Rich Burning The Glauconite Artificial Rocks And Zircon Curing Simulation Of Actinide Waste

Pyrochlore as a host phase in synroc for separated actinides fromHLW was systematically studied. Six different formulae with actinidewaste loading 32-50wt% of pyrochlore-rich synroc samples werefabricated and evaluated. The results indicated that pyrochlore is thesuitable host phase for actinides with satisfied properties. Thepreliminary study on zircon waste form for actinide wastes which wasfabricated by using natural zircon as the precursor material was alsocarried out in this study the feasibility of this method wasdemonstrated.For the study of pyrochlore-rich synroc waste forms, neodymium(Nd) and uranium (U) were used as the simulants for trivalent andtetravalent actinides, the designed phase assemblage was 85wt%pyrochlore, 5wt% hollandite and l0wt% rutile. The fabricatedpyrochlore-rich synroc samples had good physical properties with highdensity (>5.1g/cm~3) and Vickers hardness (≥947kg/mm~2), and fewporosities (<2 %). The PCT, MCC-1 and simulated geological leachingtest results showed that the samples were highly durable, with mass lossand elemental nominalized leach rates lower than or equal tozirconolite-rich synroc and synroc-C. The corrosion to the samplesurface was negligible with the matrix elements leaching depth lowerthan 100nm, the leaching of the elements (Ti, U) was enhanced by thegeological media (granite, clay etc.), but there was also no significantcorrosion effects on the sample surfaces. The scanning electronmicroscopy (SEM), positron annihilation technology (PAT) andemanation thermal analysis (ETA) study indicated that amorphous Ti-Omembrane was formed on the surface of the leached samPles, with thehighly leach resistance matrix Ti net they can retard the furthercorrosion to the samPles. The leaching mechanism of elements werevery comPlicated with many influence factrs, the leaching models ofthe main elements were also given in this stUdyThe heaVy ion irradiation technique was used in this study tosimulate the Q -decay self irradiation damage in the waste forms. ThestUdy of radiation effects on pyrochlore-rich synroc samPle showed thatthe saInPle was highly irradiation resiStance, the amorphous dOse fOrmatrix Pyrochlore Phase was 0.5dPa, Which is higher than thezirconolite (0.3~0.4dPa). PAT analyses indicated tha the defects in thesamPles produced by heaVy ion irrallation wer mainly large voids. X-ray dihoeter (XRD) and PAT fOr annalation study of the fullyamorphous samPle showed that the pyrochlore Phase could recover itScrystal StrUCtUr before 900'C, and the defects produced by irradiationwere nOt fully recovered even by annalation at l200C.W, SEWS and transmission electron microscOPy withenergy disPersive sPectrOmeter (TEM/EDS) were used to study thephase assemblage, microStrUctUr, element patitioning and phasechemical comPosition of the pyrochlore-rich synroc samPles. TheresultS showed tha the fabricated saInPles wer highly densified withfew porosity, the phase crystas were finely developed with narrowcrysta bOUnedes. The Pyrochlore phase was the main phase of thesamPles in accordance with the original design. Due tO theinhomogeneity of the fabrication process, ther were few agglomethes(<100 ll m) distributed among the matrix, the agglomer8tes mainlyconsisted of two ldnds of rutile, and a small quantity of hOllandite andzirconolite(low waste loading).There were mainly two kinds ofpyrochlore phase existed in matrix, few unexPeCtCd phases such asuraninite and brannerite also existed in matrix. The chemical formula ofthe phases (Pyrochlore, rutile and uraninite.) were determined by theanalysis of the phase elemental comPositiOn, the ion subStitution andcharge comPensaton rules wer also discussed.The preliminny study on zircon waste form fabricated by usingnatural zircon as Precursor material indicated tha this idea is feasible.The zircon waste form with high leach resistance and irradiatonresistance proPertes was fabri...