JPS6355680B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle with a core spray sparge opening in a boiling water nuclear reactor emergency core cooling water system.

First, a core arrangement of a nuclear reactor and a conventional core spray sparge opening nozzle will be explained based on FIGS. 1, 2, and 3.

Figure 1 shows a boiling water reactor, including a reactor pressure vessel 1, internal structure 2, shroud 3, shroud head 4, steam separator 5, steam dryer 6, control rods 7, fuel elements 8, and reactor core. It is equipped with a spray pipe 9 and a core spray spargeer 10.

Next, FIG. 2 shows how the core spray sparge header 11 and the nozzle with an opening 15 are attached, and an inlet orifice 12, an inlet elbow 13, and an outlet orifice 14 are provided between the two members.

Furthermore, FIG. 3 shows a nozzle 15 with an opening, and the nozzle 15 with an opening includes an outlet elbow 16, a pipe 17, and a deflector 18. The outlet elbow 16 and the pipe 17 are connected by welding. The deflector 18 is composed of a bar 19 and a ring 20, and one end of the bar 19 is connected to the outlet elbow 16 at a welded portion 20.
The bar 19 and the ring 20 are screwed together through the threaded engagement part 22, and the other end is formed with a male thread, and the other ring 20 is threaded. After adjustment and confirmation of the L dimension, the end of the bar 19 and the inside of the ring 20 are welded and fixed via the welded portion 23.
There are two types of combinations of dimension L and dimension A in FIG. This is an extremely important point in order to obtain an appropriate spray distribution to the core when the core cooling system (hereinafter referred to as ECCS) is operating. This nozzle 15 with an opening is
130 units are used in 1100MW class nuclear reactors.

Although the deflector 18 of the opening nozzle 15 of the conventional core spray spargeer 10 is constructed as described above, it has the following problems. That is, the bar 19 and the ring 20 are connected to the threaded engagement part 22.
And because they are connected by welding part 23 welded from one side, the atmosphere inside the reactor during reactor operation, thermal fatigue during ECCS operation (due to a sudden change in temperature due to cold water injection into the reactor temperature of 302°C), and vibration. There is a high possibility that cracks will occur in the weld heat affected zone (hereinafter referred to as HAZ).

There is a high possibility that crevice corrosion will occur in the screw engagement portion 22.

As the aforementioned HAZ cracks and crevice corrosion develop, there is a possibility that the connection between the bar 19 and the ring 20 will break and the ring 20 will fall into the reactor core. , entering between the fuel elements 8 or the drive passage of the control rod 7, interfering with the function of the control rod 7, and even causing damage to the fuel element 8.
Ultimately, there is a high possibility that the reactor will have no choice but to shut down.

An object of the present invention is to provide a nozzle with a core spray sparge opening that can eliminate cracking from the HAZ, crevice corrosion in the threaded joint, and accidents of rings falling off from the bar, in order to eliminate the drawbacks of the prior art. There is a particular thing.

The feature of the present invention is that cooling water is spouted from the core spray sparge header located on the circumference along the inner wall of the upper shell of the shroud of the internal structure of the boiling water nuclear reactor and supplied through the pipe fittings from the upper and lower two stages of the core spray sparge header. In many orifice nozzles, the deflector of each orifice nozzle is comprised of an integral bar and ring made of a single material, and this configuration prevents cracking from the HAZ and thread engagement. The present invention provides a nozzle with a core spray sparge opening that has no concerns about crevice corrosion or rings falling off from the bar.

The present invention will be explained below based on the drawings.

4 and 5 show embodiments of the present invention, and the present invention is characterized by the deflector 25. FIG.

That is, the deflector 25 includes a bar 26 and a ring 27, which are formed by cutting or the like from a single material 24, as shown by phantom lines in FIG. Therefore, the bar 26 and the ring 27 are integrally constructed.

This deflector 25 used in the above-mentioned 1100 MW class nuclear reactor is formed in two types with different A dimensions, and 65 pieces of each type are manufactured.

Further, as shown in FIG. 5, the deflector 25 is attached to the center line of the pipe 17 by fixing a bar 26 to the outlet elbow 16 via a weld 28 while adjusting the L dimension.

The nozzle 15 with an opening configured as described above receives cooling water supplied from the core spray sparge header through an inlet orifice, an inlet elbow, an outlet orifice, etc., through an outlet elbow 16 and a pipe 17 to the opening of the pipe 17 and a deflector 25. It is designed so that it can be ejected from a spout formed by.

Since the bar 26 and ring 27 of this deflector 25 are integrally constructed, the ring 27 will not fall off from the bar 26 during use, and there will be no screw engagement or welding between the bar 26 and the ring 27. There is no problem of cracking from the HAZ or crevice corrosion from the screw engagement area.

The present invention has the configuration and operation described above, and has the following effects. That is, since there is no weld in the fixing part of the bar tip and the inner diameter part of the ring in the conventional deflector, cracking from the HAZ can be prevented.

Since there is no screw engagement part between the tip of the bar and the inner diameter of the ring in conventional deflectors, crevice corrosion can be prevented.

By being able to prevent cracks and crevice corrosion from the HAZ, it is possible to eliminate rings from falling into the reactor core, thereby preventing fuel element damage and control rod functional disturbances caused by rings falling. This makes it possible to completely eliminate nuclear reactors and improve the safety of nuclear reactors.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of a boiling water reactor, Figure 2 is a partially enlarged sectional view of the part in Figure 1, and Figure 3 is a longitudinal sectional view of a boiling water reactor.
FIG. 4 is a front view of a deflector portion according to the present invention, and FIG. 5 is a longitudinal cross-sectional view of a nozzle with an opening according to the present invention. 15... Nozzle with opening, 16... Exit elbow of nozzle with opening, 17... Same pipe, 25...
Same deflector, 24...Deflector material, 26
...Same bar, 27...Same ring, 28...Welded part between exit elbow and bar.

Claims (1)

[Claims] 1 Boiling water reactor internal structure shroud Numerous openings located on the circumference along the inner wall of the upper shell and through which cooling water is spouted from the upper and lower two stages of core spray sparge headers supplied through pipe fittings. 1. A core spray sparge nozzle with openings, characterized in that the deflector of each nozzle with openings is composed of a bar and ring of integral structure formed from a single material.