CEFR新燃料组件贮存临界安全分析

为论证新燃料组件贮存是否满足核临界安全要求,对CEFR新燃料贮存系统进行核临界安全分析计算。 新燃料组件贮存系统由1、2号格架组成,每个格架可贮存56个(7层×8个)组件容器,一个组件容器里装2盒组件,即每个格架可贮存包括控制组件、燃料组件等在内的112盒组件。新燃料组件首先     

带7道格架的5×5棒束两相性能CFD分析

采用两相计算流体动力学（CFD）方法进行带7道格架的5×5棒束两相性能研究，其中结构搅混格架（MG）和跨间搅混格架（MSMG）交替布置，计算考虑汽泡合并与破裂、热量传递，但不考虑相间的质量传递。为选择合理的两相模型参数，首先以带2道格架（MG、MSMG）的AFA3G燃料组件5×5棒束架为研究对象，对最大气泡直径、汽泡合并破裂系数、非曳力模型及曳力模型、入口气泡直径、入口空泡份额分布等进行了敏感性及不确定性分析。此后采用该两相模型设置，针对带7道格架的AFA3G燃料组件进行了两相性能研究，计算结果显示格架间的各项参数不存在完全一致的周期性，但同种格架上游的空泡份额分布具有一定的相似性，因此用于两相性能评价可计算带2~3道格架的棒束，该研究可用于带格架棒束两相计算的模型设置与几何规模选择，为下一步采用两相CFD计算建立燃料组件热工水力性能评价准则奠定了基础。最后比较了AFA3G燃料组件及改进型燃料组件两种格架的空泡分布特性，并从提高燃料组件临界热流密度（CHF）特性的角度对其进行评价，获得与实验一致的结论，证明了评价方法的正确性。      

棒束及格架布置对燃料组件搅混特性影响的实验研究

以CPR1000核电机组使用的格架组装的5×5棒束燃料组件为对象,开展了多组全长棒束燃料组件搅混特性实验,重点分析了冷-热棒布置形式、格架布置形式等几何参数对燃料组件搅混特性的影响规律,实验结果表明,冷-热棒中心对称布置时的燃料组件热扩散系数更接近真值;跨间搅混格架对燃料组件总体热扩散系数有较小增强作用,但对于棒束压降的贡献很低。      

PWR 燃料组件锆合金定位格架设计和工艺中几个问题的探讨

PWR 燃料组件定位格架用材从镍基合金转变为锆-锡合金颇有经济意义。本文阐明了锆合金定位格架的分类及优点,并论述了锆合金定位格架的结构设计特点、冲压成型和焊接时应注意的问题。最后明确指出锆台金定位格架已是新型 PWR 燃料组件的重要特征之一。     

300MW燃料组件定位格架导向翼三维流场分析

从三维流场分析角度验证了300MW燃料组件定位格架导向翼初步设计改进方案的合理性,采用流体计算软件对燃料组件定位格架或棒束定位格架进行计算,比较导向翼修改前后的定位格架水力特性和导向翼周围流场的变化,为实际工程应用提供了依据。     

低流量工况下燃料组件优化设计研究

为了探索适用于模块式小堆（SMR）的燃料组件优化设计,本文针对截短型CF2燃料组件在SMR参数范围下的热工-水力性能开展分析研究,获得搅混格架的间距及布置形式对于燃料组件热工-水力性能的影响规律。研究结果表明:①低流量工况下,搅混格架间距过长或过短都将降低燃料组件的热工性能,设计上应合理考虑搅混格架间距;② 燃料组件加热段上游区域的搅混格架布置对于提升SMR燃料组件的热工性能不明显,设计上在此区域应简化布置;③ SMR在正常运行与事故工况下,燃料组件的中下游区域的状态点参数相对恶劣,在中下游区域合理地设计搅混格架的间距与布置可以显著地提升燃料组件的热工性能,提高热工安全裕量。本文研究结果可为SMR燃料组件的设计优化提供参考。      

压水堆燃料组件横向非线性特征模拟研究

压水堆燃料组件的燃料棒依靠格架进行夹持,保持燃料棒的横向和轴向定位。在燃料组件弯曲时,燃料棒与格架产生相对滑移,是燃料组件产生横向非线性特征的主要原因。本文分析典型的压水堆燃料组件格架和燃料棒夹持系统的设计特点,结合分析和试验结果,将夹持系统的滑移和弯曲特性分解为滑移单元和旋转弹簧单元的效应,从而实现夹持系统的力学模拟。通过计算与试验结果比较,验证所建立的夹持系统模型的有效性。将夹持系统模型用于燃料组件横向非线性模型中,通过模型计算与燃料组件横向拉伸试验结果对比,符合性良好。     

AP1000型燃料组件水平放置对格架弹簧影响分析

核电厂建设的工期延误和组件制造厂的燃料组件存贮场地不足,不能按期交付的首炉燃料组件被迫存放在组件运输容器内水平放置,有的燃料组件在运输容器内水平放置时间约1年以上.针对燃料组件在运输容器内长期水平放置是否对组件格架弹簧的力学特性有影响,以AP1000型燃料组件为例,对格架弹簧进行了力学特性影响分析.分析认为,燃料组件在...     

德国推出压水堆新燃料组件

【德国《原子经济》1991年第4期第160页报道】西门子公司能源部(即 KWU)将压水堆的新一代燃料组件,即 FOCUS 燃料组件投放市场。这种型号的燃料组件的定位格架使用锆合金。新的定位格架能更有效地利用堆芯中子、提高负荷转换灵活性和进一步     

AFA3G定位格架条带技术研究

介绍了目前国外燃料组件高燃耗、长周期、低泄漏的发展方向;阐述了研制高燃耗燃料组件定位格架的必要性和可行性。提出了定位格架研究中的主要技术指标、研究方案和实施途径。明确了定位格架条带的研制内容和模具制造中的技术难点;给出了总体实施方案,并确定了研究目标及技术性能指标。最后对格架研制中的关键技术和实施方案及格架研制中的相关配套条件进行了分析。     

VVER-1000应用PC级燃料的燃料管理

核电厂应用后处理制造的燃料组件,便可完成核燃料的"闭式循环",可以增加燃料的利用率和缓解乏燃料的储存难题。PC级燃料是利用后处理产品铀进行浓缩及加工所获得的一种核燃料,俄罗斯的VVER-1000机组中使用PC级燃料已有20年的历史。田湾核电厂1号机组已确定从第10燃料循环开始使用PC级燃料。使用KASKAD程序包,对VVER-1000使用PC级浓缩铀制造的TVS-2M组件展开研究设计,分析其应用的可行性,给出优化的燃料管理方案。     

核燃料

在法国核然料工业组织中,法杰马公司主要销售燃料组件。法比燃料公司(FBFC)的3个从属工厂都负责燃料组件的制造,该公司每年生产装铀量为1500t 的燃料组件。自1985年以来,法杰马公司又销售先进燃料组件(AFA)。该 AFA 的主要特点是使用了锆合金定位格架和可拆式上、下管嘴。大亚湾核电站要用的燃料组件正是该种与一般组件不同的先进燃料组件。法杰马公司采用钆作可燃毒物,以保证燃料组件的良好特性。近来该公司又推出混合氧化物燃料组件(MOX)。由于法杰马公司在设计和制造的各阶段都严格遵守了质量保证和质量控制制度,所以其产品质量优良、可靠性好。展望未来,法杰马公司将与法国核燃料工业中的其它集团一起,努力为用户提供尽可能好的产品。     

Fuel R & D to Improve Fuel Reliability

Light water reactor fuel is operating in an increasingly challenging environment. Fuel burnup extension and cycle length increase both can increase the local duty. Reactor water chemistry modifications for the purpose of protection the plant system materials have the potential of increasing fuel surface deposition and cladding corrosion and hydriding. The status of fuel performance in US reactors is summarized and an update of the “Fuel Reliability Program” established by the utility industry to ensure reliability is provided.     

Reactivity Effect of Non-Uniformly Distributed Fuel in Fuel Solution Systems

A numerical method to determine the optimal fuel distribution for minimum critical mass, or maximum k-effective, is developed using the Maximum Principle in order to evaluate the maximum effect of non-uniformly distributed fuel on reactivity. This algorithm maximizes the Hamiltonian directly by an iterative method under a certain constraint—the maintenance of criticality or total fuel mass. It ultimately reaches the same optimal state of a flattened fuel importance distribution as another algorithm by Dam based on perturbation theory.

This method was applied to two kinds of spherical cores with water reflector in the simulating reprocessing facility. In the slightly-enriched uranyl nitrate solution core, the minimum critical mass decreased by less than 1% at the optimal moderation state. In the plutonium nitrate solution core, the k-effective increment amounted up to 4.3Δk within the range of present study.     

Characterization of High Burnup Fuel for Safety Related Fuel Testing

Fuel Assemblies designed and fabricated by Westinghouse Electric Sweden (WSE) to reach high burnup have been operated in the Leibstadt nuclear power plant (KKL) for seven cycles attaining an assembly average burnup above 60 MWd/kgU. The irradiation conditions in KKL featured linear heat generation rates ranging from 250 W/cm early in life down to 100W/cm in the last cycle and normal water chemistry with zinc injection. Selected rods have been extracted at both intermediate and final irradiation stages and hot cell examinations have been carried out. The results show that the fuel is well suited for high burnup applications and rod segments have been provided to the OECD Halden Reactor Program, the OECD Studsvik Cladding Integrity Program and the Japanese ALPS program for dedicated high burnup tests with regard to fission as release and cladding lift-off as well as behavior under power transient, RIA and LOCA.     

Fuel transient deformation

Cladding strains resulting from fuel-cladding mechanical interaction in a transient tested fresh fuel pin are assessed against laboratory measurements of high-temperature creep and hot pressing of mixed-oxide fuel pellets.A fuel pin containing nine different fuel sections with varying fuel pellet geometry and density was transiently tested in a MARK IIIA flowing sodium loop under conditions typical of a 1$/s overpower transient. Post-test cladding strain measurements indicated that the largest strains were generated by solid pellets with small gaps while large gap annular pellets generated the smallest strains.High-temperature creep and hot pressing tests on mixed-oxide fuel have been performed at temperatures up to 2600°C. The results indicate that at temperatures above 2300°C, an additional component of creep is operative; while the densification due to hot pressing was considerably less than expected by extrapolating the low-temperature behavior.Both the in- and out-of-reactor data suggest that fuel creep into the center void or hole of a fuel pin is a more effective means of reducing fuel-cladding stress than densification by hot pressing into fuel pellet porosity.     

Fuel Temperature Coefficients of Reactivity for Heavy-Water-Moderated,Cluster-Type Fuel Lattices

Temperature coefficients of reactivity have been measured up to 600°C on cluster-type UO₂ fuel for three kinds of ²³⁵U enrichment and on a hollow cluster of sus-cladding tubes by using a hot He gas loop in a heavy-water-moderated, pressure-tube-type critical assembly. A new experimental method has been developed which accurately eliminates the reactivity disturbance caused by heat leakage in the measurement of an extremely small change in reactivity. The fuel (fuel pellet, cladding land pressure-tube) temperature coefficients of reactivity obtained for the temperature range below 300°C are +1.00±0.04, ?3.48±0.13 and - 6.36±0.25 in the unit of l0^-5% Δk/k.°C for 0.2%, 0.7% and 1.5%²³⁵U enrichment, respectively. In the higher temperature region above 300°C, each coefficient shifts to positive side by about 2x10^-5 Δk/k.°C. Temperature coefficient of reactivity for the hollow cluster of sus-cladding tubes (cladding and pressure-tube) has a large constant value with positive sign, + (6.42±0.26) x 10^-5 Δk/k.°C, all through the temperature range. A calculational model to analyze a hot-loop-type measurement of temperature coefficients with use of WIMS-D code was proposed and could be successfully applied to the present measurement.     

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。