Demilitarisation entails handling of explosives and therefore involves a potential risk of unexpected energy release. Accidents have frequently occurred with fatal consequences throughout the history of demilitarisation. One useful tool for avoiding accidental explosions is computer codes to simulate static pressure in closed volumes. Furthermore; today it is also possible to simulate dynamic pressure changes (i.e. with space and time). This can be helpful when designing facilities for demilitarisation purposes to minimize the risk of human injuries. The paper presents simulations of pressure propagation from detonating PBXN-5 under different conditions.