Purex process flowsheets

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. 

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 Purex Process has been used either with "early" or with "late" Pu-U partitioning (Fig. 1). The early split in the first cycle avoids the co-stripping of uranium and plutonium which may result in higher plutonium losses. In other flowsheets, the partitioning is delayed until the second cycle. While no particular trend has been obvious, some of the recent flowsheets in which the plutonium is reduced prior to re-extraction (10,11) will necessarily require a second cycle partitioning. 

FIG. 21.13. Flowsheet of the first purification cycle in the Purex process TPH, tetrapropylene, is a commercial dodecane. (From Musikas and Schulz.)... 

Already for some years (1991-93) studies have been made for procedures to separate the long-lived actinides from the fission products in the high-level wastes of the PUREX process. The aim of friis work was to develop a flowsheet for a solvent extraction process and the main finding of the last years was that all extractants containing only sulphur are not suitable for the separation of transplutonides (III) from lanthanides (ill). 

It still occupies that position today. Even though the PUREX process is imiversally accepted and used for reprocessing of irradiated nuclear reactor fuel, there is no single PUREX process flowsheet that is imiversally agreed on. Differences exist among PUREX processes and plants in one country, and from coimtry to coimtry. 

The most important TBP process is the PUREX process, in which 20—40 vol/% TBP in the hydrocarbon diluent is used. The flowsheet commonly used in the United States specifies 30 vol/% TBP (Long, 1978). A typical American flowsheet is shown in Figure 14.14. Uranium is extracted from the feed and decontaminated in the first contactor, separated from plutonium in the second contactor, and stripped back into an aqueous phase in the third contactor. A high aqueous phase to organic phase flow ratio... 

Because of the great variety of aqueous waste streams and differences in process flow arrangements in different plants, there is no standard flowsheet for processing aqueous wastes from the PUREX process. Figure 14.15 depicts the principal steps in one possible scheme for concentrating the wastes and recovering water and nitric acid from them. Low-level, low-acid, low-salt wastes are neutralized, if necessary, and concentrated in a simple flash or vapor-compression evaporator to produce LLW concentrates and waste sufficiently decontaminated for return to process. 

FIGURE 2.11 Generic description of the PUREX process. (Based on NBA, Spent nuclear fuel reprocessing flowsheet, OECD Nuclear Energy Agency, Paris, France, NEA/NSC/ WPEC/DOC(2012)15, 2012.)... 

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. 

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. 

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.)... 

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