Transient behaviors of plasma and in-vessel components when considering divertor plasma state transition in a fusion reactor

Transient behaviors of plasma and in-vessel components have been investigat ed considering the divertor plasma state (detached/attached) transition. Th e SAFALY code consisting of a zero-dimensional plasma model and a one-dimen sional heat transfer model of components has been modified to take account of the divertor plasma state transition on the basis of the updated diverto r plasma physics. Several plasma events, i.e., over fueling, sudden auxilia ry heating injection and confinement improvement events which would be expe cted to result in overpower, were selected for the International Thermonucl ear Experimental Reactor (ITER) and the transient behaviors were calculated on the assumption of a combined failure of plasma control and machine inte rlock in addition with a postulated plasma transient. The results show that plasma burning passively terminates due to sublimated impurity penetration from the carbon target surface, but there are possibilities of dry out of the coolant for the high heat flux in sudden attached slate transition unde r the multifailure of plasma control. However, effects Ly the aggravating f ailure of the divertor are expected to be safely terminated by the confinem ent boundary, the vacuum vessel and its pressure suppression system.