JPH05157876A - Tank type fast breeder reactor - Google Patents

Abstract

PURPOSE:To prevent the entrainment of gas into the primary side coolant inflow port of an intermediate heat exchanger by large turning flow generated around the intermediate heat exchanger by a spiral deflecting plate. CONSTITUTION:A spiral deflecting plate 18 is installed at an intermediate heat exchanger 6, from its primary side coolant inflow port to its upper coolant level, and large turning flow is formed around the intermediate heat exchanger 6 so as to prevent the generation of a local vortex to be the cause of gas entrainment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank type reactor capable of preventing gas entrainment in an intermediate heat exchanger.

[0002]

2. Description of the Related Art In a fast breeder reactor, which is the next generation of nuclear power generation, an intermediate heat exchanger and a pump are arranged outside the reactor vessel, and a loop type reactor for circulating coolant by connecting pipes between them. There is a tank type furnace in which an intermediate heat exchanger and a pump are installed in a furnace vessel to circulate a coolant.

Compared with the loop type furnace, the tank type furnace has the advantage that the piping is not required and therefore the economy and safety are high and the plant can be downsized.

FIG. 3 shows a schematic structure of a tank-type nuclear reactor. At the center of a reactor vessel 1, a core 2 composed of a core fuel assembly and a blanket fuel assembly is installed.

The furnace vessel 1 is filled with a primary side coolant 4 (generally liquid metal sodium). Above the core 2, a core upper part mechanism 5 is provided penetrating the roof slab 3. Further, a plurality of intermediate heat exchangers 6 and a plurality of pumps 7 are arranged in the furnace vessel 1 so as to be circumferentially separated from each other. The pump 7 is driven by a pump drive motor installed on the roof slab 3.

The intermediate heat exchanger 6 includes a large number of heat transfer tubes for flowing down the coolant 4 flowing from the primary side coolant inlet port 8 and secondary side cooling for sending the secondary side coolant around these heat transfer tubes. It is composed of a material inlet pipe and a secondary side coolant outlet pipe heated around the heat transfer pipe.

A partition wall 9 is installed at the height of the upper end of the core in the reactor vessel 1, and is divided into an upper plenum 10 and a lower plenum 11. Reference numeral 13 denotes an inlet pipe, which connects the high pressure plenum 12 formed below the core 2 and the pump 7.

An inert cover gas 14 such as argon gas is filled above the coolant in the furnace vessel 1. 1
Reference numeral 5 indicates a coolant liquid level.

In the tank type reactor having such a structure, the coolant on the lower plenum 11 side in the reactor vessel 1 is pressurized by the pump 7, sent to the high pressure plenum 12 through the inlet pipe 13, and heated by the reactor core 2. As it rises, it changes the flow in the horizontal direction near the core upper part mechanism 5, flows into the intermediate heat exchanger 6 from the primary side coolant inlet 8, and cools down the secondary side while flowing down in the heat transfer tube. After being cooled by exchanging heat with the secondary side coolant (generally liquid metal sodium) that flows in from the material inlet pipe and flows outside the heat transfer pipe, the lower plenum 1
1 and again pressurized by the pump 7 to the high pressure plenum 1
It is sent to the core 2 via 2

Further, in the suspension cylinder system in which the core 2 is suspended on the roof slab 3 via the suspension cylinder 19 (FIG. 4), the primary-side coolant in the furnace container is penetrated to the vertical center of the suspension cylinder 19. Although it flows through the provided flow hole 20 and flows into the primary side coolant inlet 8, the flow in the vicinity of the intermediate heat exchanger 6 is the same as the above case.

On the other hand, the secondary-side coolant heated by heat exchange with the primary-side coolant 4 is guided to a steam generator (not shown) through the outlet pipe 16 to transfer the heat generated by the core 2 to the steam system. Tell.

As described above, the heat of the core 2 is transferred to the intermediate heat exchanger 6
Is transmitted to the secondary side by the high temperature primary side coolant 4
Flows around the outside of the intermediate heat exchanger 6 toward the inflow ports 8 provided by being divided in the circumferential direction of the intermediate heat exchanger 6, so that the clockwise direction flowing around the intermediate heat exchanger 6 is generated. A local eddy current is likely to occur at the point where the flow and the counterclockwise flow merge.

If a vortex flow is generated, the cover gas 14 may be entrained in the main coolant flow as fine bubbles.
When the cover gas 14 is entrained in the main coolant flow, the bubbles are sent to the core 2 by the pump 7 together with the coolant 4.

The cover gas 14 sent to the core 2 is heated by the core 2 and increases its volume, so that the contact between the core 2 and the coolant 4 is partially obstructed. Therefore, the core portion in contact with the cover gas 14 is in a heated state, and in the worst case, there is a possibility of developing a serious accident of core melting.

As a means for preventing the entrainment of the cover gas 14, for example, as shown in Japanese Patent Laid-Open No. 1-217292 (FIG. 5), a swirl preventive plate 17 is attached to the upper portion of the temporary side coolant inlet of the intermediate heat exchanger. A method has been devised to prevent swirling and turbulence that cause gas entrainment by suppressing the swirling component of the flow of coolant at the inlet and its upper part. However, since gas entrainment occurs due to the local generation of eddy currents, in order to prevent the occurrence of eddy currents, it is necessary to make the intervals of the eddy current prevention plates 17 close or widen the length of the eddy current prevention plates. In this case, an increase in weight and a complicated structure pose problems.

[0016]

As described above,
In the conventional tank reactor, the inlet 8 of the intermediate heat exchanger 6
A eddy current is likely to be generated in the vicinity of, and in that case, as a result of the cover gas 14 being entrained in the coolant main flow, the integrity of the core 2 may be impaired, and a serious accident may be caused.

The present invention has been made to solve this problem. By preventing gas entrapment in the intermediate heat exchanger 6 without complicating the structure, the soundness of the core 2 is ensured and reliability is improved. An object is to provide a highly efficient tank furnace.

[0018]

The tank-type reactor of the present invention is a tank-type reactor in which an intermediate heat exchanger and a pump are installed in a reactor vessel. It is characterized in that a spiral deflection plate is provided.

[0019]

In the present invention, by providing a spiral deflection plate on the upper part of the inlet of the outer wall of the intermediate heat exchanger, a spiral swirl is imparted to the coolant sucked from the upper part of the inlet, and the spiral is provided around the intermediate heat exchanger. By forming a large swirl flow, the generation of local vortices is prevented. Further, even if a local minute vortex is generated, since the coolant swirls in a spiral shape, the distance to the inlet becomes longer than in the conventional case, so that the cover gas hardly reaches the inlet. This is for the following reason.

When gas entrapment occurs, the entrained gas is transported with a constant inertial force, and the inertial force gradually decreases due to friction with the surrounding fluid during transportation.
Since the gas itself is in the liquid and buoyancy is applied, the reaching distance of the entrained gas is determined by the balance between the inertial force and buoyancy of the gas. In other words, as the distance between the free liquid surface part in which the gas is entrained and the inflow port becomes longer, the entrained gas becomes hard to reach the inflow port.

[0021]

1 and 2 show an embodiment of the present invention. A spiral deflection plate 18 is provided above the plurality of temporary side coolant inlets 8 which are circumferentially divided and provided substantially vertically in the center of the intermediate heat exchanger 6 installed in the furnace vessel 1. Attach. As shown in FIG. 1, the deflecting plate 18 spirally swirls the coolant from above from the coolant surface 15 to the upper end of each coolant inlet, and guides it to the coolant inlet 8. Install.

The deflector plate 18 does not necessarily have to cover the whole, and may be partially attached so that a spiral rotation can be formed as shown in FIG.

In the thus constructed tank-type furnace of the present invention, the coolant 4 which has become high temperature by cooling the core 2 flows as shown by the arrow in FIG. 3 and flows from the inlet 8 to the intermediate heat exchanger 6. Flow into. At that time, the coolant flowing from above is carried by the entrainment action, and at that time, the intermediate heat exchanger 6
The spiral deflection plate 18 installed at the position causes the flow generated by the entrainment to swirl, so that a large swirl flow is generated around the intermediate heat exchanger, and a local vortex is less likely to be generated. Even if an entrainment vortex occurs, the spiral swirl increases the distance to the inlet, and the inertial force of the gas entrained by the vortex is canceled by the friction with the liquid and the buoyancy, so the cover gas is It becomes difficult to reach the inflow port 8.

[0024]

In the tank reactor according to the present invention, since the spiral deflection plate is installed above the coolant inlet port on the outer wall of the intermediate heat exchanger, the cover for the inlet port of the intermediate heat exchanger is provided. Entrapment of gas is prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a tank reactor.

FIG. 4 is a cross-sectional view of a suspended barrel tank reactor.

FIG. 5 is a cross-sectional view of a conventional example and a flow pattern according to the conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor vessel, 4 ... Primary side coolant, 5 ... Core upper part mechanism, 6
... Intermediate heat exchanger, 8 ... Primary side coolant inlet port, 9 ... Partition wall,
14 ... Cover gas, 15 ... Coolant liquid level, 18 ... Deflection plate.

Claims (3)

[Claims] 1. A tank-type fast breeder reactor having an intermediate heat exchanger and a pump suspended from a roof slab in a reactor vessel, and having a primary-side coolant liquid level in the reactor vessel, wherein the intermediate heat exchange is performed. A tank type fast breeder reactor characterized in that a structure for giving a swirl around the intermediate heat exchanger is provided in the coolant above the primary side coolant inlet of the reactor. 2. The tank type fast breeder reactor according to claim 1, wherein a spiral deflection plate is provided as the structure from the upper part of the inlet of the primary side coolant of the intermediate heat exchanger to the liquid surface. 3. The tank according to claim 1 or 2, wherein the deflection plate is partially provided to such an extent that a spiral swirl is given to the coolant above the primary coolant inlet of the intermediate heat exchanger. Type fast breeder reactor.