Radiation damage effects in candidate titanates for Pu disposition: Zirconolite

摘要

Results from studies of radiation-induced damage from the alpha decay Of Pu-238 on the density and crystal structure of a nominally phase-pure zirconolite and two other zirconolite-bearing ceramics are discussed. Macro and micro swelling were found to be temperature independent, whereas the density determined with He gas pycnometry was temperature dependent. Approximately 2.6 x 10(18) alpha/g were needed to render the specimens X-ray amorphous-more to saturate the swelling. Unlike pyrochlore-based ceramics, we did not observe any phase changes associated with storage temperature and damage ingrowth. The forward dissolution rate at a pH value of 2 for material containing essentially all zirconolite is 1.7(4) x 10(-3) g/(m(2) d) with very little pH dependence and no dependence on the amount of radiation-induced damage. Even after the radiation-induced swelling saturated, the specimens remained physically intact with no evidence for microcracking. Thus, the material remains physically a viable material for the disposition of surplus weapons-grade Pu. (c) 2007 Elsevier B.V. All rights reserved.