Abstract In this early development phase of the DEMO design the uncertainty affecting many operational and design parameters can modify main outcomes of accident scenario aiming at studying the critical conditions for the vacuum vessel and the contiguous containment volumes. The aim of this paper is to perform a preliminary sensitivity analysis of an accident progression predicted by MELCOR code considering selected parameters as a figure of merit to predict possible code outcomes. The uncertainty band will be evaluated through sensitivity analyses programmed, collected and statistically manipulated through RAVEN software tool. MELCOR and RAVEN have been internally coupled through a new Python code interface developed by Sapienza University of Rome, to perform sensitivity and uncertainty quantification analyses during severe accident transient. The Beyond Design Basis Accident (BDBA) analysis of an ex-vessel loss of coolant accident (LOCA) for the water-cooled lithium lead (WCLL) blanket concept has been simulated with the fusion version of MELCOR 1.8.6 code. The postulated initiating event (PIE) is a double-ended break in the first wall (FW) cooling system distributor ring, with simultaneous failure of the plasma shutdown system. An in-vessel breach of the coolant system occurs because of FW failure, with consequent unmitigated plasma shutdown transient. Sensitivity analysis results have shown that the FW temperature at which plasma in-vessel breach occurs is strongly correlated with the mass of hydrogen produced. The same parameter has also an impact on the overall accident scenario, such as the trigger of VVPSS rupture disks and thus source term mobilization.

中文翻译：

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欧盟 DEMO WCLL 毯概念的无等离子体关闭的船外 LOCA 的初步敏感性分析

摘要 在 DEMO 设计的这个早期开发阶段，影响许多操作和设计参数的不确定性可以修改事故情景的主要结果，旨在研究真空容器和连续安全壳的临界条件。本文的目的是对 MELCOR 规范预测的事故进展进行初步敏感性分析，将选定的参数作为预测可能规范结果的品质因数。不确定性带将通过编程、收集和统计操作的灵敏度分析进行评估，这些分析通过 RAVEN 软件工具进行。MELCOR 和 RAVEN 已通过罗马 Sapienza 大学开发的新 Python 代码接口进行内部耦合，以在严重事故瞬态期间执行灵敏度和不确定性量化分析。已使用 MELCOR 1.8.6 代码的融合版本对水冷锂铅 (WCLL) 毯概念的前船冷却剂损失事故 (LOCA) 的超设计基础事故 (BDBA) 分析进行了模拟。假定的起始事件 (PIE) 是第一壁 (FW) 冷却系统分配环中的双端断裂，同时等离子体关闭系统发生故障。由于 FW 故障，冷却剂系统在容器内发生故障，从而导致等离子体关闭瞬态无法缓解。灵敏度分析结果表明，发生等离子体容器内破裂的 FW 温度与产生的氢气质量密切相关。相同的参数也会对整个事故情景产生影响，例如 VVPSS 爆破片的触发以及源项动员。