Abstract The thermal stratification phenomenon plays a crucial role in the safety of various nuclear systems, including the Gen-III + Light Water Reactors (LWR) and the Gen-IV reactors. The phenomenon is of particular importance for the pool-type Sodium-cooled Fast Reactors (SFRs) because it may cause neutronic and thermal-hydraulic instabilities in the reactor core, or lead to damages of both the reactor vessel and in-vessel components due to the growth of thermal fatigue cracking. More significantly, thermal stratification could impede the establishment of the natural circulation during accidental scenarios and introduce uncertainties to the core safety of SFRs. Efforts for modeling of the thermal stratification in SFRs have been made for decades to prevent or mitigate the damage caused by the phenomenon. This paper gives a review of the advances that have been made in recent 10 years on the computational modeling methods for thermal stratification phenomenon in SFRs. These methods can be generally drawn into two categories. The first one is the system-level methods which provide fast-running but approximate calculations, and the second one is the CFD methods which provide high-resolution calculations at high computational expense. After introducing the efforts that have been made to improve the one-dimensional (1-D) models, the paper envisioned the possible research directions that could be pursued to enhance the modeling of thermal stratification in the near future.

中文翻译：

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钠冷快堆热分层建模方法现状综述

摘要 热分层现象对包括第三代+轻水反应堆（LWR）和第四代反应堆在内的各种核系统的安全起着至关重要的作用。这种现象对于池式钠冷快堆（SFRs）尤为重要，因为它可能导致堆芯中子和热水力不稳定性，或由于以下原因导致反应堆容器和容器内部件的损坏。热疲劳裂纹的增长。更重要的是，热分层可能会在意外情况下阻碍自然循环的建立，并给 SFR 的核心安全带来不确定性。几十年来，人们一直在努力对恒星形成率中的热分层进行建模，以防止或减轻这种现象造成的损害。本文回顾了近 10 年来在恒星形成率中热分层现象的计算建模方法方面取得的进展。这些方法一般可以分为两类。第一个是系统级方法，提供快速运行但近似计算，第二个是 CFD 方法，以高计算成本提供高分辨率计算。在介绍了为改进一维 (1-D) 模型所做的努力之后，本文设想了可能的研究方向，以在不久的将来加强热分层建模。第一个是系统级方法，提供快速运行但近似计算，第二个是 CFD 方法，以高计算成本提供高分辨率计算。在介绍了为改进一维 (1-D) 模型所做的努力之后，本文设想了可能的研究方向，以在不久的将来加强热分层建模。第一个是系统级方法，提供快速运行但近似计算，第二个是 CFD 方法，以高计算成本提供高分辨率计算。在介绍了为改进一维 (1-D) 模型所做的努力之后，本文设想了可能的研究方向，以在不久的将来加强热分层建模。