核反应总截面和奇异结构研究

本总结了晕和皮等奇异核子结构研究的现状,介绍了发现晕和皮现象的实验证据。然后集中介绍了利用奇异核反应总截面的实验测量和理论模型,从中提取奇异核物质半径,核内核子分布以及介质中的核子－核子碰撞截面等重要信息,我们将特别强调通过实验测量和理论模型之间的联系来研究奇异结构性质。     

New Calix[4]arene-monobenzo- and -dibenzo-crown-6 as Cesium Selective Ionophores in the Radioactive Waste Treatment: Synthesis, Complexation and Extraction Properties

Cesium possesses two long lived isotopes ¹³⁵Cs and ¹³⁷Cs and the first one has a very long (2.3 × 10⁶ y) half life and is one of the most mobile nuclides in a repository.Calix[4]arene-crowns-6 in the 1,3-alternate conformation areemerging as a new class of ionophores exhibiting a very high efficiency and selectivity in the complexation of cesium ion and itsremoval from highly acidic ([HNO₃] = 3–4 M) radioactive waste having also high sodium nitrate concentration ([NaNO₃] = 2–4 M). In order to improve both efficiency and cesium selectivity we have synthesised the novel calix[4]arene dibenzo-crowns-6 1 and 2 and thecalix[4]arene-monobenzocrown-6 3 in 1,3-alternate conformationand evaluated their complexation properties towards alkali metal cations in homogeneous solution and in two phase systems, togetherwith their performance in radioactive waste treatment. All data confirm the higher Cs/Na selectivity of the 1,3-alternate calix[4]crown-6 1–3 containing aromatic rings in the polyether loop, in comparison to previously synthesised compounds of the same series.     

Methods of high-sensitive analysis of actinides in liquid radioactive waste

A set of methods has been developed to determine actinides in liquid radioactive waste for solving the problems of radiation, nuclear and ecological safety of nuclear reactors. The main method is based on the radiochemical separation of U, Np–Pu, Am–Cm on ion-exchange and extraction columns. An identification of radionuclides and determination of their content are performed using alpha-spectrometry. The microconcentrations of the sum of the main fissile materials ²³⁵U and ²³⁹Pu are determined with plastic track detectors. An independent method of ²³⁸U content determination is the neutron activation analysis. ²⁴¹Am content is possible to be determined by gamma-spectrometry. A chemical composition of macrocomponents is determined by the atomic-absorption spectrophotometry method.     

A Proposed Storage Ion Trap of an ‘In-Flight Capture’ Type for Precise Mass Measurement of Radioactive Nuclear Reaction Products and Fission Fragments

Data on nuclear masses provide a basis for creating and testing various nuclear models. A tandem system comprised of the U-400M cyclotron, the COMBAS magnetic separator and the mass spectrometric ion trap of an ‘in-flight capture’ type is considered as a complex for producing of the short-lived nuclei by heavy ions in fragmentation reactions and for precise mass measurement of this nuclei. The FLNR plan scientific and technical research includes a project DRIBs for producing accelerated beams of radioactive nuclear reaction products and photofission fragments. This project proposes also precise mass measurements with the help of ion trap. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tagungen

The extraction of uranium as well as Eu-(152 + 154), Co-60, Ru-103 and Cs-137 by di(2-ethylhexyl) phosphoric acid (HDEHP), tricaprylmethyl ammonium chloride (Aliquate-336) and tricapryltertiaryamine (Alamine-336) in kerosene from aqueous nitrate medium of constant ionic strength, 0.6 (H+, NaNO₃) was investigated. The aqueous phase used is a representative medium for certain medium level waste (MLW) solutions. The obtained results indicate that HDEHP system is more suitable for the separation of U(VI) and Eu(III) from Ru(III), Co(II) and Cs(I). Using HDEHP loaded on XAD-4, chromatographic extraction was applied successfully for the recovery of uranium and Eu(152+154) from the aforementioned solution.

Die Extraktion von Uranium wie auch von Eu-(152 + 154), Co-60, Ru-103 und Cs-137 durch Di(2-ethylhexyl) phosphorsäurc (HDEHP), Tricaprylmethylammoniumchlorid (Aliquate-336) und Tricapryl tertiäramin (Alamin-336) in Kerosin aus wäβrigen Nitratlösungen bei einer konstanten Ionenstärke von 0,6 (H+, NaNO₃) wurde untersucht. Die verwendete wäβrige Phase ist für eine mittelaktive Abfallösung (MLW) repräsentativ. Die Ergebnisse zeigen, daβ das HDEHP-System geeigneter zur Abtrennung des U(VI) und des Eu(III) vom Ru(III), Co(II) und Cs(I) ist. Bei Verwendung eines HDEHP-beladenen Austauschers (XAD-4) konnte eine chromatographische Extraktion zur Rückgewinnung des Uraniums und des Eu-(152 + 154) von der oben erwähnten Lösung erfolgreich angewendet werden.     

中国的泥土疗法:治病篇(一)

泥土疗法过去属于民间疗法,现已成为回归自然的时尚和保健治病的手段.从文献记述、临床应用、机理探索和成分解析四个方面论述了中国泥土疗法的发展历程和科学基础.分两期刊出.     

Dose assessment of bremsstrahlung induced by beta-emitting radioisotopes of uranium-238 series and lead in human tissues

In the natural uranium-238 decay series, pure beta isotopes such as ²³⁴Th, ²³⁴Pa, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb and ²¹⁰Bi are released. The few lead isotopes such as ²¹¹Pb, ²¹²Pb, ²¹³Pb and ²¹⁵Pb are good beta emitters. In certain nuclear reactions of reactor these isotopes are released. These beta isotopes have maximum beta energies, which induce the bremsstrahlung radiation. The bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. The shapes of bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. The bremsstrahlung spectra produced by these high-energy isotopes such as ²³⁴Th, ²³⁴Pa, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb, ²¹⁰Bi, ²¹¹Pb, ²¹²Pb, ²¹³Pb and ²¹⁵Pb in bone, muscle and teeth are studied, and the computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth–dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The evaluated beta bremsstrahlung dose as a function distance for the studied nuclides is also presented. The efficiency, intensity and dose rate of bremsstrahlung induced by beta isotopes of natural uranium-238 decay series and beta-emitting lead isotopes in human tissues such as brain, breast, heart, kidney, liver, muscle, pancreas and bone have also been studied in the present investigation. The values of bremsstrahlung dosimetric parameters are low for pancreas, but they are high for bone. For all studied tissues these parameters are high for ²³⁴Pa, but low for ²¹⁰Pb.     

Environmental and radio-ecological studies on shallow marine sediments from harbour areas along the Red Sea coast of Egypt for identification of anthropogenic impacts

Analysis of marine sediments of the studied localities provides investigators with data to characterise the composition of these sediments allowing for the identification of particular pollution sources. A study of texture, geochemistry, X-ray diffraction and natural radionuclide content of shallow marine sediments from Quseir harbour, Safaga harbour and El-Esh area in the Red Sea coast of Egypt was conducted for the purpose of assessing the possible influence of human activities on the composition of the sediments. The activity concentrations of the naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K were measured by using γ-ray spectrometry. The mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in all areas studied were found to be 71±6, 66±5 and 92±7 Bq kg^?1 for ²²⁶Ra, 83±5, 71±7 and 162±23 Bq kg^?1 for ²³²Th and 513±10, 493±20 and 681±28 Bq kg^?1 for ⁴⁰K, respectively. The results of the study presented were compared with corresponding results obtained in other coastal and aquatic environments in the Red Sea.     

Accident at the Fukushima Dai-ichi Nuclear Power Stations of TEPCO —Outline & lessons learned—

The severe accident that broke out at Fukushima Dai-ichi nuclear power stations on March 11, 2011, caused seemingly infinite damage to the daily life of residents. Serious and wide-spread contamination of the environment occurred due to radioactive materials discharged from nuclear power stations (NPSs). At the same time, many issues were highlighted concerning countermeasures to severe nuclear accidents. The accident is outlined, and lessons learned are extracted with respect to the safety of NPSs, as well as radiation protection of residents under the emergency involving the accident. The materials of the current paper are those released by governmental agencies, academic societies, interim reports of committees under the government, and others.     

同位旋相关的Boltzmann-Langevin方程及新核素19Na产生截面的研究

介绍了一种同位旋相关的输运方程,研究了在入射能量为28.7和6 0. 0MeV/u时 12C+ 12C的反应,对模型进行检验,发现计算结果较好地符合实验结果,说明了方程的可靠性. 利用该模型研究了在入射能量为28.7MeV/u下反应系统 17 -20,22Ne+ 12C中核素 19Na的产生截面,发现缺中子核引起的反应,具有更大 19Na的产生截面,为新核素的探测找到了理论依据.