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。     

模块式小型压水堆ACP100堆芯燃料管理策略研究

为将多用途模块式先进小型压水堆(ACP100)堆芯换料周期提升至24个月,兼顾良好的燃料利用率并保证功率展平特性满足安全性的限值要求,本文使用具备工程经验的成熟软件,进行不同的批料数、不同富集度组合、不同径向装载模式等组合方案的燃料管理研究,通过研究掌握了不同策略特征并形成ACP100堆芯燃料管理推荐策略:选取3批次换料、24盒组件/批的倒料策略,结合部分低泄漏装载模式,作为ACP100堆芯燃料管理推荐策略,同时进一步提高燃料富集度以提升燃料经济性。     

百万千瓦级压水堆核电站长燃耗堆芯钆可燃毒物优化研究

对百万千瓦级参考核电站长燃耗堆芯（１８个月换料）采用的可燃毒物（钆）含量与堆芯燃料管理主要结果进行了分析研究。该研究采用先进的燃料管理程序系统,对不同可燃毒物含量和不同可燃毒物棒根数的燃料组件进行了计算,给出了组件无限增殖因子（ｋｉｎｆ）随燃耗的变化关系,据此对参考堆芯采用相同的装载进行了４种方案燃料管理计算。计算结果表明,对于堆芯燃料管理,采用低可燃毒物含量、含可燃毒物棒数多的装载方案明显优于高可燃毒物含量、含可燃毒物棒少的堆芯装载方案。     

双富集度18个月换料燃料管理可行性研究

针对核电厂18个月换料模式下组件批卸料燃耗不高、燃料利用率不高等问题,采用富集度分别为4.45%和4.95%的2种燃料组件进行燃料管理方案设计,给出了双富集度18个月换料的主要计算结果。结果表明,通过对燃料组件和可燃毒物进行合理化布置,双富集度18个月换料方案可以满足18个月换料周期运行的设计准则要求。在相同的循环长度下,堆芯平均卸料燃耗更高,组件使用费用更少,经济性更好。     

径向步进倒料行波堆的数值研究

行波堆是一种可实现自持增殖-燃耗的新概念快堆,它可直接使用天然铀、贫铀、钍等可转换核材料,实现非常高的燃料利用率。基于行波堆的原理,提出了具有现实应用价值的径向步进倒料行波堆的概念,并将其与典型钠冷快堆的设计相结合,采用数值方法对由外而内的径向步进行波堆二维渐近稳态特性进行了研究。计算结果表明:渐近keff随倒料循环周期近似抛物线分布,而渐近燃耗随倒料循环周期线性增长,满足临界条件的倒料循环周期中最大燃耗可达38%;堆芯功率峰随着倒料循环周期的增长,从燃料卸出区(堆芯中心)向燃料导入区(堆芯外围)移动,功率峰值逐渐降低,在高燃耗情况下,靠近堆芯中心的轴向功率分布呈M形。     

百万千瓦级环形MOX燃料堆芯设计

对环形UO2燃料及环形MOX燃料组件参数的计算方法进行了研究。设计了包含193盒环形UO2和MOX燃料组件的混合型长周期(18个月)堆芯方案。对设计的堆芯的重要物理参数进行了分析,并对各循环进行了燃耗计算。结果表明,装载约30%MOX组件的堆芯可在百万千瓦功率下实现长周期换料。堆芯从初装载可安全过渡到平衡循环,各循环的重要物理参数均满足设计要求,说明设计的堆芯及燃料管理方案是安全可行的。     

超临界水堆CSR1000堆芯设计优化

利用开发的超临界水堆(SCWR)堆芯稳态性能分析程序SNTA,研究分析中国百万千瓦级SCWR(CSR1000)优化堆芯燃耗性能、反应性控制能力、功率分布、最大燃料包壳温度和最大线功率密度等稳态性能,并给出与组件功率相匹配的第II流程冷却剂流量分配方案。研究表明,采用本文所述燃料组件及堆芯设计优化方法,可以有效延长堆芯燃耗寿期。     

百万千瓦级压水堆核电站长燃烧堆芯钆可燃毒物优化研究

对百万千瓦参考核电站长燃耗堆芯采用的可燃毒物含量与堆芯燃料管理主要结果进行分析研究。该研究采用先进的燃料管理程序系统，对不同可燃毒物含量和不同可燃毒物棒根数据的进行了计算，给出了组件无了增殖因子随燃耗的变化关系，据此对参考堆芯采用相同的装载进行了４种方案燃料管理计算。     

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.     

秦山核电厂燃料管理策略改进的研究和实施

堆芯燃料管理是涉及核电厂安全性和经济性的重要管理工作,也是核电厂运行期间最具灵活性的管理工作。在保证堆芯燃料安全运行目标的同时,合理确定堆芯燃料管理策略和换料技术路线,可以提高燃料的利用率,降低燃料循环成本,实现较好的核电厂经济性指标。秦山核电公司基于自身的燃料管理特点,从第四燃料循环起,通过燃料管理策略改进的可行性分析、分阶段实施燃料组件加深燃耗的随堆考验和性能跟踪评价等研究。逐步将国产化燃料的批平均卸料铀燃耗从设计之初的25 GWd/t提高到34 GWd/t,取得了国产化核电机组反应堆运行的安全性与经济性双重效益。     

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.