JPS6350793A - Decay heat removing system of fast breeder reactor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a decay heat removal system for a fast breeder reactor, and in particular to a fast breeder reactor in which decay heat can be removed through a safety vessel. related to a decay heat removal system.

(Prior Art) As is well known, the containment vessel of a fast breeder reactor consists of a reactor vessel that directly accommodates the reactor core and the coolant liquids, and a reactor vessel outside the reactor vessel. It has a double structure with a safety container placed so as to cover the furnace container with an inert gas layer in between. The containment vessel configured as described above is usually installed inside a reactor room surrounded by a concrete wall.

By the way, in recent years, in order to further improve the safety of such fast breeder reactors, a cooling system has been installed to remove decay heat from the outer surface of the safety vessel in the event that the main cooling system fails. is being considered. In other words, the idea is to remove decay heat by cooling the outer surface of the safety container with gas or liquid in case of an emergency.

However, there are several problems in realizing this concept. In other words, if the cooling system is activated to cool the safety container even during normal operation, thermal energy will be wasted into the atmosphere, resulting in an unavoidable economic loss. In addition, if the cooling system is activated only when it is necessary to remove decay heat, the expensive cooling system will not function properly during normal operation, and in this case, economic losses cannot be avoided. .

(Problems to be Solved by the Invention) As mentioned above, in order to realize the bedrock heat removal method via a safety container, it is necessary to consider economic efficiency as well as prevention of heat loss during normal operation. be.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a decay heat removal system for a fast breeder reactor that can reliably remove decay heat via a safety vessel when necessary and can be operated economically even during normal operation.

[Configuration 1 of the Invention (Means for Solving the Problems) The system according to the present invention includes a boiler in which a plurality of heat absorption tubes are disposed in close contact with each other on the outer surface of a safety container, and a boiler disposed above the boiler in which A steam turbine system that configures a heat cycle using a boiler as a steam generation source, and a bypass path that can directly connect a condenser of this steam turbine system to the boiler.

The reactor is provided with a valve that is inserted into the bypass passage and is controlled to be open when the reactor is shut down.

(Function) Since the heat absorption pipe of the boiler is placed in direct contact with the outer surface of the safety container, it is possible to generate steam with this boiler. Therefore, during normal operation, the steam turbine system is driven by the steam generated in the boiler, and the heat radiation energy from the safety container is recovered as motive power and effectively used. Also p
At the time of emergency, that is, when the reactor is shut down, a valve inserted in the bypass path opens, and a natural circulation path is formed in which the steam generated in the boiler is condensed in the condenser and then returned to the boiler. Therefore, the decay heat is transferred non-powered and completely passively to the condenser and is reliably removed.

(Example) An embodiment will be described below with reference to one drawing.

FIG. 1 is a diagram showing only the essential parts of a fast breeder reactor incorporating a system according to an embodiment of the present invention.

In the figure, 1 is a reactor room covered with a concrete wall, and inside this reactor room 1, a safety container 2 is placed with its opening facing upward and its upper end fixed and suspended. has been done. In the safety vessel 2, a reactor vessel (not shown) containing a reactor core and coolant is interposed between the safety vessel 2 and the safety vessel 2, and an inert gas layer is interposed between the safety vessel 2 and the safety vessel 2.
They are arranged in a small comb shape to reduce the thermal resistance between them.

A boiler 3 is arranged on the outer surface of the side wall of the safety container 2. This boiler 3 includes a plurality of annular steam drums 4 arranged around the upper outer periphery of the safety container 2, and an annular manifold pipe 5 arranged near the bottom outer surface of the safety container 2 in two circumferential directions. .

An endothermic pipe 6 whose upper end communicates with an intermediate position within the steam drum 4 and whose lower end extends downward and communicates with the manifold pipe 3 in close contact with the outer surface of the side wall of the safety container 2; A return pipe 7 connects the lower part of the manifold pipe 5 to the manifold pipe 5. steam drum 4
One end side of a steam pipe 8 and a liquid pipe 9 communicate with the upper and lower parts of the interior, respectively.
The other end side is connected to a steam turbine system 10 located above the steam drum 4.

The steam turbine system 10 employs a regeneration cycle, in which steam guided through a steam pipe 8 is passed through a high-pressure steam turbine 11. Low pressure steam turbine 12° condenser 13. Circulation pump 14. It is configured to be guided to the liquid pipe 9 via a feed water heater 15, 16 and a circulation pump 17. and,
with turbine power.

For example, the compressor (
Not shown. ).

A bypass pipe 1 is provided between the steam pipe 8 and the outlet of the low-pressure turbine 12 and between the outlet of the condenser 13 and the liquid pipe 9, respectively.
8.19 are connected, and these bypasses 1lJ18.
19 respectively have valves 20.21 and pressure limiters 22.23.
are inserted in series. The valves 20 and 21 each maintain an open state when energized, and automatically switch to an open state when not energized. and,
The valves 20 and 21 are set to the energized state (closed state 9) by a controller (not shown) when the reactor is operating normally.
II, and when the reactor is shut down, it is in a de-energized state (
(open state).

With such a configuration, the safety vessel 2 is also inevitably heated when the nuclear reactor is in operation. There is one endothermic tube 6 of the boiler 3 on the outer surface of the safety container 2! ! ! Since the heat absorbing tube 6 is provided in a fixed state, the water in the heat absorption tube 6 boils and evaporates into steam, and this steam is sent out from the steam drum 4. Therefore, the high pressure steam turbine 11 and the low pressure steam turbine 12 are driven, and thereby the compressor is driven. Therefore, most of the heat radiation energy from the safety vessel 2 during normal operation of the nuclear reactor is recovered.

On the other hand, when the operation of the nuclear reactor is stopped due to the occurrence of an emergency situation, the valves 20 and 21 are accordingly switched to the open state. As a result, the steam generated in the boiler 3 quickly flows through the bypass pipe 18 to the condenser 13, where it is condensed, and the water produced by this condensation is sent back to the boiler 3 via the liquid pipe 9. and circulate. Therefore, the decay heat at the time of reactor shutdown is also quickly removed. Note that since the steam turbine system 10 is provided above the boiler 3, the above-mentioned flow is performed by natural circulation.

In other words, the decay heat is transferred to the condenser 13 completely passively without any power.

In this way, this system can reliably remove decay heat when the reactor is shut down while preventing heat loss that is likely to occur when the reactor is operating normally. Therefore, it can contribute to economical operation. Furthermore, in this embodiment, the boiler 3 and the steam turbine system 10 are arranged in the above-mentioned relationship, and the valves 20 and 21 having the above-mentioned configuration are used, so even if the N source is lost, decay heat can be removed without any problem. can do.

Note that the present invention is not limited to the embodiments described above. That is, in the above-described embodiment, the air conditioning compressor is driven by a steam turbine, but one generator may be driven. Further, in the above-mentioned embodiments, a normal heat absorption tube is used as an element for recovering heat from the safety container, but a heat vibrator may also be used.

[Effects of the Invention] As described above, according to the present invention, decay heat can be reliably removed through the safety container when necessary while preventing heat loss during normal operation, which is economical. We can provide a decay heat removal system for fast breeder reactors that enables efficient operation.

[Brief explanation of drawings]

The figure is a diagram schematically showing only the main parts of a fast breeder reactor incorporating a system according to an embodiment of the present invention. 1... Nuclear reactor, 2... Safety vessel, 3... Boiler. 4...Steam drum, 10...Steam turbine system. 18.19...Bypass pipe, 20.21...Valve.

Claims (2)

[Claims] (1) A safety container placed outside the reactor container housing the reactor core so as to cover the reactor container, a boiler with a plurality of heat absorption tubes installed in close contact with the outer surface of the safety container, and the boiler. a steam turbine system disposed higher up and configuring a heat cycle using the boiler as a steam generation source; a bypass path that can directly connect the condenser of the steam turbine system to the boiler; and a nuclear reactor inserted in the bypass path. What is claimed is: 1. A decay heat removal system for a fast breeder reactor, comprising: a valve that is controlled to be open during shutdown. (2) The decay heat removal system for a fast breeder reactor according to claim 1, wherein the valve is automatically switched to an open state when electricity is not supplied.