Nuclear Reactions and Radionuclides in the Study of Fullerenes

Radiochemical techniques have been applied in various ways to the study of fullerenes and metallofullerenes for the past several years, and they have provided invaluable information pertaining to the stability, structures, and formation of the novel carbon material. This paper reviews those experimental results that have fully shown the usefulness and uniqueness of radionuclides demonstrated in the field of fullerene science.     

Actinides and Long-Lived Radionuclides in Tissues of the Japanese Population: Summary of the Past 20-Year Studies

Radioactive fallout constitutes the major source of contamination of the environment with fission products. Our primary interest was in selected fission products, such as ¹³¹I, ⁸⁹Sr, ⁹⁰Sr, and ¹³⁷Cs, and neutron activation products, such as ³H and ¹⁴C. Plutonium-239,240, ²⁴¹Am and ⁹⁰Tc are generated from nuclear tests, and they are important by-products of nuclear industries. Polonium-210, ²¹⁰Pb and ²³²Th, ²³⁰Th and ²²⁸Th occur widely in nature. These radionuclides enter the human body through inhalation and the ingestion through food and water. These nuclides may cause radiation doses to certain organs of the body. Assessment of the resulting health hazards is an essential public health activity, which demands reliable techniques for the assay of the various radionuclides in man and his environment. In this paper, we present the accumulation of radionuclides from man-made sources and primordial radionuclides in various tissues of the Japanese population. The studies were performed at the Department of Public Health, Akita University School of Medicine, during the periods from 1973 to 1995.     

Assessment of Risk to Hong Kong due to Accidental Releases of Radionuclides from a Nearby Nuclear Power Plant

A dispersion model was used to estimate the deposition of radionuclides onto reservoirs in Hong Kong due to accidental releases from the Daya Bay nuclear power plant. If water rationing could be imposed, the radiological hazard due to ingestion of contaminated water was about 25.8 mSv/year/person. The distribution coefficients of typical reservoir soils had been measured and were found to be about an order of magnitude less than those in other countries. It was estimated that reservoir soils had the capability of reducing the effective dose equivalent to about 16.7 mSv/year/person.     

Assessment of Metal Contamination in Shallow Coastal Sediments Around Mytilene Greece

Abstract

Different normalisation procedures were applied on a data set of metal concentrations of sediments from 28 stations in the harbour and coastal area of Mytilene, Lesvos island, Greece. Due to the great granulometric variability of the sediments the normalisation for grain-size was not applicable. Also, the normalisation to a carbonate-free basis did not provide additional information. On the other hand the normalisation to Al and the calculation of enrichment factors of metals enabled to distinguish between contaminated and non-contaminated areas. The harbour sediments were highly enriched in Cd, Cu and Zn and also slightly enriched in Pb. No enrichment was found in the sediments of the coastal area outside the harbour, indicating that the metal rich deposits of that confined area are not affecting the quality of the neighbouring coastal environment.     

核电站周围环境放射性最佳监测点数的研究

本文研究的是广东大亚湾核电站周围区域环境放射性监测最佳监测点数问题,分别对正态分布、对数正态分布、t分布和对数t分布等模型求出了监测点数的最佳数量。用车贝雪夫不等式求出了任意分布下监测点数上限值。为了节省人力、物力和时间,对采用监测复合样品的办法进行了探讨。     

Separation of Zr in the rubble waste generated at the Fukushima Daiichi Nuclear Power Station

Separation method of Zr using trans uranium resin (TRU resin) and tetra valent actinide resin (TEVA resin) was developed for the analysis of ⁹³Zr contained in the rubble waste. Zr, Nb, and U were quantitatively extracted on the TRU resin from 3 M HNO₃ and striped with 0.01 M HF, in addition, some part of Mo, Hg, Bi, and Th were also included in the stripping solution. The stripping solution was evaporated to eliminate HNO₃ and the residue was dissolved in 0.1 M HF. Finally, Zr was separated from Nb and Mo with the TEVA resin.     

Determination of 129I in Conifer Samples Around Nuclear Facilities in Argentina

An improved method has been developed that allows the determination of ¹²⁹I in conifers around nuclear facilities using neutron activation analysis. Pine and cedar needle samples were collected from the surroundings of Atucha and Embalse Nuclear Power Plants, Centro Atómico Ezeiza, as well as from background areas in Argentina. ¹³¹I was used as tracer. A chemical recovery of 98–100% was obtained for pre-irradiation distillations and total recovery was 70–85%. The minimal detectable amount (MDA) was 0.01 mBq/g of sample, depending on the total recovery, natural iodine concentration, irradiation time and neutron flux. The results presented in this paper are the first published from Argentina.     

Plutonium Isotopes in Sediments from the Sudanese Coast of the Red Sea

This paper presents the activity concentrations of Pu isotopes in surface marine sediments collected from the Sudanese coast of the Red Sea. The following concentration ranges were determined: ²³⁸Pu, 4.7–28.6 mBq/kg; ^239+240Pu, 53–343 mBq/kg dry weight. The average activity ratios of ²³⁸Pu/^239+240Pu (0.075±0.045 mBqk/kg) and ^239+240Pu/¹³⁷Cs (0.026±0.025 mBq/kg) are appropriately comparable to the literature values that are characteristic of the global fallout from the atmospheric nuclear weapon tests. However, ^239+240Pu/¹³⁷Cs ratio in sediments collected from the biologically rich fringing reef is an order of magnitude higher compared to other sampling locations.     

Radionuclides in a sediment trap and bottom sediment samples from the eastern Turkish coast of the Black Sea

Summary Radionuclide (¹³⁷Cs, ²³⁸U, ²³²Th and ⁴⁰K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish coast of the Black Sea. The specific activity of the ¹³⁷Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq^. g^-1dry weight. The calculated flux rate of the ¹³⁷Cs was between 0.37 and 2.59 Bq^. m^-2. d^-1in the sampling periods of 2002 and 2003. The ¹³⁷Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq^. g^-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the 17 years after the Chernobyl accident.     

Quantitative Analysis of Planktonic Foraminifera in Surface Sediments From the South China Sea

Q-mode factor analysis was applied to 99 surface samples from the South China Sea to define four planktonic foraminiferal assemblages: tropical-subtropical assemblage, high-salinity assemblage, transitional assemblage and dissolution resistant assemblage. The tropical-subtropical assemblage is a dominant assemblage. The variation of the planktonic foraminifera of this assemblage reflects the changes of tropical surface water from the west Pacific to South China Sea. These four assemblages reveal that different planktonic foraminiferal assemblages are controlled by different factors in the South China Sea, such as tropical-subtropical assemblage controlled by sea surface temperature (SST), high-sallnity assemblage mainly by salinity besides SST, transitional assemblage by SST and dissolution resistant assemblage by water depth.     

北黄海中部晚第四纪沉积物来源的稀土元素示踪

对北黄海中部DLC70-2孔166个沉积物样品进行了稀土元素测定,结合粒度参数研究,以探讨北黄海中部DLC70-2孔稀土元素地球化学特征和物质来源。结果表明:DLC70-2孔岩心稀土元素分布特征分别反映了末次间冰期(暖期)晚期以来北黄海海面波动以及沉积物物源的变化。判别函数和稀土元素配分模式表明北黄海DLC70-2孔沉积物物源主要为黄河源和鸭绿江源。La/Yb判别图解揭示DLC70-2孔上部0~32.10 m和下部37.60~60.72 m沉积物以黄河源为主,中部32.10~37.60 m和底部60.72~70.45 m沉积物以鸭绿江源为主。研究表明晚更新世以来黄河对北黄海中部沉积起着重要作用,而鸭绿江物质对北黄海中部沉积作用也有明显影响。     

Determination of Trace Metals in Antarctic Sediments from Terra Nova Bay - Ross Sea

Abstract

Trace metals (Cu, Pb, Zn, Cd, Cr, Ni, Co, Mn) and iron concentration were determined in several sediments collected in the Antarctica (Terra Nova Bay—Ross Sea). Samples were analyzed by inductively coupled plasma (ICP-AES) after selective and total extraction. The results are in good agreement with the data previously collected in the same area.     

Plutonium Activity Ratios in Plankton: New Evidence of Hold-Up Time in Irish Sea Sediments

The determination of activity ratios for radioisotopes of different half-lives can be used to estimate transit times from a point source to locations further away. For conservative elements, this time is approximately equivalent to the net hydrological transport. However, for non-conservative elements such as plutonium, the additional influence of biogeochemical processes decreases the net transport time. In this study, ²⁴¹Pu and ^239,240Pu concentrations in Irish Sea plankton samples, collected in May 1994, were determined and the ²⁴¹Pu/^239,240Pu ratios calculated. Plutonium-239,240 was measured using a standard method by ion exchange chromatography and alpha counting, and ²⁴¹Pu was determined by liquid scintillation counting using the disk-supported technique. The latter showed some methodological problems, which are briefly discussed. The ²⁴¹Pu/^239,240Pu ratios gave an estimate of the "transit time" from Sellafield to the different sampling points. In fact, this time represents the age of plutonium in plankton, i.e., the time lag between release from Sellafield and detection at the different sampling stations. The mean plutonium age was 17±2 years (n = 10) and 18.6±0.8 years (n = 13) in phytoplankton and zooplankton, respectively. The spatial distribution was reasonably homogeneous over the Irish Sea. The assimilation-elimination processes of plutonium in plankton are rather rapid. Therefore, it may be assumed that, in this time scale, the plutonium concentrations were in equilibrium with surrounding waters. Thus, it is concluded that plutonium was rather old because resuspension-sedimentation processes had occurred that delayed its transport within the Irish Sea. Therefore, the age of plutonium in plankton represented the hold-up time of plutonium in the sediments from the Irish Sea.     

高效液相色谱法测定海洋水体与沉积物中光合色素

建立了海洋水体与沉积物中30种光合色素的反相高效液相色谱检测方法。海水滤膜和沉积物分别采用95%甲醇和95%丙酮超声萃取。萃取液混合一定比例的超纯水后,采用Eclipse XDB C8反相柱进行分离,以乙腈(A)、甲醇(B)和四丁基羟胺-甲醇(C)混合液为流动相进行洗脱,检测波长为430,440和450nm,柱温为50℃。色谱分离梯度为:0min,100%C;22min,25%A,45%B和30%C;28～38min,70%A,20%B和10%C;38.1～40min,100%C。对23种已知浓度色素的线性关系、检出限和加标回收率进行分析。结果表明,相关系数范围为0.9972～0.9998,检出限范围为0.0305～0.7740ng,加标回收率范围为88.6%～103.3%。     

Ageing Monitoring of Plastics Used in Nuclear Power Plants by DSC

Degradation of polymeric materials used in nuclear power plants (NPP), especially polymeric cable insulation materials, in the course of their service can be monitored by measuring their properties by DSC, mainly oxidative induction time — OIT. The studied materials were in-laboratory aged by applying main stressors that act in NPP — ionising radiation and temperature. The dependence of OIT on radiation and thermal degradation of polymeric material was determined. The OIT values have been compared to elongation at break as a property that directly reflects the functionality of the studied material. The comparison of monitored OIT of real cable samples taken from NPP with dependencies on how the OIT values change with the elongation at break, makes possible to establish the extent of cable degradation. This method can be considered as a suitable and effective technique for lifetime assessment not only of cable insulations but also of many other plastics. This revised version was published online in July 2006 with corrections to the Cover Date.     

氢化物发生-原子荧光光谱法测定核电用钢中痕量锡

提出了氢化物发生-原子荧光光谱法测定核电用钢中痕量锡的方法。样品在酒石酸溶液存在下,用盐酸-硝酸(3+1)混合酸溶解,用50 g·L-1硫脲-抗坏血酸混合溶液作掩蔽剂,20 g·L-1硼氢化钾溶液作为锡(Ⅳ)的还原剂,氢化反应在pH 5.0~5.5介质中进行,锡的质量浓度在50μg·L-1范围以内与相应的荧光强度呈线性关系,方法的检出限(3s/k)为0.4μg·L-1。应用此方法分析了核电用钢及不锈钢标准样品中锡的含量,并与电感耦合等离子体原子发射光谱法作了比较,测定值与标准值相符,结果的相对标准偏差(n=8)均小于4.5%。     

Geochemical Characteristics and Significance of Organic Matter in Hydrate-Bearing Sediments from Shenhu Area,South China Sea

Rock-Eval pyrolysis and the biomarker composition of organic matter were systematically studied in hydrate-bearing sediments from the Shenhu area, South China Sea. The n-alkane distribution patterns revealed that the organic matter in the sediments appeared to originate from mixed sources of marine autochthonous input, terrestrial higher plants, and ancient reworked organic matter. The low total organic carbon contents (average < 0.5%) and the low hydrogen index (HI, <80 mg HC/g TOC) suggested the poor hydrocarbon-generation potential of the deposited organic matter at a surrounding temperature of <20 °C in unconsolidated sediments. The abnormally high production index and the fossil-originated unresolved complex mixture (UCM) accompanied by sterane and hopane of high maturity indicated the contribution of deep hydrocarbon reservoirs. Preliminary oil-to-source correlation for the extracts implied that the allochthonous hydrocarbons in the W01B and W02B sediments might have originated from the terrestrial source rocks of mature Enping and Wenchang formations, while those of W03B seem to be derived from more reduced and immature marine source rocks such as the Zhuhai formation. The results of the organic extracts supported the previous identification of source rocks based on the isotopic composition of C₂₊ hydrate-bound gases. The biomarker of methanogens, squalane, was recognized in the sediments of this study, possibly suggesting the generation of secondary microbial gases which are coupled with the biodegradation of the deep allochthonous hydrocarbons.     

南黄海表层沉积物稀土元素分布与物源关系

对南黄海295个表层沉积物样品稀土元素的电感耦合等离子体质谱法分析,结果表明,南黄海表层沉积物稀土元素平均含量为188.39μg.g-1,稀土富集与重矿物有密切关系;稀土元素的球粒陨石配分模式均呈现Eu负异常,模式具负斜率,表明表层沉积物物质主要来源于大陆地壳。从稀土元素地球化学特征的区域变化来看,南黄海东部沉积物来源于朝鲜半岛,西部沉积物来源于黄河和长江物质输入,中部细粒沉积物主要与黄河及长江物质东南、东北扩散有关,东南部为朝鲜半岛及黄河、长江物质共同作用的结果。