Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel.A closed-chamber distillation system,in which the pump is stopped and pressurein...Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel.A closed-chamber distillation system,in which the pump is stopped and pressureinduced salt distillation is performed,was arranged for fluoride salt treatment.A stair-step optimization process was demonstrated to improve the recovery efficiency by up to 99%.The pressure change curve was feasible for estimating the distillation process,and a method for displaying the pressure value online in order to determine the endpoint was also developed.The decontamination factor of Nd in the condensate salt was deduced to be greater than 100 with 1 wt%NdF3–FLiNaK distillation.The optimal conditions developed in this study showed a high recovery ratio for the fluoride carrier salt and a high separation efficiency for rare earth products.展开更多
In this study,to further promote the application of the stable carbon isotope natural abundance(SCINA)method to the study of CH4in paddy fields in China,field experiments were carried out to investigate carbon isotope...In this study,to further promote the application of the stable carbon isotope natural abundance(SCINA)method to the study of CH4in paddy fields in China,field experiments were carried out to investigate carbon isotope fractionation during CH4transport in both rice-and non-rice-growing seasons.More importantly,two new methods for the measurement of the CH4transport fractionation factor(εtransport)in paddy fields were introduced.The results indicated that the closed chamber+syringe method was much better for the determination ofεtransport during the non-rice-growing season.Presently,εtransport was calculated using theδ13C value of the CH4emitted from a rice field minus that of the CH4in the floodwater(–6.7‰to–3.0‰).In addition,there were three methods available for estimatingεtransport during the rice-growing season:deduction of theδ13C value of the CH4in the floodwater from that of the CH4emitted from the field(–16.6‰to–15.2‰);deduction of theδ13C value of the CH4in the soil pore water from that of the CH4emitted from the field(–13.2‰to–1.1‰);and deduction of theδ13C value of the CH4in the aerenchyma of plants from that of the CH4emitted from plants(–16.3‰to–10.9‰).Unfortunately,the first two methods showed relatively large uncertainties.Only the last one,the dividing+cutting method,was not only scientific and reliable but also provided accurate measurements.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(No.21771188)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02030000)A study on some key issues regarding the Th-U fuel cycle was also funded(No.QYZDY-SSW-JSC016).
文摘Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel.A closed-chamber distillation system,in which the pump is stopped and pressureinduced salt distillation is performed,was arranged for fluoride salt treatment.A stair-step optimization process was demonstrated to improve the recovery efficiency by up to 99%.The pressure change curve was feasible for estimating the distillation process,and a method for displaying the pressure value online in order to determine the endpoint was also developed.The decontamination factor of Nd in the condensate salt was deduced to be greater than 100 with 1 wt%NdF3–FLiNaK distillation.The optimal conditions developed in this study showed a high recovery ratio for the fluoride carrier salt and a high separation efficiency for rare earth products.
基金supported by the Strategic Priority Research Program- Climate Change: Carbon Budget and Relevant Issues of the Chinese Academy of Sciences (Grant No. XDA05020200)the National Natural Sciences Foundation of China (Grant No. 41071169)+1 种基金the Ministry of Science and Technology of China (Grant No. 2012DFG90290)the Special Fund for Agro-scientific Research in the Public Interest (Grant No. 201103039)
文摘In this study,to further promote the application of the stable carbon isotope natural abundance(SCINA)method to the study of CH4in paddy fields in China,field experiments were carried out to investigate carbon isotope fractionation during CH4transport in both rice-and non-rice-growing seasons.More importantly,two new methods for the measurement of the CH4transport fractionation factor(εtransport)in paddy fields were introduced.The results indicated that the closed chamber+syringe method was much better for the determination ofεtransport during the non-rice-growing season.Presently,εtransport was calculated using theδ13C value of the CH4emitted from a rice field minus that of the CH4in the floodwater(–6.7‰to–3.0‰).In addition,there were three methods available for estimatingεtransport during the rice-growing season:deduction of theδ13C value of the CH4in the floodwater from that of the CH4emitted from the field(–16.6‰to–15.2‰);deduction of theδ13C value of the CH4in the soil pore water from that of the CH4emitted from the field(–13.2‰to–1.1‰);and deduction of theδ13C value of the CH4in the aerenchyma of plants from that of the CH4emitted from plants(–16.3‰to–10.9‰).Unfortunately,the first two methods showed relatively large uncertainties.Only the last one,the dividing+cutting method,was not only scientific and reliable but also provided accurate measurements.
