Cold Crucible Vitrification of U-Bearing SRS SB4 HLW Surrogate
- PDF / 447,325 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 90 Downloads / 203 Views
1265-AA02-03
Cold Crucible Vitrification of U-Bearing SRS SB4 HLW Surrogate S.V. Stefanovsky,1 A.G. Ptashkin,1 O.A. Knyazev,1 O.I. Stefanovsky,1 J.C. Marra2 1 2
SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 RUSSIA, [email protected] Savannah River National Laboratory, Building 773-A, Aiken, SC 29808 USA
ABSTRACT Savannah River Site Defense Waste Processing Facility (DWPF) Sludge Batch 4 (SB4) high level waste (HLW) simulant at 55 wt % waste loading was produced in the demountable cold crucible and cooled to room temperature in the cold crucible. Appreciable losses of Cs, S and Cl took place during the melting. A second glass sample was subjected to canister centerline cooling (CCC) regime in an alumina crucible in a resistive furnace. X-ray diffraction (XRD) study showed that the glass blocks were composed of vitreous and spinel structure phases. No separate U-bearing phases were found. INTRODUCTION SIA Radon performed testing that has demonstrated the feasibility of the Cold Crucible Induction Melter (CCIM) to achieve high waste loadings and maintain high throughput for Savannah River Site high-level waste (HLW) feeds. A demonstration with the high alumina content SB4 feed was completed with a waste loading of 55 wt % [1]. Prior to implementation of the CCIM in a production process it is necessary to better understand processing constraints such as variability of phase composition and elemental distribution over the bulk of the glassy materials remaining in the cold crucible after pouring (“dead volume”) and annealed in canisters by a canister centerline cooling (CCC) regime [2]. EQUIPMENT AND FEED PREPARATION To produce an integrated block of solidified material a new demountable cold crucible has been designed and manufactured. The 56 mm inner diameter crucible with melt surface area of 26.4 cm2 (Fig. 1, left) consists of two sections which are fabricated from the U-shaped copper 12 mm inner diameter pipes. The two section design provides for crucible dismantling and removal of an integrated block of solidified material. The crucible is also additionally equipped with a local off-gas exhaust unit to prevent radioactive contamination of equipment and the environment (Fig. 1, middle). It is coated from the outside with a chamotte-based putty (Fig. 1, right). The cold crucible is energized from a 5.28 MHz/10 kW generator through a battery of capacitors. The flow sheet of the cold crucible based unit is shown in Fig. 2. The SB4 sludge surrogate (Table I) was prepared by a SRT-MST-2007-00070 procedure [3]. It was intermixed with a Frit 503-R4 (wt.%: 8 Li2O, 16 B2O3, 76 SiO2) to obtain a glass at 55 wt.% waste loading. Calculated chemical composition of the glass was as follows, wt.%: Al2O3 – 14.66, BaO – 0.04, CaO – 1.62, Cr2O3 – 0.12, Cs2О – 0.55, СuO – 0.03, Fe2O3 – 16.65, K2O – 0.04, MgO – 1.63; MnO – 3.31, Na2O – 11.59, NiO – 0.95, PbO – 0.21, SiO2 – 35.77, ZnO – 0.03, ZrO2 – 0.05, F – 0.02, Cl – 1.33, I – 0.03, P2O5 – 0.18, SO3 – 0.39, B2O3 – 7.20, Li2O – 3.60. Uranium was introduced as a UO2(NO3)2·6H2O
Data Loading...
