Neptunium recovery

Table 10.21 Oxidation-reduction potentials at 2S°C in neptunium recovery processes (Chap. 8)...

Figure 10.32 Principal steps in Purex process modified for neptunium recovery. Circles indicate relative volume flow rate -----organic.

Chlorine Chloroprene neptunium recovery Hydrazine nitrate neroli oil, synthetic Geranyl formate nervine, medicine Cinchona extract neurotransmitter... 

Neptunium-237 is obtained as a by-product of making plutonium from uranium isotopes in nuclear reactors. Significant amounts of this element may be recovered from plutonium plant nuclear wastes. Both the recovery and purification of neptunium can be carried out by various chemical processes, including precipitation, solvent extraction and ion exchange. 

Laurinat, J.E. 2006. SASSE modeling of first cycle neptunium(VI) recovery flowsheet. WSRC-TR-2006-00104, Rev.0. 

Zhu, Y., Song, C. 1992. Recovery of neptunium, plutonium and americium from highly active waste. Tri-alkyl phosphine oxide extraction. In Transuranium Elements A Half Century. Morss, L.R. Fuger, J., Eds. ACS, Washington, DC, pp. 318-330. 

Madic, C. Kertesz, C. Sontag, R. Koehly, G. Application of extraction chromatography to the recovery of neptunium, plutonium and americium from an industrial waste, Sep. Sci. Technol. 15 (1980) 745-762. 

Solid Phase Analyses. Portions of the Np solids from several suspensions were removed after 200 days, rinsed and dissolved in HC1. The Np oxidation state analyses of the dissolved solids (Table II) indicate that while the solids from various low pH suspensions contain predominantly Np(IV), high pH suspensions contain Np solids of mixed-Np oxidation states. Even though the TTA values are lower, the sum of the extracted and non-extracted neptunium (relative to the total Np solution concentration) does not account for all the Np. This may indicate that the Np(IV) values could be higher. Recoveries in predominantly Np(V) solutions were nearly 100%. 

A research and development program on the recovery and purification of potentially useful by-product actinides from the nuclear fuel cycle was carried out some years ago in the Federal Republic of Germany as part of the "Actinides Project" (PACT). In the course of this program, procedures for the recovery of neptunium, americium and curium isotopes from power reactor fuels, as well as procedures for the processing of irradiated targets of neptunium and americium to produce heat-source isotopes, have been developed. The history of the PACT Program has been reviewed previously (1). Most of the PACT activities were terminated towards the end of 1973, when it became evident that no major commercial market for the products in question was likely to develop. 

Modifications to this process can be made to effect recovery of neptunium, americium, curium, californium, strontium, cesium, technetium, and other nuclides. The efficient production of specific transuranic products requires consideration of the irradiation cycle in the reactor and separation of intermediate products for further irradiation. 

Actinium and protactinium are present in uranium minerals but recovery is not generally practiced. Neptunium (237Np and 239Np) and plutonium (M9Pu) are present in minute amounts in uranium ores because they result from reaction of neutrons with uranium isotopes, not due to survival from primordial formation. All other actinides are entirely synthetic. Methods of preparation for those up to Cf are given in Table 20-2 syntheses of the other elements are noted in Section 20-18. 

Plutonium is manufactured in megagram quantities neptunium, americium, and curium in kilogram quantities californium in gram amounts berkelium in 100-milligram amounts and einsteinium in milligram quantities. Chemical separations play a key role in the manufacture of actinide elements, as well as in their recovery, and analysis in the nuclear fuel cycle. This collection of timely and state-of-the-art topics emphasizes the continuing importance of actinide separations processes. 

The sucessful experiments for the retention of plutonium onto alumina from TTN0 -HF solution gave enough confidence to recomend the proposed method to separate traces of plutonium from waste solutions in the presence of macroamounts of uranium (VI). Of course, only macroamounts of thorium, uranium (IV) and rare earths are serious interfering ions, since they precipitate with HF. The behavior expected for neptunium in the same system should be similar to plutonium, thorium and rare earths. The retention of neptunium from HNO - HF solutions is in progress. The sorption yield for Pu was around 95%. The sorption mechanism is not well established. Figure 3 shows the proposed flowsheet for recovery of Pu traces from reprocessing waste solutions. 

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