Advantages Hot Isostatically Pressed Ceramic and Glass-Ceramic Waste Forms Bring to the Immobilization of Challenging Intermediate- and High-Level Nuclear Wastes

Abstract

Hot isostatic pressing (HIP) is a technology with wide applicability in consolidating calcined intermediate-level and high-level nuclear waste, especially with wastes that are not able to be readily processed by vitrification at reasonable waste loadings. The essential process steps during the HIP cycle will be outlined. We have demonstrated the effective consolidation via HIP technology of a wide variety of tailored glass-ceramic and ceramic waste forms, notably simulated ICPP waste calcines, I sorbed upon zeolite beads, Pu-bearing wastes, inactive Cs/Sr/Rb/Ba mixtures, simulated waste pyroprocessing salts from spent nuclear fuel recycling, Tc, U-rich isotope production waste, and simulated K-basin (Hanford, WA, USA) and Magnox sludges (UK). Can-ceramic interactions have been carefully studied. The principal advantages of the HIP technology include: negligible offgas during the high temperature consolidation step, relatively small footprint, and high waste loadings. As a batch process, the wasteform chemistry can be readily adjusted on a given process line, to deliver wastes into different end states (e.g. direct HIP versus chemically tailored). This flexibility allows the treatment of multiple waste streams on the one process line.

Structural and spectroscopic investigations on the crystallization of uranium brannerite phases in glass

“…1 Many durable ceramic phases, in particular, titanate mineral phases recognized in Synroc (synthetic rock), [3][4][5][6][7][8][9][10][11][12][13] e.g., zirconolite (CaZrTi 2 O 7 ) and pyrochlore (Ln 2 Ti 2 O 7 : Ln = lanthanides and CaAnTi 2 O 7 : An = actinides) with potential actinide substitutions on the Ca/Zr sites of zirconolite and Ln site of Ln 2 Ti 2 O 7 pyrochlore have been investigated. Consequently, zirconolite- [14][15][16][17][18][19][20] and pyrochlore- [21][22][23] based GCs have been developed as potential waste forms for the immobilization of some compositionally diverse actinide-rich wastes, e.g., plutonium residue wastes and separated minor actinides.…”

Development of brannerite glass‐ceramics for the immobilization of actinide‐rich radioactive wastes

“…Some durable titanate mineral phases identified in Synroc, [6][7][8][9][10][11][12][13][14][15][16] e.g., zirconolite and pyrochlore, have been considered for such an application. Consequently, both zirconolite-and pyrochlore-based glass ceramics [20][21][22][23][24][25][26][27][28] have been investigated as potential waste forms for the immobilization of some compositionally diverse actinide-rich radioactive wastes, e.g., plutonium (Pu) residue wastes and separated minor actinides. Considering their actinide waste loadings and radiation resistance, pyrochlore-based glass-ceramics are more favorable.…”

Phase evolution from Ln2Ti2O7 (Ln=Y and Gd) pyrochlores to brannerites in glass with uranium incorporation

“…Some durable ceramic phases, such as various silicates, phosphates (monazite and xenotime), as well as titanate mineral phases formulated in SYNROC, e.g., perovskite (CaTiO 3 ), zirconolite (CaZrTiO 7 ), pyrochlore (ABTi 2 O 7 ) and brannerite (UTi 2 O 6 ) have been considered for developing such glass‐ceramics. So far perovskite, zirconolite, pyrochlore and brannerite based glass‐ceramics have been investigated as potential waste forms for the immobilization of some compositionally diverse actinide‐rich radioactive wastes.…”