JPH0251159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering solid contaminants deposited at the bottom of a wide tank in nuclear reactor equipment.

Nuclear reactor equipment has wide tank bottoms that contain radioactive solid contaminants in residual water, and these large tank bottoms must be decontaminated to maintain a good environment.

Conventionally, scraping decontamination methods using brushes or high-pressure water jets were often used. However, with this method, there is a risk that water droplets containing highly concentrated radioactive solids may be dispersed into the air, and there is a strong demand for preventive measures and regulations on work behavior.

An object of the present invention is to provide a method for effectively removing highly radioactive coarse solids from a wide tank bottom on which radioactive solid contaminants have accumulated.

The method for achieving the above objective is summarized as follows.

That is, when decontaminating the solid contaminants deposited on the bottom of a wide residual water tank in a nuclear reactor facility, an endless narrow water channel is temporarily formed in the bottom of the wide tank using easily handled partitions. Next, a pump equipped with a solid-liquid separator is placed in this temporary waterway, and its suction pipes and discharge pipes are arranged in opposite directions along the temporary waterway, and the pump is operated to generate a strong water flow. This facilitates the washing away and suction recovery of accumulated solid contaminants.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

A narrow endless water channel as shown in FIG. 1 is temporarily formed by attaching it to the bottom of a wide tank where there is residual water and using a partition 16 that is easy to remove. Next, the waterway decontamination device A is installed in this temporary waterway.

As shown in Fig. 2, the waterway decontamination device A is composed of a diaphragm pump 2 and a solid-liquid separator, such as a cyclone 6, and its water intake pipe 4 and discharge pipe 5 are arranged in opposite directions along the temporary waterway. It is installed submerged in water. By operating the diaphragm pump 2, the water 3 in the waterway generates a high-speed circulating flow as shown by the arrow 11, and the solid contaminants 12 deposited on the bottom of the water are washed away through the discharge pipe 5 and collected by suction through the water suction pipe 4. Can be done.

The diaphragm pump 2 is driven by compressed air supplied from the air pipe 1. The solid contaminant-suspended water sucked by the diaphragm pump 2 is pumped to the cyclone 6, where it is separated into solid and liquid. A diaphragm valve 7 is provided at the discharge part of the cyclone 6, and this diaphragm valve mainly maintains the pressurization inside the cyclone 6 necessary to discharge the solid contaminants collected within the cyclone 6 through a discharge pipe 8. Let them rule. The end of the discharge pipe 8 of the collected solid contaminants is sent via a valve 9 to a treatment facility 10 (such as a storage tank or a filter).

Note that the amount of water flowing through the diaphragm pump 2 can be measured and detected from the heartbeat rate of the compressed air and the volume of the tympanic cavity. In addition, the pressure of the compressed air is approximately equal to the pump discharge pressure balanced through the diaphragm in the tympanic cavity, and the pressurization inside the cyclone 6 can be adjusted by the diaphragm valve 7, and both can be operated and controlled safely and reliably from a remote location. can.

The method of the present invention is as described above, and has the following effects.

(1) The bottom of the wide residual water tank can be freely partitioned into a narrow, endless waterway.

(2) Since the coarse particles of radioactive solid contaminants deposited at the bottom and corners of waterways can be washed away with a large amount of running water, even waterways with protrusions or irregularities on the bottom can be effectively decontaminated.

(3) Although there is a lot of circulating water, less waste water is needed, which reduces the burden of wastewater treatment.

(4) Coarse particles that tend to settle in waterways are separated using a collection device such as a cyclone, and fine particles can be reused as circulating water while remaining suspended in water.

(5) The coarser the radioactive solid contaminants, the larger their mass and the greater the contribution of radioactivity.
By preferentially collecting coarse particles using the method of the present invention, the dose environment can be rapidly improved.

(6) The method of the present invention becomes even safer and more reliable if the characteristics of a diaphragm pump are used to remotely detect and remotely control the flow rate and pressure. However, if other pumps are operated with the suction and discharge directions in exactly the opposite direction, the decontamination effect will be as high as that of a diaphragm pump).

(7) When the method of the present invention is used for preliminary decontamination of areas exposed to high doses, the doses can be quickly and reliably reduced.
If necessary, it allows for free and technical options for precision decontamination of the finish and provides easy access to the object.

[Brief explanation of the drawing]

FIG. 1 shows a waterway formed using removable partitions installed at the bottom of a wide residual water tank of a nuclear reactor facility, and a method of arranging a waterway decontamination device installed in the waterway. Second
The figure shows an example of an apparatus for carrying out a waterway decontamination method. In the figure: A... Waterway decontamination device, 1... Air pipe, 2... Diaphragm pump, 3... Water in the waterway, 4... Water suction pipe, 5... Discharge pipe, 6... Cyclone, 7... Diaphragm valve, 8...Discharge pipe, 9
... Valve, 10 ... Treatment equipment, 11 ... Arrow (indicating the direction of water flow), 12 ... Solid contaminant, 16 ...
…partition.

Claims (1)

[Claims] 1. A removable partition 16 is provided at the bottom of the wide residual water tank of the reactor equipment to form a narrow endless waterway at the bottom of the tank, and a water intake pipe 4 and a discharge pipe 5 are installed in the waterway.
A waterway decontamination device A, which is equipped with a pump whose openings are oriented in opposite directions and whose openings are submerged in water, and a solid-liquid separator 6 attached to the pump, is installed, and water discharged from the pump is placed in the endless waterway. unidirectional water flow 1
A method for collecting solid contaminants deposited on a wide tank bottom of a nuclear reactor facility, characterized in that the solid contaminants 12 deposited on the tank bottom are moved and collected by suction.