That said, however, it should be noted that this polemic distinction between safe fail and fail-safe does not work on most explications of ‘fail-safe’ in the literature, since those explications of ‘fail-safe’ would rightly be interpreted as referring to safe fail rather than fail-safe. Thus, both terms would refer to the same practices.
Hammer [2, p. 115], for example, says: ‘‘Fail-safe design tries to ensure that a failure will leave the product unaffected or will convert it to a state in which no injury or damage will occur.’’
Similarly, the IAEA [1, p. 9] states that ‘‘the principle of ‘fail-safe’ should be incorporated [y] i.e. if a system or component should fail the plant should pass into a safe state’’.
Rather, the distinction seems to be one of perspective; for any level of a system/component, we may ask whether it will fail as well as whether its failure will result in danger beyond the system/component (e.g., harm to humans).
Using the concept of safe fail means ultimately focusing on the latter question. We will therefore use this term to cover the entire spectrum including the latter concern of being safe when the system fails.