JPH0652312B2 - Liquid metal cooled reactor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a shield plug 4 in a liquid metal cooled nuclear reactor.
The present invention relates to a reactor equipped with a guide tube for inserting a device inside the reactor, which is capable of improving the seismic resistance of the guide pipe for the inserting device inside the reactor and preventing the rise of cover gas in the reactor.

[Technical Background of the Invention and Problems Thereof] In general, a liquid metal cooled nuclear reactor using a liquid metal such as sodium as a coolant has a core portion 1 as shown in FIG.
The upper end of the reactor vessel 2 accommodating the above is closed by a shield plug 4 on which the reactor core upper mechanism 3 is mounted.

The shielding plug 4 has a sodium see-through device for measuring the presence or absence of an abnormality in the gap between the upper core mechanism 3 and the upper surface of the core 1,
An opening for inserting an in-reactor insertion device 5 such as an in-reactor relay device for inserting and removing new fuel or spent fuel into and out of the reactor vessel 2 is provided.

The reactor insertion device 5 such as the above-mentioned sodium see-through device and in-reactor relay device is a cylindrical elongated device, and the reactor insertion device 5 is installed in the reactor vessel 2 during an earthquake or the like. In order to prevent the collision with the inner cylinder 6 and prevent the interference with the heat shield plate 7 of the shield plug 4 at the time of inserting the reactor insertion device 5, the above-mentioned opening is provided in order to improve the insertability. An in-reactor insertion device guide tube 8 is installed. A door valve 9 is provided on the upper end of the device guide tube for inserting equipment in the nuclear reactor. In FIG. 2, reference numeral 10 indicates a shielding plug cooling layer.

As shown in FIG. 3, the in-reactor insertion device guide pipe 8 is securely fixed between the shield plug 4 and the door valve 9 via the flange portion 8a, and the in-reactor insertion device guide pipe 8 is At the lower end, an insertion device supporting portion 8b that engages in the middle of the insertion device 5 in the nuclear reactor is projected.

In the conventional liquid metal cooled nuclear reactor configured as described above, the annulus portion 12 exists between the opening of the shield plug 4 and the reactor insertion device guide tube 8, and the reactor cover gas space 11 FP gas having high radioactivity rises in the annulus portion 12 due to natural convection.

This FP gas is sealed by an O-ring inserted between the flange portion 8a of the guide tube 8 and the shield plug 4, and is prevented from leaking out of the furnace.

However, since the FP gas has high radioactivity, in the reactor having a structure in which this rises through the annulus portion 12 to the lower portion of the flange portion 8a, the shield plug 4
In order to keep the radiation dose on the upper surface below the allowable value, it is necessary to install a large amount of radiation shields 13 on the upper surface of the shield plug 4.

In addition, the reactor insertion device guide tube 8 has a flange portion 8 at the upper end.
Since it is only fixed to the shielding plug 4 by a, it has a long cantilever-like support structure, and in order to secure the rigidity necessary to support the in-reactor insertion device 5 with the insertion device support portion 8b for earthquake resistance. Had a drawback that it had a large diameter and a thick structure.

[Object of the Invention]

The present invention has been made to eliminate the above-mentioned drawbacks of the background art, and supports seismic support of the reactor insertion device 5 with high rigidity and prevents the reactor cover gas from rising above the shielding plug 4. It is an object of the present invention to provide a liquid metal cooling type nuclear reactor equipped with a guide tube 8 for inserting equipment in a nuclear reactor having the function of

[Outline of Invention]

In the liquid metal cooled nuclear reactor of the present invention, a guide tube for guiding the equipment inserted into the reactor, which penetrates the shield plug, is supported in the opening of the shield plug at two points of the cylindrical shaft seal structure portion and the taper support structure portion. It is characterized by that.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the characteristic part of the nuclear reactor of the present invention.
The same parts as those in FIG. 3 or FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present invention, the reactor insertion device guide tube 20 installed in the opening of the shielding plug 4 has an outer diameter substantially the same as the inner diameter of the opening of the shielding plug 4 as shown in FIG. It is formed on the shield plug 4 side at an intermediate position between the cylindrical shaft seal structure portion 20a and the insertion device supporting portion 20b, which is a seal between the cylindrical shaft seal structure portion 20a and the opening of the shield plug 4 by 21. And a taper support structure portion 20c which is hermetically engaged with the taper hole 4a. Further, the door valve 9 is directly mounted on the shield plug 4 via the O-ring 22.

In the liquid metal cooled reactor of the present invention configured as described above, the annulus portion 12 communicating with the in-reactor cover gas space 11 is partially closed by the tapered support structure portion 20c, so that the in-reactor cover gas is It does not flow upwards. Therefore, even if the furnace cover gas has high radioactivity, the radiation dose on the upper surface of the shield plug 4 is not so high, and the shield 13 described with reference to FIG.

Further, the in-reactor insertion device guide tube 20 is supported by the shield plug 4 by the two points of the cylindrical shaft seal structure portion 20a and the taper support structure portion 20c, so that the guide tube 8 of the conventional cantilever support structure is compared with the guide tube 8. Seismic resistance has been significantly improved,
Therefore, it is possible to reduce the wall thickness.

The O-ring 21 of the cylindrical shaft seal structure portion 20a described above is used.
Is used to maintain airtightness in the furnace when removing and repairing the door valve 9.

〔The invention's effect〕

As is clear from the above description, in the liquid metal cooled nuclear reactor of the present invention, the reactor insertion device guide tube has the two-point support structure of the cylindrical shaft seal structure part and the taper support structure part, and Since the spacing between the supporting spans can be made large, the earthquake resistance of the guide tube is improved, and a small diameter and thin wall structure can be achieved.

In addition, since a surface contact portion is formed in the tapered support structure portion located at a position separated from the upper surface of the shield plug, the rise of the cover gas in the furnace that naturally convects in the annulus portion can be prevented at this portion. The radiation dose is kept low, eliminating the need to use large amounts of radiation shields as in the past.

Moreover, since the guide pipe for inserting equipment inside the nuclear reactor is not directly related to the boundarying of the reactor cover gas and the like, high quality is not required for design and quality assurance. Therefore, according to the present invention, the reliability of the liquid-cooled reactor can be improved, and at the same time, the cost can be considerably reduced.

[Brief description of drawings]

FIG. 1 shows a main part of a nuclear reactor of the present invention. FIG. 1 is a vertical cross-sectional view in the vicinity of a guide tube for inserting equipment in the reactor, and FIG. 2 is a vertical cross-sectional view showing a schematic configuration of a liquid metal cooled nuclear reactor. FIG. 3 is a vertical cross-sectional view illustrating a conventional guide pipe for inserting equipment in a nuclear reactor. 1 ... Core part 2 ... Vessel 3 ... Core upper part mechanism 4 ... Shielding plug 5 ... Reactor insertion device 6 ... Reactor container inner cylinder 7 ... Heat shield plate 8 ... Reactor insertion device Guide tube 9 ...... Door valve 10 ...... Cooler 11 ...... Reactor cover gas space 12 ...... Annulus part 13 ...... Shield 20 ...... Reactor insertion equipment guide tube 20a ...... Cylindrical shaft seal structure part 20b ...... Insertion device support 20c ... Taper support structure

Claims (2)

[Claims] 1. A guide tube for penetrating a shield plug of a liquid metal cooled nuclear reactor for guiding equipment inserted into the reactor is supported in the opening of the shield plug at two points of a cylindrical shaft seal structure and a taper support structure. Liquid metal cooled nuclear reactor characterized by being 2. The taper support structure closes the annulus portion formed between the shield plug and the reactor insertion instrument guide tube at a position separated from the upper surface of the shield plug by the taper support structure portion, and the reactor cover gas has a taper support structure. The liquid metal cooled nuclear reactor according to claim 1, wherein the liquid metal cooled nuclear reactor is prevented from rising beyond a portion.