200 MeV电子直线加速器隧道内灰尘的活化

高能电子直线加速器隧道内的灰尘会通过光核反应、中子核反应而被活化。灰尘活化产生的放射性核素可能引起检修工作人员的内照射。本文简要介绍中国科技大学国家同步辐射实验室200MeV电子直线加速器隧道内不同地点灰尘的活化现状,并提出相应的防护建议。     

Regeneration of Acid Orange 7 Exhausted Granular Activated Carbon Using Pulsed Discharge Plasmas

In this paper, a pulsed discharge plasma(PDP) system with a multi-needle-to-plate electrodes geometry was set up to investigate the regeneration of acid orange 7(AO7) exhausted granular activated carbon(GAC). Regeneration of GAC was studied under different conditions of peak pulse discharge voltage and water p H, as well as the modification effect of GAC by the pulse discharge process, to figure out the regeneration efficiency and the change of the GAC structure by the PDP treatment. The obtained results showed that there was an appropriate peak pulse voltage and an optimal initial p H value of the solution for GAC regeneration. Analyses of scanning electron microscope(SEM), Boehm titration, Brunauer-Emmett-Teller(BET), Horvath-Kawazoe(HK), and X-ray Diffraction(XRD) showed that there were more mesopore and macropore in the regenerated GAC and the structure turned smoother with the increase of discharge voltage;the amount of acidic functional groups on the GAC surface increased while the amount of basic functional groups decreased after the regeneration process. From the result of the XRD analysis,there were no new substances produced on the GAC after PDP treatment.     

硼饱和模拟废活性炭的桶外水泥固化

核电站在运行过程中会产生含硼废水浸泡且硼饱和的废活性炭,需要对其进行固化处理。采用2.5‰(质量分数)的硼酸溶液对活性炭进行浸泡直至含硼量达到稳定来模拟实际废物源项,然后脱去硼饱和后活性炭中的游离水,并采用桶外水泥固化工艺对其进行水泥固化。结果表明,试验过程稳定可靠。另外通过试验验证可知,华龙一号新增废物源项废活性炭能够利用现有桶外水泥固化技术进行废物的处理,对硼饱和模拟废活性炭采用桶外工艺固化后,养护形成的水泥固化体按照标准GB 14569.1-2011进行游离液体、机械性能、抗水性、抗冻融性以及耐γ辐照性试验测试,结果均满足要求,且活性炭颗粒在固化体中分布均匀,未出现上浮现象,其搅拌完成以及30min后自由流动度均大于200mm,完全满足桶外水泥固化工艺稳定可靠的运行要求。     

~(133)Xe示踪剂法研究活性碳纤维对大气本底水平氙的吸附性能

用133Xe作示踪剂研究了市售活性碳纤维对大气本底水平氙的吸附性能 ,并与粒状活性炭的吸附性能作了比较 ;测定了市售活性碳纤维的吸附效率。结果表明 ,市售的几种活性碳纤维在低温下对大气中氙的吸附性能均优于粒状椰壳活性炭     

用于储氢材料的碳/掺杂碳气凝胶研究

通过溶胶凝胶工艺,以间苯二酚和甲醛为原料,采用常压干燥法制备有机气凝胶和金属掺杂有机气凝胶;在氮气保护下,经1050℃高温碳化获得碳/掺杂碳气凝胶;通过CO₂活化工艺优化样品微结构、提高其比表面积,获得了比表面积达2582m²/g的碳气凝胶样品。使用比表面积与孔隙度分析仪、扫描电镜（SEM）、透射电镜（TEM）、X射线衍射仪（XRD）对样品微观结构和气体吸附性能进行表征。通过溶胶 凝胶工艺实现了过渡金属的均匀掺杂,并研究了金属掺杂对碳气凝胶微结构特性的影响。结果表明,适当的金属掺杂可提高样品的比表面积和微孔体积。     

电子辐照对硅双极晶体管参数的影响

报道了2MeV电子束辐照对硅双极晶体管参数h_(FE)、t_(off)和C_T的影响。这些参数的变化依赖于电子辐照在晶体管内部引人缺陷能级的性质。实测表明,这些缺陷能级引起的少数载流子寿命下降和多数载流子去除效应是h_(FE)、t_(off)和C_T变化的直接原因。     

Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

In this study, two regeneration methods （dielectric barrier discharge （DBD） plasma and ozone （03） regeneration） of saturated granular activated carbon （GAC） with pentachlorophe- nol （PCP） were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with 03 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after 03 regeneration. 03 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cy- cles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after 03 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that 03 regeneration has a lower weight loss than DBD plasma regeneration.     

ESR STUDY ON RADIATION GRAFTING REACTION OF INORGANIC OXIDES

In this paper Al2O3 and MgO were studied as targets for the radiation grafting of MAA by electron beams. The reaction conditions and materials were characterized by IR spectroscopy, Scanning electron microscopy, X-ray diffraction methods. It is concluded that grafting copolymerization of inorganic oxides and organic monomers has been confirmed. We focus our attention on using ESR spectrum to study the effects of ionizing radiation on inorganic oxides and the properties of initiating active centers. In addition, the radiation grafting mechanism of inorganic oxides and organic monomers has been primarily investigated.     

Improvement of carbon fiber surface properties using electron beam irradiation

Carbon fiber-reinforced advance composites have been used for structural applications,mainly on account of their mechanical properties.The main factor for a good mechanical performance of carbon fiber-reinforced com- posite is the interfacial interaction between its components,which are carbon fiber and polymeric matrix.The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite.EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests.Experimental results showed that EB irradiation improved the ten- sile strength of carbon fiber samples.The maximum value in tensile strength was reached using doses of about 250 kGy.After breakage,the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated.SEM micrographs showed modifications on the carbon fiber surface.     

Microstructural evolutions of three-dimensional carbon–carbon composite materials irradiated by carbon ions at elevated temperatures

Carbon–carbon composites are deemed as candidate materials for applications in very high temperature reactors (VHTRs). In a VHTR, carbon–carbon composite materials would experience severe environmental impacts of both a high radiation fluence (about 3 × 10¹⁶/cm² per year) and high temperatures (∼1200 °C), and radiation damage is accordingly expected. In this study, samples prepared from a three-dimensional pitch-based carbon–carbon composite material were irradiated with a 4 MeV C²⁺ ion beam emitted by an accelerator to deliberately induce various levels of radiation damage on the samples at 1000 °C. Transmission electron microscopy analyses were then conducted to examine the evolution of microstructures in the samples, and a scanning electron microscope was used to examine the changes in surface morphology. It was found that an accumulated fluence of 7.0 × 10²¹/m² at 1000 °C resulted in cracks between the matrix and the fiber in the sample. These interfacial cracks were all parallel to the fiber orientation. The fiber/matrix bonding strength might play an important role in the mechanical property of the carbon–carbon composite material. In the meantime, cracks were also found at the fiber side of the sample irradiated under the same condition.