JPS6186690A - Method of preventing redioactive contamination of nuclear reactor pool, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) Pools such as reactor cavities and reactor wells are filled with water for nuclear fuel exchange in nuclear power plants, and during this period, It concerns the prevention of radioactive contamination.

(Prior Art) It has not been done in the past to cover reactor cavities, reactor wells, etc. with polysheet to prevent radioactive contamination during the filling period of pools.

Currently, decontamination after radioactive contamination is generally carried out rather than prevention of radioactive contamination, but due to high radioactivity, decontamination work once contaminated is extremely difficult.

(Problems to be Solved by the Invention) An object of the present invention is to prevent radioactive contamination of the pool floor and wall surfaces during the period of filling the pool with water, such as the reactor cavity and reactor well. Currently, decontamination of nuclear reactor pools, etc. is carried out manually using polishers, etc. This method requires re-decontamination four to five times, and the current situation is that a so-called human wave strategy is being used. The present invention aims at proactive contamination prevention rather than such decontamination.

(Means to solve the problem) Before filling the reactor cavity, reactor well, etc. with water, a weakly adhesive polysheet is laid on the pool floor and walls, and the surrounding area is covered with strong adhesive tape. By applying the water without any gaps, the aim is to prevent the pool floor and walls from coming into direct contact with radioactively contaminated water during the filling period.

After the nuclear fuel exchange, etc., the water is drained from the pool, and the contamination inside the pool is removed by removing the installed poly sheet after the water is drained.

(Embodiment of the invention) Referring to the figure, l is a polysheet with weak adhesiveness installed on a stainless steel surface such as a nuclear reactor cavity, and the four circumferences are fixed with tape 2 with strong adhesiveness. Prevent water from entering.

In this way, the walls and floor of the pool such as the reactor cavity are covered with a polysheet with low adhesiveness, then water is filled, the reactor fuel is replaced, etc., and once the replacement work is completed, the walls and floor are covered after water is drained. This removes and disposes of the poly sheet spread on the floor, which prevents the stainless steel surface of the pool from coming into contact with water during the filling period, and eliminates the need for decontamination work with clean water after water is drained. be.

When a polysheet with weak adhesiveness is installed on the stainless steel surface of a pool, its adhesive strength makes it adhere well to the stainless steel surface, and the amount of air taken in between the polysheet and the stainless steel when installing the polysheet increases the adhesiveness. Very little compared to other poly sheets.

This is convenient for installing polysheets in pools where high water pressure is applied.

We conducted a comparative experiment of laying polysheets with weak adhesiveness and polysheets without adhesiveness, and investigated the amount of high-pressure water infiltrating the pool between the polysheet and stainless steel, and found that the polysheets with weak adhesiveness The results showed that the amount of penetration was much smaller in the case of If the amount of air taken in during this installation increases, the amount of high-pressure pool water that permeates between the polysheet and the stainless steel increases, causing problems such as peeling of the installed polysheet and radioactive contamination at the location where the polysheet is installed. However, this problem does not exist because of the weak adhesive polysheet.

In addition, by pasting a poly sheet with strong adhesive tape around all four sides, it not only prevents the poly sheet from peeling off and water penetration while filling the pool with water, but also creates a strong adhesion between the strong adhesive tape and the stainless steel. It has the effect of filtering radioactively contaminated water that penetrates while being blocked.

(Effects of the invention) 1) After laying a poly sheet for preventing radioactive contamination in the reactor cavity, filling the cavity with water and performing work such as replacing fuel rods, draining the water and replacing the poly sheet, etc. At the ground level, we found that the radioactive contamination level before installing the polysheet and the radioactive contamination level after removing the polysheet after draining water from the reactor cavity were almost the same level, and had not increased at all. In other words, the pollution prevention effect was outstanding.

2) The conventional method of removing radioactive contamination after draining pool water uses a large amount of water, but the method of the present invention using polysheet laying does not use water, so it is not possible to treat a large amount of contaminated water as in the conventional method. You don't have to do it.

3) Compared to conventional methods, the method according to the present invention allows decontamination work to be carried out in a shorter time and with a smaller number of people. There are advantages such as

[Brief explanation of the drawing]

The figure shows how to lay the polysheet. In the figure; 1 Poly sheet with weak adhesiveness 2. Tape with strong adhesive properties

Claims (1)

[Claims] Radioactive contamination of the pool floor and walls during the filling period can be prevented by laying a weakly adhesive polysheet on the floor and walls of the pool and pasting it tightly with strong adhesive tape around it. A method for preventing radioactive contamination of nuclear reactor pools, etc.