A safety assessment method for plasma transients, including thermal response of in-vessel components, was provided. We developed a plasma physics model for safety analysis which has been implemented in a safety analysis code (SAFALY). The SAFALY code consists of a zero-dimensional plasma dynamics model and a 1.5-dimensional thermal behavior model of in-vessel components in the thickness direction. The code can treat hydraulic accidents using the results from a hydraulic code and analyze a passive plasma shutdown due to the impurity release from the wall. The abnormal events in the International Thermonuclear Experimental Reactor (ITER) calculated here are: (i) loss of plasma control, and (ii) large ex-vessel loss of coolant accident (LOCA) in the first wall and large ex-vessel LOCA in the divertor. The plasma transient and thermal response of in-vessel components in such events have been assessed using the code.