Preparation and Characterization of Borosilicate Glass Waste Form for Immobilization of HLW from WWER Spent Nuclear Fuel

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Preparation and Characterization of Borosilicate Glass Waste Form for Immobilization of HLW from WWER Spent Nuclear Fuel Reprocessing S.V. Stefanovsky,1 M.V. Skvortsov,2 O.I. Stefanovsky,1 B.S. Nikonov3, I.A. Presniakov,4 I.S. Glazkova,4 A.G. Ptashkin1 1

Frumkin Institute of Physical Chemistry and Electrochemistry (IPCE) , Russian Academy of Sciences, Federal Agency of Science Organizations, 31-4 Leninskii av, Moscow 119071 Russia 2 D. Mendeleev University of Chemical Technology, Miusskaya sq. 9, 125047 Moscow, Russia 3 Institute of Geology of Ore Deposits, Mineralogy, Petrography, and Geochemistry, Russian Academy of Sciences, Federal Agency of Science Organizations, Staromonetnii lane 35, Moscow 11017 Russia 4 Lomonosov Moscow State University, Radiochemistry division, Vorobyovy Gory, 1, Building 10, Moscow 119991 Russia ABSTRACT Borosilicate glassy materials for immobilization of HLW from Russian WWER (PWR) spent nuclear fuel reprocessing were designed, synthesized in a resistive furnace, and characterized by XRD, SEM/EDS, and FTIR spectroscopy. Chemical durability was determined by PCT-A procedure and compared to EPA glass and reference data. The glasses with 20 and 25 wt.% waste loading were found to be X-ray amorphous, homogeneous and chemically durable. Glass network formally had a relatively low degree of connectedness that was increased due to embedding of different structural groups thus improving chemical durability. Boron is present primarily in trigonal oxygen coordination. The glasses with 40-45 wt.% waste loading contained minor britholite phase concentrating rare earth elements and as expected trivalent actinides. Glassy product with up to 30 wt.% waste loading was also produced by cold crucible inductive melting at the IPCE RAS lab-scale unit equipped with 56 mm inner diameter copper cold crucible and energized from a 10 kW/5.28 MHz generator. The product was composed of vitreous phase and minor britholite with average composition K0.39Sr1.99Fe0.16Nd5.50Si7.96O26.60. INTRODUCTION Currently in Russia there is the only spent nuclear fuel (SNF) reprocessing plant (RT-1) at the Production Association MAYAK (Chelyabinsk reg., Ural) which reprocesses SNF from commercial WWER-440 (PWR type), BN-600 power, transportation facility (nuclear submarines), and research nuclear reactors [1]. A new reprocessing plant at the Mining and Chemical Combine (Krasnoyarsk reg., Siberia) is under construction now. This plant will reprocess SNF from more powerful WWER-1000 reactors. High level waste (HLW) generated at SNF reprocessing is planned to incorporate in borosilicate [2] rather than aluminophosphate glass currently used at MAYAK [1]. The borosilicate glasses are currently used for immobilization of both commercial and defense HLW in the USA, France, and some other countries and have high chemical durability and radiation resistance [3]. The present work describes the phase composition, structure and chemical durability of some model borosilicate glasses which may be considered as potential vitreous waste forms for