The solidification of concentrated liquid waste from BWR through the decomposition and vitrification of Na2SO4 with silica

The development of a new solidification process for liquid waste is an important concern for modern radioactive waste disposal systems, especially in relation to the management of waste on land. In this paper, the authors examine the effect of silica on the decomposition and vitrification of Na2SO4- the major constituent of liquid waste from BWR. The decomposition of Na2SO4 with silica was successfully carried out by adding a small amount of carbon (about 10%) to Na2SO4. In this process, 10 parts Na2SO4, 1.5 parts clay containing 10% AI2O3, and 0.1 part graphite are mixed, then heated at 1200 - 13000C for one hour. The result is a vitrified mixture that is more durable than conventional window glass. This vitrification process for liquid waste is estimated to have a higher volume reduction factor and greater durability than conventional vitrification processes. (author)