DEMO reactor aims to demonstrate the feasibility of electrical energy production from nuclear fusion source in a tokamak configuration. Within the DEMO pre-conceptual design assessment, the water-cooled lithium lead (WCLL) and helium-cooled pebble bed (HCPB) concepts were selected as Breeding Blanket (BB) candidates. Along the research pathway toward blanket selection, safety analyses of these two options were performed using selected postulated initiating events (PIEs) as reference scenarios. For the WCLL BB, the out-vessel loss of liquid metal was identified as a major safety concern. This paper presents a numerical analysis of this postulated accidental scenario, carried out adopting MELCOR code. Large rupture (double-ended 200%) and leak (5%), occurring at two different positions (middle and bottom) of lithium-lead (LiPb) Cold Leg (CL) in both the inboard (IB) and outboard (OB) loop, were simulated implementing a detailed MELCOR nodalisation. The exothermic reactions of LiPb with air and steam present in the DEMO building were evaluated, adopting an in-house conservative numerical model, since only pure lithium-air/steam chemical reactions are available in the default MELCOR version. The LiPb mass flow rate discharged into the building was evaluated along with the LiPb volume transients in the hot and cold leg and segments of both the IB and OB loops. The time-dependent mass evolution of the reactants and products involved in the LiPb-air/steam chemical reactions was also calculated. Moreover, the increase in temperature and pressure within the considered building volume due to the energy released is shown. These numerical analyses do not implement safety or mitigation functions and the results presented should be considered highly conservative.

• Manufacturing of the centrifuge has reached the Factory Acceptance Test stage. • Dynamic, seismic and leak tests passed. • Issues were detected during the endurance test at feedthrough temperature. Part of the Broader Approach, JT-60SA was established as satellite experiment supporting ITER and paving the way for a future fusion power plant. Its research plan calls for a powerful Pellet Launching System (PLS), capable for both particle fuelling and ELM pacing. These different tasks are achieved simultaneously by combining a pellet source for each purpose on a centrifuge. This stop cylinder type centrifuge provides dedicated pellet launch slots, which can be filled by the pellet sources controlled by a master programmable logic control (MasterPLC) system. Previously, centrifuges like those used at ASDEX Upgrade and JET were built by modifying a large turbomolecular pump and adding an acceleration arm. The advanced novel system reported here takes an approach that separates the drive from the arm. A ferrofluidic rotary motion feedthrough, capable of speeds up to 166 Hz, transfers the rotary motion from a commercial servomotor operating in the atmosphere to a rotor blade in the high vacuum. This system is designed to launch pellets with a velocity of up to 600 m/s when the centrifuge is rotating at 120 Hz. The factory acceptance test has almost been passed. After passing the endurance test, the system will be delivered to IPP Garching, followed by a commissioning phase in the pellet lab.

• A decoupled beam stability control method for gyrotron long-pulse operation. • Dynamically regulate filament power via PI control to stabilize beam current. • Modular design decouples DAQ, feedback, and beam control for robustness. • Enhance output power stability in ECRH systems without pre-installed feedback. Gyrotrons are widely used in ECRH (Electron Cyclotron Resonance Heating) systems for plasma heating in nuclear fusion experimental devices. Due to the radiation cooling effect of the gyrotron electron gun, the beam current gradually decreases during long-pulse operation, leading to unstable output power. This paper presents a long-pulse gyrotron beam current control method that regulates the beam current by adjusting the filament power supply, thereby stabilizing the gyrotron output power. The method comprises three decoupled modules: data acquisition, feedback control, and filament power control. Data acquisition is implemented via PXI, feedback control adopts a PI (Proportional-Integral) algorithm, and filament power control is realized through SCPI (Standard Commands for Programmable Instruments) over Ethernet. This approach enhances output power stability and is particularly suitable for ECRH systems without pre-installed beam current feedback mechanisms.