Compositions – Radioactive compositions
Patent
1989-12-14
1992-05-19
Hunt, Brooks H.
Compositions
Radioactive compositions
252628, 252633, G21F 916
Patent
active
051146223
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method of cementing radioactive wastes and cemented bodies thereof, and more particularly to a method of cementing radioactive wastes and cemented bodies thereof which are less liable to bring about radioactivity leakage and suitable for disposal of cemented bodies of radioactive wastes in the land.
2. Background Art
As is well know, for stable storage and disposal, radioactive wastes generated in facilities handling radioactive substances, such as a nuclear power plant, should be solidifyed with a solidifying material into a container, thereby preventing radioactive substances from diffusing into the environment.
In recent years, sites for shallow land disposal of radioactive wastes have been decided, and the performance required of the solidified bodies of the radioactive wastes are clarifying, so that a specific measure such as legal regulation has been taken. According to this measure, assessment is made on the paths of migration of radioactive substances from the solidified bodies of radioactive wastes into the environment. Among the migration paths, particular importance has been attached to the path of migration into underground water by rainwater from the viewpoint of exposure of residents living in the periphery to the radioactive substances.
Specifically, solidified bodies of the radioactive wastes are buried in a concrete pit provided in a depth of 3 to 5 m of the disposal site. This enables the solidified bodies to be managed so that no radioactive substance will leak during the initial 50 years wherein the radioactivity level is high. For this period of time, the radioactivity level is lowered by disintegration of the radioactive substances. However, minute amounts of radioactive substances remain within solidified bodies of the radioactive wastes, which makes it necessary to reduce leakage of the radioactive substances. In the safety assessment, attention has been paid to the fact that when the solidified body is immersed in water, the radioactive substance leaks from the solidified body through the medium of water, and the safety assessment supposes immersion of the solidified body in water through penetration of rainwater into the pit.
In the conventional solidified bodies as well, the radioactivity leakage in the above-described state is so small that there occurs no problem. However, it has been desired to develop a method of solidifying a radioactive waste which further enhances the safety of the solidified body and can cope with the disposal of radioactive wastes having a high radioactivity level in the future.
In view of the above, novel solidification methods have been proposed. In these methods material is mainly composed of cement which is easy to solidify. One of these methods is described in Japanese Patent Laid-Open No. 215999/1986. This method comprises reducing the amount of water (a ratio of water to cement), when a cement-base solidifying material is mixed with water, for the purpose of suppressing the occurrence of voids derived from excess water.
In the case of cement, in order to maintain given fluidity, it is necessary to add water in an amount exceeding that consumed in the hardening reaction of the cement. This brings about formation of voids in the cement filled with the excess water. This phenomenon becomes a factor causative of permeation of water into the cement (or the voids serve as a path of leakage of radioactive substances from the cemented bodies when radioactive wastes are cemented). Cement having low water permeability has been developed for use in, among general industrial uses, applications such as floors of reservoirs and working spaces where permeation of water brings about a problem. Examples of this kind of cement include one containing a surfactant (a water reducing admixture) for the purpose of enhancing the fluidity of cement particles and one containing round particles having a size smaller than that of the cement particles (bearing effect). The cement described in the abovementione
REFERENCES:
patent: 3340202 (1967-09-01), Olombel et al.
patent: 4505851 (1985-03-01), Funabashi et al.
patent: 4661291 (1987-04-01), Yamasaki et al.
patent: 4725383 (1988-02-01), Hayashi et al.
patent: 4859367 (1989-08-01), Davidovits
Baba Tsutomu
Chino Koichi
Funabashi Kiyomi
Kikuchi Makoto
Kuriyama Osamu
Hitachi , Ltd.
Hunt Brooks H.
Mai Ngoclan T.
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