**2. Risk assessment methodology**

In conducting risk analysis studies, reference benchmarks (indicators or indices) that can be used at different levels are required. It is obvious that the risk cannot be reduced to zero and therefore it appears as a value of the maximum importance to be the limit that can be borne by people in current activities.

Accident prevention through risk analysis involves a specific activity starting from the design stage through the application of qualitative and quantitative techniques and methods based on existing data and on systematic creative imaginative actions ([9], pp. 88–93).

The qualitative analysis has as a main objective the establishment of the list of possible hazards, and it makes possible the hierarchy of the events in the order of the risk and presents the first step in the methodology of performing the quantitative risk analysis.

There are two major categories of techniques in which a number of general components are distinguished (**Table 1**):


The order of application is from qualitative identification to quantitative analysis.


**2.2 Analysis of production probability**

*DOI: http://dx.doi.org/10.5772/intechopen.91020*

probability level of the analysed event is calculated [14].

different variants (**Table 3**).

*Risk of Slipping Industrial Landfills*

*2.2.1 Qualitative risk assessment*

to the analysed accident scenario.

in a matrix (**Figure 2**).

above level 15.

**Table 3.**

**Figure 2.**

**17**

It is also achieved using the five levels, internationally accepted and used in

The level of risk as a product between the severity level (consequence) and the

Using the information obtained from the analysis, the risk of an event is placed

The extent of the risk analysis and the intensity of the prevention and mitigation

Those accident scenarios are analyzed more thoroughly which, as a result of the qualitative analysis, are considered as potentially major, probabilities over 10<sup>6</sup>

, i.e.,

measures should be proportional to the risk involved. Simple models of hazard identification and qualitative risk analysis are not always enough and therefore it is necessary to use detailed assessments. There are several methods for performing quantitative risk assessment [15]. The choice of a particular technique is particular

they can occur earlier than 10,000 years and major consequences, so high risk

1 Rarely Only in exceptional conditions Probability of occurrence in 1012 years 2 Unlikely It could sometimes occur Probability of occurrence between 108 and

3 Possibly It may sometimes occur Probability of occurrence between 106 and

4 Probably It can occur in most situations Probability of occurrence between 104 and

1012 years

108 years

106 years

than 104 years

Probability of occurrence in a period less

**Crt. No. Probability When can occur Occurrence frequency**

5 Certainly It is expected to happen in most situations

*Levels of the probability of producing risks.*

*The matrix of qualitative risk assessment and risk levels.*

#### **Table 1.**

*Difference between Hazop and Hazan.*
