JPS60247199A - Method of washing radioactive contaminated molded shape - 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 [Field of Application of the Invention] The present invention relates to a method for cleaning a molded article contaminated with a radioactive substance with an organic solvent.

[Background of the invention]

For example, when working near a nuclear reactor, small solid objects such as boots, helmets, bands, masks, and other equipment used by workers, and tools such as spanners and hammers (hereinafter referred to as molded products) are contaminated with radioactive materials and must be cleaned.

To clean molded products contaminated with radioactive materials,
There are methods using water washing and methods using organic solvents, and each method has the following problems.

In the case of washing with water, a large amount of radioactively contaminated wastewater is generated, so it is not easy to treat this wastewater.

When using organic solvents, it is difficult to remove contaminants attached to the groove bottoms (for example, the bottom of the anti-slip grooves on the backs of boots) by simply putting the contaminated molded product in a cleaning machine and turning it. For this reason, in the past, a worker generally inserted both hands into a closed sink tank and manually cleaned the tank using a solvent spray nozzle or a brush. However, this method requires a lot of labor and also makes it difficult to manage the health of the workers. Furthermore, manual cleaning results in a large loss of solvent, which may cause environmental pollution.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and it is possible to eliminate moldings contaminated with radioactive substances by reducing solvent loss, eliminating the risk of environmental pollution, and eliminating the risk of producing a large amount of contaminated wastewater. The purpose of the present invention is to provide a cleaning method that can automatically clean products with high efficiency and that can easily capture and recover contaminants.

[Summary of the invention]

In order to achieve the above object, the cleaning method of the present invention is characterized by placing the molded product to be cleaned together with a number of small brushes in a horizontal cleaning drum, injecting an organic solvent into the drum, and rotating the drum. shall be.

[Embodiments of the invention]

The accompanying drawing is a system diagram showing the arrangement and connections of each component in a cleaning apparatus used in one embodiment of the cleaning method of the present invention.

1 is a horizontal washer, and has a structure in which an inner shell 1a-2 is provided within a horizontal cylindrical outer shell 1a-1, and the inner shell 1a-2 is rotated by a drive device (not shown).

1b is a door provided on the end face of the outer shell 1a-1, and 1c is a shower nozzle provided on the door.

A solvent vapor extraction hole 1e is provided above the outer shell 1m-4.

A hot air blowing hole 1f and a gas extraction hole 1h are provided, and a bubble blowing nozzle 1g and a solvent outflow hole 11 are provided on the lower surface of the outer shell 1&-1.

A indicated by a broken line is a bubble blowing line, and blower 2, pulp 3. They communicate via a check valve 4.

The solvent outflow hole 11 is communicated with the button trap 5. This button trap is a strainer for removing small solid foreign matter, and is equipped with two discharge valves 5a and 5b.

The discharge valve 5a is connected to a solvent distillation purification line, and
6. Expansion tank 7. Still capacitor8.
The oil passes sequentially through a water separator 9 and reaches a clean oil tank 10.

The discharge valve 5b is connected to the solvent circulation line B, and the non-tank 11. It reaches the shower nozzle 1c of the washer 1 through the pulp 11a, the pump 12, the filter 13, and the solvent injection valve 1j in this order.

Reference numeral 14 denotes a low-temperature condenser installed in the organic solvent recovery line (indicated by a chain line) C. Air containing solvent vapor in the outer shell 1 is sucked in by a fan 15 through a dust filter 16, and the solvent vapor is removed. It is cooled and liquefied and sent to the water separator 9. The air from which the solvent has been removed by the low-temperature condenser 14 is heated by the heater 17 and turned into hot air, which is blown into the outer shell 1a-1.

Next, an example will be described in which work boots with radioactive sludge adhering to them were cleaned using the cleaning device as described above.

Eight pairs of boots 18 to be washed and 50 brushes 19 are placed inside the inner trunk 1a. Brush 19 used in this example
is a brush with a shape and 9 dimensions similar to a household tank.

The organic solvent in the simain tank 11 is pumped up by the pump 12 and injected into the outer shell 1a-2 to a predetermined level, and the inner shell 1a-2 is rotated at 6r, p, m for 5 minutes to perform reservoir washing. At this time, a mixture of solvent vapor and air is force-fed by the blower 2 and is ejected from the bubble ejection nozzle 1g. The ejected bubbles perform a stirring action while rising in the solvent, increasing the efficiency of contact between the solvent and the boots 18, and promoting the cleaning effect.

The boots 18, which are the items to be washed, are mixed with the brush 19 and are agitated in the inner body 1a-2 while sliding against each other, and dirt is difficult to remove using conventional techniques, such as the uneven grooved bottom of the boots to prevent slipping. The exposed areas are also scrubbed with the bristles of the brush to remove radioactive contaminants.

After the above-mentioned reservoir washing (5 minutes), open the discharge valve 5a and remove the outer shell 1a.
The solvent in -1 is discharged to the distiller 6. The time required for this draining process is about 1 minute. The waste liquid is vaporized in the distiller 6,
It is liquefied and collected in a still condenser 8, and is collected in a water separator 9.
The oil is then stored in the clean oil tank IO.

After the draining is finished, the discharge valve 5a is closed and the drain valve 5b is opened, and in parallel with the distillation and purification of the drained liquid, the inner shell 1a-2 is rotated while the pump 12 is operated to perform circulation washing for 3 minutes. .

In this circulation washing process, the pump 12 is connected to the non-tank 11.
The solvent inside the boots is sucked in and pumped, and the pressed out solvent passes through the filter 13 and is ejected from the shower nozzle IC into the inner trunk 1a-2, where it flows into the boots 18. The brush 19 is washed away and the water is returned to the main tank 11 via the button trap 5.

During the above-mentioned circulation washing, the brush 19 comes into sliding contact with the boots 18 to promote the rinsing effect.

After circulation washing, remove the solvent in the outer shell 1a-1.
1), the drying fan 15 is operated and the drying process begins. In this example, the required time for drying PJr was 8 minutes.

During the above drying process, the pulp 1j is closed, the pulp 20 is opened, the pump 12 is operated, and the solvent in the main tank 11 is filtered and cleaned by the filter 13 in preparation for the next cycle.

It was confirmed that the radioactive contaminants attached to the boots were completely removed by the above-mentioned procedure, even when washed by hand.

In this example, as described above, boots with radioactive contaminants adhered to them are drained for 5 minutes, circulated for 1 minute, and drained for 3 minutes. ... Drying for 1 minute ... 8 minutes Total cleaning was performed for 18 minutes.

As is clear from the above operation, this embodiment does not generate a large amount of contaminated wastewater unlike washing with water. In addition, since the radioactive contaminants mixed into the organic solvent used as the cleaning liquid are captured in the filter 13 or remain at the bottom of the distiller 6, it is easy to collect them and process them all at once.

Furthermore, since the organic solvent is contained in a sealed system, there is little loss and there is no risk of environmental pollution. Moreover, since manual cleaning by workers is not required, the number of man-hours required for the work is small, and no particular difficulty is caused in health management of workers, especially health management related to radiation exposure.

〔Effect of the invention〕

As detailed above, according to the cleaning method of the present invention, a large number of brushes are automatically rubbed against the molded product to be contaminated, so molded products contaminated with radioactive substances can be thoroughly cleaned with high efficiency. In addition, there is no risk of environmental pollution as there is less loss of organic solvent used as a cleaning solution, and there is no risk of causing problems with wastewater treatment as there is no generation of large amounts of contaminated wastewater. play.

[Brief explanation of drawings]

The accompanying drawing is a system diagram of a cleaning device used in one example of implementing the cleaning method of the present invention. 1...Washer equipped with horizontal cleaning drum, 4a-1.
...Outer body of the washer, 1a-2...Inner body which is a horizontal cleaning drum, IC...Shower nozzle, 1g...Bubble jet nozzle, 15...Drying fan, 18...Water Work boots as an example of laundry, 19...brush. Patent applicant: Tokyo Washing Machinery Co., Ltd. Agent
Patent Attorney Masami Akimoto

Claims (1)

[Claims] A method of cleaning a molded article contaminated with radioactive materials with an organic solvent involves placing the molded article to be cleaned and a plurality of brushes in a horizontal cleaning drum, injecting an organic solvent into the drum, and rotating the drum. A method for cleaning radioactively contaminated molded products, characterized by: