A new uranyl oxide hydrate phase derived from spent fuel alteration

From Yellow to Black: Dramatic Changes between Cerium(IV) and Plutonium(IV) Molybdates

“…34 Molybdate phases also form from the alteration of spent nuclear fuel during burn-up and have a large impact on the mobility of all actinides in a repository-type environment. 35 The environmental importance and structural complexity of molybdate has driven a large research effort in the structural chemistry of actinyl molybdates and to a smaller extent the trivalent and tetravalent actinide molybdates. [36][37][38][39][40][41] Concurrently, lanthanide molybdates have also been investigated for their complex and interesting properties such as negative thermal expansion, ferroelectricity, ferroelasticity, photoluminescence, and interesting structure types.…”

Crystal Chemistry of Rubidium Uranyl Molybdates: Crystal Structures of Rb6[(UO2)(MoO4)4], Rb6[(UO2)2O(MoO4)4], Rb2[(UO2)(MoO4)2], Rb2[(UO2)2(MoO4)3] and Rb2[(UO2)6(MoO4)7(H2O)2]

“…They may also be significant in a geological repository for nuclear waste because 97 Mo is a fission product that forms during irradiation of nuclear fuel in a reactor. Recently, a Cs-Ba-bearing uranyl molybdate was found as an alteration-induced phase on spent nuclear fuel at 901C in tests designed to simulate conditions expected in the proposed nuclear waste repository at Yucca Mountain, Nevada (2). Thus, uranyl molybdates may be important radionuclide-bearing phases during evolution of the repository.…”

“…Alkali metal uranyl molybdates have been extensively studied and several phases were described in the Na-UMo-O (3-7), K-U-Mo-O (8)(9)(10)(11), and Cs-U-Mo-O (12)(13)(14)(15) 2 (20), and a-and b-Cs 2 [(UO 2 ) 2 (MoO 4 ) 3 ] (21). Although the structures of many compounds in the Na-U-Mo-O, K-U-Mo-O and Cs-U-Mo-O systems are now known, little is known concerning Rb uranyl molybdates.…”

Actinyl Compounds with Hexavalent Elements (S, Cr, Se, Mo) – Structural Diversity, Nanoscale Chemistry, and Cellular Automata Modeling

“…Several particular examples of mutual orientation of chain diamine molecules with topology of the inorganic layer is shown in Figure 12. Gurzhiy et al [26] investigated phase formation in the system UO 2 (NO 3 ) 2 (Figure 13a), for n = 0 the structure is based upon 2D layers (Figure 13b). For n = 0.5, a disordered structure was observed that represents a superposition of the 1D and 2D structures (Figure 14).…”