苏州某燃煤电厂气载放射性排出物环境影响评价

根据苏州某大型燃煤电厂烟尘排放所致周围环境近地面空气中天然放射性核素的浓度和地面沉积量及其分布,估算了该厂气载放射性排出物对厂区周围半径100km范围内公众居民经蔬菜、农作物食入,飘尘吸入和地表γ沉积的内、外照射途径所致的归一化人均有效剂量当量和归一化集体有效剂量当量。估算结果表明,最大污染浓度位于下风向SW-NW区间距烟囱1km处;归一化人均有效剂量当量是4.17×10~(-4)Sv/GWa;对厂区周围半径100km范围内2.1×10~7公众居民的归一化集体有效剂量当量是40man·Sv/GWa。     

湖南省主要食品中~(210)Pb和~(210)Po含量的调查

本文报道了湖南省主要食品中~(210)Pb 和~(210)Po 含量的调查结果。所调查的17类食品中~(210)Pb 和~(210)Po的含量范围分别为0.02—11.8和0.04—15.6Bq·kg~(-1),由此估算出湖南省居民由食品摄入~(210)Pb 和~(210)Po 所致待积有效剂量当量分别为102.6和29.6μSv。     

北京地区人骨中^232Th活度及所致内照射剂量

本文报道了北京地区57例居民骨灰样品中~(232)Th 活度的中子活化分析结果。结果表明。人骨灰中~(232)Th 比活度的算术均值和中位数分别为7.6×10~(-4)和5.6×10~(-4)Bq/g,骨中~(232)Th 活度的算术均值和中位数分别为1.2和0.90Bq;所致骨表面细胞和红骨髓器官年吸收剂量分别为52μGy/a和4.0μGy/a;所致内照射的年有效剂量当量为41μSv/a,居民的膳食组成对这一结果可能有明显的影响。     

燃煤电厂气载放射性排出物对环境影响的辐射剂量评价

根据苏州某大型燃煤电厂烟尘排放所致周围环境近地面空气中天然放射性核素的浓度和地面沉积量及其分布的计算结果和辐射剂量的估算模式,估算了该厂气载放射性排出物导致厂区周围半径100km范围内经蔬菜、农作物摄入、漂尘吸入和地表沉积γ的内外照射途径公众居民所受的个体全身年平均剂量当量和集体剂量当量。估算结果表明,最大污染浓度的下风向SW～NW区间距烟囱1km处的个体全身年平均剂量当量值为3.13×10~(-4)Sv(GW·a)~(-1),其中 由摄入和吸入途径所受的内照射剂量分别为3.02×10~(-4)Sv(GW·a)~(-1)和8.14×10~(-6)Sv(GW·a)~(-1);地表沉积γ外照射剂量为2.94×10~(-6)Sv(GW·a)~(-1)。厂区周围半径100km范围内公众居民的集体剂量当量值为30.5man-Sv(GW·a)~(-1),其中摄入和吸入途径的内照射剂量分别为26.5和3.70man-Sv(GW·a)~(-1);地表沉积γ外照射剂量为0.34man-Sv(GW·a)~(-1)。     

中国食品和水中天然放射性核素水平及其对居民所致内照射剂量

为获得中国食品和水中天然放射性核素水平的本底资料,卫生部组织了全国各省、自治区、直辖市放射卫生防护机构完成了全国范围的各种食品和水源水的采样和分析测量工作。食品中天然放射性核素的平均比活度U为(2.2～25.5)×10~(-2)Bq/kg。Th为(0.5～6.9)×10~(-2)Bq/kg、~(226)Ra为(3.4～25.5)×10~(-2)Bq/kg、~(40)K为(25～420)×10~(-2)Bq/kg、~(210)Pb为(3.9～55)×10~(-2)Bq/kg、~(210)Po为(2.7～58)×10~(-2)Bq/kg。饮水以自来水和井水为主,水中U的平均浓度分别为2.8和3.7×10~(-2)Bq/L、~(226)Ra为0.8和1.3×10~(-2)Bq/L,Th为0.07和0.06×10~(-2)Bq/L,~(210)Pb为0.3和1.1×10~(-2)Bq/L、~(210)Po为0.3和0.5Bq/L。对天然放射性核素经消化道进入人体内六种主要天然放射性核素的年摄入量估计为205Bq,其中通过饮水U的摄入量占总U摄入量的64％,粮食对~(226)Ra、~(210)Pb、~(210)Po的摄入量分别为55.7％、59.7％和70％。估计的对中国成年男人六种主要天然放射性核素所致的人均年有效剂量当量总和为310μSv。     

北京地区土壤中~(232)Th、~(226)Ra、~(40)K浓度及其对天然γ辐射剂量的贡献

为调查北京地区外环境中来自地层的天然放射性核素的辐射剂量,在用现场辐射仪测量的同时,用φ75×75mm NaI(Tl)-塑料反符合低本底γ谱仪,分析了北京地区143个土壤样品。结果表明,北京地区表层土壤中~(232)Th、~(226)Ra 和~(40)K 浓度随地点、地形、成土母质类型有很大变化,其平均浓度分别为8.61×10~(-6)g/g、4.98×10~(-13)g/g 和2.31×10~(-6)g/g。由~(232)Th 及其子体、~(226)Ra 及其子体和~(40)K 平均浓度所致离地面1m 高处的空气吸收剂量率分别为2.31μrad/h、0.79μrad/h 和2.58μrad/h,总计为5.68μrad/h;~(232)Th 及其子体和~(40)K 的贡献约各占40%,~(226)Ra及其子体的贡献小于20%。按全市人口加权的空气总吸收剂量率为5.59μrad/h,由此所致的本市居民的年有效剂量当量为45.2mrem。     

中国食品和水中天然放射性核素水平及其对居民所致内照射剂量

为获得中国食品和水中天然放射性核素水平的本底资料,卫生部组织了全国各省、自治区、直辖市放射卫生防护机构完成了全国范围的各种食品和水源水的采样和分析测量工作。食品中天然放射性核素的平均比活度U为(2.2～25.5)×10~(-2)Bq/kg。Th为(0.5～6.9)×10~(-2)Bq/kg、~(226)Ra为(3.4～25.5)×10~(-2)Bq/kg、~(40)K为(25～420)×10~(-2)Bq/kg、~(210)Pb为(3.9～55)×10~(-2)Bq/kg、(210)Po为(2.7～58)×10~(-2)Bq/kg。饮水以自来水和井水为主,水中U的平均浓度分别为2.8×10~(-2)和3.7×10~(-2)Bq/L,~(226)Ra为0.8×10~(-2)和1.3×10~(-2)Bq/L,Th为0.07×10~(-2)和0.06×10~(-2)Bq/L,~(210)Pb为0.3×10~(-2)和1.1×10~(-2)Bq/L、~(210)Po为0.3和0.5Bq/L。对天然放射性核素经消化道进入人体内六种主要天然放射性核素的年摄入量估计为205Bq,其中通过饮水U的摄入量占总U摄入量的64％,粮食对~(226)Ra、~(210)Pb、~(210)Po的摄入量分别为55.7％、59.7％和70％。估计的对中国成年男人6种主要天然放射性核素所致的人均年有效剂量当量总和为310μSv。     

中国燃煤发电排放的放射性环境影响评价研究

选取不同装机容量等级的典型燃煤机组作为研究对象,按照不同地理区域划分滨海北方、滨海南方、内陆北方、内陆南方等4个评价区,采用一批新的调查数据和参数,评价当前我国燃煤发电排放的放射性环境影响。结果表明:(1)全国燃煤电厂放射性排放所致80 km范围公众的归一化集体剂量平均值为2.2人·Sv/GWa。(2)小火电机组所致剂量约为6.0人·Sv/GWa,主流燃煤机组约为1.8人·Sv/GWa,小火电机组是主流燃煤机组的约3倍。(3)剂量贡献最大的核素是²¹⁰Po,其次是²¹⁰Pb。食入和吸入内照射是主要照射途径。(4)不同燃煤电厂周围的人口密度差别很大,使得集体剂量相差可达1个数量级。基本结论:与天然辐射源所致公众照射剂量相比,燃煤发电的辐射环境影响仍然很小;煤电的辐射环境影响是核电的34倍。淘汰小火电机组、实施超低排放改造,我国燃煤发电所致公众归一化集体剂量仍有进一步降低的空间。目前电厂除尘技术难以高效去除和有效控制²¹⁰Po排放,有必要进一步研究。     

秦山核电厂气载放射性释放的环境影响

本文评价了秦山核电厂气载放射性流出物对环境的影响。应用现场及风洞大气扩释实验结果和厂址周围的人口与食谱调查资料,估算了秦山核电厂在正常运行和事故条件下释放的气载放射性流出物对公众产生的个人有效剂量当量和集体有效剂量当量。计算结果表明,正常运行时厂址边界(0.5km)处的最大个人有效剂量当量为2.7×10~(-2)mSv/a,该剂量的大部分来自~(137)Cs 的食入(主要由地表湿沉积引起);80km 范围内的集体有效剂量当量为1.1人·Sv/a,归一化集体有效剂量当量为3.7人·Sv/GW(e)·a。文中还给出了事故情况下剂量估算结果。     

大亚湾核电站1994～2002年职业性照射个人剂量监测和评价

本文总结了大亚湾核电站1994～2002年辐射工作人员职业性照射个人剂量的监测和评价结果.九年中,大亚湾核电站工作人员(包括参加核电站机组检修和为核电站提供各类支持服务的承包商人员)所受到的外照射累积集体剂量为11.6人·Sv,归一化集体剂量为0.879人·Sv/GWa,没有发现大于年摄入量限值1%的内沾染人员;年人均有效剂量为0.56 mSv,单年度个人剂量超过20 mSv的仅有4人,最大值为36.3 mSv.     

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.