The purpose of the Seminar was to provide an international interdisciplinary forum for in-depth discussions on the pros and cons of a denitration step by chemical means in the course of solidification of MAW (medium active waste) and HAW (highly active waste), prior to feeding the calciner or melter. In particular, differences In the volatility of some components and aerosol formation during the vitrification step are of interest. Chemical rather than thermal denitration may have particular merits which could simplify off-gas purification. A reduction in the salt burden of waste solutions, leading to a reduction In the volume of solid waste, may also be achieved. The scientific programme of the Seminar consisted of invited lectures only, given by experts actively engaged in this field of research. The emphasis was on extensive discussions among the partiCipants, with the aim of leading to an objective understanding of the state-of-the-art. The meeting also indentified issues and options for future research.