JPH0249593Y2 - - Google Patents

Description

[Detailed explanation of the idea] This project concerns the improvement of fast breeder reactors.

A conventional fast breeder reactor is explained using Figure 1.
a is a reactor vessel in which a core b is formed and a coolant outlet nozzle c is formed in the body above the core b; d is a reactor vessel in which a reactor core B is formed inside the reactor vessel a;
an inner cylinder f that is located above the container a and defines an annular space e between it and the inner surface of the container a;
is a plurality of flow holes drilled in the same inner cylinder d, g
is the upper core mechanism, h is the shielding plug, i is the pedestal, and j is the seal gas. When the reactor is tripped by some signal, it goes into low flow operation and low-temperature liquid metal sodium flows from the core b into the upper plenum k. (hereinafter referred to as sodium) flows out.
Because the flow rate of the low-temperature sodium at this time is low, it does not mix with the high-temperature sodium m remaining in the upper plenum k, and the upper plenum k is separated and defined into an upper high-temperature sodium region and a lower low-temperature sodium region. (A stratification phenomenon occurs), resulting in a large temperature difference. The interface between the high-temperature sodium region and the low-temperature sodium region gradually rises as the low-temperature sodium 1 flows out, and when it reaches the lowest edge of the plurality of flow holes f provided in the inner cylinder d, a portion of the low-temperature sodium 1 flows out from each flow hole f into the annular space e and toward the coolant outlet nozzle o. However, since only a portion of the low-temperature sodium l flows from the flow hole f to the outlet nozzle o, the boundary surface continues to rise and finally exceeds the upper edge of the inner cylinder d, overflowing from there to the outlet nozzle c. It's starting to move towards.

In the fast breeder reactor, each of the flow holes f is provided at approximately the same height position in the inner cylinder d, and the distance of the flow hole f to the outlet nozzle c differs for each flow hole f, so that the boundary surface From reaching the lowest edge of each flow hole f to passing the upper edge of the inner cylinder d, the low temperature sodium reaches the outlet nozzle c at different times, and the outlet nozzle c undergoes thermal shock in an axially asymmetric manner. There was a problem with receiving it.

This proposal addresses the above-mentioned problems, and consists of a reactor vessel with a reactor core formed inside, and a plurality of cooling units installed horizontally at intervals in the body of the reactor vessel above the reactor core. It has a material outlet nozzle, and an inner cylinder installed in the reactor vessel above the reactor core to form an annular space between it and the inner surface of the reactor vessel. A fast breeder reactor is characterized in that a plurality of flow falls are bored at intervals on a substantially wave-shaped virtual line along the cylindrical upper half of a coolant outlet nozzle, the purpose of which is to provide cooling. The object of the present invention is to provide an improved fast breeder reactor in which the structural integrity of the outlet nozzle can be improved simply by subjecting the outlet nozzle to thermal shock in an axially symmetrical manner.

Next, the fast breeder reactor of the present invention will be explained with reference to an embodiment shown in Figs. The formed reactor vessel 4 is provided in the reactor vessel 1 above the reactor core 2, and an inner cylinder 6a to 6a defines an annular space 5 between it and the inner surface of the vessel 1. 6e is the same inner cylinder 4
A plurality of flow holes are formed in the inner cylinder 4, and each of the flow holes 6a to 6e is spaced apart from each other on a substantially wave-shaped imaginary line along the upper half of the cylinder of each of the coolant outlet nozzles 3 in the inner cylinder 4. It is drilled at Further, 7 is a core upper mechanism, 8 is a shielding plug, 9 is a pedestal, and 10 is a cover gas.

Next, the operation of the fast breeder reactor will be explained. When the reactor is tripped by some signal, it goes into low flow operation and low temperature sodium flows out from the core 2 into the upper plenum 11. At this time, the low-temperature sodium does not mix with the high-temperature sodium remaining in the upper plenum 11 due to its low flow rate, and
1 is separated and defined into an upper high-temperature sodium region and a lower low-temperature sodium region (a stratification phenomenon occurs), resulting in a large temperature difference. The interface between the high-temperature sodium region and the low-temperature sodium region gradually rises as the low-temperature sodium flows out, and when it reaches the lowest flow hole 6e or higher, the low-temperature sodium flows from the upper plenum 11 through the flow hole 6e into the annular space. It begins to flow to 5. Also, the above boundary surface is the second flow hole 6d from the bottom.
If the temperature rises above, the low-temperature sodium will reach upper plenum 1
1 begins to flow out into the annular space 5 through the flow hole 6d. Similarly, the above boundary surfaces are 6c, 6
When the temperature rises above b, 6a, low-temperature sodium flows from inside the upper plenum 11 to the same flow holes 6c, 6b,
The distance between each flow hole 6e to 6a and the inner cylinder side opening of the outlet nozzle 3 is the same as that of each flow hole 6e to 6a.
Since the setting is such that the low-temperature sodium reaches the outlet nozzle 3 at the same time, the low-temperature sodium reaches the outlet nozzle 3 at the same time, and the outlet nozzle 3 receives a thermal shock almost axially symmetrically. The structural integrity of the outlet nozzle 3 is enhanced.

[Brief explanation of the drawing]

Figure 1 is a vertical side view showing a conventional fast breeder reactor.
Figure 2 is a longitudinal cross-sectional side view showing an embodiment of the fast breeder reactor according to the present invention, Figure 3 is a cross-sectional plan view of the inner cylinder portion, and Figure 4 is a developed view of the inner cylinder seen from the direction of the arrow in Figure 3. be. DESCRIPTION OF SYMBOLS 1... Reactor vessel, 2... Core, 3... Coolant outlet nozzle, 4... Inner cylinder, 5... Annular space, 6a
~6e...Flow hole.

Claims (1)

[Scope of utility model registration request] a reactor vessel having a reactor core formed therein; a plurality of coolant outlet nozzles provided at intervals in the horizontal direction in the body of the reactor vessel above the reactor core; an inner cylinder installed in the reactor vessel to form an annular space between it and the inner surface of the reactor vessel; A fast breeder reactor characterized in that a plurality of flow holes are bored at intervals on an imaginary line of a substantially waveform.