JPS61147190A - Fast breeder 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 [Technical Field of the Invention] The present invention relates to a tank-type fast breeder reactor having a reactor wall cooling liner.

[Technical background of the invention]

A conventional tank-type fast breeder reactor will be explained with reference to FIG. In the figure, reference numeral 1 denotes a reactor vessel, in which a coolant 2 such as liquid metal sodium is accommodated. The reactor vessel 1 is open at the top, and a roof slab 4 is provided to close the opening 3. [Inside the sub-reactor vessel 1, there are a plurality of fuel assemblies (not shown) and control rods ( A reactor core 5 is installed, which includes a reactor core (not shown) and the like. This core 5 is supported at the bottom of the reactor vessel 1 by a core support mechanism 6. The core support mechanism 6 is also connected to a core support mechanism 6 that forms a high-pressure plenum 7 as a coolant inlet to the reactor core 5. A partition wall 8 is provided between the inner periphery of the furnace vessel 1 and partitions an upper plenum 9 above the partition wall 8 and a lower plenum 10 below the partition wall 8. An intermediate heat exchanger 11 is supported on the roof slab 4, and the primary system inlet hole 12 of the intermediate heat exchanger 11 is opened below the liquid level in the upper plenum 9, and the primary system outlet hole 13 is opened to the lower plenum 10. Furthermore, the secondary cooling system 14 of the intermediate heat exchanger 11 is connected to a steam generator (not shown) from above the roof slab 4. Intermediate heat exchanger 11 distance R8
The penetrating portion has a structure in which the bellows 15 prevents leakage between the upper plenum 9 and the lower plenum 100 and allows thermal expansion of the intermediate heat exchanger 11 and the like to escape.

A circulation pump 16 is supported on the roof slab 4 and its intake 17 opens into the lower plenum 10 . A discharge port 18 of the circulation pump 16 is connected to the high pressure plenum 7 via a discharge pipe 19.

A normal operation motor (not shown) and an auxiliary motor (not shown) are connected to the circulation pump 16, and these are selectively operated. Also, roof slab 4
An upper core mechanism 20 that accommodates control rod guide tubes, instrumentation ferns, etc. (not shown) is supported in the upper plenum 9. An annular space 21 is provided on the inner surface of the reactor vessel 1 in the upper plenum 9.
A furnace wall cooling liner 22 is provided so as to form a furnace wall cooling liner 22, and the upper part thereof is open to the upper part of the upper plenum 9. The lower part of the annular space 21 is connected to the high pressure plenum 7 via a conduit 4.

The coolant 2 in the lower plenum 10 flows into the circulation pump 16 from the suction port 17 of the circulation pump 16, is pressurized, and flows into the high pressure plenum 7 through the discharge port 18 and the discharge pipe 19. Most of the coolant that has flowed in flows into the reactor core 5, where it receives heat and rises in temperature.The coolant that has passed through the core 5 flows into the upper plenum 9, and is transferred to the intermediate heat exchanger 11.
Heat flows from the primary system inlet hole 12 to the primary side of the intermediate heat exchanger 11.Here, heat moves from the primary side to the secondary side, and the cooled primary side coolant flows through the primary system outlet hole 13 to the lower plenum. flows into Io. The primary coolant circulates in the same manner thereafter.

On the other hand, part of the coolant that has flowed into the high pressure plenum 7 is transferred to the conduit 2.
3 into the annular space 21 and the furnace wall cooling liner 22
It overflows into the upper plenum 9 from the upper opening. The flow in this annular space 21 is for suppressing an increase in the temperature of the inner wall of the reactor vessel 1.

The secondary coolant that has received heat in the intermediate heat exchanger 11 is sent to the steam generator through the secondary cooling system 14, where it releases heat and returns to the intermediate heat exchanger 11 again.

[Problems in the background art] In the fast breeder reactor described above, when the reactor trips, the circulation pump 4' is switched from the normal operation motor to the auxiliary motor, and the flow rate of the circulation pump 'w is significantly reduced.
At this time, since the amount of heat generated in the core 5 is small, there is no problem in cooling the core 5, but the flow rate flowing into the annular space 21 from the high pressure plenum 7 through the conduit 23 becomes very small, so the inside of the annular space 21 is There is a possibility that the flow of the coolant becomes uneven, and the inner wall of the reactor vessel 1 rises abnormally. Also,
Temperature layer separation occurs within the upper plenum 9 due to the low flow rate of coolant flowing into the upper plenum 9 from the annular space 21;
Excessive thermal stress can occur in the furnace wall cooling liner 22. In addition, if the conduit 23 is made thicker as a countermeasure for the above problem, more coolant than necessary will flow into the annular space 2 during normal operation, and the power of the circulation pump 16 will be wasted.

[Purpose of the invention]

The present invention was made in view of the above problems, and an object of the present invention is to secure the flow rate of coolant necessary for cooling the furnace wall when the flow rate of the circulation pump is low, and thereby to ensure the integrity of the furnace wall. do.

[Summary of the invention]

The present invention provides high pressure in the reactor vessel, the roof slab provided to close the upper part of the reactor vessel, the reactor core provided in the reactor vessel, and the inlet portion of the coolant that supports the reactor core and flows into the reactor core. A core support mechanism that forms a plenum, an intermediate heat exchanger and a circulation pump provided in the reactor vessel, and a partition wall that partitions the reactor vessel into an upper plenum and a lower plenum;
A discharge pipe that connects the discharge port of the circulation pump and the high-pressure plenum, a reactor wall cooling liner provided along the inner surface of the reactor vessel, and a conduit that connects the discharge pipe or the high-pressure plenum with the reactor wall cooling liner 2. A variable flow resistor is installed in the middle of the conduit in a fast breeder reactor equipped with It is something.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.

In the figure, reference numeral 1 denotes a reactor vessel, in which a coolant 2 such as liquid metal sodium is accommodated. Reactor vessel 1
The roof slab 4 is open at the top and a roof slab 4 is provided to close the opening 3. A reactor core 5 is installed within the reactor vessel 1 and is comprised of a plurality of fuel assemblies (not shown), control rods (not shown), and the like. This core 5 is supported at the bottom of the reactor vessel 1 by a core support mechanism 6 . The core support mechanism 6 also forms a high-pressure plenum 7 as a coolant inlet to the core 5 . A partition wall 8 is provided between the core support mechanism 6 and the inner periphery of the reactor vessel l, and partitions an upper plenum 9 above the partition wall 8 and a lower plenum 10 below. An intermediate heat exchanger 11 is supported on the roof slab 4, and the primary system inlet hole 12 of the intermediate heat exchanger 11 is below the liquid level in the upper plenum 9, and the primary system outlet hole 13 is opened in the lower plenum JOK. There is. Further, the secondary cooling system 14 of the intermediate heat exchanger 1 is connected to the steam generator (
(not shown). The penetrating portion of the partition wall 8 of the intermediate heat exchanger 11 has a structure in which a bellows 15 prevents leakage between the upper plenum 9 and the lower plenum 10, and releases heat from the intermediate heat exchanger 11 and the like. The circulation pump 16 is supported by the roof slab 4 and its suction port 17
opens into the lower plenum 10. Circulation pump 16
The discharge port 18 is connected to the high pressure plenum 7 via a discharge pipe 19. A normal operation motor (not shown) and an auxiliary motor (not shown) are connected to the circulation valve 16, and these are selectively operated. Also,
The roof slab 4 supports an upper core mechanism 2o that accommodates a control rod guide pipe, an instrumentation well, etc. (not shown).

An annular space 21 is provided on the inner surface of the reactor vessel 1 in the upper plenum 9.
A furnace wall cooling liner 22 is provided so as to form a furnace wall cooling liner 22, and the upper part thereof is open to the upper part of the upper plenum 9. Further, an upper plenum 8 and a liquid level 40 are provided above the furnace wall cooling liner 22.
A nozzle 40 is provided toward the vicinity. Further, the lower part of the furnace wall cooling liner 22 is connected to the discharge pipe 19 via a conduit 41. The conduit 41 has a variable flow resistor 42, and is structured so that when the flow toward the annular space 21 is large, the iK has a large flow resistance, and conversely, when this flow is small, the flow resistance is small. This variable flow resistor 4
2 will be described later.

The coolant 2 in the lower plenum 10 flows into the circulation pump 16 from the suction port 17 of the circulation pump 16, is pressurized, and flows into the high-pressure plenum 7 through the discharge port 18 and the discharge pipe 19 to the high-pressure plenum 7. Most of the coolant that has flowed into the reactor core 5, where it receives heat and rises in temperature.
It flows into the primary side of the intermediate heat exchanger 11 through the primary system inlet hole 12 . Here, heat moves from the primary side to the secondary side, and the cooled primary side coolant flows into the lower plenum 10 through the primary system outlet hole 13. The primary coolant circulates in the same manner thereafter. On the other hand, a portion of the coolant that has flowed in through the conduit 41 and the variable flow resistor 42 flows into the annular space 21 . The coolant that has entered the annular space 21 flows into the upper plenum 8 through the nozzle 40 . The secondary coolant that has received heat in the intermediate heat exchanger 11 is sent to the steam generator through the secondary cooling system 14, where it releases heat and returns to the intermediate heat exchanger 11.
Return to

By the way, in this embodiment, when a nuclear reactor trip occurs, the circulation pump 16 is switched from the normal operation motor to the auxiliary motor, and the flow rate of the circulation pump 16 is significantly reduced. At this time, the flow rate of the coolant flowing into the annular space 2 through the conduit 41 also decreases, but since the flow resistance of the variable flow resistor 42 becomes small, the amount of decrease in the flow rate is small. Therefore, in this case as well, the flow velocity in the annular space 21 does not decrease excessively, and an excessive rise in the temperature of the inner wall of the reactor vessel 1 can be prevented.

Further, since the flow passing through the annular space 2 flows into the upper part of the upper plenum 9 through the nozzle 4Q, temperature stratification within the upper plenum 9 is alleviated. Also, this nozzle 4
The position where the low-temperature coolant flowing in from 0 and the high-temperature coolant in the upper plenum 9 mix is located away from the furnace wall cooling liner 22 due to the presence of the nozzle 40, so that the furnace wall cooling liner 22 is prevented from thermal fatigue. can be prevented from being affected.

FIG. 2 shows the variable flow resistor 42 used in the above embodiment.
Here is an example. That is, a container 50 is connected in the middle of the vertical conduit 41, and the interior of the container 50 is vertically divided into three spaces by a first partition plate 51 and a second partition plate 52 above it. There is. A cylinder 53 with a vertical axis is located at the center of the upper part of the first partition plate 51, and there is a gap l! between it and the lower surface of the second partition plate 52. 1i54. A ball 55 having an outer diameter slightly smaller than the inner diameter of the cylinder 53 is disposed within the cylinder 53 so as to be movable within the cylinder 53.
Ru. A first hole 56 having a diameter smaller than the diameter of the ball 55 is bored inside the cylinder 53 of the first partition plate 51, and a second hole 57 is formed outside the cylinder 53 of the first partition plate 51. is drilled. A third hole 58 having a diameter smaller than the diameter of the ball 55 is bored above the cylinder 53 of the second partition plate 52, and a fourth hole 58 is formed outside the cylinder 53 of the second partition plate 52. A hole 59 is bored. The passage area of the fourth hole 59 is smaller than the passage area of the second hole 57.

When the circulation pump 16 is in normal operation, the conduit 41
The pressure on the upstream side of the variable flow resistor 42 is high, and the conduit 41
At this time, the ball 55 is pushed up by the flow and closes the third hole 58, as shown by the solid line in FIG. Therefore, all the crossings of the conduit 4 are through the fourth hole 5.
Since the flow path area of the fourth hole 59 is small, the flow resistance becomes large. At this time, the first hole 56 is open, but since the gap between the ball 55 and the cylinder 53 is small, the flow rate is small.

On the other hand, assuming that the circulation pump 15 is not driven by the auxiliary motor during a reactor trip, etc., in this case,
The pressure upstream of the variable flow resistor 42 of the conduit 41 is not very high, and the flow rate of the conduit 41 is small. At this time, as shown by the two-dot chain line in FIG. 2, the ball 55 moves downward under its own weight, and the third hole 58 becomes open. At this time, the first hole 56 is closed, but even when the ball 55 is above as described above, the flow passing through the first hole 56 is not large, so this effect is small. Therefore, in this case, this variable flow resistor 42
flow resistance becomes smaller.

As described above, with the structure shown in FIG. 2, when the upward flow of the conduit 41 is large, the flow resistance is large;
Conversely, when this flow is small, a variable flow resistor 42 with low flow resistance can be obtained.

In the above embodiment, the inlet of the conduit 410 is provided in the middle of the discharge pipe 19, but it is clear that even if the inlet of the conduit 41 is provided in the high-pressure punnum 7, a flow will occur in the conduit 41 and the same effect will be obtained.・In addition, the structure of the variable flow resistor 42 does not necessarily have to be as shown in FIG.
Any material that provides low flow resistance when the flow rate is low may be used.

Furthermore, the shape of the flow path from the annular space 21 to the upper plenum 9 does not necessarily have to be the nozzle 4o, but may have a shape that overflows from the weir as shown in FIG. The effect of ensuring the required flow rate of the coolant flowing through the annular space 21 can be obtained.

〔Effect of the invention〕

According to the present invention, even when the circulation pump is operated at a low flow rate during a reactor trip, etc., it is possible to ensure the flow rate of coolant necessary for cooling the reactor wall, and to ensure the integrity of the reactor wall. Moreover, during normal operation, it is possible to eliminate waste caused by flowing more coolant than necessary for cooling the furnace wall.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of a fast breeder reactor according to the present invention;
FIG. 2 is a longitudinal sectional view of an embodiment of the variable flow resistor used in the present invention, and FIG. 3 is a longitudinal sectional view of a fast breeder reactor according to the prior art. 1... Reactor vessel, 2... Coolant, 3... Opening,
4... Roof slab, 5... Core, 6... Core support mechanism, 7... High pressure plenum, 8... Partition wall, 9...
・Upper plenum, 10...Lower plenum, 11...
Intermediate heat exchanger, 12... Primary system inlet hole, 13... Primary system outlet hole, 14... Secondary cooling system, 15... Bellows, 16... Circulation pump, 17... Suction Mouth, 18.
...Discharge port, 19...Discharge pipe, 20... Core upper mechanism, 21... Annular space, 22... Reactor wall cooling liner,
40... Nozzle, 41... Conduit, 42...° Variable flow resistor, 50... Container, 5 No.... First partition plate, 5
2...Second partition plate, 53...Cylinder, 55...Sphere. Agent: Patent attorney Noriyuki Chika (and 1 other person) Figure 2 Figure 3

Claims (3)

[Claims] (1) A reactor vessel that accommodates coolant and has an opening at the top, a roof slab installed to close the opening, a reactor core installed in the reactor vessel, and a core that supports the reactor and connects it to the core. a core support mechanism that forms a high-pressure plenum at the inlet of the inflowing coolant; an intermediate heat exchanger that is provided in the reactor vessel and has a primary system inlet hole and a primary system outlet hole in the upper and lower parts, respectively; a partition wall that divides the space within the reactor vessel between a system inlet hole and a primary system outlet hole into an upper upper plenum and a lower lower plenum; a circulation pump having a suction port in the lower plenum; and the circulation pump. and a reactor wall cooling liner that is arranged to form an annular space along the inner surface of the reactor vessel and has an opening between it and the upper plenum;
In a fast breeder reactor equipped with the discharge pipe or a conduit connecting the high-pressure plenum and the lower part of the reactor wall cooling liner, there is a portion in the middle of the conduit that has a small flow resistance when the flow toward the cooling liner is small. A fast breeder reactor characterized by being equipped with a variable flow resistor. (2) A reactor vessel that accommodates coolant and has an opening at the top, a roof slab installed to close the opening, a reactor core installed in the reactor vessel, and a reactor core that supports the reactor and connects it to the core. a core support mechanism that forms a high-pressure plenum at the inlet of the inflowing coolant; an intermediate heat exchanger that is provided in the reactor vessel and has a primary system inlet hole and a primary system outlet hole in the upper and lower parts, respectively; a partition wall that divides the space within the reactor vessel between a system inlet hole and a primary system outlet hole into an upper upper plenum and a lower lower plenum; a circulation pump having a suction port in the lower plenum; and the circulation pump. a discharge pipe that communicates the discharge port of the reactor with the high-pressure plenum, a reactor wall cooling liner that is arranged with a gap along the inner surface of the reactor vessel and has an opening between it and the upper plenum, and the discharge pipe. or a fast breeder reactor comprising a conduit connecting the high pressure plenum and the lower part of the reactor wall cooling liner, at least a part of the opening between the upper plenum and the reactor wall cooling liner is connected from the reactor wall cooling liner to the upper plenum. A fast breeder reactor characterized by an inward nozzle. (3) A variable flow resistor is disposed in the middle of the conduit so as to reduce the flow resistance when the flow toward the cooling liner is small. Fast breeder reactor.