The German PNP program

Existing safety margins of modem nuclear containments guarantee a safe enclosure. 3.5.2. The German PNP Program 

The PNP safety program [41] focused on the formation and explosion of clouds of the process gases H2, CO, air and other representative combustible gases such as acetylene, ethylene, propane, methane, and the damage caused by the blast wave to simple structural elements (window pane, brick wall) after fast deflagration and detonation. Areas of investigations were 

Tasks within the study were dealing with deflagration damage analysis, mechanisms of combustion, regulations and limits comprising subtasks about 

Experimental studies within the PNP gas cloud program were conducted and evaluated by the Fraunhofer Institute for Chemical Technology using flammable mixtures of hydrogen and other fuels with air in different shapes (sphere, hemisphere, tube), confined or unconfined. They are described in more detail in section 8.5.2. Experimental results from other test programs in the USA (explosion series in FLAME ) or Norway (jet ignition with transition to detonation in acetylene-air mixtures) were also taken into account. All tests were close to the go - no go boundary between deflagration and detonation. 

An overall statement concerning the deflagration - detonation transition (DDT) was made within the frame of the PNP gas cloud program saying that the mechanisms and flame acceleration are qualitatively understood, however, they cannot be described on a quantitative basis, a statement that is, in principle, still valid today [6, 30, 41], although computational efforts are progressing tremendously. 

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