JPS5952797B2 - Reactor core emergency cooling system - Google Patents

Description

[Detailed description of the invention] The present invention relates to a nuclear reactor core emergency cooling system.

In a boiling water reactor, a device for emergency cooling of a fuel assembly in the event of a loss of coolant accident is usually configured as follows.

That is, as shown in FIG. 1, a ring-shaped water distribution pipe 3 is provided in a pressure vessel 2 housing a reactor core 1 above the reactor core 1, and a plurality of spray pipes are distributed in the circumferential direction on this pipe. A nozzle 4 is provided to constitute an emergency cooling device.

When an accident occurs, cooling water is sprayed from the spray nozzle 4.

This water flows into the fuel element from the fuel element upper tie plate water flow hole and cools the fuel element.

However, in such conventional devices, the cooling water that has already flowed into the fuel element and participated in cooling turns into steam and rises inside the fuel element, so the cooling water is blown up and flows into the fuel element. There was a drawback that it was difficult to get into the market.

In addition, since the water flow holes in the upper tie plate of the fuel element are relatively small, the cooling water injected from the nozzle is stored on the tie plate and naturally flows down from the water flow holes and flows into the fuel element. , the velocity energy of the cooling water spouted from the nozzle is not utilized at all.

If such velocity energy could be utilized, a larger amount of cooling water could be allowed to flow into the fuel element than in conventional systems.

The present invention has been made in view of the above circumstances, and provides an emergency cooling system that can quickly inject a large amount of water into a fuel element in the event of a loss of coolant accident.

The invention will now be described in detail with reference to the drawings.

FIG. 2, in which the same parts as in FIG. The handle 6 is hollow as shown in the figure, and the handle 6 has a plurality of water flow holes selected from the water flow holes 8 of the upper tie plate 7 of the fuel element at suitable intervals in the member that contacts the tie plate. A plurality of branch nozzles 9 are provided.

For example, as shown in FIG. 4, the fuel elements 5 are divided into m adjacent groups, and the water supply pipe 1 of the handle 6 of each fuel element in the group is
0 and each branch of the four-branch pipe 11 arranged above them are connected by a flexible pipe 12.

The main pipe of the four-branch pipe 11 is connected to a branch 14 which is suspended from a pipe 13 provided in a grid pattern in the ring-shaped water pipe 3 in accordance with the arrangement of the groups of fuel elements.

In the figure, numerals 15, 16, and 17 indicate joints used for each connection, preferably one-touch joints that are easy to operate.

In addition, in FIG. 4, 18 indicates a water supply pipe.

In the apparatus of the present invention having the above configuration, the cooling water supplied from the water supply pipe 18 is transferred from the ring-shaped water pipe 3 to the lattice-shaped pipe 1.
The fuel is fed into the fuel element 5 from the water outlet 8 via the branch 14, the four-branch pipe 11 main pipe, each branch thereof, the flexible pipe, the bundle 6, and the branch nozzle 9.

As mentioned above, the cooling water is not stored on the tiebrae I, but is sent through the water flow hole while retaining its velocity energy, so it is not hindered by the steam blowing up inside the fuel element. can flow inside.

Therefore, a large amount of cooling water can flow into the fuel element in an emergency.

In addition, in the present invention, the operating bundle is hollow,
Since this is used as a header for allowing cooling water to flow into the fuel element, the increase in piping in the upper part of the core according to the present invention can be minimized.

In addition, the bundle and the upper tie plate can be made into a unit by combining them together, and in this case, assembly of the core is facilitated.

Furthermore, since flexible piping is used to connect the branch of the four-branch pipe and the bundle, and a one-touch joint is used for each connection joint, assembly is easy and the assembly time is significantly shortened.

FIG. 5 shows a modification of the above embodiment.

In this modification, the bundle 6 is hollow and shaped like an inverted U,
The lower ends of both legs are connected to appropriate water holes 8 of the tie plate 7, and a spray nozzle 19 is provided on the lower surface of the center piece.

In this modification, the cooling water is directly fed into the fuel element from both legs of the bundle 6 while retaining velocity energy, and at the same time, the spray from the nozzle 20 also flows through the water flow hole 8 of the tie plate. A larger amount of cooling water can be delivered into the fuel element than by spraying from a ring-shaped water pipe.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional emergency cooling device, Fig. 2 is a schematic diagram of an embodiment of the present invention, Fig. 3A is a sectional view of the main part of the embodiment of the present invention, and Fig. 3B is a perspective view thereof. FIG. 4 is a perspective view of the entire embodiment, and FIG. 5 is a perspective view of essential parts of a modification of the embodiment. 3... Ring-shaped water pipe, 5... Fuel element, 6... Operation bundle, 7... Upper tie plate, 8...・Water hole, 9...
・Branch nozzle, 11... Quadrant pipe, 13...
...Grid piping.

Claims (1)

[Scope of Claims] 1. A nuclear reactor core emergency cooling system having the following structural requirements. a Water pipe provided in the upper part of the reactor core to provide cooling water b Hollow operation handle provided at the upper end of each fuel element C Branch nozzle d that opens from the hollow part inside this handle to multiple water flow holes in the upper tie plate of the fuel element A branch pipe 2 that divides the fuel elements into groups destined for a plurality of adjacent locations and connects the handles of the fuel elements in each group to the water distribution pipe at once.The branch pipe and each operation handle are connected by a one-touch joint and The emergency cooling system for a nuclear reactor core according to claim 1, characterized in that the emergency cooling system is implemented by a flexible pipe.