3. Identify the different types of MMR

Until a few years ago, the semantics used to characterize MMR were relatively "poor" and could lead to confusion. The only distinction made was that between preventive and protective measures, among which coexisted :

• active, requiring an external source of activation to perform their safety function;

• passive, requiring no external power source to perform their safety function;

• organizational, based on human intervention or action.

In its OMEGA 10 report (see Bibliography section, Assessment of engineered safety barriers), INERIS suggests using the breakdown shown in the figure "Characterization of risk control measures according to INERIS" for the purpose of characterizing MMRs.