共查询到18条相似文献,搜索用时 125 毫秒
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基于贝叶斯推断理论,实现了一种有效融合堆内中子探测器实际测量值与中子学理论计算值两类信息的堆芯功率分布重构方法。应用大亚湾核电站1号机组的测量数据对贝叶斯推断方法的功率分布重构精度进行了验证,并将贝叶斯推断方法与卡尔曼滤波方法以及耦合系数法进行了精度对比。验证结果显示,贝叶斯推断方法在整个循环寿期内的均方根误差、最大相对误差、功率峰重构误差分别不大于0.31%、1.64%和0.07%,且重构精度优于卡尔曼滤波方法以及耦合系数法。重构精度以及计算速度表明贝叶斯推断方法有潜力被应用于功率分布在线监测系统。 相似文献
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在线准直监测是保障粒子加速器设备稳定性的重要手段,激光准直具有响应快,精度高等特点,是机器关键设备在线准直监测的重要数据参考来源。针对合肥先进光源的准直要求,提出了一种基于激光光斑相似性度量的高精度在线准直监测系统,通过对激光成像光斑位移进行测量来监测被测系统的横向位置偏移。本文介绍该系统激光光路控制、探测器组件的结构及工作原理,并对系统关键误差展开分析,在随机噪声的影响下,算法精度优于±0.17像素(pix)。然后,搭建了一套40 m长的样机系统,采用相似性度量算法,在不同时间获取不同监测位置被测目标的相对位置偏差,经测试,系统的横向监测精度优于8μm,且样机的监测精度与被测目标的距离无关。该样机系统的研制成功,为更远距离微位移监测系统的研制提供基础数据,可适用于第4代同步辐射光源、自由电子激光、直线型对撞机等加速器领域设备的在线位移监测。 相似文献
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二维/一维耦合输运方法较好地平衡了效率与精度,因此被广泛应用于一步法全堆芯输运计算。二维/一维耦合输运方法中,由于泄漏项在方程右端,导致二维特征线法(MOC)计算时方程右端总源项在迭代过程中可能成为负值,造成迭代发散。本文针对二维/一维耦合输运计算中的负源项问题,提出了一种改进的泄漏项分割方法。新的泄漏项分割方法可在不造成计算精度损失和仅增加有限内存的条件下,显著提高二维/一维耦合输运方法的稳定性。通过强泄漏算例、C5G7基准题、VERA-3A基准题等进行测试,表明该方法对提高二维/一维耦合输运方法稳定性具有显著的效果。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(10):985-987
Axially simplified method of characteristics in three-dimensional geometry (ASMOC3D) has been proposed, and the 3D neutron transport calculation code based on this method, SHIKOKU, has been developed. Since ASMOC3D handles 3D problems by a two-dimensional (2D) neutron track set and simplified treatment in axial direction, the required memory and the computational time are expected to be less than those required by a direct 3D characteristics calculation scheme. SHIKOKU is applied to two problems of 3D geometry and the results of these problems show good agreements with the reference solutions obtained by a Monte-Carlo code. SHIKOKU is also applied to an actual three-loop-type PWR core. The prediction error of the radial power distribution is satisfactory and it is shown that the computational time and the required memory for a whole-core calculation by ASMOC3D are not prohibitive for presently available PCs. 相似文献
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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. 相似文献
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Fixed in-core detectors are most suitable in real-time response to in-core power distributions in pressurized water reactors (PWRs). In this paper, a harmonics expansion method is used to reconstruct the in-core power distribution of a PWR on-line. In this method, the in-core power distribution is expanded by the harmonics of one reference case. The expansion coefficients are calculated using signals provided by fixed in-core detectors. To conserve computing time and improve reconstruction precision, a harmonics data library containing the harmonics of different reference cases is constructed. Upon reconstruction of the in-core power distribution on-line, the two closest reference cases are searched from the harmonics data library to produce expanded harmonics by interpolation. The Unit 1 reactor of DayaBay Nuclear Power Plant (DayaBay NPP) in China is considered for verification. The maximum relative error between the measurement and reconstruction results is less than 5.5%, and the computing time is about 0.53 s for a single reconstruction, indicating that this method is suitable for the on-line monitoring of PWRs. 相似文献
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最佳估算加不确定性(BEPU)分析是IAEA推荐用于核电厂事故安全分析的方法,该方法中一个关键步骤为评估输入参数对目标输出的影响大小,即定量敏感性分析。传统BEPU分析中常使用基于线性或单调假设的局部敏感性分析方法,其难以适用于复杂的核反应堆系统,而全局敏感性分析则由于计算成本过高而难以在实际工程中应用。本研究中针对矩独立全局敏感性分析方法开展了优化研究,使用高阶模型表示、高斯求积公式等方法降低矩独立敏感性度量的计算成本,得到了一种高效的敏感性分析方法。使用了多个例题对优化方法的可靠性进行了验证,并将其应用于LOFT(loss of fluid test)大破口事故的敏感性分析。结果表明,该高效敏感性分析方法能准确识别核反应堆事故工况中的重要参数,并能对参数重要度进行定量排序。 相似文献