Abstract The CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy production) reactor concept was proposed to overcome the disadvantages of current reactor technologies. In this study, a Monte Carlo–based procedure is developed for quantitative comparison of burnup performance and neutronic characteristics between lead bismuth eutectic (LBE)–cooled and sodium-cooled CANDLE reactors to demonstrate the possibility of using sodium coolant in a small CANDLE burning reactor. In this procedure, a neutron transport equation is solved using the MVP code with the JENDL-4.0 library, and the burnup calculation is solved using the MVP-BURN code with the detailed burnup chain. To simulate the fuel-shuffling process, an auxiliary code was developed using Python. The results show that for the same fuel pin design and core volume, changing the coolant from LBE to sodium reduced the keff by 2.3% and the average discharge burnup by 15.6%, due to the softer neutron spectrum and larger neutron leakage fraction. It would be necessary to increase the fuel volume and core radius approximately 38% and 17%, respectively, for criticality in a sodium-cooled CANDLE core.

中文翻译：

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使用钠冷却剂的蜡烛燃烧反应器的燃耗性能

摘要 为了克服当前反应堆技术的缺点，提出了 CANDLE（能源生产寿命期间中子通量、核素密度和功率形状的恒定轴向形状）反应堆概念。在这项研究中，开发了一种基于蒙特卡罗的程序，用于定量比较铅铋共晶 (LBE) 冷却和钠冷却 CANDLE 反应堆之间的燃耗性能和中子特性，以证明在小型 CANDLE 燃烧反应堆中使用钠冷却剂的可能性. 在此过程中，使用带有 JENDL-4.0 库的 MVP 代码求解中子输运方程，并使用带有详细燃耗链的 MVP-BURN 代码求解燃耗计算。为了模拟燃料改组过程，使用 Python 开发了辅助代码。结果表明，对于相同的燃料棒设计和堆芯体积，将冷却剂从 LBE 改为钠，由于更软的中子谱和更大的中子泄漏分数，keff 降低了 2.3%，平均放电燃耗降低了 15.6%。对于钠冷 CANDLE 堆芯的临界状态，有必要将燃料体积和堆芯半径分别增加约 38% 和 17%。