Identification of diluent degradation products in radiolyzed PUREX solvent

Mishra, Satyabrata; Soda, Anil Kumar; Madabhushi, Sridhar; Mallika, C.; Pandey, N. K.; Mudali, U. Kamachi

doi:10.1080/07366299.2017.1417776

Cited by 14 publications

(3 citation statements)

References 17 publications

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“…Within the PUREX process, Zr(IV) can undergo a reaction with the radiolysis products of TBP and alkane diluents, resulting in the formation of a viscous emulsion [ 1 , 2 , 3 ] at the interface of the organic and aqueous phases, commonly known as “crud” [ 4 , 5 ]. The formation of crud not only reduces the recovery and purity of uranium and plutonium but also hastens the decomposition of the extractant, thereby hindering the normal production process [ 6 , 7 ]. Furthermore, the PUREX process yields a considerable quantity of Zr(IV)-containing high-level liquid waste (HLLW), and the presence of Zr(IV) in HLLW could initiate the formation of a third phase during solvent extraction.…”

Section: Introductionmentioning

confidence: 99%

Selective Separation of Zr(IV) from Simulated High-Level Liquid Waste by Mesoporous Silica

Hu,

Bai,

Chen

et al. 2023

Nanomaterials

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The efficient separation of Zr(IV) ions from strong acidic and radioactive solutions is a significant challenge, especially in the context of the aqueous reprocessing of nuclear fuels. The complexity of such solutions, which are often characterized by high acidity and the presence of radioactive elements, poses formidable challenges for separation processes. Herein, several mesoporous silicas (HMS, MCM-41, KIT-6, and SiO2-70 Å) with excellent acid and radiation resistance properties were employed as sorbents to remove Zr(IV) ions from simulated high-level liquid waste. The batch experiments were designed to investigate the influence of adsorption time, HNO3 concentration, initial Zr(IV) concentration, adsorbent dosage, and temperature on the adsorption behavior of Zr(IV). The results indicate that the adsorption equilibrium time of mesoporous silica materials was approximately 8 h, and all the adsorption processes followed the pseudo-second-order kinetics equation. The isotherms of Zr(IV) adsorption by KIT-6 exhibited good agreement with the Langmuir model, while the Freundlich model could be utilized to fit the adsorption on HMS, MCM-41, and SiO2-70 Å. The adsorption capacity of MCM-41 for Zr(IV) in 3 mol/L HNO3 was 54.91 mg/g, which is three times the adsorption capacity reported for commercial silica gel (17.91 mg/g). The thermodynamic parameters indicate that the adsorption processes for zirconium are endothermic reactions. Furthermore, the mesoporous silicas exhibited a pronounced selectivity in the adsorption of Zr(IV) within a simulated high-level liquid waste containing 10 co-existing cations (3 mol/L HNO3). This suggests that mesoporous silicas have great potential for Zr(IV) removal in actual radioactive liquids with high acidity during spent fuel reprocessing.

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Section: Introductionmentioning

confidence: 99%

Selective Separation of Zr(IV) from Simulated High-Level Liquid Waste by Mesoporous Silica

Hu,

Bai,

Chen

et al. 2023

Nanomaterials

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“…e uranium fuel assembly unloaded from the nuclear reactor is called spent fuel. Some organic solvents like ntributyl phosphate (TBP) and diluents, such as paraffin and cyclohexane, are used to recycle uranium from the spent fuel by the application of the Plutonium Uranium Extraction process [1][2][3][4][5][6]. e so-called "red oil" was found following several accidents occurring when organic materials inadvertently get into the equipment and overheat with uranyl nitrate and/or nitric acid at uranium processing facilities.…”

Section: Introductionmentioning

confidence: 99%

“…erefore, researchers studied the degradation of TBP or the thermal reaction between TBP and nitric acid. Smitha et al reported the reaction of TBP with nitric acid at different acid concentrations [12][13][14][15]; the influences of diluents on the reactions and the behaviors of heat emission were also studied previously [5,[16][17][18][19][20][21][22][23]. Nazin et al reported thermal explosions in mixtures of TBP with nitric acid [14,24].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

Tian

Tang

et al. 2020

Journal of Chemistry

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The mechanisms involved in reactions between methane, n-hexane, n-butanol, cyclohexane, and nitric acid were explored by density functional theory calculations. All the calculations in gas phase and n-tributyl phosphate (TBP) solvent were performed at the B3LYP/6–311++G ∗ ∗ and CCSD(T)/6–311++G ∗ ∗ levels of theory. The results showed that TBP has an important effect on the reactions between nitric acid and alkanes or butanol. The reactions were considered as that the radicals (·NO2 and ·NO3 radicals are formed via the HNO3 decomposition under irradiation) initiate the H-atom depletion of the reactants (R), and the produced radicals in red oil combine with ·NO2 radical to form the nitro compounds spontaneously. The rate constants of reactions R + ·NO2 and R + ·NO3 differ substantially, the rate constants of the latter being much larger than those of the former. In the reactions of R + ·NO3, the transition states and products are 20 kJ/mol and 100 kJ/mol or more stable than the reactants, respectively, but the reactions of R + ·NO2 need to overcome energy barriers over 25 kJ/mol. The formations of products mainly depend on the reactions of R + ·NO3. For the same type of alkanes (either chain or cyclic ones), the lower the relative stabilities of carbon-centered radicals are, the more reactive the alkanes are. Cyclohexane is the most competitive species, followed by n-butanol, n-alkanes, and methane which are the least competitive.

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Gamma Radiolysis of n‐Dodecane: Physicochemical Properties and Metal Retention Behavior

Mishra,

Ghosh,

Rajesh

et al. 2024

ChemistrySelect

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The gamma radiolytic degradation behavior of n‐dodecane (n‐DD) was investigated under conditions both with and without the presence of nitric acid. The physicochemical property alterations due to radiolysis were quantified and compared against an unirradiated system. Compositional changes in n‐DD post radiolysis was measured, and the degraded n‐DD was characterized using Fourier‐transform infrared (FT‐IR) spectroscopy, gas chromatography (GC), and gas chromatography–mass spectrometry (GC–MS) analysis. The presence of nitric acid was observed to accelerate the radiolytic degradation of n‐DD. The extent of diluent degradation caused by gamma irradiation was assessed through the retention behavior of uranium [U(VI)], plutonium [Pu(IV)], and zirconium [Zr(IV)] in 1.1 M tri‐n‐butyl phosphate (TBP) in irradiated diluent. Furthermore, the effectiveness of hydrazine carbonate (HC) as a solvent wash reagent for the removal of diluent degradation products was evaluated.

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Identification of diluent degradation products in radiolyzed PUREX solvent

Cited by 14 publications

References 17 publications

Selective Separation of Zr(IV) from Simulated High-Level Liquid Waste by Mesoporous Silica

Selective Separation of Zr(IV) from Simulated High-Level Liquid Waste by Mesoporous Silica

Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

Gamma Radiolysis of n‐Dodecane: Physicochemical Properties and Metal Retention Behavior

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