稀TBP萃取工艺1B槽铀镎分离串级实验

镎的主要价态为四、五、六价,三种价态的镎可共存,且可在一定条件下互相转化。不同价态镎的萃取行为不尽相同。随铀钚一同进入1B槽中的镎主要为具有一定萃取能力的Np(Ⅳ)和萃取能力较高的Np(Ⅵ)。在1B槽还原性气氛下,Np(Ⅵ)将被反萃液中的还原剂还原为Np(Ⅴ)甚至Np(Ⅳ),而Np(Ⅴ     

Study on Leaching Behaviors of Pyrochlore-rich Synroc Under Simulated Disposal Conditions

镎的主要价态为四、五、六价，三种价态的镎可共存，且可在一定条件下互相转化。不同价态镎的萃取行为不尽相同。随铀钚一同进入1B槽中的镎主要为具有一定萃取能力的Np（Ⅳ）和萃取能力较高的Np（Ⅵ）。在1B槽还原性气氛下，Np（Ⅵ）将被反萃液中的还原剂还原为Np（Ⅴ）甚至Np（Ⅳ），而Np（Ⅴ）的萃取能力很弱，基本上不被萃取，所以，Np（Ⅳ）的萃取行为便成了1B槽铀镎分离的关键。基于以上分析，在1B槽铀镎分离串级实验中，初始镎以Np（Ⅳ）形式加入。     

硝酸溶液中NpO2^2＋／NpO2^＋在铂电极上的电极过程动力学

在Purex流程中，镎可以Np^4＋、NpO2^＋、NpO2^2＋价态同时存在，但Np（Ⅳ）和Np（Ⅵ）能被TBP萃取，而Np（Ⅴ）则在TBP中的分配比很低。不能被TBP萃取，因此，控制镎的价态是分离提取镎的重要环节。可利用镎不同价态之间电位的差异，采用电化学方法控制镎的价态。     

控制电位库仑法测定镎的浓度和价态

使用现有的恒电位仪、数字积分仪和数字电压表进行了镎浓度和价态的控制电位库仑滴定。利用部分电解氧化还原法测定了Ce(Ⅳ)/Ce(Ⅲ)和Np(Ⅵ)/Np(Ⅴ)电对的克式量电位,在1.00N H_2SO_4介质中,其数值分别为1.196和0.841伏。当镎的取样总量约为1.3毫克时,使用控制电位库仑法测定镎浓度得到了0.6%的精密度和较高的准确度(相对作为基准方法的恒电流库仑法有0.9%的偏差)。本方法测定镎的价态与反相分配色层法符合得很好。实验结果表明,大量铀存在时(铀:镎约为75)对镎的电解速度和镎价态测定没有显著影响。     

溶剂萃取法从辐照镎靶溶解液中提取分离钚的萃取价态选择Ⅰ:Pu(Ⅳ)-Np(Ⅳ)北大核心CSCD

采用磷酸三丁酯(TBP)溶剂萃取法对从辐照镎靶溶解液中提取分离钚的可行性进行了研究。从料液制备、流程设计两个方面研究了Pu(Ⅳ)-Np(Ⅳ)组合作为萃取价态组合的可能性。研究了1,1-二甲基肼(UDMH)还原-亚硝酸钠氧化两步法将镎、钚控制在Pu(Ⅳ)-Np(Ⅳ)的方法。结果表明,99.9%以上Pu(Ⅳ)-99.5%以上Np(Ⅳ)在4 h内能够保持稳定。基于此,设计了从辐照镎靶溶解液中提取分离钚的萃取流程,并用串级实验进行了验证:1A中镎的回收率为99.5%;1B中镎的反萃率为0.8%,钚的反萃率为99.9%;1C中镎的反萃率为99.5%。结果表明,采用Np(Ⅳ)-Pu(Ⅳ)的价态组合进料,基本可实现镎钚的分离,但料液中Np(Ⅳ)-Pu(Ⅳ)价态的长时间稳定性及TBP对Np(Ⅳ)萃取能力弱等问题将影响该工艺的实际应用。     

用萃取色层法分离Np(Ⅳ),NP(Ⅴ)和Np(Ⅵ)

本文研究了用磷酸三(2—乙基己基)酯(以下简称为TIOP)作固定相、硝酸等为流动相的萃取色层法在分离Np(Ⅳ)、Np(Ⅴ)和Np(Ⅵ)中的应用。利用Np(Ⅳ)、Np(Ⅴ)和Np(Ⅵ)在TIOP—硅胶柱上分配系数的差异使不同价态的镎得到分离。Np(Ⅴ)不被TIOP吸附,Np(Ⅳ)、Np(Ⅵ)分别用HNO_3+HF、HNO_3+HF+Fe(NH_2SO_3)_2洗脱,从而达到定量分离。文中并对光的影响进行了讨论。最后简单叙述了用TIOP—萃淋树脂来分离Np(Ⅳ)、Np(Ⅴ)和Np(Ⅵ)的实验。     

1AW溶液中U、Np和Pu的分析

研究了H2O2同时调节镎、钚、铀价态至Np(Ⅳ)、Pu(Ⅳ)以及U(Ⅵ)的条件,在6mol/L HNO3浓度下,使用1.5%H2O2作为氧化还原剂对1AW进行调价,吸附上UTEVA柱并淋洗后,对钚、镎和铀进行洗脱。对模拟放射性样品进行预处理后,其中铀、镎、钚单独顺序洗脱的回收率分别为91.5%、119%、99.8%,137 Cs的去污因子高达7.4×104,单个样品操作时间约为1~1.5h;若钚洗脱后铀、镎同时洗脱并使用ED-XRF测量可以减少操作时间,铀、镎的回收率分别为102.4%、93.9%。均满足样品分析及辐射防护要求。     

Np(Ⅴ)吸附于纤铁矿/水界面的扩展X射线吸收精细结构(EXAFS)分析

本工作采用原位扩展X射线吸收精细结构(EXAFS)能谱首次揭示了Np(Ⅴ)吸附于合成纤铁矿(γ-FeOOH)表面的化学形态。Np LⅢ边EXAFS分析结果显示Np(Ⅴ)以五价镎酰离子吸附于γ-FeOOH,未发现多核络合物与表面沉淀。傅里叶转化结果在约3(1=0.1nm)附近的能峰可归于Np-Fe配位层,证明了Np(Ⅴ)-γ-FeOOH形成了内层吸附的单一形态表面络合物。所得分析结果与Np(Ⅴ)在相似构成的含铁矿物上的吸附形态结果进行了比较,进一步确认了Np-Fe、Np-O等关键配位层的存在。然而,还需要更多设计良好的EXAFS实验来确认是否存在Np-C配位层,以确认纤铁矿界面是否存在Np碳酸根表面络合物。     

~(60)Co γ辐照场中镎价态变化的研究

本文研究了含镎的硝酸-硝酸铀酰溶液在~(60)Coγ辐照场中镎价态变化的规律。观察了硝酸浓度、硝酸铀酰浓度及辐照剂量对镎价态变化的影响。结果表明:起始价态以镎(Ⅴ)为主的溶液经辐照后发生了辐射氧化-还原反应而生成镎(Ⅳ)和镎(Ⅵ),其生成量的多寡取决于溶液成份及辐照条件,起始价态以镎(Ⅵ)为主的溶液在辐照场中镎被还原;起始价态以镎(Ⅳ)为主的溶液在辐照场中镎被氧化。本文也对~(60)Coγ辐照场中镎价态变化的反应机理进行了一些讨论。     

Np(V)在黄土及其固相组分上的吸附与解吸--相对贡献、滞后系数、溶液中腐殖酸和碳酸盐的影响

本文用批实验法和选择性提取法研究了有机质（OM）和CaCO3对Np(V）在黄土上的吸附影响，测定了在未处理黄土和去除CaCO3、去除OM、去除CaCO3和OM三种处理黄土上Np(V)的吸附和解吸等温线，并用Fre-undich方程进行了分析。结果表明，CaCO3对Np(V)在黄土上的吸附/解吸滞后有一定影响，对Np(V)的吸附有负贡献；OM对Np(V)在黄土上的吸附/解吸滞后没有影响，且对Np(V）的吸附影响很小；溶液中的腐殖酸FA或CO3^2-对Np(V)的吸附有明显的正作用；Np(V)在黄土上的吸附主要受粘土矿物成分的影响；Np(V)在黄土中的迁移滞后现象应予以考虑。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

正~~     

Radioactivity levels in soil of salt field area,Kelambakkam,Tamilnadu,India

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer.The activity concentration for ~(232)Th,~(238)U and ~(40)K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg,and from 135.54 to 381.28 Bq/kg,respectively.The measured activity concentrations for these radionuclides were compared with world average activity of soil.The average activity concentration of ~(232)Th in the present study is 1.19 times higher than world median value while the activity of ~(238)U and ~(40)K is found to be lower. The absorbed dose rates due to these radionuclides were calculated.The average absorbed gamma dose rate due to the presence of ~(232)Th,~(238)U and ~(40)K in soil samples is 36.99 nGy·h~(-1).These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.