Purex flowsheets

Fox, O.D., Jones, C.J., Birkett, J.E. et al. 2006. Advanced PUREX flowsheets for future Np and Pu fuel cycle demands. In Separations for the Nuclear Fuel Cycle in the 21st Century. Lumetta, G.J. et al. Eds. ACS Symposium Series Vol. 933, American Chemical Society, Washington, DC, pp. 89-102. 

Jenkins, J.A., Mills, A.L., Thompson, P.J., Jubin, R.T. 1993. Performance of centrifugal contactors on uranium and plutonium active PUREX flowsheets. In Solvent Extraction in the Process Industries ISEC 93, York, UK, September 16-21. Logsdail, D.H., Slater, M.J. Eds. Elsevier Applied Science, London and New York. 

For large-scale purification, the Purex Plant solvent extraction bank was used first to separate Am-Cm from the Pu in the target element and then to separate Am-Cm from the A1 in the target element. In each of the four campaigns that have been processed, the Pu in the target element has been purified by the normal Purex flowsheet. In each case, the Am-Cm fraction was initially rejected to the waste (1AW) stream. 

Under similar conditions to those under which Np(V) is photogenerated from Np(IV) and/or Np(VI) (Eqs. 16-20), Pu(III), (IV) (VI) are photo-chemically converted to Pu(IV) and (VI) while all U species are ultimately converted to UC>22+. Pu(IV), Pu(VI) and U(VI) are extractable into TBP while Np(V) is not thus, this suite of reactions may form the basis of a process for Np separation. Within an advanced PUREX flowsheet, this would find utility at the point of fission product removal, the Np being routed with the HAW stream. 

At low pH, Pu(III) and Pu(IV) are photo-oxidised to Pu(VI) in UV-irradiated urea/nitric acid solutions while Np(VI) is generated from Np species under identical conditions. As both Pu(VI) and Np(VI) are extractable into TBP/diluent, UV treatment in the presence of urea could potentially be used for the co-extraction of Np and Pu in a revised PUREX flowsheet [96]. 

Hydrazine and hydroxylamine nitrate (HAN) are two other common additives for revised PUREX flowsheets. In the presence of hydrazine/ HAN, Pu(III) is converted to Pu(IV) in UV-irradiated nitric acid solutions. In the dark, Np(V) is reduced to Np(IV) by both HAN and hydrazine, but the rates are slow [97,98] ... 

The above information was used to develop conceptual flowsheets for the extraction of all of the actinides (U, Np, Pu, Am, and Cm) from high-level liquid waste from PUREX processing using 0.4 M 0fuel using 0.8 M DHDECMP in DEB. In both flowsheets, no oxidation state of Pu is necessary since the III, IV, and VI state extract into the organic phase. 

Draw a flowsheet for the Purex process like Figure 16.10. Estimate the relative volumes of all streams in the process using data from the references cited in the text. 

Many variants of the Purex (Plutonium Uranium Reduction Extraction) process23S based on TBP extraction have been developed but a basic outline flowsheet is illustrated in Figure 38. This shows the so-called early split flowsheet most commonly used in existing plants. It involves the separation of the uranium and plutonium using two different back-extractant streams during the first solvent extraction cycle. Additional solvent extraction cycles are then carried out independently on the uranium and plutonium streams to effect further purification. An alternative arrangement is the iate split flowsheet used at the Cap La Hague plant in France, and the... 

Optimize each application of PUREX and the overall process to attain sufficiently improved performance by refinement of flowsheet conditions using reliable and accurate software (i.e., database and simulation code) and by sophistication of process-control methods. 

Thanks to these promising results, two hot tests were further carried out in the hot cells of the ITU (181, 182) on a genuine highly active PUREX raffinate obtained by reprocessing 500 g of a U02 commercial reactor spent fuel (60 GWd/t). Oxalic acid and HEDTA were added to the PUREX high-activity raffinates, and its acidity was adjusted to 4.4 M. The flowsheet tested was... 

FIGURE3.14 TODG A/TBP process flowsheet tested at the FZ J on a surrogate PUREX raffinate. (Courtesy of Modolo, G., Asp, H., Vijgen, H., Malmbeck, R., Magnusson, D., Sorel, C., Global 2007 Advanced Nuclear Fuel Cycles and Systems, September 2007, Boise, ID.)... 

FIGURE 3.24 SETFICS process flowsheet tested by JNC on an inactive surrogate PUREX raffinate. (Courtesy of Hirano, H., Koma, K., Koyama, T., 7th Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation, October 2002, Jeju, Republic of Korea.)... 

FIGURE 3.26 DIAMEX-SANEX/HDEHP process flowsheet tested at the CEA Marcoule on a genuine PUREX raffinate. (Courtesy of Madic, C., Lecomte, M., Baron, P., Boullis, B., Compte-Rendu de Physique, 3, 797-811, 2002.)... 

After a few years of storage, the main radioactive heat emitters in HLW are 90Sr and 137Cs. In addition, extremely long-lived actinides—neptunium, plutonium, americium, and curium—should be collected for transmutation in the future. Therefore, different flowsheets can be proposed for waste processing. It is possible to extract each radionuclide in the special extraction (sorption) cycle, for example, uranium and plutonium in the PUREX process, and after that, minor actinides (MAs) by the TRUEX process,4 strontium by the SREX process,5,6 and cesium by sorption7 or extraction.8... 

The flowsheet of the UREX process, developed in the United States, includes the following extraction cycles (1) separation of uranium and technetium, (2) separation of plutonium, (3) separation of cesium and strontium, (4) separation of MAs and Rare Earth Elements (REE), and (5) group separation of MA from REE metals.9,10 Flowsheet development in Europe11 includes a modified PUREX process and, after that, the DIAMEX process for separation of MAs and lanthanides, the SANEX process for separation of MAs from lanthanides, and a special cycle for Am/Cm separation. Cesium and strontium will be in the raffinate of the DIAMEX process, and this raffinate will be vitrified, or cesium can be preliminarily extracted.12... 

The CTH actinide separation process was developed as a possible means to reduce the expected long term dose to man from a geologic repository containing solidified radioactive waste from the reprocessing of spent nuclear fuel The distribution data for the elements present in significant amounts in the high level liquid waste (HLLW) from a Purex plant, the general principles and the flowsheet have been described in detail elsewhere A... 

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