The development of the risk can be described as a logical sequence: violation of the technological process, the allowed range of operation, conditions of detention, etc. -- > education, the accumulation of factors leading to crash the technical systems --> the destruction of the structure --> the release, education factors affecting the --> effect (interaction) of factors affecting the property impact (with the natural environment, man, technosphere objects, etc.) -- > the response to the damaging effects. Depending on the characteristics of the technical system the individual elements of a given chain may be missing. Each such event can be attributed to private indicator-probability event: the probability of failure of the technical system --> probability of emergency outcome --> the probability of formation of destructive factors --> the probability of impact of objects --> probability of secondary damaging factors --> effects --> the chances of failure.
From the above logical sequence, follows that the presence of potential danger in the system is not always accompanied by its negative impact on the object. Any exception in the chain leading to non-realization of the danger.
For the realization of the danger, you need to meet at least three conditions:
the danger really is valid (present);
the property is situated in the zone of danger;
the object does not have sufficient protection.