Typical Plant Units

For the estimation of natech risks, RAPID-N requires plant unit data, which can be entered as plant unit or plant unit group records. However, plant unit data may not be available for every plant. Especially for regional studies, it is quite common to have only the plant information with some indica-tors such as industrial activity and production capacity, but without specific details about plant units. Since having only a very rough estimate of damage and consequence probabilities is better than having no information, RAPID-N tries to estimate which kind of plant units may be present at such plants and conducts the risk assessment accordingly. Representative plant units are called typical plant units and can be industrial activity and plant property dependent. Typical plant unit records are used to store information on typical plant units, including related substance, properties and validity conditions.

The data fields of the typical plant unit records are listed in Table 1.

Table 1. Typical plant unit data fields

Similar to plant units, for each typical plant unit the type of the plant unit should be specified. A descriptive code number (e.g. TPU-001) can be indicated. The substance stored in the typical plant unit can be specified by selecting the substance from the list of substances available in the database. The characteristics of the typical plant unit, including amount and concentration of the substance stored, can be indicated by using the property definition framework of the system (Figure 1). Properties should be unique. Uncertain values of numerical properties can be specified by using fuzzy numbers. The system only lists properties valid for the selected plant unit type according to plant unit type settings. See "Plant Unit Types" section for more details. For each typical plant unit, the industrial activities for which the typical plant unit is valid can be indicated. The system allows selection of mul-tiple industrial activities. If no industrial activity is selected, the typical plant unit is assumed to be valid for all plants.

Similar to the property estimators, validity conditions can be specified for typical plant units. Plant properties are used as condition properties. Hence, a typical plant unit can be defined for plants with specific production capacities or construction dates after a certain year (Figure 1). See "Property Estimators" section for more details on the definition and evaluation of validity conditions.