Pseudo-resonant-nuclide subgroup method capable to precisely treat spatial self-shielding effect
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摘要: 鉴于传统的Bondarenko迭代方法(BIM)处理共振干涉效应时会引入较大的误差,国际上发展了共振干涉因子方法(RIFM)和非均匀共振伪核素方法(HPRIM),但二者都只能通过考虑共振干涉效应给出较精确的燃料棒平均有效自屏截面,而不能精确考虑空间自屏效应而无法给出精确的空间相关的有效自屏截面。针对该问题,提出了共振伪核素子群方法(PRNSM)。该方法通过在线制作共振伪核素的共振截面表考虑共振干涉效应;通过拟合方法得到共振伪核素及其组成共振核素的子群参数;通过求解共振伪核素的子群固定源问题得到子群通量并用于归并组成共振核素的子群截面得到空间相关的有效自屏截面。大量的数值结果表明,对于不同富集度UO2燃料问题,PRNSM可精确给出棒平均有效自屏截面和空间相关的有效自屏截面。
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关键词:
- 共振干涉效应 /
- 空间相关有效自屏截面 /
- Bondarenko方法 /
- 共振干涉因子方法 /
- 共振伪核素方法 /
- 子群方法
Abstract: Considering that the conventional Bondarenko-Iteration Method (BIM) would introduce much error in treating resonance interference effect, the Resonance-Interference-Factor Method (RIFM) and the Heterogeneous-Pseudo-Resonant-Isotope Method (HPRIM) was developed by researchers. Though these two methods can give relatively precise pin-averaged self-shielded cross sections by considering resonance interference effect, they cannot give exact spatial dependent self-shielded cross sections for coarsely modeling spatial self-shielding effect. In order to overcome this problem, the Pseudo-Resonant-Nuclide Subgroup Method (PRNSM) is proposed in this paper. The PRNSM takes into account the resonance interference effect by making resonance cross section table of the pseudo resonant nuclide on-line. The subgroup parameters of the pseudo resonant nuclide and the partial resonant nuclide are obtained by fitting method. The spatial dependent self-shielded cross sections are obtained by condensing the subgroup cross sections of the partial resonant nuclide with the subgroup flux which is obtained by solving subgroup fixed source problem of the pseudo resonant nuclide. The numerous numerical results show that the PRNSM can give both precise pin-averaged self-shielded cross sections and precise spatial dependent self-shielded cross sections for UO2 problems with different enrichments.
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