60Co、85Sr 和137Cs 在黄土包气带中迁移的模拟实验

从野外试验场用专门研制的原状土柱采样装置采用得未扰动土柱，以＾６０Ｃｏ、＾８５Ｓｒ和＾１３７Ｃｓ三种核素为示踪剂，在人工喷淋条件下研究核素在土柱中的迁移行为。采用直接测量和解体测量两种方法测定了核素在土柱中的垂向浓度分布。     

大亚湾核电站处置场近场介质对核素的吸附性研究

本工作所进行的核素迁移研究是为大亚湾核电站中低放废物处置可行性研究和环境安全评价提供８５Ｓｒ、１３４Ｃｓ、６０Ｃｏ的迁移参数。试验方案为静态试验测定分配系数，动态试验观察核素在介质中的迁移分布状况。试验样品取自大亚湾处置场钻井岩芯和探槽。有五个取样点，取样深度分别为１５ｍ、５－１５ｍ、１－２７ｍ、３－３８ｍ和１０－５０ｍ，共计２８个样品。静态试验表明，同一种土样对三种核素的吸附比差异很大，说明地质介质对核素的吸附具有选择性。三种核素的吸附平衡时间为１２０ｈ。２８个样品的８５Ｓｒ、１３４Ｃｓ和６０Ｃｏ的平均Ｋｄ值分别为９．４×１０ｍｌ／ｇ、２．３×１０３ｍｌ／ｇ和１．３×１０２ｍｌ／ｇ。动态试验运行１００天，流出液中未测出放射性，岩芯柱解体后测量放射性，结果表明８５Ｓｒ比１３４Ｃｓ和６０Ｃｏ迁移的远。试验运行１００天之后，８５Ｓｒ迁移５．５ｃｍ，而１３４Ｃｓ和６０Ｃｏ只迁移２．５ｃｍ。三种核素的滞留因子分别为Ｒｄ（８５Ｓｒ）７．４×１０２，Ｒｄ（１３４Ｃｓ）１．８×１０４和Ｒｄ（６０Ｃｏ）１．０×１０３。试验结果表明：大亚湾处置场近场钻井岩芯和探槽取样对８５Ｓｒ、１３４Ｃｓ和６０Ｃｏ核素具有很强的吸附性。因此     

黄土包气带中放射核素迁移的现场试验

在中国辐射防护研究院野外试验场琥展了为期二年的包气带中＾３Ｈ、＾６０Ｃｏ、＾８５Ｓｒ和＾１３４Ｃｓ的迁移试验，在天然条件和人工喷啉条件下共进行了六组试验。通过期取样和直接测量两种方法测量了示踪核素的浓度分布；同时为配合迁移试验，同步开展了包气带中水分运行观测。     

85Sr、134Cs和60Co 在黄土中吸附和迁移的研究

本文通过静态实验和动态实验，了＾８５Ｓｒ、＾１３４Ｃｓ和＾６０Ｃｏ在黄土中的吸附和迁移行为以及核素浓度、ＰＨ和温度对分配系数的影响。     

黄土包气带中核素二维迁移的试验研究

为了研究黄土包气带中放射性核素在垂直和水平方向上的二维迁移,在野外试验场的Ｃ坑和Ｆ坑进行了取样测量。将＾８５Ｓｒ、＾１３４Ｃｓ和＾６０Ｃｏ三种核素与黄土均匀混合,制成示踪源,埋置于坑底中心位置,距地表１ｍ,两坑示踪源匀为φ５．５ｃｍ＊０．６ｃｍ。     

我国市售茶叶中^90Sr,^137Cs和^144Ce的含量

本文报道了１８种国产茶叶中＾９０Ｓｒ、＾１３７Ｃｓ和＾１４４Ｃｅ含量的测定结果，样品灰化用后放射化学联合分析方法测定。结果表明，１９８５年市售茶叶中＾９０Ｓｒ、＾１３７Ｃｓ和＾１４４Ｃｅ的平均含理分别为１７、２．２和０．８Ｂｑ／ｋｇ。     

~（85）Sr、~（134）Cs和~（60）Co在浅地层黄土与地下水间的分配系

本文报道了￣（８５）Ｓｒ、￣（１３４）Ｃｓ和￣（６０）Ｃｏ在采自本院野外试验场，从地表到地下２ｍ深黄土与地下水间分配系数的测定结果，以及核素浓度、ｐＨ和温度对分配系数的影响。黄土采集的深度范围分别为：地表－０．５ｍ，０．５－１ｍ，１－１．５ｍ，１．５－２ｍ，共采集１６个样品；地下水取自试验场的井水。实验采用静态法。实验结果表明，１６个样品测定的￣（８５）Ｓｒ、￣（１３４）Ｃｓ和￣（６０）Ｃｏ的分配系数的均值分别为８２、７．４×１０￣３和５．４×１０￣３ｍＬ／ｇ；在不同深度的黄土中测得的分配系数基本一致。ｐＨ值的变化对￣（１３４）Ｃｓ和￣（８５）Ｓｒ的分配系数有较大影响，对￣（６０）Ｃｏ则影响不大。     

土壤中核素迁移实验示踪核素活度分布的直接测定

本文介绍了在中国辐射防护研究院野外试验场进行的包气层土壤核素迁移实验研究中放射性示踪核素活度分布的直接测定方法及部分实验结果。图１为直接测定实验示意图。图中Ｓ为含有８５Ｓｒ、１３４Ｃｓ和６０Ｃｏ核素的混合土样。带有准直窗的ＮａＩ探测器在测量井中扫描，...     

大亚湾海底泥中γ放射性核素比活度随深度的变化及底泥沉积速率？…

通过对广东大亚湾核电站附近海域采集的４个海底泥样品的测量分析，得到了底泥中放射性核素＾２３８Ｕ，＾２２６Ｔｈ，＾４０Ｋ，＾２１０Ｐｂ，＾１３７Ｃｓ的比活度随深度变化的数据，利用＾２１０Ｐｂ的沉积规律和１３７Ｃｓ的沉积峰值与全球大气核试验高峰斯的对应关系，估算出湾内底泥的沉积速率在０．９４～１．４２ｃｍ／ａ之间，两种方法估算的结果基本一致。     

^75Se和^113Sn的KX射线发射几率测量

用＾５４Ｍｎ、＾５７Ｃｏ、＾６５Ｚｎ、＾８５Ｓｒ、＾１０９Ｃｄ、＾１３７Ｃｓ等核素发射的ＫＸ射线和Ｉ（ＫＸ）／Ｉ（γ）比值法在５￣４０ｋｅＶ范围内对Ｓｉ（Ｌｉ）探测器的效率进行了刻度（不确定度小于２％）。在此基础上,用Ｓｉ（Ｌｉ）Ｘ射线谱仪系统和ＨＰＧｅγ射线谱仪系统对核素＾７５Ｓｅ和＾１１３Ｓｎ的主γ射线和ＫＸ射线进行了测量,获得了＾７５Ｓｅ和＾１１３Ｓｎ的ＫＸ射线发射几率,并与文献报道值进行了     

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。     

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.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.