秦山核电基地环境生物样品中14C监测方法探讨

介绍了氧弹法在秦山地区环境生物样品中¹⁴C监测中的应用情况,对氧弹法的特点进行了分析,并对秦山核电基地历年来环境生物样品中¹⁴C监测的结果进行了分析。希望本方法能对生物样品中¹⁴C监测方法的新国标的制定提供参考。     

某些铀矿化的有机质的化学研究和显微镜观察

铀矿化经常与有机质的大量富集相伴生。本文研究了奥克洛(加蓬)弗朗斯维尔组的一些样品和洛代夫(法国)二叠系的一些样品中的有机质。所利用的方法是有机地球化学法和光学显微镜法。镜下观察是在透射光和反射光(自然光和荧光)下进行的。在洛代夫盆地对含铀样品和贫铀样品作了对比。含铀样品的干酪根演化程度明显地较深、无氯仿抽提物。气烃(C_1—C_6)为干气成分,汽油组分(c_6—c_(15)只含轻组分(C_1—c_8)。总之,若贫铀样品含质量好的有机质并处在生油阶段,那么含铀样品的有机质就更加成熟,就是说处在产气阶段。奥克洛的样品与洛代夫的含铀样品相似(氯仿抽提物含量低、气烃成分为干气、汽油以轻组分为主),可是样品中有机质的演化程度好象更高(镜质体和壳质体反射率、“定碳比”),而且越接近铀矿体有机质演化程度越来越高。这个初步研究的结论是:辐射引起的有机质的变化本身就反映出演化程度明显地增高。     

国际原子能机构γ能谱测量比对

介绍了参加国际原子能机构(IAEA)组织的全球实验室间样品能力验证概况。分析连云港辐射环境监测管理站近3年(2020～2022年)运用无源效率刻度方法分析IAEA样品,模拟出水样、生物、滤膜不同介质的效率曲线,分析样品中⁴⁰K、⁶⁰Co、⁷⁵Se、^110mAg、¹³⁴Cs、¹³⁷Cs、²⁴¹Am等核素的浓度,报送34个数据的准确度和精密度均满足IAEA评估要求。验证无源效率刻度方法分析IAEA样品的实用性和可靠性,为该方法在环境辐射监测中的推广应用提供依据。     

过氯乙烯滤膜采样测定空气和废气中铀的分析方法研究

利用微波消解-ICP-MS法,针对过氯乙烯滤膜采集空气和废气中铀含量的分析,建立了过氯乙烯滤膜微波消解体系。结果表明,优选硝酸作为消解酸溶液,消解程序优化后,本方法铀加标回收率在98.4%～102.0%之间,检出限为2×10^-3 ng/m³(按采样体积10 m³、定容体积50 mL计),检出限的放射性活度浓度为6×10^-8 Bq/m³(以天然铀计)。应用该方法分析实际空气样品中铀含量,相对标准偏差为3.18%。该方法前处理时间短,结果可靠,能够实现空气和废气样品中铀含量的快速、稳定、高效、准确的分析测试。     

铀表面磁控溅射镍镀层的电化学腐蚀行为研究

采用磁控溅射离子镀膜技术在贫铀表面制备金属镍镀层,利用电化学测试技术研究了镍镀层在Cl^-溶液中的电化学腐蚀行为。结果表明：在含50 μg/g Cl^-的KCl溶液中,镍镀层的腐蚀电位-100.8 mV高于贫铀的腐蚀电位-641.2 mV,相对于贫铀是阴极性镀层,对贫铀的保护基于对腐蚀介质的物理屏障;镀镍贫铀样品的极化电阻和电化学阻抗幅值远大于贫铀,其腐蚀电流远小于贫铀;约70 h的连续腐蚀实验中镍镀层未出现镀层破裂、剥落现象,且腐蚀电位、电流保持稳定。说明镍镀层对贫铀基体具有良好的防腐蚀性能。     

加速器质谱测量~(151)Sm样品化学形式的选择

151Sm(半衰期90a)属于稀土元素,它在工业、农业、国防等应用研究中占有重要地位,研究其对环境和人体健康的影响非常重要。因其在样品中、尤其在生物样品中含量很低(只有10-6～10-9),所以加速器质谱(AMS)成为实现其高灵敏测量的有效方法。AMS测量要求离子源引出的束流尽可能大而     

铀表面脉冲偏压MSIP铝镀层的电化学腐蚀行为

采用脉冲偏压磁控溅射离子镀（MSIP）技术在贫铀表面制备铝镀层,利用电化学测试技术、扫描电镜（SEM）及X射线能谱（EDS）对铝镀层在50μg/gCl－水溶液中的电化学腐蚀行为进行研究。结果表明：铝镀层的腐蚀电位－534.8mV高于贫铀的腐蚀电位－641.2mV,它对贫铀是一种阴极性镀层;镀铝贫铀样品的极化电阻和电化学阻抗幅值远大于贫铀,腐蚀电流远小于贫铀,铝镀层对贫铀基体具有良好的防腐蚀性能;镀铝贫铀样品的腐蚀特征为局部腐蚀,并出现镀层破裂、剥落,抗腐蚀性能变差;铝/铀界面伪扩散层具有一定的抗腐蚀能力。     

植物样品中~(137)Cs灰化回收率测定

粮食和蔬菜是人民的主要的主、付食。要估算由于食物对广大群众造成的剂量,需测定食物中放射性核素的含量。目前测定食物中放射性核素的方法,有物理方法和放化分析两种。由于普通植物中放射性核素的含量极少(例如~(90)Sr约为10~(-12)居里/公斤),测量方法的灵敏度又有限,因此,必须将植物样品灰化,以浓集放射性核素。放化分析约需5—10克灰(大约相当1公斤鲜样品),而γ谱仪测量需要更多。这就需灰化大量的鲜样品,故在一般生物监测中,常采用简便的温度较高的干法灰化。     

Radiation Protection Dosimetry Vol.97 No.42001

环境中的物理因子与测量专集编者按环境中的物理因子的评价 :电离与非电离辐射及噪声 R Ciri电离辐射意大利国家环境放射性监测网的质量保证程序 P D Felice科索沃土壤贫铀水平 U Sansone等地理信息系统对评价意大利南蒂罗尔和威尼托土壤氡析出潜能的的有效性 A Bertolo等不同技术方法测定食品和环境样品的铀同位素 :一项比较 M Forte估算高海拔阿尔卑斯土壤中的 1 37Cs污染浓度用的场谱测量准确度 G Agnesod环境γ剂量评价的不同方法的比较 M C Losana等含微量贫铀的环境样品中铀同位素比率的变化 :理论与实验方面 M Magnoni等意大…     

DB-1900型低本底αβ测量仪(英文)

该仪器是核测试领域中测量干样品αβ的2π发射率的仪表,它由2π零屏栅高效αβ探测器(发明专利:ZL92 1 11938.0)与反符合探测器组成的箱式探头,并同反符合技术合理结合,组成整机。其特点是:在探测器内能稳定测量面导电性差(面电阻<10~(13)Ω)的干样品的αβ发射率;既能直接测定出αβ共存发射样的β发射率,又能同时鉴别出α和β发射率,它是放射计量、辐射防护和环境保护中的一种αβ辐射测量的优质手段。该仪器可广泛用于科研、矿料、建材、塑料、药材、海陆生物等样品的αβ低辐射水平测量。     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.