Research on Ray Effect Method Based on Global Factor Correction for First Collision Source
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摘要: 计算孤立源、大空腔中子输运问题时,离散纵标方法(SN)存在射线效应,计算结果失真,常用首次碰撞源方法进行缓解以提高结果可靠性。但在首次碰撞源方法中,需要求解未碰撞中子注量率,通常采用基于网格中心法或网格角点平均值法的射线追踪技术,破坏了未碰撞中子数守恒原则。本文提出采用全局因子修正法对未碰撞中子注量率进行修正,使其满足中子数守恒原则;经过Kobayashi屏蔽计算基准题的检验,计算结果最大误差从6.15%降到3.71%,表明该方法能有效提高计算精度,可为屏蔽优化设计提供数据支持。
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关键词:
- 全局因子 /
- 离散纵标方法(SN) /
- 首次碰撞源 /
- 射线效应
Abstract: In the calculation of neutron transport problems with spatially localized source or largely void region, the discrete ordinate method (SN) suffers from ray effects, which cause computational inaccuracies. The first collision source method is often used to alleviate the ray effect to improve the reliability of results. However, this method requires the calculation of the uncollided neutron flux. Generally, which is typically achieved through ray tracing technology based on the grid center method or the grid corner average method, destroying the conservation principle of the number of uncollided neutrons. In this paper, a global factor correction method is proposed to correct the uncollided neutron flux to meet the principle of neutron number conservation. Through the test of Kobayashi shielding calculation benchmark problem, the calculation results show that the maximum error is reduced from 6.15% to 3.71%, indicating that the method can effectively improve the accuracy of calculation results and provide data support for shielding optimization design.-
Key words:
- Global factor /
- Discrete ordinate method (SN) /
- First collision source /
- Ray effect
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表 1 截面参数
Table 1. Section Parameters
区域 源强 /(cm−3·s−1) 宏观总截面/cm−1 宏观散射截面/ cm−1 源区 1 0.1 0.05 真空区 0 0.0001 0.00005 屏蔽区 0 0.1 0.05 表 2 不同离散角度下的 JSNT-S 直接计算结果
Table 2. Calculation Results of JSNT-S at Different Discrete Angle
位置坐标/cm 中子注量率/(cm−2·s−1) 误差/% 参考解 S8 S12 S16 S8 S12 S16 (5, 5, 5) 8.293×100 8.389×100 8.309×100 8.292×100 1.16 0.19 0 (15,15,15) 6.632×10−1 6.614×10−1 6.121×10−1 6.081×10−1 −0.27 −7.7 −8.32 (25,25,25) 2.688×10−1 2.087×10−1 3.169×10−1 2.905×10−1 −22.36 17.88 8.06 (35,35,35) 1.567×10−1 2.052×10−1 2.144×10−1 1.337×10−1 30.94 36.85 −14.66 (45,45,45) 1.044×10−1 2.008×10−1 1.373×10−1 9.749×10−2 92.29 31.5 −6.63 (55,55,55) 3.021×10−2 8.466×10−2 2.500×10−2 3.101×10−2 180.23 −17.24 2.64 (65,65,65) 4.066×10−3 1.515×10−2 2.534×10−3 4.686×10−3 272.65 −37.68 15.26 (75,75,75) 5.861×10−4 2.718×10−3 3.345×10−4 6.726×10−4 363.77 −42.94 14.75 (85,85,85) 8.661×10−5 4.753×10−4 4.935×10−5 9.518×10−5 448.76 −43.03 9.9 (95,95,95) 1.129×10−5 8.038×10−5 5.795×10−6 1.204×10−5 611.99 −48.68 6.66 表 3 JSWT-S与FCS、FCS-C中子注量率计算结果与误差
Table 3. Calculation Results and Errors of Neutron Flux Rates for JSNT-S, FCS and FCS-C
位置坐标/cm 中子注量率/(cm−2·s−1) 误差/% 参考解 JSNT-S FCS FCS-C JSNT-S FCS FCS-C (5, 5, 5) 8.293×100 8.292×100 8.132×100 8.274×100 0 −1.94 0.23 (15,15,15) 6.632×10−1 6.081×10−1 6.429×10−1 6.549×10−1 −8.32 −3.06 1.25 (25,25,25) 2.688×10−1 2.905×10−1 2.690×10−1 2.745×10−1 8.06 0.08 −2.13 (35,35,35) 1.567×10−1 1.337×10−1 1.470×10−1 1.509×10−1 −14.66 −6.15 3.71 (45,45,45) 1.044×10−1 9.749×10−2 1.016×10−1 1.042×10−1 −6.63 −2.7 0.14 (55,55,55) 3.021×10−2 3.101×10−2 2.877×10−2 2.949×10−2 2.64 −4.77 2.38 (65,65,65) 4.066×10−3 4.686×10−3 4.077×10−3 4.159×10−3 15.26 0.29 −2.3 (75,75,75) 5.861×10−4 6.726×10−4 5.872×10−4 5.985×10−4 14.75 0.18 −2.12 (85,85,85) 8.661×10−5 9.518×10−5 8.582×10−5 8.747×10−5 9.9 −0.91 −0.99 (95,95,95) 1.129×10−5 1.204×10−5 1.116×10−5 1.137×10−5 6.66 −1.18 −0.71 -
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