Annealing of Mineral-Like Host Matrices for High-Level Waste Immobilization

— We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from processing of spent nuclear fuel of a thermal neutron reactor. The results demonstrate that heat treatment of Nd 2 TiZrO 7 (pyro...

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Bibliographic Details
Published in:Inorganic materials 2022-06, Vol.58 (6), p.651-660
Main Authors: Kuznetsov, I. V., Budin, O. N., Shchepin, A. S., Kalenova, M. Yu, Mel’nikova, I. M., Saprykin, R. V., Al’zhev, N. I.
Format: Article
Language:English
Subjects:
Bend strength
Chemistry
Chemistry and Materials Science
Compressive strength
Crystal defects
Defect annealing
Heat treatment
Immobilization
Industrial Chemistry/Chemical Engineering
Inert atmospheres
Inorganic Chemistry
Materials Science
Modulus of elasticity
Physical properties
Rare earth elements
Skull melting
Spent nuclear fuels
Thermal expansion
Thermal neutrons
Titanium dioxide
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Summary:— We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from processing of spent nuclear fuel of a thermal neutron reactor. The results demonstrate that heat treatment of Nd 2 TiZrO 7 (pyrochlore structure) and Nd 4 Ti 9 O 24 (orthorhombic titanate phase) + TiO 2 host matrices prepared by induction skull melting reduces the density of lattice defects. Annealing in an inert atmosphere with isothermal holding at a temperature of 850°C for 1–3 h improves the hydrolytic stability of the material. Heat treatment of the host matrices leads to changes in their bending and compressive strength. At the same time, no significant effect of annealing on their thermal expansion coefficient or elastic modulus has been detected.
ISSN:0020-1685
1608-3172
DOI:10.1134/S002016852206005X