Ma Jiang,Fang Zhiwei,Yang Xiaoyong,Wang Bo,Luo Fen,Zhao Xiaoli,Wang Xiaofen,Yang Yushan
Ceramic matrix containing zirconolite, hollandite, and perovskite phases is proposed as a potential host for HLW immobilization. Hollandite phase principally immobilizes Cs, while perovskite phase mainly immobilizes Sr. In this study, hollandite–perovskite composite ceramics are considered as a specialized waste form for immobilizing the separated Cs and Sr from HLW streams and synthesized by a solid-state reaction method at 1300 °C for 5 h. The phase compositions of the synthesized composites were characterized by XRD and BSE. The XRD results indicated that the as-prepared ceramics are composed of tetragonal hollandite Ba 0.8 Cs 0.4 Al 2 Ti 6 O 16 , cubic perovskite SrTiO 3 , alongside a lesser amount of TiO 2 . The BSE—EDX results confirm that Cs partitions into the hollandite matrix, while Sr incorporates into perovskite host with homogenous distribution. In addition, aqueous durability testing was carried out using the MCC-1 static leach test method. The normalized release rates of Cs and Sr in HP-3 sample (i.e., 75 wt% Ba 0.8 Cs 0.4 Al 2 Ti 6 O 16 + 25 wt% SrTiO 3 ) were < 10 −2 g·m −2 ·d −1 after 42 days, exhibiting excellent chemical durability. These results indicate that the hollandite–perovskite ceramic matrix could be considered as a customized host matrix for immobilization of the separated Cs and Sr from HLW streams.
In this paper, we present a productive low-temperature fabrication of Cs-hollandite ceramics by adding Bi 2 O 3 as a sintering aid to achieve high cesium retention. The effects of Bi 2 O 3 addition on the phase composition, crystal structure and aqueous stability of the stoichiometric Ba 0.9 Cs 0.3 Cr 2.1 Ti 5.9 O 16 ceramic waste form were investigated. It was found that adding Bi 2 O 3 can effectively reduce the sintering temperature and promote densification of Cs-containing hollandite products. The Cs-hollandite ceramic with 2 wt% Bi 2 O 3 sintered at 1000 °C showed a single phase with > 98 % cesium retention, which was ∼ 200 °C lower and ∼ 11 % retention rate higher than those of reported Cs-bearing hollandite. Moreover, the leached sample remained stable tetragonal structure, the LR Cs was in the order of 10 -3 g·m - 2 ·d -1 after 28 days and the leaching indexes > 8, exhibiting good aqueous stability. This route can be considered as a promising solution to prevent cesium loss for incorporating the cesium waste in ceramic hosts.
Yushan Yang,Xiaofen Wang,Shunzhong Luo,Xiaoyong Yang,Jiang Ma
[Cs x Ba y ][(Al 3+ ,Ti 3+ ) 2 y + x Ti 4+ 8-2 y - x ]O 16 (0.4 ≤ x , y ≤ 0.8) ceramics were synthesized to investigate the substitution effects of Ba 2+ for Cs + on the stability of hollandite-ceramic waste forms. It was found that the substitution of Ba 2+ for Cs + in the (Cs,Ba)-hollandite system does not cause substantial variation in the crystallographic phase and microstructure. The normalized release rates of Cs and Ba at 90 °C in deionized water were < 0.005 g m −2 d −1 after 28 days. These results indicate that hollandite ceramics are an ideal host for permanent radioactive caesium disposal.
危险品化学品经营许可证（带存储）