JPS58180992A - 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 Emergency core cooling suitable for the emergency cooling system of the present invention #i nuclear reactor, especially for a reactor having a spray nozzle that sprays cooling water from above the fuel assembly in the shroud. Regarding piping.

%1155-164274, in a nuclear reactor with a sub-reactor cooling water circulation pump built into the reactor pressure vessel, there is a system in which emergency core cooling water is spray-cooled from above the fuel assembly in the shroud. A two-system emergency core cooling system has been adopted: injected into the annular area between the reactor pressure vessel and the 7th floor, and cooled from below through the shroud support leg. However, when cooling water is injected into the annular portion between the reactor pressure vessel and the shroud, low-temperature water flows directly onto the high-temperature vessel wall. This may cause a sudden thermal shock to the container wall, potentially damaging the integrity of the container.

The object of the present invention is to eliminate the drawbacks of the above-mentioned prior art;
To provide an emergency core and water injection piping that can cool the reactor core in an emergency without impairing the integrity of the reactor pressure vessel.

The feature of the present invention is that the emergency core cooling water is injected from the reactor pressure vessel nozzle into the upper part of the shroud head by connecting it with in-reactor piping at the upper part of the shroud head.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a conceptual diagram of the Katsu reactor with a built-in Fi primary cooling water circulation pump. FIG. 2 shows a detailed longitudinal cross-sectional view of FIG. 1.

In Fig. 2, the ninth emergency core spray 10, which sprays and cools the emergency core cooling water from above the fuel assembly 8 in the shroud 2 in the event of an emergency, is fixed to the shroud head 6, and the emergency core cooling water is sprayed from above. The nozzle 11 is connected to a bent furnace pipe 13 which is connected by a slip joint 12 .

As mentioned above, the emergency core cooling system includes a water injection system that directly sprays water from the top of the fuel assembly, as well as a water injection system to supplement the coolant that has flowed out due to pipe rupture and to clean the core.

Conventionally, this water injection system has been proposed in Japanese Patent Application No. 55-164274, in which water is injected from a reactor pressure vessel nozzle into the downcomer section A shown in Figure 1, descends through this section, and flows into the lower plenum B.
It was designed to cool the reactor core Ct after 100 ms. However, in this case, the injected cold water directly hits the high-temperature reactor pressure vessel wall, and there is a risk that the integrity of the vessel may be damaged due to thermal shock.

Therefore, in the present invention, as shown in Figure 3, the emergency water injection nozzle 14 is attached to the shroud head 6 with 16t of bent reactor piping connected by the stop joint 15, and the injected emergency core cooling water is injected from the upper part of the shroud head. It is designed to be injected into the shroud. If the in-furnace piping is installed in the part of the shroud 2 below the upper grid plate 7, if the piping connected to the emergency water injection nozzle 14 were to break, the water level in the shroud would drop due to the siphon effect. In order to avoid this problem, the shroud head 6 is placed above the upper grid plate 7, and above the reactor water spray IO so as not to adversely affect the water distribution of the core spray 10. At the time of fuel exchange, the curved furnace pipe 16 is detached from the slotted pipe 15 and can be removed together with the shroud head 6, so that it does not interfere with the fuel exchange.

According to the present invention, it is possible to inject the cooling water necessary for cooling the reactor core in an emergency without risking damage to the integrity of the reactor pressure vessel, thereby improving the safety and reliability of the reactor. can.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of a nuclear reactor with a built-in primary cooling water circulation pump.
Figure 2 is a longitudinal sectional view of Figure 1, Jll! FIG. 3 is a detailed diagram of the emergency core water injection piping of the present invention. 14...Emergency core water injection nozzle, 15...Slip joint, 16...Curved in-core piping.

Claims (1)

[Claims] 1. Reactor primary cooling water circulation pump tm In a nuclear reactor built in the child reactor pressure vessel, emergency core cooling water is supplied to the reactor piping having a removable slip joint or bellows from the reactor pressure vessel nozzle. A nuclear reactor with a structural t% image of water injection into the upper part of the Yosho shroud head.