Vaporization and Surface Ionization of LaC2, CeC2, PrC2, NdC2, ThC2 and UC2

The Langmuir vaporization and the surface ionization of LaC₂, CeC₂, PrC₂, NdC₂, ThC₂ and UC₂ from a heated graphite filament have been studied mass spectrometrically. It was found that there were present small amounts of neutral and ionic metal dicarbide molecules in addition to neutral and ionic metal atoms in the LaC₂, CeC₂, PrC₂, ThC₂ and UC₂-C systems with the exception of NdC₂-C, where neither neutral nor ionic metal dicarbide molecules were observed. The reason for this exceptional behavior of the NdC₂-C system is explained by the very small vaporization coefficients, as estimated from the measurements of neutral MC₂/M ratios and ionic MC₂/M ratios.

From the measurements of the heats of vaporization, it was surmised that the ionization potential of Th measured by the surface ionization comparison technique might be too high.     

Energies and E1, M1, E2, M2 transition rates for states of the 2s22p, 2s2p2, and 2p3 configurations in boron-like ions between N III and Zn XXVI

Energies, E1, M1, E2, M2 transition rates, line strengths, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the (1s²)2s²2p, 2s2p², and 2p³ configurations in all boron-like ions between N III and Zn XXVI. Valence, core–valence, and core–core correlation effects were accounted for through single–double multireference (SD-MR) expansions to increasing sets of active orbitals.     

Energies and E1, M1, E2, and M2 transition rates for states of the 2s2p, 2s2p,and 2p configurations in nitrogen-like ions between F III and Kr XXX

Based on relativistic wavefunctions from multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s²)2s²2p³,2s2p⁴, and 2p⁵ configurations in all nitrogen-like ions between F  III and Kr  XXX. The wavefunction expansions include valence, core–valence, and core–core correlation effects through single–double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300–600 cm⁻¹ for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A&A 385 (2002) 716].     

聚酰亚胺中空纤维膜对CO_2、O_2、H_2O和Xe的分离性能

为了富集环境中的氙,使用中空纤维膜对气体进行预处理,去除掉大量的杂质气体,如氮气、氧气、二氧化碳和水蒸气,氙得以浓缩。为此,建立了膜分离实验装置,实验研究了不同的温度、流量、级切、膜数量、连接方式、气源压力等条件下聚酰亚胺中空纤维膜富集氙并去除CO_2、H_2O和O_2等杂质气体的性能。实验结果表明,气体流量和环境温度对膜的分离性能没有明显影响,采用3根或4根膜串联的方式时氙的损失率较小;在级切为2/3时,氙的损失率不大于10%,CO_2、H_2O和O_2的去除率分别不低于99%、90%和90%;空气样品氙的损失率略大于地表下气体样品。     

Breit-Pauli energy levels belonging to 2p, 2s2p, 2p, 2p3? configurations and all E1 transitions among these levels in Mg V

We present accurate oscillator strengths, line strengths and radiative rates for 1073 E1 transitions among the 86 levels belonging to 2s²2p⁴, 2s2p⁵, 2p⁶, and 2s²2p³(⁴S^o, ²D^o, ²P^o)3? configurations in Mg V. We have used 1s and 2s Hartree-Fock orbitals, re-optimized 2p on 2p³(²D^o)3s ³D^o and optimized 3s,3p,3d orbitals on real states. Sixteen additional orbitals up to 8d are optimized either as a correction to n = 3 physical orbitals or as a correlation orbital. A very large set of configurations including up to three electron promotions are used to account for all important correlation effects. All of the main five terms in the Breit-Pauli operator (except the orbit-orbit interaction) are included in order to account for the relativistic effects. Small adjustments to the diagonal elements of the Hamiltonian matrix are made to bring the calculated energies within a few cm⁻¹ of the corresponding NIST recommended data wherever available. The calculated oscillator strengths, line strengths, and radiative rates for almost all of the E1 transitions show excellent agreement with the corresponding MCDF results of Fischer. The recent results of Bhatia et al. are found to be consistently higher by 20-45%. The accuracy of the present calculation is considered to be better than the NIST accuracy ratings for various transitions.     

γ谱法测量环境中的~(210)Pb

介绍了用γ谱仪测量环境中210Pb的分析方法。用醋酸纤维滤膜采集气溶胶样品,或用马林杯直接封装环境水样,在γ谱仪上测量210Pb发射的46.5 ke V射线,通过解谱分析技术获得210Pb的放射性活度。该方法具有快速、非破坏性、无需化学分离及样品处理等优点,但存在低γ发射几率及射线能量低导致的高自吸收等不足,分析的关键在于γ谱仪效率刻度。实验结果表明:γ谱法可用于环境样品中210Pb的放射性活度测量。     

2,2′-联喹啉-N,N′-二氧化物与硝酸钍固态配合物的合成及性质研究

在无水乙醇中制得2,2′-取喹啉-N,N′-二氧化物(BiqO_2)与硝酸钍的固态配合物Th_2(BiqO_2)_3(NO_3)_8。对配合物进行了元素分析,红外光谱、溶解性及摩尔电导、紫外光谱、荧光光谱、X光粉末衍射,差热-热重分析等性质的研究。实验结果表明,在配合物中有桥式和整合式两种类型的配体存在。     

D751螯合树脂吸附铀酰,铜,镍,锌及钴的研究

本文研究了国产的具有亚胺二乙酸功能基的大孔螫合树脂D751对铀酰、铜,镍、锌、钴等5种二价离子的吸附性能。测定了树脂对5种二价离子的吸附量与溶液pH值的关系曲线;测定吸附有二价离子的树脂的红外光谱及螯合物解离pH值(DpH)。     

Results of the QUENCH-L2, DISCO-L2, and COMET-L2 experiments performed within the LACOMERA project at the Forschungszentrum Karlsruhe

The LACOMERA project at the Forschungszentrum Karlsruhe, Germany (FZK) is a 4-year action within the 5th Framework Programme of the EU which started in September 2002. Overall objective of the project is to offer research institutions from the EU Member Countries and Associated States access to four large-scale experimental facilities QUENCH, LIVE, DISCO, and COMET. These facilities are being used to investigate core melt scenarios from the beginning of core degradation to melt formation and relocation in the vessel, possible melt dispersion to the reactor cavity, and finally corium concrete interaction and corium coolability in the reactor cavity. The paper summarizes the main results obtained in the following three experiments:QUENCH-L2: boil-off of a flooded bundle. The test is of a generic interest for all reactor types, provided a link between the severe accident and design basis areas, and would deliver oxidation and thermal hydraulic data at high temperatures.DISCO-L2: fluid-dynamic, thermal, and chemical processes during melt ejection out of a breach in the lower head of a pressure vessel of the VVER-1000/320 type of reactor.COMET-L2: investigation of long-term melt-concrete interaction of metallic corium in a cylindrical siliceous concrete cavity under dry conditions with decay heat simulation of intermediate power during the first test phase, and subsequently at reduced power during the second test phase.     

稀土氧化物Gd2O3、Nd2O3、Sm2O3和Dy2O3在KCl-LiCl-Li2O熔盐中的电解

采用循环伏安法和计时电位法研究了Li₂O在KCl-LiCl熔盐中的电化学行为,并利用卷积伏安法计算了923 K下O₂^-在KCl-LiCl熔盐中的扩散系数（D),得到D=0.5×10^-5 cm²/s。以Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃为阴极,在KCl-LiCl-Li₂O(w=1%)熔盐中进行电解（恒电压3.40 V、电解温度923 K、电解时间25 h）。通过X射线衍射分析(XRD),证实稀土氧化物被部分还原为金属,并分析了电解过程中可能发生的反应。同时利用PRS模型（该模型可将固态阴极内离子的极限扩散速率与固态氧化物孔隙P、金属/氧化物摩尔体积R、阴极还原后的体积收缩率S等参数关联）分析了这些稀土氧化物的电解还原模型,得到Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃的最优孔隙率分别为18.7%、24.2%、30.6%、16.7%,最短电解时间分别为133、157、143、119 h,将这些结果与电解实验结果进行对比,发现阴极的孔隙率和电解时间均不满足金属氧化物完全被还原的要求,并给出了相应的解释。     

Investigation of ThO2 and (U, Th)O2

The effect of the properties of ThO₂ and (U, Th)O₂ powders, prepared with different technological regimes, on the properties of the finished items is investigated. The work includes detailed investigations of ThO₂ and (U, Th)O₂ powders (x-ray phase analysis, electron-microscope investigation) and sintered fuel pellets (determination of density, study of microstructure, thermophysical investigations). The temperature dependences of the crystal lattice parameters and the sizes of the crystallites in ThO₂ and (U, Th)O₂ powders with different UO₂:ThO₂ ratio are obtained. The temperature dependences of the thermal conductivity of sintered ThO₂ and (U, Th)O₂ pellets with different UO₂:ThO₂ ratio are studied.     

Measurement of the cross sections for the reactions Cr(n,2n)Cr, Zn(n,2n)Zn, Y(n,2n)Y and Zr(n,2n)Zr from 13.5 to 14.8 MeV

Cross section measurements for the reactions ⁵²Cr(n,2n)⁵¹Cr, ⁶⁶Zn(n,2n)⁶⁵Zn, ⁸⁹Y(n,2n)⁸⁸Y and ⁹⁶Zr(n,2n)⁹⁵Zr were carried out in the neutron energy range 13.47–14.79 MeV applying the activation technique. Neutrons were produced via the T(d,n)⁴He reaction, making use of the variation of neutron energy with the emission angle. The neutron fluences incident on the samples were determined relative to the well-evaluated cross section for the reaction ⁹³Nb(n,2n)^92mNb.

The induced γ-ray activities of the irradiated Zn, Zr and Y₂O₃ samples and their monitor foils were measured by means of a calibrated Ge(Li) γ-ray detector at the KFI, Debrecen. At the IRK, Vienna, relative γ-ray measurements using a high-purity Ge detector were combined with integral γ-ray counting by means of a NaI(TI) well-type detector on the Cr, Zn and Zr foils of highest activity and on some Nb monitor foils; integral γ-ray counting only was applied in the case of the Y₂O₃ samples. All necessary corrections were taken into account.

The results are compared to the corresponding results of cross section measurements published in the literature. The uncertainties obtained in this work are considerably smaller in most cases than the uncertainties given by other authors.