JPH1184062A - Water-level instrumentation nozzle for atomic reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-level instrumentation nozzle for atomic reactor, where the attaching weld part can be inspected or repaired from outside of the barrel part of a reactor pressure vessel and, at the same time, which can evenly diffuse stresses in the weld. SOLUTION: In a water-level instrumentation nozzle attached to a through hole 22 formed in the barrel part 1 of a reactor pressure vessel for measuring the level of cooling water, a built-up welded seat 23 is formed along the fringe of the through hole formed through the external wall of the barrel part 1 and a nozzle body 24 having a beveled end section is brought into contact with and fixed to the seat 23 by performing penetration welding all around the contact part 25 of the nozzle body 24 with the fringe of the hole 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor water level instrumentation nozzle attached to a through hole formed in a body of a reactor pressure vessel for measuring the level of cooling water in a reactor pressure vessel.

[0002]

2. Description of the Related Art As shown in FIG.
The body 1 of the steel pressure vessel constituting the outer shell is filled with cooling water made of light water, and a core 3 made of a fuel assembly 2 for heating the cooling water, and heated in the core 3. A steam-water separator 4 for separating steam from the cooling water, and a steam dryer 5 for drying the steam separated by the steam-water separator 4
Are mainly stored, and the high-temperature and high-pressure steam generated here is supplied from a main steam nozzle 6 provided in the body 1 of the pressure vessel to a turbine (not shown) side to generate power. ing. In the figure, 7 is a supply nozzle for supplying light water into the pressure vessel, and 10 is an upper mirror.

[0003] In addition to the main steam nozzle 6 and the supply nozzle 7 described above, a water level sensor S for continuously measuring the level of the cooling water in the pressure vessel is provided on the body 1 of the pressure vessel. A plurality of instrumentation nozzles 8 are provided along the height direction. As shown in FIG. 3, the water level instrumentation nozzle 8 allows a nozzle body 11 composed of a small-diameter pipe to pass through a through hole 9 formed in the body 1 of the pressure vessel from the inner surface side of the pressure vessel. The end is formed by partial penetration welding from the inside of the body 1, and a part of the cooling water or steam in the pressure vessel is extracted and flows to the water level sensor S side. In the vicinity of the rear end portion of the outer peripheral portion of the nozzle body 11, a tapered portion 12 whose diameter is reduced toward the front is formed, and this tapered portion 12 corresponds to a tapered portion 14 formed on the inner peripheral surface of the through hole 9. The contact makes it possible to guide the mounting and to ensure the hermeticity of the water level instrumentation nozzle.

[0004]

In the meantime, this reactor pressure vessel is required to be periodically inspected during the service period, and one of the inspection objects is the above-mentioned welded portion of the body 1 or the like. Inspection of weld joints such as nozzles. The inspection of the welded portion is automatically performed by remote control using an automatic ultrasonic flaw detection robot using ultrasonic waves.

However, as described above, the water level instrumentation nozzle 8 has a poor weldability because the welded portion is located inside the body 1 in which the cooling water or the steam dryer 5 is accommodated. In order to perform the flaw detection inspection and inspection, the automatic ultrasonic flaw detection robot must be accurately moved while removing the upper mirror 10 and checking the position of the welded portion. This operation requires a lot of time and skill. Required. Moreover, when a defect is found by this inspection, it is not easy to repair the defect, and the operation requires much time and labor.

[0006] Also, since the welding was partial penetration welding,
In some cases, stress applied to the welding route was concentrated.

The present invention has been devised in order to effectively solve the above-mentioned problem, and has as its object to inspect the welding weld of the water level instrumentation nozzle from outside the body of the pressure vessel. An object of the present invention is to provide a reactor water level instrumentation nozzle capable of performing repair work and dispersing stress of a welded portion evenly.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a water level instrumentation nozzle attached to a through hole formed in a body of a reactor pressure vessel for measuring a water level of the water. In the above, a build-up seat is formed along the peripheral edge of the through hole formed on the outer periphery of the body portion, and a nozzle body whose end is chamfered to the build-up seat is brought into contact with the outside, and the contact is formed. The contact portion is attached and fixed by all-around penetration welding.

According to the above construction, the nozzle body can be welded from the outside of the body of the pressure vessel, so that inspection and repair work of the nozzle body mounting welded portion can be easily performed from the outside of the body of the pressure vessel. It is possible to reduce the work time and labor, and to disperse the stress of the welded portion evenly by adopting the all-around penetration welding.

[0010] It is preferable that the cladding seat is formed of Inconel or stainless steel, and the inner surface of the through hole is coated with a corrosion resistant material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a reactor water level instrumentation nozzle according to the present invention.

First, the configuration of a reactor water level instrumentation nozzle according to the present invention will be described. As shown in FIG. 1, a water level instrumentation nozzle 21 is provided with an overlay pad made of Inconel or stainless steel along a peripheral portion on the outer surface side of a through hole 22 formed so as to penetrate the body 1 of the pressure vessel. 23 is formed in a ring shape. The nozzle body 24 whose end is chamfered to the overlay 23 is contacted from the outside, and the contact portion 25
Is welded all around and the overlay 23 and the nozzle body 24 are fixed.

The inner peripheral surface 26 of the through hole 22 of the body 1
Is coated with a corrosion-resistant material 27 such as stainless steel to form a cladding layer 29. The cladding layer 2
Reference numeral 9 is formed on the entire inner surface of the body 1 of the pressure vessel to prevent corrosion of the body of the body.

At the tip of the water level instrumentation nozzle 21, a pipe 28
Are connected by welding, and a water level sensor S and the like are connected through the pipe 28.

Next, the operation of the reactor water level instrumentation nozzle having the above configuration will be described. As described above, the conventional body 1
The nozzle body that has been welded from the inside of the body 1 is attached and welded from the outside of the body 1, so that the welded portion is exposed on the outer surface of the body 1. For this reason, it is possible to perform the repair work as well as the automatic flaw detection inspection and inspection of the welded portion from the outside of the body 1 of the pressure vessel,
These operations are easily performed.

In addition, since the welding portion can be easily removed, it is easy to replace the nozzle member 24 with a different material.

[0018] Further, by making the welding all-around penetration welding,
The stress applied to the welding portion can be evenly distributed over the entire welding route portion, and the strength can be improved.

As another embodiment of the present invention, when the above-mentioned overlay 23 and nozzle body 24 are formed of carbon steel, the cladding layer 29 in the through hole 22 is not formed. Can also obtain the same effect as described above. In addition, according to the above configuration, it is not necessary to form the cladding layer 29, so that the number of man-hours during manufacturing can be reduced.

[0020]

In summary, according to the present invention, since the welded portion of the water level instrumentation nozzle 21 is located on the outer surface of the body 1, the mounting of the water level instrumentation nozzle is performed from outside the body of the pressure vessel. Inspection and repair work on welds can be performed easily,
The working time and labor can be reduced, and the excellent effect that the stress of the welded portion can be evenly dispersed by using the all-around penetration welding is exhibited.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a reactor water level instrumentation nozzle according to the present invention.

FIG. 2 is a sectional view showing a schematic structure of a reactor pressure vessel.

FIG. 3 is a sectional view showing a conventional reactor water level instrumentation nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body 21 Water level instrumentation nozzle 22 Through-hole 23 Overlay seat 24 Nozzle body 25 Contact part

Claims (2)

[Claims] 1. A water level instrumentation nozzle attached to a through hole formed in a body of a reactor pressure vessel for measuring a water level of cooling water in a reactor pressure vessel, wherein the through hole formed in an outer periphery of the body is provided. Forming a weld overlay along the peripheral edge of the nozzle, contacting the nozzle body whose end is chamfered to the weld overlay from the outside, and attaching and fixing the abutting portion by full circumference welding. Characteristic reactor water level instrumentation nozzle. 2. The cladding seat is formed of Inconel or stainless steel, and the inner surface of the through hole is
The reactor water level instrumentation nozzle according to claim 1, wherein the nozzle is coated with a corrosion resistant material.