节能型空气中14C取样装置的研制

研制了空气中^14C的取样装置,基本原理是：对取样气体催化氧化、碱溶液吸收制成凝胶样品、液闪测量。催化氧化床采用了新型材料,可使使用温度降到300℃。对样品的化学处理、取样效率、催化氧化效率等作了测量。该装置对CO2的捕集效率为95％。利用该装置对环境中的^14C进行取样测量,其结果在非核环境中MC的浓度为0．13Bq／m^3,在加速器环境中^14C的浓度为2—3Bq／m^3。     

1992～2005年秦山核电基地外围环境放射性监测

自1992年,浙江省辐射环境监测站对秦山核电基地外围环境辐射水平进行了连续的监督性监测。1992～2005年,秦山核电基地外围环境电离辐射水平和各种介质放射性水平的监测结果如下：在正常运行下,秦山核电基地外围环境7辐射剂量率平均为96nGy／h;大气气溶胶总α、总β比活度分别为0．11、0．45mBq/m^3;环境大气中^3H浓度为71．6mBq/m^3,^14CO2浓度为0．30Bq／g（碳）;沉降物总β比活度为0．81Bq／m^2d;陆地环境淡水（饮用水、湖塘水、井水）中总α、总β、^90Sr、^137Cs浓度分别为65、151、4．4、0．3mBq／L,^3H为1．0Bq／L,雨水^3H浓度为2．8Bq／L;正常排放下基地附近海域海水样品^90Sr、^137Cs平均浓度分别为5．4、0．7mBq／L,^3H为1．0Bq／L;土壤、湖塘泥、潮间带土、海底泥^137Cs平均比活度分别为3．3、1．9、2．4、1．1Bq/kg（干重）;食用植物样品中,大米^90Sr、^137Cs、^3H平均比活度分别为0．06、0．14、0．4Bq／kg,青菜为0．27、0．04、3．1Bq／kg（鲜重）,萝卜为0．10、0．03、2．5Bq／kg（鲜重）;指示植物样品中,茶叶^90Sr、^137Cs、^3H平均比活度分别为3．4、0．49Bq／kg（干重）和4．6Bq／kg（鲜重）,松针分别为9．8、0．10、7．7Bq／kg（鲜重）;肉类动物样品中,猪肉^90Sr、^137Cs平均比活度分别为0．06、0．08Bq／kg（鲜重）,羊肉为0．11、0．03Bq／kg（鲜重）,牛奶为0．03、0．02Bq／k（鲜重）,奶粉^137Cs平均比活度为0．18Bq／kg（干重）,鲻鱼^90Sr、^137Cs平均比活度分别为0．13、0．05Bq／kg（鲜重）。     

一台反康普顿HPGe γ谱仪的性能改造和应用

主要描述了一台反康普顿HPGeγ谱仪系统改造前后的结构和性能。由于原有系统的积分本底偏高．在对它进行性能测试、本底来源分析之后．采取了改造屏蔽室．更换低本底主探测器等措施。通过细致的调试．测试了主要性能指标。积分本底(能区50～2000keV)由原67min^-1(主探测器相对探测效率为40％)降至约20min^-1(主探测器相对探测效率为50%)。标定了滤材样品的探测效率曲线．计算了大气气溶胶取样样品中^140Ba核素的最低可探测浓度(MDC)。在大气中^212Pb浓度约0．3Bq／m^3时．^140Ba的MDC可达10．Bq／m^3。     

环境和生物样品中3H和14C的测量

研究了环境和生物样品中^3H和^14C的测量方法。^3H测量步骤包括：样品氧化燃烧,使有机结合氚(OBT)转化为氚化水,用液闪法测量^3H活度。该方法的探测下限为1．2Bq／L。^14C测量步骤包括：将8g左右的样品经过燃烧爆炸后转变为CO2,并最终合成苯,用液闪法测量^14C的活度。该方法的探测下限(以C质量计)为1．0Bq／kg。文章同时给出了树叶、牛奶、动物、土壤等多种生物样品中^3H和^14C的测量结果。     

大亚湾和岭澳核电站外围辐射环境监督性监测

本文系统地介绍了广东省环境辐射研究监测中心自1994年以来对广东大亚湾和岭澳核电站外围辐射环境的监督性监测,包括监测方案、方法、质量保证、主要结果和结论。监测结果表明：(1)核电站运行以来的气体排放未对厂区以外的大气和陆地环境产生可观测到的影响;(2)对于^110mAg,西大亚湾的海水中仅在1995年和1997年检测到高于探测限的样品,最大年平均浓度为3．1Bq／m^3;西大亚湾的海底泥中只在1997年能被检测到,年平均值为1．0Bq／kg(干);西大亚湾的海洋生物中在：1994、1996和1997年检测到的活度浓度较高,珍珠贝、马尾藻和墨鱼中的最高年平均活度浓度分别为2．2、1．7和5．8Bq／kg(鲜),1997年以后随着排放量的下降而显著下降;(3)对于^137Cs,1994～1998年西大亚湾海水样品中的活度浓度相对较高,年平均值最高的1995年为4．6Bq／m^3,1999年以后与本底相当;^137Cs在其他海洋介质中的活度浓度很低,且在本底涨落范围内变化;(4)对于西大亚湾海水中的^3H,只在核电站排放期间短时升高,3～5天后基本恢复到本底水平,实测年平均活度浓度在0．8～3．4Bq/L之间。     

兰州市农畜产品天然放射性核素含量水平与公众年摄入量

报道了兰州市主要农畜产品中天然放射性核素^238U、^226Ra和^232Th的含量水平,粮食中的平均值分别为0．14、0．16和0．18Bq／kg,蔬菜为0．14、0．09和0．05Bq／kg,水果为0．04、0．05和0．03Bq／kg,肉类为0．23、0．21和0．17Bq／kg,蛋、奶为0．14、0．03和0．06Bq／kg;估算了由食入农畜产品致公众放射性核素年摄入量为125．8Bq。结果表明,兰州市农畜产品天然放射性核素含量水平与公众年摄入量属正常水平。     

用PIPS探测器连续测量气溶胶的研究

采用PIPS(Planar Implanted Passivated Silicon)探测器测量α气溶胶浓度,使用能量甄别的方法可以将人工α放射性和天然放射性区别开来,通过校正因子修正天然放射性对人工放射性的影响。由真空泵取样,连续测量空气中的气溶胶浓度。PIPS探测器能量分辨率好,在50Bq／m^3的环境中,对^239Pu(95％置信度)可达0．1Bq／m^3。     

^35S-KSCN示踪剂的油田井间监测方法

研究了同位素示踪剂^35S-KSCN在油田井间示踪测试中的分析方法并将其应用于矿场进行示范试验。条件实验结果显示,油田水溶液中的微量^35S-KSCN在0．5～2．0mol／L的HCl体系中与Zn^2＋配合可被磷酸三丁酯（TBP）定量萃取。用液体闪烁计数器测量^35S产生的β射线,最小探测下限为0．02Bq／L,该法回收率〉90％,0．02～5Bq／L线性良好,R^2=0．9995。通过矿场示范试验得到完整数据,验证了^35S-KSCN示踪剂是一种稳定的水驱示踪剂;同时也表明了该法简便、快速,适用于油田井间示踪测试。     

乌鲁木齐市沉降物中^(7)Be、^(40)K放射性水平

为了解乌鲁木齐市辐射环境水平,监测了乌鲁木齐市周围环境空气中沉降物2017—2021年^(7)Be、^(40)K放射性水平。结果表明:乌鲁木齐市沉降物中^(7)Be的最大值为2.8 Bq/(m^(2)·d),最小值为1.1 Bq/(m^(2)·d),5年均值为1.94 Bq/(m^(2)·d);^(40)K的最大值为1050 mBq/(m^(2)·d),最小值为104 mBq/(m^(2)·d),5年均值为354.3 mBq/(m^(2)·d);乌鲁木齐市沉降物中的^(7)Be、^(40)K放射性水平处于正常天然放射性水平,且5年测值基本处于稳定状态。     

秦山核电基地外围环境水体放射性水平监测

自1992年，浙江省辐射环境监测站对秦山核电基地外围环境放射性水平进行了连续的监督性监测。1992～2004年，基地外围环境水体放射性水平的监测结果表明：秦山核电基地外围地区陆地环境淡水（饮用水、湖塘水、井水）中总α、总β、^90Sr、^137Cs平均浓度分别为67、157、4．4、0．3mBq／L，^3H为1．4Bq／L，雨水中^3H为2．0Bq／L；正常排放下，基地附近海域水样中^90Sr、^137Cs平均浓度分别为1．4、0．7mBq／L，^3H为I．0Bq／L；第一期核电厂三回路冷却水总β、^90Sr、^137Cs平均浓度分别为2．6、4．1、1．0mBq／L，^3H为2．IBq／L，排放口海水^3H平均浓度为1．4Bq／Lo与运行前本底值和对照点监测值相比，秦山核电基地外围环境水体放射性水平在正常波动范围内，基地外围环境陆地淡水和附近海域海水没有受到放射性污染。     

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.