JPS63121785A - Double tank type fast breeder reactor - Google Patents

Abstract

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

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to fast breeder reactors, and in particular, the reactor core is surrounded by double tanks, a steam generator is installed between the inner and outer tanks, and water This relates to technology that prevents the effects of abnormal phenomena such as sodium reactions on the reactor core.

"Conventional technology and its problems" In general, fast breeder reactors use liquid sodium, which maintains metallic sodium in a molten state, as a coolant for the core. Heat exchange is performed between the secondary liquid sodium and the secondary liquid sodium in the steam generator, and further heat exchange is performed between the secondary liquid sodium and water in the steam generator to obtain the necessary high temperature and high pressure steam. The steam is sent to other steam consuming systems.

In this case, since liquid sodium has the property of rapidly reacting with air or water, liquid sodium for core cooling (-secondary liquid sodium) and secondary liquid sodium are used to improve safety and handling. Plans are being made to store them in double tanks.

However, even when liquid sodium is stored in double tanks, if an intermediate heat exchanger is interposed between the primary and secondary liquid sodium, the structure of the fast breeder reactor tends to become complicated and large. becomes unavoidable.

The present invention solves these problems, and aims to make it possible to omit the conventional intermediate heat exchanger and to improve safety.

"Means for Solving the Problems" The present invention provides a double tank type fast breeder reactor in which liquid sodium is stored in an outer tank and an inner tank constituting a double tank, in which liquid sodium is stored in the inner tank. a connecting pipe that is interposed between the inner and outer tanks to allow liquid sodium to pass therethrough; a steam generator that exchanges heat with the liquid sodium that is housed in the outer tank and is heated in the core; An abnormality detector of the generator is actuated by the detection signal of the abnormality detector to feed inert gas into the siphon portion of the connecting pipe located above the liquid level of the inner tank to insert liquid sodium. The structure includes a siphon break device for stopping the engine.

``Operation'' During operation of a fast breeder reactor, liquid sodium heated in the reactor core rises up the inner tank, is led into the outer tank via the connecting pipe, and is connected to the steam generator in the outer tank. perform heat exchange. The liquid sodium, which has been reduced to a low temperature by heat exchange, is guided to the lower part of the reactor core via a connecting pipe and circulated through the reactor core again.

Then, an abnormality such as a water-sodium reaction in the steam generator in the outer tank is detected, and the inert gas supply system is activated based on the abnormality detection signal, and a connecting pipe through which liquid sodium is passed between the inner and outer tanks. Inert gas is sent into the siphon part of the inner tank to remove the liquid sodium in the siphon part located above the liquid level of the inner tank, thereby stopping the passage of liquid sodium into the inner and outer tanks due to the siphon phenomenon. In this way, by preventing the circulation of liquid sodium between the inner and outer tanks, the water-sodium reaction product is prevented from being mixed with the liquid sodium in the vicinity of the steam generator and sent to the reactor core. There is.

“Example” An example of a fast breeder reactor according to the present invention will be described below with reference to FIGS. 1 to 4.

The fast breeder reactor targeted in this example is the first
As shown in the figure, an outer tank 1 and an inner tank 2 forming a double tank, liquid sodium 3 stored in both tanks 2, a reactor core 4 installed in the center of the inner tank 2, and an inner For example, four coolant circulation pumps 5 are installed inside the tank 2, and a steam generator 6 is installed inside the outside tank 1 to exchange heat with the liquid sodium 3 heated in the reactor core 4. A high-temperature side connecting pipe 7 and a low-temperature side connecting pipe 8 for inserting liquid sodium 3 in both tank containers 2 using a siphon phenomenon, and both connecting pipes 7 and 8.
a siphon break device 9 installed using the reactor storage pit 10; and a roof slab for installing the tank 2, the coolant circulation pump 5, etc. in a suspended state in the reactor storage pit 10. 11 and, for example, four auxiliary core cooling system heat exchangers 12 provided between the coolant circulation pumps 5.

To explain these details, the steam generation H6 has a double pipe structure and has a large number of heat transfer tubes 13 suspended in a U-shaped state bent in the outward and outward directions, as shown in FIG. With this book, as shown in Figure 1,
The outer end of the heat exchanger tube I3 is connected to a water supply system (4), and the inner end is connected to a steam consumption system (power generation turbine, etc.) 15. These ends of the heat exchanger tube 13 are
They are communicated with each other in the circumferential direction by ring-shaped header pipes 16 and 17, so that water supply is distributed and steam is collected. In addition, the heat transfer tube 13 has a double tube structure consisting of an inner tube and an outer tube, and the gap between the inner and outer tubes is used as a fluid insertion passage for leak detection, and the detection fluid supply system 18 and abnormality detection 19.

Furthermore, inside the outer tank I, a cylindrical heat insulating partition wall 20 for partitioning the liquid sodium 3 into inside and outside is disposed in a state suspended from the roof slab 11, and the heat insulating partition wall 20 The lower end of the tank is spaced apart from the bottom of the outer tank 1 to communicate with the liquid sodium 3.

A high temperature side connecting pipe 7 is provided between the two tanks 2 for communicating the upper part of the inner tank 2 with the inner part of the upper part of the outer tank I, and the lower part of the inner tank 2 and the outer part of the upper part of the outer tank 1 are provided. A low-temperature side connecting pipe 8 is provided for communication between the two connecting pipes 7 and 8, and the siphon break device 9 is provided at a portion of both the connecting pipes 7 and 8.

The siphon break device 9 connects the connected inert gas supply system 2 to the exposed siphon portion of the connecting pipes 7 and 8 from the liquid level NsL of the inner tank 2, as shown in FIG. is provided in the middle of the inert gas supply system 21, and is actuated by the detection signal of the abnormality detector 19 to open in the event of an abnormality in order to send inert gas to the zyphone portions of both the connecting pipes 6 and 7. This is a configuration in which a valve 22 is provided.

In addition, inside the inner tank 2, a core partition wall 23 is provided at the upper part of the core 4 to divide the inside of the inner tank 2 into a high temperature section and a low temperature section, that is, to partition the inside of the inner tank 2 into upper and lower sections, and the auxiliary core cooling system Heat exchanger I2 is a roof slab! (1) and the core partition wall 23.

Regarding the auxiliary core cooling heat exchanger 12, Figures 1 and 4
To explain with reference to the figure, liquid sodium 3 near the reactor core 4 is inserted into the secondary system, and an inlet 24 and an outlet 25 are provided for this, and a secondary system that exchanges heat with the secondary system is provided with an inlet 24 and an outlet 25. A heat transfer tube 26 is installed on the side of the shell to pass through the secondary liquid sodium cooled by an air cooler etc. installed outside the roof slab 11. This structure is equipped with a closing device 27 for closing the entrance 24 of the primary system and opening it in the event of an abnormality.

Further, the shutter device 27 includes a shutter 28 that opens and closes the entrance 24 of the auxiliary core cooling heat exchanger I2 by vertical movement, a drive sleeve 29 that supports and moves the shutter 28 up and down, and is connected to the drive sleeve 29. A rack and pinion mechanism 30, a drive source 3I such as a motor for driving the rack and pinion mechanism 30, a transmission mechanism 32 such as a reducer or gear, and a drive sleeve 29 are attached so as to be constantly lifted upward. Resilient spring 33
It is a structure consisting of. Note that a protective sleeve 34 is disposed around the shutter 28 and the drive sleeve 29 so as to surround them.

In the fast breeder reactor configured in this way, the steam generator 6 is housed in the outer tank 1, and in order to generate steam here, a conventional so-called intermediate heat exchanger and a secondary liquid sodium are used. The pump for circulation is omitted.

That is, during operation of the fast breeder reactor, the coolant circulation pump 5
1, the liquid sodium 3 in a low temperature state located near the bottom of the inner tank 2 is sent into the reactor core 4 as shown by the arrow in FIG. 1, and the liquid sodium 3 heated in the reactor core 4 is At the same time, the liquid sodium 3 in a high temperature state is sent into the upper part of the outer tank (2) by the high temperature side connecting pipe 7 at the upper part of the inner tank (2) as shown by the arrow.

The liquid sodium 3 sent into the outer tank 1 is
The inside and outside of the heat insulating partition wall 20 are connected to the heat transfer tubes I of the steam generator 6.
3, and then rises almost vertically as shown by the arrow, passing between the lower end of the insulating bulkhead 20 and the bottom of the outer tank I, and these descending and Heat exchange is performed with the heat transfer tube 13 during the upward stroke.

The liquid sodium 3, which has become low temperature through heat exchange, is sent to the lower part of the inner tank 2 from the low-temperature side connecting pipe 8 at the upper part of the outer tank 1, and is sucked in from the lower part of the coolant circulation pump 5 and discharged. As a result, it is fed into the core 4 again and circulated.

In the steam generator 6, steam is generated by heat exchange with the liquid sodium 3, and the steam is sent to the steam consumption system I5.

Note that when such a nuclear reactor (fast breeder reactor) is in operation, the auxiliary core cooling heat exchanger 2 is kept in a non-operating state, and in order to prevent it from performing heat exchange, as will be described later. Then, the entrance 24 is closed.

Next, detection of abnormality occurrence, protection of the reactor core 4, etc. will be explained. The pressure of the inner and outer tanks 2 containing liquid sodium 3 is approximately 5 kg/cm2, and the vapor pressure is 100~
I is set to about 80 kg/cm2, so as mentioned above, if the abnormality detector 19 is operated using the gap between the inner and outer tubes of the heat exchanger tube 13, the
If a defect occurs in one of the inner and outer tubes in step 3, supply an inert gas such as helium to the leakage detection fluid insertion passage in advance and detect the relative difference between the pressure and the detection fluid pressure. Before a water-sodium reaction accident occurs,
can be dealt with.

When an abnormality detection signal is output from the abnormality detector 19, the abnormality release valve 22 is activated by this abnormality detection signal.
is activated to send inert gas from the inert gas supply system 21 to the high-temperature side connecting pipe 7 and the low-temperature side connecting pipe 8 as shown by the arrows in FIG. Remove the liquid sodium 3 from the tube as shown by the arrow. As mentioned above, assuming that the pressure of the liquid sodium 3 is set to about 5 kg/cm2, the liquid is Sodium 4 can be eliminated.

When the liquid level Nsl of the inner tank 2 becomes higher, the siphon part located on one side becomes a gas atmosphere and the siphon phenomenon disappears, the circulation of liquid sodium 3 stops between the inner and outer tank 2, and the outer tank 2 The liquid sodium 3 near the bottom of the tank is no longer pumped into the inner tank 1, so even if a water-sodium reaction occurs,
Together with the liquid sodium in the vicinity of the steam generator 6, the water-sodium product can be prevented from being sent to the core.

On the other hand, if the abnormality detection signal of abnormality detector ■9 is output, even if the reactor is stopped immediately, the
Since decay heat of the radioactive materials continues to be generated, in order to remove it, the auxiliary core cooling heat exchanger 12 is activated, and the coolant circulation pump 5 is operated in an auxiliary manner. It will be done.

For example, depending on the abnormality detection signal, the operation of the auxiliary core cooling heat exchanger I2, the operation of the air cooler connected to it,
The operation of the shutter device 27, etc. will be disrupted.

The drive source 31 in the shutter device 27 is actuated to transmit its rotational force to the rack and pinion mechanism 30 via the transmission mechanism 32, and the shutter 28 in the chain line position in FIG. 4 is raised as shown in the solid line position. , the inlet 24 of the auxiliary core cooling heat exchanger 12 is opened. At this time,
The biasing force of the resilient spring 33 assists the upward movement of the shutter 28. As a result of these operations, when the primary system inlet 24 of the auxiliary core cooling heat exchanger I2 is opened, liquid sodium flows through the core 4, the inlet 24, and the heat exchanger tubes 26, as shown by the dashed arrow in FIG. , the outlet 25, the coolant circulation pump 5, and the reactor core 4 to remove the decay heat of the reactor.

[Other Embodiments] The following embodiments may be used instead of the embodiment described above.

(i) Install an abnormality detector in a location other than the heat transfer tube in the steam generator.

(ii) The number of auxiliary core cooling heat exchangers and the number of inlets and outlets are arbitrary.

(iii) The driving source of the shutter device is linked with an inert gas supply system, and the driving is performed by gas pressure.

(1v) Performing operations other than moving the shutter up and down.

"Effects of the Invention" As explained above, according to the fast breeder reactor of the present invention, the following excellent effects can be achieved.

■Since the steam generator is inserted into the liquid sodium in the outer tank, the intermediate heat exchanger can be omitted, making it possible to significantly streamline the fast breeder reactor.

■The circulation of liquid sodium between the inner and outer tanks is stopped by sending inert gas into the connecting pipe between the inner and outer tanks (indicator section), so in the event of an abnormality, steam will not be generated. Liquid sodium near the reactor can be prevented from being pumped into the reactor core.

■The siphon break device is designed to feed inert gas into the connecting pipe, so it can quickly stop the circulation of liquid sodium between the inner and outer tanks.

(2) The above makes it possible to simplify and downsize the siphon break device.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the double tank fast breeder reactor according to the present invention, Fig. 2 is a view taken along the line ■-■ in Fig. 1, and Fig. 3 is the same as shown in Fig. 1. An explanatory diagram of the operation of the siphon break device, FIG. 4 is a longitudinal sectional view of the Nyatta device in the auxiliary core cooling heat exchanger shown in FIG. 1. 1...Outer tank, 2...Inner tank,
3...Liquid sodium, 4...Reactor core, 5...
・Coolant circulation pump, 6... Steam generator,
7... High temperature side connecting pipe, 8... Low temperature side connecting pipe, 9... Siphon break device, 10...
...Reactor pit, 11...Roof slab,
12...Auxiliary core cooling system heat exchanger, I3...
... Heat exchanger tube, 14 ... Water supply system, I5 ...
・Steam consumption system, I6/17...Header pipe, 18...
Detection fluid supply system, 19... Abnormality detector, 20.
...Insulating bulkhead, 21...Inert gas supply system,
22... Abnormality release valve, 23... Core bulkhead, 24... Inlet, 25... Outlet, 26
... Heat exchanger tube, 27 ... Shutter device, 2
8...Shutter, 29...Drive sleeve, 30...Rack and pinion mechanism, 31...
...Drive source, 32...Transmission mechanism, 33...
...Repulsion spring, 34...Protective sleeve. Figure 8

Claims (1)

[Claims] In a double tank type fast breeder reactor in which liquid sodium is stored in an outer tank and an inner tank that constitute a double tank, the liquid sodium is interposed between the core stored in the inner tank and the inner and outer tanks. A connecting pipe through which sodium is inserted, a steam generator that exchanges heat with liquid sodium stored in an outer tank and heated in the reactor core, an abnormality detector for the steam generator, and detection of the abnormality detector. and a siphon break device that is activated by a signal to feed inert gas into the siphon portion of the connecting pipe located above the liquid level in the inner tank to stop the passage of liquid sodium. A double tank fast breeder reactor.