P_(301)型天然无机材料处理含钚、镅废水的研究

本文报道了用加工处理后的 P_(301)型天然无机材料处理含钚、镅废水的研究。对国内不同地区的样品进行了筛选,并对料液中钠、钙离子浓度,酸碱度及络合剂浓度等影响因素进行了试验。结果表明,在弱酸性介质中,对钚、镅的分配比(K_d)可达10~3—10~4,而较大量的钠盐和一定量的钙盐存在对分配比的影响较小。用模拟含钚、镅废水(~(239)Pu 比放为5.2×10~(-5)Ci/L,~(241)Am 比放为8.3×10~(-6)Ci/L)通过填装 P_(301)型天然无机材料的柱子,钚和镅的穿透床体积数分别为1100、1500时,其去污因数均大于10~4。     

尿中~(106)Ru的测定

本方法主要包括尿样前处理,高锰酸钾氧化蒸馏,氢氧化钌沉淀制源和β测量四个部分。方法的平均放化回收率为93.4±5.9%,灵敏度为7.1×10~(-13)Ci/l。对~(90)Sr、~(99)T~(144)Ce、~(131)I、~(95)Zr、~(60)Co、~(134)Cs等7个核素的去污因数均在10~4以上。六个样品的全程化学操作需10h。一、实验部分     

快速鉴别空气中人工放射性污染：β衰变比值法

本文阐述了用“β衰变比值法”鉴别空气中长寿命人工β放射性污染的原理。介绍了依据该原理设计的仪器设备,从实测数据分析得到,当天然β气溶胶浓度为7.49Bq/m~3(约2×10~(-13)Ci/L),取样1h,取样量为3.36m~3空气时,取样结束后60min,检出水平为1.82Bq/m~3(4.9×10~(-14)Ci/L);取样结束后150min,检出水平1.77Bq/m~3(4.8×10~(-14)Ci/L)。     

北京景泰兰工艺及原材料中放射性含量的测定

我们对北京首饰公司和珐琅厂的景泰兰工艺品颜料、原材料和部分产品中的放射性核素及含量进行了测定。结果表明:在多数颜料和原材料样品中,总β放射性含量在5×10~(-12)Ci/g 以下,低于一般土壤中总β含量(2×10~(-11)Ci/g);样品中所含主要放射性核素为天然~(40)K,某它放射性核素未测山;因此,可以认为使用景泰兰工艺品是安全的。     

大面积流气式正比计数管及其实验装置

本文介绍对一种大面积流气式正比计数管实验装置的技术指标的实测结果,推算其α最低测量限为1.1×10~(-6)μCi/cm~2,β最低测量限为4×10~(-6)μCi/cm~2。     

在~(41)Ar存在情况下空气中氚水蒸气浓度的连续监测

本文介绍了一种采用气液混合取样方法和液体闪烁计数技术相结合的氚连续监测装置。它的取样原理是基于~(41)Ar 和氚水蒸气(HTO)在闪烁液中溶解度的差异,使得~(41)Ar 在液相中的存留量不致于对欲测的 HTO 造成严重的干扰。装置本底为14cpm,其刻度系数对应于5×10~(-9)Ci/L 的 HTO 为6.8×10~3pm,响应时间为20分钟,无~(41)Ar 存在下探测下限至少可达到9×10~(-12)Ci/L(空气) (95%置信度)。当反应堆现场的~(41)Ar 平均浓度为3×10~(-8)Ci/L 时,对 HTO 的探测下限低于1×10~(-10)Ci/L。     

237Np、238Pu和241Am在包气带黄土中迁移的模拟实验

本文介绍了237Np、238Pu和241Am在包气带黄土中迁移的模拟实验方法和结果.实验土柱尺寸为φ280 mm×1200 mm,示踪源层由示踪核素的硝酸盐溶液与石英砂(40～80目)混合后风干形成,尺寸280 mm×5 mm,核素迁移实验在喷淋(5.5～5.6 mm/d)条件下进行.对于237Np在土柱内垂向分布和迁移速度,实验期间用γ谱仪进行柱外直接测量.同时在实验进行1073 d和665 d后分别对1#和2#土柱中的237Np、238Pu和 241Am进行解体取样测量.经1073 d,237Np、238Pu和241Am在1#柱内比活度峰位分别向下迁移3.25、0.25和0.25 cm,其平均迁移速度分别为3.03×10-3、2.33×10-4和2.33×10-4cm/d.经665 d后2#柱内三种核素比活度峰位分别向下迁移1.25、0.25和0.25 cm,其平均迁移速度分别为1.88×10-3、3.76×10-4和3.76×10-4cm/d.237Np、238Pu和 241Am三种核素的比活度分布质心在1#和2#柱内分别向下迁移2.79、0.73、-0.09 cm和1.48、0.41、-0.27 (1073 d)和2#(665 d)柱内 237Np、 238Pu和 241Am垂向扩散参数σx(t)分别为1.29×10-3、9.86×10-4、5.03×10-4和2.00×10-3、2.12×10-3、1.08×10-3 #cm;在1cm;其延迟系数分别为1.03×103、3.93×104、3.18×104和1.17×103、4.25×103、6.45×103.由于石英砂和黄土是两种不同介质,在示踪源层处核素比活度分布呈现"低谷"现象.     

环境水样品中~(131)I、~(126)I 的测定

本文介绍环境水样品中~(131)I、~(125)I 的测定方法。采用强碱性阴离子交换树脂浓集,CCl_4萃取,最后制成 AgI 沉淀源,由低本底β计数器和γ谱仪及 X 射线谱仪测定。本方法灵敏度对~(131)I 为7.7×10~(-14)Ci/1(2.8Bq/m~3),对~(125)I 为0.578×10~(-12)Ci/1(21.4Bq/m~3)。对环境中地下水、水库水、海水各取5—101,加入~(131)I 强度2.8×10~(-12)Ci/1(0.1Bq),试验结果其化学回收率分别为75—80%,放化回收率与化学回收率相符合。本方法对~(106)Ru-~(106)Rh 核素和总裂片的去污系数在1.2×10~5以上。10小时可分析6个样品。     

水体中总α总β放射性水平的测量

本文介绍以1升环境水样,用蒸发法制备样品,在具有金硅面垒半导体探测器及反符合屏蔽的低水底α-β测量装置上,同时测量水体中总α、总β放射性强度的方法。本方法的测量灵敏度,对总α为4.8×10~(-2)Bq/l,总β为1.9×10~(-2)Bq/l,最低探测限,对总α为2.4×10~(-2)Bq/l,总β为1.9×10~(-3)Bq/l。     

放射性气溶胶自动监测仪

本文阐述了新研制的“放射性气溶胶自动监测仪”设计原理、功能和技术指标。该仪器采样、测量和数据处理均全自动化,其最小可检出水平:用样品放射性活度表示,对β为54mBq,当采样量为10m~3时,可检出浓度为5.4mBq/m~3(1.46×10~(-16)Ci/L);对于α可达3.6mBq,若采样量为10m~3时,可检出浓度为0.36mBq/m~3(9.7×10~(-18)Ci/L)。     

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.