安全级数字化仪控系统行为确定性设计分析

安全级数字化仪控系统行为逻辑通过软件承载,但软件可靠性评价相对困难,因此为确保安全级数字化仪控系统行为的复现性和及时性,保障系统的可靠性和安全性,需开展行为确定性设计。本文依据标准要求并结合工程经验,提出了安全级数字化仪控系统确定性设计需求,并从安全级数字化仪控系统确定性体现的两个方面出发,提出可通过基于模型的形式化建模来保证系统的复现性,通过对系统各个环节响应时间的分配来保证系统响应的及时性,为安全级数字化仪控系统行为确定性设计提供参考。      

“华龙一号”数字化仪控系统纵深防御设计

福岛核事故后,核电厂纵深防御的设计理念得到新的发展,纵深防御层次设置和层次间独立性的安全要求进一步提高。而核电厂数字化仪控系统设计除了满足电厂总的纵深防御目标,保证在核电厂各种工况下正确可靠的执行监视、控制和保护功能之外,还需要考虑自身的数字化系统共模故障等问题。为了保证"华龙一号"数字化仪控系统设计始终满足国际最新核安全要求,为核电出海做好技术储备,一方面对国际原子能机构,西欧核监管联合会,美国核管会仪控系统纵深防御相关的最新法规要求和技术见解进行了解读和分析,归纳出共性要求;另一方面详细论述了中核集团"华龙一号"机组仪控系统整体纵深防御设计方案,并对其与前者的符合性进行了分析。通过分析,"华龙一号"仪控设计现有设计方案基本满足国际最新核安全要求,同时如进一步提升多样化保护系统独立性等问题需要在后续设计中予以关注。为"华龙一号"数字化仪控系统设计的持续改进提供了有价值的参考。     

基于NUREG/CR-7007的DAS优化设计

基于对NUREG/CR-7007中多样性准则的数据分析,归纳出各多样性准则的内在关系,利用量化多样性的方法,建立了可用0-1规划求解的、最小代价多样化驱动系统的数学模型。解决了确保预设归一化多样性量值要求下的、最小代价的多样化驱动系统是什么的问题。仿真算例表明,本方法是高效、可行的,能应用于保护系统的多样性设计及优化。     

核电站仪控系统的多样性评估方法及应用

为避免或减轻核电站数字化仪控系统软件共因故障,提出了一种半定量的多样性评估方法。该方法基于核电站运行经验,对各类多样性属性及其多样性准则分配有效性权重,开发了多样性评估工具,可用于核电站仪控系统的多样性评估工作,借助于该方法能及时发现设计的薄弱环节并改进。     

核安全级数字化仪控系统自诊断功能研究与设计

自诊断功能是核安全级数字化仪控系统的关键功能,对核安全级数字化仪控系统本身的RAMS特性,以及核电厂整体安全性和可用性有直接影响。本文基于RAMS分析评估技术,形成了以潜在故障模式为主的自诊断功能设计基准,在此基础上提出了一整套包括故障诊断、故障处理、诊断信息上报和报警指示功能的核安全级数字化仪控系统自诊断功能设计方案,并在和睦系统上进行了设计实现。实测结果表明,和睦系统可以实时在线监视自身运行状态,能够及时处理、上报和精确指示所有设计基准范围内的异常,大幅增强了故障定位能力,提高了和睦系统的可维修性,充分满足核电厂整体安全性和可用性要求。     

可用性分配法优化核电厂非安全级DCS系统设计

为核电厂非安全级数字化仪控系统(DCS)系统在设计阶段明确板卡级设备可靠性要求,在产品设计阶段利用可靠性分配方法将可用性指标合理地分配到组成系统的各部件中,可用性分配结果是开展可靠性预计工作目标和设计参考依据,可靠性预计结果是进行可靠性指标分配调整与系统指标验证的基础,二者相辅相成,通过迭代分配和指标验证为实现核电厂非安全级DCS系统设计优化提供参考。     

综合评价法在核电仪控产品设计中的应用

为了在有限的时间内更加合理地确定设计方案,在核电数字化仪控系统产品设计中引入了TOPSIS综合评价法,该方法可直观地用数据反映出方案的优劣,缩短了选择最佳设计方案的时间,通过这种方法优选出的方案综合性能指标更加合理。TOPSIS综合评价法在核电数字化仪控系统某型号机箱的结构设计方案优选中应用,取得了良好效果。     

数字化人机界面设计的人因工程问题分析

数字化仪控技术在核电站的应用是重要的改进,也是重大的挑战。采用数字化仪控技术、以数字化人机界面为主要操作方式的先进控制室在国际和国内新建核电站正在得到广泛应用。分析了数字化仪控系统带来的人因工程方面的新挑战,结合安全法规标准要求、人因工程理论,指出了先进主控室数字化人机界面设计需要解决的主要问题。根据认知理论阐述了新的操纵员任务—资源需求—认知模型,指出界面管理造成的认知资源消耗与信息瓶颈是造成人因失误的根本原因,提出了任务导向人机界面设计原则,并探讨了人机界面设计的发展趋势。     

基于PSA技术的核电厂数字化仪控系统可靠性设计及应用

传统意义上核电厂数字化仪控系统主要依靠提升设备的可靠性来满足电厂安全目标。随着监管要求的逐步提高，在提升设备可靠性基础上，基于概率论技术的设计手段逐步成为核电厂安全设计新的研究方向。本文应用概率安全评价（PSA）技术，对典型电厂始发事件进行分析及研究，之后对仪控设计方案整体进行PSA建模，再将其置于电厂PSA模型中，通过定量评估分析，识别薄弱环节，给出优化改进措施。在此基础上提出了一套确保核电厂仪控系统满足整体安全目标的可靠性设计流程。      

核电厂数字化仪控系统信息安全监管要求探讨

本文给出了核电厂信息安全的概念和内涵,研究了IAEA和NRC对核电厂数字化仪控系统信息安全的要求,分析了我国法规对核电厂数字化仪控系统信息安全的要求,对强化数字化仪控系统信息安全监管要求提出了建议。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

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%。     

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.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

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。     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

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.     

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.