JPS60142297A - Method of treating radioactive waste - 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 The present invention relates to a method for treating radioactively contaminated waste discharged from, for example, nuclear power generation facilities.

Most of the above-mentioned wastes are inorganic solids, and so-called melting treatment, in which they are immediately melted and then solidified, is an effective means of preventing secondary radioactive contamination to the outside world. However, if the solidified product obtained by the melting process is easily crushed or disintegrated, there is a high possibility that the crushed or disintegrated products will be scattered into the outside world and cause secondary pollution.

The present invention aims to solve the above-mentioned conventional problems,
The main point is to adjust the basicity (CaO/5iO2) of the waste.

The invention will be explained in detail below.

In the case of nuclear power generation facilities, the waste to be covered by the present invention is as shown in Table 1.

Table 1 The above wastes are melted, for example, directly inside an arc furnace, direct current melting furnace, combustion type melting furnace, microwave melting furnace, etc., or by being poured onto molten metal melted therein. It is then taken out of the furnace and cooled and solidified. The physical properties of the solid obtained in this way are determined by the C contained in the solid.
It changes as follows depending on the ratio of aO and 5i02 (CaO/5i02: basicity).

According to Table 2, when the basicity is less than 0.5, it becomes glassy and easily fractures, and when the basicity is from 0.5 to 1.0, the melt becomes 100%
Crystal growth occurs through heat treatment of slow cooling at around 0°C, resulting in a solidified material that is hard and difficult to crush, and at temperatures between 1.0 and 2.5, crystal growth occurs due to natural cooling of the molten material. , hard crushing [2 hard solidified material was obtained, 2.0
In particular, when the number is 2.5 or more, the tendency to absorb water and disintegrate gradually increases. Therefore, the basicity of the solidified product should be 0.5~
If adjusted to a value of 2.5, preferably in the range of 1.0 to 2.0, it will not shatter or disintegrate over a long period of time. Therefore, a rock-like solidified product can be obtained without the risk of secondary contamination.

According to Table 1, all types of waste have a basicity of 0.
, 5 to 2.5, preferably 1.0 to 2.0. Therefore, in the present invention, the basicity is calculated from the content evidence based on the direct amount of CaO and SiO in the waste, and the basicity is 0.5 to 2.5, preferably 1.0.
CaO and/or Siq components are added so that the value becomes ~2.0. CaO and 5iOJ abundance is the first
If the waste is listed in the table, approximate values can be calculated using Table 1 from the mixing ratio and processing amount without analysis.

In addition, CaO and /-1: or 5iOz components (
:'aO+5i02 As is clear from Table 1, rather than a CaO compound, the CaO component is CaO rich, that is, a CaO composite such as concrete with a high basicity, and the 5i02 component is a 5i02 rich, that is, a heat insulating material with a small basicity. SiO□ composites such as materials, glasses, etc. can be used.

FIG. 1 shows a direct current type melting furnace used in the present invention. In the figure, a direct current melting furnace (1) has a furnace body (2) made of refractory, a water-cooled wall (3) sandwiched between the furnace body (2), and a furnace body (2). The main electrodes (4) and (5) are inserted from both sides, and the input port (
6), the inspection CI (71) and the exhaust pipe (
A furnace lid (7) having a furnace cover (72), a melt outlet (8) opening on the side, and a gutter body (9) disposed directly below the outlet (8) to receive the melt, Furnace (1) is mounted on mount θ
0” is installed on the second. After the basicity of the waste has been adjusted to a predetermined value, the waste is transferred to the input port (6) via the input conveyor (b).
It is then put into the furnace (1). The input port (6) is opened and closed by a cylinder (61). The metal is melted in advance in the furnace (1), and the waste (13) is thrown onto the molten metal layer θ and melted.The waste a is thus melted and taken out from the outlet (8). The gutter body (9) is cooled and solidified.
), the solidified material is accumulated in the receiver αxun.

The present invention is not limited to the above examples,
Furnaces include combustion type melting furnaces, arc furnaces, and direct current type melting furnaces.
A microwave melting furnace or the like may be used, or the waste may be directly heated and melted without using a metal melt. The solidified product of the present invention thus obtained is rock-like and difficult to crush and disintegrate.＼Conc I7) It can be safely reused as aggregate, etc.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of the apparatus used in the present invention. In the figure (1)...furnace, (6)...metal molten layer, ol...
...Waste, patent applicant Daido Steel Co., Ltd.

Claims (1)

[Claims] (1) When melting radioactive waste, the basicity (CaO/5i02) of the waste is measured, and a predetermined amount of CaO and/or 5i02 is added based on the measured value. , a method for treating radioactive waste characterized by adjusting the basicity to a predetermined basicity (2) The predetermined basicity (CaO/5i0
2) is in the range of 0.7 to 2.5 [Claims (method for disposing of radioactive waste described in January (3)) The radioactive waste is incinerated ash contaminated with radioactive materials, heat insulating material , a filter medium, and concrete] Claim (1) and (a method for disposing of radioactive waste described in February)