What does the probability of ignition being assumed to be 100% signify in risk analysis?

In risk analysis, particularly when utilizing Layer of Protection Analysis (LOPA), assuming a probability of ignition at 100% signifies that it is a standard approach for analyzing scenarios where ignition could potentially occur. This assumption is made to simplify the risk assessment and ensure that all possible ignition scenarios are evaluated under the worst-case conditions. By treating ignition probabilities as certain, analysts can concentrate on assessing the effectiveness of various layers of protection, like safety measures or engineered controls, to evaluate their ability to mitigate the risk associated with ignition events.

This approach is useful for understanding the consequences of incidents and for determining what risk reduction measures need to be in place. It provides a clear focus for evaluating the reliability of protection layers at various stages of the process, as the risk assessment is based on the premise that an ignition event is inevitable under the defined circumstances. This framework allows for a thorough examination of the safety system and its capacity to prevent or mitigate an adverse event.