JPS61114188A - 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) The present invention relates to a boiling water nuclear reactor, and particularly to a boiling water nuclear reactor in which a circulation pump is provided in a gap between an inner circumferential wall of a reactor pressure vessel and a shroud.

[Technical background of the invention]

In a boiling water reactor, a plurality of circulation pumps are installed in the annular gap formed by the shroud provided in the nuclear pressure vessel and the inner circumferential wall of the reactor pressure vessel, and the circulation pumps circulate coolant in the reactor. There is a system that forcibly sends water into the reactor core.

That is, FIG. 4 is a vertical cross-sectional view schematically showing a boiling water reactor in which a circulation pump is provided inside the reactor pressure vessel, and a shroud 2 is installed concentrically within the reactor pressure vessel 1. (), and a reactor core 3 is disposed within the shroud 2.

A steam/water separator 5 is disposed in the second part of the shroud head 4 formed at the top of the shroud 2, and further below the steam/water separator 5 is a steam/water #l vessel 5. Minute #
A steam dryer 6 for drying the steam is provided. In addition, a water supply sparger 7 is installed in the reactor pressure vessel 1 at a position slightly below the steam separator 5.
A main steam nozzle 8 is installed above it.

On the other hand, in the lower part of the annular gap 9 formed by the inner peripheral surface of the reactor pressure vessel 1 and the shroud 2, a plurality of circulation pumps 11 each driven by a motor 10 are installed.
is installed.

FIG. 5 is an enlarged longitudinal cross-sectional view of the mounting part of the circulation pump 11, and the lower end of the annular gap 9 formed by the inner circumferential surface of the reactor pressure vessel 1 and the shroud 2 is provided with the circulation pump 11. A diffuser 12 is attached, and a pump impeller 1/I is disposed below an outlet guide vane 13 formed on the diffuser 12. The pump shaft 15 to which this pump impeller 14 is attached extends downwardly through the bottom W of the reactor pressure vessel 1, and is inserted into a motor chamber 16 suspended from the bottom wall of the reactor pressure vessel 1. It is connected to an output shaft 10b that is integral with the rotor 10a of the motor 10 mounted thereon.

Therefore, along with the reactor water drain in the reactor pressure vessel 1 and the water supply supplied from the water supply spurt 7, the circulation pump 11
The reactor pressure vessel 1 is rotated by the rotation of the pump impeller 1/I.
The reactor core 3 is sent to the lower part of the reactor core 3 through a communication port upward. As it passes through the reactor core 3, the reactor water is heated and becomes a two-phase flow of water and steam, which flows through the shroud head 4 to 1111P of steam and moisture! 5, where it is divided into water and steam. The steam separated in the steam separator 5 has its moisture removed in a steam dryer 6, and is then sent from a main steam nozzle 8 to a turbine via a main steam pipe (not shown).

[Problems with background technology]

In such a nuclear reactor J3, the coolant sent out from the circulation pump 11 disposed below the annular gap 9 formed by the inner circumferential surface of the reactor pressure vessel 1 and the shroud 2 flows through the diffuser 12. The liquid is sent to the lower part of the reactor pressure vessel 1, and further flows into the reactor core 3 through a plurality of openings 18.18 (FIG. 6) formed in the lower part of the shroud 2.

However, these openings 18 are not necessarily located at appropriate positions with respect to the flow of coolant sent from the circulation pump 11 due to constraints on the strength of the Kuco Loud 20. In other words, as shown in the cross section of the lower part of the reactor pressure vessel 1 in FIG. If the opening 18 is not located in the main flow of the flow toward the frontage 18, the shroud 2 and the lower part of the reactor pressure vessel 1, which are the connecting parts of the shroud 1 to leg 17, , which acts as a resistance to the cooling I flow. Then, the pressure loss in the flow path through which the coolant circulates increases, and the input energy to the motor 10 that drives the circulation pump 11 has to be increased accordingly. This had the disadvantage of reducing power generation efficiency.

[Purpose of the invention]

The present invention has been made in view of these points, and the shroud support leg 1 does not create resistance to the flow of coolant sent from the circulation pump. It is arranged along the coolant flow direction to reduce flow resistance and pressure loss in the coolant circulation channel, reduce the amount of input energy to the motor that drives the circulation pump, and reduce boiling water with high power generation efficiency. The purpose is to provide a type of nuclear reactor.

(Summary of the Invention) The boiling water reactor of the present invention includes a circulation pump provided in an annular gap between the inner circumferential wall of the reactor pressure vessel and the shroud, and the circulation pump circulates coolant in the reactor to the shroud. In a boiling water reactor in which the coolant flows into the reactor core through openings between a number of shroud support legs provided at the lower end and is circulated, the flow resistance of the coolant in the reactor is reduced to low i1i!t.
In order to increase the
41 The main feature is that the second Q is arranged in the direction of material flow.

(Embodiments of the Invention) Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

In this embodiment, as shown in FIGS. 1 to 3,
The shroud support leg 19 has a W-shaped cross section and is formed to be inclined along the coolant flow. Figure 1 shows the shroud rib 1-leg 1.
Fig. 9 shows a vertical cross section, Fig. 2 shows a cross section of the section, Fig. 3 shows a cross section of the
Figures (A) to (D) show its detailed shape.

To explain further, each shroud support leg 19 is provided between the lower end of the shroud 2 and the bottom surface of the reactor pressure vessel 1, and supports the shroud 2 downward. Therefore, the upper end surface 198 of the shroud 1J's boss 1 to leg 19 is formed into a long rectangular shape along the circumferential direction of the shroud 2, as shown by the chain line in FIG. 1 and <A> in FIG.

And the upper end surface 19a of the shroud 17 boat leg 19
The intermediate portion 19b extending from the lower end surface 19c is shown by the solid line in FIG. 1 and in FIGS. l', J: In order to reduce the flow resistance of the coolant, its cross section is gradually deformed to form an airfoil shape. and,
The shroud support leg 19 is connected to the coolant flow (arrows in FIGS. 1 and 2) delivered from the circulation pump 11.
In order to prevent large resistance from occurring, the intermediate portion 19b is inclined in a J direction along the cold direction 1n-U'a. In this embodiment, the coolant supplied from the circulation pump 11 flows in the direction of the reactor core 3 along the bottom inner peripheral wall of the reactor pressure vessel 1, and as shown in FIG. pump 1
C) I 1 connecting the center of 1 and the center of reactor pressure vessel 1
It is symmetrical with respect to the IFi plane. Since the shroud support leg 19 is provided at a symmetrical position with respect to its radial cross section, its intermediate portion 19b is gradually twisted in the coolant flow direction, as shown in FIGS. 1 to 3. Go,
On the lower end surface 19c, it is twisted to a twist angle of θ-θ0 so as to be parallel to the cold N1 direction.

That is, the intermediate portion 19b of the shroud support leg 19
The torsion angle θ of J: sea urchin shown in Fig. 3 (C) and (D) is
In the upper part, it is small as 0=θ1×θ0, and in the lower part, it is θ−Oo. The shroud support legs 19 located symmetrically with the radial cross section are formed symmetrically with their respective twist angles in opposite directions.

Next, the operation of this embodiment will be explained.

When the circulation pump 11 is operated by the motor 10, the coolant in the annular gap 9 between the reactor pressure vessel 1 and the shroud 2 is sucked by the circulation pump 11, passes through the diffuser 12 and the outlet guide vane 13, and flows into the reactor. It flows out towards the bottom of the pressure vessel 1. The coolant discharged from the circulation pump 11 flows into the core 3 as shown by the arrow in FIG.
flowing towards the part. At this time, each shiko loud support leg 1
9 is formed in the shape of an airfoil in cross section and is provided along the coolant flow direction, so that flow resistance to the coolant flow is extremely small, and pressure loss is also reduced. Therefore, the coolant flows well into the lower part of the core 3 through the openings between each shroud 17 boat leg 19 and then up the core 3.

Flow II resistance to this coolant flow is extremely low compared to the conventional one, so if the motor 10 is driven by the input energy required to obtain the same level of coolant flow rate as the conventional one, By means of the circulation pump 11, the amount of coolant transported can be much greater than before.

Therefore, by using this embodiment, the power generation efficiency of the nuclear reactor can be increased.

〔Effect of the invention〕

In this way, the boiling water reactor of the present invention can reduce the flow resistance to the coolant flow from the circulation pump toward the reactor core, as well as reduce pressure loss. It is possible to reduce the amount of energy, obtain a large coolant flow gap, and increase the power generation efficiency of the nuclear reactor.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the boiling water nuclear reactor of the present invention. 3(A) is a plan view of the shroud support leg, FIG. 3(B) is a partially omitted front view of the shroud support leg, and FIG. 3(C) is the mc of the same figure (8). - A cross-sectional view along the mc line, the same figure (D) is llID-1f of the same figure (8)
A cross-sectional view taken along the fD line, Figure 4 is a vertical side view of a boiling water reactor, Figure 5 is an enlarged cross-sectional view of the circulation pump section of a conventional boiling water reactor, and Figure 6 is a conventional shroud support. FIG. 3 is a cross-sectional view showing the leg portion. 1...Reactor pressure vessel, 2...Shroud, 3...
・Reactor core, 9... Annular gap, 10... Motor, 11.
...Circulation pump, 19...Shroud support leg,
19a...Top end part, 19b...Middle part, 19c...
・Lower end. Applicant's agent Inomata Seizen 71 Figure Yan β Figure 3 Figure 4 Book 5 Figure

Claims (1)

[Claims] 1. A circulation pump is provided in an annular gap between the inner circumferential wall of the reactor pressure vessel and the shroud, and this circulation pump supplies coolant in the reactor to a large number of shrouds provided at the lower end of the shroud. In a boiling water reactor in which the coolant flows into the reactor core through openings between the support legs and circulates, each of the shroud support legs is formed into an airfoil shape in order to reduce the flow resistance of the coolant in the reactor. A boiling water nuclear reactor, characterized in that the reactor is arranged in a direction in which coolant flows from the circulation pump. 2. Each shroud support leg has an upper end connected to the lower end of the shroud that is long in the circumferential direction of the shroud, and a long rectangular shape extending from the upper end to the lower end connected to the bottom of the reactor pressure vessel. The boiling water nuclear reactor according to claim 1, wherein the portion is formed in an airfoil-shaped cross section that changes smoothly and is gradually twisted in a direction along the coolant flow. .