核电厂延期换料时定期试验频度调整的评估和论证

压水堆核电站在运行初期通常采用年换料的燃料管理策略(12个自然月),为提高其经济性,在确保核安全的前提下,可实行延期换料(18个自然月)的燃料管理策略。延期换料的采用不仅会导致堆芯设计和燃料设计发生变化,也会对相关运行文件的执行产生影响,特别是核电站安全相关系统和设备的定期试验。通过应用运行经验反馈和技术经验积累、设备可靠性分析和重要度指标、概率安全分析相结合的分析方法,对定期试验频度进行确定论和概率论的综合评估和论证,从而制定合理的试验频度来满足延期换料策略的要求,最终保证核电站更安全、可靠的运行。     

核电厂多种长周期换料策略研究及改进

长周期换料是压水堆堆芯燃料管理策略的重要发展和研究方向,是提高核电厂燃料利用率和经济性的重要途径之一。本文以AP1000核电厂为例,开展了多种长周期换料策略的堆芯燃料管理研究,以实现核电厂16～24个月灵活的长周期换料策略,并为后续的长周期换料策略研究提出改进方向。本文基于同一首循环堆芯装载方案设计,对各种长周期换料策略下的平衡循环堆芯装载方案进行研究,且采用低泄漏布料方式以获得良好的经济性。本文的研究实现了16～24个月灵活的多种长周期换料策略,且通过比较表明,18个月换料策略的燃料利用率与16/20个月交替换料策略的燃料利用率相近,24个月换料策略的燃料利用率相对较低,经分析发现这主要受限于燃料棒燃耗限值和目前商用压水堆燃料的最大富集度限值。因此,提高燃料棒燃耗限值和商用压水堆燃料的最大富集度限值是后续长周期换料策略研究的重要改进方向。     

发扬成绩,总结经验,不断创新,持续改进

核电站的安全、可靠和经济运行是核电事业发展的基础。不断提升核电站的安全水平、运行业绩、提高核电的竞争力是核电发展的永恒主题。核燃料及燃料管理直接关系到核电站安全水平和运行的经济性,是核电站技术改进和安全改进的核心领域。而设备管理是保证核电站设备长期安全可靠运行的重要基础。在燃料管理方面,经过多年的实践,广东核电的燃料管理取得了长足的进步。燃料管理的队伍也不断成长壮大。20世纪80年代末、90年代初引进AFA 2G燃料组件制造技术及引进换料堆芯设计技术。20世纪90年代初引进、消化、吸收西屋全套燃料管理设计技术,并应用到电站的燃料管理设计和改进论证中。20世纪90年代中期实现AFA 2G燃料组件供应国产化。从燃料监造、换料设计到运行堆芯监督各方面从严把关,大大提高了燃料的可靠性,燃料可靠性指标连续多年保持在国际先进水平。1998年,经过广东核电、中国核动力研究设计院(NPIC)的共同努力,实现了换料设计的国内化。NPIC从第五循环开始承担大亚湾核电站的换料设计工作。1997~1999年:针对大亚湾核电站高压安注系统存在的可用率较低的问题,经过自主分析,发现了原始设计的不合理之处。经过独立分析论证,提出将高压安注...     

秦山核电二期工程堆芯设计

介绍了秦山核电二期工程堆芯核设计的总体思路、设计内容及电厂实测结果与理论预计值的比较.设计吸取了20世纪90年代初压水堆核电站先进的设计思想,采用了低线功率密度堆芯,提高了堆芯安全裕量;换料设计中,采用1/4换料方式,既满足了年换料制要求,又提高了燃料利用率,燃料组件批平均卸料燃耗满足设计要求.按设计要求确定了堆芯燃料管理方式,完成了堆芯性能参数分析,满足了总体设计对循环长度、堆芯功率分布、慢化剂温度系数、停堆裕量、组件卸料燃耗限制等安全性和经济性要求.1号机组启动物理试验和功率运行实测结果表明,控制棒价值、临界硼浓度、等温温度系数以及堆芯功率分布等设计预期值与实测值符合良好.     

压水堆多堆联合堆芯装载设计技术应用研究

在压水堆之间开展的多堆联合堆芯装载设计技术能提高堆芯装载设计的灵活性,研究其对燃料经济性和机组在燃料组件损坏情况下应对能力的影响。分析了多堆联合堆芯装载设计技术对来自其他机组燃耗过燃料组件的相容性要求。计算了燃耗过燃料组件的余热与冷却时间的关系,列出了可用于燃耗过燃料组件运输的大负荷乏燃料运输容器。分析了首循环堆芯和换料堆芯面对燃料组件损坏后堆芯装载设计的应对能力,以及在采用多堆联合堆芯装载设计技术后的应对能力改善情况。开展了多堆联合首循环堆芯装载模拟设计并分析了其经济性。研究结果表明,首循环出现燃料组件损坏的风险比后续换料堆芯大,而由全新燃料组件组成的首循环应对燃料组件损坏的能力最低;通过多堆联合堆芯装载设计技术可以把首循环转化为换料堆芯,不仅能凭借换料堆芯的设计灵活性提高应对燃料组件损坏的能力,还能节省约3.2亿元人民币的燃料费。因此,多堆联合堆芯装载设计技术能提高首循环的燃料经济性和机组面对燃料组件损坏后的应对能力。     

台山核电厂CEPR堆芯设计及燃料管理

台山核电厂采用了第三代压水堆核电技术的CEPR。堆芯采用较大的堆芯尺寸,降低了堆芯的线功率密度,提高了中子经济性;控制棒使用T模式,提高控制棒的控制效率,减小控制棒磨损;通过引入富集硼,优化了冷却剂的化学控制;从首循环开始进入18个月换料的燃料管理方案最大程度上提高了燃料经济性。     

大亚湾核电站第十循环堆芯换料设计

大亚湾核电站第十循环堆芯是自提高燃料组件富集度后实现18个月燃料循环的第二个循环堆芯。堆芯换料设计采用SCIENCE核程序包进行计算,辅以HADESⅡ处理程序,自动生成一维模型和综合法程序输入数据,并且自动生成换料设计报告。报告介绍了堆芯换料设计须提交给核电站的设计文件和所用的计算机软件,并对启动物理试验实测值与设计预计值进行了比较分析。     

AP1000核电厂灵活循环燃料管理策略研究及应用

我国核电装机容量逐年稳步扩增,核电厂参与电网调峰愈加频繁,固定的换料周期逐渐难以满足核电厂经济运行的需求。本文基于AP1000核电厂18个月堆芯装载方案,设计了±1个月和±2个月的灵活周期堆芯装载方案,完成方案的安全性限值与燃料经济性评价,开展完整的安全分析。结果表明,堆芯设计满足安全相关验收准则的要求,全面论证了灵活循环燃料管理策略的安全性和可行性。本研究为AP1000核电厂灵活循环周期运行提供了技术支撑,灵活循环周期运行即将在海阳核电厂中工程应用。     

157组燃料组件组成的堆芯燃料管理研究

本文应用SCIENCE程序包对157组燃料组件组成的压水堆堆芯进行换料优化燃料管理研究,给出了3个年换料和2个18个月换料共5个设计方案,每个设计方案给出了从首循环到第8循环共8个循环的主要计算结果,并进行了分析比较。综合来看,OUT-IN装载的设计方案功率峰值偏低,IN-OUT装载的设计方案功率峰值偏高,但均在设计限值以内;1/4堆芯换料设计方案的平均卸料燃耗最深,表明其组件燃耗得最充分,经济性较好。     

大功率压水堆堆芯燃料管理设计

设计了一种大功率压水堆堆芯,对其中可燃毒物装载方案、平衡循环布置、首循环装料及过渡循环方案进行了研究。采用特征统计算法CSA燃料管理优化程序,快速高效地搜索堆芯装载和可燃毒物配置优化方案。采用堆芯核设计程序CPACT进行全堆计算,结果真实可靠。分别设计了18个月和24个月换料两种方案,计算结果表明,在满足堆芯燃料管理所有限值要求的前提下,两种方案均从第4循环开始进入平衡循环。     

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.     

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.     

Gamma radiation levels in the ambient environment of the QNPP Base

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.