JPS60165600A - Decontaminating method - 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 decontaminating tools, equipment parts, piping, points, tanks, etc. used in nuclear power plants and whose surfaces are contaminated with radioactive substances.

Conventionally, this type of decontamination method involves spraying water and an abrasive material such as iron particles or glass particles onto a surface contaminated with radioactive materials, and the radioactive materials are removed from the surface by the water jet pressure and the abrasive action of the abrasive material. A method is provided to remove the . However, the biggest problem with the above decontamination method is the treatment of decontamination waste liquid.

The purpose of the present invention J is to solve the above-mentioned conventional problems, and the main point is to use an organic abrasive material that can be incinerated.

The invention will be explained in detail below.

In the present invention, organic abrasives are used as described above, and examples of the organic abrasives include plastic particles such as polyglobylene, polymethyl methacrylate, polystyrene, and polyamide, and wood particles such as wood I particles and seed shells. etc. are included. These organic abrasives are softer than inorganic abrasives and are less likely to be crushed by collision with the surface to be treated.They can also be reused and are therefore scattered around, causing secondary contamination. No fine powder is produced. And of course, incineration treatment is TjJ's ability. Among the above-mentioned organic abrasives, walnut shell pieces are most desirable because they have a suitable hardness, exhibit a large abrasive effect, and are difficult to crush. The above-mentioned organic abrasive is generally about 0.4 to 3.
Q: The particle size is about 11M.

To carry out this process, for example, an apparatus system as shown in FIG. 1 is used.

In the figure, (1) is a workpiece having a surface (1) A contaminated with radioactive substances, and an organic abrasive material (3
) A and water (3) B are sprayed. The organic abrasive (
3) A is stored in the Kenryakugetsu Rin storage tank (4) and goes to the supply route (5)
The water (3)B is stored in a water storage tank (6) and is supplied to the nozzle (2) through a supply path (7) with a pump (7)A interposed. The decontamination waste liquid (3)' after the contamination is received in the receiver (8) and passed through the hooking device (9).
The organic abrasive material (3) is directly sent to the organic abrasive material (3) and separated into a solid content mainly composed of A and a liquid mainly composed of water (3) B.

Needless to say, in addition to the filter (9), a centrifugal separator or the like may also be used for solid-liquid separation. The solids separated in this way are collected again as abrasive material into the storage tank (4) via the collection path θQ, but after a certain number of uses, the contamination progresses.
Since it is crushed, it is taken out from the disposal route qυ and incinerated. - Power water (3) B is also collected into the storage tank (6) via the recovery path (6) with pump 09A, but as it becomes contaminated after being used a certain number of times, it is removed from the disposal path (to). It is taken out and passed through an ion-exchange resin packed column (such as a 1L column) for purification and decontamination, and then discharged.

As an indicator of the decontamination effect of the organic abrasive of the present invention, the effect of removing a coating film on the surface to be treated was tested. The results are shown in Table 1.

2I￥1 table Paint film removal effect (diameter of paint film removed surface (a))
In Table 4, the nozzle distance is 39□DI, the processing time is 10 minutes, the spray angle is 90°, the amount of abrasive is 1.0 kg/min (50 kVcA discharge pressure) for walnut shells, and 3.
0 k'j/min (150k (1/Cd discharge pressure), polymethyl methacrylate 1.4197 min (50kg7c)
According to Table 1, when only water was injected without adding an abrasive, the paint film was not removed at all, but when an organic abrasive was added. In this case, the paint film is removed, and especially when walnut shells are used, a sufficient paint film removal effect can be seen even at a discharge pressure of 50 kg/cA.

As described above, the present invention sprays an organic abrasive and water onto a surface contaminated with radioactive substances to decontaminate the surface, so the solid content of the decontamination waste liquid is mainly composed of the organic abrasive and therefore cannot be incinerated. The possible liquids are mainly water-based and therefore easy to purify.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of an apparatus system used in the method of the present invention. In the figure: (1)...Object to be treated, (1)A...Surface contaminated by radioactive substances, (2)...Nozzle, (3)A...Organic abrasive material , (3) B...Water patent applicant Daido Steel Co., Ltd. Total 1 item

Claims (1)

[Claims] After decontaminating the surface contaminated by radioactive substances by spraying organic abrasive gI and water, the decontamination waste liquid is separated into solid and liquid, and the solid content, which is mainly composed of organic abrasives, is incinerated, and the solid content, which is mainly composed of water, is incinerated. A decontamination method that involves purifying the liquid.