基于MCNP多群伴随计算与正算分析的比较
Comparison Research and Analysis of Multigroup Adjoint Calculation and Forward Calculation Based on MCNP
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摘要: 为研究MCNP伴随计算与正算的一致性及其差异， 利用3个模型作为算例进行比较计算， 并对其结果进行分析。 模型I的计算结果表明， 伴随计算与正算结果基本一致， 而且伴随计算的FOM值大约为正算的2倍左右； 模型Ⅱ研究了伴随计算对不同材料的适用性， 结果显示， 在散射截面较大的情况下， 伴随计算的通量与正算通量的差异在20%左右， 而且正算的FOM值比伴随计算的大； 模型Ⅲ研究了伴随在产生重要函数中的应用， 并与权窗进行比较， 经分析， 虽然它们产生重要函数的机制不同， 但所得函数的性质基本相同， 而且使用伴随重要函数的FOM值大约是使用权窗的1.5倍。 In order to investigate the agreement and difference between adjoint and forward calculations with Monte Carlo method， three models have been simulated， and the calculated results are compared and analyzed. First， the comparison shows that the calculated results of the adjoint calculation are basically consistent with those of the forward calculation in modelⅠ. The FOM value of adjoint calculation is about two times of the value of forward calculation. Second， it is investigated with modelⅡ that the applicability of the adjoint calculation for the different materials， and the results show that the difference is about 20% for the case of strong scattering between the adjoint calculation and forward calculation. The FOM value of the forward calculation is larger than that of the adjoint calculation. Finally， the important function is generated by the adjoint calculation in model Ⅲ， and the results are compared with ones of the weight window game. Although their important functions are produced by different mechanisms， the values of functions are in agreement with each other， and the FOM value of ajoint calculation is about 1.5 times of the value from the weight windows.Abstract: In order to investigate the agreement and difference between adjoint and forward calculations with Monte Carlo method， three models have been simulated， and the calculated results are compared and analyzed. First， the comparison shows that the calculated results of the adjoint calculation are basically consistent with those of the forward calculation in modelⅠ. The FOM value of adjoint calculation is about two times of the value of forward calculation. Second， it is investigated with modelⅡ that the applicability of the adjoint calculation for the different materials， and the results show that the difference is about 20% for the case of strong scattering between the adjoint calculation and forward calculation. The FOM value of the forward calculation is larger than that of the adjoint calculation. Finally， the important function is generated by the adjoint calculation in model Ⅲ， and the results are compared with ones of the weight window game. Although their important functions are produced by different mechanisms， the values of functions are in agreement with each other， and the FOM value of ajoint calculation is about 1.5 times of the value from the weight windows.
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