JPH028800A - Radioactive liquid container - Google Patents

Abstract

PURPOSE:To intend shortening of working period for a periodical inspection and the like and to intend to diminish the exposure of personnels by providing a lining coated with a non-adhesive material at a surface with which a stored liquid in a container contacts. CONSTITUTION:On surfaces of concrete inner walls of a nuclear reactor well 2, a fuel storage pool 3 and an equipment and materials storage pit 4 belonging to a nuclear reactor 1, a lining 7 of stainless steel plates is provided and moreover a rubber sheet 7 coated with a non-adhesive material 8 is plastered. With this process, when the reactor 1, the well 2, the pool 3 and the pit 4 are filled with water during a refueling work and the like, radioactive materials do not easily stick to them. Consequently, as for a decontamination and a washing after draining, an enough decontamination can be accomplished by a water spray added with a water jet and the same sort of simple works therewith working period can be shortened and the exposure of personnels can be diminished as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to containers such as storage tanks for radioactive liquids generated, for example, in nuclear power plants.

(Prior Art) Conventionally, in nuclear power plants and other nuclear power plants, fuel has been replaced during periodic inspections. The reactor well 2, fuel storage pool 3, and equipment storage pit 4, which are lined with stainless steel plates on the inner surface of the concrete wall provided at the top of the reactor 1, are filled with water 5, and the top cover of the reactor 1 is removed. The inside of the tank is also filled with water 5, and the fuel is moved in the water to cool the fuel and reduce the radiation dose to the workers. However, although pure water is used as water 5 to fill the reactor well 2, etc., the radioactive crud, etc. that were in the reactor 1 are mixed during fuel exchange work and convection of water 5, and the reactor well 2 is filled with pure water. The entire second class is contaminated with radioactivity. For this reason, the entire wetted surface of the stainless steel plate lining on the inner surface of the reactor well 2, fuel storage pool 3, and equipment storage pit 4, which is the area in contact with water 5, should be cleaned at the water center after the fuel exchange operation. It is necessary to decontaminate the area. This decontamination work involves brushing the walls and bottom surfaces by a large number of workers, and in addition to this, water spraying is used for cleaning.

(Problem to be solved by the invention) For example, in the case of a nuclear reactor well, etc., the wall surface of the wetted surface that is subject to decontamination is generally about 10 meters deep, and together with the bottom surface, the working area is large, so decontamination using a recently developed electric brush is required. Even if work efficiency is improved by using a decontamination/washing machine, the process usually takes more than four days because the work is also in a radioactively contaminated area, and decontamination is also required after using the decontamination/washing machine. Improvements have been requested in both of these areas, as they are one of the obstacles to shortening the process of regular inspections and reducing worker burden.

The present invention has been made in view of the above, and its purpose is to prevent the adhesion of radioactive substances and liquids and decontaminate them by providing a coating made of a material to which radioactive substances and liquids do not easily adhere to the inner surfaces of nuclear reactor wells, etc. The object of the present invention is to provide a radioactive liquid container that is easy to clean, shortens working time, and reduces radiation exposure to workers.

[Structure of the Invention] (Means to be Solved by the Invention) The surface of the lining provided on the inner surface of the container is coated with a non-adhesive material.

(Function) Radioactive liquids or liquids mixed with radioactive substances are difficult to adhere to non-adhesive coatings, so brushing is recommended during decontamination work as radioactive substances and liquids are removed as the water is pumped out. This eliminates the need for decontamination and cleaning, and allows for easy decontamination and cleaning by cleaning with water spray, including jet water, which shortens work time and reduces the amount of radiation exposure for workers.

(Example) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of the vessel wall, and FIG. 3 is a sectional view of the main parts of the reactor building.

As shown in FIG. 3, the inner walls of the reactor well 2, fuel storage pool 3, and equipment storage pit 4 installed in the upper part of the reactor 1 are covered with stainless steel plates on the surface of the concrete wall 6, as shown in FIG. A lining 7 is applied, and a rubber sheet 9 coated with a non-adhesive material 8 (for example, fluororesin) is attached to the surface of the lining 7. A special rubber sheet coated with a non-adhesive material is KA sheet (manufactured by Japan Synthetic Rubber Co., Ltd.).

According to the above configuration, even if the reactor well 2, fuel storage pool 3, and equipment storage pit 4, including the reactor 1, are filled with water 5 during fuel exchange of the reactor 1, radioactivity will not be released on the inner surface. The contaminated water or the radioactive substances mixed in the water 5 are difficult to adhere to. Therefore, sufficient decontamination can be achieved by simply sprinkling water with water jets for decontamination cleaning after water removal. For this reason, when the inner surface of the reactor well 2, etc. is exposed from the water one after another during the water pumping process, if the newly exposed parts are cleaned, the bottom surface can be cleaned when the water pumping is completed. Since the decontamination of the wall surface is completed, there is no need for equipment such as brushing or electric brushes, the work period can be shortened to about two days, and the amount of radiation exposure for workers can also be reduced.

The vertical cross-sectional view of the container wall in FIG. 2 shows an embodiment of the present invention, and the lining 7 applied to the concrete wall 6 is coated with a paint containing a non-adhesive material in advance at high temperature on the surface of, for example, a stainless steel plate. A material coated with a non-adhesive material 10, for example Fungy Color (manufactured by Kawasaki Steel Corporation), is used. The operation and effect are similar to those of the previous embodiment.

Although the above description has been made of a reactor well installed at the top of a nuclear reactor for fuel exchange, the application of the present invention is not limited to this, and can also be applied to tanks of radioactive waste processing equipment in nuclear reactors. Of course, similar actions and effects can be obtained by doing so.

[Effects of the Invention] As described above, according to the present invention, the decontamination and cleaning work of containers for storing radioactive liquids or liquids mixed with radioactive substances is facilitated, and moreover, special equipment is not required and the work time is reduced. This has the effect of shortening periodic inspection periods and reducing radiation exposure for workers.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a vessel wall according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a vessel wall according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a main part of a reactor building. 6... Concrete wall 7... Lining 8...
- Non-adhesive material 9...Rubber sheet 10...Non-adhesive material coating. Agent Patent Attorney Norio Ogo

Claims (1)

[Claims] 1. A radioactive liquid container for storing a radioactive liquid or a liquid mixed with a radioactive substance, the container comprising a lining in which the surface in contact with the stored liquid is coated with a non-adhesive material.