[en] A multiple stage mixer-settler scale-up, for using in CELESTE-I reprocessing installation at IPEN-CNEN/SP, is presented. The mixer-settler CELESTE-I, now used in the extraction process, is not suitable for stripping step, due to the high flow that exceeds its operational limits. At the 1:2 scale-up, the proportionality between the chambers were kept. The evaluation of the mixer-settler, named CELESTE-II, has proved the viability of its use in the extraction process. (author). 5 refs, 7 figs, 3 tabs

[en] Mixer-settler plays important roles in uranium recovery process from phosphoric acid. To flow phosphoric acid from feeder tank to mixer settler, constant fluid flow rate is needed. Therefore, this program selects a pump with positive displacement of reciprocating type having specification of plunger single acting 5 ^x4 triplex, and power 2 HP, to flow phosphoric acid solution with flow rate of 20 kg/s (242 gpm), density of 1300 kg/m³, and viscosity of 4.5 cPo and suction static head of 2 m and discharge static head of 6.4 m. From cavitation evaluation. NPSH available of 8.9 m which waS greater than NPSH required of 4.5 m (specification from pump maker) was obtained. (author)

[en] Testing liquid-liquid extraction flowsheets on radioactive solutions at laboratory scale requires specific contactors, that must be as small as possible (to minimize the quantities of reagents) and suitable for use in glove boxes or hot cells. As such contactors are not commercially available, CEA designs dedicated apparatus for its experiments. Two examples of such contactors are highlighted: a stage-wise one (a miniature mixer-settler) and a differential one (the Taylor-Couette column). Both combine similarities with larger contactors that make possible flowsheet extrapolation to industrial scale, and specific features, mainly because of the major role of materials wettability when volumes are reduced. (authors)

[en] Short communication

[en] In the present invention, a flow of a nuclear fuel solution flowing in a mixer-settler is accurately measured by a neutron monitor to monitor the stability of the flow. A first neutron detector d₁ is disposed near a mixer portion. A second neutron monitor d₂ is disposed at a settler portion at a position sufficiently apart from the mixer portion. In the monitoring method, assuming a counter rate for each of the monitors as C₁, C₂, and the ratio between the counter rates as C₁/C₂=R, R=C₁/C₂ is determined at a standard condition, and normality of the flow is monitored by R(counter rate) or F=(C₁ - C₂/R)/(C₁ + C₂/R). If both of C₁ and C₂/R exceed a predetermined value, an alarm is outputted. In this case, F is an off set factor. Further, if one of them is abnormal, an alarm circuit is bypassed, to inspect the circuit by a neutron source. (I.S.)

No abstract available

No abstract available

[en] The article presents the dry construction mixtures various components polydisperse flow with light and heavy particles rotating layer mechanics numerical and experimental study results. The obtained results allow to control the polydisperse flow layer rotation while it is mixing in the pneumatic mixer chamber working volume. The conditions for estimating the braking parameter of a rotating layer with polydisperse particles on the basis of which the working mixing chamber necessary dimensions can be effectively selected were analytically obtained. (paper)

[en] Bladed mixers are widely used in the industry for granular mixing. In the past decades, the mixing of particles in bladed mixers has been extensively investigated experimentally and numerically. Recently, GPU-based DEM has been employed to simulate various industrial-scale applications. This work aims to apply the GPU-based DEM to investigate the effect of rotation speed and mixer size on granular mixing in bladed mixers of different sizes. The simulation in a larger mixer revealed distinct particle flow patterns that well-describe the mixing mechanism which is difficult to observe in a smaller mixer. The Lacey’s mixing index curves revealed a delay in mixing as the mixer size increases. The mixing rate decreases as the mixer size increases and it can be improved with increasing rotation speed. The average particle velocity increase significantly with increasing rotation speed and mixer size.

[en] Taking into account the advantages of the electrochemical technique and operational features of contactors, type mixer-settler, a new electrolytic extraction equipment is presented. Preliminary studies on electrochemical reduction behavior were carried out with a single stage prototype to set the reliable parameters for the final multistage mixer-settler design (MIRELE). Titanium was the housing material (cathode) and platinum the anode. MIRELE was designed and manufactured at IPEN workshop. After operational tests, the equipment was installed in a glove-box and U/Pu electrochemical partitioning studies were accomplished. The influences of parameters, as hydrazine as scavenger agent in nitric acid medium, current density control in each transference unit and organic and aqueous flow rate on the process efficiency were verified. An uranium separation higher than 99,5% has been achieved. Based on these studies, a flowsheet for spent nuclear fuel treatment was performed, including: an U-Pu co-extraction and scrubbing step, a partial partitioning, followed by final partitioning both using electrochemical Pu reduction, and an uranium reextraction as last step. The product with Pu/U ratio 2,2 times higher than the initial one, with suitable composition for the MOX fuel re-fabrication, has been achieved, showing an important application of the equipment in the new concept of fuel recycling. Also, waste volume reduction, one of the important aspects of the process, has been obtained. Concluding the works, an electrochemical procedure for residual hydrazine decomposition, present in the plutonium product solution, was used to provide a safety operation during the concentration step. (author). 94 refs., 44 figs., 15 tabs