蒸发处理系统中放射性去污废液pH值自动调配方案研究

废液蒸发处理系统在使用过程中曾出现上料废液pH值不稳定,导致蒸发器液位剧烈波动。对这一问题进行原因分析,探讨在上料管路中增设一套废液pH值自动调配系统来实现在线实时监测和自动调配上料废液pH值的技术方案,设计相应技术方案的工艺流程。该方案通过自动添加适量的酸或碱溶液,可以使上料废液pH值始终稳定在要求范围内。     

放射性废液蒸发器除垢方案设计及验证

针对放射性废液蒸发器处理能力短时间内明显下降,采用郎格利尔指数(LSI)等方法,对蒸发器结垢和腐蚀趋势进行了判断;重点分析了pH、蒸发温度、Ca²⁺浓度、原液流速对蒸发结垢速率的影响。结果表明:蒸发原液已具备结垢和腐蚀趋势,pH等因素改变增加了蒸发器结垢速率,结垢后蒸发器蒸发强度下降75%。借鉴民用蒸发器常用除垢方法,结合核行业蒸发器除垢具有的放射性安全要求,设计了一套放射性废液蒸发器浸泡式酸性除垢方案,用氨基磺酸进行除垢试验;经实际验证:该方案安全可行,除垢效果明显,除垢后蒸发器处理能力恢复至原设计值0.6 m³/h。     

放射性废液蒸发系统的操作条件选择

在对放射性废液蒸发处理系统进行调试过程中,通过调节废液上料量、蒸汽发生器液位、一次蒸汽流量等系统参数来改变系统运行工况,得出各工况下的净化系数,分析系统净化效果的影响因素。调试结果表明:对于该系统,蒸汽发生器液位在500mm时净化系数最高;蒸发量为1m3/h时,净化系数最高;系统在变工况运行时产生波动,净化系数降低。系统原有两条控制联锁,为一次蒸汽流量与预热器出口温度、一次蒸汽流量与蒸汽发生器液位的联锁,仅此两条联锁对于系统的稳定性不够,且一次蒸汽控制液位的控制方式灵敏性差,滞后严重。文章通过分析系统运行各参数的关系,从系统运行稳定性和净化效果的角度,提出对该系统控制方式的合理改进——调整蒸汽发生器液位与上料量联锁控制。     

中放废液的远红外蒸发处理技术研究

本文研究了用远红外蒸发技术处理中放废液的工艺条件及影响因素。探讨了远红外加热器的加热距离、系统负压、废液的pH值对各种核素(~(137)Cs、90Sr、~(147)Pm、~(95)Zr-~(95)Nb)和1AW废液的蒸发速率和去污因数影响。并对本所0.7吨中放废液进行了实际处理,二次蒸汽冷凝液的放射性浓度为1×10~(-9)Ci/l,浓缩倍数35,蒸残液已近半固体状态,需要进一步固化处理。     

天然蒸发池技术处理低水平放射性废液的发展概况

天然蒸发池技术是利用太阳能对放射性废液中多余水分蒸发、去除的一种处理方法。由于其对运行设施要求简单,不需要过多的日常维护,并具有对低放射性废液净化系数较高、处理量大、节能等特点,因此天然蒸发池技术成为一种较为常用的低放射性废液处理方法。然而,天然蒸发池的运行设施占地面积较大,需要日照时间较长,该方法的应用受到一定限制。本文通过国内外具体实例和经验,介绍了天然蒸发池技术的改进及应用情况。     

中低放废液一体化自然循环蒸发器设计

根据中低放射性废液蒸发处理工艺要求,设计一体化的放射性废水蒸发处理装置。该装置采用中央循环管式自然循环蒸发、重力分离、泡罩塔清洗和丝网除沫之类的多重工序,并集成在同一压力容器内,实现设备的一体化布置,可解决清洗液的回流问题,减少设备占地空间,简化系统和操作。通过多效净化方式,使二次蒸汽的雾沫夹带和挥发性放射性含盐量显著降低。设计的一体化自然循环蒸发器能提高废液的净化能力,提高了去污因子,符合废物最小化原则。     

放射性废物处理中心蒸发系统优化设计研究

对放射性废物处理中心蒸发系统进行简要介绍,针对传统工艺存在问题,以及无法满足新增核设施的放射性废液处理能力等问题,从二次蒸汽除沫方面对蒸发工艺核心设备及系统进行优化设计,如:降低蒸发器初级重力分离段雾沫夹带,内置泡罩塔并利用系统内净化水进行水洗,同时串联丝网除沫器进一步分离雾沫;采用带有高效聚结滤芯的净化器进行高精度净化。经理论验证,该优化设计可在保证废物最小化原则的基础上,有效提高放射性废液的净化能力和去污因子,同时简化系统设备及流程。     

红外线加热蒸发法处理放射性废液的研究

介绍了在不同ＰＨ和真空度条件下用红外线加热蒸发法处理废液的试验方法和分析结果，结果表明：该方法具有安全可靠、设备简单、操作方便、运行费用低以及化系数高达１０＾４等优点，是目前处理一些量少、成份复杂的中、低水平放射性废液的理想方法。     

移动式放射性废液接收处理装置设计

分析多种放射性废液处理方法的优缺点,结合远红外辐射加热技术与蒸发处理技术,设计一套适合复杂源项废液的移动式接收处理的试验装置,该装置具有能耗低、去污效率高、不易起泡、不易结垢等特点.     

AP1000核电厂放射性废液复用与排放研究

AP1000核电厂的放射性废液的复用与排放是水资源管理部门所关心的重要内容之一。对AP1000核电厂放射性废液的几种复用方案从技术可行性、经济合理性和工艺可靠性三个角度进行了研究,重点研究了反应堆冷却剂流出液、地面疏水和设备疏水、洗手废液、化学废液四类放射性废液的特性,包括废液产生量、放射性活度浓度、氚浓度等与废液复用潜在用户化学和容积控制系统、乏燃料池冷却系统用水关键指标的匹配程度。结果表明,反应堆冷却剂流出液、洗手废液和化学废液不具备复用可行性,建议处理后排放;地面疏水和设备疏水具备复用至乏燃料池冷却系统的可行性,建议经过处理后,复用做乏燃料池蒸发补给水。采用该复用方案后,单机组放射性废液排放量减少了1 660 m3/a,占放射性废液产生总量的55%,对实现内陆核电厂放射性废液"近零排放"具有重要意义。     

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.