改进Flower型超临界水冷快堆初步增殖研究

超临界水冷快堆集快堆和轻水堆两种特性。整个堆芯冷却剂流量仅为现BWR的1/8,中子能谱硬于普通PWR,故有一定的核燃料增殖能力。本文建立不同Flower型超临界水冷快堆堆芯物理模型,研究堆芯分区布置、冷却剂密度分层、seed及blanket组件P/D值设计、MOX燃料设计、燃料富集度分区分层布置、blanket内部通道采用贫铀冷却等方案,分析堆芯的空泡反应性、功率分布及增殖比。通过比较,得到了超临界水冷快堆的优化设计方案。     

钠冷快堆自然循环组件子通道程序初步研发

本文为计算和分析钠冷快堆自然循环组件的热工水力特性,开发了钠冷快堆堆芯自然循环冷却组件子通道分析程序。基于61棒单组件模型,通过将本程序的结果与COBRA程序进行比较,验证了钠冷快堆堆芯自然循环冷却组件子通道分析程序对自然循环冷却组件的适用性。基于多盒组件模型,初步验证了本程序具备自然循环冷却组件的流量分配和盒间换热计算的功能。本程序能为池式快堆自然循环冷却组件提供有效的设计和分析工具。     

模块化铅基快堆铀锆合金燃料堆芯概念设计优化

为深入研究第四代核能系统堆型之一铅基快堆的物理性能，进一步提高模块化铅基快堆的安全性和经济性，对铀锆合金燃料装载的不同功率水平的模块化铅基快堆堆芯特性进行研究，发现当堆芯功率提升至一定水平时，堆芯的增殖优势在规定寿期内不能得到充分释放。基于此现象，对模块化铅基快堆铀锆合金燃料堆芯的概念设计进行优化，基于堆芯功率水平和寿期，选择合适的栅距棒径比和燃料芯体有效密度，通过调整单位体积内的铀装量和²³⁵U装量调整堆芯的增殖性能，最终使堆芯反应性变化与堆芯功率、寿期基本匹配，寿期内堆芯反应性几乎不发生变化。优化后降低了堆芯反应性控制难度，充分利用了堆芯的增殖性能，同时合理的栅距棒径比为堆芯热工分析提供了安全和设计裕量，有效提高了堆芯的经济性和安全性。     

基于RELAP5和FLUENT的多尺度耦合分析方法研究

基于二次开发得到的铅冷快堆一维系统程序RELAP5_LEAD和三维计算流体力学程序FLUENT,利用动态链接库技术和FLUENT用户自定义函数,开发了多尺度耦合分析程序RELAP5/FLUENT。在单相范围内,分别利用耦合程序RELAP5/FLUENT开展简单铅冷串联管道的瞬态流动和传热模拟、简单铅冷闭式回路的瞬态流动模拟,并与RELAP5_LEAD计算结果开展Code-to-Code对比分析。研究结果表明,RELAP5/FLUENT计算结果与RELAP5_LEAD模拟结果吻合良好,耦合程序的开发取得了初步成功,可用于分析铅冷快堆堆内的复杂三维热工水力现象。     

高性能计算分析技术在大型钠冷快堆屏蔽设计中的应用

钠冷快堆堆容器是一体化的池式结构,由众多堆内构件组成且结构复杂,堆芯到生物屏蔽外中子输运过程中各向异性明显且深穿透问题严重,大尺度范围下三维S_N方法计算是制约快堆屏蔽设计的瓶颈。通过将三维SN程序与高性能计算技术相结合,采用并行计算方法可解决快堆堆本体内各向异性的三维深穿透屏蔽问题。本文以中国示范快堆（CFR600）堆本体为研究对象,采用JSNT-CFR程序详细计算了堆本体内的中子注量率、光子注量率、剂量率,并将计算结果与已有的二维程序设计结果进行比较。结果表明,将传统屏蔽计算方法与高性能计算相结合,能满足CFR600堆本体屏蔽计算精度要求,获得更为全面的三维展示效果,在计算模型复杂、粒子穿透深度等复杂问题的屏蔽计算上具有较明显的优势,为大型钠冷快堆屏蔽设计提供有力支撑。     

钠冷行波堆和驻波堆堆芯特性对比分析

采用自开发的MCNP-ORIGEN耦合程序MCORE对所设计的钠冷行波堆和驻波堆开展中子学和燃耗分析;基于MCORE获得的功率分布,采用自开发的钠冷快堆堆芯稳态热工水力分析程序SAST对钠冷行波堆和驻波堆堆芯开展热工水力分析。对比钠冷行波堆和驻波堆的堆芯物理特性和热工水力特性,结果表明：驻波堆在燃耗、最高包壳和燃料芯块温度方面具有优势,而行波堆在反应性波动和堆芯冷却剂出口温度均匀性方面具有优势。     

基于一次通过式和闭式燃料循环的快堆堆芯概念设计研究

分别针对一次通过式和闭式燃料循环提出了2种钠冷快堆概念设计,2种堆芯均采用金属燃料以达到更优的增殖性能。首先,设计了高增殖比的快堆堆芯,该方案增殖比可达到1.4,倍增时间约11 a。提出了用于长寿期运行的快堆堆芯,该方案利用倒料的方式实现堆内增殖-焚烧,达到38 a的不换料运行。在此基础上,比较了两种基于不同策略快堆设计的差异,从堆芯参数、资源利用率和经济性等角度对不同理念的快堆设计进行了初步的分析。     

钠冷快堆棒状燃料堆芯子通道分析程序开发及验证

热工水力分析软件的验证是安全审查重点关注的问题。为了实现不同设计软件间的对比验证,本工作开发出具有自主知识产权的钠冷快堆堆芯子通道分析程序SSCFR,进行中国实验快堆（CEFR）全堆芯稳态分析、子通道稳态分析及全堆芯瞬态分析,并将分析结果与CEFR运行和设计值进行对比。结果表明,SSCFR程序的计算结果与CEFR运行值及安全分析报告中的设计计算值符合较好,可用于钠冷快堆后续的软件对比验证及设计计算工作。     

一种适用于小型长寿命自然循环铅基快堆的冷却剂研究

以小型化、长寿命、自然循环为铅基快堆的设计目标，构建100 MWt铅基快堆堆芯模型并开展冷却剂选型研究，选取Pb同位素/混合物及Pb-Bi混合物，分析比较了采用不同冷却剂堆芯的物理特性与自然循环特性。结果表明：得益于²⁰⁸Pb在高能区小的非弹性散射截面与中低能区极小的中子俘获截面，加之Bi较小的中子俘获截面，采用²⁰⁸Pb-Bi冷却的铅基快堆堆芯在30满功率年运行周期内的燃耗反应性损失最小，增殖性能最佳，且具备负值较大的空泡系数、冷却剂温度系数和较大的有效缓发中子份额，可装载较低富集度或较少量燃料，有利于堆芯小型化、长寿命和固有安全性；²⁰⁸Pb-Bi相比Pb冷却的铅基快堆具备更强的自然循环能力、更弱的材料腐蚀、更宽的运行温度区间，有利于反应堆安全运行与维护。高²⁰⁸Pb丰度的铅可以从钍矿石及钍铀矿石中提取，极大降低了²⁰⁸Pb的分离提取难度。     

基于示范快堆的ADS次临界快堆堆芯研究

选取中国示范快堆作为次临界快堆参考堆芯,研究次临界快堆作为嬗变PWR(U)乏燃料中次锕系元素的可行性。中国示范快堆堆芯设计是参考目前正在建设的俄罗斯示范快堆BN-800。次临界快堆堆芯在示范快堆堆芯基础上去掉中间7盒组件放置铅靶组件,控制棒组件用含贫铀和次锕系元素(MA)的组件代替,转换区组件用反射层组件代替。采用MCNPX和ORIGEN2程序作为计算软件。计算结果表明:次临界快堆中加入MA后能够保持一定的次临界度且具有较好的嬗变效果,因此,选取示范快堆堆芯作为ADS次临界快堆的参考堆芯研究是可行的。     

OASIS程序的开发与应用

全面描述了对来自法国原子能委员会 (简称CEA)的快堆系统安全分析程序OASIS的引进和开发工作 ,并在此基础上介绍了该程序在中国实验快堆 (ChinaExperimentalFastReactor,简称CEFR)初步安全分析报告中对主给水管道断裂事故的分析计算。     

Non destructive determination of PuO2 content in MOX fuel pins for fast reactors using Passive Gamma Scanning

Use of Passive Gamma Scanning for non destructive evaluation of PuO₂ content in mixed oxide (MOX) fuels for fast reactors is demonstrated. Experiments have been carried out on MOX fuel pins for the hybrid core of Fast Breeder Test Reactor having nominal PuO₂ content of 44% and MOX pins having nominal PuO₂ content of 21% for the Prototype Fast Breeder Reactor. A comparison of results obtained using a conventional NaI(Tl) detector and that using a through well shaped detector is also presented.     

A perspective on fast reactor fuel cycle in India

The growing energy needs of India can be fulfilled only by judicious mix of all the fuel resources. It is possible to achieve energy security and sustainability through the introduction of fast reactors in an expeditious manner and closing the fuel cycle. This approach is inevitable in view of the limited uranium resources in India. The Fast Breeder Test Reactor (FBTR) built by India uses mixed carbide as fuel and the 500 MW(e) Fast Breeder Reactor Project (PFBR), to be operational in 2010, will use mixed oxide as fuel. It has also been decided that fast reactors beyond 2020, with enhanced safety features and having better economy, will use metallic fuel. Having successfully operated FBTR with carbide fuels, we need to develop the fuel cycles for both the mixed oxide fuel in the near future and the metallic fuel expeditiously. The progress achieved so far and the plans for implementation are discussed in this paper.     

Development,computer simulation and performance testing in sodium of an eddy current flowmeter

Sodium is used as a coolant in Liquid Metal Fast Breeder Reactor (LMFBR). Sodium flow measurement is of prime importance both from the operational and safety aspects of a fast reactor. Various types of flowmeters namely permanent magnet, saddle type and eddy current flowmeters are used in FBRs. From the safety point of view flow through the core should be assured under all operating conditions. This requires a flow sensor which can withstand the high temperature sodium environment and can meet the dimensional constraints and be amenable to maintenance. Eddy current flowmeter (ECFM) is one such device which meets these requirements. It is meant for measuring flow in PFBR primary pump and also at the outlets of the fuel sub-assemblies to detect flow blockage. A simulation model of ECFM was made and output of ECFM was predicted for various flowrates and temperatures. The simulation model was validated by testing in a sodium loop. This paper deals with the design, simulation and tests conducted in sodium for the eddy current flowmeter for use in the Prototype Fast Breeder Reactor (PFBR).     

Discussion and validation of a simplified analysis against buckling

The Liquid Metal Fast Breeder Reactor poses special problems in the design and construction of its important components. Its low pressures permit utilization of less expensive, thin cross-sections. But the high temperatures result in serious thermal stress and buckling problems. This paper describes the buckling design rules for the French Fast Reactor design for Class I and II components.The paper contains a simplified analysis method, offers experimental validation, and a comparison with the ASME Section III code.     

A non destructive technique for determination of U and Pu content in MOX fuel pins for fast reactors

MOX fuel pins containing both U²³³O₂ and PuO₂ have been fabricated for making an experimental subassembly for irradiation in Fast Breeder Test reactor (FBTR) at Kalpakkam, India. This unique composition of the fuel pin is chosen to simulate the thermo-mechanical conditions of the upcoming Prototype Fast Breeder Reactor (PFBR) in the existing Fast Breeder Test Reactor. Since the fertile matrix is natural UO_2, it was difficult to monitor the percentage of U²³³O₂ through chemical methods and neutron assay methods. During the fabrication of MOX fuel pins at Advanced Fuel Fabrication Facility; Bhabha Atomic Research Centre, Tarapur, Passive Gamma Scanning (PGS) was employed as one of the characterisation tools for verifying the fuel composition. PGS was found to be effective in estimating the percentage composition of both U²³³O₂ and PuO₂ and also in ensuring the uniform distribution of the fissile material in MOX fuel pins. PGS is also found effective in monitoring the correct loading of natural UO₂ insulation pellets and MOX fuel pellets in welded MOX pins.     

The design of the Prototype Fast Breeder Reactor

India has a moderate uranium reserve and a large thorium reserve. The primary energy resource for electricity generation in the country is coal. The potential of other resources like gas, oil, wind, solar and biomass is very limited. The only viable and sustainable resource is the nuclear energy. Presently, Pressurised Heavy Water Reactors utilizing natural uranium are in operation/under construction and the plutonium generated from these reactors will be multiplied through breeding in fast breeder reactors. The successful construction, commissioning and operation of Fast Breeder Test Reactor at Kalpakkam has given confidence to embark on the construction of the Prototype Fast Breeder Reactor (PFBR). This paper describes the salient design features of PFBR including the design of the reactor core, reactor assembly, main heat transport systems, component handling, steam water system, electrical power systems, instrumentation and control, plant layout, safety and research and development.     

Preliminary Thermo-mechanical Analysis of Water Cooled Ceramic Breeder Blanket for China Fusion Engineering Test Reactor

Bridging from ITER to DEMO, China Fusion Engineering Test Reactor aims at tritium self-sufficiency which is one of the main functions of blanket. The structure and thermo-mechanical performance influences strongly the operation and tritium breeding of blanket. In this paper, Water Cooled Ceramic Breeder blanket was designed with multilayer mixed pebble beds. And preliminary thermo-mechanical analysis has been done by the coupling of ANSYS finite element (FE) model and self-developed finite difference (FD) code under normal steady state condition. The results showed that the temperature distribution of the FE model corresponds well to that of the FD code. The obtained equivalent stress of the blanket is presented and critically verified the compliance with the SDC-IC code as reference criteria. At last, possible improvements such as adding fillets and plug-in materials are proposed to ameliorate the structure.     

The significance of applied mechanics in designing the fast test reactor

The discipline of applied-mechanics analysis has had a significant influence in designing the Fast Test Reactor (FTR). The FTR is a sodium-coolod fast flux reactor being constructed to test candidate materials and fuels for the U.S. Liquid Metal Fast Breeder Reactor (LMFBR) program. The influence of applied mechanics is more evident in the design of a liquid metal cooled reactor such as the FTR than it is in the more conventional water-cooled designs, primarily because the combination of environmental conditions in a liquid metal reactor results in an interplay between the mechanics analyst and the reactor designer never before required. Specifically, these environments include a fast neutron spectra, high neutron fluence (flux-time) exposures, an elevated thermal environment, and a high conductivity coolant.     

Prospective scenarios of nuclear energy evolution on the XXIst century over the world scale

Different world scenarios of nuclear energy development over the XXIst century are analyzed in this paper, by means of the EDF fuel cycle simulation code for nuclear scenario studies, TIRELIRE - STRATEGIE.Two nuclear demand scenarios are considered, and the performance of different nuclear strategies in satisfying these scenarios is analyzed and discussed, focusing on the maximum deployable capacity and the natural uranium consumption. Both thermal-spectrum systems (Pressurized Water Reactor, PWR, and High Temperature Gas-cooled Reactor, HTGR) and different designs of Fast Breeder Reactor (FBR) are investigated. A sensitivity analysis on the FBR deployment date, Breeding Gain and fuel cycle options is also presented.