Conventional electrolytic methods for separating chemically similar lanthanides(Ln)and actinides(An)are limited by thermodynamics and slow reaction kinetics,restricting their efficiency in rare-earth refining and nucl...Conventional electrolytic methods for separating chemically similar lanthanides(Ln)and actinides(An)are limited by thermodynamics and slow reaction kinetics,restricting their efficiency in rare-earth refining and nuclear fuel recycling.Herein,we report an electroextraction and oxidative back-extraction(EOB)strategy utilizing a LiCl-KCl-KAlCl_(4) molten salt that overcomes these limitations by leveraging divergent interfacial reactivity.The EOB process achieves an exceptional separation factor for Ln/An(>1000),while simultaneously increasing the separation rate by at least one order of magnitude.Through in-situ synchrotron radiation X-ray micro-computed tomography(SR-μCT)and X-ray diffraction(SR-XRD),we capture selective oxidation-induced destabilization of Ln-Al alloys while actinides retain phase stability-directly visualizing the electrochemical alloy transition mechanism.This research redefines the separation of f-block elements in molten salt systems and introduces a multimodal approach to investigating transient interfacial phenomena that are usually inaccessible to conventional metallurgical diagnostics under extreme conditions.展开更多
The corrosion behavior of a titanium-5% tantalum alloy （Ti-STa） in hot nitric acid condensate was investigated to understand aging behavior ofreprocessing equipments. On the basis of long-term immersion tests, it wa...The corrosion behavior of a titanium-5% tantalum alloy （Ti-STa） in hot nitric acid condensate was investigated to understand aging behavior ofreprocessing equipments. On the basis of long-term immersion tests, it was determined that the corrosion of Ti-STa in nitric acid condensate is accelerated with an increase in the concentration. The corrosion rate was nearly constant during the immersion test and the coupons suffered from uniform corrosion. In addition, it is important to note that the nitric acid concentration in the condensate increased on addition of metal salts to the heated nitric acid solution. The larger valence of metal ions was contributed to the increase in the concentration of nitric acid condensate. Consequently, the metal salt in the heated nitric acid solution accelerates the corrosion of Ti-STa in the condensate. Therefore, the nitric acid condensate condition should be carefully considered for the corrosion environment of titanium and its alloys.展开更多
This work investigates an accident during the pyrochemical extraction of Uranium and Plutonium from PWR spent fuel in an argon atmosphere hot cell. In the accident, the heavy metals (U and Pu) being extracted are acci...This work investigates an accident during the pyrochemical extraction of Uranium and Plutonium from PWR spent fuel in an argon atmosphere hot cell. In the accident, the heavy metals (U and Pu) being extracted are accidently exposed to air from a leaky instrument penetration which goes through the cell walls. The extracted pin size pieces of U and Pu metal readily burn when exposed to air. Technicians perform the electrochemical extraction using manipulators through a 4 foot thick hot cell concrete wall which protects them from the radioactivity of the spent fuel. Four foot thick windows placed in the wall allow the technicians to visually control the manipulators. These windows would be exposed to the heat of the metal fire. This analysis determines if the thermal stress caused by the fire would crack the windows and if the heat would degrade the window seals allowing radioactivity to escape from the cell.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(21925603)the National Natural Science Foundation of China(22306185)the China Postdoctoral Science Foundation(2023M732032)。
文摘Conventional electrolytic methods for separating chemically similar lanthanides(Ln)and actinides(An)are limited by thermodynamics and slow reaction kinetics,restricting their efficiency in rare-earth refining and nuclear fuel recycling.Herein,we report an electroextraction and oxidative back-extraction(EOB)strategy utilizing a LiCl-KCl-KAlCl_(4) molten salt that overcomes these limitations by leveraging divergent interfacial reactivity.The EOB process achieves an exceptional separation factor for Ln/An(>1000),while simultaneously increasing the separation rate by at least one order of magnitude.Through in-situ synchrotron radiation X-ray micro-computed tomography(SR-μCT)and X-ray diffraction(SR-XRD),we capture selective oxidation-induced destabilization of Ln-Al alloys while actinides retain phase stability-directly visualizing the electrochemical alloy transition mechanism.This research redefines the separation of f-block elements in molten salt systems and introduces a multimodal approach to investigating transient interfacial phenomena that are usually inaccessible to conventional metallurgical diagnostics under extreme conditions.
文摘The corrosion behavior of a titanium-5% tantalum alloy （Ti-STa） in hot nitric acid condensate was investigated to understand aging behavior ofreprocessing equipments. On the basis of long-term immersion tests, it was determined that the corrosion of Ti-STa in nitric acid condensate is accelerated with an increase in the concentration. The corrosion rate was nearly constant during the immersion test and the coupons suffered from uniform corrosion. In addition, it is important to note that the nitric acid concentration in the condensate increased on addition of metal salts to the heated nitric acid solution. The larger valence of metal ions was contributed to the increase in the concentration of nitric acid condensate. Consequently, the metal salt in the heated nitric acid solution accelerates the corrosion of Ti-STa in the condensate. Therefore, the nitric acid condensate condition should be carefully considered for the corrosion environment of titanium and its alloys.
文摘This work investigates an accident during the pyrochemical extraction of Uranium and Plutonium from PWR spent fuel in an argon atmosphere hot cell. In the accident, the heavy metals (U and Pu) being extracted are accidently exposed to air from a leaky instrument penetration which goes through the cell walls. The extracted pin size pieces of U and Pu metal readily burn when exposed to air. Technicians perform the electrochemical extraction using manipulators through a 4 foot thick hot cell concrete wall which protects them from the radioactivity of the spent fuel. Four foot thick windows placed in the wall allow the technicians to visually control the manipulators. These windows would be exposed to the heat of the metal fire. This analysis determines if the thermal stress caused by the fire would crack the windows and if the heat would degrade the window seals allowing radioactivity to escape from the cell.
