JPS6082995A - core spray equipment - 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 core spray device that is one of the emergency core cooling devices for a nuclear reactor.

Technical background of the invention and its problems In general, a boiling water nuclear reactor is constructed as shown in FIG. That is, 1 is a reactor pressure vessel, and a reactor core shroud 2 is provided inside this pressure vessel 1, and a large number of fuel assemblies are loaded inside this core shroud 2 and control rods are accommodated therein. A reactor core 3 is constructed. The coolant (soft water) in the pressure vessel 1 is sent to the lower part of the pressure vessel 1 by the circulation device 5 together with the coolant supplied from the water supply sparger 4, and flows upward into the reactor core 3. The coolant is heated as it flows through the core 3, and is sent to a steam separator 7 via a shroud head 6 provided at the top of the core shroud 2, where it is separated into water and steam.

After moisture is removed from the separated steam in a steam dryer 8, it is led out of the pressure vessel 1 through a main steam nozzle 9, and is passed through a main steam pipe (not shown) to a turbine for driving a generator (not shown). (not shown).

In the figure, 10 is a control rod guide tube that guides control rods (not shown) into the reactor core 3 from below, and 11 is a control rod drive mechanism that drives the control rods up and down. The boiling water reactor described above is also provided with an emergency core cooling system that cools the reactor core 3 and restores the water level of the cold Nj material when a loss of coolant accident or the like occurs.

A core spray device, which is one of the emergency core cooling devices, is installed above the core 3.
b are its upper and lower sparns 17; These spanners 12a', 12b are provided with several types of spray nozzles, such as spray nozzles 14. 15 are arranged alternately in the circumferential direction toward the center of the core 3. However, each of the spray nozzles 14, 15 has opposite left and right hands. In the event of a loss of coolant accident, the core spray system (not shown) connects both spans 1'12a, 1 through the core spray piping 16 (see Figure 1).
2b is supplied with coolant, which is injected from spray nozzles 14 and 15 and spread over the upper surface of the reactor core 3 to maintain the reactor core 3 in a water-immersed state.

FIG. 3 shows one type of spray nozzle 14, which is made by joining two 90' elbows 17a and 17b at a predetermined angle and fitting an orifice 18a inside the joint. , the opening at the tip of one 1-rubo 17a becomes the injection port 19. The tip of the elbow, which becomes the injection port 19, has a threaded aperture structure as shown in the figure. The other elbow 17b is attached by welding to the arcuate tube 13a of the upper spurn 12a through an orifice 18b at an angle where the axis of the injection port 19 intersects the vertical centerline of the reactor core 3.

FIG. 4 shows the other type of spray nozzle 15, in which two 90' elbows 20a and 20b are joined at a predetermined angle, and an orifice 2 is formed inside the joint.
1a, a cylindrical guide 22 is joined to the outer edge of the distal end surface of one elbow 20a, and a support rod 23 is attached inside the elbow 20a so as to be located on the center line of the cylindrical guide 22. A small circular baffle plate 24 is attached to the tip of the support rod 23 so as to be located at the center of the opening end of the cylindrical guide 22.
5, and the coolant is diffused from the injection port 25 into a hollow conical cylinder shape. The other elbow 20b is attached to the arcuate tube 13a of the spanner 12a by welding via an orifice 211) at an angle such that the axial center line of the injection port 25 intersects the vertical center line of the reactor core 3. .

However, some of the spray nozzles of the core spray device configured as described above have the following problems. In other words, if a loss of coolant accident occurs, reactor pressure vessel 1
There is a steam atmosphere inside. When the coolant is sprayed into such a steam atmosphere from the spray nozzles 14, 15, heat exchange occurs between the coolant and the water vapor in the steam atmosphere, and the water vapor is violently condensed. Here, the spray water sprayed from the spray nozzle 14 formed as shown in FIG.
Because of the thread-shaped constriction part, the behavior of the spray water becomes complicated and unstable.

As a result, especially in a steam atmosphere, it becomes extremely sensitive to conditions such as atmospheric pressure, spray water flow rate, etc. due to the unstable flow of spray water and unpleasant steam condensation from the outside.
Even if the spray nozzles have the same shape, the distribution of spray water will vary, and the experimental results show that spray nozzles 14
The injection direction of the coolant that is more erected varies by about 5 to 15 degrees with respect to the axial center line of the injection port 19, making it impossible to obtain a stable and uniform spray flow rate distribution, which increases the cooling efficiency of the core 3. There was a risk that it would not be possible.

[Object of the Invention] An object of the present invention is to provide a core spray device that is capable of stabilizing the spray distribution characteristics in the upper part of the core and improving the core cooling efficiency by improving the spray nozzle.

[Summary of the Invention] A core spray device according to the present invention includes at least some of a plurality of spray nozzles attached to an arcuate tube,
The feature is that the constriction part attached to the tip of the elbow on the side of the injection port is completely eliminated, the flow path has a smooth structure, and the same end is configured to be called injection [1].

[Embodiment of the invention] Figures 5 to 8 show an embodiment of the present invention.
The core spray device 1'01 is installed on a shroud head 103 above the core shroud 102 as shown in FIGS. 5 and 6.
It is composed of an upper spanner 104 and a lower spanner 105 arranged along the inner circumferential surface of.

The core shroud is provided inside the reactor pressure vessel 106, and a large number of fuel assemblies 107 are installed inside the core shroud.
A reactor core 107 is configured by loading a.

The upper spanner 104 has semicircular arc-shaped tubes 108a and 108b arranged on the inner circumferential surface of the shroud head 103 so that they form a circle, and each arc-shaped tube 1
There are several types of spray nozzles 1 on the bottom side of 08a and 108b.
09.110 are attached alternately in the circumferential direction. However, any spray nozzle 109.
110 also have opposite left and right hand. Further, each of the arcuate tubes 108a and 108b is connected to a vertical pipe 111.
a and 111b to a common arc-shaped pipe 112, and this arc-shaped pipe 112 is connected to a core spray pipe 113 provided penetrating the reactor pressure vessel 106.

The lower spanner 105 includes arcuate tube bodies 114a and 114 arranged along the inner peripheral surface of the shroud head 103.
Several types of spray nozzles are installed on the upper surface side of the unit 109, for example, the spray nozzle 109.b. 110 are attached alternately in the circumferential direction.In addition, each arcuate tube 114a
, 114b are connected to a common arc-shaped pipe 116 via vertical pipes 115a and 115b, respectively, and this arc-shaped pipe 116 is connected to a core spray pipe 113 provided penetrating the reactor pressure vessel 106.

The one type of spray nozzle 109 has two 90' elbows 117a, as shown in FIG.

117b are joined at a predetermined angle, and an orifice 118a is fitted inside the joined part, and the end opening of one of the elbows 117a that becomes the injection side is made into an injection port 119 without an exit constriction part, and this injection The other elbow 117b is connected to the arcuate tubes 108a and 108b at an angle such that the axial center line of the mouth 119 intersects the vertical center line of the reactor core 107.
, 114a or 114J via an orifice 118b by welding.

The other type of spray nozzle 110, as shown in FIG.
At the same time, a cylindrical guide 123 is welded to the outer edge of one side of the tip of one elbow 121a, and a support rod 124 is installed inside the guide so as to be positioned on the center line of the cylindrical guide 123. A small circular baffle plate 125 is attached to the tip of this support rod 124 so as to be positioned at the center of the opening end of the cylindrical guide 123, and an annular injection port 126 is formed around this baffle plate 125. 41?, so that the cooling air is diffused from the injection port 126 into a hollow conical shape. It has been completed. Then, at an angle such that the axial center line of the injection port 126 intersects the vertical center line of the reactor core 107,
1b is attached to the arcuate tube 108a, 108b, 114a or 114b via an orifice 122b by welding.

The core spray device 101 configured as described above operates as follows. In other words, in the event of a loss of coolant accident, the core spray piping 113
Arc-shaped piping 112. in the reactor pressure vessel 106 via.
Cooling material is supplied to the vertical pipe 116, and this coolant is supplied to the vertical pipe 11.
1a, 11 lb.

Both upper and lower spanners 104 .
105 arcuate tube bodies 108a, 1081+, 114a,
114b. and the spray nozzle 109
, 110 onto the upper surface of the core 107.

According to the core spray device 101 configured as described above, the spray nozzle shown in FIG. 3 which has been conventionally used is not used, but the spray nozzle 109 shown in FIG. 7 is used instead. spray nozzle 109
The coolant injected from the spray nozzle has no constriction at the injection port 119 at the tip of the spray nozzle, and the flow path is smooth, so if the shape is the same, the flow is stable and the steam atmosphere is However, even if severe steam condensation occurs due to the influence of pressure and spray flow rate, there will be no difference in spray distribution between the spray nozzles, and the flow rate will be distributed evenly in the upper part of the core, the spray distribution characteristics will be uniform, and the cooling of the core 107 will be improved. Efficiency is increased. Note that since the other type of spray nozzle 110 is of a diffusion type, even if the spray direction deviates from the axis of the injection port 123 to some extent, this will hardly hinder the uniformity of the coolant.

[Effects of the Invention] As described above in detail, the core spray device of the present invention has a constriction portion at the elbow tip on the injection port side of at least some of the plurality of spray nozzles attached to the arcuate tube. The coolant injection is stabilized by making the passage completely smooth. Therefore, the coolant is distributed over the upper surface of the core with a uniform flow rate, resulting in improved cooling efficiency.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a boiling water reactor, Figure 2 is a vertical cross-sectional view of the shroud head, Figure 3 is a partially cutaway cross-sectional view of the spray nozzle, and Figure 4 is a different type of reactor. 5 and 6 are perspective views and vertical sectional views showing one embodiment of the core spray device according to the present invention, and FIG. 7 is a partially cutaway sectional view showing the spray nozzle of FIG. 8 is a partially cutaway sectional view of another type of spray nozzle used in the present invention. 101... Core spray device 103... Shroud head 107... Core 108a, 108b -... Arc-shaped tube bodies 114a, 11
4b ・,, Arc-shaped tube body 109, 110... Spray nozzle 113... Core spray piping 117, 117b ・90° construction fiv ho 118a, 11
8b... Orifice 119... Injection port The representative is Noriyuki Chika (IJ or one person) Figure 2 Figure 3 Figure 4 Figure 211-c Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] It comprises an arc-shaped tube connected to the core spray piping and arranged along the inner circumferential surface of the shroud head above the core, and a plurality of spray nozzles attached to the arc-shaped tube, and at least a portion of the A spray nozzle consists of two elbows connected to each other and an orifice fitted inside the joint of both elbows.The spray nozzle has a smooth flow path with no constriction at the tip of the spray nozzle. A reactor core spray device characterized by having a mouth formed therein.