基于NECP-X的全局-局部耦合共振自屏计算方法研究

Research of Global-Local Resonance Self-Shielding Calculation Method Based on NECP-X

为应对高保真共振自屏计算所遇到的挑战,提出了全局-局部耦合共振自屏计算方法。将所有共振自屏效应及相关效应分为全局的效应和局部的效应2类,其中全局的效应较弱或者与能量无关,而局部的效应较为强烈。因此将共振自屏计算分为全局计算、耦合计算和局部计算3个步骤:全局计算建立粗糙模型,采用中子流方法计算丹可夫修正因子,处理全局的效应;耦合计算根据丹可夫修正因子守恒将待求解问题中的燃料棒等效成一维模型;局部计算采用较为精确的共振伪核素子群方法,处理局部的效应。基于NECP-X实现了该方法,数值结果表明,该方法在效率方面比传统方法提高至少一个量级,无限介质增殖因数的计算精度也提高了100~300 pcm。

To meet the challenges faced in high-fidelity resonance self-shielding calculations, the global-local self-shielding calculation method is proposed. The resonance self-shielding and correlated effects are classified into global and local effects. The global effects are weak or independent of energy, while the local effects are strong. Therefore, the resonance self-shielding calculation is split into global, coupling and local calculations. Coarse model is built for global calculation and the neutron current method is employed to compute Dancoff correction factors, where the global effects are considered. The coupling calculation is based on preservation of the Dancoff correction factors and the equivalent 1-D models of the fuel rods are obtained. The pseudo-resonant-nuclide subgroup method is employed to perform the local calculation to treat the local effects. This method is realized in NECP-X. The numerical results show that the efficiency of this method is increased by one order of magnitude compared with the conventional method. Besides, the precision of infinite medium multiplication factor is increased by 100-300 pcm.