Benchmark analysis of in-vacuum vessel LOCA scenarios for code-to-code comparison

Computer modeling codes represent a crucial tool to support the design of future fusion plants. Since one of the most important functions that codes must achieve is assessing safety systems design, a verification and validation phase is required. In this framework, a code-to-code comparison among four codes has been carried within EUROfusion consortium between Safety Analyses and Environment and Balance of Plant work packages. In particular, an in-vessel Loss of Coolant Accident has been selected as a benchmark scenario for investigating thermal-hydraulic parameters of the vacuum vessel and its suppression system. This paper aims to compare the answer of different codes in terms of peak pressure within the vacuum vessel and its timing, the equilibrium pressure, and relief valve and rupture disk opening using a simplified thermal-hydraulic model of the EU-DEMO. In order to minimize the differences among the codes, the models have been kept to the simplest possible nodalization, successively increasing the model complexity