Abstract The Advanced Lead Fast Reactor European Demonstrator (ALFRED) was conceived in the framework of the LEADER (Lead-cooled European Advanced DEmonstration Reactor) project since 2010. Recently, a revised concept of the Reactor Coolant System (RCS) is ongoing to solve some identified issues such as thermal stratification and others. To verify the improvements of the ALFRED design the authors developed a detailed nodalization scheme of the reactor using RELAP5-3D© code. This paper provides a summary of the main improvements introduced in the revised concept of ALFRED reactor and a detailed discussion of the thermal-hydraulic analysis performed with RELAP5-3D©. The nodalization scheme is described in detail together with transient boundary conditions and timing of events. The numerical activity demonstrates the improvements of the revised configuration of the reactor that avoid the establishment of relevant thermal stratification phenomena in both normal and accidental operations. The effect of two relevant parameters is also investigated, highlighting that safety conditions are maintained in the whole spectrum of the sensitivity analysis.

中文翻译：

---

停电条件下ALFRED修订概念的初步评估

摘要 自 2010 年以来，在 LEADER（铅冷却欧洲先进示范反应堆）项目的框架内构想了先进的铅快速反应堆欧洲示范装置（ALFRED）。最近，反应堆冷却剂系统（RCS）的修订概念正在进行中，以解决一些确定了诸如热分层等问题。为了验证 ALFRED 设计的改进，作者使用 RELAP5-3D© 代码开发了一个详细的反应堆节点化方案。本文概述了 ALFRED 反应器的修订概念中引入的主要改进，并详细讨论了使用 RELAP5-3D© 执行的热工水力分析。节点化方案与瞬态边界条件和事件时序一起详细描述。数值活动展示了反应堆修改配置的改进，避免在正常和意外运行中建立相关的热分层现象。还研究了两个相关参数的影响，强调在整个敏感性分析范围内都保持安全条件。