1. Introducing the LOPA method

1.1 Method objective

The LOPA method is a semi-quantitative method developed with a view to :

• assess the adequacy between the barriers implemented and the level of risk targeted;

• determine the need for new barriers;

• define the minimum "requirements" for the probability of failure of the barriers to be put in place in the event that the existing barriers are unable to justify an acceptable risk;

• assess the residual frequency of occurrence of an accident scenario.