JAERI/ANSTO co-operative research on radiation damage and actinide behaviour in Synroc

Abstract

ANSTO and JAERI have collaborated formally since 1985 in the study of actinide behaviour in and self-irradiation studies of Synroc, a titanate ceramic designed for immobilising high-level waste from nuclear fuel reprocessing. JAERI has fabricated Synroc samples containing ∼1wt% of the short-lived actinide 244Cm(t1/2 18 yr), to produce in 2 years, alpha-damage which would take ∼ 105 yr to accrue in actual Synroc. The effects of the damage on the structure and aqueous leachabilities of various constituent elements will be discussed. Parallel experiments at Ansto have dealt with the aqueous dissolution of Synroc: containing sufficiently low levels of actinides to avoid significant radiation damage effects, the effects of fast-neutron irradiation and studies of radiation damage in natural analogues of Synroc phases, especially zirconolite. Difficulties associated with the presence of sodium in Japanese waste have been eliminated by a minor reformulation of Synroc. Recent work has focussed on developing a zirconolite-rich version of Synroc to immobilise actinide-rich wastes resulting from advanced reprocessing/partitioning schemes and progress will be reviewed.