NPEX flowsheet

In UREX+3 process series, the NPEX process follows either CCD-PEG or FPEX. However, prior to NPEX (for recovery of a pure Pu/Np product) there is a significant feed adjustment step. Feed adjust is required to: (1) thermally destroy the reductant/complexant added in the UREX process to suppress extraction of plutonium and neptunium, (2) increase the con­centration of nitric acid, and (3) convert and maintain plutonium and nep­tunium in the extractable (IV) oxidation state.

The CCD-PEG or FPEX raffinate is fed to the NPEX process following feed adjustment as shown in Fig. 7.7 (Pereira, 2007b). The NPEX solvent composition is the same as for UREX, typical PUREX solvent. Impurities are removed from the solvent in the scrub section, and plutonium and neptunium are stripped using the same reductant/complexant that was fed to the scrub section of the UREX process. Uranyl nitrate may be added to

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7.7 NPEX flowsheet.

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7.8 Three-scrub TRUEX flowsheet.

the strip solution to yield a product with a controllable U : Pu ratio, suitable for mixed oxide or metallic fuel fabrication.