Transient gasification in an NBG-18 coolant channel of a VHTR prismatic fuel element

► Investigated transient gasification of nuclear graphite NBG-18 in a coolant channel of a prismatic VHTR fuel element. ► Total graphite loss depends on initial graphite temperature and the air inlet temperature and Reynolds number. ► Released heat in the production of CO and CO2 gasses strongly accelerates graphite weight loss and cannot be ignored.