JPH0361155B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to liquid metal cooled nuclear reactors, and more particularly to partitions of each liquid metal plenum.

[Technical background of the invention]

FIG. 1 is a diagram schematically showing the inside of a reactor vessel of a conventional liquid metal cooled nuclear reactor.

In a liquid metal cooled nuclear reactor, a pump 3 and an intermediate heat exchanger 2 are arranged in a tank-shaped reactor vessel 1 in addition to a reactor core 4 disposed in the lower center.

These devices create a high-temperature plenum 6, which is a liquid metal region above the reactor core 4, inside the reactor vessel 1.
, a low-temperature plenum 7 which is a liquid metal region on the outlet 14 side of the intermediate heat exchanger 2, an intermediate plenum 5 which is a liquid metal region forming a partition between the high-temperature plenum 6 and the low-temperature plenum 7, and an outlet 18 side of the pump 3. The high pressure plenum 9 is a liquid metal region below the core 4, and the intermediate pressure plenum 10 is a liquid metal region below the high pressure plenum 9.

Liquid metal is sent from pump 3 through pump outlet 18 and duct 19 to core 4 through high pressure plenum 9 in the lower core.

The liquid metal is heated in the reactor core 4 and reaches the high temperature plenum 6.

The high-temperature liquid metal enters the intermediate heat exchanger 2, where it exchanges heat and is cooled.

The cooled liquid metal flows from the intermediate heat exchanger outlet 14 into the cold plenum 7 and back into the pump inlet 12.

In this way, liquid metal circulates within the furnace vessel.

In the figure, reference numeral 15 is a roof slab on which the pump 3 and the intermediate heat exchanger 2 are suspended, which forms the upper cover of the reactor vessel 1, 11 is a concrete wall, and 16 and 17 are the intermediate heat exchanger 2, respectively. coolant inlet and outlet ducts.

[Problems with background technology]

Since the liquid metal within the reactor vessel 1 is divided as described above, when charging the liquid metal, it must be charged from several locations.

In addition, the charge position, order, etc. must be considered in order to reduce thermal stress and prevent gas accumulation.

Furthermore, when the pumps are stopped due to an accident, etc., the high-temperature plenum and the low-temperature plenum become independent, causing problems such as the core being unable to be cooled by natural circulation.

[Purpose of the invention]

The present invention has been made to solve the above problems, and the first object is to cool the liquid metal so that it can be charged from any part without causing gas accumulation when charging the liquid metal into the furnace vessel. The purpose is to provide nuclear reactors.

A second object is to provide a liquid metal cooled nuclear reactor in which the core can be cooled by natural circulation of liquid metal within the reactor vessel when the pumps are stopped.

[Summary of the invention]

The present invention provides a tank-type fast breeder reactor between a low-temperature plenum at the outlet of an intermediate heat exchanger disposed in a reactor vessel, a high-pressure plenum at the lower part of the core, and a partition between the intermediate plenum and a partition area around the core. It is a liquid metal cooled nuclear reactor characterized by having check valves installed at each side, which allows for smooth charging of liquid metal, and allows cooling of the reactor core through natural circulation when the coolant flow rate is lost. It can be carried out.

[Embodiments of the invention]

The present invention will be described in detail below with reference to the drawings.

FIG. 2 is an enlarged sectional view of the main parts of the core periphery of an embodiment of the liquid metal cooled nuclear reactor according to the present invention. The same parts as in FIG. Omitted.

That is, between the high-pressure plenum 9 located at the lower part of the core 4 and connected to the outlet 18 side of the pump 3 and the low-temperature plenum 7 connected to the intermediate heat exchanger outlet 14 side, and between the grown area 8 around the core 4 and Low temperature plenum 7
between the intermediate plenum 5 and the low temperature plenum 7, which are partition walls between the high temperature plenum 6 and the low temperature plenum 7, between the high pressure plenum 9 and the intermediate pressure plenum 10 located below it, and between the intermediate pressure plenum 10 and the low temperature plenum 9. Five valves, such as check valves 20, 21, 22, 23, and 24, are provided between the plenum 7 and the plenum 7, respectively.

These five check valves 20, 21, 22, 23,
24 is normally opened by a spring, and is closed when pressure is applied to one side.

Next, the effect will be explained.

Before the reactor starts operating, liquid metal is charged into the reactor vessel 1.

At this time, five check valves 20, 21, 22, 2
Since the high temperature plenum 6 and the low temperature plenum 7 are kept open by the springs 3 and 24, the middle plenum 5 and the low temperature plenum 7 are closed by the check valve 21.
The high pressure plenum 9 and the medium pressure plenum 10 are connected to each other by the check valve 22, and the medium pressure plenum 1 is connected to the medium pressure plenum 1 by the check valve 23.
0 and the low-temperature plenum 7 are connected by check valves 24, so no matter which plenum the liquid metal is charged from, it is sequentially charged from the lower end of the furnace vessel, preventing gas accumulation and reducing thermal stress. With less bias, liquid metal can be charged more accurately and safely.

When the nuclear reactor starts operating, the pump 3 starts and a pressure difference occurs in each plenum.

The high pressure plenum 9 on the outlet 18 side of the pump 3 has the highest pressure, and the liquid metal is sent to the reactor core 4.

Due to the power loss in the core 4, the pressure becomes slightly lower and flows into the hot plenum 6.

from the high temperature plenum 6 into the intermediate heat exchanger 2;
This pressure loss in the intermediate heat exchanger 2 further lowers the pressure, which flows into the low-temperature plenum 7.

Since this low-temperature plenum 7 is connected to the pump inlet side, it becomes the plenum with the lowest pressure.

Further, since liquid metal does not flow through the intermediate plenum 5, it is not subjected to pressure from the pump.

Further, as shown in the figure, the entrance nozzle 27 of the fuel assembly 26 is located in the high-pressure plenum 9, and in order to prevent the fuel assembly 26 from floating due to the pressure of the pump 3, its lower end is connected to the intermediate-pressure plenum 10. The fuel assembly 2 is inserted into the fuel assembly 2 due to the pressure difference between the high pressure plenum 9 and the intermediate pressure plenum 10.
The lower end of 6 is pressed against the partition wall 25.

Therefore, the high pressure plenum 9 has the highest pressure, followed by the intermediate pressure plenum 10, the high temperature plenum 6, the intermediate plenum 5, and the low temperature plenum 7, which have lower pressures in this order.

During operation, due to the pressure difference between the above plenums, the check valve 20 between the high pressure plenum 9 and the low temperature plenum 7, the check valve 21 between the recessed area 8 around the core 4 and the low temperature plenum 7, the intermediate plenum 5 and The check valve 22 between the low-temperature plenum 7, the check valve 23 between the high-pressure plenum 9 and the medium-pressure plenum 10, and the check valve 24 between the medium-pressure plenum 10 and the low-temperature plenum 7 are in a closed state. ing.

In addition, if the pump 3 is stopped during fuel exchange, main cooling system accident, power loss accident, etc., the pressure difference between each plenum will be almost eliminated, so the check valves 20, 21, 22, 23, and 24 are operated by springs. , it becomes open.

Therefore, the high pressure plenum 9, the intermediate pressure plenum 10, and the low temperature plenum 7 are in communication, so that the liquid metal is heated in the core 4 and rises to the high temperature plenum 6, is cooled by the intermediate heat exchanger 2, and descends to the low temperature plenum 7. do.

That is, the cooled liquid metal in the low-temperature plenum 7 passes through the check valves 23, 24, or 20 to cool the core, thereby performing core cooling by natural circulation.

The check valves 21 and 22 are also opened, but since the air does not pass through the core 4, no upward flow occurs and no natural circulation occurs.

Also, using gas-operated valves, electric valves, solenoid valves, etc.
It is also possible to make it work in conjunction with the pump 3 or a flow meter.

FIG. 3 partially shows another embodiment of the present invention in which a check valve is installed between the high pressure plenum 9, the cultivation area 8, the intermediate plenum 5, and the low pressure plenum 7. This shows the check valve status during reactor operation.

That is, since there is a pressure difference between the high pressure plenum 9 and the low pressure plenum 7, the spring 3 of the check valve 29
0 is pushed by the pressure difference, and the check valve 29 is in a closed state.

Therefore, there is no flow of liquid metal between the high pressure plenum 9, the cultivation area 8, the intermediate plenum 5, and the low temperature plenum 7, and the liquid metal flows from the high pressure plenum 9 to the entrance nozzle 27 to the fuel assembly 26.
Only the flow path through which flow flows to the hot plenum is in communication.

When replacing fuel or when the pump is stopped due to an accident in the main cooling system, power loss, etc., the pressure difference between each plenum is almost eliminated, so the check valve 29 is opened by the spring 30, and the high-pressure plenum 9 and the cultivation area 8 are opened. , the intermediate plenum 5 and the low temperature plenum 7 communicate with each other.

That is, the check valve 29 is pushed by the spring 30 and moves to the right in the figure, so that the intermediate plenum 5
The high-pressure plenum 9 communicates with the slide section 38 which is in communication via the check valve hollow part 32 and the check valve hole 34, and the communication hole 33 is opened, so that the formation section 8 and the partition wall hole are in communication with each other. 35, the check valve hollow 32, which communicates with the intermediate plenum 5, and the inlet 39 of the cold plenum 7 each communicate with each other.

Therefore, charging to each plenum is performed smoothly.

Natural circulation occurs due to communication between each plenum,
Core cooling is performed.

The flow path of liquid metal from the low-temperature plenum 7 to the core is as follows.

The liquid metal in the cold plenum 7 flows from the inlet 39 through the through hole 33 into the check valve hollow 32 and further through the check valve hole 34 into the sliding area 38, where it flows between the check valve 29 and the valve seat 36. It is led to the high pressure plenum 9 through the gap.

From the high pressure plenum 9, it enters the fuel assembly 26 through the entrance nozzle orifice 28 and reaches the core 4.

Further, when the pump is activated and a pressure difference is generated between the low pressure plenum and the high pressure plenum, liquid metal flows at a high flow rate through the check valve orifice of the check valve 29, so that the check valve 29 moves in the opening direction of the spring 30. It closes when it receives a closing force that is greater than the closing force.

This provides only the above-mentioned advantages without interfering with normal reactor operation.

〔Effect of the invention〕

As detailed above, according to the present invention, gas accumulation can be prevented and thermal stress can be suppressed when charging liquid metal to a reactor vessel, and liquid metal can be charged more reliably and safely. It is possible to provide a highly reliable liquid metal cooled nuclear reactor that can cool the reactor core by natural circulation and does not require charging specific parts such as the intermediate plenum.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a conventional liquid metal cooled nuclear reactor, and FIG. FIG. 3 is a longitudinal sectional view showing a check valve used in a liquid metal cooled nuclear reactor according to the present invention. 1...Reactor vessel, 2...Intermediate heat exchanger, 3...
...Pump, 4...Core, 5...Intermediate plenum, 6
...High temperature plenum, 7...Low temperature plenum, 8...
Cultivation area, 9... High pressure plenum, 10... Medium pressure plenum, 11... Concrete wall, 12... Pump inlet, 13... Intermediate heat exchanger inlet, 14... Intermediate heat exchanger outlet, 15... Roof slab, 16...
...Intermediate heat exchanger cooling sodium outlet duct, 17
...Intermediate heat exchanger cooling sodium inlet duct, 1
8...Pump outlet, 19...Duct, 20,2
1, 22, 23, 24... Check valve, 25... Partition wall, 26... Fuel assembly, 27... Entrance nozzle, 28... Entrance nozzle orifice, 29... Check valve, 30... Spring, 31
...Slide ring, 32...Check valve hollow part, 3
3... Conduction hole, 34... Check valve hole, 35... Bulkhead hole, 36... Valve seat, 37... Conduction area, 38...
Slide area, 39...inflow section.

Claims (1)

[Claims] 1. A main container with an open top containing liquid metal;
A liquid metal layer is formed between a reactor core disposed within the main vessel, an internal tank for accommodating the reactor core by forming a cultivation area around the core within the main vessel, and the internal tank. an intermediate tank that accommodates the internal tank; an intermediate heat exchanger that penetrates the internal tank and the intermediate tank and is installed at a distance around the core; 1 placed on a circle
A secondary system pump, a first lower tank installed at the bottom of the core that is connected to the outlet piping of this primary system pump and serves as an inlet for the liquid metal in the reactor core, and a first lower tank installed at the bottom of this first lower tank. In a liquid metal cooled nuclear reactor, the liquid metal in the first lower tank is pushed out by a pump and is under high pressure (high pressure plenum). ) and a portion of the cooled liquid metal (cold plenum) outside the first lower tank and at the bottom of the main vessel and on the exit side of the intermediate heat exchanger or core cooling system. A liquid metal cooled nuclear reactor characterized by being provided with. 2. The liquid metal cooled nuclear reactor according to claim 1, characterized in that a valve is provided between the low-temperature plenum and a cultivation area in which liquid metal around the core is stagnant. 3. The liquid metal cooled atom according to claim 1, characterized in that a valve is provided between the region where the liquid metal is stagnant (intermediate plenum) between the inner tank and the intermediate tank and the low-temperature plenum. Furnace. 4. Liquid metal cooling according to claim 1, characterized in that a valve is provided between the liquid metal region (intermediate pressure plenum) in which the pressure in the second lower tank is lowered and the low temperature plenum. Reactor. 5 Claim 1 characterized in that a valve is provided between the high pressure plenum and the intermediate pressure plenum.
Liquid metal cooled nuclear reactor as described in Section. 6. The liquid metal cooled nuclear reactor according to claim 1, wherein five valves are provided, and a plurality of the valves are opened and closed in conjunction with each other. 7. The liquid metal cooled nuclear reactor according to claim 1, wherein the five valves are opened and closed in conjunction with a pump or a flow meter.