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Solving point burnup equations by Magnus method
Yun Cai,Xingjie Peng,Qing Li,Lin Du,Lingfang Yang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.4
The burnup equation of nuclides is one of the most equations in nuclear reactor physics, which isgenerally coupled with transport calculations. The burnup equation describes the variation of the nuclideswith time. Because of its very stiffness and the need for large time step, this equation is solved byspecial methods, for example transmutation trajectory analysis (TTA) or the matrix exponential methodswhere the matrix exponential is approximated by CRAM. However, TTA or CRAM functions well whenthe flux is constant. In this work, a new method is proposed when the flux changes. It's an improvedmethod compared to TTA or CRAM. Furtherly, this new method is based on TTA or CRAM, and it is moreaccurate than them. The accuracy and efficiency of this method are investigated. Several cases are usedand the results show the accuracy and efficiency of this method are great.
Analysis and comparison of the 2D/1D and quasi-3D methods with the direct transport code SHARK
Chen Zhao,Xingjie Peng,Hongbo Zhang,Wenbo Zhao,Qing Li,Zhang Chen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1
The 2D/1D method has become the mainstream of the direct transport calculation considering the balance of accuracy and efficiency. However, the 2D/1D method still suffers from stability issues. Recently, a quasi-3D method has been proposed with axial Legendre expansion. Analysis and comparison of the 2D/1D and quasi-3D method is conducted in theory from the equation derivation. Besides, the C5G7 benchmark, the KUCA benchmark and the macro BEAVRS benchmark are calculated to verify the theory comparisons of these two methods with the direct transport code SHARK. All results show that the quasi-3D method has better stability and accuracy than the 2D/1D method with worse efficiency and memory cost. It provides a new option for direct transport calculation with the quasi-3D method.
Hui Guo,Xingjie Peng,Yiwei Wu,Xin Jin,Kuaiyuan Feng,Hanyang Gu 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3
The small modular liquid-metal fast reactor (SMFR) is an important component of advanced nuclearsystems. SMFRs exhibit relatively low breeding capability and constraint space for control rod installation. Consequently, control rods are deeply inserted at beginning and are withdrawn gradually tocompensate for large burnup reactivity loss in a long lifetime. This paper is committed to investigatingthe impact of control rod compensation operation on core neutronics characteristics. This paper presentsa whole core fine depletion model of long lifetime SMFR using OpenMC and the influence of depletionchains is verified. Three control rod position schemes to simulate the compensation process arecompared. The results show that the fine simulation of the control rod compensation process impactssignificantly the fuel burnup distribution and absorber consumption. A control rod equivalent positionscheme proposed in this work is an optimal option in the trade-off between computation time andaccuracy. The control position is crucial for accurate power distribution and void feedback coefficients inSMFRs. The results in this paper also show that the pin level power distribution is important due to theheterogeneous distribution in SMFRs. The fuel burnup distribution at the end of core life impacts theworth of control rods.