[en] As X-ray fluorescence analysis (XRFA) represents a fast control method, it was decided, in the scope of the activities of the SCK/CEN-BELGONUCLEAIRE Fuel Group, to investigate the possibilities of this method with respect to the determination of the Pu/U+Pu ratio in FBR fuel pellets. A proper specimen preparation technique relative to the reproducibility of the measurements is described. A calibration graph is established and evaluated. (orig.)

[en] The preparation of lithium metazirconate by calcining at low temperature an intimate mixture of lithium carbonate and zirconia is discussed. Such a powder can be cold pelletized and sintered to densities up to 92% T.D. The pellets are contamination free, fine-grained and have a completely open porosity. Some properties are reported. (author). 12 refs.; 8 figs

[en] A new approach has been developed to produce sinterable lithium metasilicate in order to fabricate high density (> 90% TD) pellets by cold compaction and sintering. Lithium carbonate and silica are intimately milled, spray-dried, pre-calcined and calcined. Precalcination under wet air at about 430⁰C has led to the discovery of a hexagonal X-phase, the formation of which is the key to the process. The X-phase can in fact easily be transformed by a calcination below 600⁰C into a high reactive metasilicate containing no disilicate nor orthosilicate, which is not possible by direct calcination. The effects of temperature, time and atmosphere on the formation of the X-phase are discussed. (orig.)

[en] Lithium metasilicate pellets fabricated by cold compaction and sintering have been characterized in order to see how fabrication parameters control their density, structure and porosity. Milling conditions, drying technique, calcination and sintering temperatures, precompaction pressure as well as the kind of raw materials and stoichiometry are some of the factors investigated. A proper combination of the fabrication parameters allows to control the final density from 60 to 96% T.D. The porosity distribution depends mostly on the density of the sintered products: up to 77% T.D. all pores are open and above 89-90% T.D. usually closed. Nevertheless, it is possible to fabricate 91-96% T.D. pellets with a very extended open porosity by recrystallization above 925⁰C. (orig.)

[en] Lithium metasilicate pellets with tailored grain size and open porosity have been produced with densities from 60% TD to more than 95% TD. These characteristics are obtained by choosing appropriate preparation conditions among the five fabrication routes discussed in this paper. An investigation of the influence of deviations from stoichiometry shows that density, grain size, porosity and recrystallization are affected by the type of the secondary phase but not by its quantity. The effect of the fabrication conditions on specific surface area and moisture content is also mentioned. Thermal stability tests were performed between 500⁰C and 925⁰C. Dimensional and structural changes were not detected up to 700⁰C. Above 750⁰C, changes were observed in pellet weight, dimension and density as well as in grain size and porosity. These changes depend on the type of the secondary phase, the fabrication conditions, the pellet structure and texture. Minor changes in stoichiometry were also established. (orig.)

No abstract available

[en] The irradiation experiments EXOTIC-1, 2 and 3 are part of the European Fusion Technology Programme on Blanket Technology and are carried out as a joint project by SL Springfields, SCK/CEN Mol and ECN Petten in collaboration with JRC Petten. In the present paper, the characteristics of the as-fabricated and of the irradiated pellets of the EXTIC-3 experiment are described and compared to the results obtained in the two preceeding experiments, with particular attention for the integrity of the irradiated pellets, their dimensional stability, vitrification effects and tritium retention. (author) 8 refs.; 3 tabs

[en] The irradiation experiments EXOTIC-1 and 2 fit in the European Fusion Technology Programme and are carried out as a joint project by SNL Springfields, SCK/CEN Mol and ECN Petten in collaboration with JRC Petten. The SCK/CEN contribution to these experiments consists in five vented capsules containing lithium metasilicate pellets with varying stoichiometry, density, grain size, pore size and ⁶Li content. The irradiations lasted respectively 25 FPD and 50 FPD. This paper compares the characteristics of the as-fabricated and irradiated pellets and discusses the structural changes which occurred during irradiation. Results on retained tritium are also given. (orig.)