Thermal interaction experiments with UO2 and sodium using pyrotechnic heating

Abstract

Abstract An experimental technique is described which tests for the possibility of a thermal interaction between UO 2 and sodium. Pyrotechnic heating is used to raise the temperature of the UO 2 to within the range 3000–3500 K. Difficulties involved in using this type of heating are discussed and an analysis is presented which calculates the thermodynamic properties of the residues which are released into the sodium. The geometry of the apparatus is such that evidence of a thermal interaction can be provided by the measurement of the argon gas blanket pressure. For a given pyrotechnic charge releasing UO 2 under sodium it is shown that there is a limiting peak gas blanket pressure below which it is not possible to state that an interaction has taken place. This limiting pressure is shown to be dependent upon the type and quantity of dispersant which is used to release the charge products. In these preliminary tests no evidence could be found of any thermal interaction between UO 2 and sodium but a substantial series of tests is prepared in which significant parameters are varied in order to investigate under what conditions such reactions might occur. Results are also reported from preparatory tests where pyrotechnic charges diluted with silver, alumina and tin were burned under water in a glass windowed vessel. In these latter tests high speed photography allowed visual examination of the charge release.