Wastes which contain hazardous organics as well as radioactive materials are designated as mixed waste and cannot be disposed directly because geological disposal of hazardous organics is not permitted. The wastes must first be treated to destroy or remove the hazardous organicsnormally that can be achieved by incineration of the waste. The primary safety concern for any mixed waste thermal treatment process is the possibility that radionuclides and, to a lesser extent, heavy metals could be emitted to the atmosphere in the off-gas stream. The purpose of this study is to evaluate the volatilities of actinides such Pu, U, Np and possibly Am. Introduction Cementitious materials are expected to be present in nuclear waste repositories in significant quantities.
Cements provide a highly alkaline environment.
Studies have shown that fresh concretes and cement phases strongly retard or immobilize certain actinides. Consequently, cementitious materials may serve as a barrier to the release of the radionuclides to the far field. Due to the uncer-tainties of these two opposite effects, it is important to investigate the interaction of actinides with concrete under varying conditions. After alteration, the chemical and mineralogical properties of these materials will be significantly different from that of the as-placed or fresh concrete. To accomplish thisobjective, new extractants capable of withstanding harsh chemical and radiation environments must be developed, modified, and tested for use in practical extraction systems.