JPS60228995A - Nozzle for pressure vessel of nuclear 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 [Field of Application of the Invention] The present invention relates to a nozzle for a nuclear reactor pressure vessel, and is particularly suitable for preventing thermal fatigue of a nozzle for the purpose of injecting cold water. This invention relates to a nozzle for a nuclear reactor pressure vessel that can be inspected.

[Background of the invention]

Conventionally, as shown in Fig. 2, when cold water (minimum 10C) is injected into high-temperature reactor water (289G) into the water supply nozzle 2 of the reactor pressure vessel 1, a nozzle was used to protect the nozzle from thermal stress generated in the nozzle body. A thermal sleeve 3 is attached to the.

As shown in Figure 3, conventional thermal sleeves employ a method in which the thermal sleeve 3 is simply inserted into the nozzle 2, but with this method, the thermal sleeve 3 contracts during cold 7X injection, so the nozzle and A gap is created at the insertion part with the thermal sleeve, and cold water flows through this gap in the direction indicated by arrow A.
Leakage as shown in B and C, this is high 1 near nozzle corner D
There was a risk that high cycle temperature fluctuations would occur at the nozzle corners, which are subject to severe stress due to mixing with reactor water.

For the plug-in thermal sleeve, give a tightening margin of about 0.2 to 0.5 between the nozzle and the thermal sleeve.
Although methods to minimize the gap have been considered, this does not prevent the thermal sleeve from shrinking when cold water is injected, and cold water may leak.

The three-piece thermal sleeve is made of Inconel or stainless steel, but the nozzle 2 body side is made of carbon steel, so the metal on the nozzle side corrodes.

Deterioration over time due to erosion, etc. is considered, and the gap between the mounting parts gradually increases, which may increase the power of cold water leaks. There are also concerns that being exposed to it can lead to fatigue and the inability to maintain the shimejiro state.

Recently, in order to prevent these cold water leaks, a bath contact type thermal sleeve has been developed, in which a thermal sleeve 3 is fixed to the nozzle 2 at the bath contact part E, and a sparger 5 is fixed to the thermal sleeve 3 by welding, as shown in Fig. 4. has been adopted,
According to this method, leakage of cold water does not occur. but,
In the above-mentioned welding type thermal sleeve, since the sparger 5 cannot be pulled out due to its structure, it was not possible to inspect a part of the entire nozzle corner during the service period.

Therefore, it is necessary to develop a nozzle structure that is free from the risk of cold water leakage, is capable of preventing thermal fatigue of the reactor pressure vessel nozzle, and is also capable of inspecting the entire nozzle corner during the service period. It was wanted.

[Purpose of the invention]

An object of the present invention is to provide a highly safe nuclear reactor pressure vessel nozzle that prevents thermal fatigue of the reactor pressure vessel nozzle corners and the inner surface of the nozzle, and allows the nozzle to be easily inspected during its service life. There is a particular thing.

[Summary of the invention]

The present invention provides a nozzle for a nuclear reactor pressure vessel comprising a thermal sleeve provided inside the nozzle and a sparger communicated with the thermal sleeve, in which an outer thermal sleeve is provided between the thermal sleeve and the nozzle body, and the A nozzle for a nuclear reactor pressure vessel, characterized in that a collar is movably fitted into an outer thermal sleeve, and the sparger is fitted into the thermal sleeve with a tight fit for communication connection, Even if cold water leaks from the thermal sleeve, the outer thermal sleeve and collar prevent the cold water from coming into contact with the nozzle, and during inspection, the collar is moved and the sparger is removed to ensure a wide inspection work space near a part of the nozzle corner. It is something that can be done.

[Embodiments of the invention]

An example of the practical implementation of the present invention will now be described with reference to FIG.

A thermal sleeve 3 disposed inside the nozzle 2 of the reactor pressure vessel is integrally joined to the nozzle 2 by a weld E. An outer thermal sleeve 4 disposed between the thermal sleeve 3 and the nozzle 2 is integrally joined to the nozzle 2 at a weld F.

A knot-shaped collar 6 is fitted onto the outer circumferential surface of the outer thermal sleeve 4 by a loose fit so as to form a slip-fit structure. The collar 6 and the thermal sleeve 3 are connected by a stopper pin 7 to prevent the collar 6 from freely sliding.

A sparger 5 is fitted and joined within the thermal sleeve 3 by an interference fit.

In this embodiment, even if cold water leaks from the thermal sleeve 3, the leaked cold water is prevented from directly contacting the nozzle 2 by the outer thermal sleeve 4 and the collar 6. Similarly, even if cold water leaks from the fitting joint between the thermal sleeve 3 and the sparger 5, the collar 6 prevents the leaked cold water from directly contacting the nozzle 2. In this way, thermal sleeve 3
Even when the sparger 5 and the sparger 5 are fitted together, direct contact of cold water leakage to the nozzle 2 can be prevented.

Next, when inspecting the vicinity of a nozzle corner, the sparger 5 is pulled out by applying high water pressure to the tight fit portion. Prior to this pulling out, the stopper pin 7 is removed and the collar 6 is pushed and moved to the left. In this way, a large inspection work space can be obtained near a part of the nozzle corner, and the area toward the inside of the nozzle can also be easily inspected.

〔Effect of the invention〕

As described above, according to the present invention, direct contact of leak water to a part of the nozzle corner can be prevented, and the part of the nozzle corner can be easily inspected. As a result, it is possible to provide a nozzle for a reactor pressure vessel that prevents thermal fatigue of the inner surface of the nozzle and a part of the nozzle corner, and allows easy inspection of the nozzle.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a nozzle part for a reactor pressure vessel according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a reactor pressure vessel,
Figure 3 is a vertical cross-sectional view of a conventional reactor pressure vessel nozzle section;
FIG. 4 is a longitudinal sectional view of another conventional nozzle section for a reactor pressure vessel. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Nozzle, 3... Thermal I)-7', 4... Outer thermal sleeve,
5...Sparger, 6...Color, D...Part of nozzle corner, E. F...Welding part. Agent Patent attorney Akio Takahashi ￥ 1 Figure A 2 Figure 13 Figure γ 4

Claims (1)

[Claims] 1. A nozzle for a nuclear reactor pressure vessel comprising a thermal sleeve inside the nozzle and a sparger communicating with the thermal sleeve, wherein an outer thermal sleeve is provided between the thermal sleeve and the nozzle body, and the outer thermal sleeve The collars are movably fitted together,
A nozzle for a nuclear reactor pressure vessel, characterized in that the sparger is tightly fitted and connected to the thermal sleeve.