TOWARDS A DIAMEX PROCESS FLOWSHEET USING HIGH ACTIVE CONCENTRATE (HAC)
The efficiency of MA recovery in the DIAMEX process has already been demonstrated using HAR. The next step aims at the demonstration of reprocessing from HAC as feed, in view of an industrial application. The volume reduction would reduce the size of the installation and thereby the costs of the process. The first step towards the demonstration of a DIAMEX process using HAC is the production of the genuine solutions. In ITU about 9 L HAR raffinate has been prepared, from PUREX reprocessing of 1.4 kg of MOX fuel, and characterised in order to produce HAC for the upcoming extraction tests. For this purpose, the HAR is subjected to a concentration/denitration process to obtain HAC with a final acidity compatible with the DIAMEX operating conditions, i.e. around 3 M HNO3. This process has been tested and optimised using HAR-simulate. Promising results were found for concentration factors (CF) of 6 to 8. At CF of 39 a significant co-precipitation of lanthanides occurred.
Partitioning of minor actinides from HLLW using the DIAMEX process.Part 2 - ´´Hot´´ continuous counter-current experiment
Among several processes proposed world-wide, the French DIAMEX (DIAMide EXtraction) process seems to be very efficient for the removal of Minor Actinides (MA) from genuine High Level Liquid Waste (HLLW). The MA are in this process directly extracted from the PUREX (Plutonium Uranium Redox EXtraction) raffinate together with fission lanthanides using the completely combustible diamide extractant. In this work a hot demonstration of the DIAMEX process using genuine high-level PUREX raffinate is reported. The continuous counter-current experiment was carried out in a 16 stage centrifugal extractor battery, installed in a hot cell. In order to produce a representative HLLW a PUREX process was applied on dissolved fuel using the same equipment. In the DIAMEX process up to 6 extraction stages were sufficient to achieve feed decontamination factors between 100 and 230 for lanthanides and above 300 for minor actinides. Co-extraction of molybdenum and zirconium were efficiently prevented using oxalic acid scrubbing. The back extraction proved to be very efficient, yielding in 4 stages more than 99.9% recovery of both the lanthanides and the actinides. Co-extracted ruthenium, technetium, palladium and neptunium are less efficiently back-extracted requiring further process development.
Magnetic properties of Lu2Fe17 crystals
Abstract We present the results of crystal structure and magnetization studies of three single crystals grown from melts of different nominal compositions in the vicinity of the Lu2Fe17 stoichiometry. The ferromagnetic state of the crystals is strongly dependent on the real sample composition and the local atomic ordering. A drastic difference is observed in the behaviour of the ferro–antiferromagnetic transition, even in crystals for which almost identical composition and crystal parameters were determined by microprobe and X-ray analysis.