FSUE Mining and Chemical Combine, Zheleznogorsk, Russia:

P. V. Aksyutin, Radiochemist Engineer, e-mail: atomlink@mcc.krasnoyarsk.su
A. S. Dyachenko, Leading Engineer
A. Yu. Zhabin, Head of Laboratory

National Research Tomsk Polytechnic University, Tomsk, Russia:
I. I. Zherin, Professor, Doctor of Chemistry

Thermochemical treatment of irradiated fuel simulator containing UO₂ of ceramic properties by N_xO_y + O₂ + CO₂ + H₂O_(steam) oxidizing mixture was tested in the range of 588 to 663 K. Fragments of new fuel elements were used as a feed material containing uranium-235 within 0.72 wt. % and 50 mm in length while jam of ends cutoff was 30% or less. Ability in principle to convert ceramic fuel in zirconium cladding into powder-like material during 3 hours was proven under N_xO_y + O₂ + CO₂ + H₂O_(steam) atmosphere at temperatures of 623–643 K. Thermochemical treatment was carried out in a furnace based reactor equipped with horizontal axis of rotation. Following thermochemical treatment of ceramic fuel simulator by N_xO_y + O₂ + CO₂ + H₂O_(steam) oxidizing mixture at temperature of 623 and 643 K, we made black powders separated from zirconium claddings completely. Fuel coming out of cladding was 99.9%. These powder s are in agreement with molecular formula U3O8 based on gravimetric analysis. Powder-like material was proven to be triuranium octoxide (X-ray peaks for 20; 21.5; 26; 34; 44; 46; 47;52) in accordance with X-ray phase analysis and typical reflections of XRD patterns. Particle sizes of powder in its basic fraction were 2–6 microns (95% of derived product or more).
This research was supported by TPU development program.

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