JPH08146173A - Vortex preventing device of fast breeder reactor - Google Patents

Abstract

PURPOSE: To prevent gas entrainment from the liquid surface to the reactor core so as to improve the safety of a fast breeder reactor. CONSTITUTION: A double cylinder (inner and outer cylinders) 5, 6 having many opening parts on the side surface is fitted to the lower part of a reactor core upper structure. A trumpet-like shroud 17 having many opening parts on the base and the side is fitted to the lower part of the double cylinder 5, 6. Horizontal guide plates 11 having many opening parts are installed in plural stages vertically in the interior of the double cylinder 5, 6, and a high temperature fluid is let flow radially, substantially horizontally and uniformly from the respective opening parts provided on the side of the double cylinder 5, 6 to an upper plenum 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antivortex device for a fast breeder reactor.

[0002]

2. Description of the Related Art A conventional fast breeder reactor will be described with reference to FIGS. 3 and 4. 1 is three inlet tubes, 2 is a coolant header, 3 is a reactor core, 7 is an upper plenum, and 8 is an outlet tube. , 9 is a reactor vessel, 10 is four heat exchangers, 12 is a cylindrical core upper structure, 13 is a bottom surface of the same core upper structure 12, 14 is a liquid surface, and the reactor upper structure is 3 loops. In this case, the three inlet pipes 1, the three outlet pipes 8 and the four heat exchangers 10 surround the cylindrical core upper structure 12, and only the dowel part of each outlet pipe 8 is separated from the core 3. Is opened as a fluid discharge passage.

Each inlet pipe 1 and each heat exchanger 10 stand in a reactor vessel 9 above the reactor core 3. The core upper structure 12 is located above the core 3, and the bottom surface 13 of the core upper structure 12 faces the top surface of the core 3 with a slight distance. In the fast breeder reactor, the high-temperature fluid from the core 13 collides with the bottom surface 13 of the core upper structure 12, diffuses in four directions as a jet flow, reaches the inner wall surface of the reactor vessel 9, rises, and rises at the liquid level 14. Inverted to become the inverted flow 15 (Fig. 4
(See (a) to (c)), each outlet pipe 8 is adapted to be discharged.

[0004]

In the conventional fast breeder reactor shown in FIGS. 3 and 4, the high temperature fluid from the core 13 collides with the bottom surface 13 of the core upper structure 12 and diffuses in all directions as a jet flow. Reaches the inner wall surface of the furnace vessel 9 and rises to the liquid surface 1
Since it is reversed at 4 and becomes a reversal flow 15, a vortex 16 is generated in the liquid surface 14 at the rear portion of each outlet pipe 8 and each inlet pipe 1, and this vortex 16 causes gas from the liquid surface 14 to the core 3. Get involved.

In the fast breeder reactor, when gas is entrained in the core 3, the fuel rods are melted and output control becomes difficult. Therefore, entrainment of gas from the liquid surface 14 into the core 3 is absolutely not allowed. Typical examples of the cause of gas entrainment from the liquid surface 14 to the core 3 are "gas entrainment vortex on the liquid surface", "gas entrainment due to entrainment flow",
It is three of "gas entrainment by breaking waves". Among these, the "gas entrainment vortex of the liquid surface" is likely to occur at a portion where the swirling flow and the downward flow in the furnace vessel 9 interfere with each other. Further, the "gas entrainment due to the entrainment flow" is likely to occur at the portion of the liquid surface 14 where the horizontal flow velocity is large. Further, "gas entrainment due to breaking waves" is likely to occur at the drop portion where the jet flow rises upward from the liquid surface 14.

The present invention is proposed in view of the above problems, and an object of the present invention is to eliminate gas entrainment from the liquid surface to the core and to operate the fast breeder reactor safely.
Another object of the present invention is to provide a vortex preventive device for a fast breeder reactor that can improve the safety of the fast breeder reactor.

[0007]

In order to achieve the above object, a vortex preventive device for a fast breeder reactor according to the present invention comprises a double cylinder having a large number of openings on its side surface at the bottom of a core upper structure. Mounting, a trumpet-shaped enclosure plate with a large number of openings on the bottom and side surfaces is attached to the bottom of the double cylinder, and horizontal guide plates with a large number of openings are installed inside the double cylinder in a plurality of upper and lower stages. It is installed.

[0008]

As described above, the vortex preventive apparatus for a fast breeder reactor of the present invention has a double cylinder having a large number of openings on its side surface attached to the lower part of the core upper structure, and has a large number of openings on the bottom and side surfaces. Is attached to the lower part of the double cylinder, and by these double cylinders and the trumpet-shaped shroud, the total amount of the jet from the core does not go up to the inner wall surface of the reactor vessel. Flow, and then flow out radially to the upper plenum, substantially horizontally and evenly, so that the jet leaving the core does not directly go to the inner wall surface of the reactor vessel, and the rise of the liquid level is blocked,
Generation of vortices is prevented, gas entrainment from the liquid surface to the core is eliminated, and the fast breeder reactor is operated safely. In addition, horizontal guide plates with multiple openings are installed inside the double cylinder in a plurality of upper and lower stages, so that the high-temperature fluid radiates from the openings provided on the side surface of the double cylinder to the upper plenum in a substantially horizontal manner. , Outflow evenly. Then, the high temperature fluid that flowed out a little upwards became slightly downward, the high temperature fluid that flowed out a little downwards became a little upward, and they gathered together to make the flow velocity uniform, and at the liquid level, from the inner wall surface side of the furnace vessel to the center Since the flow becomes gentle to the side (the liquid surface velocity decreases), the safety of the fast breeder reactor is improved.

[0009]

EXAMPLE A vortex preventer for a fast breeder reactor according to the present invention will be described below with reference to an embodiment shown in FIGS. 1 and 2. 1 is three inlet pipes, 2 is a coolant header, 3 is a core, and 4 is a core. Is a bottom plate having a large number of openings, 5 is a double cylinder having a large number of openings on its side surface (inner cylinder), 6 is a double cylinder having a large number of openings on its side surface (outer cylinder), 7 is Upper plenum, 8 is three outlet pipes, 9 is a furnace vessel, 10 is four heat exchangers, 11 is a horizontal guide plate with many openings, 14 is a liquid surface, and 17 is a trumpet-shaped shroud. The double cylinders (inner and outer cylinders) 5 and 6 are attached to the lower part of the core upper structure (see 12 in FIGS. 3 and 4), and the bottom plate 4
Are attached to the lower part of the double cylinder (outer cylinder) 6, the horizontal guide plates 11 are mounted inside the double cylinder (inner cylinder) 5 in a plurality of upper and lower stages, and the trumpet-shaped enclosure plate 4 is doubled. Tube (outer tube)
It is attached to the bottom of 6.

The bottom plate 4, the double cylinders (inner and outer cylinders) 5, 6 and the horizontal guide plate 11 are integrally assembled and fixed to a flange (not shown) of the core upper structure. Next, the operation of the vortex prevention device for the fast breeder reactor shown in FIGS. 1 and 2 will be specifically described. The fluid flowing in from each inlet pipe 1 enters the core 3 from the coolant header 2, and the high temperature fluid exiting the core is
Each opening provided in the bottom plate 4 → Ascended through each opening provided in each horizontal guide plate 11 in the double cylinder (inner cylinder) 5 and provided on the side surface of the double cylinder (inner and outer cylinders) 5, 6. Radially and substantially horizontally flows out to the upper plenum 7 through each opening, traverses each outlet pipe 8 and each heat exchanger 10, and reaches the furnace vessel 9 (Fig. 2).
(See (a) to (c)), from the inside of the upper plenum 7 to the outlet pipe 8
To the next device (not shown), and then returns to the inside of the furnace vessel 9 via each inlet pipe 1 for recirculation.

At this time, the high temperature fluid is a double cylinder (inner and outer cylinders).
The hot fluid that has flowed out to the upper plenum 7 radially and substantially evenly from the openings provided on the side surfaces of 5 and 6, but the hot fluid that has flowed slightly upward is slightly downward, and the hot fluid that has flowed slightly downward is A little upturned, each other gathered,
The flow velocity becomes uniform, and at the liquid surface 14, a gentle flow from the inner wall surface side of the furnace vessel 9 to the center side (the liquid surface flow velocity decreases), so that the liquid surface is prevented from being dipped in.

[0012]

As described above, the vortex preventive device for a fast breeder reactor of the present invention has a double cylinder having a large number of openings on its side surface attached to the lower part of the core upper structure, and has a large number of openings on its bottom and side surfaces. The trumpet-shaped shroud provided in and is attached to the lower part of the double cylinder, and by these double cylinders and the trumpet-shaped shroud, the total amount of jet flow from the core is not directed to the inner wall surface of the reactor vessel. Since it is made to flow upward, and then to the upper plenum, it is made to flow radially, substantially horizontally, and evenly, so that the jet flow leaving the core is not directly directed to the inner wall surface of the reactor vessel, and it is possible to prevent the rise of the liquid level, The generation of vortices can be prevented, gas entrainment from the liquid surface to the core can be eliminated, and the fast breeder reactor can be operated safely.

Further, horizontal guide plates provided with a large number of openings are attached inside the double cylinder in a plurality of upper and lower stages, and hot fluid is radially radiated from the respective openings provided on the side surface of the double cylinder to the upper plenum. Make it flow out almost horizontally. Then, the high temperature fluid flowing out slightly upward is directed slightly downward, the high temperature fluid flowing out slightly downward is directed upward, and they are collected together to make the flow velocity uniform. Since the flow is made smooth (the liquid surface velocity is reduced), the safety of the fast breeder reactor can be improved.

[Brief description of drawings]

FIG. 1A is a plan view showing an embodiment of a vortex prevention device for a fast breeder reactor of the present invention, and FIG. 1B is a vertical side view.

2 (a) to 2 (c) are explanatory views of the operation of the vortex prevention device.

3A is a plan view of a conventional fast breeder reactor, and FIG. 3B is a vertical side view.

FIG. 4A is a plan view of the fast breeder reactor, FIG. 4B is an operation explanatory view taken along the line ao in FIG. 4A, and FIG. And FIG. 8D is an operation explanatory view taken along the line co-o of FIG.

[Explanation of symbols]

 1 inlet pipe 2 coolant header 3 core 4 bottom plate 5 double cylinder (inner cylinder) 6 double cylinder (outer cylinder) 7 upper plenum 8 outlet pipe 9 furnace vessel 10 heat exchanger 11 horizontal guide plate 14 liquid level 17 trumpet shape Shroud

Claims (1)

[Claims] 1. A double cylinder having a large number of openings on its side surface is attached to a lower portion of a core upper structure, and a trumpet-shaped shroud having a large number of openings on its bottom surface and side surfaces is provided at the bottom of said double cylinder. A vortex preventive device for a fast breeder reactor, characterized in that horizontal guide plates having a large number of openings are attached inside the double cylinder in a plurality of upper and lower stages.