JPH0427517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a liquid metal cooled fast breeder reactor in which an intermediate cooling system, which is a secondary main cooling system, is completely eliminated.

As is well known, conventional fast breeder reactor power plants that use liquid metal sodium as the primary coolant transport the heat generated in the reactor core in the primary sodium system and transfer it to the secondary sodium system via an intermediate heat exchanger. The structure had an intercooling system loop in which steam was generated by transmitting water to water and then transmitting it from the secondary sodium system to water via a steam generator.

For example, Figure 1 is a typical example of the cooling system of a liquid metal cooled fast breeder reactor, which is called a loop type reactor structure. Heat is transported by the primary coolant sodium, which is circulated in the primary main cooling system loop 4 by the pump 3, and the secondary cooling is circulated in the secondary main cooling system loop 6 in a non-contact manner in the intermediate heat exchanger 5. The water is transmitted to the water flowing through the steam system loop 8 in a non-contact manner in the steam generator 7. The steam generated by the steam generator 7 is supplied to the turbine 9 and generates electricity by driving a generator 10 directly connected to the turbine 9. In addition, although not shown in the figure, there is a liquid metal cooled fast breeder reactor called a tank type reactor, and the cooling system of this type of reactor is the first reactor.
The primary main circulation pump 3 and intermediate heat exchanger 5 shown in the figure are housed in the reactor vessel 1.In place of the primary main cooling system closed loop 4, the primary system sodium is placed inside the reactor vessel 1. It is circulated to an intermediate heat exchanger.

In this way, conventional liquid metal cooled fast breeder reactors are equipped with a secondary main cooling system loop called an intercooling system.The reason for this is that the primary system sodium is activated by fast neutrons generated in the core 2 Therefore, if the primary coolant is supplied directly to the steam generator, such as in a pressurized water reactor,
Water, which is a heat medium in the steam system, exchanges heat with the primary sodium via the heat transfer tube of the steam generator. If the heat transfer tube is damaged, the primary sodium and water will react violently and hydrogen will be generated. Hydrogen gas, depending on its generation behavior, may pose a risk of plastic deformation or damage to the primary cooling boundary, and caustic soda may have an adverse effect on the reactor core as a corrosive substance. Because there is.

However, on the other hand, equipment costs and construction costs related to intercooling systems have been forced to increase significantly, and there is a strong demand for cost reduction due to the enormous construction costs, which are said to be about three times that of light water reactors. . Therefore, in view of the above-mentioned background, a new type of liquid metal-cooled fast breeder reactor has been proposed in recent years, in which the secondary main cooling system is completely eliminated, with the aim of reducing construction costs.

For example, the nuclear reactor disclosed in Japanese Patent Application Laid-Open No. 57-44885, which is one of them, has two compartments inside the reactor vessel 1, as shown in FIG. The steam generator 7 is placed above the reactor vessel 1, and the primary coolant is pumped up from the surrounding sections by the primary main circulation pump 3 placed inside the reactor vessel. The primary coolant heated by the reactor core 2 passes through the steam generator 7 above the reactor vessel 1 and returns to the surrounding compartment due to the siphon effect. Of course, a turbine (not shown) is connected to the secondary side of the steam generator 7, and the steam that has finished working is returned to water by a double water device (not shown), as shown by arrow A. The coolant is supplied to the steam generator 7 by a coolant pump (not shown), and 1
Next, it exchanges heat with the coolant (sodium), becomes steam again, and is sent in the direction of arrow B.

Another example uses a satellite pool structure 20 as shown in FIG. In this intermediate cooling system removal plant having a satellite pool structure, thermal energy generated in the reactor core 2 in the reactor vessel 1 is transferred from the upper plenum 24 of the reactor vessel to the primary system hot leg piping using sodium, which is the primary coolant. 13 to a hot pool 18 in a satellite pool container 14.

The satellite pool structure 20 has a sealed structure made of the satellite pool container 14 and shielding plastic,
It is connected to the reactor vessel 1 by a primary system hot leg piping 13 and a primary system cold leg piping 12.
A steam generator 7 installed and supported by a shielding plug 16 and a primary main circulation pump 3 are built into the satellite pool 14, and the steam generator 7 generates steam using heat from the primary system high temperature sodium. let The low temperature sodium heat exchanged by the steam generator 7 overflows from above the partition plate 17 and flows into the cold pool 19 at the inner bottom of the satellite pool container 14.
It is pumped up and pressurized by the primary main circulation pump 3 inserted in this part, and is passed through the primary system cold leg piping 12 connected to the pump to the high pressure plenum 15 in the reactor vessel 1.
is sent to cool the reactor core 2.

A pool partition plate 17 is installed in the satellite pool container 14 to partition a hot pool 18 and a cold pool 19, and since each pool has a free liquid level, a cover gas inert to sodium is provided. The space 21 above the liquid level is filled. This cover gas space 21 is connected to each of a plurality of satellite pool structures 20 (the figure shows only one for simplicity, but in reality there are multiple) and the reactor vessel 1 through cover gas system pressure equalization piping 22. It communicates with the cover gas inside the main body.

The above-mentioned intercooling system-eliminated plant is not particularly new because its technical concept is no different from a pressurized water reactor. but,
Although the aim is to reduce construction costs, since sodium is used as a primary coolant, safety measures must be taken to prevent an accident, that is, a sodium-water reaction caused by a rupture of a steam generator heat exchanger tube. From this point of view, compared to the former type, which is considered to have various effects on the reactor vessel 1 when a sodium-water reaction occurs, the latter type, which has a satellite pool structure, This cover gas space has a buffering effect against pressure waves caused by the sodium-water reaction, and at the same time, the satellite pool container functions as a storage container for the reaction product, which is considered preferable from a safety standpoint.

However, even if a satellite pool structure is interposed, the primary main cooling system piping is intact at the time of the sodium-water reaction accident, so it is connected to the reactor vessel, and therefore the primary main circulation pump During pump coast down until complete stop, or
There is a considerable risk that reaction products will flow into the reactor vessel and damage the integrity of the reactor core due to diffusion during the plant shutdown period following a sodium-water reaction accident.

This invention was made in view of the above-mentioned circumstances, and can significantly reduce the construction cost of nuclear power plants, and moreover, it is possible to reduce the construction costs of nuclear power plants, and it also takes into consideration sodium-water reaction accidents such as steam generator heat transfer rupture. The purpose of this invention is to provide a cooling system for a liquid metal cooled fast breeder reactor that does not impair the integrity of the reactor core.

Corresponding to this purpose, the cooling system of the liquid metal cooled fast breeder reactor of the present invention includes at least a reactor vessel and a plurality of satellite pool structures each having a primary main circulation pump and a steam generator in the satellite pool. , primary system hot leg piping connecting the hot pool in each of the satellite pool vessels and the upper plenum of the reactor vessel;
Primary system cold leg piping that connects the discharge side of the secondary main circulation pump and the high-pressure plenum of the reactor vessel, and a cover that connects the cover gas space of each of the satellite pool vessels and the cover gas space of the reactor vessel. In the cooling system of a liquid metal cooled fast breeder reactor, which is constituted by a gas system pressure equalizing pipe, a rupture disk is installed in the primary system cold leg pipe above the cold pool liquid level in the satellite pool container.

Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment.

FIG. 4 is a diagram showing a cooling system of a liquid metal cooled fast breeder reactor according to the present invention, and in the figure, reference numeral 25 is a rapture disk. Rapture disk 25 is cold pool 19 in satellite pool container 14
It is installed in the primary system cold leg piping 12 above the liquid level. The rest of the structure is the same as that of the intercooling system removal plant having the satellite pool structure shown in FIG. 3, so the same reference numerals will be used and the explanation will be omitted.

Next, the effect will be explained. If the heat transfer tube 11 in the steam generator 7 were to break, sodium and water would react violently, and at this time, a large pressure wave would propagate from the reaction point throughout the plant. When the pressure wave reaches the rupture disk 25, the pressure causes the rupture disk 25 to rupture, and the sodium in the cold leg piping 12 flows to the rupture disk rupture port, where the pressure loss is much smaller than in the flow path toward the high-pressure plenum 15. A large amount of water flows, and from here it flows down to the cold pool 19.

In addition, since the cold leg piping 12 outside the satellite pool vessel 14 is provided with a check valve 23, the cold leg piping 12 is
There is no reflux of sodium. On the other hand, the decay heat of the core 2 can be removed by the sound loop, so there is no need to worry.

When a sodium-water reaction accident occurs, the primary main circulation pump 3 is tripped by an accident signal (for example, a hydrogen gas detection signal in the system), and the pump goes through coat down and comes to a stop. During this time, sodium is still being discharged from the rupture port of the rupture disk, but at a certain point, cover gas flows in from the rupture port. This is because the primary cold leg piping 12 is located well above the liquid level of the cold pool 19, and as a result, the pump pressure decreases.
This is due to an effect caused by the pressure in the secondary cold leg piping becoming lower than the cover gas pressure, and as a result, the flow path from the satellite pool vessel 14 to the reactor vessel 1 is automatically severed.

As is clear from the above description, according to the present invention, the rapture disk can be easily used in the event of a sodium-water reaction accident by installing a lap-tire disk in the primary cold leg piping in the satellite pool container. It is possible to form a circulation flow path due to the rupture of the yard disk, from the cold pool to the primary main circulation pump, to the rupture port of the rupture disk, to the cold pool, and to separate the flow path to the reactor vessel. Therefore, it is possible to achieve a significant reduction in plant construction costs by eliminating the intercooling system, and even in the event of a sodium-water reaction accident such as a rupture of a steam generator heat exchanger tube or a coast down of the primary main circulation pump. A cooling system for a liquid metal cooled fast breeder reactor that can prevent reaction products (for example, corrosive substances such as caustic soda) from migrating to the reactor core and maintain the integrity of the reactor core can be obtained.

[Brief explanation of drawings]

Figure 1 is a diagram showing the cooling system of a loop type liquid metal cooled fast breeder reactor equipped with a secondary main cooling system;
FIG. 3 is a diagram showing a cooling system of a conventional liquid metal cooled fast breeder reactor without an intercooling system, and FIG. 4 is a diagram showing a cooling system of a liquid metal cooled fast breeder reactor according to the present invention. 1...Reactor vessel, 2...Reactor core, 3...Primary main circulation pump, 7...Steam generator, 11...Heat transfer tube, 12...Primary system cold leg piping, 13...
Primary system hot leg piping, 14... Satellite pool container, 15... High pressure plenum, 17... Pool partition plate, 18... Hot pool, 19... Cold pool, 20... Satellite pool structure, 2
2...Cover gas system pressure equalization piping, 25...Lapture disk.

Claims (1)

[Claims] 1 At least a reactor vessel, a plurality of satellite pool structures each having a primary main circulation pump and a steam generator in the satellite pool, a hot pool in each of the satellite pool vessels, and an upper plenum of the reactor vessel; primary system hot leg piping that connects the primary system hot leg piping that connects the primary system cold leg piping that connects the discharge side of each of the primary main circulation pumps and the high pressure plenum of the reactor vessel, and the cover gas space of each of the satellite pool vessels. and a cover gas system pressure equalizing pipe that connects the cover gas space of the reactor vessel. A cooling system for a liquid metal cooled fast breeder reactor characterized by having a rapture disk installed in the piping.