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1.
实验研制了基于α能谱法的~(222)Rn/~(220)Rn子体连续测量仪。该仪器采用微孔滤膜采样,采用PIPS探测器与α能谱测量技术实现~(222)Rn、~(220)Rn子体的α粒子计数与测量。实验测试表明:在不更换滤膜的前提下,可实现~(222)Rn/~(220)Rn子体的活度浓度及潜能的有限次连续测量;测~(222)Rn、~(220)Rn子体活度浓度的下限为10 Bq/m~3,~(222)Rn子体活度浓度为100 Bq/m~3时的测量合成不确定度优于10%。  相似文献   

2.
模拟基于α能谱法的混合~(222)Rn、~(220)Rn子体测量程序,分别就醋酸纤维素酯微孔滤膜对~(222)Rn、~(220)Rn各α放射性子体的自吸收进行了实验研究。研究结果表明:该滤膜对~(222)Rn、~(220)Rn子体的自吸收以及同种滤膜间的差异较小,可取0.978为α能谱法(或总α法)的滤膜自吸收因子;微孔滤膜模拟α能谱法以120 min为测量周期,重复使用时沉积在滤膜表面的α放射性气溶胶对滤膜自吸收的影响可忽略。  相似文献   

3.
基于标准点源(~(60)Co、~(137)Cs)测量与MC模拟计算,对LaBr_3探测器的结构尺寸进行了优化,并通过模拟计算获得了La Br3探测器对~(222)Rn/~(220)Rn子体采样滤膜的探测效率。~(222)Rn子体滤膜源效率实验验证表明,LaBr_3探测器对~(222)Rn/~(220)Rn子体采样滤膜的探测效率模拟值与实际值的相对误差在3%以内。该研究结果为实现~(220)Rn子体的γ能谱准确测量打下了基础。  相似文献   

4.
对核电厂员工按工作性质、区域进行分组,运用FT-648型测氡仪对核电厂各监测区域采用经湿度校正的双滤膜法测量氡的浓度、总a五段法测量222Rn/220Rn短寿命放射性子体的浓度,研究核电厂工作人员因氡及222Rn/220Rn子体所致年有效剂量,提出高氡区域的具体防护措施.研究结果表明,核电厂中除乏燃料水池外,其他各区域...  相似文献   

5.
曾新元  刘汉钦 《辐射防护》1989,9(2):156-158
本文介绍了湖南省东南部可能有较高氡浓度的部分非铀矿山井下氡子体α潜能浓度以及地洞内~(222)Rn 及其子体α潜能浓度的调查结果。调查了有人为活动的78个地洞。其内289个测点的~(222)Rn浓度和~(222)Rn 子体α潜能浓度的范围分别为0.032—2.57kBq/m~3和0.042—9.63μJ/m~3,所调查的16个非铀矿山的~(222)Rn 子体α潜能浓度平均值的范围为1.3—1.1×10~3μJ/m~3,其中63%的矿山的~(222)Rn 子体浓度超过了 ICRP 关于工作人员吸入氡子体的限值8.3μJ/m~3(0.40WL)。  相似文献   

6.
镭是亲骨性极毒放射性元素。在镭的同位素中~(224)Ra和~(226)Ra的子体~(220)Rn和~(222)Rn均为射气。我们利用这一特点以及二者显著的半衰期差别,用射气法在同一样品中先后测定~(220)Rn和~(222)Rn,从而确定~(224)Ra和~(26)Ra的含量。 待测样品处理成溶液后,再经硫酸铅、钡沉淀载带、EDTA-2Na溶液溶解转入100ml扩散管。将该扩散管鼓泡、赶气5分钟,立即按图接入循环式测量系统。10分钟后启动循环泵,气流循环5分钟后开始计数测  相似文献   

7.
本文分析了在应用双滤膜法测定氡(气土)浓度的一般条件下采用直线速度分布的合理性,在这个基础上,建立起一个既考虑射气本身在职样管内飞行时的衰变又考虑了其子体在飞行时的积累和衰变的扩散方程,给出了一个完整的计算公式。只要用通用的扩散系数值(D=0.06 cm~2/s)代入公式,理论计算结果与 J.W.Thomas 的实验结果很好地一致,从而克服了 C.W.Tan 的扩散理论中对飞行时间限制很严的缺点和在选择扩散系数 D 值上的困难。因而使计算公式的适用性和结果的精确度都相应地得到了改善。  相似文献   

8.
空气中混合222Rn、220Rn子体浓度水平测量方法的比较   总被引:1,自引:1,他引:0  
为了对同时测量222Rn、220Rn子体浓度水平的五段法、二段法和α能谱连续测量法的特点和可靠性进行比较,在南华大学氡实验室用这三种方法进行了222Rn、 220Rn子体浓度水平的同时测量.与二段法比较,五段法测量结果较准确,但由于测量时间长(10 h以上)、测量段数多且操作麻烦,故不适合用于快速、大规模的测量;然而在高220Rn、低222Rn的建筑物中,用二段法测得的222Rn子体α潜能浓度的误差较大.采用α能谱法的LCD BWLM型222Rn、220Rn子体测量仪,具有操 作方便、能区分能量及连续测量等优点,但它需要开机8 h以上才能得到较准确的220 Rn子体浓度测量结果.对于220Rn子体浓度变化很大的实际环境,LCD BWLM型仪器测 得的220Rn子体水平结果不够准确,且该仪器在重启的同时要更换新的滤膜.  相似文献   

9.
本文介绍了一种连续监测空气中氡同位素浓度的新技术。与其他方法相比,该技术可直接测量~(220)Rn、~(222)Rn衰变的α粒子。  相似文献   

10.
氡是地球上无处不在的放射性气体,对222Rn/220Rn问题的研究一直是辐射防护和环境保护的重要课题.目前国内外222Rn测量仪比较成熟,而220Rn的测量标准还没有建立起来.222Rn/220Rn联合测量主要分为双滤膜能谱法、闪烁室延时法、α径迹蚀刻法、活性炭盒λ谱法、活性炭滤纸法、静电收集法.国内外222Rn/22...  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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%。  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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