田湾核电站1号机组第6循环堆芯装载策略及验证

田湾核电站1号机组第5次换料大修期间,根据燃料组件检查结果,开展了紧急换料设计。1号机组第6循环堆芯装载策略具有不同于正常换料的特点,例如燃料装载不对称、部分辐照过的燃料组件移动到对称象限、堆芯功率分布不对称等。另外,堆芯装载策略考虑了TVS-2M先导燃料组件的位置要求。经第6循环寿期初物理试验和堆内测量系统验证,堆芯装载方案设计结果满足各项测量准则要求,且堆芯运行参数符合设计预期。     

高通量工程试验堆三维物理热工程序系统的验证

介绍了高通量工程试验堆 (HFETR)堆芯三维稳态物理热工计算程序系统的验证结果。该程序系统由 6个部分组成 :基于WIMS D4的栅元均匀化少群参数计算程序、基于SIXTUS 3的三维堆芯燃料管理程序S3BURN、节块精细注量率重组程序HFETRPPC、堆芯流量分配计算程序HFETRFD、燃料元件流场和温场三维数值计算程序CASH以及基于COBRA 1V的燃料考验组件热工水力分析程序。通过程序计算值与实测值广泛范围的比较 ,对程序系统进行了验证。从结果可以看出 ,该程序系统功能强、性能好、计算速度快 ,可以完成HFETR及配套设施的堆芯运行方案设计计算。     

六边形套管型燃料堆芯临界物理试验方案设计研究

为验证六边形套管型燃料堆芯核设计计算程序CELL和CPLEV2的计算精度和可靠性,本文根据六边形套管型燃料堆芯临界物理试验内容,提出了11个堆芯临界物理试验方案,并进行了计算论证分析。其中,临界质量测量方案考虑了计算与实际有偏差时,可以对堆芯布置进行微调,确保全提棒有效增殖因子与临界状态的偏差在可接受范围内。论证结果表明,本文提出的堆芯装载方案满足堆芯核设计程序可靠性检验要求,可以作为六边形套管型燃料堆芯临界物理试验方案。      

TVS-2M燃料棒制造参数对堆内性能影响的不确定性研究

田湾核电站3、4号机组计划从首炉堆芯开始使用TVS-2M燃料。为了对前8个燃料循环中燃料棒稳态性能进行验证,根据保守性燃料制造参数进行选择,利用START-3程序开展了5个设计准则上的燃料棒性能校验工作。但是,上述传统方法的保守性并未得到验证,而且也无法开展燃料制造参数的敏感性研究。为此,将DAKOTA与START-3程序耦合,利用统计类的GRS方法,对田湾核电站3、4号机组中的TVS-2M燃料棒稳态性能的不确定性开展计算分析。结果表明:传统方法在燃料温度与包壳应力方面过于保守,而在包壳的轴向和径向应变方面则保守性不足;在燃料制造参数的敏感性方面,包壳内径和芯块外径的敏感度价值普遍较高;此外,燃料密度对燃料温度和燃料棒内压有较大影响。     

田湾核电站线功率密度保护参数计算

田湾核电站(TNPS)堆内核测量系统的54个中子温度测量通道分成4组,每组通道将自给能探测器电流转换为功率并通过扩展计算获得全堆芯的功率分布。电流转换为功率的系数等参数由堆内测量系统上层服务器计算获得并传递给下层服务器。每个燃料组件最大线功率密度由周边影响区域内的4个中子温度测量通道计算的线功率密度值加权平均得到,权重系数与自给能探测器到周边影响区域内燃料组件的距离有关。本文阐述这种由自给能探测器电流计算线功率密度保护参数的方法。该方法简易、响应及时,且误差小于5.7%,已成功应用在田湾核电站运行机组的实时在线保护中。     

国内特别报道

<正>田湾核电站首次采用堆芯倒料获得成功2010年6月4日12时47分,随着田湾核电站2号机组最后一组新燃料组件被平稳地从乏燃料水池送往反应堆堆芯存放,田湾核电站首次采用堆芯倒料模式实施装换料操作宣告成功。(摘编自江苏核电有限公司网2010年6月9日报道)     

ERANOS程序用于CEFR堆芯物理特性的验证计算

ERANOS系统(欧洲反应堆分析优化系统)是欧洲和日本联合开发的快中子反应堆堆芯物理屏蔽计算软件系统,采用模块化设计,包含核截面库制作、中子学计算和燃耗计算等模块。该系统可进行反应堆中子学一维至三维的扩散、输运计算,可进行堆芯中子动态特性、燃料管理以及灵敏度分析等计算。本工作主要是进一步学习使用ERANOS程序系统,并针对CEFR堆芯物理特性进行了对比计算。主要计算内容包括:针对CEFR不同组件进行栅元计算,得到各种材料的少群截面数据;堆芯稳态物理特性参数和燃耗计算。对于CEFR堆芯物理参数,通过对比计算表明采用不同程…     

田湾核电站TVS-2M先导组件堆芯热工水力分析

田湾核电站一号机组于第5燃料循环装入6组TVS-2M先导燃料组件,并将经历从第5燃料循环到第8燃料循环4年的堆内运行。本文通过对先导燃料组件堆芯热工水力分析,堆芯运行实际试验测量以及组件变形检查,验证了热工水力设计程序计算模型的合理性以及计算结果与试验结果的符合性。结果表明,TVS-2M燃料组件与AFA燃料组件具有良好的相容性,从而证实了过渡循环条件下反应堆运行的安全性和可靠性。     

田湾核电站1~4号机组堆芯燃料管理优化研究

采用KASKAD程序包对田湾核电站1~4号机组进行堆芯燃料管理优化研究,优化的燃料管理方案通过提高新组件的平均富集度减少了换料组件的类型和数量,并提高了平衡循环的循环长度。从燃料管理计算结果可以看出,堆芯各项安全参数均满足限值要求,同时具有很好的运行灵活性,提高了燃料利用率,提升了核电厂的经济效益,具有非常好的工程应用价值。      

SRAC程序在中国先进研究堆上的应用研究

SRAC程序是由日本原子能研究机构发布的在Linux系统下运行的堆芯物理计算程序包,包括栅元计算程序、堆芯计算程序和燃耗计算程序.本程序采用基于JENDL或ENDF/B系列的数据库,可处理300多种核素的截面参数.该程序具有计算速度快、堆芯燃料管理方便等优点.本文对SRAC程序在中国先进研究堆(CARR)上的应用进行了初步研究,利用SRAC程序对CARR进行了临界计算和首炉燃耗计算.通过与WIMS-CITATION程序系统计算结果的比较,初步确定了SRAC程序是CARR在线计算工具很好的选择,并为今后的实际应用奠定了良好的技术基础.     

Analyses of the V1000CT-1 benchmark with the DYN3D/ATHLET and DYN3D/RELAP coupled code systems including a coolant mixing model validated against CFD calculations

Plant-measured data provided within the specification of the OECD/NEA VVER-1000 coolant transient benchmark (V1000CT) were used to validate the DYN3D/RELAP5 and DYN3D/ATHLET coupled code systems. Phase 1 of the benchmark (V1000CT-1) refers to the MCP (main coolant pump) switching on experiment conducted in the frame of the plant-commissioning activities at the Kozloduy NPP Unit 6 in Bulgaria. The experiment was started at the beginning of cycle (BOC) with average core expose of 30.7 effective full power days (EFPD), when the reactor power was at 27.5% of the nominal level and three out of four MCPs were operating. The transient is characterized by a rapid increase in the primary coolant flow through the core and, as a consequence, a decrease of the space-dependent core inlet temperature. Both DYN3D/RELAP5 and DYN3D/ATHLET analyses were based on the same reactor model, including identical MCP characteristics, boundary conditions, benchmark-specified nuclear data library and nearly identical nodalization schemes. For an adequate modelling of the redistribution of the coolant flow in the reactor pressure vessel during the transient a simplified mixing model for the DYN3D/ATHLET code was developed and validated against a computational fluid dynamics calculation.

The results of both coupled code calculations are in good agreement with the available experimental data. The discrepancies between experimental data and the results of both coupled code calculations do not exceed the accuracy of the measurement data. This concerns the initial steady-state data as well as the time histories during the transient. In addition to the validation of the coupled code systems against measured data, a code-to-code comparison between simulation results has been performed to evaluate relevant thermal hydraulic models of the system codes RELAP5 and ATHLET and to explain differences between the calculation results.     

RELAP5/MOD3.2 investigation of a VVER-1000 MCP switching on Benchmark problem

This paper provides comparisons between experimental data of Kozloduy NPP “MCP switching on when the other three MCP are in operation”, with Relap5 calculations. The investigated thermal-hydraulic driven transient is characterized by spatially dependant non-symmetric processes. RELAP5/MOD3.2 computer code has been used to simulate the investigated transient. Operational data from Kozloduy NPP have been used for the purpose of assessing how the RELAP5 model compares against plant data. During the plant-commissioning phase at Kozloduy NPP Unit 6 a number of experiments have been performed. One of them is switching on MCP when the other three MCPs are in operation. The event is characterized by rapid increase in the flow through the core resulting in a coolant temperature decrease, which leads to insertion of positive reactivity due to the modeled feedback mechanisms. The main purpose of this investigation was to improve the discrepancy between the calculations and the plant data. The sensitivity calculation investigates the mixing in reactor vessel and influence of heat structure on the hot legs temperature. The areas of improvements to the Relap5 model are:

• •The non-symmetrical mixing in downcomer and reactor vessel annular exit.
• •The influence of heat structure temperature on the time delay for equipments measurements.
• •Investigation of pressurizer water level – using the hot legs temperature correction.

The RELAP5/MOD3.2 model of Kozloduy NPP VVER-1000 for investigation of operational occurrences, abnormal events, and design basis scenarios have been developed and validated in the Institute for Nuclear Research and Nuclear Energy – Bulgarian Academy of Sciences (INRNE-BAS) Sofia, and Kozloduy NPP. The model provides a significant analytical capability for the specialists working in the field of NPP safety.This investigation is a process that compares the analytical results obtained by the RELAP5 computer model of the VVER-1000 against the experimental transient data received from the Kozloduy NPP Unit 6. The comparisons indicate good agreement between the RELAP5 results and the experimental data. The sensitivity investigation improves the discrepancy between the calculation and the plant data.This investigation was possible through the participation of leading specialists from Kozloduy NPP and with the support of Argonne National Laboratory, under the International Nuclear Safety Program (INSP) of the United States Department of Energy.     

Validation of coupled neutronic/thermal-hydraulic code RELAP5-3D for RBMK-1500 reactor analysis application

This paper summarizes RELAP5-3D code validation activities carried out at the Lithuanian Energy Institute, which was performed through the modeling of RBMK-1500 specific transients taking place at Ignalina NPP. A best estimate RELAP5-3D model of the INPP RBMK-1500 reactor has been developed and validated against real plant data, as well as with the calculation results obtained using the Russian STEPAN/KOBRA code. The obtained calculation results demonstrate reasonable agreement with Ignalina NPP measured data. Behaviors of the separate MCC thermal-hydraulic parameters, as well as physical processes are predicted reasonably well to the real processes, occurring in the primary circuit of RBMK-1500 reactor. The calculated reactivity and the total reactor core power behavior in time are also in reasonable agreement with the measured plant data, which demonstrates the correct modeling of the neutronic processes taking place in RBMK-1500 reactor core. The performed validation of RELAP5-3D model of Ignalina NPP RBMK-1500 reactor allowed to improve the model, which in the future would be used for the safety substantiation calculations of RBMK-1500 reactors. Future activities are discussed.     

Comparison of RELAP5 calculations of VVER-1000 coolant transient benchmark phase 1 at different power

This paper provides comparisons between experimental data of “MCP switching on when the other three MCPs are in operation” and RELAP5 calculations with different initial levels of the reactor power 29.45% and 27.47% from the nominal.

The reference power plant for this analysis is Unit 6 at the Kozloduy nuclear power plant (NPP) site. RELAP5/MOD3.2 computer code has been used to simulate the investigated transient. Operational data from Kozloduy NPP have been used for the purpose of assessing how the RELAP5 model compares against plant data. During the plant-commissioning phase at Kozloduy NPP Unit 6 a number of experiments have been performed. One of them is switching on MCP when the other three MCPs are in operation.

This investigation was possible through the participation of leading specialists from Kozloduy NPP and with the support of Argonne National Laboratory, under the International Nuclear Safety Program (INSP) of the United States Department of Energy.     

田湾核电站安全仪控系统(TXS系统)失效概率估算

介绍了田湾核电厂安全仪控系统(TXS系统)失效概率的估算方法,推导了用于反应堆停堆系统和ESFAS系统失效概率估算的一般性公式。并以主给水/主蒸汽系统故障停堆和触发应急给水系统启动两个仪控功能为例进行计算,结果证明田核电站TXS系统失效概率满足可靠性要求。     

田湾核电站数字化反应堆保护系统可靠性分析

分析了田湾核电站数字化反应堆保护系统的结构和基本功能,以故障树分析方法为基础,确定了数字化反应堆保护系统故障树的顶事件,建立了以反应堆停堆子系统失效为顶事件的故障树,利用RISK-SPECTRUM程序,对所建的故障树进行了定量分析和计算,得到了系统故障树的失效概率和最小割集,为田湾核电站运行和维修提供了有益的指导.     

Revised calculation route for two group macroscopic cross-section library for RBMK-1500 type reactor

To increase the accuracy of predicted reactivity effects and coefficients for the unit equipped with a RBMK-1500 type reactor at Ignalina NPP, the calculation route used to generate the library of nuclear data constants applied in the neutronic/thermal hydraulic analysis has been updated with a modern version of the WIMS lattice code, WIMS8. The previously available two group library used with the QUABOX/CUBBOX-HYCA code, adapted to model the physical and nuclear processes in a RBMK-1500 reactor core, was created using the freely available WIMSD reactor physics cell code and its associated nuclear data library. In this article, the results that are obtained under the performance of the new two group cross-section library generated with WIMS8 for RBMK-1500 design core are presented. This discussion is mostly concentrated on the prediction of the key physics parameter for the RBMK type reactor, the void reactivity coefficient, as this parameter has been underestimated, especially at higher fuel irradiation.     

Static analytical and experimental research of shock absorber to safeguard the nuclear fuel assemblies

The Ignalina Nuclear Power Plant (NPP) has two RBMK-1500 graphite-moderated boiling water multi-channel reactors. The Ignalina NPP Unit 1 was shutdown at the end of 2004, while Unit 2 is foreseen to be shutdown at the end of 2009. At the Ignalina NPP Unit 1 remains approximately 1000 spent fuel assemblies with low burn-up depth. A special set of equipment was developed to reuse these assemblies in the reactor of Unit 2. One of most important items of this set is a container, which is used for the transportation of spent fuel assemblies between the reactors of Unit 1 and Unit 2. A special shock absorber was designed to avoid failure of fuel assemblies in case of hypothetical spent fuel assemblies drop accident during uploading/unloading of spent fuel assemblies to/from container. This shock absorber was examined by using scaled experiments.The objective of this article is the estimation whether the proposed design of shock absorber fulfils the function of the absorber and the optimization of its geometrical parameters using the results of the performed investigations. Static analytical and experimental investigations are presented in the article. The finite element code BRIGADE/Plus was used for the analytical analysis. The calculation model was verified by comparing the experimental investigation and simulation results for further employment of this finite element model in the development of an optimum design of shock absorber. Static simulation was used to perform primary optimization of design and dimension of the shock absorber.     

田湾核电站14C和3H年产生量估算

介绍了压水堆核电站堆芯燃料和冷却剂中14^C和3^H产生量的计算方法,计算了田湾核电站每年在堆芯燃料和冷却剂中产生的14^C和3^H的总活度,将该计算结果与俄罗斯在田湾核电站最终安全分析报告中给出的数据进行了比较分析,并从减少这两种核素产生量的角度提出了一些设计建议。     

Analysis of the VVER1000 coolant trip benchmark using the coupled RELAP5/PARCS code

Incorporation of full three-dimensional models of the reactor core into system thermal–hydraulic transient codes allows better estimation of interactions between the core behavior and plant dynamics. Considerable efforts have been made in various countries and organizations to verify and validate the capability of the so-called coupled codes technique. For these purposes appropriate Light Water Reactor (LWR) transient benchmarks based upon programmed transients performed in Nuclear Power Plants (NPP) were recently developed on a higher ‘best-estimate’ level. The reference problem considered in the current framework is a Main Coolant Pump (MCP) switching-on transient in a VVER1000 NPP. This event is characterized by a positive reactivity addition as consequence of the increase of the core flow. In the current study the coupled RELAP5/PARCS code is used to reproduce the considered test. Results of calculation were assessed against experimental data and also through the code-to-code comparison.