JPS61795A - Gas cooling type 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] [Technical field to which the invention pertains]

The present invention relates to a gas-cooled nuclear reactor using, for example, helium gas as a primary coolant. In this type of gas-cooled nuclear reactor, in the event that a rupture occurs in the primary cooling system pipes, it is desirable to be able to cool the reactor so that the reactor core is brought to a low temperature immediately after the reactor is shut down.

[Prior art and its problems]

First, FIG. 7 shows the conventional configuration of the gas-cooled nuclear reactor mentioned above. In the figure, 1 is a pressure vessel of a nuclear reactor, 2 is a fuel block 31, a reflector block 4. A reactor core section consisting of a high-temperature plenum section 5, etc., 6 a heat exchanger 7. This is a primary cooling system conduit that serves as a loop system including the gas circulation machine 8, and the main cooling pipe of the primary cooling system conduit connected to the pressure volume 'B1 has a double pipe structure inside and outside, and its gas population The pipe 9 opens into the bottom wall of the pressure vessel 1, and the outlet pipe 10 passes through the bottom wall of the pressure vessel and opens into the high-temperature brenum section 5 of the reactor core section 2. Still, the primary cooling system pipe line 6 is usually installed in a plurality of loops for one nuclear reactor. When the reactor is operated with this configuration, the gas cooled by the heat exchanger 7 is pressurized by the gas circulator 8 and then discharged into the pressure vessel 1 through the inlet pipe 9 of the primary cooling system pipe line, from where the pressure is increased. The fuel rises along the outer periphery of the container, flows from the upper part into the fuel channel of the reactor core 2, exchanges heat with the fuel block 3, and rises in temperature. It then merges into the high temperature plenum section 4, from which exit '[10 through 1
It circulates and flows to be discharged to the next cooling system pipe line 6. By the way, during the operation of the reactor in such nuclear reactor equipment, 1.
A breakage accident may occur in the secondary cooling system pipes. When such an emergency situation occurs, in order to avoid an abnormal temperature rise in the core, it is necessary to immediately stop the operation of the reactor and to remove heat from the reactor after the shutdown. Conventionally, as a heat removal measure, a back-up cooling panel 11 is installed surrounding the outer periphery of the pressure vessel 1 as shown in FIG. 7, and heat is removed indirectly from the reactor through radiant heat transfer. has been done. However,
The heat removal method using the backup cooling panel 11 described above has low heat removal performance, and improvements are desired. In this regard, if it is possible to continue operating the other healthy loops except for the primary cooling system piping in which the rupture accident occurred even after the reactor has stopped operating, and to circulate the cooling gas through the reactor core, the reactor can be restarted as soon as possible. It is possible to bring the temperature down to a low temperature. However, if we assume that a rupture accident occurs in the pipe at the location indicated by the symbol P in Figure 7, we will assume that forced circulation of gas is performed using the healthy primary cooling system pipe 6 on the left. However, some of the gas discharged into the pressure vessel 1 through the inlet pipe 9 leaks out of the system through the fracture point P before flowing through the reactor core 2, as shown by the dotted arrow, and conversely leaks out of the system through the high-temperature preform. A mixture of air and helium gas is sucked into section 5 from outside the system. As a result, a sufficient flow rate of gas flowing through the reactor core section 2 cannot be secured, and the reactor core cannot be effectively cooled. −

[Purpose of the Invention] This invention has been made in consideration of the above points, and its purpose is to repair other healthy primary cooling system pipes other than the loop in which the rupture accident occurred even when a rupture accident occurs in the primary cooling system pipe. By using channels to enable forced circulation of cooling gas through the reactor,
An object of the present invention is to provide a gas-cooled nuclear reactor in which the core can be directly cooled by gas. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a primary cooling system for a plurality of loops connected to a pressure vessel of a nuclear reactor. A gas flow rate limiting mechanism is installed in series with the cooling system pipeline and limits the gas flow in the pipeline when the primary cooling system pipeline breaks, and the operation of the gas flow rate limiting mechanism causes the primary cooling system to While restricting gas flow leakage from the cooling system pipes, the system ensures a flow rate of circulating gas flowing through the healthy side loop within the reactor core to bring the reactor to a low temperature as soon as possible.

[Embodiments of the invention]

FIG. 1 is a schematic configuration diagram of an umbrella body of a gas-cooled nuclear reactor equipped with a gas flow rate restriction mechanism according to an embodiment of the present invention; FIG.
3, 4, 5, and 6 each show the structure of different embodiments of the gas flow rate limiting mechanism,
In FIG. 1, for each primary cooling system pipe line 6 connected to the pressure vessel 1, a gas flow rate ratio mechanism indicated by the reference numeral 12 is installed inside the pressure vessel 1, facing the open end of the inlet pipe 9. ing. This gas flow rate restriction mechanism 12 is configured so that, when a rupture accident occurs in one of the plurality of loops of primary cooling system piping, the gas flow is passed through other healthy loops other than the loop in which the accident occurred. It serves to limit the bypass flow in which the supplied gas leaks to the outside through the fracture location.Next, several embodiments of this gas flow rate limiting mechanism will be described with reference to the drawings. First, the embodiments shown in FIGS. 2 and 3 show a gas flow rate limiting mechanism that is a sliding shutter mechanism.
Sliding type shaft installed in 3) anti-14a, 1
4b, and the rack-pinion mechanism 15
The drive device 16 is configured to open and close in the direction of the arrow through the drive device 16. Shutter 14a. 14b has a shape in which four semicircular parts corresponding to the outer shape of the outlet pipe 10 are cut out at the end, and is normally retracted to the solid line position, and by giving a command to the drive device 16,
It slides to the chain line position and operates to close the open end of the inlet pipe 9. With the above configuration, if a rupture occurs in the pipe line of the primary cooling system loop currently in operation of the furnace, a command is given to the drive device 16 of the gas flow rate restriction mechanism 12 of the loop where the rupture accident occurred. When the shutter plate is closed, the gas flow introduced into the pressure vessel through other healthy loops will not leak out of the system through the inlet pipe of the rupture loop, but will circulate through the reactor core and directly flow into the reactor core. Gas cooled. Note that since the gas flow that has passed through the reactor core directly passes through the high-temperature plenum and returns to the exit pipe 10 of the healthy loop, there is almost no possibility that outside air from outside the pressure vessel will be sucked in through the exit pipe of the broken loop. In the embodiments shown in FIGS. 4 and 5, rotating shutter plates 17a, 17 are used instead of the sliding shutter plates of the previous embodiments.
b is configured to be rotated 180 degrees as shown by the arrow between the open position shown by the solid line and the closed position shown by the chain line for opening and closing operations by the driving device 16. The embodiment shown in FIG. 6 differs from each of the above-described embodiments in that a fixed throttle mechanism 18, which serves as a gas flow rate limiting mechanism and serves as a ring-shaped orifice surrounding the outer periphery of the outlet pipe 10, is installed at the open end of the inlet pipe 9. . This fixed throttle mechanism 18 is set so that the throttle flow path resistance between it and the outer circumferential surface of the outlet pipe 10 is greater than the flow path resistance passing through the reactor core 2 shown in FIG. . This suppresses the occurrence of gas bypass flow as shown by the dotted arrow in Figure 7 when forced gas circulation is performed through other healthy loops when the rupture rate of 4 occurs in the primary cooling system pipes. This means that the flow rate of gas flowing through the reactor core can be secured. Although this embodiment is somewhat inferior in gas flow suppression effect as compared to the previously described embodiments, it does not require any moving parts or their driving devices, and therefore does not require maintenance and can provide high reliability. Also, during normal furnace operation, this fixed throttle mechanism 18 acts and the pressure loss in the gas circulation system increases to some extent, but this point can be prevented by setting the discharge pressure of the gas circulation machine to a somewhat high level. It is possible to perform gas circulation within the furnace without having to do so. In each of the above embodiments, the gas flow rate limit I! Construction force (both examples are shown in which it is installed on the outlet pipe side of the primary cooling system pipe, but this gas flow restriction mechanism number is installed on the outlet pipe side of the primary cooling system pipe, or between the inlet pipe and the outlet. Similar effects can be obtained even if the system is installed on both sides of the pipe. [Effects of the Invention] As described above, according to the present invention, the primary cooling system with multiple loops connected to the pressure vessel Regarding the pipelines, a gaff and a flow rate side p1 mechanism are arranged in series with each of the loop cooling system pipelines on the inner side of the pressure vessel to restrict the gas flow in the pipeline when the primary cooling system pipeline is broken. By installing this system, in the event that a rupture occurs in the primary cooling system pipe of one of the loops during operation of the furnace, other healthy loops are operated to perform forced gas circulation inside the furnace. It is possible to suppress the generation of gas bypass flow in the loop on the rupture side, thereby ensuring a sufficient flow rate of gas flowing through the reactor core, and quickly cooling the reactor with gas after shutdown to bring it to a low temperature. be able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a gas-cooled nuclear reactor equipped with a gas flow rate restriction mechanism according to an embodiment of the present invention, and FIGS. FIG. 6 is a longitudinal cross-sectional view and a plan view showing the structure of different embodiments of the flow rate restriction mechanism, FIG. 6 is a cross-sectional view of the structure of a further different embodiment, and FIG. 7 is a cross-sectional view of the structure of a conventional gas-cooled nuclear reactor. 1: Pressure vessel, 2: Reactor core, 6: Primary cooling system pipes, 9:
Inlet pipe, 10: Outlet pipe, 12: Gas flow rate restriction side L14a
, 14b Ni-slide shutter plate, 16F shutter plate drive device, 17a, 17b: rotating shutter plate,
18: Fixed aperture mechanism.

Claims (1)

[Claims] 1) In a gas-cooled nuclear reactor in which a plurality of loops of primary cooling system pipes are connected to a pressure vessel housing a reactor core, the primary cooling system of each loop is connected to the inside of the pressure vessel. 1. A gas-cooled nuclear reactor, characterized in that a gas flow rate limiting mechanism is installed in series with a system pipe and limits the gas flow in the pipe when the primary cooling system pipe is broken. 2) In the gas-cooled nuclear reactor according to claim 1, the gas flow rate restriction mechanism is installed corresponding to at least one side of the inlet and outlet pipes of the primary cooling system pipe line drawn out from the pressure vessel. A gas-cooled nuclear reactor characterized by: 3) In the gas-cooled nuclear reactor according to claim 1, when a rupture accident occurs in the primary cooling system pipe, the gas flow rate restriction mechanism closes the opening end of the rupture accident pipe to the pressure vessel. 1. A gas-cooled nuclear reactor characterized by a shutter mechanism consisting of a shutter plate and a shutter plate drive device that operate to close the reactor. 4) In the gas-cooled nuclear reactor according to claim 1, the gas flow rate limiting mechanism is a fixed throttle mechanism whose throttle resistance is set to be greater than the gas flow path resistance through the reactor core. A gas-cooled nuclear reactor featuring: