JPS60107596A - Boiling-water type 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] This invention relates to a boiling water nuclear reactor equipped with an intra-reactor circulation pump attached to a reactor pressure vessel.

[Technical background of the invention and its problems]

A conventional boiling water reactor is equipped with several to ten or more jet pumps 2 in a reactor pressure vessel 1, as shown in FIG.
This jet pump 2 is operated by driving water from a recirculation ponder 3 to circulate reactor water.

However, a boiling water reactor equipped with jet pump 2
Since the recirculation pump 3 was installed outside the reactor pressure vessel 1, there was a problem in that the structure of the piping etc. was complicated.

For this reason, boiling water reactors have been developed in which an in-reactor circulation pump as a circulation pump is directly attached to the reactor pressure vessel. As shown in FIGS. 2 and 3, this boiling water reactor houses a cylindrical core shroud 12 that supports a reactor core 11 in a reactor pressure vessel 10. A plurality of in-reactor circulation pumps 14 are installed in an annular passage 13 formed between the peripheral wall and the annular passage 13.
A pump section 14a is installed. A motor section (not shown) of the reactor circulation pump 14 is provided so as to protrude downward from the bottom of the reactor pressure vessel 10.

By the way, reactor water in the reactor pressure vessel 10 is sent to the lower core 17 from the annular passage 13 through the reactor water flow port 16 by the operation of the reactor circulation pump 14 . This reactor water reversely rises from the lower part of the reactor core and passes through the inside of the reactor core 11.

While the reactor water passes through the reactor core, it is heated and becomes a gas-liquid two-phase flow, and this gas-liquid two-phase flow is separated into water and steam by a steam separator (not shown). After the separated steam passes through a steam dryer and becomes dry steam, it is sent to a steam turbine to drive the steam turbine. Further, the separated reactor water is guided to an annular passage 13 and circulated to the lower part of the reactor core by the operation of an intra-reactor circulation pump 14.

Incidentally, the annular passage 13 is separated from the core lower part 17 by a partition wall 18 serving as a partition wall, and a pump portion 14a of the in-reactor circulation pump 14 is provided so as to penetrate this partition wall. The diameter of this pump part 14a is larger than the diameter of the jet pump 2, and therefore the passage width of the annular passage 13 that accommodates the intra-reactor circulation pump 14 is larger than the passage width in which the jet pump 2 is installed. The cross-sectional area of is also large.

On the other hand, the number of in-reactor circulation pumps 14 installed is smaller than the number of jet pumps 2 installed, and the number of in-reactor circulation pumps 14 is smaller than the number of jet pumps 2 installed.
4 has a wide installation interval. Therefore, the flow rate of reactor water handled by one in-reactor circulation pump 14 is large, and the reactor water flowing through the annular passage [3] is
When being sucked into a, the flow is rapidly contracted and the flow velocity increases.

In addition, if a specific reactor circulation pump 14 breaks down,
It is expected that the reactor water in that area will flow back along the bulkhead 18 to the adjacent reactor circulation pump 14, creating a vortex. Due to the generation of this vortex, the reactor water flowing through this area becomes turbulent, and
There was a risk that the efficiency of the circulation pump in the reactor would decrease and cavitation would occur due to the generated swirling flow, causing damage to pump equipment.

[Purpose of the invention]

The present invention takes the above points into consideration and provides a boiling water nuclear reactor that effectively prevents the occurrence of cavitation due to swirling flow and prevents a decrease in pump efficiency and damage to pump equipment. The purpose is to

[Summary of the invention]

In order to achieve the above-mentioned object, a boiling water nuclear reactor according to the present invention accommodates a core shroud in a reactor pressure vessel, and forms an annular passage between the core shroud and the reactor pressure vessel. , in which the pump parts of a plurality of reactor circulation pumps are attached to the partition wall provided at the lower part of this annular passage, the lower part of the inner annular space is installed in the annular space between each pump part of the above-mentioned reactor circulation pump. Partition plates are installed radially to divide the area.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the boiling water reactor according to the present invention will be described with reference to the accompanying drawings.

In FIG. 4, the reference numeral "addition" indicates a reactor pressure vessel of a boiling water reactor, and a cylindrical core shroud 21 is housed concentrically within this reactor pressure vessel. Core shrou P2
1 is installed upright at the bottom of the reactor pressure vessel, while the inside of the reactor core, in which a large number of fuel assemblies are mounted, is constructed within the shroud 421. A steam-water separator B is installed above the core n, and the steam-water separator B separates the gas-liquid two-phase flow flowing out from the core n into steam and water. Among these, the steam is guided to the main steam nozzle 6 through a steam dryer installed above the steam separator B, and is sent to a steam turbine (not shown) via a main steam pipe (not shown). It has become.

On the other hand, a control rod drive mechanism n for moving control rods in and out of the reactor core is provided below within the reactor core.

The operation of the control rod drive mechanism 27 causes the control rods to be moved in and out of the red reactor core B, thereby controlling the operation of the nuclear reactor.

Further, an annular passage 4 called a downcomer is formed between the reactor pressure vessel and the core shroud 21, and the lower part of this annular passage is partitioned off by an annular partition wall 29 serving as a partition wall. The partition wall 4 integrally connects the lower part of the core shroud 21 and the inner circumferential wall near the bottom of the reactor core. A pump section 31 for supplying a circulation pump within the nuclear reactor is provided on the partition wall 4 that partitions the annular passageway. Multiple reactor circulation pumps are installed along the inner peripheral wall of the reactor pressure vessel.

The reactor circulation pump includes a pump section 31 located within the reactor pressure vessel and a motor section 3 that drives this pump section.
The motor section 32 is installed protruding from the reactor pressure vessel.The rotational driving force from the motor section 32 is transmitted to the pump section 31 via a pump shirt 33. As shown in FIGS. 5 and 6, the pump section 31 has a cylindrical diffuser mark that covers the impeller and the impeller mounted on the pump shaft, and the diffuser 36 extends through the partition wall 4. It will be installed.

Reactor water flow openings are formed in the lower end circumferential wall portion of the core shroud 21, which corresponds to the position immediately below the pump portion 31 of the reactor circulation pump (9). The portion between the reactor water flow openings is formed thickly and constitutes leg portions 39, and the core shroud 21 is supported by these leg portions 39.
It supports the load of the reactor core.

Thus, the reactor water discharged downward from the pump section 31 of the intra-reactor circulation pump 30 is guided to the lower core 40 through the reactor water distribution line.

Further, the pump parts 31 of the reactor circulation pump are installed along the inner circumferential wall of the reactor pressure vessel at appropriate intervals in the circumferential direction. A rectangular partition plate 42 is provided between each of the pump parts 31 and 31 to divide the annular passage row into several to ten-odd parts in the circumferential direction.
is interposed. The partition plate 42 is arranged radially at the lower part of the annular passage, and the lower part thereof is fixed on the annular partition circle.

One end of the partition plate 42 is connected to the outer peripheral wall of the core shroud 21,
The opposite side ends are respectively fixed to the inner circumferential wall of the reactor pressure vessel.

In addition, in FIG. 4, reference numeral 44 is an annular water supply sparger, and water in a condenser (not shown) is supplied to this water supply sparger 44 through a water supply pipe 45. The water supplied to the reactor is spouted into the reactor pressure vessel Ginpaku from here.

Next, the operation of the boiling water m nuclear reactor according to the present invention will be explained.

The reactor water in the reactor pressure vessel is mixed with the feed water supplied from the feed water sparger 44 and guided to the annular passageway, where the okara is pumped by the reactor circulation pump and flows into the lower core 40. Sent.

The reactor water guided to the lower part of the reactor core 40 is turned around and sent to the reactor core, and while passing through the reactor core, it is heated and boiled, becoming a gas-liquid two-phase flow. The gas-liquid two-phase flow is separated into steam and water by a steam-water separator n above the core n.

The steam separated in the steam separator n is dried in a separate steam dryer to become dry steam, and this steam is sent from the main steam nozzle 5 to the steam turbine via the main steam pipe (not shown), and the steam turbine is drive. Steam expanded by driving the steam turbine is sent to a condenser (not shown) where it is condensed and becomes condensed water. This condensate is heat-treated on the way and is sent from the water supply pipe 45 to the water supply sparger 44, and from this water supply sparger 44 is supplied to the reactor pressure vessel Ginpaku.

On the other hand, the water separated by the steam-water separator is guided again to the annular passageway as a downcomer, and guided from the annular passageway to the lower core 40 by the pumping action of the reactor circulation pump (9). be done. In this way, the reactor water within the ribs of one reactor pressure vessel is internally circulated by the pumping action of the reactor circulation pump section.

In this way, the reactor water in the reactor pressure vessel Ginpaku flows down the annular passage, is discharged downward by the pumping action of the reactor circulation pump, and is guided to the lower core 40 through the reactor water flow opening. Ru. If the operation of a particular reactor circulation pump stops for some reason during this pivoting of the reactor circulation pump, a backflow may occur in the reactor water for that section, but this reactor water is Since it is guided smoothly and without disturbance to the adjacent pump section 31 along the surface of the plate 420, the flow becomes smooth and the generation of vortices is effectively prevented. Therefore, the occurrence of cavitation and the like can be effectively prevented, and a decrease in the efficiency of the pump for circulation inside the reactor can be prevented.

〔Effect of the invention〕

As described above, in the boiling water reactor according to the present invention, partition plates are provided radially in the annular space between the pump parts of the in-reactor circulation pump to divide the lower part of this annular space. The lower part of the space is divided into a plurality of parts along the circumferential direction, and the pump part of the intra-reactor circulation pump is housed in the divided space. Therefore, even if a particular reactor circulation pump stops for some reason, the reactor water flowing down in the annular passage is guided by the partition plate, and the reactor water in the stopped pump section is
Since the fluid is smoothly sucked into the adjacent pump section along the partition plate and beyond the partition plate, it is possible to effectively prevent the generation of vortices and the occurrence of cavitation and the like. Therefore, it is possible to effectively prevent a decrease in pump efficiency of the in-reactor circulation pump and damage to pump equipment.

[Brief explanation of the drawing]

Figure 2 is a perspective view of a part of a conventional boiling water reactor equipped with an internal circulation pump; Figure 3 is taken along line 1t-tn in Figure 2. 4 is a vertical sectional view showing one embodiment of the boiling water nuclear reactor according to the present invention, FIG. 5 is a plan sectional view taken along line v-V in FIG. 4, and FIG. Figure 3 shows a perspective view of the part shown in the figure; Ka...Reactor pressure vessel, 21...Reactor core 732911
Section: Core, Otsu: Steam-water separator, Sae: Steam dryer, n: Control rod drive mechanism, vane: Annular passage, 4:
...Bulkhead, processing...Reactor circulation pump, 3rd work...Pump section, Ah...Diffuser, Ah...Reactor water flow port,
40... Core lower part, 42-... Partition plate. Representative Patent Attorney Kensuke Chika (and 1 other person) No. 1
Figure 2 Figure 3 Figure 4 Figure 5 Figure 3 Figure 6

Claims (1)

[Claims] 1. A reactor core shroud is housed in a reactor pressure vessel, an annular reactor water passage is formed between the reactor core shroud and the reactor pressure vessel, and a reactor water passage is provided at the bottom of the annular passage. In a boiling water reactor in which the pump parts of a plurality of in-reactor circulation pumps are attached to a bulkhead, a partition plate is installed in a radial manner in the annular space between each pump part of the in-reactor circulation pump to divide the lower part of this annular space. A boiling water reactor characterized by being installed in 2. The partition plate has a rectangular shape, and its lower part is fixed to the partition wall, while one end of the partition plate is fixed to the outer circumferential wall of the core shroud, and the opposite side end is fixed to the inner circumferential wall of the reactor pressure vessel. A boiling water nuclear reactor according to claim 1.