JP2012233695A - Radioactive substance removal apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve simple means for decontaminating grass without cutting grass and/or changing soil when a pasture or the like is radioactively contaminated and allowing an easy processing of removed radioactive substances while preventing operators from being exposed to radiation while they are at decontamination work.SOLUTION: Radioactive substances wiped off by a rotary brush and a blowing air of a radioactive substance removal apparatus are sucked with the air by an air blower of the apparatus. The sucked air passes through the water in a water tank and is accumulated in an air layer in the upper part of the tank. While passing through the water, the radioactive substances are collected by the water. The air accumulated in the air layer is pushed out by a pressure to be blown towards the ground surface. By being blown, the air is sucked again. Thus, as a so-called closed circuit is structured, the radioactive substances are not leaked out of the apparatus.

Description

  The present invention relates to a radioactive substance removing apparatus.

  When pastures are radioactively contaminated due to the scattering of radioactive materials resulting from an accident at a nuclear power plant, the radioactive materials accumulate in the livestock due to grazing, resulting in radioactive contamination of meat and milk. The If meat or milk contaminated in this way is ingested, a person will be exposed to internal radiation exposure, resulting in serious radiation exposure injury. For example, in the current Chernobyl nuclear power plant accident in Ukraine, about 4,000 children have developed childhood thyroid cancer due to ingestion of cow's milk ingested radiation-contaminated grass (according to IAEA research report). ).

  Thus, when pastures and the like are radioactively contaminated, conventionally, there has been no choice but to abandon the pastures or otherwise cut all the pastures and replace the soil if necessary. Pastures are generally vast and require a huge amount of work to mow all the grass or replace the soil. In addition, since the cut grass and the removed soil itself are radioactively contaminated, there arises a problem of how to deal with it.

  As a conventional technique for removing radioactive substances, a method and an apparatus for removing radioactive substances in the air (for example, see Patent Document 1) are known. In addition, a method and an apparatus for removing radioactive substances in water (for example, see Patent Document 5) are known. However, none of these techniques are intended to remove radioactive material deposited on the ground surface, and are inconvenient for decontaminating a wide range of pastures.

  Patent Documents 2 and 4 both disclose a technique for collecting dust collected by passing water through a vacuum cleaner. By using water as a filter, it is possible to collect fine particles that are difficult to collect with ordinary air filters, but these are technologies intended for indoor cleaning, and even when used outdoors, even non-radioactive soil and grass. Because it sucks, it was not suitable for decontamination of the outdoor ground surface such as pasture.

  Patent Document 3 discloses a technique for removing radioactive substances in the air using an extremely fine air filter such as a HEPA filter. This is a technique for removing radioactive materials in the air in a space shielded from the surroundings such as a clean house or a glove box, and it is also not suitable for decontamination of the outdoor ground surface.

JP 2005-10013 A JP 2000-316765 A JP 2001-174586 A Japanese Utility Model Publication No. 7-25921 JP 2005-177709 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is to decontaminate the grass without cutting the grass or replacing the soil when the grassland is radioactively contaminated. The purpose of the present invention is to find a simple means in which the treatment of the removed radioactive substance is simple and the worker is not exposed during the decontamination work.

  In the present invention, a watertight water tank and a blower are mounted on a vehicle body towed by a tractor or the like. The blower is driven by electric power or hydraulic pressure from the tractor. The radioactive material sucked by the blower passes through the water in the water tank and moves to the air layer above the water tank. The air pressure in the air layer above the water tank becomes high, and the air pushed out by this pressure is discharged toward the ground.

  By passing through the water tank, radioactive material is adsorbed by the surface tension of the water. On the other hand, although the radioactive material which could not be removed with water remains in the air discharged by the blower, it is discharged toward the ground near the suction port. The exhaled air is sucked again. In other words, since a closed circuit is configured, the amount of radioactive material leaked to the outside is extremely small.

  In addition to the method of using water, there is a method of collecting radioactive substances with an air filter. The size of radioactive material particles scattered by the nuclear accident varies, but the particles that are carried by the wind to reach a long distance are mainly fine particles with a particle size of about 0.3 to 1.0 μm. A sufficiently fine filter, such as a so-called HEPA filter or ULPA filter, is effective.

  According to the present invention, when pastures and the like are radioactively contaminated, the grass is decontaminated without removing the grass or replacing the soil, the treatment of the removed radioactive material is simple, and during the decontamination work A simple means that workers do not expose was realized.

FIG. 1 is an explanatory view showing a method of implementing the radioactive substance removing apparatus. Example 1 FIG. 2 is an explanatory view showing a method of implementing the radioactive substance removing apparatus. (Example 2) FIG. 3 is an explanatory view showing a method for carrying out the radioactive substance removing apparatus. (Example 3) FIG. 4 is an explanatory view showing a method for carrying out the radioactive substance removing apparatus. Example 4

  The chassis is supported by wheels. Four wheels are stable and best, but three wheels are also acceptable. Since there are many cases where a tractor is held in a ranch or the like, the chassis is best pulled by a tractor or the like. The chassis is equipped with a water-tight water tank. The tank is filled with water so that an air layer is formed at the top. Normal water is used as the water, but an adsorbent such as nickel ferrocyanide which increases the removal rate of radioactive cesium may be mixed. The water tank is provided with a water inlet and a drain. The airtightness of the entire tank is increased so that air does not leak out and scatter radioactive material. Therefore, the water inlet is opened and closed with a highly airtight cap. Opening and closing stool is attached to the drain, and drains when necessary.

  A blower is mounted on the chassis or water tank. A centrifugal type so-called sirocco fan is desirable as the blower because the pressure loss is high in order to pass water, but an axial fan, a cross flow fan, or a turbo fan may be used. The drive of the blower is preferably a hydraulic pump type using hydraulic pressure from a tractor or the like, but may be driven by an electric motor. Supply of electric power to the electric motor may be supplied from a tractor or the like, or electric power from an engine generator mounted separately may be used. The horsepower of the blower is determined in consideration of the overall size of the apparatus, but in order to increase the suction force, it is desirable to mount a horsepower as large as possible.

  An air inlet that sucks in air is installed at the bottom of the chassis. The shape and dimensions of the air inlet are determined by the balance between the overall size of the device and the capacity of the blower. However, if the air inlet is too far away from the ground or the air suction speed is too slow, the air cannot be sucked. Further, if the wind speed in the intake pipe is too slow, the radioactive fine particles cannot be carried. According to the results of the experiment, the lower limit of both the air suction speed and the wind speed in the intake pipe was 2 meters per second, and about 5 meters per second was good. A pre-filter is installed in front of the intake port. The purpose of the prefilter is to remove coarse dirt, not to remove radioactive material. Therefore, as a prefilter, those with too fine eyes are clogged immediately and are inconvenient, so it is desirable that the prefilter is coarse and has a high dust collecting ability. A plurality of prefilters having different eye roughness may be combined.

  The wind from the blower is guided to the bottom of the water tank through the blower pipe and discharged into the water from the discharge port. The discharge port may be cut off from the pipe, but it is preferable to disperse the air as much as possible so that the radioactive substance can be adsorbed to water, so that a so-called air diffuser tube having many fine holes is desirable.

  The air in the air layer in the upper part of the tank is pushed out and blown out from the outlet through the outlet pipe toward the ground. The shape of the air outlet is not particularly defined, but it is designed to blow out as much as possible toward the ground. According to experiments, wind speeds of around 5 meters per second are considered best because the fan's back pressure is low for a strong momentum. The direction in which the air is blown out is most preferably a shape in which the blown air is reflected from the ground and travels toward the intake port.

  A flexible skirt is attached to the lower part of the chassis. This skirt is installed so as to cover the entire circumference of the lower part of the chassis and to contact the ground. By doing so, the gap between the skirt and the ground is made as narrow as possible. By narrowing the gap, the speed of air passing through the gap is increased. The higher the speed of air, the higher the efficiency of inhaling radioactive material. The skirt is preferably a thin resin, but may be a brush in some cases.

  If the wind speed from the outlet cannot be obtained sufficiently due to the restriction of the output of the blower, etc., it is possible to provide an exhaust port instead of the outlet pipe as shown in FIG. Good. In this case, it is desirable to provide a fine filter such as a HEPA filter at the exhaust port in order to prevent radioactive substances that could not be removed by water from being exhausted into the atmosphere.

  The embodiment of FIG. 3 is provided with a brush that rotates in front of the lower portion of the chassis, that is, in the direction of the towing vehicle, in addition to the radioactive substance removing device of the first embodiment. The radioactive material adhering to the surface of grass or the like is scattered by the rotation of the brush. The brush may be a so-called brush in which fine hairs of nylon or natural hair are radially planted, but a softer one such as a fluffy hair is preferable so that grass and the like are not shredded.

  The embodiment of FIG. 4 is a radioactive substance removing device that collects radioactive substances using an air filter. Instead of the water tank shown in Examples 1 to 3, an airtight casing having an air filter is provided. Air sucked from the air inlet is introduced into the casing and passes through the air filter. In order to collect fine radioactive substances, the air filter uses a fine filter such as a so-called HEPA filter that collects 0.3 μm particles and a ULPA filter that collects 0.15 μm particles. These filters may be combined with an activated carbon fiber filter. The air cleaned by the air filter is pushed out from the blower and blown out from the blowout outlet toward the ground via the blowout pipe. The direction in which the air is blown out is most preferably a shape in which the blown air is reflected from the ground and travels toward the intake port.

  The radioactive substance removing apparatus according to the present invention is mainly used for the purpose of removing radioactive substances from the surface of the grass on which radioactive substances scattered by an accident at a nuclear power plant have been deposited. It can be used to remove radioactive materials even on ground and roads.

DESCRIPTION OF SYMBOLS 1 Chassis 2 Traction tool 3 Water tank 4 Water injection port 5 Drainage port 6 Wheel 7 Blower 8 Drive means 9 Intake port 10 Intake pipe 11 Discharge port 12 Blower pipe 13 Prefilter 14 Outlet 15 Outlet pipe 16 Brush 17 Rotating means 18 Skirt 19 Casing 20 Air filter 21 Exhaust port

Claims (6)

A chassis 1, a traction tool 2 provided rotatably in the chassis, a watertight water tank 3 mounted on the chassis, an openable and closable water inlet 4 provided in the upper part of the water tank, and provided in the lower part of the water tank Openable and closable drainage port 5, a plurality of wheels 6 for supporting the chassis, a blower 7 mounted on the chassis or the water tank, a driving means 8 for driving the blower, and a lower portion of the chassis. An intake port 10, an intake pipe 10 connecting the intake port and the suction port of the blower, a discharge port 11 provided at the bottom of the water tank, a blower pipe 12 connecting the discharge port and the blower port of the blower, the intake air A pre-filter 13 attached to the mouth, an air outlet 14 installed toward the ground at the bottom of the chassis, and an air outlet pipe connecting the air outlet and the air layer above the water tank 5, the radioactive substance remover consisting of the chassis lower portion of the front and rear left and right flexible steel installed in the skirt 18. The radioactive substance removing apparatus according to claim 1, wherein the radioactive substance removing apparatus is provided with an exhaust port 20 instead of the outlet 14 and the outlet pipe 15. 3. The radioactive substance removing device according to claim 1, further comprising: a brush 16 rotatably supported at a lower portion of the chassis; and a rotating means 17 for driving the brush. Chassis 1, traction tool 2 rotatably provided on the chassis, an airtight casing 19 mounted on the chassis, a plurality of wheels 6 for supporting the chassis, and a blower 7 mounted on the chassis or the casing , Driving means 8 for driving the blower, air inlet 9 provided in the lower part of the chassis, pre-filter 13 attached to the air inlet, air filter 20 mounted on the casing, toward the ground at the lower part of the chassis A radioactive substance removing device comprising an installed outlet 14 and flexible skirts 18 installed at the front, rear, left and right of the lower portion of the chassis. 5. The radioactive substance removing device according to claim 4, further comprising: a brush 16 rotatably supported at a lower portion of the chassis; and a rotating means 17 for driving the brush. The radioactive substance removing device according to any one of claims 1 to 5, wherein the radioactive material removing device is self-propelled without a traction tool.

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