Development of a New Aqueous Process for Nuclear Fuel Reprocessing: Hot Tests on the Recovery of U and Pu from a Nitric Acid Solution of Spent LWR Fuel

Wei, Yuezhou; Arai, Tsuyoshi; Hoshi, Harutaka; Kumagai, Mikio; Bruggeman, A.; Goethals, Patrick

doi:10.13182/nt05-a3591

Cited by 8 publications

(7 citation statements)

References 19 publications

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“…However, a considerable change is observed both in the UV−visible−NIR (Figure ) and in the EXAFS spectra (Figure ), even between 7.7 and 9.0 M HNO 3 samples. This indicates that the speciation is still changing in the higher HNO 3 concentration range above 5 M. It is well-known that An 4+ , including U 4+ , are strongly adsorbed on anion exchangers in the HNO 3 system, in which these tetravalent cations interact with anion exchange functional sites as negatively charged nitrato complexes, such as [An IV (H 2 O) m (NO 3 ) 5 ] − or [An IV (H 2 O) n (NO 3 ) 6 ] 2− . Additionally, several X-ray absorption studies , have proposed the presence of the hexanitrato Pu IV complex, [Pu IV (NO 3 ) 6 ] 2− , in concentrated HNO 3 .…”

Section: Resultsmentioning

confidence: 99%

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

et al. 2009

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In order to elucidate the uranium solution chemistry at the high HNO(3) concentrations typically employed for the reprocessing of spent nuclear fuels, speciation and complex structures of U(IV) and U(VI) are studied in aqueous HNO(3) solutions, as well as in HClO(4) solutions, by means of UV-visible-near-infrared and X-ray absorption spectroscopies and density functional theory calculations. In 1.0 M HClO(4), U(IV) exists as a spherical cation of U(4+), which is surrounded by 9-10 water molecules in the primary coordination sphere, while it forms a colloidal hydrous oxide, U(IV)O(2) x nH(2)O, at a lower acidic concentration of 0.1 M HClO(4). U(VI) exists as a transdioxo uranyl cation, UO(2)(2+), and forms a 5-fold pure hydrate complex of [U(VI)O(2)(H(2)O)(5)](2+) in 1.0 M HClO(4). With increasing HNO(3) concentration, the water molecules of the U(IV) and U(VI) hydrate complexes are successively replaced by planar bidentate coordinating nitrate ions (NO(3)(-)), forming dominant species of [U(IV)(H(2)O)(x)(NO(3))(5)](-) in 9.0 M HNO(3) and [U(VI)O(2)(NO(3))(3)](-) in 14.5 M HNO(3), respectively. The present multitechnique approach also suggests the formation of two intermediate U(VI) species, a 5-fold mononitrato complex ([U(VI)O(2)(H(2)O)(3)(eta(2)-NO(3))](+)) and a 6-fold dinitrato complex ([U(VI)O(2)(H(2)O)(2)(eta(2)-NO(3))(2)](0)), involving an increase in the total coordination number on the uranyl(VI) equatorial plane from 5 to 6 with increasing HNO(3) concentration. The presence of unidentate coordinate nitrato complexes or tetranitrato U(VI) complexes is less probable in the present HNO(3) system.

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Section: Resultsmentioning

confidence: 99%

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

et al. 2009

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“…A high efficiency separation is necessary to partition long-lived radioisotopes for transmutation and to greatly reduce the requirements of long-term storage of high-level-waste. Several groups have investigated embedding organic resins in porous silica beads to achieve a separation [11][12][13], while others have assessed inorganic ion exchangers [14][15][16], both routes have shown mild success but leave room for improvement in this delicate separation. Herein we investigate the oxidation-state specific interactions of selected lanthanides and actinides to establish the selectivity of the porous Zr(IV) and Sn(IV) phosphates we have synthesized and evaluate the extent to which these extractants could be useful in the separation of trivalent actinides and lanthanides.…”

Section: Introductionmentioning

confidence: 99%

Pillared metal(IV) phosphate-phosphonate extraction of actinides

Burns

Clearfield²,

Borkowski

et al. 2012

Radiochimica Acta

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Four pillared metal(IV) phosphate-phosphonate ion exchange materials were synthesized and characterized. Studies were conducted to determine their affinity for the lanthanides (Ln's) and actinides (An's). It was determined that by simply manipulating the metal source (Zr or Sn) and the phosphate source (H 3 PO 4 or Na 3 PO 4 ) large differences were seen in the extraction of the Ln and An species. K d values higher than 4 × 10 5 were observed for the AnO 2 2+ species in nitric acid at pH 2. These basic uptake experiments are important, as the data they provide may indicate the possibility of a separation of Ln's from An's or even more notably americium from curium and Ln's.

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“…It was found that U and Pu were also adsorbed by the adsorbent and efficiently eluted off by H2O together with the MA. Since the spent fuel solution was once reduced by electroreduction prior to the anion exchange separation process, the valence representations of U and Pu in the MA-Ln effluent were considered to be U(IV) and Pu(IV) or Pu(III), respectively [16]. From this experimental result, we can conclude that the U and Pu that remained in MA-Ln effluent could be effectively recovered together with the MA.…”

Section: Chromatographic Separation Of Am(iii) From Ln(iii)mentioning

confidence: 97%

“…The HLLW sample solution containing 6 M of HNO 3 was generated from the anion exchange process that had separated the U, Pu, Pd, Ru, and Tc from a spent LWR fuel solution [12,16]. Prior to the separation of MA/Ln, the HLLW sample was fed to a CMPO/SiO 2 -P packed column for the elemental group partitioning according to the procedure shown in Figure 1.…”

Section: Hot Column Separation Experimentsmentioning

confidence: 99%

Separation of Minor Actinides from High-Level Liquid Waste Using Novel Silica-Based Butyl-BTP Adsorbents

Jiang

Ning

et al. 2022

Toxics

Self Cite

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To separate the long-lived minor actinides (MA = Am, Cm) from high-level liquid waste (HLLW), we have been studying an advanced separation process via selective adsorption that uses minimal amounts of organic solvent and compact equipment. The process consists of two separation columns packed with a CMPO (octyl(phenyl)-N,N-diisobutylcarbamoyl-methyl phosphine oxide) adsorbent for elemental group separation and a soft-donor named the R-BTP (2,6-bis-(5,6-dialkyl-1,2,4-triazine-3-yl) pyridine) adsorbent for the isolation of MA from lanthanides (Ln). In this work, the effects of nitrate ion (NO3−) on the adsorption behavior of Am(III) and a typical fission product Ln(III) onto the isoBu-BTP/SiO2-P adsorbent were studied experimentally. Then, the desorption properties of the adsorbed element were examined using different eluting agents. A hot test for the separation of MA from the fission product Ln in a genuine MA containing effluent from the irradiated MOX-fuel treatment process was carried out using a nBu-BTP/SiO2-P packed column. It was found that the separation factor between Am(III) and Ln(III)-FP is over 100 in the measured 0.5–4 M NO3−. The adsorbed elements could be effectively eluted off using a complexing agent such as DTPA or pure water. Complete separation between MA and Ln was achieved in the column results, indicating that the proposed MA separation process is feasible in principle.

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Development of a New Aqueous Process for Nuclear Fuel Reprocessing: Hot Tests on the Recovery of U and Pu from a Nitric Acid Solution of Spent LWR Fuel

Cited by 8 publications

References 19 publications

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Pillared metal(IV) phosphate-phosphonate extraction of actinides

Separation of Minor Actinides from High-Level Liquid Waste Using Novel Silica-Based Butyl-BTP Adsorbents

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