[en] To understand the spatial distribution of ¹⁴C discharged from Qinshan nuclear power plant, where two HWRs and four PWRs are on commercial operation, simulation using Gaussian plume model was carried out. The predicted values were compared with the measured ¹⁴C results of moss samples collected in 2010. A good fit was found between these two data sets, indicating that the spatial distribution of ¹⁴C follows a Gaussian model. It can be concluded that HWRs are the dominant ¹⁴C sources at Qinshan site and meteorological influences is the leading factor affecting the distribution of ¹⁴C. (author)

[en] To accurately determine "2"4"1Am by mass spectrometry, interfering elements (IEs) including Bi, Hf, Hg, Pb, Pt, Pu and Tl need to be decontaminated. In this study, the extraction behaviors of IEs in HNO_3 and HCl mediums were systematically studied for the employed extraction resins (TRU, DGA-N and DGA-B). Based on the results, chemical separation procedures were proposed. After cooperation with proper co-precipitation methods, the proposed procedures can be used to determine "2"4"1Am in environmental samples. The results of evaluation showed that IEs in soil samples were completely removed and "2"4"1Am was accurately determined for all proposed procedures. (author)

[en] The vertical distribution and migration behavior of ^239+240Pu in a soil core in northern Loess Plateau in Shaanxi Province was investigated. The results showed that the ^239+240Pu activity concentration was in the range of 0.02-0.75 mBq/g. The measured atom ratios of ²⁴⁰Pu/²³⁹Pu in the soil profile varied from 0.179 to 0.201 and were consistent with the typical global fallout. The inventory of ^239+240Pu was 66 Bq/m2 in the sampling site and the proportion of Pu in the first 10 cm top layer accounted for around 75%. The apparent convection velocity and effective dispersion coefficient were 0.19 cm/year and 0.12 cm²/year by the convection dispersion equation model, respectively. Further investigation is still highly required to clarify the dominant factors that control Pu migration. (author)

[en] Microstructure evolution of AZ80 magnesium alloy under isothermal condition is researched by experiment. Effect law of heating temperature and holding time on grain size for AZ80 magnesium alloy is researched. With increasing of holding time and with rising of heating temperature, the grain size increases obviously. According to the test data, the grain growth model of AZ80 magnesium alloy under isothermal condition is established based on Seller’s model, and the activation energy of grain growth of AZ80 magnesium alloy is determined, Q=85900J/mol. The model calculation results are in good agreement with that of experiment, and the relative errors between the model calculation results and that of experiment are less than 15.6%. (paper)

[en] Similar to other high-temperature superconductors, the pinning centers largely determine the critical current density ( J _c) in Co-doped BaFe₂As₂ (Ba122:Co). Therefore, understanding the vortex pinning mechanism of high- J _c Ba122:Co thin films is important for the applications of Ba122:Co. Herein we report the pinning of the naturally grown defects in Ba122:Co thin films with a high critical current density. The transport J _c of thin films is up to 2.6 MA cm⁻² in 9 T at 4.2 K, which is the highest value in iron-based superconductors. Microstructure investigations reveal a high density of ab -planar defects (stacking faults) and localized vertical defects present in the sample. The Dew–Hughes mode analyses prove that pinning centers by surface defects and by point defects are responsible for H // ab and H // c , respectively. Therefore, the high J _c in strong magnetic field for both H // ab and H // c are related to surface and point defects which act as the pinning centers in Ba122:Co films. (paper)

[en] To rapidly assess the contamination of actinides in emergency water, a method was developed to simultaneously analyze U, Th, Pu and Am. The method consists of two steps: extraction chromatographic separation using UTEVA and DGA resins and isotopic determination of actinides by inductively coupled plasma mass spectrometry (ICPMS). The whole analytical procedure takes only 8 h and high chemical recoveries of actinides were obtained. The cross spectral interferences between actinides in ICPMS measurement were sufficiently removed. The accuracy was validated by analyzing IAEA-443 seawater sample. The low limits of detection of actinides allow this method to distinguish low level contamination. (author)

[en] Plutonium is one of the key radionuclides in nuclear decommission. In this study, a rapid method was developed to analyze Pu for concrete samples using total digestion, CaF₂/LaF₃ coprecipitation, extraction chromatography using TEVA and DGA resins, and ICP-MS measurement. The whole analytical process can be achieved within 2 days, with sufficiently high decontamination factors of interfering elements and high Pu chemical recovery (57-93%). The high throughput (22 samples/2 days) and low LODs (0.008 mBq g^-1 for ²³⁹Pu and 0.02 mBq g^-1 for ²⁴⁰Pu) allow this method to effectively detect low level Pu contamination in concrete samples. (author)

[en] New method was developed to analyze Pu and Am sequentially for soil and sediment by inductively coupled plasma mass spectrometry (ICPMS). The developed method uses conc. HNO₃ to leach Pu and Am, Fe(OH)₃ coprecipitation to remove alkali and alkaline metals, extraction chromatographic separation using UTEVA, DGA and TEVA resins to remove interfering elements (IEs) and separate Pu and Am from each other, and sector field-ICPMS to measure Pu and Am. The analysis of four standard reference materials showed that both Pu isotopes and ²⁴¹Am were accurately determined by this method, as a result of its excellent decontamination ability of IEs. Especially the high decontamination factor of Pu [DF(Pu), 4.2 × 10²] in Am fraction and high DF(Am) (7.0 × 10³) in Pu fraction sufficiently eliminated the cross interference between ²⁴¹Pu and ²⁴¹Am in ICPMS measurement. In addition, stable and high chemical recoveries were achieved for Pu (71-91%) and Am (70-88%). The low LODs of Pu isotopes, short analytical time (14 h) and high DFs of IEs allows this method to sequentially analyze Pu and Am, for both global fallout and nuclear accident sourced samples. (author)