Plant Units

The natech risk assessment methodology of RAPID-N is based on the estimation of damage probabilities of plant units located at industrial plants for a certain natural hazard scenario, and the calculation of distances to endpoints by using basic consequence modeling techniques. Hence, the focus is on proc-ess units and their physical characteristics, their structural behavior against the forces created by the natural hazards, and the substances stored or processed therein. Plant unit records are used to store information on plant units, including related properties and substances.

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

Table 1. Plant unit data fields

For each plant unit, the plant where the plant unit is located and the type of the plant unit should be specified. The plant can be selected from available plants in the database. If available, the code number of the plant unit (e.g. TK-201, S-60) can be indicated. The midpoint coordinate of the plant unit can be entered manually as latitude and longitude. Coordinate fields are linked to the map and updated automatically if the location of the plant unit is marked on the map. The boundary of the unit can also be drawn as polygon. For plant units having a circular shape (e.g. spherical tank, vertical cylindrical tank), the boundary is drawn using a circle instead of a polygon (Figure 1). If diameter prop-erty is available, it is linked to the circle and updated automatically by the system.

The substance stored in the plant unit can be specified by selecting the substance from the list of sub-stances available in the database. The amount and concentration of the substance stored in the plant unit can be indicated by using various parameters, such as stored quantity, stored volume, fill height, fill level, mass concentration, or volume concentration, which can be entered by using properties as ex-plained below.

The characteristics of the plant unit can be indicated by using the property definition framework of the system. Properties should be unique, but uncertain values of numerical properties can be specified by using fuzzy numbers. The system only lists properties valid for the selected plant unit type accord-ing to plant unit type settings. See "Plant Unit Types" section for more details. The availability of certain properties depends on the values of other properties. For example, the diameter property is not available if the shape is set as rectangular or the roof type property is available only for cylindrical verti-cal tanks under atmospheric storage conditions.