ИСТИНА

Commercial reactors spent nuclear fuel (SNF) reprocessing produces high-level radioactive waste with high residual amount of americium, mainly 241Am which exceeds the amount of 239Pu by more than 10,000 times [1]. As a result, in the USA refused SNF reprocessing is not applied but in France the methods of americium as well as curium separation as a DIAMEX or EXAM process are under development now [2]. The heat release of 241Am and 244Cm are 0.111 and 2.78 W/g, respectively, results in strong decomposition of extractants yielding low efficiency of Am separation and from 1 to 5% of total Am will remain in HLW. In this case the residual HLW (after Am and Cm) separation must be incorporated in glass-ceramics rather than glass as at present [4]. Taking into account Russian experience when HLW is incorporated in sodium-alumino-phosphate glass the sodium aluminophosphate glass-ceramics may be considered as the suitable host phase for the Am-bearing residues. This glass-ceramics is composed of the Am-bearing monazite structure (Ln,Al)PO4 and sodium-iron orthophosphate – Na3Fe2(PO4)3 with minor Al crystalline phases distributed in the interstitial glass. Elemental leach rates of the major elements (Na, Al, Fe, P) determined by Russian standard were found to be 10-5-10-7 g/(cm2d), for REEs – lower 10-5 г/(см2сут) [5]. An alternative matrix is murataite based ceramics or glass-ceramics composed of the zoned structure murataite grains with maximum actinide concentrations in the core of the grains that strongly reduces leaching of the actinide elements. Incorporation of up to 10 wt.% actinide oxides in the murataite structure at excellent chemical durability has been proven [7]. The work was supported from RFBR (project #18-29-12032\18 mk). 1. N.S. Babaev et al. At. Energy. 98 (2005) 115. 2. C. Poinssot et al. Procedia Chemistry. 21 (2016) 524-529. 3. V. Vanel et al. Procedia Chemistry. 21 (2016) 190-197. 4. R. Didierlaurent et al. WM2016 Conference, March 6 – 10, 2016, Phoenix, Arizona, USA. 16376. 5. S.V. Stefanovsky et al. J. Nucl. Mater. 500 (2018) 153-165. A.A. Lizin et al. J. Radioanalyt. Nucl. Chem. 318 (2018) 2363-2372.