JPS58127199A - Emergency reactor cooling system - 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 [Technical Field of the Invention] The present invention relates to a nuclear reactor emergency cooling system used for emergency core cooling in the event of an accident in, for example, a fast breeder reactor.

[Technical background of the invention]

Nuclear reactor accidents include main cooling system or power loss accidents.

When the flow rate of coolant flowing inside a nuclear reactor is lost due to these accidents, it is necessary to ensure core cooling and prevent fuel melting accidents.

Conventionally, this problem has been dealt with by combining natural circulation in the main cooling system and an emergency reactor core cooling system using pumps.

However, when using the natural circulation of the main cooling system, in order to ensure the necessary flow rate against the flow resistance of the cooling system,
It is necessary to set an appropriate height difference between the center of the reactor core and the heat transfer center of the heat exchanger, and the balance with equipment layout becomes an issue.

In addition, the emergency core cooling system using pumps stops its cooling function during normal reactor operation, and must operate reliably when necessary, which poses a problem in the event of a power loss accident.

A core cooling method using heat pipes that does not require external power has long been known as a method for cooling the reactor core.

For example, “John L. Anclerson:
and Edward Lartz: ANUCLEAR
Tl(ERMIONIC5PACE POWERC0
NCEPTUSING ROD C0NTR0L
AND HgAT PIPES, Lewig
Research Center C1eveland
, 0hjo, NASA TND-5250+19
69”.

This method cools the reactor core by removing heat from the reactor core through phase changes due to evaporation and condensation of the heat medium within the heat pipe and transferring the heat to the outside.

Further, Japanese Patent Application Laid-Open No. 51-104199 proposes a nuclear reactor emergency cooling system that cools the reactor core by utilizing the evaporation and condensation of a heat medium by a heat pipe.

FIG. 1 shows an example in which a core cooling system using heat pipes is applied to a liquid metal cooled fast breeder reactor.

That is, the reactor vessel 1 supported on the pedestal wall is provided with a coolant inlet nozzle 2 at the bottom and an outlet nozzle 6 at the upper side.

A support plate 5 for the core support structure 4 is provided horizontally at the bottom of the reactor vessel 1, and an inlet plenum 6 is provided in the reactor vessel 1 located below the support plate 5, and a blanket is provided above the support plate 5. 6 and a reactor core 8 loaded with fuel assemblies 7 are installed, and the reactor vessel 1 in which the above-mentioned outflow nozzle B is located is installed.
A coolant outlet blemish 9 is provided at.

A control rod 10 is inserted into the reactor core 8 .

In addition, cover gas 11 is provided at the upper exit blemish 9 of the core 8.
is filled and closed with a shielding plug 12.

A rotating plug 16 is biased and rotatably inserted into the shielding plug 12, and is fixed through the rotating plug 13 (-upper mechanisms 14 such as core upper mechanism, control rod drive mechanism, and fuel exchanger).

The control rod drive mechanism is used to shut down the nuclear reactor, and inserts the control rods 10 into the reactor core 8 and pulls them out from the reactor core 8.

A heat pipe 15 is inserted and attached by penetrating the reactor vessel 1, and the heat pipe 15 is connected to a heat dissipation device 16.

The heat dissipation device 16 utilizes liquid metal cooling, water cooling, or air cooling.

Note that as the heat medium of the emergency cooling device using the heat pipe 15, Li, Na, K, or NaK is used.

[Problems with background technology]

The heat medium takes heat from the coolant in the upper part of the furnace vessel and evaporates, and the generated steam transfers heat to the heated part and condenses there.

The vapor of the heat medium moves due to the difference in vapor pressure between the condensing section and the evaporating section within the heat pipe.

Further, the condensed liquid is sent back to the evaporation section by capillary action of a porous material (hereinafter referred to as wick material) around the inside of the tube.

In this way, reliable cooling function can be expected.

However, in addition to cooling performance, the emergency cooling system must not operate during normal operation of the nuclear reactor, but must be able to start up reliably and quickly in an emergency.

In response to this requirement, heat pipes cool the core during normal operation because they constantly transfer heat, and are not suitable for use as emergency core cooling devices.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide nuclear reactors that do not operate normally but can reliably operate and perform core cooling during emergency core cooling. The purpose of the present invention is to provide a furnace emergency cooling system.

[Summary of the invention]

In order to achieve the above object, the present invention provides an injection operation system that injects a heat medium into a heat pipe, and in an emergency, this injection operation system injects a heat medium to make the heat pipe function, and inside the pipe. A reactor emergency cooling system that cools the reactor core by removing heat from the coolant in the reactor vessel and circulating the coolant through convection within the reactor vessel through phase changes due to evaporation and condensation of the heat transfer medium. be.

[Embodiments of the invention]

Hereinafter, an embodiment of the nuclear reactor emergency cooling system according to the present invention will be described in detail with reference to FIG.

Note that FIG. 2 shows only the essential parts of the present invention, and since the installation of the heat pipe into the reactor vessel is almost the same as that in FIG. 1, it is omitted, and only the upper part of the heat pipe is shown.

In addition, although only a single heat pipe is shown in the figure, for example, as shown in Figs. A pipe assembly composed of 24°25 may also be used.

That is, FIG. 6 shows a heat pipe 20 with a hexagonal cross section.
are arranged in a honeycomb shape and integrated into a cylindrical body 22. In addition, in FIG. , an example in which a heat insulating material 26 is filled between each heat pipe 21 is shown.

As shown in FIG. 2, the heat pipes 20 and 21 have a porous material (hereinafter referred to as wick material) 28 stretched on the inner surface of an outer cylinder 22 or 23.

A pipe 29 through which the heat medium flows is connected to the side surface of the outer cylinder 22 or 26, and this pipe 29 is connected to the injection valve 3.
0 to the heat medium injection tank 31.

Further, a temperature detector 32 is provided above the pipe 29, and the detector 62 is connected to a recorder 36.

Further, a heat insulating material 64 is provided on the outer peripheral surface of the outer cylinder 22 or 23.

A neck portion 66 having fins 35 is connected to the upper end surface of the outer cylinder 22 or 23, and an exhaust pipe 37 is connected to the upper end of the neck portion 36.

A valve 38 is connected to the exhaust pipe 67, and an electromagnetic valve 40 is connected to the valve 68 via a vibro 9.

The electromagnetic pulp 40 is connected to a vacuum pump 41.

Further, a pressure gauge 42 is connected to the pipe 39, and
The signal from this pressure gauge 42 is sent to a control device 46.

The output signal of the control device 43 is sent to the electromagnetic pulp 40 and the vacuum pump 41.

[Action of the invention]

Next, the operation of the emergency cooling device of the present invention will be explained.

During normal operation, the valve 38 is open and the injection pulp 60 is closed, creating a vacuum inside the heat pipe 20 or 21, but it does not function because no heat medium is flowing into it.

The degree of vacuum inside the heat pipe 20 or 21 is determined by the pressure gauge 4.
2, the electromagnetic pulp 40 is detected by the vacuum control device 46.
A high vacuum is maintained by controlling the vacuum pump 41.

In an emergency, the valve 68 is closed, the injection pulp 30 is opened, and the heating medium in the injection tank 61 is charged into the heat nozzle 20 or 21.

The heat pipe starts functioning by charging the heat medium,
Heat from the core is removed.

Whether or not the heat pipe 20 or 21 has started functioning can be confirmed by detecting the temperature rise of the heat dissipation section with the temperature detector 32 and by checking the change in the indication on the recorder 66.

〔Effect of the invention〕

As explained above, the device according to the present invention does not perform the cooling function during normal operation, but performs the cooling function by evaporating the heat medium during operation without requiring extra power such as a pump, so it is reliable in an emergency. This provides a highly reliable emergency cooling device that operates in a timely manner.

In addition, the liquid metal cooled by the equipment of the present invention flows downward into the reactor vessel, while the liquid metal heated in the reactor core flows upward into the reactor vessel, and the coolant is circulated by convection within the reactor vessel. Do the following.

Therefore, unlike when using the natural circulation of the main cooling system, the positional relationship between the core and the heat exchanger does not pose a problem.

In addition, since power from a pump or the like is not required during operation, there is no loss of functionality even in the event of a power loss accident.

Moreover, in steady state, there is no heat medium inside the heat pipe, so there is no extra heat loss.

In addition, depending on the usage conditions of the heat pipe, water, organic solvents, various metals, etc. can be used as a heat medium, resulting in light water reactors,
Even when the device of the present invention is used in a gas furnace or the like, the same effects as described above can be obtained.

For example, when the operating temperature is 450 to 800°C, Na, Li, K, NaK, etc. are used as the heat medium,
The degree of vacuum is maintained at approximately 10-6 molar.

As detailed above, the present invention provides an emergency cooling system for emergency core cooling in the event of an accident, which has no heat loss during steady state, operates reliably when necessary, and has a highly reliable cooling function. be able to.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a conventional emergency cooling device using a heat vibrator used in a liquid metal cooled nuclear reactor, and FIG. 2 is a schematic cross-sectional view of an emergency cooling device using a heat vibrator according to the present invention. 3 and 5 are cross-sectional views showing two examples of the heat vibrator assembly used in the device shown in FIG. 2, and FIG. FIG. 7 is a partially cutaway perspective view of the heat pipe assembly of FIG. 6; 20.21...Heat vibe 28...Quick 29...Injection vibro 1...Heat medium injection tank 62...
...Temperature detector 66...Recorder 64...Heat insulation material 35...Radiation fin 66... ...Neck section 67...Exhaust pipe 41...Vacuum pump 42...Pressure gauge 43... ...Patent attorney for control equipment Satoshi Suyama - Figure 1 Figure 7

Claims (1)

[Scope of Claims] 1. A heat pipe provided with one end immersed in a coolant in a nuclear reactor vessel and the other end exposed outside the reactor vessel;
An atom characterized by comprising an injection system for injecting a heat medium into the heat pipe, an evacuation system for maintaining the inside of the heat pipe at reduced pressure, and a temperature measurement system for measuring the temperature inside the heat pipe. Furnace emergency cooling system. 2. The vacuum exhaust system is equipped with a pressure gauge from one end of the heat pipe through the pulp, and a vacuum pump that inputs the signal of this pressure gauge to the control device and operates based on this input signal. A nuclear reactor emergency cooling system according to claim 1, characterized in that: