Vitrification of U3O8 in iron aluminium phosphate matrices including Bi2O3 as uranium surrogate

Abstract

In order to encapsulate nuclear wastes (NW) enriched in Uranium, they have been designed and obtained vitrified matrices of iron aluminum phosphates including substitution of U by Bi. These glasses have been designed and obtained formulating all from the starting binary composition: 60P2O5·40Fe2O3 where the Fe/P ratio was 0.67. The thermal behavior has been investigated by DTA/TG analysis and thermal expansion, as well as identification of some phases by TEM/EDS. The vitrified structures are difficult to crystallize as is the case of the (Fe + U) contents in the range of 0.50 per P atom. Glasses with Bi-oxide are less resistant to crystallization than those containing U. The glasses here investigated depict a reasonable water chemical stability due to the high percentage of P–O–Fe–O bonds and the presence of U (4+ to 6+). Lately, it has been also investigated the calcination of simulated miniplates of Si2U3/Al having additions of these glasses and U3O8 to dilute this Uranium enriched in MTR combustible (Material Testing Reactor).