Simulation of severe accidents in sodium-cooled fast reactors using ASTRA code with a molten clad motion model

IF 2.3 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Annals of Nuclear Energy Pub Date : 2025-09-27 DOI:10.1016/j.anucene.2025.111894

Yadu Narendran, K. Natesan, A. John Arul, A. Jasmin Sudha

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Abstract

Accidents in sodium cooled fast reactors such as Unprotected Loss of Flow (ULOFA), and Total Instantaneous Blockage (TIB) involve coolant boiling and molten material motion inside the voided channel. Accurate modeling of molten clad dynamics is required to calculate transient power evolutions, fuel motion modeling, and transition and disassembly phase calculations. In the present study, a one dimensional molten clad motion model is developed. The model is validated with analytical calculations and benchmark experiment data. Integrating the clad motion model, TIB and ULOFA scenarios in a medium sized SFR is analyzed using the ASTRA code. The TIB analysis revealed that fast voiding resulted in rapid power rise and fuel melting. The coolant channel was blocked by the refrozen clad at the lower axial blanket. The parametric study showed that the heat generation rate affects the time of occurrence of key events such as sodium boiling, clad melting, fuel melting. The ULOFA analysis showed a gradual introduction of steel relocation feedback and a complete channel blockage at the top of the fissile region at the time of fuel melting. The parametric study showed that the heat generation rate is the most influential parameter that affects the time of occurrence of key events.

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用含熔包层运动模型的ASTRA代码模拟钠冷快堆严重事故

钠冷却快堆中的事故，如无保护失流（ULOFA）和完全瞬时阻塞（TIB），涉及冷却剂沸腾和熔融物质在空通道内运动。熔覆层动力学的精确建模需要计算瞬态功率演化、燃料运动建模以及过渡和拆卸阶段的计算。本文建立了熔覆层的一维运动模型。通过分析计算和基准实验数据对模型进行了验证。结合包层运动模型，利用ASTRA代码对中型SFR的TIB和ULOFA场景进行了分析。TIB分析显示，快速排空导致功率快速上升和燃料熔化。冷却剂通道被下轴向包层处的再冻结包层阻塞。参数化研究表明，产热速率影响着钠沸腾、包层熔化、燃料熔化等关键事件的发生时间。ULOFA分析表明，在燃料熔化时，在裂变区顶部逐渐引入钢重定位反馈和完全通道阻塞。参数化研究表明，产热率是影响关键事件发生时间的最重要参数。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Annals of Nuclear Energy 工程技术-核科学技术

CiteScore

4.30

自引率

21.10%

发文量

632

审稿时长

7.3 months

期刊介绍： Annals of Nuclear Energy provides an international medium for the communication of original research, ideas and developments in all areas of the field of nuclear energy science and technology. Its scope embraces nuclear fuel reserves, fuel cycles and cost, materials, processing, system and component technology (fission only), design and optimization, direct conversion of nuclear energy sources, environmental control, reactor physics, heat transfer and fluid dynamics, structural analysis, fuel management, future developments, nuclear fuel and safety, nuclear aerosol, neutron physics, computer technology (both software and hardware), risk assessment, radioactive waste disposal and reactor thermal hydraulics. Papers submitted to Annals need to demonstrate a clear link to nuclear power generation/nuclear engineering. Papers which deal with pure nuclear physics, pure health physics, imaging, or attenuation and shielding properties of concretes and various geological materials are not within the scope of the journal. Also, papers that deal with policy or economics are not within the scope of the journal.