Abstract

The objective of the present study is to show that it is feasible to establish the breed-and-burn (B&B) mode of operation with rotational fuel shuffling in the S-PRISM core based on neutronic and thermal-hydraulic analyses. The results quantified the impact of major core design choices on the criticality of a core that uses sodium as a coolant material and HT9 steel as structural material. The design variables examined include the binary metallic fuel U-Zr with different weight percentages of zirconium as well as different core heights and fuel rod pitch-to-diameter ratios (P/Ds) in the fuel assembly. We found that a core using the binary metallic fuel U-Zr with 2 wt% zirconium, with a core height of 200 cm, a P/D of 1.086, and a core power of 400 MW(thermal), could overcome some major design constraints.

It was also found that with shuffling intervals of 1125 to 1250 days, the core with rotational fuel shuffling was critical in the equilibrium state, and the possible average discharged burnup was from 274.8 to 305.3 GWd/ton HM. Reactor characteristics such as neutron flux and power profile were almost stable during the equilibrium cycle. A steady-state thermal-hydraulic analysis was performed for the hottest channel in the core. It revealed that both the fuel and cladding maximum temperatures were less than the melting point of the fuel and the chemical interaction temperature of the HT-9, respectively. The mixed coolant outlet temperature was somewhat below the temperature usually observed in sodium-cooled fast reactors. Thus, it appears that the S-PRISM can be principally designed to have a B&B core.

摘要

本研究的目的是表明在 S-PRISM 堆芯中基于中子和热工水力分析建立具有旋转燃料改组的增殖和燃烧 (B&B) 运行模式是可行的。结果量化了主要堆芯设计选择对使用钠作为冷却剂材料和 HT9 钢作为结构材料的堆芯临界性的影响。检查的设计变量包括具有不同锆重量百分比的二元金属燃料 U-Zr，以及燃料组件中不同的堆芯高度和燃料棒节径比 (P/D)。我们发现使用含 2 wt% 锆的二元金属燃料 U-Zr 的堆芯，堆芯高度为 200 cm，P/D 为 1.086，堆芯功率为 400 MW（热），可以克服一些主要设计约束。

还发现，在 1125 至 1250 天的改组间隔下，具有旋转燃料改组的堆芯在平衡状态下至关重要，可能的平均排放燃耗为 274.8 至 305.3 GWd/ton HM。在平衡循环期间，中子通量和功率分布等反应堆特性几乎稳定。对岩心中最热的通道进行了稳态热工水力分析。结果表明，燃料和包壳的最高温度分别低于燃料的熔点和 HT-9 的化学相互作用温度。混合冷却剂出口温度略低于钠冷快堆中通常观察到的温度。因此，似乎 S-PRISM 可以主要设计为具有 B&B 核心。