Study on Utilisation of Flyash for Barrier Layer/Buff er Materials for Radioactive Waste Disposal

摘要

About 15 per cent of total electricity (400 MkW) was generated by nuclear power plants in the worldrn(2009) and about 36 000 tons of uranium has been mined in uranium mines annually. Radioactivernwaste material is produced from uranium mines and nuclear power plants. The wastes must berndisposed or stored safely for long-term. If they leak and/or move from disposal or storage sitesrndue to air/groundwater fl ow, then a serious environmental pollution can occur. Hence, multi-layerrnsystem has been proposed and employed in order to seal off these radioactive waste materials fromrnbiosphere. Basically, bentonite is now used for establishing absorbing and sealing layers in thisrnsystem. However, the amount of high quality betonite is very limited and in some cases it is hard tornbe obtained.rnOn the other hand, a great deal of refuse from coal burning plants is produced every year and thernamount of it is expected to be higher each year, especially in developing countries. More than half ofrnfl yash is utilised and the remaining is disposed at the disposal sites. However, the life of the disposalrnsite is limited and it is diffi cult to fi nd a new disposal site. It is requested that the percentage of thernutilisation of the fl yash be increased in every fi eld.rnFrom the above two points of view, a fl yash-based barrier layer/cover system is considered inrnthis research and this paper discusses the applicability of fl yash as a content of barrier layer/coverrnmaterial based on the results of a series of laboratory tests.