JPH0579157B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention eliminates the secondary cooling system in a fast breeder reactor plant and connects the reactor vessel and steam generator directly through a coolant. This invention relates to a cooling system that performs heat exchange.

(Prior technology) The cooling system of a fast breeder reactor uses liquid sodium as a coolant to extract heat from the reactor vessel.The liquid sodium cooling system of a conventional fast breeder reactor plant consists of a primary cooling system and a secondary cooling system. The system consisted of two cooling systems.

The cooling system of a conventional fast breeder reactor plant will be explained below with reference to FIG.

Referring to the figure, a system that circulates a primary coolant such as liquid sodium between the reactor vessel 1 and the intermediate heat exchanger 2 is a primary cooling system A. Further, a secondary cooling system B is a system that circulates a secondary coolant such as liquid sodium between the intermediate heat exchanger 2 and the steam generator 3.

High temperature primary coolant is sent from inside the reactor vessel 1 to the intermediate heat exchanger 2 via the outgoing pipe line 4 of the primary cooling system A. In the intermediate heat exchanger 2, the secondary coolant in the secondary cooling system B receives heat from the primary cooling system A, and in the primary cooling system, the primary coolant whose temperature has decreased by releasing heat is transferred to atoms via the return pipe 5. It is returned to the furnace vessel 1. The secondary coolant that has received heat in the intermediate exchanger 2 is sent to the steam generator 3 via the pipeline of the secondary cooling system B. In the steam generator 3, the water sent through the pipe line 7 receives heat from the secondary cooling system B, evaporates, and becomes steam.
This steam is sent to a power generation turbine (not shown).

In this way, in the conventional cooling system, the secondary cooling system B is interposed between the primary cooling system A, which takes out the coolant from the reactor vessel 1, and the steam generator 3.

The reason why the secondary cooling system B is provided is as follows.

If the heat transfer tube 8 in the steam generator 3 is damaged for some reason, the sodium coolant and water react to generate hydrogen. This hydrogen becomes bubbles and mixes into the coolant, and if these hydrogen bubbles flow into the reactor core 9 in the reactor vessel 1, the nuclear reaction in the reactor core 9 will be excessively promoted and the stable operation of the reactor will be maintained. The fuel may run out or the fuel may be locally damaged. When the secondary cooling system B is present, the heat exchanger tube 8
Even if the cooling system B is damaged, the hydrogen bubbles only circulate through the pipes of the secondary cooling system B, and the hydrogen bubbles do not enter into the nuclear reactor vessel 1 via the primary cooling system A.

(Problems to be Solved by the Invention) However, when a secondary cooling system is interposed in the cooling system, thermal efficiency is sacrificed and the plant becomes complicated and large.

In order to improve the thermal efficiency of fast breeder reactors, downsize the plant, and reduce construction costs, it is necessary to create a cooling system that eliminates the secondary cooling system. A prerequisite for this is that a means is provided to prevent coolant containing hydrogen bubbles from flowing into the reactor vessel through the cooling system piping even if the steam generator heat transfer tubes are damaged. Become.

An object of the present invention is to provide a cooling system that eliminates the secondary cooling system of a fast breeder reactor, which can prevent hydrogen bubbles from entering the reactor vessel even if a heat transfer tube of a steam generator is damaged.

(Configuration of the present invention) In order to achieve the above object, the present invention is configured as follows.

A cooling pipe line in which a secondary cooling system consisting of an outgoing pipe line that sends coolant from the reactor vessel to the evaporator and a return line that returns the coolant from the evaporator to the reactor vessel is removed; a pump provided in the return pipe; a rotating body having a substantially cylindrical shape on an inner wall of a side surface and provided in the return pipe; A gas-liquid separation device having an inlet pipe, a gas-liquid outlet pipe provided at approximately the center of the upper surface of the rotating shell, and an outlet pipe provided on the rotating shell and connected to the return pipe; The present invention is configured to include a communication pipe line that connects the gas-liquid outlet pipe of the gas-liquid separation device and a coolant tank.

(Example) An example of the present invention will be described below in Figures 1 to 4.
This will be explained with reference to the figures.

Referring to FIG. 1, a reactor core 9 is placed in a reactor vessel 1 immersed in a coolant such as liquid sodium. An outgoing pipe line 4 is provided to send high-temperature coolant from the reactor vessel 1 to the evaporation generator 3, and a return pipe line 5 is provided to return the coolant to the reactor vessel 1 after heat exchange in the steam generator 3. is provided. The return pipe 5 is provided with a pump 10 that circulates the coolant.

A pipe line 7 for sending water to the steam generator 3 is provided, and the water flowing through the pipe line 7 is transferred to a heat transfer tube 8 in the steam generator 3.
The coolant receives heat from the high-temperature coolant, evaporates into steam, is further superheated, and is sent to the load side, such as a power generation turbine (not shown).

The cooling system that directly sends the coolant in the reactor vessel 1 to the steam generator 3 for heat exchange in this manner is referred to as a cooling system that eliminates the secondary cooling system.

When the heat exchanger tube 8 is damaged for some reason, water and sodium react to generate hydrogen, which becomes bubbles and mixes into the coolant. If these hydrogen bubbles enter the reactor vessel 1 through the return pipe 5 and flow into the reactor core 9, the nuclear reaction in the reactor core 9 will be excessively promoted, making it impossible to maintain stable operation of the reactor.
Local fuel damage may occur. Therefore,
A gas-liquid separation device is required to prevent hydrogen bubbles from entering the reactor vessel 1. In the present invention, this gas-liquid separation device is configured as follows.

In this embodiment, in the return pipe line 5, the pump 10
Although the gas-liquid separation device 11 is provided between the steam generator 3 and the reactor vessel 1, it may also be provided between the steam generator 3 and the pump 10. The gas-liquid separation device 11 includes a rotating body 12, an inlet pipe 13 provided on the rotating body 12, and a gas-liquid outlet pipe 1.
4, and an outlet pipe 15.

The inner wall 17 of the side surface portion 16 of the rotating body 12 has a substantially cylindrical shape. The inlet pipe 13 is provided approximately tangentially to the side surface 16 of the rotating trunk 12, and is connected to the return pipe 5.
It is connected to the. The gas-liquid outlet pipe 14 is connected to the rotating body 1
2, and is connected to a communication pipe 20 that communicates with a coolant tank 19 such as an overflow tank. Outlet pipe 15
is provided substantially in the tangential direction of the side surface portion 16 of the rotating trunk 16 and is connected to the downstream side of the connecting portion of the return pipe 5 to the inlet pipe 13 .

Since the inlet pipe 13 is provided in a substantially tangential direction to the side surface 16 of the rotating shell 12 and the inner wall 17 of the side surface 16 of the rotating shell 12 is formed in a substantially cylindrical shape, the coolant flowing from the inlet pipe 13 is It swirls along the inner wall 17 of the side surface 16 of the rotating body 12, forming a vortex. When the inflowing coolant contains hydrogen bubbles, the centrifugal separation effect causes the hydrogen bubbles with low specific gravity to gather at the center of the vortex, and the coolant with high specific gravity to gather on the outside of the vortex. The collected hydrogen bubbles coalesce and eventually grow into large bubbles. Rotating trunk 12
The gas-liquid outlet pipe 14, which opens to the upper surface 18, is an outlet for discharging the grown hydrogen bubbles together with the coolant. On the other hand, the outlet pipe 15 opening at the lower part of the side surface 16 of the rotating body 12 serves as an outlet for the coolant from which hydrogen bubbles have been removed. The outlet pipe 15 is connected to the rotating body 16
Since it is provided approximately in the tangential direction of the side surface portion 16, the swirling coolant tends to flow out due to centrifugal force.
In addition, there is no fear that the coolant flowing out will entrain hydrogen bubbles and flow out together with the coolant.

If the hydrogen bubbles are small, the rise due to the buoyant force acting on the bubbles themselves will be slow, and the bubbles themselves will remain in the coolant and will not rise easily. For this reason, if the bubbles are small, it becomes difficult to separate the hydrogen bubbles, but as mentioned above, a high separation effect can be obtained by using the centrifugal separation effect to agglomerate minute hydrogen bubbles in the center and grow them together. .

Since there is no free liquid surface of the coolant inside the rotating shell 12, the rotating shell 12 is always filled with coolant. This prevents the coolant level from dropping for some reason and causing the coolant to flow out, entraining hydrogen bubbles, and is therefore highly reliable.

Hydrogen bubbles and coolant are separated in the rotating shell 12, and the hydrogen bubbles flow into the coolant tank 19 via the connecting pipe 20, while the coolant flows into the reactor vessel 1 via the return pipe 5. do.

The coolant tank 19 into which the coolant mixed with hydrogen bubbles separated from the coolant flows is an overflow tank in this embodiment, but may be a dump tank or other tank. When the coolant exceeds a predetermined level in the reactor vessel 1 , the coolant flows into the coolant tank 19 via the overflow line 21 . After being stored in the coolant tank 19, the coolant is returned to the reactor vessel 1 by an electromagnetic pump 23 via a return pipe 22 as required.

This embodiment configured as described above operates as follows.

High-temperature coolant is sent from the reactor vessel 1 to the steam generator 3 via the outgoing line 4, and after heat exchanged in the steam generator 3, the coolant enters the returning line 5. Return pipeline 5
Then, via the pump 10, the outlet pipe 15 of the rotating barrel 12
From there, it is sent to the reactor vessel 1 via the return pipe 5.
This circulation of the coolant is performed by a pump 10.

Now, if the heat transfer tube 8 is damaged for some reason in the steam generator 3, water and sodium react to generate hydrogen bubbles, which enter the return pipe line 5.

The coolant flowing in from the inlet pipe 13 swirls along the inner wall 17 of the side surface 16 of the swirling shell 12, forming a vortex. Due to the centrifugal separation effect, hydrogen bubbles with low specific gravity gather in the center of the vortex, and coolant with high specific gravity gathers on the outside of the vortex.

The collected hydrogen bubbles coalesce and grow into large bubbles, and the grown hydrogen bubbles rise due to buoyancy, flow out from the gas-liquid outlet pipe 14 in a state mixed with the coolant, and are cooled via the communication pipe 20. material tank 19
sent to.

On the other hand, the coolant from which the hydrogen bubbles have been separated is the outlet pipe 1.
5 and is sent to the reactor vessel 1 via the return pipe 5.

In this way, the hydrogen bubbles and the coolant are separated in the rotating shell 12, and only the coolant that does not contain hydrogen bubbles is sent to the reactor vessel 1. The separated hydrogen bubbles are
It is sent together with the coolant into a coolant tank, where it is temporarily stored and hydrogen is completely separated, and then the separated hydrogen is released into the atmosphere by opening the valve 24. Further, a small amount of coolant sent into the coolant tank 19 together with hydrogen bubbles through the separation pipe 20 is sent to the reactor vessel 1 through a return pipe 22 and used again.

Next, an example other than the gas-liquid separator 11 according to the above example will be described.

In the case shown in FIG. 3, the rotating barrel 1 of the inlet pipe 13
A diaphragm 13A is provided at the connection part with 2. The throttle 13A is a nozzle that increases the flow rate of the fluid passing through it, and is intended to increase the inflow rate of the coolant, thereby increasing the flow rate of the swirling flow within the swirling shell 12. As the flow rate of the swirling flow increases, the centrifugal force becomes stronger and the gas-liquid separation effect becomes greater.

In the case shown in FIG. 4, the upper surface 1 of the rotating trunk 12
8 is formed into a conical shape, making it easy for hydrogen bubbles to collect.

(Effects of the Invention) In the present invention, the cooling system of a fast breeder reactor plant is such that the secondary cooling system is removed, and the return pipe of the cooling system has a substantially cylindrical inner wall on the side surface. A gas and liquid connected to a rotating shell, an inlet pipe provided substantially tangentially to a side surface of the rotating shell, and a connecting pipe extending to a coolant tank provided approximately at the center of the upper surface of the rotating shell. and a gas-liquid separation device having an outlet pipe and an outlet pipe provided in the swirling barrel.

Therefore, the present invention has the following effects.

Even if the heat transfer tubes of the steam generator are damaged and the hydrogen bubbles generated thereby enter the return pipe of the cooling system, the gas-liquid separator removes the hydrogen bubbles from the coolant, preventing hydrogen bubbles from entering the core. This can be prevented. Furthermore, since the centrifugal separation effect is used to separate the hydrogen bubbles and the coolant, even minute hydrogen bubbles that are difficult to separate due to simple buoyancy can be efficiently separated by coalescing and growing. Furthermore, since there is no free liquid surface of the coolant within the swirling shell 12, the coolant level will not drop for some reason and the escaping coolant will not entrain hydrogen bubbles, thereby increasing reliability.

As described above, the gas-liquid separation device according to the present invention has a high hydrogen bubble removal effect, so even if the secondary system is deleted in a fast breeder reactor plant, the safety of the cooling system is maintained, and the secondary system is not interposed. compared to when
Thermal efficiency is improved, the plant is simpler and smaller, and construction costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram according to an embodiment of the present invention. FIG. 2 is a partially cutaway perspective view showing the gas-liquid separator of FIG. 1. FIG. 3 is a front view showing another modification of the gas-liquid separator of the present invention. FIG. 4 is a front view showing still another modification of the gas-liquid separation device. FIG. 5 is a system diagram of the prior art. 1: Reactor vessel, 4: Outbound pipeline, 5: Return pipeline, 1
0: Pump, 11: Gas-liquid separation device, 12: Swivel barrel, 13: Inlet pipe, 14: Gas-liquid outlet pipe, 15: Outlet pipe, 16: Side part, 17: Inner wall, 18: Top part, 19: Cooling Material tank, 20: Connecting pipe.

Claims (1)

[Scope of Claims] 1. A secondary cooling system elimination type cooling system that directly sends coolant from the reactor vessel to the steam generator, comprising: an outgoing pipe line that sends the coolant from the reactor vessel to the steam generator; a cooling conduit consisting of a return conduit for returning coolant from the reactor vessel to the reactor vessel; a pump provided in the cooling conduit; and a pump provided in the return conduit, the inner wall of the side surface of which a certain rotating body; an inlet pipe provided approximately tangentially to a side surface of the rotating body and connected to the return pipe; and a gas-liquid outlet pipe provided approximately at the center of the upper surface of the rotating body; a gas-liquid separator having an outlet pipe provided on the revolving barrel and connected to the return pipe; and a communication pipe connecting the gas-liquid outlet pipe of the gas-liquid separator and a coolant tank. A secondary cooling system deletion type cooling system in a fast breeder reactor plant, characterized by comprising: