JPS58156Y2 - Shielding structure of reactor shielding wall opening - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shielding structure for an opening in a reactor shielding wall, and in particular, to prevent blowdown from the reactor pressure vessel from flowing between the reactor pressure vessel and the reactor shielding wall. The present invention relates to a shielding structure for an opening in a nuclear reactor shielding wall suitable for use in a nuclear reactor shielding wall.

Generally, a reactor pressure vessel (hereinafter referred to as RPV) is surrounded by a reactor shield wall (hereinafter referred to as R8W) at a distance of about 300 to 400 mm.

Most of the welded parts between the RPV nozzle and the pipe, which are expected to break as a measure against pipe breakage, are located within the annular part of the RPVR8W.

Therefore, in the event of a rupture, blowdown from the RPV side will flow into this narrow annular portion, causing a pressure increase and creating a large moment and shear force at the R8W base and the RPV base.

In addition, the RPV nozzle opening of R3W has an IS of the welded part.
For In-Service Inspection, a removable annular shield is installed and therefore requires significant support for the jet forces of the shield.

However, considering the ISI work under radiation, this increases the work to remove the support, which is not desirable.

The present invention solves the above-mentioned conventional difficulties, and the blowdown from the RPV side does not flow into the RPV-R3W annular part, so no jet load is applied to the shield, RPV, and R3W through the reactor shield wall opening. The purpose is to provide a shielding structure for the area.

The present invention involves fitting a split pipe with a required gap between the shield and the piping, and fixing this pipe to the nozzle via a slide mechanism that can absorb thermal expansion during reactor operation. It is removably connected to the seal ring, and blowdown from the RPV side does not flow into the RPV-R8W annular part.
It is configured so that it passes between the piping and the split pipe and is blown out to the outside of the R8W.

The present invention will be described below based on an illustrated embodiment.

In FIG. 1, 1 is an RPV, and an RPV nozzle 2 is integrally provided at a required position of this RPVl.
1, R8W3 is erected on the outer periphery so as to cover RPV1.

An opening 4 is provided at a position facing the RPV nozzle 2 of R3W3, and an annular shield 5 is provided in this opening 4.
is removably embedded.

A pipe 6 whose tip end is welded to the RPV nozzle 2 is loosely fitted into the shield 5 as shown in FIG. 1, and the shield 5 has a required gap between it and the pipe 6. And the tip is RPV
A split pipe 7 (split into two in this embodiment) that reaches the nozzle 2 is fitted.

Then, this pipe 7 is connected to the RP via a slide mechanism 8.
It is removably connected to a seal ring 9 fixed to the V nozzle 2.

This seal ring 9 has a sufficient amount of overlap in the vertical direction to absorb elongation due to thermal expansion during nuclear reactor operation.

As shown in FIG. 2, the slide mechanism 8 has a connecting portion 8a that is fixed to the pipe 7 and has a groove on the side opposite to the seal ring 9, and a connecting portion 8a that is fixed to the seal ring 9 and slides into the dovetail groove. It is formed from a possible retaining portion 8b, and is configured to absorb elongation due to thermal expansion during reactor operation.

In FIG. 1, 10 is a weld line between the RPv nozzle 2 and the pipe 6, and 11 is an RPV-R8W annular portion formed between RPVl and R3W3.

In the above configuration, if a break occurs at the welded part of the RPV nozzle 2, the jet from the RP nozzle 2 will
Since the route into the RPV-R8W annular portion 11 is cut off, it passes between the pipe 6 and the pipe 7 and is discharged to the outside of the R3W3.

Note that elongation due to thermal expansion during reactor operation acts to move the seal ring 9 in the vertical direction, but since the seal ring 9 and the pipe 7 are connected via the slide mechanism 8, The jet inflow into the RPv-R3W annular portion 11 is almost eliminated.

As explained above, according to this embodiment, R3W and R
The design load of the PV can be reduced, thereby reducing the number of base anchor bolts and structural materials.

Furthermore, since support for the opening shield can be omitted, removal work during ISI can be reduced, and radiation exposure can be reduced.

The present invention has been explained above based on the preferred embodiments. According to the present invention, blowdown from the RPV side
There is no flow into the 8W annular portion, thus preventing the jet load from being applied to the shield, RPV and R8W.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a view taken along the line II--II in FIG. 1...RPV, 2...RPV nozzle,
3...R3W, 4...Opening, 5...
...shield, 6...piping, 7...
Pipe, 8...Slide mechanism, 9...
Seal ring.

Claims (1)

[Scope of utility model registration request] An opening is provided in a reactor shielding wall provided around the reactor pressure vessel at a position facing the reactor pressure vessel nozzle, and an annular shield is placed in this opening and is welded to the reactor vessel nozzle. In the shielding structure for the opening of the reactor shielding wall, in which the piping is inserted into the shield, a split pipe having a required gap between the pipe and the pipe is fitted into the shield, and the pipe has the following features: A shielding structure for an opening in a nuclear reactor shielding wall, characterized in that it is removably connected to a seal ring fixed to a nozzle via a slide mechanism capable of absorbing thermal expansion during nuclear reactor operation.