Study on the Coupled Calculation Method of Discrete-Ordinates and Point Kernel Integration
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摘要: 针对现存的大部分点核积分程序在屏蔽计算中存在的明显缺陷，即在面对较大源和多层屏蔽组合的计算过程中会产生数量级级别的误差。本研究在点核积分计算中引入离散纵标方法，并研究TORT与QADS两个程序的特点，编写了接口程序，实现两者的耦合计算，解决了传统点核积分程序中源离散计算精度差、缺乏斜角分解技术等问题，并设计简单的几何模型针对该方法进行可行性研究。结果显示，在计算深穿透问题时，离散纵标-点核积分耦合方法极大提高了计算精度，能够在辐射屏蔽计算实践中提供相对于所涉及方法更优的结果。Abstract: To address the obvious shortcomings of most existing point kernel integration codes in shielding calculations, i.e., they produce errors of order of magnitude in the calculation process of large source and multi-layer shielding combinations. In this study, discrete-ordinates method is introduced in the point kernel integration calculation, and the characteristics of the two codes TORT and QADS are investigated. An interface code is written to realize the coupling of the two codes. The problems of poor accuracy of source discretization and lack of oblique angle decomposition technology in traditional point kernel integration codes are solved, and a simple geometric model is designed to study the feasibility of this method. The results show that the coupled discrete-ordinates and point kernel integral method greatly improves the computational accuracy in the calculation of deep penetration problems and can provide better results in the practice of radiation shielding calculation compared with the involved methods.
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Key words:
- TORT /
- QADS /
- Discrete-ordinates /
- Point kernel integration
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图 4 离散点数量对探测点位置剂量率的影响
Figure 4. Influence of Number of Discrete Points on Photon Flux Density
图 5 低能群下各探测点剂量率
蒙卡—蒙特卡洛
Figure 5. Dose Rate of Each Detection Point under Low Energy Group
表 1 SN-点核积分耦合方法在不同耦合面上的光子剂量率与误差结果
Table 1. Dose Rate Calculation Results and Error of SN -Point Kernel Integral Coupling Method on Different Coupling Surfaces
SN计算/（10−4 mSv·h−1） 点核积分计算/（10−4 mSv·h−1） 耦合计算（面1）/（10−4 mSv·h−1） 误差1/% 耦合计算（面2）/（10−4 mSv·h−1） 误差2/% 3.99 7.59 4.01 0.50 3.76 5.76 
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表 2 低能γ射线源下辐射场剂量率
Table 2. Low Energy γ Source Radiation Field Dose Rate
对比项目名称 蒙卡计算 TORT计算 QADS计算 耦合计算（面1） 耦合计算（面2） 探测点1/(mSv·h−1) 3.86×10−2（±0.0019） 6.03×10−2 1.63×10−1 5.12×10−2 4.70×10−2 探测点2/(mSv·h−1) 1.08×10−2（±0.0006） 3.86×10−2 1.10×10−2 9.67×10−3 外表面平均/(mSv·h−1) 2.45×10−2（±0.0015） 3.82×10−2 1.38×10−1 4.38×10−2 3.91×10−2 计算时间 8 h 40 min 2 s 5 min 6 min
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表 3 高能γ源辐射场剂量率
Table 3. High Energy γ Source Radiation Field Dose Rate
对比项目名称 蒙卡计算 TORT计算 QADS计算 耦合计算（面1） 耦合计算（面2） 探测点1/（mSv·h−1） 8.84×102（±20.33） 1.52×103 1.04×103 8.84×102 6.99×102 探测点2/（mSv·h−1） 1.40×102（±4.34） 2.16×102 1.88×102 1.56×102 外表面平均/（mSv·h−1） 7.37×102（±5.16） 1.24×103 8.82×102 7.31×102 5.73×102 计算时间 10 h 1 h 2s 5 min 6 min
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