Fabrication Technologies for ThO2-based Fuel

Mukerjee, S.K.; Kutty, T.R.G.; Kumar, N.; Pai, Rajesh V.; Kumar, Arun

doi:10.1007/978-1-4471-5589-8_6

Cited by 5 publications

(4 citation statements)

References 86 publications

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“…This work presents the first single-crystal structure of Pu-(C 2 O 4 ) 2 • 6 H 2 O, which is widely used for the precipitation of Pu in the PUREX process, as well as in other fundamental Pu chemistry. The first Th(C 2 O 4 ) 2 • 6 H 2 O crystal structure, another vital compound in the Th fuel cycle, [38] is also reported. The previously reported Np(C 2 O 4 ) 2 • 6 H 2 O and U(C 2 O 4 ) 2 • 6 H 2 O compounds were synthesized and characterized to better compare the An(C 2 O 4 ) 2 • 6 H 2 O series and attempt to resolve discrepancies with the previous work.…”

Section: Discussionmentioning

confidence: 95%

Insight into the Structural Ambiguity of Actinide(IV) Oxalate Sheet Structures: A Case for Alternate Coordination Geometries**

Sockwell

Sweet

Barth

et al. 2023

Chemistry A European J

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Plutonium(IV) oxalate hexahydrate (Pu(C 2 O 4 ) 2 • 6 H 2 O; PuOx) is an important intermediate in the recovery of plutonium from used nuclear fuel. Its formation by precipitation is well studied, yet its crystal structure remains unknown. Instead, the crystal structure of PuOx is assumed to be isostructural with neptunium(IV) oxalate hexahydrate (Np-(C 2 O 4 ) 2 • 6 H 2 O; NpOx) and uranium(IV) oxalate hexahydrate (U(C 2 O 4 ) 2 • 6 H 2 O; UOx) despite the high degree of unresolved disorder that exists when determining water positions in the crystal structures of the latter two compounds. Such assumptions regarding the isostructural behavior of the actinide elements have been used to predict the structure of PuOx for use in a wide range of studies. Herein, we report the first crystal structures for PuOx and Th(C 2 O 4 ) 2 • 6 H 2 O (ThOx). These data, along with new characterization of UOx and NpOx, have resulted in the full determination of the structures and resolution of the disorder around the water molecules. Specifically, we have identified the coordination of two water molecules with each metal center, which necessitates a change in oxalate coordination mode from axial to equatorial that has not been reported in the literature. The results of this work exemplify the need to revisit previous assumptions regarding fundamental actinide chemistry, which are heavily relied upon within the current nuclear field.

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Section: Discussionmentioning

confidence: 95%

Insight into the Structural Ambiguity of Actinide(IV) Oxalate Sheet Structures: A Case for Alternate Coordination Geometries**

Sockwell

Sweet

Barth

et al. 2023

Chemistry A European J

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“…This work presents the first single crystal structure of Pu(C2O4)2•6H2O, which is widely used for the precipitation of Pu in the PUREX process, as well as in other fundamental Pu chemistry. The first Th(C2O4)2•6H2O crystal structure, another vital compound in the Th fuel cycle, 38 is also reported. The previously reported Np(C2O4)2•6H2O and U(C2O4)2•6H2O compounds were synthesized and characterized to better compare the An(C2O4)2•6H2O series and attempt to resolve discrepancies with the previous work.…”

Section: Discussionmentioning

confidence: 95%

Insight into the structural ambiguity of actinide(IV) oxalate sheet structures: a case for alternate coordination geometries

Sockwell

Sweet

Barth

et al. 2023

Preprint

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Plutonium(IV) oxalate hexahydrate (Pu(C2O4)2∙6H2O; PuOx) is an important intermediate in the recovery of plutonium from used nuclear fuel. Its formation via precipitation is well studied, yet its crystal structure remains unknown. Instead, the crystal structure of PuOx is assumed to be isostructural with neptunium(IV) oxalate hexahydrate (Np(C2O4)¬2∙6H2O; NpOx) and uranium(IV) oxalate hexahydrate (U(C2O4)¬2∙6H2O; UOx) despite the high degree of unresolved disorder that exists when determining water positions in the crystal structures of the latter two compounds. Such assumptions regarding the isostructural behavior of the actinide elements have been used to predict the structure of PuOx for use in a wide range of studies. Herein, we report the first crystal structures for PuOx and Th(C2O4)2·6H2O (ThOx). This data, along with new characterization of UOx and NpOx, has resulted in the full determination of the structures and resolution of the disorder around the water molecules. Specifically, we identify the coordination of two water molecules with each metal center, which necessitates a change in oxalate coordination mode from axial to equatorial that has not been reported in the literature. The results of this work exemplify the need to revisit previous assumptions regarding fundamental actinide chemistry, which are heavily relied upon within the current nuclear field.

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“…UO 2 (Et-Tol-BPymDA)(NO 3 )•UO 2 (NO 3 ) 3 (4). A solution of Et-Tol-BPymDA (12 mg, 0.025 mmol) in 2 mL of dichloromethane was mixed with a solution of UO 2 (NO 3 ) 2 •6H 2 O (13 mg, 0.025 mmol) in 2 mL of ethanol.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Facing the ever-growing low-carbon energy demand and ensuring energy security, thorium-based molten salt reactors (TMSRs) for the Gen-IV nuclear reactor system have attracted escalating attention in recent years. , Compared to the well-known uranium-plutonium fuel cycle, the thorium-uranium fuel cycle offers several potential merits, such as high actinide burnup, less long-lived minor actinide production, intrinsic nuclear proliferation resistance, and so forth. , Thorium in the earth’s crust is 3–4 times more abundant than uranium (the worldwide thorium resources amount to 6.35–6.37 million tonnes) and naturally exists in a monoisotopic form of 232 Th, and thus the use of thorium could greatly reduce energy-intensive enrichment activities and mining operations. As the counterpart of 239 Pu in the uranium-plutonium fuel cycle, the fissile nucleus 233 U could be produced via neutron capture on the fertile material 232 Th in breeder reactors , and then separated and recovered during the reprocessing of irradiated thorium for ultimate use as a fuel.…”

Section: Introductionmentioning

confidence: 99%

Selective Complexation and Separation of Uranium(VI) from Thorium(IV) with New Tetradentate N,O-Hybrid Diamide Ligands: Synthesis, Extraction, Spectroscopy, and Crystallographic Studies

Wang

Yang

et al. 2023

Inorg. Chem.

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An unmet challenge in the thorium-uranium fuel cycle is the efficient separation of uranium from thorium. Herein, two new tetradentate N,O-hybrid ligands, N,N′-diethyl-N,N′-di-p-tolyl-2,2′-bipyridine-6,6′-dicarboxamide (Et-Tol-BPDA) and N,N′-diethyl-N,N′-di-p-tolyl-2,2′-bipyrimidine-4,4′-dicarboxamide (Et-Tol-BPymDA), comprising a bipyridine or bipyrimidine core and amide moieties were designed and synthesized for selectively complexing and separating U(VI) from Th(IV). The high U(VI)/ Th(IV) extraction selectivity was achieved by Et-Tol-BPDA (SF U/Th = 33 at 3 M HNO 3 ) and Et-Tol-BPymDA (SF U/Th = 73 at 3 M HNO 3 ) in nitric acid solutions. The extraction process for U(VI) or Th(IV) with these two ligands primarily proceeded through the solvation mechanism, as evidenced by slope analyses. Thermodynamic studies for the extraction of U(VI) and Th(IV) revealed a spontaneous process. Results from UV−vis spectroscopic titration and slope analyses demonstrated that U(VI) and Th(IV) each form a 1:1 complex with the two ligands both in the monophasic organic solution and the biphasic extraction system. The stability constants of the 1:1 complexes of Et-Tol-BPDA or Et-Tol-BPymDA with U(VI) were found to be larger than those with Th(IV), which coincide well with the high U(VI)/Th(IV) extraction selectivity. The solid-state structures of Et-Tol-BPDA, Et-Tol-BPymDA, and 1:1 complexes of the two ligands with U(VI) or Th(IV) were analyzed by X-ray diffraction technique. The results from this work implicate the potential of bipyridine-and bipyrimidinederived diamide ligands for uranium/thorium separation.

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Fabrication Technologies for ThO2-based Fuel

Cited by 5 publications

References 86 publications

Insight into the Structural Ambiguity of Actinide(IV) Oxalate Sheet Structures: A Case for Alternate Coordination Geometries**

Insight into the Structural Ambiguity of Actinide(IV) Oxalate Sheet Structures: A Case for Alternate Coordination Geometries**

Insight into the structural ambiguity of actinide(IV) oxalate sheet structures: a case for alternate coordination geometries

Selective Complexation and Separation of Uranium(VI) from Thorium(IV) with New Tetradentate N,O-Hybrid Diamide Ligands: Synthesis, Extraction, Spectroscopy, and Crystallographic Studies

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