[en] The sol dispersion process controlling methods used in different Sol-Gel technologies natively and abroad as well as the effects of these methods to the size distribution advancement so as to enhance the size qualification rate have been stated. The advantages and disadvantages as well as the final results of different controlling methods have been compared. The method of two-fluid nozzle with vibration is considered as an effective method for the controlling of sol dispersion process. The feasibility of using single-fluid nozzle with vibration to control sol dispersion process so as to improve the size distribution of fine nuclear fuel microspheres has been discussed

[en] The fabrication of long PZT (Pb(Zr_0.53Ti_0.47)) fibers by Sol-Gel technology using a continual method are presented. The influences of various parameters on the properties of mass and Gel fibers have been tested and discussed. The reasons for the cracking of fibers in drying and pyrolysis processes have been found and proper measures have been taken to deal with the cracking. A special roller is designed and used, of which the diameter can be adjusted easily. Wet Gel fibers can be wound and dried just on this roller, so the cracking of Gel fibers resulted from rewinding and shortening after spinning are avoided. Under the protection of N₂ the continual pyrolysis of dried Gel fibers at 300 degree C has been realized and pyrolyzed fibers with length up to 2 m have been obtained. After calcination and sintering, the long PZT fibers have been fabricated successfully

[en] HTGR fuel UO₂ kernels were prepared by the internal gelation process. The various steps of the process, e.g., preparing the acid deficient uranyl nitrate solution and the sol solution, dispersing the sol solution into droplets and gelating them so as to get solid microspheres, then washing, drying, calcining, reducing and sintering them into dense UO₂ microspheres have been studied. The suitable parameters for preparing UO₂ microspheres by a set of equipment with a throughput of 1 kg/day have been obtained. The performances of UO₂ microspheres are as follows: density: > 98% T.D., O/U: 2.000 ± 0.005, sphericity (D_max/D_Min): 1.03, crushing strength: 2 kg, closed pore size: ∼1 μm. The UO₂ kernels are suitable for the fuel element of the 10 MW HTGR of China

[en] The effect of temperature on pickling rate of zirconium alloy and the heat release constant was studied in this paper by soaked method. The results show that temperature has exponential effect on pickling rate of zirconium alloy, the rate increases 2.0∼2.5 times 10 at 20∼60. The pickling frequency factor is about 1.18 × 10¹² and the activation energy is about 70 kJ/mol. The pickling reaction of zirconium alloy is exothermic. The reaction temperature increases with the pickling process in which the heat release constant is 760 kJ/mol. (authors)

[en] In order to control the size of small UO₂ micro-spheres, vibration is used to control the dispersion process of liquid jet. The effects of aperture type, diameter and other parameters on the dispersion have been studied. The results show that the aperture with cone-shaped leading hole and small diameter is more beneficial to the realization of uniform dispersion of jet by vibration, as compared with that with cylinder-shaped leading hole and large diameter

[en] The effects of some stochastic factors on the vibration dispersion of liquid jet have been researched. These disadvantageous effects can be reduced and the probability forming uniform dispersion under suitable condition can be raised, if some according measures are taken, for example, to polish the inner surface of the syringe needle capillary; to filter water; to clean the inner part of the syringe needle capillary thoroughly; to avoid surrounding vibration and so on

[en] To improve uranium homogenization of (U-Mo)-Al fuel, the effect of mixing method and compact end shape on uranium homogenization in fuel meat was studied. Mixing contrast experiment of U-Mo powder and Al-Si powder was made by rotating pan mixer and special tridimensional mixer. Three (U-Mo)-Al fuel compacts of different end shape were respectively pressed by using traditional forming mould for flat angle compact and special forming mould for cutting angle compact. Uranium content of mixing powder was determined by oxidation-reduction titration. Uranium homogenization of fuel plate was detected by γ ray absorption method. Microstructure of the fuel meat was observed by optical microscopy. Results were as follows: Compared with two-dimension mixing, mixing extent of powder was increased by tridimensional mixing, which improved uranium homogenization in homogenous zone of (U-Mo)-Al fuel plate greatly, but there was no positive effect for uranium homogenization in dog-bone zone. Fuel compact end shape has a great influence on uranium homogenization of fuel plate 'dog-bone' zone. Fuel plate made of flat angle compact has obvious 'dog-bone'; 'Dog-bone' extent was aggravated in fuel plate made of double-sided cutting angle compact; Meat thickness tended to small at the end of fuel plate meat made of single-side cutting angle compact, and fractured fuel and long trailing phenomenon was not found, the extent of 'log-bone 'was improved obviously. Verification test results showed that uranium homogenization of (U-Mo)-Al fuel plate was improved greatly by using the tridimensional mixing and single-side cutting angle compact; Uranium homogenization in homogenous zone could be controlled in the range of ±12%, and uranium homogenization in dog-bone zone could be controlled in the range of ±20%. (authors)

[en] Due to the different fluidity greatly between U-M_o microsphere fuel particles and aluminum powders, segregation would take place during mixing and loading. In order to reduce segregation and improve the microcosmic uniformity of (U-M_o)-Al dispersion fuel seriously. The various coating process were carried out. The same size stainless steel microspheres were substituted for U-M_o microsphere particles in this paper. Results show that the adding directly binder process and the free falling process are not suitable for coating U-M_o microspheres. The solvent evaporation process can coat a layer of matrix powders on the surface of all U-M_o microsphere, which is feasible for microsphere physical coating. After coating, microsphere surface became uneven, the roughness increase greatly, and the bite force is exist between the particles during flowing, which reduce microsphere fluidity greatly. (authors)

[en] This paper presents a method based on the box dimension of fractal theory to evaluate the distribution uniformity of dispersion fuel phase, and theoretically calculate two kinds of fuel distribution by fractal theory; the one is fuel uniformly distributed, and the other one the ratio of transverse and longitudinal distribution of phase spacing is 1.5. At the same time verified the accuracy of the evaluation method, finally carried out the practical application of research on the established method. The experimental results showed that: in the situation of two kinds of fuel phase distribution, regardless of value of fuel phase volume is big or small, the box dimension value of each distribution is the same, but the values of two kinds are different, this indicated that the box dimension method can evaluate the distribution uniformity of dispersion fuel phase, and has nothing to do with the fuel phase volume; and also showed that the box dimension can accurately distinguish distribution uniformity of dispersion fuel phase, the evaluation method is feasible. (authors)

[en] In order to improve the size distribution and to control the diameter of fine ceramic nuclear fuel microspheres, the dispersion process of sol jet is controlled by vibration; and the corresponding uniform sol drops have been prepared. The uniform fine gel microspheres with different diameters have been fabricated by using carrying-fluid to protect the formed sol drops when the velocity of sol jet and the corresponding vibration frequency are high; the carrying-fluid is not necessary when those are not high. The principle of vibration dispersion of liquid jet has been tested and verified by the diameter measurements of the gel microspheres