JP2007033348A - Shield made of concrete and its developing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shield made of concrete of complicated geometry which can prevent aluminium-alkali reaction and be used containing in a vacuum vessel. <P>SOLUTION: The inner surface of aluminium vessel 1 and aluminium lid 4 is provided with heat resistant layers 2 and 5 formed by spreading heat resistant paint. The aluminium vessel 1 is filled with concrete 3, so that the concrete 3 is dried at a constant temperature until it reaches a constant mass after drying in the air for a period. The aluminium vessel 1 and the aluminium lid 4 are air-tightly welded to seal at the opening for filling concrete 3 to constitute a shield body. A stainless steel hanging metal 9 penetrating the aluminium lid 4 and held in the concrete 3 is provided as need arises, and both inner surfaces of the aluminium vessel 1 facing each other are connected with reinforcing ribs 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shield installed around an apparatus that generates radiation in an accelerator facility, a neutron generation facility, a nuclear facility, and the like, and in particular, a concrete shield that is manufactured by filling concrete inside an aluminum container, and It relates to the production method.

  Generally, in high energy accelerator facilities, neutron generation facilities, and nuclear facilities, high-energy accelerated particle collision points and targets are protected around the human body from radiation generated from these facilities, or measurement equipment using radiation. In order to prevent interference with the steel, a shield made of concrete or steel is used.

  As this type of radiation shielding body, several shielding bodies that have been difficult to activate have been proposed. For example, an aluminum driven weir plate that is difficult to activate is used, and a short piece of lead is used instead of a steel ball or steel piece as the coarse aggregate, and this coarse aggregate is less likely to be activated. A shielding body having an aluminum driving dam plate integrated with a concrete structure, which is constructed by laying in a space defined by, and injecting and hardening mortar into this portion, has been proposed. (See Patent Document 1).

  In addition, a two-layer structure in which a low-activation alloy material such as an aluminum alloy that also serves as a formwork is disposed on one side and a molded panel that serves as a neutron absorption and shielding material such as boron is disposed on the inside. Further, a radiation shielding structure has been proposed in which an iron plate serving as a shielding material and a mold is used on the other surface, and a reinforcing bar is disposed in the space between the molded panel and the iron plate to place concrete. reference).

  By the way, in Non-Patent Document 1, since the intensity of the particle beam to be used is large, the radiation and heat released from the collision point of the particle beam are large, and the vacuum duct for beam transportation arranged around the target is difficult to cool, It is described that devices such as electromagnets are stored in a vacuum container. Moreover, in the vacuum vessel, in addition to the electromagnet and other devices, a shielding block for shielding the radiation generated from the collision point of the particle beam and the target is housed, and this shielding block is made of iron on the lower side and on the upper side. Made of concrete. The concrete shielding block is made by filling concrete in an aluminum container, which is a low activation material, in order to reduce the emitted gas. Moreover, since concrete is alkaline, it reacts with aluminum to generate hydrogen. It is described that an appropriate treatment must be applied to the inner surface of the aluminum container in order to prevent the occurrence of this.

  Since calcium hydroxide, which is the main component of concrete, is strongly alkaline, when it comes into contact with aluminum, as is well known, hydrogen gas is generated by the aluminum-alkali reaction represented by the following reaction formula, and aluminum is corroded. There is a problem.

2Al + Ca (OH) ₂ + 2H ₂ O → CaAl ₂ O ₃ + 3H ₂ ↑
The property that aluminum generates hydrogen gas by alkali corrosion is used as a non-shrink mortar by putting aluminum powder or the like as an expansion material.

  Normally, during the solidification process in which various solid waste generated from nuclear power plants is poured into drums, the metal aluminum in the solid waste corrodes with the alkali of the solidification material, so it is solidified with hydrogen gas generated during the corrosion. Improvement measures are taken to prevent voids from forming in the material and adversely affecting the strength of the solidified material. For example, on the surface of the metal aluminum, particularly suitable for temperature control when generating a protective coating that is lithium aluminate or a double salt of lithium aluminate and aluminum hydroxide, thereby suppressing alkali corrosion of the metal aluminum, It has been proposed that generation of hydrogen gas can be suppressed (see Patent Document 3).

In addition, when using a lightweight aluminum material for the outer plate of an automobile body, an anionic water-based urethane resin or lubricant powder is formed on the surface of the aluminum material in order to make the aluminum material excellent in moldability and chemical processing properties. It has also been proposed to have excellent alkali resistance by applying an aqueous coating composition containing silica particles, a silane coupling agent, and water as main components (see Patent Document 4). .
Furthermore, although it is a composite structure of steel and concrete, zinc, aluminum, manganese and an alloy mainly composed of these metals are used on the surface of the steel material to be used, and at least one of Mg and In is weight%. It is also proposed that the steel material has excellent corrosion resistance even in an alkaline corrosion environment or the like when a thin alloy coating layer containing 0.05% or more and 10% or less is formed (see Patent Document 5). ).

JP 2000-88995 A Japanese Patent Publication No. 6-77067 JP-A-8-179097 JP 7-331171 A Japanese Patent Laid-Open No. 11-158657 KEK Internal 2004-3 July 2004 A / H / M / R / D "J-PARC High-Intensity Proton Accelerator Facility Nuclear Elementary Particle Experiment Facility Construction Group Hadron Beamline Subgroup Second Interim Report" Pages 103-111 page

  However, the conventional radiation shielding bodies such as Patent Documents 1 and 2 are structures intended to be used in the atmosphere, and have a problem that they cannot be used when placed in a vacuum environment. In addition, when filling the aluminum container with concrete, in order to prevent an aluminum-alkali reaction, the surface treatment and the treatment to ensure waterproofness shown in Patent Documents 3 to 5 may be performed, but when used in a radiation environment, Patent Documents 3 and 4 and a protective coating formed with a waterproof paint that is generally available on the market may change in quality and the functions such as waterproofness may be lost. Therefore, it is necessary to advance the dried state to a state called absolutely dry, in which the filled concrete is dried to a constant weight at a constant temperature according to JASS 5N T-602 “Drying unit volume mass acceleration test method of concrete” There is.

  Furthermore, in order to use an aluminum container filled with concrete in a vacuum atmosphere, it is necessary to weld and seal a lid to the opening of the aluminum container. For this reason, the waterproof treatment applied to the inner surface of the aluminum container must withstand the thermal shock during welding, but the waterproof paints that are commercially available in Patent Documents 3 and 4 and generally withstand the thermal shock during welding, There is a problem that it is difficult to make without a pinhole. Note that the film described in Patent Document 5 is unclear in its effect as a film on an aluminum material.

  An object of the present invention is to provide a concrete shielding body having a complicated shape and a manufacturing method thereof, which can suppress alkaline corrosion of aluminum even when an aluminum container is used and can be disposed in a vacuum environment.

  The present invention constitutes a concrete shield by filling concrete in an aluminum container, and is provided with a heat-resistant coating layer formed by applying an inorganic paint excellent in heat resistance on the inner surface of the aluminum container, Similarly, the aluminum container is constructed by welding and sealing an aluminum lid having a heat-resistant coating layer on the inner surface.

  The concrete shield is manufactured by forming a heat-resistant coating layer with an inorganic paint with excellent heat resistance on the inner surface of the aluminum container, drying it thoroughly, and filling the aluminum container with a certain amount of concrete in advance. After air drying for a certain period of time, the concrete in the aluminum container is dried to a constant weight, and then the aluminum lid is coated with a heat-resistant paint on the inner surface to form a heat-resistant coating layer. It is manufactured by welding in a vacuum-tight manner. For drying the concrete to a constant weight, a heating furnace or vacuum drying is used.

If a concrete shield is configured as in the present invention, even when an aluminum container is filled with concrete, the alkaline corrosion of aluminum is suppressed, and the concrete can be placed in a vacuum environment and has a complicated shape. A shield body can be provided.
Moreover, according to the production method of the present invention, a concrete shield that can be stored and used in a vacuum container can be easily produced.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to specific examples.

  The concrete shielding body which is one Example of this invention is shown to Fig.1 (a) and (b). The aluminum container 1 is filled with concrete 3, and the concrete 3 is dried at a constant temperature until it reaches a constant weight after air drying for a certain period. This aluminum container 1 is sealed by welding an aluminum lid 4 to an opening for filling concrete 3 to constitute a shield. The inner surfaces of the aluminum container 1 and the aluminum lid 4 are coated with an inorganic paint having excellent heat resistance, which will be described later, to form heat-resistant coating layers 2 and 5, respectively. Prevent alkaline reactions.

  The aluminum lid 4 is provided with a stainless steel hanging bracket 9 which is held in the concrete 3 filled therethrough, and this hanging bracket 9 is also sealed with the aluminum lid 4 in a vacuum-tight manner. Then, it joins using the dissimilar material joint 10 of aluminum and stainless steel manufactured by the prior art. That is, the aluminum side of the dissimilar material joint 10 is joined by welding to the aluminum lid 4, and the stainless steel side of the dissimilar material joint 10 is joined to the stainless steel hanging bracket 9 by welding, so that vacuum-tightness can be achieved. For example, a hanging tool such as an eyebolt 11 is attached to the hanging bracket 9 and used when lifting the shield.

  Since the hanging metal fitting 9 held by the concrete 3 is provided, the aluminum container 1 and the aluminum lid 4 can be hung without giving a load even when hung and moved. For this reason, there also exists an advantage which can reduce the board thickness of aluminum and can raise the ratio of the concrete in a shield. The aluminum container 1 can also be made to connect the inner surfaces which oppose with the reinforcement rib 8, and to raise an intensity | strength.

  Next, an example of a heat-resistant coating layer forming experiment conducted by the present inventors will be described. An aluminum plate (A5052) 100 mm × 150 mm × 3 mm thickness was selected as the substrate. For inorganic paints with excellent heat resistance, water-based metal salt paints mainly composed of silica as the base material to be the first layer, and metal alkoxide paints mainly composed of silica as the top coat material to be the second layer These were applied in order to form the heat-resistant coating layer 2 and sufficiently dried. The paint applied to the aluminum plate of the substrate is heated from room temperature to 500 ° C. for 10 minutes using a muffle furnace, held at 500 ° C. for 10 minutes, naturally cooled to 200 ° C. in the muffle furnace, and then from the muffle furnace. The thermal shock of taking out and allowing to cool was given, and the pinhole test was implemented before and after the heating according to JIS G 5528-1984 “Epoxy resin powder coating in ductile cast iron pipe”.

As the above-mentioned base material, water-based metal salt-based paint S-1000 (manufactured by Nippon Sheet Laboratory Co., Ltd.) is applied at about 180 g / m ^2. Two layers of about 50 g / m ² were applied to each layer, and a coating without a pinhole that could generate a spark at a test voltage of 1000 V before and after heating could be obtained. These inorganic paints excellent in heat resistance are not limited to the above as long as they can withstand similar heating and thermal shock.

  An example of the process in the manufacturing method of the concrete shielding body of this invention is shown to Fig.2 (a) to (d). First, the aluminum container 1 processed and molded as shown in FIG. 2 (a) is coated with the above-described inorganic paint having excellent heat resistance to form the heat-resistant coating layer 2 and sufficiently dried. Next, as shown in FIG. 2B, the aluminum container 1 is filled with a certain amount of concrete 3, and then air-dried for a predetermined period, for example, about 4 weeks.

  As the mass per unit volume of the concrete 3 to be filled, a blend that can provide a predetermined shielding performance with a dry unit volume mass is selected. Here, the dry unit volume mass is the mass of the concrete per unit volume dried to a constant weight at a constant temperature according to JASS 5N T-602 “Dry unit volume mass acceleration test method of concrete”.

  The aluminum container 1 that has been subjected to air-drying curing is housed in the heating furnace 20 as shown in FIG. 2 (c), and the concrete becomes constant at a temperature of 100 ° C. or higher, for example, 105 ° C. ± 5 ° C. Continue to dry. After this drying, the aluminum lid 4 having the heat-resistant coating layer 5 formed by applying a heat-resistant coating on the inner surface side as shown in FIG. 2 (d) is vacuum-tightly welded to the aluminum container 1. By joining, a concrete shield that can be used even in a vacuum can be produced.

  In the manufacturing method described above, a heating furnace is used to quickly dry the concrete until it reaches a constant weight. However, instead of this, other means can be used. In addition, the concrete shield shown in this manufacturing method is not provided with reinforcing ribs that connect the inner surfaces facing each other of the aluminum container, or hanging metal fittings that pass through the aluminum lid and are held by the concrete 3. Can be produced in the same way.

  Another example of the process in the method for producing a concrete shield according to the present invention is shown in FIGS. Also in this example, in the steps of FIGS. 3A and 3B, the heat-resistant coating layer 2 is formed on the inner surface of the aluminum container 1 processed and molded similarly to FIG. Fill it with sufficient air-drying curing.

  Next, in order to close the opening part of the aluminum container 1, the heat-resistant coating layer 5 is formed on the inner surface side, and the aluminum lid 4 to which the port 6 for evacuating the inside is attached is shown in FIG. As described above, the aluminum container 1 is joined by vacuum-tight welding. A heater 21 is attached to the outside of the aluminum container 1 integrated with the aluminum lid 4 and covered with a heat insulating material 22. A vacuum pipe 23 is connected to the vacuum exhaust port 6, and a vacuum exhaust pump 25 is connected via a water trap or a cold trap 24. In this state, while the aluminum container 1 is heated from the outside using the heater 21, the inside of the aluminum container 1 is evacuated and vacuum drying proceeds.

  In order to prevent the water inside the concrete 3 from freezing due to a decrease in the temperature of the aluminum container 1 due to adiabatic expansion during evacuation, the capacity of the heater 21 is preferably capable of heating the aluminum container 1 to 100 ° C. or higher. However, it is sufficient even if it is the capacity | capacitance which can be heated to about 50-60 degreeC.

The water in the concrete 3 is removed by a water trap or a cold trap 24, but the vacuum exhaust pump 25 is preferably a vacuum exhaust pump of a type that does not use lubricating oil in order to exhaust moisture air. After the concrete 3 is dried to a constant weight, the vacuum exhaust port 6 is sealed with a plug 7 as shown in FIG. Even a concrete shield made by this manufacturing method can be manufactured by providing reinforcing ribs and suspension fittings as necessary, as in the second embodiment.
This vacuum drying method has an advantage that a concrete shield can be manufactured without preparing a large heating furnace which is a permanent facility when the size of the aluminum container 1 becomes large and cannot be put into the heating furnace 20. There is.

  An embodiment of the concrete shield of the present invention is shown in FIG. In this example, the aluminum container 1 without the hanging metal fittings is formed by connecting opposing inner surfaces with reinforcing ribs 8 such as stainless steel, and the other parts constitute a shield in the same manner as in the embodiment of FIG. ing. In this way, if the inner surfaces facing each other of the aluminum container 1 are connected to each other by the reinforcing rib 8, it is possible to suppress the aluminum container 1 from bulging and deforming due to the internal pressure in the vacuum atmosphere. Interference with a shield or the like can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the concrete shielding body which shows one Example of this invention, (a) is a longitudinal cross-sectional view, (b) is side sectional drawing. It is a schematic manufacturing-process figure of the manufacturing method of the concrete shield using the heating furnace which is one Example of this invention. It is a schematic manufacturing-process figure of the manufacturing method of the concrete-made shielding body which performs the vacuum drying which is the other Example of this invention. It is a schematic block diagram of the concrete shield which shows the other Example of this invention, (a) is a longitudinal cross-sectional view, (b) is side sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Aluminum container, 2, 5 ... Heat-resistant coating layer, 3 ... Concrete, 4 ... Aluminum lid, 6 ... Port, 7 ... Plug, 8 ... Reinforcement rib, 9 ... Hanging metal fitting, 10 ... Dissimilar material joint, 11 ... Eye bolt, 20 ... heating furnace, 21 ... heater, 22 ... heat insulating material, 23 ... vacuum piping, 24 ... trap, 25 ... vacuum exhaust pump.

Claims (7)

  In a concrete shield configured by filling concrete in an aluminum container, a heat-resistant coating layer formed by applying an inorganic paint excellent in heat resistance is provided on the inner surface of the aluminum container and the aluminum lid, A concrete shield characterized in that it is constructed by welding and sealing with an aluminum lid provided with a heat-resistant coating layer on the inner surface.   2. The heat-resistant coating layer according to claim 1, comprising a first layer of a base material of a water-based metal salt paint mainly composed of silica and a second layer of a top coat material of a metal alkoxide paint mainly composed of silica. A concrete shield filled with concrete.   2. The concrete shield according to claim 1, wherein the aluminum container is provided with reinforcing ribs that connect between the inner surfaces facing each other.   4. The concrete shield according to claim 1, wherein the aluminum lid is provided with a hanging fitting that extends to and holds the concrete in the aluminum container.   A heat-resistant coating layer is formed on the inner surface of the aluminum container with an inorganic paint having excellent heat resistance and sufficiently dried, and a predetermined amount of concrete is filled in the aluminum container to perform air-drying curing for a predetermined period. After that, the concrete in the aluminum container is dried to a constant weight, and then an aluminum lid having a heat-resistant coating layer formed by applying a heat-resistant coating on the inner surface side of the aluminum container is vacuum-tightly welded and joined. A method for producing a concrete shield characterized by the above.   6. The method for manufacturing a concrete shield according to claim 5, wherein the drying is performed at a predetermined temperature after the aluminum container is accommodated in a heating furnace until the concrete has a constant weight. A heat-resistant coating layer is formed on the inner surface of the aluminum container with an inorganic paint having excellent heat resistance and sufficiently dried, and a predetermined amount of concrete is filled in the aluminum container to perform air-drying curing for a predetermined period. After that, the aluminum container and an aluminum lid provided with a heat-resistant coating layer on the inner surface are joined by vacuum-tight welding, and a heater is attached to the outside of the aluminum container integrated with the aluminum lid and covered with a heat insulating material. A method for producing a concrete shield, wherein the aluminum container is vacuum-exhausted while the aluminum container is heated by a heater, and the concrete is dried to a constant weight, and then the aluminum container is sealed.

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