Accident analysis with MELCOR-fusion code for DONES lithium loop and accelerator.

• Deterministic Accident Analysis for DONES licensing are performed with MELCOR fusion version. • Lithium Loop and Accelerator models are developed for relevant scenarios. • Candidate safety systems, requirements and metrics under control are identified. • First scenario: beam shutdown and margin to lithium disappearance are addressed. • Second scenario: fast isolation valve and water reaching the target are addressed. Safety assessment is a key issue for the licensing of DONES facility, the DEMO-Oriented Neutron Source. A first phase of the safety assessment includes Failure Mode Analyses of systems to identify postulated initiating events (PIEs), while deterministic accident analyses are lately performed to estimate source terms in radiological hazards. In addition, the deterministic analyses are also the basis to identify safety class structures, systems and components, and to establish the operational range of system parameters as well as the actuation of the protection system. In this paper two accident scenarios, previously identified as PIEs, are explored with the fusion version of the MELCOR 1.8.6 code. A loss of flow (LOFA) in the lithium loop due to the trip of the electromagnetic pump and a loss of vacuum (LOVA) in the accelerator beam duct due to containment rupture have been studied to provide a preliminary estimation of the available actuation time for detection and mitigation systems with a particular focus on the beam shutdown system and isolation of the vacuum duct. [ABSTRACT FROM AUTHOR]