FINAL REPORT FOR THE INITIAL SOLID PHASE CHARACTERIZATION OF THE 2011 GRAB SAMPLES AND COMPOSITE FOR THE C-109 HARD HEEL STUDY

[摘要] On May 3, 2011, solid phase characterization subsamples were taken from six of the eight grab samples that had been collected from tank 241-C-109 in April, 2011 and delivered to the 222-S Laboratory. These subsamples were characterized in order to guide the creation of the composite for the C-109 hard heel study. Visual observation showed that there was a large variability in the physical characteristics of the eight individual grab samples. Several of the grab samples consisted of 'stone-like' cobbles (several > 25 mm in diameter) while the other grab samples were of a finer granular composition referred to as 'bulk material'. Half of the six subsamples taken for this initial SPC were of crushed cobbles and half were of the bulk material. Scanning electron microscopy was performed on all six subsamples, and X-ray diffraction was performed on all three of the 'bulk material' samples and one of the crushed cobble samples. The crushed cobbles were found to be composed primarily of gibbsite (Al[OHh]{sub 3}). Analysis by X-ray diffraction indicated gibbsite to be the only crystalline phase detected, and scanning electron microscopy showed the crushed cobbles to consist primarily of aggregates of euhedral to subhedral gibbsite crystals that were 20 to 100 {mu}m in size. The aggregates, having a moderate amount of pore space, were cemented primarily by recrystallized gibbsite making them resistant to crushing. The bulk material consisted of coarse to fine-grained pebble-sized (2 to 20 mm) particles. The X-ray diffraction analysis showed them to be a mixture of natrophosphate (Na{sub 7}[PO{sub 4}]{sub 2}F{center_dot}19[H{sub 2}O]) and gibbsite crystals in varying amounts in each of the three subsamples (i.e., some grab samples were primarily natrophosphate while others were mixed with gibbsite). The scanning electron microscopy analysis of the bulk material showed the crystals to be euhedral to anhedral (rounded) in shape. Trace phases, too minor to be detected by XRD, were observed in the SEM analysis of both the crushed cobble and bulk material. Some of the trace phases were identified as uranium-rich (sodium diuranate and/or clarkeite), sodium aluminum-rich (dawsonite and/or sodium aluminate), and a sludge-like phase with a variable chemistry rich in iron, nickel, and lead. A composite was created from the grab samples and a sample was taken from the composite, labeled S11T009482, for solid phase characterization. In general, the vast majority of the particles and aggregates analyzed in the composite were either gibbsite or natrophosphate. A very minor phase consisting of dispersed small particles was rich in uranium.

[发布日期] 2011-12-01

[学科分类] 核能源与工程

[关键词] AR FACILITIES;CHEMISTRY;CLARKEITE;CRUSHING;DAWSONITE;GIBBSITE;IRON;MIXTURES;NICKEL;SCANNING ELECTRON MICROSCOPY;SHAPE;SODIUM;TANKS;URANIUM;X-RAY DIFFRACTION