基于折射率匹配方法的球床三维重构
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摘要
固态钍基熔盐堆(Thorium-based Molten Salt Reactor with Solid Fuel,TMSR-SF)是第四代核反应堆堆型之一,它融合了高温气冷堆的石墨基质包覆颗粒燃料球技术和熔盐堆的高温熔盐冷却剂技术。堆芯的物理设计和几何设计依赖于燃料球在堆芯中的堆积因子,为研究球床堆堆芯模型内燃料球的堆积三维结构,本文提出基于折射率匹配的方法对球床进行三维重构的方案,并通过初步的模拟实验对程序进行验证,旨在探索该方法在球床三维重构中的可行性。针对三维重构中的一系列关键问题进行阐释,并提出相应的解决方案;同时给出了三维重构方案的完整流程,并计算出了衡量三维重构精确度的度量值:直径重叠量。最后,搭建了一个小型规则排布的球床实验装置,通过折射率匹配技术开展球床可视化实验以探索该方案在球床三维重构中的精确度,并说明该方法的可行性。试验结果表明,颗粒间平均重叠量为1.43 mm,重构精度有待提高,重构方法有待改进。
Background: Thorium-based molten salt reactor with solid fuel(TMSR-SF) is one type of the fourth nuclear power plant which combines high-temperature graphite-matrix coated-particle pebble fuel for hightemperature gas-cooled reactors and liquid salts developed for the molten salt reactors. The design of TMSR-SF requires detailed understanding of the packing structure of the pebble bed in reactor core. Purpose: This article is aimed to explore the effectiveness of refractive index matched scanning technique(RIMS) in the 3 D-reconstruction of reactor core. Methods: The cross sections of the pebble bed are imaged by a charge-coupled device(CCD), then the threshold transformation, filter transformation and Hough transformation are used to process the images, and the coordinates of points on the spheres' edge are extracted. Then an algorithm is used to acquire the relative center coordinates of each sphere. Results: The result shows that excluding irrelevant distractors can improve the accuracy of the 3 D-reconstruction, and creating region of interest(ROI) to make threshold transformation is a good method to enhance circles' edges, and when the circles in the images distort, minimum bounding rectangle(MBR) functions is more effective than Hough circle transformation. Conclusion: Our scheme of reconstruction can reconstruct the 3 D packing structure of the pebble bed with the mean distance-overlapped which is 1.43 mm, and this precision needs to be improved later.
Background: Thorium-based molten salt reactor with solid fuel(TMSR-SF) is one type of the fourth nuclear power plant which combines high-temperature graphite-matrix coated-particle pebble fuel for hightemperature gas-cooled reactors and liquid salts developed for the molten salt reactors. The design of TMSR-SF requires detailed understanding of the packing structure of the pebble bed in reactor core. Purpose: This article is aimed to explore the effectiveness of refractive index matched scanning technique(RIMS) in the 3 D-reconstruction of reactor core. Methods: The cross sections of the pebble bed are imaged by a charge-coupled device(CCD), then the threshold transformation, filter transformation and Hough transformation are used to process the images, and the coordinates of points on the spheres' edge are extracted. Then an algorithm is used to acquire the relative center coordinates of each sphere. Results: The result shows that excluding irrelevant distractors can improve the accuracy of the 3 D-reconstruction, and creating region of interest(ROI) to make threshold transformation is a good method to enhance circles' edges, and when the circles in the images distort, minimum bounding rectangle(MBR) functions is more effective than Hough circle transformation. Conclusion: Our scheme of reconstruction can reconstruct the 3 D packing structure of the pebble bed with the mean distance-overlapped which is 1.43 mm, and this precision needs to be improved later.
引文
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2 Benenati R,Brosilow C B.Void fraction distribution in beds of spheres[J].Aiche Journal,1962,8(3):359-361.DOI:10.1002/aic.690080319.
3 Mueller G.Radial porosity in packed beds of spheres[J].Powder Technology,2010,203(3):626-633.DOI:10.1016/j.powtec.2010.07.007.
4 Auwerda G J,Kloosterman J,Lathouwers D,et al.Macroscopic and microscopic packing properties of experimental and computational pebble beds[J].Nuclear Technology,2013,183(3):272-286.
5 Nguyen N L,Van Buren V,Von Garnier A,et al.Application of magnetic resonance imaging(MRI)for investigation of fluid dynamics in trickle bed reactors and of droplet separation kinetics in packed beds[J].Chemical Engineering Science,2005,60(22):6289-6297.DOI:10.1016/j.ces.2005.04.083.
6 Wiederseiner S,Andreini N,Epely-Chauvin G,et al.Refractive-index and density matching in concentrated particle suspensions:a review[J].Experiments in Fluids,2011,50(5):1183-1206.DOI:10.1007/s00348-010-0996-8.
7艾淑芳,闫钧华,李大雷,等.遥感图像中的机场跑道检测算法[J].电光与控制,2017,24(2):43-46.DOI:10.3969/j.issn.1671-637X.017.0.009.AI Shufang,YAN Junhua,LI Dalei,et al.An algorithm for detecting the airport runway in remote sensing image[J].Electronics Optics&Control,2017,24(2):43-46.DOI:10.3969/j.issn.1671-637X.017.0.009.
8雷浩鹏.数字图像去噪算法研究及应用[D].长沙:长沙理工大学,2010.DOI:10.7666/d.Y1699449.LEI Haopeng.The research and application of digital image de-noising algorithm[D].Changsha:Changsha University of Science&Technology,2010.DOI:10.7666/d.Y1699449.
9于仕琪,刘瑞祯.学习Open CV[M].北京:清华大学出版社,2009.YU Shiqi,LIU Ruizhen.Learning Open CV[M].Beijing:Tstinghua University Press,2009.
10杨治明,周齐国.基于霍夫变换理论的图形识别[J].重庆工业高等专科学校学报,2002,17(4):16-17.DOI:10.3969/j.issn.1673-1999.2002.04.005.YANG Zhiming,ZHOU Qiguo.The recognition of the geometric figure based on the Hough transformation theory[J].Journal of Chongqing Polytechnic College,2002,17(4):16-17.DOI:10.3969/j.issn.1673-1999.2002.04.005.