Polymer supported calix[6]arene hydroxamic acid, a novel chelating resin

A new polymer-supported calix[6]arene hydroxamic acid has been synthesised by reacting the acid chloride 37,38,39,40,41,42 hexahydroxy 1,8,13,19,25,31 hexacarboxy calix[6]arene with poly(styrene β-hydroxylamine). The synthesised resin was characterised by elemental analysis, FT-IR and mass spectra. Physicochemical properties viz. swelling, wet-density, void-volume, exchange capacity etc. were determined. The resin has 4.46 mmol/g exchange capacity for rare elements. The resin was used for the chromatographic separation of U(VI), Th(IV) and Ce(IV) by the judicious adjustment of pH 4.0, 6.0 and 7.5, respectively. The thorium and cerium were eluted with 0.1 M HCl while uranium was eluted with 2 M HCl. These rare elements were preconcentrated and determined in the presence of each other, monazite sand and environmental samples.     

基于GPU的三维扩散方程在反应堆计算中的应用

本文介绍了基于统一计算设备架构(Compute Unified Device Architecture, CUDA)的图形处理器(Graphic Processing Unit, GPU)计算环境在钍基熔盐堆(Thorium Molten Salt Reactor, TMSR)设计平台的建立,并将反应堆球场计算软件SRAC (Structure Research and Analysic Corporation)的中子三维扩散计算模块移植到GPU上进行测试及结果验证。采用中心点差分方法推导出三维扩散计算的差分方程,并用超松弛迭代法(Successive Over Relaxation Method, SOR)求解φ,研究了SOR迭代算法的并行实现过程。结果表明,移植的GPU模块部分计算正确,计算速度得到有效提升,验证了TMSR设计平台在GPU计算环境下可正常工作。     

Thorium partitioning in Greek industrial bauxite investigated by synchrotron radiation and laser-ablation techniques

Typical red-brown (Fe-rich) and high-quality white-grey (Fe-depleted) bauxite samples from active mines of the Parnassos-Ghiona area, central Greece, were investigated. According to XRF and ICP-MS analyses their actinide content, and particularly of Th, is relatively increased. Fe-depleted samples contain up to 62.75 ppm Th corresponding to 220 Bq/kg due to ²²⁸Ac (²³²Th-series), whereas Fe-rich samples are less Th-radioactive (up to 58.25 ppm Th, 180 Bq/kg due to ²²⁸Ac). Powder-XRD patterns showed that Th-enriched (Fe-depleted) bauxite consists mostly of diaspore (AlOOH polymorph), anatase and rutile (TiO₂ polymorphs). SEM-EDS indicated the presence of Ti-Fe-containing phases (e.g. ilmenite, FeTiO₃), chromite (Cr-spinel) and besides LREE-minerals (mostly bastnäsite/parisite-group) and zircon (ZrSiO₄) hosting a part of the bulk Th. The presence of Th in diaspore and in Ti-containing phases (not detected by SEM-EDS as in the case of REE-minerals and zircon) was investigated, into distinct pisoliths of Fe-depleted bauxite, using μ-XRF and μ-XAFS in the SUL-X beamline of the ANKA Synchrotron facility (KIT, Germany). XAFS spectra of Th salts and Th-containing reference materials were obtained as well. Accordingly it was revealed, for the first time in the literature, that Ti-phases, and particularly anatase, host significant amounts of Th. This novel conclusion was complementary supported by LA-ICP-MS analyses indicated an average of 73 ppm Th in anatase grains together with abundant Nb (3356 ppm), Ta (247 ppm) and U (33 ppm). The Th L_III-edge XAFS spectra as compared to reference materials, give also evidence that Th⁴⁺ may not replace Ti⁴⁺ in distorted [TiO₆] fundamental octahedral units of anatase and ilmenite lattice (CN = 6). The occupation of either extraframework sites of higher coordination (CN = 6.9 or even CN = 7.4), according to EXAFS signals evaluation, or of defected/vacant (**) sites is more probable. This is likely explained by the difficulty of Th⁴⁺ to replace directly Ti⁴⁺ in [6]-coordinated (octahedral) sites due to the large difference in the relevant ionic radii (0.940 and 0.605 Å respectively).     

Plutonium management with thorium-based fuels and inert matrix fuels in thermal reactor systems

The plutonium that is produced by light water reactors worldwide is currently re-used to a limited extent. In the last century, the expected introduction of fast reactors and the associated need for large amounts of plutonium did not take place. The result is that worldwide a stockpile of excess plutonium has formed, which is the dominant contributor to the radiotoxicity of spent nuclear fuel for storage times from 10² to 10⁵ years. One option to reduce or stabilize the plutonium stockpile is to utilize this plutonium in advanced fuel types, such as thorium-based and inert matrix fuels. Because these fuels do not contain uranium, the plutonium consumption rate is very high. In this paper, the status of the fuel research and some recent developments are given.     

圆柱氧化钍装置上的中子及伽马穿透能谱实验测量

利用D-T中子对氧化钍圆柱装置进行了辐照。样品直径为30 cm、厚度为15 cm。在不同的布局状态下,采用芪晶体闪烁体基于反冲质子法对1 MeV~15 MeV中子能谱进行了实验测量;基于反冲电子法对中子辐照下和辐照后的0.5 MeV以上伽马能谱进行了测量。对能谱中的分布规律、与布局状态的关系进行了比对分析。     

Heterogeneous distribution of radionuclides, barium and strontium in phosphogypsum by-product

Phosphogypsum (PG) is a high volume by-product of the phosphate fertilizer industry which is composed mainly of CaSO₄·2H₂O. Impurities in PG include F, trace elements and naturally-occurring radionuclides. Radium-226 content is sufficiently high in some PGs that it has limited PG usage in building materials and as an amendment to agricultural soils. Radium likely exists in PG as a sulfate solid solution with Ba, and possibly Sr. This study determined the distribution of ²²⁶Ra, Ba, Sr, U, Th and ²¹⁰Pb among three size fractions (fine: <20 μm; medium: 20–53 μm; coarse: >53 μm) in PGs derived from three different phosphate rock sources. All chemical species, except for Sr in PG derived from Idaho rock, were enriched in the <20-μm fraction relative to the other size fractions and relative to unfractionated PG. On average, fine fraction ²²⁶Ra and ²¹⁰Pb contents were enriched approximately sixfold over unfractionated PG. ²²⁶Ra was enriched in the fine fraction to a greater degree than were Ba or Sr, indicating that Ra behavior in PG is distinct from these other elements. The combination of (i) particle sorting during PG deposition, and (ii) non-uniform distribution of radionuclides in PG, may contribute to radionuclide heterogeneity at PG repositories.     

1,9-双(1''''-苯基-3''''-甲基-5''''-氧代吡唑-4''''-基)壬二酮-[1,9]与TOPO协同萃取钍(Ⅳ)机理的研究

一、前言 1,9-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)壬二酮-[1,9] (简称H_2A)为新近合成的一种双-β二酮螯合剂,它较HPMBP类试剂多一倍螯合功能团,不但能与钍(Ⅳ)形成较稳定的可萃络合物,而且还能与某些中性萃取剂产生协萃作用。本文以氯仿为溶剂研究了它对钍(Ⅳ)的单独萃取及它与三辛基氧膦(TOPO)协同萃取钍的作用,测得了萃合物的组成为ThA_2·TOPO。求得单独萃取和协同萃取反应的平衡常数分别为β_(20)=1.03×10~8和β_(21)=1.18×10~9。     

The ternary thorium aluminium carbides Th2Al2C3 and ThAl4C4

The title compounds were prepared by are-melting cold-pressed pellets of the elemental components with subsequent annealing at 900°C. Th₂Al₂C₃ crystallizes orthorhombic: Pnnm, a = 540.6(1) pm, B = 1155.6(2) pm, C =3 52.01(6) pm, Z = 2. The structure was determined from powder diffractometer data using the Rietveld method: R_F = 0.039 for 42 structure factors and six variable positional parameters. The positions of the metal atoms correspond to those of the InS-type structure. The two different carbon atoms are in octahedral coordination formed by four thorium and two aluminium atoms. The hydrolysis of ThAl₄C₄ with diluted hydrochloric acid resulted in 74 wt.% methane, 12 wt.% ethane and ethylene and 14 wt.% saturated and unsaturated higher hydrocarbons. Nevertheless, the crystal structure determination from single-crystal X-ray data showed that there are only isolated carbon atoms in the solid: I4/m, a = 823.1(1) pm, C = 332.72(6) pm, Z = 2, R = 0.032 for 13 variable parameters and 372 structure factors. It is isotypic with UCr₄C₄. The carbon atoms are octahedrally coordinated by two thorium and four aluminium atoms.     

Transition toward thorium fuel cycle in a molten salt reactor by using plutonium

The molten salt reactor(MSR), as one of the Generation Ⅳ advanced nuclear systems, has attracted a worldwide interest due to its excellent performances in safety, economics, sustainability, and proliferation resistance. The aim of this work is to provide and evaluate possible solutions to fissile 233 U production and further the fuel transition to thorium fuel cycle in a thermal MSR by using plutonium partitioned from light water reactors spent fuel. By using an in-house developed tool, a breeding and burning(BB) scenario is first introduced and analyzed from the aspects of the evolution of main nuclides, net 233 U production, spectrum shift, and temperature feedback coefficient. It can be concluded that such a Th/Pu to Th/~(233)U transition can be accomplished by employing a relatively fast fuel reprocessing with a cycle time less than 60 days. At the equilibrium state, the reactor can achieve a conversion ratio of about 0.996 for the 60-day reprocessing period(RP) case and about 1.047 for the 10-day RP case.The results also show that it is difficult to accomplish such a fuel transition with limited reprocessing(RP is 180 days),and the reactor operates as a converter and burns the plutonium with the help of thorium. Meanwhile, a prebreeding and burning(PBB) scenario is also analyzed briefly with respect to the net 233 U production and evolution of main nuclides. One can find that it is more efficient to produce 233 U under this scenario, resulting in a double time varying from about 1.96 years for the 10-day RP case to about 6.15 years for the 180-day RP case.