Formal–statistical methods - Probabilistic Safety Assessment for Optimum Nuclear Power Plant Life Management (PLiM) - page 64

The next stage of risk analysis is the identification of hazards. The main
task is to identify (based on information about the object, examination
results and experience with similar systems) and describe accurately all
the hazards inherent in the system. This is a crucial stage of analysis since
the hazards undetected at this stage are not subject to further consideration
and disappear from sight.
There are a number of formal methods of identifying hazards which are
discussed below. Here is a preliminary assessment of hazards in order to
select further activities:
• To stop further analysis because of low risk;
• A more detailed analysis of risk;
• Develop recommendations to reduce hazards.
Baseline data and the results of preliminary hazard assessment should
also be properly documented. In principle, the process of risk analysis can
already be terminated at the stage of hazard identification.
If necessary, after identifying the hazards we can transfer to the stage
of risk assessment.
The final stage in risk analysis of technological systems is the
formulation of recommendations for reducing the level of risk (risk
management) if the level of risk is higher than acceptable.
In this type of work all the regulations prescribe the preparation of a
report, with the requirements on the content of the report strictly defined
and relating to the above questions.
The plurality of analysis results and the possibility of compromise
solutions give reason to believe that risk analysis is not a strictly scientific
process, verifiable by objective scientific methods.
Risk analysis is closely related to another process - risk assessment.
Risk assessment is the process used to determine the value (measures)
of the analyzed risk of danger to human health, property, environment
and other situations associated with the hazards. Risk assessment is an
indispensable part of the analysis. Risk assessment includes an analysis of
frequency, impact analysis and combinations thereof.
The English literature uses the terms 'risk estimation', 'risk assessment',
'risk evaluation', which often have different meaning but are translated as
risk assessment.
Risk assessment is the stage at which the identified risk must be
evaluated on the basis of the criteria of acceptable risk in order to identify
hazards with an unacceptable level of risk, and this step will be the basis
for the formulation of recommendations and measures to reduce hazards. In
this case, both the criteria of acceptable risk and risk assessment can be
expressed both qualitatively and quantitatively.
By definition, risk assessment includes an analysis of the frequency and
impact analysis. However, when the effects are negligible and the frequency
is very low, it suffices to estimate one parameter.
Several different approaches to risk assessment will be discussed:

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