Neptunium Doping of the Crystalline Ceramic Waste Form Synroc B

Abstract

The crystalline ceramic waste form synroc B was produced with a nominal loading of 10 wt% NpO{sub 2} by soaking green pellets with Np solution followed by sintering in reducing atmosphere (Ar/8% H{sub 2}). Electron microprobe analysis showed that Np was partitioned between the zirconolite (10.7 wt% Np) and perovskite phases (9.5 wt%), whereas the remaining two phases of hollandite and rutile contained {le} 0.2 wt% Np. The partitioning of Np was not significantly changed by an oxidizing anneal. Leach tests (190{degree}C, 7d, deionized water) showed the leach rate for Np to be <5 {times} 10{sup {minus}3} g/(m{sup 2}{center dot}d).