium 111 inside them warm. Configured to prevent clotting. In addition, in this first embodiment, the heat medium storage tank 113 is provided below the cooler 108, so when the heat medium 111 is removed from the cooler 108, the heat medium storage tank 113 is removed from the exhaust tank 116 side and the heat medium storage tank. 113 side, the heat medium 111 is removed by gravity, and the cooler 10
When filling the heat medium 111 into the cooler 108, the heat medium storage tank 113 side is set to high pressure, and the exhaust tank 116 side is set to low pressure, and the heat medium 111 is filled into the cooler 108 by this pressure difference. However, when the heat medium storage tank 113 is located above the cooler 108, the heat medium 11 is stored in the cooler 108.
1, the pressure relationship between the heat medium storage tank 113 side and the exhaust tank 116 side is configured to be the opposite of the above, and the heat medium storage tank 113 is approximately equal to the cooler 108. If they are at the same height, the pressure on the heat medium storage tank 113 side is low when removing the heat medium 111 from the cooler 108, and the pressure on the exhaust tank 116 side is low when filling the heat medium 111 into the cooler 108, due to the differential pressure. The heat medium 111 is supplied to and discharged from the cooler 108. Furthermore, when the heat medium 111 is removed from the cooler 108, the gas supply/discharge mechanism 118 maintains the same pressure difference between the heat medium storage tank 113 side and the exhaust tank 116 side, and the exhaust tank 116 side. That is, the cooler 10
It is constructed so that the inside of the chamber 8 can be evacuated to a vacuum.

The first embodiment of the present invention configured as described above is used when the nuclear reactor is shut down, that is, when this auxiliary core cooling system 10
6 is used, the gas in the exhaust tank 116 is exhausted by the gas supply and exhaust mechanism 118, and the gas is supplied into the heat medium storage tank 113, and the exhaust tank 116 side is kept under low pressure and the heat medium storage tank 113 is
As shown in FIG. 4, the heat medium 111 in the heat medium storage tank 113 is pushed out by this differential pressure, and the heat medium 111 is filled into the cooler 108. Then, the circulation pump 110 is operated to circulate the heat medium 111 between the cooler 108 and the heat exchanger 107 via the circulation pipes 109, 109. Therefore, this heat medium 111 is heat exchanged with the primary coolant 104 in the reactor vessel 101, and the high temperature heat medium 111 is exchanged with the cooling air sent by the blower 112 in the cooler 108, so that the temperature becomes low. The heat medium 111 is returned to the heat exchanger 107, and decay heat generated in the core 103 is removed by circulation of the heat medium 111. In addition, if the circulation pump 110 or the like fails, the heat medium 111 is circulated by natural convection due to the temperature difference between the heat medium 111 in the heat exchanger 107 and the cooler 108, and the heat removal function of the core 103 is maintained. do. When the reactor is in operation, that is, when this auxiliary core cooling device 106 is not used, the gas in the heat medium storage tank 113 is exhausted and the gas is supplied into the exhaust tank 116. The pressure on the exhaust tank 116 side and the exhaust tank 116 side are made to be approximately the same pressure. Therefore, as shown in FIG. 3, the heat medium 111 is removed from the cooler 108 by gravity, and the heat medium 111 removed from the cooler 108 is stored in the heat medium storage tank 113. . Further, from this state, the gas in the exhaust tank 116 and the heat medium storage tank 113 is exhausted while maintaining the same pressure relationship between the pressures on the heat medium storage tank 113 side and the exhaust tank 116 side, and the gas inside these tanks and the cooler 108 is exhausted. Make a vacuum inside. Therefore, the heat medium 111 is divided at the cooler 108, so no natural convection occurs, and therefore the heat generated in the reactor core 103 during operation is not dissipated from the cooler 108, and the reactor There is no reduction in thermal efficiency. Also, in this state,
The heat medium 111 is accommodated in the circulation pipes 109, 109 and the heat medium storage tank 113, and since the circulation pipes 109, 109 and the heat medium storage tank 113 are covered with a heat insulating material 119, these The internal heat medium 111 is kept warm. In addition, in this state, the heat medium 111 in the cooler 108
is excluded, so even if the circulation of the heat medium 111 is stopped, the heat medium 111 remains in the cooler 108.
will not solidify, and the cooler 10 will not solidify.
There is no need to heat 8. Yotsutoko cooler 10
8. Does not require electricity for heating. There is no decrease in the thermal efficiency of the reactor equipment as a whole. Also, in this state, the inside of the cooler 108 is evacuated to create a vacuum, so
No gas convection occurs within the cooler 108, and heat dissipation is reliably prevented.

Note that the present invention is not limited to the first embodiment described above.

For example, FIG. 5 shows a second embodiment of the present invention. In this second embodiment, a heat medium storage tank 213 is provided in the primary coolant 104 in the reactor vessel 101, and gas at a predetermined pressure is sealed in the heat medium storage tank 213. The second embodiment has the same structure as the first embodiment except for the above-mentioned points, and the same reference numerals are given to the parts corresponding to those of the first embodiment in FIG. 5, and the explanation thereof will be omitted. Note that 220 is a primary coolant inflow pipe, and 221 is a primary coolant outflow pipe. In this second embodiment, the gas in the exhaust tank 213 is supplied and discharged by a gas supply/discharge mechanism 218, and the cooler 108 is used as in the first embodiment.
The heat medium 111 inside is removed and filled. Also, during the operation of the nuclear reactor, the primary coolant 1 in the reactor vessel 101 is
04 rises above a predetermined temperature, the gas sealed in the heat medium storage tank 213 expands and pushes out the heat medium 111 in the heat medium storage tank 213, causing the heat medium to flow into the cooler 108. 1
11 is filled and the heat medium 111 is circulated by natural convection, which can automatically remove heat and can also operate as a core cooling system in an emergency.

Furthermore, the present invention is not limited to the above embodiments.

For example, an exhaust tank is not necessarily required, and a gas supply and exhaust mechanism may be directly connected to the upper part of the cooler.

Further, the gas supply/exhaust mechanism does not need to have a function of evacuating the inside of the cooler in a state in which the heat medium is removed from the cooler.

As described above, the present invention provides a heat medium storage tank connected to a circulation pipe for circulating a heat medium through a cooler, and also provides a gas supply and exhaust mechanism above the cooler.
When the reactor is shut down, gas is supplied into the cooler to remove the heat medium in the cooler into the heat medium storage tank, and when the reactor is shut down, the gas in the cooler is discharged to remove the heat medium from the cooler. A heating medium is filled inside. Therefore, since the inside of the cooler is empty during reactor operation, the heat medium does not circulate through natural convection, and heat generated in the core is prevented from escaping via this auxiliary core cooling device. is,
The thermal efficiency of the nuclear reactor can be improved. Also,
Since the inside of the cooler is empty during operation, the heat medium does not solidify inside the cooler, and there is no need to heat the cooler. Therefore, there is no need for electric power for heating the cooler, and the overall thermal efficiency of the reactor does not deteriorate, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional example, and FIG. 2 is a schematic configuration diagram of another conventional example. 3 and 4 show a first embodiment of the present invention, in which FIG. 3 is a vertical cross-sectional view in a nuclear reactor operating state, and FIG. 4 is a vertical cross-sectional view in a nuclear reactor shutdown state. Further, FIG. 5 is a schematic configuration diagram of the second embodiment. 101...Reactor vessel, 103...Reactor core, 10
4...Primary coolant, 107...Heat exchanger, 108
... Cooler, 109 ... Circulation pipe line, 111 ... Heat medium, 113 ... Heat medium storage tank, 116 ...
Exhaust tank, 118... Gas supply and exhaust mechanism, 213...
...heat medium storage tank, 309...circulation pipe, 40
9...Circulation pipe line, 424...Intermediate heat exchanger, 42
5...Steam generator.

Claims (1)

[Claims] 1. A cooler provided outside the reactor vessel, a circulation pipe for circulating a liquid heat medium between the cooler and the reactor vessel or the coolant passage, and a circulation pipe communicating with the circulation pipe for the cooling. A heat medium storage tank having a volume larger than the internal volume of the reactor is connected to the above-mentioned cooler, and when the reactor is operating, gas is supplied into this cooler and the heat medium in this cooler is transferred to the above-mentioned heat medium storage tank. 1. An auxiliary core cooling device comprising: a gas supply/discharge mechanism for discharging gas from the cooler and filling the inside of the cooler with the heat medium when the reactor is shut down.