JP5365877B2 - Demolition method of concrete structure - Google Patents

Description

  The present invention relates to a method for demolishing a concrete structure. For example, the present invention relates to a method for demolishing a concrete structure suitable for a concrete structure constituting a biological shielding wall of a nuclear facility.

  A concrete structure that constitutes a biological shielding wall of a nuclear facility that has become a decommissioning furnace has a part that can be treated as radioactive waste and a part that can be treated as general waste. When dismantling this concrete structure, the part to be treated as radioactive waste is divided into multiple blocks by cutting it from multiple directions, and then the part that can be treated as general waste is blown up, crushed, etc. By doing so, it is supposed to be dismantled (for example, see Patent Document 1).

  By the way, the method of dismantling the concrete structure that cuts the part to be treated as radioactive waste and the part that can be treated as general waste in a lump, and then cuts it for each radioactivity level in a separate shredding area is considered. Has been. For cutting concrete structures, the use of a wire saw device that wraps the wire with diamond beads wrapped around the cutting point and circulates the wire is being considered, but the wire saw device prevents seizure of diamond beads. In order to do so, it is necessary to pour cooling water into the cutting site.

JP 2005-83923 A

  However, when the part to be treated as radioactive waste and the part that can be treated as general waste are cut together, the waste liquid mixed with the radioactive dust in the cooling water penetrates into the part that can be treated as general waste, Sites that can be treated as general waste are secondarily contaminated.

  The present invention has been made in view of the above, and when a part to be treated as radioactive waste and a part that can be treated as general waste are cut together, a secondary of the part that can be treated as general waste. An object of the present invention is to provide a method for demolishing a concrete structure that prevents contamination.

  In order to solve the above-described problems and achieve the object, the present invention supplies cooling water to a cutting site spanning a site to be treated as radioactive waste and a site that can be treated as general waste, and the radioactive waste In a dismantling method for a concrete structure in which a part to be treated as a waste and a part that can be treated as a general waste are collectively cut, the cooling water is managed so as to be alkaline.

  Moreover, the present invention is characterized in that, in the method for dismantling a concrete structure, the cooling water is controlled so that the pH value thereof becomes 11-13.

  Moreover, the present invention is characterized in that, in the method for dismantling a concrete structure, the concrete structure is a biological shielding wall of a nuclear facility.

  Since the concrete structure dismantling method according to the present invention is controlled so that the cooling water becomes alkaline, even if the dust activated by cutting the site to be treated as radioactive waste is eluted into the cooling water, the radioactive material is radioactive. The material precipitates as a hydroxide salt. Therefore, the situation where the radioactive cooling water permeates the site that can be treated as general waste is avoided, and secondary contamination of the site that can be treated as general waste can be prevented.

FIG. 1 is a conceptual diagram showing a biological shielding wall of a nuclear facility to which a concrete structure dismantling method according to an embodiment of the present invention is applied. FIG. 2 is a process diagram showing a concrete structure dismantling method according to an embodiment of the present invention. FIG. 3 is a conceptual diagram showing a cutting process of the concrete structure shown in FIG.

  Embodiments of a concrete structure disassembling method according to the present invention will be described below in detail with reference to the drawings. Here, a method for demolishing a concrete structure constituting the biological shielding wall W of the nuclear facility will be described as an example, but the present invention is not limited to this embodiment.

  FIG. 1 is a conceptual diagram showing a biological shielding wall of a nuclear facility to which a concrete structure dismantling method according to an embodiment of the present invention is applied.

  As shown in FIG. 1, the concrete structure 1 which comprises the biological shielding wall W has the cylindrical shape in which the storage chamber R which accommodates a nuclear reactor was defined. The inner peripheral portion 10 of the concrete structure 1 constituting the living body shielding wall W is activated by the time of dismantling. The radioactivity level of the concrete structure 1 constituting the biological shielding wall W gradually decreases from the inner peripheral side toward the outer peripheral side. The inner peripheral portion 10 of the concrete structure 1 constituting the biological shielding wall W is an L2 level corresponding to a relatively low radioactive level, and the outer peripheral portion 20 corresponds to a CL that does not need to be treated as a radioactive substance. Is a level. Moreover, the center part 30 pinched | interposed into the inner peripheral part 10 and the outer peripheral part 20 is L3 level to which the thing with an extremely low radioactivity level corresponds. The inner peripheral portion 10 at the L2 level and the central portion 30 at the L3 level need to be treated as radioactive waste, and the outer peripheral portion 20 at the CL level can be treated as general waste.

  Moreover, the free water filled in the capillary space | gap of the surface area of the concrete structure 1 which comprises the biological shielding wall W evaporates and reduces by being exposed to air. For this reason, water permeates into the surface area of the concrete structure 1. On the other hand, the capillary space in the inner area of the concrete structure 1 constituting the living body shielding wall W is filled with free water. For this reason, it is difficult for water to penetrate into the surface area of the cut surface obtained by cutting the concrete structure 1.

  FIG. 2 is a process diagram of a concrete structure disassembling method according to an embodiment of the present invention, and FIG. 3 is a conceptual diagram showing a concrete structure cutting process shown in FIG.

  The concrete structure 1 constituting the living body shielding wall W is disassembled by cutting the concrete structure 1 constituting the living body shielding wall W in a lump, and then performing radioactivity in a separate shredding area (not shown). Shred by level.

  As shown in FIG. 2, the dismantling method of the concrete structure 1 constituting the biological shielding wall W includes a painting process (step S1), a collective cutting process (step S2), and a shredding process (step S3). .

  The painting process (step S1) is a process of painting a penetration preventing material that prevents the penetration of water on the surface of a site that can be treated as a general waste. The site that can be treated as general waste is the outer peripheral portion 20 at the CL level, and the surface of the site that can be treated as general waste is the outer peripheral surface 20A. The permeation preventive material may be any material that can prevent water permeation from the concrete surface. For example, an epoxy-based paint is used. The coating is not particularly limited as long as it forms the penetration preventing film 21 on the concrete surface, and any method such as spraying or coating can be employed.

  In this way, the outer peripheral surface 20A on which the permeation preventing coating 21 is formed is prevented from permeating water, and even if water adheres, the water does not permeate from the outer peripheral surface 20A.

  The collective cutting process (step S2) is a process of cutting a part to be treated as radioactive waste and a part to be treated as general waste in a lump. The parts to be treated as radioactive waste are the inner peripheral part 10 having the radioactivity level L2 and the central part 30 having the L3 level, and the parts to be treated as general waste are the outer peripheral part 20 having the CL level. Further, the size of the block obtained as a result of batch cutting is determined in consideration of handling.

  As shown in FIG. 3, a wire saw cutting device 4 is used for the collective cutting step (step S2). The wire saw cutting device 4 winds a wire 41 fitted with diamond beads around a cutting portion, and circulates the wire 41 to cut it. The wire saw cutting device 4 includes a main pulley 42 that circulates the wire 41, a guide pulley 43 that guides the wire 41, and a tension device 45 that applies a constant tension to the wire 41.

  Further, at the time of cutting, by supplying cooling water to the cutting site, the diamond beads are prevented from seizing, cutting noise is suppressed, and generation of dust is suppressed.

  The cooling water is controlled to be alkaline. Specifically, it is managed so that the pH value of the cooling water becomes 11 to 13 (strong alkali). The management is performed, for example, by a tank (not shown) storing cooling water, and the cutting water is supplied with cooling water having a pH value of 11 to 13.

For this reason, while supplying cooling water to the cutting | disconnection site | part straddling the inner peripheral part 10 and the center part 30 processed as a radioactive waste part, and the outer peripheral part 20 which can be processed as a general waste, the inner peripheral part processed as a radioactive waste part When 10 and the central part 30 and the outer peripheral part 20 that can be treated as general waste are cut together, the activated dust is mixed with the cooling water and becomes waste liquid. Radioactive substances (eg, europium, cobalt) contained in the activated dust generate OH ^- ions and hydroxide salts (europium hydroxide, cobalt hydroxide) with alkali-controlled cooling water. Precipitate. Even if these deposited substances adhere to the outer peripheral surface of the outer peripheral portion 20, they do not permeate from the outer peripheral surface 20A. Therefore, even if the deposited substance adheres to the outer peripheral surface 20A, secondary contamination is avoided by washing with water.

  When cutting, in order to prevent the diffusion of dust, the cutting portion of the concrete structure 1 constituting the living body shielding wall W and the wire saw cutting device 4 are covered with the portable barrier 5.

  The shredding step (step S3) is a step of cutting each radioactivity level in a shredding area (not shown) provided separately. In this step, the radiation level is divided into an inner peripheral portion 10 having an L2 level, a central portion 30 having an L3 level, and an outer peripheral portion 20 having a CL level. An arbitrary cutting device such as the wire saw cutting device 4 described above is used for the shredding step (step S3).

  Since the dismantling method of the concrete structure 1 which is embodiment of this invention mentioned above manages cooling water so that it may become a strong alkali, it cut | disconnects the inner peripheral part 10 and the center part 30 which are processed as radioactive waste. Even if the dust activated by the elution is eluted in the cooling water, the radioactive substance is deposited as a hydroxide salt (for example, europium hydroxide, cobalt hydroxide). Therefore, the situation where the cooling water having radioactivity penetrates into the outer peripheral portion 20 that can be treated as general waste is avoided, and secondary contamination of the outer peripheral portion that can be treated as general waste can be prevented.

  In addition, after forming a permeation preventing coating 21 on the outer peripheral surface 20A of the outer peripheral portion 20 that can be treated as general waste with an epoxy-based paint that prevents water penetration, the inner peripheral portion 10 and the central portion that are treated as radioactive waste 30 and the outer peripheral portion 20 that can be treated as general waste are cut at once, so that waste liquid mixed with dust, hydroxide salt, and cooling water may adhere to the outer peripheral surface 20A of the outer peripheral portion 20. It does not penetrate from the outer peripheral surface 20A. Therefore, even if the waste liquid adheres to the outer peripheral surface 20A of the outer peripheral portion 20, the secondary contamination of the outer peripheral portion 20 that can be treated as general waste can be prevented by washing with water.

  Further, the precipitated hydroxide salt (for example, europium hydroxide, cobalt hydroxide) can be removed at the same time when sludge is removed from the waste liquid, and the radioactivity level of the waste liquid can be greatly reduced. Further, the removed hydroxide salt can be reused.

DESCRIPTION OF SYMBOLS 1 Concrete structure 10 Inner peripheral part 20 Outer part 20A Outer peripheral surface 21 Permeation prevention coating 30 Center part 4 Wire saw cutting device 41 Wire 42 Main pulley 43 Guide pulley 45 Tension device 5 Portable barrier W Biological shielding wall R Containment chamber

Claims (3)

Cooling water is supplied to a cutting part that spans a part that is treated as radioactive waste and a part that can be treated as general waste, and the part that is treated as radioactive waste and the part that can be treated as general waste are collectively In the method of dismantling concrete structures to be cut,
A method for demolishing a concrete structure, wherein the cooling water is managed so as to be alkaline.   The method for demolishing a concrete structure according to claim 1, wherein the cooling water is controlled to have a pH value of 11 to 13.   The method for dismantling a concrete structure according to claim 1 or 2, wherein the concrete structure is a biological shielding wall of a nuclear facility.

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