JPH02285287A - Nuclear reactor containment - Google Patents

Abstract

PURPOSE:To enable conducting a refueling work and work at the upper part of a dry well in parallel by providing a movable shielding body with which a space between a nuclear reactor pressure vessel and the dry well can be opened at the top part of a nuclear reactor shielding wall. CONSTITUTION:A top of a nuclear reactor shielding wall 2 is divided into two parts that are an inner surface side and an outer surface side, the inner surface side is constituted by a sleeve shaped shielding wall 6 as a movable shielding body and the wall 6 is held so as to be able to slide vertically along a fixed shielding wall 2A of the inner surface side. A space between a nuclear reactor pressure vessel 3 and a dry well 8 can be shielded by lifting up the wall 6 to block a space reaching to a nuclear reactor containment vessel 1. Considering about that a gap is generated between the vessel 1 and the wall 6 when the wall 6 is lifted up, a hanging wall for shielding is provided to the vessel 1 in order to shield a radiation passing through the gap. In this way, an amount of radiation to the dry well 8 is diminished and therefore there is no need to keep out an upper part of the dry well during a refuelling work.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor containment vessel that houses a nuclear reactor pressure vessel, and particularly relates to a nuclear reactor containment vessel that houses a nuclear reactor pressure vessel, and particularly to a nuclear reactor containment vessel that shields radiation from a nuclear reactor pressure vessel. This invention relates to a nuclear reactor containment vessel equipped with a shielding wall.

(Prior Art) In a nuclear reactor such as a boiling water reactor, a reactor containment vessel is installed in a reactor building. .

As shown in (B), a reactor pressure vessel (hereinafter abbreviated as RPV) 3 is accommodated. Around this RPV3,
As shown in FIGS. 6(A) and (8), a reactor shielding wall (hereinafter abbreviated as R8W) 2 is installed and covers the RPV 3. In addition, in the dry well 8 in the reactor containment vessel 1,
A platform 5 is provided for maintenance of each device.

By the way, in the reactor containment vessel 1 shown in FIG. 5, during normal operation, heat from the RPV3 rises between R8W2 and RPV3, and heat or pressure may accumulate in the containment vessel top head section 12. Conceivable. For this reason, R
The space between 8W2 and the reactor containment vessel 1 is opened to allow the above heat or pressure to escape to the dry well 8.

Furthermore, there is a risk that the dry well 8 will be irradiated with radiation 7 from between the R8W2 and the reactor containment vessel 1 when the spent fuel is extracted from the core during fuel exchange. Since there is a risk that workers may be exposed to radiation during this fuel exchange, the upper part of the dry well 8 is prohibited from entry.

(Problem to be solved by the invention) In the reactor shielding wall structure in the conventional reactor containment vessel, R
Since the space between 8W2 and reactor containment vessel 1 is open, the upper part of dry well 8 must be prohibited from entering during fuel exchange, and periodic inspection work here cannot be performed during fuel exchange. Therefore, the impact on the periodic inspection process is increasing. In particular, in a reinforced concrete containment vessel (RCCV), a hatch 4 for loading and unloading equipment is installed at the top of the dry well 8, and since this hatch 4 is the main access 10 during regular inspections, the dry well 8
The fact that workers are prohibited from entering the upper part of the fuel tank during fuel exchange has a significant impact on the periodic inspection process.

The present invention has been made in consideration of the above-mentioned circumstances, so that by shielding radiation to the upper part of the dry well during fuel exchange, it is possible to perform fuel exchange and work by workers at the upper part of the dry well in parallel. Another object of the present invention is to provide a reactor containment vessel that prevents heat or pressure from accumulating in the top head portion of the containment vessel during normal operation.

[Structure of the invention]

(Means for Solving the Problems) A reactor containment vessel according to the present invention is a reactor containment vessel in which a reactor shielding wall surrounding a reactor pressure vessel and shielding radiation from the reactor pressure vessel is installed. The present invention is characterized in that a movable shield capable of opening the space between the reactor pressure vessel and the dry well is provided on the top of the reactor shielding wall.

(Function) In the present invention having the above configuration, the movable shield provided at the top of the reactor shielding wall is activated at the time of fuel exchange,
By shielding radiation to the upper part of the dry well during fuel exchange, fuel exchange and work on the upper part of the dry well can be performed in parallel.

Furthermore, during normal operation, by opening the space between the reactor pressure vessel and the dry well, heat or pressure accumulated in the top head of the containment vessel can be released into the dry well.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Note that parts that are the same as or correspond to the conventional configuration will be described using the same reference numerals.

FIG. 1 shows a first embodiment of a nuclear reactor containment vessel according to the present invention. Inside this reactor containment vessel 1 is a reactor pressure vessel (RP).
This reactor containment vessel 3 is installed on an RPV support pedestal (not shown). A cylindrical reactor shielding wall (R3W) 2 is installed above the RPV support pedestal so as to cover the RPV 3.

Further, a platform 5 is provided in the dry well 8 of the reactor containment vessel 1, and workers perform maintenance work on each device on this platform 5. A hatch 4 for carrying in and out of the VI equipment is installed at the top of the dry well 8, and this hatch 4 serves as the main access during periodic inspections.

Furthermore, the top of R8W2 is divided into two parts, an inner circumferential side and an outer circumferential side, of which the outer circumferential side is constituted by a sleeve-shaped shielding wall 6 as a movable shield, and this shielding wall 6 is fixed on the inner circumferential side. It is held slidably in the vertical direction along the side shielding wall 2A. By lifting this movable shielding wall 6 and closing off the space between the reactor containment vessel 1 and the RPV 3 and the dry well 8.
It is now possible to shield between the Considering that a gap will be created between the movable shielding wall 6 and the reactor containment vessel 1 when it is lifted, a shielding wall 11 is installed in the reactor containment vessel 1 in order to shield radiation passing through the gap.
This is provided.

Next, the operation of this embodiment will be explained.

During normal operation, the movable shield W16 is lowered as shown by the solid line in FIG. 1, and the space between the RPV 3 and the dry well 8 is opened. Thereby, the heat or pressure accumulated in the containment vessel top head section 12 during normal operation can be released into the dry well 8.

On the other hand, during fuel exchange, the movable shielding wall 6 is lifted up to close off the space between the top of R8W2 and the reactor containment vessel 1, as shown by the two-dot chain line in FIG. This allows the movable shielding wall 6 to be used when pulling out spent fuel rods during fuel exchange.
Therefore, the radiation irradiated to the dry well 8 can be shielded, and the upper part of the dry well 8 will not be prohibited from entering. Therefore, the fuel exchange work and the periodic inspection work on the upper part of the dry well 8 can be performed in parallel.

FIG. 2 shows a second embodiment of the reactor containment vessel according to the present invention, and the same members as those in the first embodiment will be described with the same reference numerals. In the first embodiment, the top of the R8W2 is divided into two parts, the inner circumference side and the outer circumference side, and the outer circumference 1111 part is used as the movable shielding wall 6a, but in this embodiment, as shown in FIG. A movable sleeve-shaped shielding wall 1 is installed on the outer circumferential side of the top of the
6 is provided. According to this embodiment, since the movable shielding wall 16 is provided on the outer peripheral side of the existing R8W2, manufacturing efficiency is improved and costs can be reduced. The other configurations and operations are the same as those of the first embodiment, so their explanation will be omitted.

3 and 4 show a third embodiment of the reactor containment vessel according to the present invention. The same members as those in the first embodiment are designated by the same reference numerals and their explanations will be omitted.

In this embodiment, the top of R8W2 extends to the vicinity of the ceiling wall of the dry well 8 of the reactor containment vessel 1, and the top of R8W2 is divided into two, an inner circumferential side and an outer circumferential side, and the outer circumferential side is a movable shield. The wall 26 is configured to be slidable in the circumferential direction relative to the inner peripheral side (fixed side) of the top of R8W2. Openings 2a and 26a are formed at predetermined intervals in the circumferential direction on the inner peripheral side of the top of R8W2 and on the movable shielding wall 26, respectively, so as to be openable and closable.

In the above configuration, during normal operation, as shown in FIG. 4(A), the opening 2a on the inner peripheral side of the top of R8W2 and the opening 26a of the movable shielding wall 26 should be aligned in the circumferential direction. Then, the space between RPV3 and dry well 8 is opened,
It's communicating. As a result, the containment vessel top head section 1
The heat or pressure accumulated in dry well 2 can be released into dry well 8 through openings 2a and 26a.

Also, in order to shield the radiation (indicated by the arrow in the figure) 7 that is irradiated to the dry well 8 during fuel exchange, as shown in Fig. 4 (B).
Movable shielding as shown! 26 in the circumferential direction to connect the opening 2a on the inner peripheral side of the top of R8W2 and the movable shielding wall 2.
By differentiating the circumferential position from the opening 26a of the RPV 3 and the dry well 8, the space between the RPV 3 and the dry well 8 is shielded.

In this way, according to the third embodiment, the radiation 11
7 is shielded, the movable shielding wall 6 of the first embodiment
This eliminates the need for lifting, which improves operability and requires a smaller power source. The other configurations and operations are the same as those of the first embodiment, so their explanation will be omitted.

(Effects of the Invention) As described above, according to the present invention, a movable shield is provided at the top of the reactor shield wall, and the i!! shield shields the space between the reactor pressure vessel and the dry well during fuel exchange. By doing so,
Because the radiation layer into the drywell is reduced, there is no need to cordon off the top of the drywell during refueling.

As a result, fuel exchange work and periodic inspection work on the upper part of the dry well can be performed in parallel, making it possible to shorten the periodic inspection process.

In addition, by opening the space between the reactor pressure vessel and the dry well during normal operation, heat or pressure buildup in the top head of the containment vessel is prevented, making it possible to provide a highly reliable reactor containment vessel. This effect is achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram partially showing a first embodiment of a reactor containment vessel according to the present invention, FIG. 2 is a block diagram partially showing a second embodiment of the present invention, and FIG. 3 is a block diagram partially showing a first embodiment of a reactor containment vessel according to the present invention. FIGS. 4A and 4B are plan cross-sectional views showing the movable shielding wall in FIG. 3 in an open state and a shielded state, respectively. FIG. FIGS. 6(A) and 6(B) are a configuration diagram showing a conventional reactor containment vessel, and are a longitudinal sectional view and a partial plan view showing the structure of the reactor shielding wall in FIG. 5. 1... Reactor containment vessel, 2... Reactor shielding wall (R8
W), 3... Reactor pressure vessel (RPV), 6...
・Movable shielding wall (shielding body), 8...Dry well, 1
2... Containment vessel top head section.

Claims (1)

[Claims] In a reactor containment vessel equipped with a reactor shielding wall that surrounds a reactor pressure vessel and shields radiation from the reactor pressure vessel, a reactor shielding wall is provided at the top of the reactor shielding wall to connect the reactor pressure vessel and a dry well. A nuclear reactor containment vessel characterized by being provided with a movable shield that can be opened between.