Research on Multi-Group Constant with Discrete Angle and SPH Method Based on RMC
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摘要: 蒙特卡罗方法使用连续能量截面且具有灵活的几何处理能力。本文提出了一种散射角离散的蒙特卡罗群常数计算方法，并使用棒状燃料组件进行群常数计算与验证。本文首先基于堆用蒙卡程序（RMC）加工基于组件或栅元的角度离散多群常数库，然后利用群常数库进行全堆输运计算。在多群常数库加工环节，基于中子历史跟踪中子碰撞行为，可以准确表达中子的各向异性散射，并且基于全堆真实条件加工群常数库，理论上在输运过程没有近似。在等效均匀化方面，采用改进的超级均匀化 （SPH） 方法。研究表明，与传统的勒让德散射矩阵比较，本文提出的方法避免了负截面的产生；与连续能量蒙卡结果比较，组件计算结果小于70pcm（1pcm=10−5）。采用全堆真实条件加工群常数更加准确，几何描述灵活，普适性好。
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关键词:
- 蒙卡程序（RMC） /
- 群常数 /
- 角度离散 /
- 超级均匀化（SPH）
Abstract: In this paper, a Monte Carlo group constant calculation method with discrete scattering angle is proposed, and the group constants are calculated and verified by using rod-type fuel assembly. First, a multi-group constant library based on fuel assembly or pin is calculated using the Reactor Monte Carlo (RMC) code, and then the group constant library is used for the neutron transport calculation of the full core. In the generation process of multi-group constant library, the neutron collision behavior is tracked based on the neutron history, which can accurately express the anisotropic scattering of neutrons. Since the group constant library is generated under real full-core conditions, no approximations are theoretically introduced during the transport calculation. For equivalent homogenization, an improved Superhomogenization (SPH) method is adopted. The above research shows that compared with the traditional Legendre scattering matrix, the method proposed in this paper avoids the generation of negative cross section; Compared with the continuous energy Monte Carlo results, the assembly calculation error is less than 70pcm (pcm=10−5); It is more accurate to calculate the group constant under real full-core conditions, with flexible geometric adaptability and excellent universality. -
图 2 SERPENT勒让德散射矩阵与散射角离散的散射矩阵的对比
Figure 2. Comparison of the Legendre Scattering Matrix Using SERPENT and the Scattering Matrix with Discretized Scattering Angles
图 3 2×2组件群常数计算模型
Figure 3. Model for Group Constants of a 2×2 Fuel Assembly Configuration
图 4 2×2组件均匀化前后热群和快群通量
Figure 4. Comparison of Thermal and Fast Neutron Fluxes in a 2×2 Fuel Assembly Array before and after Homogenization
图 5 均匀化前后通量分布相对误差
Figure 5. Relative Error of Neutron Flux Distribution before and after Homogenization
表 1 组件均匀化前后keff对比
Table 1. Comparison of the keff before and after Homogenization of the Fuel Assembly
计算方式 keff 统计方差 相对误差/% 时间压缩比 RMC_CE 1.35923 0.00021 Homo 1.35859 0.00022 −0.047 7.22 keff—有效增殖因子；Homo—组件均匀化。 
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表 2 RMC与SERPENT 2群一般截面比较
Table 2. Comparative Analysis of General Cross-Sections Using RMC and SERPENT 2
群常数 能群数 RMC 标准
相对偏差
（RMC）SERPENT 标准
相对偏差
(SERPENT)相对
误差/%总截面 1 5.34×10−1 8.93×10−5 5.32×10−1 6.80×10−5 0.38 2 1.07 6.42×10−5 1.07 1.40×10−4 0 裂变
截面1 2.95×10−3 2.48×10−4 2.95×10−3 3.40×10−4 0 2 7.82×10−2 2.05×10−4 7.77×10−2 3.40×10−4 0.64 俘获
截面1 6.93×10−3 4.57×10−4 6.94×10−3 3.90×10−4 −0.14 2 3.24×10−2 1.61×10−4 3.22×10−2 2.60×10−4 0.62 中子
产额1 2.55 3.51×10−5 2.55 4.10×10−5 0 2 2.44 2.03×10-10 2.44 0 0
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表 3 均匀化前后keff对比
Table 3. Comparison of keff before and after Homogenization
计算方式 keff 相对误差/% 时间压缩比 参考解 1.23568±0.000055 组件均匀化 1.23548±0.000058 0.016 7.72 栅元均匀化 1.23580±0.000061 0.010 4.19
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[1] REDMOND II E L. Multigroup cross section generation via Monte Carlo methods[D]. Cambridge: Massachusetts Institute of Technology, 1997. [2] POUNDERS J M. Stochastically generated multigroup diffusion coefficients[D]. Atlanta: Georgia Institute of Technology, 2006. [3] LEPPÄNEN J. On the use of the continuous-energy Monte Carlo method for lattice physics applications[C]//2009 International Nuclear Atlantic Conference. Rio de Janeiro: INAC, 2009: 1-16. [4] SHIM H J, CHO J Y, SONG J S, et al. Generation of few group diffusion theory constants by Monte Carlo code[J]. Transactions of the American Nuclear Society, 2008, 99: 343-345. [5] LIU S C, SHE D, LIANG J G, et al. Development of random geometry capability in RMC code for stochastic media analysis[J]. Annals of Nuclear Energy, 2015, 85: 903-908. doi: 10.1016/j.anucene.2015.07.008 [6] 袁媛. 基于RMC的在线均匀化方法研究及应用[D]. 北京:清华大学,2020. [7] 冯致远. 基于RMC的等效均匀化群常数及截面参数化研究[D]. 北京: 清华大学,2022. [8] HÉBERT A, BENOIST P. A consistent technique for the global homogenization of a pressurized water reactor assembly[J]. Nuclear Science and Engineering, 1991, 109(4): 360-372. doi: 10.13182/NSE109-360 [9] LEPPÄNEN J, PUSA M, FRIDMAN E. Overview of methodology for spatial homogenization in the Serpent 2 Monte Carlo code[J]. Annals of Nuclear Energy, 2016, 96: 126-136. doi: 10.1016/j.anucene.2016.06.007 -
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