This standard provides criteria for the analysis of subcompartment pressure@ temperature@ and flooding transients resulting from high- or moderateenergy line breaks and other events both inside and outside light water reactor primary containments. Criteria are provided for the determination of mass and energy release rates and for the formulation of input parameters to assure a conservative - subcompartment or building design basis. Attention is given to the intended use of the transient data. Interfaces with active and passive systems such as valves and structural heat sinks are treated. The qualification of equipment and design of their supports is also addressed through treatment of long-term pressure and temperature transients and also asymmetric pressure loading and its effects.