在Purex流程中RuNO络合物的某些化学行为

HNO_3预平衡的30％TBP-煤油经γ辐照后对RuNO络合物有严重的保留作用,即不易用酸碱洗涤去除。将辐照溶剂分为碱萃相、水萃相和中性相,实验证明对Ru有保留作用的是中性相,而不是水萃相。进一步实验表明,造成辐照溶剂中Ru保留的主要是稀释剂的辐解产物。30％TBP-十二碳异羟肟酸-煤油对Ru有明显的保留作用。     

强辐照场下Purex过程溶剂的辐解研究——Ⅰ.30%TBP-煤油-1mol/L HNO_3两相混合状态下TBP辐解生成DBP和MBP规律的研究

本文研究了30％TBP-煤油-1mol/L HNO_3两相混合及1mol/L HNO_3平衡过的30％TBP-煤油单有机相两种条件下TBP辐解生成DBP和MBP的规律。混合相辐照TBP降解成DBP的主要过程发生在有机相中;在剂量小于2×10~5Gy,混合相辐照有较高的DBP生成G值,而当剂量大于2×10~5Gy时,混合相与单相辐照生成DBP的G值则趋于一致;混合相辐照MBP生成浓度比单相辐照高30％-40％。混合相辐照有较高的MBP生成浓度及低剂量下有较高的DBP生成G值,很可能与混合相中含有大量水及辐照时接触到较多的氧气有关。     

辐照TBP-正十二烷萃取体系对钌的保留行为

采用系列相比法研究了吸收剂量、辐照前预平衡硝酸浓度、辐照前体系中含钌、萃取水相的硝酸浓度等对钌保留的影响,并测定了几种模拟辐解产物对钌的萃取.结果表明,γ辐照后的TBP-正十二烷萃取钌达平衡很慢,碱洗涤平衡较快;随着吸收剂量、辐照前预平衡硝酸浓度、循环使用次数的增加,钌保留增加;辐照前体系中含钌时,则钌保留较大;含钌的...     

锆在HNO_3-HDBP-煤油体系中的萃取行为

一、前言为了了解锆在Purex流程中的行为,进行了HDBP萃取~(95)Zr的初步研究。在Purex流程中,所采用的萃取剂是30%TBP-煤油。由于放射性辐照及酸等因素的影响,导致了TBP-煤油的降解。其降解产物有HDBP、H_2MBP、气体产物以及高分子聚合物。此外辐照剂量大时也可产生H_3PO_4、少量丁醇乙醚等异羟肟酸、各种醛、肟羧酸、羟胺、有机硝酸酯、有机硝基化合物、有机亚硝基化合物等。HDBP在工艺流程中与金属     

单长链烷基酸性磷酸酯对锆的萃取和保留

本文研究了在30％TBP-单长链烷基酸性磷酸酯(MLCAP)-煤油-HNO_3和MLCAP-煤油-HNO_3两个体系中,萃取剂浓度、水相中H~+、总NO_3~-、稳定锆和铀的浓度及温度等因素对Zr的萃取行为和酸、碱洗涤后Zr的保留行为的影响。还对萃取反应机制进行了初步探讨。结果表明,在实验条件下,MLCAP与Zr生成组成为2:1的萃合物;当MLCAP存在于30％TBP-煤油中时,会使Zr的萃取明显增加并易产生界面物;在用Na_2CO_3洗涤有机相时,不能将Zr有效洗脱并易产生乳化现象,使溶剂质量变坏和造成分相困难。乳化生成的程度与体系中稳定锆的浓度和MLCAP的存在量有关。     

高加浓铀燃料后处理辐照溶剂串级萃取研究

本文是一篇有机萃取溶剂经模拟辐照后进行萃取工艺研究的报告。以~(60)Co为辐照源,5%TBP-煤油为模拟辐照溶剂,在1×10~5～1×10~6拉德剂量范围内进行辐照,按给定的工艺条件,用试管进行串级研究。实验说明,有机溶剂TBP的降解产物DBP是导致有机溶剂中~(95)Zr—~(95)Nb和铀保留的主要因素。随着剂量的增大,1A槽中~(95)Zr-~(95)Nb的分配系数明显上升,即对~(95)Zr-~(95)Nb的净化急剧降低;1B和1C槽净化无明显变化;1C槽铀回收率有显著下降。     

在TBP-煤油有机相中光化还原制取U(Ⅳ)的研究——Ⅱ.降解产物的产生和它们对萃取的影响

本文研究了在TBP-煤油体系中光化还原制取U(Ⅳ)时,降解产物的产生和它们对萃取性能的影响。结果表明,TBP-煤油的主要降解产物有DBP和MBP、羰基化合物和硝基烷。光照后的有机相经稀酸反萃和碱洗所得回收萃取剂的萃铀分配比、铀保留值和分相时间与新鲜萃取剂无明显差别)。     

TBP-煤油-HNO_3体系的辐解与水解

本文应用气相色谱法测定了TBP-煤油-HNO_3萃取体系中 TBP辐解产物DBP和MBP的生成G值。G_(DBP)值与文献值一致:G_(MBP)值为文献值的～1/3。测定了TBP在 27℃下水解生成DBP的速度常k值。通过表观动力学计算指出,TBP辐解生成 MBP有两个途径。给出了一个TBP 辐解生成DBP和MBP与辐照剂量之间的关系式。     

TBP—煤油体系中U（Ⅵ）的光化学还原以及在铀,钚分离上的应用

文章研究了30%TBP-煤油体系中U(VI)的光化学还原以及有机相中HNO_2含量、温度对光化学过程的影响,并测定了光化学反应后有机相对铀的保留量以及对裂片元素~(95)Zr-~(95)Nb,~(103)Ru和~(153)Gd的萃取性能的影响。按照Purex过程1 B柱工艺进行了光化学还原反萃分离钚的单级试验。结果表明,铀、钚分离效果是满意的,光化学反应对铀在有机相中的保留和对裂片元素的净化没有明显影响。     

30%TBP-煤油-HNO_3体系辐解产物长链酸性磷酸酯产额的计算

本文利用文献数据计算了TBP一煤油一HNO_3体系辐解产物长链酸性磷酸酯的辐解产额。长链酸性磷酸酯的生成G值随着剂量的增加而呈线性增加。辐照剂量在1×10~7拉德到1×10~8拉德范围内G=0.0096—0.143。     

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.     

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。     

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.     

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.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.