JPS62269090A - Nuclear 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] (Industrial application field) The present invention relates to nuclear reactors.

(Conventional technology) A conventional fast breeder reactor will be explained with reference to FIG.

(1) is a reactor vessel, (2) is a partition plate that partitions the inside of the reactor vessel (1) into an upper plenum and a lower plenum, (3)
The reactor core 1 (4) is an inlet nozzle provided at the lower part of the reactor vessel (1), (5) is the upper reactor mechanism located above the upper surface of the reactor core (3), and (6) is the upper part of the reactor. Mechanism (5)
The flow guide member (7) installed at the lower end of the reactor vessel (1) is the outlet nozzle installed in the middle of the reactor vessel (1), and the coolant flows from the inlet nozzle (4) to the lower plenum of the reactor vessel (1). It flows into the reactor core (3).

It is heated here, flows out to the upper plenum, hits the flow guide member (6), flows laterally, turns upward, continues to rise while mixing with the coolant in the upper plenum, and flows to the upper part of the upper plenum. From there, it turns around, descends, and flows out of the reactor vessel (1) from the outlet nozzle (7). Note that during rated operation of the reactor, the force of high-temperature coolant flowing out from the reactor core (3) to the upper plenum is strong. If this high-temperature coolant flows upward into the upper plenum, the flow of high-temperature coolant will reach the liquid level in the furnace, causing problems such as turbulence of the liquid level and entrainment of air bubbles into the coolant. The reason why the flow guide member (6) is disposed above the upper surface of the reactor core (3) to once flow the high temperature coolant from the reactor core (3) sideways is to prevent the entrainment of air bubbles and the like.

(Problem to be solved by the invention) During operation of a fast breeder reactor, if the operation is suddenly stopped for some reason, control rods are inserted into the reactor to stop the nuclear reaction. Low-temperature coolant flows into the plenum and gives a thermal shock to the walls of the reactor vessel (1). In order to reduce the thermal shock at this time, an operating method is adopted in which the flow rate of the coolant flowing into the reactor vessel (1) from the artificial nozzle (4) is reduced at the same time as the reactor is stopped. At this time, the conventional fast breeder reactor shown in FIG. 7 has a first-order problem. That is, from the inlet nozzle (4) to the reactor vessel (
1) Reducing the flow rate of coolant flowing into the reactor core (3
) to the upper plenum becomes weaker. At that time, if the flow of low-temperature coolant is upward, the low-temperature coolant will sufficiently mix with the high-temperature coolant that was in the upper plenum before the reactor shutdown, and a layer of high-temperature coolant will form at the top of the upper plenum. However, in the fast breeder reactor shown in FIG. 7, the flow guide member (7) attached to the lower end of the upper reactor mechanism (5) does not form a low-temperature coolant layer at the bottom. is a horizontal plate shape, and the low-temperature coolant with low momentum changes its direction laterally, so the low-temperature coolant does not mix with the high-temperature coolant that was in the upper plenum before the reactor was shut down.1 There was a problem in that a high-temperature coolant layer was formed in the upper part of the upper brenum and a low-temperature coolant layer was formed in the lower part, giving a thermal shock to the reactor vessel (1) wall and the like.

(Means for Solving the Problems) The present invention addresses the above-mentioned problems by attaching a flow guide member having an opening to the lower end of the reactor upper mechanism located above the upper surface of the reactor core. Relating to a nuclear reactor characterized in that a shape memory alloy guide plate is attached to the flow guide member;
The purpose of this is to transfer coolant from the core to high-temperature coolant in the upper plenum, both during rated operation when high-temperature coolant flows out from the core, and during sudden reactor shutdowns when low-temperature coolant flows out from the core. The object of the present invention is to provide an improved nuclear reactor that is capable of sufficient mixing.

(effect) The nuclear reactor of the present invention is constructed as described above.

During rated operation when high temperature coolant flows out of the core.

A shape memory alloy guide plate closes the opening provided in the flow guide member. As a result, the powerful high-temperature coolant flowing out from the first reactor hits the flow guide member and the shape memory alloy guide plate, flows laterally, and then begins to rise, mixing with the coolant in the upper plenum as it continues to rise. . Also, during a sudden shutdown of a nuclear reactor where low-temperature coolant flows out from the core.

The shape of the shape memory alloy guide plate is changed by the low temperature coolant to open an opening provided in the flow guide member. Therefore, the low-temperature coolant flowing out from the reactor core flows upward through the opening provided in the flow guide member, and the low-temperature coolant sufficiently mixes with the high-temperature coolant in the upper plenum.

(Example) Next, the nuclear reactor of the present invention will be explained with reference to an example shown in FIGS. The reactor upper mechanism (6) is located above the upper surface of the reactor upper mechanism, the flow guide member (6) is attached to the lower end of the reactor upper mechanism (5), and (6a) is radially attached to the outer periphery of the flow guide member (6). multiple openings provided,
(8) is a shape memory alloy guide plate whose negative side edge is fixed to the same flow guide member (6), and the same shape memory alloy guide plate (8) changes the temperature of the coolant coming out of the core (3). The shape changes due to

Each opening (6a) is opened when low temperature coolant (low temperature coolant of about 300 to 400'') flows out.

Next, the operation of the nuclear reactor shown in FIGS. 1 to 4 will be described in Section 5.
This will be explained in detail with reference to FIG. As shown in Figure 5, during rated operation when high-temperature coolant flows out from the core (3), the shape memory alloy guide plate (8) closes the opening (6a) provided in the flow guide member (6). . Therefore, the reactor core (
The strong high-temperature coolant flowing out from 3) hits the flow guide member (6) and the shape memory alloy guide plate (8) and flows laterally, then turns upward and mixes with the coolant in the upper plenum. continue to rise.

Furthermore, as shown in Fig. 6, during sudden shutdown of the reactor when low-temperature coolant flows out from the reactor core (3), the shape of the shape memory alloy guide plate (8) changes due to the low-temperature coolant, and the flow guide member ( The opening (6a) provided in 6) is opened. Therefore, the low-temperature coolant flowing out from the core (3) flows upward through the opening (6a) provided in the flow guide member (6), and the low-temperature coolant flows into the high-temperature coolant in the upper brenum. Mix thoroughly.

(Effects of the Invention) As described above, in the nuclear reactor of the present invention, during rated operation in which high-temperature coolant flows out from the core, the shape memory alloy guide plate closes the opening provided in the flow guide member, and the flow of high-temperature coolant from the core is accelerated. After the strong high temperature coolant hits the flow guide member and the shape memory alloy guide plate and flows laterally, it begins to rise and continues to rise while mixing with the coolant in the upper brenum. In addition, during a sudden shutdown of a nuclear reactor when low-temperature coolant flows out from the core, the shape of the shape memory alloy guide plate changes due to the low-temperature coolant, openings in the flow guide member are opened, and the flow of low-temperature coolant from the core is accelerated. The weaker low temperature coolant flows upwardly through the openings provided in the flow guide member, and the low temperature coolant mixes well with the high temperature coolant in the upper brenum.

Even during rated operation when high temperature coolant flows out of the core.

Even in the event of a sudden shutdown of a nuclear reactor where low-temperature coolant flows out from the core,
This has the effect of sufficiently mixing the coolant from the core with the high-temperature coolant in the upper brenum.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the nuclear reactor according to the present invention, Fig. 2 is a longitudinal side view showing the open position of the guide plate made of shape memory alloy, and Fig. 3 is a flow guide member and the shape memory alloy made guide plate. FIG. 4 is a plan view of the guide plate, and FIG. 4 is a plan view showing the shape memory alloy guide plate in the open position. Figure 5 is an explanatory diagram showing the flow of high temperature coolant during rated operation;
FIG. 6 is an explanatory diagram showing the flow of low-temperature coolant during sudden shutdown of a nuclear reactor, and FIG. 7 is a longitudinal side view showing a conventional nuclear reactor. (3)...Reactor core, (5)...Reactor upper mechanism, (6
)...flow guide member, (6a)...opening, (8)...shape memory alloy guide plate. Sub-agent Patent Attorney Shigefumi Okamoto and two others Figure 5

Claims (1)

[Claims] A flow guide member having an opening is attached to the lower end of the reactor upper mechanism located above the upper surface of the reactor core, and its shape changes due to temperature changes of the coolant coming out of the core, and the opening is closed when low temperature coolant flows out. A nuclear reactor characterized in that an openable guide plate made of a shape memory alloy is attached to the flow guide member.