JPS58131592A - Method of capturing cladding in reactor pressure vessel - 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 The present invention relates to a method for capturing crud within a nuclear reactor pressure vessel.

Conventionally, activated crud exists within a nuclear reactor pressure vessel, which is an impediment to radiation protection and maintenance of the nuclear reactor system. For example, when removing nuclear fuel from a reactor pressure vessel, it is necessary to move through water due to the high radiation dose, and it is necessary to fill the reactor well above the reactor pressure vessel with water. This water filling is caused by the water level in the reactor pressure vessel, and at this time, crud existing in the reactor pressure vessel infiltrates into the reactor well as the water level rises. For this reason, after the conversion of nuclear fuel, etc. is completed and the water in the reactor well is removed, crud remains attached to the wall surface of the reactor well. Since this crud is radioactive, it must be decontaminated, but there are restrictions because the work is under a radiation atmosphere. For example, some of the wells around the reactor pressure vessel and reactor containment vessel are rounded and have a complicated shape, making decontamination and cleaning difficult. Since dyeing is a critical process, work 9 must be carried out smoothly. For this reason, decontamination of reactor wells requires a lot of effort.

He had been exposed to radiation.

The present invention is provided to eliminate these drawbacks.

To explain the present invention with reference to the drawings, FIG. 1 shows a reactor pressure vessel composed of nozzles 3 and 7 flange 4 of a lid 2 at the upper part of the vessel 1, and a filter 5 is attached to the 7 flange 4. An outlet pipe 6 is attached to the upper part of the filter 5, an inlet pipe 7 is attached to the lower part of the filter 5, and a 7 flange 8 is fixed to the tip of the inlet pipe 7.

Flange 4 and flange 8 are connected by bolts and nuts.

In FIG. 2, a cover plate 1o is placed on the flange 9 of the container 10. The cover plate 10 has a hole 11, and above the hole 11 there is a tube 12.
A flange 13 is fixed to the pipe 12.

A filter 5 is attached to this upper part. An outlet pipe 6 is attached to the upper part of the filter 5, an inlet pipe 7 is attached to the lower side of the filter 5,
A flange 8 is fixed to the tip of the inlet pipe 7, and a flange 13
and the flange 8 are connected with bolts, nuts, etc. Note that hanging fittings 17 are attached to the cover plate 10 at appropriate positions 9, for example, at equal intervals on a plane.

Figure 4 of the third book shows a wire mesh 14 on the top of the 7 lunges 9 of the container 1.
A filter material 15, such as a sponge or glass wool, covered all around is placed, and a presser plate 16 is placed on top of it. The planar shape of the holding plate 16 is the same as the planar shape of the flange 9. Hanging fittings 17 are attached to the holding plate 16 at appropriate positions 1, for example, at regular intervals on a plane. wire mesh 1
There are two types of 4: a structure that is separated from the presser plate 16 and a structure that is fixed to the holding plate 16, but in this example 9, a case where it is fixed will be explained.

That is, the wire mesh 14 and the filter material 15 are fixed to the holding plate 16 with screws or the like.

After configuring as described above, the pumps attached to the reactor pressure vessel, such as the reactor recirculation system pump and the reactor feed water pump, are operated to inject water into the vessel 1 to raise the water level inside the vessel 1. In the case of Fig. 1 and Fig. 2, the water in the filter 5 is filtered.
In the case of FIGS. 3 and 4, it is discharged into the reactor well 16 via the filter material 15, and then, in the case of FIG. 1, the lid 2 is lifted out of the reactor well 18 using a crane. Flange 4. The bolts and nuts connecting the flanges 8 are disassembled and the filter 5 is recovered.

In the case of Figure 2, the ridge board 10 is moved using a crane.

Pull it out of the reactor well 18 and dismantle the bolts and nuts connecting 7 langes 8 and flange 13.

Collect the filter 5.

In the case of FIGS. 3 and 4, the holding plate 16 is lifted out of the reactor well 18 using a crane, and the wire mesh 14 and filter material 15 are recovered from the holding plate 16 by loosening the screws.

The recovered filter 5 and filter material 15 adsorb the crud that was present in the container 1. That is, when water is poured into the container 1, the water in the container 1 is stirred, and at the same time, the crud is also suspended, and as the water level in the container 1 rises, the crud moves, and the water passes through the filter 5 and the filter material 15. The cladding contained in the cladding is adhered and absorbed.

Since the present invention operates by capturing the crud in the vessel 1 as described above, it is possible to reduce crud adhering to the reactor well 18 during and after nuclear fuel exchange. Therefore, work efficiency can be improved and radiation exposure can be reduced.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention for capturing crud in a nuclear reactor pressure vessel. FIGS. 1 to 3 are side views (including partial cross sections) showing the embodiment. FIG. 4 is a partial side view showing the embodiment. 1... Container 2...
......Lid 3...Nozzle
4...Flange 5...
・・・・・・Filter 6・・・・・・・・・・・・
・Outlet pipe 7・・・・・・・・・Inlet pipe 8・
・・・・・・・・・・・・Flange 9・・・・・・・・・
...7 lunge 10...Enoki board 11...Hole 12...
・・・・・・・・・Tube 13・・・・・・・・・・・・
7 Lunge 14・・・・・・・・・Wire mesh 15・
......Filtering material 16...
......Press plate 17...Hanging metal fittings 18~...Reactor well patent applicant Representative of System Maintenance Co., Ltd. Honma Take No. 101 18 Figure 2 Figure 3 Figure 1 Figure 6

Claims (1)

[Claims] A filter or filter material is attached to a reactor pressure vessel. Drive the pump and inject water into the reactor pressure vessel. Capture of crud in the reactor pressure vessel by raising the water level in the reactor pressure vessel, releasing the water in the reactor pressure vessel to the reactor well via a filter, and causing the crud to adhere to the filter or filter material. Method.